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Sample records for high energy ct

  1. High-energy x-ray CT and its application for digital engineering

    International Nuclear Information System (INIS)

    Kamimura, H.; Sadaoka, N.

    2005-01-01

    A high-energy x-ray computed tomography system and x-ray CT data handling software have been developed for digital engineering; internal dimension measurement, density analysis, actual and designed shape comparison, STL file generation, and support for reverse engineering and rapid prototyping. The system is designed to collect accurate images in short scanning time (10 s per section) using a MeV-energy electron linear accelerator and highly sensitive semiconductor detectors in order to scan large objects made of aluminum and/or iron. An excellent environment in digital engineering is provided by the software products; 'StereoCooker' for 3D bitmap CAD (rendering, feature extraction, dimensional measurement, and shape comparison, etc.), 'FeatureMaker' for translating bitmap CT data to CAD data including feature information, and 'Wingware' for realizing an Windows PC cluster system 'WINGluster' to apply CT data analysis. (author)

  2. Design of scanning motion control system for high-energy X-ray industrial CT

    International Nuclear Information System (INIS)

    Duan Liming

    2008-01-01

    A scanning motion control system was developed for the high-energy X-ray industrial computerized tomography (CT). The system consists of an industrial control computer, a counter card, a control card, servo drivers, servo motors, working platforms, gratings and control software. Based on windows driver model(WDM) mode, the composition of the driver pro- gram for the system was studied. Took the motor control card as an example, the method to develop the driver program was researched, and the intercourse process between the device driver program and the user-program was analyzed. The real-time control of the system was implemented using the WDM driver. The real-time performance and reliability of the system can satisfy the requirement of high-energy X-ray industrial CT. (authors)

  3. The effect of intravenous contrast on SUV value in 18F-FDG PET/CT using diagnostic high energy CT

    International Nuclear Information System (INIS)

    Jeong, Young Jin; Kang, Do Young

    2006-01-01

    According to the development of CT scanner in PET/CT system, the role of CT unit as a diagnostic tool has been more important. To improve the diagnostic ability of CT scanner, it is a key aspect that CT scanning has to be performed with high dose energy and intravenous (IV) contrast. So we investigated the effect of IV contrast media on the maximum SUV (maxSUV) of normal tissues and pathologic lesions using PET/CT scanner with high dose CT scanning. The study enrolled 13 patients who required PET/CT evaluation. At first, the patients were performed whole body non-contrast CT (NCCT - 120 kVp, 130 mAs) scan. Than contrast enhanced CT (CECT) scan was performed immediately. Finally PET scan was followed. The PET emission data were reconstructed twice, once with the NCCT and again with the CECT. We measured the maxSUV of 10 different body regions that were considered as normal in all patients. Also pathologic lesions were investigated. There were not seen focal artifacts in PET images based on CT with IV contrast agent. Firstly, 130 normal regions in 13 patients were evaluated. The maxSUV was significantly different between two PET images (p < 0.001). The maxSUV was 1.1 ± 0.5 in PET images with CECT-corrected attenuation and 1.0 ± 0.5 in PET images with NCCT-corrected attenuation. The limit of agreement was 0.1 ± 0.3 in Bland-Altman analysis. Especially there were significant differences in 6 of 10 regions, apex and base of the right lung, ascending aorta, segment 6 and segment 8 of the liver and spleen (p <0.05). Secondly, 39 pathologic lesions were evaluated. The maxSUV was significantly different between two PET images (p < 0.001). The maxSUV was 4.7 ± 2.0 in PET images with CECT-corrected attenuation and 4.4 ± 2.0 in PET images with NCCT- corrected attenuation. The limit of agreement was 0.4 ± 0.8 in Bland-Altman analysis. Although there were increases of maxSUVs in the PET images based on CT with IV contrast agent, it was very narrow in the range of limit of

  4. Differentiation of urinary calculi with dual energy CT: effect of spectral shaping by high energy tin filtration.

    Science.gov (United States)

    Thomas, Christoph; Krauss, Bernhard; Ketelsen, Dominik; Tsiflikas, Ilias; Reimann, Anja; Werner, Matthias; Schilling, David; Hennenlotter, Jörg; Claussen, Claus D; Schlemmer, Heinz-Peter; Heuschmid, Martin

    2010-07-01

    In dual energy (DE) computed tomography (CT), spectral shaping by additional filtration of the high energy spectrum can theoretically improve dual energy contrast. The aim of this in vitro study was to examine the influence of an additional tin filter for the differentiation of human urinary calculi by dual energy CT. A total of 36 pure human urinary calculi (uric acid, cystine, calciumoxalate monohydrate, calciumoxalate dihydrate, carbonatapatite, brushite, average diameter 10.5 mm) were placed in a phantom and imaged with 2 dual source CT scanners. One scanner was equipped with an additional tin (Sn) filter. Different combinations of tube voltages (140/80 kV, 140/100 kV, Sn140/100 kV, Sn140/80 kV, with Sn140 referring to 140 kV with the tin filter) were applied. Tube currents were adapted to yield comparable dose indices. Low- and high energy images were reconstructed. The calculi were segmented semiautomatically in the datasets and DE ratios (attenuation@low_kV/attenuation@high_kV) and were calculated for each calculus. DE contrasts (DE-ratio_material1/DE-ratio_material2) were computed for uric acid, cystine and calcified calculi and compared between the combinations of tube voltages. Using exclusively DE ratios, all uric acid, cystine and calcified calculi (as a group) could be differentiated in all protocols; the calcified calculi could not be differentiated among each other in any examination protocol. The highest DE ratios and DE contrasts were measured for the Sn140/80 protocol (53%-62% higher DE contrast than in the 140/80 kV protocol without additional filtration). The DE ratios and DE contrasts of the 80/140 kV and 100/Sn140 kV protocols were comparable. Uric acid, cystine and calcified calculi could be reliably differentiated by any of the protocols. A dose-neutral gain of DE contrast was found in the Sn-filter protocols, which might improve the differentiation of smaller calculi (Sn140/80 kV) and improve image quality and calculi differentiation in

  5. Cross-sectional imaging of large and dense materials by high energy X-ray CT using linear accelerator

    International Nuclear Information System (INIS)

    Kanamori, Takahiro; Kamata, Shouji; Ito, Shinichi.

    1989-01-01

    A prototype high energy X-ray CT (computed tomography) system has been developed which employs a linear accelerator as the X-ray source (max. photon energy: 12 MeV). One problem encountered in development of this CT system was to reduce the scattered photons from adjacent detectors, i.e. crosstalk, due to high energy X-rays. This crosstalk was reduced to 2% by means of detector shields using tungsten spacers. Spatial resolution was not affected by such small crosstalk as confirmed by numerical simulations. A second problem was to reduce the scattered photons from the test object. This was done using collimators. A third concern was to realize a wide dynamic range data processing which would allow applications to large and dense objects. This problem was solved by using a sample and hold data acquisition method to reduce the dark current of the photo detectors. The dynamic range of this system was experimentally confirmed over 60 dB. It was demonstrated that slits (width: 2 mm) in an iron object (diameter: 25 cm) could be imaged by this prototype CT system. (author)

  6. Dual energy cardiac CT.

    Science.gov (United States)

    Carrascosa, Patricia; Deviggiano, Alejandro; Rodriguez-Granillo, Gastón

    2017-06-01

    Conventional single energy CT suffers from technical limitations related to the polychromatic nature of X-rays. Dual energy cardiac CT (DECT) shows promise to attenuate and even overcome some of these limitations, and might broaden the scope of patients eligible for cardiac CT towards the inclusion of higher risk patients. This might be achieved as a result of both safety (contrast reduction) and physiopathological (myocardial perfusion and characterization) issues. In this article, we will review the main clinical cardiac applications of DECT, that can be summarized in two core aspects: coronary artery evaluation, and myocardial evaluation.

  7. Effective dose calculation in CT using high sensitivity TLDs

    International Nuclear Information System (INIS)

    Brady, Z.; Johnston, P.N.

    2010-01-01

    Full text: To determine the effective dose for common paediatric CT examinations using thermoluminescence dosimetry (TLD) mea surements. High sensitivity TLD chips (LiF:Mg,Cu,P, TLD-IOOH, Thermo Fisher Scientific, Waltham, MA) were calibrated on a linac at an energy of 6 MY. A calibration was also performed on a superricial X-ray unit at a kilovoltage energy to validate the megavoltage cali bration for the purpose of measuring doses in the diagnostic energy range. The dose variation across large organs was assessed and a methodology for TLD placement in a 10 year old anthropomorphic phantom developed. Effective dose was calculated from the TLD measured absorbed doses for typical CT examinations after correcting for the TLD energy response and taking into account differences in the mass energy absorption coefficients for different tissues and organs. Results Using new tissue weighting factors recommended in ICRP Publication 103, the effective dose for a CT brain examination on a 10 year old was 1.6 millisieverts (mSv), 4.9 mSv for a CT chest exa ination and 4.7 mSv for a CT abdomen/pelvis examination. These values are lower for the CT brain examination, higher for the CT chest examination and approximately the same for the CT abdomen/ pelvis examination when compared with effective doses calculated using ICRP Publication 60 tissue weighting factors. Conclusions High sensitivity TLDs calibrated with a radiotherapy linac are useful for measuring dose in the diagnostic energy range and overcome limitations of output reproducibility and uniformity asso ciated with traditional TLD calibration on CT scanners or beam quality matched diagnostic X-ray units.

  8. Dual energy CT: New horizon in medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo [Dept. of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Goo, Jin Mo [Dept. of Radiology, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2017-08-01

    Dual-energy CT has remained underutilized over the past decade probably due to a cumbersome workflow issue and current technical limitations. Clinical radiologists should be made aware of the potential clinical benefits of dual-energy CT over single-energy CT. To accomplish this aim, the basic principle, current acquisition methods with advantages and disadvantages, and various material-specific imaging methods as clinical applications of dual-energy CT should be addressed in detail. Current dual-energy CT acquisition methods include dual tubes with or without beam filtration, rapid voltage switching, dual-layer detector, split filter technique, and sequential scanning. Dual-energy material-specific imaging methods include virtual monoenergetic or monochromatic imaging, effective atomic number map, virtual non-contrast or unenhanced imaging, virtual non-calcium imaging, iodine map, inhaled xenon map, uric acid imaging, automatic bone removal, and lung vessels analysis. In this review, we focus on dual-energy CT imaging including related issues of radiation exposure to patients, scanning and post-processing options, and potential clinical benefits mainly to improve the understanding of clinical radiologists and thus, expand the clinical use of dual-energy CT; in addition, we briefly describe the current technical limitations of dual-energy CT and the current developments of photon-counting detector.

  9. Dual-Energy CT: New Horizon in Medical Imaging.

    Science.gov (United States)

    Goo, Hyun Woo; Goo, Jin Mo

    2017-01-01

    Dual-energy CT has remained underutilized over the past decade probably due to a cumbersome workflow issue and current technical limitations. Clinical radiologists should be made aware of the potential clinical benefits of dual-energy CT over single-energy CT. To accomplish this aim, the basic principle, current acquisition methods with advantages and disadvantages, and various material-specific imaging methods as clinical applications of dual-energy CT should be addressed in detail. Current dual-energy CT acquisition methods include dual tubes with or without beam filtration, rapid voltage switching, dual-layer detector, split filter technique, and sequential scanning. Dual-energy material-specific imaging methods include virtual monoenergetic or monochromatic imaging, effective atomic number map, virtual non-contrast or unenhanced imaging, virtual non-calcium imaging, iodine map, inhaled xenon map, uric acid imaging, automatic bone removal, and lung vessels analysis. In this review, we focus on dual-energy CT imaging including related issues of radiation exposure to patients, scanning and post-processing options, and potential clinical benefits mainly to improve the understanding of clinical radiologists and thus, expand the clinical use of dual-energy CT; in addition, we briefly describe the current technical limitations of dual-energy CT and the current developments of photon-counting detector.

  10. The study of amplification circuit characteristics of photocurrent signal of high-energy industrial CT detection system

    International Nuclear Information System (INIS)

    Wang Jue; Tan Hui; Wang Xin; Chen Jiaoze

    2011-01-01

    According to characteristics of the Photocurrent signal from detection system of high energy industrial CT, sets up the integral amplifier circuit test platform based ACF2101, through the study of this amplifier circuit, a integral capacitor using air as dielectric is proposed in order to get high-gain. After experimental tests, results are good. (authors)

  11. Primary staging of laryngeal and hypopharyngeal cancer: CT, MR imaging and dual-energy CT

    International Nuclear Information System (INIS)

    Kuno, Hirofumi; Onaya, Hiroaki; Fujii, Satoshi; Ojiri, Hiroya; Otani, Katharina; Satake, Mitsuo

    2014-01-01

    Laryngeal and hypopharyngeal cancer, in particular T4a disease associated with cartilage invasion and extralaryngeal spread, needs to be evaluated accurately because treatment can impact heavily on a patient's quality of life. Reliable imaging tools are therefore indispensible. CT offers high spatial and temporal resolution and remains the preferred imaging modality. Although cartilage invasion can be diagnosed with acceptable accuracy by applying defined criteria for combinations of erosion, lysis and transmural extralaryngeal spread, iodine-enhanced tumors and non-ossified cartilage are sometimes difficult to distinguish. MR offers high contrast resolution for images without motion artifacts, although inflammatory changes in cartilage sometimes resemble cartilage invasion. With dual-energy CT, combined iodine overlay images and weighted average images can be used for evaluation of cartilage invasion, since iodine enhancement is evident in tumor tissue but not in cartilage. Extralaryngeal spread can be evaluated from CT, MR or dual-energy CT images and the routes of tumor spread into the extralaryngeal soft tissue must be considered; (1) via the thyrohyoid membrane along the superior laryngeal neurovascular bundle, (2) via the inferior pharyngeal constrictor muscle, and (3) via the cricothyroid membrane. Radiologists need to understand the advantages and limitations of each imaging modality for staging of laryngeal and hypopharyngeal cancer

  12. High energy X-ray CT system using a linear accelerator for automobile parts inspection

    International Nuclear Information System (INIS)

    Kanamori, T.; Sukita, T.

    1995-01-01

    A high energy X-ray CT system (maximum photon energy: 0.95 MeV) has been developed for industrial use. This system employs a linear accelerator as an X-ray source. It is able to image the cross section of automobile parts and can be applied to a solidification analysis study of the cylinder head in an automobile. This paper describes the features of the system and application results which can be related to solidification analysis of the cylinder head when fabricated from an aluminum casting. Some cross-sectional images are also presented as evidence for nondestructive inspection of automobile parts. (orig.)

  13. High-picture quality industrial CT scanner

    International Nuclear Information System (INIS)

    Shoji, Takao; Nishide, Akihiko; Fujii, Masashi.

    1989-01-01

    Industrial X-ray-CT-scanners, which provide cross-sectional images of a tested sample without destroying it, are attracting attention as a new nondestructive inspection device. In 1982, Toshiba commenced the development of industrial CT scanners, and introduced the 'TOSCANER' -3000 and-4000 series. Now, the state of the art 'TOSCANER'-20000 series of CT systems has been developed incorporating the latest computer tomography and image processing technology, such as the T9506 image processor. One of the advantages of this system is its applicability to a wide range of X-ray energy . The 'TOSCANER'-20000 series can be utilized for inspecting castings and other materials with relatively low-transparency to X-rays, as well as ceramics, composite materials and other materials with high X-ray transparency. A further feature of the new system is its high-picture quality, with a high-spatial resolution resulting from a pixel size of 0.2x0.2(mm). (author)

  14. Can dual-energy CT replace perfusion CT for the functional evaluation of advanced hepatocellular carcinoma?

    Science.gov (United States)

    Mulé, Sébastien; Pigneur, Frédéric; Quelever, Ronan; Tenenhaus, Arthur; Baranes, Laurence; Richard, Philippe; Tacher, Vania; Herin, Edouard; Pasquier, Hugo; Ronot, Maxime; Rahmouni, Alain; Vilgrain, Valérie; Luciani, Alain

    2018-05-01

    To determine the degree of relationship between iodine concentrations derived from dual-energy CT (DECT) and perfusion CT parameters in patients with advanced HCC under treatment. In this single-centre IRB approved study, 16 patients with advanced HCC treated with sorafenib or radioembolization who underwent concurrent dynamic perfusion CT and multiphase DECT using a single source, fast kV switching DECT scanner were included. Written informed consent was obtained for all patients. HCC late-arterial and portal iodine concentrations, blood flow (BF)-related and blood volume (BV)-related perfusion parameters maps were calculated. Mixed-effects models of the relationship between iodine concentrations and perfusion parameters were computed. An adjusted p value (Bonferroni method) statistic (F)=28.52, padvanced HCC lesions, DECT-derived late-arterial iodine concentration is strongly related to both aBF and BV, while portal iodine concentration mainly reflects BV, offering DECT the ability to evaluate both morphological and perfusion changes. • Late-arterial iodine concentration is highly related to arterial BF and BV. • Portal iodine concentration mainly reflects tumour blood volume. • Dual-energy CT offers significantly decreased radiation dose compared with perfusion CT.

  15. TU-F-18A-09: CT Number Stability Across Patient Sizes Using Virtual-Monoenergetic Dual-Energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Michalak, G; Grimes, J; Fletcher, J; McCollough, C [Mayo Clinic, Rochester, MN (United States); Halaweish, A [Siemens Healthcare, Rochester, MN (United States)

    2014-06-15

    Purpose: Virtual-monoenergetic imaging uses dual-energy CT data to synthesize images corresponding to a single photon energy, thereby reducing beam-hardening artifacts. This work evaluated the ability of a commercial virtual-monoenergetic algorithm to achieve stable CT numbers across patient sizes. Methods: Test objects containing a range of iodine and calcium hydroxyapatite concentrations were placed inside 8 torso-shaped water phantoms, ranging in lateral width from 15 to 50 cm, and scanned on a dual-source CT system (Siemens Somatom Force). Single-energy scans were acquired from 70-150 kV in 10 kV increments; dual-energy scans were acquired using 4 energy pairs (low energy: 70, 80, 90, and 100 kV; high energy: 150 kV + 0.6 mm Sn). CTDIvol was matched for all single- and dual-energy scans for a given phantom size. All scans used 128×0.6 mm collimation and were reconstructed with 1-mm thickness at 0.8-mm increment and a medium smooth body kernel. Monoenergetic images were generated using commercial software (syngo Via Dual Energy, VA30). Iodine contrast was calculated as the difference in mean iodine and water CT numbers from respective regions-of-interest in 10 consecutive images. Results: CT numbers remained stable as phantom width varied from 15 to 50 cm for all dual-energy data sets (except for at 50 cm using 70/150Sn due to photon starvation effects). Relative to the 15 cm phantom, iodine contrast was within 5.2% of the 70 keV value for phantom sizes up to 45 cm. At 90/150Sn, photon starvation did not occur at 50 cm, and iodine contrast in the 50-cm phantom was within 1.4% of the 15-cm phantom. Conclusion: Monoenergetic imaging, as implemented in the evaluated commercial system, eliminated the variation in CT numbers due to patient size, and may provide more accurate data for quantitative tasks, including radiation therapy treatment planning. Siemens Healthcare.

  16. A simulation study on proton computed tomography (CT) stopping power accuracy using dual energy CT scans as benchmark.

    Science.gov (United States)

    Hansen, David C; Seco, Joao; Sørensen, Thomas Sangild; Petersen, Jørgen Breede Baltzer; Wildberger, Joachim E; Verhaegen, Frank; Landry, Guillaume

    2015-01-01

    Accurate stopping power estimation is crucial for treatment planning in proton therapy, and the uncertainties in stopping power are currently the largest contributor to the employed dose margins. Dual energy x-ray computed tomography (CT) (clinically available) and proton CT (in development) have both been proposed as methods for obtaining patient stopping power maps. The purpose of this work was to assess the accuracy of proton CT using dual energy CT scans of phantoms to establish reference accuracy levels. A CT calibration phantom and an abdomen cross section phantom containing inserts were scanned with dual energy and single energy CT with a state-of-the-art dual energy CT scanner. Proton CT scans were simulated using Monte Carlo methods. The simulations followed the setup used in current prototype proton CT scanners and included realistic modeling of detectors and the corresponding noise characteristics. Stopping power maps were calculated for all three scans, and compared with the ground truth stopping power from the phantoms. Proton CT gave slightly better stopping power estimates than the dual energy CT method, with root mean square errors of 0.2% and 0.5% (for each phantom) compared to 0.5% and 0.9%. Single energy CT root mean square errors were 2.7% and 1.6%. Maximal errors for proton, dual energy and single energy CT were 0.51%, 1.7% and 7.4%, respectively. Better stopping power estimates could significantly reduce the range errors in proton therapy, but requires a large improvement in current methods which may be achievable with proton CT.

  17. A simulation study on proton computed tomography (CT) stopping power accuracy using dual energy CT scans as benchmark

    DEFF Research Database (Denmark)

    Hansen, David Christoffer; Seco, Joao; Sørensen, Thomas Sangild

    2015-01-01

    Background. Accurate stopping power estimation is crucial for treatment planning in proton therapy, and the uncertainties in stopping power are currently the largest contributor to the employed dose margins. Dual energy x-ray computed tomography (CT) (clinically available) and proton CT (in...... development) have both been proposed as methods for obtaining patient stopping power maps. The purpose of this work was to assess the accuracy of proton CT using dual energy CT scans of phantoms to establish reference accuracy levels. Material and methods. A CT calibration phantom and an abdomen cross section...... phantom containing inserts were scanned with dual energy and single energy CT with a state-of-the-art dual energy CT scanner. Proton CT scans were simulated using Monte Carlo methods. The simulations followed the setup used in current prototype proton CT scanners and included realistic modeling...

  18. Early small-bowel ischemia: dual-energy CT improves conspicuity compared with conventional CT in a swine model.

    Science.gov (United States)

    Potretzke, Theodora A; Brace, Christopher L; Lubner, Meghan G; Sampson, Lisa A; Willey, Bridgett J; Lee, Fred T

    2015-04-01

    To compare dual-energy computed tomography (CT) with conventional CT for the detection of small-bowel ischemia in an experimental animal model. The study was approved by the animal care and use committee and was performed in accordance with the Guide for Care and Use of Laboratory Animals issued by the National Research Council. Ischemic bowel segments (n = 8) were created in swine (n = 4) by means of surgical occlusion of distal mesenteric arteries and veins. Contrast material-enhanced dual-energy CT and conventional single-energy CT (120 kVp) sequences were performed during the portal venous phase with a single-source fast-switching dual-energy CT scanner. Attenuation values and contrast-to-noise ratios of ischemic and perfused segments on iodine material-density, monospectral dual-energy CT (51 keV, 65 keV, and 70 keV), and conventional 120-kVp CT images were compared. Linear mixed-effects models were used for comparisons. The attenuation difference between ischemic and perfused segments was significantly greater on dual-energy 51-keV CT images than on conventional 120-kVp CT images (mean difference, 91.7 HU vs 47.6 HU; P conventional CT by increasing attenuation differences between ischemic and perfused segments on low-kiloelectron volt and iodine material density images. © RSNA, 2014.

  19. Energy Dependence of Measured CT Numbers on Substituted Materials Used for CT Number Calibration of Radiotherapy Treatment Planning Systems.

    Directory of Open Access Journals (Sweden)

    Reza Mahmoudi

    Full Text Available For accurate dose calculations, it is necessary to provide a correct relationship between the CT numbers and electron density in radiotherapy treatment planning systems (TPSs. The purpose of this study was to investigate the energy dependence of measured CT numbers on substituted materials used for CT number calibration of radiotherapy TPSs and the resulting errors in the treatment planning calculation doses.In this study, we designed a cylindrical water phantom with different materials used as tissue equivalent materials for the simulation of tissues and obtaining the related CT numbers. For evaluating the effect of CT number variations of substituted materials due to energy changing of scanner (kVp on the dose calculation of TPS, the slices of the scanned phantom at three kVp's were imported into the desired TPSs (MIRS and CorePLAN. Dose calculations were performed on two TPSs.The mean absolute percentage differences between the CT numbers of CT scanner and two treatment planning systems for all the samples were 3.22%±2.57% for CorePLAN and 2.88%±2.11% for MIRS. It was also found that the maximum absolute percentage difference between all of the calculated doses from each photon beam of linac (6 and 15 MV at three kVp's was less than 1.2%.The present study revealed that, for the materials with effective low atomic number, the mean CT number increased with increasing energy, which was opposite for the materials with an effective high atomic number. We concluded that the tissue substitute materials had a different behavior in the energy ranges from 80 to 130 kVp. So, it is necessary to consider the energy dependence of the substitute materials used for the measurement or calibration of CT number for radiotherapy treatment planning systems.

  20. Comparison of the effect of radiation exposure from dual-energy CT versus single-energy CT on double-strand breaks at CT pulmonary angiography.

    Science.gov (United States)

    Tao, Shu Min; Li, Xie; Schoepf, U Joseph; Nance, John W; Jacobs, Brian E; Zhou, Chang Sheng; Gu, Hai Feng; Lu, Meng Jie; Lu, Guang Ming; Zhang, Long Jiang

    2018-04-01

    To compare the effect of dual-source dual-energy CT versus single-energy CT on DNA double-strand breaks (DSBs) in blood lymphocytes at CT pulmonary angiography (CTPA). Sixty-two patients underwent either dual-energy CTPA (Group 1: n = 21, 80/Sn140 kVp, 89/38 mAs; Group 2: n = 20, 100/Sn140 kVp, 89/76 mAs) or single-energy CTPA (Group 3: n = 21, 120 kVp, 110 mAs). Blood samples were obtained before and 5 min after CTPA. DSBs were assessed with fluorescence microscopy and Kruskal-Walls tests were used to compare DSBs levels among groups. Volume CT dose index (CTDIvol), dose length product (DLP) and organ radiation dose were compared using ANOVA. There were increased excess DSB foci per lymphocyte 5 min after CTPA examinations in three groups (Group 1: P = .001; Group 2: P = .001; Group 3: P = .006). There were no differences among groups regarding excess DSB foci/cell and percentage of excess DSBs (Group 1, 23%; Group 2, 24%; Group 3, 20%; P = .932). CTDIvol, DLP and organ radiation dose in Group 1 were the lowest among the groups (all P dual-source and single-source CTPA, while dual-source dual-energy CT protocols do not increase the estimated radiation dose and also do not result in a higher incidence of DNA DSBs in patients undergoing CTPA. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Derivation of linear attenuation coefficients from CT numbers for low-energy photons

    International Nuclear Information System (INIS)

    Watanabe, Y.

    1999-01-01

    One can estimate photon attenuation properties from the CT number. In a standard method one assumes that the linear attenuation coefficient is proportional to electron density and ignores its nonlinear dependence on atomic number. When the photon energy is lower than about 50 keV, such as for brachytherapy applications, however, photoelectric absorption and Rayleigh scattering become important. Hence the atomic number must be explicitly considered in estimating the linear attenuation coefficient. In this study we propose a method to more accurately estimate the linear attenuation coefficient of low-energy photons from CT numbers. We formulate an equation that relates the CT number to the electron density and the effective atomic number. We use a CT calibration phantom to determine unknown coefficients in the equation. The equation with a given CT number is then solved for the effective atomic number, which in turn is used to calculate the linear attenuation coefficient for low-energy photons. We use the CT phantom to test the new method. The method significantly improves the standard method in estimating the attenuation coefficient at low photon energies (20keV≤E≤40keV) for materials with high atomic numbers. (author)

  2. Dual-Energy CT in Enhancing Subdural Effusions that Masquerade as Subdural Hematomas: Diagnosis with Virtual High-Monochromatic (190-keV) Images.

    Science.gov (United States)

    Bodanapally, U K; Dreizin, D; Issa, G; Archer-Arroyo, K L; Sudini, K; Fleiter, T R

    2017-10-01

    Extravasation of iodinated contrast into subdural space following contrast-enhanced radiographic studies results in hyperdense subdural effusions, which can be mistaken as acute subdural hematomas on follow-up noncontrast head CTs. Our aim was to identify the factors associated with contrast-enhancing subdural effusion, characterize diffusion and washout kinetics of iodine in enhancing subdural effusion, and assess the utility of dual-energy CT in differentiating enhancing subdural effusion from subdural hematoma. We retrospectively analyzed follow-up head dual-energy CT studies in 423 patients with polytrauma who had undergone contrast-enhanced whole-body CT. Twenty-four patients with enhancing subdural effusion composed the study group, and 24 randomly selected patients with subdural hematoma were enrolled in the comparison group. Postprocessing with syngo.via was performed to determine the diffusion and washout kinetics of iodine. The sensitivity and specificity of dual-energy CT for the diagnosis of enhancing subdural effusion were determined with 120-kV, virtual monochromatic energy (190-keV) and virtual noncontrast images. Patients with enhancing subdural effusion were significantly older (mean, 69 years; 95% CI, 60-78 years; P subdural effusions was reached within the first 8 hours of contrast administration with a mean of 0.98 mg/mL (95% CI, 0.81-1.13 mg/mL), and complete washout was achieved at 38 hours. For the presence of a hyperdense subdural collection on 120-kV images with a loss of hyperattenuation on 190-keV and virtual noncontrast images, when considered as a true-positive for enhancing subdural effusion, the sensitivity was 100% (95% CI, 85.75%-100%) and the specificity was 91.67% (95% CI, 73%-99%). Dual-energy CT has a high sensitivity and specificity in differentiating enhancing subdural effusion from subdural hematoma. Hence, dual-energy CT has a potential to obviate follow-up studies. © 2017 by American Journal of Neuroradiology.

  3. Energy Limits in Second Generation High-pitch Dual Source CT - Comparison in an Upper Abdominal Phantom

    Directory of Open Access Journals (Sweden)

    Martin Beeres

    2015-01-01

    Full Text Available Objectives: The aim of our study was to find out how much energy is applicable in second-generation dual source high-pitch computed tomography (CT in imaging of the abdomen. Materials and Methods: We examined an upper abdominal phantom using a Somatom Definition Flash CT-Scanner (Siemens, Forchheim, Germany. The study protocol consisted of a scan-series at 100 kV and 120 kV. In each scan series we started with a pitch of 3.2 and reduced it in steps of 0.2, until a pitch of 1.6 was reached. The current was adjusted to the maximum the scanner could achieve. Energy values, image noise, image quality, and radiation exposure were evaluated. Results: For a pitch of 3.2 the maximum applicable current was 142 mAs at 120 kV and in 100 kV the maximum applicable current was 114 mAs. For conventional abdominal imaging, current levels of 200 to 260 mAs are generally used. To achieve similar current levels, we had to decrease the pitch to 1.8 at 100 kV - at this pitch we could perform our imaging at 204 mAs. At a pitch of 2.2 in 120 kV we could apply a current of 206 mAs. Conclusion: We conclude our study by stating that if there is a need for a higher current, we have to reduce the pitch. In a high-pitch dual source CT, we always have to remember where our main focus is, so we can adjust the pitch to the energy we need in the area of the body that has to be imaged, to find answers to the clinical question being raised.

  4. Dual-energy compared to single-energy CT in pediatric imaging: a phantom study for DECT clinical guidance

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaowei; Servaes, Sabah; Darge, Kassa [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); University of Pennsylvania, The Perelman School of Medicine, Philadelphia, PA (United States); McCullough, William P. [University of Virginia Health System, Department of Radiology and Medical Imaging, Charlottesville, VA (United States); Mecca, Patricia [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States)

    2016-11-15

    Dual-energy CT technology is available on scanners from several vendors and offers significant advantages over classic single-energy CT technology in multiple clinical applications. Many studies have detailed dual-energy CT applications in adults and several have evaluated the relative radiation dose performance of dual-energy CT in adult imaging. However, little has been published on dual-energy CT imaging in the pediatric population, and the relative dose performance of dual-energy CT imaging in the pediatric population is not well described. When evaluating dual-energy CT technology for implementation into a routine clinical pediatric imaging practice, the radiation dose implications must be considered, and when comparing relative CT dose performance, image quality must also be evaluated. Therefore the purpose of this study is to develop dual-energy CT scan protocols based on our optimized single-energy scan protocols and compare the dose. We scanned the head, chest and abdomen regions of pediatric-size anthropomorphic phantoms with contrast inserts, using our optimized single-energy clinical imaging protocols on a Siemens Flash {sup registered} CT scanner. We then scanned the phantoms in dual-energy mode using matching image-quality reference settings. The effective CT dose index volume (CTDI{sub vol}) of the scans was used as a surrogate for relative dose in comparing the single- and dual-energy scans. Additionally, we evaluated image quality using visual assessment and contrast-to-noise ratio. Dual-energy CT scans of the head and abdomen were dose-neutral for all three phantoms. Dual-energy CT scans of the chest showed a relative dose increase over the single-energy scan for 1- and 5-year-old child-based age-equivalent phantoms, ranging 11-20%. Quantitative analysis of image quality showed no statistically significant difference in image quality between the single-energy and dual-energy scans. There was no clinically significant difference in image quality by

  5. Synthetic CT: Simulating low dose single and dual energy protocols from a dual energy scan

    International Nuclear Information System (INIS)

    Wang, Adam S.; Pelc, Norbert J.

    2011-01-01

    Purpose: The choice of CT protocol can greatly impact patient dose and image quality. Since acquiring multiple scans at different techniques on a given patient is undesirable, the ability to predict image quality changes starting from a high quality exam can be quite useful. While existing methods allow one to generate simulated images of lower exposure (mAs) from an acquired CT exam, the authors present and validate a new method called synthetic CT that can generate realistic images of a patient at arbitrary low dose protocols (kVp, mAs, and filtration) for both single and dual energy scans. Methods: The synthetic CT algorithm is derived by carefully ensuring that the expected signal and noise are accurate for the simulated protocol. The method relies on the observation that the material decomposition from a dual energy CT scan allows the transmission of an arbitrary spectrum to be predicted. It requires an initial dual energy scan of the patient to either synthesize raw projections of a single energy scan or synthesize the material decompositions of a dual energy scan. The initial dual energy scan contributes inherent noise to the synthesized projections that must be accounted for before adding more noise to simulate low dose protocols. Therefore, synthetic CT is subject to the constraint that the synthesized data have noise greater than the inherent noise. The authors experimentally validated the synthetic CT algorithm across a range of protocols using a dual energy scan of an acrylic phantom with solutions of different iodine concentrations. An initial 80/140 kVp dual energy scan of the phantom provided the material decomposition necessary to synthesize images at 100 kVp and at 120 kVp, across a range of mAs values. They compared these synthesized single energy scans of the phantom to actual scans at the same protocols. Furthermore, material decompositions of a 100/120 kVp dual energy scan are synthesized by adding correlated noise to the initial material

  6. Inertial fusion energy power plant design using the Compact Torus Accelerator: HYLIFE-CT

    International Nuclear Information System (INIS)

    Moir, R.W.; Hammer, J.H.; Hartman, C.W.; Leber, R.L.; Logan, B.G.; Petzoldt, R.W.; Tabak, M.; Tobin, M.T.; Bieri, R.L.; Hoffman, M.A.

    1992-01-01

    The Compact Torus Accelerator (CTA), under development at Lawrence Livermore National Laboratory, offers the promise of a low-cost, high-efficiency, high energy, high-power-density driver for ICF and MICF (Magnetically Insulated ICF) type fusion systems. A CTA with 100 MJ driver capacitor bank energy is predicted to deliver ∼30 MJ CT kinetic energy to a 1 cm 2 target in several nanoseconds for a power density of ∼10 16 watts/cm 2 . The estimated cost of delivered energy is ∼3$/Joule, or $100M for 30 MJ. This driver appears to be cost-effective and, in this regard, is virtually alone among IFE drivers. We discuss indirect-drive ICF with a DT fusion energy gain Q = 70 for a total yield of 2 GJ. The CT can be guided to the target inside a several-meter-long disposable cone made of frozen Li 2 BeF 4 , the same material as the coolant. We have designed a power plant including CT injection, target emplacement, containment, energy recovery, and tritium breeding. The cost of electricity is predicted to be 4.8 cents/kWh, which is competitive with future coal and nuclear costs

  7. Dual-energy compared to single-energy CT in pediatric imaging: a phantom study for DECT clinical guidance

    International Nuclear Information System (INIS)

    Zhu, Xiaowei; Servaes, Sabah; Darge, Kassa; McCullough, William P.; Mecca, Patricia

    2016-01-01

    Dual-energy CT technology is available on scanners from several vendors and offers significant advantages over classic single-energy CT technology in multiple clinical applications. Many studies have detailed dual-energy CT applications in adults and several have evaluated the relative radiation dose performance of dual-energy CT in adult imaging. However, little has been published on dual-energy CT imaging in the pediatric population, and the relative dose performance of dual-energy CT imaging in the pediatric population is not well described. When evaluating dual-energy CT technology for implementation into a routine clinical pediatric imaging practice, the radiation dose implications must be considered, and when comparing relative CT dose performance, image quality must also be evaluated. Therefore the purpose of this study is to develop dual-energy CT scan protocols based on our optimized single-energy scan protocols and compare the dose. We scanned the head, chest and abdomen regions of pediatric-size anthropomorphic phantoms with contrast inserts, using our optimized single-energy clinical imaging protocols on a Siemens Flash "r"e"g"i"s"t"e"r"e"d CT scanner. We then scanned the phantoms in dual-energy mode using matching image-quality reference settings. The effective CT dose index volume (CTDI_v_o_l) of the scans was used as a surrogate for relative dose in comparing the single- and dual-energy scans. Additionally, we evaluated image quality using visual assessment and contrast-to-noise ratio. Dual-energy CT scans of the head and abdomen were dose-neutral for all three phantoms. Dual-energy CT scans of the chest showed a relative dose increase over the single-energy scan for 1- and 5-year-old child-based age-equivalent phantoms, ranging 11-20%. Quantitative analysis of image quality showed no statistically significant difference in image quality between the single-energy and dual-energy scans. There was no clinically significant difference in image quality

  8. Myocardial perfusion imaging with dual energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Kwang Nam [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Radiology, SMG-SNU Boramae Medical Center, Seoul (Korea, Republic of); De Cecco, Carlo N. [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Caruso, Damiano [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Radiological Sciences, Oncology and Pathology, University of Rome “Sapienza”, Rome (Italy); Tesche, Christian [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Cardiology and Intensive Care Medicine, Heart Center Munich-Bogenhausen, Munich (Germany); Spandorfer, Adam; Varga-Szemes, Akos [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Schoepf, U. Joseph, E-mail: schoepf@musc.edu [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC (United States)

    2016-10-15

    Highlights: • Stress dual-energy sCTMPI offers the possibility to directly detect the presence of myocardial perfusion defects. • Stress dual-energy sCTMPI allows differentiating between reversible and fixed myocardial perfusion defects. • The combination of coronary CT angiography and dual-energy sCTMPI can improve the ability of CT to detect hemodynamically relevant coronary artery disease. - Abstract: Dual-energy CT (DECT) enables simultaneous use of two different tube voltages, thus different x-ray absorption characteristics are acquired in the same anatomic location with two different X-ray spectra. The various DECT techniques allow material decomposition and mapping of the iodine distribution within the myocardium. Static dual-energy myocardial perfusion imaging (sCTMPI) using pharmacological stress agents demonstrate myocardial ischemia by single snapshot images of myocardial iodine distribution. sCTMPI gives incremental values to coronary artery stenosis detected on coronary CT angiography (CCTA) by showing consequent reversible or fixed myocardial perfusion defects. The comprehensive acquisition of CCTA and sCTMPI offers extensive morphological and functional evaluation of coronary artery disease. Recent studies have revealed that dual-energy sCTMPI shows promising diagnostic accuracy for the detection of hemodynamically significant coronary artery disease compared to single-photon emission computed tomography, invasive coronary angiography, and cardiac MRI. The aim of this review is to present currently available DECT techniques for static myocardial perfusion imaging and recent clinical applications and ongoing investigations.

  9. Dual-energy perfusion-CT of pancreatic adenocarcinoma

    International Nuclear Information System (INIS)

    Klauß, M.; Stiller, W.; Pahn, G.; Fritz, F.; Kieser, M.; Werner, J.; Kauczor, H.U.; Grenacher, L.

    2013-01-01

    Purpose: To evaluate the feasibility of dual-energy CT (DECT)-perfusion of pancreatic carcinomas for assessing the differences in perfusion, permeability and blood volume of healthy pancreatic tissue and histopathologically confirmed solid pancreatic carcinoma. Materials and methods: 24 patients with histologically proven pancreatic carcinoma were examined prospectively with a 64-slice dual source CT using a dynamic sequence of 34 dual-energy (DE) acquisitions every 1.5 s (80 ml of iodinated contrast material, 370 mg/ml, flow rate 5 ml/s). 80 kV p , 140 kV p , and weighted average (linearly blended M0.3) 120 kV p -equivalent dual-energy perfusion image data sets were evaluated with a body-perfusion CT tool (Body-PCT, Siemens Medical Solutions, Erlangen, Germany) for estimating perfusion, permeability, and blood volume values. Color-coded parameter maps were generated. Results: In all 24 patients dual-energy CT-perfusion was. All carcinomas could be identified in the color-coded perfusion maps. Calculated perfusion, permeability and blood volume values were significantly lower in pancreatic carcinomas compared to healthy pancreatic tissue. Weighted average 120 kV p -equivalent perfusion-, permeability- and blood volume-values determined from DE image data were 0.27 ± 0.04 min −1 vs. 0.91 ± 0.04 min −1 (p −1 vs. 0.67 ± 0.05 *0.5 min −1 (p = 0.06) and 0.49 ± 0.07 min −1 vs. 1.28 ± 0.11 min −1 (p p the standard deviations of the kV p 120 kV p -equivalent values were manifestly smaller. Conclusion: Dual-energy CT-perfusion of the pancreas is feasible. The use of DECT improves the accuracy of CT-perfusion of the pancreas by fully exploiting the advantages of enhanced iodine contrast at 80 kV p in combination with the noise reduction at 140 kV p . Therefore using dual-energy perfusion data could improve the delineation of pancreatic carcinomas

  10. Dual-energy CT for detection of contrast enhancement or leakage within high-density haematomas in patients with intracranial haemorrhage

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshiyuki; Tsukabe, Akio; Kunitomi, Yuki; Nishizawa, Mitsuo; Arisawa, Atsuko; Tanaka, Hisashi; Tomiyama, Noriyuki [Osaka University Graduate School of Medicine, Department of Diagnostic and Interventional Radiology, Suita, Osaka (Japan); Yoshiya, Kazuhisa; Shimazu, Takeshi [Osaka University Graduate School of Medicine, Department of Traumatology and Acute Critical Medicine, Osaka (Japan)

    2014-04-15

    Our study aimed to elucidate the diagnostic performance of dual-energy CT (DECT) in the detection of contrast enhancement in intracranial haematomas (ICrH) with early phase dual-energy computed tomography angiography (CTA) and compare the results with those obtained by delayed CT enhancement. Thirty-six patients with ICrH were retrospectively included in this study. All patients had undergone single-energy non-contrast CT and contrast-enhanced dual-source DECT. DECT images were post-processed with commercial software, followed by obtaining iodine images and virtual non-contrast images and generating combined images that created the impression of 120-kVp images. Two neuroradiologists, blinded to the patients' data, reviewed two reading sessions: session A (non-contrast CT and combined CT) and session B (non-contrast CT, combined CT, and iodine images) for detection of contrast enhancement in the haematomas. Contrast leakage or enhancement was detected in 23 (57.5 %) out of 40 haemorrhagic lesions in 36 patients on delayed CT. Three enhanced lesions were depicted only in the DECT iodine images. The sensitivity, specificity, positive predictive value, and negative predictive value of session A were 82.6, 94.1, 95.0, and 80.0 %, respectively, and those of session B were 95.7, 94.1, 95.7, and 94.1 %, respectively. DECT emphasised the iodine enhancement and facilitated the detection of contrast enhancement or leakage. (orig.)

  11. Dual-energy CT for detection of contrast enhancement or leakage within high-density haematomas in patients with intracranial haemorrhage.

    Science.gov (United States)

    Watanabe, Yoshiyuki; Tsukabe, Akio; Kunitomi, Yuki; Nishizawa, Mitsuo; Arisawa, Atsuko; Tanaka, Hisashi; Yoshiya, Kazuhisa; Shimazu, Takeshi; Tomiyama, Noriyuki

    2014-04-01

    Our study aimed to elucidate the diagnostic performance of dual-energy CT (DECT) in the detection of contrast enhancement in intracranial haematomas (ICrH) with early phase dual-energy computed tomography angiography (CTA) and compare the results with those obtained by delayed CT enhancement. Thirty-six patients with ICrH were retrospectively included in this study. All patients had undergone single-energy non-contrast CT and contrast-enhanced dual-source DECT. DECT images were post-processed with commercial software, followed by obtaining iodine images and virtual non-contrast images and generating combined images that created the impression of 120-kVp images. Two neuroradiologists, blinded to the patients' data, reviewed two reading sessions: session A (non-contrast CT and combined CT) and session B (non-contrast CT, combined CT, and iodine images) for detection of contrast enhancement in the haematomas. Contrast leakage or enhancement was detected in 23 (57.5 %) out of 40 haemorrhagic lesions in 36 patients on delayed CT. Three enhanced lesions were depicted only in the DECT iodine images. The sensitivity, specificity, positive predictive value, and negative predictive value of session A were 82.6, 94.1, 95.0, and 80.0 %, respectively, and those of session B were 95.7, 94.1, 95.7, and 94.1 %, respectively. DECT emphasised the iodine enhancement and facilitated the detection of contrast enhancement or leakage.

  12. Dual-energy CT for detection of contrast enhancement or leakage within high-density haematomas in patients with intracranial haemorrhage

    International Nuclear Information System (INIS)

    Watanabe, Yoshiyuki; Tsukabe, Akio; Kunitomi, Yuki; Nishizawa, Mitsuo; Arisawa, Atsuko; Tanaka, Hisashi; Tomiyama, Noriyuki; Yoshiya, Kazuhisa; Shimazu, Takeshi

    2014-01-01

    Our study aimed to elucidate the diagnostic performance of dual-energy CT (DECT) in the detection of contrast enhancement in intracranial haematomas (ICrH) with early phase dual-energy computed tomography angiography (CTA) and compare the results with those obtained by delayed CT enhancement. Thirty-six patients with ICrH were retrospectively included in this study. All patients had undergone single-energy non-contrast CT and contrast-enhanced dual-source DECT. DECT images were post-processed with commercial software, followed by obtaining iodine images and virtual non-contrast images and generating combined images that created the impression of 120-kVp images. Two neuroradiologists, blinded to the patients' data, reviewed two reading sessions: session A (non-contrast CT and combined CT) and session B (non-contrast CT, combined CT, and iodine images) for detection of contrast enhancement in the haematomas. Contrast leakage or enhancement was detected in 23 (57.5 %) out of 40 haemorrhagic lesions in 36 patients on delayed CT. Three enhanced lesions were depicted only in the DECT iodine images. The sensitivity, specificity, positive predictive value, and negative predictive value of session A were 82.6, 94.1, 95.0, and 80.0 %, respectively, and those of session B were 95.7, 94.1, 95.7, and 94.1 %, respectively. DECT emphasised the iodine enhancement and facilitated the detection of contrast enhancement or leakage. (orig.)

  13. Multi-energy spectral CT: adding value in emergency body imaging.

    Science.gov (United States)

    Punjabi, Gopal V

    2018-04-01

    Most vendors offer scanners capable of dual- or multi-energy computed tomography (CT) imaging. Advantages of multi-energy CT scanning include superior tissue characterization, detection of subtle iodine uptake differences, and opportunities to reduce contrast dose. However, utilization of this technology in the emergency department (ED) remains low. The purpose of this pictorial essay is to illustrate the value of multi-energy CT scanning in emergency body imaging.

  14. Material Separation Using Dual-Energy CT: Current and Emerging Applications.

    Science.gov (United States)

    Patino, Manuel; Prochowski, Andrea; Agrawal, Mukta D; Simeone, Frank J; Gupta, Rajiv; Hahn, Peter F; Sahani, Dushyant V

    2016-01-01

    Dual-energy (DE) computed tomography (CT) offers the opportunity to generate material-specific images on the basis of the atomic number Z and the unique mass attenuation coefficient of a particular material at different x-ray energies. Material-specific images provide qualitative and quantitative information about tissue composition and contrast media distribution. The most significant contribution of DE CT-based material characterization comes from the capability to assess iodine distribution through the creation of an image that exclusively shows iodine. These iodine-specific images increase tissue contrast and amplify subtle differences in attenuation between normal and abnormal tissues, improving lesion detection and characterization in the abdomen. In addition, DE CT enables computational removal of iodine influence from a CT image, generating virtual noncontrast images. Several additional materials, including calcium, fat, and uric acid, can be separated, permitting imaging assessment of metabolic imbalances, elemental deficiencies, and abnormal deposition of materials within tissues. The ability to obtain material-specific images from a single, contrast-enhanced CT acquisition can complement the anatomic knowledge with functional information, and may be used to reduce the radiation dose by decreasing the number of phases in a multiphasic CT examination. DE CT also enables generation of energy-specific and virtual monochromatic images. Clinical applications of DE CT leverage both material-specific images and virtual monochromatic images to expand the current role of CT and overcome several limitations of single-energy CT. (©)RSNA, 2016.

  15. Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT.

    Science.gov (United States)

    Pelgrim, Gert Jan; van Hamersvelt, Robbert W; Willemink, Martin J; Schmidt, Bernhard T; Flohr, Thomas; Schilham, Arnold; Milles, Julien; Oudkerk, Matthijs; Leiner, Tim; Vliegenthart, Rozemarijn

    2017-09-01

    To determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques. Five tubes with different iodine concentrations (0, 5, 10, 15, 20 mg/ml) were analysed in an anthropomorphic thoracic phantom. Adding two phantom rings simulated increased patient size. For third-generation dual source CT (DSCT), tube voltage combinations of 150Sn and 70, 80, 90, 100 kVp were analysed. For dual layer CT (DLCT), 120 and 140 kVp were used. Scans were repeated three times. Median normalized values and interquartile ranges (IQRs) were calculated for all kVp settings and phantom sizes. Correlation between measured and known iodine concentrations was excellent for both systems (R = 0.999-1.000, p < 0.0001). For DSCT, median measurement errors ranged from -0.5% (IQR -2.0, 2.0%) at 150Sn/70 kVp and -2.3% (IQR -4.0, -0.1%) at 150Sn/80 kVp to -4.0% (IQR -6.0, -2.8%) at 150Sn/90 kVp. For DLCT, median measurement errors ranged from -3.3% (IQR -4.9, -1.5%) at 140 kVp to -4.6% (IQR -6.0, -3.6%) at 120 kVp. Larger phantom sizes increased variability of iodine measurements (p < 0.05). Iodine concentration can be accurately quantified with state-of-the-art DECT systems from two vendors. The lowest absolute errors were found for DSCT using the 150Sn/70 kVp or 150Sn/80 kVp combinations, which was slightly more accurate than 140 kVp in DLCT. • High-end CT scanners allow accurate iodine quantification using different DECT techniques. • Lowest measurement error was found in scans with largest photon energy separation. • Dual-source CT quantified iodine slightly more accurately than dual layer CT.

  16. Agreement and precision of periprosthetic bone density measurements in micro-CT, single and dual energy CT.

    Science.gov (United States)

    Mussmann, Bo; Overgaard, Søren; Torfing, Trine; Traise, Peter; Gerke, Oke; Andersen, Poul Erik

    2017-07-01

    The objective of this study was to test the precision and agreement between bone mineral density measurements performed in micro CT, single and dual energy computed tomography, to determine how the keV level influences density measurements and to assess the usefulness of quantitative dual energy computed tomography as a research tool for longitudinal studies aiming to measure bone loss adjacent to total hip replacements. Samples from 10 fresh-frozen porcine femoral heads were placed in a Perspex phantom and computed tomography was performed with two acquisition modes. Bone mineral density was calculated and compared with measurements derived from micro CT. Repeated scans and dual measurements were performed in order to measure between- and within-scan precision. Mean density difference between micro CT and single energy computed tomography was 72 mg HA/cm 3 . For dual energy CT, the mean difference at 100 keV was 128 mg HA/cm 3 while the mean difference at 110-140 keV ranged from -84 to -67 mg HA/cm 3 compared with micro CT. Rescanning the samples resulted in a non-significant overall between-scan difference of 13 mg HA/cm 3 . Bland-Altman limits of agreement were wide and intraclass correlation coefficients ranged from 0.29 to 0.72, while 95% confidence intervals covered almost the full possible range. Repeating the density measurements for within-scan precision resulted in ICCs >0.99 and narrow limits of agreement. Single and dual energy quantitative CT showed excellent within-scan precision, but poor between-scan precision. No significant density differences were found in dual energy quantitative CT at keV-levels above 110 keV. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1470-1477, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  17. Dual-energy CT and ceramic or titanium prostheses material reduce CT artifacts and provide superior image quality of total knee arthroplasty.

    Science.gov (United States)

    Kasparek, Maximilian F; Töpker, Michael; Lazar, Mathias; Weber, Michael; Kasparek, Michael; Mang, Thomas; Apfaltrer, Paul; Kubista, Bernd; Windhager, Reinhard; Ringl, Helmut

    2018-06-07

    To evaluate the influence of different scan parameters for single-energy CT and dual-energy CT, as well as the impact of different material used in a TKA prosthesis on image quality and the extent of metal artifacts. Eight pairs of TKA prostheses from different vendors were examined in a phantom set-up. Each pair consisted of a conventional CoCr prosthesis and the corresponding anti-allergic prosthesis (full titanium, ceramic, or ceramic-coated) from the same vendor. Nine different (seven dual-energy CT and two single-energy CT) scan protocols with different characteristics were used to determine the most suitable CT protocol for TKA imaging. Quantitative image analysis included assessment of blooming artifacts (metal implants appear thicker on CT than they are, given as virtual growth in mm in this paper) and streak artifacts (thick dark lines around metal). Qualitative image analysis was used to investigate the bone-prosthesis interface. The full titanium prosthesis and full ceramic knee showed significantly fewer blooming artifacts compared to the standard CoCr prosthesis (mean virtual growth 0.6-2.2 mm compared to 2.9-4.6 mm, p energy CT protocols showed less blooming (range 3.3-3.8 mm) compared to single-energy protocols (4.6-5.5 mm). The full titanium and full ceramic prostheses showed significantly fewer streak artifacts (mean standard deviation 77-86 Hounsfield unit (HU)) compared to the standard CoCr prosthesis (277-334 HU, p energy CT protocols had fewer metal streak artifacts (215-296 HU compared to single-energy CT protocols (392-497 HU)). Full titanium and ceramic prostheses were ranked superior with regard to the image quality at the bone/prosthesis interface compared to a standard CoCr prosthesis, and all dual-energy CT protocols were ranked better than single-energy protocols. Dual-energy CT and ceramic or titanium prostheses reduce CT artifacts and provide superior image quality of total knee arthroplasty at the bone/prosthesis interface

  18. Quantitative dual energy CT measurements in rabbit VX2 liver tumors: Comparison to perfusion CT measurements and histopathological findings

    International Nuclear Information System (INIS)

    Zhang, Long Jiang; Wu, Shengyong; Wang, Mei; Lu, Li; Chen, Bo; Jin, Lixin; Wang, Jiandong; Larson, Andrew C.; Lu, Guang Ming

    2012-01-01

    Purpose: To evaluate the correlation between quantitative dual energy CT and perfusion CT measurements in rabbit VX2 liver tumors. Materials and methods: This study was approved by the institutional animal care and use committee at our institution. Nine rabbits with VX2 liver tumors underwent contrast-enhanced dual energy CT and perfusion CT. CT attenuation for the tumors and normal liver parenchyma and tumor-to-liver ratio were obtained at the 140 kVp, 80 kVp, average weighted images and dual energy CT iodine maps. Quantitative parameters for the viable tumor and adjacent liver were measured with perfusion CT. The correlation between the enhancement values of the tumor in iodine maps and perfusion CT parameters of each tumor was analyzed. Radiation dose from dual energy CT and perfusion CT was measured. Results: Enhancement values for the tumor were higher than that for normal liver parenchyma at the hepatic arterial phase (P < 0.05). The highest tumor-to-liver ratio was obtained in hepatic arterial phase iodine map. Hepatic blood flow of the tumor was higher than that for adjacent liver (P < 0.05). Enhancement values of hepatic tumors in the iodine maps positively correlated with permeability of capillary vessel surface (r = 0.913, P < 0.001), hepatic blood flow (r = 0.512, P = 0.010), and hepatic blood volume (r = 0.464, P = 0.022) at the hepatic arterial phases. The effective radiation dose from perfusion CT was higher than that from DECT (P < 0.001). Conclusions: The enhancement values for viable tumor tissues measured in iodine maps were well correlated to perfusion CT measurements in rabbit VX2 liver tumors. Compared with perfusion CT, dual energy CT of the liver required a lower radiation dose.

  19. Development of high resolution x-ray CT technique for irradiated fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Ishimi, Akihiro; Katsuyama, Kozo; Maeda, Koji; Asaga, Takeo [Japan Atomic Energy Agency, Oarai Research and Development Center, Oarai, Ibaraki (Japan)

    2012-03-15

    High X-ray CT technique was developed to observe the irradiation performance of FBR fuel assembly and MOX fuel. In this technique, the high energy X-ray pulse (12MeV) was used synchronizing detection system with the X-ray pulse to reduce the effect of the gamma ray emissions from the irradiated fuel assembly. In this study, this technique was upgraded to obtain high resolution X-ray CT image. In this upgrading, the collimator which had slit width of 0.1 mm and X-ray detector of a highly sensitive silicon semiconductor detector (100 channels) was introduced in the X-ray CT system. As a result of these developments, high resolution X-ray CT images could be obtained on the transverse cross section of irradiated fuel assembly. (author)

  20. Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT

    NARCIS (Netherlands)

    Pelgrim, Gert Jan; van Hamersvelt, Robbert W; Willemink, Martin J; Schmidt, Bernhard T; Flohr, Thomas; Schilham, Arnold; Milles, Julien; Oudkerk, Matthijs; Leiner, Tim; Vliegenthart, Rozemarijn

    OBJECTIVE: To determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques. METHODS: Five tubes with different iodine concentrations (0, 5, 10, 15, 20 mg/ml) were analysed in an anthropomorphic

  1. Implementation of dual energy CT scanning

    International Nuclear Information System (INIS)

    Marshall, W.; Hall, E.; Doost-Hoseini, A.; Alvarez, R.; Macovski, A.; Cassel, D.

    1984-01-01

    A prereconstruction method for dual energy (PREDECT) analysis of CT scans is described. In theory, this method can (a) eliminate beam hardening and produce an accuracy comparable with monoenergetic scans and (b) provide the effective atomic number and electron density of any voxel scanned. The implementation proves these statements and eliminates some of the objectionable noise. A phantom was constructed with a cylindrical sleeve-like compartment containing known amounts of high atomic number material simulating a removable skull. Conventional scans, with and without this beam hardener, were done of a water bath containing tubes of high electron and high atomic number material. Dual energy scans were then done for PREDECT. To increase the effective separation of the low and high energy beams by using more appropriate tube filtration, a beam filter changer was fabricated containing erbium, tungsten, aluminum, and steel. Erbium, tungsten, and steel were used at high energy and aluminum, steel, and erbium at low energy for data acquisition. The reconstructions were compared visually and numerically for noise levels with the original steel only filtration. A decrease was found in noise down to approximately one-half the prior level when erbium/aluminum or tungsten/aluminum replaced the steel/steel filter. Erbium and tungsten were equally effective. Steel/erbium and steel/aluminum also significantly reduced image noise. The noise in the photoelectric (P) and Compton (C) images is negatively correlated. At any pixel, if the noise is positive in the P image, it is most probably negative in the C. Using this fact, the noise was reduced by postreconstruction processing

  2. Virtual non-contrast dual-energy CT compared to single-energy CT of the urinary tract: a prospective study

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, Margareta; Liden, Mats; Geijer, Haakan; Andersson, Torbjoern [Dept. of Radiology, Oerebro Univ. Hospital, Oerebro Univ., Oerebro (Sweden)], E-mail: margareta.lundin@orebroll.se; Magnuson, Anders [Clinical Epidemiology and Biostatistic Unit, Oerebro Univ. Hospital, Oerebro (Sweden); Mohammed, Ahmed Abdulilah [Dept. of Radiology, Linkoeping Univ. Hospital, Linkoeping (Sweden); Persson, Anders [CMIV Center for Medical Image Science and Visualization, Linkoeping (Sweden)

    2012-07-15

    Background. Dual-energy computed tomography (DECT) has been shown to be useful for subtracting bone or calcium in CT angiography and gives an opportunity to produce a virtual non-contrast-enhanced (VNC) image from a series where contrast agents have been given intravenously. High noise levels and low resolution have previously limited the diagnostic value of the VNC images created with the first generation of DECT. With the recent introduction of a second generation of DECT, there is a possibility of obtaining VNC images with better image quality at hopefully lower radiation dose compared to the previous generation. Purpose. To compare the image quality of the single-energy series to a VNC series obtained with a two generations of DECT scanners. CT of the urinary tract was used as a model. Material and Methods. Thirty patients referred for evaluation of hematuria were examined with an older system (Somatom Definition) and another 30 patients with a new generation (Somatom Definition Flash). One single-energy series was obtained before and one dual-energy series after administration of intravenous contrast media. We created a VNC series from the contrast-enhanced images. Images were assessed concerning image quality with a visual grading scale evaluation of the VNC series with the single-energy series as gold standard. Results. The image quality of the VNC images was rated inferior to the single-energy variant for both scanners, OR 11.5-67.3 for the Definition and OR 2.1-2.8 for the Definition Flash. Visual noise and overall quality were regarded as better with Flash than Definition. Conclusion. Image quality of VNC images obtained with the new generation of DECT is still slightly inferior compared to native images. However, the difference is smaller with the new compared to the older system.

  3. Virtual non-contrast dual-energy CT compared to single-energy CT of the urinary tract: a prospective study.

    Science.gov (United States)

    Lundin, Margareta; Lidén, Mats; Magnuson, Anders; Mohammed, Ahmed Abdulilah; Geijer, Håkan; Andersson, Torbjörn; Persson, Anders

    2012-07-01

    Dual-energy computed tomography (DECT) has been shown to be useful for subtracting bone or calcium in CT angiography and gives an opportunity to produce a virtual non-contrast-enhanced (VNC) image from a series where contrast agents have been given intravenously. High noise levels and low resolution have previously limited the diagnostic value of the VNC images created with the first generation of DECT. With the recent introduction of a second generation of DECT, there is a possibility of obtaining VNC images with better image quality at hopefully lower radiation dose compared to the previous generation. To compare the image quality of the single-energy series to a VNC series obtained with a two generations of DECT scanners. CT of the urinary tract was used as a model. Thirty patients referred for evaluation of hematuria were examined with an older system (Somatom Definition) and another 30 patients with a new generation (Somatom Definition Flash). One single-energy series was obtained before and one dual-energy series after administration of intravenous contrast media. We created a VNC series from the contrast-enhanced images. Images were assessed concerning image quality with a visual grading scale evaluation of the VNC series with the single-energy series as gold standard. The image quality of the VNC images was rated inferior to the single-energy variant for both scanners, OR 11.5-67.3 for the Definition and OR 2.1-2.8 for the Definition Flash. Visual noise and overall quality were regarded as better with Flash than Definition. Image quality of VNC images obtained with the new generation of DECT is still slightly inferior compared to native images. However, the difference is smaller with the new compared to the older system.

  4. Virtual non-contrast dual-energy CT compared to single-energy CT of the urinary tract: a prospective study

    International Nuclear Information System (INIS)

    Lundin, Margareta; Liden, Mats; Geijer, Haakan; Andersson, Torbjoern; Magnuson, Anders; Mohammed, Ahmed Abdulilah; Persson, Anders

    2012-01-01

    Background. Dual-energy computed tomography (DECT) has been shown to be useful for subtracting bone or calcium in CT angiography and gives an opportunity to produce a virtual non-contrast-enhanced (VNC) image from a series where contrast agents have been given intravenously. High noise levels and low resolution have previously limited the diagnostic value of the VNC images created with the first generation of DECT. With the recent introduction of a second generation of DECT, there is a possibility of obtaining VNC images with better image quality at hopefully lower radiation dose compared to the previous generation. Purpose. To compare the image quality of the single-energy series to a VNC series obtained with a two generations of DECT scanners. CT of the urinary tract was used as a model. Material and Methods. Thirty patients referred for evaluation of hematuria were examined with an older system (Somatom Definition) and another 30 patients with a new generation (Somatom Definition Flash). One single-energy series was obtained before and one dual-energy series after administration of intravenous contrast media. We created a VNC series from the contrast-enhanced images. Images were assessed concerning image quality with a visual grading scale evaluation of the VNC series with the single-energy series as gold standard. Results. The image quality of the VNC images was rated inferior to the single-energy variant for both scanners, OR 11.5-67.3 for the Definition and OR 2.1-2.8 for the Definition Flash. Visual noise and overall quality were regarded as better with Flash than Definition. Conclusion. Image quality of VNC images obtained with the new generation of DECT is still slightly inferior compared to native images. However, the difference is smaller with the new compared to the older system

  5. Technical Note: Improved CT number stability across patient size using dual-energy CT virtual monoenergetic imaging

    International Nuclear Information System (INIS)

    Michalak, Gregory; Grimes, Joshua; Fletcher, Joel; Yu, Lifeng; Leng, Shuai; McCollough, Cynthia; Halaweish, Ahmed

    2016-01-01

    Purpose: The purpose of this study was to evaluate, over a wide range of phantom sizes, CT number stability achieved using two techniques for generating dual-energy computed tomography (DECT) virtual monoenergetic images. Methods: Water phantoms ranging in lateral diameter from 15 to 50 cm and containing a CT number test object were scanned on a DSCT scanner using both single-energy (SE) and dual-energy (DE) techniques. The SE tube potentials were 70, 80, 90, 100, 110, 120, 130, 140, and 150 kV; the DE tube potential pairs were 80/140, 70/150Sn, 80/150Sn, 90/150Sn, and 100/150Sn kV (Sn denotes that the 150 kV beam was filtered with a 0.6 mm tin filter). Virtual monoenergetic images at energies ranging from 40 to 140 keV were produced from the DECT data using two algorithms, monoenergetic (mono) and monoenergetic plus (mono+). Particularly in large phantoms, water CT number errors and/or artifacts were observed; thus, datasets with water CT numbers outside ±10 HU or with noticeable artifacts were excluded from the study. CT numbers were measured to determine CT number stability across all phantom sizes. Results: Data exclusions were generally limited to cases when a SE or DE technique with a tube potential of less than 90 kV was used to scan a phantom larger than 30 cm. The 90/150Sn DE technique provided the most accurate water background over the large range of phantom sizes evaluated. Mono and mono+ provided equally improved CT number stability as a function of phantom size compared to SE; the average deviation in CT number was only 1.4% using 40 keV and 1.8% using 70 keV, while SE had an average deviation of 11.8%. Conclusions: The authors’ report demonstrates, across all phantom sizes, the improvement in CT number stability achieved with mono and mono+ relative to SE

  6. Technical Note: Improved CT number stability across patient size using dual-energy CT virtual monoenergetic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Michalak, Gregory; Grimes, Joshua; Fletcher, Joel; Yu, Lifeng; Leng, Shuai; McCollough, Cynthia, E-mail: mccollough.cynthia@mayo.edu [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Halaweish, Ahmed [Siemens Medical Solutions, Malvern, Pennsylvania 19355 (United States)

    2016-01-15

    Purpose: The purpose of this study was to evaluate, over a wide range of phantom sizes, CT number stability achieved using two techniques for generating dual-energy computed tomography (DECT) virtual monoenergetic images. Methods: Water phantoms ranging in lateral diameter from 15 to 50 cm and containing a CT number test object were scanned on a DSCT scanner using both single-energy (SE) and dual-energy (DE) techniques. The SE tube potentials were 70, 80, 90, 100, 110, 120, 130, 140, and 150 kV; the DE tube potential pairs were 80/140, 70/150Sn, 80/150Sn, 90/150Sn, and 100/150Sn kV (Sn denotes that the 150 kV beam was filtered with a 0.6 mm tin filter). Virtual monoenergetic images at energies ranging from 40 to 140 keV were produced from the DECT data using two algorithms, monoenergetic (mono) and monoenergetic plus (mono+). Particularly in large phantoms, water CT number errors and/or artifacts were observed; thus, datasets with water CT numbers outside ±10 HU or with noticeable artifacts were excluded from the study. CT numbers were measured to determine CT number stability across all phantom sizes. Results: Data exclusions were generally limited to cases when a SE or DE technique with a tube potential of less than 90 kV was used to scan a phantom larger than 30 cm. The 90/150Sn DE technique provided the most accurate water background over the large range of phantom sizes evaluated. Mono and mono+ provided equally improved CT number stability as a function of phantom size compared to SE; the average deviation in CT number was only 1.4% using 40 keV and 1.8% using 70 keV, while SE had an average deviation of 11.8%. Conclusions: The authors’ report demonstrates, across all phantom sizes, the improvement in CT number stability achieved with mono and mono+ relative to SE.

  7. Dual- and Multi-Energy CT: Principles, Technical Approaches, and Clinical Applications

    Science.gov (United States)

    Leng, Shuai; Yu, Lifeng; Fletcher, Joel G.

    2015-01-01

    In x-ray computed tomography (CT), materials having different elemental compositions can be represented by identical pixel values on a CT image (ie, CT numbers), depending on the mass density of the material. Thus, the differentiation and classification of different tissue types and contrast agents can be extremely challenging. In dual-energy CT, an additional attenuation measurement is obtained with a second x-ray spectrum (ie, a second “energy”), allowing the differentiation of multiple materials. Alternatively, this allows quantification of the mass density of two or three materials in a mixture with known elemental composition. Recent advances in the use of energy-resolving, photon-counting detectors for CT imaging suggest the ability to acquire data in multiple energy bins, which is expected to further improve the signal-to-noise ratio for material-specific imaging. In this review, the underlying motivation and physical principles of dual- or multi-energy CT are reviewed and each of the current technical approaches is described. In addition, current and evolving clinical applications are introduced. © RSNA, 2015 PMID:26302388

  8. Gas scintillation glass GEM detector for high-resolution X-ray imaging and CT

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, T., E-mail: fujiwara-t@aist.go.jp [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Mitsuya, Y. [Nuclear Professional School, The University of Tokyo, Tokai, Naka, Ibaraki 319-1188 (Japan); Fushie, T. [Radiment Lab. Inc., Setagaya, Tokyo 156-0044 (Japan); Murata, K.; Kawamura, A.; Koishikawa, A. [XIT Co., Naruse, Machida, Tokyo 194-0045 (Japan); Toyokawa, H. [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Takahashi, H. [Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8654 (Japan)

    2017-04-01

    A high-spatial-resolution X-ray-imaging gaseous detector has been developed with a single high-gas-gain glass gas electron multiplier (G-GEM), scintillation gas, and optical camera. High-resolution X-ray imaging of soft elements is performed with a spatial resolution of 281 µm rms and an effective area of 100×100 mm. In addition, high-resolution X-ray 3D computed tomography (CT) is successfully demonstrated with the gaseous detector. It shows high sensitivity to low-energy X-rays, which results in high-contrast radiographs of objects containing elements with low atomic numbers. In addition, the high yield of scintillation light enables fast X-ray imaging, which is an advantage for constructing CT images with low-energy X-rays.

  9. Energy dispersive CdTe and CdZnTe detectors for spectral clinical CT and NDT applications

    Energy Technology Data Exchange (ETDEWEB)

    Barber, W.C., E-mail: william.barber@dxray.com [DxRay, Inc., Northridge, CA (United States); Interon AS, Asker (Norway); Wessel, J.C. [DxRay, Inc., Northridge, CA (United States); Interon AS, Asker (Norway); Nygard, E. [Interon AS, Asker (Norway); Iwanczyk, J.S. [DxRay, Inc., Northridge, CA (United States)

    2015-06-01

    We are developing room temperature compound semiconductor detectors for applications in energy-resolved high-flux single x-ray photon-counting spectral computed tomography (CT), including functional imaging with nanoparticle contrast agents for medical applications and non-destructive testing (NDT) for security applications. Energy-resolved photon-counting can provide reduced patient dose through optimal energy weighting for a particular imaging task in CT, functional contrast enhancement through spectroscopic imaging of metal nanoparticles in CT, and compositional analysis through multiple basis function material decomposition in CT and NDT. These applications produce high input count rates from an x-ray generator delivered to the detector. Therefore, in order to achieve energy-resolved single photon counting in these applications, a high output count rate (OCR) for an energy-dispersive detector must be achieved at the required spatial resolution and across the required dynamic range for the application. The required performance in terms of the OCR, spatial resolution, and dynamic range must be obtained with sufficient field of view (FOV) for the application thus requiring the tiling of pixel arrays and scanning techniques. Room temperature cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) compound semiconductors, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel provided the sensors are designed for rapid signal formation across the x-ray energy ranges of the application at the required energy and spatial resolutions, and at a sufficiently high detective quantum efficiency (DQE). We have developed high-flux energy-resolved photon-counting x-ray imaging array sensors using pixellated CdTe and CdZnTe semiconductors optimized for clinical CT and security NDT. We have also fabricated high

  10. Experimental verification of ion stopping power prediction from dual energy CT data in tissue surrogates

    Science.gov (United States)

    Farace, Paolo

    2014-11-01

    A two-steps procedure is presented to convert dual-energy CT data to stopping power ratio (SPR), relative to water. In the first step the relative electron density (RED) is calculated from dual-energy CT-numbers by means of a bi-linear relationship: RED = a HUscH + b HUscL + c, where HUscH and HUscL are scaled units (HUsc = HU + 1000) acquired at high and low energy respectively, and the three parameters a, b and c has to be determined for each CT scanner. In the second step the RED values were converted into SPR by means of published poly-line functions, which are invariant as they do not depend on a specific CT scanner. The comparison with other methods provides encouraging results, with residual SPR error on human tissue within 1%. The distinctive features of the proposed method are its simplicity and the generality of the conversion functions.

  11. Experimental verification of ion stopping power prediction from dual energy CT data in tissue surrogates.

    Science.gov (United States)

    Farace, Paolo

    2014-11-21

    A two-steps procedure is presented to convert dual-energy CT data to stopping power ratio (SPR), relative to water. In the first step the relative electron density (RED) is calculated from dual-energy CT-numbers by means of a bi-linear relationship: RED=a HUscH+b HUscL+c, where HUscH and HUscL are scaled units (HUsc=HU+1000) acquired at high and low energy respectively, and the three parameters a, b and c has to be determined for each CT scanner. In the second step the RED values were converted into SPR by means of published poly-line functions, which are invariant as they do not depend on a specific CT scanner. The comparison with other methods provides encouraging results, with residual SPR error on human tissue within 1%. The distinctive features of the proposed method are its simplicity and the generality of the conversion functions.

  12. Dual energy CT for the assessment of lung perfusion-Correlation to scintigraphy

    International Nuclear Information System (INIS)

    Thieme, Sven F.; Becker, Christoph R.; Hacker, Marcus; Nikolaou, Konstantin; Reiser, Maximilian F.; Johnson, Thorsten R.C.

    2008-01-01

    Purpose of this study was to determine the diagnostic value of dual energy CT in the assessment of pulmonary perfusion with reference to pulmonary perfusion scintigraphy. Thirteen patients received both dual energy CT (DECT) angiography (Somatom Definition, Siemens) and ventilation/perfusion scintigraphy. Median time between scans was 3 days (range, 0-90). DECT perfusion maps were generated based on the spectral properties of iodine. Two blinded observes assessed DECT angiograms, perfusion maps and scintigrams for presence and location of perfusion defects. The results were compared by patient and by segment, and diagnostic accuracy of DECT perfusion imaging was calculated regarding scintigraphy as standard of reference. Diagnostic accuracy per patient showed 75% sensitivity, 80% specificity and a negative predictive value of 66%. Sensitivity per segment amounted to 83% with 99% specificity, with 93% negative predictive value. Peripheral parts of the lungs were not completely covered by the 80 kVp detector in 85% of patients. CTA identified corresponding emboli in 66% of patients with concordant perfusion defects in DECT and scintigraphy. Dual energy CT perfusion imaging is able to display pulmonary perfusion defects with good agreement to scintigraphic findings. DECT can provide a pulmonary CT angiogram, high-resolution morphology of the lung parenchyma and perfusion information in one single exam

  13. Dual energy CT for the assessment of lung perfusion-Correlation to scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Thieme, Sven F.; Becker, Christoph R. [Department of Clinical Radiology, Ludwig-Maximilians-University of Munich (Germany); Hacker, Marcus [Department of Nuclear Medicine, Ludwig-Maximilians-University of Munich (Germany); Nikolaou, Konstantin; Reiser, Maximilian F. [Department of Clinical Radiology, Ludwig-Maximilians-University of Munich (Germany); Johnson, Thorsten R.C. [Department of Clinical Radiology, Ludwig-Maximilians-University of Munich (Germany)], E-mail: thorsten.johnson@med.uni-muenchen.de

    2008-12-15

    Purpose of this study was to determine the diagnostic value of dual energy CT in the assessment of pulmonary perfusion with reference to pulmonary perfusion scintigraphy. Thirteen patients received both dual energy CT (DECT) angiography (Somatom Definition, Siemens) and ventilation/perfusion scintigraphy. Median time between scans was 3 days (range, 0-90). DECT perfusion maps were generated based on the spectral properties of iodine. Two blinded observes assessed DECT angiograms, perfusion maps and scintigrams for presence and location of perfusion defects. The results were compared by patient and by segment, and diagnostic accuracy of DECT perfusion imaging was calculated regarding scintigraphy as standard of reference. Diagnostic accuracy per patient showed 75% sensitivity, 80% specificity and a negative predictive value of 66%. Sensitivity per segment amounted to 83% with 99% specificity, with 93% negative predictive value. Peripheral parts of the lungs were not completely covered by the 80 kVp detector in 85% of patients. CTA identified corresponding emboli in 66% of patients with concordant perfusion defects in DECT and scintigraphy. Dual energy CT perfusion imaging is able to display pulmonary perfusion defects with good agreement to scintigraphic findings. DECT can provide a pulmonary CT angiogram, high-resolution morphology of the lung parenchyma and perfusion information in one single exam.

  14. Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT

    International Nuclear Information System (INIS)

    Yu Lifeng; Primak, Andrew N.; Liu Xin; McCollough, Cynthia H.

    2009-01-01

    In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of non-material-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans.

  15. Usefulness of multi-plane dynamic subtraction CT (MPDS-CT) for intracranial high density lesions

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, Ryo; Kumazaki, Tatsuo [Nippon Medical School, Tokyo (Japan)

    1996-02-01

    We present a new CT technique using the high speed CT scanner in detection and evaluation of temporal and spatial contrast enhancement of intracranial high density lesions. A multi-plane dynamic subtraction CT (MPDS-CT) was performed in 21 patients with intracranial high density lesions. These lesions consisted of 10 brain tumors, 7 intracerebral hemorrhages and 4 vascular malformations (2 untreated, 2 post-embolization). Baseline study was first performed, and 5 sequential planes of covering total high density lesions were selected. After obtaining the 5 sequential CT images as mask images, three series of multi-plane dynamic CT were performed for the same 5 planes with an intravenous bolus injection of contrast medium. MPDS-CT images were reconstructed by subtracting dynamic CT images from the mask ones. MPDS-CT were compared with conventional contrast-enhanced CT. MPDS-CT images showed the definite contrast enhancement of high density brain tumors and vascular malformations which were not clearly identified on conventional contrast-enhanced CT images because of calcified or hemorrhagic lesions and embolic materials, enabling us to eliminate enhanced abnormalities with non-enhanced areas such as unusual intracerebral hemorrhages. MPDS-CT will provide us further accurate and objective information and will be greatly helpful for interpreting pathophysiologic condition. (author).

  16. Virtual Non-Contrast CT Using Dual-Energy Spectral CT: Feasibility of Coronary Artery Calcium Scoring

    OpenAIRE

    Song, Inyoung; Yi, Jeong Geun; Park, Jeong Hee; Kim, Sung Mok; Lee, Kyung Soo; Chung, Myung Jin

    2016-01-01

    Objective To evaluate the feasibility of coronary artery calcium scoring based on three virtual noncontrast-enhanced (VNC) images derived from single-source spectral dual-energy CT (DECT) as compared with true noncontrast-enhanced (TNC) images. Materials and Methods This prospective study was conducted with the approval of our Institutional Review Board. Ninety-seven patients underwent noncontrast CT followed by contrast-enhanced chest CT using single-source spectral DECT. Iodine eliminated V...

  17. Xenon ventilation CT using dual-source and dual-energy technique in children with bronchiolitis obliterans: correlation of xenon and CT density values with pulmonary function test results

    International Nuclear Information System (INIS)

    Goo, Hyun Woo; Yang, Dong Hyun; Seo, Joon Beom; Chae, Eun Jin; Lee, Jeongjin; Hong, Soo-Jong; Yu, Jinho; Kim, Byoung-Ju; Krauss, Bernhard

    2010-01-01

    Xenon ventilation CT using dual-source and dual-energy technique is a recently introduced, promising functional lung imaging method. To expand its clinical applications evidence of additional diagnostic value of xenon ventilation CT over conventional chest CT is required. To evaluate the usefulness of xenon ventilation CT using dual-source and dual-energy technique in children with bronchiolitis obliterans (BO). Seventeen children (age 7-18 years; 11 boys) with BO underwent xenon ventilation CT using dual-source and dual-energy technique. Xenon and CT density values were measured in normal and hyperlucent lung regions on CT and were compared between the two regions. Volumes of hyperlucent regions and ventilation defects were calculated with thresholds determined by visual and histogram-based analysis. Indexed volumes of hyperlucent lung regions and ventilation defects were correlated with pulmonary function test results. Effective doses of xenon CT were calculated. Xenon (14.6 ± 6.4 HU vs 26.1 ± 6.5 HU; P 25-75 , (γ = -0.68-0.88, P ≤ 0.002). Volume percentages of xenon ventilation defects (35.0 ± 16.4%)] were not significantly different from those of hyperlucent lung regions (38.2 ± 18.6%). However, mismatches between the volume percentages were variable up to 21.4-33.3%. Mean effective dose of xenon CT was 1.9 ± 0.5 mSv. In addition to high-resolution anatomic information, xenon ventilation CT using dual-source and dual-energy technique demonstrates impaired regional ventilation and its heterogeneity accurately in children with BO without additional radiation exposure. (orig.)

  18. A Flexible Method for Multi-Material Decomposition of Dual-Energy CT Images.

    Science.gov (United States)

    Mendonca, Paulo R S; Lamb, Peter; Sahani, Dushyant V

    2014-01-01

    The ability of dual-energy computed-tomographic (CT) systems to determine the concentration of constituent materials in a mixture, known as material decomposition, is the basis for many of dual-energy CT's clinical applications. However, the complex composition of tissues and organs in the human body poses a challenge for many material decomposition methods, which assume the presence of only two, or at most three, materials in the mixture. We developed a flexible, model-based method that extends dual-energy CT's core material decomposition capability to handle more complex situations, in which it is necessary to disambiguate among and quantify the concentration of a larger number of materials. The proposed method, named multi-material decomposition (MMD), was used to develop two image analysis algorithms. The first was virtual unenhancement (VUE), which digitally removes the effect of contrast agents from contrast-enhanced dual-energy CT exams. VUE has the ability to reduce patient dose and improve clinical workflow, and can be used in a number of clinical applications such as CT urography and CT angiography. The second algorithm developed was liver-fat quantification (LFQ), which accurately quantifies the fat concentration in the liver from dual-energy CT exams. LFQ can form the basis of a clinical application targeting the diagnosis and treatment of fatty liver disease. Using image data collected from a cohort consisting of 50 patients and from phantoms, the application of MMD to VUE and LFQ yielded quantitatively accurate results when compared against gold standards. Furthermore, consistent results were obtained across all phases of imaging (contrast-free and contrast-enhanced). This is of particular importance since most clinical protocols for abdominal imaging with CT call for multi-phase imaging. We conclude that MMD can successfully form the basis of a number of dual-energy CT image analysis algorithms, and has the potential to improve the clinical utility

  19. Development and applications of high energy industrial computed tomography in China

    International Nuclear Information System (INIS)

    Xiao, YongShun; Chen, Zhiqiang

    2016-01-01

    In recent years, China's rapid development of high-end equipment manufacturing industry in the high-speed railway, aircraft, carrier rocket, etc. brings the growing requirements of the high quality assurance of the product. The accelerator based high-energy X-ray Industrial CT has the advantages of strong penetrating power, high sensitivity defect detection and quantitative measurement with image visualization, can meet the needs of the large complicated structure inspection demands. This paper introduces the current research and development status of high energy industrial CT system in China. Research achievements by the Tsinghua University and the Granpect company are discussed, including the ICT system design, high-power LINAC accelerator X-ray source and high detection efficiency detector development, fast and accurate reconstruction algorithms research, etc. This paper also introduces the particularized NDT applications from dozens of industrial CT systems made by Granpect in China, including welding structure nondestructive testing, assembly quality inspection, reverse engineering, scientific research and other applications. Then the future development and application of high energy industrial CT is prospected.

  20. Technical Note: Insertion of digital lesions in the projection domain for dual-source, dual-energy CT.

    Science.gov (United States)

    Ferrero, Andrea; Chen, Baiyu; Li, Zhoubo; Yu, Lifeng; McCollough, Cynthia

    2017-05-01

    To compare algorithms performing material decomposition and classification in dual-energy CT, it is desirable to know the ground truth of the lesion to be analyzed in real patient data. In this work, we developed and validated a framework to insert digital lesions of arbitrary chemical composition into patient projection data acquired on a dual-source, dual-energy CT system. A model that takes into account beam-hardening effects was developed to predict the CT number of objects with known chemical composition. The model utilizes information about the x-ray energy spectra, the patient/phantom attenuation, and the x-ray detector energy response. The beam-hardening model was validated on samples of iodine (I) and calcium (Ca) for a second-generation dual-source, dual-energy CT scanner for all tube potentials available and a wide range of patient sizes. The seven most prevalent mineral components of renal stones were modeled and digital stones were created with CT numbers computed for each patient/phantom size and x-ray energy spectra using the developed beam-hardening model. Each digital stone was inserted in the dual-energy projection data of a water phantom scanned on a dual-source scanner and reconstructed with the routine algorithms in use in our practice. The geometry of the forward projection for dual-energy data was validated by comparing CT number accuracy and high-contrast resolution of simulated dual-energy CT data of the ACR phantom with experimentally acquired data. The beam-hardening model and forward projection method accurately predicted the CT number of I and Ca over a wide range of tube potentials and phantom sizes. The images reconstructed after the insertion of digital kidney stones were consistent with the images reconstructed from the scanner, and the CT number ratios for different kidney stone types were consistent with data in the literature. A sample application of the proposed tool was also demonstrated. A framework was developed and validated

  1. Energy spectrum measurement of high power and high energy(6 and 9 MeV) pulsed x-ray source for industrial use

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, Hiroyuki [Hitachi, Ltd. Power Systems Company, Ibaraki (Japan); Murata, Isao [Graduate School of Engineering, Osaka University, Osaka (Japan)

    2016-06-15

    Industrial X-ray CT system is normally applied to non-destructive testing (NDT) for industrial product made from metal. Furthermore there are some special CT systems, which have an ability to inspect nuclear fuel assemblies or rocket motors, using high power and high energy (more than 6 MeV) pulsed X-ray source. In these case, pulsed X-ray are produced by the electron linear accelerator, and a huge number of photons with a wide energy spectrum are produced within a very short period. Consequently, it is difficult to measure the X-ray energy spectrum for such accelerator-based X-ray sources using simple spectrometry. Due to this difficulty, unexpected images and artifacts which lead to incorrect density information and dimensions of specimens cannot be avoided in CT images. For getting highly precise CT images, it is important to know the precise energy spectrum of emitted X-rays. In order to realize it we investigated a new approach utilizing the Bayesian estimation method combined with an attenuation curve measurement using step shaped attenuation material. This method was validated by precise measurement of energy spectrum from a 1 MeV electron accelerator. In this study, to extend the applicable X-ray energy range we tried to measure energy spectra of X-ray sources from 6 and 9 MeV linear accelerators by using the recently developed method. In this study, an attenuation curves are measured by using a step-shaped attenuation materials of aluminum and steel individually, and the each X-ray spectrum is reconstructed from the measured attenuation curve by the spectrum type Bayesian estimation method. The obtained result shows good agreement with simulated spectra, and the presently developed technique is adaptable for high energy X-ray source more than 6 MeV.

  2. CT findings of pancreatic carcinoma. Evaluation with the combined method of early enhancement CT and high dose enhancement CT

    International Nuclear Information System (INIS)

    Itoh, Shigeki; Endo, Tokiko; Isomura, Takayuki; Ishigaki, Takeo; Ikeda, Mitsuru; Senda, Kouhei.

    1995-01-01

    Computed tomographic (CT) findings of pancreatic ductal adenocarcinoma were studied with the combined method of early enhancement CT and high dose enhancement CT in 72 carcinomas. Common Findings were change in pancreatic contour, abnormal attenuation in a tumor and dilatation of the main pancreatic duct. The incidence of abnormal attenuation and dilatation of the main pancreatic duct and bile duct was constant regardless of tumor size. The finding of hypoattenuation at early enhancement CT was most useful for demonstrating a carcinoma. However, this finding was negative in ten cases, five of which showed inhomogenous hyperattenuation at high dose enhancement CT. The detection of change in pancreatic contour and dilatation of the main pancreatic duct was most frequent at high dose enhancement CT. The finding of change in pancreatic contour and/or abnormal attenuation in a tumor could be detected in 47 cases at plain CT, 66 at early enhancement CT and 65 at high dose enhancement CT. Since the four cases in which neither finding was detected by any CT method showed dilatated main pancreatic duct, there was no case without abnormal CT findings. This combined CT method will be a reliable diagnostic technique in the imaging of pancreatic carcinoma. (author)

  3. Low-dose dual-energy cone-beam CT using a total-variation minimization algorithm

    International Nuclear Information System (INIS)

    Min, Jong Hwan

    2011-02-01

    Dual-energy cone-beam CT is an important imaging modality in diagnostic applications, and may also find its use in other application such as therapeutic image guidance. Despite of its clinical values, relatively high radiation dose of dual-energy scan may pose a challenge to its wide use. In this work, we investigated a low-dose, pre-reconstruction type of dual-energy cone-beam CT (CBCT) using a total-variation minimization algorithm for image reconstruction. An empirical dual-energy calibration method was used to prepare material-specific projection data. Raw data at high and low tube voltages are converted into a set of basis functions which can be linearly combined to produce material-specific data using the coefficients obtained through the calibration process. From much fewer views than are conventionally used, material specific images are reconstructed by use of the total-variation minimization algorithm. An experimental study was performed to demonstrate the feasibility of the proposed method using a micro-CT system. We have reconstructed images of the phantoms from only 90 projections acquired at tube voltages of 40 kVp and 90 kVp each. Aluminum-only and acryl-only images were successfully decomposed. We evaluated the quality of the reconstructed images by use of contrast-to-noise ratio and detectability. A low-dose dual-energy CBCT can be realized via the proposed method by greatly reducing the number of projections

  4. WE-AB-202-08: Feasibility of Single-Inhalation/Single-Energy Xenon CT for High-Resolution Imaging of Regional Lung Ventilation in Humans

    International Nuclear Information System (INIS)

    Pinkham, D; Schueler, E; Diehn, M; Mittra, E; Loo, B; Maxim, P; Negahdar, M; Yamamoto, T

    2016-01-01

    Purpose: To demonstrate the efficacy of a novel functional lung imaging method that utilizes single-inhalation, single-energy xenon CT (Xe-CT) lung ventilation scans, and to compare it against the current clinical standard, ventilation single-photon emission CT (V-SPECT). Methods: In an IRB-approved clinical study, 14 patients undergoing thoracic radiotherapy received two successive single inhalation, single energy (80keV) CT images of the entire lung using 100% oxygen and a 70%/30% xenon-oxygen mixture. A subset of ten patients also received concurrent SPECT ventilation scans. Anatomic reproducibility between the two scans was achieved using a custom video biofeedback apparatus. The CT images were registered to each other by deformable registration, and a calculated difference image served as surrogate xenon ventilation map. Both lungs were partitioned into twelve sectors, and a sector-wise correlation was performed between the xenon and V-SPECT scans. A linear regression model was developed with forced expiratory volume (FEV) as a predictor and the coefficient of variation (CoV) as the outcome. Results: The ventilation comparison for five of the patients had either moderate to strong Pearson correlation coefficients (0.47 to 0.69, p<0.05). Of these, four also had moderate to strong Spearman correlation coefficients (0.46 to 0.80, p<0.03). The patients with the strongest correlation had clear regional ventilation deficits. The patient comparisons with the weakest correlations had more homogeneous ventilation distributions, and those patients also had diminished lung function as assessed by spirometry. Analysis of the relationship between CoV and FEV yielded a non-significant trend toward negative correlation (Pearson coefficient −0.60, p<0.15). Conclusion: Significant correlations were found between the Xe-CT and V-SPECT ventilation imagery. The results from this small cohort of patients indicate that single inhalation, single energy Xe-CT has the potential to

  5. WE-AB-202-08: Feasibility of Single-Inhalation/Single-Energy Xenon CT for High-Resolution Imaging of Regional Lung Ventilation in Humans

    Energy Technology Data Exchange (ETDEWEB)

    Pinkham, D; Schueler, E; Diehn, M; Mittra, E; Loo, B; Maxim, P [Stanford University School of Medicine, Palo Alto, California (United States); Negahdar, M [IBM Research Center, San Jose, California (United States); Yamamoto, T [University of California Davis Medical Center, Sacramento, CA (United States)

    2016-06-15

    Purpose: To demonstrate the efficacy of a novel functional lung imaging method that utilizes single-inhalation, single-energy xenon CT (Xe-CT) lung ventilation scans, and to compare it against the current clinical standard, ventilation single-photon emission CT (V-SPECT). Methods: In an IRB-approved clinical study, 14 patients undergoing thoracic radiotherapy received two successive single inhalation, single energy (80keV) CT images of the entire lung using 100% oxygen and a 70%/30% xenon-oxygen mixture. A subset of ten patients also received concurrent SPECT ventilation scans. Anatomic reproducibility between the two scans was achieved using a custom video biofeedback apparatus. The CT images were registered to each other by deformable registration, and a calculated difference image served as surrogate xenon ventilation map. Both lungs were partitioned into twelve sectors, and a sector-wise correlation was performed between the xenon and V-SPECT scans. A linear regression model was developed with forced expiratory volume (FEV) as a predictor and the coefficient of variation (CoV) as the outcome. Results: The ventilation comparison for five of the patients had either moderate to strong Pearson correlation coefficients (0.47 to 0.69, p<0.05). Of these, four also had moderate to strong Spearman correlation coefficients (0.46 to 0.80, p<0.03). The patients with the strongest correlation had clear regional ventilation deficits. The patient comparisons with the weakest correlations had more homogeneous ventilation distributions, and those patients also had diminished lung function as assessed by spirometry. Analysis of the relationship between CoV and FEV yielded a non-significant trend toward negative correlation (Pearson coefficient −0.60, p<0.15). Conclusion: Significant correlations were found between the Xe-CT and V-SPECT ventilation imagery. The results from this small cohort of patients indicate that single inhalation, single energy Xe-CT has the potential to

  6. Accuracy of Combined Computed Tomography Colonography and Dual Energy Iiodine Map Imaging for Detecting Colorectal masses using High-pitch Dual-source CT.

