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.)

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...

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.

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.

PET/CT and contrast enhanced CT in single vs. two separate sessions: a cost analysis study.

Science.gov (United States)

Picchio, M; Mansueto, M; Crivellaro, C; Guerra, L; Marcelli, S; Arosio, M; Sironi, S; Gianolli, L; Grimaldi, A; Messa, C

2012-06-01

Aim of the study was to quantify the economic impact of PET/CT and contrast enhanced (c.e.) CT performed in a single session examination vs. stand-alone modalities in oncological patients. One-hundred-forty-five cancer patients referred to both PET/CT and c.e. CT, to either stage (N.=46) or re-stage (N.=99) the disease, were included. Seventy-two/145 performed both studies in a single session (innovative method) and 73/145 in two different sessions (traditional method). The cost-minimization analysis was performed by evaluating: 1) institutional costs, data obtained by hospital accountability (staff, medical materials, equipment maintenance and depreciation, departments utilities); 2) patients costs, data obtained by a specific survey provided to patients (travel, food, accommodation costs, productivity loss). Economic data analysis showed that the costs for innovative method was lower than those of traditional method, both for Institution (106 € less per test) and for patient (21 € less per patient). The loss of productivity for patient and caregivers resulted lower for the innovative method than the traditional method (3 work-hour less per person). PET/CT and c.e. CT performed in a single session is more cost-effective than stand-alone modalities, by reducing both Institutional and patients costs. These advantages are mainly due to lower Institutional cost (single procedure) and to lower cost related to travel and housing.

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.)

Source position error influence on industry CT image quality

International Nuclear Information System (INIS)

Cong Peng; Li Zhipeng; Wu Haifeng

2004-01-01

Based on the emulational exercise, the influence of source position error on industry CT (ICT) image quality was studied and the valuable parameters were obtained for the design of ICT. The vivid container CT image was also acquired from the CT testing system. (authors)

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

Acute gastrointestinal bleeding: detection of source and etiology with multi-detector-row CT

Energy Technology Data Exchange (ETDEWEB)

Scheffel, Hans; Pfammatter, Thomas; Marincek, Borut; Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic Radiology, Zurich (Switzerland); Wildi, Stefan [University Hospital Zurich, Department of Visceral and Transplant Surgery, Zurich (Switzerland); Bauerfeind, Peter [University Hospital Zurich, Division of Gastroenterology, Zurich (Switzerland)

2007-06-15

This study was conducted to determine the ability of multi-detector-row computed tomography (CT) to identify the source and etiology of acute gastrointestinal bleeding. Eighteen patients with acute upper (n = 10) and lower (n = 8) gastrointestinal bleeding underwent 4-detector-row CT (n = 6), 16-detector-row CT (n = 11), and 64-slice CT (n = 1) with an arterial and portal venous phase of contrast enhancement. Unenhanced scans were performed in nine patients. CT scans were reviewed to determine conspicuity of bleeding source, underlying etiology, and for potential causes of false-negative prospective interpretations. Bleeding sources were prospectively identified with CT in 15 (83%) patients, and three (17%) bleeding sources were visualized in retrospect, allowing the characterization of all sources of bleeding with CT. Contrast extravasation was demonstrated with CT in all 11 patients with severe bleeding, but only in 1 of 7 patients with mild bleeding. The etiology could not be identified on unenhanced CT scans in any patient, whereas arterial-phase and portal venous-phase CT depicted etiology in 15 (83%) patients. Underlying etiology was correctly identified in all eight patients with mild GI bleeding. Multi-detector-row CT enables the identification of bleeding source and precise etiology in patients with acute gastrointestinal bleeding. (orig.)

Acute gastrointestinal bleeding: detection of source and etiology with multi-detector-row CT

International Nuclear Information System (INIS)

Scheffel, Hans; Pfammatter, Thomas; Marincek, Borut; Alkadhi, Hatem; Wildi, Stefan; Bauerfeind, Peter

2007-01-01

This study was conducted to determine the ability of multi-detector-row computed tomography (CT) to identify the source and etiology of acute gastrointestinal bleeding. Eighteen patients with acute upper (n = 10) and lower (n = 8) gastrointestinal bleeding underwent 4-detector-row CT (n = 6), 16-detector-row CT (n = 11), and 64-slice CT (n = 1) with an arterial and portal venous phase of contrast enhancement. Unenhanced scans were performed in nine patients. CT scans were reviewed to determine conspicuity of bleeding source, underlying etiology, and for potential causes of false-negative prospective interpretations. Bleeding sources were prospectively identified with CT in 15 (83%) patients, and three (17%) bleeding sources were visualized in retrospect, allowing the characterization of all sources of bleeding with CT. Contrast extravasation was demonstrated with CT in all 11 patients with severe bleeding, but only in 1 of 7 patients with mild bleeding. The etiology could not be identified on unenhanced CT scans in any patient, whereas arterial-phase and portal venous-phase CT depicted etiology in 15 (83%) patients. Underlying etiology was correctly identified in all eight patients with mild GI bleeding. Multi-detector-row CT enables the identification of bleeding source and precise etiology in patients with acute gastrointestinal bleeding. (orig.)

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.)

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

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.

Multisource inverse-geometry CT. Part II. X-ray source design and prototype

Energy Technology Data Exchange (ETDEWEB)

Neculaes, V. Bogdan, E-mail: neculaes@ge.com; Caiafa, Antonio; Cao, Yang; De Man, Bruno; Edic, Peter M.; Frutschy, Kristopher; Gunturi, Satish; Inzinna, Lou; Reynolds, Joseph; Vermilyea, Mark; Wagner, David; Zhang, Xi; Zou, Yun [GE Global Research, Niskayuna, New York 12309 (United States); Pelc, Norbert J. [Department of Radiology, Stanford University, Stanford, California 94305 (United States); Lounsberry, Brian [Healthcare Science Technology, GE Healthcare, West Milwaukee, Wisconsin 53219 (United States)

2016-08-15

Purpose: This paper summarizes the development of a high-power distributed x-ray source, or “multisource,” designed for inverse-geometry computed tomography (CT) applications [see B. De Man et al., “Multisource inverse-geometry CT. Part I. System concept and development,” Med. Phys. 43, 4607–4616 (2016)]. The paper presents the evolution of the source architecture, component design (anode, emitter, beam optics, control electronics, high voltage insulator), and experimental validation. Methods: Dispenser cathode emitters were chosen as electron sources. A modular design was adopted, with eight electron emitters (two rows of four emitters) per module, wherein tungsten targets were brazed onto copper anode blocks—one anode block per module. A specialized ceramic connector provided high voltage standoff capability and cooling oil flow to the anode. A matrix topology and low-noise electronic controls provided switching of the emitters. Results: Four modules (32 x-ray sources in two rows of 16) have been successfully integrated into a single vacuum vessel and operated on an inverse-geometry computed tomography system. Dispenser cathodes provided high beam current (>1000 mA) in pulse mode, and the electrostatic lenses focused the current beam to a small optical focal spot size (0.5 × 1.4 mm). Controlled emitter grid voltage allowed the beam current to be varied for each source, providing the ability to modulate beam current across the fan of the x-ray beam, denoted as a virtual bowtie filter. The custom designed controls achieved x-ray source switching in <1 μs. The cathode-grounded source was operated successfully up to 120 kV. Conclusions: A high-power, distributed x-ray source for inverse-geometry CT applications was successfully designed, fabricated, and operated. Future embodiments may increase the number of spots and utilize fast read out detectors to increase the x-ray flux magnitude further, while still staying within the stationary target inherent

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.

Single-photon sources

International Nuclear Information System (INIS)

Lounis, Brahim; Orrit, Michel

2005-01-01

The concept of the photon, central to Einstein's explanation of the photoelectric effect, is exactly 100 years old. Yet, while photons have been detected individually for more than 50 years, devices producing individual photons on demand have only appeared in the last few years. New concepts for single-photon sources, or 'photon guns', have originated from recent progress in the optical detection, characterization and manipulation of single quantum objects. Single emitters usually deliver photons one at a time. This so-called antibunching of emitted photons can arise from various mechanisms, but ensures that the probability of obtaining two or more photons at the same time remains negligible. We briefly recall basic concepts in quantum optics and discuss potential applications of single-photon states to optical processing of quantum information: cryptography, computing and communication. A photon gun's properties are significantly improved by coupling it to a resonant cavity mode, either in the Purcell or strong-coupling regimes. We briefly recall early production of single photons with atomic beams, and the operation principles of macroscopic parametric sources, which are used in an overwhelming majority of quantum-optical experiments. We then review the photophysical and spectroscopic properties and compare the advantages and weaknesses of various single nanometre-scale objects used as single-photon sources: atoms or ions in the gas phase and, in condensed matter, organic molecules, defect centres, semiconductor nanocrystals and heterostructures. As new generations of sources are developed, coupling to cavities and nano-fabrication techniques lead to improved characteristics, delivery rates and spectral ranges. Judging from the brisk pace of recent progress, we expect single photons to soon proceed from demonstrations to applications and to bring with them the first practical uses of quantum information

Open source deformable image registration system for treatment planning and recurrence CT scans

DEFF Research Database (Denmark)

Zukauskaite, Ruta; Brink, Carsten; Hansen, Christian Rønn

2016-01-01

manually contoured eight anatomical regions-of-interest (ROI) twice on pCT and once on rCT. METHODS: pCT and rCT images were deformably registered using the open source software elastix. Mean surface distance (MSD) and Dice similarity coefficient (DSC) between contours were used for validation of DIR...

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

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

Single-slice rebinning method for helical cone-beam CT

International Nuclear Information System (INIS)

Noo, F.; Defrise, M.; Clackdoyle, R.

1999-01-01

In this paper, we present reconstruction results from helical cone-beam CT data, obtained using a simple and fast algorithm, which we call the CB-SSRB algorithm. This algorithm combines the single-slice rebinning method of PET imaging with the weighting schemes of spiral CT algorithms. The reconstruction is approximate but can be performed using 2D multislice fan-beam filtered backprojection. The quality of the results is surprisingly good, and far exceeds what one might expect, even when the pitch of the helix is large. In particular, with this algorithm comparable quality is obtained using helical cone-beam data with a normalized pitch of 10 to that obtained using standard spiral CT reconstruction with a normalized pitch of 2. (author)

Dual-energy CT virtual non-calcium technique for detection of bone marrow edema in patients with vertebral fractures: A prospective feasibility study on a single- source volume CT scanner

Energy Technology Data Exchange (ETDEWEB)

Diekhoff, T., E-mail: torsten.diekhoff@charite.de [Department of Radiology, Charité - Universitätsmedizin Berlin Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Berlin (Germany); Hermann, K.G. [Department of Radiology, Charité - Universitätsmedizin Berlin Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Berlin (Germany); Pumberger, M. [Department of Spine Surgery, Center for Musculoskeletal Surgery, Charité - Universitätsmedizin Berlin Campus Mitte, Berlin (Germany); Hamm, B. [Department of Radiology, Charité - Universitätsmedizin Berlin Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Berlin (Germany); Putzier, M.; Fuchs, M. [Department of Spine Surgery, Center for Musculoskeletal Surgery, Charité - Universitätsmedizin Berlin Campus Mitte, Berlin (Germany)

2017-02-15

Objectives: Dual-energy computed tomography (DECT) is a recent development for detecting bone marrow edema (BME) in patients with vertebral compression fractures. The aim of this pilot study was to determine the reliability of single-source DECT in detecting vertebral BME using magnetic resonance imaging (MRI) as standard of reference. Materials and methods: Nine patients with radiographic thoracic or lumbar vertebral compression fractures underwent both, DECT on a 320-row single-source scanner and 1.5 T MRI. Virtual non-calcium (VNC) images were reconstructed from the DECT volume datasets. Three blinded readers independently scored images for the presence of BME. Only vertebrae with loss of height in radiography (target vertebrae) were included in the analysis. A vertebra was counted as positive if two readers agreed on the presence of BME. Cohen’s kappa was calculated for interrater comparison. Intervertebral ratios of target and the reference vertebra were compared for CT attenuation and MR signal intensity in a reference vertebra using Spearman correlation. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Results: Fourteen target vertebrae with a radiographic height loss were identified; eight of them showed BME on MRI, while DECT identified BME in 7 instances. There were no false positive virtual non-calcium images, resulting in a sensitivity of 0.88 (0.75–1.0 among all readers) and specificity of 1.0 (0.81–1.0). Interrater agreement was inferior for DECT (κ = 0.63–0.89) compared to MRI (κ = 0.9–1.0). Intervertebral ratio in VNC images strongly correlated with short-tau inversion recovery (r = 0.87) and inversely with T1 (-0.89). SNR (0.2 +/− 0.2 in VNC and 16.7 +/− 7.3 in STIR) and CNR (0.2 +/− 0.3 and 7.1 +/− 6.3) values were inferior in VNC. Conclusions: Detecting BME with single-source DECT is feasible and allows detection of vertebral compression fractures with reasonably high sensitivity and specificity

Dual-energy CT virtual non-calcium technique for detection of bone marrow edema in patients with vertebral fractures: A prospective feasibility study on a single- source volume CT scanner

International Nuclear Information System (INIS)

Diekhoff, T.; Hermann, K.G.; Pumberger, M.; Hamm, B.; Putzier, M.; Fuchs, M.

2017-01-01

Objectives: Dual-energy computed tomography (DECT) is a recent development for detecting bone marrow edema (BME) in patients with vertebral compression fractures. The aim of this pilot study was to determine the reliability of single-source DECT in detecting vertebral BME using magnetic resonance imaging (MRI) as standard of reference. Materials and methods: Nine patients with radiographic thoracic or lumbar vertebral compression fractures underwent both, DECT on a 320-row single-source scanner and 1.5 T MRI. Virtual non-calcium (VNC) images were reconstructed from the DECT volume datasets. Three blinded readers independently scored images for the presence of BME. Only vertebrae with loss of height in radiography (target vertebrae) were included in the analysis. A vertebra was counted as positive if two readers agreed on the presence of BME. Cohen’s kappa was calculated for interrater comparison. Intervertebral ratios of target and the reference vertebra were compared for CT attenuation and MR signal intensity in a reference vertebra using Spearman correlation. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Results: Fourteen target vertebrae with a radiographic height loss were identified; eight of them showed BME on MRI, while DECT identified BME in 7 instances. There were no false positive virtual non-calcium images, resulting in a sensitivity of 0.88 (0.75–1.0 among all readers) and specificity of 1.0 (0.81–1.0). Interrater agreement was inferior for DECT (κ = 0.63–0.89) compared to MRI (κ = 0.9–1.0). Intervertebral ratio in VNC images strongly correlated with short-tau inversion recovery (r = 0.87) and inversely with T1 (-0.89). SNR (0.2 +/− 0.2 in VNC and 16.7 +/− 7.3 in STIR) and CNR (0.2 +/− 0.3 and 7.1 +/− 6.3) values were inferior in VNC. Conclusions: Detecting BME with single-source DECT is feasible and allows detection of vertebral compression fractures with reasonably high sensitivity and specificity

Dual-energy CT virtual non-calcium technique for detection of bone marrow edema in patients with vertebral fractures: A prospective feasibility study on a single- source volume CT scanner.

Science.gov (United States)

Diekhoff, T; Hermann, K G; Pumberger, M; Hamm, B; Putzier, M; Fuchs, M

2017-02-01

Dual-energy computed tomography (DECT) is a recent development for detecting bone marrow edema (BME) in patients with vertebral compression fractures. The aim of this pilot study was to determine the reliability of single-source DECT in detecting vertebral BME using magnetic resonance imaging (MRI) as standard of reference. Nine patients with radiographic thoracic or lumbar vertebral compression fractures underwent both, DECT on a 320-row single-source scanner and 1.5T MRI. Virtual non-calcium (VNC) images were reconstructed from the DECT volume datasets. Three blinded readers independently scored images for the presence of BME. Only vertebrae with loss of height in radiography (target vertebrae) were included in the analysis. A vertebra was counted as positive if two readers agreed on the presence of BME. Cohen's kappa was calculated for interrater comparison. Intervertebral ratios of target and the reference vertebra were compared for CT attenuation and MR signal intensity in a reference vertebra using Spearman correlation. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Fourteen target vertebrae with a radiographic height loss were identified; eight of them showed BME on MRI, while DECT identified BME in 7 instances. There were no false positive virtual non-calcium images, resulting in a sensitivity of 0.88 (0.75-1.0 among all readers) and specificity of 1.0 (0.81-1.0). Interrater agreement was inferior for DECT (κ=0.63-0.89) compared to MRI (κ=0.9-1.0). Intervertebral ratio in VNC images strongly correlated with short-tau inversion recovery (r=0.87) and inversely with T1 (-0.89). SNR (0.2+/- 0.2 in VNC and 16.7+/- 7.3 in STIR) and CNR (0.2+/- 0.3 and 7.1+/- 6.3) values were inferior in VNC. Detecting BME with single-source DECT is feasible and allows detection of vertebral compression fractures with reasonably high sensitivity and specificity. However, image quality of VNC reconstructions has to be improved to achieve better

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.

Determination of single-kidney glomerular filtration rate (GFR) with CT urography versus renal dynamic imaging Gates method

Energy Technology Data Exchange (ETDEWEB)

You, Shan [Hebei North University, Department of Graduate, Zhangjiakou City, Hebei Province (China); Ma, XianWu; Zhang, ChangZhu; Li, Qiang [Qiqihar Chinese Medicine Hospital, Department of Radiology, Qigihar City, Heilongjiang Province (China); Shi, WenWei; Zhang, Jing; Yuan, XiaoDong [The 309th Hospital of Chinese People' s Liberation Army, Department of Radiology, Beijing (China)

2018-03-15

To present a single-kidney CT-GFR measurement and compare it with the renal dynamic imaging Gates-GFR. Thirty-six patients with hydronephrosis referred for CT urography and 99mTc-DTPA renal dynamic imaging were prospectively included. Informed consent was obtained from all patients. The CT urography protocol included non-contrast, nephrographic, and excretory phase imaging. The total CT-GFR was calculated by dividing the CT number increments of the total urinary system between the nephrographic and excretory phase by the products of iodine concentration in the aorta and the elapsed time, then multiplied by (1- Haematocrit). The total CT-GFR was then split into single-kidney CT-GFR by a left and right kidney proportionality factor. The results were compared with single-kidney Gates-GFR by using paired t-test, correlation analysis, and Bland-Altman plots. Paired difference between single-kidney CT-GFR (45.02 ± 13.91) and single-kidney Gates-GFR (51.21 ± 14.76) was 6.19 ± 5.63 ml/min, p<0.001, demonstrating 12.1% systematic underestimation with ±11.03 ml/min (±21.5%) measurement deviation. A good correlation was revealed between both measurements (r=0.87, p<0.001). The proposed single-kidney CT-GFR correlates and agrees well with the reference standard despite a systematic underestimation, therefore it could be a one-stop-shop for evaluating urinary tract morphology and split renal function. (orig.)