    Science.gov (United States)

    Sun, Kai; Han, Ruijuan; Han, Yang; Shi, Xuesen; Hu, Jiang; Lu, Bin

    2018-02-28

    To evaluate the diagnostic accuracy of combined computed tomography colonography (CTC) and dual-energy iodine map imaging for detecting colorectal masses using high-pitch dual-source CT, compared with optical colonography (OC) and histopathologic findings. Twenty-eight consecutive patients were prospectively enrolled in this study. All patients were underwent contrast-enhanced CTC acquisition using dual-energy mode and OC and pathologic examination. The size of the space-occupied mass, the CT value after contrast enhancement, and the iodine value were measured and statistically compared. The sensitivity, specificity, accuracy rate, and positive predictive and negative predictive values of dual-energy contrast-enhanced CTC were calculated and compared between conventional CTC and dual-energy iodine images. The iodine value of stool was significantly lower than the colonic neoplasia (P dual-energy iodine maps imaging was 95.6% (95% CI = 77.9%-99.2%). The specificity of the two methods was 42.8% (95% CI = 15.4%-93.5%) and 100% (95% CI = 47.9%-100%; P = 0.02), respectively. Compared with optical colonography and histopathology, combined CTC and dual-energy iodine maps imaging can distinguish stool and colonic neoplasia, distinguish between benign and malignant tumors initially and improve the diagnostic accuracy of CTC for colorectal cancer screening.

  7. Clinical application of in vivo treatment delivery verification based on PET/CT imaging of positron activity induced at high energy photon therapy

    Science.gov (United States)

    Janek Strååt, Sara; Andreassen, Björn; Jonsson, Cathrine; Noz, Marilyn E.; Maguire, Gerald Q., Jr.; Näfstadius, Peder; Näslund, Ingemar; Schoenahl, Frederic; Brahme, Anders

    2013-08-01

    The purpose of this study was to investigate in vivo verification of radiation treatment with high energy photon beams using PET/CT to image the induced positron activity. The measurements of the positron activation induced in a preoperative rectal cancer patient and a prostate cancer patient following 50 MV photon treatments are presented. A total dose of 5 and 8 Gy, respectively, were delivered to the tumors. Imaging was performed with a 64-slice PET/CT scanner for 30 min, starting 7 min after the end of the treatment. The CT volume from the PET/CT and the treatment planning CT were coregistered by matching anatomical reference points in the patient. The treatment delivery was imaged in vivo based on the distribution of the induced positron emitters produced by photonuclear reactions in tissue mapped on to the associated dose distribution of the treatment plan. The results showed that spatial distribution of induced activity in both patients agreed well with the delivered beam portals of the treatment plans in the entrance subcutaneous fat regions but less so in blood and oxygen rich soft tissues. For the preoperative rectal cancer patient however, a 2 ± (0.5) cm misalignment was observed in the cranial-caudal direction of the patient between the induced activity distribution and treatment plan, indicating a beam patient setup error. No misalignment of this kind was seen in the prostate cancer patient. However, due to a fast patient setup error in the PET/CT scanner a slight mis-position of the patient in the PET/CT was observed in all three planes, resulting in a deformed activity distribution compared to the treatment plan. The present study indicates that the induced positron emitters by high energy photon beams can be measured quite accurately using PET imaging of subcutaneous fat to allow portal verification of the delivered treatment beams. Measurement of the induced activity in the patient 7 min after receiving 5 Gy involved count rates which were about

  8. Proton tracking in a high-granularity Digital Tracking Calorimeter for proton CT purposes

    Science.gov (United States)

    Pettersen, H. E. S.; Alme, J.; Biegun, A.; van den Brink, A.; Chaar, M.; Fehlker, D.; Meric, I.; Odland, O. H.; Peitzmann, T.; Rocco, E.; Ullaland, K.; Wang, H.; Yang, S.; Zhang, C.; Röhrich, D.

    2017-07-01

    Radiation therapy with protons as of today utilizes information from x-ray CT in order to estimate the proton stopping power of the traversed tissue in a patient. The conversion from x-ray attenuation to proton stopping power in tissue introduces range uncertainties of the order of 2-3% of the range, uncertainties that are contributing to an increase of the necessary planning margins added to the target volume in a patient. Imaging methods and modalities, such as Dual Energy CT and proton CT, have come into consideration in the pursuit of obtaining an as good as possible estimate of the proton stopping power. In this study, a Digital Tracking Calorimeter is benchmarked for proof-of-concept for proton CT purposes. The Digital Tracking Calorimeter was originally designed for the reconstruction of high-energy electromagnetic showers for the ALICE-FoCal project. The presented prototype forms the basis for a proton CT system using a single technology for tracking and calorimetry. This advantage simplifies the setup and reduces the cost of a proton CT system assembly, and it is a unique feature of the Digital Tracking Calorimeter concept. Data from the AGORFIRM beamline at KVI-CART in Groningen in the Netherlands and Monte Carlo simulation results are used to in order to develop a tracking algorithm for the estimation of the residual ranges of a high number of concurrent proton tracks. High energy protons traversing the detector leave a track through the sensor layers. These tracks are spread out through charge diffusion processes. A charge diffusion model is applied for acquisition of estimates of the deposited energy of the protons in each sensor layer by using the size of the charge diffused area. A model fit of the Bragg Curve is applied to each reconstructed track and through this, estimating the residual range of each proton. The range of the individual protons can at present be estimated with a resolution of 4%. The readout system for this prototype is able to

  9. Proton tracking in a high-granularity Digital Tracking Calorimeter for proton CT purposes

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, H.E.S., E-mail: helge.pettersen@helse-bergen.no [Department of Oncology and Medical Physics, Haukeland University Hospital, Postbox 1400, 5021 Bergen (Norway); Department of Physics and Technology, University of Bergen, Postbox 7803, 5020 Bergen (Norway); Alme, J. [Department of Physics and Technology, University of Bergen, Postbox 7803, 5020 Bergen (Norway); Biegun, A. [Kernfysisch Versneller Instituut, University of Groningen, NL-9747 AA Groningen (Netherlands); Brink, A. van den [Nikhef, Utrecht University, Postbox 41882, 1009 DB Amsterdam (Netherlands); Chaar, M.; Fehlker, D. [Department of Physics and Technology, University of Bergen, Postbox 7803, 5020 Bergen (Norway); Meric, I. [Department of Electrical Engineering, Bergen University College, Postbox 7030, 5020 Bergen (Norway); Odland, O.H. [Department of Oncology and Medical Physics, Haukeland University Hospital, Postbox 1400, 5021 Bergen (Norway); Peitzmann, T.; Rocco, E. [Nikhef, Utrecht University, Postbox 41882, 1009 DB Amsterdam (Netherlands); Ullaland, K. [Department of Physics and Technology, University of Bergen, Postbox 7803, 5020 Bergen (Norway); Wang, H. [Nikhef, Utrecht University, Postbox 41882, 1009 DB Amsterdam (Netherlands); Yang, S. [Department of Physics and Technology, University of Bergen, Postbox 7803, 5020 Bergen (Norway); Zhang, C. [Nikhef, Utrecht University, Postbox 41882, 1009 DB Amsterdam (Netherlands); Röhrich, D. [Department of Physics and Technology, University of Bergen, Postbox 7803, 5020 Bergen (Norway)

    2017-07-11

    Radiation therapy with protons as of today utilizes information from x-ray CT in order to estimate the proton stopping power of the traversed tissue in a patient. The conversion from x-ray attenuation to proton stopping power in tissue introduces range uncertainties of the order of 2–3% of the range, uncertainties that are contributing to an increase of the necessary planning margins added to the target volume in a patient. Imaging methods and modalities, such as Dual Energy CT and proton CT, have come into consideration in the pursuit of obtaining an as good as possible estimate of the proton stopping power. In this study, a Digital Tracking Calorimeter is benchmarked for proof-of-concept for proton CT purposes. The Digital Tracking Calorimeter was originally designed for the reconstruction of high-energy electromagnetic showers for the ALICE-FoCal project. The presented prototype forms the basis for a proton CT system using a single technology for tracking and calorimetry. This advantage simplifies the setup and reduces the cost of a proton CT system assembly, and it is a unique feature of the Digital Tracking Calorimeter concept. Data from the AGORFIRM beamline at KVI-CART in Groningen in the Netherlands and Monte Carlo simulation results are used to in order to develop a tracking algorithm for the estimation of the residual ranges of a high number of concurrent proton tracks. High energy protons traversing the detector leave a track through the sensor layers. These tracks are spread out through charge diffusion processes. A charge diffusion model is applied for acquisition of estimates of the deposited energy of the protons in each sensor layer by using the size of the charge diffused area. A model fit of the Bragg Curve is applied to each reconstructed track and through this, estimating the residual range of each proton. The range of the individual protons can at present be estimated with a resolution of 4%. The readout system for this prototype is able to

  10. Pulmonary ventilation and perfusion imaging with dual-energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Thieme, Sven F. [Klinikum Grosshadern, Department of Clinical Radiology, Ludwig Maximilians University, Muenchen (Germany); Klinikum Grosshadern, Institut fuer Klinische Radiologie, LMU Muenchen, Muenchen (Germany); Hoegl, Sandra; Fisahn, Juergen; Irlbeck, Michael [Klinikum Grosshadern, Department of Anesthesiology, Ludwig Maximilians University, Muenchen (Germany); Nikolaou, Konstantin; Maxien, Daniel; Reiser, Maximilian F.; Becker, Christoph R.; Johnson, Thorsten R.C. [Klinikum Grosshadern, Department of Clinical Radiology, Ludwig Maximilians University, Muenchen (Germany)

    2010-12-15

    To evaluate the feasibility of dual-energy CT (DECT) ventilation imaging in combination with DE perfusion mapping for a comprehensive assessment of ventilation, perfusion, morphology and structure of the pulmonary parenchyma. Two dual-energy CT acquisitions for xenon-enhanced ventilation and iodine-enhanced perfusion mapping were performed in patients under artificial respiration. Parenchymal xenon and iodine distribution were mapped and correlated with structural or vascular abnormalities. In all datasets, image quality was sufficient for a comprehensive image reading of the pulmonary CTA images, lung window images and pulmonary functional parameter maps and led to expedient results in each patient. With dual-source CT systems, DECT of the lung with iodine or xenon administration is technically feasible and makes it possible to depict the regional iodine or xenon distribution representing the local perfusion and ventilation. (orig.)

  11. Material Discriminated X-Ray CT System by Using New X-Ray Imager with Energy Discriminate Function

    Directory of Open Access Journals (Sweden)

    Toru Aoki

    2008-04-01

    Full Text Available Material discriminated X-ray CT system has been constructed by using conventional X-ray tube (white X-ray source and photon-counting X-ray imager as an application with energy band detection. We have already reported material identify X-ray CT using K-shell edge method elsewhere. In this report the principle of material discrimination was adapted the separation of electron-density and atomic number from attenuation coefficient mapping in X-ray CT reconstructed image in two wavelength X-ray CT method using white X-ray source and energy discriminated X-ray imager by using two monochrome X-ray source method. The measurement phantom was prepared as four kinds material rods (Carbon(C, Iron(Fe, Copper(Cu, Titanium(Ti rods of 3mm-diameter inside an aluminum(Al rod of 20mm-diameter. We could observed material discriminated X-ray CT reconstructed image, however, the discrimination properties were not good than two monochrome X-ray CT method. This results was could be explained because X-ray scattering, beam-hardening and so on based on white X-ray source, which could not observe in two monochrome X-ray CT method. However, since our developed CdTe imager can be detect five energy-bands at the same time, we can use multi-band analysis to decrease the least square error margin. We will be able to obtain more high separation in atomic number mapping in X-ray CT reconstructed image by using this system.

  12. Dual-energy perfusion-CT in recurrent pancreatic cancer. Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, F.; Skornitzke, S.; Kauczor, H.U.; Stiller, W.; Klauss, M. [Heidelberg Univ. (Germany). Clinic of Diagnostic and Interventional Radiology; Hackert, T. [Heidelberg Univ. (Germany). Clinic of Surgery; Grenacher, L. [Diagnostik Muenchen (Germany). Diagnostic Imaging Center

    2016-06-15

    To evaluate the diagnostic performance of dual energy (DE) perfusion-CT for the differentiation between postoperative soft-tissue formation and tumor recurrence in patients after potentially curative pancreatic cancer resection. 24 patients with postoperative soft-tissue formation in the conventional regular follow-up CT acquisition after pancreatic cancer resection with curative intent were included prospectively. They were examined with a 64-row dual-source CT using a dynamic sequence of 34 DE acquisitions every 1.5 s (80 ml of iodinated contrast material, 370 mg/ml, flow rate 5 ml/s). Weighted average (linearly blended M0.5) 120 kVp-equivalent dual-energy perfusion image data sets were evaluated with a body-perfusion CT tool for estimating blood flow, permeability, and blood volume. Diagnosis was confirmed by histological study (n=4) and by regular follow-up. Final diagnosis was local recurrence of pancreatic cancer in 15 patients and unspecific postoperative tissue formation in 9 patients. The blood-flow values for recurrence tissue trended to be lower compared to postoperative tissue formation with 16.6 ml/100 ml/min and 24.7 ml/100 ml/min, respectively for weighted average 120 kVp-equivalent image data, which was not significant (n.s.) (p=0.06, significance level 0.05). Permeability- and blood-volume values were only slightly lower in recurrence tissue (n.s.). DE perfusion-CT is feasible in patients after pancreatic cancer resection and a promising functional imaging technique. As only a trend for lower perfusion values in local recurrence compared to unspecific postoperative alterations was found, the perfusion differences are not yet sufficient to differentiate between malignancy and unspecific postoperative alterations for this new technique. Further studies and technical improvements are needed to generate reliable data for this clinically highly relevant differentiation.

  13. Dosimetric comparison of stopping power calibration with dual-energy CT and single-energy CT in proton therapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jiahua [Department of Physics, University of Adelaide, Adelaide, SA 5005 (Australia); Penfold, Scott N., E-mail: scott.penfold@adelaide.edu.au [Department of Physics, University of Adelaide, Adelaide, SA 5005, Australia and Department of Medical Physics, Royal Adelaide Hospital, Adelaide, SA 5000 (Australia)

    2016-06-15

    Purpose: The accuracy of proton dose calculation is dependent on the ability to correctly characterize patient tissues with medical imaging. The most common method is to correlate computed tomography (CT) numbers obtained via single-energy CT (SECT) with proton stopping power ratio (SPR). CT numbers, however, cannot discriminate between a change in mass density and change in chemical composition of patient tissues. This limitation can have consequences on SPR calibration accuracy. Dual-energy CT (DECT) is receiving increasing interest as an alternative imaging modality for proton therapy treatment planning due to its ability to discriminate between changes in patient density and chemical composition. In the current work we use a phantom of known composition to demonstrate the dosimetric advantages of proton therapy treatment planning with DECT over SECT. Methods: A phantom of known composition was scanned with a clinical SECT radiotherapy CT-simulator. The phantom was rescanned at a lower X-ray tube potential to generate a complimentary DECT image set. A set of reference materials similar in composition to the phantom was used to perform a stoichiometric calibration of SECT CT number to proton SPRs. The same set of reference materials was used to perform a DECT stoichiometric calibration based on effective atomic number. The known composition of the phantom was used to assess the accuracy of SPR calibration with SECT and DECT. Intensity modulated proton therapy (IMPT) treatment plans were generated with the SECT and DECT image sets to assess the dosimetric effect of the imaging modality. Isodose difference maps and root mean square (RMS) error calculations were used to assess dose calculation accuracy. Results: SPR calculation accuracy was found to be superior, on average, with DECT relative to SECT. Maximum errors of 12.8% and 2.2% were found for SECT and DECT, respectively. Qualitative examination of dose difference maps clearly showed the dosimetric advantages

  14. TH-CD-202-04: Evaluation of Virtual Non-Contrast Images From a Novel Split-Filter Dual-Energy CT Technique

    International Nuclear Information System (INIS)

    Huang, J; Szczykutowicz, T; Bayouth, J; Miller, J

    2016-01-01

    Purpose: To compare the ability of two dual-energy CT techniques, a novel split-filter single-source technique of superior temporal resolution against an established sequential-scan technique, to remove iodine contrast from images with minimal impact on CT number accuracy. Methods: A phantom containing 8 tissue substitute materials and vials of varying iodine concentrations (1.7–20.1 mg I /mL) was imaged using a Siemens Edge CT scanner. Dual-energy virtual non-contrast (VNC) images were generated using the novel split-filter technique, in which a 120kVp spectrum is filtered by tin and gold to create high- and low-energy spectra with < 1 second temporal separation between the acquisition of low- and high-energy data. Additionally, VNC images were generated with the sequential-scan technique (80 and 140kVp) for comparison. CT number accuracy was evaluated for all materials at 15, 25, and 35mGy CTDIvol. Results: The spectral separation was greater for the sequential-scan technique than the split-filter technique with dual-energy ratios of 2.18 and 1.26, respectively. Both techniques successfully removed iodine contrast, resulting in mean CT numbers within 60HU of 0HU (split-filter) and 40HU of 0HU (sequential-scan) for all iodine concentrations. Additionally, for iodine vials of varying diameter (2–20 mm) with the same concentration (9.9 mg I /mL), the system accurately detected iodine for all sizes investigated. Both dual-energy techniques resulted in reduced CT numbers for bone materials (by >400HU for the densest bone). Increasing the imaging dose did not improve the CT number accuracy for bone in VNC images. Conclusion: VNC images from the split-filter technique successfully removed iodine contrast. These results demonstrate a potential for improving dose calculation accuracy and reducing patient imaging dose, while achieving superior temporal resolution in comparison sequential scans. For both techniques, inaccuracies in CT numbers for bone materials

  15. TH-CD-202-04: Evaluation of Virtual Non-Contrast Images From a Novel Split-Filter Dual-Energy CT Technique

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J; Szczykutowicz, T; Bayouth, J; Miller, J [University of Wisconsin, Madison, WI (United States)

    2016-06-15

    Purpose: To compare the ability of two dual-energy CT techniques, a novel split-filter single-source technique of superior temporal resolution against an established sequential-scan technique, to remove iodine contrast from images with minimal impact on CT number accuracy. Methods: A phantom containing 8 tissue substitute materials and vials of varying iodine concentrations (1.7–20.1 mg I /mL) was imaged using a Siemens Edge CT scanner. Dual-energy virtual non-contrast (VNC) images were generated using the novel split-filter technique, in which a 120kVp spectrum is filtered by tin and gold to create high- and low-energy spectra with < 1 second temporal separation between the acquisition of low- and high-energy data. Additionally, VNC images were generated with the sequential-scan technique (80 and 140kVp) for comparison. CT number accuracy was evaluated for all materials at 15, 25, and 35mGy CTDIvol. Results: The spectral separation was greater for the sequential-scan technique than the split-filter technique with dual-energy ratios of 2.18 and 1.26, respectively. Both techniques successfully removed iodine contrast, resulting in mean CT numbers within 60HU of 0HU (split-filter) and 40HU of 0HU (sequential-scan) for all iodine concentrations. Additionally, for iodine vials of varying diameter (2–20 mm) with the same concentration (9.9 mg I /mL), the system accurately detected iodine for all sizes investigated. Both dual-energy techniques resulted in reduced CT numbers for bone materials (by >400HU for the densest bone). Increasing the imaging dose did not improve the CT number accuracy for bone in VNC images. Conclusion: VNC images from the split-filter technique successfully removed iodine contrast. These results demonstrate a potential for improving dose calculation accuracy and reducing patient imaging dose, while achieving superior temporal resolution in comparison sequential scans. For both techniques, inaccuracies in CT numbers for bone materials

  16. Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT.

    Science.gov (United States)

    Paul, Jijo; Banckwitz, Rosemarie; Krauss, Bernhard; Vogl, Thomas J; Maentele, Werner; Bauer, Ralf W

    2012-04-01

    To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation. Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120kV, (2) single-source 100kV, (3) high-pitch 120kV, and (4) dual-energy with 100/Sn140kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived. DLP-based estimates differed by 4.5-16.56% and 5.2-15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04mSv. Estimates of E based on DLP work equally well for single-energy, high-pitch and dual-energy CT examinations. The tube potential definitely affects effective dose in a substantial way. Effective dose estimations by ICRP 103 and 60 for both single-energy and dual-energy examinations differ not more than 0.04mSv. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  17. In Vivo Differentiation of Complementary Contrast Media at Dual-Energy CT

    Science.gov (United States)

    Mongan, John; Rathnayake, Samira; Fu, Yanjun; Wang, Runtang; Jones, Ella F.; Gao, Dong-Wei

    2012-01-01

    Purpose: To evaluate the feasibility of using a commercially available clinical dual-energy computed tomographic (CT) scanner to differentiate the in vivo enhancement due to two simultaneously administered contrast media with complementary x-ray attenuation ratios. Materials and Methods: Approval from the institutional animal care and use committee was obtained, and National Institutes of Health guidelines for the care and use of laboratory animals were observed. Dual-energy CT was performed in a set of iodine and tungsten solution phantoms and in a rabbit in which iodinated intravenous and bismuth subsalicylate oral contrast media were administered. In addition, a second rabbit was studied after intravenous administration of iodinated and tungsten cluster contrast media. Images were processed to produce virtual monochromatic images that simulated the appearance of conventional single-energy scans, as well as material decomposition images that separate the attenuation due to each contrast medium. Results: Clear separation of each of the contrast media pairs was seen in the phantom and in both in vivo animal models. Separation of bowel lumen from vascular contrast medium allowed visualization of bowel wall enhancement that was obscured by intraluminal bowel contrast medium on conventional CT scans. Separation of two vascular contrast media in different vascular phases enabled acquisition of a perfectly coregistered CT angiogram and venous phase–enhanced CT scan simultaneously in a single examination. Conclusion: Commercially available clinical dual-energy CT scanners can help differentiate the enhancement of selected pairs of complementary contrast media in vivo. © RSNA, 2012 PMID:22778447

  18. WE-E-18C-01: Multi-Energy CT: Current Status and Recent Innovations

    International Nuclear Information System (INIS)

    Pelc, N; McCollough, C; Yu, L; Schmidt, T

    2014-01-01

    Conventional computed tomography (CT) uses a single polychromatic x-ray spectrum and energy integrating detectors, and produces images whose contrast depends on the effective attenuation coefficient of the broad spectrum beam. This can introduce errors from beam hardening and does not produce the optimal contrast-to-noise ratio. In addition, multiple materials can have the same effective attenuation coefficient, causing different materials to be indistinguishable in conventional CT images. If transmission measurements at two or more energies are obtained, even with polychromatic beams, more specific information about the object can be obtained. If the object does not contain materials with k-edges in the spectrum, the x-ray attenuation can be well-approximated by a linear combination of two processes (photoelectric absorption and Compton scattering) or, equivalently, two basis materials. For such cases, two spectral measurements suffice, although additional measurements can provide higher precision. If K-edge materials are present, additional spectral measurements can allow these materials to be isolated. Current commercial implementations use varied approaches, including two sources operating a different kVp, one source whose kVp is rapidly switched in a single scan, and a dual layer detector that can provide spectral information in every reading. Processing of the spectral information can be performed in the raw data domain or in the image domain. The process of calculating the amount of the two basis functions implicitly corrects for beam hardening and therefore can lead to improvements in quantitative accuracy. Information can be extracted to provide material specific information beyond that of conventional CT. This additional information has been shown to be important in several clinical applications, and can also lead to more efficient clinical protocols. Recent innovations in x-ray sources, detectors, and systems have made multi-energy CT much more practical

  19. High resolution CT of the chest

    Energy Technology Data Exchange (ETDEWEB)

    Barneveld Binkhuysen, F H [Eemland Hospital (Netherlands), Dept. of Radiology

    1996-12-31

    Compared to conventional CT high resolution CT (HRCT) shows several extra anatomical structures which might effect both diagnosis and therapy. The extra anatomical structures were discussed briefly in this article. (18 refs.).

  20. Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT

    International Nuclear Information System (INIS)

    Paul, Jijo; Banckwitz, Rosemarie; Krauss, Bernhard; Vogl, Thomas J.; Maentele, Werner; Bauer, Ralf W.

    2012-01-01

    Highlights: ► The dual-energy protocol delivers the lowest effective dose of the investigated protocols for standard chest CT examinations, thus enabling functional imaging (like dual-energy perfusion) and can produce weighted images without dose penalty. ► The high-pitch protocol goes along with a 16% increase in dose compared to the standard 120 kV protocol and thus should preferably be used in pediatric, acute care settings (e.g. pulmonary embolism, aortic dissection and the like) or restless patients. ► The difference in effective dose estimates between ICRP 60 and 103 is minimal. ► Tube potential definitely has an effect on estimates of effective dose. - Abstract: Purpose: To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation. Materials and methods: Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014 mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120 kV, (2) single-source 100 kV, (3) high-pitch 120 kV, and (4) dual-energy with 100/Sn140 kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived. Results: DLP-based estimates differed by 4.5–16.56% and 5.2–15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04 m

  1. Algorithm-enabled partial-angular-scan configurations for dual-energy CT.

    Science.gov (United States)

    Chen, Buxin; Zhang, Zheng; Xia, Dan; Sidky, Emil Y; Pan, Xiaochuan

    2018-05-01

    We seek to investigate an optimization-based one-step method for image reconstruction that explicitly compensates for nonlinear spectral response (i.e., the beam-hardening effect) in dual-energy CT, to investigate the feasibility of the one-step method for enabling two dual-energy partial-angular-scan configurations, referred to as the short- and half-scan configurations, on standard CT scanners without involving additional hardware, and to investigate the potential of the short- and half-scan configurations in reducing imaging dose and scan time in a single-kVp-switch full-scan configuration in which two full rotations are made for collection of dual-energy data. We use the one-step method to reconstruct images directly from dual-energy data through solving a nonconvex optimization program that specifies the images to be reconstructed in dual-energy CT. Dual-energy full-scan data are generated from numerical phantoms and collected from physical phantoms with the standard single-kVp-switch full-scan configuration, whereas dual-energy short- and half-scan data are extracted from the corresponding full-scan data. Besides visual inspection and profile-plot comparison, the reconstructed images are analyzed also in quantitative studies based upon tasks of linear-attenuation-coefficient and material-concentration estimation and of material differentiation. Following the performance of a computer-simulation study to verify that the one-step method can reconstruct numerically accurately basis and monochromatic images of numerical phantoms, we reconstruct basis and monochromatic images by using the one-step method from real data of physical phantoms collected with the full-, short-, and half-scan configurations. Subjective inspection based upon visualization and profile-plot comparison reveals that monochromatic images, which are used often in practical applications, reconstructed from the full-, short-, and half-scan data are largely visually comparable except for some

  2. Diagnosis value of dual-phase contrast enhancement CT combined with virtual non-enhanced images by dual-energy CT in clear cell renal cell carcinoma

    International Nuclear Information System (INIS)

    Ma Zhoupeng; Zhou Jianjun; Liu Xueling; Wang Chun; Zhang Shunzhuang

    2012-01-01

    Objective: To explore the diagnostic value of dual-phase contrast enhancement CT combined with virtual non-enhanced images by dual-energy CT in clear cell renal cell carcinoma. Methods: Sixty patients who were suspected of clear cell renal cell carcinoma underwent non-enhanced CT and contrast enhancement CT of early interface-phase between cortex -medulla and parenchymal phase on a dual-energy CT. The true non-enhanced kidney CT (TNCT) was performed in a single-energy acquisition mode, but the dual-phase contrast enhancement CT were performed in a dual-energy mode of 80 kV and 140 kV respectively. The virtual non-enhanced CT (VNCT) images were derived from the data of early interface phase using liver virtual non-contrast software. The diagnose according to VNCT combined dual-phase contrast enhancement CT and dual-phase contrast enhancement CT only were made respectively and compared with χ 2 test. Between the true non-contrast CT and the virtual non-contrast CT, the image quality was compared with Wilcoxon test; The radiation dose of volume CT dose index (CTDIvol) and dose length product(DLP) in a single-phase and total examination, the mean CT HU values of the tumours were compared with t test. Results: The accuracy of VNCT combined dual-phase contrast enhancement CT was higher than that of dual-phase contrast enhancement CT only [93.3% (56/60) vs.78.3% (47/60); χ 2 =5.6, P<0.05]. The detective ability (score) of VNCT was near to that of TNCT and the difference was not obvious (Z=0.00, P>0.05). The radiation dose of volume CT dose index (CTDIvol) and dose length product (DLP) in a single phase and total examination of VNCT [(8.85 ± 1.28) mGy, (196.45 ±21.12) mGy·cm, (17.69±2.35) mGy, (392.90±42.25) mGy · cm] were lower than that of TNCT [(10.20 ± 1.44) mGy,(218.29 ± 29.60) mGy · cm, (30.61 ± 3.27) mGy and (654.86 ± 88.81) mGy ·cm], t=4.21, 3.58, 23.63, 16.12 respectively, P<0.05. The mean CT HU values of tumours on VNCT images was higher than that

  3. Collateral ventilation to congenital hyperlucent lung lesions assessed on xenon-enhanced dynamic dual-energy CT: an initial experience.

    Science.gov (United States)

    Goo, Hyun Woo; Yang, Dong Hyun; Kim, Namkug; Park, Seung Il; Kim, Dong Kwan; Kim, Ellen Ai-Rhan

    2011-01-01

    We wanted to evaluate the resistance to collateral ventilation in congenital hyperlucent lung lesions and to correlate that with the anatomic findings on xenon-enhanced dynamic dual-energy CT. Xenon-enhanced dynamic dual-energy CT was successfully and safely performed in eight children (median age: 5.5 years, 4 boys and 4 girls) with congenital hyperlucent lung lesions. Functional assessment of the lung lesions on the xenon map was done, including performing a time-xenon value curve analysis and assessing the amplitude of xenon enhancement (A) value, the rate of xenon enhancement (K) value and the time of arrival value. Based on the A value, the lung lesions were categorized into high or low (A value > 10 Hounsfield unit [HU]) resistance to collateral ventilation. In addition, the morphologic CT findings of the lung lesions, including cyst, mucocele and an accessory or incomplete fissure, were assessed on the weighted-average CT images. The xenon-enhanced CT radiation dose was estimated. Five of the eight lung lesions were categorized into the high resistance group and three lesions were categorized into the low resistance group. The A and K values in the normal lung were higher than those in the low resistance group. The time of arrival values were delayed in the low resistance group. Cysts were identified in five lesions, mucocele in four, accessory fissure in three and incomplete fissure in two. Either cyst or an accessory fissure was seen in four of the five lesions showing high resistance to collateral ventilation. The xenon-enhanced CT radiation dose was 2.3 ± 0.6 mSv. Xenon-enhanced dynamic dual-energy CT can help visualize and quantitate various degrees of collateral ventilation to congenital hyperlucent lung lesions in addition to assessing the anatomic details of the lung.

  4. A unified material decomposition framework for quantitative dual- and triple-energy CT imaging.

    Science.gov (United States)

    Zhao, Wei; Vernekohl, Don; Han, Fei; Han, Bin; Peng, Hao; Yang, Yong; Xing, Lei; Min, James K

    2018-04-21

    Many clinical applications depend critically on the accurate differentiation and classi-fication of different types of materials in patient anatomy. This work introduces a unified framework for accurate nonlinear material decomposition and applies it, for the first time, in the concept of triple-energy CT (TECT) for enhanced material differentiation and classification as well as dual-energy CT METHODS: We express polychromatic projection into a linear combination of line integrals of material-selective images. The material decomposition is then turned into a problem of minimizing the least-squares difference between measured and estimated CT projections. The optimization problem is solved iteratively by updating the line integrals. The proposed technique is evaluated by using several numerical phantom measurements under different scanning protocols The triple-energy data acquisition is implemented at the scales of micro-CT and clinical CT imaging with commercial "TwinBeam" dual-source DECT configuration and a fast kV switching DECT configu-ration. Material decomposition and quantitative comparison with a photon counting detector and with the presence of a bow-tie filter are also performed. The proposed method provides quantitative material- and energy-selective images exam-ining realistic configurations for both dual- and triple-energy CT measurements. Compared to the polychromatic kV CT images, virtual monochromatic images show superior image quality. For the mouse phantom, quantitative measurements show that the differences between gadodiamide and iodine concentrations obtained using TECT and idealized photon counting CT (PCCT) are smaller than 8 mg/mL and 1 mg/mL, respectively. TECT outperforms DECT for multi-contrast CT imag-ing and is robust with respect to spectrum estimation. For the thorax phantom, the differences between the concentrations of the contrast map and the corresponding true reference values are smaller than 7 mg/mL for all of the realistic

  5. Dual energy CT of the chest: how about the dose?

    Science.gov (United States)

    Schenzle, Jan C; Sommer, Wieland H; Neumaier, Klement; Michalski, Gisela; Lechel, Ursula; Nikolaou, Konstantin; Becker, Christoph R; Reiser, Maximilian F; Johnson, Thorsten R C

    2010-06-01

    New generation Dual Source computed tomography (CT) scanners offer different x-ray spectra for Dual Energy imaging. Yet, an objective, manufacturer independent verification of the dose required for the different spectral combinations is lacking. The aim of this study was to assess dose and image noise of 2 different Dual Energy CT settings with reference to a standard chest scan and to compare image noise and contrast to noise ratios (CNR). Also, exact effective dose length products (E/DLP) conversion factors were to be established based on the objectively measured dose. An anthropomorphic Alderson phantom was assembled with thermoluminescent detectors (TLD) and its chest was scanned on a Dual Source CT (Siemens Somatom Definition) in dual energy mode at 140 and 80 kVp with 14 x 1.2 mm collimation. The same was performed on another Dual Source CT (Siemens Somatom Definition Flash) at 140 kVp with 0.8 mm tin filter (Sn) and 100 kVp at 128 x 0.6 mm collimation. Reference scans were obtained at 120 kVp with 64 x 0.6 mm collimation at equivalent CT dose index of 5.4 mGy*cm. Syringes filled with water and 17.5 mg iodine/mL were scanned with the same settings. Dose was calculated from the TLD measurements and the dose length products of the scanner. Image noise was measured in the phantom scans and CNR and spectral contrast were determined in the iodine and water samples. E/DLP conversion factors were calculated as ratio between the measured dose form the TLDs and the dose length product given in the patient protocol. The effective dose measured with TLDs was 2.61, 2.69, and 2.70 mSv, respectively, for the 140/80 kVp, the 140 Sn/100 kVp, and the standard 120 kVp scans. Image noise measured in the average images of the phantom scans was 11.0, 10.7, and 9.9 HU (P > 0.05). The CNR of iodine with optimized image blending was 33.4 at 140/80 kVp, 30.7 at 140Sn/100 kVp and 14.6 at 120 kVp. E/DLP conversion factors were 0.0161 mSv/mGy*cm for the 140/80 kVp protocol, 0.0181 m

  6. Is energy imparted a good measure of the radiation risk associated with CT examinations

    International Nuclear Information System (INIS)

    Huda, W.

    1984-01-01

    The dose distribution in a Rando phantom has been measured for typical EMI 5005 CT scans of the head, chest, abdomen and pelvis. These dose distributions have been used to generate quantitative estimates of the somatic and genetic radiation risks associated with these CT examinations and also to measure the total energy imparted during each scan. A comparison has been made between the radiation risk estimates and the energy imparted measurements. The energy imparted measurements are not a good indicator of the somatic and/or genetic risks when one type of CT scan is compared with another. However, for a given type of scan, the energy imparted may be a reasonable indicator of the relative somatic risks associated with different CT examinations. Considerable care should be taken when interpreting and using any measured value of energy imparted in a radiological examination since published values of the risk per unit energy imparted can significantly underestimate the radiation risk. (author)

  7. Radiation dose levels in pediatric chest CT: experience in 499 children evaluated with dual-source single-energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Martine, Remy-Jardin; Colas, Lucie; Jean-Baptiste, Faivre; Remy, Jacques [CHU Lille (EA 2694) University of Lille, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Santangelo, Teresa [CHU Lille (EA 2694) University of Lille, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Bambino Gesu Children' s Hospital, Department of Imaging, Rome (Italy); Duhamel, Alain [University of Lille (EA 2694), Department of Biostatistics, CHU Lille, Lille (France); Deschildre, Antoine [CHU Lille - University of Lille, Department of Pediatric Pulmonology, Lille (France)

    2017-02-15

    The availability of dual-source technology has introduced the possibility of scanning children at lower kVp with a high-pitch mode, combining high-speed data acquisition and high temporal resolution. To establish the radiation dose levels of dual-source, single-energy chest CT examinations in children. We retrospectively recorded the dose-length product (DLP) of 499 consecutive examinations obtained in children <50 kg, divided into five weight groups: group 1 (<10 kg, n = 129); group 2 (10-20 kg, n = 176); group 3 (20-30 kg, n = 99), group 4 (30-40 kg, n = 58) and group 5 (40-49 kg, n = 37). All CT examinations were performed with high temporal resolution (75 ms), a high-pitch mode and a weight-adapted selection of the milliamperage. CT examinations were obtained at 80 kVp with a milliamperage ranging between 40 mAs and 90 mAs, and a pitch of 2.0 (n = 162; 32.5%) or 3.0 (n = 337; 67.5%). The mean duration of data acquisition was 522.8 ± 192.0 ms (interquartile range 390 to 610; median 490). In the study population, the mean CT dose index volume (CTDIvol{sub 32}) was 0.83 mGy (standard deviation [SD] 0.20 mGy; interquartile range 0.72 to 0.94; median 0.78); the mean DLP{sub 32} was 21.4 mGy.cm (SD 9.1 mGy.cm; interquartile range 15 to 25; median 19.0); and the mean size-specific dose estimate (SSDE) was 1.7 mGy (SD 0.4 mGy; interquartile range 1.5 to 1.9; median 1.7). The DLP{sub 32}, CTDI{sub vol32} and SSDE were found to be statistically significant in the five weight categories (P < 0.0001). This study establishes the radiation dose levels for dual-source, single-kVp chest CT from a single center. In the five weight categories, the median values varied 15-37 mGy.cm for the DLP{sub 32}, 0.78-1.25 mGy for the CTDI{sub vol32} and 1.6-2.1 mGy for the SSDE. (orig.)

  8. Radiation dose levels in pediatric chest CT: experience in 499 children evaluated with dual-source single-energy CT

    International Nuclear Information System (INIS)

    Martine, Remy-Jardin; Colas, Lucie; Jean-Baptiste, Faivre; Remy, Jacques; Santangelo, Teresa; Duhamel, Alain; Deschildre, Antoine

    2017-01-01

    The availability of dual-source technology has introduced the possibility of scanning children at lower kVp with a high-pitch mode, combining high-speed data acquisition and high temporal resolution. To establish the radiation dose levels of dual-source, single-energy chest CT examinations in children. We retrospectively recorded the dose-length product (DLP) of 499 consecutive examinations obtained in children <50 kg, divided into five weight groups: group 1 (<10 kg, n = 129); group 2 (10-20 kg, n = 176); group 3 (20-30 kg, n = 99), group 4 (30-40 kg, n = 58) and group 5 (40-49 kg, n = 37). All CT examinations were performed with high temporal resolution (75 ms), a high-pitch mode and a weight-adapted selection of the milliamperage. CT examinations were obtained at 80 kVp with a milliamperage ranging between 40 mAs and 90 mAs, and a pitch of 2.0 (n = 162; 32.5%) or 3.0 (n = 337; 67.5%). The mean duration of data acquisition was 522.8 ± 192.0 ms (interquartile range 390 to 610; median 490). In the study population, the mean CT dose index volume (CTDIvol 32 ) was 0.83 mGy (standard deviation [SD] 0.20 mGy; interquartile range 0.72 to 0.94; median 0.78); the mean DLP 32 was 21.4 mGy.cm (SD 9.1 mGy.cm; interquartile range 15 to 25; median 19.0); and the mean size-specific dose estimate (SSDE) was 1.7 mGy (SD 0.4 mGy; interquartile range 1.5 to 1.9; median 1.7). The DLP 32 , CTDI vol32 and SSDE were found to be statistically significant in the five weight categories (P < 0.0001). This study establishes the radiation dose levels for dual-source, single-kVp chest CT from a single center. In the five weight categories, the median values varied 15-37 mGy.cm for the DLP 32 , 0.78-1.25 mGy for the CTDI vol32 and 1.6-2.1 mGy for the SSDE. (orig.)

  9. Dual-energy computed tomography for the assessment of early treatment effects of regorafenib in a preclinical tumor model: comparison with dynamic contrast-enhanced CT and conventional contrast-enhanced single-energy CT

    International Nuclear Information System (INIS)

    Knobloch, Gesine; Hamm, Bernd; Jost, Gregor; Pietsch, Hubertus; Huppertz, Alexander

    2014-01-01

    The potential diagnostic value of dual-energy computed tomography (DE-CT) compared to dynamic contrast-enhanced CT (DCE-CT) and conventional contrast-enhanced CT (CE-CT) in the assessment of early regorafenib treatment effects was evaluated in a preclinical setting. A rat GS9L glioma model was examined with contrast-enhanced dynamic DE-CT measurements (80 kV/140 kV) for 4 min before and on days 1 and 4 after the start of daily regorafenib or placebo treatment. Tumour time-density curves (0-240 s, 80 kV), DE-CT (60 s) derived iodine maps and the DCE-CT (0-30 s, 80 kV) based parameters blood flow (BF), blood volume (BV) and permeability (PMB) were calculated and compared to conventional CE-CT (60 s, 80 kV). The regorafenib group showed a marked decrease in the tumour time-density curve, a significantly lower iodine concentration and a significantly lower PMB on day 1 and 4 compared to baseline, which was not observed for the placebo group. CE-CT showed a significant decrease in tumour density on day 4 but not on day 1. The DE-CT-derived iodine concentrations correlated with PMB and BV but not with BF. DE-CT allows early treatment monitoring, which correlates with DCE-CT. Superior performance was observed compared to single-energy CE-CT. circle Regorafenib treatment response was evaluated by CT in a rat tumour model. (orig.)

  10. Dual-energy computed tomography for the assessment of early treatment effects of regorafenib in a preclinical tumor model: comparison with dynamic contrast-enhanced CT and conventional contrast-enhanced single-energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Knobloch, Gesine; Hamm, Bernd [Charite - Universitaetsmedizin Berlin, Department of Radiology, Berlin (Germany); Jost, Gregor; Pietsch, Hubertus [Bayer Healthcare, MR and CT Contrast Media Research, Berlin (Germany); Huppertz, Alexander [Imaging Science Institute Charite - Siemens, Berlin (Germany)

    2014-08-15

    The potential diagnostic value of dual-energy computed tomography (DE-CT) compared to dynamic contrast-enhanced CT (DCE-CT) and conventional contrast-enhanced CT (CE-CT) in the assessment of early regorafenib treatment effects was evaluated in a preclinical setting. A rat GS9L glioma model was examined with contrast-enhanced dynamic DE-CT measurements (80 kV/140 kV) for 4 min before and on days 1 and 4 after the start of daily regorafenib or placebo treatment. Tumour time-density curves (0-240 s, 80 kV), DE-CT (60 s) derived iodine maps and the DCE-CT (0-30 s, 80 kV) based parameters blood flow (BF), blood volume (BV) and permeability (PMB) were calculated and compared to conventional CE-CT (60 s, 80 kV). The regorafenib group showed a marked decrease in the tumour time-density curve, a significantly lower iodine concentration and a significantly lower PMB on day 1 and 4 compared to baseline, which was not observed for the placebo group. CE-CT showed a significant decrease in tumour density on day 4 but not on day 1. The DE-CT-derived iodine concentrations correlated with PMB and BV but not with BF. DE-CT allows early treatment monitoring, which correlates with DCE-CT. Superior performance was observed compared to single-energy CE-CT. circle Regorafenib treatment response was evaluated by CT in a rat tumour model. (orig.)

  11. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, N.G. [University of Otago, Department of Radiology, Christchurch (New Zealand); Butler, A.P. [University of Otago, Department of Radiology, Christchurch (New Zealand); University of Canterbury, Physics and Astronomy, Christchurch (New Zealand); Scott, N.J.A. [University of Otago, Department of Medicine, Christchurch (New Zealand); Cook, N.J. [Christchurch Hospital, Medical Physics and Bioengineering, Christchurch (New Zealand); Butzer, J.S. [Karlsruhe Institute of Technology, Physics Department, Karlsruhe (Germany); Schleich, N. [University of Canterbury, Physics and Astronomy, Christchurch (New Zealand); Christchurch Hospital, Medical Physics and Bioengineering, Christchurch (New Zealand); Firsching, M. [Friedrich Alexander University, Physics Department, Erlangen (Germany); Grasset, R.; Ruiter, N. de [University of Canterbury, Hitlab NZ, Christchurch (New Zealand); Campbell, M. [European Organisation for Nuclear Research, Physics Section, Geneva (Switzerland); Butler, P.H. [University of Canterbury, Physics and Astronomy, Christchurch (New Zealand)

    2010-09-15

    Spectral CT differs from dual-energy CT by using a conventional X-ray tube and a photon-counting detector. We wished to produce 3D spectroscopic images of mice that distinguished calcium, iodine and barium. We developed a desktop spectral CT, dubbed MARS, based around the Medipix2 photon-counting energy-discriminating detector. The single conventional X-ray tube operated at constant voltage (75 kVp) and constant current (150 {mu}A). We anaesthetised with ketamine six black mice (C57BL/6). We introduced iodinated contrast material and barium sulphate into the vascular system, alimentary tract and respiratory tract as we euthanised them. The mice were preserved in resin and imaged at four detector energy levels from 12 keV to 42 keV to include the K-edges of iodine (33.0 keV) and barium (37.4 keV). Principal component analysis was applied to reconstructed images to identify components with independent energy response, then displayed in 2D and 3D. Iodinated and barium contrast material was spectrally distinct from soft tissue and bone in all six mice. Calcium, iodine and barium were displayed as separate channels on 3D colour images at <55 {mu}m isotropic voxels. Spectral CT distinguishes contrast agents with K-edges only 4 keV apart. Multi-contrast imaging and molecular CT are potential future applications. (orig.)

  12. A prospective study of spine fractures diagnosed by total spine computed tomography in high energy trauma patients

    International Nuclear Information System (INIS)

    Takami, Masanari; Nohda, Kazuhiro; Sakanaka, Junya; Nakamura, Masamichi; Yoshida, Munehito

    2011-01-01

    Since it is known to be impossible to identify spinal fractures in high-energy trauma patients the primary trauma evaluation, we have been performing total spine computed tomography (CT) in high-energy trauma cases. We investigated the spinal fractures that it was possible to detect by total spine CT in 179 cases and evaluated the usefulness of total spine CT prospectively. There were 54 (30.2%) spinal fractures among the 179 cases. Six (37.5%) of the 16 cervical spine fractures that were not detected on plain X-ray films were identified by total spine CT. Six (14.0%) of 43 thoracolumbar spine fractures were considered difficult to diagnose based on the clinical findings if total spine CT had not been performed. We therefore concluded that total spine CT is very useful and should be performed during the primary trauma evaluation in high-energy trauma cases. (author)

  13. In vitro differentiation of renal stone composition using dual-source, dual-energy CT

    International Nuclear Information System (INIS)

    Zhou Changsheng; Zhang Longjiang; Xu Feng; Qi Li; Zhao Yan'e; Zheng Ling; Huang Wei; Liu Youhuang; Lu Guangming

    2012-01-01

    Objective: To evaluate the ability of dual-source. dual-energy CT in differentiating uric acid stones from non-uric acid stones with infrared spectroscopy as reference standard. Materials and Methods: Urinary calculus from 308 patients were scanned in first generation dual-source CT with dual-energy mode between July 2011 and June 2012. Renal Stone application was used to analyze their composition. The uric acid stones color were coded red and non-uric acid stones were blue. CT values were measured in 60 selective urinary calculus including 30 uric acid stones and 30 non-uric acid stones. The accuracy of dual energy CT to differentiate uric acid and no-uric acid stones was calculated. Results: Of 308 patients, 60 patients had uric acid stones and 248 non-uric acid stones. No difference was found for uric acid stone at 80 kV and 140 kV (375.8±69.2 HU vs. 374.1±69.4 HU; t=-0.217, P=0.830), while CT values of non-uric acid stones were higher at 80 kV than those at 140 kV (1455.1±312.4 HU vs. 1039.6±194.4 HU; t=-12.16. P<0.001). CT values of non-uric acid stones at 80 kV, 140 kV, and average weighted images (1455.1±312.4 HU, 1 039.6±194.4 HU, and 882.0±176.4 HU, respectively) were higher than those of uric acid stones (375.8±69.2 HU, 374.1±69.4 HU, and 366.3±80.1 HU, respectively; P<0.001). With infrared spectrum findings as reference standard, the accuracy of dual energy CT in differentiating uric acid stones from non-uric acid stones was 100%. Conclusions: Dual-source, dual-energy CT can accurately differentiate uric acid stones from non-uric acid stones, and plays an important role in treatment planning of renal stones. (authors)

  14. Virtual Non-Contrast CT Using Dual-Energy Spectral CT: Feasibility of Coronary Artery Calcium Scoring.

    Science.gov (United States)

    Song, Inyoung; Yi, Jeong Geun; Park, Jeong Hee; Kim, Sung Mok; Lee, Kyung Soo; Chung, Myung Jin

    2016-01-01

    To evaluate the feasibility of coronary artery calcium scoring based on three virtual noncontrast-enhanced (VNC) images derived from single-source spectral dual-energy CT (DECT) as compared with true noncontrast-enhanced (TNC) images. This prospective study was conducted with the approval of our Institutional Review Board. Ninety-seven patients underwent noncontrast CT followed by contrast-enhanced chest CT using single-source spectral DECT. Iodine eliminated VNC images were reconstructed using two kinds of 2-material decomposition algorithms (material density iodine-water pair [MDW], material density iodine-calcium pair [MDC]) and a material suppressed algorithm (material suppressed iodine [MSI]). Two readers independently quantified calcium on VNC and TNC images. The Spearman correlation coefficient test and Bland-Altman method were used for statistical analyses. Coronary artery calcium scores from all three VNC images showed excellent correlation with those from the TNC images (Spearman's correlation coefficient [ρ] = 0.94, 0.88, and 0.89 for MDW, MDC, and MSI, respectively; p VNC images also correlated well with those from TNC images (ρ = 0.92, 0.87, and 0.91 for MDW, MDC, and MSI, respectively; p VNC images, coronary calcium from MDW correlated best with that from TNC. The coronary artery calcium scores and volumes were significantly lower from the VNC images than from the TNC images (p VNC images from contrast-enhanced CT using dual-energy material decomposition/suppression is feasible for coronary calcium scoring. The absolute value from VNC tends to be smaller than that from TNC.

  15. SU-G-IeP2-15: Virtual Insertion of Digital Kidney Stones Into Dual-Source, Dual- Energy CT Projection Data

    International Nuclear Information System (INIS)

    Ferrero, A; Chen, B; Huang, A; Montoya, J; Yu, L; McCollough, C

    2016-01-01

    Purpose: In order to investigate novel methods to more accurately estimate the mineral composition of kidney stones using dual energy CT, it is desirable to be able to combine digital stones of known composition with actual phantom and patient scan data. In this work, we developed and validated a method to insert digital kidney stones into projection data acquired on a dual-source, dual-energy CT system. Methods: Attenuation properties of stones of different mineral composition were computed using tabulated mass attenuation coefficients, the chemical formula for each stone type, and the effective beam energy at each evaluated tube potential. A previously developed method to insert lesions into x-ray CT projection data was extended to include simultaneous dual-energy CT projections acquired on a dual-source gantry (Siemens Somatom Flash). Digital stones were forward projected onto both detectors and the resulting projections added to the physically acquired sinogram data. To validate the accuracy of the technique, digital stones were inserted into different locations in the ACR CT accreditation phantom; low and high contrast resolution, CT number accuracy and noise properties were compared before and after stone insertion. The procedure was repeated for two dual-energy tube potential pairs in clinical use on the scanner, 80/Sn140 kV and 100/Sn140 kV, respectively. Results: The images reconstructed after the insertion of digital kidney stones were consistent with the images reconstructed from the scanner. The largest average CT number difference for the 4 insert in the CT number accuracy module of the phantom was 3 HU. Conclusion: A framework was developed and validated for the creation of digital kidney stones of known mineral composition, and their projection-domain insertion into commercial dual-source, dual-energy CT projection data. This will allow a systematic investigation of the impact of scan and reconstruction parameters on stone attenuation and dual-energy

  16. Machine learning-based dual-energy CT parametric mapping.

    Science.gov (United States)

    Su, Kuan-Hao; Kuo, Jung-Wen; Jordan, David W; Van Hedent, Steven; Klahr, Paul; Wei, Zhouping; Al Helo, Rose; Liang, Fan; Qian, Pengjiang; Pereira, Gisele C; Rassouli, Negin; Gilkeson, Robert C; Traughber, Bryan J; Cheng, Chee-Wai; Muzic, Raymond F

    2018-05-22

    The aim is to develop and evaluate machine learning methods for generating quantitative parametric maps of effective atomic number (Zeff), relative electron density (ρe), mean excitation energy (Ix), and relative stopping power (RSP) from clinical dual-energy CT data. The maps could be used for material identification and radiation dose calculation. Machine learning methods of historical centroid (HC), random forest (RF), and artificial neural networks (ANN) were used to learn the relationship between dual-energy CT input data and ideal output parametric maps calculated for phantoms from the known compositions of 13 tissue substitutes. After training and model selection steps, the machine learning predictors were used to generate parametric maps from independent phantom and patient input data. Precision and accuracy were evaluated using the ideal maps. This process was repeated for a range of exposure doses, and performance was compared to that of the clinically-used dual-energy, physics-based method which served as the reference. The machine learning methods generated more accurate and precise parametric maps than those obtained using the reference method. Their performance advantage was particularly evident when using data from the lowest exposure, one-fifth of a typical clinical abdomen CT acquisition. The RF method achieved the greatest accuracy. In comparison, the ANN method was only 1% less accurate but had much better computational efficiency than RF, being able to produce parametric maps in 15 seconds. Machine learning methods outperformed the reference method in terms of accuracy and noise tolerance when generating parametric maps, encouraging further exploration of the techniques. Among the methods we evaluated, ANN is the most suitable for clinical use due to its combination of accuracy, excellent low-noise performance, and computational efficiency. . © 2018 Institute of Physics and Engineering in

  17. Development of a high-energy x-ray CT and its application to iron and steel analysis

    International Nuclear Information System (INIS)

    Taguchi, Isamu

    1987-01-01

    X-ray computed tomographic scanners are extensively used in medicine but have rarely been applied to non-medical purposes. Steel specimens pose particularly difficult problems - very poor transmission of X-rays and the need for high resolving capability. There have thus been no effective tomographic methods for examining steel specimens. Due to the growing need for non-destructive, non-contact methods for observing and analyzing the internal conditions of steel and raw materials for steel, however, we have developed a new high-energy computed tomographic scanner for steel (CTS). Its major specifications and functions are as follows. Type : 2nd-generation CT, 8-channel, Scanning method : 6deg revolution, 30-time traversing, Slice width : 0.3 mm, Resolving capability : 0.1 x 0.1 mm X-ray source : 420 kV, 3 mA, X-ray detector : BGO scintillator, Standard sample size : 50 mm dia., 50 mm high, Data collection time : 9.5 or 5 min. The CTS was successfully applied to the observation and the analysis of porosities of stainless steel (SUS 304) bloom, pores of iron ore sinters and metallic phases of the meteirites found in Antarctic Continent. (author)

  18. Grating Oriented Line-Wise Filtration (GOLF) for Dual-Energy X-ray CT

    Science.gov (United States)

    Xi, Yan; Cong, Wenxiang; Harrison, Daniel; Wang, Ge

    2017-12-01

    In medical X-ray Computed Tomography (CT), the use of two distinct X-ray source spectra (energies) allows dose-reduction and material discrimination relative to that achieved with only one source spectrum. Existing dual-energy CT methods include source kVp-switching, double-layer detection, dual-source gantry, and two-pass scanning. Each method suffers either from strong spectral correlation or patient-motion artifacts. To simultaneously address these problems, we propose to improve CT data acquisition with the Grating Oriented Line-wise Filtration (GOLF) method, a novel X-ray filter that is placed between the source and patient. GOLF uses a combination of absorption and filtering gratings that are moved relative to each other and in synchronization with the X-ray tube kVp-switching process and/or the detector view-sampling process. Simulation results show that GOLF can improve the spectral performance of kVp-switching to match that of dual-source CT while avoiding patient motion artifacts and dual imaging chains. Although significant flux is absorbed by this pre-patient filter, the proposed GOLF method is a novel path for cost-effectively extracting dual-energy or multi-energy data and reducing radiation dose with or without kVp switching.

  19. Split-bolus CT-urography using dual-energy CT: Feasibility, image quality and dose reduction

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, Mitsuru, E-mail: m2rbimn@gmail.com [Nagoya City University Graduate School of Medical Sciences, Department of Radiology, 1 Kawasumi Mizuho-cho, Mizuho-ku, Nagoya, 467-8601 (Japan); Kawai, Tatsuya; Ito, Masato; Ogawa, Masaki [Nagoya City University Graduate School of Medical Sciences, Department of Radiology, 1 Kawasumi Mizuho-cho, Mizuho-ku, Nagoya, 467-8601 (Japan); Ohashi, Kazuya [Nagoya City University Hospital, Department of Radiology, 1 Kawasumi Mizuho-cho, Mizuho-ku, Nagoya, 467-8601 (Japan); Hara, Masaki; Shibamoto, Yuta [Nagoya City University Graduate School of Medical Sciences, Department of Radiology, 1 Kawasumi Mizuho-cho, Mizuho-ku, Nagoya, 467-8601 (Japan)

    2012-11-15

    Purpose: To prospectively evaluate the feasibility of dual-energy (DE) split-bolus CT-urography (CTU) and the quality of virtual non-enhanced images (VNEI) and DE combined nephrographic-excretory phase images (CNEPI), and to estimate radiation dose reduction if true non-enhanced images (TNEI) could be omitted. Patients and methods: Between August and September 2011, 30 consecutive patients with confirmed or suspected urothelial cancer or with hematuria underwent DE CT. Single-energy TNEI and DE CNEPI were obtained. VNEI was reconstructed from CNEPI. Image quality of CNEPI and VNEI was evaluated using a 5-point scale. The attenuation of urine in the bladder on TNEI and VNEI was measured. The CT dose index volume (CTDI (vol)) of the two scans was recorded. Results: The mean image quality score of CNEPI and VNEI was 4.7 and 3.3, respectively. The mean differences in urine attenuation between VNEI and TNEI were 14 {+-} 15 [SD] and -16 {+-} 29 in the anterior and posterior parts of the bladder, respectively. The mean CTDI (vol) for TNEI and CNEPI was 11.8 and 10.9 mGy, respectively. Omission of TNEI could reduce the total radiation dose by 52%. Conclusion: DE split-bolus CTU is technically feasible and can reduce radiation exposure; however, an additional TNEI scan is necessary when the VNEI quality is poor or quantitative evaluation of urine attenuation is required.

  20. SU-F-I-06: Evaluation of Imaging Dose for Modulation Layer Based Dual Energy Cone-Beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Eunbin [Department of Medical Science, Ewha Womans University, Seoul (Korea, Republic of); Ahn, SoHyun; Cho, Samju; Keum, Ki Chang [Department of Radiation Oncology, School of Medicine, Yonsei Univeristy, Seoul (Korea, Republic of); Lee, Rena [Department of Radiation Oncology, School of Medicine, Ewha Womans University, Seoul (Korea, Republic of)

    2016-06-15

    Purpose: Dual energy cone beam CT system is finding a variety of promising applications in diagnostic CT, both in imaging of endogenous materials and exogenous materials across a range of body sites. Dual energy cone beam CT system to suggest in this study acquire image by rotating 360 degree with half of the X-ray window covered using copper modulation layer. In the region that covered by modulation layer absorb the low energy X-ray by modulation layer. Relative high energy X-ray passes through the layer and contributes to image reconstruction. Dose evaluation should be carried out in order to utilize such an imaging acquirement technology for clinical use. Methods: For evaluating imaging dose of modulation layer based dual energy cone beam CT system, Prototype cone beam CT that configured X-ray tube (D054SB, Toshiba, Japan) and detector (PaxScan 2520V, Varian Medical Systems, Palo Alto, CA) is used. A range of 0.5–2.0 mm thickness of modulation layer is implemented in Monte Carlo simulation (MCNPX, ver. 2.6.0, Los Alamos National Laboratory, USA) with half of X-ray window covered. In-house phantom using in this study that has 3 cylindrical phantoms configured water, Teflon air with PMMA covered for verifying the comparability the various material in human body and is implemented in Monte Carlo simulation. The actual dose with 2.0 mm copper covered half of X-ray window is measured using Gafchromic EBT3 film with 5.0 mm bolus for compared with simulative dose. Results: Dose in phantom reduced 33% by copper modulation layer of 2.0 mm. Scattering dose occurred in modulation layer by Compton scattering effect is 0.04% of overall dose. Conclusion: Modulation layer of that based dual energy cone beam CT has not influence on unnecessary scatter dose. This study was supported by the Radiation Safety Research Programs (1305033) through the Nuclear Safety and Security Commission.

  1. Longitudinal interfacility precision in single-energy quantitative CT

    International Nuclear Information System (INIS)

    Morin, R.L.; Gray, J.E.; Wahner, H.W.; Weekes, R.G.

    1987-01-01

    The authors investigated the precision of single-energy quantitative CT measurements between two facilities over 3 months. An anthropomorphic phantom with calcium hydroxyapatite inserts (60,100, and 160 mg/cc) was used with the Cann-Gennant method to measure bone mineral density. The same model CT scanner, anthropomorphic phantom, quantitative CT standard and analysis package were utilized at each facility. Acquisition and analysis techniques were identical to those used in patient studies. At one facility, 28 measurements yielded an average precision of 6.1% (5.0%-8.5%). The average precision for 39 measurements at the other facility was 4.3% (3.2%-8.1%). Successive scans with phantom repositioning between scanning yielded an average precision of about 3% (1%-4% without repositioning). Despite differences in personnel, scanners, standards, and phantoms, the variation between facilities was about 2%, which was within the intrafacility variation of about 5% at each location

  2. Virtual non-contrast of liver from dual energy CT: a clinical application

    International Nuclear Information System (INIS)

    Qian Yu'e; Hu Hongjie; Zhang Qiaowei; Hu Peng; Shen Guohui

    2011-01-01

    Objective: To assess the virtual non-contrast liver CT from dual-energy CT for the clinical application. Methods: In total, 51 patients were included in the study, and all patients underwent multi-phase liver CT on a dual-source CT. The True non-contrast liver CT (TNCT) was performed in a single-energy acquisition mode, but the arterial and portovenous liver CT (VNCT) were performed in a dual- energy mode of 110 kV and 140 kV respectively. The virtual non-contrast CT images were derived from the arterial data using liver virtual non-contrast software. Between the true non-contrast CT and the virtual non- contrast CT, the image quality, mean CT HU values in the liver and muscle, signal to noise (SNR), the radiation dose of volume CT dose index (CTDIvol) and dose length product (DLP) in a single phase and total examination were compared with t test. Results: There was no significant difference in the detection of' liver lesions between TNCT and VNCT. The CT Hu values of muscle on both TNCT and VNCT images were almost equal. The CT HU values of liver on VNCT images were higher than that on TNCT images and the difference was significant [61.32±6.04 vs. (56.85±4.80) HU, t=-3.927, P<0.01]. There was also significant difference of SNR between TNCT (11.28±2.78) and VNCT (8.65±1.56) images (t=-5.590, P<0.01). The CTDIvol and DLP of single phase were (7.07±0.85) mGy and (155.11± 22.52) mGy · cm respectively in TNCT, and (7.05±0.87) mGy and (154.48±23.12) mGy · cm in VNCT. The total CTDIvol and DLP in VNCT were (14.35±1.66) mGy and (313.91±45.08) mGy · cm respectively, but in TNCT the total CTDIvol and DLP reached (21.43±2.46) mGy and (469.02± 66.22) mGy · cm. The difference of CTDIvol and DLP in single phase between TNCT and VNCT showed no significance, but the total CTDIvol and DLP were significantly different (t=16.168 and 13.132, P< 0.01). Conclusion: With the consequent reduction in radiation dose, the VNCT can replace TNCT as an imaging protocol in multi

  3. Recent Advances in Cardiac Computed Tomography: Dual Energy, Spectral and Molecular CT Imaging

    Science.gov (United States)

    Danad, Ibrahim; Fayad, Zahi A.; Willemink, Martin J.; Min, James K.

    2015-01-01

    Computed tomography (CT) evolved into a powerful diagnostic tool and it is impossible to imagine current clinical practice without CT imaging. Due to its widespread availability, ease of clinical application, superb sensitivity for detection of CAD, and non-invasive nature, CT has become a valuable tool within the armamentarium of the cardiologist. In the last few years, numerous technological advances in CT have occurred—including dual energy CT (DECT), spectral CT and CT-based molecular imaging. By harnessing the advances in technology, cardiac CT has advanced beyond the mere evaluation of coronary stenosis to an imaging modality tool that permits accurate plaque characterization, assessment of myocardial perfusion and even probing of molecular processes that are involved in coronary atherosclerosis. Novel innovations in CT contrast agents and pre-clinical spectral CT devices have paved the way for CT-based molecular imaging. PMID:26068288

  4. Adenosine-stress dynamic real-time myocardial perfusion CT and adenosine-stress first-pass dual-energy myocardial perfusion CT for the assessment of acute chest pain: Initial results

    Energy Technology Data Exchange (ETDEWEB)

    Weininger, Markus [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Schoepf, U. Joseph, E-mail: schoepf@musc.edu [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Department of Medicine, Division of Cardiology, Medical University of South Carolina, Charleston, SC (United States); Ramachandra, Ashok [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Fink, Christian [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany); Rowe, Garrett W.; Costello, Philip [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Henzler, Thomas [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany)

    2012-12-15

    Purpose: Recent innovations in CT enable the evolution from mere morphologic imaging to dynamic and functional testing. We describe our initial experience performing myocardial stress perfusion CT in a clinical population with acute chest pain. Methods and materials: Myocardial stress perfusion CT was performed on twenty consecutive patients (15 men, 5 women; mean age 65 ± 8 years) who presented with acute chest pain and were clinically referred for stress/rest SPECT and cardiac MRI. Prior to CT each patient was randomly assigned either to Group A or to Group B in a consecutive order (10 patients per group). Group A underwent adenosine-stress dynamic real-time myocardial perfusion CT using a novel “shuttle” mode on a 2nd generation dual-source CT. Group B underwent adenosine-stress first-pass dual-energy myocardial perfusion CT using the same CT scanner in dual-energy mode. Two experienced observers visually analyzed all CT perfusion studies. CT findings were compared with MRI and SPECT. Results: In Group A 149/170 myocardial segments (88%) could be evaluated. Real-time perfusion CT (versus SPECT) had 86% (84%) sensitivity, 98% (92%) specificity, 94% (88%) positive predictive value, and 96% (92%) negative predictive value in comparison with perfusion MRI for the detection of myocardial perfusion defects. In Group B all myocardial segments were available for analysis. Compared with MRI, dual-energy myocardial perfusion CT (versus SPECT) had 93% (94%) sensitivity, 99% (98%) specificity, 92% (88%) positive predictive value, and 96% (94%) negative predictive value for detecting hypoperfused myocardial segments. Conclusion: Our results suggest the clinical feasibility of myocardial perfusion CT imaging in patients with acute chest pain. Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusion CT showed good agreement for the detection of myocardial perfusion defects.

  5. Adenosine-stress dynamic real-time myocardial perfusion CT and adenosine-stress first-pass dual-energy myocardial perfusion CT for the assessment of acute chest pain: Initial results

    International Nuclear Information System (INIS)

    Weininger, Markus; Schoepf, U. Joseph; Ramachandra, Ashok; Fink, Christian; Rowe, Garrett W.; Costello, Philip; Henzler, Thomas

    2012-01-01

    Purpose: Recent innovations in CT enable the evolution from mere morphologic imaging to dynamic and functional testing. We describe our initial experience performing myocardial stress perfusion CT in a clinical population with acute chest pain. Methods and materials: Myocardial stress perfusion CT was performed on twenty consecutive patients (15 men, 5 women; mean age 65 ± 8 years) who presented with acute chest pain and were clinically referred for stress/rest SPECT and cardiac MRI. Prior to CT each patient was randomly assigned either to Group A or to Group B in a consecutive order (10 patients per group). Group A underwent adenosine-stress dynamic real-time myocardial perfusion CT using a novel “shuttle” mode on a 2nd generation dual-source CT. Group B underwent adenosine-stress first-pass dual-energy myocardial perfusion CT using the same CT scanner in dual-energy mode. Two experienced observers visually analyzed all CT perfusion studies. CT findings were compared with MRI and SPECT. Results: In Group A 149/170 myocardial segments (88%) could be evaluated. Real-time perfusion CT (versus SPECT) had 86% (84%) sensitivity, 98% (92%) specificity, 94% (88%) positive predictive value, and 96% (92%) negative predictive value in comparison with perfusion MRI for the detection of myocardial perfusion defects. In Group B all myocardial segments were available for analysis. Compared with MRI, dual-energy myocardial perfusion CT (versus SPECT) had 93% (94%) sensitivity, 99% (98%) specificity, 92% (88%) positive predictive value, and 96% (94%) negative predictive value for detecting hypoperfused myocardial segments. Conclusion: Our results suggest the clinical feasibility of myocardial perfusion CT imaging in patients with acute chest pain. Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusion CT showed good agreement for the detection of myocardial perfusion defects.

  6. Coronary calcium screening with dual-source CT: reliability of ungated, high-pitch chest CT in comparison with dedicated calcium-scoring CT

    Energy Technology Data Exchange (ETDEWEB)

    Hutt, Antoine; Faivre, Jean-Baptiste; Remy, Jacques; Remy-Jardin, Martine [CHRU et Universite de Lille, Department of Thoracic Imaging, Hospital Calmette (EA 2694), Lille (France); Duhamel, Alain; Deken, Valerie [CHRU et Universite de Lille, Department of Biostatistics (EA 2694), Lille (France); Molinari, Francesco [Centre Hospitalier General de Tourcoing, Department of Radiology, Tourcoing (France)

    2016-06-15

    To investigate the reliability of ungated, high-pitch dual-source CT for coronary artery calcium (CAC) screening. One hundred and eighty-five smokers underwent a dual-source CT examination with acquisition of two sets of images during the same session: (a) ungated, high-pitch and high-temporal resolution acquisition over the entire thorax (i.e., chest CT); (b) prospectively ECG-triggered acquisition over the cardiac cavities (i.e., cardiac CT). Sensitivity and specificity of chest CT for detecting positive CAC scores were 96.4 % and 100 %, respectively. There was excellent inter-technique agreement for determining the quantitative CAC score (ICC = 0.986). The mean difference between the two techniques was 11.27, representing 1.81 % of the average of the two techniques. The inter-technique agreement for categorizing patients into the four ranks of severity was excellent (weighted kappa = 0.95; 95 % CI 0.93-0.98). The inter-technique differences for quantitative CAC scores did not correlate with BMI (r = 0.05, p = 0.575) or heart rate (r = -0.06, p = 0.95); 87.2 % of them were explained by differences at the level of the right coronary artery (RCA: 0.8718; LAD: 0.1008; LCx: 0.0139; LM: 0.0136). Ungated, high-pitch dual-source CT is a reliable imaging mode for CAC screening in the conditions of routine chest CT examinations. (orig.)

  7. High resolution CT of the lung

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Harumi (Kyoto Univ. (Japan). Faculty of Medicine)

    1991-02-01

    The emergence of computed tomography (CT) in the early 1970s has greatly contributed to diagnostic radiology. The brain was the first organ examined with CT, followed by the abdomen. For the chest, CT has also come into use shortly after the introduction in the examination of the thoracic cavity and mediastinum. CT techniques were, however, of limited significance in the evaluation of pulmonary diseases, especially diffuse pulmonary diseases. High-resolution CT (HRCT) has been introduced in clinical investigations of the lung field. This article is designed to present chest radiographic and conventional tomographic interpretations and to introduce findings of HRCT corresponding to the same shadows, with a summation of the significance of HRCT and issues of diagnostic imaging. Materials outlined are tuberculosis, pneumoconiosis, bronchopneumonia, mycoplasma pneumonia, lymphangitic carcinomatosis, sarcoidosis, diffuse panbronchiolitis, interstitial pneumonia, and pulmonary emphysema. Finally, an overview of basic investigations evolved from HRCT is given. (N.K.) 140 refs.

  8. Two-pass dual-energy CT imaging for simultaneous detection, characterization, and volume measurement of urinary stones with excretory-phase CT urography alone. A phantom study

    International Nuclear Information System (INIS)

    Takahashi, Satoru; Niikawa, Hidekazu; Shikata, Atsushi; Murakami, Emi; Tsunoda, Hiroshi; Yoshioka, Toshiaki; Yamamoto, Hiroshi; Itoh, Toshihide; Tsujihata, Masao

    2013-01-01

    The purpose of this study was to evaluate if two-pass dual-energy CT imaging - id est (i.e.), simultaneous three-material and two-material decomposition analysis - can depict and characterize urinary stones in various concentrations of iodine solution in vitro. Twelve urinary stones were scanned with a dual-source CT scanner. First, each stone (in a saline-filled tube) underwent single- and dual-energy mode CT scans in order to measure the volume of the stone. Each stone was then placed in various concentrations of contrast medium and scanned in dual-energy mode to calculate its volume via three-material decomposition analysis. Two-pass dual-energy CT imaging analysis software for the Matlab environment, which was developed specifically to process simultaneous three-material and two-material decomposition, was applied to characterize and calculate the volume of each stone. Although the virtual non-contrast images from three-material decomposition analysis clearly visualized all of the stones in contrast medium with up to 80 mgI/mL, the volumes of the uric acid stones were overestimated. Two-pass dual-energy CT imaging was able to depict and characterize non-uric-acid stones in diluted contrast medium with up to 80 mgI/mL, whereas uric acid stones were correctly evaluated in diluted contrast medium with 40 mgI/mL or less. Two-pass dual-energy CT imaging is able to depict and characterize urinary stones in contrast medium. (author)

  9. CT energy weighting in the presence of scatter and limited energy resolution

    International Nuclear Information System (INIS)

    Schmidt, Taly Gilat

    2010-01-01

    Purpose: Energy-resolved CT has the potential to improve the contrast-to-noise ratio (CNR) through optimal weighting of photons detected in energy bins. In general, optimal weighting gives higher weight to the lower energy photons that contain the most contrast information. However, low-energy photons are generally most corrupted by scatter and spectrum tailing, an effect caused by the limited energy resolution of the detector. This article first quantifies the effects of spectrum tailing on energy-resolved data, which may also be beneficial for material decomposition applications. Subsequently, the combined effects of energy weighting, spectrum tailing, and scatter are investigated through simulations. Methods: The study first investigated the effects of spectrum tailing on the estimated attenuation coefficients of homogeneous slab objects. Next, the study compared the CNR and artifact performance of images simulated with varying levels of scatter and spectrum tailing effects, and reconstructed with energy integrating, photon-counting, and two optimal linear weighting methods: Projection-based and image-based weighting. Realistic detector energy-response functions were simulated based on a previously proposed model. The energy-response functions represent the probability that a photon incident on the detector at a particular energy will be detected at a different energy. Realistic scatter was simulated with Monte Carlo methods. Results: Spectrum tailing resulted in a negative shift in the estimated attenuation coefficient of slab objects compared to an ideal detector. The magnitude of the shift varied with material composition, increased with material thickness, and decreased with photon energy. Spectrum tailing caused cupping artifacts and CT number inaccuracies in images reconstructed with optimal energy weighting, and did not impact images reconstructed with photon counting weighting. Spectrum tailing did not significantly impact the CNR in reconstructed images

  10. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE

    CERN Document Server

    Anderson, NG; Firsching, M; de Ruiter, N; Schleich, N; Butzer, J S; Cook, N J; Grasset, R; Campbell, M; Scott, N J A; Anderson, N G

    2010-01-01

    Spectral CT differs from dual-energy CT by using a conventional X-ray tube and a photon-counting detector. We wished to produce 3D spectroscopic images of mice that distinguished calcium, iodine and barium. We developed a desktop spectral CT, dubbed MARS, based around the Medipix2 photon-counting energy-discriminating detector. The single conventional X-ray tube operated at constant voltage (75 kVp) and constant current (150 A mu A). We anaesthetised with ketamine six black mice (C57BL/6). We introduced iodinated contrast material and barium sulphate into the vascular system, alimentary tract and respiratory tract as we euthanised them. The mice were preserved in resin and imaged at four detector energy levels from 12 keV to 42 keV to include the K-edges of iodine (33.0 keV) and barium (37.4 keV). Principal component analysis was applied to reconstructed images to identify components with independent energy response, then displayed in 2D and 3D. Iodinated and barium contrast material was spectrally distinct f...

  11. Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE.

    Science.gov (United States)

    Anderson, N G; Butler, A P; Scott, N J A; Cook, N J; Butzer, J S; Schleich, N; Firsching, M; Grasset, R; de Ruiter, N; Campbell, M; Butler, P H

    2010-09-01

    Spectral CT differs from dual-energy CT by using a conventional X-ray tube and a photon-counting detector. We wished to produce 3D spectroscopic images of mice that distinguished calcium, iodine and barium. We developed a desktop spectral CT, dubbed MARS, based around the Medipix2 photon-counting energy-discriminating detector. The single conventional X-ray tube operated at constant voltage (75 kVp) and constant current (150 microA). We anaesthetised with ketamine six black mice (C57BL/6). We introduced iodinated contrast material and barium sulphate into the vascular system, alimentary tract and respiratory tract as we euthanised them. The mice were preserved in resin and imaged at four detector energy levels from 12 keV to 42 keV to include the K-edges of iodine (33.0 keV) and barium (37.4 keV). Principal component analysis was applied to reconstructed images to identify components with independent energy response, then displayed in 2D and 3D. Iodinated and barium contrast material was spectrally distinct from soft tissue and bone in all six mice. Calcium, iodine and barium were displayed as separate channels on 3D colour images at contrast agents with K-edges only 4 keV apart. Multi-contrast imaging and molecular CT are potential future applications.

  12. Quantification of coronary artery calcium on the basis of dual-energy coronary CT angiography.

    Science.gov (United States)

    Schwarz, Florian; Nance, John W; Ruzsics, Balazs; Bastarrika, Gorka; Sterzik, Alexander; Schoepf, U Joseph

    2012-09-01

    To evaluate the feasibility of using virtual noncontrast material-enhanced (VNC) computed tomographic (CT) series derived from dual-energy CT imaging studies for coronary artery calcium quantification. This HIPAA-compliant study was institutional review board approved; all patients provided written informed consent. Thirty-six patients prospectively underwent noncontrast-enhanced CT calcium scoring followed by coronary CT angiography performed in dual-energy mode. By using different reconstruction algorithms, three VNC series were generated and evaluated for noise and efficiency of virtual iodine removal. Two readers independently quantified calcium on VNC images and true noncontrast-enhanced conventional calcium scoring series. A leave-one-out cross validation was used to assess the accuracy of calcium score prediction from VNC series by means of linear regression. CT value histograms of the VNC series closely resembled the profile in the true noncontrast-enhanced series. There was excellent correlation between calcium volumes on the VNC series and true noncontrast-enhanced series on a per-patient (r = 0.94, P VNC series was excellent (r = 0.82). Multiethnic Study of Atherosclerosis rankings that were derived from the predicted calcium scores also showed excellent agreement (intraclass correlation coefficient = 0.909). Coronary artery calcium identification and quantification based on dual-energy coronary CT angiographic studies may obviate the need for dedicated CT calcium scoring studies. © RSNA, 2012

  13. ChromAIX2: A large area, high count-rate energy-resolving photon counting ASIC for a Spectral CT Prototype

    Science.gov (United States)

    Steadman, Roger; Herrmann, Christoph; Livne, Amir

    2017-08-01

    Spectral CT based on energy-resolving photon counting detectors is expected to deliver additional diagnostic value at a lower dose than current state-of-the-art CT [1]. The capability of simultaneously providing a number of spectrally distinct measurements not only allows distinguishing between photo-electric and Compton interactions but also discriminating contrast agents that exhibit a K-edge discontinuity in the absorption spectrum, referred to as K-edge Imaging [2]. Such detectors are based on direct converting sensors (e.g. CdTe or CdZnTe) and high-rate photon counting electronics. To support the development of Spectral CT and show the feasibility of obtaining rates exceeding 10 Mcps/pixel (Poissonian observed count-rate), the ChromAIX ASIC has been previously reported showing 13.5 Mcps/pixel (150 Mcps/mm2 incident) [3]. The ChromAIX has been improved to offer the possibility of a large area coverage detector, and increased overall performance. The new ASIC is called ChromAIX2, and delivers count-rates exceeding 15 Mcps/pixel with an rms-noise performance of approximately 260 e-. It has an isotropic pixel pitch of 500 μm in an array of 22×32 pixels and is tile-able on three of its sides. The pixel topology consists of a two stage amplifier (CSA and Shaper) and a number of test features allowing to thoroughly characterize the ASIC without a sensor. A total of 5 independent thresholds are also available within each pixel, allowing to acquire 5 spectrally distinct measurements simultaneously. The ASIC also incorporates a baseline restorer to eliminate excess currents induced by the sensor (e.g. dark current and low frequency drifts) which would otherwise cause an energy estimation error. In this paper we report on the inherent electrical performance of the ChromAXI2 as well as measurements obtained with CZT (CdZnTe)/CdTe sensors and X-rays and radioactive sources.

  14. Detection of pulmonary fat embolism with dual-energy CT: an experimental study in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chun Xiang; Zhou, Chang Sheng; Zhao, Yan E.; Han, Zong Hong; Qi, Li; Zhang, Long Jiang; Lu, Guang Ming [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Schoepf, U.J. [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Mangold, Stefanie; Ball, B.D. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States)

    2017-04-15

    To evaluate the use of dual-energy CT imaging of the lung perfused blood volume (PBV) for the detection of pulmonary fat embolism (PFE). Dual-energy CT was performed in 24 rabbits before and 1 hour, 1 day, 4 days and 7 days after artificial induction of PFE via the right ear vein. CT pulmonary angiography (CTPA) and lung PBV images were evaluated by two radiologists, who recorded the presence, number, and location of PFE on a per-lobe basis. Sensitivity, specificity, and accuracy of CTPA and lung PBV for detecting PFE were calculated using histopathological evaluation as the reference standard. A total of 144 lung lobes in 24 rabbits were evaluated and 70 fat emboli were detected on histopathological analysis. The overall sensitivity, specificity and accuracy were 25.4 %, 98.6 %, and 62.5 % for CTPA, and 82.6 %, 76.0 %, and 79.2 % for lung PBV. Higher sensitivity (p < 0.001) and accuracy (p < 0.01), but lower specificity (p < 0.001), were found for lung PBV compared with CTPA. Dual-energy CT can detect PFE earlier than CTPA (all p < 0.01). Dual-energy CT provided higher sensitivity and accuracy in the detection of PFE as well as earlier detection compared with conventional CTPA in this animal model study. (orig.)

  15. Optimization of dual-energy CT acquisitions for proton therapy using projection-based decomposition.

    Science.gov (United States)

    Vilches-Freixas, Gloria; Létang, Jean Michel; Ducros, Nicolas; Rit, Simon

    2017-09-01

    Dual-energy computed tomography (DECT) has been presented as a valid alternative to single-energy CT to reduce the uncertainty of the conversion of patient CT numbers to proton stopping power ratio (SPR) of tissues relative to water. The aim of this work was to optimize DECT acquisition protocols from simulations of X-ray images for the treatment planning of proton therapy using a projection-based dual-energy decomposition algorithm. We have investigated the effect of various voltages and tin filtration combinations on the SPR map accuracy and precision, and the influence of the dose allocation between the low-energy (LE) and the high-energy (HE) acquisitions. For all spectra combinations, virtual CT projections of the Gammex phantom were simulated with a realistic energy-integrating detector response model. Two situations were simulated: an ideal case without noise (infinite dose) and a realistic situation with Poisson noise corresponding to a 20 mGy total central dose. To determine the optimal dose balance, the proportion of LE-dose with respect to the total dose was varied from 10% to 90% while keeping the central dose constant, for four dual-energy spectra. SPR images were derived using a two-step projection-based decomposition approach. The ranges of 70 MeV, 90 MeV, and 100 MeV proton beams onto the adult female (AF) reference computational phantom of the ICRP were analytically determined from the reconstructed SPR maps. The energy separation between the incident spectra had a strong impact on the SPR precision. Maximizing the incident energy gap reduced image noise. However, the energy gap was not a good metric to evaluate the accuracy of the SPR. In terms of SPR accuracy, a large variability of the optimal spectra was observed when studying each phantom material separately. The SPR accuracy was almost flat in the 30-70% LE-dose range, while the precision showed a minimum slightly shifted in favor of lower LE-dose. Photon noise in the SPR images (20 mGy dose

  16. Virtual non-contrast CT using dual energy spectral CT: Feasibility of coronary artery calcium scoring

    International Nuclear Information System (INIS)

    Song, In Young; Yi, Jeong Geun; Park, Jeong Hee; Lee, Sung Mok; Lee, Kyung Soo; Chung, Myung Jin

    2016-01-01

    To evaluate the feasibility of coronary artery calcium scoring based on three virtual noncontrast-enhanced (VNC) images derived from single-source spectral dual-energy CT (DECT) as compared with true noncontrast-enhanced (TNC) images. This prospective study was conducted with the approval of our Institutional Review Board. Ninety-seven patients underwent noncontrast CT followed by contrast-enhanced chest CT using single-source spectral DECT. Iodine eliminated VNC images were reconstructed using two kinds of 2-material decomposition algorithms (material density iodine-water pair [MDW], material density iodine-calcium pair [MDC]) and a material suppressed algorithm (material suppressed iodine [MSI]). Two readers independently quantified calcium on VNC and TNC images. The Spearman correlation coefficient test and Bland-Altman method were used for statistical analyses. Coronary artery calcium scores from all three VNC images showed excellent correlation with those from the TNC images (Spearman's correlation coefficient [ρ] = 0.94, 0.88, and 0.89 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Measured coronary calcium volumes from VNC images also correlated well with those from TNC images (ρ = 0.92, 0.87, and 0.91 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Among the three VNC images, coronary calcium from MDW correlated best with that from TNC. The coronary artery calcium scores and volumes were significantly lower from the VNC images than from the TNC images (p < 0.001 for all pairs). The use of VNC images from contrast-enhanced CT using dual-energy material decomposition/suppression is feasible for coronary calcium scoring. The absolute value from VNC tends to be smaller than that from TNC

  17. Virtual non-contrast CT using dual energy spectral CT: Feasibility of coronary artery calcium scoring

    Energy Technology Data Exchange (ETDEWEB)

    Song, In Young; Yi, Jeong Geun; Park, Jeong Hee [Dept. of Radiology, Konkuk University School of Medicine, Seoul (Korea, Republic of); Lee, Sung Mok; Lee, Kyung Soo; Chung, Myung Jin [Dept. of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2016-06-15

    To evaluate the feasibility of coronary artery calcium scoring based on three virtual noncontrast-enhanced (VNC) images derived from single-source spectral dual-energy CT (DECT) as compared with true noncontrast-enhanced (TNC) images. This prospective study was conducted with the approval of our Institutional Review Board. Ninety-seven patients underwent noncontrast CT followed by contrast-enhanced chest CT using single-source spectral DECT. Iodine eliminated VNC images were reconstructed using two kinds of 2-material decomposition algorithms (material density iodine-water pair [MDW], material density iodine-calcium pair [MDC]) and a material suppressed algorithm (material suppressed iodine [MSI]). Two readers independently quantified calcium on VNC and TNC images. The Spearman correlation coefficient test and Bland-Altman method were used for statistical analyses. Coronary artery calcium scores from all three VNC images showed excellent correlation with those from the TNC images (Spearman's correlation coefficient [ρ] = 0.94, 0.88, and 0.89 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Measured coronary calcium volumes from VNC images also correlated well with those from TNC images (ρ = 0.92, 0.87, and 0.91 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Among the three VNC images, coronary calcium from MDW correlated best with that from TNC. The coronary artery calcium scores and volumes were significantly lower from the VNC images than from the TNC images (p < 0.001 for all pairs). The use of VNC images from contrast-enhanced CT using dual-energy material decomposition/suppression is feasible for coronary calcium scoring. The absolute value from VNC tends to be smaller than that from TNC.

  18. Dual energy CT iodine map for delineating inflammation of inflammatory arthritis

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Takeshi; Fukuda, Kunihiko [The Jikei University School of Medicine, Department of Radiology, Tokyo (Japan); Umezawa, Yoshinori; Asahina, Akihiko; Nakagawa, Hidemi [The Jikei University School of Medicine, Department of Dermatology, Tokyo (Japan); Furuya, Kazuhiro [The Jikei University School of Medicine, Division of Rheumatology Department of Internal Medicine, Tokyo (Japan)

    2017-12-15

    Iodine mapping is an image-processing technique used with dual-energy computed tomography (DECT) to improve iodine contrast resolution. CT, because of its high spatial resolution and thin slice reconstruction, is well suited to the evaluation of the peripheral joints. Recent developments in the treatment of inflammatory arthritis that require early diagnosis and precise therapeutic assessment encourage radiological evaluation. To facilitate such assessment, we describe DECT iodine mapping as a novel modality for evaluating rheumatoid arthritis and psoriatic arthritis of the hands and feet. (orig.)

  19. Reducing the effects of metal artefact using high keV monoenergetic reconstruction of dual energy CT (DECT) in hip replacements

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Mark [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Norwich Radiology Academy, Norwich (United Kingdom); Reid, Karen [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Toms, Andoni P. [Norfolk and Norwich University Hospital and University of East Anglia, Norwich (United Kingdom)

    2013-02-15

    The aim of this study was to determine whether high keV monoenergetic reconstruction of dual energy computed tomography (DECT) could be used to overcome the effects of beam hardening artefact that arise from preferential deflection of low energy photons. Two phantoms were used: a Charnley total hip replacement set in gelatine and a Catphan 500. DECT datasets were acquired at 100, 200 and 400 mA (Siemens Definition Flash, 100 and 140 kVp) and reconstructed using a standard combined algorithm (1:1) and then as monoenergetic reconstructions at 10 keV intervals from 40 to 190 keV. Semi-automated segmentation with threshold inpainting was used to obtain the attenuation values and standard deviation (SD) of the streak artefact. High contrast line pair resolution and background noise were assessed using the Catphan 500. Streak artefact is progressively reduced with increasing keV monoenergetic reconstructions. Reconstruction of a 400 mA acquisition at 150 keV results in reduction in the volume of streak artefact from 65 cm{sup 3} to 17 cm{sup 3} (74 %). There was a decrease in the contrast to noise ratio (CNR) at higher tube voltages, with the peak CNR seen at 70-80 keV. High contrast spatial resolution was maintained at high keV values. Monoenergetic reconstruction of dual energy CT at increasing theoretical kilovoltages reduces the streak artefact produced by beam hardening from orthopaedic prostheses, accompanied by a modest increase in heterogeneity of background image attenuation, and decrease in contrast to noise ratio, but no deterioration in high contrast line pair resolution. (orig.)

  20. New horizons in cardiac CT

    International Nuclear Information System (INIS)

    Harder, A.M. den; Willemink, M.J.; Jong, P.A. de; Schilham, A.M.R.; Rajiah, P.; Takx, R.A.P.; Leiner, T.

    2016-01-01

    Until recently, cardiovascular computed tomography angiography (CCTA) was associated with considerable radiation doses. The introduction of tube current modulation and automatic tube potential selection as well as high-pitch prospective ECG-triggering and iterative reconstruction offer the ability to decrease dose with approximately one order of magnitude, often to sub-millisievert dose levels. In parallel, advancements in computational technology have enabled the measurement of fractional flow reserve (FFR) from CCTA data (FFR_C_T). This technique shows potential to replace invasively measured FFR to select patients in need of coronary intervention. Furthermore, developments in scanner hardware have led to the introduction of dual-energy and photon-counting CT, which offer the possibility of material decomposition imaging. Dual-energy CT reduces beam hardening, which enables CCTA in patients with a high calcium burden and more robust myocardial CT perfusion imaging. Future-generation CT systems will be capable of counting individual X-ray photons. Photon-counting CT is promising and may result in a substantial further radiation dose reduction, vastly increased spatial resolution, and the introduction of a whole new class of contrast agents.

  1. Correlation of iodine uptake and perfusion parameters between dual-energy CT imaging and first-pass dual-input perfusion CT in lung cancer.

    Science.gov (United States)

    Chen, Xiaoliang; Xu, Yanyan; Duan, Jianghui; Li, Chuandong; Sun, Hongliang; Wang, Wu

    2017-07-01

    To investigate the potential relationship between perfusion parameters from first-pass dual-input perfusion computed tomography (DI-PCT) and iodine uptake levels estimated from dual-energy CT (DE-CT).The pre-experimental part of this study included a dynamic DE-CT protocol in 15 patients to evaluate peak arterial enhancement of lung cancer based on time-attenuation curves, and the scan time of DE-CT was determined. In the prospective part of the study, 28 lung cancer patients underwent whole-volume perfusion CT and single-source DE-CT using 320-row CT. Pulmonary flow (PF, mL/min/100 mL), aortic flow (AF, mL/min/100 mL), and a perfusion index (PI = PF/[PF + AF]) were automatically generated by in-house commercial software using the dual-input maximum slope method for DI-PCT. For the dual-energy CT data, iodine uptake was estimated by the difference (λ) and the slope (λHU). λ was defined as the difference of CT values between 40 and 70 KeV monochromatic images in lung lesions. λHU was calculated by the following equation: λHU = |λ/(70 - 40)|. The DI-PCT and DE-CT parameters were analyzed by Pearson/Spearman correlation analysis, respectively.All subjects were pathologically proved as lung cancer patients (including 16 squamous cell carcinoma, 8 adenocarcinoma, and 4 small cell lung cancer) by surgery or CT-guided biopsy. Interobserver reproducibility in DI-PCT (PF, AF, PI) and DE-CT (λ, λHU) were relatively good to excellent (intraclass correlation coefficient [ICC]Inter = 0.8726-0.9255, ICCInter = 0.8179-0.8842; ICCInter = 0.8881-0.9177, ICCInter = 0.9820-0.9970, ICCInter = 0.9780-0.9971, respectively). Correlation coefficient between λ and AF, and PF were as follows: 0.589 (P input CT perfusion analysis method can be applied to assess blood supply of lung cancer patients. Preliminary results demonstrated that the iodine uptake relevant parameters derived from DE-CT significantly correlated with perfusion

  2. Impact of low-energy CT imaging on selection of positive oral contrast media concentration.

    Science.gov (United States)

    Patino, Manuel; Murcia, Diana J; Iamurri, Andrea Prochowski; Kambadakone, Avinash R; Hahn, Peter F; Sahani, Dushyant V

    2017-05-01

    To determine to what extent low-energy CT imaging affects attenuation of gastrointestinal tract (GIT) opacified with positive oral contrast media (OCM). Second, to establish optimal OCM concentrations for low-energy diagnostic CT exams. One hundred patients (38 men and 62 women; age 62 ± 11 years; BMI 26 ± 5) with positive OCM-enhanced 120-kVp single-energy CT (SECT), and follow-up 100-kVp acquisitions (group A; n = 50), or 40-70-keV reconstructions from rapid kV switching-single-source dual-energy CT (ssDECT) (group B; n = 50) were included. Luminal attenuation from different GIT segments was compared between exams. Standard dose of three OCM and diluted solutions (75%, 50%, and 25% concentrations) were introduced serially in a gastrointestinal phantom and scanned using SECT (120, 100, and 80 kVp) and DECT (80/140 kVp) acquisitions on a ssDECT scanner. Luminal attenuation was obtained on SECT and DECT images (40-70 keV), and compared to 120-kVp scans with standard OCM concentrations. Luminal attenuation was higher on 100-kVp (328 HU) and on 40-60-keV images (410-924 HU) in comparison to 120-kVp scans (298 HU) in groups A and B (p < 0.05). Phantom: There was an inverse correlation between luminal attenuation and X-ray energy, increasing up to 527 HU on low-kVp and 999 HU on low-keV images (p < 0.05). 25% and 50% diluted OCM solutions provided similar or higher attenuation than 120 kVp, at low kVp and keV, respectively. Low-energy CT imaging increases the attenuation of GIT opacified with positive OCM, permitting reduction of 25%-75% OCM concentration.

  3. Dual-phase CT for the assessment of acute vascular injuries in high-energy blunt trauma: the imaging findings and management implications.

    Science.gov (United States)

    Iacobellis, Francesca; Ierardi, Anna M; Mazzei, Maria A; Magenta Biasina, Alberto; Carrafiello, Gianpaolo; Nicola, Refky; Scaglione, Mariano

    2016-01-01

    Acute vascular injuries are the second most common cause of fatalities in patients with multiple traumatic injuries; thus, prompt identification and management is essential for patient survival. Over the past few years, multidetector CT (MDCT) using dual-phase scanning protocol has become the imaging modality of choice in high-energy deceleration traumas. The objective of this article was to review the role of dual-phase MDCT in the identification and management of acute vascular injuries, particularly in the chest and abdomen following multiple traumatic injuries. In addition, this article will provide examples of MDCT features of acute vascular injuries with correlative surgical and interventional findings.

  4. WE-FG-207B-08: Dual-Energy CT Iodine Accuracy Across Vendors and Platforms

    International Nuclear Information System (INIS)

    Jacobsen, M; Wood, C; Cody, D

    2016-01-01

    Purpose: Although a major benefit of dual-energy CT is its quantitative capabilities, it is critical to understand how results vary by scanner manufacturer and/or model before making clinical patient management decisions. Each manufacturer utilizes a specific dual-energy CT approach; cross-calibration may be required for facilities with more than one dual-energy CT scanner type. Methods: A solid dual-energy quality control phantom (Gammex, Inc.; Appleton, WI) representing a large body cross-section containing three Iodine inserts (2mg/ml, 5mg/ml, 15 mg/ml) was scanned on these CT systems: GE HD-750 (80/140kVp), prototype GE Revolution CT with GSI (80/140kVp), Siemens Flash (80/140kVp and 100/140kVp), and Philips IQon (120kVp and 140kVp). Iodine content was measured in units of concentration (mg/ml) from a single 5mm-thick central image. Three to five acquisitions were performed on each scanner platform in order to compute standard deviation. Scan acquisitions were approximately dose-matched (∼25mGy CTDIvol) and image parameters were as consistent as possible (thickness, kernel, no noise reduction applied). Results: Iodine measurement error ranges were −0.24-0.16 mg/ml for the 2mg/ml insert (−12.0 − 8.0%), −0.28–0.26 mg/ml for the 5mg/ml insert (−5.6 − 5.2%), and −1.16−0.99 mg/ml for the 15mg/ml insert (−7.7 − 6.6%). Standard deviations ranged from 0 to 0.19 mg/ml for the repeated acquisitions from each scanner. The average iodine measurement error and standard deviation across all systems and inserts was −0.21 ± 0.48 mg/ml (−1.5 ± 6.48%). The largest absolute measurement error was found in the 15mg/ml iodine insert. Conclusion: There was generally good agreement in Iodine quantification across 3 dual-energy CT manufacturers and 4 scanner models. This was unexpected given the widely different underlying dual-energy CT mechanisms employed. Future work will include additional scanner platforms, independent verification of the Iodine

  5. Dual-energy CT can detect malignant lymph nodes in rectal cancer

    DEFF Research Database (Denmark)

    Al-Najami, I.; Lahaye, M. J.; Beets-Tan, Regina G H

    2017-01-01

    a pelvic DECT scan and a standard MRI. The Dual Energy CT quantitative parameters were analyzed: Water and Iodine concentration, Dual-Energy Ratio, Dual Energy Index, and Effective Z value, for the benign and malignant lymph node differentiation. Results DECT scanning showed statistical difference between...... quantitative parameters between benign and malignant lymph nodes. There were no difference in the accuracy of lymph node staging between DECT and MRI....

  6. Xenon-enhanced CT using subtraction CT: Basic and preliminary clinical studies for comparison of its efficacy with that of dual-energy CT and ventilation SPECT/CT to assess regional ventilation and pulmonary functional loss in smokers

    International Nuclear Information System (INIS)

    Ohno, Yoshiharu; Yoshikawa, Takeshi; Takenaka, Daisuke; Fujisawa, Yasuko; Sugihara, Naoki; Kishida, Yuji; Seki, Shinichiro; Koyama, Hisanobu; Sugimura, Kazuro

    2017-01-01

    Purpose: To prospectively and directly compare the capability for assessments of regional ventilation and pulmonary functional loss in smokers of xenon-ventilation CT obtained with the dual-energy CT (DE-CT) and subtraction CT (Sub-CT) Materials and methods: Twenty-three consecutive smokers (15 men and 8 women, mean age: 69.7 ± 8.7 years) underwent prospective unenhanced and xenon-enhanced CTs, the latter by Sub-CT and DE-CT methods, ventilation SPECT and pulmonary function tests. Sub-CT was generated from unenhanced and xenon-enhanced CT, and all co-registered SPECT/CT data were produced from SPECT and unenhanced CT data. For each method, regional ventilation was assessed by using a 11-point scoring system on a per-lobe basis. To determine the functional lung volume by each method, it was also calculated for individual sublets with a previously reported method. To determine inter-observer agreement for each method, ventilation defect assessment was evaluated by using the χ2 test with weighted kappa statistics. For evaluation of the efficacy of each method for pulmonary functional loss assessment, functional lung volume was correlated with%FEV 1 . Results: Each inter-observer agreement was rated as substantial (Sub-CT: κ = 0.69, p < 0.0001; DE-CT: κ = 0.64, p < 0.0001; SPECT/CT: κ = 0.64, p < 0.0001). Functional lung volume for each method showed significant to good correlation with%FEV 1 (Sub-CT: r = 0.72, p = 0.0001; DE-CT: r = 0.74, p < 0.0001; SPECT/CT: r = 0.66, p = 0.0006). Conclusion: Xenon-enhanced CT obtained by Sub-CT can be considered at least as efficacious as that obtained by DE-CT and SPECT/CT for assessment of ventilation abnormality and pulmonary functional loss in smokers.

  7. Xenon-enhanced CT using subtraction CT: Basic and preliminary clinical studies for comparison of its efficacy with that of dual-energy CT and ventilation SPECT/CT to assess regional ventilation and pulmonary functional loss in smokers

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Yoshiharu, E-mail: yosirad@kobe-u.ac.jp [Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe University Graduate School of Medicine, Kobe (Japan); Advanced Biomedical Imaging Research Center, Kobe University Graduate School of Medicine, Kobe (Japan); Yoshikawa, Takeshi [Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe University Graduate School of Medicine, Kobe (Japan); Advanced Biomedical Imaging Research Center, Kobe University Graduate School of Medicine, Kobe (Japan); Takenaka, Daisuke [Department of Radiology, Hyogo Cancer Center, Akashi (Japan); Fujisawa, Yasuko; Sugihara, Naoki [Toshiba Medical Systems Corporation, Otawara (Japan); Kishida, Yuji; Seki, Shinichiro; Koyama, Hisanobu; Sugimura, Kazuro [Division of Radiology, Department of Radiology, Kobe University Graduate School of Medicine (Japan)

    2017-01-15

    Purpose: To prospectively and directly compare the capability for assessments of regional ventilation and pulmonary functional loss in smokers of xenon-ventilation CT obtained with the dual-energy CT (DE-CT) and subtraction CT (Sub-CT) Materials and methods: Twenty-three consecutive smokers (15 men and 8 women, mean age: 69.7 ± 8.7 years) underwent prospective unenhanced and xenon-enhanced CTs, the latter by Sub-CT and DE-CT methods, ventilation SPECT and pulmonary function tests. Sub-CT was generated from unenhanced and xenon-enhanced CT, and all co-registered SPECT/CT data were produced from SPECT and unenhanced CT data. For each method, regional ventilation was assessed by using a 11-point scoring system on a per-lobe basis. To determine the functional lung volume by each method, it was also calculated for individual sublets with a previously reported method. To determine inter-observer agreement for each method, ventilation defect assessment was evaluated by using the χ2 test with weighted kappa statistics. For evaluation of the efficacy of each method for pulmonary functional loss assessment, functional lung volume was correlated with%FEV{sub 1}. Results: Each inter-observer agreement was rated as substantial (Sub-CT: κ = 0.69, p < 0.0001; DE-CT: κ = 0.64, p < 0.0001; SPECT/CT: κ = 0.64, p < 0.0001). Functional lung volume for each method showed significant to good correlation with%FEV{sub 1} (Sub-CT: r = 0.72, p = 0.0001; DE-CT: r = 0.74, p < 0.0001; SPECT/CT: r = 0.66, p = 0.0006). Conclusion: Xenon-enhanced CT obtained by Sub-CT can be considered at least as efficacious as that obtained by DE-CT and SPECT/CT for assessment of ventilation abnormality and pulmonary functional loss in smokers.

  8. Ultra-low dose CT attenuation correction for PET/CT

    International Nuclear Information System (INIS)

    Xia Ting; Kinahan, Paul E; Alessio, Adam M; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren

    2012-01-01

    A challenge for positron emission tomography/computed tomography (PET/CT) quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently available, lowest dose CT techniques, extended duration cine CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging. (paper)

  9. Ultra-low dose CT attenuation correction for PET/CT

    Science.gov (United States)

    Xia, Ting; Alessio, Adam M.; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren; Kinahan, Paul E.

    2012-01-01

    A challenge for PET/CT quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently-available, lowest dose CT techniques, extended duration CINE CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. Methods We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. Results CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. Conclusion When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging. PMID:22156174

  10. SU-E-I-39: Combining Conventional Tomographic Imaging Strategy and Interior Tomography for Low Dose Dual-Energy CT (DECT)

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Q [School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Xing, L [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Xiong, G; Elmore, K; Min, J [Dalio Institute of Cardiovascular Imaging, New York- Presbyterian Hospital and Weill Cornell Medical College, New York, NY (United States)

    2015-06-15

    Purpose: Dual-energy CT (DECT) affords quantitative information of tissue density and provides a new dimension for disease diagnosis and treatment planning. The technique, however, increases the imaging dose because of the doubled scans, and thus hinders its widespread clinical applications. The purpose of this work is to develop a novel hybrid DECT image acquisition and reconstruction strategy, in which one of the energies is dealt by interior tomography while the other one is obtained using conventional tomography approach. Methods: In the proposed hybrid imaging strategy, the projection data of one of the energies (e.g., high-energy) were acquired and processed in an interior scanning model, whereas the other energy in the conventional tomographic approach. It known that, if the ROI is piecewise constant or polynomial, the interior ROI can be reconstructed with TV or HOT minimization. Here we extend the TV based interior reconstruction method into dual-energy situation. The ROI images so obtained were overlaid in the context of conventional CT of the companion energy. A material based composition in ROI was used in the proposed reconstruction framework. Results: In the simulation experiment with a diagnostic DECT geometry and energies, we were able to derive the densities of soft-tissues and bones in the ROI with high fidelity. In the experimental CBCT study, both kV and MV data were collected using the on-board kV and MV imaging system. The MV data were truncated only across the ROI. Using the interior tomography reconstruction above, we were able to obtain the ROI images as that obtained using un-truncated MV data with known tissue densities. Conclusion: The proposed DECT imaging strategy provides an effective way to extract tissue density information in the ROI and in the context of anatomical images of CT imaging, with much reduced imaging dose.

  11. High-resolution breast tomography at high energy: a feasibility study of phase contrast imaging on a whole breast

    International Nuclear Information System (INIS)

    Sztrókay, A; Schlossbauer, T; Bamberg, F; Reiser, M F; Coan, P; Diemoz, P C; Brun, E; Bravin, A; Mayr, D

    2012-01-01

    Previous studies on phase contrast imaging (PCI) mammography have demonstrated an enhancement of breast morphology and cancerous tissue visualization compared to conventional imaging. We show here the first results of the PCI analyser-based imaging (ABI) in computed tomography (CT) mode on whole and large (>12 cm) tumour-bearing breast tissues. We demonstrate in this work the capability of the technique of working at high x-ray energies and producing high-contrast images of large and complex specimens. One entire breast of an 80-year-old woman with invasive ductal cancer was imaged using ABI-CT with monochromatic 70 keV x-rays and an area detector of 92×92 µm 2 pixel size. Sagittal slices were reconstructed from the acquired data, and compared to corresponding histological sections. Comparison with conventional absorption-based CT was also performed. Five blinded radiologists quantitatively evaluated the visual aspects of the ABI-CT images with respect to sharpness, soft tissue contrast, tissue boundaries and the discrimination of different structures/tissues. ABI-CT excellently depicted the entire 3D architecture of the breast volume by providing high-resolution and high-contrast images of the normal and cancerous breast tissues. These results are an important step in the evolution of PCI-CT towards its clinical implementation. (paper)

  12. High-resolution breast tomography at high energy: a feasibility study of phase contrast imaging on a whole breast

    Science.gov (United States)

    Sztrókay, A.; Diemoz, P. C.; Schlossbauer, T.; Brun, E.; Bamberg, F.; Mayr, D.; Reiser, M. F.; Bravin, A.; Coan, P.

    2012-05-01

    Previous studies on phase contrast imaging (PCI) mammography have demonstrated an enhancement of breast morphology and cancerous tissue visualization compared to conventional imaging. We show here the first results of the PCI analyser-based imaging (ABI) in computed tomography (CT) mode on whole and large (>12 cm) tumour-bearing breast tissues. We demonstrate in this work the capability of the technique of working at high x-ray energies and producing high-contrast images of large and complex specimens. One entire breast of an 80-year-old woman with invasive ductal cancer was imaged using ABI-CT with monochromatic 70 keV x-rays and an area detector of 92×92 µm2 pixel size. Sagittal slices were reconstructed from the acquired data, and compared to corresponding histological sections. Comparison with conventional absorption-based CT was also performed. Five blinded radiologists quantitatively evaluated the visual aspects of the ABI-CT images with respect to sharpness, soft tissue contrast, tissue boundaries and the discrimination of different structures/tissues. ABI-CT excellently depicted the entire 3D architecture of the breast volume by providing high-resolution and high-contrast images of the normal and cancerous breast tissues. These results are an important step in the evolution of PCI-CT towards its clinical implementation.

  13. Volumetric expiratory high-resolution CT of the lung

    International Nuclear Information System (INIS)

    Nishino, Mizuki; Hatabu, Hiroto

    2004-01-01

    We developed a volumetric expiratory high-resolution CT (HRCT) protocol that provides combined inspiratory and expiratory volumetric imaging of the lung without increasing radiation exposure, and conducted a preliminary feasibility assessment of this protocol to evaluate diffuse lung disease with small airway abnormalities. The volumetric expiratory high-resolution CT increased the detectability of the conducting airway to the areas of air trapping (P<0.0001), and added significant information about extent and distribution of air trapping (P<0.0001)

  14. Diagnosis of pulmonary artery embolism. Comparison of single-source CT and 3rd generation dual-source CT using a dual-energy protocol regarding image quality and radiation dose

    International Nuclear Information System (INIS)

    Petritsch, Bernhard; Kosmala, Aleksander; Gassenmeier, Tobias; Weng, Andreas Max; Veldhoen, Simon; Kunz, Andreas Steven; Bley, Thorsten Alexander

    2017-01-01

    To compare radiation dose, subjective and objective image quality of 3 rd generation dual-source CT (DSCT) and dual-energy CT (DECT) with conventional 64-slice single-source CT (SSCT) for pulmonary CTA. 180 pulmonary CTA studies were performed in three patient cohorts of 60 patients each. Group 1: conventional SSCT 120 kV (ref.); group 2: single-energy DSCT 100 kV (ref.); group 3: DECT 90/Sn150 kV. CTDIvol, DLP, effective radiation dose were reported, and CT attenuation (HU) was measured on three central and peripheral levels. The signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. Two readers assessed subjective image quality according to a five-point scale. Mean CTDIvol and DLP were significantly lower in the dual-energy group compared to the SSCT group (p < 0.001 [CTDIvol]; p < 0.001 [DLP]) and the DSCT group (p = 0.003 [CTDIvol]; p = 0.003 [DLP]), respectively. The effective dose in the DECT group was 2.79 ± 0.95 mSv and significantly smaller than in the SSCT group (4.60 ± 1.68 mSv, p < 0.001) and the DSCT group (4.24 ± 2.69 mSv, p = 0.003). The SNR and CNR were significantly higher in the DSCT group (p < 0.001). Subjective image quality did not differ significantly among the three protocols and was rated good to excellent in 75 % (135/180) of cases with an inter-observer agreement of 80 %. Dual-energy pulmonary CTA protocols of 3 rd generation dual-source scanners allow for significant reduction of radiation dose while providing excellent image quality and potential additional information by means of perfusion maps. Dual-energy CT with 90/Sn150 kV configuration allows for significant dose reduction in pulmonary CTA. Subjective image quality was similar among the three evaluated CT-protocols (64-slice SSCT, single-energy DSCT, 90/Sn150 kV DECT) and was rated good to excellent in 75% of cases. Dual-energy CT provides potential additional information by means of iodine distribution maps.

  15. Dual-energy CT (DECT) imaging of tophi and monosodium urate deposits in a patient with longstanding anorexia nervosa

    DEFF Research Database (Denmark)

    Weihe, Johan Petur; Birger Morillon, Melanie; Lambrechtsen, Jess

    Dual-energy CT (DECT) imaging of tophi and monosodium urate deposits in a patient with longstanding anorexia nervosa......Dual-energy CT (DECT) imaging of tophi and monosodium urate deposits in a patient with longstanding anorexia nervosa...

  16. Preliminary investigations on high energy electron beam tomography

    Energy Technology Data Exchange (ETDEWEB)

    Baertling, Yves; Hoppe, Dietrich; Hampel, Uwe

    2010-12-15

    In computed tomography (CT) cross-sectional images of the attenuation distribution within a slice are created by scanning radiographic projections of an object with a rotating X-ray source detector compound and subsequent reconstruction of the images from these projection data on a computer. CT can be made very fast by employing a scanned electron beam instead of a mechanically moving X-ray source. Now this principle was extended towards high-energy electron beam tomography with an electrostatic accelerator. Therefore a dedicated experimental campaign was planned and carried out at the Budker Institute of Nuclear Physics (BINP), Novosibirsk. There we investigated the capabilities of BINP's accelerators as an electron beam generating and scanning unit of a potential high-energy electron beam tomography device. The setup based on a 1 MeV ELV-6 (BINP) electron accelerator and a single detector. Besides tomographic measurements with different phantoms, further experiments were carried out concerning the focal spot size and repeat accuracy of the electron beam as well as the detector's response time and signal to noise ratio. (orig.)

  17. Automated bone removal in CT angiography: Comparison of methods based on single energy and dual energy scans

    International Nuclear Information System (INIS)

    Straten, Marcel van; Schaap, Michiel; Dijkshoorn, Marcel L.; Greuter, Marcel J.; Lugt, Aad van der; Krestin, Gabriel P.; Niessen, Wiro J.

    2011-01-01

    Purpose: To evaluate dual energy based methods for bone removal in computed tomography angiography (CTA) images and compare these with single energy based methods that use an additional, nonenhanced, CT scan. Methods: Four different bone removal methods were applied to CT scans of an anthropomorphic thorax phantom, acquired with a second generation dual source CT scanner. The methods differed by the way information on the presence of bone was obtained (either by using an additional, nonenhanced scan or by scanning with two tube voltages at the same time) and by the way the bone was removed from the CTA images (either by masking or subtracting the bone). The phantom contained parts which mimic vessels of various diameters in direct contact with bone. Both a quantitative and qualitative analysis of image quality after bone removal was performed. Image quality was quantified by the contrast-to-noise ratio (CNR) normalized to the square root of the dose (CNRD). At locations where vessels touch bone, the quality of the bone removal and the vessel preservation were visually assessed. The dual energy based methods were assessed with and without the addition of a 0.4 mm tin filter to the high voltage x-ray tube filtration. For each bone removal method, the dose required to obtain a certain CNR after bone removal was compared with the dose of a reference scan with the same CNR but without automated bone removal. The CNRD value of the reference scan was maximized by choosing the lowest tube voltage available. Results: All methods removed the bone completely. CNRD values were higher for the masking based methods than for the subtraction based methods. Single energy based methods had a higher CNRD value than the corresponding dual energy based methods. For the subtraction based dual energy method, tin filtration improved the CNRD value with approximately 50%. For the masking based dual energy method, it was easier to differentiate between iodine and bone when tin filtration

  18. High-resolution CT findings in Streptococcus milleri pulmonary infection

    International Nuclear Information System (INIS)

    Okada, F.; Ono, A.; Ando, Y.; Nakayama, T.; Ishii, H.; Hiramatsu, K.; Sato, H.; Kira, A.; Otabe, M.; Mori, H.

    2013-01-01

    Aim: To assess pulmonary high-resolution computed tomography (CT) findings in patients with acute Streptococcus milleri pulmonary infection. Materials and methods: Sixty consecutive patients with acute S. milleri pneumonia who had undergone high-resolution CT chest examinations between January 2004 and March 2010 were retrospectively identified. Twenty-seven patients with concurrent infections were excluded. The final study group comprised 33 patients (25 men, 8 women; aged 20–88 years, mean 63.1 years) with S. milleri infection. The patients' clinical findings were assessed. Parenchymal abnormalities, enlarged lymph nodes, and pleural effusion were evaluated on high-resolution CT. Results: Underlying conditions included malignancy (n = 15), a smoking habit (n = 11), and diabetes mellitus (n = 8). CT images of all patients showed abnormal findings, including ground-glass opacity (n = 24), bronchial wall thickening (n = 23), consolidation (n = 17), and cavities (n = 7). Pleural effusion was found in 18 patients, and complex pleural effusions were found in seven patients. Conclusion: Pulmonary infection caused by S. milleri was observed mostly in male patients with underlying conditions such as malignancy or a smoking habit. The CT findings in patients with S. milleri consisted mainly of ground-glass opacity, bronchial wall thickening, pleural effusions, and cavities

  19. Dual-energy CT in the assessment of mediastinal lymph nodes: Comparative study of virtual non-contrast and true non-contrast images

    International Nuclear Information System (INIS)

    Yoo, Seon Young; Kim, Yoo Kyung; Cho, Hyun Hae; Choi, Mi Joo; Shim, Sung Shine; Lee, Jeong Kyong; Baek, Seung Yon

    2013-01-01

    To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation ≤ the aorta; 1, > the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 ± 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (κ value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.

  20. Dual-energy CT in the assessment of mediastinal lymph nodes: Comparative study of virtual non-contrast and true non-contrast images

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Seon Young; Kim, Yoo Kyung; Cho, Hyun Hae; Choi, Mi Joo; Shim, Sung Shine; Lee, Jeong Kyong; Baek, Seung Yon [School of Medicine, Ewha Womans University, Seou (Korea, Republic of)

    2013-06-15

    To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation ≤ the aorta; 1, > the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 ± 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (κ value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.

  1. Dual-energy CT in the assessment of mediastinal lymph nodes: comparative study of virtual non-contrast and true non-contrast images.

    Science.gov (United States)

    Yoo, Seon Young; Kim, Yookyung; Cho, Hyun Hae; Choi, Mi Joo; Shim, Sung Shine; Lee, Jeong Kyong; Baek, Seung Yon

    2013-01-01

    To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation ≤ the aorta; 1, > the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 ± 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (κ value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.

  2. Image quality comparison between single energy and dual energy CT protocols for hepatic imaging

    International Nuclear Information System (INIS)

    Yao, Yuan; Pelc, Norbert J.; Ng, Joshua M.; Megibow, Alec J.

    2016-01-01

    Purpose: Multi-detector computed tomography (MDCT) enables volumetric scans in a single breath hold and is clinically useful for hepatic imaging. For simple tasks, conventional single energy (SE) computed tomography (CT) images acquired at the optimal tube potential are known to have better quality than dual energy (DE) blended images. However, liver imaging is complex and often requires imaging of both structures containing iodinated contrast media, where atomic number differences are the primary contrast mechanism, and other structures, where density differences are the primary contrast mechanism. Hence it is conceivable that the broad spectrum used in a dual energy acquisition may be an advantage. In this work we are interested in comparing these two imaging strategies at equal-dose and more complex settings. Methods: We developed numerical anthropomorphic phantoms to mimic realistic clinical CT scans for medium size and large size patients. MDCT images based on the defined phantoms were simulated using various SE and DE protocols at pre- and post-contrast stages. For SE CT, images from 60 kVp through 140 with 10 kVp steps were considered; for DE CT, both 80/140 and 100/140 kVp scans were simulated and linearly blended at the optimal weights. To make a fair comparison, the mAs of each scan was adjusted to match the reference radiation dose (120 kVp, 200 mAs for medium size patients and 140 kVp, 400 mAs for large size patients). Contrast-to-noise ratio (CNR) of liver against other soft tissues was used to evaluate and compare the SE and DE protocols, and multiple pre- and post-contrasted liver-tissue pairs were used to define a composite CNR. To help validate the simulation results, we conducted a small clinical study. Eighty-five 120 kVp images and 81 blended 80/140 kVp images were collected and compared through both quantitative image quality analysis and an observer study. Results: In the simulation study, we found that the CNR of pre-contrast SE image mostly

  3. Opportunities for new CT contrast agents to maximize the diagnostic potential of emerging spectral CT technologies.

    Science.gov (United States)

    Yeh, Benjamin M; FitzGerald, Paul F; Edic, Peter M; Lambert, Jack W; Colborn, Robert E; Marino, Michael E; Evans, Paul M; Roberts, Jeannette C; Wang, Zhen J; Wong, Margaret J; Bonitatibus, Peter J

    2017-04-01

    The introduction of spectral CT imaging in the form of fast clinical dual-energy CT enabled contrast material to be differentiated from other radiodense materials, improved lesion detection in contrast-enhanced scans, and changed the way that existing iodine and barium contrast materials are used in clinical practice. More profoundly, spectral CT can differentiate between individual contrast materials that have different reporter elements such that high-resolution CT imaging of multiple contrast agents can be obtained in a single pass of the CT scanner. These spectral CT capabilities would be even more impactful with the development of contrast materials designed to complement the existing clinical iodine- and barium-based agents. New biocompatible high-atomic number contrast materials with different biodistribution and X-ray attenuation properties than existing agents will expand the diagnostic power of spectral CT imaging without penalties in radiation dose or scan time. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Effects of dual-energy CT with non-linear blending on abdominal CT angiography

    International Nuclear Information System (INIS)

    Li, Sulan; Wang, Chaoqin; Jiang, Xiao Chen; Xu, Ge

    2014-01-01

    To determine whether non-linear blending technique for arterial-phase dual-energy abdominal CT angiography (CTA) could improve image quality compared to the linear blending technique and conventional 120 kVp imaging. This study included 118 patients who had accepted dual-energy abdominal CTA in the arterial phase. They were assigned to Sn140/80 kVp protocol (protocol A, n = 40) if body mass index (BMI) < 25 or Sn140/100 kVp protocol (protocol B, n = 41) if BMI ≥ 25. Non-linear blending images and linear blending images with a weighting factor of 0.5 in each protocol were generated and compared with the conventional 120 kVp images (protocol C, n = 37). The abdominal vascular enhancements, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and radiation dose were assessed. Statistical analysis was performed using one-way analysis of variance test, independent t test, Mann-Whitney U test, and Kruskal-Wallis test. Mean vascular attenuation, CNR, SNR and subjective image quality score for the non-linear blending images in each protocol were all higher compared to the corresponding linear blending images and 120 kVp images (p values ranging from < 0.001 to 0.007) except for when compared to non-linear blending images for protocol B and 120 kVp images in CNR and SNR. No significant differences were found in image noise among the three kinds of images and the same kind of images in different protocols, but the lowest radiation dose was shown in protocol A. Non-linear blending technique of dual-energy CT can improve the image quality of arterial-phase abdominal CTA, especially with the Sn140/80 kVp scanning.

  5. Effects of dual-energy CT with non-linear blending on abdominal CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Li, Sulan; Wang, Chaoqin; Jiang, Xiao Chen; Xu, Ge [Dept. of Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou (China)

    2014-08-15

    To determine whether non-linear blending technique for arterial-phase dual-energy abdominal CT angiography (CTA) could improve image quality compared to the linear blending technique and conventional 120 kVp imaging. This study included 118 patients who had accepted dual-energy abdominal CTA in the arterial phase. They were assigned to Sn140/80 kVp protocol (protocol A, n = 40) if body mass index (BMI) < 25 or Sn140/100 kVp protocol (protocol B, n = 41) if BMI ≥ 25. Non-linear blending images and linear blending images with a weighting factor of 0.5 in each protocol were generated and compared with the conventional 120 kVp images (protocol C, n = 37). The abdominal vascular enhancements, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and radiation dose were assessed. Statistical analysis was performed using one-way analysis of variance test, independent t test, Mann-Whitney U test, and Kruskal-Wallis test. Mean vascular attenuation, CNR, SNR and subjective image quality score for the non-linear blending images in each protocol were all higher compared to the corresponding linear blending images and 120 kVp images (p values ranging from < 0.001 to 0.007) except for when compared to non-linear blending images for protocol B and 120 kVp images in CNR and SNR. No significant differences were found in image noise among the three kinds of images and the same kind of images in different protocols, but the lowest radiation dose was shown in protocol A. Non-linear blending technique of dual-energy CT can improve the image quality of arterial-phase abdominal CTA, especially with the Sn140/80 kVp scanning.

  6. Ventilation imaging of the paranasal sinuses using xenon-enhanced dynamic single-energy CT and dual-energy CT: a feasibility study in a nasal cast

    Energy Technology Data Exchange (ETDEWEB)

    Thieme, Sven F.; Helck, Andreas D.; Reiser, Maximilian F.; Johnson, Thorsten R.C. [Ludwig Maximilians University Hospital Munich, Institute for Clinical Radiology, Munich (Germany); Moeller, Winfried; Eickelberg, Oliver [Institute for Lung Biology and Disease (iLBD) and Comprehensive Pneumology Center (CPC), Helmholtz Zentrum Muenchen, Neuherberg, Munich (Germany); Becker, Sven [Ludwig-Maximilians-Universitaet, Department of Otorhinolaryngology - Head and Neck Surgery, Munich (Germany); Schuschnig, Uwe [Pari Pharma GmbH, Graefelfing (Germany)

    2012-10-15

    To show the feasibility of dual-energy CT (DECT) and dynamic CT for ventilation imaging of the paranasal sinuses in a nasal cast. In a first trial, xenon gas was administered to a nasal cast with a laminar flow of 7 L/min. Dynamic CT acquisitions of the nasal cavity and the sinuses were performed. This procedure was repeated with pulsating xenon flow. Local xenon concentrations in the different compartments of the model were determined on the basis of the enhancement levels. In a second trial, DECT measurements were performed both during laminar and pulsating xenon administration and the xenon concentrations were quantified directly. Neither with dynamic CT nor DECT could xenon-related enhancement be detected in the sinuses during laminar airflow. Using pulsating flow, dynamic imaging showed a xenon wash-in and wash-out in the sinuses that followed a mono-exponential function with time constants of a few seconds. Accordingly, DECT revealed xenon enhancement in the sinuses only after pulsating xenon administration. The feasibility of xenon-enhanced DECT for ventilation imaging was proven in a nasal cast. The superiority of pulsating gas flow for the administration of gas or aerosolised drugs to the paranasal sinuses was demonstrated. (orig.)

  7. Metal artefact reduction in gemstone spectral imaging dual-energy CT with and without metal artefact reduction software

    International Nuclear Information System (INIS)

    Lee, Young Han; Song, Ho-Taek; Kim, Sungjun; Suh, Jin-Suck; Park, Kwan Kyu

    2012-01-01

    To assess the usefulness of gemstone spectral imaging (GSI) dual-energy CT (DECT) with/without metal artefact reduction software (MARs). The DECTs were performed using fast kV-switching GSI between 80 and 140 kV. The CT data were retro-reconstructed with/without MARs, by different displayed fields-of-view (DFOV), and with synthesised monochromatic energy in the range 40-140 keV. A phantom study of size and CT numbers was performed in a titanium plate and a stainless steel plate. A clinical study was performed in 26 patients with metallic hardware. All images were retrospectively reviewed in terms of the visualisation of periprosthetic regions and the severity of beam-hardening artefacts by using a five-point scale. The GSI-MARs reconstruction can markedly reduce the metal-related artefacts, and the image quality was affected by the prosthesis composition and DFOV. The spectral CT numbers of the prosthesis and periprosthetic regions showed different patterns on stainless steel and titanium plates. Dual-energy CT with GSI-MARs can reduce metal-related artefacts and improve the delineation of the prosthesis and periprosthetic region. We should be cautious when using GSI-MARs because the image quality was affected by the prosthesis composition, energy (in keV) and DFOV. The metallic composition and size should be considered in metallic imaging with GSI-MARs reconstruction. circle Metal-related artefacts can be troublesome on musculoskeletal computed tomography (CT). circle Gemstone spectral imaging (GSI) with dual-energy CT (DECT) offers a novel solution circle GSI and metallic artefact reduction software (GSI-MAR) can markedly reduce these artefacts. circle However image quality is influenced by the prosthesis composition and other parameters. circle We should be aware about potential overcorrection when using GSI-MARs. (orig.)

  8. Noise suppression for dual-energy CT via penalized weighted least-square optimization with similarity-based regularization

    Energy Technology Data Exchange (ETDEWEB)

    Harms, Joseph; Wang, Tonghe; Petrongolo, Michael; Zhu, Lei, E-mail: leizhu@gatech.edu [Nuclear and Radiological Engineering and Medical Physics Programs, The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Niu, Tianye [Sir Run Run Shaw Hospital, Zhejiang University School of Medicine (China); Institute of Translational Medicine, Zhejiang University, Hangzhou, Zhejiang, 310016 (China)

    2016-05-15

    Purpose: Dual-energy CT (DECT) expands applications of CT imaging in its capability to decompose CT images into material images. However, decomposition via direct matrix inversion leads to large noise amplification and limits quantitative use of DECT. Their group has previously developed a noise suppression algorithm via penalized weighted least-square optimization with edge-preservation regularization (PWLS-EPR). In this paper, the authors improve method performance using the same framework of penalized weighted least-square optimization but with similarity-based regularization (PWLS-SBR), which substantially enhances the quality of decomposed images by retaining a more uniform noise power spectrum (NPS). Methods: The design of PWLS-SBR is based on the fact that averaging pixels of similar materials gives a low-noise image. For each pixel, the authors calculate the similarity to other pixels in its neighborhood by comparing CT values. Using an empirical Gaussian model, the authors assign high/low similarity value to one neighboring pixel if its CT value is close/far to the CT value of the pixel of interest. These similarity values are organized in matrix form, such that multiplication of the similarity matrix to the image vector reduces image noise. The similarity matrices are calculated on both high- and low-energy CT images and averaged. In PWLS-SBR, the authors include a regularization term to minimize the L-2 norm of the difference between the images without and with noise suppression via similarity matrix multiplication. By using all pixel information of the initial CT images rather than just those lying on or near edges, PWLS-SBR is superior to the previously developed PWLS-EPR, as supported by comparison studies on phantoms and a head-and-neck patient. Results: On the line-pair slice of the Catphan{sup ©}600 phantom, PWLS-SBR outperforms PWLS-EPR and retains spatial resolution of 8 lp/cm, comparable to the original CT images, even at 90% reduction in noise

  9. Diagnosis of pulmonary artery embolism. Comparison of single-source CT and 3{sup rd} generation dual-source CT using a dual-energy protocol regarding image quality and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Petritsch, Bernhard; Kosmala, Aleksander; Gassenmeier, Tobias; Weng, Andreas Max; Veldhoen, Simon; Kunz, Andreas Steven; Bley, Thorsten Alexander [Univ. Hospital Wuerzburg (Germany). Inst. of Diagnostic and Interventional Radiology

    2017-06-15

    To compare radiation dose, subjective and objective image quality of 3 rd generation dual-source CT (DSCT) and dual-energy CT (DECT) with conventional 64-slice single-source CT (SSCT) for pulmonary CTA. 180 pulmonary CTA studies were performed in three patient cohorts of 60 patients each. Group 1: conventional SSCT 120 kV (ref.); group 2: single-energy DSCT 100 kV (ref.); group 3: DECT 90/Sn150 kV. CTDIvol, DLP, effective radiation dose were reported, and CT attenuation (HU) was measured on three central and peripheral levels. The signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. Two readers assessed subjective image quality according to a five-point scale. Mean CTDIvol and DLP were significantly lower in the dual-energy group compared to the SSCT group (p < 0.001 [CTDIvol]; p < 0.001 [DLP]) and the DSCT group (p = 0.003 [CTDIvol]; p = 0.003 [DLP]), respectively. The effective dose in the DECT group was 2.79 ± 0.95 mSv and significantly smaller than in the SSCT group (4.60 ± 1.68 mSv, p < 0.001) and the DSCT group (4.24 ± 2.69 mSv, p = 0.003). The SNR and CNR were significantly higher in the DSCT group (p < 0.001). Subjective image quality did not differ significantly among the three protocols and was rated good to excellent in 75 % (135/180) of cases with an inter-observer agreement of 80 %. Dual-energy pulmonary CTA protocols of 3 rd generation dual-source scanners allow for significant reduction of radiation dose while providing excellent image quality and potential additional information by means of perfusion maps. Dual-energy CT with 90/Sn150 kV configuration allows for significant dose reduction in pulmonary CTA. Subjective image quality was similar among the three evaluated CT-protocols (64-slice SSCT, single-energy DSCT, 90/Sn150 kV DECT) and was rated good to excellent in 75% of cases. Dual-energy CT provides potential additional information by means of iodine distribution maps.

  10. SPECT/CT and pulmonary embolism

    Energy Technology Data Exchange (ETDEWEB)

    Mortensen, Jann [Copenhagen University Hospital, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen (Denmark); The Faroese National Hospital, Department of Medicine, Torshavn (Faroe Islands); Gutte, Henrik [Copenhagen University Hospital, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen (Denmark); Herlev Hospital, Copenhagen University Hospital, Department of Radiology, Copenhagen (Denmark); University of Copenhagen, Cluster for Molecular Imaging, Faculty of Health Sciences, Copenhagen (Denmark)

    2014-05-15

    Acute pulmonary embolism (PE) is diagnosed either by ventilation/perfusion (V/P) scintigraphy or pulmonary CT angiography (CTPA). In recent years both techniques have improved. Many nuclear medicine centres have adopted the single photon emission CT (SPECT) technique as opposed to the planar technique for diagnosing PE. SPECT has been shown to have fewer indeterminate results and a higher diagnostic value. The latest improvement is the combination of a low-dose CT scan with a V/P SPECT scan in a hybrid tomograph. In a study comparing CTPA, planar scintigraphy and SPECT alone, SPECT/CT had the best diagnostic accuracy for PE. In addition, recent developments in the CTPA technique have made it possible to image the pulmonary arteries of the lungs in one breath-hold. This development is based on the change from a single-detector to multidetector CT technology with an increase in volume coverage per rotation and faster rotation. Furthermore, the dual energy CT technique is a promising modality that can provide functional imaging in combination with anatomical information. Newer high-end CT scanners and SPECT systems are able to visualize smaller subsegmental emboli. However, consensus is lacking regarding the clinical impact and treatment. In the present review, SPECT and SPECT in combination with low-dose CT, CTPA and dual energy CT are discussed in the context of diagnosing PE. (orig.)

  11. High-resolution CT of the lungs: Anatomic-pathologic correlation

    International Nuclear Information System (INIS)

    Stein, M.G.; Webb, W.R.; Finkbeiner, W.; Gamsu, G.

    1986-01-01

    The interpretation of thin-section (1.5-mm), high-resolution CT scans of the lungs has been limited by lack of direct radiologic and pathologic correlation. The author scanned fresh inflated isolated lungs from ten healthy and five diseased subjects using thin-section, high-resolution techniques. The lungs were then fixed by inflation with endobronchial Formalin. Gough sections (1 mm thick) were obtained at the same levels as the CT scans. In healthy subjects, secondary lobules were identified by the presence of visible interlobular septa and central arterioles. In some patients with disease, septal thickening was visible. In patients with honeycombing cystic areas of destroyed lung were seen, along with areas of fibrosis. Emphysema was well evaluated. Thin-section, high-resolution CT can define lung architecture and may resolve mild changes of the interstitium

  12. The demonstration of the auditory ossicles by high resolution CT

    International Nuclear Information System (INIS)

    Lloyd, G.A.S.; Boulay, G.H. du; Phelps, P.D.; Pullicino, P.

    1979-01-01

    The high resolution CT scanning system introduced by EMI in 1978 has added a new dimension to computerised tomography in otology. The apparatus used for this study was an EMI CT 5005 body scanner adapted for head and neck scanning and incorporating a high resolution facility. The latter has proved most advantageous in areas of relatively high differential absorption, so that its application to the demonstration of abnormalities in the petrous temporal bone, and in particular middle ear disease, has been very rewarding. Traumatic ossicular disruptions may now be demonstrated and the high contrast of CT often shows them better than conventional hypocycloidal tomography. The stapes is also better visualised and congenital abnormalities of its superstructure have been recorded. These studies have been achieved with a very acceptable level of radiation to the eye, lens and cornea and the technique is clearly a rival to conventional pluridirectional tomography in the assessment of the petrous temporal bone. With further design improvements high resolution CT could completely replace existing techniques. (orig.) [de

  13. Single source dual energy CT: What is the optimal monochromatic energy level for the analysis of the lung parenchyma?

    Energy Technology Data Exchange (ETDEWEB)

    Ohana, M., E-mail: mickael.ohana@gmail.com [iCube Laboratory, Université de Strasbourg/CNRS, UMR 7357, 67400 Illkirch (France); Service de Radiologie B, Nouvel Hôpital Civil – Hôpitaux Universitaires de Strasbourg, 1 place de l’hôpital, 67000 Strasbourg (France); Labani, A., E-mail: aissam.labani@chru-strasbourg.fr [Service de Radiologie B, Nouvel Hôpital Civil – Hôpitaux Universitaires de Strasbourg, 1 place de l’hôpital, 67000 Strasbourg (France); Severac, F., E-mail: francois.severac@chru-strasbourg.fr [Département de Biostatistiques et d’Informatique Médicale, Hôpital Civil – Hôpitaux Universitaires de Strasbourg,1 place de l’hôpital, 67000 Strasbourg (France); Jeung, M.Y., E-mail: Mi-Young.Jeung@chru-strasbourg.fr [Service de Radiologie B, Nouvel Hôpital Civil – Hôpitaux Universitaires de Strasbourg, 1 place de l’hôpital, 67000 Strasbourg (France); Gaertner, S., E-mail: Sebastien.Gaertner@chru-strasbourg.fr [Service de Médecine Vasculaire, Nouvel Hôpital Civil – Hôpitaux Universitaires de Strasbourg,1 place de l’hôpital, 67000 Strasbourg (France); and others

    2017-03-15

    Highlights: • Lung parenchyma aspect varies with the monochromatic energy level in spectral CT. • Optimal diagnostic and image quality is obtained at 50–55 keV. • Mediastinum and parenchyma could be read on the same monochromatic energy level. - Abstract: Objective: To determine the optimal monochromatic energy level for lung parenchyma analysis in spectral CT. Methods: All 50 examinations (58% men, 64.8 ± 16yo) from an IRB-approved prospective study on single-source dual energy chest CT were retrospectively included and analyzed. Monochromatic images in lung window reconstructed every 5 keV from 40 to 140 keV were independently assessed by two chest radiologists. Based on the overall image quality and the depiction/conspicuity of parenchymal lesions, each reader had to designate for every patient the keV level providing the best diagnostic and image quality. Results: 72% of the examinations exhibited parenchymal lesions. Reader 1 picked the 55 keV monochromatic reconstruction in 52% of cases, 50 in 30% and 60 in 18%. Reader 2 chose 50 keV in 52% cases, 55 in 40%, 60 in 6% and 40 in 2%. The 50 and 55 keV levels were chosen by at least one reader in 64% and 76% of all patients, respectively. Merging 50 and 55 keV into one category results in an optimal setting selected by reader 1 in 82% of patients and by reader 2 in 92%, with a 74% concomitant agreement. Conclusion: The best image quality for lung parenchyma in spectral CT is obtained with the 50–55 keV monochromatic reconstructions.

  14. Dual energy CT intracranial angiography: image quality, radiation dose and initial application results

    International Nuclear Information System (INIS)

    Chai Xue; Zhang Longjiang; Lu Guangming; Zhou Changsheng

    2009-01-01

    Objective: To assess the clinical value of dual-energy intracranial CT angiography (CTA). Methods: Forty-one patients suspected of intracranial vascular diseases underwent dual-energy intracranial CT angiography, and 41 patients who underwent conventional subtraction CT were enrolled as the control group. Image quality of intracranial and skull base vessels and radiation dose between dual-energy CTA and conventional subtraction CTA were compared using two independent sample nonparametric test and independent-samples t test, respectively. Prevalence and size of lesions detected by dual-energy CTA and digital subtraction CTA were compared using paired-samples t test and Spearman correlative analysis. Results: The percentage of image quality scored 5 was 70.7% (29/41) for dual-energy CTA and 75.6% (31/41) for conventional subtraction CTA. There was no significant difference between the two groups (Z= -0.455, P=0.650). Image quality of vessels at the skull base in conventional subtraction CTA was superior to that in dual-energy CTA, especially for the petrosal and syphon segment (Z=-4.087, P=0.000). Radiation exposure of dual energy CTA and conventional CTA were (396.54±17.43) and (1090.95±114.29) mGy·cm respectively. Radiation exposure was decreased by 64% (t=-38.52, P=0.000) by dual energy CTA compared with conventional subtraction CTA. Out of the 41 patients, 19 patients were diagnosed as intracranial aneurysm, 2 patients as arteriovenous malformation (AVM), 3 patients with Moya-moya's disease, and the remaining 17 patients with negative results. Nine patients with intracranial aneurysm, 2 patients with AVM, 3 patients with Moya-moya's disease, and 2 patients with negative findings underwent DSA or operation, with concordant findings from both techniques. Diameter of aneurysm neck, long axis and minor axis by dual-energy CTA was (2.90±1.61), (5.23±1.68) and (3.83±1.69) mm, respectively; Diameter of aneurysm neck, long axis and minor axis by DSA was (2.95±1

  15. Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT

    Energy Technology Data Exchange (ETDEWEB)

    Pelgrim, Gert Jan; Oudkerk, Matthijs [University of Groningen, University Medical Center Groningen, Center for Medical Imaging - North East Netherlands, P.O. Box EB44, Groningen (Netherlands); Hamersvelt, Robbert W. van; Willemink, Martin J.; Schilham, Arnold; Leiner, Tim [Utrecht University Medical Center, Department of Radiology, Utrecht (Netherlands); Schmidt, Bernhard T.; Flohr, Thomas [Siemens Healthcare GmbH, Forchheim (Germany); Milles, Julien [Philips Healthcare, Best (Netherlands); Vliegenthart, Rozemarijn [University of Groningen, University Medical Center Groningen, Center for Medical Imaging - North East Netherlands, P.O. Box EB44, Groningen (Netherlands); University of Groningen, University Medical Center Groningen, Department of Radiology, Groningen (Netherlands)

    2017-09-15

    To determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques. Five tubes with different iodine concentrations (0, 5, 10, 15, 20 mg/ml) were analysed in an anthropomorphic thoracic phantom. Adding two phantom rings simulated increased patient size. For third-generation dual source CT (DSCT), tube voltage combinations of 150Sn and 70, 80, 90, 100 kVp were analysed. For dual layer CT (DLCT), 120 and 140 kVp were used. Scans were repeated three times. Median normalized values and interquartile ranges (IQRs) were calculated for all kVp settings and phantom sizes. Correlation between measured and known iodine concentrations was excellent for both systems (R = 0.999-1.000, p < 0.0001). For DSCT, median measurement errors ranged from -0.5% (IQR -2.0, 2.0%) at 150Sn/70 kVp and -2.3% (IQR -4.0, -0.1%) at 150Sn/80 kVp to -4.0% (IQR -6.0, -2.8%) at 150Sn/90 kVp. For DLCT, median measurement errors ranged from -3.3% (IQR -4.9, -1.5%) at 140 kVp to -4.6% (IQR -6.0, -3.6%) at 120 kVp. Larger phantom sizes increased variability of iodine measurements (p < 0.05). Iodine concentration can be accurately quantified with state-of-the-art DECT systems from two vendors. The lowest absolute errors were found for DSCT using the 150Sn/70 kVp or 150Sn/80 kVp combinations, which was slightly more accurate than 140 kVp in DLCT. (orig.)

  16. Assessment of pancreatic adenocarcinoma: use of low-dose whole pancreatic CT perfusion and individualized dual-energy CT scanning

    International Nuclear Information System (INIS)

    Li, Hai-ou; Guo, Jun; Li, Xiao; Qi, Yao-dong; Wang, Xi-ming; Xu, Zhuo-dong; Liu, Cheng; Chen, Jiu-hong

    2015-01-01

    The objective of this study was to investigate the value of low-dose whole pancreatic computed tomography (CT) perfusion integrated with individualized dual-energy CT (DECT) scanning in the diagnosis of pancreatic adenocarcinoma. Twenty patients with pancreatic adenocarcinoma underwent pancreatic CT perfusion as well as individualized dual-phase DECT pancreatic scans. Perfusion characteristics of non-tumourous pancreatic parenchyma and pancreatic adenocarcinoma were analysed. Weighted-average 120 kVp images and the optimal monoenergetic images in dual phase were reconstructed and the contrast noise ratio (CNR) of pancreas-to-tumour were compared. There were significant difference on blood flow as well as blood volume between pancreatic adenocarcinoma and the non-tumourous pancreatic parenchyma (P < 0.05), whereas no difference on permeability (P > 0.05). CNRs of pancreas-to-tumour in individualized pancreatic phase were significantly higher than those in venous phase (P < 0.05), and CNRs of optimal monoenergetic images were higher than those on weighted-average 120 kVp images (P < 0.05) in both phase. Total effective radiation dose of CT examination was around 9.32–13.75 mSv. Low-dose whole pancreatic CT perfusion can provide functional information, and the individualized pancreatic phase DECT scan is the optimal method for detecting pancreatic adenocarcinomas. The integration of the two techniques has great value in clinical application.

  17. Multimaterial Decomposition Algorithm for the Quantification of Liver Fat Content by Using Fast-Kilovolt-Peak Switching Dual-Energy CT: Experimental Validation.

    Science.gov (United States)

    Hyodo, Tomoko; Hori, Masatoshi; Lamb, Peter; Sasaki, Kosuke; Wakayama, Tetsuya; Chiba, Yasutaka; Mochizuki, Teruhito; Murakami, Takamichi

    2017-02-01

    Purpose To assess the ability of fast-kilovolt-peak switching dual-energy computed tomography (CT) by using the multimaterial decomposition (MMD) algorithm to quantify liver fat. Materials and Methods Fifteen syringes that contained various proportions of swine liver obtained from an abattoir, lard in food products, and iron (saccharated ferric oxide) were prepared. Approval of this study by the animal care and use committee was not required. Solid cylindrical phantoms that consisted of a polyurethane epoxy resin 20 and 30 cm in diameter that held the syringes were scanned with dual- and single-energy 64-section multidetector CT. CT attenuation on single-energy CT images (in Hounsfield units) and MMD-derived fat volume fraction (FVF; dual-energy CT FVF) were obtained for each syringe, as were magnetic resonance (MR) spectroscopy measurements by using a 1.5-T imager (fat fraction [FF] of MR spectroscopy). Reference values of FVF (FVF ref ) were determined by using the Soxhlet method. Iron concentrations were determined by inductively coupled plasma optical emission spectroscopy and divided into three ranges (0 mg per 100 g, 48.1-55.9 mg per 100 g, and 92.6-103.0 mg per 100 g). Statistical analysis included Spearman rank correlation and analysis of covariance. Results Both dual-energy CT FVF (ρ = 0.97; P iron. Phantom size had a significant effect on dual-energy CT FVF after controlling for FVF ref (P iron concentrations, the linear coefficients of dual-energy CT FVF decreased and those of MR spectroscopy FF increased (P iron, dual-energy CT FVF led to underestimateion of FVF ref to a lesser degree than FF of MR spectroscopy led to overestimation of FVF ref . © RSNA, 2016 Online supplemental material is available for this article.

  18. Charge versus Energy Transfer Effects in High-Performance Perylene Diimide Photovoltaic Blend Films.

    Science.gov (United States)

    Singh, Ranbir; Shivanna, Ravichandran; Iosifidis, Agathaggelos; Butt, Hans-Jürgen; Floudas, George; Narayan, K S; Keivanidis, Panagiotis E

    2015-11-11

    Perylene diimide (PDI)-based organic photovoltaic devices can potentially deliver high power conversion efficiency values provided the photon energy absorbed is utilized efficiently in charge transfer (CT) reactions instead of being consumed in nonradiative energy transfer (ET) steps. Hitherto, it remains unclear whether ET or CT primarily drives the photoluminescence (PL) quenching of the PDI excimer state in PDI-based blend films. Here, we affirm the key role of the thermally assisted PDI excimer diffusion and subsequent CT reaction in the process of PDI excimer PL deactivation. For our study we perform PL quenching experiments in the model PDI-based composite made of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2-6-diyl] (PBDTTT-CT) polymeric donor mixed with the N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) acceptor. Despite the strong spectral overlap between the PDI excimer PL emission and UV-vis absorption of PBDTTT-CT, two main observations indicate that no significant ET component operates in the overall PL quenching: the PL intensity of the PDI excimer (i) increases with decreasing temperature and (ii) remains unaffected even in the presence of 10 wt % content of the PBDTTT-CT quencher. Temperature-dependent wide-angle X-ray scattering experiments further indicate that nonradiative resonance ET is highly improbable due to the large size of PDI domains. The dominance of the CT over the ET process is verified by the high performance of devices with an optimum composition of 30:70 PBDTTT-CT:PDI. By adding 0.4 vol % of 1,8-diiodooctane we verify the plasticization of the polymer side chains that balances the charge transport properties of the PBDTTT-CT:PDI composite and results in additional improvement in the device efficiency. The temperature-dependent spectral width of the PDI excimer PL band suggests the presence of energetic disorder in the

  19. Systematic radiation dose optimization of abdominal dual-energy CT on a second-generation dual-source CT scanner: assessment of the accuracy of iodine uptake measurement and image quality in an in vitro and in vivo investigations.

    Science.gov (United States)

    Schindera, Sebastian T; Zaehringer, Caroline; D'Errico, Luigia; Schwartz, Fides; Kekelidze, Maka; Szucs-Farkas, Zsolt; Benz, Matthias R

    2017-10-01

    To assess the accuracy of iodine quantification in a phantom study at different radiation dose levels with dual-energy dual-source CT and to evaluate image quality and radiation doses in patients undergoing a single-energy and two dual-energy abdominal CT protocols. In a phantom study, the accuracy of iodine quantification (4.5-23.5 mgI/mL) was evaluated using the manufacturer-recommended and three dose-optimized dual-energy protocols. In a patient study, 75 abdomino-pelvic CT examinations were acquired as follows: 25 CT scans with the manufacturer-recommended dual-energy protocol (protocol A); 25 CT scans with a dose-optimized dual-energy protocol (protocol B); and 25 CT scans with a single-energy CT protocol (protocol C). CTDI vol and objective noise were measured. Five readers scored each scan according to six subjective image quality parameters (noise, contrast, artifacts, visibility of small structures, sharpness, overall diagnostic confidence). In the phantom study, differences between the real and measured iodine concentrations ranged from -8.8% to 17.0% for the manufacturer-recommended protocol and from -1.6% to 20.5% for three dose-optimized protocols. In the patient study, the CTDI vol of protocol A, B, and C were 12.5 ± 1.9, 7.5 ± 1.2, and 6.5 ± 1.7 mGycm, respectively (p dual-energy and the single-energy protocol. A dose reduction of 41% is feasible for the manufacturer-recommended, abdominal dual-energy CT protocol, as it maintained the accuracy of iodine measurements and subjective image quality compared to a single-energy protocol.

  20. High resolution CT of temporal bone trauma

    International Nuclear Information System (INIS)

    Youn, Eun Kyung

    1986-01-01

    Radiographic studies of the temporal bone following head trauma are indicated when there is cerebrospinal fluid otorrhea or rhinorrhoea, hearing loss, or facial nerve paralysis. Plain radiography displays only 17-30% of temporal bone fractures and pluridirectional tomography is both difficult to perform, particularly in the acutely ill patient, and less satisfactory for the demonstration of fine fractures. Consequently, high resolution CT is the imaging method of choice for the investigation of suspected temporal bone trauma and allows special resolution of fine bony detail comparable to that attainable by conventional tomography. Eight cases of temporal bone trauma examined at Korea General Hospital April 1985 through May 1986. The results were as follows: Seven patients (87%) suffered longitudinal fractures. In 6 patients who had purely conductive hearing loss, CT revealed various ossicular chain abnormality. In one patient who had neuro sensory hearing loss, CT demonstrated intract ossicular with a fracture nearing lateral wall of the lateral semicircular canal. In one patient who had mixed hearing loss, CT showed complex fracture.

  1. Pulmonary langerhans cell histiocytosis in adults: high-resolution CT - pathology comparisons and evolutional changes at CT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyo Jin; Lee, Ho Yun; Kim, Tae Sung [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea, Republic of); Lee, Kyung Soo [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea, Republic of); Samsung Medical Center, Department of Radiology, Seoul (Korea, Republic of); Johkoh, Takeshi [Kinki Central Hospital of Mutual Aid Association of Public School Teachers, Department of Radiology, Hyoko (Japan); Tomiyama, Noriyuki [Osaka University Graduate School of Medicine, Department of Radiology, Osaka (Japan); Han, Joungho [Sungkyunkwan University School of Medicine, Department of Pathology, Samsung Medical Center, Seoul (Korea, Republic of)

    2011-07-15

    To compare high-resolution (HR) CT and histopathological findings and to evaluate serial CT findings in pulmonary Langerhans cell histiocytosis (PLCH). We reviewed CT of lung lesions in 27 adults (M:F = 20:7, mean age, 41 {+-} 12.3 years) with PLCH. After evaluating lung abnormalities including nodules, micronodules, thick-walled, thin-walled, and bizarre-shaped cysts and reticulation, observers compared CT findings obtained at lung biopsy sites with histopathological findings. The final CT was compared with the initial CT to determine disease extent changes. The most frequently observed patterns of lung abnormalities were micronodules (n = 24, 89%), thick-walled (n = 22, 82%), and thin-walled (n = 22, 82%) cysts. Even thin-walled and bizarre cysts harboured active inflammatory Langerhans cell sheets and eosinophils in their walls. In thin-walled cysts, we noted pericystic inflammatory cell infiltrations along the alveolar walls, as well as pericystic emphysema. Thin-walled or bizarre cysts demonstrated a tendency to coalesce with surrounding cysts via their cystic wall destruction. Fourteen (52%) patients showed improvement and nine (33%) showed progressing disease. More than half of patients with pulmonary PLCH show improvement at follow-up CT. Even thin-walled cysts harbour active inflammatory cells on histopathology and exhibit improvement at follow-up CT. (orig.)

  2. High resolution extremity CT for biomechanics modeling

    International Nuclear Information System (INIS)

    Ashby, A.E.; Brand, H.; Hollerbach, K.; Logan, C.M.; Martz, H.E.

    1995-01-01

    With the advent of ever more powerful computing and finite element analysis (FEA) capabilities, the bone and joint geometry detail available from either commercial surface definitions or from medical CT scans is inadequate. For dynamic FEA modeling of joints, precise articular contours are necessary to get appropriate contact definition. In this project, a fresh cadaver extremity was suspended in parafin in a lucite cylinder and then scanned with an industrial CT system to generate a high resolution data set for use in biomechanics modeling

  3. High resolution extremity CT for biomechanics modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, A.E.; Brand, H.; Hollerbach, K.; Logan, C.M.; Martz, H.E.

    1995-09-23

    With the advent of ever more powerful computing and finite element analysis (FEA) capabilities, the bone and joint geometry detail available from either commercial surface definitions or from medical CT scans is inadequate. For dynamic FEA modeling of joints, precise articular contours are necessary to get appropriate contact definition. In this project, a fresh cadaver extremity was suspended in parafin in a lucite cylinder and then scanned with an industrial CT system to generate a high resolution data set for use in biomechanics modeling.

  4. High-resolution CT of otosclerosis

    International Nuclear Information System (INIS)

    Dewen, Yang; Kodama, Takao; Tono, Tetsuya; Ochiai, Reiji; Kiyomizu, Kensuke; Suzuki, Yukiko; Yano, Takanori; Watanabe, Katsushi

    1997-01-01

    High-resolution CT (HRCT) scans of thirty-two patients (60 ears) with the clinical diagnosis of fenestral otosclerosis were evaluated retrospectively. HRCT was performed with 1-mm-thick targeted sections and 1-mm (36 ears) or 0.5-mm (10 ears) intervals in the semiaxial projection. Seven patients (14 ears) underwent helical scanning with a 1-mm slice thickness and 1-mm/sec table speed. Forty-five ears (75%) were found to have one or more otospongiotic or otosclerotic foci on HRCT. In most instances (30 ears), the otospongiotic foci were found in the region of the fissula ante fenestram. No significant correlations between CT findings and air conduction threshold were observed. We found a significant relationship between lesions of the labyrinthine capsule and sensorineural hearing loss. We conclude that HRCT is a valuable modality for diagnosing otosclerosis, especially when otospongiotic focus is detected. (author)

  5. Lung nodule detection by microdose CT versus chest radiography (standard and dual-energy subtracted).

    Science.gov (United States)

    Ebner, Lukas; Bütikofer, Yanik; Ott, Daniel; Huber, Adrian; Landau, Julia; Roos, Justus E; Heverhagen, Johannes T; Christe, Andreas

    2015-04-01

    The purpose of this study was to investigate the feasibility of microdose CT using a comparable dose as for conventional chest radiographs in two planes including dual-energy subtraction for lung nodule assessment. We investigated 65 chest phantoms with 141 lung nodules, using an anthropomorphic chest phantom with artificial lung nodules. Microdose CT parameters were 80 kV and 6 mAs, with pitch of 2.2. Iterative reconstruction algorithms and an integrated circuit detector system (Stellar, Siemens Healthcare) were applied for maximum dose reduction. Maximum intensity projections (MIPs) were reconstructed. Chest radiographs were acquired in two projections with bone suppression. Four blinded radiologists interpreted the images in random order. A soft-tissue CT kernel (I30f) delivered better sensitivities in a pilot study than a hard kernel (I70f), with respective mean (SD) sensitivities of 91.1%±2.2% versus 85.6%±5.6% (p=0.041). Nodule size was measured accurately for all kernels. Mean clustered nodule sensitivity with chest radiography was 45.7%±8.1% (with bone suppression, 46.1%±8%; p=0.94); for microdose CT, nodule sensitivity was 83.6%±9% without MIP (with additional MIP, 92.5%±6%; pmicrodose CT for readers 1, 2, 3, and 4 were 84.3%, 90.7%, 68.6%, and 45.0%, respectively. Sensitivities with chest radiography for readers 1, 2, 3, and 4 were 42.9%, 58.6%, 36.4%, and 90.7%, respectively. In the per-phantom analysis, respective sensitivities of microdose CT versus chest radiography were 96.2% and 75% (pmicrodose CT, the applied dose was 0.1323 mSv. Microdose CT is better than the combination of chest radiography and dual-energy subtraction for the detection of solid nodules between 5 and 12 mm at a lower dose level of 0.13 mSv. Soft-tissue kernels allow better sensitivities. These preliminary results indicate that microdose CT has the potential to replace conventional chest radiography for lung nodule detection.

  6. WE-A-BRF-01: Dual-Energy CT Imaging in Diagnostic Imaging and Radiation Therapy

    International Nuclear Information System (INIS)

    Molloi, S; Li, B; Yin, F; Chen, H

    2014-01-01

    classification based on calcium scores shows excellent agreement with classification on the basis of conventional coronary artery calcium scoring. These studies demonstrate dual-energy cardiovascular CT can potentially be a noninvasive and sensitive modality in high risk patients. On-board KV/MV Imaging. To enhance soft tissue contrast and reduce metal artifacts, we have developed a dual-energy CBCT technique and a novel on-board kV/MV imaging technique based on hardware available on modern linear accelerators. We have also evaluated the feasibility of these two techniques in various phantom studies. Optimal techniques (energy, beam filtration, # of overlapping projections, etc) have been investigated with unique calibration procedures, which leads to successful decomposition of imaged material into acrylic-aluminum basis material pair. This enables the synthesis of virtual monochromatic (VM) CBCT images that demonstrate much less beam hardening, significantly reduced metal artifacts, and/or higher soft tissue CNR compared to single-energy CBCT. Adaptive Radiation Therapy. DECT could actually contribute to the area of Dose-Guided Radiation Therapy (or Adaptive Therapy). The application of DECT imaging using 80kV and 140 kV combinations could potentially increase the image quality by reducing the bone or high density material artifacts and also increase the soft tissue contrast by a light contrast agent. The result of this higher contrast / quality images is beneficial for deformable image registration / segmentation algorithm to improve its accuracy hence to make adaptive therapy less time consuming in its recontouring process. The real time re-planning prior to per treatment fraction could become more realistic with this improvement especially in hypofractional SBRT cases. Learning Objectives: Learn recent developments of dual-energy imaging in diagnosis and radiation therapy; Understand the unique clinical problem and required quantification accuracy in each application

  7. Dual-energy CT can detect malignant lymph nodes in rectal cancer.

    Science.gov (United States)

    Al-Najami, I; Lahaye, M J; Beets-Tan, R G H; Baatrup, G

    2017-05-01

    There is a need for an accurate and operator independent method to assess the lymph node status to provide the most optimal personalized treatment for rectal cancer patients. This study evaluates whether Dual Energy Computed Tomography (DECT) could contribute to the preoperative lymph node assessment, and compared it to Magnetic Resonance Imaging (MRI). The objective of this prospective observational feasibility study was to determine the clinical value of the DECT for the detection of metastases in the pelvic lymph nodes of rectal cancer patients and compare the findings to MRI and histopathology. The patients were referred to total mesorectal excision (TME) without any neoadjuvant oncological treatment. After surgery the rectum specimen was scanned, and lymph nodes were matched to the pathology report. Fifty-four histology proven rectal cancer patients received a pelvic DECT scan and a standard MRI. The Dual Energy CT quantitative parameters were analyzed: Water and Iodine concentration, Dual-Energy Ratio, Dual Energy Index, and Effective Z value, for the benign and malignant lymph node differentiation. DECT scanning showed statistical difference between malignant and benign lymph nodes in the measurements of iodine concentration, Dual-Energy Ratio, Dual Energy Index, and Effective Z value. Dual energy CT classified 42% of the cases correctly according to N-stage compared to 40% for MRI. This study showed statistical difference in several quantitative parameters between benign and malignant lymph nodes. There were no difference in the accuracy of lymph node staging between DECT and MRI. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Advanced virtual monoenergetic images: improving the contrast of dual-energy CT pulmonary angiography

    International Nuclear Information System (INIS)

    Meier, A.; Wurnig, M.; Desbiolles, L.; Leschka, S.; Frauenfelder, T.; Alkadhi, H.

    2015-01-01

    Aim: To investigate the value of advanced virtual monoenergetic image reconstruction (mono-plus) from dual-energy computed tomography (CT) for improving the contrast of CT pulmonary angiography (CTPA). Materials and methods: Forty consecutive patients (25 women, mean 62.5 years, range 28–87 years) underwent 192-section dual-source CTPA with dual-energy CT (90/150 SnkVp) after the administration of 60 ml contrast media (300 mg iodine/ml). Conventional virtual monochromatic images at 60 keV and 17 mono-plus image datasets from 40–190 keV (in 10 keV steps) were reconstructed. Subjective image quality (artefacts, subjective noise) was rated. Attenuation was measured in the pulmonary trunk and in the right lower lobe pulmonary artery; noise was measured in the periscapular musculature. The signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated for each patient and dataset. Comparisons between monochromatic images and mono-plus images were performed by repeated measures analysis of variance (ANOVA) with post-hoc Bonferroni correction. Results: Interreader agreement was good to excellent for subjective image quality (ICC: 0.616–0.889). As compared to conventional 60 keV images, artefacts occurred less (p=0.001) and subjective noise was rated lower (p<0.001) in mono-plus 40 keV images. Noise was lower (p<0.001), and the SNR and CNR in the pulmonary trunk and right lower lobe pulmonary artery were higher (both, p<0.001) in mono-plus 40 keV images compared to conventional monoenergetic 60 keV images. Transient interruption of contrast (TIC) was found in 14/40 (35%) of patients, with subjective contrast being similar 8/40 (20%) or higher 32/40 (80%) in mono-plus 40 keV as compared to conventional monoenergetic 60 keV images. Conclusions: Compared to conventional virtual monoenergetic imaging, mono-plus images at 40 keV improve the contrast of dual-energy CTPA. - Highlights: • Advanced monoenergetic image reconstruction from dual-energy CT

  9. Pin-photodiode array for the measurement of fan-beam energy and air kerma distributions of X-ray CT scanners.

    Science.gov (United States)

    Haba, Tomonobu; Koyama, Shuji; Aoyama, Takahiko; Kinomura, Yutaka; Ida, Yoshihiro; Kobayashi, Masanao; Kameyama, Hiroshi; Tsutsumi, Yoshinori

    2016-07-01

    Patient dose estimation in X-ray computed tomography (CT) is generally performed by Monte Carlo simulation of photon interactions within anthropomorphic or cylindrical phantoms. An accurate Monte Carlo simulation requires an understanding of the effects of the bow-tie filter equipped in a CT scanner, i.e. the change of X-ray energy and air kerma along the fan-beam arc of the CT scanner. To measure the effective energy and air kerma distributions, we devised a pin-photodiode array utilizing eight channels of X-ray sensors arranged at regular intervals along the fan-beam arc of the CT scanner. Each X-ray sensor consisted of two plate type of pin silicon photodiodes in tandem - front and rear photodiodes - and of a lead collimator, which only allowed X-rays to impinge vertically to the silicon surface of the photodiodes. The effective energy of the X-rays was calculated from the ratio of the output voltages of the photodiodes and the dose was calculated from the output voltage of the front photodiode using the energy and dose calibration curves respectively. The pin-photodiode array allowed the calculation of X-ray effective energies and relative doses, at eight points simultaneously along the fan-beam arc of a CT scanner during a single rotation of the scanner. The fan-beam energy and air kerma distributions of CT scanners can be effectively measured using this pin-photodiode array. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  10. Limited-angle multi-energy CT using joint clustering prior and sparsity regularization

    Science.gov (United States)

    Zhang, Huayu; Xing, Yuxiang

    2016-03-01

    In this article, we present an easy-to-implement Multi-energy CT scanning strategy and a corresponding reconstruction method, which facilitate spectral CT imaging by improving the data efficiency the number-of-energy- channel fold without introducing visible limited-angle artifacts caused by reducing projection views. Leveraging the structure coherence at different energies, we first pre-reconstruct a prior structure information image using projection data from all energy channels. Then, we perform a k-means clustering on the prior image to generate a sparse dictionary representation for the image, which severs as a structure information constraint. We com- bine this constraint with conventional compressed sensing method and proposed a new model which we referred as Joint Clustering Prior and Sparsity Regularization (CPSR). CPSR is a convex problem and we solve it by Alternating Direction Method of Multipliers (ADMM). We verify our CPSR reconstruction method with a numerical simulation experiment. A dental phantom with complicate structures of teeth and soft tissues is used. X-ray beams from three spectra of different peak energies (120kVp, 90kVp, 60kVp) irradiate the phantom to form tri-energy projections. Projection data covering only 75◦ from each energy spectrum are collected for reconstruction. Independent reconstruction for each energy will cause severe limited-angle artifacts even with the help of compressed sensing approaches. Our CPSR provides us with images free of the limited-angle artifact. All edge details are well preserved in our experimental study.

  11. Dual-energy CT for detection of endoleaks after endovascular abdominal aneurysm repair: usefulness of colored iodine overlay.

    Science.gov (United States)

    Ascenti, Giorgio; Mazziotti, Silvio; Lamberto, Salvatore; Bottari, Antonio; Caloggero, Simona; Racchiusa, Sergio; Mileto, Achille; Scribano, Emanuele

    2011-06-01

    The purpose of our study was to evaluate the value of dual-source dual-energy CT with colored iodine overlay for detection of endoleaks after endovascular abdominal aortic aneurysm repair. We also calculated the potential dose reduction by using a dual-energy CT single-phase protocol. From November 2007 to November 2009, 74 patients underwent CT angiography 2-7 days after endovascular repair during single-energy unenhanced and dual-energy venous phases. By using dual-energy software, the iodine overlay was superimposed on venous phase images with different percentages ranging between 0 (virtual unenhanced images) and 50-75% to show the iodine in an orange color. Two blinded readers evaluated the data for diagnosis of endoleaks during standard unenhanced and venous phase images (session 1, standard of reference) and virtual unenhanced and venous phase images with colored iodine overlay images (session 2). We compared the effective dose radiation of a single-energy biphasic protocol with that of a single-phase dual-energy protocol. The diagnostic accuracy of session 2 was calculated. The mean dual-energy effective dose was 7.27 mSv. By using a dual-energy single-phase protocol, we obtained a mean dose reduction of 28% with respect to a single-energy biphasic protocol. The diagnostic accuracy of session 2 was: 100% sensitivity, 100% specificity, 100% negative predictive value, and 100% positive predictive value. Statistically significant differences in the level of confidence for endoleak detection between the two sessions were found by reviewers for scores 3-5. Dual-energy CT with colored iodine overlay is a useful diagnostic tool in endoleak detection. The use of a dual-energy single-phase study protocol will lower radiation exposure to patients.

  12. Reduction of ring artefacts in high resolution micro-CT reconstructions

    International Nuclear Information System (INIS)

    Sijbers, Jan; Postnov, Andrei

    2004-01-01

    High resolution micro-CT images are often corrupted by ring artefacts, prohibiting quantitative analysis and hampering post processing. Removing or at least significantly reducing such artefacts is indispensable. However, since micro-CT systems are pushed to the extremes in the quest for the ultimate spatial resolution, ring artefacts can hardly be avoided. Moreover, as opposed to clinical CT systems, conventional correction schemes such as flat-field correction do not lead to satisfactory results. Therefore, in this note a simple but efficient and fast post processing method is proposed that effectively reduces ring artefacts in reconstructed μ-CT images. (note)

  13. Application of high resolution synchrotron micro-CT radiation in dental implant osseointegration

    DEFF Research Database (Denmark)

    Neldam, Camilla Albeck; Lauridsen, Torsten; Rack, Alexander

    2015-01-01

    The purpose of this study was to describe a refined method using high-resolution synchrotron radiation microtomography (SRmicro-CT) to evaluate osseointegration and peri-implant bone volume fraction after titanium dental implant insertion. SRmicro-CT is considered gold standard evaluating bone...... microarchitecture. Its high resolution, high contrast, and excellent high signal-to-noise-ratio all contribute to the highest spatial resolutions achievable today. Using SRmicro-CT at a voxel size of 5 μm in an experimental goat mandible model, the peri-implant bone volume fraction was found to quickly increase...

  14. Ring artifact correction for high-resolution micro CT

    International Nuclear Information System (INIS)

    Kyriakou, Yiannis; Prell, Daniel; Kalender, Willi A

    2009-01-01

    In high-resolution micro CT using flat detectors (FD), imperfect or defect detector elements may cause concentric-ring artifacts due to their continuous over- or underestimation of attenuation values, which often disturb image quality. We here present a dedicated image-based ring artifact correction method for high-resolution micro CT, based on median filtering of the reconstructed image and working on a transformed version of the reconstructed images in polar coordinates. This post-processing method reduced ring artifacts in the reconstructed images and improved image quality for phantom and in in vivo scans. Noise and artifacts were reduced both in transversal and in multi-planar reformations along the longitudinal axis. (note)

  15. Dosimetric Evaluation of Metal Artefact Reduction using Metal Artefact Reduction (MAR) Algorithm and Dual-energy Computed Tomography (CT) Method

    Science.gov (United States)

    Laguda, Edcer Jerecho

    Purpose: Computed Tomography (CT) is one of the standard diagnostic imaging modalities for the evaluation of a patient's medical condition. In comparison to other imaging modalities such as Magnetic Resonance Imaging (MRI), CT is a fast acquisition imaging device with higher spatial resolution and higher contrast-to-noise ratio (CNR) for bony structures. CT images are presented through a gray scale of independent values in Hounsfield units (HU). High HU-valued materials represent higher density. High density materials, such as metal, tend to erroneously increase the HU values around it due to reconstruction software limitations. This problem of increased HU values due to metal presence is referred to as metal artefacts. Hip prostheses, dental fillings, aneurysm clips, and spinal clips are a few examples of metal objects that are of clinical relevance. These implants create artefacts such as beam hardening and photon starvation that distort CT images and degrade image quality. This is of great significance because the distortions may cause improper evaluation of images and inaccurate dose calculation in the treatment planning system. Different algorithms are being developed to reduce these artefacts for better image quality for both diagnostic and therapeutic purposes. However, very limited information is available about the effect of artefact correction on dose calculation accuracy. This research study evaluates the dosimetric effect of metal artefact reduction algorithms on severe artefacts on CT images. This study uses Gemstone Spectral Imaging (GSI)-based MAR algorithm, projection-based Metal Artefact Reduction (MAR) algorithm, and the Dual-Energy method. Materials and Methods: The Gemstone Spectral Imaging (GSI)-based and SMART Metal Artefact Reduction (MAR) algorithms are metal artefact reduction protocols embedded in two different CT scanner models by General Electric (GE), and the Dual-Energy Imaging Method was developed at Duke University. All three

  16. 1024 matrix image reconstruction: usefulness in high resolution chest CT

    International Nuclear Information System (INIS)

    Jeong, Sun Young; Chung, Myung Jin; Chong, Se Min; Sung, Yon Mi; Lee, Kyung Soo

    2006-01-01

    We tried to evaluate whether high resolution chest CT with a 1,024 matrix has a significant advantage in image quality compared to a 512 matrix. Each set of 512 and 1024 matrix high resolution chest CT scans with both 0.625 mm and 1.25 mm slice thickness were obtained from 26 patients. Seventy locations that contained twenty-four low density lesions without sharp boundary such as emphysema, and forty-six sharp linear densities such as linear fibrosis were selected; these were randomly displayed on a five mega pixel LCD monitor. All the images were masked for information concerning the matrix size and slice thickness. Two chest radiologists scored the image quality of each ar rowed lesion as follows: (1) undistinguishable, (2) poorly distinguishable, (3) fairly distinguishable, (4) well visible and (5) excellently visible. The scores were compared from the aspects of matrix size, slice thickness and the different observers by using ANOVA tests. The average and standard deviation of image quality were 3.09 (± .92) for the 0.625 mm x 512 matrix, 3.16 (± .84) for the 0.625 mm x 1024 matrix, 2.49 (± 1.02) for the 1.25 mm x 512 matrix, and 2.35 (± 1.02) for the 1.25 mm x 1024 matrix, respectively. The image quality on both matrices of the high resolution chest CT scans with a 0.625 mm slice thickness was significantly better than that on the 1.25 mm slice thickness (ρ < 0.001). However, the image quality on the 1024 matrix high resolution chest CT scans was not significantly different from that on the 512 matrix high resolution chest CT scans (ρ = 0.678). The interobserver variation between the two observers was not significant (ρ = 0.691). We think that 1024 matrix image reconstruction for high resolution chest CT may not be clinical useful

  17. Simplified derivation of stopping power ratio in the human body from dual-energy CT data.

    Science.gov (United States)

    Saito, Masatoshi; Sagara, Shota

    2017-08-01

    The main objective of this study is to propose an alternative parameterization for the empirical relation between mean excitation energies (I-value) and effective atomic numbers (Z eff ) of human tissues, and to present a simplified formulation (which we called DEEDZ-SPR) for deriving the stopping power ratio (SPR) from dual-energy (DE) CT data via electron density (ρ e ) and Z eff calibration. We performed a numerical analysis of this DEEDZ-SPR method for the human-body-equivalent tissues of ICRU Report 46, as objects of interest with unknown SPR and ρ e . The attenuation coefficients of these materials were calculated using the XCOM photon cross-sections database. We also applied the DEEDZ-SPR conversion to experimental DECT data available in the literature, which was measured for the tissue-characterization phantom using a dual-source CT scanner at 80 kV and 140 kV/Sn. It was found that the DEEDZ-SPR conversion enables the calculation of SPR simply by means of the weighted subtraction of an electron-density image and a low- or high-kV CT image. The simulated SPRs were in excellent agreement with the reference values over the SPR range from 0.258 (lung) to 3.638 (bone mineral-hydroxyapatite). The relative deviations from the reference SPR were within ±0.6% for all ICRU-46 human tissues, except for the thyroid that presented a -1.1% deviation. The overall root-mean-square error was 0.21%. Application to experimental DECT data confirmed this agreement within the experimental accuracy, which demonstrates the practical feasibility of the method. The DEEDZ-SPR conversion method could facilitate the construction of SPR images as accurately as a recent DECT-based calibration procedure of SPR parameterization based directly on the CT numbers in a DECT data set. © 2017 American Association of Physicists in Medicine.

  18. Feasibility of Single Scan for Simultaneous Evaluation of Regional Krypton and Iodine Concentrations with Dual-Energy CT: An Experimental Study.

    Science.gov (United States)

    Hong, Sae Rom; Chang, Suyon; Im, Dong Jin; Suh, Young Joo; Hong, Yoo Jin; Hur, Jin; Kim, Young Jin; Choi, Byoung Wook; Lee, Hye-Jeong

    2016-11-01

    Purpose To evaluate the feasibility of a simultaneous single scan of regional krypton and iodine concentrations by using dual-energy computed tomography (CT). Materials and Methods The study was approved by the institutional animal experimental committee. An airway obstruction model was first made in 10 beagle dogs, and a pulmonary arterial occlusion was induced in each animal after 1 week. For each model, three sessions of dual-energy CT (80% krypton ventilation [krypton CT], 80% krypton ventilation with iodine enhancement [mixed-contrast agent CT], and iodine enhancement [iodine CT]) were performed. Krypton maps were made from krypton and mixed-contrast agent CT, and iodine maps were made from iodine and mixed-contrast agent CT. Observers measured overlay Hounsfield units of the diseased and contralateral segments on each map. Values were compared by using the Wilcoxon signed-rank test. Results In krypton maps of airway obstruction, overlay Hounsfield units of diseased segments were significantly decreased compared with those of contralateral segments in both krypton and mixed-contrast agent CT (P = .005 for both). However, the values of mixed-contrast agent CT were significantly higher than those of krypton CT for both segments (P = .005 and .007, respectively). In iodine maps of pulmonary arterial occlusion, values were significantly lower in diseased segments than in contralateral segments for both iodine and mixed-contrast agent CT (P = .005 for both), without significant difference between iodine and mixed-contrast agent CT for both segments (P = .126 and .307, respectively). Conclusion Although some limitations may exist, it might be feasible to analyze regional krypton and iodine concentrations simultaneously by using dual-energy CT. © RSNA, 2016.

  19. Multiphase contrast-enhanced CT with highly concentrated contrast agent can be used for PET attenuation correction in integrated PET/CT imaging

    International Nuclear Information System (INIS)

    Aschoff, Philip; Plathow, Christian; Lichy, Matthias P.; Claussen, Claus D.; Pfannenberg, Christina; Beyer, Thomas; Erb, Gunter; Oeksuez, Mehmet Oe.

    2012-01-01

    State-of-the-art positron emission tomography/computed tomography (PET/CT) systems incorporate multislice CT technology, thus facilitating the acquisition of multiphase, contrast-enhanced CT data as part of integrated PET/CT imaging protocols. We assess the influence of a highly concentrated iodinated contrast medium (CM) on quantification and image quality following CT-based attenuation correction (CT-AC) in PET/CT. Twenty-eight patients with suspected malignant liver lesions were enrolled prospectively. PET/CT was performed 60 min after injection of 400 MBq of 18 F-fluorodeoxyglucose (FDG) and following the biphasic administration of an intravenous CM (400 mg iodine/ml, Iomeron 400). PET images were reconstructed with CT-AC using any of four acquired CT image sets: non-enhanced, pre-contrast (n-PET), arterial phase (art-PET), portal venous phase (pv-PET) and late phase (late-PET). Normal tissue activity and liver lesions were assessed visually and quantitatively on each PET/CT image set. Visual assessment of PET following CT-AC revealed no noticeable difference in image appearance or quality when using any of the four CT data sets for CT-AC. A total of 44 PET-positive liver lesions was identified in 21 of 28 patients. There were no false-negative or false-positive lesions on PET. Mean standardized uptake values (SUV) in 36 evaluable lesions were: 5.5 (n-PET), 5.8 (art-PET), 5.8 (pv-PET) and 5.8 (late-PET), with the highest mean increase in mean SUV of 6%. Mean SUV changes in liver background increased by up to 10% from n-PET to pv-PET. Multiphase CT data acquired with the use of highly concentrated CM can be used for qualitative assessment of liver lesions in torso FDG PET/CT. The influence on quantification of FDG uptake is small and negligible for most clinical applications. (orig.)

  20. Optimized energy of spectral CT for infarct imaging: Experimental validation with human validation.

    Science.gov (United States)

    Sandfort, Veit; Palanisamy, Srikanth; Symons, Rolf; Pourmorteza, Amir; Ahlman, Mark A; Rice, Kelly; Thomas, Tom; Davies-Venn, Cynthia; Krauss, Bernhard; Kwan, Alan; Pandey, Ankur; Zimmerman, Stefan L; Bluemke, David A

    Late contrast enhancement visualizes myocardial infarction, but the contrast to noise ratio (CNR) is low using conventional CT. The aim of this study was to determine if spectral CT can improve imaging of myocardial infarction. A canine model of myocardial infarction was produced in 8 animals (90-min occlusion, reperfusion). Later, imaging was performed after contrast injection using CT at 90 kVp/150 kVpSn. The following reconstructions were evaluated: Single energy 90 kVp, mixed, iodine map, multiple monoenergetic conventional and monoenergetic noise optimized reconstructions. Regions of interest were measured in infarct and remote regions to calculate contrast to noise ratio (CNR) and Bhattacharya distance (a metric of the differentiation between regions). Blinded assessment of image quality was performed. The same reconstruction methods were applied to CT scans of four patients with known infarcts. For animal studies, the highest CNR for infarct vs. myocardium was achieved in the lowest keV (40 keV) VMo images (CNR 4.42, IQR 3.64-5.53), which was superior to 90 kVp, mixed and iodine map (p = 0.008, p = 0.002, p energy in conjunction with noise-optimized monoenergetic post-processing improves CNR of myocardial infarct delineation by approximately 20-25%. Published by Elsevier Inc.

  1. Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT

    International Nuclear Information System (INIS)

    Okada, Munemasa; Nakashima, Yoshiteru; Kunihiro, Yoshie; Nakao, Sei; Matsunaga, Naofumi; Morikage, Noriyasu; Sano, Yuichi; Suga, Kazuyoshi

    2013-01-01

    Background: Dual-energy perfusion CT (DE p CT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas. Purpose: To evaluate if volumetric evaluation of DE p CT can be used as a predictor of right heart strain by the presence of IPCs. Material and Methods: One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DE p CT using a 64-slice dual-source CT. DE p CT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V 120 ), 1-15 HU (V 15 ), 1-10 HU (V 10 ), and 1-5 HU (V 5 ). Each relative ratio per V 120 was expressed as the %V 15 , %V 10 , and %V 5 . Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee. Results: PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V 15 , V 10 , V 5 , %V 15 , %V 10 , and %V 5 were also significantly higher than those without IPC (P = 0.001). %V 5 had a better correlation with D-dimer (r = 0.30, P p CT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE

  2. Comparing 511 keV Attenuation Maps Obtained from Different Energy Mapping Methods for CT Based Attenuation Correction of PET Data

    Directory of Open Access Journals (Sweden)

    Maryam Shirmohammad

    2008-06-01

    Full Text Available Introduction:  The  advent  of  dual-modality  PET/CT  scanners  has  revolutionized  clinical  oncology  by  improving lesion localization and facilitating treatment planning for radiotherapy. In addition, the use of  CT images for CT-based attenuation correction (CTAC decreases the overall scanning time and creates  a noise-free  attenuation  map  (6map.  CTAC  methods  include  scaling,  segmentation,  hybrid  scaling/segmentation, bilinear and dual energy methods. All CTAC methods require the transformation  of CT Hounsfield units (HU to linear attenuation coefficients (LAC at 511 keV. The aim of this study is  to compare the results of implementing different methods of energy mapping in PET/CT scanners.   Materials and Methods: This study was conducted in 2 phases, the first phase in a phantom and the  second  one  on  patient  data.  To  perform  the  first  phase,  a  cylindrical  phantom  with  different  concentrations of K2HPO4 inserts was CT scanned and energy mapping methods were implemented on  it. For performing the second phase, different energy  mapping  methods  were implemented on several  clinical studies and compared to the transmission (TX image derived using Ga-68 radionuclide source  acquired on the GE Discovery LS PET/CT scanner.   Results: An ROI analysis was performed on different positions of the resultant 6maps and the average  6value of each ROI was compared to the reference value. The results of the 6maps obtained for 511 keV  compared to the theoretical  values showed that in the phantom for low  concentrations  of K 2 HPO 4 all  these  methods  produce  511  keV  attenuation  maps  with  small  relative  difference  compared  to  gold  standard. The relative difference for scaling, segmentation, hybrid, bilinear and dual energy methods was  4.92,  3.21,  4.43,  2.24  and  2.29%,  respectively.  Although  for  high  concentration

  3. Multi-energy CT based on a prior rank, intensity and sparsity model (PRISM)

    International Nuclear Information System (INIS)

    Gao, Hao; Osher, Stanley; Yu, Hengyong; Wang, Ge

    2011-01-01

    We propose a compressive sensing approach for multi-energy computed tomography (CT), namely the prior rank, intensity and sparsity model (PRISM). To further compress the multi-energy image for allowing the reconstruction with fewer CT data and less radiation dose, the PRISM models a multi-energy image as the superposition of a low-rank matrix and a sparse matrix (with row dimension in space and column dimension in energy), where the low-rank matrix corresponds to the stationary background over energy that has a low matrix rank, and the sparse matrix represents the rest of distinct spectral features that are often sparse. Distinct from previous methods, the PRISM utilizes the generalized rank, e.g., the matrix rank of tight-frame transform of a multi-energy image, which offers a way to characterize the multi-level and multi-filtered image coherence across the energy spectrum. Besides, the energy-dependent intensity information can be incorporated into the PRISM in terms of the spectral curves for base materials, with which the restoration of the multi-energy image becomes the reconstruction of the energy-independent material composition matrix. In other words, the PRISM utilizes prior knowledge on the generalized rank and sparsity of a multi-energy image, and intensity/spectral characteristics of base materials. Furthermore, we develop an accurate and fast split Bregman method for the PRISM and demonstrate the superior performance of the PRISM relative to several competing methods in simulations. (papers)

  4. Advances in CT imaging for urolithiasis

    Directory of Open Access Journals (Sweden)

    Yasir Andrabi

    2015-01-01

    Full Text Available Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT is highly sensitive (>95% and specific (>96% in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT and technological innovations in CT such as dual-energy CT (DECT has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice.