Determination of single-kidney glomerular filtration rate (GFR) with CT urography versus renal dynamic imaging Gates method

International Nuclear Information System (INIS)

You, Shan; Ma, XianWu; Zhang, ChangZhu; Li, Qiang; Shi, WenWei; Zhang, Jing; Yuan, XiaoDong

2018-01-01

To present a single-kidney CT-GFR measurement and compare it with the renal dynamic imaging Gates-GFR. Thirty-six patients with hydronephrosis referred for CT urography and 99mTc-DTPA renal dynamic imaging were prospectively included. Informed consent was obtained from all patients. The CT urography protocol included non-contrast, nephrographic, and excretory phase imaging. The total CT-GFR was calculated by dividing the CT number increments of the total urinary system between the nephrographic and excretory phase by the products of iodine concentration in the aorta and the elapsed time, then multiplied by (1- Haematocrit). The total CT-GFR was then split into single-kidney CT-GFR by a left and right kidney proportionality factor. The results were compared with single-kidney Gates-GFR by using paired t-test, correlation analysis, and Bland-Altman plots. Paired difference between single-kidney CT-GFR (45.02 ± 13.91) and single-kidney Gates-GFR (51.21 ± 14.76) was 6.19 ± 5.63 ml/min, p<0.001, demonstrating 12.1% systematic underestimation with ±11.03 ml/min (±21.5%) measurement deviation. A good correlation was revealed between both measurements (r=0.87, p<0.001). The proposed single-kidney CT-GFR correlates and agrees well with the reference standard despite a systematic underestimation, therefore it could be a one-stop-shop for evaluating urinary tract morphology and split renal function. (orig.)

Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: image reconstruction and assessment of image quality.

Science.gov (United States)

Flohr, Thomas G; Leng, Shuai; Yu, Lifeng; Aiimendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H

2009-12-01

To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. No significant differences in quantitative measures of image quality were found between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6 pitch 3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch = 3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving coronary artery phantom

Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: Image reconstruction and assessment of image quality

International Nuclear Information System (INIS)

Flohr, Thomas G.; Leng Shuai; Yu Lifeng; Allmendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D.; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H.

2009-01-01

Purpose: To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. Methods: With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. Results: No significant differences in quantitative measures of image quality were found between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6≤pitch≤3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch=3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving

Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: Image reconstruction and assessment of image quality

Energy Technology Data Exchange (ETDEWEB)

Flohr, Thomas G.; Leng Shuai; Yu Lifeng; Allmendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D.; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H. [Siemens Healthcare, Computed Tomography, 91301 Forchheim, Germany and Department of Diagnostic Radiology, Eberhard-Karls-Universitaet, 72076 Tuebingen (Germany); Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Siemens Healthcare, Computed Tomography, 91301 Forchheim (Germany); Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

2009-12-15

Purpose: To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. Methods: With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. Results: No significant differences in quantitative measures of image quality were found between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6{<=}pitch{<=}3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch=3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving

Single-photon sources based on single molecules in solids

International Nuclear Information System (INIS)

Moerner, W E

2004-01-01

Single molecules in suitable host crystals have been demonstrated to be useful single-photon emitters both at liquid-helium temperatures and at room temperature. The low-temperature source achieved controllable emission of single photons from a single terrylene molecule in p-terphenyl by an adiabatic rapid passage technique. In contrast with almost all other single-molecule systems, terrylene single molecules show extremely high photostability under continuous, high-intensity irradiation. A room-temperature source utilizing this material has been demonstrated, in which fast pumping into vibrational sidebands of the electronically excited state achieved efficient inversion of the emissive level. This source yielded a single-photon emission probability p(1) of 0.86 at a detected count rate near 300 000 photons s -1 , with very small probability of emission of more than one photon. Thus, single molecules in solids can be considered as contenders for applications of single-photon sources such as quantum key distribution

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

Comprehensive low-dose imaging of carotid and coronary arteries with a single-injection dual-source CT angiography protocol.

Science.gov (United States)

Tognolini, A; Arellano, C S; Marfori, W; Heidari, G; Sayre, J W; Krishnam, M S; Ruehm, S G

2014-03-01

To assess the feasibility of a fast single-bolus combined carotid and coronary computed tomography angiography (CTA) protocol in asymptomatic patients. Thirty-three consecutive patients (18 women and 15 men) with a median age of 61 ± 14 years old (range 37-87 years) with known or suspected atherosclerotic disease were enrolled in this prospective study. A single breath-hold, single biphasic injection protocol (50 ml at 3 ml/s, 50 ml at 5 ml/s, 50 ml saline flush at 5 ml/s) was used for combined CTA imaging of the supra-aortic (SAA) and coronary arteries (CA) on a 64-slice dual-source CT (DSCT) machine. Helical CTA acquisition of the SAA was followed by prospective electrocardiography (ECG)-triggered coronary CTA. Subjective (four-point scale) image quality and objective signal-to-noise (SNR) and contrast-to-noise (CNR) measurements were performed. Vascular disease was graded on a four-point scale (grade 1: absent; grade 2: mild, grade 3: moderate; grade 4: severe). The radiation dose was recorded for each patient. The average enhancement and subjective quality score of SAA and CA segments were 396 HU/358 HU and 1.2 ± 0.3/1.72 ± 0.4, respectively. The SNR was 27.1 ± 1.7 in the SAA and 21.6 ± 1.6 in the CA (p grade 2 and 1/33 (3%) had grade 3 disease. CA findings were as follows: 25/33 (76%) showed no disease and 6/33 (18%) patients had grade 2 and 2/33 (6%) had grade 3 disease. Five patients had disease in both districts. The average radiation dose for the combined CTA angiogram was 4.3 ± 0.6 mSv. A fast, low-dose combined DSCT angiography protocol appears technically feasible for imaging carotid and coronary atherosclerotic disease. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

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

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

Single photon sources with single semiconductor quantum dots

Science.gov (United States)

Shan, Guang-Cun; Yin, Zhang-Qi; Shek, Chan Hung; Huang, Wei

2014-04-01

In this contribution, we briefly recall the basic concepts of quantum optics and properties of semiconductor quantum dot (QD) which are necessary to the understanding of the physics of single-photon generation with single QDs. Firstly, we address the theory of quantum emitter-cavity system, the fluorescence and optical properties of semiconductor QDs, and the photon statistics as well as optical properties of the QDs. We then review the localization of single semiconductor QDs in quantum confined optical microcavity systems to achieve their overall optical properties and performances in terms of strong coupling regime, efficiency, directionality, and polarization control. Furthermore, we will discuss the recent progress on the fabrication of single photon sources, and various approaches for embedding single QDs into microcavities or photonic crystal nanocavities and show how to extend the wavelength range. We focus in particular on new generations of electrically driven QD single photon source leading to high repetition rates, strong coupling regime, and high collection efficiencies at elevated temperature operation. Besides, new developments of room temperature single photon emission in the strong coupling regime are reviewed. The generation of indistinguishable photons and remaining challenges for practical single-photon sources are also discussed.

Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part I: Studies on Image Quality Using Dual Source CT

International Nuclear Information System (INIS)

Hwang, Hye Jeon; Seo, Joon Beom; Lee, Jin Seong; Song, Jae Woo; Lee, Hyun Joo; Lim, Chae Hun; Kim, Song Soo

2012-01-01

To determine whether the image quality (IQ) is improved with iterative reconstruction in image space (IRIS), and whether IRIS can be used for radiation reduction in chest CT. Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying a dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from a single tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Objective noise was measured. The subjective IQ was evaluated by radiologists for the followings: noise, contrast and sharpness of mediastinum and lung. Objective noise was significantly lower in H-IRIS than in F-FBP (p < 0.01). In both SDCT and LDCT, the IQ scores were highest in F-IRIS, followed by F-FBP, H-IRIS and H-FBP, except those for sharpness of mediastinum, which tended to be higher in FBP. When comparing CT images between the same dose and different reconstruction (F-IRIS/F-FBP and H-IRIS/H-FBP) algorithms, scores tended to be higher in IRIS than in FBP, being more distinct in half-dose images. However, despite the use of IRIS, the scores were lower in H-IRIS than in F-FBP. IRIS generally helps improve the IQ, being more distinct at the reduced radiation. However, reduced radiation by half results in IQ decrease even when using IRIS in chest CT.

Value of 100 kVp scan with sinogram-affirmed iterative reconstruction algorithm on a single-source CT system during whole-body CT for radiation and contrast medium dose reduction: an intra-individual feasibility study.

Science.gov (United States)

Nagayama, Y; Nakaura, T; Oda, S; Tsuji, A; Urata, J; Furusawa, M; Tanoue, S; Utsunomiya, D; Yamashita, Y

2018-02-01

To perform an intra-individual investigation of the usefulness of a contrast medium (CM) and radiation dose-reduction protocol using single-source computed tomography (CT) combined with 100 kVp and sinogram-affirmed iterative reconstruction (SAFIRE) for whole-body CT (WBCT; chest-abdomen-pelvis CT) in oncology patients. Forty-three oncology patients who had undergone WBCT under both 120 and 100 kVp protocols at different time points (mean interscan intervals: 98 days) were included retrospectively. The CM doses for the 120 and 100 kVp protocols were 600 and 480 mg iodine/kg, respectively; 120 kVp images were reconstructed with filtered back-projection (FBP), whereas 100 kVp images were reconstructed with FBP (100 kVp-F) and the SAFIRE (100 kVp-S). The size-specific dose estimate (SSDE), iodine load and image quality of each protocol were compared. The SSDE and iodine load of 100 kVp protocol were 34% and 21%, respectively, lower than of 120 kVp protocol (SSDE: 10.6±1.1 versus 16.1±1.8 mGy; iodine load: 24.8±4versus 31.5±5.5 g iodine, p<0.01). Contrast enhancement, objective image noise, contrast-to-noise-ratio, and visual score of 100 kVp-S were similar to or better than of 120 kVp protocol. Compared with the 120 kVp protocol, the combined use of 100 kVp and SAFIRE in WBCT for oncology assessment with an SSCT facilitated substantial reduction in the CM and radiation dose while maintaining image quality. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Dual-source CT cardiac imaging: initial experience

International Nuclear Information System (INIS)

Johnson, Thorsten R.C.; Nikolaou, Konstantin; Wintersperger, Bernd J.; Rist, Carsten; Buhmann, Sonja; Reiser, Maximilian F.; Becker, Christoph R.; Leber, Alexander W.; Ziegler, Franz von; Knez, Andreas

2006-01-01

The relation of heart rate and image quality in the depiction of coronary arteries, heart valves and myocardium was assessed on a dual-source computed tomography system (DSCT). Coronary CT angiography was performed on a DSCT (Somatom Definition, Siemens) with high concentration contrast media (Iopromide, Ultravist 370, Schering) in 24 patients with heart rates between 44 and 92 beats per minute. Images were reconstructed over the whole cardiac cycle in 10% steps. Two readers independently assessed the image quality with regard to the diagnostic evaluation of right and left coronary artery, heart valves and left ventricular myocardium for the assessment of vessel wall changes, coronary stenoses, valve morphology and function and ventricular function on a three point grading scale. The image quality ratings at the optimal reconstruction interval were 1.24±0.42 for the right and 1.09±0.27 for the left coronary artery. A reconstruction of diagnostic systolic and diastolic images is possible for a wide range of heart rates, allowing also a functional evaluation of valves and myocardium. Dual-source CT offers very robust diagnostic image quality in a wide range of heart rates. The high temporal resolution now also makes a functional evaluation of the heart valves and myocardium possible. (orig.)

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.

Comprehensive low-dose imaging of carotid and coronary arteries with a single-injection dual-source CT angiography protocol

International Nuclear Information System (INIS)

Tognolini, A.; Arellano, C.S.; Marfori, W.; Heidari, G.; Sayre, J.W.; Krishnam, M.S.; Ruehm, S.G.

2014-01-01

Aim: To assess the feasibility of a fast single-bolus combined carotid and coronary computed tomography angiography (CTA) protocol in asymptomatic patients. Materials and methods: Thirty-three consecutive patients (18 women and 15 men) with a median age of 61 ± 14 years old (range 37–87 years) with known or suspected atherosclerotic disease were enrolled in this prospective study. A single breath-hold, single biphasic injection protocol (50 ml at 3 ml/s, 50 ml at 5 ml/s, 50 ml saline flush at 5 ml/s) was used for combined CTA imaging of the supra-aortic (SAA) and coronary arteries (CA) on a 64-slice dual-source CT (DSCT) machine. Helical CTA acquisition of the SAA was followed by prospective electrocardiography (ECG)-triggered coronary CTA. Subjective (four-point scale) image quality and objective signal-to-noise (SNR) and contrast-to-noise (CNR) measurements were performed. Vascular disease was graded on a four-point scale (grade 1: absent; grade 2: mild, grade 3: moderate; grade 4: severe). The radiation dose was recorded for each patient. Results: The average enhancement and subjective quality score of SAA and CA segments were 396 HU/358 HU and 1.2 ± 0.3/1.72 ± 0.4, respectively. The SNR was 27.1 ± 1.7 in the SAA and 21.6 ± 1.6 in the CA (p < 0.0001). The CNR was 18.1 ± 1.2 and 15.9 ± 1.8, respectively (p = 0.4). Four percent of SAA and 14% of CA segments (mostly due to peri-venous streak artefacts and small calibre, respectively) produced non-diagnostic images. SAA findings were as follows: 26/33 (79%) patients showed no disease and 6/33 (18%) had grade 2 and 1/33 (3%) had grade 3 disease. CA findings were as follows: 25/33 (76%) showed no disease and 6/33 (18%) patients had grade 2 and 2/33 (6%) had grade 3 disease. Five patients had disease in both districts. The average radiation dose for the combined CTA angiogram was 4.3 ± 0.6 mSv. Conclusion: A fast, low-dose combined DSCT angiography protocol appears technically feasible for imaging carotid and

First experience with single-source dual-energy computed tomography in six patients with acute arthralgia: a feasibility experiment using joint aspiration as a reference

International Nuclear Information System (INIS)

Diekhoff, Torsten; Kiefer, Tobias; Hamm, Bernd; Hermann, Kay-Geert A.; Ziegeler, Katharina; Feist, Eugen; Mews, Juergen

2015-01-01

Dual-energy computed tomography (DECT) is an emerging imaging technique for examining patients with suspected gout. Single-source dual-energy CT (S-DECT) is a new way of obtaining DECT information on conventional CT scanners rather than using special dual-source CT systems. We tested the feasibility of S-DECT (320-row CT; Aquilion ONE, Toshiba Medical Systems, Otawara, Japan) in 6 patients (5 men, 1 woman; mean age 61.3, range 48 to 69 years) with acute arthralgia and suspected gout, and compared the S-DECT findings with the results of joint aspiration. Three patients had a diagnosis of gouty arthritis with negatively birefringent crystals in synovial fluid, in addition to gouty tophi in S-DECT. Three patients had no detectable crystals by polarization microscopy and no tophi on DECT. Their final diagnoses were rheumatoid arthritis, activated osteoarthritis, and septic arthritis in one case each. This initial experience suggests that S-DECT might be a valuable alternative to dual-source CT. Hence, more patients may benefit from its additional diagnostic abilities in the future. (orig.)

First experience with single-source dual-energy computed tomography in six patients with acute arthralgia: a feasibility experiment using joint aspiration as a reference

Energy Technology Data Exchange (ETDEWEB)

Diekhoff, Torsten; Kiefer, Tobias; Hamm, Bernd; Hermann, Kay-Geert A. [Charite - Universitaetsmedizin Berlin Campus Mitte, Humboldt-Universitaet zu Berlin, Freie Universitaet Berlin, Department of Radiology, Berlin (Germany); Ziegeler, Katharina; Feist, Eugen [Charite - Universitaetsmedizin Berlin Campus Mitte, Humboldt-Universitaet zu Berlin, Freie Universitaet Berlin, Department of Rheumatology and Clinical Immunology, Berlin (Germany); Mews, Juergen [Toshiba Medical Systems Europe, BV, Zoetermeer (Netherlands)

2015-11-15

Dual-energy computed tomography (DECT) is an emerging imaging technique for examining patients with suspected gout. Single-source dual-energy CT (S-DECT) is a new way of obtaining DECT information on conventional CT scanners rather than using special dual-source CT systems. We tested the feasibility of S-DECT (320-row CT; Aquilion ONE, Toshiba Medical Systems, Otawara, Japan) in 6 patients (5 men, 1 woman; mean age 61.3, range 48 to 69 years) with acute arthralgia and suspected gout, and compared the S-DECT findings with the results of joint aspiration. Three patients had a diagnosis of gouty arthritis with negatively birefringent crystals in synovial fluid, in addition to gouty tophi in S-DECT. Three patients had no detectable crystals by polarization microscopy and no tophi on DECT. Their final diagnoses were rheumatoid arthritis, activated osteoarthritis, and septic arthritis in one case each. This initial experience suggests that S-DECT might be a valuable alternative to dual-source CT. Hence, more patients may benefit from its additional diagnostic abilities in the future. (orig.)

Dual time point 18FDG-PET/CT versus single time point 18FDG-PET/CT for the differential diagnosis of pulmonary nodules - A meta-analysis

International Nuclear Information System (INIS)

Zhang, Li; Wang, Yinzhong; Lei, Junqiang; Tian, Jinhui; Zhai, Yanan

2013-01-01

Background: Lung cancer is one of the most common cancer types in the world. An accurate diagnosis of lung cancer is crucial for early treatment and management. Purpose: To perform a comprehensive meta-analysis to evaluate the diagnostic performance of dual time point 18F-fluorodexyglucose position emission tomography/computed tomography (FDG-PET/CT) and single time point 18FDG-PET/CT in the diagnosis of pulmonary nodules. Material and Methods: PubMed (1966-2011.11), EMBASE (1974-2011.11), Web of Science (1972-2011.11), Cochrane Library (-2011.11), and four Chinese databases; CBM (1978-2011.11), CNKI (1994-2011.11), VIP (1989-2011.11), and Wanfang Database (1994-2011.11) were searched. Summary sensitivity, summary specificity, summary diagnostic odds ratios (DOR), and summary positive likelihood ratios (LR+) and negative likelihood ratios (LR-) were obtained using Meta-Disc software. Summary receiver-operating characteristic (SROC) curves were used to evaluate the diagnostic performance of dual time point 18FDG-PET/CT and single time point 18FDG-PET/CT. Results: The inclusion criteria were fulfilled by eight articles, with a total of 415 patients and 430 pulmonary nodules. Compared with the gold standard (pathology or clinical follow-up), the summary sensitivity of dual time point 18FDG-PET/CT was 79% (95%CI, 74.0 - 84.0%), and its summary specificity was 73% (95%CI, 65.0-79.0%); the summary LR+ was 2.61 (95%CI, 1.96-3.47), and the summary LR- was 0.29 (95%CI, 0.21 - 0.41); the summary DOR was 10.25 (95%CI, 5.79 - 18.14), and the area under the SROC curve (AUC) was 0.8244. The summary sensitivity for single time point 18FDG-PET/CT was 77% (95%CI, 71.9 - 82.3%), and its summary specificity was 59% (95%CI, 50.6 - 66.2%); the summary LR+ was 1.97 (95%CI, 1.32 - 2.93), and the summary LR- was 0.37 (95%CI, 0.29 - 0.49); the summary DOR was 6.39 (95%CI, 3.39 - 12.05), and the AUC was 0.8220. Conclusion: The results indicate that dual time point 18FDG-PET/CT and single

A measurement-based generalized source model for Monte Carlo dose simulations of CT scans.

Science.gov (United States)

Ming, Xin; Feng, Yuanming; Liu, Ransheng; Yang, Chengwen; Zhou, Li; Zhai, Hezheng; Deng, Jun

2017-03-07

The goal of this study is to develop a generalized source model for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm. The in-air film measurement of fan-beam dose profiles at fixed gantry was back-projected to generate the fluence distribution of the source model. A benchmarked Monte Carlo user code was used to simulate the dose distributions in water with the developed source model as beam input. The feasibility and accuracy of the proposed source model was tested on a GE LightSpeed and a Philips Brilliance Big Bore multi-detector CT (MDCT) scanners available in our clinic. In general, the Monte Carlo simulations of the PDDs in water and dose profiles along lateral and longitudinal directions agreed with the measurements within 4%/1 mm for both CT scanners. The absolute dose comparison using two CTDI phantoms (16 cm and 32 cm in diameters) indicated a better than 5% agreement between the Monte Carlo-simulated and the ion chamber-measured doses at a variety of locations for the two scanners. Overall, this study demonstrated that a generalized source model can be constructed based only on a set of measurement data and used for accurate Monte Carlo dose simulations of patients' CT scans, which would facilitate patient-specific CT organ dose estimation and cancer risk management in the diagnostic and therapeutic radiology.

A measurement-based generalized source model for Monte Carlo dose simulations of CT scans

Science.gov (United States)

Ming, Xin; Feng, Yuanming; Liu, Ransheng; Yang, Chengwen; Zhou, Li; Zhai, Hezheng; Deng, Jun

2017-03-01

The goal of this study is to develop a generalized source model for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm. The in-air film measurement of fan-beam dose profiles at fixed gantry was back-projected to generate the fluence distribution of the source model. A benchmarked Monte Carlo user code was used to simulate the dose distributions in water with the developed source model as beam input. The feasibility and accuracy of the proposed source model was tested on a GE LightSpeed and a Philips Brilliance Big Bore multi-detector CT (MDCT) scanners available in our clinic. In general, the Monte Carlo simulations of the PDDs in water and dose profiles along lateral and longitudinal directions agreed with the measurements within 4%/1 mm for both CT scanners. The absolute dose comparison using two CTDI phantoms (16 cm and 32 cm in diameters) indicated a better than 5% agreement between the Monte Carlo-simulated and the ion chamber-measured doses at a variety of locations for the two scanners. Overall, this study demonstrated that a generalized source model can be constructed based only on a set of measurement data and used for accurate Monte Carlo dose simulations of patients’ CT scans, which would facilitate patient-specific CT organ dose estimation and cancer risk management in the diagnostic and therapeutic radiology.

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.)

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.

Technical Note: FreeCT_ICD: An Open Source Implementation of a Model-Based Iterative Reconstruction Method using Coordinate Descent Optimization for CT Imaging Investigations.

Science.gov (United States)

Hoffman, John M; Noo, Frédéric; Young, Stefano; Hsieh, Scott S; McNitt-Gray, Michael

2018-06-01

To facilitate investigations into the impacts of acquisition and reconstruction parameters on quantitative imaging, radiomics and CAD using CT imaging, we previously released an open source implementation of a conventional weighted filtered backprojection reconstruction called FreeCT_wFBP. Our purpose was to extend that work by providing an open-source implementation of a model-based iterative reconstruction method using coordinate descent optimization, called FreeCT_ICD. Model-based iterative reconstruction offers the potential for substantial radiation dose reduction, but can impose substantial computational processing and storage requirements. FreeCT_ICD is an open source implementation of a model-based iterative reconstruction method that provides a reasonable tradeoff between these requirements. This was accomplished by adapting a previously proposed method that allows the system matrix to be stored with a reasonable memory requirement. The method amounts to describing the attenuation coefficient using rotating slices that follow the helical geometry. In the initially-proposed version, the rotating slices are themselves described using blobs. We have replaced this description by a unique model that relies on tri-linear interpolation together with the principles of Joseph's method. This model offers an improvement in memory requirement while still allowing highly accurate reconstruction for conventional CT geometries. The system matrix is stored column-wise and combined with an iterative coordinate descent (ICD) optimization. The result is FreeCT_ICD, which is a reconstruction program developed on the Linux platform using C++ libraries and the open source GNU GPL v2.0 license. The software is capable of reconstructing raw projection data of helical CT scans. In this work, the software has been described and evaluated by reconstructing datasets exported from a clinical scanner which consisted of an ACR accreditation phantom dataset and a clinical pediatric

Closing in on the K Edge : Coronary CT Angiography at 100, 80, and 70 kV-Initial Comparison of a Second-versus a Third-Generation Dual-Source CT System

NARCIS (Netherlands)

Meyer, Mathias; Haubenreisser, Holger; Schoepf, U. Joseph; Vliegenthart, Rozemarijn; Leidecker, Christianne; Allmendinger, Thomas; Lehmann, Ralf; Sudarski, Sonja; Borggrefe, Martin; Schoenberg, Stefan O.; Henzler, Thomas

2014-01-01

Purpose: To prospectively evaluate radiation and contrast medium requirements for performing high-pitch coronary computed tomographic (CT) angiography at 70 kV using a third-generation dual-source CT system in comparison to a second-generation dual-source CT system. Materials and Methods: All

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)

Single minimum incision endoscopic radical nephrectomy for renal tumors with preoperative virtual navigation using 3D-CT volume-rendering

Directory of Open Access Journals (Sweden)

Shioyama Yasukazu

2010-04-01

Full Text Available Abstract Background Single minimum incision endoscopic surgery (MIES involves the use of a flexible high-definition laparoscope to facilitate open surgery. We reviewed our method of radical nephrectomy for renal tumors, which is single MIES combined with preoperative virtual surgery employing three-dimensional CT images reconstructed by the volume rendering method (3D-CT images in order to safely and appropriately approach the renal hilar vessels. We also assessed the usefulness of 3D-CT images. Methods Radical nephrectomy was done by single MIES via the translumbar approach in 80 consecutive patients. We performed the initial 20 MIES nephrectomies without preoperative 3D-CT images and the subsequent 60 MIES nephrectomies with preoperative 3D-CT images for evaluation of the renal hilar vessels and the relation of each tumor to the surrounding structures. On the basis of the 3D information, preoperative virtual surgery was performed with a computer. Results Single MIES nephrectomy was successful in all patients. In the 60 patients who underwent 3D-CT, the number of renal arteries and veins corresponded exactly with the preoperative 3D-CT data (100% sensitivity and 100% specificity. These 60 nephrectomies were completed with a shorter operating time and smaller blood loss than the initial 20 nephrectomies. Conclusions Single MIES radical nephrectomy combined with 3D-CT and virtual surgery achieved a shorter operating time and less blood loss, possibly due to safer and easier handling of the renal hilar vessels.

Advanced single-slice rebinning for tilted spiral cone-beam CT

International Nuclear Information System (INIS)

Kachelriess, Marc; Fuchs, Theo; Schaller, Stefan; Kalender, Willi A.

2001-01-01

Future medical CT scanners and today's micro CT scanners demand cone-beam reconstruction algorithms that are capable of reconstructing data acquired from a tilted spiral trajectory where the vector of rotation is not necessarily parallel to the vector of table increment. For the medical CT scanner this case of nonparallel object motion is met for nonzero gantry tilt: the table moves into a direction that is not perpendicular to the plane of rotation. Since this is not a special application of medical CT but rather a daily routine in head exams, there is a strong need for corresponding reconstruction algorithms. In contrast to medical CT, where the special case of nonperpendicular motion is used on purpose, micro CT scanners cannot avoid aberrations of the rotational axis and the table increment vector due to alignment problems. Especially for those micro CT scanners that have the lifting stage mounted on the rotation table (in contrast to setups where the lifting stage holds the rotation table), this kind of misalignment is equivalent to a gantry tilt. We therefore generalize the advanced single-slice rebinning algorithm (ASSR), which is considered a very promising approach for medical cone-beam reconstruction due to its high image quality and its high reconstruction speed [Med. Phys. 27, 754-772 (2000)], to the case of tilted gantries. We evaluate this extended ASSR approach (which we will denote as ASSR + , for convenience) in comparison to the original ASSR algorithm using simulated phantom data for reconstruction. For the case of nonparallel object motion ASSR + shows significant improvements over ASSR, however, its computational complexity is slightly increased due to the broken symmetry of the spiral trajectory

TU-A-12A-02: Novel Lung Ventilation Imaging with Single Energy CT After Single Inhalation of Xenon: Comparison with SPECT Ventilation Images

Energy Technology Data Exchange (ETDEWEB)

Negahdar, M [Stanford University School of Medicine, Stanford, CA (United States); Yamamoto, T [UC Davis School of Medicine, Sacramento, CA (United States); Shultz, D; Gable, L; Shan, X; Mittra, E; Loo, B; Maxim, P [Stanford University, Stanford, CA (United States); Diehn, M [Stanford University, Palo Alto, CA (United States)

2014-06-15

Purpose: We propose a novel lung functional imaging method to determine the spatial distribution of xenon (Xe) gas in a single inhalation as a measure of regional ventilation. We compare Xe-CT ventilation to single-photon emission CT (SPECT) ventilation, which is the current clinical reference. Regional lung ventilation information may be useful for the diagnosis and monitoring of pulmonary diseases such as COPD, radiotherapy planning, and assessing the progression of toxicity after radiation therapy. Methods: In an IRB-approved clinical study, Xe-CT and SPECT ventilation scans were acquired for three patients including one patient with severe emphysema and two lung cancer patients treated with radiotherapy. For Xe- CT, we acquired two breath-hold single energy CT images of the entire lung with inspiration of 100% O2 and a mixture of 70% Xe and 30% O2, respectively. A video biofeedback system was used to achieve reproducible breath-holds. We used deformable image registration to align the breathhold images with each other to accurately subtract them, producing a map of the distribution of Xe as a surrogate of lung ventilation. We divided each lung into twelve parts and correlated the Hounsfield unit (HU) enhancement at each part with the SPECT ventilation count of the corresponding part of the lung. Results: The mean of the Pearson linear correlation coefficient values between the Xe-CT and ventilation SPECT count for all three patients were 0.62 (p<0.01). The Xe-CT image had a higher resolution than SPECT, and did not show central airway deposition artifacts that were present in the SPECT image. Conclusion: We developed a rapid, safe, clinically practical, and potentially widely accessible method for regional lung functional imaging. We demonstrated strong correlations between the Xe-CT ventilation image and SPECT ventilation image as the clinical reference. This ongoing study will investigate more patients to confirm this finding.

TU-A-12A-02: Novel Lung Ventilation Imaging with Single Energy CT After Single Inhalation of Xenon: Comparison with SPECT Ventilation Images

International Nuclear Information System (INIS)

Negahdar, M; Yamamoto, T; Shultz, D; Gable, L; Shan, X; Mittra, E; Loo, B; Maxim, P; Diehn, M

2014-01-01

Purpose: We propose a novel lung functional imaging method to determine the spatial distribution of xenon (Xe) gas in a single inhalation as a measure of regional ventilation. We compare Xe-CT ventilation to single-photon emission CT (SPECT) ventilation, which is the current clinical reference. Regional lung ventilation information may be useful for the diagnosis and monitoring of pulmonary diseases such as COPD, radiotherapy planning, and assessing the progression of toxicity after radiation therapy. Methods: In an IRB-approved clinical study, Xe-CT and SPECT ventilation scans were acquired for three patients including one patient with severe emphysema and two lung cancer patients treated with radiotherapy. For Xe- CT, we acquired two breath-hold single energy CT images of the entire lung with inspiration of 100% O2 and a mixture of 70% Xe and 30% O2, respectively. A video biofeedback system was used to achieve reproducible breath-holds. We used deformable image registration to align the breathhold images with each other to accurately subtract them, producing a map of the distribution of Xe as a surrogate of lung ventilation. We divided each lung into twelve parts and correlated the Hounsfield unit (HU) enhancement at each part with the SPECT ventilation count of the corresponding part of the lung. Results: The mean of the Pearson linear correlation coefficient values between the Xe-CT and ventilation SPECT count for all three patients were 0.62 (p<0.01). The Xe-CT image had a higher resolution than SPECT, and did not show central airway deposition artifacts that were present in the SPECT image. Conclusion: We developed a rapid, safe, clinically practical, and potentially widely accessible method for regional lung functional imaging. We demonstrated strong correlations between the Xe-CT ventilation image and SPECT ventilation image as the clinical reference. This ongoing study will investigate more patients to confirm this finding

Dual-energy imaging of bone marrow edema on a dedicated multi-source cone-beam CT system for the extremities

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Zbijewski, W.; Sisniega, A.; Stayman, J. W.; Thawait, G.; Packard, N.; Yorkston, J.; Demehri, S.; Fritz, J.; Siewerdsen, J. H.

2015-03-01

Purpose: Arthritis and bone trauma are often accompanied by bone marrow edema (BME). BME is challenging to detect in CT due to the overlaying trabecular structure but can be visualized using dual-energy (DE) techniques to discriminate water and fat. We investigate the feasibility of DE imaging of BME on a dedicated flat-panel detector (FPD) extremities cone-beam CT (CBCT) with a unique x-ray tube with three longitudinally mounted sources. Methods: Simulations involved a digital BME knee phantom imaged with a 60 kVp low-energy beam (LE) and 105 kVp high-energy beam (HE) (+0.25 mm Ag filter). Experiments were also performed on a test-bench with a Varian 4030CB FPD using the same beam energies as the simulation study. A three-source configuration was implemented with x-ray sources distributed along the longitudinal axis and DE CBCT acquisition in which the superior and inferior sources operate at HE (and collect half of the projection angles each) and the central source operates at LE. Three-source DE CBCT was compared to a double-scan, single-source orbit. Experiments were performed with a wrist phantom containing a 50 mg/ml densitometry insert submerged in alcohol (simulating fat) with drilled trabeculae down to ~1 mm to emulate the trabecular matrix. Reconstruction-based three-material decomposition of fat, soft tissue, and bone was performed. Results: For a low-dose scan (36 mAs in the HE and LE data), DE CBCT achieved combined accuracy of ~0.80 for a pattern of BME spherical lesions ranging 2.5 - 10 mm diameter in the knee phantom. The accuracy increased to ~0.90 for a 360 mAs scan. Excellent DE discrimination of the base materials was achieved in the experiments. Approximately 80% of the alcohol (fat) voxels in the trabecular phantom was properly identified both for single and 3-source acquisitions, indicating the ability to detect edemous tissue (water-equivalent plastic in the body of the densitometry insert) from the fat inside the trabecular matrix

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.

Very low-dose (0.15 mGy) chest CT protocols using the COPDGene 2 test object and a third-generation dual-source CT scanner with corresponding third-generation iterative reconstruction software.

Science.gov (United States)

Newell, John D; Fuld, Matthew K; Allmendinger, Thomas; Sieren, Jered P; Chan, Kung-Sik; Guo, Junfeng; Hoffman, Eric A

2015-01-01

The purpose of this study was to evaluate the impact of ultralow radiation dose single-energy computed tomographic (CT) acquisitions with Sn prefiltration and third-generation iterative reconstruction on density-based quantitative measures of growing interest in phenotyping pulmonary disease. The effects of both decreasing dose and different body habitus on the accuracy of the mean CT attenuation measurements and the level of image noise (SD) were evaluated using the COPDGene 2 test object, containing 8 different materials of interest ranging from air to acrylic and including various density foams. A third-generation dual-source multidetector CT scanner (Siemens SOMATOM FORCE; Siemens Healthcare AG, Erlangen, Germany) running advanced modeled iterative reconstruction (ADMIRE) software (Siemens Healthcare AG) was used.We used normal and very large body habitus rings at dose levels varying from 1.5 to 0.15 mGy using a spectral-shaped (0.6-mm Sn) tube output of 100 kV(p). Three CT scans were obtained at each dose level using both rings. Regions of interest for each material in the test object scans were automatically extracted. The Hounsfield unit values of each material using weighted filtered back projection (WFBP) at 1.5 mGy was used as the reference value to evaluate shifts in CT attenuation at lower dose levels using either WFBP or ADMIRE. Statistical analysis included basic statistics, Welch t tests, multivariable covariant model using the F test to assess the significance of the explanatory (independent) variables on the response (dependent) variable, and CT mean attenuation, in the multivariable covariant model including reconstruction method. Multivariable regression analysis of the mean CT attenuation values showed a significant difference with decreasing dose between ADMIRE and WFBP. The ADMIRE has reduced noise and more stable CT attenuation compared with WFBP. There was a strong effect on the mean CT attenuation values of the scanned materials for ring

Dual-source CT in chest pain diagnosis

International Nuclear Information System (INIS)

Johnson, Thorsten R.C.; Nikolaou, K.; Fink, C.; Rist, C.; Reiser, M.F.; Becker, C.R.; Becker, A.; Knez, A.

2007-01-01

With the depiction of pulmonary arteries, coronary arteries, and the aorta, CT angiography of the chest offers a comprehensive diagnostic work-up of unclear chest pain. The aim of this study was to assess the diagnostic accuracy of dual-source CT in this patient group. A total of 47 patients suffering from unclear chest pain were examined with a Siemens Somatom Definition. Volume and flow of contrast media (Ultravist, Schering) were adapted to the body weight. The examinations were evaluated with regard to image quality and contrast opacification and to the diagnostic accuracy with reference to the final clinical diagnosis. Adequate contrast opacification was achieved in all examinations. The depiction of the coronary arteries was diagnostic in all cases. The cause of chest pain could be identified in 41 cases. Among the diagnoses were coronary and myocardial pathologies, valvular disease, aortic aneurysms and dissections, pulmonary embolism, and pneumonic consolidation. DSCT angiography of the chest offers a very good image quality even at high heart rates so that a high diagnostic accuracy is achieved in patients with acute chest pain. (orig.) [de

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

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

The utilization of dual source CT in imaging of polytrauma

Energy Technology Data Exchange (ETDEWEB)

Nicolaou, S. [University of British Columbia, Vancouver General Hospital, Department of Radiology, 899 West 12th Avenue, Vancouver, British Columbia, V5Z1M9 (Canada)], E-mail: savvas.nicolaou@vch.ca; Eftekhari, A.; Sedlic, T.; Hou, D.J.; Mudri, M.J.; Aldrich, John; Louis, L. [University of British Columbia, Vancouver General Hospital, Department of Radiology, 899 West 12th Avenue, Vancouver, British Columbia, V5Z1M9 (Canada)

2008-12-15

Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner.