  5. Adrenal incidentaloma triage with single source (fast kVp switch) dual energy CT

    Science.gov (United States)

    Glazer, Daniel I; Keshavarzi, Nahid R; Parker, Robert A; Kaza, Ravi K; Platt, Joel F; Francis, Isaac R

    2015-01-01

    Purpose To evaluate single source dual energy CT (DECT) for distinguishing benign and indeterminate adrenal nodules, with attention to effects of phase of intravenous contrast enhancement. Materials and methods An IRB-approved, HIPAA-compliant retrospective review revealed 273 contrast-enhanced abdominal DECTs from November 2009–March 2012. 50 adrenal nodules ≥ 0.8 cm were identified in 41 patients: 22 female, 19 male, average age 66 (range 36–88 years). CT post-processing and measurements were independently performed by two radiologists (R1 and R2) for each nodule: (1) HU on true non-contrast images; (2) post-contrast HU on monochromatic spectral images at 40, 75, and 140 keV; (3) post-contrast material density (mg/cc) on virtual non-contrast (VNC) images. Nodules were separated into benign (VNC images, benign nodules had significantly lower material density (R1: 992.4 mg/cc ± 9.9; R2: 992.7 mg/cc ±9.6) than indeterminate nodules (R1: 1001.1mg/cc ±20.5 (p .038); R2: 1007.6 HU ±13.4 (p <.0001). Conclusion DECT tools can mathematically subtract iodine or minimize its effects in high energy reconstructions, approximating non-contrast imaging and potentially reducing the need for additional studies to triage adrenal nodules detected on post-contrast DECT exams. PMID:25055267

  6. Photon CT scanning of advanced ceramic materials

    International Nuclear Information System (INIS)

    Sawicka, B.D.; Ellingson, W.A.

    1987-02-01

    Advanced ceramic materials are being developed for high temperature applications in advanced heat engines and high temperature heat recovery systems. Small size flaws (10 - 200 μm) and small nonuniformities in density distributions (0.1 -2%) present as long-range density gradients, are critical in most ceramics and their detection is of crucial importance. Computed tomographic (CT) imaging provides a means of obtaining a precise two-dimensional density map of a cross section through an object from which accurate information about small flaws and small density gradients can be obtained. With the use of high energy photon sources high contrast CT images can be obtained for both low and high density ceramics. In the present paper we illustrate the applicability of the photon CT technique to the examination of advanced ceramics. CT images of sintered alumina tiles are presented from which data on high-density inclusions, cracks and density gradients have been extracted

  7. Dual energy CT at the synchrotron: A piglet model for neurovascular research

    International Nuclear Information System (INIS)

    Schueltke, Elisabeth; Kelly, Michael E.; Nemoz, Christian; Fiedler, Stefan; Ogieglo, Lissa; Crawford, Paul; Paterson, Jessica; Beavis, Cole; Esteve, Francois; Brochard, Thierry; Renier, Michel; Requardt, Herwig; Dallery, Dominique; Le Duc, Geraldine; Meguro, Kotoo

    2011-01-01

    Background: Although the quality of imaging techniques available for neurovascular angiography in the hospital environment has significantly improved over the last decades, the equipment used for clinical work is not always suited for neurovascular research in animal models. We have previously investigated the suitability of synchrotron-based K-edge digital subtraction angiography (KEDSA) after intravenous injection of iodinated contrast agent for neurovascular angiography in radiography mode in both rabbit and pig models. We now have used the KEDSA technique for the acquisition of three-dimensional images and dual energy CT. Materials and methods: All experiments were conducted at the biomedical beamline ID 17 of the European Synchrotron Radiation Facility (ESRF). A solid state germanium (Ge) detector was used for the acquisition of image pairs at 33.0 and 33.3 keV. Three-dimensional images were reconstructed from an image series containing 60 single images taken throughout a full rotation of 360 o . CT images were reconstructed from two half-acquisitions with 720 projections each. Results: The small detector field of view was a limiting factor in our experiments. Nevertheless, we were able to show that dual energy CT using the KEDSA technique available at ID 17 is suitable for neurovascular research in animal models.

  8. Dual energy CT at the synchrotron: a piglet model for neurovascular research.

    Science.gov (United States)

    Schültke, Elisabeth; Kelly, Michael E; Nemoz, Christian; Fiedler, Stefan; Ogieglo, Lissa; Crawford, Paul; Paterson, Jessica; Beavis, Cole; Esteve, Francois; Brochard, Thierry; Renier, Michel; Requardt, Herwig; Dallery, Dominique; Le Duc, Geraldine; Meguro, Kotoo

    2011-08-01

    Although the quality of imaging techniques available for neurovascular angiography in the hospital environment has significantly improved over the last decades, the equipment used for clinical work is not always suited for neurovascular research in animal models. We have previously investigated the suitability of synchrotron-based K-edge digital subtraction angiography (KEDSA) after intravenous injection of iodinated contrast agent for neurovascular angiography in radiography mode in both rabbit and pig models. We now have used the KEDSA technique for the acquisition of three-dimensional images and dual energy CT. All experiments were conducted at the biomedical beamline ID 17 of the European Synchrotron Radiation Facility (ESRF). A solid state germanium (Ge) detector was used for the acquisition of image pairs at 33.0 and 33.3 keV. Three-dimensional images were reconstructed from an image series containing 60 single images taken throughout a full rotation of 360°. CT images were reconstructed from two half-acquisitions with 720 projections each. The small detector field of view was a limiting factor in our experiments. Nevertheless, we were able to show that dual energy CT using the KEDSA technique available at ID 17 is suitable for neurovascular research in animal models. Copyright © 2010. Published by Elsevier Ireland Ltd.

  9. Predictive value of low tube voltage and dual-energy CT for successful shock wave lithotripsy: an in vitro study.

    Science.gov (United States)

    Largo, Remo; Stolzmann, Paul; Fankhauser, Christian D; Poyet, Cédric; Wolfsgruber, Pirmin; Sulser, Tullio; Alkadhi, Hatem; Winklhofer, Sebastian

    2016-06-01

    This study investigates the capabilities of low tube voltage computed tomography (CT) and dual-energy CT (DECT) for predicting successful shock wave lithotripsy (SWL) of urinary stones in vitro. A total of 33 urinary calculi (six different chemical compositions; mean size 6 ± 3 mm) were scanned using a dual-source CT machine with single- (120 kVp) and dual-energy settings (80/150, 100/150 Sn kVp) resulting in six different datasets. The attenuation (Hounsfield Units) of calculi was measured on single-energy CT images and the dual-energy indices (DEIs) were calculated from DECT acquisitions. Calculi underwent SWL and the number of shock waves for successful disintegration was recorded. The prediction of required shock waves regarding stone attenuation/DEI was calculated using regression analysis (adjusted for stone size and composition) and the correlation between CT attenuation/DEI and the number of shock waves was assessed for all datasets. The median number of shock waves for successful stone disintegration was 72 (interquartile range 30-361). CT attenuation/DEI of stones was a significant, independent predictor (P waves with the best prediction at 80 kVp (β estimate 0.576) (P waves ranged between ρ = 0.31 and 0.68 showing the best correlation at 80 kVp (P < 0.001). The attenuation of urinary stones at low tube voltage CT is the best predictor for successful stone disintegration, being independent of stone composition and size. DECT shows no added value for predicting the success of SWL.

  10. Tuberculous otitis media: findings on high-resolution CT

    International Nuclear Information System (INIS)

    Lungenschmid, D.; Buchberger, W.; Schoen, G.; Schoepf, R.; Mihatsch, T.; Birbamer, G.; Wicke, K.

    1993-01-01

    We describe two cases of tuberculous otitis media studied with high-resolution computed tomography (CT). Findings included extensive soft tissue densities with fluid levels in the tympanic cavity, the antrum, the mastoid and petrous air cells. Multifocal bony erosions and reactive bone sclerosis were seen as well. CT proved valuable for planning therapy by accurately displaying the involvement of the various structures of the middle and inner ear. However, the specific nature of the disease could only be presumed. (orig.)

  11. Scaling-law for the energy dependence of anatomic power spectrum in dedicated breast CT

    Energy Technology Data Exchange (ETDEWEB)

    Vedantham, Srinivasan; Shi, Linxi; Glick, Stephen J.; Karellas, Andrew [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States)

    2013-01-15

    Purpose: To determine the x-ray photon energy dependence of the anatomic power spectrum of the breast when imaged with dedicated breast computed tomography (CT). Methods: A theoretical framework for scaling the empirically determined anatomic power spectrum at one x-ray photon energy to that at any given x-ray photon energy when imaged with dedicated breast CT was developed. Theory predicted that when the anatomic power spectrum is fitted with a power curve of the form k f{sup -{beta}}, where k and {beta} are fit coefficients and f is spatial frequency, the exponent {beta} would be independent of x-ray photon energy (E), and the amplitude k scales with the square of the difference in energy-dependent linear attenuation coefficients of fibroglandular and adipose tissues. Twenty mastectomy specimens based numerical phantoms that were previously imaged with a benchtop flat-panel cone-beam CT system were converted to 3D distribution of glandular weight fraction (f{sub g}) and were used to verify the theoretical findings. The 3D power spectrum was computed in terms of f{sub g} and after converting to linear attenuation coefficients at monoenergetic x-ray photon energies of 20-80 keV in 5 keV intervals. The 1D power spectra along the axes were extracted and fitted with a power curve of the form k f{sup -{beta}}. The energy dependence of k and {beta} were analyzed. Results: For the 20 mastectomy specimen based numerical phantoms used in the study, the exponent {beta} was found to be in the range of 2.34-2.42, depending on the axis of measurement. Numerical simulations agreed with the theoretical predictions that for a power-law anatomic spectrum of the form k f{sup -{beta}}, {beta} was independent of E and k(E) =k{sub 1}[{mu}{sub g}(E) -{mu}{sub a}(E)]{sup 2}, where k{sub 1} is a constant, and {mu}{sub g}(E) and {mu}{sub a}(E) represent the energy-dependent linear attenuation coefficients of fibroglandular and adipose tissues, respectively. Conclusions: Numerical

  12. Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Munemasa; Nakashima, Yoshiteru; Kunihiro, Yoshie; Nakao, Sei; Matsunaga, Naofumi [Dept. of Radiology, Yamaguchi Univ. Graduate School of Medicine, Yamaguchi (Japan)], e-mail: radokada@yamaguchi-u.ac.jp; Morikage, Noriyasu [Medical Bioregulation Dept. of Organ Regulatory Surgery, Yamaguchi Univ. Graduate School of Medicine, Yamaguchi (Japan); Sano, Yuichi [Dept. of Radiology, Yamaguchi Univ. Hospital, Yamaguchi (Japan); Suga, Kazuyoshi [Dept. of Radiology, St Hills Hospital, Yamaguchi (Japan)

    2013-07-15

    Background: Dual-energy perfusion CT (DE{sub p}CT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas. Purpose: To evaluate if volumetric evaluation of DE{sub p}CT can be used as a predictor of right heart strain by the presence of IPCs. Material and Methods: One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DE{sub p}CT using a 64-slice dual-source CT. DE{sub p}CT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V{sub 120}), 1-15 HU (V{sub 15}), 1-10 HU (V{sub 10}), and 1-5 HU (V{sub 5}). Each relative ratio per V{sub 120} was expressed as the %V{sub 15}, %V{sub 10}, and %V{sub 5}. Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee. Results: PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V{sub 15}, V{sub 10}, V{sub 5}, %V{sub 15}, %V{sub 10}, and %V{sub 5} were also significantly higher than those without IPC (P = 0.001). %V{sub 5} had a better correlation with D-dimer (r = 0.30, P < 0.001) and RV/LV diameter ratio (r = 0.27, P < 0.001), and showed a higher AUC (0.73) than the other CT measurements. Conclusion: The volumetric evaluation by DE{sub p}CT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE.

  13. Unresectable colorectal liver metastases. Percutaneous ablation using CT-guided high-dose-rate brachytherapy (CT-HDBRT); Nicht resektable kolorektale Lebermetastasen. Perkutane Ablation mittels CT-gesteuerter Hochdosisbrachytherapie (CT-HDBRT)

    Energy Technology Data Exchange (ETDEWEB)

    Collettini, F.; Lutter, A.; Schnapauff, D.; Denecke, T.; Gebauer, B. [Charite, Campus Virchow-Klinikum, Berlin (Germany). Dept. of Diagnostic and Interventional Radiology; Hildebrandt, B. [Charite, Campus Virchow-Klinikum, Berlin (Germany). Dept. of Oncology; Puhl, G. [Charite, Campus Virchow-Klinikum, Berlin (Germany). Dept. of General, Visceral and Transplantation Surgery; Wust, P. [Charite, Campus Virchow-Klinikum, Berlin (Germany). Dept. of Radiation Oncology

    2014-06-15

    Purpose: To evaluate the clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) of unresectable colorectal liver metastases (CRLMs). Materials and Methods: Retrospective analysis of all consecutive patients with unresectable CRLMs treated with CT-HDRBT between January 2008 and November 2012. Treatment was performed by CT-guided catheter placement and high-dose-rate brachytherapy with an iridium-192 source. MRI follow-up was performed after 6 weeks and then every 3 months post-intervention. The primary endpoint was local tumor control (LTC); secondary endpoints included time to progression (TTP) and overall survival (OS). Results: 80 heavily pretreated patients with 179 metastases were available for MRI evaluation for a mean follow-up time of 16.9 months. The mean tumor diameter was 28.5 mm (range: 8 - 107 mm). No major complications were observed. A total of 23 (12.9%) local tumor progressions were observed. Lesions ≥ 4 cm in diameter showed significantly more local progression than smaller lesions (< 4 cm). 50 patients (62.5%) experienced systemic tumor progression. The median TTP was 6 months. 28 (43%) patients died during the follow-up period. The median OS after ablation was 18 months. Conclusion: CT-HDRBT is an effective technique for the treatment of unresectable CRLMs and warrants promising LTC rates compared to thermal ablative techniques. A combination with other local and systemic therapies should be evaluated in patients with lesions > 4 cm in diameter, in which higher progression rates are expected. (orig.)

  14. Spectral CT of carotid atherosclerotic plaque: comparison with histology

    Energy Technology Data Exchange (ETDEWEB)

    Zainon, R.; Doesburg, R.M. [University of Canterbury, Department of Physics and Astronomy, Christchurch (New Zealand); Ronaldson, J.P.; Gieseg, S.P. [University of Otago, Centre for Bioengineering, Christchurch (New Zealand); Janmale, T. [University of Canterbury, Free Radical Biochemistry Laboratory, School of Biological Sciences, Christchurch (New Zealand); Scott, N.J. [University of Otago, Department of Medicine, Christchurch (New Zealand); Buckenham, T.M. [University of Otago, Department of Academic Radiology, Christchurch (New Zealand); Butler, A.P.H. [University of Otago, Centre for Bioengineering, Christchurch (New Zealand); University of Otago, Department of Academic Radiology, Christchurch (New Zealand); University of Canterbury, Department of Electrical and Computer Engineering, Christchurch (New Zealand); European Organisation for Nuclear Research (CERN), Geneva (Switzerland); Butler, P.H. [University of Canterbury, Department of Physics and Astronomy, Christchurch (New Zealand); European Organisation for Nuclear Research (CERN), Geneva (Switzerland); Roake, J.A. [Christchurch Hospital, Department of Vascular, Endovascular and Transplant Surgery, Christchurch (New Zealand); Anderson, N.G. [University of Otago, Centre for Bioengineering, Christchurch (New Zealand); University of Otago, Department of Academic Radiology, Christchurch (New Zealand); University of Otago, Christchurch, Department of Radiology, PO Box 4345, Christchurch (New Zealand)

    2012-12-15

    To distinguish components of vulnerable atherosclerotic plaque by imaging their energy response using spectral CT and comparing images with histology. After spectroscopic calibration using phantoms of plaque surrogates, excised human carotid atherosclerotic plaques were imaged using MARS CT using a photon-processing detector with a silicon sensor layer and microfocus X-ray tube (50 kVp, 0.5 mA) at 38-{mu}m voxel size. The plaques were imaged, sectioned and re-imaged using four threshold energies: 10, 16, 22 and 28 keV; then sequentially stained with modified Von Kossa, Perl's Prussian blue and Oil-Red O, and photographed. Relative Hounsfield units across the energies were entered into a linear algebraic material decomposition model to identify the unknown plaque components. Lipid, calcium, iron and water-like components of plaque have distinguishable energy responses to X-ray, visible on spectral CT images. CT images of the plaque surface correlated very well with histological photographs. Calcium deposits (>1,000 {mu}m) in plaque are larger than iron deposits (<100 {mu}m), but could not be distinguished from each other within the same voxel using the energy range available. Spectral CT displays energy information in image form at high spatial resolution, enhancing the intrinsic contrast of lipid, calcium and iron within atheroma. (orig.)

  15. Diagnostic accuracy of high-definition CT coronary angiography in high-risk patients

    International Nuclear Information System (INIS)

    Iyengar, S.S.; Morgan-Hughes, G.; Ukoumunne, O.; Clayton, B.; Davies, E.J.; Nikolaou, V.; Hyde, C.J.; Shore, A.C.; Roobottom, C.A.

    2016-01-01

    Aim: To assess the diagnostic accuracy of computed tomography coronary angiography (CTCA) using a combination of high-definition CT (HD-CTCA) and high level of reader experience, with invasive coronary angiography (ICA) as the reference standard, in high-risk patients for the investigation of coronary artery disease (CAD). Materials and methods: Three hundred high-risk patients underwent HD-CTCA and ICA. Independent experts evaluated the images for the presence of significant CAD, defined primarily as the presence of moderate (≥50%) stenosis and secondarily as the presence of severe (≥70%) stenosis in at least one coronary segment, in a blinded fashion. HD-CTCA was compared to ICA as the reference standard. Results: No patients were excluded. Two hundred and six patients (69%) had moderate and 178 (59%) had severe stenosis in at least one vessel at ICA. The sensitivity, specificity, positive predictive value, and negative predictive value were 97.1%, 97.9%, 99% and 93.9% for moderate stenosis, and 98.9%, 93.4%, 95.7% and 98.3%, for severe stenosis, on a per-patient basis. Conclusion: The combination of HD-CTCA and experienced readers applied to a high-risk population, results in high diagnostic accuracy comparable to ICA. Modern generation CT systems in experienced hands might be considered for an expanded role. - Highlights: • Diagnostic accuracy of High-Definition CT Angiography (HD-CTCA) has been assessed. • Invasive Coronary angiography (ICA) is the reference standard. • Diagnostic accuracy of HD-CTCA is comparable to ICA. • Diagnostic accuracy is not affected by coronary calcium or stents. • HD-CTCA provides a non-invasive alternative in high-risk patients.

  16. WE-FG-207B-10: Dual-Energy CT Monochromatic Image Consistency Across Vendors and Platforms

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsen, M; Wood, C; Cody, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: Although dual-energy CT provides improved sensitivity of HU for certain tissue types at lower simulated energy levels, if these values vary by scanner type they may impact clinical patient management decisions. Each manufacturer has selected a specific dual-energy CT approach (or in one case, three different approaches); understanding HU variability among low monochromatic images may be required when more than one dual-energy CT scanner type is available for use. Methods: A large elliptical dualenergy quality control phantom (Gammex Inc.; Middleton, WI) containing several standard tissue type materials was scanned at least three times on each of the following systems: GE HD750, prototype GE Revolution CT with GSI, Siemens Flash, Siemens Edge, Siemens AS 128, and Philips IQon. Images were generated at 50, 70, and 140 keV. Soft tissue and Iodine HU were measured on a single central 5mm-thick image; NIST constants were used to calculate the ideal HU for each material. Scan acquisitions were approximately dose-matched (∼25mGy CTDIvol) and image parameters were held as consistent as possible (thickness, kernel, no noise reduction). Results: Measured soft tissue (29 HU at 120 kVp) varied from 28 HU to 44 HU at 50 keV (excluding one outlier), from 21 HU to 31 HU at 70 keV, and from 19 HU to 32 HU at 140 keV. Measured iodine (5mg/ml, 106 HU at 120 kVp) varied from 246 HU to 280 HU at 50 keV, from 123 HU to 129 HU at 70 keV, and from 22 HU to 32 HU at 140 keV. Conclusion: Measured HU in standard rods across 3 dual-energy CT manufacturers and 6 scanner models varied directly with monochromatic level, with the most variability was observed at 50 keV and least variability at 70keV. Future work will include additional scanner platforms and how measurement variability impacts radiologists. This research has been supported by funds from Dr. William Murphy, Jr., the John S. Dunn, Sr. Distinguished Chair in Diagnostic Imaging at MD Anderson Cancer Center.

  17. Dual energy CT. A new perspective in the diagnosis of gout; Dual Energy CT. Eine neue Perspektive in der Gicht-Diagnostik

    Energy Technology Data Exchange (ETDEWEB)

    Artmann, Andreas; Ratzenboeck, M.; Noszian, I. [Radiologie II, Klinikum Wels Grieskirchen (Austria); Inst. fuer Digitale Schnittbildtechnik, Wels (Austria); Trieb, K. [Orthopaedie, Klinikum Wels Grieskirchen (Austria)

    2010-03-15

    Purpose: To describe the first experience with dual energy CT (DECT) for the diagnosis of gout and to evaluate its potential for the clinical routine. Materials and Methods: DECT examinations acquired with a dual source CT of 71 regions from 41 patients were evaluated with respect to image quality, amount of urate deposits and their location. The amount of urate deposits was described using a 4-stage scale: none (1), minimal punctual (up to 2 mm) (2), at least moderate (bigger than 2 mm) (3), soft tissue or osseus tophi (4). The DECT results were compared with the findings of the diagnostic tools currently in use. Results: The DECTs of peripheral regions showed excellent image quality, while the image quality was poor in the regions of the trunk. Patients (n) and regions (r) with a score of 3 (n = 23, r = 44), 4 (n=5, r=8) and 1 (n=2, r=2) showed a highly significant correlation (p<0.01) with the currently available diagnostic tools. In patients or regions with a score of 2 (n = 7, r = 11), the urate deposits were asymptomatic, the serum urate levels were partly elevated (43%) and partly normal (57%). The symptoms were ultimately able to be associated with a differential diagnosis. The urate deposits were found in tendons (57), articular synovia (25), cartilage (17), soft tissue tophi (8), osseus tophi (5), cruciate ligaments (7) and menisci (7). Conclusion: DECT allows specific and quantitative visualization of urate deposits in peripheral regions. Taking into account the amount of urate deposits shown in DECT, the diagnosis of gout can be stated reliably. Based on our experience and results, DECT greatly benefits the routine diagnosis of gout in peripheral regions. (orig.)

  18. Recent developments of dual-energy CT in oncology

    Energy Technology Data Exchange (ETDEWEB)

    Simons, David; Schlemmer, Heinz-Peter [Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg (Germany); Kachelriess, Marc [Department of Medical Physics in Radiology, Division of X-ray Imaging and CT, German Cancer Research Center (DKFZ), Heidelberg (Germany)

    2014-04-15

    Dual-energy computed tomography (DECT) can amply contribute to support oncological imaging: the DECT technique offers promising clinical applications in oncological imaging for tumour detection and characterisation while concurrently reducing the radiation dose. Fast image acquisition at two different X-ray energies enables the determination of tissue- or material-specific features, the calculation of virtual unenhanced images and the quantification of contrast medium uptake; thus, tissue can be characterised and subsequently monitored for any changes during treatment. DECT is already widely used, but its potential in the context of oncological imaging has not been fully exploited yet. The technology is the subject of ongoing innovation and increasingly with respect to its clinical potential, particularly in oncology. This review highlights recent state-of-the-art DECT techniques with a strong emphasis on ongoing DECT developments relevant to oncologic imaging, and then focuses on clinical DECT applications, especially its prospective uses in areas of oncological imaging. circle Dual-energy CT (DECT) offers fast, robust, quantitative and functional whole-body imaging. (orig.)

  19. WE-FG-207B-09: Experimental Assessment of Noise and Spatial Resolution in Virtual Non-Contrast Dual-Energy CT Images Across Multiple Patient Sizes and CT Systems

    International Nuclear Information System (INIS)

    Montoya, J; Ferrero, A; Yu, L; Leng, S; McCollough, C

    2016-01-01

    Purpose: To investigate the noise and spatial resolution properties of virtual non-contrast (VNC) dual-energy CT images compared to true non-contrast (TNC) images across multiple patient sizes and CT systems. Methods: Torso-shaped water phantoms with lateral widths of 25, 30, 35, 40 and 45 cm and a high resolution bar pattern phantom (Catphan CTP528) were scanned using 2nd and 3rd generation dual-source CT systems (Scanner A: Somatom Definition Flash, Scanner B: Somatom Force, Siemens Healthcare) in dual-energy scan mode with the same radiation dose for a given phantom size. Tube potentials of 80/Sn140 and 100/Sn140 on Scanner A and 80/Sn150, 90/Sn150 and 100/Sn150 on Scanner B were evaluated to examine the impact of spectral separation. Images were reconstructed using a medium sharp quantitative kernel (Qr40), 1.0-mm thickness, 1.0-mm interval and 20 cm field of view. Mixed images served as TNC images. VNC images were created using commercial software (Virtual Unenhanced, Syngo VIA Version VA30, Siemens Healthcare). The noise power spectrum (NPS), area under the NPS, peak frequency of the NPS and image noise were measured for every phantom size and tube potential combination in TNC and VNC images. Results were compared within and between CT systems. Results: Minimal shift in NPS peak frequencies was observed in VNC images compared to TNC for NPS having pronounced peaks. Image noise and area under the NPS were higher in VNC images compared to TNC images across all tube potentials and for scanner A compared to scanner B. Limiting spatial resolution was deemed to be identical between VNC and TNC images. Conclusion: Quantitative assessment of image quality in VNC images demonstrated higher noise but equivalent spatial resolution compared to TNC images. Decreased noise was observed in the 3rd generation dual-source CT system for tube potential pairs having greater spectral separation. Dr. McCollough receives research support from Siemens Healthcare

  20. WE-FG-207B-09: Experimental Assessment of Noise and Spatial Resolution in Virtual Non-Contrast Dual-Energy CT Images Across Multiple Patient Sizes and CT Systems

    Energy Technology Data Exchange (ETDEWEB)

    Montoya, J; Ferrero, A; Yu, L; Leng, S; McCollough, C [Mayo Clinic, Rochester, MN (United States)

    2016-06-15

    Purpose: To investigate the noise and spatial resolution properties of virtual non-contrast (VNC) dual-energy CT images compared to true non-contrast (TNC) images across multiple patient sizes and CT systems. Methods: Torso-shaped water phantoms with lateral widths of 25, 30, 35, 40 and 45 cm and a high resolution bar pattern phantom (Catphan CTP528) were scanned using 2nd and 3rd generation dual-source CT systems (Scanner A: Somatom Definition Flash, Scanner B: Somatom Force, Siemens Healthcare) in dual-energy scan mode with the same radiation dose for a given phantom size. Tube potentials of 80/Sn140 and 100/Sn140 on Scanner A and 80/Sn150, 90/Sn150 and 100/Sn150 on Scanner B were evaluated to examine the impact of spectral separation. Images were reconstructed using a medium sharp quantitative kernel (Qr40), 1.0-mm thickness, 1.0-mm interval and 20 cm field of view. Mixed images served as TNC images. VNC images were created using commercial software (Virtual Unenhanced, Syngo VIA Version VA30, Siemens Healthcare). The noise power spectrum (NPS), area under the NPS, peak frequency of the NPS and image noise were measured for every phantom size and tube potential combination in TNC and VNC images. Results were compared within and between CT systems. Results: Minimal shift in NPS peak frequencies was observed in VNC images compared to TNC for NPS having pronounced peaks. Image noise and area under the NPS were higher in VNC images compared to TNC images across all tube potentials and for scanner A compared to scanner B. Limiting spatial resolution was deemed to be identical between VNC and TNC images. Conclusion: Quantitative assessment of image quality in VNC images demonstrated higher noise but equivalent spatial resolution compared to TNC images. Decreased noise was observed in the 3rd generation dual-source CT system for tube potential pairs having greater spectral separation. Dr. McCollough receives research support from Siemens Healthcare.

  1. Spatial Distribution of Iron Within the Normal Human Liver Using Dual-Source Dual-Energy CT Imaging.

    Science.gov (United States)

    Abadia, Andres F; Grant, Katharine L; Carey, Kathleen E; Bolch, Wesley E; Morin, Richard L

    2017-11-01

    Explore the potential of dual-source dual-energy (DSDE) computed tomography (CT) to retrospectively analyze the uniformity of iron distribution and establish iron concentration ranges and distribution patterns found in healthy livers. Ten mixtures consisting of an iron nitrate solution and deionized water were prepared in test tubes and scanned using a DSDE 128-slice CT system. Iron images were derived from a 3-material decomposition algorithm (optimized for the quantification of iron). A conversion factor (mg Fe/mL per Hounsfield unit) was calculated from this phantom study as the quotient of known tube concentrations and their corresponding CT values. Retrospective analysis was performed of patients who had undergone DSDE imaging for renal stones. Thirty-seven patients with normal liver function were randomly selected (mean age, 52.5 years). The examinations were processed for iron concentration. Multiple regions of interest were analyzed, and iron concentration (mg Fe/mL) and distribution was reported. The mean conversion factor obtained from the phantom study was 0.15 mg Fe/mL per Hounsfield unit. Whole-liver mean iron concentrations yielded a range of 0.0 to 2.91 mg Fe/mL, with 94.6% (35/37) of the patients exhibiting mean concentrations below 1.0 mg Fe/mL. The most important finding was that iron concentration was not uniform and patients exhibited regionally high concentrations (36/37). These regions of higher concentration were observed to be dominant in the middle-to-upper part of the liver (75%), medially (72.2%), and anteriorly (83.3%). Dual-source dual-energy CT can be used to assess the uniformity of iron distribution in healthy subjects. Applying similar techniques to unhealthy livers, future research may focus on the impact of hepatic iron content and distribution for noninvasive assessment in diseased subjects.

  2. Neutron-induced electronic failures around a high-energy linear accelerator

    International Nuclear Information System (INIS)

    Kry, Stephen F.; Johnson, Jennifer L.; White, R. Allen; Howell, Rebecca M.; Kudchadker, Rajat J.; Gillin, Michael T.

    2011-01-01

    Purpose: After a new in-vault CT-on-rails system repeatedly malfunctioned following use of a high-energy radiotherapy beam, we investigated the presence and impact of neutron radiation on this electronic system, as well as neutron shielding options. Methods: We first determined the CT scanner's failure rate as a function of the number of 18 MV monitor units (MUs) delivered. We then re-examined the failure rate with both 2.7-cm-thick and 7.6-cm-thick borated polyethylene (BPE) covering the linac head for neutron shielding. To further examine shielding options, as well as to explore which neutrons were relevant to the scanner failure, Monte Carlo simulations were used to calculate the neutron fluence and spectrum in the bore of the CT scanner. Simulations included BPE covering the CT scanner itself as well as covering the linac head. Results: We found that the CT scanner had a 57% chance of failure after the delivery of 200 MUs. While the addition of neutron shielding to the accelerator head reduced this risk of failure, the benefit was minimal and even 7.6 cm of BPE was still associated with a 29% chance of failure after the delivery of 200 MU. This shielding benefit was achieved regardless of whether the linac head or CT scanner was shielded. Additionally, it was determined that fast neutrons were primarily responsible for the electronic failures. Conclusions: As illustrated by the CT-on-rails system in the current study, physicists should be aware that electronic systems may be highly sensitive to neutron radiation. Medical physicists should therefore monitor electronic systems that have not been evaluated for potential neutron sensitivity. This is particularly relevant as electronics are increasingly common in the therapy vault and newer electronic systems may exhibit increased sensitivity.

  3. Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels.

    Science.gov (United States)

    Guggenberger, R; Winklhofer, S; Osterhoff, G; Wanner, G A; Fortunati, M; Andreisek, G; Alkadhi, H; Stolzmann, P

    2012-11-01

    To evaluate optimal monoenergetic dual-energy computed tomography (DECT) settings for artefact reduction of posterior spinal fusion implants of various vendors and spine levels. Posterior spinal fusion implants of five vendors for cervical, thoracic and lumbar spine were examined ex vivo with single-energy (SE) CT (120 kVp) and DECT (140/100 kVp). Extrapolated monoenergetic DECT images at 64, 69, 88, 105 keV and individually adjusted monoenergy for optimised image quality (OPTkeV) were generated. Two independent radiologists assessed quantitative and qualitative image parameters for each device and spine level. Inter-reader agreements of quantitative and qualitative parameters were high (ICC = 0.81-1.00, κ = 0.54-0.77). HU values of spinal fusion implants were significantly different among vendors (P metallic artefacts from implants than SECT. Use of individual keV values for vendor and spine level is recommended. • Artefacts pose problems for CT following posterior spinal fusion implants. • CT images are interpreted better with monoenergetic extrapolation using dual-energy (DE) CT. • DECT extrapolation improves image quality and reduces metallic artefacts over SECT. • There were considerable differences in monoenergy values among vendors and spine levels. • Use of individualised monoenergy values is indicated for different metallic hardware devices.

  4. Differential diagnosis between benign and malignant pleural effusion with dual-energy spectral CT.

    Science.gov (United States)

    Zhang, Xirong; Duan, Haifeng; Yu, Yong; Ma, Chunling; Ren, Zhanli; Lei, Yuxin; He, Taiping; Zhang, Ming

    2018-01-01

    of 100% and specificity of 71.4% with area-under-curve of 0.933 for differentiating benign from malignant effusion. The CT value measurement at both high and low energy levels and the effective atomic number obtained in a single spectral CT scan can assist the differential diagnosis of benign from malignant pleural effusion.Combining them with patient age and disease history can further improve diagnostic performance. Clinical findings and Spectral CT imaging can provide significant evidences about the nature of pleural effusion.

  5. Diagnostic accuracy of virtual non-contrast enhanced dual-energy CT for diagnosis of adrenal adenoma: A systematic review and meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, Michael J.; McInnes, Matthew D.F.; Schieda, Nicola [University of Ottawa Department of Radiology, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON (United States); El-Khodary, Mohamed [McMaster University Department of Radiology, Hamilton, ON (Canada); McGrath, Trevor A. [University of Ottawa, Faculty of Medicine, Ottawa, Ontario (Canada)

    2017-10-15

    To compare the diagnostic accuracy of dual-energy (DE) virtual non-contrast computed tomography (vNCT) to non-contrast CT (NCT) for the diagnosis of adrenal adenomas. Search of multiple databases and grey literature was performed. Two reviewers independently applied inclusion criteria and extracted data. Risk of bias was assessed using QUADAS-2. Summary estimates of diagnostic accuracy were generated and sources of heterogeneity were assessed. Five studies (170 patients; 192 adrenal masses) were included for diagnostic accuracy assessment; all used dual-source dual-energy CT. Pooled sensitivity for adrenal adenoma on vNCT was 54% (95% CI: 47-62%). Pooled sensitivity for NCT was 57% (95% CI: 45-69%). Pooling of specificity was not performed since no false positives were reported. There was a trend for overestimation of HU density on vNCT as compared to NCT which appeared related to contrast timing. Potential sources of bias were seen regarding the index test and reference standard for the included studies. Potential sources of heterogeneity between studies were seen in adenoma prevalence and intravenous contrast timing. vNCT images generated from dual-energy CT demonstrated comparable sensitivity to NCT for the diagnosis of adenomas; however the included studies are heterogeneous and at high risk for some types of bias. (orig.)

  6. Initial use of fast switched dual energy CT for coronary artery disease

    Science.gov (United States)

    Pavlicek, William; Panse, Prasad; Hara, Amy; Boltz, Thomas; Paden, Robert; Yamak, Didem; Licato, Paul; Chandra, Naveen; Okerlund, Darin; Dutta, Sandeep; Bhotika, Rahul; Langan, David

    2010-04-01

    Coronary CT Angiography (CTA) is limited in patients with calcified plaque and stents. CTA is unable to confidently differentiate fibrous from lipid plaque. Fast switched dual energy CTA offers certain advantages. Dual energy CTA removes calcium thereby improving visualization of the lumen and potentially providing a more accurate measure of stenosis. Dual energy CTA directly measures calcium burden (calcium hydroxyapatite) thereby eliminating a separate non-contrast series for Agatston Scoring. Using material basis pairs, the differentiation of fibrous and lipid plaques is also possible. Patency of a previously stented coronary artery is difficult to visualize with CTA due to resolution constraints and localized beam hardening artifacts. Monochromatic 70 keV or Iodine images coupled with Virtual Non-stent images lessen beam hardening artifact and blooming. Virtual removal of stainless steel stents improves assessment of in-stent re-stenosis. A beating heart phantom with 'cholesterol' and 'fibrous' phantom coronary plaques were imaged with dual energy CTA. Statistical classification methods (SVM, kNN, and LDA) distinguished 'cholesterol' from 'fibrous' phantom plaque tissue. Applying this classification method to 16 human soft plaques, a lipid 'burden' may be useful for characterizing risk of coronary disease. We also found that dual energy CTA is more sensitive to iodine contrast than conventional CTA which could improve the differentiation of myocardial infarct and ischemia on delayed acquisitions. These phantom and patient acquisitions show advantages with using fast switched dual energy CTA for coronary imaging and potentially extends the use of CT for addressing problem areas of non-invasive evaluation of coronary artery disease.

  7. High resolution CT in the investigation of bone destruction in the outer ear

    International Nuclear Information System (INIS)

    Koester, O.; Straehler-Pohl, H.J.; Bonn Univ.

    1986-01-01

    Eleven patients with known malignant tumours of the outer ear and three patients with otitis externa maligna were examined by high resolution CT. CT provided accurate information concerning soft tissue infiltration into the parotid or subtemporal tissues, and of the bony destruction in the mastoid, meatus and tympanic cavity. Absolute differentiation between a malignant tumour and otitis cisterna maligna is not possible, not even by high resolution CT. (orig.) [de

  8. Material elemental decomposition in dual and multi-energy CT via a sparsity-dictionary approach for proton stopping power ratio calculation.

    Science.gov (United States)

    Shen, Chenyang; Li, Bin; Chen, Liyuan; Yang, Ming; Lou, Yifei; Jia, Xun

    2018-04-01

    Accurate calculation of proton stopping power ratio (SPR) relative to water is crucial to proton therapy treatment planning, since SPR affects prediction of beam range. Current standard practice derives SPR using a single CT scan. Recent studies showed that dual-energy CT (DECT) offers advantages to accurately determine SPR. One method to further improve accuracy is to incorporate prior knowledge on human tissue composition through a dictionary approach. In addition, it is also suggested that using CT images with multiple (more than two) energy channels, i.e., multi-energy CT (MECT), can further improve accuracy. In this paper, we proposed a sparse dictionary-based method to convert CT numbers of DECT or MECT to elemental composition (EC) and relative electron density (rED) for SPR computation. A dictionary was constructed to include materials generated based on human tissues of known compositions. For a voxel with CT numbers of different energy channels, its EC and rED are determined subject to a constraint that the resulting EC is a linear non-negative combination of only a few tissues in the dictionary. We formulated this as a non-convex optimization problem. A novel algorithm was designed to solve the problem. The proposed method has a unified structure to handle both DECT and MECT with different number of channels. We tested our method in both simulation and experimental studies. Average errors of SPR in experimental studies were 0.70% in DECT, 0.53% in MECT with three energy channels, and 0.45% in MECT with four channels. We also studied the impact of parameter values and established appropriate parameter values for our method. The proposed method can accurately calculate SPR using DECT and MECT. The results suggest that using more energy channels may improve the SPR estimation accuracy. © 2018 American Association of Physicists in Medicine.

  9. Effect of a novel intracycle motion correction algorithm on dual-energy spectral coronary CT angiography: A study with pulsating coronary artery phantom at high heart rates

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yan; Zhao, Yuan; Pan, Cun Xue; Azati, Gulina; Wang, Yan Wei; Liu, Wen Ya [Imaging Center, The First Affiliated Hospital of Xinjiang Medical University, Xinjiang (China); Guo, Ning [CT Imaging Research Center, GE Healthcare, Beijing (China)

    2017-11-15

    Using a pulsating coronary artery phantom at high heart rate settings, we investigated the efficacy of a motion correction algorithm (MCA) to improve the image quality in dual-energy spectral coronary CT angiography (CCTA). Coronary flow phantoms were scanned at heart rates of 60–100 beats/min at 10-beats/min increments, using dual-energy spectral CT mode. Virtual monochromatic images were reconstructed from 50 to 90 keV at 10-keV increments. Two blinded observers assessed image quality using a 4-point Likert Scale (1 = non-diagnostic, 4 = excellent) and the fraction of interpretable segments using MCA versus conventional algorithm (CA). Comparison of variables was performed with the Wilcoxon rank sum test and McNemar test. At heart rates of 70, 80, 90, and 100 beats/min, images with MCA were rated as higher image scores compared to those with CA on monochromatic levels of 50, 60, and 70 keV (each p < 0.05). Meanwhile, at a heart rate of 90 beats/min, image interpretability was improved by MCA at a monochromatic level of 60 keV (p < 0.05) and 70 keV (p < 0.05). At a heart rate of 100 beats/min, image interpretability was improved by MCA at monochromatic levels of 50 keV (from 69.4% to 86.1%, p < 0.05), 60 keV (from 55.6% to 83.3%, p < 0.05) and 70 keV (from 33.3% to 69.3%, p < 0.05). Low-keV monochromatic images combined with MCA improves image quality and image interpretability in CCTAs at high heart rates.

  10. Added value of lung perfused blood volume images using dual-energy CT for assessment of acute pulmonary embolism

    International Nuclear Information System (INIS)

    Okada, Munemasa; Kunihiro, Yoshie; Nakashima, Yoshiteru; Nomura, Takafumi; Kudomi, Shohei; Yonezawa, Teppei; Suga, Kazuyoshi; Matsunaga, Naofumi

    2015-01-01

    Purpose: To investigate the added value of lung perfused blood volume (LPBV) using dual-energy CT for the evaluation of intrapulmonary clot (IPC) in patients suspected of having acute pulmonary embolism (PE). Materials and methods: Institutional review board approval was obtained for this retrospective study. Eighty-three patients suspected of having PE who underwent CT pulmonary angiography (CTPA) using a dual-energy technique were enrolled in this study. Two radiologists who were blinded retrospectively and independently reviewed CTPA images alone and the combined images with color-coded LPBV over a 4-week interval, and two separate sessions were performed with a one-month interval. Inter- and intraobserver variability and diagnostic accuracy were evaluated for each reviewer with receiver operating characteristic (ROC) curve analysis. Results: Values for inter- and intraobserver agreement, respectively, were better for CTPA combined with LPBV (ICC = 0.847 and 0.937) than CTPA alone (ICC = 0.748 and 0.861). For both readers, diagnostic accuracy (area under the ROC curve [A z ]) were also superior, when CTPA alone (A z = 0.888 [reader 1] and 0.912 [reader 2]) was compared with that after the combination with LPBV images (A z = 0.966 [reader 1] and 0.959 [reader 2]) (p < 0.001). However, A z values of both images might not have significant difference in statistics, because A z value of CTPA alone was high and 95% confidence intervals overlapped in both images. Conclusion: Addition of dual-energy perfusion CT to CTPA improves detection of peripheral IPCs with better interobserver agreement

  11. Pulmonary imaging using dual-energy CT, a role of the assessment of iodine and air distribution

    Energy Technology Data Exchange (ETDEWEB)

    Ferda, Jiri, E-mail: e-mail@fnplzen.cz [Radiodiagnostic Clinic, Charles University Teaching Hospital Plzen, Alej Svobody 80, 30640 Plzen (Czech Republic); Ferdova, Eva; Mirka, Hynek; Baxa, Jan; Bednarova, Alena [Radiodiagnostic Clinic, Charles University Teaching Hospital Plzen, Alej Svobody 80, 30640 Plzen (Czech Republic); Flohr, Thomas; Schmidt, Bernhard [Siemens Healthcare, Computed Tomography, 91301 Siemensstr. 1, Forchheim (Germany); Matejovic, Martin [1st Internal Department, Charles University Teaching Hospital Plzen, Alej Svobody 80, 30640 Plzen (Czech Republic); Kreuzberg, Boris [Radiodiagnostic Clinic, Charles University Teaching Hospital Plzen, Alej Svobody 80, 30640 Plzen (Czech Republic)

    2011-02-15

    Aim: The aim of the study is to present the feasibility of using dual-energy CT and the evaluation of iodine and air distribution in differentiation of pathological conditions. Material and method: We used the data of 50 CT examinations performed due to suspected pulmonary embolism with any pathological finding except consolidation of the parenchyma. The patients underwent CT angiography of the pulmonary arteries on a dual-source CT (DSCT), with the two tubes independently operated at 140 and 80 kV. By exploiting the dual-energy information, iodine distribution maps were obtained in addition to the conventional CT images which served as a marker of pulmonary perfusion. Minimum intensity projections (MinIP) were used as a marker of air content. Results: By comparing the iodine distribution maps and MinIP images, it was possible to differentiate between the following templates of lung parenchyma: A - normal iodine and air distribution; B - iodine content deficit with minimal or with no redistribution of air; C - reduced iodine content and increased content of air; D - deficit of iodine content and increased content of air; E - increased iodine content and normal content of air; F - increased iodine content and reduced content of air; G - reduced perfusion and reduced content of air. The type A (five cases) was typical for the pulmonary embolism with preserved normal conditions of perfusion and ventilation. Type B (18 cases) occurred in pulmonary embolism; type C was found in case of inflammation of small respiratory airways (five cases); emphysema was typical for type D (nine cases); increased perfusion was observed in the parenchyma preserved from emphysema or preserved from embolism in cases of emphysema or pulmonary embolism; type F occurred in pulmonary interstitial edema (four cases) both with pulmonary infection; finally type G was found in interstitial lung diseases (five cases). Conclusion: Imaging of the pulmonary circulation by means of dual-energy CT opens

  12. Dual-energy attenuation coefficient decomposition with differential filtration and application to a microCT scanner

    International Nuclear Information System (INIS)

    Taschereau, R; Silverman, R W; Chatziioannou, A F

    2010-01-01

    Dual-energy x-ray computed tomography (DECT) has the capability to decompose attenuation coefficients using two basis functions and has proved its potential in reducing beam-hardening artifacts from reconstructed images. The method typically involves two successive scans with different x-ray tube voltage settings. This work proposes an approach to dual-energy imaging through x-ray beam filtration that requires only one scan and a single tube voltage setting. It has been implemented in a preclinical microCT tomograph with minor modifications. Retrofitting of the microCT scanner involved the addition of an automated filter wheel and modifications to the acquisition and reconstruction software. Results show that beam-hardening artifacts are reduced to noise level. Acquisition of a μ-Compton image is well suited for attenuation-correction of PET images while dynamic energy selection (4D viewing) offers flexibility in image viewing by adjusting contrast and noise levels to suit the task at hand. All dual-energy and single energy reference scans were acquired at the same soft tissue dose level of 50 mGy.

  13. Dual-energy attenuation coefficient decomposition with differential filtration and application to a microCT scanner

    Energy Technology Data Exchange (ETDEWEB)

    Taschereau, R; Silverman, R W; Chatziioannou, A F [Crump Institute for Molecular Imaging, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States)], E-mail: rtaschereau@mednet.ucla.edu

    2010-02-21

    Dual-energy x-ray computed tomography (DECT) has the capability to decompose attenuation coefficients using two basis functions and has proved its potential in reducing beam-hardening artifacts from reconstructed images. The method typically involves two successive scans with different x-ray tube voltage settings. This work proposes an approach to dual-energy imaging through x-ray beam filtration that requires only one scan and a single tube voltage setting. It has been implemented in a preclinical microCT tomograph with minor modifications. Retrofitting of the microCT scanner involved the addition of an automated filter wheel and modifications to the acquisition and reconstruction software. Results show that beam-hardening artifacts are reduced to noise level. Acquisition of a {mu}-Compton image is well suited for attenuation-correction of PET images while dynamic energy selection (4D viewing) offers flexibility in image viewing by adjusting contrast and noise levels to suit the task at hand. All dual-energy and single energy reference scans were acquired at the same soft tissue dose level of 50 mGy.

  14. Optimal Monochromatic Energy Levels in Spectral CT Pulmonary Angiography for the Evaluation of Pulmonary Embolism

    Science.gov (United States)

    Wu, Huawei; Zhang, Qing; Hua, Jia; Hua, Xiaolan; Xu, Jianrong

    2013-01-01

    Background The aim of this study was to determine the optimal monochromatic spectral CT pulmonary angiography (sCTPA) levels to obtain the highest image quality and diagnostic confidence for pulmonary embolism detection. Methods The Institutional Review Board of the Shanghai Jiao Tong University School of Medicine approved this study, and written informed consent was obtained from all participating patients. Seventy-two patients with pulmonary embolism were scanned with spectral CT mode in the arterial phase. One hundred and one sets of virtual monochromatic spectral (VMS) images were generated ranging from 40 keV to 140 keV. Image noise, clot diameter and clot to artery contrast-to-noise ratio (CNR) from seven sets of VMS images at selected monochromatic levels in sCTPA were measured and compared. Subjective image quality and diagnostic confidence for these images were also assessed and compared. Data were analyzed by paired t test and Wilcoxon rank sum test. Results The lowest noise and the highest image quality score for the VMS images were obtained at 65 keV. The VMS images at 65 keV also had the second highest CNR value behind that of 50 keV VMS images. There was no difference in the mean noise and CNR between the 65 keV and 70 keV VMS images. The apparent clot diameter correlated with the keV levels. Conclusions The optimal energy level for detecting pulmonary embolism using dual-energy spectral CT pulmonary angiography was 65–70 keV. Virtual monochromatic spectral images at approximately 65–70 keV yielded the lowest image noise, high CNR and highest diagnostic confidence for the detection of pulmonary embolism. PMID:23667583

  15. Integration of PET-CT and cone-beam CT for image-guided radiotherapy with high image quality and registration accuracy

    Science.gov (United States)

    Wu, T.-H.; Liang, C.-H.; Wu, J.-K.; Lien, C.-Y.; Yang, B.-H.; Huang, Y.-H.; Lee, J. J. S.

    2009-07-01

    Hybrid positron emission tomography-computed tomography (PET-CT) system enhances better differentiation of tissue uptake of 18F-fluorodeoxyglucose (18F-FDG) and provides much more diagnostic value in the non-small-cell lung cancer and nasopharyngeal carcinoma (NPC). In PET-CT, high quality CT images not only offer diagnostic value on anatomic delineation of the tissues but also shorten the acquisition time for attenuation correction (AC) compared with PET-alone imaging. The linear accelerators equipped with the X-ray cone-beam computed tomography (CBCT) imaging system for image-guided radiotherapy (IGRT) provides excellent verification on position setup error. The purposes of our study were to optimize the CT acquisition protocols of PET-CT and to integrate the PET-CT and CBCT for IGRT. The CT imaging parameters were modified in PET-CT for increasing the image quality in order to enhance the diagnostic value on tumour delineation. Reproducibility and registration accuracy via bone co-registration algorithm between the PET-CT and CBCT were evaluated by using a head phantom to simulate a head and neck treatment condition. Dose measurement in computed tomography dose index (CTDI) was also estimated. Optimization of the CT acquisition protocols of PET-CT was feasible in this study. Co-registration accuracy between CBCT and PET-CT on axial and helical modes was in the range of 1.06 to 2.08 and 0.99 to 2.05 mm, respectively. In our result, it revealed that the accuracy of the co-registration with CBCT on helical mode was more accurate than that on axial mode. Radiation doses in CTDI were 4.76 to 18.5 mGy and 4.83 to 18.79 mGy on axial and helical modes, respectively. Registration between PET-CT and CBCT is a state-of-the-art registration technology which could provide much information on diagnosis and accurate tumour contouring on radiotherapy while implementing radiotherapy procedures. This novelty technology of PET-CT and cone-beam CT integration for IGRT may have a

  16. Integration of PET-CT and cone-beam CT for image-guided radiotherapy with high image quality and registration accuracy

    International Nuclear Information System (INIS)

    Wu, T-H; Liang, C-H; Wu, J-K; Lien, C-Y; Yang, B-H; Lee, J J S; Huang, Y-H

    2009-01-01

    Hybrid positron emission tomography-computed tomography (PET-CT) system enhances better differentiation of tissue uptake of 18 F-fluorodeoxyglucose ( 18 F-FDG) and provides much more diagnostic value in the non-small-cell lung cancer and nasopharyngeal carcinoma (NPC). In PET-CT, high quality CT images not only offer diagnostic value on anatomic delineation of the tissues but also shorten the acquisition time for attenuation correction (AC) compared with PET-alone imaging. The linear accelerators equipped with the X-ray cone-beam computed tomography (CBCT) imaging system for image-guided radiotherapy (IGRT) provides excellent verification on position setup error. The purposes of our study were to optimize the CT acquisition protocols of PET-CT and to integrate the PET-CT and CBCT for IGRT. The CT imaging parameters were modified in PET-CT for increasing the image quality in order to enhance the diagnostic value on tumour delineation. Reproducibility and registration accuracy via bone co-registration algorithm between the PET-CT and CBCT were evaluated by using a head phantom to simulate a head and neck treatment condition. Dose measurement in computed tomography dose index (CTDI) was also estimated. Optimization of the CT acquisition protocols of PET-CT was feasible in this study. Co-registration accuracy between CBCT and PET-CT on axial and helical modes was in the range of 1.06 to 2.08 and 0.99 to 2.05 mm, respectively. In our result, it revealed that the accuracy of the co-registration with CBCT on helical mode was more accurate than that on axial mode. Radiation doses in CTDI were 4.76 to 18.5 mGy and 4.83 to 18.79 mGy on axial and helical modes, respectively. Registration between PET-CT and CBCT is a state-of-the-art registration technology which could provide much information on diagnosis and accurate tumour contouring on radiotherapy while implementing radiotherapy procedures. This novelty technology of PET-CT and cone-beam CT integration for IGRT may have a

  17. X-ray CT high-density artefact suppression in the presence of bones

    Energy Technology Data Exchange (ETDEWEB)

    Wei Jikun [School of Health Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 (United States); Chen Laigao [BioImaging Center of Emphasis, Pfizer Global Research and Development, 2800 Plymouth RD, Ann Arbor, MI 48105 (United States); Sandison, George A [School of Health Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 (United States); Liang Yun [Department of Radiology, Indiana University Medical School, Indianapolis, IN 46202 (United States); Xu, Lisa X [School of Mechanical Engineering, 585 Purdue Mall, West Lafayette, IN 47907-2040 (United States)

    2004-12-21

    This paper presents a novel method of reducing x-ray CT high-density artefacts generated by metal objects when abundant bone structures are present in the region of interest. This method has an advantage over previously proposed methods since it heavily suppresses the metal artefacts without introducing extra bone artefacts. The method of suppression requires that bone pixels are isolated and segmented by thresholding. Then artificial CT numbers are assigned to the bone pixels so that their projection profiles are smooth and thus can be properly simulated by a polynomial interpolation. The projection profile of the metal object is then removed to fully suppress the artefacts. The resulting processed profile is fed to a reconstruction routine and the previously preserved bone pixels added back. The new method utilizes two important features of the CT image with metal artefacts: (a) metal and bone pixels are not severely affected by the high-density artefacts and (b) the high-density artefacts can be located in specific projection channels in the profile domain, although they are spread out in the image domain. This suppression method solves the problem of CT image artefacts arising from metal objects in the body. It has the potential to greatly improve diagnostic CT imaging in the presence of these objects and treatment planning that utilizes CT for patients with metal applicators (e.g., brachytherapy for cervix cancer and prostate cryotherapy)

  18. X-ray CT high-density artefact suppression in the presence of bones

    International Nuclear Information System (INIS)

    Wei Jikun; Chen Laigao; Sandison, George A; Liang Yun; Xu, Lisa X

    2004-01-01

    This paper presents a novel method of reducing x-ray CT high-density artefacts generated by metal objects when abundant bone structures are present in the region of interest. This method has an advantage over previously proposed methods since it heavily suppresses the metal artefacts without introducing extra bone artefacts. The method of suppression requires that bone pixels are isolated and segmented by thresholding. Then artificial CT numbers are assigned to the bone pixels so that their projection profiles are smooth and thus can be properly simulated by a polynomial interpolation. The projection profile of the metal object is then removed to fully suppress the artefacts. The resulting processed profile is fed to a reconstruction routine and the previously preserved bone pixels added back. The new method utilizes two important features of the CT image with metal artefacts: (a) metal and bone pixels are not severely affected by the high-density artefacts and (b) the high-density artefacts can be located in specific projection channels in the profile domain, although they are spread out in the image domain. This suppression method solves the problem of CT image artefacts arising from metal objects in the body. It has the potential to greatly improve diagnostic CT imaging in the presence of these objects and treatment planning that utilizes CT for patients with metal applicators (e.g., brachytherapy for cervix cancer and prostate cryotherapy)

  19. PET/CT in staging of the high risk prostate cancer

    International Nuclear Information System (INIS)

    Bergero, M.A.; David, C.; Dipatto, F.; Popeneciu, V.; Ríos, L.; Faccio, F.

    2016-01-01

    Objectives: In the last decade multimodal management of the high risk prostate cancer (HRPC) is a therapeutic option in selected patients and the staging of these patients depends on the current diagnostic methods (DM) which have low diagnostic accuracy for detecting metastasis (MTS). The positron emission tomography/computed tomography (PET/CT) would have a greater diagnostic accuracy and it is presented as a better DM for staging prostate cancer (PC). The aim of this article is present 2 patients in whom PET/CT modified the therapeutic decision and conduct a literature review. Materials and methods: 2 patients with HRPC who performed PET/CT and it modified the therapeutic behavior were described and a systematic review of the literature was conducted using PubMed, Embase, SciELO and Cochrane answering the question: has PET/CT a place in HRPC staging? Results: TPET/CT has a sensitivity and specificity between 19% to 100% and 67% to 98,5 %, respectively, in assessing nodal involvement by PC and between 84% to 96% and 92.3% to 100%, respectively, in assessing bone involvement by PC. Besides PET/CT allowed to modify the therapeutic behavior between 20% to 40% of the patients with PC. Conclusions: PET/CT has good specificity and moderate sensitivity for detecting lymph node MTS and good sensitivity and specificity for detecting bone MTS. Besides PET/CT modified the therapeutic behavior in 1/3 of cases and it allowed us to modify the therapeutic behavior in our series. (authors) [es

  20. Pulmonary lymphangioleiomyomatosis: high-resolution CT findings

    International Nuclear Information System (INIS)

    Kirchner, J.; Stein, A.; Thalhammer, A.; Jacobi, V.

    1999-01-01

    Lymphangioleiomyomatosis (LAM) of the lung is a very rare disease. There are obvious discrepancies in the literature concerning the appearance of LAM on CT scans of the lung. This study adds the imaging findings of 11 patients and demonstrates how the imaging findings changed over time in four patients. Twenty-two CT examinations, and radiographs that had been obtained close to the CT examinations, of 11 patients with LAM confirmed by open lung biopsy were retrospectively evaluated with particular attention to the size of cystic lesions and wall thickness. Furthermore the CT scans were analysed for the type of pulmonary infiltration process and its distribution, presence or absence of pleural effusion, pneumothorax and lymph node enlargement. Clinical and CT follow-up studies were available in four patients. The CT scans revealed an increase in the interstitial pattern in all patients. Architectural distortion was seen in two patients and cystic lesions were present in all. The size of the cysts varied from small lesions to bullous emphysema. The cystic lesions revealed a wall thickness up to 2 mm but a wall was not perceptible in all. Pneumothorax was seen in only two patients; pleural effusion was seen in two patients. CT examination of patients with LAM reveals neither a uniform nor a pathognomonic appearance. In the early stages of LAM or in cases with interstitial changes the differential diagnosis of centrilobular emphysema or idiopathic pulmonary fibrosis seems to be more difficult than most authors believe. (orig.) (orig.)

  1. Collateral Ventilation to Congenital Hyperlucent Lung Lesions Assessed on Xenon-Enhanced Dynamic Dual-Energy CT: an Initial Experience

    OpenAIRE

    Goo, Hyun Woo; Yang, Dong Hyun; Kim, Namkug; Park, Seung Il; Kim, Dong Kwan; Kim, Ellen Ai-Rhan

    2011-01-01

    Objective We wanted to evaluate the resistance to collateral ventilation in congenital hyperlucent lung lesions and to correlate that with the anatomic findings on xenon-enhanced dynamic dual-energy CT. Materials and Methods Xenon-enhanced dynamic dual-energy CT was successfully and safely performed in eight children (median age: 5.5 years, 4 boys and 4 girls) with congenital hyperlucent lung lesions. Functional assessment of the lung lesions on the xenon map was done, including performing a ...

  2. Pneumonia: high-resolution CT findings in 114 patients

    Energy Technology Data Exchange (ETDEWEB)

    Reittner, Pia [Department of Radiology, Vancouver Hospital and Health Sciences Center, 855 W. 12th Ave., Vancouver, BC (Canada); Department of Radiology, Karl Franzens University and University Hospital Graz, Auenbruggerplatz 9, 8036 Graz (Austria); Ward, Suzanne; Heyneman, Laura; Mueller, Nestor L. [Department of Radiology, Vancouver Hospital and Health Sciences Center, 855 W. 12th Ave., Vancouver, BC (Canada); Johkoh, Takeshi [Department of Radiology, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565-0825 (Japan)

    2003-03-01

    The objective of the present study was to assess the high-resolution CT appearances of different types of pneumonia. The high-resolution CT scans obtained in 114 patients (58 immunocompetent, 59 immunocompromised) with bacterial, Mycoplasma pneumoniae, viral, fungal, and Pneumocystis carinii pneumonias were analyzed retrospectively by two independent observers for presence, pattern, and distribution of abnormalities. Areas of air-space consolidation were not detected in patients with viral pneumonia and were less frequently seen in patients with Pneumocystis carinii pneumonia (2 of 22 patients, 9%) than in bacterial (30 of 35, 85%), Mycoplasma pneumoniae (22 of 28, 79%), and fungal pneumonias (15 of 20, 75%; p<0.01). There was no significant difference in the prevalence or distribution of consolidation between bacterial, Mycoplasma pneumoniae, and fungal pneumonias. Extensive symmetric bilateral areas of ground-glass attenuation were present in 21 of 22 (95%) patients with Pneumocystis carinii pneumonia and were not seen in other pneumonias except in association with areas of consolidation and nodules. Centrilobular nodules were present less commonly in bacterial pneumonia (6 of 35 patients, 17%) than in Mycoplasma pneumoniae (24 of 28, 96%), viral (7 of 9, 78%), or fungal (12 of 20, 92%) pneumonia (p<0.01). Except for Pneumocystis carinii pneumonia and Mycoplasma pneumoniae pneumonia, which often have a characteristic appearance, high-resolution CT is of limited value in the differential diagnosis of the various types of infective pneumonia. (orig.)

  3. Pneumonia: high-resolution CT findings in 114 patients

    International Nuclear Information System (INIS)

    Reittner, Pia; Ward, Suzanne; Heyneman, Laura; Mueller, Nestor L.; Johkoh, Takeshi

    2003-01-01

    The objective of the present study was to assess the high-resolution CT appearances of different types of pneumonia. The high-resolution CT scans obtained in 114 patients (58 immunocompetent, 59 immunocompromised) with bacterial, Mycoplasma pneumoniae, viral, fungal, and Pneumocystis carinii pneumonias were analyzed retrospectively by two independent observers for presence, pattern, and distribution of abnormalities. Areas of air-space consolidation were not detected in patients with viral pneumonia and were less frequently seen in patients with Pneumocystis carinii pneumonia (2 of 22 patients, 9%) than in bacterial (30 of 35, 85%), Mycoplasma pneumoniae (22 of 28, 79%), and fungal pneumonias (15 of 20, 75%; p<0.01). There was no significant difference in the prevalence or distribution of consolidation between bacterial, Mycoplasma pneumoniae, and fungal pneumonias. Extensive symmetric bilateral areas of ground-glass attenuation were present in 21 of 22 (95%) patients with Pneumocystis carinii pneumonia and were not seen in other pneumonias except in association with areas of consolidation and nodules. Centrilobular nodules were present less commonly in bacterial pneumonia (6 of 35 patients, 17%) than in Mycoplasma pneumoniae (24 of 28, 96%), viral (7 of 9, 78%), or fungal (12 of 20, 92%) pneumonia (p<0.01). Except for Pneumocystis carinii pneumonia and Mycoplasma pneumoniae pneumonia, which often have a characteristic appearance, high-resolution CT is of limited value in the differential diagnosis of the various types of infective pneumonia. (orig.)

  4. Grating-based X-ray phase-contrast tomography of atherosclerotic plaque at high photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Hetterich, Holger; Fill, Sandra [Klinikum der Ludwig-Maximilians-Univ., Muenchen (Germany). Inst. fuer Klinische Radiologie; Herzen, Julia [Technische Univ. Muenchen, Garching (Germany). Physik-Dept. und Inst. fuer Medizintechnik; Helmholtz-Zentrum Geesthacht, Geesthacht (Germany). Zentrum fuer Materialforschung] [and others

    2013-10-01

    Background: Tissue characterization of atherosclerosis by absorption-based imaging methods is limited due to low soft-tissue contrast. Grating-based phase-contrast computed tomography (PC-CT) may become an alternative for plaque assessment if the phase signal can be retrieved at clinically applicable photon energies. The aims of this feasibility study were (i) to characterize arterial vessels at low and high photon energies, (ii) to extract qualitative features and (iii) quantitative phase-contrast Hounsfield units (HU-phase) of plaque components at 53 keV using histopathology as gold standard. Materials and methods: Five human carotid artery specimens underwent grating-based PC-CT using synchrotron radiation of either 23 keV or 53 keV and histological work-up. Specimens without advanced atherosclerosis were used to extract signal criteria of vessel layers. Diseased specimens were screened for important plaque components including fibrous tissue (FT), lipid (LIP), necrotic core (NEC), intraplaque hemorrhage (IPH), inflammatory cell infiltration (INF) and calcifications (CA). Qualitative features as well as quantitative HU-phase were analyzed. Results: Thirty-three regions in 6 corresponding PC-CT scans and histology sections were identified. Healthy samples had the same signal characteristics at 23 keV and 53 keV with bright tunica intima and adventitia and dark media. Plaque components showed differences in signal intensity and texture at 53 keV. Quantitative analysis demonstrated the highest HU-phase of soft plaque in dense FT. Less organized LIP, NEC and INF were associated with lower HU-phase values. The highest HU-phase were measured in CA. Conclusion: PC-CT of atherosclerosis is feasible at high, clinically relevant photon energies and provides detailed information about plaque structure including features of high risk vulnerable plaques. (orig.)

  5. Obtaining the conversion curve of CT numbers to electron density from the effective energy of the CT using the dummy SEFM

    International Nuclear Information System (INIS)

    Martin-Viera Cueto, J. A.; Garcia Pareja, S.; Benitez Villegas, E. M.; Moreno Saiz, E. M.; Bodineau Gil, C.; Caudepon Moreno, F.

    2011-01-01

    The objective of this work is to obtain the conversion curve of Hounsfield units (A) versus electron densities using a mannequin with different tissue equivalent materials. This provides for the effective energy beam CT and is used to characterize the linear coefficients of absorption of different materials that comprise the dummy.

  6. Preliminary study on the differentiation between parapelvic cyst and hydronephrosis with non-calculous using only pre-contrast dual-energy spectral CT scans

    Science.gov (United States)

    Han, Dong; Ma, Guangming; Wei, Lequn; Ren, Chenglong; Zhou, Jieli; Shen, Chen

    2017-01-01

    Objective: To investigate the value of using the quantitative parameters from only the pre-contrast dual-energy spectral CT imaging for distinguishing between parapelvic cyst and hydronephrosis with non-calculous (HNC). Methods: This retrospective study was approved by the institutional review board. 28 patients with parapelvic cyst and 24 patients with HNC who underwent standard pre-contrast and multiphase contrast-enhanced dual-energy spectral CT imaging were retrospectively identified. The parapelvic cyst and HNC were identified using the contrast-enhanced scans, and their CT number in the 70-keV monochromatic images, effective atomic number (Zeff), iodine concentration (IC) and water concentration in the pre-contrast images were measured. The slope of the spectral curve (λ) was calculated. The difference in the measurements between parapelvic cyst and HNC was statistically analyzed using SPSS® v. 19.0 (IBM Corp., New York, NY; formerly SPSS Inc., Chicago, IL) statistical software. Receiver-operating characteristic analysis was performed to assess the diagnostic performance. Results: The CT numbers in the 70-keV images, Zeff and IC values were statistically different between parapelvic cyst and HNC (all p  0.05). Conclusion: The quantitative parameters obtained in the pre-contrast dual-energy spectral CT imaging may be used to differentiate between parapelvic cyst and HNC. Advances in knowledge: The pre-contrast dual-energy spectral CT scans may be used to screen parapelvic cysts for patients who are asymptomatic, thereby avoiding contrast-enhanced CT or CT urography examination for these patients to reduce ionizing radiation dose and contrast dose. PMID:28281789

  7. Pulmonary lymphangioleiomyomatosis: high-resolution CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Kirchner, J.; Stein, A.; Thalhammer, A.; Jacobi, V. [Mainz Univ. (Germany). Inst. fuer Allgemeine Roentgendiagnostik; Viel, K.; Dietrich, C.F. [Frankfurt Univ. (Germany). Medizinische Klinik II; Schneider, M. [Zentrum fuer Pathologie, Frankfurt Univ. (Germany)

    1999-02-01

    Lymphangioleiomyomatosis (LAM) of the lung is a very rare disease. There are obvious discrepancies in the literature concerning the appearance of LAM on CT scans of the lung. This study adds the imaging findings of 11 patients and demonstrates how the imaging findings changed over time in four patients. Twenty-two CT examinations, and radiographs that had been obtained close to the CT examinations, of 11 patients with LAM confirmed by open lung biopsy were retrospectively evaluated with particular attention to the size of cystic lesions and wall thickness. Furthermore the CT scans were analysed for the type of pulmonary infiltration process and its distribution, presence or absence of pleural effusion, pneumothorax and lymph node enlargement. Clinical and CT follow-up studies were available in four patients. The CT scans revealed an increase in the interstitial pattern in all patients. Architectural distortion was seen in two patients and cystic lesions were present in all. The size of the cysts varied from small lesions to bullous emphysema. The cystic lesions revealed a wall thickness up to 2 mm but a wall was not perceptible in all. Pneumothorax was seen in only two patients; pleural effusion was seen in two patients. CT examination of patients with LAM reveals neither a uniform nor a pathognomonic appearance. In the early stages of LAM or in cases with interstitial changes the differential diagnosis of centrilobular emphysema or idiopathic pulmonary fibrosis seems to be more difficult than most authors believe. (orig.) (orig.) With 5 figs., 2 tabs., 21 refs.

  8. High-resolution CT in eosinophilic granuloma (histiocytosis X) of the lung

    International Nuclear Information System (INIS)

    Godwin, J.D.; Buschman, D.L.; Moore, A.D.A.; Muller, N.L.; Naidich, D.P.; Carvalho, C.R.R.; Takasugi, J.E.; Schmidt, R.A.

    1988-01-01

    Eosinophilic granuloma of the lung is fascinating but poorly understood. Computed tomographic (CT) scans in 18 cases (11 high resolution) showed a variety of striking patterns: cysts up to 4 cm with thin or indiscernible walls, ranging from a few lesions to confluent honeycombing; retriculonodular infiltrate; and nodules 2 mm-2cm, sometimes cavitated. CT showed that the ill-defined lucencies barely visible on radiographs are indeed cysts, rather than preserved normal lung surrounded by infiltrate. High-resolution CT showed that some of the early, small nodules were concentrated along terminal bronchioles within the secondary lobules. The differential diagnosis includes sarcoidosis and idiopathic fibrosis, but the prominent cystic abnormality and the lack of peripheral concentration help to distinguish eosinophilic granuloma

  9. Thin-slice high-resolution CT study of pulmonary asbestosis and idiopathic interstitial pneumonia

    International Nuclear Information System (INIS)

    Hatakeyama, Masayuki; Maeda, Munehiro; Ohmura, Takuya

    1987-01-01

    Thin-slice high-resolution CT findings were compared between 36 patients with pulmonary asbestos exposure (AS) and 33 patients with idiopathic interstitial pneumonia (IIP). The CT scans of these patients were classified into 5 types (0-IV) by the subpleural curvilinear shadow (SCLS) and honey-comb shadow (HS). SCLS was detected in 22 (62 %) patients with AS and 7 (21 %) with IIP. HS was detected in 14 (39 %) patients with AS and 33 (100 %) with IIP. In both the diseases, SCLS was distributed mainly in the lower lobe in CT types I and II, and in mildly fibrotic segments in types III and IV. In CT types II, III and IV, SCLS was always communicated with HS. Thin-slice high-resolution CT is considered very helpful in diagnosis and staging of not only AS and IIP but also pulmonary fibrosis. (author)

  10. Advanced ceramic matrix composites for high energy x-ray generation

    International Nuclear Information System (INIS)

    Khan, Amir Azam; Labbe, Jean Claude

    2011-01-01

    High energy x-ray targets are the anodes used in high performance tubes, designed to work for long operating times and at high power. Such tubes are used in computed tomography (CT) scan machines. Usually the tubes used in CT scanners have to continuously work at high temperatures and for longer scan durations in order to get maximum information during a single scan. These anodes are composed of a refractory substrate which supports a refractory metallic coating. The present work is a review of the development of a ceramic metal composite based on aluminium nitride (AlN) and molybdenum for potential application as the substrate. This composite is surface engineered by coating with tungsten, the most popular material for high energy x-ray targets. To spray metallic coatings on the surface of ceramic matrix composites dc blown arc plasma is employed. The objective is to increase the performance and the life of an x-ray tube. Aluminium nitride-molybdenum ceramic matrix composites were produced by uniaxial hotpressing mixtures of AlN and Mo powders. These composites were characterized for their mechanical, thermal, electrical and micro-structural properties. An optimized composition was selected which contained 25 vol.% of metallic phase dispersed in the AlN matrix. These composites were produced in the actual size of an anode and coated with tungsten through dc blown arc plasma spraying. The results have shown that sintering of large size anodes is possible through uniaxial pressing, using a modified sintering cycle

  11. Determination of liquid's molecular interference function based on X-ray diffraction and dual-energy CT in security screening

    International Nuclear Information System (INIS)

    Zhang, Li; YangDai, Tianyi

    2016-01-01

    A method for deriving the molecular interference function (MIF) of an unknown liquid for security screening is presented. Based on the effective atomic number reconstructed from dual-energy computed tomography (CT), equivalent molecular formula of the liquid is estimated. After a series of optimizations, the MIF and a new effective atomic number are finally obtained from the X-ray diffraction (XRD) profile. The proposed method generates more accurate results with less sensitivity to the noise and data deficiency of the XRD profile. - Highlights: • EDXRD combined with dual-energy CT has been utilized for deriving the molecular interference function of an unknown liquid. • The liquid's equivalent molecular formula is estimated based on the effective atomic number reconstructed from dual-energy CT. • The proposed method provides two ways to estimate the molecular interference function: the simplified way and accurate way. • A new effective atomic number of the liquid could be obtained.

  12. Reconstruction of limited-angle dual-energy CT using mutual learning and cross-estimation (MLCE)

    Science.gov (United States)

    Zhang, Huayu; Xing, Yuxiang

    2016-03-01

    Dual-energy CT (DECT) imaging has gained a lot of attenuation because of its capability to discriminate materials. We proposes a flexible DECT scan strategy which can be realized on a system with general X-ray sources and detectors. In order to lower dose and scanning time, our DECT acquires two projections data sets on two arcs of limited-angular coverage (one for each energy) respectively. Meanwhile, a certain number of rays from two data sets form conjugate sampling pairs. Our reconstruction method for such a DECT scan mainly tackles the consequent limited-angle problem. Using the idea of artificial neural network, we excavate the connection between projections at two different energies by constructing a relationship between the linear attenuation coefficient of the high energy and that of the low one. We use this relationship to cross-estimate missing projections and reconstruct attenuation images from an augmented data set including projections at views covered by itself (projections collected in scanning) and by the other energy (projections estimated) for each energy respectively. Validated by our numerical experiment on a dental phantom with rather complex structures, our DECT is effective in recovering small structures in severe limited-angle situations. This DECT scanning strategy can much broaden DECT design in reality.

  13. Exploring metal artifact reduction using dual-energy CT with pre-metal and post-metal implant cadaver comparison: are implant specific protocols needed?

    NARCIS (Netherlands)

    Wellenberg, Ruud H. H.; Donders, Johanna C. E.; Kloen, Peter; Beenen, Ludo F. M.; Kleipool, Roeland P.; Maas, Mario; Streekstra, Geert J.

    2017-01-01

    To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans. Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel

  14. Single- and dual-energy quantitative CT adjacent to acetabular prosthetic components

    DEFF Research Database (Denmark)

    Mussmann, Bo Redder; Andersen, Poul Erik; Torfing, Trine

    2017-01-01

    and to compare BMD measurements in single and dual energy CT (SECT and DECT). Methods and Materials: 10 male patients with uncemented hip prosthetics were scanned and rescanned using 120 kVp SECT and DECT with virtual monochromatic images reconstructed at 130 keV. Hemispherical ROIs were defined slice...... that the intraobserver agreement of the scan modes is equal. BMD cannot be measured interchangeably with SECT and DECT....

  15. X-ray CT high-density artefact suppression in cryosurgery

    International Nuclear Information System (INIS)

    Wei Jikun; Sandison, George A; Chen Laigao; Liang Yun; Xu, Lisa X

    2002-01-01

    Advantages of x-ray CT for imaging guidance of cryosurgery include 3D visualization of frozen and unfrozen tissue and calibration of temperature in the tissue water-ice interface (0-10 deg. C) to Hounsfield units. However, use of x-ray CT images and their thermal calibration can be compromised by the cryoprobes generating high-density streak artefacts. A new subtraction technique for artefact suppression is proposed and tested in prostate cryosurgery simulations. By subtracting the measured CT x-ray projection profile without cryoprobes from the profile with cryoprobes plus iceballs, one obtains the combined profile of the cryoprobes and a low value background. Polynomial interpolation to obtain the background profile allows its addition to the original profile without probes. The result may then be fed to a conventional filtered back-projection routine to reconstruct the probe-free image. Finally the cryoprobe pixels in the originally constructed image with probes and iceballs are added back to the probe-free image to get the final artefact-suppressed image. The major advantage of this subtraction technique is that it can successfully suppress the high-density artefacts in bone-abundant body regions such as the pelvis. X-ray CT images of cryoprobe arrays in a homogeneous gelatin phantom and the pelvic region of an anthropomorphic Rando phantom containing a human skeleton were generated. After suppression, cryoprobe metal artefact streaks are reduced and visualization of the positions and dimensions of the cryoprobes are well preserved. (note)

  16. Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies.

    Science.gov (United States)

    Filograna, Laura; Magarelli, Nicola; Leone, Antonio; Guggenberger, Roman; Winklhofer, Sebastian; Thali, Michael John; Bonomo, Lorenzo

    2015-09-01

    The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging.

  17. Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies

    Energy Technology Data Exchange (ETDEWEB)

    Filograna, Laura [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland); Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Rome (Italy); Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo [Catholic University of Rome, School of Medicine, University Hospital ' ' A. Gemelli' ' , Department of Radiological Sciences, Rome (Italy); Guggenberger, Roman; Winklhofer, Sebastian [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Thali, Michael John [University of Zurich, Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, Zurich (Switzerland)

    2015-09-15

    The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging. (orig.)

  18. Value of monoenergetic dual-energy CT (DECT) for artefact reduction from metallic orthopedic implants in post-mortem studies

    International Nuclear Information System (INIS)

    Filograna, Laura; Magarelli, Nicola; Leone, Antonio; Bonomo, Lorenzo; Guggenberger, Roman; Winklhofer, Sebastian; Thali, Michael John

    2015-01-01

    The aim of this ex vivo study was to assess the performance of monoenergetic dual-energy CT (DECT) reconstructions to reduce metal artefacts in bodies with orthopedic devices in comparison with standard single-energy CT (SECT) examinations in forensic imaging. Forensic and clinical impacts of this study are also discussed. Thirty metallic implants in 20 consecutive cadavers with metallic implants underwent both SECT and DECT with a clinically suitable scanning protocol. Extrapolated monoenergetic DECT images at 64, 69, 88, 105, 120, and 130 keV and individually adjusted monoenergy for optimized image quality (OPTkeV) were generated. Image quality of the seven monoenergetic images and of the corresponding SECT image was assessed qualitatively and quantitatively by visual rating and measurements of attenuation changes induced by streak artefact. Qualitative and quantitative analyses showed statistically significant differences between monoenergetic DECT extrapolated images and SECT, with improvements in diagnostic assessment in monoenergetic DECT at higher monoenergies. The mean value of OPTkeV was 137.6 ± 4.9 with a range of 130 to 148 keV. This study demonstrates that monoenergetic DECT images extrapolated at high energy levels significantly reduce metallic artefacts from orthopedic implants and improve image quality compared to SECT examination in forensic imaging. (orig.)

  19. Noise-optimized virtual monoenergetic images and iodine maps for the detection of venous thrombosis in second-generation dual-energy CT (DECT): an ex vivo phantom study.

    Science.gov (United States)

    Bongers, Malte N; Schabel, Christoph; Krauss, Bernhard; Tsiflikas, Ilias; Ketelsen, Dominik; Mangold, Stefanie; Claussen, Claus D; Nikolaou, Konstantin; Thomas, Christoph

    2015-06-01

    Deep venous thrombosis (DVT) can be difficult to detect using CT due to poor and heterogeneous contrast. Dual-energy CT (DECT) allows iodine contrast optimization using noise-optimized monoenergetic extrapolations (MEIs) and iodine maps (IMs). Our aim was to assess whether MEI and IM could improve the delineation of thrombotic material within iodine-enhanced blood compared to single-energy CT (SECT). Six vessel phantoms, including human thrombus and contrast media-enhanced blood and one phantom without contrast, were placed in an attenuation phantom and scanned with DECT 100/140 kV and SECT 120 kV. IM, virtual non-contrast images (VNC), mixed images, and MEI were calculated. Attenuation of thrombi and blood were measured. Contrast and contrast-to-noise-ratios (CNRs) were calculated and compared among IM, VNC, mixed images, MEI, and SECT using paired t tests. MEI40keV and IM showed significantly higher contrast and CNR than SE120kV from high to intermediate iodine concentrations (contrast:pMEI40keV VNC images showed significantly higher contrast and CNR than SE120kV with inverted contrasts (contrast:pMEI190keV < 0.008,pVNC < 0.002;CNR:pMEI190keV < 0.003,pVNC < 0.002). Noise-optimized MEI and IM provide significantly higher contrast and CNR in the delineation of thrombosis compared to SECT, which may facilitate the detection of DVT in difficult cases. • Poor contrast makes it difficult to detect thrombosis in CT. • Dual-energy-CT allows contrast optimization using monoenergetic extrapolations (MEI) and iodine maps (IM). • Noise-optimized-MEI and IM are significantly superior to single-energy-CT in delineation of thrombosis. • Noise-optimized-MEI and IM may facilitate the detection of deep vein thrombosis.

  20. Energy-resolved computed tomography: first experimental results

    International Nuclear Information System (INIS)

    Shikhaliev, Polad M

    2008-01-01

    First experimental results with energy-resolved computed tomography (CT) are reported. The contrast-to-noise ratio (CNR) in CT has been improved with x-ray energy weighting for the first time. Further, x-ray energy weighting improved the CNR in material decomposition CT when applied to CT projections prior to dual-energy subtraction. The existing CT systems use an energy (charge) integrating x-ray detector that provides a signal proportional to the energy of the x-ray photon. Thus, the x-ray photons with lower energies are scored less than those with higher energies. This underestimates contribution of lower energy photons that would provide higher contrast. The highest CNR can be achieved if the x-ray photons are scored by a factor that would increase as the x-ray energy decreases. This could be performed by detecting each x-ray photon separately and measuring its energy. The energy selective CT data could then be saved, and any weighting factor could be applied digitally to a detected x-ray photon. The CT system includes a photon counting detector with linear arrays of pixels made from cadmium zinc telluride (CZT) semiconductor. A cylindrical phantom with 10.2 cm diameter made from tissue-equivalent material was used for CT imaging. The phantom included contrast elements representing calcifications, iodine, adipose and glandular tissue. The x-ray tube voltage was 120 kVp. The energy selective CT data were acquired, and used to generate energy-weighted and material-selective CT images. The energy-weighted and material decomposition CT images were generated using a single CT scan at a fixed x-ray tube voltage. For material decomposition the x-ray spectrum was digitally spilt into low- and high-energy parts and dual-energy subtraction was applied. The x-ray energy weighting resulted in CNR improvement of calcifications and iodine by a factor of 1.40 and 1.63, respectively, as compared to conventional charge integrating CT. The x-ray energy weighting was also applied

  1. Study of CT Scan Flooding System at High Temperature and Pressure

    Science.gov (United States)

    Chen, X. Y.

    2017-12-01

    CT scan flooding experiment can scan micro-pore in different flooding stages by the use of CT scan technology, without changing the external morphology and internal structure of the core, and observe the distribution characterization in pore medium of different flooding fluid under different pressure.thus,it can rebuilt the distribution images of oil-water distribution in different flooding stages. However,under extreme high pressure and temperature conditions,the CT scan system can not meet the requirements. Container of low density materials or thin shell can not resist high pressure,while high density materials or thick shell will cause attenuation and scattering of X-ray. The experiment uses a simple Ct scanning systems.X ray from a point light source passing trough a micro beryllium shell on High pressure stainless steal container,continuously irradiates the core holder that can continuously 360° rotate along the core axis. A rare earth intensifying screen behind the core holder emitting light when irradiated with X ray can show the core X ray section image. An optical camera record the core X ray images through a transparency high pressure glazing that placed on the High pressure stainless steal container.Thus,multiple core X ray section images can reconstruct the 3D core reconstruction after a series of data processing.The experiment shows that both the micro beryllium shell and rare earth intensifying screen can work in high temperature and high pressure environment in the stainless steal container. This way that X-ray passes through a thin layer of micro beryllium shell , not high pressure stainless steal shell,avoid the attenuation and scattering of X-ray from the container shell,while improving the high-pressure experiment requirements.

  2. The effect of Moidal non-linear blending function for dual-energy CT on CT image quality

    International Nuclear Information System (INIS)

    Zhang Fan; Yang Li

    2011-01-01

    Objective: To compare the difference between linear blending and non-linear blending function for dual-energy CT, and to evaluate the effect on CT image quality. Methods: The model was made of a piece of fresh pork liver inserted with 5 syringes containing various concentrations of iodine solutions (16.3, 26.4, 48.7, 74.6 and 112.3 HU). Linear blending images were automatically reformatted after the model was scanned in the dual-energy mode. Non-linear blending images were reformatted using the software of optimal contrast in Syngo workstation. Images were divided into 3 groups, including linear blending group, non-linear blending group and 120 kV group. Contrast noise ratio (CNR) were measured and calculated respectively in the 3 groups and the different figure of merit (FOM) values between the groups were compared using one-way ANOVA. Twenty patients scanned in the dual-energy mode were randomly selected and the SNR of their liver, renal cortex, spleen, pancreas and abdominal aorta were measured. The independent sample t test was used to compare the difference of signal to noise ratio (SNR) between linear blending group and non linear blending group. Two readers' agreement score and single-blind method were used to investigate the conspicuity difference between linear blending group and non linear blending group. Results: With models of different CT values, the FOM values in non-linear blending group were 20.65± 8.18, 11.40±4.25, 1.60±0.82, 2.40±1.13, 45.49±17.86. In 74.6 HU and 112.3 HU models, the differences of the FOM values observed among the three groups were statistically significant (P<0.05), which were 0.30±0.06 and 14.43±4.59 for linear blending group, and 0.22±0.05 and 15.31±5.16 for 120 kV group. And non-linear blending group had a better FOM value. The SNR of renal cortex and abdominal aorta were 19.2±5.1 and 36.5±13.9 for non-linear blending group, while they were 12.4±3.8 and 22.6±7.0 for linear blending group. There were statistically

  3. Multimaterial Decomposition Algorithm for the Quantification of Liver Fat Content by Using Fast-Kilovolt-Peak Switching Dual-Energy CT: Clinical Evaluation.

    Science.gov (United States)

    Hyodo, Tomoko; Yada, Norihisa; Hori, Masatoshi; Maenishi, Osamu; Lamb, Peter; Sasaki, Kosuke; Onoda, Minori; Kudo, Masatoshi; Mochizuki, Teruhito; Murakami, Takamichi

    2017-04-01

    Purpose To assess the clinical accuracy and reproducibility of liver fat quantification with the multimaterial decomposition (MMD) algorithm, comparing the performance of MMD with that of magnetic resonance (MR) spectroscopy by using liver biopsy as the reference standard. Materials and Methods This prospective study was approved by the institutional ethics committee, and patients provided written informed consent. Thirty-three patients suspected of having hepatic steatosis underwent non-contrast material-enhanced and triple-phase dynamic contrast-enhanced dual-energy computed tomography (CT) (80 and 140 kVp) and single-voxel proton MR spectroscopy within 30 days before liver biopsy. Percentage fat volume fraction (FVF) images were generated by using the MMD algorithm on dual-energy CT data to measure hepatic fat content. FVFs determined by using dual-energy CT and percentage fat fractions (FFs) determined by using MR spectroscopy were compared with histologic steatosis grade (0-3, as defined by the nonalcoholic fatty liver disease activity score system) by using Jonckheere-Terpstra trend tests and were compared with each other by using Bland-Altman analysis. Real non-contrast-enhanced FVFs were compared with triple-phase contrast-enhanced FVFs to determine the reproducibility of MMD by using Bland-Altman analyses. Results Both dual-energy CT FVF and MR spectroscopy FF increased with increasing histologic steatosis grade (trend test, P algorithm quantifying hepatic fat in dual-energy CT images is accurate and reproducible across imaging phases. © RSNA, 2017 Online supplemental material is available for this article.

  4. Activity-based cost analysis of hepatic tumor ablation using CT-guided high-dose rate brachytherapy or CT-guided radiofrequency ablation in hepatocellular carcinoma.

    Science.gov (United States)

    Schnapauff, D; Collettini, F; Steffen, I; Wieners, G; Hamm, B; Gebauer, B; Maurer, M H

    2016-02-25

    To analyse and compare the costs of hepatic tumor ablation with computed tomography (CT)-guided high-dose rate brachytherapy (CT-HDRBT) and CT-guided radiofrequency ablation (CT-RFA) as two alternative minimally invasive treatment options of hepatocellular carcinoma (HCC). An activity based process model was created determining working steps and required staff of CT-RFA and CT-HDRBT. Prorated costs of equipment use (purchase, depreciation, and maintenance), costs of staff, and expenditure for disposables were identified in a sample of 20 patients (10 treated by CT-RFA and 10 by CT-HDRBT) and compared. A sensitivity and break even analysis was performed to analyse the dependence of costs on the number of patients treated annually with both methods. Costs of CT-RFA were nearly stable with mean overall costs of approximately 1909 €, 1847 €, 1816 € and 1801 € per patient when treating 25, 50, 100 or 200 patients annually, as the main factor influencing the costs of this procedure was the single-use RFA probe. Mean costs of CT-HDRBT decreased significantly per patient ablation with a rising number of patients treated annually, with prorated costs of 3442 €, 1962 €, 1222 € and 852 € when treating 25, 50, 100 or 200 patients, due to low costs of single-use disposables compared to high annual fix-costs which proportionally decreased per patient with a higher number of patients treated annually. A break-even between both methods was reached when treating at least 55 patients annually. Although CT-HDRBT is a more complex procedure with more staff involved, it can be performed at lower costs per patient from the perspective of the medical provider when treating more than 55 patients compared to CT-RFA, mainly due to lower costs for disposables and a decreasing percentage of fixed costs with an increasing number of treatments.

  5. High resolution CT in diffuse lung disease

    International Nuclear Information System (INIS)

    Webb, W.R.

    1995-01-01

    High resolution CT (computerized tomography) was discussed in detail. The conclusions were HRCT is able to define lung anatomy at the secondary lobular level and define a variety of abnormalities in patients with diffuse lung diseases. Evidence from numerous studies indicates that HRCT can play a major role in the assessment of diffuse infiltrative lung disease and is indicate clinically (95 refs.)

  6. High resolution CT in diffuse lung disease

    Energy Technology Data Exchange (ETDEWEB)

    Webb, W R [California Univ., San Francisco, CA (United States). Dept. of Radiology

    1996-12-31

    High resolution CT (computerized tomography) was discussed in detail. The conclusions were HRCT is able to define lung anatomy at the secondary lobular level and define a variety of abnormalities in patients with diffuse lung diseases. Evidence from numerous studies indicates that HRCT can play a major role in the assessment of diffuse infiltrative lung disease and is indicate clinically (95 refs.).

  7. Dose heterogeneity correction for low-energy brachytherapy sources using dual-energy CT images

    Science.gov (United States)

    Mashouf, S.; Lechtman, E.; Lai, P.; Keller, B. M.; Karotki, A.; Beachey, D. J.; Pignol, J. P.

    2014-09-01

    Permanent seed implant brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG-43 formalism, which generates the dose in a homogeneous water medium. Recently, AAPM TG-186 emphasized the importance of accounting for tissue heterogeneities. We have previously reported on a methodology where the absorbed dose in tissue can be obtained by multiplying the dose, calculated by the TG-43 formalism, by an inhomogeneity correction factor (ICF). In this work we make use of dual energy CT (DECT) images to extract ICF parameters. The advantage of DECT over conventional CT is that it eliminates the need for tissue segmentation as well as assignment of population based atomic compositions. DECT images of a heterogeneous phantom were acquired and the dose was calculated using both TG-43 and TG-43 × \\text{ICF} formalisms. The results were compared to experimental measurements using Gafchromic films in the mid-plane of the phantom. For a seed implant configuration of 8 seeds spaced 1.5 cm apart in a cubic structure, the gamma passing score for 2%/2 mm criteria improved from 40.8% to 90.5% when ICF was applied to TG-43 dose distributions.

  8. The linear attenuation coefficients as features of multiple energy CT image classification

    International Nuclear Information System (INIS)

    Homem, M.R.P.; Mascarenhas, N.D.A.; Cruvinel, P.E.

    2000-01-01

    We present in this paper an analysis of the linear attenuation coefficients as useful features of single and multiple energy CT images with the use of statistical pattern classification tools. We analyzed four CT images through two pointwise classifiers (the first classifier is based on the maximum-likelihood criterion and the second classifier is based on the k-means clustering algorithm) and one contextual Bayesian classifier (ICM algorithm - Iterated Conditional Modes) using an a priori Potts-Strauss model. A feature extraction procedure using the Jeffries-Matusita (J-M) distance and the Karhunen-Loeve transformation was also performed. Both the classification and the feature selection procedures were found to be in agreement with the predicted discrimination given by the separation of the linear attenuation coefficient curves for different materials

  9. Multiple-energy Techniques in Industrial Computerized Tomography

    Science.gov (United States)

    Schneberk, D.; Martz, H.; Azevedo, S.