The utilization of dual source CT in imaging of polytrauma

International Nuclear Information System (INIS)

Nicolaou, S.; Eftekhari, A.; Sedlic, T.; Hou, D.J.; Mudri, M.J.; Aldrich, John; Louis, L.

2008-01-01

Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner

Assessing Model Characterization of Single Source ...

Science.gov (United States)

Aircraft measurements made downwind from specific coal fired power plants during the 2013 Southeast Nexus field campaign provide a unique opportunity to evaluate single source photochemical model predictions of both O3 and secondary PM2.5 species. The model did well at predicting downwind plume placement. The model shows similar patterns of an increasing fraction of PM2.5 sulfate ion to the sum of SO2 and PM2.5 sulfate ion by distance from the source compared with ambient based estimates. The model was less consistent in capturing downwind ambient based trends in conversion of NOX to NOY from these sources. Source sensitivity approaches capture near-source O3 titration by fresh NO emissions, in particular subgrid plume treatment. However, capturing this near-source chemical feature did not translate into better downwind peak estimates of single source O3 impacts. The model estimated O3 production from these sources but often was lower than ambient based source production. The downwind transect ambient measurements, in particular secondary PM2.5 and O3, have some level of contribution from other sources which makes direct comparison with model source contribution challenging. Model source attribution results suggest contribution to secondary pollutants from multiple sources even where primary pollutants indicate the presence of a single source. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, deci

[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.

Coronary artery anomalies in adults: imaging at dual source CT coronary angiography

International Nuclear Information System (INIS)

Laspas, Fotios; Roussakis, Arkadios; Mourmouris, Christos; Kritikos, Nikolaos; Efthimiadou, Roxani; Andreou, John

2013-01-01

Congenital abnormalities of the coronary arteries have an incidence of 1%, and most of these are benign. However, a small number are associated with myocardial ischaemia and sudden death. Various imaging modalities are available for coronary artery assessment. Recently, multi-detector CT has emerged as an accurate diagnostic tool for defining coronary artery anomalies. The purpose of this pictorial essay is to review the dual source CT appearance of congenital anomalies of the coronary arteries in adults.

Tailoring single-photon and multiphoton probabilities of a single-photon on-demand source

International Nuclear Information System (INIS)

Migdall, A.L.; Branning, D.; Castelletto, S.

2002-01-01

As typically implemented, single-photon sources cannot be made to produce single photons with high probability, while simultaneously suppressing the probability of yielding two or more photons. Because of this, single-photon sources cannot really produce single photons on demand. We describe a multiplexed system that allows the probabilities of producing one and more photons to be adjusted independently, enabling a much better approximation of a source of single photons on demand

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.)

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.

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

Preliminary characterization of a single photon counting detection system for CT application

International Nuclear Information System (INIS)

Belcari, N.; Bisogni, M.G.; Carpentieri, C.; Del Guerra, A.; Delogu, P.; Panetta, D.; Quattrocchi, M.; Rosso, V.; Stefanini, A.

2007-01-01

The aim of this work is to evaluate the capability of a single photon counting acquisition system based on the Medipix2 read-out chip for Computed Tomography (CT) applications in Small Animal Imaging. We used a micro-focus X-ray source with a W anode. The detection system is based on the Medipix2 read-out chip, bump-bonded to a 1 mm thick silicon pixel detector. The read-out chip geometry is a matrix of 256x256 cells, 55 μmx55 μm each. This system in planar radiography shows a good detection efficiency (about 70%) at the anode voltage of 30 kV and a good spatial resolution (MTF=10% at 16.8 lp/mm). Starting from these planar performances we have characterized the system for the tomography applications with phantoms. We will present the results obtained as a function of magnification with two different background medium compositions. The effect of the reconstruction algorithm on image quality will be also discussed

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

Evaluation of image quality on a per-patient, per-vessel, and per-segment basis by noninvasive coronary angiography with 64-section computed tomography. Dual-source versus single-source computed tomography

International Nuclear Information System (INIS)

Nakashima, Yoshiteru; Okada, Munemasa; Washida, Yasuo; Miura, Toshiro; Fujimura, Tatsuo; Nao, Tomoko; Matsunaga, Naofumi

2011-01-01

The purpose of this study was to evaluate the image quality (IQ) of dual-source CT (DSCT) versus single-source CT (SSCT). A total of 100 patients underwent 64-section CT coronary angiography (50 DSCT, 50 SSCT). Three observers evaluated the IQ of each coronary segment using a four-point scale (1, excellent; 2, good; 3, fair; 4, no assessment). The IQ of DSCT coronary angiography was compared with SSCT coronary angiography on a per-patient, per-vessel, and per-segment basis using the chi-squared test. The DSCT image quality score (IQS) was significantly lower on a per-patient basis and per-vessel basis for all vessels and on a per-segment basis for some segments (1, 2, 4PD, 4AV, 7, 9, 11, 12, 13) compared with SSCT. The DSCT IQS was significantly lower for certain segments (2, 4PD, 11, 13) with high heart rates (≥70 beats/min). The DSCT IQS was significantly lower for certain segments (1, 2, 3, 4PD, 4AV, 7, 8, 9, 10, 12, 13) with low heart rates (<70 beats/min). DSCT showed a significantly better IQ than SSCT, especially in patients with low heart rates. (author)

A measurement-based X-ray source model characterization for CT dosimetry computations.

Science.gov (United States)

Sommerville, Mitchell; Poirier, Yannick; Tambasco, Mauro

2015-11-08

The purpose of this study was to show that the nominal peak tube voltage potential (kVp) and measured half-value layer (HVL) can be used to generate energy spectra and fluence profiles for characterizing a computed tomography (CT) X-ray source, and to validate the source model and an in-house kV X-ray dose computation algorithm (kVDoseCalc) for computing machine- and patient-specific CT dose. Spatial variation of the X-ray source spectra of a Philips Brilliance and a GE Optima Big Bore CT scanner were found by measuring the HVL along the direction of the internal bow-tie filter axes. Third-party software, Spektr, and the nominal kVp settings were used to generate the energy spectra. Beam fluence was calculated by dividing the integral product of the spectra and the in-air NIST mass-energy attenuation coefficients by in-air dose measurements along the filter axis. The authors found the optimal number of photons to seed in kVDoseCalc to achieve dose convergence. The Philips Brilliance beams were modeled for 90, 120, and 140 kVp tube settings. The GE Optima beams were modeled for 80, 100, 120, and 140 kVp tube settings. Relative doses measured using a Capintec Farmer-type ionization chamber (0.65 cc) placed in a cylindrical polymethyl methacrylate (PMMA) phantom and irradiated by the Philips Brilliance, were compared to those computed with kVDoseCalc. Relative doses in an anthropomorphic thorax phantom (E2E SBRT Phantom) irradiated by the GE Optima were measured using a (0.015 cc) PTW Freiburg ionization chamber and compared to computations from kVDoseCalc. The number of photons required to reduce the average statistical uncertainty in dose to measurement over all 12 PMMA phantom positions was found to be 1.44%, 1.47%, and 1.41% for 90, 120, and 140 kVp, respectively. The maximum percent difference between calculation and measurement for all energies, measurement positions, and phantoms was less than 3.50%. Thirty-five out of a total of 36 simulation conditions were

This immortal coil? New CT rigs duel against singles

Energy Technology Data Exchange (ETDEWEB)

Creighton, J.

1998-12-01

New competition to conventional single rigs that have changed little in the last four decades face new competition from next-generation coiled tubing (CT) units which have multi-function capabilities, ranging from driving onto leases, drilling and setting surface case to cementing. Several of these new units are ready to challenge the conventional single rigs. Their ability to perform at high penetration rates (up to twice what single rigs can do) is expected to significantly cut drill time, with corresponding cost savings for both contractors and operators. Serval Corporation and Fleet Coiled Services are just two of the drilling service companies that have launched new shallow grass roots coiled tubing drilling units recently, gambling that the new technology will win over conventional methods hands down. Some major companies, like Fracmaster Ltd. and NOWSCO Well Service Ltd., have targeted the re-entry and horizontal markets, a much more difficult technical challenge, sinking billions of dollars of research and development money into advancing the most technically difficult applications of coil technology.

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

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.

Optimizing CT angiography in patients with Fontan physiology: single-center experience of dual-site power injection

International Nuclear Information System (INIS)

Sandler, K.L.; Markham, L.W.; Mah, M.L.; Byrum, E.P.; Williams, J.R.

2014-01-01

Aim: To identify adult patients with single-ventricle congenital heart disease and Fontan procedure palliation who have been misdiagnosed with or incompletely evaluated for pulmonary embolism. Additionally, this study was designed to demonstrate that simultaneous, dual-injection of contrast medium into an upper and lower extremity vein is superior to single-injection protocols for CT angiography (CTA) of the chest in this population. Materials and methods: Patients included in the study were retrospectively selected from the Adult Congenital Heart Disease (ACHD) database. Search criteria included history of Fontan palliation and available chest CT examination. Patients were evaluated for (1) type of congenital heart disease and prior operations;(2) indication for initial CT evaluation;(3) route of contrast medium administration for the initial CT examination and resulting diagnosis;(4) whether or not anticoagulation therapy was initiated; and (5) final diagnosis and treatment plan. Results: The query of the ACHD database resulted in 28 individuals or patients with Fontan palliation (superior and inferior venae cavae anastomosed to the pulmonary arteries). Of these, 19 patients with Fontan physiology underwent CTA of the pulmonary circulation, and 17 had suboptimal imaging studies. Unfortunately, seven of these 17 patients (41%) were started on anticoagulation therapy due to a diagnosis of pulmonary embolism that was later excluded. Conclusion: Patients with single-ventricle/Fontan physiology are at risk of thromboembolic disease. Therefore, studies evaluating their complex anatomy must be performed with the optimal imaging protocol to ensure diagnostic accuracy, which is best achieved with dual-injection of an upper and lower extremity central vein. - Highlights: • The adult congenital heart disease population is growing. • Many of these patients have single ventricle/Fontan physiology. • Patients with Fontan physiology are at increased risk for

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.)

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.)

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....

Absorbed dose in CT. Comparison by CT dose index

International Nuclear Information System (INIS)

Yamamoto, Kenji; Akazawa, Hiroshi; Andou, Takashi

2002-01-01

Few reports have discussed the absorbed dose on CT units with increased scanning capacity even with the current widespread adoption of multi-slice CT units. To compare and investigate the dose indexes among CT units, we measured the absorbed dose on CT units operating in Nagano Prefecture Japan. The measurements showed proportionality between phantom absorbed dose and the exposured mAs values in conventional scanning operation. Further, the measurements showed that the absorbed dose in the center of the phantom differed by about 2.1-fold between the highest and lowest levels on individual CT units. Within a single company, multi-slice CT units of the same company gave absorbed doses of about 1.3 to 1.5 times those of conventional single-slice CT units under the same exposured conditions of conventional scanning. When the scanning pitch was reduced in helical scanning, the absorbed dose at the center of the phantom increased. (author)

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

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.)

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.)

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.

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.

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

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.

Photon statistics characterization of a single-photon source

International Nuclear Information System (INIS)

Alleaume, R; Treussart, F; Courty, J-M; Roch, J-F

2004-01-01

In a recent experiment, we reported the time-domain intensity noise measurement of a single-photon source relying on single-molecule fluorescence control. In this paper, we present data processing starting from photocount timestamps. The theoretical analytical expression of the time-dependent Mandel parameter Q(T) of an intermittent single-photon source is derived from ON↔OFF dynamics. Finally, source intensity noise analysis, using the Mandel parameter, is quantitatively compared with the usual approach relying on the time autocorrelation function, both methods yielding the same molecular dynamical parameters

Single-energy pediatric chest computed tomography with spectral filtration at 100 kVp: effects on radiation parameters and image quality

Energy Technology Data Exchange (ETDEWEB)

Bodelle, Boris; Fischbach, Constanze; Booz, Christian; Yel, Ibrahim; Frellesen, Claudia; Kaup, Moritz; Beeres, Martin; Vogl, Thomas J.; Scholtz, Jan-Erik [Goethe University of Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany)

2017-06-15

Most of the applied radiation dose at CT is in the lower photon energy range, which is of limited diagnostic importance. To investigate image quality and effects on radiation parameters of 100-kVp spectral filtration single-energy chest CT using a tin-filter at third-generation dual-source CT in comparison to standard 100-kVp chest CT. Thirty-three children referred for a non-contrast chest CT performed on a third-generation dual-source CT scanner were examined at 100 kVp with a dedicated tin filter with a tube current-time product resulting in standard protocol dose. We compared resulting images with images from children examined using standard single-source chest CT at 100 kVp. We assessed objective and subjective image quality and compared radiation dose parameters. Radiation dose was comparable for children 5 years old and younger, and it was moderately decreased for older children when using spectral filtration (P=0.006). Effective tube current increased significantly (P=0.0001) with spectral filtration, up to a factor of 10. Signal-to-noise ratio and image noise were similar for both examination techniques (P≥0.06). Subjective image quality showed no significant differences (P≥0.2). Using 100-kVp spectral filtration chest CT in children by means of a tube-based tin-filter on a third-generation dual-source CT scanner increases effective tube current up to a factor of 10 to provide similar image quality at equivalent dose compared to standard single-source CT without spectral filtration. (orig.)

Single-energy pediatric chest computed tomography with spectral filtration at 100 kVp: effects on radiation parameters and image quality

International Nuclear Information System (INIS)

Bodelle, Boris; Fischbach, Constanze; Booz, Christian; Yel, Ibrahim; Frellesen, Claudia; Kaup, Moritz; Beeres, Martin; Vogl, Thomas J.; Scholtz, Jan-Erik

2017-01-01

Most of the applied radiation dose at CT is in the lower photon energy range, which is of limited diagnostic importance. To investigate image quality and effects on radiation parameters of 100-kVp spectral filtration single-energy chest CT using a tin-filter at third-generation dual-source CT in comparison to standard 100-kVp chest CT. Thirty-three children referred for a non-contrast chest CT performed on a third-generation dual-source CT scanner were examined at 100 kVp with a dedicated tin filter with a tube current-time product resulting in standard protocol dose. We compared resulting images with images from children examined using standard single-source chest CT at 100 kVp. We assessed objective and subjective image quality and compared radiation dose parameters. Radiation dose was comparable for children 5 years old and younger, and it was moderately decreased for older children when using spectral filtration (P=0.006). Effective tube current increased significantly (P=0.0001) with spectral filtration, up to a factor of 10. Signal-to-noise ratio and image noise were similar for both examination techniques (P≥0.06). Subjective image quality showed no significant differences (P≥0.2). Using 100-kVp spectral filtration chest CT in children by means of a tube-based tin-filter on a third-generation dual-source CT scanner increases effective tube current up to a factor of 10 to provide similar image quality at equivalent dose compared to standard single-source CT without spectral filtration. (orig.)

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

Single-photon source engineering using a Modal Method

DEFF Research Database (Denmark)

Gregersen, Niels

Solid-state sources of single indistinguishable photons are of great interest for quantum information applications. The semiconductor quantum dot embedded in a host material represents an attractive platform to realize such a single-photon source (SPS). A near-unity efficiency, defined as the num...... nanowire SPSs...

Simultaneous CT and SPECT tomography using CZT detectors

Science.gov (United States)

Paulus, Michael J.; Sari-Sarraf, Hamed; Simpson, Michael L.; Britton, Jr., Charles L.

2002-01-01

A method for simultaneous transmission x-ray computed tomography (CT) and single photon emission tomography (SPECT) comprises the steps of: injecting a subject with a tracer compound tagged with a .gamma.-ray emitting nuclide; directing an x-ray source toward the subject; rotating the x-ray source around the subject; emitting x-rays during the rotating step; rotating a cadmium zinc telluride (CZT) two-sided detector on an opposite side of the subject from the source; simultaneously detecting the position and energy of each pulsed x-ray and each emitted .gamma.-ray captured by the CZT detector; recording data for each position and each energy of each the captured x-ray and .gamma.-ray; and, creating CT and SPECT images from the recorded data. The transmitted energy levels of the x-rays lower are biased lower than energy levels of the .gamma.-rays. The x-ray source is operated in a continuous mode. The method can be implemented at ambient temperatures.

Methods for forming particles from single source precursors

Science.gov (United States)

Fox, Robert V [Idaho Falls, ID; Rodriguez, Rene G [Pocatello, ID; Pak, Joshua [Pocatello, ID

2011-08-23

Single source precursors are subjected to carbon dioxide to form particles of material. The carbon dioxide may be in a supercritical state. Single source precursors also may be subjected to supercritical fluids other than supercritical carbon dioxide to form particles of material. The methods may be used to form nanoparticles. In some embodiments, the methods are used to form chalcopyrite materials. Devices such as, for example, semiconductor devices may be fabricated that include such particles. Methods of forming semiconductor devices include subjecting single source precursors to carbon dioxide to form particles of semiconductor material, and establishing electrical contact between the particles and an electrode.

27-Level DC–AC inverter with single energy source

International Nuclear Information System (INIS)

Tsang, K.M.; Chan, W.L.

2012-01-01

Highlights: ► This paper reports a novel 27-level DC–AC inverter using only single renewable energy source. ► The efficiency of the inverter is very high. The output waveform is almost sinusoidal. ► The cost is low as the number of power switches required is only 12. - Abstract: A novel design of multilevel DC–AC inverter using only single renewable energy source is presented in this paper. The proposed approach enables multilevel output to be realised by a few cascaded H-bridges and a single energy source. As an illustration, a 27-level inverter has been implemented based on three cascaded H-bridges with a single energy source and two capacitors. Using the proposed novel switching strategy, 27 levels can be realized and the two virtual energy sources can be well regulated. Experimental results are included to demonstrate the effectiveness of the proposed inverter.

Aphasia following left thalamic hemorrhage. A study by Western Aphasia Battery and single photon emission CT

Energy Technology Data Exchange (ETDEWEB)

Makishita, Hideo; Miyasaka, Motomaro; Tanizaki, Yoshio; Yanagisawa, Nobuo; Sugishita, Morihiro

1984-07-01

A report is given of 7 patients with left thalamic hemorrhage in the chronic stage (from 1.5 months to 4.5 months) in which language disorders were examined by Western Aphasia Battery (WAB) and cerebral blood flow was measured by single photon emission CT. Examination of language by WAB revealed 4 aphasics out of 7 cases, and 3 patients had no language deficit. The patient with Wernicke's aphasia showed low density area only in the left posterior thalamus in X-ray CT, and revealed severe low blood flow area extending to left temporal lobe in emission CT. In the case with transcortical sensory aphasia, although X-ray CT showed no obvious low density area, emission CT revealed moderate low flow area in the left temporooccipital region and low blood flow at the left thalamus. In one of the two patients classified as anomic aphasia, emission CT showed slight low flow area at the temporo-occipital region similar to the case with transcortical sensory aphasia. In another case with anomic aphasia there was a wide low density area all over the left thalamus and midline shift to the right in X-ray CT, and emission CT showed severe low blood flow in the same region spreading widely toward the cerebral surface. In all of the 3 patients without aphasia, emission CT showed low flow region restricted to the left thalamus.

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

The impact of heart rate on image quality and reconstruction timing of dual-source CT coronary angiography

International Nuclear Information System (INIS)

Wang Yining; Jin Zhengyu; Kong Lingyan; Zhang Zhuhua; Song Lan; Mu Wenbin; Wang Yun; Zhao Wenmin; Zhang Shuyang; Lin Songbai

2008-01-01

Objective: To evaluate the impact of patient's heart rate (HR) on coronary CT angiography (CTA) image quality (IQ) and reconstruction timing in dual-source CT (DSCT). Methods Ninety-five patients with suspicion of coronary artery disease were examined with a DSCT scanner (Somatom Definition, Siemens) using 32 x 0.6 mm collimation. All patients were divided three groups according to the heart rate (HR): group 1, HR ≤ 70 beats per minute (bpm), n=26; group 2, HR >70 bpm to ≤90 bpm, n=37; group 3, HR > 90 bpm, n=32. No beta-blockers were taken before CT scan. 50- 60 ml of nonionic contrast agent were injected with a rate of 5 ml/s. Images were reconstructed from 10% to 100% of the R-R interval using single-segment reconstruction. Two readers independently assessed IQ of all coronary, segments using a 3-point scale from excellent (1) to non-assessable (3) for coronary segments and the relationship between IQ and the HR. Results: Overall mean IQ score was 1.31 ± 0.55 for all patients with 1.08 ± 0.27 for group 1, 1.32 ± 0.58 for group 2 and 1.47 ± 0.61 for group 3. The IQ was better in the LAD than the RCA and LCX (P<0.01). Only 1.4% (19/1386) of coronary artery segments were considered non-assessable due to the motion artifacts. Optimal image quality of all coronary segments in 74 patients (77.9%) can be achieved with one reconstruction data set. The best IQ was predominately in diastole (88.5%) in group 1, while the best IQ was in systole (84.4%) in group 3. Conclusions: DSCT can achieve the optimal IQ with a wide range of HR using single-segment reconstruction. With the increasing of HR, the timing of data reconstruction for the best IQ shifts from mid-diastole to systole. (authors)

Abdominal and Pelvic CT

Medline Plus

Full Text Available ... view of the body's interior. Refinements in detector technology allow nearly all CT scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ...

Computed Tomography (CT) -- Sinuses

Medline Plus

Full Text Available ... view of the body's interior. Refinements in detector technology allow nearly all CT scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ...

Computed Tomography (CT) -- Head

Medline Plus

Full Text Available ... view of the body's interior. Refinements in detector technology allow nearly all CT scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ...

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.

CT-angiography source images indicate less fatal outcome despite coma of patients in the Basilar Artery International Cooperation Study.

Science.gov (United States)

Pallesen, Lars P; Khomenko, Andrei; Dzialowski, Imanuel; Barlinn, Jessica; Barlinn, Kristian; Zerna, Charlotte; van der Hoeven, Erik Jrj; Algra, Ale; Kapelle, L Jaap; Michel, Patrik; Bodechtel, Ulf; Demchuk, Andrew M; Schonewille, Wouter; Puetz, Volker

2017-02-01

Background Coma is associated with poor outcome in patients with basilar artery occlusion. Aims We sought to assess whether the posterior circulation Acute Stroke Prognosis Early CT Score and the Pons-Midbrain Index applied to CT angiography source images predict the outcome of comatose patients in the Basilar Artery International Cooperation Study. Methods Basilar Artery International Cooperation Study was a prospective, observational registry of patients with acute basilar artery occlusion with 48 recruiting centers worldwide. We applied posterior circulation Acute Stroke Prognosis Early CT Score and Pons-Midbrain Index to CT angiography source images of Basilar Artery International Cooperation Study patients who presented with coma. We calculated adjusted risk ratios to assess the association of dichotomized posterior circulation Acute Stroke Prognosis Early CT Score (≥8 vs. International Cooperation Study registry, CT angiography source images were available for review in 158 patients. Among these, 78 patients (49%) presented with coma. Compared to non-comatose patients, comatose patients were more likely to die (risk ratios 2.34; CI 95% 1.56-3.52) and less likely to have a favourable outcome (risk ratios 0.44; CI 95% 0.24-0.80). Among comatose patients, a Pons-Midbrain Index < 3 was related to reduced mortality (adjusted RR 0.66; 95% CI 0.46-0.96), but not to favourable outcome (adjusted RR 1.19; 95% CI 0.39-3.62). Posterior circulation Acute Stroke Prognosis Early CT Score dichotomized at ≥ 8 vs. <8 was not significantly associated with death (adjusted RR 0.70; 95% CI 0.46-1.05). Conclusion In comatose patients with basilar artery occlusion, the extent of brainstem ischemia appears to be related to mortality but not to favourable outcome.

Imaging skeletal anatomy of injured cervical spine specimens: comparison of single-slice vs multi-slice helical CT

Energy Technology Data Exchange (ETDEWEB)

Obenauer, S.; Alamo, L.; Herold, T.; Funke, M.; Kopka, L.; Grabbe, E. [Department of Radiology, Georg August-University Goettingen, Robert-Koch-Strasse 40, 37075 Goettingen (Germany)

2002-08-01

Our objective was to compare a single-slice CT (SS-CT) scanner with a multi-slice CT (MS-CT) scanner in the depiction of osseous anatomic structures and fractures of the upper cervical spine. Two cervical spine specimens with artificial trauma were scanned with a SS-CT scanner (HighSpeed, CT/i, GE, Milwaukee, Wis.) by using various collimations (1, 3, 5 mm) and pitch factors (1, 1.5, 2, 3) and a four-slice helical CT scanner (LightSpeed, QX/i, GE, Milwaukee, Wis.) by using various table speeds ranging from 3.75 to 15 mm/rotation for a pitch of 0.75 and from 7.5 to 30 mm/rotation for a pitch of 1.5. Images were reconstructed with an interval of 1 mm. Sagittal and coronal multiplanar reconstructions of the primary and reconstructed data set were performed. For MS-CT a tube current resulting in equivalent image noise as with SS-CT was used. All images were judged by two observers using a 4-point scale. The best image quality for SS-CT was achieved with the smallest slice thickness (1 mm) and a pitch smaller than 2 resulting in a table speed of up to 2 mm per gantry rotation (4 points). A reduction of the slice thickness rather than of the table speed proved to be beneficial at MS-CT. Therefore, the optimal scan protocol in MS-CT included a slice thickness of 1.25 mm with a table speed of 7.5 mm/360 using a pitch of 1.5 (4 points), resulting in a faster scan time than when a pitch of 0.75 (4 points) was used. This study indicates that MS-CT could provide equivalent image quality at approximately four times the volume coverage speed of SS-CT. (orig.)

Dual Contrast CT Method Enables Diagnostics of Cartilage Injuries and Degeneration Using a Single CT Image.

Science.gov (United States)

Saukko, Annina E A; Honkanen, Juuso T J; Xu, Wujun; Väänänen, Sami P; Jurvelin, Jukka S; Lehto, Vesa-Pekka; Töyräs, Juha

2017-12-01

Cartilage injuries may be detected using contrast-enhanced computed tomography (CECT) by observing variations in distribution of anionic contrast agent within cartilage. Currently, clinical CECT enables detection of injuries and related post-traumatic degeneration based on two subsequent CT scans. The first scan allows segmentation of articular surfaces and lesions while the latter scan allows evaluation of tissue properties. Segmentation of articular surfaces from the latter scan is difficult since the contrast agent diffusion diminishes the image contrast at surfaces. We hypothesize that this can be overcome by mixing anionic contrast agent (ioxaglate) with bismuth oxide nanoparticles (BINPs) too large to diffuse into cartilage, inducing a high contrast at the surfaces. Here, a dual contrast method employing this mixture is evaluated by determining the depth-wise X-ray attenuation profiles in intact, enzymatically degraded, and mechanically injured osteochondral samples (n = 3 × 10) using a microCT immediately and at 45 min after immersion in contrast agent. BiNPs were unable to diffuse into cartilage, producing high contrast at articular surfaces. Ioxaglate enabled the detection of enzymatic and mechanical degeneration. In conclusion, the dual contrast method allowed detection of injuries and degeneration simultaneously with accurate cartilage segmentation using a single scan conducted at 45 min after contrast agent administration.

Highly efficient sources of single indistinguishable photons

DEFF Research Database (Denmark)

Gregersen, Niels

2013-01-01

be electrically driven. Several design strategies addressing these requirements have been proposed. In the cavity-based source, light emission is controlled using resonant cavity quantum electrodynamics effects, whereas in the waveguide-based source, broadband electric field screening effects are employed......Solid-state sources capable of emitting single photons on demand are of great interest in quantum information applications. Ideally, such a source should emit exactly one photon into the collection optics per trigger, the emitted photons should be indistinguishable and the source should...

Clinical evaluation of a dose monitoring software tool based on Monte Carlo Simulation in assessment of eye lens doses for cranial CT scans

Energy Technology Data Exchange (ETDEWEB)

Guberina, Nika; Suntharalingam, Saravanabavaan; Nassenstein, Kai; Forsting, Michael; Theysohn, Jens; Wetter, Axel; Ringelstein, Adrian [University Hospital Essen, Institute of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany)

2016-10-15

The aim of this study was to verify the results of a dose monitoring software tool based on Monte Carlo Simulation (MCS) in assessment of eye lens doses for cranial CT scans. In cooperation with the Federal Office for Radiation Protection (Neuherberg, Germany), phantom measurements were performed with thermoluminescence dosimeters (TLD LiF:Mg,Ti) using cranial CT protocols: (I) CT angiography; (II) unenhanced, cranial CT scans with gantry angulation at a single and (III) without gantry angulation at a dual source CT scanner. Eye lens doses calculated by the dose monitoring tool based on MCS and assessed with TLDs were compared. Eye lens doses are summarized as follows: (I) CT angiography (a) MCS 7 mSv, (b) TLD 5 mSv; (II) unenhanced, cranial CT scan with gantry angulation, (c) MCS 45 mSv, (d) TLD 5 mSv; (III) unenhanced, cranial CT scan without gantry angulation (e) MCS 38 mSv, (f) TLD 35 mSv. Intermodality comparison shows an inaccurate calculation of eye lens doses in unenhanced cranial CT protocols at the single source CT scanner due to the disregard of gantry angulation. On the contrary, the dose monitoring tool showed an accurate calculation of eye lens doses at the dual source CT scanner without gantry angulation and for CT angiography examinations. The dose monitoring software tool based on MCS gave accurate estimates of eye lens doses in cranial CT protocols. However, knowledge of protocol and software specific influences is crucial for correct assessment of eye lens doses in routine clinical use. (orig.)

Clinical evaluation of a dose monitoring software tool based on Monte Carlo Simulation in assessment of eye lens doses for cranial CT scans

International Nuclear Information System (INIS)

Guberina, Nika; Suntharalingam, Saravanabavaan; Nassenstein, Kai; Forsting, Michael; Theysohn, Jens; Wetter, Axel; Ringelstein, Adrian

2016-01-01

The aim of this study was to verify the results of a dose monitoring software tool based on Monte Carlo Simulation (MCS) in assessment of eye lens doses for cranial CT scans. In cooperation with the Federal Office for Radiation Protection (Neuherberg, Germany), phantom measurements were performed with thermoluminescence dosimeters (TLD LiF:Mg,Ti) using cranial CT protocols: (I) CT angiography; (II) unenhanced, cranial CT scans with gantry angulation at a single and (III) without gantry angulation at a dual source CT scanner. Eye lens doses calculated by the dose monitoring tool based on MCS and assessed with TLDs were compared. Eye lens doses are summarized as follows: (I) CT angiography (a) MCS 7 mSv, (b) TLD 5 mSv; (II) unenhanced, cranial CT scan with gantry angulation, (c) MCS 45 mSv, (d) TLD 5 mSv; (III) unenhanced, cranial CT scan without gantry angulation (e) MCS 38 mSv, (f) TLD 35 mSv. Intermodality comparison shows an inaccurate calculation of eye lens doses in unenhanced cranial CT protocols at the single source CT scanner due to the disregard of gantry angulation. On the contrary, the dose monitoring tool showed an accurate calculation of eye lens doses at the dual source CT scanner without gantry angulation and for CT angiography examinations. The dose monitoring software tool based on MCS gave accurate estimates of eye lens doses in cranial CT protocols. However, knowledge of protocol and software specific influences is crucial for correct assessment of eye lens doses in routine clinical use. (orig.)

Extent of hypoattenuation on CT angiography source images in basilar artery occlusion: prognostic value in the Basilar Artery International Cooperation Study.

Science.gov (United States)

Puetz, Volker; Khomenko, Andrei; Hill, Michael D; Dzialowski, Imanuel; Michel, Patrik; Weimar, Christian; Wijman, Christine A C; Mattle, Heinrich P; Engelter, Stefan T; Muir, Keith W; Pfefferkorn, Thomas; Tanne, David; Szabo, Kristina; Kappelle, L Jaap; Algra, Ale; von Kummer, Ruediger; Demchuk, Andrew M; Schonewille, Wouter J

2011-12-01

The posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) quantifies the extent of early ischemic changes in the posterior circulation with a 10-point grading system. We hypothesized that pc-ASPECTS applied to CT angiography source images predicts functional outcome of patients in the Basilar Artery International Cooperation Study (BASICS). BASICS was a prospective, observational registry of consecutive patients with acute symptomatic basilar artery occlusion. Functional outcome was assessed at 1 month. We applied pc-ASPECTS to CT angiography source images of patients with CT angiography for confirmation of basilar artery occlusion. We calculated unadjusted and adjusted risk ratios (RRs) of pc-ASPECTS dichotomized at ≥8 versus <8. Primary outcome measure was favorable outcome (modified Rankin Scale scores 0-3). Secondary outcome measures were mortality and functional independence (modified Rankin Scale scores 0-2). Of 158 patients included, 78 patients had a CT angiography source images pc-ASPECTS≥8. Patients with a pc-ASPECTS≥8 more often had a favorable outcome than patients with a pc-ASPECTS<8 (crude RR, 1.7; 95% CI, 0.98-3.0). After adjustment for age, baseline National Institutes of Health Stroke Scale score, and thrombolysis, pc-ASPECTS≥8 was not related to favorable outcome (RR, 1.3; 95% CI, 0.8-2.2), but it was related to reduced mortality (RR, 0.7; 95% CI, 0.5-0.98) and functional independence (RR, 2.0; 95% CI, 1.1-3.8). In post hoc analysis, pc-ASPECTS dichotomized at ≥6 versus <6 predicted a favorable outcome (adjusted RR, 3.1; 95% CI, 1.2-7.5). pc-ASPECTS on CT angiography source images independently predicted death and functional independence at 1 month in the CT angiography subgroup of patients in the BASICS registry.

Abdominal and Pelvic CT

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ... preferable over CT scanning. top of page Additional Information and Resources RTAnswers.org: Radiation Therapy for Bladder ...

A singly charged ion source for radioactive 11C ion acceleration

Science.gov (United States)

Katagiri, K.; Noda, A.; Nagatsu, K.; Nakao, M.; Hojo, S.; Muramatsu, M.; Suzuki, K.; Wakui, T.; Noda, K.

2016-02-01

A new singly charged ion source using electron impact ionization has been developed to realize an isotope separation on-line system for simultaneous positron emission tomography imaging and heavy-ion cancer therapy using radioactive 11C ion beams. Low-energy electron beams are used in the electron impact ion source to produce singly charged ions. Ionization efficiency was calculated in order to decide the geometric parameters of the ion source and to determine the required electron emission current for obtaining high ionization efficiency. Based on these considerations, the singly charged ion source was designed and fabricated. In testing, the fabricated ion source was found to have favorable performance as a singly charged ion source.

The completeness condition and source orbits for exact image reconstruction in 3D cone-beam CT

International Nuclear Information System (INIS)

Mao Xiping; Kang Kejun

1997-01-01

The completeness condition for exact image reconstruction in 3D cone-beam CT are carefully analyzed in theory, and discussions about some source orbits which fulfill the completeness condition are followed

A novel high-efficiency single-mode quantum dot single photon source

DEFF Research Database (Denmark)

Gerard, J.M.; Gregersen, Niels; Nielsen, Torben Roland

2008-01-01

We present a novel single-mode single photon source exploiting the emission of a semiconductor quantum dot (QD) located inside a photonic wire. Besides an excellent coupling (>95%) of QD spontaneous emission to the fundamental guided mode [1], we show that a single photon collection efficiency...... above 80% within a 0.5 numerical aperture can be achieved using a bottom Bragg mirror and a tapering of the nanowire tip. Because this photon collection strategy does not exploit the Purcell effect, it could also be efficiently applied to broadband single photon emitters such as F-centers in diamond....

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

Radiation exposure in multi-slice versus single-slice spiral CT: results of a nationwide survey

International Nuclear Information System (INIS)

Brix, G.; Nagel, H.D.; Stamm, G.; Veit, R.; Lechel, U.; Griebel, J.; Galanski, M.

2003-01-01

Multi-slice (MS) technology increases the efficacy of CT procedures and offers new promising applications. The expanding use of MSCT, however, may result in an increase in both frequency of procedures and levels of patient exposure. It was, therefore, the aim of this study to gain an overview of MSCT examinations conducted in Germany in 2001. All MSCT facilities were requested to provide information about 14 standard examinations with respect to scan parameters and frequency. Based on this data, dosimetric quantities were estimated using an experimentally validated formalism. Results are compared with those of a previous survey for single-slice (SS) spiral CT scanners. According to the data provided for 39 dual- and 73 quad-slice systems, the average annual number of patients examined at MSCT is markedly higher than that examined at SSCT scanners (5500 vs 3500). The average effective dose to patients was changed from 7.4 mSv at single-slice to 5.5 mSv and 8.1 mSv at dual- and quad-slice scanners, respectively. There is a considerable potential for dose reduction at quad-slice systems by an optimisation of scan protocols and better education of the personnel. To avoid an increase in the collective effective dose from CT procedures, a clear medical justification is required in each case. (orig.)