    1990-08-01

    Considerable effort is being applied to develop multiple-energy industrial CT techniques for materials characterization. Multiple-energy CT can provide reliable estimates of effective Z (Z{sub eff}), weight fraction, and rigorous calculations of absolute density, all at the spatial resolution of the scanner. Currently, a wide variety of techniques exist for CT scanners, but each has certain problems and limitations. Ultimately, the best multi-energy CT technique would combine the qualities of accuracy, reliability, and wide range of application, and would require the smallest number of additional measurements. We have developed techniques for calculating material properties of industrial objects that differ somewhat from currently used methods. In this paper, we present our methods for calculating Z{sub eff}, weight fraction, and density. We begin with the simplest case -- methods for multiple-energy CT using isotopic sources -- and proceed to multiple-energy work with x-ray machine sources. The methods discussed here are illustrated on CT scans of PBX-9502 high explosives, a lexan-aluminum phantom, and a cylinder of glass beads used in a preliminary study to determine if CT can resolve three phases: air, water, and a high-Z oil. In the CT project at LLNL, we have constructed several CT scanners of varying scanning geometries using {gamma}- and x-ray sources. In our research, we employed two of these scanners: pencil-beam CAT for CT data using isotopic sources and video-CAT equipped with an IRT micro-focal x-ray machine source.

  10. Normal lumbar spine bone mineral densities with single-energy CT

    International Nuclear Information System (INIS)

    Hendrick, R.E.; Ritenour, E.R.; Geis, J.R.; Thickman, D.; Freeman, K.

    1988-01-01

    The authors report trabecular spine densities determined by single-energy CT in 267 healthy women, aged 22 to 75 years. Volunteers were scanned at eight sites with use of identical fourth-generation CT scanners, postpatient calibration phantoms, and analysis software that accounts for beam hardening as a function of patient size. Results indicate that a cubic polynomial best represents the decrease in bone density (in milligrams per milliliter of K 2 HPO 4 ) with age (in years): Bone Density = 140.9 + 4.44(Age) - 0.133(Age) 2 + 0.0008(Age) 3 , with statistical significance over the best linear and quadratic polynomial fits (P < .001). The mean bone densities of healthy women above age 30 years are found to be lower by an average of 8 mg/mL than reported by Cann et al, whose data indicate that the greatest loss in trabecular bone density in healthy women occurs in the 50-59-year group, while out data indicate greatest loss in the 60-75 year age group

  11. Diagnostic accuracy of dual energy CT angiography in patients with diabetes mellitus; Diagnostische Genauigkeit der Dual-energy-CT-Angiographie bei Patienten mit Diabetes mellitus

    Energy Technology Data Exchange (ETDEWEB)

    Schabel, C.; Bongers, M.N.; Syha, R. [Klinikum der Eberhard-Karls-Universitaet, Abteilung fuer Diagnostische und Interventionelle Radiologie, Tuebingen (Germany); Klinikum der Eberhard-Karls-Universitaet, Sektion fuer Experimentelle Radiologie der Abteilung fuer Diagnostische und Interventionelle Radiologie, Tuebingen (Germany); Ketelsen, D.; Homann, G.; Notohamiprodjo, M.; Nikolaou, K.; Bamberg, F. [Klinikum der Eberhard-Karls-Universitaet, Abteilung fuer Diagnostische und Interventionelle Radiologie, Tuebingen (Germany); Thomas, C. [Universitaetsklinikum Duesseldorf, Abteilung fuer Diagnostische und Interventionelle Radiologie, Duesseldorf (Germany)

    2015-04-01

    Peripheral arterial disease (PAD) represents a major and highly prevalent complication in patients with diabetes mellitus. The diagnostic, non-invasive work-up by computed tomography angiography (CTA) is limited in the presence of extensive calcification. The aim of the study was to determine the diagnostic accuracy of dual energy CTA (DE-CTA) for the detection and characterization of PAD in patients with diabetes mellitus. In this study 30 diabetic patients with suspected or known PAD were retrospectively included in the analysis. All subjects underwent DE-CTA (Somatom Definition Flash, Siemens Healthcare, Erlangen, Germany) prior to invasive angiography, which served as the reference standard. Blinded analysis included assessment of the presence and degree of peripheral stenosis on curved multiplanar reformatting (MPR) and maximum intensity projections (MIP). Conventional measures of diagnostic accuracy were derived. Among the 30 subjects included in the analysis (83 % male, mean age 70.0 ± 10.5 years, 83 % diabetes type 2), the prevalence of critical stenosis in 331 evaluated vessel segments was high (30 %). Dual energy CT identified critical stenoses with a high sensitivity and good specificity using curved MPR (100 % and 93.1 %, respectively) and MIP images (99 % and 91.8 %, respectively). In stratified analysis, the diagnostic accuracy was higher for stenosis pertaining to the pelvic and thigh vessels as compared with the lower extremities (curved MPR accuracy 97.1 % vs. 99.2 vs. 90.9 %; respectively, p < 0.001). The use of DE-CTA allows reliable detection and characterization of peripheral arterial stenosis in patients with diabetes mellitus with higher accuracy in vessels in the pelvic and thigh regions compared with the vessels in the lower legs. (orig.) [German] Die periphere arterielle Verschlusskrankheit (PAVK) ist eine wesentliche Komplikation des Diabetes mellitus und stellt aufgrund ausgepraegter Gefaessverkalkungen eine diagnostische

  12. Preliminary study of single contrast enhanced dual energy heart imaging using dual-source CT

    International Nuclear Information System (INIS)

    Peng Jin; Zhang Longjiang; Zhou Changsheng; Lu Guangming; Ma Yan; Gu Haifeng

    2009-01-01

    Objective: To evaluate the feasibility and preliminary applications of single contrast enhanced dual energy heart imaging using dual-source CT (DSCT). Methods: Thirty patients underwent dual energy heart imaging with DSCT, of which 6 cases underwent SPECT or DSA within one week. Two experienced radiologists assessed image quality of coronary arteries and iodine map of myocardium. and correlated the coronary artery stenosis with the perfusion distribution of iodine map. Results: l00% (300/300) segments reached diagnostic standards. The mean score of image for all patients was 4.68±0.57. Mural coronary artery was present in 10 segments in S cases, atherosclerotic plaques in 32 segments in 12 cases, of which 20 segments having ≥50% stenosis, 12 segments ≤50% stenosis; dual energy CT coronary angiography was consistent with the DSA in 3 patients. 37 segmental perfusion abnormalities on iodine map were found in 15 cases, including 28 coronary blood supply segment narrow segment and 9 no coronary stenosis (including three negative segments in SPECD. Conclusion: Single contrast enhanced dual energy heart imaging can provide good coronary artery and myocardium perfusion images in the patients with appropriate heart rate, which has a potential to be used in the clinic and further studies are needed. (authors)

  13. 3D-CT of the temporal bone area with high-speed processing

    International Nuclear Information System (INIS)

    Hattori, Taku

    1994-01-01

    Three-dimentional (3D)-CT was introduced to represent abnormal findings in the temporal bone area utilizing a SOMATOM DRH CT scanner with accessory 3D reconstruction software and an exclusive high-speed 3D processing system, VOXEL FLINGER. In a patient with eosinophilic granuloma, a defect in the squamous part of the temporal bone was demonstrated suggesting exposure of the dura mater during surgery. In a patient with a normal ear, well-developed mastoid cavity, a part of the handle and the head of the malleus, the incudomalleal joint, the short limb, body and a part of the long limb of the incus and the round window niche were demonstrated. In a case of chronic otitis media, poorly developed mastoid cavity and a possible defect of the tip of the long limb of the incus were demonstrated, in contrast to the patient with the normal ear. 3D-CT yields objective and solid images which are useful for diagnosis, treatment planning and explanation of the pathology to patients and their family. To obtain convincing 3D images, physicians themselves have to choose exact rotation angles. It is not adequate to reconstruct original CT data using a CT computer with accessory 3D software whose processing capability is not good enough for this purpose. The conclusion is as follows: 1) it is necessary and effective to transfer original CT data into the memory of the exclusive high-speed 3D processing system and 2) process the data by the voxel memory method to establish a clinically valuable 3D-CT imaging system. (author)

  14. Exploring metal artifact reduction using dual-energy CT with pre-metal and post-metal implant cadaver comparison: are implant specific protocols needed?

    Science.gov (United States)

    Wellenberg, Ruud H H; Donders, Johanna C E; Kloen, Peter; Beenen, Ludo F M; Kleipool, Roeland P; Maas, Mario; Streekstra, Geert J

    2017-08-25

    To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans. Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel tibia plate and a titanium intramedullary nail respectively. Virtual monochromatic images were analyzed from 70 to 190 keV. Region-of-interest (ROI), used to determine fluctuations and inaccuracies in CT numbers of soft tissues and bone, were placed in muscle, fat, cortical bone and intramedullary tibia canal. The stainless-steel implant resulted in more pronounced metal artifacts compared to both titanium implants. CT number inaccuracies in 70 keV reference images were minimized at 130, 180 and 190 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Noise, measured as the standard deviation of pixels within a ROI, was minimized at 130, 150 and 140 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Tailoring dual-energy CT protocols using implant specific virtual monochromatic images minimizes fluctuations and inaccuracies in CT numbers in bone and soft tissues compared to non-metal reference scans.

  15. High resolution CT in children with cystic fibrosis

    International Nuclear Information System (INIS)

    Stiglbauer, R.; Schurawitzki, H.; Eichler, I.; Goetz, M.

    1992-01-01

    High resolution CT (HRCT) was performed in 24 children (median age 57.9 months) suffering from cystic fibrosis (CF). In 23 patients (one examination unacceptable because of motion artifacts) the most frequent finding was bronchial wall thickening, shown in 21 patients (91%), followed by bronchiectasis in 15 patients (65%). Less frequent findings were mucus plugging and patchy consolidations, which could be demonstrated in 11 patients each (48%). Findings were classified using a CT scoring system and including only irreversible pulmonary changes; a statistically significant correlation with lung function tests could be established. HRCT to date seems to be the most valuable method to determine extent and severity of lung involvement in children with CF and should therefore be routinely used for the staging of this disease. (orig.)

  16. High-resolution CT of temporal bone trauma: review of 38 cases

    International Nuclear Information System (INIS)

    Hiroual, M.R.; Zougarhi, A.; Cherif Idrissi El Ganouni, N.; Essadki, O.; Ousehal, A.; Tijani Adil, O.; Maliki, O.; Aderdour, L.; Raji, A.

    2010-01-01

    Purpose Temporal bone trauma is frequent but difficult to assess due to the diversity of clinical presentations and complex anatomy. We have sought to assess the different types of fractures and complications on high-resolution CT. Materials and methods Descriptive retrospective study over a 24 month period performed in the ENT radiology section of the Mohammed 6 university medical center in Marrakech. A total of 38 cases of temporal bone trauma were reviewed. All patients underwent ENT evaluation and high-resolution CT of the temporal bone using 1 mm axial and coronal sections. Results Mean patient age was 33 years (range: 14-55 years) with male predominance (sex ratio: 36/2). Clinical symptoms were mainly otorrhagia and conductive hearing loss. Oblique extra-labyrinthine fractures were most frequent. Two cases of pneumo-labyrinth were noted. Management was conservative in most cases with deafness in 3 cases. Conclusion High-resolution CT of the temporal bone provides accurate depiction of lesions explaining the clinical symptoms and helps guide management. MRI is complimentary to further assess the labyrinth and VII-VIII nerve complex. (author)

  17. Three-rooted premolar analyzed by high-resolution and cone beam CT.

    Science.gov (United States)

    Marca, Caroline; Dummer, Paul M H; Bryant, Susan; Vier-Pelisser, Fabiana Vieira; Só, Marcus Vinicius Reis; Fontanella, Vania; Dutra, Vinicius D'avila; de Figueiredo, José Antonio Poli

    2013-07-01

    The aim of this study was to analyze the variations in canal and root cross-sectional area in three-rooted maxillary premolars between high-resolution computed tomography (μCT) and cone beam computed tomography (CBCT). Sixteen extracted maxillary premolars with three distinct roots and fully formed apices were scanned using μCT and CBCT. Photoshop CS software was used to measure root and canal cross-sectional areas at the most cervical and the most apical points of each root third in images obtained using the two tomographic computed (CT) techniques, and at 30 root sections equidistant from both root ends using μCT images. Canal and root areas were compared between each method using the Student t test for paired samples and 95 % confidence intervals. Images using μCT were sharper than those obtained using CBCT. There were statistically significant differences in mean area measurements of roots and canals between the μCT and CBCT techniques (P < 0.05). Root and canal areas had similar variations in cross-sectional μCT images and became proportionally smaller in a cervical to apical direction as the cementodentinal junction was approached, from where the area then increased apically. Although variation was similar in the roots and canals under study, CBCT produced poorer image details than μCT. Although CBCT is a strong diagnosis tool, it still needs improvement to provide accuracy in details of the root canal system, especially in cases with anatomical variations, such as the three-rooted maxillary premolars.

  18. Improved detection of sentinel lymph nodes in SPECT/CT images acquired using a low- to medium-energy general-purpose collimator.

    Science.gov (United States)

    Yoneyama, Hiroto; Tsushima, Hiroyuki; Kobayashi, Masato; Onoguchi, Masahisa; Nakajima, Kenichi; Kinuya, Seigo

    2014-01-01

    The use of the low-energy high-resolution (LEHR) collimator for lymphoscintigraphy causes the appearance of star-shaped artifacts at injection sites. The aim of this study was to confirm whether the lower resolution of the low- to medium-energy general-purpose (LMEGP) collimator is compensated by decrease in the degree of septal penetration and the reduction in star-shaped artifacts. A total of 106 female patients with breast cancer, diagnosed by biopsy, were enrolled in this study. Tc phytate (37 MBq, 1 mCi) was injected around the tumor, and planar and SPECT/CT images were obtained after 3 to 4 hours. When sentinel lymph nodes (SLNs) could not be identified from planar and SPECT/CT images by using the LEHR collimator, we repeated the study with the LMEGP collimator. Planar imaging performed using the LEHR and LEHR + LMEGP collimators positively identified SLNs in 96.2% (102/106) and 99.1% (105/106) of the patients, respectively. Using combination of planar and SPECT/CT imaging with the LEHR and LEHR + LMEGP collimators, SLNs were positively identified in 97.2% (103/106) and 100% (106/106) of the patients, respectively. The LMEGP collimator provided better results than the LEHR collimator because of the lower degree of septal penetration. The use of the LMEGP collimator improved SLN detection.

  19. Accuracy of Dual-Energy Virtual Monochromatic CT Numbers: Comparison between the Single-Source Projection-Based and Dual-Source Image-Based Methods.

    Science.gov (United States)

    Ueguchi, Takashi; Ogihara, Ryota; Yamada, Sachiko

    2018-03-21

    To investigate the accuracy of dual-energy virtual monochromatic computed tomography (CT) numbers obtained by two typical hardware and software implementations: the single-source projection-based method and the dual-source image-based method. A phantom with different tissue equivalent inserts was scanned with both single-source and dual-source scanners. A fast kVp-switching feature was used on the single-source scanner, whereas a tin filter was used on the dual-source scanner. Virtual monochromatic CT images of the phantom at energy levels of 60, 100, and 140 keV were obtained by both projection-based (on the single-source scanner) and image-based (on the dual-source scanner) methods. The accuracy of virtual monochromatic CT numbers for all inserts was assessed by comparing measured values to their corresponding true values. Linear regression analysis was performed to evaluate the dependency of measured CT numbers on tissue attenuation, method, and their interaction. Root mean square values of systematic error over all inserts at 60, 100, and 140 keV were approximately 53, 21, and 29 Hounsfield unit (HU) with the single-source projection-based method, and 46, 7, and 6 HU with the dual-source image-based method, respectively. Linear regression analysis revealed that the interaction between the attenuation and the method had a statistically significant effect on the measured CT numbers at 100 and 140 keV. There were attenuation-, method-, and energy level-dependent systematic errors in the measured virtual monochromatic CT numbers. CT number reproducibility was comparable between the two scanners, and CT numbers had better accuracy with the dual-source image-based method at 100 and 140 keV. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  20. Enhanced intersystem crossing via a high energy charge transfer state in a perylenediimide-perylenemonoimide dyad

    NARCIS (Netherlands)

    Veldman, D.; Chopin-Cado, S.M.A; Meskers, S.C.J.; Janssen, R.A.J.

    2008-01-01

    The electronic relaxation processes of a photoexcited linear perylenediimide-perylenemonoimide (PDI-PMI) acceptor-donor dyad were studied. PDI-PMI serves as a model compound for donor-acceptor systems in photovoltaic devices and has been designed to have a high-energy PDI--PMI + charge transfer (CT)

  1. Simultaneous Reduction in Noise and Cross-Contamination Artifacts for Dual-Energy X-Ray CT

    Directory of Open Access Journals (Sweden)

    Baojun Li

    2013-01-01

    Full Text Available Purpose. Dual-energy CT imaging tends to suffer from much lower signal-to-noise ratio than single-energy CT. In this paper, we propose an improved anticorrelated noise reduction (ACNR method without causing cross-contamination artifacts. Methods. The proposed algorithm diffuses both basis material density images (e.g., water and iodine at the same time using a novel correlated diffusion algorithm. The algorithm has been compared to the original ACNR algorithm in a contrast-enhanced, IRB-approved patient study. Material density accuracy and noise reduction are quantitatively evaluated by the percent density error and the percent noise reduction. Results. Both algorithms have significantly reduced the noises of basis material density images in all cases. The average percent noise reduction is 69.3% and 66.5% with the ACNR algorithm and the proposed algorithm, respectively. However, the ACNR algorithm alters the original material density by an average of 13% (or 2.18 mg/cc with a maximum of 58.7% (or 8.97 mg/cc in this study. This is evident in the water density images as massive cross-contaminations are seen in all five clinical cases. On the contrary, the proposed algorithm only changes the mean density by 2.4% (or 0.69 mg/cc with a maximum of 7.6% (or 1.31 mg/cc. The cross-contamination artifacts are significantly minimized or absent with the proposed algorithm. Conclusion. The proposed algorithm can significantly reduce image noise present in basis material density images from dual-energy CT imaging, with minimized cross-contaminations compared to the ACNR algorithm.

  2. The use of thin-section high-resolution CT in pediatric pulmonary disease

    International Nuclear Information System (INIS)

    Hay, T.C.; Horgan, J.G.; Rumack, C.M.

    1989-01-01

    High-resolution thin-section CT of the chest was used successfully to characterize the extent of pulmonary disease. This paper reports on a study in which ten children with chronic lung disorders (including cystic fibrosis, reactive airway disease, and idiopathic disease) were evaluated to test the accuracy of the posteroanterior and lateral chest CT, with both thick (1 cm) and thin (1-3 mm) sections. Unsuspected bronchiectasis was established n two patients with reactive airway disease, and the extent of bronchiectasis in other patients was best defined on thin-section CT. Technique was crucial for an accurate study, and magnification views of each lung were useful. Thin-section CT of the chest was helpful in defining and localizing the extent of these pulmonary disorders

  3. Phase-contrast X-ray CT

    Energy Technology Data Exchange (ETDEWEB)

    Momose, Atsushi [Hitachi Ltd., Saitama (Japan). Advanced Research Laboratory; Takeda, Tohoru; Itai, Yuji

    1995-12-01

    Phase-contrast X-ray computed tomography (CT) enabling the observation of biological soft tissues without contrast enhancement has been developed. The X-ray phase shift caused by an object is measured and input to a standard CT reconstruction algorithm. A thousand times increase in the image sensitivity to soft tissues is achieved compared with the conventional CT using absorption contrast. This is because the X-ray phase shift cross section of light elements is about a thousand times larger than the absorption cross section. The phase shift is detected using an X-ray interferometer and computer analyses of interference patterns. Experiments were performed using a synchrotron X-ray source. Excellent image sensitivity is demonstrated in the observation of cancerous rabbit liver. The CT images distinguish cancer lesion from normal liver tissue and, moreover, visualize the pathological condition in the lesion. Although the X-ray energy employed and the present observation area size are not suitable for medical applications as they are, phase-contrast X-ray CT is promising for investigating the internal structure of soft tissue which is almost transparent for X-rays. The high sensitivity also provides the advantage of reducing X-ray doses. (author).

  4. Application of dual-energy scanning technique with dual-source CT in pulmonary mass lesions

    International Nuclear Information System (INIS)

    Jiang Jie; Xu Yiming; He Bo; Xie Xiaojie; Han Dan

    2012-01-01

    Objective: To explore the feasibility of DSCT dual-energy technique in pulmonary mass lesions. Methods: A total of 100 patients with pulmonary masses underwent conventional plain CT scan and dual-energy enhanced CT scan. The virtual non-contrast (VNC) images were obtained at post-processing workstation.The mean CT value,enhancement value,signal to noise ratio (SNR), image quality and radiation dose of pulmonary masses were compared between the two scan techniques using F or t test and the detectability of lesions was compared using Wilcoxon test. Results: There was no statistically significant difference among VNC (A) (32.89 ± 12.58) HU,VNC (S) (30.86 ± 9.60) HU and conventional plain images (35.89 ± 9.99) HU in mean CT value of mass (F =2.08, P>0.05). There was statistically significant difference among VNC (A) (3.29 ± 1.45), VNC (S) (3.93 ± 1.49) and conventional plain image (4.61 ± 1.50) in SNR (F =6.01, P<0.05), which of conventional plain scan was higher than that of VNC.The enhancement value of mass in conventional enhanced scan (60.74 ± 13.9) HU and distribution of iodine from VNC (A) (58.26 ± 31.99) HU was no statistically significant difference (t=0.48, P>0.05), but there was a significant difference between conventional enhanced scan (56.51 ± 17.94) HU and distribution of iodine from VNC (S) (52.65 ± 16.78) HU (t=4.45, P<0.05). There was no statistically significant difference among conventional plain scan (4.69 ± 0.06) and VNC (A) (4.60 ± 0.09), VNC (S) (4.61 ±0.11) in image quality at mediastinal window (F=3.014, P>0.05). The appearance, size, internal features of mass (such as necrosis, calcification and cavity) were showed the same in conventional plain scan, VNC (A) and VNC (S). Of 41 patients with hilar mass, 18 patients were found to have lobular and segmental perfusion decrease or defect. Perfusion defect area was found in 59 patients with peripheral lung mass. The radiation dose of dual-energy enhanced scan was lower than that of

  5. Pituitary gland and its stalk observed by high resolution CT

    International Nuclear Information System (INIS)

    Nakagawa, Yoshinobu; Fukami, Tsuneharu; Matsumoto, Keizo.

    1982-01-01

    It seemed to be important to recognize the CT findings of normal pituitary gland and the stalk for the acurate morphological diagnosis of pituitary microadenoma. In a consecutive series of normal 103 cases, the CT scans obtained by high resolution CT (CE-CT, Metrizamide CT) were analized and compared with 6 cases of microadenoma. The pituitary stalk demonstrated by the reconstructed coronal CT was examined and the inclination of the stalk was measured. The mean value of the inclination of pituitary stalk was 1.4 +- 1.7 0 in normal group and 9.3 +- 2.4 0 in microadenoma group. The form of the pituitary gland demonstrated by a reconstructed mid-saggital CT were classified into the following 3 types. Type I : The gland filling the whole pituitary fossa. Type II : The gland filled with small CSF space localized in the upper-anterior part in the pituitary fossa. Type III : The enlarged CSF space of more than half of the depth of pituitary fossa and the gland localized in the retro-lower part. As for the shape of pituitary gland, type I was revealed in 26 cases (7 cases in male and 19 cases in female), Type II was revealed in 31 cases (12 cases in male and 19 cases in female), Type III was revealed in 46 cases (25 cases in male and 21 cases in female). Type I was shown in female, especially in 10 years old young female. In 19 cases of 30 years to 40 years female, Type II was shown in 9 cases. In 44 male cases, Type I and Type II were shown in all ages. In the aged, Type III was shown in more than the other types. On the other hand, Type I was noted in 5 out of 6 cases of microadenoma group. (author)

  6. Detection of occult, undisplaced hip fractures with a dual-energy CT algorithm targeted to detection of bone marrow edema.

    Science.gov (United States)

    Reddy, T; McLaughlin, P D; Mallinson, P I; Reagan, A C; Munk, P L; Nicolaou, S; Ouellette, H A

    2015-02-01

    The purpose of this study is to describe our initial clinical experience with dual-energy computed tomography (DECT) virtual non-calcium (VNC) images for the detection of bone marrow (BM) edema in patients with suspected hip fracture following trauma. Twenty-five patients presented to the emergency department at a level 1 trauma center between January 1, 2011 and January 1, 2013 with clinical suspicion of hip fracture and normal radiographs were included. All CT scans were performed on a dual-source, dual-energy CT system. VNC images were generated using prototype software and were compared to regular bone reconstructions by two musculoskeletal radiologists in consensus. Radiological and/or clinical diagnosis of fracture at 30-day follow-up was used as the reference standard. Twenty-one patients were found to have DECT-VNC signs of bone marrow edema. Eighteen of these 21 patients were true positive and three were false positive. A concordant fracture was clearly seen on bone reconstruction images in 15 of the 18 true positive cases. In three cases, DECT-VNC was positive for bone marrow edema where bone reconstruction CT images were negative. Four patients demonstrated no DECT-VNC signs of bone marrow edema: two cases were true negative, two cases were false negative. When compared with the gold standard of hip fracture determined at retrospective follow-up, the sensitivity of DECT-VNC images of the hip was 90 %, specificity was 40 %, positive predictive value was 86 %, and negative predictive value was 50 %. Our initial experience would suggest that DECT-VNC is highly sensitive but poorly specific in the diagnosis of hip fractures in patients with normal radiographs. The value of DECT-VNC primarily lies in its ability to help detect fractures which may be subtle or undetectable on bone reconstruction CT images.

  7. Dual source CT imaging

    International Nuclear Information System (INIS)

    Seidensticker, Peter R.; Hofmann, Lars K.

    2008-01-01

    The introduction of Dual Source Computed Tomography (DSCT) in 2005 was an evolutionary leap in the field of CT imaging. Two x-ray sources operated simultaneously enable heart-rate independent temporal resolution and routine spiral dual energy imaging. The precise delivery of contrast media is a critical part of the contrast-enhanced CT procedure. This book provides an introduction to DSCT technology and to the basics of contrast media administration followed by 25 in-depth clinical scan and contrast media injection protocols. All were developed in consensus by selected physicians on the Dual Source CT Expert Panel. Each protocol is complemented by individual considerations, tricks and pitfalls, and by clinical examples from several of the world's best radiologists and cardiologists. This extensive CME-accredited manual is intended to help readers to achieve consistently high image quality, optimal patient care, and a solid starting point for the development of their own unique protocols. (orig.)

  8. TU-A-12A-12: Improved Airway Measurement Accuracy for Low Dose Quantitative CT (qCT) Using Statistical (ASIR), at Reduced DFOV, and High Resolution Kernels in a Phantom and Swine Model

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, G; Imai, Y; Hsieh, J

    2014-06-15

    Purpose: Quantitative accuracy of Iodine Hounsfield Unit (HU) in conventional single-kVp scanning is susceptible to beam-hardening effect. Dual-energy CT has unique capabilities of quantification using monochromatic CT images, but this scanning mode requires the availability of the state-of-the-art CT scanner and, therefore, is limited in routine clinical practice. Purpose of this work was to develop a beam-hardening-correction (BHC) for single-kVp CT that can linearize Iodine projections at any nominal energy, apply this approach to study Iodine response with respect to keV, and compare with dual-energy based monochromatic images obtained from material-decomposition using 80kVp and 140kVp. Methods: Tissue characterization phantoms (Gammex Inc.), containing solid-Iodine inserts of different concentrations, were scanned using GE multi-slice CT scanner at 80, 100, 120, and 140 kVp. A model-based BHC algorithm was developed where Iodine was estimated using re-projection of image volume and corrected through an iterative process. In the correction, the re-projected Iodine was linearized using a polynomial mapping between monochromatic path-lengths at various nominal energies (40 to 140 keV) and physically modeled polychromatic path-lengths. The beam-hardening-corrected 80kVp and 140kVp images (linearized approximately at effective energy of the beam) were used for dual-energy material-decomposition in Water-Iodine basis-pair followed by generation of monochromatic images. Characterization of Iodine HU and noise in the images obtained from singlekVp with BHC at various nominal keV, and corresponding dual-energy monochromatic images, was carried out. Results: Iodine HU vs. keV response from single-kVp with BHC and dual-energy monochromatic images were found to be very similar, indicating that single-kVp data may be used to create material specific monochromatic equivalent using modelbased projection linearization. Conclusion: This approach may enable quantification of

  9. Application of high resolution synchrotron micro-CT radiation in dental implant osseointegration.

    Science.gov (United States)

    Neldam, Camilla Albeck; Lauridsen, Torsten; Rack, Alexander; Lefolii, Tore Tranberg; Jørgensen, Niklas Rye; Feidenhans'l, Robert; Pinholt, Else Marie

    2015-06-01

    The purpose of this study was to describe a refined method using high-resolution synchrotron radiation microtomography (SRmicro-CT) to evaluate osseointegration and peri-implant bone volume fraction after titanium dental implant insertion. SRmicro-CT is considered gold standard evaluating bone microarchitecture. Its high resolution, high contrast, and excellent high signal-to-noise-ratio all contribute to the highest spatial resolutions achievable today. Using SRmicro-CT at a voxel size of 5 μm in an experimental goat mandible model, the peri-implant bone volume fraction was found to quickly increase to 50% as the radial distance from the implant surface increased, and levelled out to approximately 80% at a distance of 400 μm. This method has been successful in depicting the bone and cavities in three dimensions thereby enabling us to give a more precise answer to the fraction of the bone-to-implant contact compared to previous methods. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  10. Tensor-based Dictionary Learning for Spectral CT Reconstruction

    Science.gov (United States)

    Zhang, Yanbo; Wang, Ge

    2016-01-01

    Spectral computed tomography (CT) produces an energy-discriminative attenuation map of an object, extending a conventional image volume with a spectral dimension. In spectral CT, an image can be sparsely represented in each of multiple energy channels, and are highly correlated among energy channels. According to this characteristics, we propose a tensor-based dictionary learning method for spectral CT reconstruction. In our method, tensor patches are extracted from an image tensor, which is reconstructed using the filtered backprojection (FBP), to form a training dataset. With the Candecomp/Parafac decomposition, a tensor-based dictionary is trained, in which each atom is a rank-one tensor. Then, the trained dictionary is used to sparsely represent image tensor patches during an iterative reconstruction process, and the alternating minimization scheme is adapted for optimization. The effectiveness of our proposed method is validated with both numerically simulated and real preclinical mouse datasets. The results demonstrate that the proposed tensor-based method generally produces superior image quality, and leads to more accurate material decomposition than the currently popular popular methods. PMID:27541628

  11. Tensor-Based Dictionary Learning for Spectral CT Reconstruction.

    Science.gov (United States)

    Zhang, Yanbo; Mou, Xuanqin; Wang, Ge; Yu, Hengyong

    2017-01-01

    Spectral computed tomography (CT) produces an energy-discriminative attenuation map of an object, extending a conventional image volume with a spectral dimension. In spectral CT, an image can be sparsely represented in each of multiple energy channels, and are highly correlated among energy channels. According to this characteristics, we propose a tensor-based dictionary learning method for spectral CT reconstruction. In our method, tensor patches are extracted from an image tensor, which is reconstructed using the filtered backprojection (FBP), to form a training dataset. With the Candecomp/Parafac decomposition, a tensor-based dictionary is trained, in which each atom is a rank-one tensor. Then, the trained dictionary is used to sparsely represent image tensor patches during an iterative reconstruction process, and the alternating minimization scheme is adapted for optimization. The effectiveness of our proposed method is validated with both numerically simulated and real preclinical mouse datasets. The results demonstrate that the proposed tensor-based method generally produces superior image quality, and leads to more accurate material decomposition than the currently popular popular methods.

  12. CT-guided high-dose-rate brachytherapy of unresectable hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Collettini, Federico; Schreiber, Nadja; Schnapauff, Dirk; Denecke, Timm; Hamm, Bernd; Gebauer, Bernhard; Wust, Peter; Schott, Eckart

    2015-01-01

    The purpose of the present study was to evaluate the clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) in patients with unresectable hepatocellular carcinoma (HCC). Over a 6-year period, 98 patients with 212 unresectable HCC underwent CT-HDRBT applying a 192 Ir source at our institution. Magnetic resonance imaging (MRI) follow-up was performed 6 weeks after the intervention and then every 3 months. The primary endpoint was local tumor control (LTC); secondary endpoints included progression-free survival (PFS) and overall survival (OS). Patients were available for MRI evaluation for a mean follow-up of 23.1 months (range 4-64 months; median 20 months). Mean tumor diameter was 5 cm (range 1.8-12 cm). Eighteen of 212 (8.5 %) tumors showed local progression after a mean LTC of 21.1 months. In all, 67 patients (68.4 %) experienced distant tumor progression. The mean PFS was 15.2 months. Forty-six patients died during the follow-up period. Median OS was 29.2 months. Actuarial 1-, 2-, and 3-year OS rates were 80, 62, and 46 %, respectively. CT-HDRBT is an effective therapy to attain local tumor control in patients with unresectable HCC. Prospective randomized studies comparing CT-HDRBT with the standard treatments like Radiofrequency ablation (RFA) and chemoembolization (TACE) are mandatory. (orig.) [de

  13. High Dose MicroCT Does Not Contribute Toward Improved MicroPET/CT Image Quantitative Accuracy and Can Limit Longitudinal Scanning of Small Animals

    Directory of Open Access Journals (Sweden)

    Wendy A. McDougald

    2017-10-01

    Full Text Available Obtaining accurate quantitative measurements in preclinical Positron Emission Tomography/Computed Tomography (PET/CT imaging is of paramount importance in biomedical research and helps supporting efficient translation of preclinical results to the clinic. The purpose of this study was two-fold: (1 to investigate the effects of different CT acquisition protocols on PET/CT image quality and data quantification; and (2 to evaluate the absorbed dose associated with varying CT parameters.Methods: An air/water quality control CT phantom, tissue equivalent material phantom, an in-house 3D printed phantom and an image quality PET/CT phantom were imaged using a Mediso nanoPET/CT scanner. Collected data was analyzed using PMOD software, VivoQuant software and National Electric Manufactures Association (NEMA software implemented by Mediso. Measured Hounsfield Unit (HU in collected CT images were compared to the known HU values and image noise was quantified. PET recovery coefficients (RC, uniformity and quantitative bias were also measured.Results: Only less than 2 and 1% of CT acquisition protocols yielded water HU values < −80 and air HU values < −840, respectively. Four out of 11 CT protocols resulted in more than 100 mGy absorbed dose. Different CT protocols did not impact PET uniformity and RC, and resulted in <4% overall bias relative to expected radioactive concentration.Conclusion: Preclinical CT protocols with increased exposure times can result in high absorbed doses to the small animals. These should be avoided, as they do not contributed toward improved microPET/CT image quantitative accuracy and could limit longitudinal scanning of small animals.

  14. Comparison of the image quality between volumetric and conventional high-resolution CT with 64-slice row CT

    International Nuclear Information System (INIS)

    Gao Yanli; Zhang Lei; Zhao Xia; Ma Min; Zhai Renyou

    2008-01-01

    Objective: To compare the image quality between volumetric high-resolution CT (VHRCT) and conventional high-resolution CT (CHRCT), and investigate the feasibility of VHRCT. Methods: Catphan 412 phantom was scanned with protocols of CHRCT and VHRCT on a set of GE Lightspeed VCT. The spatial-resolution (LP/cm), noise (standard deviation in an ROI) and radiation close (CTDI) were recorded for each CT scan. Difference of noise between CHRCT and VHRCT were evaluated by paired t test. In clinical study, 32 patients were scanned with VHRCT and CHRCT protocols. The image quality of CHRCT and VHRCT was rated and compared. The quality difference between CHRCT and VHRCT was assessed by Wilcoxon paired signed rank sum test. Results: In phantom study, the in-plane spatial-resolution of both VHRCT and CHRCT was 11 LP/cm for axial images and 12 LP/cm for coronal reformatted images. The noise of VHRCT and CHRCT was (69.18±2.77)HU and (54.62±2.12) HU respectively (t=-15.929, P 0.05). The quality assessment scores of VHRCT coronal reformatted images and CHRCT coronal reformatted images were 3.05 and 1.88 respectively with significant difference (Z= -5.088, P<0.01). Conclusion: The image quality of VHRCT cross-sectional image is similar to that of CHRCT. Multiplanar images with high resolution of VHRCT are recommended. The radiation dose of VHRCT remains to be optimized. (authors)

  15. Tolosa-Hunt syndrome. A CT demonstration of a high-density lesion

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Kazuhiro; Muramoto, Masato; Chiba, Yasuhiro; Yagishita, Saburo

    1987-08-01

    CT scan studies of the Tolosa-Hunt syndrome have seldom been reported; positive abnormal findings are especially rare. A 36-year-old man suffered from steady, boring pain behind the left eye for one year. On admission he complained of diplopia on the right lateral gaze and hypesthesea of the first and second divisions of the left trigeminal nerve. A CT scan demonstrated a slightly high-density lesion, which was homogeneously enhanced, in the left cavernous portion and the superior orbital fissure. Carotid angiograms demonstrated no abnormal finding, and the cavernous sinus venography revealed no filling of the left cavernous sinus. A left front-temporal craniotomy was performed for the purpose of biopsy. A histological examination revealed non-specific focal granulomatous pachymeningitis. He responded dramatically to systemic steroid therapy, and he became pain-free by the fourth post-operative day. This diagnosis of the Tolosa-Hunt syndrome was confirmed both clinically and etiologically; however, the CT scan after the treatment demonstrated no definitive change in the lesion. The CT scan is useful for the diagnosis of this syndrome. Considering the stage of the illness, it is possible that the high-resolution CT scan can demonstrate this lesion with an advanced technique. The clinical diagnosis is almost easy, and surgical exploration is not always necessary if there is a prompt remission upon systemic steroid therapy. However, this syndrome should be differentiated from the other causes by appropriate examinations. Some cases similar to ours, especially suspected tumors, need surgical exploration because these angiographic findings are not specific.

  16. Making the invisible visible: improving conspicuity of noncalcified gallstones using dual-energy CT.

    Science.gov (United States)

    Uyeda, Jennifer W; Richardson, Ian J; Sodickson, Aaron D

    2017-12-01

    To determine whether virtual monochromatic imaging (VMI) increases detectability of noncalcified gallstones on dual-energy CT (DECT) compared with conventional CT imaging. This retrospective IRB-approved, HIPAA-compliant study included consecutive patients who underwent DECT of the abdomen in the Emergency Department during a 30-month period (July 1, 2013-December 31, 2015), with a comparison US or MR within 1-year. 51 patients (36F, 15M; mean age 52 years) fulfilled the inclusion criteria. All DECT were acquired on a dual-source 128 × 2 slice scanner using either 80/Sn140 or 100/Sn140 kVp pairs. Source images at high and low kVp were used for DE post-processing with VMI. Within 3 mm reconstructed images, regions of interest of 0.5 cm 2 were placed on noncalcified gallstones and bile to record hounsfield units (HU) at VMI energy levels ranging between 40 and 190 keV. Noncalcified gallstones uniformly demonstrated lowest HU at 40 keV and increase at higher keV; the HU of bile varied at higher keV. Few of the noncalcified stones are visible at 70 keV (simulating a conventional 120 kVp scan), with measured contrast (bile-stone HU difference) 20 HU in 2%. Contrast was maximal at 40 keV, where 100% demonstrated >20 HU difference from surrounding bile, 75% >44 HU difference, and 50% >60 HU difference. A paired t test demonstrated a significant difference (p < 0.0001) between this stone-bile contrast at 40 vs. 70 keV and 70 vs. 190 keV. Low keV virtual monochromatic imaging increased conspicuity of noncalcified gallstones, improving their detectability.

  17. Assessment of subpleural opacities on high-resolution CT

    International Nuclear Information System (INIS)

    Choi, Hee Seok; Kim, Jeung Sook; Kang, Eun Young; Kim, Hak Hee

    2007-01-01

    The purpose of this study was to assess the value of HRCT for determining the cause of subpleural opacities. We evaluated 49 cases of subpleural opacities on HRCT scan, among with the patients with subpleural opacities seen on the conventional chest radiographs. Two 'blinded' reviewers retrospectively analyzed the CT scans by working in consensus. The patients consisted of COP (n = 14), NSIP (n = 13), UIP (n = 10), fibrosis associated with connective tissue disease or drug toxicity (n = 4), CEP (n = 4), Churg-Strauss syndrome (n = 2), DIP (n = 1) and AIP (n = 1). The predominant findings were consolidation (57%) with a peribronchovascular distribution (57%) in the COP patients, GGO (69%) and the associated focal reticular densities (61%) in the NSIP patients, and reticular or reticulonodular densities with a paucity of GGO in the UIP patients (100%). For the diagnosis of COP, NSIP and UIP, the use of HRCT demonstrated a high sensitivity (86%, 85% and 90%, respectively), specificity (97%, 86% and 95%) and accuracy (94%, 86% and 94%). Although an overlap of CT findings is seen for diseases showing subpleural opacities, consolidation with a subpleural and peribronchovascular distribution is highly suggestive for COP, subpleural GGO is highly suggestive of NSIP, subpleural reticular or reticulonodular densities with a paucity of GGO is highly suggestive of UIP and subpleural consolidation accompanied by reticular densities is suggestive of fibrosis

  18. Assessment of subpleural opacities on high-resolution CT

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hee Seok; Kim, Jeung Sook [Dngguk University International Hospital, Goyang (Korea, Republic of); Kang, Eun Young [Korea University Guro Hospital, Seoul (Korea, Republic of); Kim, Hak Hee [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2007-11-15

    The purpose of this study was to assess the value of HRCT for determining the cause of subpleural opacities. We evaluated 49 cases of subpleural opacities on HRCT scan, among with the patients with subpleural opacities seen on the conventional chest radiographs. Two 'blinded' reviewers retrospectively analyzed the CT scans by working in consensus. The patients consisted of COP (n = 14), NSIP (n = 13), UIP (n = 10), fibrosis associated with connective tissue disease or drug toxicity (n = 4), CEP (n = 4), Churg-Strauss syndrome (n = 2), DIP (n = 1) and AIP (n = 1). The predominant findings were consolidation (57%) with a peribronchovascular distribution (57%) in the COP patients, GGO (69%) and the associated focal reticular densities (61%) in the NSIP patients, and reticular or reticulonodular densities with a paucity of GGO in the UIP patients (100%). For the diagnosis of COP, NSIP and UIP, the use of HRCT demonstrated a high sensitivity (86%, 85% and 90%, respectively), specificity (97%, 86% and 95%) and accuracy (94%, 86% and 94%). Although an overlap of CT findings is seen for diseases showing subpleural opacities, consolidation with a subpleural and peribronchovascular distribution is highly suggestive for COP, subpleural GGO is highly suggestive of NSIP, subpleural reticular or reticulonodular densities with a paucity of GGO is highly suggestive of UIP and subpleural consolidation accompanied by reticular densities is suggestive of fibrosis.

  19. Bolus timing in high-pitch CT angiography of the aorta

    International Nuclear Information System (INIS)

    Beeres, Martin; Loch, Matthias; Schulz, Boris; Kerl, Matthias; Al-Butmeh, Firas; Bodelle, Boris; Herrmann, Eva; Gruber-Rouh, Tatjana; Lee, Clara; Jacobi, Volkmar; Vogl, Thomas J.

    2013-01-01

    Objective: To investigate the bolus geometry in high-pitch CT angiography (CTA) of the aorta without ECG synchronisation in comparison to single-source CT. Methods: Overall 160 consecutive patients underwent CTA either in conventional single-source mode with a pitch of 1.2 (group 1), or in dual-source mode with a pitch of 3.0 (groups 2, 3 and 4) using different contrast media timings with bolus triggering at 140 HU (5 s, group 1; 10 s, group 2; 12 s, group 3; 14 s, group 4). Contrast material, saline flush, flow rate and kV/mAs settings were kept equal for optimum comparability. Aortic attenuation was measured along the z-axis of the patient at different anatomic landmarks and subjective image quality was compared. Results: The most homogeneous enhancement of the aorta was reached with a delay of 10 s after reaching the trigger threshold. The imaging length was not significantly different, but the examination time was significantly (p < 0.001) shorter in the high-pitch group (7.7 s vs. 1.7 s for group 1 vs. 2, 3 and 4). Conclusion: In high-pitch CT angiography using a start delay of 10 s after a trigger threshold of 140 HU in the descending aorta is reached, a homogenous contrast along the z-axis is accomplished

  20. Routine chest and abdominal high-pitch CT: An alternative low dose protocol with preserved image quality

    International Nuclear Information System (INIS)

    Amacker, Nadja A.; Mader, Caecilia; Alkadhi, Hatem; Leschka, Sebastian; Frauenfelder, Thomas

    2012-01-01

    Objective: To investigate the radiation dose and image quality of the high-pitch dual source computer tomography (DSCT) for routine chest and abdominal scans. Methods: 130 consecutive patients (62 female, 68 male, median age 55 years) were included. All patients underwent 128-slice high-pitch DSCT (chest n = 99; abdomen n = 84) at a pitch of 3.2. Two observers independently rated image quality using a 4-point score (1: excellent to 4: non-diagnostic). Image noise was measured and operational radiation dose quantities were recorded. An additional group of 132 patients (chest, n = 80; abdomen n = 52) scanned with standard-pitch CT matched for age, gender, and body mass index (BMI) served as control group. Results: Interobserver agreement for image quality rating was good (k = 0.74). Subjective image quality of high-pitch CT was diagnostic in all patients (median score chest; 2, median score abdomen: 2). Image noise of high-pitch CT was comparable to standard-pitch for the chest (p = 0.32) but increased in the abdomen (p < 0.0001). For high-pitch CT radiation dose was 4.4 ± 0.9 mSv (chest) and 6.5 ± 1.2 mSv (abdomen). These values were significantly lower compared to standard-pitch CT (chest: 5.5 ± 1.2 mSv; abdomen: 11.3 ± 3.8 mSv). Conclusion: Based on the technical background high-pitch dual source CT may serve as an alternative scan mode for low radiation dose routine chest and abdominal CT.

  1. High Flux Energy-Resolved Photon-Counting X-Ray Imaging Arrays with CdTe and CdZnTe for Clinical CT

    International Nuclear Information System (INIS)

    Barber, William C.; Hartsough, Neal E.; Gandhi, Thulasidharan; Iwanczyk, Jan S.; Wessel, Jan C.; Nygard, Einar; Malakhov, Nail; Wawrzyniak, Gregor; Dorholt, Ole; Danielsen, Roar

    2013-06-01

    We have fabricated fast room-temperature energy dispersive photon counting x-ray imaging arrays using pixellated cadmium zinc (CdTe) and cadmium zinc telluride (CdZnTe) semiconductors. We have also fabricated fast application specific integrated circuits (ASICs) with a two dimensional (2D) array of inputs for readout from the CdZnTe sensors. The new CdTe and CdZnTe sensors have a 2D array of pixels with a 0.5 mm pitch and can be tiled in 2D. The new 2D ASICs have four energy discriminators per pixel with a linear energy response across the entire dynamic range for clinical CT. The ASICs can also be tiled in 2D and are designed to fit within the active area of the 2D sensors. We have measured several important performance parameters including; an output count rate (OCR) in excess of 20 million counts per second per square mm, an energy resolution of 7 keV full width at half maximum (FWHM) across the entire dynamic range, and a noise floor less than 20 keV. This is achieved by directly interconnecting the ASIC inputs to the pixels of the CdTE and CdZnTe sensors incurring very little additional capacitance. We present a comparison of the performance of the CdTe and CdZnTe sensors including the OCR, FWHM energy resolution, and noise floor. (authors)

  2. High-pitch dual-source CT angiography of the whole aorta without ECG synchronisation: Initial experience

    International Nuclear Information System (INIS)

    Beeres, Martin; Schell, Boris; Mastragelopoulos, Aristidis; Kerl, Josef Matthias; Gruber-Rouh, Tatjana; Lee, Clara; Siebenhandl, Petra; Bodelle, Boris; Zangos, Stephan; Vogl, Thomas J.; Jacobi, Volkmar; Bauer, Ralf W.; Herrmann, Eva

    2012-01-01

    To investigate the feasibility, image quality and radiation dose for high-pitch dual-source CT angiography (CTA) of the whole aorta without ECG synchronisation. Each group of 40 patients underwent CTA either on a 16-slice (group 1) or dual-source CT device with conventional single-source (group 2) or high-pitch mode with a pitch of 3.0 (group 3). The presence of motion or stair-step artefacts of the thoracic aorta was independently assessed by two readers. Subjective and objective scoring of motion and artefacts were significantly reduced in the high-pitch examination protocol (p < 0.05). The imaging length was not significantly different, but the imaging time was significantly (p < 0.001) shorter in the high-pitch group (12.2 vs. 7.4 vs. 1.7 s for groups 1, 2 and 3). The ascending aorta and the coronary ostia were reliably evaluable in all patients of group 3 without motion artefacts as well. High-pitch dual-source CT angiography of the whole aorta is feasible in unselected patients. As a significant advantage over regular pitch protocols, motion-free imaging of the aorta is possible without ECG synchronisation. Thus, this CT mode bears potential to become a standard CT protocol before trans-catheter aortic valve implantation (TAVI). (orig.)

  3. Percutaneous CT-guided high-dose brachytherapy (CT-HDRBT) ablation of primary and metastatic lung tumors in nonsurgical candidates; Perkutane CT-gesteuerte Hochdosis-Brachytherapie (CT-HDRBT) von primaeren und metastatischen Lungentumoren in nicht chirurgischen Kandidaten

    Energy Technology Data Exchange (ETDEWEB)

    Collettini, F.; Schnapauff, D.; Poellinger, A.; Denecke, T.; Banzer, J.; Golenia, M.J.; Gebauer, B. [Charite - Universitatesmedizin Berlin (Germany). Inst. fuer Radiologie; Wust, P. [Charite - Universitatesmedizin Berlin (Germany). Klinik fuer Strahlentherapie

    2012-04-15

    To evaluate the safety and efficacy of CT-guided high-dose brachytherapy (CT-HDRBT) ablation of primary and metastatic lung tumors. Between November 2007 and May 2010, all consecutive patients with primary or metastatic lung tumors, unsuitable for surgery, were treated with CT-HDRBT. Imaging follow-up after treatment was performed with contrast-enhanced CT at 6 weeks, 3 months and every 6 months after the procedure. The endpoints of the study were local tumor control and time to progression. The Kaplan-Meier method was used to estimate survival functions and local tumor progression rates. 34 procedures were carried out on 33 lesions in 22 patients. The mean diameter of the tumors was 33.3 mm (SD = 20.4). The first contrast-enhanced CT showed that complete ablation was achieved in all lesions. The mean minimal tumor enclosing dose was 18.9 Gy (SD = 2). Three patients developed a pneumothorax after the procedure. The mean follow-up time was 13.7 (3 - 29) months. 2 of 32 lesions (6.25 %) developed a local tumor progression. 8 patients (36.3 %) developed a distant tumor progression. After 17.7 months, 13 patients were alive and 9 patients had died. CT-HDRBT ablation is a safe and attractive treatment option for patients with lung malignancies and allows targeted destruction of tumor tissue with simultaneous preservation of important lung structures. Furthermore, CT-HDRBT is independent of the size of the lesion and its location within the lung parenchyma. (orig.)

  4. Ex vivo validation of a stoichiometric dual energy CT proton stopping power ratio calibration

    Science.gov (United States)

    Xie, Yunhe; Ainsley, Christopher; Yin, Lingshu; Zou, Wei; McDonough, James; Solberg, Timothy D.; Lin, Alexander; Teo, Boon-Keng Kevin

    2018-03-01

    A major source of uncertainty in proton therapy is the conversion of Hounsfield unit (HU) to proton stopping power ratio relative to water (SPR). In this study, we measured and quantified the accuracy of a stoichiometric dual energy CT (DECT) SPR calibration. We applied a stoichiometric DECT calibration method to derive the SPR using CT images acquired sequentially at 80 kVp and 140 kVp . The dual energy index was derived based on the HUs of the paired spectral images and used to calculate the effective atomic number (Z eff), relative electron density ({{ρ }e} ), and SPRs of phantom and biological materials. Two methods were used to verify the derived SPRs. The first method measured the sample’s water equivalent thicknesses to deduce the SPRs using a multi-layer ion chamber (MLIC) device. The second method utilized Gafchromic EBT3 film to directly compare relative ranges between sample and water after proton pencil beam irradiation. Ex vivo validation was performed using five different types of frozen animal tissues with the MLIC and three types of fresh animal tissues using film. In addition, the residual ranges recorded on the film were used to compare with those from the treatment planning system using both DECT and SECT derived SPRs. Bland-Altman analysis indicates that the differences between DECT and SPR measurement of tissue surrogates, frozen and fresh animal tissues has a mean of 0.07% and standard deviation of 0.58% compared to 0.55% and 1.94% respectively for single energy CT (SECT) and SPR measurement. Our ex vivo study indicates that the stoichiometric DECT SPR calibration method has the potential to be more accurate than SECT calibration under ideal conditions although beam hardening effects and other image artifacts may increase this uncertainty.

  5. Precise fusion of MRI and dual energy 111In WBC/99mTc HDP SPECT/CT in the diabetic foot using companion CT: an example of SPECT/MRI imaging

    International Nuclear Information System (INIS)

    Knešaurek, K.; Heiba, S.; Kolker, D.; Vatti, S.

    2015-01-01

    The purpose of our study was to correctly fuse MRI and SPECT 111 In WBC and 99m Tc HDP images using companion CT images. The fused images could be used to assess proper surgical approach in treatment of the diabetic foot. Nine patients who had dual energy 111 In WBC/ 99 m Tc HDP SPECT/CT and MRI studies within a week were investigated in an ongoing project. A GE Infinia SPECT/CT camera and Siemens MAGNETOM 1.5T MR system were used in this study. First, the MRI and corresponding CT images were coregistrated using a transformation based on normalized mutual information. The transformation was saved and used for MRI and 111 In WBC/ 99 m Tc HDP SPECT fusion. A Jaszczak phantom study was also performed in order to estimate accuracy of MRI/ SPECT fusion. The Jaszczak phantom study with 3.7 MBq 111 In hot sphere showed that MRI/SPECT alignment using the approach described above produced registration with 0.7±0.4 mm accuracy in all three dimensions (3D). The nine clinical cases were visually evaluated and showed 1-2 mm 3D fusion accuracy. MRI provides almost perfect anatomy of soft tissue and bony structures but it may exaggerate the extent of infection. 111 In WBC/ 99 m Tc HDP SPECT imaging is more accurate for infection detection but lacks anatomical reference. Combination of these images proved an essential adjunct to diagnosis. A clinical utility of the approach is illustrated in two clinical examples. In conclusion, the CT in dual energy 111 In WBC/ 99 m Tc HDP SPECT/CT studies can be used to accurately fuse and compare 111 In WBC/ 99 m Tc HDP SPECT and MRI images of the diabetic foot. This can significantly help in conservative treatment planning and limb salvage procedures in treatment of diabetic foot infections.

  6. Illegal intra-corporeal packets: can dual energy CT be used for the evaluation of cocaine concentration? A cross sectional study

    International Nuclear Information System (INIS)

    Platon, Alexandra; Becker, Minerva; Becker, Christoph D.; Lock, Eric; Wolff, Hans; Perneger, Thomas; Poletti, Pierre-Alexandre

    2016-01-01

    The recent implementation of the dual energy technology on CT-scanners has opened new perspectives in tissue and material characterization. This study aims to evaluate whether dual energy CT can be used to assess the concentration of cocaine of intra-intestinal illegal packets. The study was approved by the institutional review board of our institution (CER 13-027-R). From November 2010 to May 2013, all consecutive conveyors in whom a low-dose abdominal CT (LDCT) revealed the presence of illegal intra-corporeal drug packets underwent a dual energy CT series (gemstone spectral imaging) targeted on one container. The mean radiological density (HU) of these packets was measured on the LDCT series, and on the monochromatic dual energy series, at 40 and 140 keV. The difference between the HU at 40 and 140 keV was reported as ∆HU. The effective atomic number Z(eff) was also measured on the monochromatic series. A chemical analysis was performed after expulsion to select cocaine containing packets, and to determine their cocaine concentrations. A correlation analysis was performed between HU, ∆HU and Z(eff), with regard to the percentage of cocaine. Fifty-four cocaine conveyors were included. The mean cocaine content of the packets was 36.8 % (range 11.2–80, SD 15.4), the mean radiologic density 105 HU, the mean Z(eff) 8.7 and the mean ∆HU 163. The cocaine content was correlated with the ∆HU (0.57, p < 0.001), with the Z(eff) (r = 0.56, p < 0.001) but not with radiologic density (r = 0.25, p = 0.064). ∆HU >200 was 0.9 (9 of 10) sensitive and 0.82 (36 of 44) specific to predict a cocaine concentration higher than 50 %. Measuring ∆HU or Z(eff) on dual energy monochromatic CT series can be used to detect ingested packets with cocaine concentration >50 %

  7. Clinical evaluation of dual-energy bone removal in CT angiography of the head and neck: comparison with conventional bone-subtraction CT angiography

    International Nuclear Information System (INIS)

    Deng, K.; Liu, C.; Ma, R.; Sun, C.; Wang, X.-M.; Ma, Z.-T.; Sun, X.-L.

    2009-01-01

    Aim: To evaluate the bone-subtraction effect of dual-energy bone removal in computed tomography angiography (CTA) of the head and neck in comparison with conventional bone-subtraction CTA. Material and Methods: The study comprised 52 patients who were divided into two groups at random, and examined using dual-source CT for head and neck CTA. Dual-energy bone removal CTA and conventional bone-subtraction CTA were applied to each of the two groups, respectively. The bone subtraction was performed automatically in both methods. Vascular structures, as well as brain tissue remained visible. The subtracted images were further processed with maximum intensity projection (MIP) and volume-rendering technique (VRT) for image evaluation. Two experienced radiologists reviewed the resulting subtracted and non-subtracted volume data with respect to the delineation and detection of image quality and vascular pathology. Results: The means of the weighted CT dose index (CTDIvol) for bone-removal dual-energy CTA and conventional bone-subtraction CTA were 20.56 ± 0.01 mGy and 25.57 ± 0.56 mGy, respectively. There was a significant difference between them. The percentage of carotid and vertebral arteries and all other vessels that could be successfully assessed with these two methods were 87.8, 68, and 83%, and 93.5, 91.8, and 92.6%, respectively. There were no significant differences in the visualization of the carotid arteries; however, there were significant differences in the visualization of the vertebral arteries. Conclusion: Compared with conventional bone-subtraction CTA, dual-energy bone-removal CTA had a lower radiation dose. It eliminated most bones in the head and neck successfully; however, the bone subtraction effect around the vertebral artery was unsatisfactory. Dual-energy bone-removal CTA provides a new method for detecting vascular diseases in routine clinical work.

  8. Dual energy spectral CT imaging for the evaluation of small hepatocellular carcinoma microvascular invasion.

    Science.gov (United States)

    Yang, Chuang-Bo; Zhang, Shuang; Jia, Yong-Jun; Yu, Yong; Duan, Hai-Feng; Zhang, Xi-Rong; Ma, Guang-Ming; Ren, Chenglong; Yu, Nan

    2017-10-01

    To study the clinical value of dual-energy spectral CT in the quantitative assessment of microvascular invasion of small hepatocellular carcinoma. This study was approved by our ethics committee. 50 patients with small hepatocellular carcinoma who underwent contrast enhanced spectral CT in arterial phase (AP) and portal venous phase (VP) were enrolled. Tumour CT value and iodine concentration (IC) were measured from spectral CT images. The slope of spectral curve, normalized iodine concentration (NIC, to abdominal aorta) and ratio of IC difference between AP and VP (RIC AP-VP : [RIC AP-VP =(IC AP -IC VP )/IC AP ]) were calculated. Tumours were identified as either with or without microvascular invasion based on pathological results. Measurements were statistically compared using independent samples t test. The receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of tumours microvascular invasion assessment. The 70keV images were used to simulate the results of conventional CT scans for comparison. 56 small hepatocellular carcinomas were detected with 37 lesions (Group A) with microvascular invasion and 19 (Group B) without. There were significant differences in IC, NIC and slope in AP and RIC AP-VP between Group A (2.48±0.70mg/ml, 0.23±0.05, 3.39±1.01 and 0.28±0.16) and Group B (1.65±0.47mg/ml, 0.15±0.05, 2.22±0.64 and 0.03±0.24) (all phepatocellular carcinoma with and without microvascular invasion. Quantitative iodine concentration measurement in spectral CT may be used to provide a new method to improve the evaluation for small hepatocellular carcinoma microvascular invasion. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. CT dose equilibration and energy absorption in polyethylene cylinders with diameters from 6 to 55 cm

    International Nuclear Information System (INIS)

    Li, Xinhua; Zhang, Da; Liu, Bob

    2015-01-01

    Purpose: ICRU Report No. 87 Committee and AAPM Task Group 200 designed a three-sectional polyethylene phantom of 30 cm in diameter and 60 cm in length for evaluating the midpoint dose D L (0) and its rise-to-the-equilibrium curve H(L) = D L (0)/D eq from computed tomography (CT) scanning, where D eq is the equilibrium dose. To aid the use of the phantom in radiation dose assessment and to gain an understanding of dose equilibration and energy absorption in polyethylene, the authors evaluated the short (20 cm) to long (60 cm) phantom dose ratio with a polyethylene diameter of 30 cm, assessed H(L) in polyethylene cylinders of 6–55 cm in diameters, and examined energy absorption in these cylinders. Methods: A GEANT4-based Monte Carlo program was used to simulate the single axial scans of polyethylene cylinders (diameters 6–55 cm and length 90 cm, as well as diameter 30 cm and lengths 20 and 60 cm) on a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare). Axial dose distributions were computed on the phantom central and peripheral axes. An average dose over the central 23 or 100 mm region was evaluated for modeling dose measurement using a 0.6 cm 3 thimble chamber or a 10 cm long pencil ion chamber, respectively. The short (20 cm) to long (90 cm) phantom dose ratios were calculated for the 30 cm diameter polyethylene phantoms scanned at four tube voltages (80–140 kV) and a range of beam apertures (1–25 cm). H(L) was evaluated using the dose integrals computed with the 90 cm long phantoms. The resultant H(L) data were subsequently used to compute the fraction of the total energy absorbed inside or outside the scan range (E in /E or E out /E) on the phantom central and peripheral axes, where E = LD eq was the total energy absorbed along the z axis. Results: The midpoint dose in the 60 cm long polyethylene phantom was equal to that in the 90 cm long polyethylene phantom. The short-to-long phantom dose ratios changed with beam aperture and

  10. CT dose equilibration and energy absorption in polyethylene cylinders with diameters from 6 to 55 cm

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu [Division of Diagnostic Imaging Physics and Webster Center for Advanced Research and Education in Radiation, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)

    2015-06-15

    Purpose: ICRU Report No. 87 Committee and AAPM Task Group 200 designed a three-sectional polyethylene phantom of 30 cm in diameter and 60 cm in length for evaluating the midpoint dose D{sub L}(0) and its rise-to-the-equilibrium curve H(L) = D{sub L}(0)/D{sub eq} from computed tomography (CT) scanning, where D{sub eq} is the equilibrium dose. To aid the use of the phantom in radiation dose assessment and to gain an understanding of dose equilibration and energy absorption in polyethylene, the authors evaluated the short (20 cm) to long (60 cm) phantom dose ratio with a polyethylene diameter of 30 cm, assessed H(L) in polyethylene cylinders of 6–55 cm in diameters, and examined energy absorption in these cylinders. Methods: A GEANT4-based Monte Carlo program was used to simulate the single axial scans of polyethylene cylinders (diameters 6–55 cm and length 90 cm, as well as diameter 30 cm and lengths 20 and 60 cm) on a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare). Axial dose distributions were computed on the phantom central and peripheral axes. An average dose over the central 23 or 100 mm region was evaluated for modeling dose measurement using a 0.6 cm{sup 3} thimble chamber or a 10 cm long pencil ion chamber, respectively. The short (20 cm) to long (90 cm) phantom dose ratios were calculated for the 30 cm diameter polyethylene phantoms scanned at four tube voltages (80–140 kV) and a range of beam apertures (1–25 cm). H(L) was evaluated using the dose integrals computed with the 90 cm long phantoms. The resultant H(L) data were subsequently used to compute the fraction of the total energy absorbed inside or outside the scan range (E{sub in}/E or E{sub out}/E) on the phantom central and peripheral axes, where E = LD{sub eq} was the total energy absorbed along the z axis. Results: The midpoint dose in the 60 cm long polyethylene phantom was equal to that in the 90 cm long polyethylene phantom. The short-to-long phantom dose

  11. Anatomy of the minor fissure: assessment with high-resolution CT and classification

    International Nuclear Information System (INIS)

    Ariyuerek, Macit O.; Yelgec, Selcuk N.; Guelsuen, Meltem; Karabulut, Nevzat

    2002-01-01

    The aims of this study were to investigate the anatomy of the minor fissure and its variations on high-resolution CT (HRCT) sections and to propose a detailed classification. The prospective study included 67 patients who were referred to CT for various indications. High-resolution CT examinations (1.5-mm collimation) were obtained through the region of the minor fissure. The CT scans were assessed for the presence, completeness, and configuration of the minor fissure. Various configurations of the minor fissure were classified into four major types, based on whether the highest portion of the middle lobe upper surface was medial (type I), lateral (type II), posterior (type III), or central (type IV). Minor fissure was identified in 65 (97%) of 67 patients, and absent in 2 (3%) cases. The fissure was incomplete in 35 (54%) of 65 patients. Type-I minor fissure is seen in 28 (43%) patients, type II in 22 (34%), type III in 5 (8%), and type IV in 2 (3%) patients. Because the majority of the fissure was absent in 8 (12%) of 35 patients with incomplete fissure, they were considered indeterminate. Comprehensive knowledge of the various configurations of the minor fissure is helpful in correct localization of a lesion and its extension. In equivocal cases, limited thin-section CT scans through the fissure delineate the anatomy more clearly and provide greater degree of precision in localizing pulmonary lesions. (orig.)

  12. Asbestosis and other pulmonary fibrosis in asbestos-exposed workers: high-resolution CT features with pathological correlations

    Energy Technology Data Exchange (ETDEWEB)

    Arakawa, Hiroaki [Dokkyo Medical University, Department of Radiology, Mibu, Tochigi (Japan); Kishimoto, Takumi [Okayama Rosai Hospital, Asbestos Research Center, Okayama (Japan); Ashizawa, Kazuto [Nagasaki University Graduate School of Biomedical Sciences, Department of Clinical Oncology, Nagasaki (Japan); Kato, Katsuya [Kawasaki Medical School, Department of Diagnostic Radiology 2, Okayama (Japan); Okamoto, Kenzo [Hokkaido Chuo Hospital, Department of Pathology, Iwamizawa, Hokkaido (Japan); Honma, Koichi [Dokkyo Medical University, Department of Pathology, Mibu, Tochigi (Japan); Hayashi, Seiji [National Hospital Organization Kinki-Chuo Chest Medical Center, Osaka (Japan); Akira, Masanori [National Hospital Organization Kinki-Chuo Chest Medical Center, Department of Radiology, Osaka (Japan)

    2016-05-15

    The purpose was to identify distinguishing CT features of pathologically diagnosed asbestosis, and correlate diagnostic confidence with asbestos body burden. Thirty-three workers (mean age at CT: 73 years) with clinical diagnoses of asbestosis, who were autopsied (n = 30) or underwent lobectomy (n = 3), were collected. Two radiologists independently scored high-resolution CT images for various CT findings and the likelihood of asbestosis was scored. Two pathologists reviewed the pathology specimens and scored the confidence of their diagnoses. Asbestos body count was correlated with CT and pathology scores. Pathologically, 15 cases were diagnosed as asbestosis and 18 cases with various lung fibroses other than asbestosis. On CT, only the score of the subpleural curvilinear lines was significantly higher in asbestosis (p = 0.03). Accuracy of CT diagnosis of asbestosis with a high confidence ranged from 0.73 to 0.79. Asbestos body count positively correlated with CT likelihood of asbestosis (r = 0.503, p = 0.003), and with the confidence level of pathological diagnosis (r = 0.637, p < 0.001). Subpleural curvilinear lines were the only clue for the diagnosis of asbestosis. However, this was complicated by other lung fibrosis, especially at low asbestos body burden. (orig.)

  13. On the feasibility of polyurethane based 3D dosimeters with optical CT for dosimetric verification of low energy photon brachytherapy seeds

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, Justus, E-mail: justus.adamson@duke.edu; Yang, Yun; Juang, Titania; Chisholm, Kelsey; Rankine, Leith; Yin, Fang Fang; Oldham, Mark [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Adamovics, John [Department of Chemistry, Rider University, Lawrenceville, New Jersey 08648 (United States)

    2014-07-15

    relatively stable within the first 5 cm especially for I-125. The inherent assumption of radial symmetry in the TG43 geometry leads to a linear increase in sample points within the 3D dosimeter as a function of distance away from the source, which partially offsets the decreasing signal. Simulations of dose reconstruction using optical CT showed the feasibility of reconstructing dose out to a radius of 10 cm without saturating projection images using an optimal dose and high dynamic range scanning; the simulations also predicted that reconstruction artifacts at the channel surface due to a small discrepancy in refractive index should be negligible. Agreement of the measured with calculated radial dose function for I-125 was within 5% between 0.3 and 2.5 cm from the source, and the median difference of measured from calculated anisotropy function was within 5% between 0.3 and 2.0 cm from the source. Conclusions: 3D dosimetry using polyurethane dosimeters with optical CT looks to be a promising application to verify dosimetric distributions surrounding low energy brachytherapy sources.

  14. Bronchiolitis obliterans in children with Stevens-Johnson syndrome: follow-up with high resolution CT

    International Nuclear Information System (INIS)

    Kim, M.J.; Lee, K.Y.

    1996-01-01

    About one third of children with Stevens-Johnson syndrome have pulmonary involvement. As a consequence of airway epithelial injury, bronchiolitis obliterans can occur in these patients. Two cases of Stevens-Johnson syndrome-associated bronchiolitis obliterans in children were diagnosed and followed by high resolution CT without open lung biopsy. Serial changes of high resolution CT features of bronchiolitis obliterans are discussed and the literature is reviewed. (orig.)

  15. New horizons with PET/CT in high-tech radiotherapy planning

    International Nuclear Information System (INIS)

    Hadjieva, T.

    2009-01-01

    Full text:The precise delineation of exposed volumes in the high-tech radiotherapy is a major problem. The malignoma imaging was revolutionized by PET. PET became one of the routine imaging methods in developed countries in Europe and USA. PET with 18-FDG, combined with structural and topographic representation of images by CT, currently provides the most reliable information about the location and spread of tumor. Three dimensional radiotherapy planning is a challenge in today's practice and requires the most accurate visualization of the tumor, with its functional characteristics (proliferation activity, hypoxic cells, apoptosis, neoangiogenesis) and surrounding radiosensitive normal tissue and organs. The collected information about the main indications for radiotherapy planning using PET / CT in head and neck cancers , small cell lung carcinoma and some malignant lymphomas has been discussed. The problem of false positive and false negative findings has been also considered. The protocol for 18-FDG PET / CT conducting according to the agreed consensus of the IAEA expert meeting held in 2006 is presented

  16. Dual-energy CT for the characterization of urinary calculi: In vitro and in vivo evaluation of a low-dose scanning protocol

    International Nuclear Information System (INIS)

    Thomas, C.; Patschan, O.; Nagele, U.; Stenzl, A.; Ketelsen, D.; Tsiflikas, I.; Reimann, A.; Brodoefel, H.; Claussen, C.; Kopp, A.; Heuschmid, M.; Schlemmer, H.P.; Buchgeister, M.

    2009-01-01

    The efficiency and radiation dose of a low-dose dual-energy (DE) CT protocol for the evaluation of urinary calculus disease were evaluated. A low-dose dual-source DE-CT renal calculi protocol (140 kV, 46 mAs; 80 kV, 210 mAs) was derived from the single-energy (SE) CT protocol used in our institution for the detection of renal calculi (120 kV, 75 mAs). An Alderson-Rando phantom was equipped with thermoluminescence dosimeters and examined by CT with both protocols. The effective doses were calculated. Fifty-one patients with suspected or known urinary calculus disease underwent DE-CT. DE analysis was performed if calculi were detected using a dedicated software tool. Results were compared to chemical analysis after invasive calculus extraction. An effective dose of 3.43 mSv (male) and 5.30 mSv (female) was measured in the phantom for the DE protocol (vs. 3.17/4.57 mSv for the SE protocol). Urinary calculi were found in 34 patients; in 28 patients, calculi were removed and analyzed (23 patients with calcified calculi, three with uric acid calculi, one with 2,8-dihyxdroxyadenine-calculi, one patient with a mixed struvite calculus). DE analysis was able to distinguish between calcified and non-calcified calculi in all cases. In conclusion, dual-energy urinary calculus analysis is effective also with a low-dose protocol. The protocol tested in this study reliably identified calcified urinary calculi in vivo. (orig.)

  17. Dual-energy CT for the characterization of urinary calculi: In vitro and in vivo evaluation of a low-dose scanning protocol.

    Science.gov (United States)

    Thomas, C; Patschan, O; Ketelsen, D; Tsiflikas, I; Reimann, A; Brodoefel, H; Buchgeister, M; Nagele, U; Stenzl, A; Claussen, C; Kopp, A; Heuschmid, M; Schlemmer, H-P

    2009-06-01

    The efficiency and radiation dose of a low-dose dual-energy (DE) CT protocol for the evaluation of urinary calculus disease were evaluated. A low-dose dual-source DE-CT renal calculi protocol (140 kV, 46 mAs; 80 kV, 210 mAs) was derived from the single-energy (SE) CT protocol used in our institution for the detection of renal calculi (120 kV, 75 mAs). An Alderson-Rando phantom was equipped with thermoluminescence dosimeters and examined by CT with both protocols. The effective doses were calculated. Fifty-one patients with suspected or known urinary calculus disease underwent DE-CT. DE analysis was performed if calculi were detected using a dedicated software tool. Results were compared to chemical analysis after invasive calculus extraction. An effective dose of 3.43 mSv (male) and 5.30 mSv (female) was measured in the phantom for the DE protocol (vs. 3.17/4.57 mSv for the SE protocol). Urinary calculi were found in 34 patients; in 28 patients, calculi were removed and analyzed (23 patients with calcified calculi, three with uric acid calculi, one with 2,8-dihyxdroxyadenine-calculi, one patient with a mixed struvite calculus). DE analysis was able to distinguish between calcified and non-calcified calculi in all cases. In conclusion, dual-energy urinary calculus analysis is effective also with a low-dose protocol. The protocol tested in this study reliably identified calcified urinary calculi in vivo.

  18. Dual-energy CT for the characterization of urinary calculi: In vitro and in vivo evaluation of a low-dose scanning protocol

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, C. [University of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Patschan, O.; Nagele, U.; Stenzl, A. [University of Tuebingen, Department of Urology, Tuebingen (Germany); Ketelsen, D.; Tsiflikas, I.; Reimann, A.; Brodoefel, H.; Claussen, C.; Kopp, A.; Heuschmid, M.; Schlemmer, H.P. [University of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Buchgeister, M. [University of Tuebingen, Medical Physics, Department of Radiation Oncology, Tuebingen (Germany)

    2009-06-15

    The efficiency and radiation dose of a low-dose dual-energy (DE) CT protocol for the evaluation of urinary calculus disease were evaluated. A low-dose dual-source DE-CT renal calculi protocol (140 kV, 46 mAs; 80 kV, 210 mAs) was derived from the single-energy (SE) CT protocol used in our institution for the detection of renal calculi (120 kV, 75 mAs). An Alderson-Rando phantom was equipped with thermoluminescence dosimeters and examined by CT with both protocols. The effective doses were calculated. Fifty-one patients with suspected or known urinary calculus disease underwent DE-CT. DE analysis was performed if calculi were detected using a dedicated software tool. Results were compared to chemical analysis after invasive calculus extraction. An effective dose of 3.43 mSv (male) and 5.30 mSv (female) was measured in the phantom for the DE protocol (vs. 3.17/4.57 mSv for the SE protocol). Urinary calculi were found in 34 patients; in 28 patients, calculi were removed and analyzed (23 patients with calcified calculi, three with uric acid calculi, one with 2,8-dihyxdroxyadenine-calculi, one patient with a mixed struvite calculus). DE analysis was able to distinguish between calcified and non-calcified calculi in all cases. In conclusion, dual-energy urinary calculus analysis is effective also with a low-dose protocol. The protocol tested in this study reliably identified calcified urinary calculi in vivo. (orig.)

  19. Development of high speed and reliable data transmission system for industrial CT

    International Nuclear Information System (INIS)

    Gao Fuqiang; Dong Yanli; Liu Guohua

    2010-01-01

    In order to meet the requirements of large capacity,high speed and high reliability of data transmission for industrial CT, a data transmission system based on USB 2.0 was designed. In the process of data transmission, FPGA was the main controller, and USB 2.0 CY7C68013A worked in slave FIFO mode. The system sent the data got from data acquisition system to host computer for image reconstruction. The testing results show that the transmission rate can reach 33 MB/s and the precision is 100%. The system satisfies the requirements of data transmission for industrial CT. (authors)

  20. Diagnostic accuracy of dual energy CT angiography in patients with diabetes mellitus

    International Nuclear Information System (INIS)

    Schabel, C.; Bongers, M.N.; Syha, R.; Ketelsen, D.; Homann, G.; Notohamiprodjo, M.; Nikolaou, K.; Bamberg, F.; Thomas, C.

    2015-01-01

    Peripheral arterial disease (PAD) represents a major and highly prevalent complication in patients with diabetes mellitus. The diagnostic, non-invasive work-up by computed tomography angiography (CTA) is limited in the presence of extensive calcification. The aim of the study was to determine the diagnostic accuracy of dual energy CTA (DE-CTA) for the detection and characterization of PAD in patients with diabetes mellitus. In this study 30 diabetic patients with suspected or known PAD were retrospectively included in the analysis. All subjects underwent DE-CTA (Somatom Definition Flash, Siemens Healthcare, Erlangen, Germany) prior to invasive angiography, which served as the reference standard. Blinded analysis included assessment of the presence and degree of peripheral stenosis on curved multiplanar reformatting (MPR) and maximum intensity projections (MIP). Conventional measures of diagnostic accuracy were derived. Among the 30 subjects included in the analysis (83 % male, mean age 70.0 ± 10.5 years, 83 % diabetes type 2), the prevalence of critical stenosis in 331 evaluated vessel segments was high (30 %). Dual energy CT identified critical stenoses with a high sensitivity and good specificity using curved MPR (100 % and 93.1 %, respectively) and MIP images (99 % and 91.8 %, respectively). In stratified analysis, the diagnostic accuracy was higher for stenosis pertaining to the pelvic and thigh vessels as compared with the lower extremities (curved MPR accuracy 97.1 % vs. 99.2 vs. 90.9 %; respectively, p < 0.001). The use of DE-CTA allows reliable detection and characterization of peripheral arterial stenosis in patients with diabetes mellitus with higher accuracy in vessels in the pelvic and thigh regions compared with the vessels in the lower legs. (orig.) [de

  1. Performance evaluation of the General Electric eXplore CT 120 micro-CT using the vmCT phantom

    Energy Technology Data Exchange (ETDEWEB)

    Bahri, M.A., E-mail: M.Bahri@ulg.ac.be [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); Warnock, G.; Plenevaux, A. [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); Choquet, P.; Constantinesco, A. [Biophysique et Medecine Nucleaire, Hopitaux universitaires de Strasbourg, Strasbourg (France); Salmon, E.; Luxen, A. [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); Seret, A. [ULg-Liege University, Cyclotron Research Centre, Liege, Bat. 30, Allee du 6 aout, 8 (Belgium); ULg-Liege University, Experimental Medical Imaging, Liege (Belgium)

    2011-08-21

    The eXplore CT 120 is the latest generation micro-CT from General Electric. It is equipped with a high-power tube and a flat-panel detector. It allows high resolution and high contrast fast CT scanning of small animals. The aim of this study was to compare the performance of the eXplore CT 120 with that of the eXplore Ultra, its predecessor for which the methodology using the vmCT phantom has already been described . The phantom was imaged using typical a rat (fast scan or F) or mouse (in vivo bone scan or H) scanning protocols. With the slanted edge method, a 10% modulation transfer function (MTF) was observed at 4.4 (F) and 3.9-4.4 (H) mm{sup -1} corresponding to 114 {mu}m resolution. A fairly larger MTF was obtained by the coil method with the MTF for the thinnest coil (3.3 mm{sup -1}) equal to 0.32 (F) and 0.34 (H). The geometric accuracy was better than 0.3%. There was a highly linear (R{sup 2}>0.999) relationship between measured and expected CT numbers for both the CT number accuracy and linearity sections of the phantom. A cupping effect was clearly seen on the uniform slices and the uniformity-to-noise ratio ranged from 0.52 (F) to 0.89 (H). The air CT number depended on the amount of polycarbonate surrounding the area where it was measured; a difference as high as approximately 200 HU was observed. This hindered the calibration of this scanner in HU. This is likely due to the absence of corrections for beam hardening and scatter in the reconstruction software. However in view of the high linearity of the system, the implementation of these corrections would allow a good quality calibration of the scanner in HU. In conclusion, the eXplore CT 120 achieved a better spatial resolution than the eXplore Ultra (based on previously reported specifications) and future software developments will include beam hardening and scatter corrections that will make the new generation CT scanner even more promising.

  2. Dual-energy CT-cholangiography in potential donors for living-related liver transplantation: Improved biliary visualization by intravenous morphine co-medication

    International Nuclear Information System (INIS)

    Sommer, C.M.; Schwarzwaelder, C.B.; Stiller, W.; Schindera, S.T.; Heye, T.; Stampfl, U.; Bellemann, N.; Holzschuh, M.; Schmidt, J.; Weitz, J.; Grenacher, L.; Kauczor, H.U.; Radeleff, B.A.

    2012-01-01

    Purpose: To prospectively evaluate whether intravenous morphine co-medication improves bile duct visualization of dual-energy CT-cholangiography. Materials and methods: Forty potential donors for living-related liver transplantation underwent CT-cholangiography with infusion of a hepatobiliary contrast agent over 40 min. Twenty minutes after the beginning of the contrast agent infusion, either normal saline (n = 20 patients; control group [CG]) or morphine sulfate (n = 20 patients; morphine group [MG]) was injected. Forty-five minutes after initiation of the contrast agent, a dual-energy CT acquisition of the liver was performed. Applying dual-energy post-processing, pure iodine images were generated. Primary study goals were determination of bile duct diameters and visualization scores (on a scale of 0 to 3: 0—not visualized; 3—excellent visualization). Results: Bile duct visualization scores for second-order and third-order branch ducts were significantly higher in the MG compared to the CG (2.9 ± 0.1 versus 2.6 ± 0.2 [P < 0.001] and 2.7 ± 0.3 versus 2.1 ± 0.6 [P < 0.01], respectively). Bile duct diameters for the common duct and main ducts were significantly higher in the MG compared to the CG (5.9 ± 1.3 mm versus 4.9 ± 1.3 mm [P < 0.05] and 3.7 ± 1.3 mm versus 2.6 ± 0.5 mm [P < 0.01], respectively). Conclusion: Intravenous morphine co-medication significantly improved biliary visualization on dual-energy CT-cholangiography in potential donors for living-related liver transplantation

  3. Dual-energy CT-cholangiography in potential donors for living-related liver transplantation: Improved biliary visualization by intravenous morphine co-medication

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, C.M., E-mail: christof.sommer@med.uni-heidelberg.de [Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg (Germany); Schwarzwaelder, C.B.; Stiller, W. [Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg (Germany); Schindera, S.T. [Department of Diagnostic, Interventional, and Pediatric Radiology, University Hospital and University of Berne, Berne (Switzerland); Heye, T.; Stampfl, U.; Bellemann, N.; Holzschuh, M. [Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg (Germany); Schmidt, J.; Weitz, J. [Department of General, Abdominal and Transplantation Surgery, University Hospital Heidelberg, Heidelberg (Germany); Grenacher, L.; Kauczor, H.U.; Radeleff, B.A. [Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg (Germany)

    2012-09-15

    Purpose: To prospectively evaluate whether intravenous morphine co-medication improves bile duct visualization of dual-energy CT-cholangiography. Materials and methods: Forty potential donors for living-related liver transplantation underwent CT-cholangiography with infusion of a hepatobiliary contrast agent over 40 min. Twenty minutes after the beginning of the contrast agent infusion, either normal saline (n = 20 patients; control group [CG]) or morphine sulfate (n = 20 patients; morphine group [MG]) was injected. Forty-five minutes after initiation of the contrast agent, a dual-energy CT acquisition of the liver was performed. Applying dual-energy post-processing, pure iodine images were generated. Primary study goals were determination of bile duct diameters and visualization scores (on a scale of 0 to 3: 0—not visualized; 3—excellent visualization). Results: Bile duct visualization scores for second-order and third-order branch ducts were significantly higher in the MG compared to the CG (2.9 ± 0.1 versus 2.6 ± 0.2 [P < 0.001] and 2.7 ± 0.3 versus 2.1 ± 0.6 [P < 0.01], respectively). Bile duct diameters for the common duct and main ducts were significantly higher in the MG compared to the CG (5.9 ± 1.3 mm versus 4.9 ± 1.3 mm [P < 0.05] and 3.7 ± 1.3 mm versus 2.6 ± 0.5 mm [P < 0.01], respectively). Conclusion: Intravenous morphine co-medication significantly improved biliary visualization on dual-energy CT-cholangiography in potential donors for living-related liver transplantation.

  4. The role of dual energy CT in differentiating between brain haemorrhage and contrast medium after mechanical revascularisation in acute ischaemic stroke

    International Nuclear Information System (INIS)

    Tijssen, M.P.M.; Stadler, A.A.R.; Zwam, W. van; Graaf, R. de; Postma, A.A.; Hofman, P.A.M.; Oostenbrugge, R.J. van; Klotz, E.; Wildberger, J.E.

    2014-01-01

    To assess the feasibility of dual energy computed tomography (DE-CT) in intra-arterially treated acute ischaemic stroke patients to discriminate between contrast extravasation and intracerebral haemorrhage. Thirty consecutive acute ischaemic stroke patients following intra-arterial treatment were examined with DE-CT. Simultaneous imaging at 80 kV and 140 kV was employed with calculation of mixed images. Virtual unenhanced non-contrast (VNC) images and iodine overlay maps (IOM) were calculated using a dedicated brain haemorrhage algorithm. Mixed images alone, as ''conventional CT'', and DE-CT interpretations were evaluated and compared with follow-up CT. Eight patients were excluded owing to a lack of follow-up or loss of data. Mixed images showed intracerebral hyperdense areas in 19/22 patients. Both haemorrhage and residual contrast material were present in 1/22. IOM suggested contrast extravasation in 18/22 patients; in 16/18 patients this was confirmed at follow-up. The positive predictive value (PPV) of mixed imaging alone was 25 %, with a negative predictive value (NPV) of 91 % and accuracy of 63 %. The PPV for detection of haemorrhage with DE-CT was 100 %, with an NPV of 89 % and accuracy improved to 89 %. Dual energy computed tomography improves accuracy and diagnostic confidence in early differentiation between intracranial haemorrhage and contrast medium extravasation in acute stroke patients following intra-arterial revascularisation. (orig.)

  5. The role of dual energy CT in differentiating between brain haemorrhage and contrast medium after mechanical revascularisation in acute ischaemic stroke

    Energy Technology Data Exchange (ETDEWEB)

    Tijssen, M.P.M.; Stadler, A.A.R.; Zwam, W. van; Graaf, R. de; Postma, A.A. [Maastricht University Medical Centre, Department of Radiology, P.O. Box 5800, Maastricht (Netherlands); Hofman, P.A.M. [Maastricht University Medical Centre, Department of Radiology, P.O. Box 5800, Maastricht (Netherlands); Maastricht University, MhENS School for Mental Health and Neuroscience, Maastricht (Netherlands); Oostenbrugge, R.J. van [Maastricht University Medical Centre, Department of Neurology, P.O. Box 5800, Maastricht (Netherlands); Maastricht University, CARIM School for Cardiovascular Diseases, P.O. Box 616, Maastricht (Netherlands); Klotz, E. [Siemens Healthcare Sector, Computed Tomography, Forchheim (Germany); Wildberger, J.E. [Maastricht University Medical Centre, Department of Radiology, P.O. Box 5800, Maastricht (Netherlands); Maastricht University, CARIM School for Cardiovascular Diseases, P.O. Box 616, Maastricht (Netherlands)

    2014-04-15

    To assess the feasibility of dual energy computed tomography (DE-CT) in intra-arterially treated acute ischaemic stroke patients to discriminate between contrast extravasation and intracerebral haemorrhage. Thirty consecutive acute ischaemic stroke patients following intra-arterial treatment were examined with DE-CT. Simultaneous imaging at 80 kV and 140 kV was employed with calculation of mixed images. Virtual unenhanced non-contrast (VNC) images and iodine overlay maps (IOM) were calculated using a dedicated brain haemorrhage algorithm. Mixed images alone, as ''conventional CT'', and DE-CT interpretations were evaluated and compared with follow-up CT. Eight patients were excluded owing to a lack of follow-up or loss of data. Mixed images showed intracerebral hyperdense areas in 19/22 patients. Both haemorrhage and residual contrast material were present in 1/22. IOM suggested contrast extravasation in 18/22 patients; in 16/18 patients this was confirmed at follow-up. The positive predictive value (PPV) of mixed imaging alone was 25 %, with a negative predictive value (NPV) of 91 % and accuracy of 63 %. The PPV for detection of haemorrhage with DE-CT was 100 %, with an NPV of 89 % and accuracy improved to 89 %. Dual energy computed tomography improves accuracy and diagnostic confidence in early differentiation between intracranial haemorrhage and contrast medium extravasation in acute stroke patients following intra-arterial revascularisation. (orig.)

  6. Redistributed Regional Ventilation after the Administration of a Bronchodilator Demonstrated on Xenon-Inhaled Dual-Energy CT in a Patient with Asthma

    International Nuclear Information System (INIS)

    Goo, Hyun Woo; Yu, Jin Ho

    2011-01-01

    We report here on the redistributed regional ventilation abnormalities after the administration of a bronchodilator and as seen on xenon-inhaled dual-energy CT in a patient with asthma. The improved ventilation seen in the right lower lobe and the decreased ventilation seen in the right middle lobe after the administration of a bronchodilator on xenon-inhaled dual-energy CT could explain a positive bronchodilator response on a pulmonary function test. These changes may reflect the heterogeneity of the airway responsiveness to a bronchodilator in patients with asthma.

  7. Redistributed Regional Ventilation after the Administration of a Bronchodilator Demonstrated on Xenon-Inhaled Dual-Energy CT in a Patient with Asthma

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo; Yu, Jin Ho [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2011-06-15

    We report here on the redistributed regional ventilation abnormalities after the administration of a bronchodilator and as seen on xenon-inhaled dual-energy CT in a patient with asthma. The improved ventilation seen in the right lower lobe and the decreased ventilation seen in the right middle lobe after the administration of a bronchodilator on xenon-inhaled dual-energy CT could explain a positive bronchodilator response on a pulmonary function test. These changes may reflect the heterogeneity of the airway responsiveness to a bronchodilator in patients with asthma.

  8. Lymphocytic interstitial pneumonia in children with AIDS: high-resolution CT findings

    International Nuclear Information System (INIS)

    Becciolini, V.; Gudinchet, F.; Schnyder, P.; Cheseaux, J.J.

    2001-01-01

    Pulmonary involvement in children with acquired immunodeficiency syndrome (AIDS) represents a wide spectrum of diseases. Among the non-infectious, non-neoplastic affections associated with AIDS, lymphocytic interstitial pneumonia (LIP) is now a well-recognized entity, but its radiological pattern studied with high-resolution computed tomography (HRCT) has rarely been described in children. The aim of this study was to illustrate the HRCT spectrum of pulmonary involvement in children with LIP and to evaluate its usefulness in the early diagnosis of this entity. Twelve children with AIDS, aged 3-9 years (mean age 5 years 7 months), underwent chest radiographs and HRCT. A control group of 7 healthy aged-matched children was also studied in the same conditions. Diagnosis of LIP was based on clinical data and HRCT findings. Eight children of 12 had a reticulonodular pattern on chest radiographs. Two children had normal chest films and two children showed peribronchiolar thickening. High-resolution CT displayed micronodules, 1-3 mm in diameter, with a perilymphatic distribution in all patients. High-resolution CT demonstrated also subpleural nodules in children without reticulonodular opacities on chest radiographs. High-resolution CT is able to define a more specific pattern of abnormalities than conventional chest radiographs in children with LIP, allows an earlier and more confident diagnosis and may be useful for the detection of other pathologies associated with AIDS, such as opportunistic infections or superimposed malignancies. (orig.)

  9. Helical CT in the primary trauma evaluation of the cervical spine: an evidence-based approach

    Energy Technology Data Exchange (ETDEWEB)

    Blackmore, C.C. [Washington Univ., Seattle, WA (United States). Dept. of Radiology; Center for Cost and Outcomes Research, Univ. of Washington, Seattle (United States); Dept. of Radiology, Harborview Medical Center, Seattle, WA (United States); Mann, F.A. [Washington Univ., Seattle, WA (United States). Dept. of Radiology; Harborview Injury Prevention and Research Center, University of Washington, Seattle (United States); Wilson, A.J. [Washington Univ., Seattle, WA (United States). Dept. of Radiology

    2000-11-01

    This review provides a summary of the cost-effectiveness, clinical utility, performance, and interpretation of screening helical cervical spine CT for trauma patients. Recent evidence supports the use of helical CT as a cost-effective method for screening the cervical spine in high-risk trauma patients. Screening cervical spine CT can be performed at the time of head CT to lower the cost of the evaluation, and when all short- and long-term costs are considered, CT may actually save money when compared with traditional radiographic screening. In addition to having higher sensitivity and specificity for cervical spine injury, CT screening also allows more rapid radiological clearance of the cervical spine than radiography. Patients who are involved in high-energy trauma, who sustain head injury, or who have neurological deficits are candidates for CT screening. Screening with CT may enhance detection of other potentially important injuries of the cervical region. (orig.)