Single-channel source separation using non-negative matrix factorization

DEFF Research Database (Denmark)

Schmidt, Mikkel Nørgaard

-determined and its solution relies on making appropriate assumptions concerning the sources. This dissertation is concerned with model-based probabilistic single-channel source separation based on non-negative matrix factorization, and consists of two parts: i) three introductory chapters and ii) five published...... papers. The first part introduces the single-channel source separation problem as well as non-negative matrix factorization and provides a comprehensive review of existing approaches, applications, and practical algorithms. This serves to provide context for the second part, the published papers......, in which a number of methods for single-channel source separation based on non-negative matrix factorization are presented. In the papers, the methods are applied to separating audio signals such as speech and musical instruments and separating different types of tissue in chemical shift imaging....

Single channel blind source separation based on ICA feature extraction

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

A new technique is proposed to solve the blind source separation (BSS) given only a single channel observation. The basis functions and the density of the coefficients of source signals learned by ICA are used as the prior knowledge. Based on the learned prior information the learning rules of single channel BSS are presented by maximizing the joint log likelihood of the mixed sources to obtain source signals from single observation,in which the posterior density of the given measurements is maximized. The experimental results exhibit a successful separation performance for mixtures of speech and music signals.

MDCT of acute pancreatitis: Intraindividual comparison of single-phase versus dual-phase MDCT for initial assessment of acute pancreatitis using different CT scoring systems

Energy Technology Data Exchange (ETDEWEB)

Avanesov, Maxim, E-mail: m.avanesov@uke.de [Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Hamburg (Germany); Weinrich, Julius M.; Kraus, Thomas [Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Hamburg (Germany); Derlin, Thorsten [Department of Nuclear Medicine, Hannover Medical School (Germany); Adam, Gerhard; Yamamura, Jin [Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Hamburg (Germany); Karul, Murat [Department of Diagnostic and Interventional Radiology, Marienkrankenhaus Hamburg (Germany)

2016-11-15

Objectives: The purpose of the retrospective study was to evaluate the additional value of dual-phase multidetector computed tomography (MDCT) protocols over a single-phase protocol on initial MDCT in patients with acute pancreatitis using three CT-based pancreatitis severity scores with regard to radiation dose. Methods: In this retrospective, IRB approved study MDCT was performed in 102 consecutive patients (73 males; 55years, IQR48–64) with acute pancreatitis. Inclusion criteria were CT findings of interstitial edematous pancreatitis (IP) or necrotizing pancreatitis (NP) and a contrast-enhanced dual-phase (arterial phase and portal-venous phase) abdominal CT performed at ≥72 h after onset of symptoms. The severity of pancreatic and extrapancreatic changes was independently assessed by 2 observers using 3 validated CT-based scoring systems (CTSI, mCTSI, EPIC). All scores were applied to arterial phase and portal venous phase scans and compared to score results of portal venous phase scans, assessed ≥14 days after initial evaluation. For effective dose estimation, volume CT dose index (CTDIvol) and dose length product (DLP) were recorded in all examinations. Results: In neither of the CT severity scores a significant difference was observed after application of a dual-phase protocol compared with a single-phase protocol (IP: CTSI: 2.7 vs. 2.5, p = 0.25; mCTSI: 4.0 vs. 4.0, p = 0.10; EPIC: 2.0 vs. 2.0, p = 0.41; NP: CTSI: 8.0 vs. 7.0, p = 0.64; mCTSI: 8.0 vs. 8.0, p = 0.10; EPIC: 3.0 vs. 3.0, p = 0.06). The application of a single-phase CT protocol was associated with a median effective dose reduction of 36% (mean dose reduction 31%) compared to a dual-phase CT scan. Conclusions: An initial dual-phase abdominal CT after ≥72 h after onset of symptoms of acute pancreatitis was not superior to a single-phase protocol for evaluation of the severity of pancreatic and extrapancreatic changes. However, the effective radiation dose may be reduced by 36% using a

Protecting single-photon entanglement with practical entanglement source

Science.gov (United States)

Zhou, Lan; Ou-Yang, Yang; Wang, Lei; Sheng, Yu-Bo

2017-06-01

Single-photon entanglement (SPE) is important for quantum communication and quantum information processing. However, SPE is sensitive to photon loss. In this paper, we discuss a linear optical amplification protocol for protecting SPE. Different from the previous protocols, we exploit the practical spontaneous parametric down-conversion (SPDC) source to realize the amplification, for the ideal entanglement source is unavailable in current quantum technology. Moreover, we prove that the amplification using the entanglement generated from SPDC source as auxiliary is better than the amplification assisted with single photons. The reason is that the vacuum state from SPDC source will not affect the amplification, so that it can be eliminated automatically. This protocol may be useful in future long-distance quantum communications.

Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT

Energy Technology Data Exchange (ETDEWEB)

Xu, Lei; Yang, Lin; Zhang, Zhaoqi [Capital Medical University, Department of Radiology, Beijing Anzhen Hospital, Beijing (China); Wang, Yining; Jin, Zhengyu [Chinese Academy of Medical Sciences, Department of Radiology, Peking Union Medical College Hospital, Beijing (China); Zhang, Longjiang; Lu, Guangming [Nanjing University, Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing, Jiangsu (China)

2013-07-15

To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol. 100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated. Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P < 0.001). Effective dose was 4.29 {+-} 1.86 and 11.95 {+-} 5.34 mSv for each of the two protocols (P < 0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging. In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality. (orig.)

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.)

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.)

SU-E-T-70: Commissioning a Multislice CT Scanner for X-Ray CT Polymer Gel Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Johnston, H [University of Victoria, Victoria, BC (Australia); UT Southwestern Medical Center, Dallas, TX (United States); Hilts, M [University of Victoria, Victoria, BC (Australia); BC Cancer Agency, Kelowna, BC (Australia); Jirasek, A [University of Victoria, Victoria, BC (Australia)

2014-06-01

Purpose: To commission a multislice computed tomography (CT) scanner for fast and reliable readout of radiation therapy (RT) dose distributions using CT polymer gel dosimetry (PGD). Methods: Commissioning was performed for a 16-slice CT scanner using images acquired through a 1L cylinder filled with water. Additional images were collected using a single slice machine for comparison purposes. The variability in CT number associated with the anode heel effect was evaluated and used to define a new slice-by-slice background image subtraction technique. Image quality was assessed for the multislice system by comparing image noise and uniformity to that of the single slice machine. The consistency in CT number across slices acquired simultaneously using the multislice detector array was also evaluated. Finally, the variability in CT number due to increasing x-ray tube load was measured for the multislice scanner and compared to the tube load effects observed on the single slice machine. Results: Slice-by-slice background subtraction effectively removes the variability in CT number across images acquired simultaneously using the multislice scanner and is the recommended background subtraction method when using a multislice CT system. Image quality for the multislice machine was found to be comparable to that of the single slice scanner. Further study showed CT number was consistent across image slices acquired simultaneously using the multislice detector array for each detector configuration of the slice thickness examined. In addition, the multislice system was found to eliminate variations in CT number due to increasing x-ray tube load and reduce scanning time by a factor of 4 when compared to imaging a large volume using a single slice scanner. Conclusion: A multislice CT scanner has been commissioning for CT PGD, allowing images of an entire dose distribution to be acquired in a matter of minutes. Funding support provided by the Natural Sciences and Engineering

Comparison of scatter doses from a multislice and a single slice CT scanner

International Nuclear Information System (INIS)

Burrage, J. W.; Causer, D. A.

2006-01-01

During shielding calculations for a new multislice CT (MSCT) scanner it was found that the manufacturer's data indicated significantly higher external scatter doses than would be generated for a single slice CT (SSCT). Even allowing for increased beam width, the manufacturer's data indicated that the scatter dose per scan was higher by a factor of about 3 to 4. The magnitude of the discrepancy was contrary to expectations and also contrary to a statement by the UK ImPACT group, which indicated that when beam width is taken into account, the scatter doses should be similar. The matter was investigated by comparing scatter doses from an SSCT and an MSCT. Scatter measurements were performed at three points using a standard perspex CTDI phantom, and CT dose indices were also measured to compare scanner output. MSCT measurements were performed with a 40 mm wide beam, SSCT measurements with a 10 mm wide beam. A film badge survey was also performed after the installation of the MSCT scanner to assess the adequacy of lead shielding in the room. It was found that the scatter doses from the MSCT were lower than indicated by the manufacturer's data. MSCT scatter doses were approximately 4 times higher than those from the SSCT, consistent with expectations due to beam width differences. The CT dose indices were similar, and the film badge survey indicated that the existing shielding, which had been adequate for the SSCT, was also adequate for the MSCT

Equivalent properties of single event burnout induced by different sources

International Nuclear Information System (INIS)

Yang Shiyu; Cao Zhou; Da Daoan; Xue Yuxiong

2009-01-01

The experimental results of single event burnout induced by heavy ions and 252 Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252 Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the 'turn-off' state is more susceptible to single event burnout than it is in the 'turn-on' state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and 252 Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout. (authors)

Micro-CT and nano-CT analysis of filling quality of three different endodontic sealers.

Science.gov (United States)

Huang, Yan; Celikten, Berkan; de Faria Vasconcelos, Karla; Ferreira Pinheiro Nicolielo, Laura; Lippiatt, Nicholas; Buyuksungur, Arda; Jacobs, Reinhilde; Orhan, Kaan

2017-12-01

To investigate voids in different root canal sealers using micro-CT and nano-CT, and to explore the feasibility of using nano-CT for quantitative analysis of sealer filling quality. 30 extracted mandibular central incisors were randomly assigned into three groups according to the applied root canal sealers (Total BC Sealer, Sure Seal Root, AH Plus) by the single cone technique. Subsequently, micro-CT and nano-CT were performed to analyse the incidence rate of voids, void fraction, void volume and their distribution in each sample. Micro-CT evaluation showed no significant difference among sealers for the incidence rate of voids or void fraction in the whole filling materials (p > 0.05), whereas a significant difference was found between AH Plus and the other two sealers using nano-CT (p nano-CT results displayed higher void volume in AH Plus among all the sealers and regions (p nano-CT analysis, when round root canals were treated by the single cone technique. The disparate results suggest that the higher resolution of nano-CT have a greater ability of distinguishing internal porosity, and therefore suggesting the potential use of nano-CT in quantitative analysis of filling quality of sealers.

Equitable Prices of Single-Source Drugs in Thailand.

Science.gov (United States)

Ngorsuraches, Surachat; Chaiyakan, Kanokkan

2015-08-01

In Thailand, total drug expenditure has grown rapidly. Recently, the Thai government has addressed the issue of drug pricing, but the prices of single-source drugs remain a major challenge. To examine equitable prices of single-source drugs in Thailand. A total of 98 single-source and high-expenditure drugs were examined. Unit prices from the Drug and Medical Supplies Information Center (DMSIC) and National Average Drug Acquisition Cost (NADAC) were used to represent drug prices at the provider level in Thailand and the U.S., respectively. Data for measuring drug affordability, e.g., dose and poverty line, were obtained from Micromedex online and the National Statistical Office (NSO). The U.S. drug prices were adjusted by the Human Development Index (HDI) to be equitable prices for Thailand. Purchasing Power Parity (PPP) was used to convert US currency into Thai baht. All prices in this study were based on the year 2012. Catastrophic, Impoverishment, and WHO/Health Action International (HAI) approaches were used to determine Thai citizens' ability to afford the study drugs. Finally, uncertainty analyses were conducted. From all study drugs, 55 single-source drugs were priced higher than their equitable prices, ranging from 0.38 to 422.36% higher. Among these, 28 items were antineoplastic drugs. The prices of drugs outside the National List of Essential Medicines (NLEM), as well as the country's newer drugs, tended to be higher than their calculated equitable prices. The majority of drugs in Thailand priced higher than equitable prices were unaffordable for most Thai citizens. The uncertainty analyses revealed that almost all results were relatively robust. Most single-source drug prices in Thailand were higher than their equitable prices, and were likely to be unaffordable to Thai citizens.

Children's (Pediatric) CT (Computed Tomography)

Medline Plus

Full Text Available ... view of the body's interior. Refinements in detector technology allow new CT scanners to obtain multiple slices in a single rotation. These scanners, called "multislice CT" or "multidetector CT," ...

Evaluation of Rib Fractures on a Single-in-plane Image Reformation of the Rib Cage in CT Examinations.

Science.gov (United States)

Dankerl, Peter; Seuss, Hannes; Ellmann, Stephan; Cavallaro, Alexander; Uder, Michael; Hammon, Matthias

2017-02-01

This study aimed to evaluate the diagnostic performance of using a reformatted single-in-plane image reformation of the rib cage for the detection of rib fractures in computed tomography (CT) examinations, employing different levels of radiological experience. We retrospectively evaluated 10 consecutive patients with and 10 patients without rib fractures, whose CT scans were reformatted to a single-in-plane image reformation of the rib cage. Eight readers (two radiologists, two residents in radiology, and four interns) independently evaluated the images for the presence of rib fractures using a reformatted single-in-plane image and a multi-planar image reformation. The time limit was 30 seconds for each read. A consensus of two radiologist readings was considered as the reference standard. Diagnostic performance (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]) was assessed and evaluated per rib and per location (anterior, lateral, posterior). To determine the time limit, we prospectively analyzed the average time it took radiologists to assess the rib cage, in a bone window setting, in 50 routine CT examinations. McNemar test was used to compare the diagnostic performances. Single image reformation was successful in all 20 patients. The sensitivity, specificity, PPV, and NPV for the detection of rib fractures using the conventional multi-planar read were 77.5%, 99.2%, 89.9%, and 98.0% for radiologists; 46.3%, 99.7%, 92.5%, and 95.3% for residents; and 29.4%, 99.4%, 82.5%, and 93.9% for interns, respectively. Sensitivity, PPV, and NPV increased across all three groups of experience, using the reformatted single-in-plane image of the rib cage (radiologists: 85.0%, 98.6%, and 98.7%; residents: 80.0%, 92.8%, and 98.2%; interns: 66.9%, 89.9%, and 97.1%), whereas specificity did not change significantly (99.9%, 99.4%, and 99.3%). The diagnostic performance of the interns and residents was significantly better when

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

Multi-slice and dual-source CT in cardiac imaging. Principles - protocols - indications - outlook. 2. ed.

International Nuclear Information System (INIS)

Ohnesorge, B.M.; Flohr, T.G.; Becker, C.R.; Reiser, M.F.; Knez, A

2007-01-01

Cardiac diseases, and in particular coronary artery disease, are the leading cause of death and morbidity in industrialized countries. The development of non-invasive imaging techniques for the heart and the coronary arteries has been considered a key element in improving patient care. A breakthrough in cardiac imaging using CT occurred in 1998, with the introduction of multi-slice computed tomography (CT). Since then, amazing advances in performance have taken place with scanners that acquire up to 64 slices per rotation. This book discusses the state-of-the-art developments in multi-slice CT for cardiac imaging as well as those that can be anticipated in the future. It serves as a comprehensive work that covers all aspects of this technology, from the technical fundamentals and image evaluation all the way to clinical indications and protocol recommendations. This fully reworked second edition draws on the most recent clinical experience obtained with 16- and 64-slice CT scanners by world-leading experts from Europe and the United States. It also includes ''hands-on'' experience in the form of 10 representative clinical case studies, which are included on the accompanying CD. As a further highlight, the latest results of the very recently introduced dual-source CT, which may soon represent the CT technology of choice for cardiac applications, are presented. This book will not only convince the reader that multi-slice cardiac CT has arrived in clinical practice, it will also make a significant contribution to the education of radiologists, cardiologists, technologists, and physicists-whether newcomers, experienced users, or researchers. (orig.)

Comparison of 68Ga-DOTANOC PET/CT and contrast-enhanced CT in localisation of tumours in ectopic ACTH syndrome

Science.gov (United States)

Jadhav, Swati S; Lila, Anurag R; Kasaliwal, Rajeev; Khare, Shruti; Yerawar, Chaitanya G; Hira, Priya; Phadke, Uday; Shah, Hina; Lele, Vikram R; Malhotra, Gaurav; Bandgar, Tushar; Shah, Nalini S

2016-01-01

Background Localising ectopic adrenocorticotrophic hormone (ACTH) syndrome (EAS) tumour source is challenging. Somatostatin receptor-based PET imaging has shown promising results, but the data is limited to case reports and small case series. We reviewed here the performance of 68Ga-DOTANOC positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced CT (CECT) in our cohort of 12 consecutive EAS patients. Materials and methods Retrospective data analysis of 12 consecutive patients of EAS presenting to a single tertiary care centre in a period between January 2013 and December 2014 was done. CECT and 68Ga-DOTANOC PET/CT were reported (blinded) by an experienced radiologist and a nuclear medicine physician, respectively. The performance of CECT and 68Ga-DOTANOC PET/CT was compared. Results Tumours could be localised in 11 out of 12 patients at initial presentation (overt cases), whereas in one patient, tumour remained occult. Thirteen lesions were identified in 11 patients as EAS source (true positives). CECT localised 12 out of these 13 lesions (sensitivity 92.3%) and identified five false-positive lesions (positive predictive value (PPV) 70.5%). Compared with false-positive lesions, true-positive lesions had greater mean contrast enhancement at 60s (33.2 vs 5.6 Hounsfield units (HU)). 68Ga-DOTANOC PET/CT was able to identify 9 out of 13 lesions (sensitivity 69.2%) and reported no false-positive lesions (PPV 100%). Conclusion CECT remains the first-line investigation in localisation of EAS. The contrast enhancement pattern on CECT can further aid in characterisation of the lesions. 68Ga-DOTANOC PET/CT can be added to CECT, to enhance positive prediction of the suggestive lesions. PMID:27006371

A prospective study about an imaging quality of low dosage of contrast media with single-detector CT

International Nuclear Information System (INIS)

Saku, Madoka

2004-01-01

The steadily elevating cost of the contrast-enhanced CT has been a problem in last decade. One approach to curtail the cost is to reduce the amount of contrast media (CM). The purpose of this study was to examine the possibility of reducing the volume of CM in single-detector CT (SDCT) without compromising diagnostic ability. One hundred ml of Iohexol 300 and 75 ml of Ioversol 320 were compared in a prospective CT study about their imaging quality. One hundred patients were randomly divided into two parallel groups (A and B). The former agent was used for group A and the latter for B. CT attenuations of the aorta, central vein, spleen and kidney were measured and each imaging quality was reviewed by three radiologists. CT attenuations and the imaging quality were significantly superior (p<0.05) in A group, however, comparing in the condition under 50 kg patients, they showed no significant differences and the quality was tolerable for diagnosis in both group. This demonstrates the difficulty to perform the high-quality CT with a reduced CM in SDCT. However, this does not negate the diagnostic ability of low dose of CM, but reflects the importance of determining the acceptable lowest doze of CM for diagnosis. (author)

High-quality asynchronous heralded single-photon source at telecom wavelength

International Nuclear Information System (INIS)

Fasel, Sylvain; Alibart, Olivier; Tanzilli, Sebastien; Baldi, Pascal; Beveratos, Alexios; Gisin, Nicolas; Zbinden, Hugo

2004-01-01

We report on the experimental realization and characterization of an asynchronous heralded single-photon source based on spontaneous parametric down-conversion. Photons at 1550 nm are heralded as being inside a single-mode fibre with more than 60% probability, and the multi-photon emission probability is reduced by a factor of up to more than 500 compared to Poissonian light sources. These figures of merit, together with the choice of telecom wavelength for the heralded photons, are compatible with practical applications needing very efficient and robust single-photon sources

Dual-source virtual non-contrast CT of the head: a preliminary study

International Nuclear Information System (INIS)

Huang Wei; Xu Yiming; Shao Jin

2011-01-01

Objective: To investigate image quality and clinical value of dual-source dual energy virtual non-contrast (VNC) CT of the head. Methods: Sixty-two patients suspected of cerebrovascular diseases underwent conventional non-contrast (CNC) CT and dual energy CTA examination of the head with dual-source CT. Virtual non-contrast images were reconstructed using dual energy software. The CT values of gray matter, white matter, cerebrospinal fluid, hyperdense hemorrhagic lesion and hypodense ischemic lesion were compared between CNC and VNC images. A four-score scale was used to assess image quality subjectively. Image noise, radiation dosage and detection rate were compared between CNC and VNC images. Paired t test, Wilcoxon signed ranks test and Chi-square test (McNemar test and Kappa test) were used. Results: The CT value on CNC and VNC images, were (43.3±1.5) and (33.2±1.3) HU for gray matter (t=46.98, P 0.05, Kappa = 1.000) at per-patient level. Twenty-two patients with hypodense ischemic lesions were found on VNC images with one false positive case and two false negative cases. The sensitivity, specificity, positive predictive value and negative predictive value were 91.3% (21/23), 97.4% (38/39), 95.5% (21/22) and 95.0% (38/40) respectively. No statistical difference was found in detecting hypodense lesions between VNC and CNC images (χ 2 = 0.00, P>0.05, Kappa = 0.895). In per-lesion analysis, 53 hemorrhage lesions were found on VNC images with false negative results of four lesions and no false positive result. The sensitivity, specificity, positive predictive value and negative predictive value were 93.0% (53/57). 100.0% (38/38), 100.0% (53/.53) and 90.5% (38/42) respectively. There was no significant difference in detection rate of hyperdense lesion between VNC and CNC images (χ 2 = 2.25, P>0.05, Kappa = 0.914). Thirty-eight hypodense lesions were found on VNC images with 2 false positive lesions and 13 false negative lesions. The sensitivity, specificity

Low-dose computed tomography of the paranasal sinus and facial skull using a high-pitch dual-source system - First clinical results

International Nuclear Information System (INIS)

Schell, Boris; Bauer, Ralf W.; Lehnert, Thomas; Kerl, J.M.; Vogl, Thomas J.; Mack, Martin G.; Hambek, Markus; May, Angelika

2011-01-01

Computed tomography (CT) of the paranasal sinus is the standard diagnostic tool for a wide range of indications in mostly younger patients. This study aims to assess the image quality of CT of the sinus by using a high-pitch dual-source technique with special regard to the radiation dose. Examinations were performed on a second-generation dual-source CT with a pitch factor of 3.0 (dual-source mode). Images were compared with those with a pitch factor of 0.9 on the same system (single-source mode) and with those of 16-slice CT. Image quality was evaluated by four blinded readers using a 5-point scale (1 = poor, 5 = excellent). Comparison of the dose length product (DLP) was used to estimate radiation exposure. Seventy-three consecutive patients underwent imaging with the proposed CT protocols. The viewers rated the image quality of the dual-source image sets as nearly as good (3.62) as the single-source images on the same device (4.18) and those on 16-slice CT (3.7). DLP was cut to half of the dose [51 mGycm vs. 97.8 mGycm vs. 116.9 mGycm (p < 0.01)]. Using the proposed dual-source mode when examining the paranasal sinus, diagnostic image quality can be achieved while drastically lowering the patient's radiation exposure. (orig.)

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.

Improved assessment of mediastinal and pulmonary pathologies in combined staging CT examinations using a fast-speed acquisition dual-source CT protocol

Energy Technology Data Exchange (ETDEWEB)

Braun, Franziska M.; Holzner, Veronica; Meinel, Felix G.; Armbruster, Marco; Brandlhuber, Martina; Ertl-Wagner, Birgit; Sommer, Wieland H. [University Hospital Munich, Institute for Clinical Radiology, Munich (Germany)

2017-12-15

To demonstrate the feasibility of fast Dual-Source CT (DSCT) and to evaluate the clinical utility in chest/abdomen/pelvis staging CT studies. 45 cancer patients with two follow-up combined chest/abdomen/pelvis staging CT examinations (maximally ±10 kV difference in tube potential) were included. The first scan had to be performed with our standard protocol (fixed pitch 0.6), the second one using a novel fast-speed DSCT protocol (fixed pitch 1.55). Effective doses (ED) were calculated, noise measurements performed. Scan times were compared, motion artefacts and the diagnostic confidence rated in consensus reading. ED for the standard and fast-speed scans was 9.1 (7.0-11.1) mSv and 9.2 (7.4-12.8) mSv, respectively (P = 0.075). Image noise was comparable (abdomen; all P > 0.05) or reduced for fast-speed CTs (trachea, P = 0.001; ascending aorta, P < 0.001). Motion artefacts of the heart/the ascending aorta (all P < 0.001) and breathing artefacts (P < 0.031) were reduced in fast DSCT. The diagnostic confidence for the evaluation of mediastinal (P < 0.001) and pulmonary (P = 0.008) pathologies was improved for fast DSCT. Fast DSCT for chest/abdomen/pelvis staging CT examinations is performed within 2 seconds scan time and eliminates relevant intrathoracic motion/breathing artefacts. Mediastinal/pulmonary pathologies can thus be assessed with high diagnostic confidence. Abdominal image quality remains excellent. (orig.)

Improved quantification in single-pinhole and multiple-pinhole SPECT using micro-CT information

International Nuclear Information System (INIS)

Vanhove, Christian; Bossuyt, Axel; Defrise, Michel; Lahoutte, Tony

2009-01-01

The purpose of this study was to demonstrate the feasibility of accurate quantification in pinhole SPECT using micro-CT information. Pinhole SPECT scans were performed using a clinical dual-head gamma camera. Each pinhole SPECT scan was followed by a micro-CT acquisition. Functional and anatomical images were coregistered using six point sources visible with both modalities. Pinhole SPECT images were reconstructed iteratively. Attenuation correction was based on micro-CT information. Scatter correction was based on dual and triple-energy window methods. Phantom and animal experiments were performed. A phantom containing nine vials was filled with different concentrations of 99m Tc. Three vials were also filled with CT contrast agent to increase attenuation. Activity concentrations measured on the pinhole SPECT images were compared with activity concentrations measured by the dose calibrator. In addition, 11 mice were injected with 99m Tc-labelled Nanobodies. After acquiring functional and anatomical images, the animals were killed and the liver activity was measured using a gamma-counter. Activity concentrations measured on the reconstructed images were compared with activity concentrations measured with the gamma counter. The phantom experiments demonstrated an average error of -27.3 ± 15.9% between the activity concentrations measured on the uncorrected pinhole SPECT images and in the dose calibrator. This error decreased significantly to -0.1 ± 7.3% when corrections were applied for nonuniform attenuation and scatter. The animal experiment revealed an average error of -18.4 ± 11.9% between the activity concentrations measured on the uncorrected pinhole SPECT images and measured with the gamma counter. This error decreased to -7.9 ± 10.4% when attenuation and scatter correction was applied. Attenuation correction obtained from micro-CT data in combination with scatter correction allows accurate quantification in pinhole SPECT. (orig.)

Evaluation of mechanical precision and alignment uncertainties for an integrated CT/LINAC system

International Nuclear Information System (INIS)

Court, Laurence; Rosen, Isaac; Mohan, Radhe; Dong Lei

2003-01-01

A new integrated CT/LINAC combination, in which the CT scanner is inside the radiation therapy treatment room and the same patient couch is used for CT scanning and treatment (after a 180-degree couch rotation), should allow for accurate correction of interfractional setup errors. The purpose of this study was to evaluate the sources of uncertainties, and to measure the overall precision of this system. The following sources of uncertainty were identified: (1) the patient couch position on the LINAC side after a rotation, (2) the patient couch position on the CT side after a rotation, (3) the patient couch position as indicated by its digital readout, (4) the difference in couch sag between the CT and LINAC positions, (5) the precision of the CT coordinates, (6) the identification of fiducial markers from CT images, (7) the alignment of contours with structures in the CT images, and (8) the alignment with setup lasers. The largest single uncertainties (one standard deviation or 1 SD) were found in couch position on the CT side after a rotation (0.5 mm in the RL direction) and the alignment of contours with the CT images (0.4 mm in the SI direction). All other sources of uncertainty are less than 0.3 mm (1 SD). The overall precision of two setup protocols was investigated in a controlled phantom study. A protocol that relies heavily on the mechanical integrity of the system, and assumes a fixed relationship between the LINAC isocenter and the CT images, gave a predicted precision (1 SD) of 0.6, 0.7, and 0.6 mm in the SI, RL and AP directions, respectively. The second protocol reduces reliance on the mechanical precision of the total system, particularly the patient couch, by using radio-opaque fiducial markers to transfer the isocenter information from the LINAC side to the CT images. This protocol gave a slightly improved predicted precision of 0.5, 0.4, and 0.4 mm in the SI, RL and AP directions, respectively. The distribution of phantom position after CT

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.)

Multi-photon absorption limits to heralded single photon sources

Science.gov (United States)

Husko, Chad A.; Clark, Alex S.; Collins, Matthew J.; De Rossi, Alfredo; Combrié, Sylvain; Lehoucq, Gaëlle; Rey, Isabella H.; Krauss, Thomas F.; Xiong, Chunle; Eggleton, Benjamin J.

2013-01-01

Single photons are of paramount importance to future quantum technologies, including quantum communication and computation. Nonlinear photonic devices using parametric processes offer a straightforward route to generating photons, however additional nonlinear processes may come into play and interfere with these sources. Here we analyse spontaneous four-wave mixing (SFWM) sources in the presence of multi-photon processes. We conduct experiments in silicon and gallium indium phosphide photonic crystal waveguides which display inherently different nonlinear absorption processes, namely two-photon (TPA) and three-photon absorption (ThPA), respectively. We develop a novel model capturing these diverse effects which is in excellent quantitative agreement with measurements of brightness, coincidence-to-accidental ratio (CAR) and second-order correlation function g(2)(0), showing that TPA imposes an intrinsic limit on heralded single photon sources. We build on these observations to devise a new metric, the quantum utility (QMU), enabling further optimisation of single photon sources. PMID:24186400

Cerebral angiography with prospective ECG triggering preliminary study of dual-source CT

International Nuclear Information System (INIS)

Xue Yuejun; Qian Nong; Shao Yanhui; Pan Changjie; Rong Weiliang; Xu Yiqun

2012-01-01

Objective: To study the image quality and radiation dose in dual-source CT cerebral angiography with prospective ECG-triggered sequence mode (step-and-shoot, SAS). Methods: A total of forty-three patients with clinically suspected cerebral vascular disease underwent cerebral CT angiography with prospective ECG-triggering (step-and-shoot, SAS). Data acquisition was at 60% R-R interval of the ECG presentation mode. The post-processing included maximum intensity projection (MIP), multiplanar reformation (MPR) and volume rendering (VR). The CTA image quality, radiation dose and rates of excellent images were evaluated. Results: The CTA image quality score was 4.72 ± 0.50 and 97.7% (42/43) patients had excellent CTA images. The average effective dose of SAS-CTA was (0.22 ± 0.01)mSv, which was lower by 76.31% than that of DE-CTA. Conclusions: Prospective ECG-triggering sequence could be used in cerebral angiography with a significant reduction in radiation dose and diagnostic image quality. (authors)

Single-Photon Source for Quantum Information Based on Single Dye Molecule Fluorescence in Liquid Crystal Host

International Nuclear Information System (INIS)

Lukishova, S.G.; Knox, R.P.; Freivald, P.; McNamara, A.; Boyd, R.W.; Stroud, Jr. C.R.; Schmid, A.W.; Marshall, K.L.

2006-01-01

This paper describes a new application for liquid crystals: quantum information technology. A deterministically polarized single-photon source that efficiently produces photons exhibiting antibunching is a pivotal hardware element in absolutely secure quantum communication. Planar-aligned nematic liquid crystal hosts deterministically align the single dye molecules which produce deterministically polarized single (antibunched) photons. In addition, 1-D photonic bandgap cholesteric liquid crystals will increase single-photon source efficiency. The experiments and challenges in the observation of deterministically polarized fluorescence from single dye molecules in planar-aligned glassy nematic-liquid-crystal oligomer as well as photon antibunching in glassy cholesteric oligomer are described for the first time

Deterministic and Storable Single-Photon Source Based on a Quantum Memory

International Nuclear Information System (INIS)

Chen Shuai; Chen, Y.-A.; Strassel, Thorsten; Zhao Bo; Yuan Zhensheng; Pan Jianwei; Schmiedmayer, Joerg

2006-01-01

A single-photon source is realized with a cold atomic ensemble ( 87 Rb atoms). A single excitation, written in an atomic quantum memory by Raman scattering of a laser pulse, is retrieved deterministically as a single photon at a predetermined time. It is shown that the production rate of single photons can be enhanced considerably by a feedback circuit while the single-photon quality is conserved. Such a single-photon source is well suited for future large-scale realization of quantum communication and linear optical quantum computation

Detection of Airway Anomalies in?Pediatric?Patients with Cardiovascular Anomalies with Low Dose Prospective ECG-Gated Dual-Source CT

OpenAIRE

Jiao, Hui; Xu, Zhuodong; Wu, Lebin; Cheng, Zhaoping; Ji, Xiaopeng; Zhong, Hai; Meng, Chen

2013-01-01

OBJECTIVES: To assess the feasibility of low-dose prospective ECG-gated dual-source CT (DSCT) in detecting airway anomalies in pediatric patients with cardiovascular anomalies compared with flexible tracheobronchoscopy (FTB). METHODS: 33 pediatrics with respiratory symptoms who had been revealed cardiovascular anomalies by transthoracic echocardiography underwent FTB and contrast material-enhanced prospective ECG-triggering CT were enrolled. The study was approved by our institution review bo...

Single-source gamma radiation procedures for improved calibration and measurements in porous media

International Nuclear Information System (INIS)

Oostrom, M.; Hofstee, C.; Dane, H.; Lenhard, R.J.

1998-01-01

When dual-energy gamma radiation systems are employed for measurements in porous media, count rates from both sources are often used to compute parameter values. However, for several applications, the count rates of just one source are insufficient. These applications include the determination of volumetric liquid content values in two-liquid systems and salt concentration values in water-saturated porous media. Single-energy gamma radiation procedures for three applications are described in this paper. Through an error analysis, single-source procedures are shown to reduce the probable error in the determinations considerably. Example calculations and simple column experiments were conducted for each application to compare the performance of the new single-source and standard dual-source methods. In all cases, the single-source methods provided more reliable data than the traditional dual-source methods. In addition, a single-source calibration procedure is proposed to determine incident count rates indirectly. This procedure, which requires packing under saturated conditions, can be used in all single- and dual-source applications and yields accurate porosity and dry bulk density values

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.

High speed imaging of dynamic processes with a switched source x-ray CT system

International Nuclear Information System (INIS)

Thompson, William M; Lionheart, William R B; Morton, Edward J; Cunningham, Mike; Luggar, Russell D

2015-01-01

Conventional x-ray computed tomography (CT) scanners are limited in their scanning speed by the mechanical constraints of their rotating gantries and as such do not provide the necessary temporal resolution for imaging of fast-moving dynamic processes, such as moving fluid flows. The Real Time Tomography (RTT) system is a family of fast cone beam CT scanners which instead use multiple fixed discrete sources and complete rings of detectors in an offset geometry. We demonstrate the potential of this system for use in the imaging of such high speed dynamic processes and give results using simulated and real experimental data. The unusual scanning geometry results in some challenges in image reconstruction, which are overcome using algebraic iterative reconstruction techniques and explicit regularisation. Through the use of a simple temporal regularisation term and by optimising the source firing pattern, we show that temporal resolution of the system may be increased at the expense of spatial resolution, which may be advantageous in some situations. Results are given showing temporal resolution of approximately 500 µs with simulated data and 3 ms with real experimental data. (paper)

Diagnostic accuracy of 128-slice dual-source CT coronary angiography: a randomized comparison of different acquisition protocols

International Nuclear Information System (INIS)

Neefjes, Lisan A.; Kate, Gert-Jan R. ten; Rossi, Alexia; Nieman, Koen; Papadopoulou, Stella L.; Dharampal, Anoeshka S.; Dedic, Admir; Feyter, Pim J. de; Mollet, Nico R.; Genders, Tessa S.S.; Hunink, M.G.M.; Schultz, Carl J.; Weustink, Annick C.; Dijkshoorn, Marcel L.; Straten, Marcel van; Cademartiri, Filippo; Krestin, Gabriel P.

2013-01-01

To compare the diagnostic performance and radiation exposure of 128-slice dual-source CT coronary angiography (CTCA) protocols to detect coronary stenosis with more than 50 % lumen obstruction. We prospectively included 459 symptomatic patients referred for CTCA. Patients were randomized between high-pitch spiral vs. narrow-window sequential CTCA protocols (heart rate below 65 bpm, group A), or between wide-window sequential vs. retrospective spiral protocols (heart rate above 65 bpm, group B). Diagnostic performance of CTCA was compared with quantitative coronary angiography in 267 patients. In group A (231 patients, 146 men, mean heart rate 58 ± 7 bpm), high-pitch spiral CTCA yielded a lower per-segment sensitivity compared to sequential CTCA (89 % vs. 97 %, P = 0.01). Specificity, PPV and NPV were comparable (95 %, 62 %, 99 % vs. 96 %, 73 %, 100 %, P > 0.05) but radiation dose was lower (1.16 ± 0.60 vs. 3.82 ± 1.65 mSv, P 0.05). Radiation dose of sequential CTCA was lower compared to retrospective CTCA (6.12 ± 2.58 vs. 8.13 ± 4.52 mSv, P < 0.001). Diagnostic performance was comparable in both groups. Sequential CTCA should be used in patients with regular heart rates using 128-slice dual-source CT, providing optimal diagnostic accuracy with as low as reasonably achievable (ALARA) radiation dose. circle 128-slice dual-source CT coronary angiography offers several different acquisition protocols. (orig.)

Abdominal and Pelvic CT

Medline Plus

Full Text Available ... CT scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector ... Safety page for more information about radiation dose. Women should always inform their physician and x-ray ...

Computed Tomography (CT) -- Head

Medline Plus

Full Text Available ... CT scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector ... Safety page for more information about radiation dose. Women should always inform their physician and x-ray ...