  10. New possibilities in the diagnosis of ischemia. CT-FFR and CT-Perfusion; Neue Moeglichkeiten der Ischaemiediagnostik. CT-FFR und CT-Perfusion

    Energy Technology Data Exchange (ETDEWEB)

    Lehmkuhl, Lukas [Herz- und Gefaessklinik, Bad Neustadt an der Saale (Germany). Abt. fuer Radiologie; Krieghoff, Christian [Herzzentrum Leipzig (Germany); Gutberlet, Matthias [Herzzentrum Leipzig (Germany). Abt. fuer Diagnostische und Interventionelle Radiologie; Leipzig Univ. (Germany). Kardiologische Bildgebung

    2017-12-15

    Coronary CT-angiography (CCTA) plays an increasing role in the primary diagnostics of coronary artery disease (CAD) according to the present guidelines but also in clinical reality. The sensitivity and negative predictive value of CCTA is very high, but the specificity could still be improved. Newer techniques to assess myocardial ischemia like CT-FFR and CT-Perfusion may help to achieve that goal.

  11. Diagnosis of acute ischemia using dual energy CT after mechanical thrombectomy.

    Science.gov (United States)

    Gariani, Joanna; Cuvinciuc, Victor; Courvoisier, Delphine; Krauss, Bernhard; Mendes Pereira, Vitor; Sztajzel, Roman; Lovblad, Karl-Olof; Vargas, Maria Isabel

    2016-10-01

    To assess the performance of dual energy unenhanced CT in the detection of acute ischemia after mechanical thrombectomy. Retrospective study, approved by the local institutional review board, including all patients that underwent intra-arterial thrombectomy in our institution over a period of 2 years. The presence of acute ischemia and hemorrhage was evaluated by three readers. Sensitivity and specificity of the non-contrast CT weighted sum image (NCCT) and the virtual non-contrast reconstructed image (VNC) were estimated and compared using generalized estimating equations to account for the non-independence of regions in each patient. 58 patients (27 women and 31 men; mean age 70.4 years) were included in the study, yielding 580 regions of interest. Sensitivity and specificity in detecting acute ischemia were higher for all readers when using VNC, with a significant increase in sensitivity for two readers (pVNC images were superior in the identification of acute ischemia in comparison with NCCT. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  12. Comparison of CT numbers between cone-beam CT and multi-detector CT

    International Nuclear Information System (INIS)

    Kim, Dong Soo; Han, Won Jeong; Kim, Eun Kyung

    2010-01-01

    To compare the CT numbers on 3 cone-beam CT (CBCT) images with those on multi-detector CT (MDCT) image using CT phantom and to develop linear regressive equations using CT numbers to material density for all the CT scanner each. Mini CT phantom comprised of five 1 inch thick cylindrical models with 1.125 inches diameter of materials with different densities (polyethylene, polystyrene, plastic water, nylon and acrylic) was used. It was scanned in 3 CBCTs (i-CAT, Alphard VEGA, Implagraphy SC) and 1 MDCT (Somatom Emotion). The images were saved as DICOM format and CT numbers were measured using OnDemand 3D. CT numbers obtained from CBCTs and MDCT images were compared and linear regression analysis was performed for the density, ρ(g/cm 3 ), as the dependent variable in terms of the CT numbers obtained from CBCTs and MDCT images. CT numbers on i-CAT and Implagraphy CBCT images were smaller than those on Somatom Emotion MDCT image (p<0.05). Linear relationship on a range of materials used for this study were ρ=0.001 H+1.07 with R2 value of 0.999 for Somatom Emotion, ρ=0.002 H+1.09 with R2 value of 0.991 for Alphard VEGA, ρ=0.001 H+1.43 with R2 value of 0.980 for i-CAT and ρ=0.001 H+1.30 with R2 value of 0.975 for Implagraphy. CT numbers on i-CAT and Implagraphy CBCT images were not same as those on Somatom Emotion MDCT image. The linear regressive equations to determine the density from the CT numbers with very high correlation coefficient were obtained on three CBCT and MDCT scan.

  13. Comparison of CT numbers between cone-beam CT and multi-detector CT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Soo; Han, Won Jeong; Kim, Eun Kyung [Department of Oral and Maxillofacial Radiology, School of Dentistry, Dankook University, Cheonan (Korea, Republic of)

    2010-06-15

    To compare the CT numbers on 3 cone-beam CT (CBCT) images with those on multi-detector CT (MDCT) image using CT phantom and to develop linear regressive equations using CT numbers to material density for all the CT scanner each. Mini CT phantom comprised of five 1 inch thick cylindrical models with 1.125 inches diameter of materials with different densities (polyethylene, polystyrene, plastic water, nylon and acrylic) was used. It was scanned in 3 CBCTs (i-CAT, Alphard VEGA, Implagraphy SC) and 1 MDCT (Somatom Emotion). The images were saved as DICOM format and CT numbers were measured using OnDemand 3D. CT numbers obtained from CBCTs and MDCT images were compared and linear regression analysis was performed for the density, {rho}(g/cm{sup 3}), as the dependent variable in terms of the CT numbers obtained from CBCTs and MDCT images. CT numbers on i-CAT and Implagraphy CBCT images were smaller than those on Somatom Emotion MDCT image (p<0.05). Linear relationship on a range of materials used for this study were {rho}=0.001 H+1.07 with R2 value of 0.999 for Somatom Emotion, {rho}=0.002 H+1.09 with R2 value of 0.991 for Alphard VEGA, {rho}=0.001 H+1.43 with R2 value of 0.980 for i-CAT and {rho}=0.001 H+1.30 with R2 value of 0.975 for Implagraphy. CT numbers on i-CAT and Implagraphy CBCT images were not same as those on Somatom Emotion MDCT image. The linear regressive equations to determine the density from the CT numbers with very high correlation coefficient were obtained on three CBCT and MDCT scan.

  14. Spectral multi-energy CT texture analysis with machine learning for tissue classification: an investigation using classification of benign parotid tumours as a testing paradigm.

    Science.gov (United States)

    Al Ajmi, Eiman; Forghani, Behzad; Reinhold, Caroline; Bayat, Maryam; Forghani, Reza

    2018-06-01

    There is a rich amount of quantitative information in spectral datasets generated from dual-energy CT (DECT). In this study, we compare the performance of texture analysis performed on multi-energy datasets to that of virtual monochromatic images (VMIs) at 65 keV only, using classification of the two most common benign parotid neoplasms as a testing paradigm. Forty-two patients with pathologically proven Warthin tumour (n = 25) or pleomorphic adenoma (n = 17) were evaluated. Texture analysis was performed on VMIs ranging from 40 to 140 keV in 5-keV increments (multi-energy analysis) or 65-keV VMIs only, which is typically considered equivalent to single-energy CT. Random forest (RF) models were constructed for outcome prediction using separate randomly selected training and testing sets or the entire patient set. Using multi-energy texture analysis, tumour classification in the independent testing set had accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 92%, 86%, 100%, 100%, and 83%, compared to 75%, 57%, 100%, 100%, and 63%, respectively, for single-energy analysis. Multi-energy texture analysis demonstrates superior performance compared to single-energy texture analysis of VMIs at 65 keV for classification of benign parotid tumours. • We present and validate a paradigm for texture analysis of DECT scans. • Multi-energy dataset texture analysis is superior to single-energy dataset texture analysis. • DECT texture analysis has high accura\\cy for diagnosis of benign parotid tumours. • DECT texture analysis with machine learning can enhance non-invasive diagnostic tumour evaluation.

  15. Renal stone characterization using high resolution imaging mode on a photon counting detector CT system

    Science.gov (United States)

    Ferrero, A.; Gutjahr, R.; Henning, A.; Kappler, S.; Halaweish, A.; Abdurakhimova, D.; Peterson, Z.; Montoya, J.; Leng, S.; McCollough, C.

    2017-03-01

    In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm x 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same subelements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

  16. TU-H-207A-09: An Automated Technique for Estimating Patient-Specific Regional Imparted Energy and Dose From TCM CT Exams Across 13 Protocols

    International Nuclear Information System (INIS)

    Sanders, J; Tian, X; Segars, P; Boone, J; Samei, E

    2016-01-01

    Purpose: To develop an automated technique for estimating patient-specific regional imparted energy and dose from tube current modulated (TCM) computed tomography (CT) exams across a diverse set of head and body protocols. Methods: A library of 58 adult computational anthropomorphic extended cardiac-torso (XCAT) phantoms were used to model a patient population. A validated Monte Carlo program was used to simulate TCM CT exams on the entire library of phantoms for three head and 10 body protocols. The net imparted energy to the phantoms, normalized by dose length product (DLP), and the net tissue mass in each of the scan regions were computed. A knowledgebase containing relationships between normalized imparted energy and scanned mass was established. An automated computer algorithm was written to estimate the scanned mass from actual clinical CT exams. The scanned mass estimate, DLP of the exam, and knowledgebase were used to estimate the imparted energy to the patient. The algorithm was tested on 20 chest and 20 abdominopelvic TCM CT exams. Results: The normalized imparted energy increased with increasing kV for all protocols. However, the normalized imparted energy was relatively unaffected by the strength of the TCM. The average imparted energy was 681 ± 376 mJ for abdominopelvic exams and 274 ± 141 mJ for chest exams. Overall, the method was successful in providing patientspecific estimates of imparted energy for 98% of the cases tested. Conclusion: Imparted energy normalized by DLP increased with increasing tube potential. However, the strength of the TCM did not have a significant effect on the net amount of energy deposited to tissue. The automated program can be implemented into the clinical workflow to provide estimates of regional imparted energy and dose across a diverse set of clinical protocols.

  17. Reconciling the cosmic age problem in the R{sub h} = ct universe

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H. [Nanjing University, School of Astronomy and Space Science, Nanjing (China); Wang, F.Y. [Nanjing University, School of Astronomy and Space Science, Nanjing (China); Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Ministry of Education, Nanjing (China)

    2014-10-15

    Many dark energy models fail to pass the cosmic age test. In this paper, we investigate the cosmic age problem associated with nine extremely old Global Clusters (GCs) and the old quasar APM 08279+5255 in the R{sub h} = ct universe. The age data of these oldest GCs in M31 are acquired from the Beijing-Arizona-Taiwan-Connecticut system with up-to-date theoretical synthesis models. They have not been used to test the cosmic age problem in the R{sub h} = ct universe in previous literature. By evaluating the age of the R{sub h} = ct universe with the observational constraints from the type Ia supernovae and the Hubble parameter, we find that the R{sub h} = ct universe can accommodate five GCs and the quasar APM 08279+5255 at redshift z = 3.91. But for other models, such as ΛCDM, the interacting dark energy model, the generalized Chaplygin gas model, and holographic dark energy model, cannot accommodate all GCs and the quasar APM 08279+5255. It is worthwhile to note that the age estimates of some GCs are controversial. So, unlike other cosmological models, the R{sub h} = ct universe can marginally solve the cosmic age problem, especially at high redshift. (orig.)

  18. Computed tomography with energy-resolved detection: a feasibility study

    Science.gov (United States)

    Shikhaliev, Polad M.

    2008-03-01

    The feasibility of computed tomography (CT) with energy-resolved x-ray detection has been investigated. A breast CT design with multi slit multi slice (MSMS) data acquisition was used for this study. The MSMS CT includes linear arrays of photon counting detectors separated by gaps. This CT configuration allows for efficient scatter rejection and 3D data acquisition. The energy-resolved CT images were simulated using a digital breast phantom and the design parameters of the proposed MSMS CT. The phantom had 14 cm diameter and 50/50 adipose/glandular composition, and included carcinoma, adipose, blood, iodine and CaCO3 as contrast elements. The x-ray technique was 90 kVp tube voltage with 660 mR skin exposure. Photon counting, charge (energy) integrating and photon energy weighting CT images were generated. The contrast-to-noise (CNR) improvement with photon energy weighting was quantified. The dual energy subtracted images of CaCO3 and iodine were generated using a single CT scan at a fixed x-ray tube voltage. The x-ray spectrum was electronically split into low- and high-energy parts by a photon counting detector. The CNR of the energy weighting CT images of carcinoma, blood, adipose, iodine, and CaCO3 was higher by a factor of 1.16, 1.20, 1.21, 1.36 and 1.35, respectively, as compared to CT with a conventional charge (energy) integrating detector. Photon energy weighting was applied to CT projections prior to dual energy subtraction and reconstruction. Photon energy weighting improved the CNR in dual energy subtracted CT images of CaCO3 and iodine by a factor of 1.35 and 1.33, respectively. The combination of CNR improvements due to scatter rejection and energy weighting was in the range of 1.71-2 depending on the type of the contrast element. The tilted angle CZT detector was considered as the detector of choice. Experiments were performed to test the effect of the tilting angle on the energy spectrum. Using the CZT detector with 20° tilting angle decreased the

  19. Triphasic contrast injection improves evaluation of dual energy lung perfusion in pulmonary CT angiography

    International Nuclear Information System (INIS)

    Kerl, J. Matthias; Bauer, Ralf W.; Renker, Matthias; Weber, Eva; Weisser, Philipp; Korkusuz, Huedayi; Schell, Boris; Larson, Maya Christina; Kromen, Wolfgang; Jacobi, Volkmar

    2011-01-01

    Purpose: Lung perfusion analysis at dual energy CT (DECT) is sensitive to beam hardening artifacts from dense contrast material (CM). We compared two scan and four CM injection protocols in terms of severity of artifacts and attenuation levels in the thoracic vessels. Methods and materials: Data of 120 patients who had undergone dual source dual energy CT pulmonary angiography for suspected acute pulmonary embolism were evaluated. Group 1 (n = 30) was scanned in craniocaudal direction using 64 × 0.6 mm collimation; groups 2–4 (n = 30 each) were scanned in caudocranial direction using 14 × 1.2 mm collimation. In groups 1–3 biphasic injection protocols with different amounts of CM and NaCl were investigated. In group 4 a split-bolus protocol with an initial CM bolus of 50 ml followed by 30 ml of a 70%:30% NaCl/CM mixture and a 50 ml NaCl chaser bolus was used. CT density values in the subclavian vein (SV), superior vena cava (SVC), pulmonary artery tree (PA), and the descending aorta (DA) were measured. Artifacts arising from the SV and SVC on DE pulmonary iodine distribution map were rated on a scale from 1 to 5 (1 = fully diagnostic; 5 = non-diagnostic) by two blinded readers. Results: In protocol 4 mean attenuation in the SV (645 ± 158 HU) and SVC (389 ± 114 HU) were significantly lower compared to groups 1–3 (p < 0.002). Artifacts in group 4 (1.1 ± 0.4 and 1.5 ± 0.7 for the SV and SVC, respectively) were rated significantly less severe compared to group 1 (3.2 ± 1.0 and 3.0 ± 1.1), 2 (2.6 ± 1.1 and 2.3 ± 1.0) and 3 (1.9 ± 0.9 and 1.9 ± 0.7) (p < 0.01 for all), whereas no significant difference was found between groups 1 and 2 for the subclavian vein (p = 0.07). Attenuation in the PA was also significantly lower in group 4 (282 ± 116 HU) compared to group 1 (397 ± 137 HU), group 2 (376 ± 115 HU) and group 3 (311 ± 104 HU), but still on a diagnostic level. Conclusion: Split-bolus injection provides sufficient attenuation for pulmonary DECT

  20. Comparative study between ultrahigh spatial frequency algorithm and high spatial frequency algorithm in high-resolution CT of the lungs

    International Nuclear Information System (INIS)

    Oh, Yu Whan; Kim, Jung Kyuk; Suh, Won Hyuck

    1994-01-01

    To date, the high spatial frequency algorithm (HSFA) which reduces image smoothing and increases spatial resolution has been used for the evaluation of parenchymal lung diseases in thin-section high-resolution CT. In this study, we compared the ultrahigh spatial frequency algorithm (UHSFA) with the high spatial frequency algorithm in the assessment of thin section images of the lung parenchyma. Three radiologists compared the UHSFA and HSFA on identical CT images in a line-pair resolution phantom, one lung specimen, 2 patients with normal lung and 18 patients with abnormal lung parenchyma. Scanning of a line-pair resolution phantom demonstrated no difference in resolution between two techniques but it showed that outer lines of the line pairs with maximal resolution looked thicker on UHSFA than those on HSFA. Lung parenchymal detail with UHSFA was judged equal or superior to HSFA in 95% of images. Lung parenchymal sharpness was improved with UHSFA in all images. Although UHSFA resulted in an increase in visible noise, observers did not found that image noise interfered with image interpretation. The visual CT attenuation of normal lung parenchyma is minimally increased in images with HSFA. The overall visual preference of the images reconstructed on UHSFA was considered equal to or greater than that of those reconstructed on HSFA in 78% of images. The ultrahigh spatial frequency algorithm improved the overall visual quality of the images in pulmonary parenchymal high-resolution CT

  1. Gene Regulation and Targeted Therapy in Gastric Cancer Peritoneal Metastasis: Radiological Findings from Dual Energy CT and PET/CT.

    Science.gov (United States)

    Shi, Bowen; Lin, Huimin; Zhang, Miao; Lu, Wei; Qu, Ying; Zhang, Huan

    2018-01-22

    Gastric cancer remains fourth in cancer incidence worldwide with a five-year survival of only 20%-30%. Peritoneal metastasis is the most frequent type of metastasis that accompanies unresectable gastric cancer and is a definitive determinant of prognosis. Preventing and controlling the development of peritoneal metastasis could play a role in helping to prolong the survival of gastric cancer patients. A non-invasive and efficient imaging technique will help us to identify the invasion and metastasis process of peritoneal metastasis and to monitor the changes in tumor nodules in response to treatments. This will enable us to obtain an accurate description of the development process and molecular mechanisms of gastric cancer. We have recently described experiment using dual energy CT (DECT) and positron emission tomography/computed tomography (PET/CT) platforms for the detection and monitoring of gastric tumor metastasis in nude mice models. We have shown that weekly continuous monitoring with DECT and PET/CT can identify dynamic changes in peritoneal metastasis. The sFRP1-overexpression in gastric cancer mice models showed positive radiological performance, a higher FDG uptake and increasing enhancement, and the SUVmax (standardized uptake value) of nodules demonstrated an obvious alteration trend in response to targeted therapy of TGF-β1 inhibitor. In this article, we described the detailed non-invasive imaging procedures to conduct more complex research on gastric cancer peritoneal metastasis using animal models and provided representative imaging results. The use of non-invasive imaging techniques should enable us to better understand the mechanisms of tumorigenesis, monitor tumor growth, and evaluate the effect of therapeutic interventions for gastric cancer.

  2. Spectrotemporal CT data acquisition and reconstruction at low dose

    International Nuclear Information System (INIS)

    Clark, Darin P.; Badea, Cristian T.; Lee, Chang-Lung; Kirsch, David G.

    2015-01-01

    Purpose: X-ray computed tomography (CT) is widely used, both clinically and preclinically, for fast, high-resolution anatomic imaging; however, compelling opportunities exist to expand its use in functional imaging applications. For instance, spectral information combined with nanoparticle contrast agents enables quantification of tissue perfusion levels, while temporal information details cardiac and respiratory dynamics. The authors propose and demonstrate a projection acquisition and reconstruction strategy for 5D CT (3D + dual energy + time) which recovers spectral and temporal information without substantially increasing radiation dose or sampling time relative to anatomic imaging protocols. Methods: The authors approach the 5D reconstruction problem within the framework of low-rank and sparse matrix decomposition. Unlike previous work on rank-sparsity constrained CT reconstruction, the authors establish an explicit rank-sparse signal model to describe the spectral and temporal dimensions. The spectral dimension is represented as a well-sampled time and energy averaged image plus regularly undersampled principal components describing the spectral contrast. The temporal dimension is represented as the same time and energy averaged reconstruction plus contiguous, spatially sparse, and irregularly sampled temporal contrast images. Using a nonlinear, image domain filtration approach, the authors refer to as rank-sparse kernel regression, the authors transfer image structure from the well-sampled time and energy averaged reconstruction to the spectral and temporal contrast images. This regularization strategy strictly constrains the reconstruction problem while approximately separating the temporal and spectral dimensions. Separability results in a highly compressed representation for the 5D data in which projections are shared between the temporal and spectral reconstruction subproblems, enabling substantial undersampling. The authors solved the 5D reconstruction

  3. Vanishing lung syndrome: the importance of the high-resolution CT in its diagnostic

    International Nuclear Information System (INIS)

    Rodriguez Cerezo, M.I.; Porres Azcona, E.; Pina Insausti, L.; Inchusta Sarasibar, M.I.; Mellado Rodriguez, M.

    1995-01-01

    Vanishing lung syndrome, also referred to as idiopathic giant bullions emphysema is a dissolver that has yet to be fully characterized. It is considered a different entry from classic pulmonary emphysema. It is characterized by the presence of large bullae associated with some type of emphysema. High-resolution CT is the best imaging technique to identify the underlying type of emphysema and it helps to determine the viability of the nonbullous lung. We present the case of an asymptomatic patient in whom the diagnosis was suspected on the basis of plain chest X ray and was confirmed by high-resolution CT. 13 refs

  4. Serial high resolution CT in non-specific interstitial pneumonia: prognostic value of the initial pattern

    Energy Technology Data Exchange (ETDEWEB)

    Screaton, N.J. [Department of Radiology, Addenbrooke' s Hospital, Cambridge (United Kingdom)]. E-mail: nicholas.screaton@papworth.nhs.uk; Hiorns, M.P. [Department of Radiology, Great Ormond Street Hospital, London (United Kingdom); Lee, K.S. [Samsung Medical Centre, Seoul (Korea); Franquet, T. [Hospital de Saint Pau, Universidad Autonoma de Barcelona, Barcelona (Spain); Johkoh, T. [Department of Medical Physics and Radiology, Osaka University Graduate School of Medicine, Osaka (Japan); Fujimoto, K. [Department of Radiology, Kurume University School of Medicine, Kurume (Japan); Ichikado, K. [First Department of Internal Medicine, Kumamoto University School of Medicine, Kumamoto (Japan); Colby, T.V. [Department of Laboratory Medicine/Pathology, Mayo Clinic Scottsdale, AZ (United States); Mueller, N.L. [Department of Radiology, Vancouver General Hospital, Vancouver (Canada)

    2005-01-01

    AIM: To assess the relationship between initial CT pattern and serial changes in CT findings and pulmonary function tests (PFTs) in patients with non-specific interstitial pneumonia (NSIP). MATERIALS AND METHODS: Serial high resolution (HR) CTs and PFTs were retrospectively analyzed in 38 cases of histologically proven NSIP, including 4 with cellular NSIP, 13 with mixed cellular and fibrotic NSIP, and 21 with fibrotic NSIP. The presence and extent of various CT findings were assessed. A fibrosis index (defined as the ratio of the extent of a reticular/honeycomb pattern to the overall extent of abnormal parenchyma) was derived. RESULTS: The predominant CT pattern was reticular/honeycomb in 27 (84%) cases and ground-glass/consolidation in 6 (16%) cases. Between scans, mean disease extent reduced by 5.2%. Disease extent reduced by >10% in 13 (34%) and increased by >10% in 6 (16%) patients. Histopathological subtype of NSIP did not correlate with individual CT pattern, predominant pattern, fibrosis index or serial change in disease extent on CT or PFTs. Response on follow-up CT was associated with fibrosis index, predominant pattern and extent of consolidation on initial CT. CONCLUSION: In NSIP disease, progression on CT correlates with the predominant CT pattern, fibrosis index, and extent of consolidation but not with histopathological subtype. An inflammatory (ground-glass/consolidation) predominant pattern is associated with better outcome in terms of disease extent on HRCT.

  5. Dosimetric impact of dual-energy CT tissue segmentation for low-energy prostate brachytherapy: a Monte Carlo study

    Science.gov (United States)

    Remy, Charlotte; Lalonde, Arthur; Béliveau-Nadeau, Dominic; Carrier, Jean-François; Bouchard, Hugo

    2018-01-01

    The purpose of this study is to evaluate the impact of a novel tissue characterization method using dual-energy over single-energy computed tomography (DECT and SECT) on Monte Carlo (MC) dose calculations for low-dose rate (LDR) prostate brachytherapy performed in a patient like geometry. A virtual patient geometry is created using contours from a real patient pelvis CT scan, where known elemental compositions and varying densities are overwritten in each voxel. A second phantom is made with additional calcifications. Both phantoms are the ground truth with which all results are compared. Simulated CT images are generated from them using attenuation coefficients taken from the XCOM database with a 100 kVp spectrum for SECT and 80 and 140Sn kVp for DECT. Tissue segmentation for Monte Carlo dose calculation is made using a stoichiometric calibration method for the simulated SECT images. For the DECT images, Bayesian eigentissue decomposition is used. A LDR prostate brachytherapy plan is defined with 125I sources and then calculated using the EGSnrc user-code Brachydose for each case. Dose distributions and dose-volume histograms (DVH) are compared to ground truth to assess the accuracy of tissue segmentation. For noiseless images, DECT-based tissue segmentation outperforms the SECT procedure with a root mean square error (RMS) on relative errors on dose distributions respectively of 2.39% versus 7.77%, and provides DVHs closest to the reference DVHs for all tissues. For a medium level of CT noise, Bayesian eigentissue decomposition still performs better on the overall dose calculation as the RMS error is found to be of 7.83% compared to 9.15% for SECT. Both methods give a similar DVH for the prostate while the DECT segmentation remains more accurate for organs at risk and in presence of calcifications, with less than 5% of RMS errors within the calcifications versus up to 154% for SECT. In a patient-like geometry, DECT-based tissue segmentation provides dose

  6. The value of FDG-PET/CT in assessing single pulmonary nodules in patients at high risk of lung cancer

    International Nuclear Information System (INIS)

    Kagna, Olga; Solomonov, Anna; Fruchter, Oren; Keidar, Zohar; Bar-Shalom, Rachel; Israel, Ora; Yigla, Mordechai; Guralnik, Luda

    2009-01-01

    To evaluate whether PET/low-dose CT (ldCT) using 18 F-fluorodeoxyglucose (FDG) improves characterization of indeterminate single pulmonary nodules (SPNs) in patients at high risk of lung cancer. Retrospective analysis of 307 patients who underwent FDG-PET/CT for indeterminate SPNs identified 93 (70 men, age range 46-90 years) at high risk of lung cancer (age >40 years, minimum 10 pack-year smokers). SPNs were evaluated for the presence and intensity of FDG avidity and ldCT patterns. The performance of visual and semiquantitative FDG-PET/ldCT algorithms for characterization of SPNs was compared to that of ldCT. Incongruent FDG-PET and ldCT patterns were analyzed for significance in further patient management. Malignancy was diagnosed in 38% patients. FDG avidity defined 33 SPNs as true-positive (TP) and 2 as false-negative (FN) (malignant), and 41 as true-negative (TN) and 17 as false-positive (FP) (benign). For SUVmax of 2.2 (by ROC analysis) there were 27 TP, 8 FN, 48 TN and 10 FP SPNs. LdCT defined 34 TP, 1 FN, 28 TN and 30 FP lesions. Of the FP lesions on ldCT, 60% were FDG-negative. Visual PET/ldCT analysis had a sensitivity of 94%, a specificity of 70%, an accuracy of 80%, a positive predictive value (PPV) of 66%, and a negative predictive value (NPV) of 95% as compared to 77%, 83%, 81%, 73%, 86% for semiquantitative PET/ldCT and 97%, 48%, 66%, 53%, 96% for ldCT, respectively. Both PET/ldCT algorithms had statistically significantly higher specificity and accuracy than ldCT. Semiquantitative analysis showed significantly higher PPV and lower sensitivity and NPV than found with ldCT. A single screening procedure encompassing FDG-PET and ldCT may improve screening for lung cancer in high-risk patients. The significantly improved specificity may potentially reduce FP ldCT results and further unnecessary invasive procedures. (orig.)

  7. Evaluation of high-resolution CT after tympanoplasty

    International Nuclear Information System (INIS)

    Torizuka, T.; Hayakawa, K.; Sato, Y.; Tanaka, F.; Okuno, Y.

    1991-01-01

    This paper reports on the condition of the middle ear cavity following tympanoplasty which is always of great interest to radiologists and otosurgeons. This study consisted of 21 patients who had various types of tympanoplasty (types I-IV) for chronic otitis media and cholesteatoma by using high-resolution CT (HRCT). HRCT following tympanoplasty was a valuable method for assessing the middle ear aeration and the state of ossicular reconstruction, including stapes prosthesis, although in some cases of soft-tissue mass in the middle ear it was necessary to correlate with clinical findings in order to differentiate between granulation and recurrence

  8. CT and Ultrasound Guided Stereotactic High Intensity Focused Ultrasound (HIFU)

    Science.gov (United States)

    Wood, Bradford J.; Yanof, J.; Frenkel, V.; Viswanathan, A.; Dromi, S.; Oh, K.; Kruecker, J.; Bauer, C.; Seip, R.; Kam, A.; Li, K. C. P.

    2006-05-01

    To demonstrate the feasibility of CT and B-mode Ultrasound (US) targeted HIFU, a prototype coaxial focused ultrasound transducer was registered and integrated to a CT scanner. CT and diagnostic ultrasound were used for HIFU targeting and monitoring, with the goals of both thermal ablation and non-thermal enhanced drug delivery. A 1 megahertz coaxial ultrasound transducer was custom fabricated and attached to a passive position-sensing arm and an active six degree-of-freedom robotic arm via a CT stereotactic frame. The outer therapeutic transducer with a 10 cm fixed focal zone was coaxially mounted to an inner diagnostic US transducer (2-4 megahertz, Philips Medical Systems). This coaxial US transducer was connected to a modified commercial focused ultrasound generator (Focus Surgery, Indianapolis, IN) with a maximum total acoustic power of 100 watts. This pre-clinical paradigm was tested for ability to heat tissue in phantoms with monitoring and navigation from CT and live US. The feasibility of navigation via image fusion of CT with other modalities such as PET and MRI was demonstrated. Heated water phantoms were tested for correlation between CT numbers and temperature (for ablation monitoring). The prototype transducer and integrated CT/US imaging system enabled simultaneous multimodality imaging and therapy. Pre-clinical phantom models validated the treatment paradigm and demonstrated integrated multimodality guidance and treatment monitoring. Temperature changes during phantom cooling corresponded to CT number changes. Contrast enhanced or non-enhanced CT numbers may potentially be used to monitor thermal ablation with HIFU. Integrated CT, diagnostic US, and therapeutic focused ultrasound bridges a gap between diagnosis and therapy. Preliminary results show that the multimodality system may represent a relatively inexpensive, accessible, and simple method of both targeting and monitoring HIFU effects. Small animal pre-clinical models may be translated to large

  9. Lung perfusion characteristics in pulmonary arterial hypertension (PAH) and peripheral forms of chronic thromboembolic pulmonary hypertension (pCTEPH): Dual-energy CT experience in 31 patients

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, Jessica; Khung, Suonita; Remy, Jacques; Remy-Jardin, Martine [Hospital Calmette (EA 2694), Department of Thoracic Imaging, Lille (France); Duhamel, Alain [University Lille, CHU Lille, Department of Biostatistics, Lille (France); Hossein-Foucher, Claude; Bellevre, Dimitri [University Lille, CHU Lille, Department of Nuclear Medicine, Hospital Salengro, Lille (France); Lamblin, Nicolas [University Lille, CHU Lille, Department of Cardiology, Cardiology Hospital, Lille (France)

    2017-04-15

    To compare lung perfusion in PAH and pCTEPH on dual-energy CT (DECT) examinations. Thirty-one patients with PAH (group 1; n = 19) and pCTEPH (group 2; n = 12) underwent a dual-energy chest CTA with reconstruction of diagnostic and perfusion images. Perfusion alterations were analysed at a segmental level. V/Q scintigraphy was available in 22 patients (group 1: 13/19; group 2: 9/12). CT perfusion was abnormal in 52.6 % of group 1 patients and in 100 % of group 2 patients (p = 0.0051). The patterns of perfusion alteration significantly differed between the two groups (p < 0.0001): (1) in group 1, 96.6 % of segments with abnormal perfusion showed patchy defects; (2) in group 2, the most frequent abnormalities consisted of patchy (58.5 %) and PE-type (37.5 %) defects. Paired comparison of CT perfusion and scintigraphy showed concordant findings in 76.9 % of group 1 (10/13) and 100 % of group 2 (9/9) patients, with a predominant or an exclusive patchy pattern in group 1 and a mixed pattern of abnormalities in group 2. Lung perfusion alterations at DECT are less frequent and more homogeneous in PAH than in pCTEPH, with a high level of concordant findings with V/Q scintigraphy. (orig.)

  10. CT of hepatocellular carcinoma. Analysis of contrast-enhanced CT using CT arteriography

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, H; Tanaka, T; Hori, S; Tokunaga, K; Yoshioka, H [Osaka Univ. (Japan). Faculty of Medicine

    1981-02-01

    Although changes in the CT appearance resulting from contrast enhancement (CE) for hepatocellular carcinoma have been considered in association with vascularity of tumors, no detailed studies have yet been made. We analyzed changes in the CT appearance following CE by comparing with hepatic arteriogram and CT arteriogram (CTA) performed during intraarterial infusion of contrast medium. When tumors showing low density in the plain CT were enhanced by contrast, the results were variable, ranging from intensification of the low density to replacement by high density, and the results were classified into L/sub 0/ to L/sub 3/ according to vascularity of tumors. The results after CE could also be classified into I/sub 0/ to I/sub 3/ when tumors showed isodensity in the plain CT. There was a correlation between vascularity presumed from CE and vascularity by CTA. It may be concluded that tumor vascularity could be estimated by the findings of CE which might indicate a possibility of qualitative diagnosis of tumors.

  11. Scaphoid fracture: Bone marrow edema detected with dual-energy CT virtual non-calcium images and confirmed with MRI

    Energy Technology Data Exchange (ETDEWEB)

    Dareez, Nazeer M.; Engesland, Eirin; Lindland, Elisabeth S. [Department of Radiology, SSHF Arendal, Arendal (Norway); Dahlslett, Kristine H. [Haukelands Universitetssjukehus, Department of Radiology, Bergen (Norway)

    2017-12-15

    We aimed to determine whether bone marrow edema (BME) in acute traumatic scaphoid fracture could be demonstrated with dual-energy CT (DECT) using MRI as the gold standard. In recent years, virtual non-calcium (VNCa) images have been used to demonstrate BME in trauma cases, for example, in vertebral compression fractures, hip trauma to detect occult fractures and knee fractures. We present three cases of acute scaphoid trauma. Two patients had subtle or invisible fractures on x-ray and conventional CT images, while DECT VNCa images clearly visualized the BME, which was confirmed by MRI. One patient had negative findings on both VNCa and MRI images. The DECT VNCa algorithm is a promising technique to demonstrate BME in scaphoid fractures, with potential for increasing the diagnostic value of CT in this type of injury. (orig.)

  12. High-resolution CT of airway reactivity

    International Nuclear Information System (INIS)

    Herold, C.J.; Brown, R.H.; Hirshman, C.A.; Mitzner, W.; Zerhouni, E.A.

    1990-01-01

    Assessment of airway reactivity has generally been limited to experimental nonimaging models. This authors of this paper used high-resolution CT (HRCT) to evaluate airway reactivity and to calculate airway resistance (Raw) compared with lung resistance (RL). Ten anesthetized and ventilated dogs were investigated with HRCT (10 contiguous 2-mm sections through the lower lung lobes) during control state, following aerosol histamine challenge, and following posthistamine hyperinflation. The HRCT scans were digitized, and areas of 10 airways per dog (diameter, 1-10 mm) were measured with a computer edging process. Changes in airway area and Raw (calculated by 1/[area] 2 ) were measured. RL was assessed separately, following the same protocol. Data were analyzed by use of a paired t-test with significance at p < .05

  13. F-FDG PET/CT (PET/CT) influences management in patients with known or suspected pancreatic cancer

    International Nuclear Information System (INIS)

    Barber, Thomas W.; Kalff, Victor; Cherk, Martin H.; Yap, Kenneth SK.; Evans, Peter; Kelly, Michael J.

    2009-01-01

    Full text: Objective: To assess the impact on clinical management of PET/CT in patients with known or suspected pancreatic cancer. Methods: Between April 2006 and September 2008,25 PET/CT scans were performed using a dedicated PET/CT (22 scans) or a coincidence hybrid PET/CT camera (3 scans) in 23 patients with known or suspected pancreatic cancer. 17 scans were performed for initial evaluation and 8 for restaging of disease. The pre-PET/CT management plan and for intent were prospectively recorded in all cases. The post-PET/CT management plan was determined from the medical record and for discussions with treating clinicians. The impact of PET/CT on management was classified as High, Medium, Low or None, defined using ANZAPNM PET data collection project criteria. Follow-up was used to reconcile any discordance between PET/CT and conventional imaging. Results: Overall, PET/CT management impact was classified as high (n equal 7), medium (n equal 4), low (n equal 10) or none (n equal 4). Impact was either high or medium in l l/25 patients (44%) (95% confidence interval; 24 - 64%). Impact was high in 4/17 patients imaged for initial evaluation, predominantly by clarifying equivocal lesions on conventional imaging. In restaged patients, PET/CT impact was high in 3/8, and it correctly modified disease extent in 5/8. In the 16 discordant studies, PET/CT assessment was correct in 10, conventional imaging in 4 and there was insufficient information in 2. Conclusion: PET/CT has high or medium management impact in 44% of patients imaged for known or suspected pancreatic cancer, more commonly during restaging. Discordant PET/CT results were usually correct.

  14. Examination of the fine interstitial changes of pneumoconiosis with high resolution computed tomography (HR-CT)

    International Nuclear Information System (INIS)

    Kido, Masamitsu; Miyazaki, Nobuyoshi; Harada, Susumu; Nakata, Hajime

    1986-01-01

    High resolution CT was performed in 14 patients with fine interstitial changes of pneumoconiosis and Review image was evaluated for the diagnostic accuracy as compared with conventional chest roentgenogram. Of the 14 Patients in the study, 7 were divided category 1 by the ILO U/C classification, 4 were category 2, 3 were category 3. Studies of lung function showed obstructive ventilatory disturbance characterized by moderate reduction in FEV 1.0% (58.6 ± 16.5 %) and V25/H (0.34 ± 0.24 l/sec/m). HR-CT defined more sensitive in the presence of fine lung nodules than conventional X-p, and showed high contrast interfaces provided by the aerated lung. HR-CT was also of value in detecting bulla, bleb, peripleural changes and hilar lymphadenopathy. Radiologic-pathologic correlation was examined on tne specimens of transbronchial lung biopsy in 4 patients, and revealed the diagnostic usefullness of HR-CT. (author)

  15. Chronic pneumonitis of infancy: high-resolution CT findings

    International Nuclear Information System (INIS)

    Olsen, Oeystein E.; Owens, Catherine M.; Sebire, Neil J.; Jaffe, Adam

    2004-01-01

    Chronic pneumonitis of infancy (CPI) is a very rare entity. We report the chest radiography and high-resolution CT (HRCT) findings in an infant with histopathologically confirmed CPI. The child was admitted for intensive care 18 h after birth and died at 39 days of age. On HRCT there was diffuse ground-glass change, interlobular septal thickening and discrete centrilobular nodules. An accurate diagnosis is crucial for correct management; however, several entities with the same HRCT findings are recognized. (orig.)

  16. Dual energy CT

    DEFF Research Database (Denmark)

    Al-Najami, Issam; Drue, Henrik Christian; Steele, Robert

    2017-01-01

    and inaccurate with existing methods. Dual Energy Computed Tomography (DECT) enables qualitative tissue differentiation by simultaneous scanning with different levels of energy. We aimed to assess the feasibility of DECT in quantifying tumor response to neoadjuvant therapy in loco-advanced rectal cancer. METHODS...... to determine the average quantitative parameters; effective-Z, water- and iodine-concentration, Dual Energy Index (DEI), and Dual Energy Ratio (DER). These parameters were compared to the regression in the resection specimen as measured by the pathologist. RESULTS: Changes in the quantitative parameters...

  17. High spatial resolution CT image reconstruction using parallel computing

    International Nuclear Information System (INIS)

    Yin Yin; Liu Li; Sun Gongxing

    2003-01-01

    Using the PC cluster system with 16 dual CPU nodes, we accelerate the FBP and OR-OSEM reconstruction of high spatial resolution image (2048 x 2048). Based on the number of projections, we rewrite the reconstruction algorithms into parallel format and dispatch the tasks to each CPU. By parallel computing, the speedup factor is roughly equal to the number of CPUs, which can be up to about 25 times when 25 CPUs used. This technique is very suitable for real-time high spatial resolution CT image reconstruction. (authors)

  18. Single-portal-phase low-tube-voltage dual-energy CT for short-term follow-up of acute pancreatitis: evaluation of CT severity index, interobserver agreement and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Wichmann, Julian L. [University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Universitaetsklinikum Frankfurt, Institut fuer Diagnostische und Interventionelle Radiologie, Frankfurt am Main (Germany); Majenka, Pawel; Beeres, Martin; Kromen, Wolfgang; Schulz, Boris; Bauer, Ralf W.; Kerl, J.M.; Gruber-Rouh, Tatjana; Hammerstingl, Renate; Vogl, Thomas J.; Lehnert, Thomas [University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Wesarg, Stefan [Fraunhofer IGD, Cognitive Computing and Medical Imaging, Darmstadt (Germany)

    2014-11-15

    To intra-individually compare single-portal-phase low-tube-voltage (100-kVp) computed tomography (CT) with 120-kVp images for short-term follow-up assessment of CT severity index (CTSI) of acute pancreatitis, interobserver agreement and radiation dose. We retrospectively analysed 66 patients with acute pancreatitis who underwent initial dual-contrast-phase CT (unenhanced, arterial, portal phase) at admission and short-term (mean interval 11.4 days) follow-up dual-contrast-phase dual-energy CT. The 100-kVp and linearly blended images representing 120-kVp acquisition follow-up CT images were independently evaluated by three radiologists using a modified CTSI assessing pancreatic inflammation, necrosis and extrapancreatic complications. Scores were compared with paired t test and interobserver agreement was evaluated using intraclass correlation coefficients (ICC). Mean CTSI scores on unenhanced, portal- and dual-contrast-phase images were 4.9, 6.1 and 6.2 (120 kVp) and 5.0, 6.0 and 6.1 (100 kVp), respectively. Contrast-enhanced series showed a higher CTSI compared to unenhanced images (P < 0.05) but no significant differences between single- and dual-contrast-phase series (P > 0.7). CTSI scores were comparable for 100-kVp and 120-kVp images (P > 0.05). Interobserver agreement was substantial for all evaluated series and subcategories (ICC 0.67-0.93). DLP of single-portal-phase 100-kVp images was reduced by 41 % compared to 120-kVp images (363.8 versus 615.9 mGy cm). Low-tube-voltage single-phase 100-kVp CT provides sufficient information for follow-up evaluation of acute pancreatitis and significantly reduces radiation exposure. (orig.)

  19. New perspective in high tech radiotherapy planning using PET/CT images (Radiation oncologist's view on PET/CT usage)

    International Nuclear Information System (INIS)

    Hadjieva, T.; Bildirev, N.; Koleva, I.; Zahariev, Z.; Vasileva, V.; Encheva, E.; Sultanov, B.

    2010-01-01

    Biological images provided by 18F-FDG PET in combination with structural X ray picture currently offer the most accurate available information on tumour staging, curative antitumour effect for prognosis, impairment of organ function after treatment, as well as primary tumour detection in unknown primary metastatic disease. The authors as radiation oncologists critically have analyzed numerous clinical trials and two guidelines to prove PET/ CT benefit in radiotherapy practice. At present they found lack of scientific evidence to confirm that patient outcomes are superior as a result of the use of PET in RT planning. PET/CT offers a best image for tumour delineation only in some cases of lung cancer, mediastinal lymph nodes and malignant lymphomas. 11C methionin PET adds additional information on postoperative MRI image for brain tumours. Inflammation as postradiation phenomenon, as well as physiological organ movements leads to false-positive PET signal. High tech radiotherapy methods require delineation on precise images given after multidisciplinary team expertise - a practice that is possible only in clinical trials, These unsolved problems have raised many ethical challenges in medical, scientific and social aspect, if wide and routine use of FDG-PET u PET/CT is advocated. (authors)

  20. Assessment of lobar perfusion in smokers according to the presence and severity of emphysema: preliminary experience with dual-energy CT angiography

    International Nuclear Information System (INIS)

    Pansini, Vittorio; Remy-Jardin, Martine; Faivre, Jean-Baptiste; Remy, Jacques; Schmidt, Bernhard; Dejardin-Bothelo, Alexis; Perez, Thierry; Delannoy, Valerie; Duhamel, Alain

    2009-01-01

    The purpose of the study was to assess pulmonary perfusion on a lobar level in smokers using dual-energy computed tomography (CT). Forty-seven smokers and ten non-smokers underwent a dual-energy multi-detector CT angiogram of the chest that allowed automatic quantification of emphysema and determination of the iodine content at the level of the microcirculation (i.e. ''perfusion imaging''). Emphysema was present in 37 smokers and absent in ten smokers. Smokers with an upper lobe predominance of emphysema (n = 8) had: (1) significantly lower attenuation enhancement values in the upper lobes compared with smokers without emphysema; (2) the lobes with the most severe emphysematous changes had a statistically significantly higher percentage of emphysema (p = 0.0001) and lower mean attenuation enhancement values (p = 0.0001) than the ipsilateral lobes with less severe emphysema, matching parenchymal destruction; (3) a correlation was found between the difference in percentage of emphysema between the upper and lower lobes and the difference in attenuation attenuation enhancement values in the corresponding lobes (p = 0.0355; r = -0.54). Regional alterations of lung perfusion can be depicted by dual-energy CT in smokers with predominant emphysema. (orig.)

  1. Clinical evaluation of high-resolution CT, 1. CT diagnosis of liver tumors and its limit

    Energy Technology Data Exchange (ETDEWEB)

    Araki, T [Tokyo Univ. (Japan). Faculty of Medicine

    1980-03-01

    To estimate diagnostic accuracy of CT in liver tumors, CT diagnosis in 120 patients with primary hepatocellular carcinoma was discussed. As a result, primary hepatocellular carcinoma less than 2 cm in diameter could not be visualized by CT. Even tumors between 4 and 8 cm in diameter showed false negative caused by isodense tumors on images of 4 patients. To improve the detectability of liver tumors by CT, the higher resolution of low contrast regions on images are required. As a method to improve qualitative diagnosis of liver tumors, rapid intravenous injection of contrast medium was performed on 42 patients with liver tumors, As a result, images reflecting vascularity of tumors were obtained, and the differential diagnosis was possible to some extent by observing the movement of the contrast. Especially, cavernous hemangioma could be distinguished from hepatocellular carcinoma, because cavernous hemangioma showed specific images and could be diagnosed accurately.

  2. CT and MR imaging of the kidney and adrenal glands: CT of the kidney

    International Nuclear Information System (INIS)

    Levine, E.

    1987-01-01

    Because of its high diagnostic yield, safety, and cost-effectiveness, CT has become a major imaging technique for evaluating the kidney. CT is highly accurate for determining the nature and extent of renal masses, and this has become the main indication for renal CT. However, CT is also valuable in assessing patients with renal cystic disease, trauma, inflammatory disease, infarction, hemorrhage and hydronephrosis of unknown cause. This presentation reviews the normal CT anatomy of the kidneys and the usefulness of CT in the diagnosis of all these conditions. Examination techniques are discussed with particular emphasis on avoiding diagnostic pitfalls and tailoring the examination to the nature of the clinical problem. CT findings in various renal disorders are compared with those of other imaging techniques, particularly US and angiography, and the place of CT in the diagnostic approach to these disorders is considered

  3. Utility of multiple rule out CT screening of high-risk atraumatic patients in an emergency department-a feasibility study

    DEFF Research Database (Denmark)

    Pries-Heje, Mia M; Hasselbalch, Rasmus B; Raaschou, Henriette

    2018-01-01

    malignant tumors in 10 (10%) cases. The mean size specific radiation dose was 15.9 mSv (± 3.1 mSv). CONCLUSION: Screening with a multi-rule out CT scan of high-risk patients in an ED is feasible and result in discovery of clinically unrecognized diagnoses and malignant tumors, but at the cost of radiation......BACKGROUND: Several large trials have evaluated the effect of CT screening based on specific symptoms, with varying outcomes. Screening of patients with CT based on their prognosis alone has not been examined before. For moderate-to-high risk patients presenting in the emergency department (ED......), the potential gain from a CT scan might outweigh the risk of radiation exposure. We hypothesized that an accelerated "multiple rule out" CT screening of moderate-to-high risk patients will detect many clinically unrecognized diagnoses that affect change in treatment. METHOD: Patients ≥ 40 years, triaged as high...

  4. A case of diffuse hemispheric gyral high density on CT scan following acute subdural hematoma in children

    International Nuclear Information System (INIS)

    Kannuki, Seiji; Oi, Shizuo

    1986-01-01

    A case of diffuse hemispheric gyral high density area following acute subdural hematoma was reported. A 2 - 10/12 year-old male was admitted to our hospital in comatous state after head injury by fall. Neurological examination revealed deep coma with anisocoria (R < L), absence of light reflex and positive bilateral Babinski reflex. CT scan disclosed left acute subdural hematoma with remarkable midline shift and tentorial herniation sign. Emergency decompressive craniectomy was performed. Posttraumatic hydrocephalus appeared after 10 days. So, ventriculoperitoneal shunt was done. The patient became gradually improved, but was in appalic state. 23 days after craniectomy, suddenly diffuse hemispheric gyral high density appeared on plain CT scan. In spite of this change, no clinical change was found. This high density spontaneously disappeared 10 days after appearance. Cerebral infarction-like phenomenon on postoperative CT scan of acute subdural hematoma in infants was sometimes reported. This phenomenon was sometimes accompanied with hemorrhagic infarction-like high density on CT scan. Diffuse hemispheric gyral high density was probably a kind of those hemorrhagic infarction-like phenomenon. Possible mechanism of this peculiar high density is discussed on the basis of characteristics of child's cerebral artery and pathophysiology of cerebral infarction. (author)

  5. CT findings of inoperable lung carcinoma

    International Nuclear Information System (INIS)

    Gay, S.B.; Black, W.C.

    1987-01-01

    CT is useful in the evaluation of patients with newly diagnosed or highly suspected lung cancer. The principal role of CT is to screen those patients with metastatic disease beyond the hili from an attempt at curative thoracotomy. While CT is regarded as very sensitive, it is not considered highly specific, and thus a surgical procedure is usually recommended for definitive diagnosis of most ''positive'' CT findings. However, the authors demonstrate a few characteristic CT findings that are highly predictive of unresectable metastatic disease. These CT findings include massive mediastinal lymphadenopathy, diffuse mediastinal infiltration, pericardial involvement, vascular encasement, and advanced chest wall invasion

  6. High-resolution CT of lymphoid interstitial pneumonia

    International Nuclear Information System (INIS)

    Vilgrain, V.; Frija, J.; Yana, C.; Couderc, L.J.; David, M.; Clauvel, J.P.; Laval-Jeantet, M.

    1989-01-01

    Three patients with lymphoid interstitial pneumonia (two HIV 1+ patients with chronic lymphadenopathic syndromes and one with a not-characterized autoimmune disease) have been studied with high-resolution computed tomography (HR-CT). This technique reveals septal lines, small reticulonodular opacities, polyhedral micronodular opacities, 'ground-glass' opacities and a dense, subpleural, curved broken line in one patient. The lesions dominate in the bases of the lungs. They are not characteristic for lymphoid interstitial pneumonia. If a patient presents with a chronic lymphadenopathic syndrome, the diagnosis of an opportunistic infection should not be automatically made, since the syndrome can be caused by lymphoid interstitial pneumonia [fr

  7. Construction of a voxel model from CT images with density derived from CT numbers

    International Nuclear Information System (INIS)

    Cheng Mengyun; Zeng Qin; Cao Ruifen; Li Gui; Zheng Huaqing; Huang Shanqing; Song Gang; Wu Yican

    2010-01-01

    The voxel models representing human anatomy have been developed to calculate dose distribution in human body, while the density is the most important physical property of voxel model. Traditionally, when creating the Monte Carlo input files, the average tissue parameters recommended in ICRP report were used to assign each voxel in the existing voxel models. However, as each tissue consists of many voxels in which voxels are different in their densities, the method of assigning average tissue parameters doesn't take account of the voxel's discrepancy, and can't represent human anatomy faithfully. To represent human anatomy more faithfully, a method was implemented to assign each voxel, the density of which was derived from CT number. In order to compare with the traditional method, we have constructed two models from a same cadaver specimen date set. A CT-based pelvic voxel model called Pelvis-CT model, was constructed, the densities of which were derived from the CT numbers. A color photograph-based pelvic voxel model called Pelvis-Photo model, was also constructed, the densities of which were taken from ICRP Publication. The CT images and color photographs were obtained from the same female cadaver specimen. The Pelvis-CT and Pelvis-Photo models were ported into Monte Carlo code MCNP to calculate the conversion coefficients from kerma free-in-air to absorbed dose for external monoenergetic photon beams with energies of 0.1, 1 and 10 MeV under anterior-posterior (AP) geometries. The results were compared with those of given in ICRP74. Differences of up to 50% were observed between conversion coefficients of Pelvis-CT and Pelvis-Photo models, moreover the discrepancies decreased for the photon beams with higher energies. The overall trend of conversion coefficients of the Pelvis-CT model were agreed well with that of ICRP74 data. (author)

  8. Construction of a voxel model from CT images with density derived from CT numbers

    International Nuclear Information System (INIS)

    Cheng Mengyun; Zeng Qin; Cao Ruifen; Li Gui; Zheng Huaqing; Huang Shanqing; Song Gang; Wu Yican

    2011-01-01

    The voxel models representing human anatomy have been developed to calculate dose distribution in human body, while the density and elemental composition are the most important physical properties of voxel model. Usually, when creating the Monte Carlo input files, the average tissue densities recommended in ICRP Publication were used to assign each voxel in the existing voxel models. As each tissue consists of many voxels with different densities, the conventional method of average tissue densities failed to take account of the voxel's discrepancy, and therefore could not represent human anatomy faithfully. To represent human anatomy more faithfully, a method was implemented to assign each voxel, the densities of which were derived from CT number. In order to compare with the traditional method, we constructed two models from the cadaver specimen dataset. A CT-based pelvic voxel model called Pelvis-CT model was constructed, the densities of which were derived from the CT numbers. A color photograph-based pelvic voxel model called Pelvis-Photo model was also constructed, the densities of which were taken from ICRP Publication. The CT images and the color photographs were obtained from the same female cadaver specimen. The Pelvis-CT and Pelvis-Photo models were both ported into Monte Carlo code MCNP to calculate the conversion coefficients from kerma free-in-air to absorbed dose for external monoenergetic photon beams with energies of 0.1, 1 and 10 MeV under anterior-posterior (AP) geometry. The results were compared with those of given in ICRP Publication 74. Differences of up to 50% were observed between conversion coefficients of Pelvis-CT and Pelvis- Photo models, moreover the discrepancies decreased for the photon beams with higher energies. The overall trend of conversion coefficients of the Pelvis-CT model agreed well with that of ICRP Publication 74 data. (author)

  9. Single- and dual-energy CT of the abdomen: comparison of radiation dose and image quality of 2nd and 3rd generation dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Wichmann, Julian L. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Hardie, Andrew D.; Felmly, Lloyd M.; Perry, Jonathan D.; Varga-Szemes, Akos; De Cecco, Carlo N. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Schoepf, U.J. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Mangold, Stefanie [University Hospital of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Caruso, Damiano [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Rome ' ' Sapienza' ' , Department of Radiological Sciences, Oncological and Pathological Sciences, Latina (Italy); Canstein, Christian [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Siemens Medical Solutions USA, Malvern, PA (United States); Vogl, Thomas J. [University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany)

    2017-02-15

    To compare single-energy (SECT) and dual-energy (DECT) abdominal CT examinations in matched patient cohorts regarding differences in radiation dose and image quality performed with second- and third-generation dual-source CT (DSCT). We retrospectively analysed 200 patients (100 male, 100 female; mean age 61.2 ± 13.5 years, mean body mass index 27.5 ± 3.8 kg/m{sup 2}) equally divided into four groups matched by gender and body mass index, who had undergone portal venous phase abdominal CT with second-generation (group A, 120-kV-SECT; group B, 80/140-kV-DECT) and third-generation DSCT (group C, 100-kV-SECT; group D, 90/150-kV-DECT). The radiation dose was normalised for 40-cm scan length. Dose-independent figure-of-merit (FOM) contrast-to-noise ratios (CNRs) were calculated for various organs and vessels. Subjective overall image quality and reader confidence were assessed. The effective normalised radiation dose was significantly lower (P < 0.001) in groups C (6.2 ± 2.0 mSv) and D (5.3 ± 1.9 mSv, P = 0.103) compared to groups A (8.8 ± 2.3 mSv) and B (9.7 ± 2.4 mSv, P = 0.102). Dose-independent FOM-CNR peaked for liver, kidney, and portal vein measurements (all P ≤ 0.0285) in group D. Subjective image quality and reader confidence were consistently rated as excellent in all groups (all ≥1.53 out of 5). With both DSCT generations, abdominal DECT can be routinely performed without radiation dose penalty compared to SECT, while third-generation DSCT shows improved dose efficiency. (orig.)

  10. CT of the heart

    International Nuclear Information System (INIS)

    Lipton, M.J.

    1986-01-01

    Advances based upon the detector elements instead of X-ray film have greatly increased the power of X-ray imaging. Computed tomography (CT) creates cross sectional rather than projected images. Recently, high speed CT devices have been developed for cardiovascular studies. The Cine-CT scanner employs a scanning electron beam deflected on an extended tungsten target ring. Fast scans of 50 millisecond exposures at multiple levels can provide information concerning blood flow in vessels and tissues, myocardial wall motion, valve integrity, coronary bypass graft patency and proximal coronary artery anatomy. Cine-CT dynamic scanning can also provide volume imaging with small quantities (0.05 - 1.5 ml/kg) of contrast medium administered via peripheral vein injections. Cine-CT provides simultaneous measurements of cardiac dimensions and function and is rapidly becoming a new tool for quantitating myocardial blood flow, cardiac chamber volumes and wall mechanics. The future outlook is very promising for this three-dimensional cine-CT technique with high spatial resolution. High speed CT should provide unique diagnostic information and as the technology continues to improve at a rapid speed, this new imaging modality could be a challenge for angiography. (Auth.)

  11. Automatic intensity-based 3D-to-2D registration of CT volume and dual-energy digital radiography for the detection of cardiac calcification

    Science.gov (United States)

    Chen, Xiang; Gilkeson, Robert; Fei, Baowei

    2007-03-01

    We are investigating three-dimensional (3D) to two-dimensional (2D) registration methods for computed tomography (CT) and dual-energy digital radiography (DR) for the detection of coronary artery calcification. CT is an established tool for the diagnosis of coronary artery diseases (CADs). Dual-energy digital radiography could be a cost-effective alternative for screening coronary artery calcification. In order to utilize CT as the "gold standard" to evaluate the ability of DR images for the detection and localization of calcium, we developed an automatic intensity-based 3D-to-2D registration method for 3D CT volumes and 2D DR images. To generate digital rendering radiographs (DRR) from the CT volumes, we developed three projection methods, i.e. Gaussian-weighted projection, threshold-based projection, and average-based projection. We tested normalized cross correlation (NCC) and normalized mutual information (NMI) as similarity measurement. We used the Downhill Simplex method as the search strategy. Simulated projection images from CT were fused with the corresponding DR images to evaluate the localization of cardiac calcification. The registration method was evaluated by digital phantoms, physical phantoms, and clinical data sets. The results from the digital phantoms show that the success rate is 100% with mean errors of less 0.8 mm and 0.2 degree for both NCC and NMI. The registration accuracy of the physical phantoms is 0.34 +/- 0.27 mm. Color overlay and 3D visualization of the clinical data show that the two images are registered well. This is consistent with the improvement of the NMI values from 0.20 +/- 0.03 to 0.25 +/- 0.03 after registration. The automatic 3D-to-2D registration method is accurate and robust and may provide a useful tool to evaluate the dual-energy DR images for the detection of coronary artery calcification.

  12. [Clinical application of high-pitch excretory phase images during dual-source CT urography with stellar photon detector].

    Science.gov (United States)

    Sun, Hao; Xue, Hua-dan; Jin, Zheng-yu; Wang, Xuan; Chen, Yu; He, Yong-lan; Zhang, Da-ming; Zhu, Liang; Wang, Yun; Qi, Bing; Xu, Kai; Wang, Ming

    2014-10-01

    To retrospectively evaluate the clinical feasibility of high-pitch excretory phase images during dual-source CT urography with Stellar photon detector. Totally 100 patients received dual-source CT high-pitch urinary excretory phase scanning with Stellar photon detector [80 kV, ref.92 mAs, CARE Dose 4D and CARE kV, pitch of 3.0, filter back projection reconstruction algorithm (FBP)] (group A). Another 100 patients received dual-source CT high-pitch urinary excretory phase scanning with common detector(100 kV, ref.140 mAs, CARE Dose 4D, pitch of 3.0, FBP) (group B). Quantitative measurement of CT value of urinary segments (Hounsfield units), image noise (Hounsfield units), and effective radiation dose (millisievert) were compared using independent-samples t test between two groups. Urinary system subjective opacification scores were compared using Mann-Whitney U test between two groups. There was no significant difference in subjective opacification score of intrarenal collecting system and ureters between two groups (all P>0.05). The group A images yielded significantly higher CT values of all urinary segments (all P0.05). The effective radiation dose of group A (1.1 mSv) was significantly lower than that of group B (3.79 mSv) (Ppitch low-tube-voltage during excretory phase dual-source CT urography with Stellar photon detector is feasible, with acceptable image noise and lower radiation dose.

  13. [Accurate 3D free-form registration between fan-beam CT and cone-beam CT].

    Science.gov (United States)

    Liang, Yueqiang; Xu, Hongbing; Li, Baosheng; Li, Hongsheng; Yang, Fujun

    2012-06-01

    Because the X-ray scatters, the CT numbers in cone-beam CT cannot exactly correspond to the electron densities. This, therefore, results in registration error when the intensity-based registration algorithm is used to register planning fan-beam CT and cone-beam CT. In order to reduce the registration error, we have developed an accurate gradient-based registration algorithm. The gradient-based deformable registration problem is described as a minimization of energy functional. Through the calculus of variations and Gauss-Seidel finite difference method, we derived the iterative formula of the deformable registration. The algorithm was implemented by GPU through OpenCL framework, with which the registration time was greatly reduced. Our experimental results showed that the proposed gradient-based registration algorithm could register more accurately the clinical cone-beam CT and fan-beam CT images compared with the intensity-based algorithm. The GPU-accelerated algorithm meets the real-time requirement in the online adaptive radiotherapy.

  14. Characteristics of modified CT injector for JFT-2M

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, N. [Himeji Institute of Technology, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan)]. E-mail: fukumoto@elct.eng.himeji-tech.ac.jp; Ogawa, H. [Japan Atomic Energy Research Institute (JAERI), 2-4 Shirakatashirane, Tokai-mura, Naka-gun, Ibaraki 311-0193 (Japan); Nagata, M. [Himeji Institute of Technology, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan); Uyama, T. [Himeji Institute of Technology, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan); Shibata, T. [Japan Atomic Energy Research Institute (JAERI), 2-4 Shirakatashirane, Tokai-mura, Naka-gun, Ibaraki 311-0193 (Japan); Kashiwa, Y. [Japan Atomic Energy Research Institute (JAERI), 2-4 Shirakatashirane, Tokai-mura, Naka-gun, Ibaraki 311-0193 (Japan); Kusama, Y. [Japan Atomic Energy Research Institute (JAERI), 2-4 Shirakatashirane, Tokai-mura, Naka-gun, Ibaraki 311-0193 (Japan)

    2004-10-01

    The HIT-CTI mark II compact toroid (CT) injector employed for the JFT-2M tokamak facility at the Japan Atomic Energy Research Institute (JAERI) has been upgraded to improve injection performance. The nozzle of the mark III injector now has a linear tube in place of the original focus cone to avoid rapid focus and deceleration, and the tapered outer electrode has been replaced with more gentle taper in the compression section in order to facilitate gradual compression. The dependence of CT velocity and electron density on poloidal bias flux and trigger time of CT acceleration have been investigated in the operable range of 70-230 km/s average CT velocity and electron density of 0.1-1.0 x 10{sup 22} m{sup -3} at an accelerator bank voltage of 25 kV. The operation window is broader than that of the mark II injector. Emission of a CT plasmoid from the injector, and transport to the flux conserver as a high-density spheromak magnetic structure have also been confirmed.

  15. Patient size and x-ray transmission in body CT.

    Science.gov (United States)

    Ogden, Kent; Huda, Walter; Scalzetti, Ernest M; Roskopf, Marsha L

    2004-04-01

    Physical characteristics were obtained for 196 patients undergoing chest and abdomen computed tomography (CT) examinations. Computed tomography sections for these patients having no evident pathology were analyzed to determine patient dimensions (AP and lateral), together with the average attenuation coefficient. Patient weights ranged from approximately 3 kg to about 120 kg. For chest CT, the mean Hounsfield unit (HU) fell from about -120 HU for newborns to about -300 HU for adults. For abdominal CT, the mean HU for children and normal-sized adults was about 20 HU, but decreased to below -50 HU for adults weighing more than 100 kg. The effective photon energy and percent energy fluence transmitted through a given patient size and composition was calculated for representative x-ray spectra at 80, 100, 120, and 140 kV tube potentials. A 70-kg adult scanned at 120 kVp transmits 2.6% of the energy fluence for chest and 0.7% for abdomen CT examinations. Reducing the patient size to 10 kg increases transmission by an order of magnitude. For 70 kg patients, effective energies in body CT range from approximately 50 keV at 80 kVp to approximately 67 keV at 140 kVp; increasing patient size from 10 to 120 kg resulted in an increase in effective photon energy of approximately 4 keV. The x-ray transmission data and effective photon energy data can be used to determine CT image noise and image contrast, respectively, and information on patient size and composition can be used to determine patient doses.

  16. CT dose reduction in children

    International Nuclear Information System (INIS)

    Vock, Peter

    2005-01-01

    World wide, the number of CT studies in children and the radiation exposure by CT increases. The same energy dose has a greater biological impact in children than in adults, and scan parameters have to be adapted to the smaller diameter of the juvenile body. Based on seven rules, a practical approach to paediatric CT is shown: Justification and patient preparation are important steps before scanning, and they differ from the preparation of adult patients. The subsequent choice of scan parameters aims at obtaining the minimal signal-to-noise ratio and volume coverage needed in a specific medical situation; exposure can be divided in two aspects: the CT dose index determining energy deposition per rotation and the dose-length product (DLP) determining the volume dose. DLP closely parallels the effective dose, the best parameter of the biological impact. Modern scanners offer dose modulation to locally minimise exposure while maintaining image quality. Beyond the selection of the physical parameters, the dose can be kept low by scanning the minimal length of the body and by avoiding any non-qualified repeated scanning of parts of the body. Following these rules, paediatric CT examinations of good quality can be obtained at a reasonable cost of radiation exposure. (orig.)

  17. Alveolar architecture of clear cell renal carcinomas (≤5.0 cm) show high attenuation on dynamic CT scanning

    International Nuclear Information System (INIS)

    Fujimoto, Hiroyuki; Wakao, Fumihiko; Moriyama, Noriyuki; Tobisu, Kenichi; Kakizoe, Tadao; Sakamoto, Michiie

    1999-01-01

    To establish the correlation between tumor appearance on CT and tumor histology in renal cell carcinomas. The density and attenuation patterns of 96 renal cell carcinomas, each ≤5 cm in greatest diameter, were studied by non-enhanced CT and early and late after bolus injection of contrast medium using dynamic CT. The density and attenuation patterns and pathological maps of each tumor were individually correlated. High attenuated areas were present in 72 of the 96 tumors on early enhanced dynamic CT scanning. All 72 high attenuated areas were of the clear cell renal cell carcinoma and had alveolar architecture. The remaining 24 tumors that did not demonstrate high attenuated foci on early enhanced scanning included three clear cell, nine granular cell, six papillary, five chromophobe and one collecting duct type. With respect to tumor architecture, all clear cell tumors of alveolar architecture demonstrated high attenuation on early enhanced scanning. Clear cell renal cell carcinomas of alveolar architecture show high attenuation on early enhanced dynamic CT scanning. A larger number of patients are indispensable to obtaining clear results. However, these findings seem to be an important clue to the diagnosis of renal cell carcinomas as having an alveolar structure. (author)

  18. Changes in measured size of atherosclerotic plaque calcifications in dual-energy CT of ex vivo carotid endarterectomy specimens: effect of monochromatic keV image reconstructions

    International Nuclear Information System (INIS)

    Mannelli, Lorenzo; Mitsumori, Lee M.; Ferguson, Marina; Xu, Dongxiang; Chu, Baocheng; Branch, Kelley R.; Shuman, William P.; Yuan, Chun

    2013-01-01

    The aim of this study was to compare the size of the calcifications measured on the different keV images to a histological standard. Five ex vivo carotid endarterectomy (CEA) specimens were imaged with a dual-energy CT. CT images were reconstructed at different monochromatic spectral energies (40, 60, 77, 80, 100, 120, 140 keV). Cross-sectional area of the plaque calcifications present on each CT image was measured. The histological calcium areas on each corresponding CEA specimen were traced manually on digitised images of Toluidine Blue/Basic Fuchsin stained plastic sections. The CT images and corresponding histology sections were matched. The CT-derived calcium areas on each keV image were compared to the calcified area measurements by histology. A total of 107 histology sections were matched to corresponding CT images. The average calcified area per section by histology was 7.6 ± 7 mm 2 (range 0-26.4 mm 2 ). There was no significant difference between the calcified areas measured by histology and those measured on CT-virtual monochromatic spectral (VMS) reconstructed images at 77 keV (P = 0.08), 80 keV (P = 0.20) and 100 keV (P = 0.14). Calcium area measured on the 80 keV image set was most comparable to the amount of calcium measured by histology. (orig.)

  19. Acute pulmonary injury: high-resolution CT and histopathological spectrum

    Science.gov (United States)

    Obadina, E T; Torrealba, J M

    2013-01-01

    Acute lung injury usually causes hypoxaemic respiratory failure and acute respiratory distress syndrome (ARDS). Although diffuse alveolar damage is the hallmark of ARDS, other histopathological patterns of injury, such as acute and fibrinoid organising pneumonia, can be associated with acute respiratory failure. Acute eosinophilic pneumonia can also cause acute hypoxaemic respiratory failure and mimic ARDS. This pictorial essay reviews the high-resolution CT findings of acute lung injury and the correlative histopathological findings. PMID:23659926

  20. CT and MR imaging of high cervical intradural lipomas

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joo Hyeong; Choi, Woo Suk; Lee, Sun Wha; Lim, Jae Hoon; Leem, Woon; Kim, Gook Ki; Rhee, Bong Arm [Kyung Hee University Hospital, Seoul (Korea, Republic of)

    1988-04-15

    Intradural spinal lipoma occurs in less than 1% of all spinal cord tumors. It has been described at every level of the spinal canal, although its most common location is the cervicothoracic and thoracic region. However, lipoma located in the high cervical region is very unusual. We described two cases, a teenager and an adult, with progressive neurologic deficit from such a lipomatous tumor, which were evaluated by CT scanning and MR imaging.

  1. Improved spatial resolution and lower-dose pediatric CT imaging: a feasibility study to evaluate narrowing the X-ray photon energy spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Benz, Mark G. [Safer Pediatric Imaging and Engineering Horizons International, Lincoln, VT (United States); Benz, Matthew W. [Southboro Medical Group, Southboro, MA (United States); Birnbaum, Steven B. [Dartmouth Hitchcock Clinic Manchester, Department of Radiology, Manchester, NH (United States); Chason, Eric; Sheldon, Brian W. [Brown University, Division of Engineering, Materials Science and Engineering Program, Providence, RI (United States); McGuire, Dale [R and D Manager, C and G Technologies Inc., Jeffersonville, IN (United States)

    2014-08-15

    This feasibility study has shown that improved spatial resolution and reduced radiation dose can be achieved in pediatric CT by narrowing the X-ray photon energy spectrum. This is done by placing a hafnium filter between the X-ray generator and a pediatric abdominal phantom. A CT system manufactured in 1999 that was in the process of being remanufactured was used as the platform for this study. This system had the advantage of easy access to the X-ray generator for modifications to change the X-ray photon energy spectrum; it also had the disadvantage of not employing the latest post-imaging noise reduction iterative reconstruction technology. Because we observed improvements after changing the X-ray photon energy spectrum, we recommend a future study combining this change with an optimized iterative reconstruction noise reduction technique. (orig.)

  2. Detecting metastasis of gastric carcinoma using high-resolution micro-CT system: in vivo small animal study

    Science.gov (United States)

    Liu, Junting; Tian, Jie; Liang, Jimin; Li, Xiangsi; Yang, Xiang; Chen, Xiaofeng; Chen, Yi; Zhou, Yuanfang; Wang, Xiaorui

    2011-03-01

    Immunocytochemical and immunofluorescence staining are used for identifying the characteristics of metastasis in traditional ways. Micro-computed tomography (micro-CT) is a useful tool for monitoring and longitudinal imaging of tumor in small animal in vivo. In present study, we evaluated the feasibility of the detection for metastasis of gastric carcinoma by high-resolution micro-CT system with omnipaque accumulative enhancement method in the organs. Firstly, a high-resolution micro-CT ZKKS-MCT-sharp micro-CT was developed by our research group and Guangzhou Zhongke Kaisheng Medical Technology Co., Ltd. Secondly, several gastric carcinoma models were established through inoculating 2x106 BGC-823 gastric carcinoma cells subcutaneously. Thirdly, micro-CT scanning was performed after accumulative enhancement method of intraperitoneal injection of omnipaque contrast agent containing 360 mg iodine with a concentration of 350 mg I/ml. Finally, we obtained high-resolution anatomical information of the metastasis in vivo in a BALB/c NuNu nude mouse, the 3D tumor architecture is revealed in exquisite detail at about 35 μm spatial resolution. In addition, the accurate shape and volume of the micrometastasis as small as 0.78 mm3 can be calculated with our software. Overall, our data suggest that this imaging approach and system could be used to enhance the understanding of tumor proliferation, metastasis and could be the basis for evaluating anti-tumor therapies.

  3. Diagnostic performance of calcification-suppressed coronary CT angiography using rapid kilovolt-switching dual-energy CT.

    Science.gov (United States)

    Yunaga, Hiroto; Ohta, Yasutoshi; Kaetsu, Yasuhiro; Kitao, Shinichiro; Watanabe, Tomomi; Furuse, Yoshiyuki; Yamamoto, Kazuhiro; Ogawa, Toshihide

    2017-07-01

    Multi-detector-row computed tomography angiography (MDCTA) plays an important role in the assessment of patients with suspected coronary artery disease. However, MDCTA tends to overestimate stenosis in calcified coronary artery lesions. The aim of our study was to evaluate the diagnostic performance of calcification-suppressed material density (MD) images produced by using a single-detector single-source dual-energy computed tomography (ssDECT). We enrolled 67 patients with suspected or known coronary artery disease who underwent ssDECT with rapid kilovolt-switching (80 and 140 kVp). Coronary artery stenosis was evaluated on the basis of MD images and virtual monochromatic (VM) images. The diagnostic performance of the two methods for detecting coronary artery disease was compared with that of invasive coronary angiography as a reference standard. We evaluated 239 calcified segments. In all the segments, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting significant stenosis were respectively 88%, 88%, 75%, 95% and 88% for the MD images, 91%, 71%, 56%, 95% and 77% for the VM images. PPV was significantly higher on the MD images than on the VM images (P < 0.0001). Calcification-suppressed MD images improved PPV and diagnostic performance for calcified coronary artery lesions. • Computed tomography angiography tends to overestimate stenosis in calcified coronary artery. • Dual-energy CT enables us to suppress calcification of coronary artery lesions. • Calcification-suppressed material density imaging reduces false-positive diagnosis of calcified lesion.

  4. Pre-reconstruction dual-energy, X-ray computerized tomography (CT): theory, implementation, results, and clinical use

    International Nuclear Information System (INIS)

    Oravez, W.T.

    1986-01-01

    For the task of bone mineral measurement, single-energy quantitative CT has demonstrated its worth in terms of precision for most longitudinal clinical studies. However, for cross-sectional clinical studies, known inaccuracy exists due to less than robust beam-hardening corrections, and negatively biased bone mineral measurement, due to the effect of unknown variable concentration of bone marrow fat within the metabolically active trabecular bone space. A dual-energy measurement technique provides a solution to these deficiencies of single-energy measurements. The fundamental theory of dual-energy measurement techniques is based on a Compton-photoelectric approximation and the mixture rule for the total attenuation coefficient. Resolution of atomic composition and electron density components of attenuation should then be possible. To take full advantage of these principles, the raw dual-energy projection values are operated on before reconstruction. This method beam-hardening and composition-selective imaging. Rapid kilovoltage switching between projection measurements, rather than serial measurements, assures the best measurement quality

  5. PET attenuation coefficients from CT images: experimental evaluation of the transformation of CT into PET 511-keV attenuation coefficients.

    Science.gov (United States)

    Burger, C; Goerres, G; Schoenes, S; Buck, A; Lonn, A H R; Von Schulthess, G K

    2002-07-01

    The CT data acquired in combined PET/CT studies provide a fast and essentially noiseless source for the correction of photon attenuation in PET emission data. To this end, the CT values relating to attenuation of photons in the range of 40-140 keV must be transformed into linear attenuation coefficients at the PET energy of 511 keV. As attenuation depends on photon energy and the absorbing material, an accurate theoretical relation cannot be devised. The transformation implemented in the Discovery LS PET/CT scanner (GE Medical Systems, Milwaukee, Wis.) uses a bilinear function based on the attenuation of water and cortical bone at the CT and PET energies. The purpose of this study was to compare this transformation with experimental CT values and corresponding PET attenuation coefficients. In 14 patients, quantitative PET attenuation maps were calculated from germanium-68 transmission scans, and resolution-matched CT images were generated. A total of 114 volumes of interest were defined and the average PET attenuation coefficients and CT values measured. From the CT values the predicted PET attenuation coefficients were calculated using the bilinear transformation. When the transformation was based on the narrow-beam attenuation coefficient of water at 511 keV (0.096 cm(-1)), the predicted attenuation coefficients were higher in soft tissue than the measured values. This bias was reduced by replacing 0.096 cm(-1) in the transformation by the linear attenuation coefficient of 0.093 cm(-1) obtained from germanium-68 transmission scans. An analysis of the corrected emission activities shows that the resulting transformation is essentially equivalent to the transmission-based attenuation correction for human tissue. For non-human material, however, it may assign inaccurate attenuation coefficients which will also affect the correction in neighbouring tissue.

  6. Coronary CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Dewey, Marc [Charite - Universitaetsmedizin Berlin (Germany). Inst. fuer Radiologie

    2009-07-01

    Coronary CT angiography has attained increasing scientific attention at academic institutions and has become a highly accurate diagnostic modality. Extending this knowledge into a practice setting is the purpose of 'Coronary CT Angiography'. This book will assist you in integrating cardiac CT into your daily practice, while also giving an overview of the current technical status and applications. The specific features of scanners from all four main vendors are also presented providing an objective overview of noninvasive coronary angiography using CT. (orig.)

  7. Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Baissalov, R.; Sandison, G.A.; Rewcastle, J.C. [Department of Medical Physics, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 2 Department of Physics and Astronomy, University of Calgary, Calgary T2N 2N4 (Canada); Donnelly, B.J. [Department of Surgery, Tom Baker Cancer Center, Calgary, Canada, T2N 4N2 4 Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Saliken, J.C. [Department of Surgery, Tom Baker Cancer Center, Calgary T2N 4N2 (Canada); Department of Diagnostic Imaging, Foothills Hospital, Calgary T2N 2T7 (Canada); McKinnon, J.G. [Department of Surgery, Foothills Hospital, Calgary T2N 2T7 (Canada); Muldrew, K. [Department of Surgery, Faculty of Medicine, University of Calgary, Calgary T2N 2T7 (Canada)

    2000-05-01

    Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent. (author)

  8. Suppression of high-density artefacts in x-ray CT images using temporal digital subtraction with application to cryotherapy

    International Nuclear Information System (INIS)

    Baissalov, R.; Sandison, G.A.; Rewcastle, J.C.; Donnelly, B.J.; Saliken, J.C.; McKinnon, J.G.; Muldrew, K.

    2000-01-01

    Image guidance in cryotherapy is usually performed using ultrasound. Although not currently in routine clinical use, x-ray CT imaging is an alternative means of guidance that can display the full 3D structure of the iceball, including frozen and unfrozen regions. However, the quality of x-ray CT images is compromised by the presence of high-density streak artefacts. To suppress these artefacts we applied temporal digital subtraction (TDS). This TDS method has the added advantage of improving the grey-scale contrast between frozen and unfrozen tissue in the CT images. Two sets of CT images were taken of a phantom material, cryoprobes and a urethral warmer (UW) before and during the cryoprobe freeze cycle. The high-density artefacts persisted in both image sets. TDS was performed on these two image sets using the corresponding mask image of unfrozen material and the same geometrical configuration of the cryoprobes and the UW. The resultant difference image had a significantly reduced artefact content. Thus TDS can be used to significantly suppress or eliminate high-density CT streak artefacts without reducing the metallic content of the cryoprobes. In vivo study needs to be conducted to establish the utility of this TDS procedure for CT assisted prostate or liver cryotherapy. Applying TDS in x-ray CT guided cryotherapy will facilitate estimation of the number and location of all frozen and unfrozen regions, potentially making cryotherapy safer and less operator dependent. (author)

  9. c-T phase diagram and Landau free energies of (AgAu)55 nanoalloy via neural-network molecular dynamic simulations.

    Science.gov (United States)

    Chiriki, Siva; Jindal, Shweta; Bulusu, Satya S

    2017-10-21

    For understanding the structure, dynamics, and thermal stability of (AgAu) 55 nanoalloys, knowledge of the composition-temperature (c-T) phase diagram is essential due to the explicit dependence of properties on composition and temperature. Experimentally, generating the phase diagrams is very challenging, and therefore theoretical insight is necessary. We use an artificial neural network potential for (AgAu) 55 nanoalloys. Predicted global minimum structures for pure gold and gold rich compositions are lower in energy compared to previous reports by density functional theory. The present work based on c-T phase diagram, surface area, surface charge, probability of isomers, and Landau free energies supports the enhancement of catalytic property of Ag-Au nanoalloys by incorporation of Ag up to 24% by composition in Au nanoparticles as found experimentally. The phase diagram shows that there is a coexistence temperature range of 70 K for Ag 28 Au 27 compared to all other compositions. We propose the power spectrum coefficients derived from spherical harmonics as an order parameter to calculate Landau free energies.

  10. Single-phase dual-energy CT urography in the evaluation of haematuria

    International Nuclear Information System (INIS)

    Ascenti, G.; Mileto, A.; Gaeta, M.; Blandino, A.; Mazziotti, S.; Scribano, E.

    2013-01-01

    Aim: To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic–excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Materials and methods: Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic–excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. Results: The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Conclusion: Single-phase DECT urography with synchronous nephrographic–excretory phase enhancement represents an accurate “all-in-one’’ approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol.

  11. Crackle analysis for chest auscultation and comparison with high-resolution CT findings.

    Science.gov (United States)

    Kawamura, Takeo; Matsumoto, Tsuneo; Tanaka, Nobuyuki; Kido, Shoji; Jiang, Zhongwei; Matsunaga, Naofumi

    2003-01-01

    The purpose of our study was to clarify the correlation between respiratory sounds and the high-resolution CT (HRCT) findings of lung diseases. Respiratory sounds were recorded using a stethoscope in 41 patients with crackles. All had undergone inspiratory and expiratory CT. Subjects included 18 patients with interstitial pneumonia and 23 without interstitial pneumonia. Two parameters, two-cycle duration (2CD) and initial deflection width (IDW) of the "crackle," were induced by time-expanded waveform analysis. Two radiologists independently assessed 11 HRCT findings. An evaluation was carried out to determine whether there was a significant difference in the two parameters between the presence and absence of each HRCT finding. The two parameters of crackles were significantly shorter in the interstitial pneumonia group than the non-interstitial pneumonia group. Ground-glass opacity, honeycombing, lung volume reduction, traction bronchiectasis, centrilobular nodules, emphysematous change, and attenuation and volume change between inspiratory and expiratory CT were correlated with one or two parameters in all patients, whereas the other three findings were not. Among the interstitial pneumonia group, traction bronchiectasis, emphysematous change, and attenuation and volume change between inspiratory and expiratory CT were significantly correlated with one or two parameters. Abnormal respiratory sounds were correlated with some HRCT findings.

  12. Crackle analysis for chest auscultation and comparison with high-resolution CT findings

    International Nuclear Information System (INIS)

    Kawamura, Takeo; Matsumoto, Tsuneo; Tanaka, Nobuyuki; Matsunaga, Naofumi; Kido, Shoji; Jiang Zhongwei

    2003-01-01

    The purpose of our study was to clarify the correlation between respiratory sounds and the high-resolution CT (HRCT) findings of lung diseases. Respiratory sounds were recorded using a stethoscope in 41 patients with crackles. All had undergone inspiratory and expiratory CT. Subjects included 18 patients with interstitial pneumonia and 23 without interstitial pneumonia. Two parameters, two-cycle duration (2CD) and initial deflection width (IDW) of the ''crackle,'' were induced by time-expanded waveform analysis. Two radiologists independently assessed 11 HRCT findings. An evaluation was carried out to determine whether there was a significant difference in the two parameters between the presence and absence of each HRCT finding. The two parameters of crackles were significantly shorter in the interstitial pneumonia group than the non-interstitial pneumonia group. Ground-glass opacity, honeycombing, lung volume reduction, traction bronchiectasis, centrilobular nodules, emphysematous change, and attenuation and volume change between inspiratory and expiratory CT were correlated with one or two parameters in all patients, whereas the other three findings were not. Among the interstitial pneumonia group, traction bronchiectasis, emphysematous change, and attenuation and volume change between inspiratory and expiratory CT were significantly correlated with one or two parameters. Abnormal respiratory sounds were correlated with some HRCT findings. (author)

  13. SU-G-206-07: Dual-Energy CT Inter- and Intra-Scanner Variability Within One Make and Model

    International Nuclear Information System (INIS)

    Jacobsen, M; Wood, C; Cody, D

    2016-01-01

    Purpose: It can be logistically quite difficult to scan patients on the same exact device for their repeat visits in multi-scanner facilities. The reliability between dual-energy CT scanners’ quantitative results is not known, nor is their individual repeatability. Therefore, we evaluated inter- and intra-scanner variability with respect to several key clinical quantitative metrics specific to dual-energy CT. Methods: Eleven identical GE HD-750 CT scanners in a busy clinical environment were used to perform dual-energy (DE) CT scans of a large elliptical quality control (QC) phantom (Gammex, Inc.; Middleton, WI) which contains many standard insert materials. The DE-QC phantom was scanned bi-weekly during 2016; 3 to 4 scans were obtained from each scanner (a total of 35 data sets were used for analysis). Iodine accuracy for the 2mg/ml, 5mg/ml and 15mg/ml rods (from the Iodine(Water) image set) and soft tissue HU (40 HU based on NIST constants) from the 50keV data set were used to assess inter- and intra-scanner variability (standard deviation). Results: Intra-scanner variability average for 2mg/ml Iodine was 0.10 mg/ml (range 0.05–0.15 mg/ml), for 5mg/ml Iodine was 0.12 mg/ml (range 0.07–0.16 mg/ml), for 15 mg/ml Iodine was 0.25 mg/ml (range 0.16–0.37 mg/ml), and for the soft tissue inserts was 2.1 HU (range 1.8–2.6 HU). Inter-scanner variability average for 2mg/ml Iodine was 0.16 mg/ml (range 0.11–0.19 mg/ml), for 5mg/ml Iodine was 0.18 mg/ml (range 0.11–0.22 mg/ml), for 15 mg/ml Iodine was 0.35 mg/ml (range 0.23–0.44 mg/ml), and for the soft tissue inserts was 3.8 HU (range 3.1–4.5 HU). Conclusion: Intra-scanner variability for the iodine and soft tissue inserts averaged 3.1% and 5.2% respectively, and inter-scanner variability for these regions analyzed averaged 5.0% and 9.5%, respectively. Future work will include determination of smallest measurable change and acceptable limits for DE-CT scanner variability over longer time intervals. This

  14. Atypical adenomatous hyperplasia of the lung: correlation between high-resolution CT findings and histopathologic features

    International Nuclear Information System (INIS)

    Kawakami, S.; Takashima, S.; Li, F.; Yang, Z.G.; Maruyama, Y.; Hasegawa, M.; Wang, J.C.; Sone, S.; Honda, T.

    2001-01-01

    We describe herein the CT features of atypical adenomatous hyperplasia (AAH) of the lung and its histopathological characteristics. Among 17,919 individuals screened for lung cancer by CT scanning, ten AAH nodules were detected in nine asymptomatic subjects. On high-resolution CT, the lesions measured from 6 x 6 mm to 15 x 17 mm and their CT number ranged from -500 to -760 HU. The AAHs appeared as round nodules with smooth and distinct borders and showed a ground-glass opacity. Plain chest radiographs failed to identify all lesions. Histopathologically, AAH lesions showed atypical epithelial cell proliferation along slightly thickened alveolar septa. Whereas it is often easy to differentiate these nodules from inflammatory and benign lung lesions, histopathological examination remains at present the only method to differentiate AAH from lung cancers. (orig.)

  15. Atypical adenomatous hyperplasia of the lung: correlation between high-resolution CT findings and histopathologic features

    Energy Technology Data Exchange (ETDEWEB)

    Kawakami, S.; Takashima, S.; Li, F.; Yang, Z.G.; Maruyama, Y.; Hasegawa, M.; Wang, J.C. [Dept. of Radiology, Shinshu University School of Medicine, Matsumoto (Japan); Sone, S. [Dept. of Radiology, Shinshu University School of Medicine, Matsumoto (Japan); Azumi General Hospital, Ikeda, Nagano (Japan); Honda, T. [Dept. of Laboratory Medicine, Shinshu University School of Medicine, Matsumoto (Japan)

    2001-05-01

    We describe herein the CT features of atypical adenomatous hyperplasia (AAH) of the lung and its histopathological characteristics. Among 17,919 individuals screened for lung cancer by CT scanning, ten AAH nodules were detected in nine asymptomatic subjects. On high-resolution CT, the lesions measured from 6 x 6 mm to 15 x 17 mm and their CT number ranged from -500 to -760 HU. The AAHs appeared as round nodules with smooth and distinct borders and showed a ground-glass opacity. Plain chest radiographs failed to identify all lesions. Histopathologically, AAH lesions showed atypical epithelial cell proliferation along slightly thickened alveolar septa. Whereas it is often easy to differentiate these nodules from inflammatory and benign lung lesions, histopathological examination remains at present the only method to differentiate AAH from lung cancers. (orig.)

  16. High-resolution CT with histopathological correlates of the classic metaphyseal lesion of infant abuse

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Andy; Kleinman, Paul K. [Boston Children' s Hospital, Department of Radiology, Boston, MA (United States); McDonald, Anna G. [Office of the Chief Medical Examiner, Boston, MA (United States); Rosenberg, Andrew E. [University of Miami Hospital, Department of Pathology, Miami, FL (United States); Gupta, Rajiv [Massachusetts General Hospital, Department of Radiology, Boston, MA (United States)

    2014-02-15

    The classic metaphyseal lesion (CML) is a common high specificity indicator of infant abuse and its imaging features have been correlated histopathologically in infant fatalities. High-resolution CT imaging and histologic correlates were employed to (1) characterize the normal infant anatomy surrounding the chondro-osseous junction, and (2) confirm the 3-D model of the CML previously inferred from planar radiography and histopathology. Long bone specimens from 5 fatally abused infants, whose skeletal survey showed definite or suspected CMLs, were studied postmortem. After skeletal survey, selected specimens were resected and imaged with high-resolution digital radiography. They were then scanned with micro-CT (isotropic resolution of 45 μm{sup 3}) or with high-resolution flat-panel CT (isotropic resolutions of 200 μm{sup 3}). Visualization of the bony structures was carried out using image enhancement, segmentation and isosurface extraction, together with volume rendering and multiplanar reformatting. These findings were then correlated with histopathology. Study of normal infant bone clarifies the 3-D morphology of the subperiosteal bone collar (SPBC) and the radiographic zone of provisional calcification (ZPC). Studies on specimens with CML confirm that this lesion is a fracture extending in a planar fashion through the metaphysis, separating a mineralized fragment. This disk-like mineralized fragment has two components: (1) a thick peripheral component encompassing the SPBC; and (2) a thin central component comprised predominantly of the radiologic ZPC. By manipulating the 3-D model, the varying appearances of the CML are displayed. High-resolution CT coupled with histopathology provides elucidation of the morphology of the CML, a strong indicator of infant abuse. This new information may prove useful in assessing the biomechanical factors that produce this strong indicator of abusive assaults in infants. (orig.)

  17. High-resolution CT with histopathological correlates of the classic metaphyseal lesion of infant abuse

    International Nuclear Information System (INIS)

    Tsai, Andy; Kleinman, Paul K.; McDonald, Anna G.; Rosenberg, Andrew E.; Gupta, Rajiv

    2014-01-01

    The classic metaphyseal lesion (CML) is a common high specificity indicator of infant abuse and its imaging features have been correlated histopathologically in infant fatalities. High-resolution CT imaging and histologic correlates were employed to (1) characterize the normal infant anatomy surrounding the chondro-osseous junction, and (2) confirm the 3-D model of the CML previously inferred from planar radiography and histopathology. Long bone specimens from 5 fatally abused infants, whose skeletal survey showed definite or suspected CMLs, were studied postmortem. After skeletal survey, selected specimens were resected and imaged with high-resolution digital radiography. They were then scanned with micro-CT (isotropic resolution of 45 μm 3 ) or with high-resolution flat-panel CT (isotropic resolutions of 200 μm 3 ). Visualization of the bony structures was carried out using image enhancement, segmentation and isosurface extraction, together with volume rendering and multiplanar reformatting. These findings were then correlated with histopathology. Study of normal infant bone clarifies the 3-D morphology of the subperiosteal bone collar (SPBC) and the radiographic zone of provisional calcification (ZPC). Studies on specimens with CML confirm that this lesion is a fracture extending in a planar fashion through the metaphysis, separating a mineralized fragment. This disk-like mineralized fragment has two components: (1) a thick peripheral component encompassing the SPBC; and (2) a thin central component comprised predominantly of the radiologic ZPC. By manipulating the 3-D model, the varying appearances of the CML are displayed. High-resolution CT coupled with histopathology provides elucidation of the morphology of the CML, a strong indicator of infant abuse. This new information may prove useful in assessing the biomechanical factors that produce this strong indicator of abusive assaults in infants. (orig.)

  18. CT imaging of the internal human ear: Test of a high resolution scanner

    Energy Technology Data Exchange (ETDEWEB)

    Bettuzzi, M., E-mail: matteo.bettuzzi@unibo.it [Department of Physics, University of Bologna and National Institute of Nuclear Physics Section of Bologna (Italy); Brancaccio, R.; Morigi, M.P. [Department of Physics, University of Bologna and National Institute of Nuclear Physics Section of Bologna (Italy); Gallo, A. [Medicine Faculty, Magna Graecia University, Catanzaro and INFN Cosenza (Italy); Strolin, S.; Casali, F. [Department of Physics, University of Bologna and National Institute of Nuclear Physics Section of Bologna (Italy); Lamanna, Ernesto [Medicine Faculty, Magna Graecia University, Catanzaro and INFN Cosenza (Italy); Ariu, Marilu [CEFLA Dental Group, Imola (Italy)

    2011-08-21

    During the course of 2009, in the framework of a project supported by the National Institute of Nuclear Physics, a number of tests were carried out at the Department of Physics of the University of Bologna in order to achieve a good quality CT scan of the internal human ear. The work was carried out in collaboration with the local 'S. Orsola' Hospital in Bologna and a company (CEFLA) already involved in the production and commercialization of a CT scanner dedicated to dentistry. A laboratory scanner with a simple concept detector (CCD camera-lens-mirror-scintillator) was used to see to what extent it was possible to enhance the quality of a conventional CT scanner when examining the internal human ear. To test the system, some conventional measurements were made, such as the spatial resolution calculation with the MTF and dynamic range evaluation. Different scintillators were compared to select the most suitable for the purpose. With 0.5 mm thick structured cesium iodide and a field of view of 120x120 mm{sup 2}, a spatial resolution of 6.5l p/mm at 5% MTF was obtained. The CT of a pair of human head phantoms was performed at an energy of 120 kVp. The first phantom was a rough representation of the human head shape, with soft tissue made of coarse slabs of Lucite. Some inserts, like small aluminum cylinders and cubes, with 1 mm diameter drilled holes, were used to simulate the channels that one finds inside the human inner ear. The second phantom is a plastic PVC fused head with a real human cranium inside. The bones in the cranium are well conserved and the inner ear features, such as the cochlea and semicircular channels, are clearly detectable. After a number of CT tests we obtained good results as far as structural representation and channel detection are concerned. Some images of the 3D rendering of the CT volume are shown below. The doctors of the local hospital who followed our experimentation expressed their satisfaction. The CT was compared to a

  19. The value of energy spectral CT in the differential diagnosis between benign and malignant soft tissue masses of the musculoskeletal system.

    Science.gov (United States)

    Sun, Xin; Shao, Xiaodong; Chen, Haisong

    2015-06-01

    To explore the value of energy spectral CT in the differential diagnosis between benign and malignant tumor of the musculoskeletal system. Energy spectral CT scan was performed on 100 patients with soft tissue mass caused by musculoskeletal tumors found by MRI. Solid areas with homogenous density were chosen as region of interests (ROI), avoiding necrosis, hemorrhage and calcification region. Select the optimal keV on single energy images, and then the keV-CT curve was automatically generated. All 100 cases of tumors proved by histological examination were divided into four groups, 38 cases were in benign group, 10 cases in borderline group, 49 cases in malignant group, and 3 cases of lipoma (that were analyzed separately since its curve was arc shaped, significantly different from other curves). The formula used to calculate the slope of spectral curve was as follows: slope=(Hu40 keV-Hu80 keV)/40. As the slope was steep within the range of 40-80 keV based on preliminary observations, 40 keV and 80 keV were used as the reference points to calculate the slope value of the energy spectral curve. Kruskal-Wallis rank sum test was applied for statistical analysis, and Pbenign and malignant group, benign and borderline group were of statistical significance (Pbenign and malignant tumor of the musculoskeletal system. Arc shaped curve is a specific sign for tumors containing abundant fat. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  20. TU-G-207-01: CT Imaging Using Energy-Sensitive Photon-Counting Detectors

    International Nuclear Information System (INIS)

    Taguchi, K.

    2015-01-01

    Last few years has witnessed the development of novel of X-ray imaging modalities, such as spectral CT, phase contrast CT, and X-ray acoustic/fluorescence/luminescence imaging. This symposium will present the recent advances of these emerging X-ray imaging modalities and update the attendees with knowledge in various related topics, including X-ray photon-counting detectors, X-ray physics underlying the emerging applications beyond the traditional X-ray imaging, image reconstruction for the novel modalities, characterization and evaluation of the systems, and their practical implications. In addition, the concept and practical aspects of X-ray activatable targeted nanoparticles for molecular X-ray imaging will be discussed in the context of X-ray fluorescence and luminescence CT. Learning Objectives: Present background knowledge of various emerging X-ray imaging techniques, such as spectral CT, phase contrast CT and X-ray fluorescence/luminescence CT. Discuss the practical need, technical aspects and current status of the emerging X-ray imaging modalities. Describe utility and future impact of the new generation of X-ray imaging applications

  1. The Effect of Therapy Oriented CT in Radiation Therapy Planning

    International Nuclear Information System (INIS)

    Kim, Sung Kyu; Shin, Sei One; Kim, Myung Se

    1987-01-01

    The success of radiation therapy depends on exact treatment of the tumor with significant high dose for maximizing local control and excluding the normal tissues for minimizing unwanted complications. To achieve these goals, correct estimation of target volume in three dimension, exact dose distribution in tumor and normal critical structures and correction of tissue inhomogeneity are required. The effect of therapy oriented CT (planning CT) were compared with conventional simulation method in necessity of planning change, set dose, and proper distribution of tumor dose. Of 365 new patients examined, planning CT was performed in 104 patients (28%). Treatment planning was changed in 47% of head and neck tumor, 79% of intrathoracic tumor and 63% of abdominal tumor. In breast cancer and musculoskeletal tumors, planning CT was recommended for selection of adequate energy and calculation of exact dose to critical structures such as kidney or spinal cord. The average difference of tumor doses between CT planning and conventional simulation was 10% in intrathoracic and intra-abdominal tumors but 20% in head and neck tumors which suggested that tumor dose may be overestimated in conventional simulation. Although some limitations and disadvantages including the cost and irradiation during CT are still criticizing, our study showed that CT planning is very helpful in radiotherapy planning

  2. Three-dimensional monochromatic x-ray CT

    Science.gov (United States)

    Saito, Tsuneo; Kudo, Hiroyuki; Takeda, Tohoru; Itai, Yuji; Tokumori, Kenji; Toyofuku, Fukai; Hyodo, Kazuyuki; Ando, Masami; Nishimura, Ktsuyuki; Uyama, Chikao

    1995-08-01

    In this paper, we describe a 3D computed tomography (3D CT) using monochromatic x-rays generated by synchrotron radiation, which performs a direct reconstruction of 3D volume image of an object from its cone-beam projections. For the develpment of 3D CT, scanning orbit of x-ray source to obtain complete 3D information about an object and corresponding 3D image reconstruction algorithm are considered. Computer simulation studies demonstrate the validities of proposed scanning method and reconstruction algorithm. A prototype experimental system of 3D CT was constructed. Basic phantom examinations and specific material CT image by energy subtraction obtained in this experimental system are shown.

  3. Microwave Ablation of Pulmonary Malignancies Using a Novel High-energy Antenna System

    Energy Technology Data Exchange (ETDEWEB)

    Little, Mark W.; Chung, Daniel; Boardman, Philip; Gleeson, Fergus V.; Anderson, Ewan M., E-mail: ewan.anderson@ouh.nhs.uk [Churchill Hospital, Department of Radiology (United Kingdom)

    2013-04-15

    To evaluate the technical success, safety, and imaging follow-up of malignant pulmonary nodules treated with a novel high-energy percutaneous microwave ablation (MWA) system. Between July 2010 and September 2011, a total of 23 patients, 12 men, mean age 68 (range 30-87) years with 29 pulmonary malignancies of median diameter 19 (range 8-57) mm, underwent computed tomography (CT)-guided MWA with a 16G microwave needle antenna enabling power up to 180 W. Technical success was defined as needle placement in the intended lesion without death or serious injury. Adequacy of ablation was assessed at 24 h on contrast-enhanced CT. Circumferential solid or ground glass opacification >5 mm was used to define an ideal ablation. Local tumor recurrence was assessed at 1, 3, and 6 months after ablation on contrast-enhanced CT. MWA was technically successful in 93 % (n = 27). Mean ablation duration was 3.6 (range 1-9) min. Ten patients (43 %) developed a pneumothorax as a result of the MWA; only 3 (13 %) required placement of a chest drain. Thirty-day mortality rate was 0 %. The mean hospital stay was 1.5 (range 1-7) days. A total of 22 lesions (75 %) were surrounded by {>=}5 mm ground glass or solid opacification after the procedure. At a median follow-up of 6 months, local recurrence was identified in 3 out of 26 lesions, giving a local control rate of 88 %. MWA using a high-power antenna of pulmonary malignancies is safe, technically achievable, and enables fast ablation times.

  4. Focal airtrapping at expiratory high-resolution CT: comparison with pulmonary function tests

    International Nuclear Information System (INIS)

    Kauczor, H.U.; Hast, J.; Heussel, C.P.; Mildenberger, P.; Thelen, M.; Schlegel, J.

    2000-01-01

    This study was undertaken to determine prevalence, extent, and severity of focal airtrapping at expiratory high-resolution CT, and to compare focal airtrapping with age, gender, pulmonary function tests, and blood gas analysis. Two-hundred seventeen patients with and without pulmonary disease underwent paired inspiratory/expiratory high-resolution CT. Six scan pairs with corresponding scan levels were visually assessed for focal - not diffuse - airtrapping using a four-point scale. Pulmonary function tests and blood gas analysis were available for correlation in all patients (mean interval 5 days). Focal airtrapping with lower lung predominance was observed in 80 % of patients. Twenty-six of 26 patients with restrictive lung function impairment exhibited focal airtrapping (mean score 2.4), whereas only 72 of 98 (74 %) patients with obstruction did (mean score 1.5; p < 0.05). Fifty-eight of 70 (83 %) patients with normal lung function (mean score 1.8) and 19 of 23 (83 %) patients with mixed impairment (mean score 1.8) had focal airtrapping. Focal airtrapping showed negative correlations with static lung volumes (-0.27 to -0.37; p < 0.001) in all patients and moderate positive correlations with dynamic parameters (0.3-0.4; p < 0.001) in patients with obstruction. No significant correlations were found with age, gender, and blood gas analysis. Visual assessment of focal - not diffuse - airtrapping at expiratory high-resolution CT does not correlate with physiological evidence of obstruction as derived from pulmonary function tests since the perception of focal airtrapping requires an adequate expiratory increase in lung density. (orig.)

  5. Low-dose Dental-CT

    International Nuclear Information System (INIS)

    Gahleitner, A.; Imhof, H.; Homolka, P.; Fuerhauser, R.; Freudenthaler, J.; Watzek, G.

    2000-01-01

    Dental-CT is a relatively new, increasingly used investigation technique in dental radiology. Several authors have stated that the indication for Dental-CT has to be chosen on a strict basis, due to high dose values. This article describes the technique of performing dental-CT and calculates the effective dose based on published data and own measurements as well as the dose reduction potential to achieve an optimized protocol for Dental-CT investigations. (orig.) [de

  6. Ultra-high resolution flat-panel volume CT: fundamental principles, design architecture, and system characterization

    International Nuclear Information System (INIS)

    Gupta, Rajiv; Brady, Tom; Grasruck, Michael; Suess, Christoph; Schmidt, Bernhard; Stierstorfer, Karl; Popescu, Stefan; Flohr, Thomas; Bartling, Soenke H.

    2006-01-01

    Digital flat-panel-based volume CT (VCT) represents a unique design capable of ultra-high spatial resolution, direct volumetric imaging, and dynamic CT scanning. This innovation, when fully developed, has the promise of opening a unique window on human anatomy and physiology. For example, the volumetric coverage offered by this technology enables us to observe the perfusion of an entire organ, such as the brain, liver, or kidney, tomographically (e.g., after a transplant or ischemic event). By virtue of its higher resolution, one can directly visualize the trabecular structure of bone. This paper describes the basic design architecture of VCT. Three key technical challenges, viz., scatter correction, dynamic range extension, and temporal resolution improvement, must be addressed for successful implementation of a VCT scanner. How these issues are solved in a VCT prototype and the modifications necessary to enable ultra-high resolution volumetric scanning are described. The fundamental principles of scatter correction and dose reduction are illustrated with the help of an actual prototype. The image quality metrics of this prototype are characterized and compared with a multi-detector CT (MDCT). (orig.)

  7. Ultra-high resolution flat-panel volume CT: fundamental principles, design architecture, and system characterization

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Rajiv; Brady, Tom [Massachusetts General Hospital, Department of Radiology, Founders House, FND-2-216, Boston, MA (United States); Grasruck, Michael; Suess, Christoph; Schmidt, Bernhard; Stierstorfer, Karl; Popescu, Stefan; Flohr, Thomas [Siemens Medical Solutions, Forchheim (Germany); Bartling, Soenke H. [Hannover Medical School, Department of Neuroradiology, Hannover (Germany)

    2006-06-15

    Digital flat-panel-based volume CT (VCT) represents a unique design capable of ultra-high spatial resolution, direct volumetric imaging, and dynamic CT scanning. This innovation, when fully developed, has the promise of opening a unique window on human anatomy and physiology. For example, the volumetric coverage offered by this technology enables us to observe the perfusion of an entire organ, such as the brain, liver, or kidney, tomographically (e.g., after a transplant or ischemic event). By virtue of its higher resolution, one can directly visualize the trabecular structure of bone. This paper describes the basic design architecture of VCT. Three key technical challenges, viz., scatter correction, dynamic range extension, and temporal resolution improvement, must be addressed for successful implementation of a VCT scanner. How these issues are solved in a VCT prototype and the modifications necessary to enable ultra-high resolution volumetric scanning are described. The fundamental principles of scatter correction and dose reduction are illustrated with the help of an actual prototype. The image quality metrics of this prototype are characterized and compared with a multi-detector CT (MDCT). (orig.)

  8. Pulmonary tuberculosis with airspace consolidation vs mycoplasma pneumonia in adults: high-resolution CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Chull Hee; Choi, Gyo Chang; Park, Jai Soung; Hwang, Jung Hwa; Kim, Kyung Rak; Im, Han Haek; Kim, Dae Ho; Choi, Deuk Lin [Soonchunghyang Univ. College of Medicine, Seoul (Korea, Republic of)

    1997-02-01

    To analyse and compare high-resolution CT findings of pulmonary tuberculosis with consolidation and mycoplasma pneumonia. Twenty patients with pulmonary tuberculosis [confirmed by sputum culture (n=9) and bronchoscopic biopsy (n=11)] and airspace consolidation on high-resolution CT and 17 patients with mycoplasma pneumonia, confirmed by serologic test, were included in this study. High-resolution CT findings were analyzed in terms of ground-glass opacities, distribution of consolidation, type of nodules, cavities, interlobular septal thickening, bronchial dilatations, bronchial wall thickening and pleural effusion. In patients with tuberculosis, average age was 33.5 years (range, 20-67); in those with mycoplasma pneumonia it was 32.5 years (range, 17-74). Segmental and subsegmental distributions were most common in both diseases; the preferred site of consolidation was different, however; for tuberculosis it was the upper lobes (13 cases, 65%; bilateral involvement, 7 cases); for mycoplasma pneumonia it was the lower lobes (11 cases, 64.7%). Non-segmental (diffuse and random) distribution of ground-glass opacities were seen in two patients(11.8%) with mycoplasma pneumonia. Centrilobular nodules, branching linear opacities and alveolar nodules were not different in both diseases, but there were nodules above 10mm in 14 cases of tuberculosis and in only one case of mycoplasma pneumonia. Tree-in-bud appearances were seen in five cases of tuberculosis. Cavities without air-fluid level were noted in ten cases of tuberculosis. Other interlobular septal thickening, bronchial wall thickening, bronchial dilatation and pleural effusion were not different in both diseases. There was considerable overlap between high resolution CT findings of tuberculosis with airspace consolidation and those of mycoplasma pneumonia. The location of consolidation, type of nodules, and the presence of tree-in-bud appearance and cavities help in the differentiation of the two diseases, however.

  9. Pulmonary tuberculosis with airspace consolidation vs mycoplasma pneumonia in adults: high-resolution CT findings

    International Nuclear Information System (INIS)

    Cha, Chull Hee; Choi, Gyo Chang; Park, Jai Soung; Hwang, Jung Hwa; Kim, Kyung Rak; Im, Han Haek; Kim, Dae Ho; Choi, Deuk Lin

    1997-01-01

    To analyse and compare high-resolution CT findings of pulmonary tuberculosis with consolidation and mycoplasma pneumonia. Twenty patients with pulmonary tuberculosis [confirmed by sputum culture (n=9) and bronchoscopic biopsy (n=11)] and airspace consolidation on high-resolution CT and 17 patients with mycoplasma pneumonia, confirmed by serologic test, were included in this study. High-resolution CT findings were analyzed in terms of ground-glass opacities, distribution of consolidation, type of nodules, cavities, interlobular septal thickening, bronchial dilatations, bronchial wall thickening and pleural effusion. In patients with tuberculosis, average age was 33.5 years (range, 20-67); in those with mycoplasma pneumonia it was 32.5 years (range, 17-74). Segmental and subsegmental distributions were most common in both diseases; the preferred site of consolidation was different, however; for tuberculosis it was the upper lobes (13 cases, 65%; bilateral involvement, 7 cases); for mycoplasma pneumonia it was the lower lobes (11 cases, 64.7%). Non-segmental (diffuse and random) distribution of ground-glass opacities were seen in two patients(11.8%) with mycoplasma pneumonia. Centrilobular nodules, branching linear opacities and alveolar nodules were not different in both diseases, but there were nodules above 10mm in 14 cases of tuberculosis and in only one case of mycoplasma pneumonia. Tree-in-bud appearances were seen in five cases of tuberculosis. Cavities without air-fluid level were noted in ten cases of tuberculosis. Other interlobular septal thickening, bronchial wall thickening, bronchial dilatation and pleural effusion were not different in both diseases. There was considerable overlap between high resolution CT findings of tuberculosis with airspace consolidation and those of mycoplasma pneumonia. The location of consolidation, type of nodules, and the presence of tree-in-bud appearance and cavities help in the differentiation of the two diseases, however

  10. Single-phase dual-energy CT urography in the evaluation of haematuria.

    Science.gov (United States)

    Ascenti, G; Mileto, A; Gaeta, M; Blandino, A; Mazziotti, S; Scribano, E

    2013-02-01

    To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic-excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic-excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Single-phase DECT urography with synchronous nephrographic-excretory phase enhancement represents an accurate "all-in-one'' approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol. Copyright © 2012 The Royal College of Radiologists. All rights reserved.

  11. Calcium scoring with dual-energy CT in men and women: an anthropomorphic phantom study

    Science.gov (United States)

    Li, Qin; Liu, Songtao; Myers, Kyle; Gavrielides, Marios A.; Zeng, Rongping; Sahiner, Berkman; Petrick, Nicholas

    2016-03-01

    This work aimed to quantify and compare the potential impact of gender differences on coronary artery calcium scoring with dual-energy CT. An anthropomorphic thorax phantom with four synthetic heart vessels (diameter 3-4.5 mm: female/male left main and left circumflex artery) were scanned with and without female breast plates. Ten repeat scans were acquired in both single- and dual-energy modes and reconstructed at six reconstruction settings: two slice thicknesses (3 mm, 0.6 mm) and three reconstruction algorithms (FBP, IR3, IR5). Agatston and calcium volume scores were estimated from the reconstructed data using a segmentation-based approach. Total calcium score (summation of four vessels), and male/female calcium scores (summation of male/female vessels scanned in phantom without/with breast plates) were calculated accordingly. Both Agatston and calcium volume scores were found comparable between single- and dual-energy scans (Pearson r= 0.99, pwomen and men in calcium scoring, and for standardizing imaging protocols for improved gender-specific calcium scoring.

  12. A framelet-based iterative maximum-likelihood reconstruction algorithm for spectral CT

    Science.gov (United States)

    Wang, Yingmei; Wang, Ge; Mao, Shuwei; Cong, Wenxiang; Ji, Zhilong; Cai, Jian-Feng; Ye, Yangbo

    2016-11-01

    Standard computed tomography (CT) cannot reproduce spectral information of an object. Hardware solutions include dual-energy CT which scans the object twice in different x-ray energy levels, and energy-discriminative detectors which can separate lower and higher energy levels from a single x-ray scan. In this paper, we propose a software solution and give an iterative algorithm that reconstructs an image with spectral information from just one scan with a standard energy-integrating detector. The spectral information obtained can be used to produce color CT images, spectral curves of the attenuation coefficient μ (r,E) at points inside the object, and photoelectric images, which are all valuable imaging tools in cancerous diagnosis. Our software solution requires no change on hardware of a CT machine. With the Shepp-Logan phantom, we have found that although the photoelectric and Compton components were not perfectly reconstructed, their composite effect was very accurately reconstructed as compared to the ground truth and the dual-energy CT counterpart. This means that our proposed method has an intrinsic benefit in beam hardening correction and metal artifact reduction. The algorithm is based on a nonlinear polychromatic acquisition model for x-ray CT. The key technique is a sparse representation of iterations in a framelet system. Convergence of the algorithm is studied. This is believed to be the first application of framelet imaging tools to a nonlinear inverse problem.

  13. Noise-optimized virtual monoenergetic images and iodine maps for the detection of venous thrombosis in second-generation dual-energy CT (DECT): an ex vivo phantom study

    International Nuclear Information System (INIS)

    Bongers, Malte N.; Schabel, Christoph; Tsiflikas, Ilias; Ketelsen, Dominik; Mangold, Stefanie; Claussen, Claus D.; Nikolaou, Konstantin; Thomas, Christoph; Krauss, Bernhard

    2015-01-01

    Deep venous thrombosis (DVT) can be difficult to detect using CT due to poor and heterogeneous contrast. Dual-energy CT (DECT) allows iodine contrast optimization using noise-optimized monoenergetic extrapolations (MEIs) and iodine maps (IMs). Our aim was to assess whether MEI and IM could improve the delineation of thrombotic material within iodine-enhanced blood compared to single-energy CT (SECT). Six vessel phantoms, including human thrombus and contrast media-enhanced blood and one phantom without contrast, were placed in an attenuation phantom and scanned with DECT 100/140 kV and SECT 120 kV. IM, virtual non-contrast images (VNC), mixed images, and MEI were calculated. Attenuation of thrombi and blood were measured. Contrast and contrast-to-noise-ratios (CNRs) were calculated and compared among IM, VNC, mixed images, MEI, and SECT using paired t tests. MEI40keV and IM showed significantly higher contrast and CNR than SE120kV from high to intermediate iodine concentrations (contrast:pMEI40keV < 0.002,pIM < 0.005;CNR:pMEI40keV < 0.002,pIM < 0.004). At low iodine concentrations, MEI190keV and VNC images showed significantly higher contrast and CNR than SE120kV with inverted contrasts (contrast:pMEI190keV < 0.008,pVNC < 0.002;CNR:pMEI190keV < 0.003,pVNC < 0.002). Noise-optimized MEI and IM provide significantly higher contrast and CNR in the delineation of thrombosis compared to SECT, which may facilitate the detection of DVT in difficult cases. circle Poor contrast makes it difficult to detect thrombosis in CT. (orig.)

  14. Noise-optimized virtual monoenergetic images and iodine maps for the detection of venous thrombosis in second-generation dual-energy CT (DECT): an ex vivo phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Bongers, Malte N.; Schabel, Christoph; Tsiflikas, Ilias; Ketelsen, Dominik; Mangold, Stefanie; Claussen, Claus D.; Nikolaou, Konstantin; Thomas, Christoph [University Hospital of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Krauss, Bernhard [Siemens AG, Healthcare Sector, Forchheim (Germany)

    2015-06-01

    Deep venous thrombosis (DVT) can be difficult to detect using CT due to poor and heterogeneous contrast. Dual-energy CT (DECT) allows iodine contrast optimization using noise-optimized monoenergetic extrapolations (MEIs) and iodine maps (IMs). Our aim was to assess whether MEI and IM could improve the delineation of thrombotic material within iodine-enhanced blood compared to single-energy CT (SECT). Six vessel phantoms, including human thrombus and contrast media-enhanced blood and one phantom without contrast, were placed in an attenuation phantom and scanned with DECT 100/140 kV and SECT 120 kV. IM, virtual non-contrast images (VNC), mixed images, and MEI were calculated. Attenuation of thrombi and blood were measured. Contrast and contrast-to-noise-ratios (CNRs) were calculated and compared among IM, VNC, mixed images, MEI, and SECT using paired t tests. MEI40keV and IM showed significantly higher contrast and CNR than SE120kV from high to intermediate iodine concentrations (contrast:pMEI40keV < 0.002,pIM < 0.005;CNR:pMEI40keV < 0.002,pIM < 0.004). At low iodine concentrations, MEI190keV and VNC images showed significantly higher contrast and CNR than SE120kV with inverted contrasts (contrast:pMEI190keV < 0.008,pVNC < 0.002;CNR:pMEI190keV < 0.003,pVNC < 0.002). Noise-optimized MEI and IM provide significantly higher contrast and CNR in the delineation of thrombosis compared to SECT, which may facilitate the detection of DVT in difficult cases. circle Poor contrast makes it difficult to detect thrombosis in CT. (orig.)

  15. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    International Nuclear Information System (INIS)

    Sun, Hao; Hou, Xin-Yi; Xue, Hua-Dan; Li, Xiao-Guang; Jin, Zheng-Yu; Qian, Jia-Ming; Yu, Jian-Chun; Zhu, Hua-Dong

    2015-01-01

    Highlights: • GIB is a common gastrointestinal emergency with a high mortality rate. • Detection and localization of GIB source are important for imaging modality. • DSDECTA using a dual-phase scan protocol is clinically feasible. • DSDECTA with VNE and iodine map images can diagnose the active GIB source accurately. • DSDECTA can reduce radiation dose compared with conventional CT examination in GIB. - Abstract: Objectives: To evaluate the clinical feasibility of dual-source dual-energy CT angiography (DSDECTA) with virtual non-enhanced images and iodine map for active gastrointestinal bleeding (GIB). Methods: From June 2010 to December 2012, 112 consecutive patients with clinical signs of active GIB underwent DSDECTA with true non-enhanced (TNE), arterial phase with single-source mode, and portal-venous phase with dual-energy mode (100 kVp/230 mAs and Sn 140 kVp/178 mAs). Virtual non-enhanced CT (VNE) image sets and iodine map were reformatted from ‘Liver VNC’ software. The mean CT number, noise, signal to noise ratio (SNR), image quality and radiation dose were compared between TNE and VNE image sets. Two radiologists, blinded to clinical data, interpreted images from DSDECTA with TNE (protocol 1), and DSDECTA with VNE and iodine map (protocol 2) respectively, with discordant interpretation resolved by consensus. The standards of reference included digital subtraction angiography, endoscopy, surgery, or final pathology reports. Receiver–operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated for CT protocols 1 and 2, respectively. Results: There was no significant difference in mean CT numbers of all organs (including liver, pancreas, spleen, kidney, abdominal aorta, and psoas muscle) (P > 0.05). Lower noise and higher SNR were found on VNE images than TNE images (P < 0.05). Image quality of VNE was lower than that of TNE without significant difference (P > 0.05). The active GIB source was identified

  16. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hao, E-mail: sunhao_robert@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Hou, Xin-Yi, E-mail: hxy_pumc@126.com [Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing (China); Xue, Hua-Dan, E-mail: bjdanna95@hotmail.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Li, Xiao-Guang, E-mail: xglee88@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Jin, Zheng-Yu, E-mail: zhengyu_jin@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Qian, Jia-Ming, E-mail: qjiaming57@gmail.com [Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Yu, Jian-Chun, E-mail: yu-jch@163.com [Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Zhu, Hua-Dong, E-mail: huadongzhu@hotmail.com [Department of Emergency, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China)

    2015-05-15

    Highlights: • GIB is a common gastrointestinal emergency with a high mortality rate. • Detection and localization of GIB source are important for imaging modality. • DSDECTA using a dual-phase scan protocol is clinically feasible. • DSDECTA with VNE and iodine map images can diagnose the active GIB source accurately. • DSDECTA can reduce radiation dose compared with conventional CT examination in GIB. - Abstract: Objectives: To evaluate the clinical feasibility of dual-source dual-energy CT angiography (DSDECTA) with virtual non-enhanced images and iodine map for active gastrointestinal bleeding (GIB). Methods: From June 2010 to December 2012, 112 consecutive patients with clinical signs of active GIB underwent DSDECTA with true non-enhanced (TNE), arterial phase with single-source mode, and portal-venous phase with dual-energy mode (100 kVp/230 mAs and Sn 140 kVp/178 mAs). Virtual non-enhanced CT (VNE) image sets and iodine map were reformatted from ‘Liver VNC’ software. The mean CT number, noise, signal to noise ratio (SNR), image quality and radiation dose were compared between TNE and VNE image sets. Two radiologists, blinded to clinical data, interpreted images from DSDECTA with TNE (protocol 1), and DSDECTA with VNE and iodine map (protocol 2) respectively, with discordant interpretation resolved by consensus. The standards of reference included digital subtraction angiography, endoscopy, surgery, or final pathology reports. Receiver–operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated for CT protocols 1 and 2, respectively. Results: There was no significant difference in mean CT numbers of all organs (including liver, pancreas, spleen, kidney, abdominal aorta, and psoas muscle) (P > 0.05). Lower noise and higher SNR were found on VNE images than TNE images (P < 0.05). Image quality of VNE was lower than that of TNE without significant difference (P > 0.05). The active GIB source was identified

  17. Interferometric phase-contrast X-ray CT imaging of VX2 rabbit cancer at 35keV X-ray energy

    Science.gov (United States)

    Takeda, Tohoru; Wu, Jin; Tsuchiya, Yoshinori; Yoneyama, Akio; Lwin, Thet-Thet; Hyodo, Kazuyuki; Itai, Yuji

    2004-05-01

    Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

  18. Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition

    International Nuclear Information System (INIS)

    Bruder, H; Raupach, R; Sunnegardh, J; Allmendinger, T; Klotz, E; Stierstorfer, K; Flohr, T

    2015-01-01

    In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta.Examples: in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectral dataset of the same body region provides additional quanta which might be utilized to improve SNR of each spectral component. Perfusion CT is a high dose application, and dose reduction is highly desirable. However, a meaningful evaluation of perfusion parameters might be impaired by noisy time frames. On the other hand, the SNR of the average of all time frames is extremely high.In redundant CT acquisitions, multiple image datasets can be reconstructed and averaged to composite image data. These composite image data, however, might be compromised with respect to contrast resolution and/or spatial resolution and/or temporal resolution. These observations bring us to the idea of transferring high SNR of composite image data to low SNR ‘source’ image data, while maintaining their resolution.It has been shown that the noise characteristics of CT image data can be improved by iterative reconstruction (Popescu et al 2012 Book of Abstracts, 2nd CT Meeting (Salt Lake City, UT) p 148). In case of data dependent Gaussian noise it can be modelled with image-based iterative reconstruction at least in an approximate manner (Bruder et al 2011 Proc. SPIE 7961 79610J).We present a generalized update equation in image space, consisting of a linear combination of the previous update, a correction term which is constrained by the source image data, and a regularization prior, which is initialized by the composite image data. This iterative reconstruction approach we call bimodal reconstruction (BMR).Based on simulation data it is shown that BMR can improve low contrast detectability, substantially reduces the noise power and has the potential to recover spatial

  19. Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition

    Science.gov (United States)

    Bruder, H.; Raupach, R.; Sunnegardh, J.; Allmendinger, T.; Klotz, E.; Stierstorfer, K.; Flohr, T.

    2015-11-01

    In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples: in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectral dataset of the same body region provides additional quanta which might be utilized to improve SNR of each spectral component. Perfusion CT is a high dose application, and dose reduction is highly desirable. However, a meaningful evaluation of perfusion parameters might be impaired by noisy time frames. On the other hand, the SNR of the average of all time frames is extremely high. In redundant CT acquisitions, multiple image datasets can be reconstructed and averaged to composite image data. These composite image data, however, might be compromised with respect to contrast resolution and/or spatial resolution and/or temporal resolution. These observations bring us to the idea of transferring high SNR of composite image data to low SNR ‘source’ image data, while maintaining their resolution. It has been shown that the noise characteristics of CT image data can be improved by iterative reconstruction (Popescu et al 2012 Book of Abstracts, 2nd CT Meeting (Salt Lake City, UT) p 148). In case of data dependent Gaussian noise it can be modelled with image-based iterative reconstruction at least in an approximate manner (Bruder et al 2011 Proc. SPIE 7961 79610J). We present a generalized update equation in image space, consisting of a linear combination of the previous update, a correction term which is constrained by the source image data, and a regularization prior, which is initialized by the composite image data. This iterative reconstruction approach we call bimodal reconstruction (BMR). Based on simulation data it is shown that BMR can improve low contrast detectability, substantially reduces the noise power and has the potential to recover

  20. Use of FDG PET/CT for investigation of febrile neutropenia: evaluation in high-risk cancer patients

    International Nuclear Information System (INIS)

    Guy, Stephen D.; Tramontana, Adrian R.; Worth, Leon J.; Thursky, Karin A.; Slavin, Monica A.; Lau, Eddie; Hicks, Rodney J.; Seymour, John F.

    2012-01-01

    Febrile neutropenia (FNP) is a frequent complication of cancer care and evaluation often fails to identify a cause. [ 18 F]FDG PET/CT has the potential to identify inflammatory and infectious foci, but its potential role as an investigation for persistent FNP has not previously been explored. The aim of this study was to prospectively evaluate the clinical utility of FDG PET/CT in patients with cancer and severe neutropenia and five or more days of persistent fever despite antibiotic therapy. Adult patients with a diagnosis of an underlying malignancy and persistent FNP (temperature ≥38 C and neutrophil count <500 cells/μl for 5 days) underwent FDG PET/CT as an adjunct to conventional evaluation and management. The study group comprised 20 patients with FNP who fulfilled the eligibility criteria and underwent FDG PET/CT in addition to conventional evaluation. The median neutrophil count on the day of the FDG PET/CT scan was 30 cells/μl (range 0-730 cells/μl). Conventional evaluation identified 14 distinct sites of infection, 13 (93 %) of which were also identified by FDG PET/CT, including all deep tissue infections. FDG PET/CT identified 9 additional likely infection sites, 8 of which were subsequently confirmed as ''true positives'' by further investigations. FDG PET/CT was deemed to be of 'high' clinical impact in 15 of the 20 patients (75 %). This study supports the utility of FDG PET/CT scanning in severely neutropenic patients with five or more days of fever. Further evaluation of the contribution of FDG PET/CT in the management of FNP across a range of underlying malignancies is required. (orig.)

  1. Use of FDG PET/CT for investigation of febrile neutropenia: evaluation in high-risk cancer patients

    Energy Technology Data Exchange (ETDEWEB)

    Guy, Stephen D.; Tramontana, Adrian R. [Western Health, Department of Infectious Diseases, Private Bag, Footscray, Victoria (Australia); University of Melbourne, Parkville, Victoria (Australia); Worth, Leon J.; Thursky, Karin A.; Slavin, Monica A. [University of Melbourne, Parkville, Victoria (Australia); Peter MacCallum Cancer Centre, Department of Infectious Diseases, Melbourne, Victoria (Australia); Lau, Eddie; Hicks, Rodney J. [University of Melbourne, Parkville, Victoria (Australia); Peter MacCallum Cancer Centre, Centre for Cancer Imaging, Melbourne, Victoria (Australia); Seymour, John F. [University of Melbourne, Parkville, Victoria (Australia); Peter MacCallum Cancer Centre, Department of Haematology, Melbourne, Victoria (Australia)

    2012-08-15

    Febrile neutropenia (FNP) is a frequent complication of cancer care and evaluation often fails to identify a cause. [{sup 18} F]FDG PET/CT has the potential to identify inflammatory and infectious foci, but its potential role as an investigation for persistent FNP has not previously been explored. The aim of this study was to prospectively evaluate the clinical utility of FDG PET/CT in patients with cancer and severe neutropenia and five or more days of persistent fever despite antibiotic therapy. Adult patients with a diagnosis of an underlying malignancy and persistent FNP (temperature {>=}38 C and neutrophil count <500 cells/{mu}l for 5 days) underwent FDG PET/CT as an adjunct to conventional evaluation and management. The study group comprised 20 patients with FNP who fulfilled the eligibility criteria and underwent FDG PET/CT in addition to conventional evaluation. The median neutrophil count on the day of the FDG PET/CT scan was 30 cells/{mu}l (range 0-730 cells/{mu}l). Conventional evaluation identified 14 distinct sites of infection, 13 (93 %) of which were also identified by FDG PET/CT, including all deep tissue infections. FDG PET/CT identified 9 additional likely infection sites, 8 of which were subsequently confirmed as ''true positives'' by further investigations. FDG PET/CT was deemed to be of 'high' clinical impact in 15 of the 20 patients (75 %). This study supports the utility of FDG PET/CT scanning in severely neutropenic patients with five or more days of fever. Further evaluation of the contribution of FDG PET/CT in the management of FNP across a range of underlying malignancies is required. (orig.)

  2. Flat-Panel Computed Tomography (DYNA-CT) in Neuroradiology. From High-Resolution Imaging of Implants to One-Stop-Shopping for Acute Stroke.

    Science.gov (United States)

    Doerfler, A; Gölitz, P; Engelhorn, T; Kloska, S; Struffert, T

    2015-10-01

    Originally aimed at improving standard radiography by providing higher absorption efficiency and a wider dynamic range, flat-panel detector technology has meanwhile got widely accepted in the neuroradiological community. Especially flat-panel detector computed tomography (FD-CT) using rotational C-arm mounted flat-panel detector technology is capable of volumetric imaging with a high spatial resolution. By providing CT-like images of the brain within the angio suite, FD-CT is able to rapidly visualize hemorrhage and may thus improve complication management without the need of patient transfer. As "Angiographic CT" FD-CT may be helpful during many diagnostic and neurointerventional procedures and for noninvasive monitoring and follow-up. In addition, spinal interventions and high-resolution imaging of the temporal bone might also benefit from FD-CT. Finally, using novel dynamic perfusion and angiographic protocols, FD-CT may provide functional information on brain perfusion and vasculature with the potential to replace standard imaging in selected acute stroke patients.

  3. High resolution CT in pulmonary sarcoidosis

    International Nuclear Information System (INIS)

    Spina, Juan C.; Curros, Marisela L.; Gomez, M.; Gonzalez, A.; Chacon, Carolina; Guerendiain, G.

    2000-01-01

    Objectives: To establish the particular advantages of High Resolution CT (HRCT) for the diagnosis of pulmonary sarcoidosis. Material and Methods: A series of fourteen patients, (4 men and 10 women; mean age 44,5 years) with thoracic sarcoidosis. All patients were studied using HRCT and diagnosis was confirmed for each case. Confidence intervals were obtained for different disease manifestations. Results: The most common findings were: lymph node enlargement (n=14 patients), pulmonary nodules (n=13), thickening of septa (n=6), peribronquial vascular thickening (n=5) pulmonary pseudo mass (n=5) and signs of fibrosis (n=4). The stage most commonly observed was stage II. It is worth noting that no cases of pleural effusion or cavitations of pulmonary lesions were observed. Conclusions: In this series, confidence interval overlapping for lymph node enlargement, single pulmonary nodules and septum thickening, allows to infer that their presence in a young adult, with few clinical symptoms, forces to rule out first the possibility of sarcoidosis. (author)

  4. Case with high cervical intramedullary hemangioblastoma associated with arteriovenous fistula. CT with simultaneous intravenous and intrathecal injection of contrast medium

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Takao; Shoji, Shin-ichi; Yanagisawa, Nobuo; Tada, Tsuyoshi; Kobayashi, Naoki

    1988-02-01

    A 34-year-old woman complained of right hemiparesis and pain in the right hand. Routine X-ray of the cervical portion failed to reveal abnormal findings. CT with intravenous contrast medium showed a large high-density mass in the spinal canal at the level of C2. Right vertebral angiography showed a hypervascular mass. With simultaneous intravenous and intrathecal injections of contrast medium, the tumor was shown as a moderately high-density area and the parenchyma of cord as a thin low-density area surrounding the tumor stain on CT. These CT appearances led to the final diagnosis of high cervical intramedullary hemangioblastoma associated with arteriovenous fistulae. Pathological findings are typical of hemangioblastoma. The usefulness of CT in detecting the localization of hypervascular spinal cord lesions is stressed. (Namekawa, K.).

  5. High-resolution three-dimensional visualization of the rat spinal cord microvasculature by synchrotron radiation micro-CT

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jianzhong; Cao, Yong; Wu, Tianding; Li, Dongzhe [Department of Spine Surgery, Xiangya Hospital, Central South University, Changsha 410008 (China); Lu, Hongbin, E-mail: hongbinlu@hotmail.com [Department of Sports Medicine, Research Centre of Sports Medicine, Xiangya Hospital, Central South University, Changsha 410008 (China)

    2014-10-15

    Purpose: Understanding the three-dimensional (3D) morphology of the spinal cord microvasculature has been limited by the lack of an effective high-resolution imaging technique. In this study, synchrotron radiation microcomputed tomography (SRµCT), a novel imaging technique based on absorption imaging, was evaluated with regard to the detection of the 3D morphology of the rat spinal cord microvasculature. Methods: Ten Sprague-Dawley rats were used in this ex vivo study. After contrast agent perfusion, their spinal cords were isolated and scanned using conventional x-rays, conventional micro-CT (CµCT), and SRµCT. Results: Based on contrast agent perfusion, the microvasculature of the rat spinal cord was clearly visualized for the first time ex vivo in 3D by means of SRµCT scanning. Compared to conventional imaging techniques, SRµCT achieved higher resolution 3D vascular imaging, with the smallest vessel that could be distinguished approximately 7.4 μm in diameter. Additionally, a 3D pseudocolored image of the spinal cord microvasculature was generated in a single session of SRµCT imaging, which was conducive to detailed observation of the vessel morphology. Conclusions: The results of this study indicated that SRµCT scanning could provide higher resolution images of the vascular network of the spinal cord. This modality also has the potential to serve as a powerful imaging tool for the investigation of morphology changes in the 3D angioarchitecture of the neurovasculature in preclinical research.

  6. Dual Energy CT Angiography of Peripheral Arterial Disease: Feasibility of Using Lower Contrast Medium Volume.

    Directory of Open Access Journals (Sweden)

    Abdulrahman Almutairi

    Full Text Available One of the main drawbacks associated with Dual Energy Computed Tomography Angiography (DECTA is the risk of developing contrast medium-induced nephropathy (CIN. The aim of the present study was firstly, to design an optimal CT imaging protocol by determining the feasibility of using a reduced contrast medium volume in peripheral arterial DECTA, and secondly, to compare the results with those obtained from using routine contrast medium volume.Thirty four patients underwent DECTA for the diagnosis of peripheral arterial disease. They were randomly divided into two groups: Group 1 (routine contrast volume group with n = 17, injection rate 4-5 ml/s, and 1.5 ml/kg of contrast medium, and Group 2 ((low contrast volume group, with n = 17, injection rate 4-5ml/s, and contrast medium volume 0.75 ml/kg. A fast kilovoltage-switching 64-slice CT scanner in the dual-energy mode was employed for the study. A total of 6 datasets of monochromatic images at 50, 55, 60, 65, 70 and 75 keV levels were reconstructed with adaptive statistical iterative reconstruction (ASIR at 50%. A 4-point scale was the tool for qualitative analysis of results. The two groups were compared and assessed quantitatively for image quality on the basis of signal-to-noise ratio (SNR and contrast-to-noise-ratio (CNR. Radiation and contrast medium doses were also compared.The overall mean CT attenuation and mean noise for all lower extremity body parts was significantly lower for the low volume contrast group (p<0.001, and varied significantly between groups (p = 0.001, body parts (p<0.001 and keVs (p<0.001. The interaction between group body parts was significant with CT attenuation and CNR (p = 0.002 and 0.003 respectively, and marginally significant with SNR (p = 0.047, with minimal changes noticed between the two groups. Group 2 (low contrast volume group displayed the lowest image noise between 65 and 70 keV, recorded the highest SNR and CNR at 65 keV, and produced significantly lower

  7. Nonlocal low-rank and sparse matrix decomposition for spectral CT reconstruction

    Science.gov (United States)

    Niu, Shanzhou; Yu, Gaohang; Ma, Jianhua; Wang, Jing

    2018-02-01

    Spectral computed tomography (CT) has been a promising technique in research and clinics because of its ability to produce improved energy resolution images with narrow energy bins. However, the narrow energy bin image is often affected by serious quantum noise because of the limited number of photons used in the corresponding energy bin. To address this problem, we present an iterative reconstruction method for spectral CT using nonlocal low-rank and sparse matrix decomposition (NLSMD), which exploits the self-similarity of patches that are collected in multi-energy images. Specifically, each set of patches can be decomposed into a low-rank component and a sparse component, and the low-rank component represents the stationary background over different energy bins, while the sparse component represents the rest of the different spectral features in individual energy bins. Subsequently, an effective alternating optimization algorithm was developed to minimize the associated objective function. To validate and evaluate the NLSMD method, qualitative and quantitative studies were conducted by using simulated and real spectral CT data. Experimental results show that the NLSMD method improves spectral CT images in terms of noise reduction, artifact suppression and resolution preservation.

  8. Why high energy physics

    International Nuclear Information System (INIS)

    Diddens, A.N.; Van de Walle, R.T.

    1981-01-01

    An argument is presented for high energy physics from the point of view of the practitioners. Three different angles are presented: The cultural consequence and scientific significance of practising high energy physics, the potential application of the results and the discovery of high energy physics, and the technical spin-offs from the techniques and methods used in high energy physics. (C.F.)

  9. Head trauma and CT

    International Nuclear Information System (INIS)

    Samejima, Kanji; Yoshii, Nobuo; Tobari, Chitoshi

    1979-01-01

    In our cases of acute and subacute subdural hematoma, the use of CT was evaluated. In our department of surgery, acute subdural hematoma was found in 46 of 388 patients of head trauma who underwent CT. Acute subdural hematoma, like epidural hematoma was usually visualized as a high-density area along the cranial inner table, and this was easily differenciated from epidural hematoma because of difference in shape from the other. The picture of acute subdural hematoma was occasionally confused with that of intracerebral hematoma or cerebral contusion. Single use of CT does not differenciate subacute subdural hematoma from chronic subdural hematoma. However, CT usually visualized acute hematoma as a high-density area, showing the extent of hematoma. Comparison of the thickness of hematoma with the axis deviation of the median part such as the 3rd cerebral ventricle suggested severity of cerebral edema. CT also revealed bilateral or multiple lesions of cerebral contusion or intracerebral hematoma. (Ueda, J.)

  10. [Clinical value of CT-guided high frequency-induced thermotherapy as a treatment for intrahepatic cholangiocarcinoma].

    Science.gov (United States)

    Fan, Wei-Jun; Zhang, Liang; Gu, Yang-Kui; Wang, Li-Gang; Ouyang, Yu-Shu

    2008-07-01

    To evaluate the therapeutic effect of CT-guided high frequency-induced thermotherapy (HiTT) for intrahepatic cholangiocarcinoma. Seventeen patients of intrahepatic cholangiocarcinoma with 21 lesions underwent comprehensive treatment with HiTT as the principle approach. As to the patients with obstructive jaundice, percutaneous trans-hepatic cholangial drainage (PTCD) or bile duct endoprosthesis placement was performed first to improve the liver function, then HiTT was performed; and patients without obstructive jaundice underwent CT-guided HiTT directly, 1-2 weeks later, chemotherapy was given for 4 - 6 courses. CT scan 1 week after HiTT showed a short-term achievement rate of 100% (17/17), and the single puncture in situ ablation rate was 76.1% (16/21). The average life span in the near future was 13.5 months. The adverse effects included topo-bleeding, pain after procedure, liver function damage, defervescence, etc. All the patients recovered after symptomatic treatment. The clinical value of CT-guided HiTT for intrahepatic cholangiocarcinoma is obvious.

  11. Dual energy CT monitoring of the renal corticomedullary sodium gradient in swine

    International Nuclear Information System (INIS)

    Kumar, Rahi; Wang, Zhen J.; Forsythe, Carlos; Fu Yanjun; Chen, Yunn-Yi; Yeh, Benjamin M.

    2012-01-01

    Objective: To evaluate the feasibility of dual-energy CT (DECT) for monitoring dynamic changes in the renal corticomedullary sodium gradient in swine. Material and methods: This study was approved by our Institutional Animal Care and Use Committee. Four water-restricted pigs were CT-scanned at 80 and 140 kVp at baseline and at 5 min intervals for 30 min during saline or furosemide diuresis. The renal cortical and medullary CT numbers were recorded. A DECT basis material decomposition method was used to quantify renal cortical and medullary sodium concentrations and medulla-to-cortex sodium ratios at each time point based on the measured CT numbers. The sodium concentrations and medulla-to-cortex sodium ratios were compared between baseline and at 30 min diuresis using paired Student t-tests. The medulla-to-cortex sodium ratios were considered to reflect the corticomedullary sodium gradient. Results: At baseline prior to saline diuresis, the mean medullary and cortical sodium concentrations were 103.8 ± 8.7 and 65.3 ± 1.7 mmol/l, respectively, corresponding to a medulla-to-cortex sodium ratio of 1.59. At 30 min of saline diuresis, the medullary and cortical sodium concentrations decreased to 72.3 ± 1.0 and 56.0 ± 1.4 mmol/l, respectively, corresponding to a significantly reduced medulla-to-cortex sodium ratio of 1.29 (P < 0.05). At baseline prior to furosemide diuresis, the mean medullary and cortical sodium concentrations were 110.5 ± 3.6 and 66.7 ± 4.1 mmol/l, respectively, corresponding to a medulla-to-cortex sodium ratio of 1.66. At 30 min of furosemide diuresis, the medullary and cortical sodium concentrations decreased to 68.5 ± 0.3 and 58.9 ± 4.0 mmol/l, respectively, corresponding to a significantly reduced medulla-to-cortex sodium ratio of 1.16 (P < 0.05). One of the 4 pigs developed acute tubular necrosis likely related to prolonged hypoxia during intubation prior to the furosemide diuresis experiment. The medulla-to-cortex sodium ratio for this

  12. Spectral resolution and high-flux capability tradeoffs in CdTe detectors for clinical CT.

    Science.gov (United States)

    Hsieh, Scott S; Rajbhandary, Paurakh L; Pelc, Norbert J

    2018-04-01

    Photon-counting detectors using CdTe or CZT substrates are promising candidates for future CT systems but suffer from a number of nonidealities, including charge sharing and pulse pileup. By increasing the pixel size of the detector, the system can improve charge sharing characteristics at the expense of increasing pileup. The purpose of this work is to describe these considerations in the optimization of the detector pixel pitch. The transport of x rays through the CdTe substrate was simulated in a Monte Carlo fashion using GEANT4. Deposited energy was converted into charges distributed as a Gaussian function with size dependent on interaction depth to capture spreading from diffusion and Coulomb repulsion. The charges were then collected in a pixelated fashion. Pulse pileup was incorporated separately with Monte Carlo simulation. The Cramér-Rao lower bound (CRLB) of the measurement variance was numerically estimated for the basis material projections. Noise in these estimates was propagated into CT images. We simulated pixel pitches of 250, 350, and 450 microns and compared the results to a photon counting detector with pileup but otherwise ideal energy response and an ideal dual-energy system (80/140 kVp with tin filtration). The modeled CdTe thickness was 2 mm, the incident spectrum was 140 kVp and 500 mA, and the effective dead time was 67 ns. Charge summing circuitry was not modeled. We restricted our simulations to objects of uniform thickness and did not consider the potential advantage of smaller pixels at high spatial frequencies. At very high x-ray flux, pulse pileup dominates and small pixel sizes perform best. At low flux or for thick objects, charge sharing dominates and large pixel sizes perform best. At low flux and depending on the beam hardness, the CRLB of variance in basis material projections tasks can be 32%-55% higher with a 250 micron pixel pitch compared to a 450 micron pixel pitch. However, both are about four times worse in variance

  13. CT Image Contrast of High-Z Elements: Phantom Imaging Studies and Clinical Implications.

    Science.gov (United States)

    FitzGerald, Paul F; Colborn, Robert E; Edic, Peter M; Lambert, Jack W; Torres, Andrew S; Bonitatibus, Peter J; Yeh, Benjamin M

    2016-03-01

    To quantify the computed tomographic (CT) image contrast produced by potentially useful contrast material elements in clinically relevant imaging conditions. Equal mass concentrations (grams of active element per milliliter of solution) of seven radiodense elements, including iodine, barium, gadolinium, tantalum, ytterbium, gold, and bismuth, were formulated as compounds in aqueous solutions. The compounds were chosen such that the active element dominated the x-ray attenuation of the solution. The solutions were imaged within a modified 32-cm CT dose index phantom at 80, 100, 120, and 140 kVp at CT. To simulate larger body sizes, 0.2-, 0.5-, and 1.0-mm-thick copper filters were applied. CT image contrast was measured and corrected for measured concentrations and presence of chlorine in some compounds. Each element tested provided higher image contrast than iodine at some tube potential levels. Over the range of tube potentials that are clinically practical for average-sized and larger adults-that is, 100 kVp and higher-barium, gadolinium, ytterbium, and tantalum provided consistently increased image contrast compared with iodine, respectively demonstrating 39%, 56%, 34%, and 24% increases at 100 kVp; 39%, 66%, 53%, and 46% increases at 120 kVp; and 40%, 72%, 65%, and 60% increases at 140 kVp, with no added x-ray filter. The consistently high image contrast produced with 100-140 kVp by tantalum compared with bismuth and iodine at equal mass concentration suggests that tantalum could potentially be favorable for use as a clinical CT contrast agent.

  14. Automated method for relating regional pulmonary structure and function: integration of dynamic multislice CT and thin-slice high-resolution CT

    Science.gov (United States)

    Tajik, Jehangir K.; Kugelmass, Steven D.; Hoffman, Eric A.

    1993-07-01

    We have developed a method utilizing x-ray CT for relating pulmonary perfusion to global and regional anatomy, allowing for detailed study of structure to function relationships. A thick slice, high temporal resolution mode is used to follow a bolus contrast agent for blood flow evaluation and is fused with a high spatial resolution, thin slice mode to obtain structure- function detail. To aid analysis of blood flow, we have developed a software module, for our image analysis package (VIDA), to produce the combined structure-function image. Color coded images representing blood flow, mean transit time, regional tissue content, regional blood volume, regional air content, etc. are generated and imbedded in the high resolution volume image. A text file containing these values along with a voxel's 3-D coordinates is also generated. User input can be minimized to identifying the location of the pulmonary artery from which the input function to a blood flow model is derived. Any flow model utilizing one input and one output function can be easily added to a user selectable list. We present examples from our physiologic based research findings to demonstrate the strengths of combining dynamic CT and HRCT relative to other scanning modalities to uniquely characterize pulmonary normal and pathophysiology.

  15. Driving forces and barriers in the development and implementation of coal-to-liquids (CtL) technologies in Germany

    International Nuclear Information System (INIS)

    Vallentin, Daniel

    2008-01-01

    Because of a growing global energy demand and rising oil prices coal-abundant nations, such as China and the United States, are pursuing the application of technologies which could replace crude oil imports by converting coal to synthetic hydrocarbon fuels-so-called coal-to-liquids (CtL) technologies. The case of CtL is well suited to analyse techno-economic, resources-related, policy-driven and actor-related parameters, which are affecting the market prospects of a technology that eases energy security constraints but is hardly compatible with a progressive climate policy. This paper concentrates on Germany as an example-the European Union (EU)'s largest member state with considerable coal reserves. It shows that in Germany and the EU, CtL is facing rather unfavourable market conditions as high costs and ambitious climate targets offset its energy security advantage

  16. High-resolution CT findings in infants with bronchopulmonary dysplasia: preliminary report

    International Nuclear Information System (INIS)

    Chung, Yoon Ho; Lee, Young Seok; Kim, Ji Hye; Han, Heon; Chung, Hyo Sun; Cha, Yoo Mi; Kim, Young Chae; Kim, Sang Hee

    1996-01-01

    To evaluate high resolution CT(HRCT) findings in infants with bronchopulmonary dysplasia(BPD). In 13 infants(age range, 1-12 months;11 premature babies, two full-term babies; birth weight, 0.97-3.88kg;mean 2,03kg) with clinico-radiologically suggested BPD, HRCT findings of the lung were reviewed retrospectively. Spiral CT using ultra high bone algorithm, 1mm collimation with 5-8mm interval, and 0.7sec scan time was performed without regard to breathing-control of infants. Three radiologists each analysed the HRCT findings twice. HRCT findings of BPD were as follows:parenchymal bands(n=13), interlobular septal thickenings (n=12), multifocal hyperaeration involving lobar or segmental distribution(n=7), and involving lobular distribution or small cyst-like lesion(n=4), centrilobular nodules(n=7), consolidation and/or atelectasis(n=7), and bronchovascular bundle thickening(n=6). Parenchymal bands, interlobular septal thickenings, and multifocal hyperaerations were the major findings in cases of bronchopulmonary dysplasia whereas, centrilobular nodules, consolidation and/or atelectasis, and bronchovascular bundle thickenings were the minor findings. These findings may be used as basic data in the evaluation of BPD in future studies

  17. A novel APD-based detector module for multi-modality PET/SPECT/CT scanners

    International Nuclear Information System (INIS)

    Saoudi, A.; Lecomte, R.

    1999-01-01

    The lack of anatomical information in SPECT and PET images is one of the major factors limiting the ability to localize and accurately quantify radionuclide uptake in small regions of interest. This problem could be resolved by using multi-modality scanners having the capability to acquire anatomical and functional images simultaneously. The feasibility of a novel detector suitable for measuring high-energy annihilation radiation in PET, medium-energy γ-rays in SPECT and low-energy X-rays in transmission CT is demonstrated and its performance is evaluated for potential use in multi-modality PET/SPECT/CT imaging. The proposed detector consists of a thin CsI(Tl) scintillator sitting on top of a deep GSO/LSO pair read out by an avalanche photodiode. The GSO/LOS pair provides depth-of-interaction information for 511 keV detection in PET, while the thin CsI(Tl) that is essentially transparent to annihilation radiation is used for detecting lower energy X- and γ-rays. The detector performance is compared to that of an LSO/YSO phoswich. Although the implementation of the proposed GSO/LSO/CsI(Tl) detector raises special problems that increase complexity, it generally outperforms the LSO/YSO phoswich for simultaneous PET, SPECT and CT imaging

  18. CT findings at lupus mesenteric vasculitis

    International Nuclear Information System (INIS)

    Ko, S.F.; Lee, T.Y.; Cheng, T.T.; Ng, S.H.; Lai, H.M.; Cheng, Y.F.; Tsai, C.C.

    1997-01-01

    Purpose: To describe the spectrum of early CT findings of lupus mesenteric vasculitis (LMV) and to assess the utility of CT in the management of this uncommon entity. Methods: Abdominal CT was performed within 1-4 days (average 2.2 days) of the onset of severe abdominal pain and tenderness in 15 women with systemic lupus erythematosus. Prompt high-dose i.v. corticosteroid in 11 patients after the CT diagnosis of LMV was made. CT was performed after abdominal symptoms subsided. Results: Eleven cases revealed CT features suggestive of LMV including conspicuous prominence of mesentric vessels with palisade pattern or comb-like appearance (CT comb sign) supplying focal or diffuse dilated bowel loops (n=11), ascites with slightly increased peritoneal enhancement (n=11), small bowel wall thickening (n=10) with double halo or target sign (n=8). Follow-up CT before high-dose steroid therapy revealed complete or marked resolution of the abnormal CT findings. Conclusion: CT is helpful for confirming the diagnosis of LMV, especially the comb sign which may be an early sign. Bowel ischemia due to LMV is less ominous than previously expected, and the abnormal CT findings were reversible when early diagnosis and prompt i.v. steroid therapy could be achieved. (orig.)

  19. CT findings at lupus mesenteric vasculitis

    Energy Technology Data Exchange (ETDEWEB)

    Ko, S.F. [Chang Gung Medical College and Memorial Hospital, Dept. of Radiology, Kaohsiung Hsien (Taiwan); Lee, T.Y. [Chang Gung Medical College and Memorial Hospital, Dept. of Radiology, Kaohsiung Hsien (Taiwan); Cheng, T.T. [Chang Gung Medical College and Memorial Hospital, Dept. of Rheumatology, Kaohsiung Hsien (Taiwan); Ng, S.H. [Chang Gung Medical College and Memorial Hospital, Dept. of Radiology, Kaohsiung Hsien (Taiwan); Lai, H.M. [Chang Gung Medical College and Memorial Hospital, Dept. of Rheumatology, Kaohsiung Hsien (Taiwan); Cheng, Y.F. [Chang Gung Medical College and Memorial Hospital, Dept. of Radiology, Kaohsiung Hsien (Taiwan); Tsai, C.C. [Chang Gung Medical College and Memorial Hospital, Dept. of Radiology, Kaohsiung Hsien (Taiwan)

    1997-01-01

    Purpose: To describe the spectrum of early CT findings of lupus mesenteric vasculitis (LMV) and to assess the utility of CT in the management of this uncommon entity. Methods: Abdominal CT was performed within 1-4 days (average 2.2 days) of the onset of severe abdominal pain and tenderness in 15 women with systemic lupus erythematosus. Prompt high-dose i.v. corticosteroid in 11 patients after the CT diagnosis of LMV was made. CT was performed after abdominal symptoms subsided. Results: Eleven cases revealed CT features suggestive of LMV including conspicuous prominence of mesentric vessels with palisade pattern or comb-like appearance (CT comb sign) supplying focal or diffuse dilated bowel loops (n=11), ascites with slightly increased peritoneal enhancement (n=11), small bowel wall thickening (n=10) with double halo or target sign (n=8). Follow-up CT before high-dose steroid therapy revealed complete or marked resolution of the abnormal CT findings. Conclusion: CT is helpful for confirming the diagnosis of LMV, especially the comb sign which may be an early sign. Bowel ischemia due to LMV is less ominous than previously expected, and the abnormal CT findings were reversible when early diagnosis and prompt i.v. steroid therapy could be achieved. (orig.).

  20. Characterisation of urinary stones in the presence of iodinated contrast medium using dual-energy CT: a phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jia; Qu, Mingliang; Duan, Xinhui; Takahashi, Naoki; Kawashima, Akira; Leng, Shuai; McCollough, Cynthia H. [Mayo Clinic, Department of Radiology, Rochester, MN (United States)

    2012-12-15

    To develop a dual-energy CT (DECT) method for differentiating uric acid (UA) from non-UA stones in the presence of iodinated contrast medium. Thirty UA and 45 non-UA stones were selected after infra-red spectroscopic analysis and independently placed in a 1.5-ml vial, which was filled first with saline and then with increasing concentrations of iodine. For each condition, tubes were put in a 35-cm water phantom and examined using a dual-source CT system at 100 and 140 kV. Virtual unenhanced images created from CT data sets of the stones in iodine-containing solutions provided position and volume information. This map was used to calculate a CT number ratio to differentiate stone type. A region-growing method was developed to improve the ability to differentiate between UA and non-UA stones with iodinated contrast medium. The sensitivity for detecting UA stones was 100 % for unenhanced images but fell to 18 % with 20 mgI/ml iodine solution and 0 % for higher concentrations. With region growing, the sensitivity for detecting UA stones was increased to 100 %, 82 %, 57 %, 50 % and 21 % for iodine solutions of 20, 40, 60, 80 and 100 mgI/ml. The region-growing method improves differentiation of UA from non-UA stones on contrast-enhanced DECT urograms. (orig.)

  1. A Time-Based Front End Readout System for PET & CT

    CERN Document Server

    Meyer, T C; Anghinolfi, F; Auffray, E; Dosanjh, M; Hillemanns, H; Hoffmann, H -F; Jarron, P; Kaplon, J; Kronberger, M; Lecoq, P; Moraes, D; Trummer, J

    2007-01-01

    In the framework of the European FP6's BioCare project, we develop a novel, time-based, photo-detector readout technique to increase sensitivity and timing precision for molecular imaging in PET and CT. The project aims to employ Avalanche Photo Diode (APD) arrays with state of the art, high speed, front end amplifiers and discrimination circuits developed for the Large Hadron Collider (LHC) physics program at CERN, suitable to detect and process photons in a combined one-unit PET/CT detection head. In the so-called time-based approach our efforts focus on the system's timing performance with sub-nanosecond time-jitter and -walk, and yet also provide information on photon energy without resorting to analog to digital conversion. The bandwidth of the electronic circuitry is compatible with the scintillator's intrinsic light response (e.g. les40ns in LSO) and hence allows high rate CT operation in single-photon counting mode. Based on commercial LSO crystals and Hamamatsu S8550 APD arrays, we show the system pe...

  2. Spiral CT versus conventional CT in the preoperative assessment of metallic intraocular foreign bodies

    International Nuclear Information System (INIS)

    Prokesch, R.; Bankier, A.; Ba-Ssalamah, A.; Imhof, H.; Lakits, A.; Scholda, C.

    1998-01-01

    Purpose: To compare the effectiveness of spiral CT versus conventional CT in the preoperative assessment of metallic intraocular foreign bodies. Results: All foreign bodies were detected by each scanning modality on the axial and on the reconstructed planes. The quality of the axial images was similar for spiral and conventional CT. The spiral technique provided high-quality reconstructed images which allowed accurate localization of the foreign bodies in all cases. Reconstructions by conventional technique were inadequate for preoperative assessment. The examination time for the total orbital volume was 18 s for spiral CT and 52 s for conventional CT. Radiation dose delivered to the lens was 35 mGy for spiral CT and 56 mGy for conventional CT axial scanning. Conclusion: Spiral CT multiplanar offers several significant advantages for the preoperative assessment of metallic intraocular foreign bodies compared to the conventional CT technique in clinical practice, including short examination time, minimized motion artifacts, reduced radiation exposure, and accurate localization. (orig.) [de

  3. High resolution CT for localization of early hilar lung carcinoma

    International Nuclear Information System (INIS)

    Minami, Yuko; Ishikawa, Shigemi; Saida, Yukihisa; Kajitani, Motomasa; Yamamoto, Tatsuo; Sato, Yukio; Onizuka, Masataka; Sakakibara, Yuzuru; Noguchi, Masayuki

    2002-01-01

    The purpose of this study was to analyse the usefulness of high resolution CT (HRCT) for the diagnosis and localization of roentgenographically occult lung cancer. HRCT was performed prospectively on chest X-ray negative patients with bloody sputum or suspicious or positive cells on sputum cytology between 1998 and 2000. After the HRCT scan, white light bronchoscopy and autofluorescence bronchoscopy were performed. HRCT depicted 19 hilar bronchial lesions in 13 cases out of 19 patients, of which 9 lesions were confirmed by white light broncoscope. Of 8 hilar squamous cell carcinomas diagnosed in this study, 7 lesions (87.5%) were depicted by HRCT. One CT-negative case (12.5%) was an in situ carcinoma in left B 1+2 . Four out of 20 lesions which showed bronchoscopic abnormality, could not be depicted by HRCT. HRCT could prospectively detect 80% of the bronchoscopic abnormalities and 87.5% of the hilar squamous cell carcinomas of the tracheobronchial lesions of the lung. Therefore, HRCT can be an effective supplemental means for screening for hilar squamous cell carcinoma. (author)

  4. CT findings of infant epilepsy

    International Nuclear Information System (INIS)

    Hojoh, Hiroatsu; Kataoka, Kenkichi; Nakagawa, Yoshihiro; Nakano, Shozo; Tomita, Yutaka.

    1982-01-01

    CT diagnosis of infantile epilepsy was evaluated. High incidence of abnormal CT findings in infantile spasms and Lennox-Gastaut syndrome was same as in other reports. Comparison between CT findings and neurological complications and that between CT findings and electroencephalogram findings revealed a stronger relationship existing in the former. This suggested that CT is more useful as a measure to detect underlying diseases which are due to organic change of the brain to cause epilepsy, rather than as that to disclose epileptic primary lesions of functional change. (Ueda, J.)

  5. Performance of turbo high-pitch dual-source CT for coronary CT angiography: first ex vivo and patient experience

    Energy Technology Data Exchange (ETDEWEB)

    Morsbach, Fabian; Gordic, Sonja; Husarik, Daniela; Frauenfelder, Thomas; Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Desbiolles, Lotus; Leschka, Sebastian [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Kantonsspital St. Gallen, Divison of Radiology and Nuclear Medicine, St. Gallen (Switzerland); Schmidt, Bernhard; Allmendinger, Thomas [Siemens AG, Healthcare Sector, Forchheim (Germany); Wildermuth, Simon [Kantonsspital St. Gallen, Divison of Radiology and Nuclear Medicine, St. Gallen (Switzerland)

    2014-08-15

    To evaluate image quality, maximal heart rate allowing for diagnostic imaging, and radiation dose of turbo high-pitch dual-source coronary computed tomographic angiography (CCTA). First, a cardiac motion phantom simulating heart rates (HRs) from 60-90 bpm in 5-bpm steps was examined on a third-generation dual-source 192-slice CT (prospective ECG-triggering, pitch 3.2; rotation time, 250 ms). Subjective image quality regarding the presence of motion artefacts was interpreted by two readers on a four-point scale (1, excellent; 4, non-diagnostic). Objective image quality was assessed by calculating distortion vectors. Thereafter, 20 consecutive patients (median, 50 years) undergoing clinically indicated CCTA were included. In the phantom study, image quality was rated diagnostic up to the HR75 bpm, with object distortion being 1 mm or less. Distortion increased above 1 mm at HR of 80-90 bpm. Patients had a mean HR of 66 bpm (47-78 bpm). Coronary segments were of diagnostic image quality for all patients with HR up to 73 bpm. Average effective radiation dose in patients was 0.6 ± 0.3 mSv. Our combined phantom and patient study indicates that CCTA with turbo high-pitch third-generation dual-source 192-slice CT can be performed at HR up to 75 bpm while maintaining diagnostic image quality, being associated with an average radiation dose of 0.6 mSv. (orig.)

  6. Performance of turbo high-pitch dual-source CT for coronary CT angiography: first ex vivo and patient experience

    International Nuclear Information System (INIS)

    Morsbach, Fabian; Gordic, Sonja; Husarik, Daniela; Frauenfelder, Thomas; Alkadhi, Hatem; Desbiolles, Lotus; Leschka, Sebastian; Schmidt, Bernhard; Allmendinger, Thomas; Wildermuth, Simon

    2014-01-01

    To evaluate image quality, maximal heart rate allowing for diagnostic imaging, and radiation dose of turbo high-pitch dual-source coronary computed tomographic angiography (CCTA). First, a cardiac motion phantom simulating heart rates (HRs) from 60-90 bpm in 5-bpm steps was examined on a third-generation dual-source 192-slice CT (prospective ECG-triggering, pitch 3.2; rotation time, 250 ms). Subjective image quality regarding the presence of motion artefacts was interpreted by two readers on a four-point scale (1, excellent; 4, non-diagnostic). Objective image quality was assessed by calculating distortion vectors. Thereafter, 20 consecutive patients (median, 50 years) undergoing clinically indicated CCTA were included. In the phantom study, image quality was rated diagnostic up to the HR75 bpm, with object distortion being 1 mm or less. Distortion increased above 1 mm at HR of 80-90 bpm. Patients had a mean HR of 66 bpm (47-78 bpm). Coronary segments were of diagnostic image quality for all patients with HR up to 73 bpm. Average effective radiation dose in patients was 0.6 ± 0.3 mSv. Our combined phantom and patient study indicates that CCTA with turbo high-pitch third-generation dual-source 192-slice CT can be performed at HR up to 75 bpm while maintaining diagnostic image quality, being associated with an average radiation dose of 0.6 mSv. (orig.)

  7. Evaluation of image quality and radiation dose using gold nanoparticles and other clinical contrast agents in dual-energy Computed Tomography (CT): CT abdomen phantom

    Science.gov (United States)

    Zukhi, J.; Yusob, D.; Tajuddin, A. A.; Vuanghao, L.; Zainon, R.

    2017-05-01

    The aim of this study was to evaluate the image quality and radiation dose using commercial gold nanoparticles and clinical contrast agents in dual-energy Computed Tomography (CT). Five polymethyl methacrylate (PMMA) tubes were used in this study, where four tubes were filled with different contrast agents (barium, iodine, gadolinium, and gold nanoparticles). The fifth tube was filled with water. Two optically stimulated luminescence dosimeters (OSLD) were placed in each tube to measure the radiation dose. The tubes were placed in a fabricated adult abdominal phantom of 32 cm in diameter using PMMA. The phantom was scanned using a DECT at low energy (80 kV) and high energy (140 kV) with different pitches (0.6 mm and 1.0 mm) and different slice thickness (3.0 mm and 5.0 mm). The tube current was applied automatically using automatic exposure control (AEC) and tube current modulation recommended by the manufacturer (CARE Dose 4D, Siemens, Germany). The contrast-to-noise ratio (CNR) of each contrast agent was analyzed using Weasis software. Gold nanoparticles has highest atomic number (Z = 79) than barium (Z = 56), iodine (Z = 53) and gadolinium (Z = 64). The CNR value of each contrast agent increases when the slice thickness increases. The radiation dose obtained from this study decreases when the pitch increases. The optimal imaging parameters for gold nanoparticles and other clinical contrast agents is obtained at pitch value of 1.0 mm and slice thickness of 5.0 mm. Low noise and low radiation dose obtained at these imaging parameters. The optimal imaging parameters obtained in this study can be applied in multiple contrast agents imaging.

  8. Evaluation of image quality and radiation dose using gold nanoparticles and other clinical contrast agents in dual-energy Computed Tomography (CT): CT abdomen phantom

    International Nuclear Information System (INIS)

    Zukhi, J; Yusob, D; Vuanghao, L; Zainon, R; Tajuddin, A A

    2017-01-01

    The aim of this study was to evaluate the image quality and radiation dose using commercial gold nanoparticles and clinical contrast agents in dual-energy Computed Tomography (CT). Five polymethyl methacrylate (PMMA) tubes were used in this study, where four tubes were filled with different contrast agents (barium, iodine, gadolinium, and gold nanoparticles). The fifth tube was filled with water. Two optically stimulated luminescence dosimeters (OSLD) were placed in each tube to measure the radiation dose. The tubes were placed in a fabricated adult abdominal phantom of 32 cm in diameter using PMMA. The phantom was scanned using a DECT at low energy (80 kV) and high energy (140 kV) with different pitches (0.6 mm and 1.0 mm) and different slice thickness (3.0 mm and 5.0 mm). The tube current was applied automatically using automatic exposure control (AEC) and tube current modulation recommended by the manufacturer (CARE Dose 4D, Siemens, Germany). The contrast-to-noise ratio (CNR) of each contrast agent was analyzed using Weasis software. Gold nanoparticles has highest atomic number (Z = 79) than barium (Z = 56), iodine (Z = 53) and gadolinium (Z = 64). The CNR value of each contrast agent increases when the slice thickness increases. The radiation dose obtained from this study decreases when the pitch increases. The optimal imaging parameters for gold nanoparticles and other clinical contrast agents is obtained at pitch value of 1.0 mm and slice thickness of 5.0 mm. Low noise and low radiation dose obtained at these imaging parameters. The optimal imaging parameters obtained in this study can be applied in multiple contrast agents imaging. (paper)

  9. Utility of single-energy and dual-energy computed tomography in clot characterization: An in-vitro study.

    Science.gov (United States)

    Brinjikji, Waleed; Michalak, Gregory; Kadirvel, Ramanathan; Dai, Daying; Gilvarry, Michael; Duffy, Sharon; Kallmes, David F; McCollough, Cynthia; Leng, Shuai

    2017-06-01

    Background and purpose Because computed tomography (CT) is the most commonly used imaging modality for the evaluation of acute ischemic stroke patients, developing CT-based techniques for improving clot characterization could prove useful. The purpose of this in-vitro study was to determine which single-energy or dual-energy CT techniques provided optimum discrimination between red blood cell (RBC) and fibrin-rich clots. Materials and methods Seven clot types with varying fibrin and RBC densities were made (90% RBC, 99% RBC, 63% RBC, 36% RBC, 18% RBC and 0% RBC with high and low fibrin density) and their composition was verified histologically. Ten of each clot type were created and scanned with a second generation dual source scanner using three single (80 kV, 100 kV, 120 kV) and two dual-energy protocols (80/Sn 140 kV and 100/Sn 140 kV). A region of interest (ROI) was placed over each clot and mean attenuation was measured. Receiver operating characteristic curves were calculated at each energy level to determine the accuracy at differentiating RBC-rich clots from fibrin-rich clots. Results Clot attenuation increased with RBC content at all energy levels. Single-energy at 80 kV and 120 kV and dual-energy 80/Sn 140 kV protocols allowed for distinguishing between all clot types, with the exception of 36% RBC and 18% RBC. On receiver operating characteristic curve analysis, the 80/Sn 140 kV dual-energy protocol had the highest area under the curve for distinguishing between fibrin-rich and RBC-rich clots (area under the curve 0.99). Conclusions Dual-energy CT with 80/Sn 140 kV had the highest accuracy for differentiating RBC-rich and fibrin-rich in-vitro thrombi. Further studies are needed to study the utility of non-contrast dual-energy CT in thrombus characterization in acute ischemic stroke.

  10. The upper limits of the SNR in radiography and CT with polyenergetic x-rays

    International Nuclear Information System (INIS)

    Shikhaliev, Polad M

    2010-01-01

    The aim of the study is to determine the upper limits of the signal-to-noise ratio (SNR) in radiography and computed tomography (CT) with polyenergetic x-ray sources. In x-ray imaging, monoenergetic x-rays provide a higher SNR compared to polyenergetic x-rays. However, the SNR in polyenergetic x-ray imaging can be increased when a photon-counting detector is used and x-rays are optimally weighted according to their energies. For a particular contrast/background combination and at a fixed x-ray entrance skin exposure, the SNR in energy-weighting x-ray imaging depends on tube voltage and can be maximized by selecting the optimal tube voltage. The SNR in energy-weighted x-ray images acquired at this optimal tube voltage is the highest SNR that can be achieved with polyenergetic x-ray sources. The optimal tube voltages and the highest SNR were calculated and compared to the SNR of monoenergetic x-ray imaging. Monoenergetic, energy-weighting polyenergetic and energy-integrating polyenergetic x-ray imagings were simulated at a fixed entrance skin exposure of 20 mR. The tube voltages varied in the range of 30-140 kVp with 10 kV steps. Contrast elements of CaCO 3 , iodine, adipose and tumor with thicknesses of 280 mg cm -2 , 15 mg cm -2 , 1 g cm -2 and 1 g cm -2 , respectively, inserted in a soft tissue background with 10 cm and 20 cm thicknesses, were used. The energy weighting also improves the contrast-to-noise ratio (CNR) in CT when monoenergetic CT projections are optimally weighted prior to CT reconstruction (projection-based weighting). Alternatively, monoenergetic CT images are reconstructed, optimally weighted and composed to yield a final CT image (image-based weighting). Both projection-based and image-based weighting methods improve the CNR in CT. An analytical approach was used to determine which of these two weighting methods provides the upper limit of the CNR in CT. The energy-weighting method was generalized and expanded as a weighting method applicable in

  11. Collateral ventilation quantification using xenon-enhanced dynamic dual-energy CT: Differences between canine and swine models of bronchial occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Ah; Goo, Jin Mo; Park, Sang Joon; Lee, Chang Hyun; Park, Chng Min [Dept. of Radiology, Seoul National University College of Medicine and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul (Korea, Republic of)

    2015-06-15

    The aim of this study was to evaluate whether the difference in the degree of collateral ventilation between canine and swine models of bronchial obstruction could be detected by using xenon-enhanced dynamic dual-energy CT. Eight mongrel dogs and six pigs underwent dynamic dual-energy scanning of 64-slice dual-source CT at 12-second interval for 2-minute wash-in period (60% xenon) and at 24-second interval for 3-minute wash-out period with segmental bronchus occluded. Ventilation parameters of magnitude (A value), maximal slope, velocity (K value), and time-to-peak (TTP) enhancement were calculated from dynamic xenon maps using exponential function of Kety model. A larger difference in A value between parenchyma was observed in pigs than in dogs (absolute difference, -33.0 +/- 5.0 Hounsfield units [HU] vs. -2.8 +/- 7.1 HU, p = 0.001; normalized percentage difference, -79.8 +/- 1.8% vs. -5.4 +/- 16.4%, p = 0.0007). Mean maximal slopes in both periods in the occluded parenchyma only decreased in pigs (all p < 0.05). K values of both periods were not different (p = 0.892) in dogs. However, a significant (p = 0.027) difference was found in pigs in the wash-in period. TTP was delayed in the occluded parenchyma in pigs (p = 0.013) but not in dogs (p = 0.892). Xenon-ventilation CT allows the quantification of collateral ventilation and detection of differences between canine and swine models of bronchial obstruction.

  12. Collateral ventilation quantification using xenon-enhanced dynamic dual-energy CT: Differences between canine and swine models of bronchial occlusion

    International Nuclear Information System (INIS)

    Kim, Eun Ah; Goo, Jin Mo; Park, Sang Joon; Lee, Chang Hyun; Park, Chng Min

    2015-01-01

    The aim of this study was to evaluate whether the difference in the degree of collateral ventilation between canine and swine models of bronchial obstruction could be detected by using xenon-enhanced dynamic dual-energy CT. Eight mongrel dogs and six pigs underwent dynamic dual-energy scanning of 64-slice dual-source CT at 12-second interval for 2-minute wash-in period (60% xenon) and at 24-second interval for 3-minute wash-out period with segmental bronchus occluded. Ventilation parameters of magnitude (A value), maximal slope, velocity (K value), and time-to-peak (TTP) enhancement were calculated from dynamic xenon maps using exponential function of Kety model. A larger difference in A value between parenchyma was observed in pigs than in dogs (absolute difference, -33.0 +/- 5.0 Hounsfield units [HU] vs. -2.8 +/- 7.1 HU, p = 0.001; normalized percentage difference, -79.8 +/- 1.8% vs. -5.4 +/- 16.4%, p = 0.0007). Mean maximal slopes in both periods in the occluded parenchyma only decreased in pigs (all p < 0.05). K values of both periods were not different (p = 0.892) in dogs. However, a significant (p = 0.027) difference was found in pigs in the wash-in period. TTP was delayed in the occluded parenchyma in pigs (p = 0.013) but not in dogs (p = 0.892). Xenon-ventilation CT allows the quantification of collateral ventilation and detection of differences between canine and swine models of bronchial obstruction.

  13. Evaluation of dual energy spectral CT in differentiating metastatic from non-metastatic lymph nodes in rectal cancer: Initial experience

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huanhuan [Department of Radiology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Department of Radiology, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine (China); Yan, Fuhua; Pan, Zilai; Lin, Xiaozhu; Luo, Xianfu; Shi, Cen [Department of Radiology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Chen, Xiaoyan [Department of Pathology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Wang, Baisong [Department of Biomedical Statistics, Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China); Zhang, Huan, E-mail: huanzhangy@126.com [Department of Radiology, Ruijin Hospital Affiliated to Shanghai Jiaotong University, School of Medicine, Shanghai 200025 (China)

    2015-02-15

    Highlights: • Colorectal cancer is the third most prevalent cancer and the status of the regional lymph nodes in rectal cancer is considered to be one of the most powerful prognostic factor in the absence of distant metastatic disease. Detecting LNs metastasis is still a challenging problem due to the presence of microscopic metastasis or inflammatory swelling of LNs. • We investigated the value of dual energy spectral CT in differentiating metastatic from non-metastatic lymph nodes in rectal cancer. Our study demonstrated that the quantitative normalized iodine concentration (nIC) could be useful for differentiating metastatic and non-metastatic lymph nodes. The combination of nIC in portal venous phase and conventional size criterion could improve the diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive value of rectal cancer. - Abstract: Objectives: To investigate the value of dual energy spectral CT (DEsCT) imaging in differentiating metastatic from non-metastatic lymph nodes in rectal cancer. Methods: Fifty-five patients with rectal cancer underwent the arterial phase (AP) and portal venous phase (PP) contrast-enhanced DEsCT imaging. The virtual monochromatic images and iodine-based material decomposition images derived from DEsCT imaging were interpreted for lymph nodes (LNs) measurement. The short axis diameter and the normalized iodine concentration (nIC) of metastatic and non-metastatic LNs were measured. The two-sample t test was used to compare the short axis diameters and nIC values of metastatic and non-metastatic LNs. ROC analysis was performed to assess the diagnostic performance. Results: One hundred and fifty two LNs including 92 non-metastatic LNs and 60 metastatic LNs were matched using the radiological-pathological correlation. The mean short axis diameter of metastatic LNs was significantly larger than that of the non-metastatic LNs (7.28 ± 2.28 mm vs. 4.90 ± 1.64 mm, P < 0.001). The mean n

  14. TU-AB-BRC-03: Accurate Tissue Characterization for Monte Carlo Dose Calculation Using Dual-and Multi-Energy CT Data

    Energy Technology Data Exchange (ETDEWEB)

    Lalonde, A; Bouchard, H [University of Montreal, Montreal, Qc (Canada)

    2016-06-15

    Purpose: To develop a general method for human tissue characterization with dual-and multi-energy CT and evaluate its performance in determining elemental compositions and the associated proton stopping power relative to water (SPR) and photon mass absorption coefficients (EAC). Methods: Principal component analysis is used to extract an optimal basis of virtual materials from a reference dataset of tissues. These principal components (PC) are used to perform two-material decomposition using simulated DECT data. The elemental mass fraction and the electron density in each tissue is retrieved by measuring the fraction of each PC. A stoichiometric calibration method is adapted to the technique to make it suitable for clinical use. The present approach is compared with two others: parametrization and three-material decomposition using the water-lipid-protein (WLP) triplet. Results: Monte Carlo simulations using TOPAS for four reference tissues shows that characterizing them with only two PC is enough to get a submillimetric precision on proton range prediction. Based on the simulated DECT data of 43 references tissues, the proposed method is in agreement with theoretical values of protons SPR and low-kV EAC with a RMS error of 0.11% and 0.35%, respectively. In comparison, parametrization and WLP respectively yield RMS errors of 0.13% and 0.29% on SPR, and 2.72% and 2.19% on EAC. Furthermore, the proposed approach shows potential applications for spectral CT. Using five PC and five energy bins reduces the SPR RMS error to 0.03%. Conclusion: The proposed method shows good performance in determining elemental compositions from DECT data and physical quantities relevant to radiotherapy dose calculation and generally shows better accuracy and unbiased results compared to reference methods. The proposed method is particularly suitable for Monte Carlo calculations and shows promise in using more than two energies to characterize human tissue with CT.

  15. TU-AB-BRC-03: Accurate Tissue Characterization for Monte Carlo Dose Calculation Using Dual-and Multi-Energy CT Data

    International Nuclear Information System (INIS)

    Lalonde, A; Bouchard, H

    2016-01-01

    Purpose: To develop a general method for human tissue characterization with dual-and multi-energy CT and evaluate its performance in determining elemental compositions and the associated proton stopping power relative to water (SPR) and photon mass absorption coefficients (EAC). Methods: Principal component analysis is used to extract an optimal basis of virtual materials from a reference dataset of tissues. These principal components (PC) are used to perform two-material decomposition using simulated DECT data. The elemental mass fraction and the electron density in each tissue is retrieved by measuring the fraction of each PC. A stoichiometric calibration method is adapted to the technique to make it suitable for clinical use. The present approach is compared with two others: parametrization and three-material decomposition using the water-lipid-protein (WLP) triplet. Results: Monte Carlo simulations using TOPAS for four reference tissues shows that characterizing them with only two PC is enough to get a submillimetric precision on proton range prediction. Based on the simulated DECT data of 43 references tissues, the proposed method is in agreement with theoretical values of protons SPR and low-kV EAC with a RMS error of 0.11% and 0.35%, respectively. In comparison, parametrization and WLP respectively yield RMS errors of 0.13% and 0.29% on SPR, and 2.72% and 2.19% on EAC. Furthermore, the proposed approach shows potential applications for spectral CT. Using five PC and five energy bins reduces the SPR RMS error to 0.03%. Conclusion: The proposed method shows good performance in determining elemental compositions from DECT data and physical quantities relevant to radiotherapy dose calculation and generally shows better accuracy and unbiased results compared to reference methods. The proposed method is particularly suitable for Monte Carlo calculations and shows promise in using more than two energies to characterize human tissue with CT.

  16. Prototype heel effect compensation filter for cone-beam CT

    International Nuclear Information System (INIS)

    Mori, Shinichiro; Endo, Masahiro; Nishizawa, Kanae; Ohno, Mari; Miyazaki, Hiroaki; Tsujita, Kazuhiko; Saito, Yasuo

    2005-01-01

    The prototype cone-beam CT (CBCT) has a larger beam width than the conventional multi-detector row CT (MDCT). This causes a non-uniform angular distribution of the x-ray beam intensity known as the heel effect. Scan conditions for CBCT tube current are adjusted on the anode side to obtain an acceptable clinical image quality. However, as the dose is greater on the cathode side than on the anode side, the signal-to-noise ratio on the cathode side is excessively high, resulting in an unnecessary dose amount. To compensate for the heel effect, we developed a heel effect compensation (HEC) filter. The HEC filter rendered the dose distribution uniform and reduced the dose by an average of 25% for free air and by 20% for CTDI phantoms compared to doses with the conventional filter. In addition, its effect in rendering the effective energy uniform resulted in an improvement in image quality. This new HEC filter may be useful in cone-beam CT studies. (note)

  17. Initial implementation of the conversion from the energy-subtracted CT number to electron density in tissue inhomogeneity corrections: An anthropomorphic phantom study of radiotherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Tsukihara, Masayoshi [Division of Radiological Technology, Graduate School of Health Sciences, Niigata University, Niigata 951-8518 (Japan); Noto, Yoshiyuki [Department of Radiology, Niigata University Medical and Dental Hospital, Niigata 951-8520 (Japan); Sasamoto, Ryuta; Hayakawa, Takahide; Saito, Masatoshi, E-mail: masaito@clg.niigata-u.ac.jp [Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Niigata University, Niigata 951-8518 (Japan)

    2015-03-15

    Purpose: To achieve accurate tissue inhomogeneity corrections in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted computed tomography (CT) number to an electron density (ΔHU–ρ{sub e} conversion), which provides a single linear relationship between ΔHU and ρ{sub e} over a wide range of ρ{sub e}. The purpose of this study is to present an initial implementation of the ΔHU–ρ{sub e} conversion method for a treatment planning system (TPS). In this paper, two example radiotherapy plans are used to evaluate the reliability of dose calculations in the ΔHU–ρ{sub e} conversion method. Methods: CT images were acquired using a clinical dual-source CT (DSCT) scanner operated in the dual-energy mode with two tube potential pairs and an additional tin (Sn) filter for the high-kV tube (80–140 kV/Sn and 100–140 kV/Sn). Single-energy CT using the same DSCT scanner was also performed at 120 kV to compare the ΔHU–ρ{sub e} conversion method with a conventional conversion from a CT number to ρ{sub e} (Hounsfield units, HU–ρ{sub e} conversion). Lookup tables for ρ{sub e} calibration were obtained from the CT image acquisitions for tissue substitutes in an electron density phantom (EDP). To investigate the beam-hardening effect on dosimetric uncertainties, two EDPs with different sizes (a body EDP and a head EDP) were used for the ρ{sub e} calibration. Each acquired lookup table was applied to two radiotherapy plans designed using the XiO TPS with the superposition algorithm for an anthropomorphic phantom. The first radiotherapy plan was for an oral cavity tumor and the second was for a lung tumor. Results: In both treatment plans, the performance of the ΔHU–ρ{sub e} conversion was superior to that of the conventional HU–ρ{sub e} conversion in terms of the reliability of dose calculations. Especially, for the oral tumor plan, which dealt with dentition and bony structures, treatment

  18. Opportunistic screening for osteoporosis by routine CT in Southern Europe.

    Science.gov (United States)

    Alacreu, Elena; Moratal, David; Arana, Estanislao

    2017-03-01

    Feasibility evaluation of early detection of osteoporosis in oncologic patients by bone mineral density (BMD) on abdominal computed tomography (CT) scans performed for other clinical indications, by using dual-energy X-ray absorptiometry (DXA) as reference. Abdominal CT images can identify patients with osteoporosis BMD without additional radiation exposure or cost. The purpose of the study is to evaluate the feasibility of early detection of osteoporosis by bone mineral density (BMD) on abdominal computed tomography (CT) scans performed in oncologic patients, comparing calibrated and uncalibrated measurements by using dual-energy X-ray absorptiometry (DXA) as reference. We also performed an external validation of a threshold of 160 Hounsfield units (HU), proposed as highly sensitive. Cohort comprised CT-DXA pairs within a 6-month period performed for any indication on 326 consecutive adults, aged 62.4 ± 12.38 years (mean ± standard deviation). CT attenuation of trabecular bone in HU was measured at the axial cross sections of L1, L2, L3, and L4 vertebrae. Vertebral compression fractures were assessed by sagittal reconstruction view. Diagnostic performance measures and the area under the receiver operator characteristic curve (AUC) for diagnosing osteoporosis were calculated. BMD values were statistical significantly lower at any vertebral level from L1 to L4 for patients with osteoporosis defined by DXA (p < 0.001). Calibrated and uncalibrated BMD values were significantly correlated (R 2  = 0.833, p < 0.01). An uncalibrated L1 CT attenuation threshold of 160 HU was more than 90 % sensitive, and a threshold of 73 HU was more than 90 % specific for distinguishing osteoporosis BMD. Fifty-nine percent of patients with vertebral compression fracture had non-osteoporotic DXA T-scores. Abdominal CT images obtained for other reasons can identify patients with osteoporosis BMD without additional radiation exposure or cost. Uncalibrated values at L1 can

  19. CT vs 68Ge attenuation correction in a combined PET/CT system: evaluation of the effect of lowering the CT tube current

    International Nuclear Information System (INIS)

    Kamel, Ehab; Hany, Thomas F.; Burger, Cyrill; Treyer, Valerie; Schulthess von, Gustav K.; Buck, Alfred; Lonn, Albert H.R.

    2002-01-01

    With the introduction of combined positron emission tomography/computed tomography (PET/CT) systems, several questions have to be answered. In this work we addressed two of these questions: (a) to what value can the CT tube current be reduced while still yielding adequate maps for the attenuation correction of PET emission scans and (b) how do quantified uptake values in tumours derived from CT and germanium-68 attenuation correction compare. In 26 tumour patients, multidetector CT scans were acquired with 10, 40, 80 and 120 mA (CT 10 , CT 40 , CT 80 and CT 120 ) and used for the attenuation correction of a single FDG PET emission scan, yielding four PET scans designated PET CT10 -PET CT120 . In 60 tumorous lesions, FDG uptake and lesion size were quantified on PET CT10 -PET CT120 . In another group of 18 patients, one CT scan acquired with 80 mA and a standard transmission scan acquired using 68 Ge sources were employed for the attenuation correction of the FDG emission scan (PET CT80 , PET 68Ge ). Uptake values and lesion size in 26 lesions were compared on PET CT80 and PET 68Ge . In the first group of patients, analysis of variance revealed no significant effect of CT current on tumour FDG uptake or lesion size. In the second group, tumour FDG uptake was slightly higher using CT compared with 68 Ge attenuation correction, especially in lesions with high FDG uptake. Lesion size was similar on PET CT80 and PET 68Ge . In conclusion, low CT currents yield adequate maps for the attenuation correction of PET emission scans. Although the discrepancy between CT- and 68 Ge-derived uptake values is probably not relevant in most cases, it should be kept in mind if standardised uptake values derived from CT and 68 Ge attenuation correction are compared. (orig.)

  20. Evaluating optimal CNR as a preset criteria for nonlinear moidal blending of dual energy CT data

    Science.gov (United States)

    Holmes, D. R., III; Apel, A.; Fletcher, J. G.; Guimaraes, L. S.; Eusemann, C. E.; Robb, R. A.

    2009-02-01

    Nonlinear blending of dual-energy CT data is available on current scanners. Selection of the blending parameters can be time-consuming and challenging. The purpose of this study was to determine if the Contrast-To-Noise Ratio (CNR) may be used ti automatic select of blending parameters. A Bovine liver was built with six syringes filled with varying concentrations of CT contrast yielding six 140kV HU levels (15, 47, 64, 79, 116, and 145). The phantom was scanned using 95 mAs @ 140kV and 404mAs @ 80 kV. The 80 and 140 kV datasets were blended using a modified sigmoid (moidal) function which requires two parameters - level and width. Every combination of moidal level and width was applied to the data, and the CNR was calculated as (mean(syringe ROI) - mean(liver ROI)) / STD(water). The maximum CNR was determined for each of the 6 HU levels. Pairs of blended images were presented in a blind manner to observers. Nine comparisons for each of the 6 HU settings were made by a staff radiologist, a resident, and a physicist. For each comparison, the observer selected the more "visually appealing" image. Outcomes from the study were compared using the Fisher Sign Test statistic. Analysis by observer showed a statistical (penergy CT data may provide consistency across radiologists and facilitate the clinical review process.

  1. Imaging of bronchiectasis: the great value of high-resolution CT in differential diagnosis; Differenzialdiagnose der Bronchiektasen: High-resolution CT als wertvolle Hilfe

    Energy Technology Data Exchange (ETDEWEB)

    Heckmann, M.; Kramann, B.; Heinrich, M. [Klinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum des Saarlandes, Homburg/Saar (Germany); Uder, M. [Inst. fuer Diagnostische Radiologie, Friedrich-Alexander-Univ. Erlangen-Nuernberg, Erlangen (Germany)

    2006-07-01

    Bronchiectasis is defined as localized irreversible dilatation of the bronchial tree. Brochiectasis has been associated with a wide variety of causes, but it is mostly caused by acute, chronic or recurrent infections. This paper should give a review about the manifestation of bronchiectasis and bronchioloectasis in HR-CT and discuss the causing entities. However, integration of bronchiectasis and other HR-CT findings may enable a narrower differential diagnosis, in some cases it is possible to give the correct diagnose directly. (orig.)

  2. Comparative Investigation of Ce3+ Doped Scintillators in a Wide Range of Photon Energies Covering X-ray CT, Nuclear Medicine and Megavoltage Radiation Therapy Portal Imaging Applications

    Science.gov (United States)

    Valais, Ioannis G.; Michail, Christos M.; David, Stratos L.; Liaparinos, Panagiotis F.; Fountos, George P.; Paschalis, Theodoros V.; Kandarakis, Ioannis S.; Panayiotakis, George S.

    2010-02-01

    The aim of the present work is to study the performance of scintillators currently used in PET and animal PET systems, under conditions met in radiation therapy and PET/CT imaging. The results of this study will be useful in applications where both CT and PET photons as well as megavoltage cone beam CT (MV CBCT) photons could be detected using a common detector unit. To this aim crystal samples of GSO, LSO, LYSO, LuYAP and YAP scintillators, doped with cerium (Ce+3) were examined under a wide energy range of photon energies. Evaluation was performed by determining the absolute luminescence efficiency (emitted light flux over incident X-ray exposure) in the energy range employed in X-ray CT, in Nuclear Medicine (70 keV up to 662 keV) and in radiotherapy 6 MV (approx. 2.0 MeV mean energy)-18 MV (approx. 4.5 MeV mean energy). Measurements were performed using an experimental set-up based on a photomultiplier coupled to a light integration sphere. The emission spectrum under X-ray excitation was measured, using an optical grating monochromator, to determine the spectral compatibility to optical photon detectors incorporated in medical imaging systems. Maximum absolute luminescence efficiency values were observed at 70 keV for YAP:Ce and LuYAP:Ce and at 140 keV for LSO:Ce, LYSO:Ce and GSO:Ce. Highest absolute efficiency between the scintillators examined was observed for LSO:Ce, followed by LYSO:Ce. The detector optical gain (DOG) exhibited a significant variation with the increase of energy between 70 keV to 2.0 MeV. All scintillators exhibited low compatibility when combined with GaAsP (G5645) photodetector.

  3. Dual-energy CT in assessing therapeutic response to radiofrequency ablation of renal cell carcinomas

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Yoon; Kim, Chan Kyo, E-mail: chankyokim@skku.edu; Park, Byung Kwan

    2014-02-15

    Purpose: To investigate the utility of dual-energy (DE) CT using virtual noncontrast (VNC) and iodine overlay (IO) images to assess therapeutic response to radiofrequency ablation (RFA) for renal cell carcinomas (RCCs). Materials and methods: In this institutional review board-approved study (with waiver of informed consent), 47 patients with RCCs that underwent DECT after RFA were enrolled in this study. DECT protocols included true noncontrast (TNC), linearly blended DE corticomedullary and late nephrographic phase imaging. Two types of VNC and IO images were derived from corticomedullary and late nephrographic phases, respectively. To predict local tumor progression at RFA site, linearly blended and IO images were analyzed both qualitatively and quantitatively. Contrast-to-noise ratios (CNR) of renal cortex-to-RFA zones were calculated. The overall imaging quality of VNC images was compared with TNC images. Results: The IO images from corticomedullary and late nephrographic phases showed excellent diagnostic performance (each sensitivity 100% and each specificity 91.5%) for predicting local tumor progression. The degree of enhancement of local tumor progression was not significantly different between linearly blended and IO images (P > 0.05). The mean CT numbers were not significantly different between TNC and VNC images (P > 0.05). In renal cortex-to-RFA site, CNR between linearly blended and IO images was not significantly different (P > 0.05). The VNC imaging quality from the two phases was given a good rating. Conclusion: VNC and IO images from DECT may allow acceptable diagnostic performance with less radiation exposure as a follow-up imaging tool after RFA for RCC, compared to the linearly blended CT images.

  4. Dual-energy CT in assessing therapeutic response to radiofrequency ablation of renal cell carcinomas

    International Nuclear Information System (INIS)

    Park, Sung Yoon; Kim, Chan Kyo; Park, Byung Kwan

    2014-01-01

    Purpose: To investigate the utility of dual-energy (DE) CT using virtual noncontrast (VNC) and iodine overlay (IO) images to assess therapeutic response to radiofrequency ablation (RFA) for renal cell carcinomas (RCCs). Materials and methods: In this institutional review board-approved study (with waiver of informed consent), 47 patients with RCCs that underwent DECT after RFA were enrolled in this study. DECT protocols included true noncontrast (TNC), linearly blended DE corticomedullary and late nephrographic phase imaging. Two types of VNC and IO images were derived from corticomedullary and late nephrographic phases, respectively. To predict local tumor progression at RFA site, linearly blended and IO images were analyzed both qualitatively and quantitatively. Contrast-to-noise ratios (CNR) of renal cortex-to-RFA zones were calculated. The overall imaging quality of VNC images was compared with TNC images. Results: The IO images from corticomedullary and late nephrographic phases showed excellent diagnostic performance (each sensitivity 100% and each specificity 91.5%) for predicting local tumor progression. The degree of enhancement of local tumor progression was not significantly different between linearly blended and IO images (P > 0.05). The mean CT numbers were not significantly different between TNC and VNC images (P > 0.05). In renal cortex-to-RFA site, CNR between linearly blended and IO images was not significantly different (P > 0.05). The VNC imaging quality from the two phases was given a good rating. Conclusion: VNC and IO images from DECT may allow acceptable diagnostic performance with less radiation exposure as a follow-up imaging tool after RFA for RCC, compared to the linearly blended CT images

  5. Dual-energy CT in assessing therapeutic response to radiofrequency ablation of renal cell carcinomas.

    Science.gov (United States)

    Park, Sung Yoon; Kim, Chan Kyo; Park, Byung Kwan

    2014-02-01

    To investigate the utility of dual-energy (DE) CT using virtual noncontrast (VNC) and iodine overlay (IO) images to assess therapeutic response to radiofrequency ablation (RFA) for renal cell carcinomas (RCCs). In this institutional review board-approved study (with waiver of informed consent), 47 patients with RCCs that underwent DECT after RFA were enrolled in this study. DECT protocols included true noncontrast (TNC), linearly blended DE corticomedullary and late nephrographic phase imaging. Two types of VNC and IO images were derived from corticomedullary and late nephrographic phases, respectively. To predict local tumor progression at RFA site, linearly blended and IO images were analyzed both qualitatively and quantitatively. Contrast-to-noise ratios (CNR) of renal cortex-to-RFA zones were calculated. The overall imaging quality of VNC images was compared with TNC images. The IO images from corticomedullary and late nephrographic phases showed excellent diagnostic performance (each sensitivity 100% and each specificity 91.5%) for predicting local tumor progression. The degree of enhancement of local tumor progression was not significantly different between linearly blended and IO images (P>0.05). The mean CT numbers were not significantly different between TNC and VNC images (P>0.05). In renal cortex-to-RFA site, CNR between linearly blended and IO images was not significantly different (P>0.05). The VNC imaging quality from the two phases was given a good rating. VNC and IO images from DECT may allow acceptable diagnostic performance with less radiation exposure as a follow-up imaging tool after RFA for RCC, compared to the linearly blended CT images. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

  6. Thymic epithelial tumors: Comparison of CT and MR imaging findings of low-risk thymomas, high-risk thymomas, and thymic carcinomas

    International Nuclear Information System (INIS)

    Sadohara, Junko; Fujimoto, Kiminori; Mueller, Nestor L.; Kato, Seiya; Takamori, Shinzo; Ohkuma, Kazuaki; Terasaki, Hiroshi; Hayabuchi, Naofumi

    2006-01-01

    Objective: To assess the CT and magnetic resonance (MR) imaging findings of thymic epithelial tumors classified according to the current World Health Organization (WHO) histologic classification and to determine useful findings in differentiating the main subtypes. Materials and methods: Sixty patients with thymic epithelial tumor who underwent both CT and MR imaging were reviewed retrospectively. All cases were classified according to the 2004 WHO classification. The following findings were assessed in each case on both CT and MRI: size of tumor, contour, perimeter of capsule; homogeneity, presence of septum, hemorrhage, necrotic or cystic component within tumor; presence of mediastinal lymphadenopathy, pleural effusion, and great vessel invasion. These imaging characteristics of 30 low-risk thymomas (4 type A, 12 type AB, and 14 type B1), 18 high-risk thymomas (11 type B2 and seven type B3), and 12 thymic carcinomas on CT and MR imaging were compared using the chi-square test. Comparison between CT and MR findings was performed by using McNemar test. Results: On both CT and MR imaging, thymic carcinomas were more likely to have irregular contours (P < .001), necrotic or cystic component (P < .05), heterogeneous contrast-enhancement (P < .05), lymphadenopathy (P < .0001), and great vessel invasion (P < .001) than low-risk and high-risk thymomas. On MR imaging, the findings of almost complete capsule, septum, and homogenous enhancement were more commonly seen in low-risk thymomas than high-risk thymomas and thymic carcinomas (P < .05). MR imaging was superior to CT in the depiction of capsule, septum, or hemorrhage within tumor (all comparison, P < .05). Conclusion: The presence of irregular contour, necrotic or cystic component, heterogeneous enhancement, lymphadenopathy, and great vessel invasion on CT or MR imaging are strongly suggestive of thymic carcinomas. On MR imaging, the findings of contour, capsule, septum, and homogenous enhancement are helpful in

  7. Dual-source dual-energy CT for the differentiation of urinary stone composition: preliminary study

    International Nuclear Information System (INIS)

    Yang Qifang; Zhang Wanshi; Meng Limin; Shi Huiping; Wang Dong; Bi Yongmin; Li Xiangsheng; Fang Hong; Guo Heqing; Yan Jingmin

    2011-01-01

    Objective: To evaluate dual-source dual-energy CT (DSCT) for the differentiation of' urinary stone composition in vitro. Methods: Ninety-seven urinary stones were obtained by endoscopic lithotripsy and scanned using dual-source dual-energy CT. The stones were divided into six groups according to infrared spectroscopy stone analysis: uric acid (UA) stones (n=10), cystine stones (n=5), struvite stones (n=6), calcium oxalate (CaOx) stones (n=22), mixed UA stones (n=7) and mixed calcium stones (n=47). Hounsfield units (HU) of each stone were recorded for the 80 kV and the 140 kV datasets by hand-drawing method. HU difference, HU ratio and dual energy index (DEI) were calculated and compared among the stone groups with one-way ANOVA. Using dual energy software to determine the composition of all stones, results were compared to infrared spectroscopy analysis. Results: There were statistical differences in HU difference [(-17±13), (229±34), (309±45), (512±97), (201±64) and (530±71) HU respectively], in HU ratio (0.96±0.03, 1.34±0.04, 1.41±0.03, 1.47±0.03, 1.30±0.07, and 1.49±0.03 respectively), and DEI (-0.006±0.004, 0.064±0.007, 0.080± 0.007, 0.108±0.011, 0.055±0.014 and 0.112±0.008 respectively) among different stone groups (F= 124.894, 407.028, 322.864 respectively, P<0.01). There were statistical differences in HU difference, HU ratio and DEI between UA stones and the other groups (P<0.01). There were statistical differences in HU difference, HU ratio and DEI between CaOx or mixed calcium stones and the other four groups (P< 0.01). There was statistical difference in HU ratio between cystine and struvite stones (P<0.01). There were statistical differences in HU difference, HU ratio and DEI between struvite and mixed UA stones (P< 0.05). Dual energy software correctly characterized 10 UA stones, 4 cystine stones, 22 CaOx stones and 6 mixed UA stones. Two struvite stones were considered to contain cystine. One cystine stone, 1 mixed UA stone, 4

  8. TH-EF-207A-06: High-Resolution Optical-CT/ECT Imaging of Unstained Mice Femur, Brain, Spleen, and Tumor

    International Nuclear Information System (INIS)

    Yoon, S; Dewhirst, M; Oldham, M; Boss, M; Birer, S

    2016-01-01

    Purpose: Optical transmission and emission computed tomography (optical-CT/ECT) provides high-resolution 3D attenuation and emission maps in unsectioned large (∼1cm 3 ) ex vivo tissue samples at a resolution of 12.9µm 3 per voxel. Here we apply optical-CT/ECT to investigate high-resolution structure and auto-fluorescence in a range of optically cleared mice organs, including, for the first time, mouse bone (femur), opening the potential for study of bone metastasis and bone-mediated immune response. Methods: Three BALBc mice containing 4T1 flank tumors were sacrificed to obtain spleen, brain, tumor, and femur. Tissues were washed in 4% PFA, fixed in EtOH solution (for 5, 10, 10, and 2 days respectively), and then optically cleared for 3 days in BABBs. The femur was also placed in 0.25M aqueous EDTA for 15–30 days to remove calcium. Optical-CT/ECT attenuation and emission maps at 633nm (the latter using 530nm excitation light) were obtained for all samples. Bi-telecentric optical-CT was compared side-by-side with conventional optical projection tomography (OPT) imaging to evaluate imaging capability of these two rival techniques. Results: Auto-fluorescence mapping of femurs reveals vasculatures and fluorescence heterogeneity. High signals (A.U.=10) are reported in the medullary cavity but not in the cortical bone (A.U.=1). The brain strongly and uniform auto-fluoresces (A.U.=5). Thick, optically dense organs such as the spleen and the tumor (0.12, 0.46OD/mm) are reconstructed at depth without significant loss of resolution, which we attribute to the bi-telecentric optics of optical-CT. The attenuation map of tumor reveals vasculature, attenuation heterogeneity, and possibly necrotic tissue. Conclusion: We demonstrate the feasibility of optical-CT/ECT imaging of un-sectioned mice bones (femurs) and spleen with high resolution. This result, and the characterization of unstained organs, are important steps enabling future studies involving optical-CT/ECT applied

  9. CT diagnosis of acute spinal injury

    International Nuclear Information System (INIS)

    Ohhama, Mitsuru; Niimiya, Hikosuke; Kimura, Ko; Yamazaki, Gyoji; Nasu, Yoshiro; Shioya, Akihide

    1982-01-01

    CT pictures of 22 acute spinal injuries with damage of the spinal cord were evaluated. In the cases of spinal cord damage with bone injury, changes in the vertebral canal were fully observed by CT. In some of spinal cord damages without bone injury, narrowing of the vertebral canal was demonstrated by CT combined with CT myelography and reconstruction. Evaluation of CT number showed a high density area in damaged spinal cord in some cases. CT was thus considered to be useful as an adjunct diagnostic aid. (Ueda, J.)

  10. Detection of Bone Marrow Edema in Nondisplaced Hip Fractures: Utility of a Virtual Noncalcium Dual-Energy CT Application.

    Science.gov (United States)

    Kellock, Trenton T; Nicolaou, Savvas; Kim, Sandra S Y; Al-Busaidi, Sultan; Louis, Luck J; O'Connell, Tim W; Ouellette, Hugue A; McLaughlin, Patrick D

    2017-09-01

    Purpose To quantify the sensitivity and specificity of dual-energy computed tomographic (CT) virtual noncalcium images in the detection of nondisplaced hip fractures and to assess whether obtaining these images as a complement to bone reconstructions alters sensitivity, specificity, or diagnostic confidence. Materials and Methods The clinical research ethics board approved chart review, and the requirement to obtain informed consent was waived. The authors retrospectively identified 118 patients who presented to a level 1 trauma center emergency department and who underwent dual-energy CT for suspicion of a nondisplaced traumatic hip fracture. Clinical follow-up was the standard of reference. Three radiologists interpreted virtual noncalcium images for traumatic bone marrow edema. Bone reconstructions for the same cases were interpreted alone and then with virtual noncalcium images. Diagnostic confidence was rated on a scale of 1 to 10. McNemar, Fleiss κ, and Wilcoxon signed-rank tests were used for statistical analysis. Results Twenty-two patients had nondisplaced hip fractures and 96 did not have hip fractures. Sensitivity with virtual noncalcium images was 77% and 91% (17 and 20 of 22 patients), and specificity was 92%-99% (89-95 of 96 patients). Sensitivity increased by 4%-5% over that with bone reconstruction images alone for two of the three readers when both bone reconstruction and virtual noncalcium images were used. Specificity remained unchanged (99% and 100%). Diagnostic confidence in the exclusion of fracture was improved with combined bone reconstruction and virtual noncalcium images (median score: 10, 9, and 10 for readers 1, 2, and 3, respectively) compared with bone reconstruction images alone (median score: 9, 8, and 9). Conclusion When used as a supplement to standard bone reconstructions, dual-energy CT virtual noncalcium images increased sensitivity for the detection of nondisplaced traumatic hip fractures and improved diagnostic confidence in

  11. High impact of FDG-PET/CT in diagnostic strategies for ovarian cancer

    International Nuclear Information System (INIS)

    Zytoon, Ashraf Anas; Murakami, Koji; Eid, Hazem; El-Gammal, Mahmoud

    2013-01-01

    Background: Ovarian cancer has the highest mortality of all gynecologic malignancies. FDG-PET/CT was proven to be accurate for identification of primary ovarian tumors, regional lymph nodes, and distant metastases. Purpose: To evaluate ovarian masses at FDG-PET/CT in correlation with histopathologic findings. Material and Methods: Ninety-eight patients underwent whole body FDG-PET/CT examination. Eighty-six patients with primary ovarian cancer and 12 patients with metastatic disease to the ovaries were included. Results: PET/CT imaging was true-positive in 87/94 patients with malignant tumors. In 4/4 patients with benign tumors, PET/CT results were true-negative, with sensitivity of 92.6%, specificity 100%, total test accuracy 92.9%. Fifty-seven patients were diagnosed as stage IV ovarian cancer with distant metastasis. Conclusion: The anatomical/functional examination by FDG-PET/CT was proven to be valuable in increasing the diagnostic accuracy that can help improve patient management

  12. Role of focused assessment with sonography for trauma as a screening tool for blunt abdominal trauma in young children after high energy trauma

    NARCIS (Netherlands)

    Tummers, W.; van Schuppen, J.; Langeveld, H.; Wilde, J.; Banderker, E.; van As, A.

    2016-01-01

    The objective of the study was to review the utility of focused assessement with sonography for trauma (FAST) as a screening tool for blunt abdominal trauma (BAT) in children involved in high energy trauma (HET), and to determine whether a FAST could replace computed tomography (CT) in clinical

  13. Physics and basic technology of CT

    International Nuclear Information System (INIS)

    Mahesh, Mahadevappa

    2017-01-01

    Computed Tomography is one of the prime imaging modalities in any hospital around the globe. From its inception in 1973, CT technology have advanced leaps and bounds in medical diagnosis. Advances in X-ray tubes, detection technologies and image reconstruction methods led to the development of multiple-row detector CT (MDCT) technologies in early 2000, that has been the impetus for new fields such as Cardiovascular CT, Hybrid CT (PET-CT and SPECT-CT), CT Perfusion, Cone Beam CT, etc. It is now possible to image the entire organ (such as heart) in less than 0.3 seconds providing isotropic resolution images with high temporal resolution. With all X-ray imaging modalities, including CT, the concern is the radiation dose. Since CT procedures are one of the major imaging procedures performed in any hospital, it is important to optimize CT protocols in order to provide quality images at optimal radiation dose

  14. High energy neutron radiography

    International Nuclear Information System (INIS)

    Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

    1996-01-01

    High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos

  15. Coronary CT angiography: Diagnostic value and clinical challenges.

    Science.gov (United States)

    Sabarudin, Akmal; Sun, Zhonghua

    2013-12-26

    Coronary computed tomography (CT) angiography has been increasingly used in the diagnosis of coronary artery disease due to improved spatial and temporal resolution with high diagnostic value being reported when compared to invasive coronary angiography. Diagnostic performance of coronary CT angiography has been significantly improved with the technological developments in multislice CT scanners from the early generation of 4-slice CT to the latest 320- slice CT scanners. Despite the promising diagnostic value, coronary CT angiography is still limited in some areas, such as inferior temporal resolution, motion-related artifacts and high false positive results due to severe calcification. The aim of this review is to present an overview of the technical developments of multislice CT and diagnostic value of coronary CT angiography in coronary artery disease based on different generations of multislice CT scanners. Prognostic value of coronary CT angiography in coronary artery disease is also discussed, while limitations and challenges of coronary CT angiography are highlighted.

  16. Dual-energy X-ray micro-CT imaging of hybrid Ni/Al open-cell foam

    International Nuclear Information System (INIS)

    Fíla, T.; Koudelka, P.; Zlámal, P.; Jiroušek, O.; Kumpová, I.; Vavřík, D.; Jung, A.

    2016-01-01

    In this paper, we employ dual-energy X-ray microfocus tomography (DECT) measurement to develop high-resolution finite element (FE) models that can be used for the numerical assessment of the deformation behaviour of hybrid Ni/Al foam subjected to both quasi-static and dynamic compressive loading. Cubic samples of hybrid Ni/Al open-cell foam with an edge length of [15]mm were investigated by the DECT measurement. The material was prepared using AlSi 7 Mg 0.3 aluminium foam with a mean pore size of [0.85]mm, coated with nanocrystalline nickel (crystallite size of approx. [50]nm) to form a surface layer with a theoretical thickness of [0.075]mm. CT imaging was carried out using state-of-the-art DSCT/DECT X-ray scanner developed at Centre of Excellence Telč. The device consists of a modular orthogonal assembly of two tube-detector imaging pairs, with an independent geometry setting and shared rotational stage mounted on a complex 16-axis CNC positioning system to enable unprecedented measurement variability for highly-detailed tomographical measurements. A sample of the metal foam was simultaneously irradiated using an XWT-240-SE reflection type X-ray tube and an XWT-160-TCHR transmission type X-ray tube. An enhanced dual-source sampling strategy was used for data acquisition. X-ray images were taken using XRD1622 large area GOS scintillator flat panel detectors with an active area of [410 × 410]mm and resolution [2048 × 2048]pixels. Tomographic scanning was performed in 1,200 projections with a 0.3 degree angular step to improve the accuracy of the generated models due to the very complex microstructure and high attenuation of the investigated material. Reconstructed data was processed using a dual-energy algorithm, and was used for the development of a 3D model and voxel model of the foam. The selected parameters of the models were compared with nominal parameters of the actual foam and showed good correlation

  17. Gyral high density on CT scan after head injury; [sup 123]I-IMP SPECT and MRI findings in three children

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Takumi; Matsumoto, Kiyoshi (Showa Univ., Tokyo (Japan). School of Medicine); Sakamoto, Tetsuya; Aruga, Tohru

    1994-02-01

    The authors treated three children who had 'gyral high density' on plain CT scans after head injury with acute subdural hematoma. [sup 123]I-IMP SPECT (IMP) and MRI in the chronic stage were performed. All were males, about one year of age, with acute subdural hematoma. CT scan 48 hours after injury showed diffuse low density in the ipsilateral parenchyma with minimum midline shift, and IMP showed decreased activity in the same area. Plain CT scan 1 to 3 weeks after injury showed remarkably high density along the gyri in part of the same area. This area was markedly enhanced on CT with contrast medium and showed decreased blood flow on IMP. This high density area disappeared within 2 months after injury and the area concerned showed brain atrophy. In the chronic stage (after 6 months), only the high density area along the gyri seen in the CT scan showed MRI evidence of ishemia, but there was no definite evidence of hemorrhage. All three children had hemiplegia at the time of discharge. The gyral high density suggests ischemic brain, but the pathophysiological process might be different from that of so-called hemorrhagic infarction. Presumably, it is due to incomplete autoregulation, the incomplete blood-brain barrier and the sensitivity to stimulation of cerebral blood vessels in the brains of infants. The intensity and range of the gyral high density are considered to be important in estimating the future amount of atrophic change in the insulted brain and the resulting sequelae. (author).

  18. PET/CT: underlying physics, instrumentation, and advances.

    Science.gov (United States)

    Torres Espallardo, I

    Since it was first introduced, the main goal of PET/CT has been to provide both PET and CT images with high clinical quality and to present them to radiologists and specialists in nuclear medicine as a fused, perfectly aligned image. The use of fused PET and CT images quickly became routine in clinical practice, showing the great potential of these hybrid scanners. Thanks to this success, manufacturers have gone beyond considering CT as a mere attenuation corrector for PET, concentrating instead on design high performance PET and CT scanners with more interesting features. Since the first commercial PET/CT scanner became available in 2001, both the PET component and the CT component have improved immensely. In the case of PET, faster scintillation crystals with high stopping power such as LYSO crystals have enabled more sensitive devices to be built, making it possible to reduce the number of undesired coincidence events and to use time of flight (TOF) techniques. All these advances have improved lesion detection, especially in situations with very noisy backgrounds. Iterative reconstruction methods, together with the corrections carried out during the reconstruction and the use of the point-spread function, have improved image quality. In parallel, CT instrumentation has also improved significantly, and 64- and 128-row detectors have been incorporated into the most modern PET/CT scanners. This makes it possible to obtain high quality diagnostic anatomic images in a few seconds that both enable the correction of PET attenuation and provide information for diagnosis. Furthermore, nowadays nearly all PET/CT scanners have a system that modulates the dose of radiation that the patient is exposed to in the CT study in function of the region scanned. This article reviews the underlying physics of PET and CT imaging separately, describes the changes in the instrumentation and standard protocols in a combined PET/CT system, and finally points out the most important

  19. Parametric boundary reconstruction algorithm for industrial CT metrology application.

    Science.gov (United States)

    Yin, Zhye; Khare, Kedar; De Man, Bruno

    2009-01-01

    High-energy X-ray computed tomography (CT) systems have been recently used to produce high-resolution images in various nondestructive testing and evaluation (NDT/NDE) applications. The accuracy of the dimensional information extracted from CT images is rapidly approaching the accuracy achieved with a coordinate measuring machine (CMM), the conventional approach to acquire the metrology information directly. On the other hand, CT systems generate the sinogram which is transformed mathematically to the pixel-based images. The dimensional information of the scanned object is extracted later by performing edge detection on reconstructed CT images. The dimensional accuracy of this approach is limited by the grid size of the pixel-based representation of CT images since the edge detection is performed on the pixel grid. Moreover, reconstructed CT images usually display various artifacts due to the underlying physical process and resulting object boundaries from the edge detection fail to represent the true boundaries of the scanned object. In this paper, a novel algorithm to reconstruct the boundaries of an object with uniform material composition and uniform density is presented. There are three major benefits in the proposed approach. First, since the boundary parameters are reconstructed instead of image pixels, the complexity of the reconstruction algorithm is significantly reduced. The iterative approach, which can be computationally intensive, will be practical with the parametric boundary reconstruction. Second, the object of interest in metrology can be represented more directly and accurately by the boundary parameters instead of the image pixels. By eliminating the extra edge detection step, the overall dimensional accuracy and process time can be improved. Third, since the parametric reconstruction approach shares the boundary representation with other conventional metrology modalities such as CMM, boundary information from other modalities can be directly

  20. Dual-energy CT iodine maps as an alternative quantitative imaging biomarker to abdominal CT perfusion: determination of appropriate trigger delays for acquisition using bolus tracking.

    Science.gov (United States)

    Skornitzke, Stephan; Fritz, Franziska; Mayer, Philipp; Koell, Marco; Hansen, Jens; Pahn, Gregor; Hackert, Thilo; Kauczor, Hans-Ulrich; Stiller, Wolfram

    2018-05-01

    Quantitative evaluation of different bolus tracking trigger delays for acquisition of dual energy (DE) CT iodine maps as an alternative to CT perfusion. Prior to this retrospective analysis of prospectively acquired data, DECT perfusion sequences were dynamically acquired in 22 patients with pancreatic carcinoma using dual source CT at 80/140 kV p with tin filtration. After deformable motion-correction, perfusion maps of blood flow (BF) were calculated from 80 kV p image series of DECT, and iodine maps were calculated for each of the 34 DECT acquisitions per patient. BF and iodine concentrations were measured in healthy pancreatic tissue and carcinoma. To evaluate potential DECT acquisition triggered by bolus tracking, measured iodine concentrations from the 34 DECT acquisitions per patient corresponding to different trigger delays were assessed for correlation to BF and intergroup differences between tissue types depending on acquisition time. Average BF measured in healthy pancreatic tissue and carcinoma was 87.6 ± 28.4 and 38.6 ± 22.2 ml/100 ml min -1 , respectively. Correlation between iodine concentrations and BF was statistically significant for bolus tracking with trigger delay greater than 0 s (r max = 0.89; p alternative to CT perfusion measurements of BF. Advances in knowledge: After clinical validation, DECT iodine maps of pancreas acquired using bolus tracking with appropriate trigger delay as determined in this study could offer an alternative quantitative imaging biomarker providing functional information for tumor assessment at reduced patient radiation exposure compared to CT perfusion measurements of BF.

  1. Evaluation of radiation exposure with singleslice- and a multislice-spiral CT system (a phantom study)

    International Nuclear Information System (INIS)

    Giacomuzzi, S.M.; Rieger, M.; Lottersberger, C.; Peer, S.; Peer, R.; Buchberger, W.; Bale, R.; Mallouhi, A.; Jaschke, W.; Torbica, P.; Perkmann, R.

    2001-01-01

    The purpose of study was to compare patient dose applying singleslice- and multislice-spiral CT. Methods: The examinations were performed with a singleslice-spiral CT (Highspeed Advantage; GE Medical Systems; Milwaukee, USA) and with a multislice CT systems (LightSpeed QX/i GE Medical Systems; Milwaukee, USA). For the determination of the radiation exposure (absorbed dose) a selection of most executed protocols (thorax-helical, abdomen-helical, petrous bone-axial, head-axial) were simulated using an Alderson Rando Phantom. The dose was determined by means of lithiumfluorid-thermoluminescence dosimeters (TLD-GR 200). Results: For thorax and abdomen protocols higher energy dose values could be found using a multislice CT. On the average the energy dose values were increased by 2.6 on an average in relation to single slice spiral CT. The energy dose values of the multisclice CT using head protocols could be reduced by 30% in relation to single slice spiral CT due to suitable parameter selections. The energy dose applying a petrous bone protocol resulted in an average increase by a factor 1.5 using a multislice CT. Conclusion: Using the new multislice CT technique protocol strategies must be optimized regarding the patient doses. Users can operate critically in the sense of the radiation protection only if they are aware of the occurring dose amounts to the patient. (orig.) [de

  2. Examination of hepatic dynamic CT images following infusion of high-concentration contrast media

    International Nuclear Information System (INIS)

    Takeyama, Nobuyuki; Hayashi, Takaki; Kinebuchi, Yuko; Kitahara, Tadashi; Ohbuchi, Masao; Shinjyo, Hidenori; Ohgiya, Yoshimitsu

    2008-01-01

    There are scarce examinations on the integrated effects of given iodine weight (mgI) and its rate (mgI/sec) on the quality and diagnostic accuracy in the hepatic contrast CT imaging while the former is known to affect the image of parenchyma and the latter, of arterial systems. The purpose of this study is to analyze and evaluate the effects qualitatively and quantitatively in hepatic dynamic CT images of patients with moderate body weight in whom different concentrations of I are given at the same flux rate and total weight. Patients having chronic hepatitis suspicious of carcinoma, or cirrhosis were 52-84 years old (M 50/F 55, b. wt. 50-65 kg) and were randomly divided in A and B group. A group received infusion of 25 sec in the right elbow vein of iopamidol, 300 mgI/100 mL, and B group, 370 mgI/80 mL: the I flux of ca. 1.2 gI/sec and total I of ca. 30 gI. Before and at 25 (early arterial phase), 40 (late art. phase), 70 (portal vein) and 180 (equilibrium) sec after infusion, CT images were obtained with the machine Light Speed select (GE Healthcare), Housfield Units before and after enhancing were used for quantitative evaluation, three experts qualitatively read images, and PACS system in Synapse 3.1.0 (Fuji Film Med.) was used for observation of tumor nodules if present. Neither qualitative nor quantitative differences were found in these CT images of the 4 phases and use of high-concentration contrast media was confirmed to be possible for lowered infusion rate. Authors also pointed out the importance of care for radiation exposure in this CT technique. (R.T.)

  3. Prospective evaluation of solitary thyroid nodule on 18F-FDG PET/CT and high-resolution ultrasonography

    International Nuclear Information System (INIS)

    D'Souza, M.M.; Marwaha, R.K.; Sharma, R.

    2010-01-01

    The utility of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the assessment of thyroid nodules is unclear as there are several conflicting reports on the usefulness of standardized uptake value (SUV) as an indicator to distinguish benign from malignant thyroid lesions. This study incorporated an additional parameter, namely dual time point imaging, to determine the diagnostic accuracy of PET/CT imaging. The performance of 18F-FDG PET/CT was compared to that of high-resolution ultrasound which is routinely used for the evaluation of thyroid nodules. Two hundred patients with incidentally detected solitary thyroid nodules were included in the study. Each patient underwent ultrasound and PET/CT evaluation within 7 days of each other, reported by an experienced radiologist and nuclear medicine specialist, respectively, in a blinded manner. The PET/CT criteria employed were maximum SUV (SUV max ) at 60 min and change in SUV max at delayed (120 min) imaging. Final diagnosis was based on pathological evaluation and follow-up. Of the 200 patients, 26 had malignant and 174 had benign nodules. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of ultrasound were 80.8, 81.6, 39.6, 96.6 and 81.5%, respectively. Using SUV max at 60 min as the diagnostic criterion, the above indices were 80.8, 84.5, 43.8, 96.7 and 84%, respectively, for PET/CT. The SUV max of malignant thyroid lesions was significantly higher than benign lesions (16.2±10.6 vs. 4.5±3.1, respectively; p=0.0001). Incorporation of percentage change in SUV max at delayed imaging as the diagnostic criterion yielded a slightly improved sensitivity, specificity, PPV, NPV and accuracy of 84.6, 85.6, 46.8, 97.4 and 85.5%, respectively. There was a significant difference in percentage change in SUV max between malignant and benign thyroid lesions (14.9±11.4 vs. -1.6±13.7, respectively; p=0.0001). However, there was no statistically

  4. Use of high concentration contrast media (HCCM): principles and rationale--body CT

    International Nuclear Information System (INIS)

    Brink, James A.

    2003-01-01

    Numerous complex pharmacokinetic interrelationships affect the use of contrast media for computed tomography (CT) imaging. The volume, concentration, and rate of injection, all affect the degree of enhancement that is achieved with an injection of contrast material. In addition, the injection technique, whether the contrast is infused with a constant injection rate (uniphasic injection) or whether the rate is altered during the injection (multiphasic injection) also affect the magnitude and duration of contrast enhancement. In body CT imaging, the liver poses unique challenges in managing the use of intravenous contrast material because of its dual blood supply and the need to complete imaging before equilibrium occurs between the intravascular and extravascular compartments. The magnitude of hepatic enhancement that is ultimately achieved is related primarily to the amount of iodinated contrast material that accumulates in the extravascular space within the target organ, independent of the speed of the CT scanner. The key determinant of the onset of the equilibrium phase is the injection duration. Given that a high injection flow rate (4-5 ml/s) is desirable for arterial phase imaging, the injection duration is maintained with use of an appropriate contrast volume. Thus, modifications of total iodine dose are best done with alterations in contrast concentration. The magnitude of arterial enhancement that is achieved is related to both the concentration and rate of contrast administration. The speed of the scanner determines its ability to record image data during the most advantageous time period, the peak of arterial enhancement. Thus, rapid imaging is particularly advantageous for optimal contrast use in CT angiography as well as in multiphasic imaging of the parenchymal organs

  5. Urinary calculi composed of uric acid, cystine, and mineral salts: differentiation with dual-energy CT at a radiation dose comparable to that of intravenous pyelography.

    Science.gov (United States)

    Thomas, Christoph; Heuschmid, Martin; Schilling, David; Ketelsen, Dominik; Tsiflikas, Ilias; Stenzl, Arnulf; Claussen, Claus D; Schlemmer, Heinz-Peter

    2010-11-01

    To retrospectively evaluate radiation dose, image quality, and the ability to differentiate urinary calculi of differing compositions by using low-dose dual-energy computed tomography (CT). The institutional review board approved this retrospective study; informed consent was waived. A low-dose dual-energy CT protocol (tube voltage and reference effective tube current-time product, 140 kV and 23 mAs and 80 kV and 105 mAs; collimation, 64 × 0.6 mm; pitch, 0.7) for the detection of urinary calculi was implemented into routine clinical care. All patients (n = 112) who were examined with this protocol from July 2008 to August 2009 were included. The composition of urinary calculi was assessed by using commercially available postprocessing software and was compared with results of the reference standard (ex vivo infrared spectroscopy) in 40 patients for whom the reference standard was available. Effective doses were calculated. Image quality was rated subjectively and objectively and was correlated with patient size expressed as body cross-sectional area at the level of acquisition by using Spearman correlation coefficients. One calcified concrement in the distal ureter of an obese patient was mistakenly interpreted as mixed calcified and uric acid. One struvite calculus was falsely interpreted as cystine. All other uric acid, cystine, and calcium-containing calculi were correctly identified by using dual-energy CT. The mean radiation dose was 2.7 mSv. The average image quality was rated as acceptable, with a decrease in image quality in larger patients. Low-dose unenhanced dual-source dual-energy CT can help differentiate between calcified, uric acid, and cystine calculi at a radiation dose comparable to that of conventional intravenous pyelography. Because of decreased image quality in obese patients, only nonobese patients should be examined with this protocol. © RSNA, 2010.

  6. {sup 18}F-FDG PET/contrast enhanced CT in the standard surveillance of high risk colorectal cancer patients

    Energy Technology Data Exchange (ETDEWEB)

    Jiménez Londoño, Germán Andrés, E-mail: gjimenez91@yahoo.com [Department of Nuclear Medicine, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); García Vicente, Ana María [Department of Nuclear Medicine, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); Sánchez Pérez, Victoria [Department of Oncology, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); Jiménez Aragón, Fátima [Department of Radiology, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); León Martin, Alberto [Investigation Unit, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); Cano Cano, Juana María [Department of Oncology, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); Domínguez Ferreras, Esther [Department of Radiology, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); Gómez López, Ober Van [Department of Nuclear Medicine, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); Espinosa Arranz, Javier [Department of Oncology, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain); Soriano Castrejón, Ángel María [Department of Nuclear Medicine, Hospital General Universitario de Ciudad Real, Ciudad Real (Spain)

    2014-12-15

    Highlights: • We assessed the accuracy of FDG-PET/contrast enhanced CT (FDG-PET/ceCT) in the detection of unsuspected recurrence of colorectal cancer. In regard to our knowledge, no previous experience has been reported about the combined acquisition and interpretation of a FDG-PET/ceCT in the surveillance of colorectal cancer. • We designed a prospective study and performed an individual and combined assessment of both techniques (PET and ceCT), in a patient-based analysis and a lesion-based analysis. • The value of PET and ceCT was found to be similar in the detection of unsuspected recurrence of CRC in a patient-based analysis. The most interesting of our result, is that the combined assessment of PET/ceCT improves the accuracy in the lesion-based analysis. - Abstract: Objective: To assess the accuracy of FDG-PET/contrast enhanced CT (FDG-PET/ceCT) in the detection of unsuspected recurrence of colorectal cancer (CRC) in patients with high risk of relapse. Methods: Thirty-three patients (14 females and 19 males, mean age: 62, range: 41–78), with CRC in complete remission, were prospectively included. All patients underwent FDG-PET/ceCT (58 studies). FDG-PET/ceCT was requested in the surveillance setting, and performed following a standardized protocol. A portal venous phase CT scan was performed after the injection of iodinated contrast agent. An individual and combined assessment of both techniques (PET and ceCT) was performed. Concordant and discordant findings of PET, ceCT and FDG-PET/ceCT were compared in a patient-based and a lesion-based analysis. The final diagnosis, recurrence or disease free status (DFS), were established by histopathology or clinical/radiological follow-up of at least 6 months. Results: Seven out of 33 patients had a confirmed recurrence and the rest of patients had a DFS. In a patient-based analysis the sensitivity and specificity of PET, ceCT and PET/ceCT was of 86% and 88%, 86% and 92%, 86% and 85%, respectively. Attending to

  7. Dynamic CT myocardial perfusion imaging

    International Nuclear Information System (INIS)

    Caruso, Damiano; Eid, Marwen; Schoepf, U. Joseph; Jin, Kwang Nam; Varga-Szemes, Akos; Tesche, Christian; Mangold, Stefanie

    2016-01-01

    Highlights: • CT myocardial perfusion provides functional assessment of the myocardium. • CCTA is limited in determining the hemodynamic significance of coronary stenosis. • CT-MPI can accurately detect hemodynamically significant coronary artery stenosis. - Abstract: Non-invasive cardiac imaging has rapidly evolved during the last decade due to advancements in CT based technologies. Coronary CT angiography has been shown to reliably assess coronary anatomy and detect high risk coronary artery disease. However, this technique is limited to anatomical assessment, thus non-invasive techniques for functional assessment of the heart are necessary. CT myocardial perfusion is a new CT based technique that provides functional assessment of the myocardium and allows for a comprehensive assessment of coronary artery disease with a single modality when combined with CTA. This review aims to discuss dynamic CT myocardial perfusion as a new technique in the assessment of CAD.

  8. Dynamic CT myocardial perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Caruso, Damiano [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Radiological Sciences, Oncological and Pathological Sciences, University of Rome “Sapienza”, Latina (Italy); Eid, Marwen [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Schoepf, U. Joseph, E-mail: schoepf@musc.edu [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC (United States); Jin, Kwang Nam [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Radiology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul (Korea, Republic of); Varga-Szemes, Akos [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Tesche, Christian [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Cardiology and Intensive Care Medicine, Heart Center Munich-Bogenhausen, Munich (Germany); Mangold, Stefanie [Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (United States); Department of Diagnostic and Interventional Radiology, University Hospital of Tuebingen, Tuebingen (Germany); and others

    2016-10-15

    Highlights: • CT myocardial perfusion provides functional assessment of the myocardium. • CCTA is limited in determining the hemodynamic significance of coronary stenosis. • CT-MPI can accurately detect hemodynamically significant coronary artery stenosis. - Abstract: Non-invasive cardiac imaging has rapidly evolved during the last decade due to advancements in CT based technologies. Coronary CT angiography has been shown to reliably assess coronary anatomy and detect high risk coronary artery disease. However, this technique is limited to anatomical assessment, thus non-invasive techniques for functional assessment of the heart are necessary. CT myocardial perfusion is a new CT based technique that provides functional assessment of the myocardium and allows for a comprehensive assessment of coronary artery disease with a single modality when combined with CTA. This review aims to discuss dynamic CT myocardial perfusion as a new technique in the assessment of CAD.

  9. High-pitch coronary CT angiography in dual-source CT during free breathing vs. breath holding in patients with low heart rates

    Energy Technology Data Exchange (ETDEWEB)

    Bischoff, Bernhard, E-mail: bernhard.bischoff@med.uni-muenchen.de [Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich (Germany); DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich (Germany); Meinel, Felix G. [Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich (Germany); DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich (Germany); Del Prete, Alessandra [Department of Radiology Magrassi-Lanzara, Second University of Naples, Naples (Italy); Reiser, Maximilian F.; Becker, Hans-Christoph [Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich (Germany); DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich (Germany)

    2013-12-01

    Background: Coronary CT angiography (CCTA) is usually performed during breath holding to reduce motion artifacts caused by respiration. However, some patients are not able to follow the breathing commands adequately due to deafness, hearing impairment, agitation or pulmonary diseases. The aim of this study was to evaluate the potential of high-pitch CCTA in free breathing patients when compared to breath holding patients. Methods: In this study we evaluated 40 patients (20 free breathing and 20 breath holding patients) with a heart rate of 60 bpm or below referred for CCTA who were examined on a 2nd generation dual-source CT system. Image quality of each coronary artery segment was rated using a 4-point grading scale (1: non diagnostic–4: excellent). Results: Mean heart rate during image acquisition was 52 ±5 bpm in both groups. There was no significant difference in mean image quality, slightly favoring image acquisition during breath holding (mean image quality score 3.76 ± 0.32 in breath holding patients vs. 3.61 ± 0.45 in free breathing patients; p = 0.411). Due to a smaller amount of injected contrast medium, there was a trend for signal intensity to be slightly lower in free breathing patients, but this was not statistically significant (435 ± 123 HU vs. 473 ± 117 HU; p = 0.648). Conclusion: In patients with a low heart rate who are not able to hold their breath adequately, CCTA can also be acquired during free breathing without substantial loss of image quality when using a high pitch scan mode in 2nd generation dual-source CT.

  10. Detecting Intracranial Hemorrhage Using Automatic Tube Current Modulation With Advanced Modeled Iterative Reconstruction in Unenhanced Head Single- and Dual-Energy Dual-Source CT.

    Science.gov (United States)

    Scholtz, Jan-Erik; Wichmann, Julian L; Bennett, Dennis W; Leithner, Doris; Bauer, Ralf W; Vogl, Thomas J; Bodelle, Boris

    2017-05-01

    The purpose of our study was to determine diagnostic accuracy, image quality, and radiation dose of low-dose single- and dual-energy unenhanced third-generation dual-source head CT for detection of intracranial hemorrhage (ICH). A total of 123 patients with suspected ICH were examined using a dual-source 192-MDCT scanner. Standard-dose 120-kVp single-energy CT (SECT; n = 36) and 80-kVp and 150-kVp dual-energy CT (DECT; n = 30) images were compared with low-dose SECT (n = 32) and DECT (n = 25) images obtained using automated tube current modulation (ATCM). Advanced modeled iterative reconstruction (ADMIRE) was used for all protocols. Detection of ICH was performed by three readers who were blinded to the image acquisition parameters of each image series. Image quality was assessed both quantitatively and qualitatively. Interobserver agreement was calculated using the Fleiss kappa. Radiation dose was measured as dose-length product (DLP). Detection of ICH was excellent (sensitivity, 94.9-100%; specificity, 94.7-100%) in all protocols (p = 1.00) with perfect interobserver agreement (0.83-0.96). Qualitative ratings showed significantly better ratings for both standard-dose protocols regarding gray matter-to-white matter contrast (p ≤ 0.014), whereas highest gray matter-to-white matter contrast-to-noise ratio was observed with low-dose DECT images (p ≥ 0.057). The lowest posterior fossa artifact index was measured for standard-dose DECT, which showed significantly lower values compared with low-dose protocols (p ≤ 0.034). Delineation of ventricular margins and sharpness of subarachnoidal spaces were rated excellent in all protocols (p ≥ 0.096). Low-dose techniques lowered radiation dose by 26% for SECT images (DLP, 575.0 ± 72.3 mGy · cm vs 771.5 ± 146.8 mGy · cm; p dual-source CT while allowing significant radiation dose reduction.

  11. TU-FG-BRB-01: Dual Energy CT Proton Stopping Power Ratio Calibration and Validation with Animal Tissues

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Y; Yin, L; Ainsley, C; McDonough, J; Solberg, T; Lin, A; Teo, B [University of Pennsylvania, Philadelphia, PA (United States)

    2016-06-15

    Purpose: The conversion of Hounsfield Unit (HU) to proton stopping power ratio (SPR) is a main source of uncertainty in proton therapy. In this study, the SPRs of animal tissues were measured and compared with prediction from dual energy CT (DECT) and single energy CT (SECT) calibrations. Methods: A stoichiometric calibration method for DECT was applied to predict the SPR using CT images acquired at 80 kVp and 140 kVp. The dual energy index was derived based on the HUs of the paired spectral images and used to calculate the SPRs of the materials. Tissue surrogates with known chemical compositions were used for calibration, and animal tissues (pig brain, liver, kidney; veal shank, muscle) were used for validation. The materials were irradiated with proton pencil beams, and SPRs were deduced from the residual proton range measured using a multi-layer ion chamber device. In addition, Gafchromic EBT3 films were used to measure the distal dose profiles after irradiation through the tissue samples and compared with those calculated by the treatment planning system using both DECT and SECT predicted SPRs. Results: The differences in SPR between DECT prediction and measurement were −0.31±0.36% for bone, 0.47±0.42% for brain, 0.67±0.15% for liver, 0.51±0.52% for kidney, and −0.96±0.15% for muscle. The corresponding results using SECT were 3.1±0.12%, 1.90±0.45%, −0.66±0.11%, 2.33±0.21%, and −1.70±0.17%. In the film measurements, average distances between film and calculated distal dose profiles were 0.35±0.12 mm for DECT calibration and −1.22±0.12 mm for SECT calibration for a beam with a range of 15.79 cm. Conclusion: Our study indicates that DECT is superior to SECT for proton SPR prediction and has the potential to reduce the range uncertainty to less than 2%. DECT may permit the use of tighter distal and proximal range uncertainty margins for treatment, thereby increasing the precision of proton therapy.

  12. Qualitative and quantitative evaluation of rigid and deformable motion correction algorithms using dual-energy CT images in view of application to CT perfusion measurements in abdominal organs affected by breathing motion.

    Science.gov (United States)

    Skornitzke, S; Fritz, F; Klauss, M; Pahn, G; Hansen, J; Hirsch, J; Grenacher, L; Kauczor, H-U; Stiller, W

    2015-02-01

    To compare six different scenarios for correcting for breathing motion in abdominal dual-energy CT (DECT) perfusion measurements. Rigid [RRComm(80 kVp)] and non-rigid [NRComm(80 kVp)] registration of commercially available CT perfusion software, custom non-rigid registration [NRCustom(80 kVp], demons algorithm) and a control group [CG(80 kVp)] without motion correction were evaluated using 80 kVp images. Additionally, NRCustom was applied to dual-energy (DE)-blended [NRCustom(DE)] and virtual non-contrast [NRCustom(VNC)] images, yielding six evaluated scenarios. After motion correction, perfusion maps were calculated using a combined maximum slope/Patlak model. For qualitative evaluation, three blinded radiologists independently rated motion correction quality and resulting perfusion maps on a four-point scale (4 = best, 1 = worst). For quantitative evaluation, relative changes in metric values, R(2) and residuals of perfusion model fits were calculated. For motion-corrected images, mean ratings differed significantly [NRCustom(80 kVp) and NRCustom(DE), 3.3; NRComm(80 kVp), 3.1; NRCustom(VNC), 2.9; RRComm(80 kVp), 2.7; CG(80 kVp), 2.7; all p VNC), 22.8%; RRComm(80 kVp), 0.6%; CG(80 kVp), 0%]. Regarding perfusion maps, NRCustom(80 kVp) and NRCustom(DE) were rated highest [NRCustom(80 kVp), 3.1; NRCustom(DE), 3.0; NRComm(80 kVp), 2.8; NRCustom(VNC), 2.6; CG(80 kVp), 2.5; RRComm(80 kVp), 2.4] and had significantly higher R(2) and lower residuals. Correlation between qualitative and quantitative evaluation was low to moderate. Non-rigid motion correction improves spatial alignment of the target region and fit of CT perfusion models. Using DE-blended and DE-VNC images for deformable registration offers no significant improvement. Non-rigid algorithms improve the quality of abdominal CT perfusion measurements but do not benefit from DECT post processing.

  13. Children's (Pediatric) CT (Computed Tomography)

    Medline Plus

    Full Text Available ... obtain CT images. It is known that high levels of radiation may cause cancer. However, CT scans result in a low-level exposure. Whether such levels cause cancer is debatable ...

  14. The accuracy of {sup 68}Ga-PSMA PET/CT in primary lymph node staging in high-risk prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Oebek, Can; Doganca, Tuenkut [Acibadem Taksim Hospital, Department of Urology, Istanbul (Turkey); Demirci, Emre [Sisli Etfal Training and Research Hospital, Department of Nuclear Medicine, Istanbul (Turkey); Ocak, Meltem [Istanbul University, Faculty of Pharmacy, Department of Pharmaceutical Technology, Istanbul (Turkey); Kural, Ali Riza [Acibadem University, Department of Urology, Istanbul (Turkey); Yildirim, Asif [Istanbul Medeniyet University, Department of Urology, Istanbul (Turkey); Yuecetas, Ugur [Istanbul Training and Research Hospital, Department of Urology, Istanbul (Turkey); Demirdag, Cetin [Istanbul University, Cerrahpasa School of Medicine, Department of Urology, Istanbul (Turkey); Erdogan, Sarper M. [Istanbul University, Cerrahpasa School of Medicine, Department of Public Health, Istanbul (Turkey); Kabasakal, Levent [Istanbul University, Cerrahpasa School of Medicine, Department of Nuclear Medicine, Istanbul (Turkey); Collaboration: Members of Urooncology Association, Turkey

    2017-10-15

    To assess the diagnostic accuracy of {sup 68}Ga-PSMA PET in predicting lymph node (LN) metastases in primary N staging in high-risk and very high-risk nonmetastatic prostate cancer in comparison with morphological imaging. This was a multicentre trial of the Society of Urologic Oncology in Turkey in conjunction with the Nuclear Medicine Department of Cerrahpasa School of Medicine, Istanbul University. Patients were accrued from eight centres. Patients with high-risk and very high-risk disease scheduled to undergo surgical treatment with extended LN dissection between July 2014 and October 2015 were included. Either MRI or CT was used for morphological imaging. PSMA PET/CT was performed and evaluated at a single centre. Sensitivity, specificity and accuracy were calculated for the detection of lymphatic metastases by PSMA PET/CT and morphological imaging. Kappa values were calculated to evaluate the correlation between the numbers of LN metastases detected by PSMA PET/CT and by histopathology. Data on 51 eligible patients are presented. The sensitivity, specificity and accuracy of PSMA PET in detecting LN metastases in the primary setting were 53%, 86% and 76%, and increased to 67%, 88% and 81% in the subgroup with of patients with ≥15 LN removed. Kappa values for the correlation between imaging and pathology were 0.41 for PSMA PET and 0.18 for morphological imaging. PSMA PET/CT is superior to morphological imaging for the detection of metastatic LNs in patients with primary prostate cancer. Surgical dissection remains the gold standard for precise lymphatic staging. (orig.)

  15. Scope for energy improvement for hospital imaging services in the USA.

    Science.gov (United States)

    Esmaeili, Amin; Twomey, Janet M; Overcash, Michael R; Soltani, Seyed A; McGuire, Charles; Ali, Kamran

    2015-04-01

    To aid radiologists by measuring the carbon footprint of CT scans by quantifying in-hospital and out-of-hospital energy use and to assess public health impacts. The study followed a standard life cycle assessment protocol to measure energy from a CT scan then expanding to all hospital electrical energy related to CT usage. In addition, all the fuel energy used to generate electricity and to manufacture the CT consumables was measured. The study was conducted at two hospitals. The entire life cycle energy for a CT scan was 24-34 kWh of natural resource energy per scan. The actual active patient scan energy that produces the images is only about 1.6% of this total life cycle energy. This large multiplier to get total CT energy is a previously undocumented environmental response to the direct radiology order for a patient CT scan. The CT in-hospital energy related to idle periods, where the machine is on but no patients are being scanned and is 14-30-fold higher than the energy used for the CT image. The in-hospital electrical energy of a CT scan makes up only about 25% of the total energy footprint. The rest is generated outside the hospital: 54-62% for generation and transmission of the electricity, while 13-22% is for all the energy to make the consumables. Different CT scanners have some influences on the results and could help guide purchase of CT equipment. The transparent, detailed life cycle approach allows the data from this study to be used by radiologists to examine details of both direct and of unseen energy impacts of CT scans. The public health (outside-the-hospital) impact (including the patients receiving a CT) needs to be measured and included. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  16. CT and HR-CT of exogenous allergic alveolitis

    International Nuclear Information System (INIS)

    Lederer, A.; Kullnig, P.; Pongratz, M.

    1992-01-01

    The CT changes on conventional and high resolution CT in 14 patients with exogeneous allergic alveolitis (EAA) were analysed retrospectively. There were 8 patients with clinically subacute disease, 5 patients in a chronic stage and 1 patient with acute EAA. The appearances and their distribution were examined. Seven of the 8 patients in the subacute stage showed a ground glass pattern and multiple nodules of less than 2 mm. All patients in the chronic stage showed a combination of fine infiltrates, small nodules and irregular linear densities; distortion of the pulmonary pattern was present in 3 cases. The patient with acute EAA showed diffuse dense areas of consolidation in both lungs as well as multiple nodules and a ground glass pattern. The CT appearances of EAA correspond with the basic micropathology and, within the clinical context, permit diagnostic classification. (orig.) [de

  17. Treatment response evaluation with 18F-FDG PET/CT and 18F-NaF PET/CT in multiple myeloma patients undergoing high-dose chemotherapy and autologous stem cell transplantation.

    Science.gov (United States)

    Sachpekidis, Christos; Hillengass, J; Goldschmidt, H; Wagner, B; Haberkorn, U; Kopka, K; Dimitrakopoulou-Strauss, A

    2017-01-01

    The aim of this study was to assess the combined use of the radiotracers 18 F-FDG and 18 F-NaF in treatment response evaluation of a group of multiple myeloma (MM) patients undergoing high-dose chemotherapy (HDT) followed by autologous stem cell transplantation (ASCT) by means of static (whole-body) and dynamic PET/CT (dPET/CT). Thirty-four patients with primary, previously untreated MM scheduled for treatment with HDT followed by ASCT were enrolled in the study. All patients underwent PET/CT scanning with 18 F-FDG and 18 F-NaF before and after therapy. Treatment response by means of PET/CT was assessed according to the European Organization for Research and Treatment of Cancer (EORTC) 1999 criteria. The evaluation of dPET/CT studies was based on qualitative evaluation, semi-quantitative (SUV) calculation, and quantitative analysis based on two-tissue compartment modelling and a non-compartmental approach leading to the extraction of fractal dimension (FD). An analysis was possible in 29 patients: three with clinical complete response (CR) and 26 with non-CR (13 patients near complete response-nCR, four patients very good partial response-VGPR, nine patients partial response-PR). After treatment, 18 F-FDG PET/CT was negative in 14/29 patients and positive in 15/29 patients, showing a sensitivity of 57.5 % and a specificity of 100 %. According to the EORTC 1999 criteria, 18 F-FDG PET/CT-based treatment response revealed CR in 14 patients ( 18 F-FDG PET/CT CR), PR in 11 patients ( 18 F-FDG PET/CT PR) and progressive disease in four patients ( 18 F-FDG PET/CT PD). In terms of 18 F-NaF PET/CT, 4/29 patients (13.8 %) had a negative baseline scan, thus failed to depict MM. Regarding the patients for which a direct lesion-to-lesion comparison was feasible, 18 F-NaF PET/CT depicted 56 of the 129 18 F-FDG positive lesions (43 %). Follow-up 18 F-NaF PET/CT showed persistence of 81.5 % of the baseline 18 F-NaF positive MM lesions after treatment, despite the fact that 64

  18. High to ultra-high power electrical energy storage.

    Science.gov (United States)

    Sherrill, Stefanie A; Banerjee, Parag; Rubloff, Gary W; Lee, Sang Bok

    2011-12-14

    High power electrical energy storage systems are becoming critical devices for advanced energy storage technology. This is true in part due to their high rate capabilities and moderate energy densities which allow them to capture power efficiently from evanescent, renewable energy sources. High power systems include both electrochemical capacitors and electrostatic capacitors. These devices have fast charging and discharging rates, supplying energy within seconds or less. Recent research has focused on increasing power and energy density of the devices using advanced materials and novel architectural design. An increase in understanding of structure-property relationships in nanomaterials and interfaces and the ability to control nanostructures precisely has led to an immense improvement in the performance characteristics of these devices. In this review, we discuss the recent advances for both electrochemical and electrostatic capacitors as high power electrical energy storage systems, and propose directions and challenges for the future. We asses the opportunities in nanostructure-based high power electrical energy storage devices and include electrochemical and electrostatic capacitors for their potential to open the door to a new regime of power energy.

  19. Technical principles of dual source CT

    International Nuclear Information System (INIS)

    Petersilka, Martin; Bruder, Herbert; Krauss, Bernhard; Stierstorfer, Karl; Flohr, Thomas G.

    2008-01-01

    During the past years, multi-detector row CT (MDCT) has evolved into clinical practice with a rapid increase of the number of detector slices. Today's 64 slice CT systems allow whole-body examinations with sub-millimeter resolution in short scan times. As an alternative to adding even more detector slices, we describe the system concept and design of a CT scanner with two X-ray tubes and two detectors (mounted on a CT gantry with a mechanical offset of 90 deg.) that has the potential to overcome limitations of conventional MDCT systems, such as temporal resolution for cardiac imaging. A dual source CT (DSCT) scanner provides temporal resolution equivalent to a quarter of the gantry rotation time, independent of the patient's heart rate (83 ms at 0.33 s rotation time). In addition to the benefits for cardiac scanning, it allows to go beyond conventional CT imaging by obtaining dual energy information if the two tubes are operated at different voltages. Furthermore, we discuss how both acquisition systems can be used to add the power reserve of two X-ray tubes for long scan ranges and obese patients. Finally, future advances of DSCT are highlighted

  20. CT scan findings of fungal pneumonia; Diagnose der Pilzpneumonie in der Thorax-CT

    Energy Technology Data Exchange (ETDEWEB)

    Heckmann, M.; Uder, M.; Bautz, W.; Heinrich, M. [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. fuer Diagnostische Radiologie

    2008-07-01

    The importance of fungal infection of the lung in immunocompromised patients has increased substantially during the last decades. Numerically the most patients are those with neutropenia, e.g. patients with malignancies or solid organ and stem cell transplantation, chemotherapy, corticosteroid use and HIV infection. Although fungal infections can occur in immunocompetent patients, their frequency in this population is rare. The clinical symptoms such as fever accompanied with non-productive cough are unspecific. In some patients progression to hypoxemia and dyspnea may occur rapidly. In spite of improved antifungal therapy morbidity and mortality of these infections are still high. Therefore an early and non-invasive diagnosis is very important. That is why CT and even better High-Resolution-CT (HR-CT) is a very important modality in examining immunocompromised patients with a probability of fungal infection. CT is everywhere available and, as a non-invasive method, able to give the relevant diagnose efficiently. This paper should give an overview about the radiologic findings and possible differential diagnosis of diverse pulmonary fungal infections in CT. Pneumonias caused by Aspergillus, Cryptococcus, Candida, Histoplasma, Mucor and Geotrichum capitatum are illustrated. (orig.)

  1. SU-E-I-98: Dose Comparison for Pulmonary Embolism CT Studies: Single Energy Vs. Dual Energy

    International Nuclear Information System (INIS)

    Mahmood, U; Erdi, Y

    2014-01-01

    Purpose: The purpose of this study was to assess and compare the size specific dose estimate (SSDE), dose length product (DLP) and noise relationship for pulmonary embolism studies evaluated by single source dual energy computed tomography (DECT) against conventional CT (CCT) studies in a busy cancer center and to determine the dose savings provided by DECT. Methods: An IRB-approved retrospective study was performed to determine the CTDIvol and DLP from a subset of patients scanned with both DECT and CCT over the past five years. We were able to identify 30 breast cancer patients (6 male, 24 female, age range 24 to 81) who had both DECT and CCT studies performed. DECT scans were performed with a GE HD 750 scanner (140/80 kVp, 480 mAs and 40 mm) and CCT scans were performed with a GE Lightspeed 16 slice scanner (120 kVp, 352 mAs, 20 mm). Image noise was measured by placing an ROI and recording the standard deviation of the mean HU along the descending aorta. Results: The average DECT patient size specific dose estimate was to be 14.2 ± 1.7 mGy as compared to 22.4 ± 2.7 mGy from CCT PE studies, which is a 37% reduction in the SSDE. The average DECT DLP was 721.8 ± 84.6 mGy-cm as compared to 981.8 ± 106.1 mGy-cm for CCT, which is a 26% decrease. Compared to CCT the image noise was found to decrease by 19% when using DECT for PE studies. Conclusion: DECT SSDE and DLP measurements indicate dose savings and image noise reduction when compared to CCT. In an environment that heavily debates CT patient doses, this study confirms the effectiveness of DECT in PE imaging

  2. Radiation exposure during CT-guided biopsies: recent CT machines provide markedly lower doses.

    Science.gov (United States)

    Guberina, Nika; Forsting, Michael; Ringelstein, Adrian; Suntharalingam, Saravanabavaan; Nassenstein, Kai; Theysohn, Jens; Wetter, Axel

    2018-03-28

    To examine radiation dose levels of CT-guided interventional procedures of chest, abdomen, spine and extremities on different CT-scanner generations at a large multicentre institute. 1,219 CT-guided interventional biopsies of different organ regions ((A) abdomen (n=516), (B) chest (n=528), (C) spine (n=134) and (D) extremities (n=41)) on different CT-scanners ((I) SOMATOM-Definition-AS+, (II) Volume-Zoom, (III) Emotion6) were included from 2013-2016. Important CT-parameters and standard dose-descriptors were retrospectively examined. Additionally, effective dose and organ doses were calculated using Monte-Carlo simulation, following ICRP103. Overall, radiation doses for CT interventions are highly dependent on CT-scanner generation: the newer the CT scanner, the lower the radiation dose imparted to patients. Mean effective doses for each of four procedures on available scanners are: (A) (I) 9.3mSv versus (II) 13.9mSv (B) (I) 7.3mSv versus (III) 11.4mSv (C) (I) 6.3mSv versus (II) 7.4mSv (D) (I) 4.3mSv versus (II) 10.8mSv. Standard dose descriptors [standard deviation (SD); CT dose index vol (CTDI vol ); dose-length product (DLP body ); size-specific dose estimate (SSDE)] were also compared. Effective dose, organ doses and SSDE for various CT-guided interventional biopsies on different CT-scanner generations following recommendations of the ICRP103 are provided. New CT-scanner generations involve markedly lower radiation doses versus older devices. • Effective dose, organ dose and SSDE are provided for CT-guided interventional examinations. • These data allow identifying organs at risk of higher radiation dose. • Detailed knowledge of radiation dose may contribute to a better individual risk-stratification. • New CT-scanner generations involve markedly lower radiation doses compared to older devices.

  3. High-energy detector

    Science.gov (United States)

    Bolotnikov, Aleksey E [South Setauket, NY; Camarda, Giuseppe [Farmingville, NY; Cui, Yonggang [Upton, NY; James, Ralph B [Ridge, NY

    2011-11-22

    The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

  4. A dual energy CT study on vascular effects of gold nanoparticles in radiation therapy

    Science.gov (United States)

    Ashton, Jeffrey R.; Hoye, Jocelyn; Deland, Katherine; Whitley, Melodi; Qi, Yi; Moding, Everett; Kirsch, David G.; West, Jennifer; Badea, Cristian T.

    2016-03-01

    Gold nanoparticles (AuNPs) are emerging as promising agents for both cancer therapy and CT imaging. AuNPs are delivered to tumors via the enhanced permeability and retention effect and they preferentially accumulate in close proximity to the tumor blood vessels. AuNPs produce low-energy, short-range photoelectrons during external beam radiation therapy (RT), boosting dose. This work is focused on understanding how tumor vascular permeability is influenced by AuNP-augmented radiation therapy (RT), and how this knowledge can potentially improve the delivery of additional nanoparticle-based chemotherapeutics. We use dual energy (DE) CT to detect accumulation of AuNPs and increased vascular permeability to liposomal iodine (i.e. a surrogate for chemotherapeutics with liposome encapsulation) following RT. We used sarcoma tumors generated in LSL-KrasG12D; p53FL/FL conditional mutant mice. A total of n=37 mice were used in this study. The treated mice were injected with 20 mg AuNP (0.1 ml/25 g mouse) 24 hours before delivery of 5 Gy RT (n=5), 10 Gy RT (n=3) or 20 Gy RT (n=6). The control mice received no AuNP injection and either no RT (n=6), 5 Gy RT (n=3), 10 Gy RT (n=3), 20 Gy RT (n=11). Twenty four hours post-RT, the mice were injected with liposomal iodine (0.3 ml/25 mouse) and imaged with DE-CT three days later. The results suggest that independent of any AuNP usage, RT levels of 10 Gy and 20 Gy increase the permeability of tumor vasculature to liposomal iodine and that the increase in permeability is dose-dependent. We found that the effect of RT on vasculature may already be at its maximum response i.e. saturated at 20 Gy, and therefore the addition of AuNPs had almost no added benefit. Similarly, at 5 Gy RT, our data suggests that there was no effect of AuNP augmentation on tumor vascular permeability. However, by using AuNPs with 10 Gy RT, we observed an increase in the vascular permeability, however this is not yet statistically significant due to the small

  5. Diagnostic test accuracy study of 18F-sodium fluoride PET/CT, 99mTc-labelled diphosphonate SPECT/CT, and planar bone scintigraphy for diagnosis of bone metastases in newly diagnosed, high-risk prostate cancer

    DEFF Research Database (Denmark)

    Fonager, Randi F; Zacho, Helle D; Langkilde, Niels C

    2017-01-01

    The aim of this study was to prospectively compare planar, bone scan (BS) versus SPECT/CT and NaF PET/CT in detecting bone metastases in prostate cancer. Thirty-seven consecutive, newly diagnosed, prostate cancer patients with prostate specific antigen (PSA) levels ≥ 50 ng/mL and who were...... considered eligible for androgen-deprivation therapy (ADT) were included in this study. BS, SPECT/CT, and NaF PET/CT, were performed prior to treatment and were repeated after six months of ADT. Baseline images from each index test were independently read by two experienced readers. The reference standard......%, and 96%, respectively, and the negative predictive values were 60%, 77% and 75%, respectively. No statistically significant difference among the three imaging modalities was observed. All three imaging modalities showed high sensitivity and specificity. NaF PET/CT and SPECT/CT showed numerically improved...

  6. Energy Systems High-Pressure Test Laboratory | Energy Systems Integration

    Science.gov (United States)

    Facility | NREL Energy Systems High-Pressure Test Laboratory Energy Systems High-Pressure Test Laboratory In the Energy Systems Integration Facility's High-Pressure Test Laboratory, researchers can safely test high-pressure hydrogen components. Photo of researchers running an experiment with a hydrogen fuel

  7. Normal CT anatomy of the spine

    International Nuclear Information System (INIS)

    Quiroga, O.; Matozzi, F.; Beranger, M.; Nazarian, S.; Salamon, G.; Gambarelli, J.

    1982-01-01

    To analyse the anatomo-radiological correlation of the spine and spinal cord, 22 formalized, frozen anatomical specimens corresponding to different regions of the spinal column (8 cervical, 5 dorsal, and 9 lumbar) were studied by CT scans on axial, sagittal and coronal planes and by contact radiography after they were cut into anatomical slices in order to clarify the normal CT anatomy of the spinal column. The results obtained from CT patient scans, performed exclusively on the axial plane, were compared with those obtained from the anatomical specimens (both CT and contrast radiography). High resolution CT programs were used, enabling us to obtain better individualization of the normal structures contained in the spinal column. Direct sagittal and coronal sections were performed on the specimens in order to get further anatomo-radiological information. Enhanced CT studies of the specimens were also available because of the air already present in the subarachnoid spaces. Excellent visualization was obtained of bone structures, soft tissue and the spinal cord. High CT resolution of the spine appeares to be an excellent neuroradiological procedure to study the spine and spinal cord. A metrizamide CT scan is, however, necessary when a normal unenhanced CT scan is insufficient for diagnosis and when the spinal cord is not clearly visible, as often happens at the cervical level. Clinical findings are certainly very useful to ascertain the exact CT level and to limit the radiation exposure. (orig.)

  8. CT of splenic trauma

    International Nuclear Information System (INIS)

    Griffiths, B.G.; Federle, M.P.; Minagi, H.; Jeffrey, R.B.

    1986-01-01

    Fifty-five consecutive cases of surgically proved splenic injuries were evaluated by CT. CT correctly identified 54 splenic injuries, with one false-negative and three false-positive studies. In the single false-negative study and in two of the three false-positive studies, CT correctly indicated the presence of a large hemoperitoneum and other abdominal visceral lacerations and so correctly indicated the need for surgery. Of the 55 proved cases of splenic injury, CT revealed hemoperitoneum in 54 (99%), perisplenic clot in 47 (85%), splenic laceration in 39 (71%), and subcapsular hematoma in 13 (24%). Perisplenic clot can be distinguished from lysed blood in the peritoneal cavity and is a sensitive and specific sign of splenic trauma, even in the absence of visible splenic laceration. The authors conclude that CT is highly reliable means of evaluating splenic trauma

  9. Development of ''Eminence STARGATE'' PET/CT system

    International Nuclear Information System (INIS)

    Okazaki, Masato; Inoue, Yoshihiro; Amano, Masaharu

    2009-01-01

    A PET/CT system, the combination of a PET (Positron Emission Tomography) system with an X-ray CT system, has been widely used in recent years. Our newly developed ''Eminence STARGATE'' PET/CT system allows the PET gantry and the X-ray CT gantry to move independently. This advantage provides high flexibility for PET examination and X-ray CT examination and also eases a patient's psychological anxiety about closed spaces. The system has a 16-slice X-ray CT scanner. (author)

  10. Preoperative 4D CT Localization of Nonlocalizing Parathyroid Adenomas by Ultrasound and SPECT-CT.

    Science.gov (United States)

    Hinson, Andrew M; Lee, David R; Hobbs, Bradley A; Fitzgerald, Ryan T; Bodenner, Donald L; Stack, Brendan C

    2015-11-01

    To evaluate 4-dimensional (4D) computed tomography (CT) for the localization of parathyroid adenomas previously considered nonlocalizing on ultrasound and single-photon emission CT with CT scanning (SPECT-CT). To measure radiation exposure associated with 4D-CT and compared it with SPECT-CT. Case series with chart review. University tertiary hospital. Nineteen adults with primary hyperparathyroidism who underwent preoperative 4D CT from November 2013 through July 2014 after nonlocalizing preoperative ultrasound and technetium-99m SPECT-CT scans. Sensitivity, specificity, predictive values, and accuracy of 4D CT were evaluated. Nineteen patients (16 women and 3 men) were included with a mean age of 66 years (range, 39-80 years). Mean preoperative parathyroid hormone level was 108.5 pg/mL (range, 59.3-220.9 pg/mL), and mean weight of the excised gland was 350 mg (range, 83-797 mg). 4D CT sensitivity and specificity for localization to the patient's correct side of the neck were 84.2% and 81.8%, respectively; accuracy was 82.9%. The sensitivity for localizing adenomas to the correct quadrant was 76.5% and 91.5%, respectively; accuracy was 88.2%. 4D CT radiation exposure was significantly less than the radiation associated with SPECT-CT (13.8 vs 18.4 mSv, P = 0.04). 4D CT localizes parathyroid adenomas with relatively high sensitivity and specificity and allows for the localization of some adenomas not observed on other sestamibi-based scans. 4D CT was also associated with less radiation exposure when compared with SPECT-CT based on our study protocol. 4D CT may be considered as first- or second-line imaging for localizing parathyroid adenomas in the setting of primary hyperparathyroidism. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

  11. Spiral CT for evaluation of chest trauma; Spiral-CT beim Thoraxtrauma

    Energy Technology Data Exchange (ETDEWEB)

    Roehnert, W. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik; Weise, R. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik

    1997-07-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [Deutsch] Nach Einfuehrung der Spiral-CT in unserer Einrichtung versuchten wir, den Stellenwert der Computertomographie in der Notfalldiagnostik des Thoraxtraumas neu zu bestimmen. Dazu wurden retrospektiv ueber einen Zeitraum von 10 Monaten alle mittels Spiral-CT untersuchten Notfallpatienten mit Thoraxverletzungen ausgewertet. Im Vordergrund standen folgende Befunde unterschiedlichen Schweregrades: Pneumothorax, Haematothorax, Lungenkontusion/-lazeration, Mediastinalhaematom, Gefaessruptur, Herz- und Herzbeutelverletzung. Auf die unterschiedlichen Frakturen wird bewusst nicht naeher eingegangen. In vielen Faellen liefert die Spiral-CT mit relativ geringem Zeitaufwand wesentliche diagnostische Aussagen. Haeufig kann auf eine Angiographie verzichtet werden. Ein starres diagnostisches Stufenschema laesst sich nicht definieren. Die Thoraxuebersichtsaufnahme besitzt einen unveraendert hohen Stellenwert. (orig.)

  12. Postoperative CT in pancreas transplantation

    International Nuclear Information System (INIS)

    Powell, F.E.; Harper, S.J.F.; Callaghan, C.J.; Shaw, A.; Godfrey, E.M.; Bradley, J.A.; Watson, C.J.E.; Pettigrew, G.J.

    2015-01-01

    Aim: To examine the usage and value of computed tomography (CT) following simultaneous pancreas and kidney (SPK) transplantation. Materials and methods: Indications for postoperative CT, key findings, and their influence on management were determined by retrospective analysis. Results: Ninety-eight patients underwent 313 CT examinations. Common indications for the examinations included suspected intra-abdominal collection (31.1%) and elevated serum amylase/lipase (24.1%). CT findings most frequently showed non-specific mild inflammation (27.6%), a normal scan (17.1%) and fluid collections (16.3%). High capillary blood glucose (CBG) was associated with resultant CT demonstration of graft vascular abnormalities, but otherwise, particular clinical indications were not associated with specific CT findings. Conclusion: Clinical findings in patients with SPK transplants are non-specific. The pattern of abnormalities encountered is significantly different to those seen in native pancreatic disease and demands a tailored protocol. CT enables accurate depiction of vascular abnormalities and fluid collections, thus reducing the number of surgical interventions that might otherwise be required. Elevated CBG should prompt urgent CT to exclude potentially reversible vascular complications. - Highlights: • The value of CT following simultaneous pancreas and kidney transplantation was assessed. • 313 CT scans were performed on 98 patients between January 2005 and August 2010. • Elevated blood glucose was associated with CT findings of graft vascular anomalities. • CT was particularly useful in directing operative versus non-operative intervention.

  13. Comprehensive Assessment of Osteoporosis and Bone Fragility with CT Colonography

    Science.gov (United States)

    Murthy, Naveen S.; Khosla, Sundeep; Clarke, Bart L.; Bruining, David H.; Kopperdahl, David L.; Lee, David C.; Keaveny, Tony M.

    2016-01-01

    Purpose To evaluate the ability of additional analysis of computed tomographic (CT) colonography images to provide a comprehensive osteoporosis assessment. Materials and Methods This Health Insurance Portability and Accountability Act–compliant study was approved by our institutional review board with a waiver of informed consent. Diagnosis of osteoporosis and assessment of fracture risk were compared between biomechanical CT analysis and dual-energy x-ray absorptiometry (DXA) in 136 women (age range, 43–92 years), each of whom underwent CT colonography and DXA within a 6-month period (between January 2008 and April 2010). Blinded to the DXA data, biomechanical CT analysis was retrospectively applied to CT images by using phantomless calibration and finite element analysis to measure bone mineral density and bone strength at the hip and spine. Regression, Bland-Altman, and reclassification analyses and paired t tests were used to compare results. Results For bone mineral density T scores at the femoral neck, biomechanical CT analysis was highly correlated (R2 = 0.84) with DXA, did not differ from DXA (P = .15, paired t test), and was able to identify osteoporosis (as defined by DXA), with 100% sensitivity in eight of eight patients (95% confidence interval [CI]: 67.6%, 100%) and 98.4% specificity in 126 of 128 patients (95% CI: 94.5%, 99.6%). Considering both the hip and spine, the classification of patients at high risk for fracture by biomechanical CT analysis—those with osteoporosis or “fragile bone strength”—agreed well against classifications for clinical osteoporosis by DXA (T score ≤−2.5 at the hip or spine), with 82.8% sensitivity in 24 of 29 patients (95% CI: 65.4%, 92.4%) and 85.7% specificity in 66 of 77 patients (95% CI: 76.2%, 91.8%). Conclusion Retrospective biomechanical CT analysis of CT colonography for colorectal cancer screening provides a comprehensive osteoporosis assessment without requiring changes in imaging protocols.

  14. Multi-phase simultaneous segmentation of tumor in lung 4D-CT data with context information.

    Directory of Open Access Journals (Sweden)

    Zhengwen Shen

    Full Text Available Lung 4D computed tomography (4D-CT plays an important role in high-precision radiotherapy because it characterizes respiratory motion, which is crucial for accurate target definition. However, the manual segmentation of a lung tumor is a heavy workload for doctors because of the large number of lung 4D-CT data slices. Meanwhile, tumor segmentation is still a notoriously challenging problem in computer-aided diagnosis. In this paper, we propose a new method based on an improved graph cut algorithm with context information constraint to find a convenient and robust approach of lung 4D-CT tumor segmentation. We combine all phases of the lung 4D-CT into a global graph, and construct a global energy function accordingly. The sub-graph is first constructed for each phase. A context cost term is enforced to achieve segmentation results in every phase by adding a context constraint between neighboring phases. A global energy function is finally constructed by combining all cost terms. The optimization is achieved by solving a max-flow/min-cut problem, which leads to simultaneous and robust segmentation of the tumor in all the lung 4D-CT phases. The effectiveness of our approach is validated through experiments on 10 different lung 4D-CT cases. The comparison with the graph cut without context constraint, the level set method and the graph cut with star shape prior demonstrates that the proposed method obtains more accurate and robust segmentation results.

  15. Very high energy colliders

    International Nuclear Information System (INIS)

    Richter, B.

    1986-03-01

    The luminosity and energy requirements are considered for both proton colliders and electron-positron colliders. Some of the basic design equations for high energy linear electron colliders are summarized, as well as design constraints. A few examples are given of parameters for very high energy machines. 4 refs., 6 figs

  16. SU-D-BRA-06: Dual-Energy Chest CT: The Effects of Virtual Monochromatic Reconstructions On Texture Analysis Features

    International Nuclear Information System (INIS)

    Sorensen, J; Duran, C; Stingo, F; Wei, W; Rao, A; Zhang, L; Court, L; Erasmus, J; Godoy, M

    2015-01-01

    Purpose: To characterize the effect of virtual monochromatic reconstructions on several commonly used texture analysis features in DECT of the chest. Further, to assess the effect of monochromatic energy levels on the ability of these textural features to identify tissue types. Methods: 20 consecutive patients underwent chest CTs for evaluation of lung nodules using Siemens Somatom Definition Flash DECT. Virtual monochromatic images were constructed at 10keV intervals from 40–190keV. For each patient, an ROI delineated the lesion under investigation, and cylindrical ROI’s were placed within 5 different healthy tissues (blood, fat, muscle, lung, and liver). Several histogram- and Grey Level Cooccurrence Matrix (GLCM)-based texture features were then evaluated in each ROI at each energy level. As a means of validation, these feature values were then used in a random forest classifier to attempt to identify the tissue types present within each ROI. Their predictive accuracy at each energy level was recorded. Results: All textural features changed considerably with virtual monochromatic energy, particularly below 70keV. Most features exhibited a global minimum or maximum around 80keV, and while feature values changed with energy above this, patient ranking was generally unaffected. As expected, blood demonstrated the lowest inter-patient variability, for all features, while lung lesions (encompassing many different pathologies) exhibited the highest. The accuracy of these features in identifying tissues (76% accuracy) was highest at 80keV, but no clear relationship between energy and classification accuracy was found. Two common misclassifications (blood vs liver and muscle vs fat) accounted for the majority (24 of the 28) errors observed. Conclusion: All textural features were highly dependent on virtual monochromatic energy level, especially below 80keV, and were more stable above this energy. However, in a random forest model, these commonly used features were

  17. SU-D-BRA-06: Dual-Energy Chest CT: The Effects of Virtual Monochromatic Reconstructions On Texture Analysis Features

    Energy Technology Data Exchange (ETDEWEB)

    Sorensen, J; Duran, C; Stingo, F; Wei, W; Rao, A; Zhang, L; Court, L; Erasmus, J; Godoy, M [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: To characterize the effect of virtual monochromatic reconstructions on several commonly used texture analysis features in DECT of the chest. Further, to assess the effect of monochromatic energy levels on the ability of these textural features to identify tissue types. Methods: 20 consecutive patients underwent chest CTs for evaluation of lung nodules using Siemens Somatom Definition Flash DECT. Virtual monochromatic images were constructed at 10keV intervals from 40–190keV. For each patient, an ROI delineated the lesion under investigation, and cylindrical ROI’s were placed within 5 different healthy tissues (blood, fat, muscle, lung, and liver). Several histogram- and Grey Level Cooccurrence Matrix (GLCM)-based texture features were then evaluated in each ROI at each energy level. As a means of validation, these feature values were then used in a random forest classifier to attempt to identify the tissue types present within each ROI. Their predictive accuracy at each energy level was recorded. Results: All textural features changed considerably with virtual monochromatic energy, particularly below 70keV. Most features exhibited a global minimum or maximum around 80keV, and while feature values changed with energy above this, patient ranking was generally unaffected. As expected, blood demonstrated the lowest inter-patient variability, for all features, while lung lesions (encompassing many different pathologies) exhibited the highest. The accuracy of these features in identifying tissues (76% accuracy) was highest at 80keV, but no clear relationship between energy and classification accuracy was found. Two common misclassifications (blood vs liver and muscle vs fat) accounted for the majority (24 of the 28) errors observed. Conclusion: All textural features were highly dependent on virtual monochromatic energy level, especially below 80keV, and were more stable above this energy. However, in a random forest model, these commonly used features were

  18. Dual-energy MDCT: Comparison of pulmonary artery enhancement on dedicated CT pulmonary angiography, routine and low contrast volume studies

    Energy Technology Data Exchange (ETDEWEB)

    Godoy, Myrna C.B., E-mail: migbarco@gmail.com [New York University Langone Medical Center, Department of Radiology, New York, NY (United States); University of Texas M.D. Anderson Cancer Center, Department of Diagnostic Radiology, Houston, TX (United States); Heller, Samantha L.; Naidich, David P.; Assadourian, Bernard [New York University Langone Medical Center, Department of Radiology, New York, NY (United States); Leidecker, Christianne [Siemens Medical Solutions, Malvern, PA (United States); Schmidt, Bernhard [Siemens Healthcare, Forchheim (Germany); Vlahos, Ioannis [New York University Langone Medical Center, Department of Radiology, New York, NY (United States); St. George' s Hospital NHS Trust, London (United Kingdom)

    2011-08-15

    Purpose: The aim of this study was (a) to compare arterial enhancement in simultaneously acquired high- and low-kilovoltage images; and (b) to determine whether low tube-voltage imaging would permit PE evaluation on routine chest CT studies or CTPA studies performed with a low volume of contrast media. Materials and methods: We compared 20 CTPA studies (CTPA group), 20 routine thoracic CT studies (RT group) and 10 CTPA studies performed with reduced volume of contrast media (RC group). HU values were measured in all groups at 80 kVp and 140 kVp images in multiple pulmonary arterial segments bilaterally. The diagnostic quality of the central and peripheral vascular enhancement and the image noise were evaluated at both energies using a five-point scale. Results: For all patients, the mean CT attenuation values were greater at 80 kVp than 140 kVp images (p < 0.001). At 80 kVp, CTPA group attenuation values were greater than RT group (p = 0.03) with a similar trend at 140 kVp (p = 0.08). At both 140 kVp and 80 kVp, CTPA group attenuation values were greater than RC group (p = 0.02 and p = 0.03, respectively). Qualitative analysis showed that at 140 kVp CTPA studies had better global image quality scores than RT (p = 0.003) and RC (p = 0.001) groups. However, at 80 kVp, there was no significant difference of global image quality between CTPA and the other groups (p = 0.4 and p = 0.5, respectively). Although measurable image noise was greater at 80 kVp than 140 kVp (p < 0.001), qualitative analysis revealed lower image noise at 80 kVp images. Conclusion: DECT at 80 kVp increases arterial enhancement in both CTPA and routine studies. For routine studies this results in central and peripheral enhancement quality equivalent to that of CTPA studies. Low tube-voltage imaging allows marked contrast volume reduction for CTPA. In selected cases, satisfactory lower radiation dose CT might be achievable using lower kVp imaging alone.

  19. TH-C-18A-02: Machine Learning and STAPLE Based Simultaneous Longitudinal Segmentation of Bone and Marrow Structures From Dual Energy CT

    International Nuclear Information System (INIS)

    Fehr, D; Schmidtlein, C; Hwang, S; Deasy, J; Veeraraghavan, H

    2014-01-01

    Purpose: To develop a fully-automatic longitudinal bone and marrow segmentation method in the pelvic region from dual energy computed tomography (DECT). Methods: We developed a two-step automatic bone and marrow segmentation method for simultaneous longitudinal evaluation of patients with metastatic bone disease using dual energy CT (DECT). Our approach transforms the DECT images into a multi-material decomposition (MMD) model that represents the voxels as a mixture of multiple materials. A support vector machine (SVM) was trained using a single scan. In the first step of the longitudinal segmentation the trained SVM model detects bone and marrow structures on all available longitudinal scans. Segmentation is further refined through active contour segmentation. In the second step, the segmentations from the individual scans are merged by employing the simultaneous truth and performance level estimation (STAPLE) algorithm. The scans are registered using affine and deformable registration. We found that our approach improves the segmentation in all the scans under reliable registration performance between the same scans. Improving registration was not under the scope of this work. Results: We applied our approach to segment bone and marrow in DECT scans in the pelvic regions for multiple patients. Each patient had three to five follow up scans. All the patients in the analysis had artificial metal prostheses which introduced challenges for the registration. Our algorithm achieved reasonable accurate segmentation despite the presence of metal artifacts and high-density oral contrast in neighboring structures. Our approach obtained an overall segmentation accuracy of 80% using DICE metric. Conclusion: We developed a two-step automatic longitudinal segmentation technique for bone and marrow region structures in the pelvic areas from dual energy CT. Our approach achieves robust segmentation despite the presence of confounding structures with similar intensities as the

  20. Optimization of Proton CT Detector System and Image Reconstruction Algorithm for On-Line Proton Therapy.

    Directory of Open Access Journals (Sweden)

    Chae Young Lee

    Full Text Available The purposes of this study were to optimize a proton computed tomography system (pCT for proton range verification and to confirm the pCT image reconstruction algorithm based on projection images generated with optimized parameters. For this purpose, we developed a new pCT scanner using the Geometry and Tracking (GEANT 4.9.6 simulation toolkit. GEANT4 simulations were performed to optimize the geometric parameters representing the detector thickness and the distance between the detectors for pCT. The system consisted of four silicon strip detectors for particle tracking and a calorimeter to measure the residual energies of the individual protons. The optimized pCT system design was then adjusted to ensure that the solution to a CS-based convex optimization problem would converge to yield the desired pCT images after a reasonable number of iterative corrections. In particular, we used a total variation-based formulation that has been useful in exploiting prior knowledge about the minimal variations of proton attenuation characteristics in the human body. Examinations performed using our CS algorithm showed that high-quality pCT images could be reconstructed using sets of 72 projections within 20 iterations and without any streaks or noise, which can be caused by under-sampling and proton starvation. Moreover, the images yielded by this CS algorithm were found to be of higher quality than those obtained using other reconstruction algorithms. The optimized pCT scanner system demonstrated the potential to perform high-quality pCT during on-line image-guided proton therapy, without increasing the imaging dose, by applying our CS based proton CT reconstruction algorithm. Further, we make our optimized detector system and CS-based proton CT reconstruction algorithm potentially useful in on-line proton therapy.