Computed Tomography (CT) -- Sinuses

Medline Plus

Full Text Available ... CT scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector ... Safety page for more information about radiation dose. Women should always inform their physician and x-ray ...

Computed Tomography (CT) -- Sinuses

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ... prescribed procedure with your doctor, the medical facility staff and/or your insurance provider to get a ...

Computed Tomography (CT) -- Head

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ... prescribed procedure with your doctor, the medical facility staff and/or your insurance provider to get a ...

Abdominal and Pelvic CT

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ... prescribed procedure with your doctor, the medical facility staff and/or your insurance provider to get a ...

Computed Tomography (CT) -- Head

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ... membranes covering the brain. top of page Additional Information and Resources RTAnswers.org Radiation Therapy for Brain ...

Computed Tomography (CT) -- Sinuses

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called multislice CT or multidetector CT, ... for the moving table. top of page Additional Information and Resources RTAnswers.org Radiation Therapy for Head ...

SPECT/CT and pulmonary embolism

DEFF Research Database (Denmark)

Mortensen, Jann; Borgwardt, Henrik Gutte

2014-01-01

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......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...

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

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.

3D Printing of CT Dataset: Validation of an Open Source and Consumer-Available Workflow.

Science.gov (United States)

Bortolotto, Chandra; Eshja, Esmeralda; Peroni, Caterina; Orlandi, Matteo A; Bizzotto, Nicola; Poggi, Paolo

2016-02-01

The broad availability of cheap three-dimensional (3D) printing equipment has raised the need for a thorough analysis on its effects on clinical accuracy. Our aim is to determine whether the accuracy of 3D printing process is affected by the use of a low-budget workflow based on open source software and consumer's commercially available 3D printers. A group of test objects was scanned with a 64-slice computed tomography (CT) in order to build their 3D copies. CT datasets were elaborated using a software chain based on three free and open source software. Objects were printed out with a commercially available 3D printer. Both the 3D copies and the test objects were measured using a digital professional caliper. Overall, the objects' mean absolute difference between test objects and 3D copies is 0.23 mm and the mean relative difference amounts to 0.55 %. Our results demonstrate that the accuracy of 3D printing process remains high despite the use of a low-budget workflow.

Single Photon Sources in Silicon Carbide

International Nuclear Information System (INIS)

Brett Johnson

2014-01-01

Single photon sources in semiconductors are highly sought after as they constitute the building blocks of a diverse range of emerging technologies such as integrated quantum information processing, quantum metrology and quantum photonics. In this presentation, we show the first observation of single photon emission from deep level defects in silicon carbide (SiC). The single photon emission is photo-stable at room temperature and surprisingly bright. This represents an exciting alternative to diamond color centers since SiC possesses well-established growth and device engineering protocols. The defect is assigned to the carbon vacancy-antisite pair which gives rise to the AB photoluminescence lines. We discuss its photo-physical properties and their fabrication via electron irradiation. Preliminary measurements on 3C SiC nano-structures will also be discussed. (author)

Comparison of carotid and cerebrovascular disease between diabetic and non-diabetic patients using dual-source CT

International Nuclear Information System (INIS)

He Ci; Yang Zhigang; Chu Zhigang; Dong Zhihui; Li Yunming; Shao Heng; Deng Wen

2011-01-01

Purpose: To clarify the differences of the carotid and cerebrovascular disease between patients with and without type 2 diabetes using dual-source CT angiography. Materials and methods: Dual-source CT angiography of the carotid and cerebrovascular arteries was performed in 79 type 2 diabetic patients and 207 non-diabetic patients. The type, extent and distribution of plaques, and luminal stenosis were compared. Results: Compared with non-diabetic patients, diabetic patients had a higher overall incidence of plaque (p 0.05), as well as for the number of diseased segments and the distribution of plaques; both mainly involved the bilateral cavernous segment of the internal carotid artery. As for the stenosis, non-obstructive lesions were more common in diabetic patients (p 0.05). Conclusion: Diabetes is associated with a higher incidence of plaque and non-obstructive stenosis. However, no significant differences were observed in the type, extent and distribution of involved plaques between diabetic and non-diabetic patients.

Energy Harvesting Research: The Road from Single Source to Multisource.

Science.gov (United States)

Bai, Yang; Jantunen, Heli; Juuti, Jari

2018-06-07

Energy harvesting technology may be considered an ultimate solution to replace batteries and provide a long-term power supply for wireless sensor networks. Looking back into its research history, individual energy harvesters for the conversion of single energy sources into electricity are developed first, followed by hybrid counterparts designed for use with multiple energy sources. Very recently, the concept of a truly multisource energy harvester built from only a single piece of material as the energy conversion component is proposed. This review, from the aspect of materials and device configurations, explains in detail a wide scope to give an overview of energy harvesting research. It covers single-source devices including solar, thermal, kinetic and other types of energy harvesters, hybrid energy harvesting configurations for both single and multiple energy sources and single material, and multisource energy harvesters. It also includes the energy conversion principles of photovoltaic, electromagnetic, piezoelectric, triboelectric, electrostatic, electrostrictive, thermoelectric, pyroelectric, magnetostrictive, and dielectric devices. This is one of the most comprehensive reviews conducted to date, focusing on the entire energy harvesting research scene and providing a guide to seeking deeper and more specific research references and resources from every corner of the scientific community. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

International Nuclear Information System (INIS)

Zhong, Renming; Lu, You; Wang, Jin; Zhou, Lin; Xu, Feng; Liu, Li; Zhou, Jidan; Jiang, Xiaoqin; Chen, Nianyong; Bai, Sen

2014-01-01

To analyze the feasibility of active breath control (ABC), the lung tumor reproducibility and the rationale for single-breath-hold cone beam CT (CBCT)-guided hypofraction radiotherapy. Single-breath-hold CBCT images were acquired using ABC in a cohort of 83 lung cancer patients (95 tumors) treated with hypofraction radiotherapy. For all alignments between the reference CT and CBCT images (including the pre-correction, post-correction and post-treatment CBCT images), the tumor reproducibility was evaluated via online manual alignment of the tumors, and the vertebral bone uncertainties were evaluated via offline manual alignment of the vertebral bones. The difference between the tumor reproducibility and the vertebral bone uncertainty represents the change in the tumor position relative to the vertebral bone. The relative tumor positions along the coronal, sagittal and transverse axes were measured based on the reference CT image. The correlations between the vertebral bone uncertainty, the relative tumor position, the total treatment time and the tumor reproducibility were evaluated using the Pearson correlations. Pre-correction, the systematic/random errors of tumor reproducibility were 4.5/2.6 (medial-lateral, ML), 5.1/4.8 (cranial-caudal, CC) and 4.0/3.6 mm (anterior-posterior, AP). These errors were significantly decreased to within 3 mm, both post-correction and post-treatment. The corresponding PTV margins were 4.7 (ML), 7.4 (CC) and 5.4 (AP) mm. The changes in the tumor position relative to the vertebral bone displayed systematic/random errors of 2.2/2.0 (ML), 4.1/4.4 (CC) and 3.1/3.3 (AP) mm. The uncertainty of the vertebral bone significantly correlated to the reproducibility of the tumor position (P < 0.05), except in the CC direction post-treatment. However, no significant correlation was detected between the relative tumor position, the total treatment time and the tumor reproducibility (P > 0.05). Using ABC for single-breath-hold CBCT guidance is an

Optimised paediatric CT dose at a tertiary children's hospital in Japan: a 4-y single-centre analysis

International Nuclear Information System (INIS)

Nakada, Y.; Yamamoto, H.; Nabatame, K.; Obara, S.; Akahane, K.; Blyth, B.J.; Shimada, Y.; Fujiwara, M.; Yokoyama, T.; Shirayama, A.; Date, H.; Hoshioka, A.; Yakami, M.; Miyazaki, O.; Yagi, K.

2016-01-01

Since diagnostic reference levels (DRLs) for children are not currently established in Japan, the authors determined local DRLs for the full range of paediatric CT examinations in a single tertiary care children's hospital. A retrospective review of 4801 CT performance records for paediatric patients (<15 y old) who had undergone CT examinations from 2008 to 2011 was conducted. The most frequent examinations were of the head (52 %), followed by cardiac (15 %), temporal bone (9 %), abdomen (7 %), chest (6 %) and others (11 %). Approximately one-third of children received two or more CT scans. The authors' investigation showed that mean CTDI vol and DLP for head, chest and abdomen increased as a function of age. Benchmarking of the results showed that CTDI vol , DLP and effective dose for chest and abdomen examinations in this hospital were below average, whereas those for the head tended to be at or slightly above average of established DRL values from five countries. The results suggest that CT examinations as performed in a tertiary children's hospital in Japan are well optimised. (authors)

Experiences of using a single post-contrast CT scan of the urinary tract after triphasic contrast injection

Directory of Open Access Journals (Sweden)

Phillip Carl Pretorius

2011-12-01

Full Text Available I was alerted to an article in Radiology Vol. 255 No. 2 (May 20101 by a colleague. The article, entitled ‘Kidney and urinary tract imaging: Triple-bolus multidetector CT urography as a one-stop shop – Protocol design, opacification, and image quality analysis’, clearly describes the technique, while the quotation below, from the article, summarises the findings: ‘We have shown that triple-bolus multidetector CT urography allowed visualization of renal parenchymal, excretory, and vascular contrast-enhancement phases in a single dose-efficient acquisition and provided sufficient opacification of the UUT, with simultaneous and adequate image quality of renal parenchyma and vascular anatomy.’ The main emphasis on this technique is to reduce the number of unnecessary CT scans when assessing the urinary tract. Our previous protocol for scanning the urinary tract for pathology included four phases: a pre-contrast, corticomedullary, nephrographic and delay excretory phase.

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.

Multidetector row computed tomography of acute pancreatitis: Utility of single portal phase CT scan in short-term follow up

Energy Technology Data Exchange (ETDEWEB)

Kwon, Yongwonn [Department of Radiology, Konkuk University Medical Center, 4-12, Hwayang-dong, Gwangjin-gu, Seoul 143-729 (Korea, Republic of); Park, Hee Sun, E-mail: heesun.park@gmail.com [Department of Radiology, Konkuk University Medical Center, 4-12, Hwayang-dong, Gwangjin-gu, Seoul 143-729 (Korea, Republic of); Kim, Young Jun; Jung, Sung Il; Jeon, Hae Jeong [Department of Radiology, Konkuk University Medical Center, 4-12, Hwayang-dong, Gwangjin-gu, Seoul 143-729 (Korea, Republic of)

2012-08-15

Objective: The purpose of this study is to evaluate the question of whether nonenhanced CT or contrast enhanced portal phase CT can replace multiphasic pancreas protocol CT in short term monitoring in patients with acute pancreatitis. Materials and methods: This retrospective study was approved by the Institutional Review Board. From April 2006 to May 2010, a total of 52 patients having acute pancreatitis who underwent initial dual phase multidetector row CT (unenhanced, arterial, and portal phase) at admission and a short term (within 30 days) follow up dual phase CT (mean interval 10.3 days, range 3-28 days) were included. Two abdominal radiologists performed an independent review of three sets of follow up CT images (nonenhanced scan, single portal phase scan, and dual phase scan). Interpretation of each image set was done with at least 2-week interval. Radiologists evaluated severity of acute pancreatitis with regard to pancreatic inflammation, pancreatic necrosis, and extrapancreatic complication, based on the modified CT severity index. Scores of each image set were compared using a paired t-test and interobserver agreement was evaluated using intraclass correlation coefficient statistics. Results: Mean scores of sum of CT severity index on nonenhanced scan, portal phase scan, and dual phase scan were 5.7, 6.6, and 6.5 for radiologist 1, and 5.0, 5.6, and 5.8 for radiologist 2, respectively. In both radiologists, contrast enhanced scan (portal phase scan and dual phase scan) showed significantly higher severity score compared with that of unenhanced scan (P < 0.05), while portal phase and dual phase scan showed no significant difference each other. The trend was similar regarding pancreatic inflammation and extrapancreatic complications, in which contrast enhanced scans showed significantly higher score compared with those of unenhanced scan, while no significant difference was observed between portal phase scan and dual phase scan. In pancreatic necrosis

{sup 18}F-FDG PET/CT and contrast-enhanced CT findings of pulmonary cryptococcosis

Energy Technology Data Exchange (ETDEWEB)

Wang, Si-yun, E-mail: wang_shuxia@outlook.com [Department of PET Center, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Chen, Gang, E-mail: cgggh@outlook.com [Department of Thoracic Surgery, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Luo, Dong-lan, E-mail: 695532870@qq.com [Department of Pathology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Shao, Dan, E-mail: shaodan501@outlook.com [Department of PET Center, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Liu, En-tao, E-mail: GDGH2015@gmail.com [Department of PET Center, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Sun, Taotao, E-mail: sunmoodsdaisy@bjmu.edu.cn [Department of PET Center, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Wang, Shu-Xia, E-mail: wsyggh@outlook.com [Department of PET Center, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China)

2017-04-15

Purpose: Pulmonary cryptococcosis is an uncommon cause of pulmonary nodules in non-AIDS patients. This study reports the {sup 18}F-fluorodeoxyglucose-positron emission tomography ({sup 18}F-FDG PET/CT) and contrast-enhanced CT (CE-CT) findings of 42 patients with pulmonary cryptococcosis. Materials and methods: A retrospective review of the {sup 18}F-FDG PET/CT and CE-CT findings of 42 patients with histologically proven pulmonary cryptococcosis was conducted. All patients underwent PET/CT and CE-CT in the same session. The CT diagnosis was based on the location, morphological features, and enhancement of lesions. The PET/CT findings were recorded, and clinical data and surgical and histopathological findings were collected. Results: The results of the PET scans revealed that 37 (88%) of 42 patients showed higher FDG uptake, and 5 (12%) patients demonstrated lower FDG uptake than the mediastinal blood pool. The maximum standardized uptake value (SUV) of pulmonary cryptococcosis ranged from 1.4 to 13.0 (average: 5.7 ± 3.3, median 4.9). A single nodular pattern was the most prevalent pattern observed and was found in 29 (69%) patients. This pattern was followed by scattered nodular (n = 4, 10%), clustered nodular (n = 3, 7%), mass-like (n = 3, 7%), and bronchopneumonic (n = 3, 7%) patterns. The most frequent pattern of immunocompetent patients was the single nodular pattern (29 of 33, 88%). Immunocompromised patients most frequently pattern exhibited mass-like (3 of 9, 33%) and bronchopneumonic (3 of 9, 33%) patterns. Conclusion: Pulmonary cryptococcosis most commonly appears as single nodules in immunocompetent patients. Mass-like and bronchopneumonic patterns were common in immunocompromised patients. In 88% of patients, lung lesions showed high FDG uptake, thus mimicking a possible malignant condition.

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

Incidental physiological sliding hiatal hernia: a single center comparison study between CT with water enema and CT colonography.

Science.gov (United States)

Revelli, Matteo; Furnari, Manuele; Bacigalupo, Lorenzo; Paparo, Francesco; Astengo, Davide; Savarino, Edoardo; Rollandi, Gian Andrea

2015-08-01

Hiatal hernia is a well-known factor impacting on most mechanisms underlying gastroesophageal reflux, related with the risk of developing complications such as erosive esophagitis, Barrett's esophagus and ultimately, esophageal adenocarcinoma. It is our firm opinion that an erroneous reporting of hiatal hernia in CT exams performed with colonic distention may trigger a consecutive diagnostic process that is not only unnecessary, inducing a unmotivated anxiety in the patient, but also expensive and time-consuming for both the patient and the healthcare system. The purposes of our study were to determine whether colonic distention at CT with water enema and CT colonography can induce small sliding hiatal hernias and to detect whether hiatal hernias size modifications could be considered significant for both water and gas distention techniques. We retrospectively evaluated 400 consecutive patients, 200 undergoing CT-WE and 200 undergoing CTC, including 59 subjects who also underwent a routine abdominal CT evaluation on a different time, used as internal control, while a separate group of 200 consecutive patients who underwent abdominal CT evaluation was used as external control. Two abdominal radiologists assessed the CT exams for the presence of a sliding hiatal hernia, grading the size as small, moderate, or large; the internal control groups were directly compared with the corresponding CT-WE or CTC study looking for a change in hernia size. We used the Student's t test applying a size-specific correction factor, in order to account for the effect of colonic distention: these "corrected" values were then individually compared with the external control group. A sliding hiatal hernia was present in 51 % (102/200) of the CT-WE patients and in 48.5 % (97/200) of the CTC patients. Internal control CT of the 31 patients with a hernia at CT-WE showed resolution of the hernia in 58.1 % (18/31) of patients, including 76.5 % (13/17) and 45.5 % (5/11) of small and moderate

Spiral computed tomography phase-space source model in the BEAMnrc/EGSnrc Monte Carlo system: implementation and validation

International Nuclear Information System (INIS)

Kim, Sangroh; Yoshizumi, Terry T; Yin Fangfang; Chetty, Indrin J

2013-01-01

Currently, the BEAMnrc/EGSnrc Monte Carlo (MC) system does not provide a spiral CT source model for the simulation of spiral CT scanning. We developed and validated a spiral CT phase-space source model in the BEAMnrc/EGSnrc system. The spiral phase-space source model was implemented in the DOSXYZnrc user code of the BEAMnrc/EGSnrc system by analyzing the geometry of spiral CT scan—scan range, initial angle, rotational direction, pitch, slice thickness, etc. Table movement was simulated by changing the coordinates of the isocenter as a function of beam angles. Some parameters such as pitch, slice thickness and translation per rotation were also incorporated into the model to make the new phase-space source model, designed specifically for spiral CT scan simulations. The source model was hard-coded by modifying the ‘ISource = 8: Phase-Space Source Incident from Multiple Directions’ in the srcxyznrc.mortran and dosxyznrc.mortran files in the DOSXYZnrc user code. In order to verify the implementation, spiral CT scans were simulated in a CT dose index phantom using the validated x-ray tube model of a commercial CT simulator for both the original multi-direction source (ISOURCE = 8) and the new phase-space source model in the DOSXYZnrc system. Then the acquired 2D and 3D dose distributions were analyzed with respect to the input parameters for various pitch values. In addition, surface-dose profiles were also measured for a patient CT scan protocol using radiochromic film and were compared with the MC simulations. The new phase-space source model was found to simulate the spiral CT scanning in a single simulation run accurately. It also produced the equivalent dose distribution of the ISOURCE = 8 model for the same CT scan parameters. The MC-simulated surface profiles were well matched to the film measurement overall within 10%. The new spiral CT phase-space source model was implemented in the BEAMnrc/EGSnrc system. This work will be beneficial in estimating the

Spiral computed tomography phase-space source model in the BEAMnrc/EGSnrc Monte Carlo system: implementation and validation.

Science.gov (United States)

Kim, Sangroh; Yoshizumi, Terry T; Yin, Fang-Fang; Chetty, Indrin J

2013-04-21

Currently, the BEAMnrc/EGSnrc Monte Carlo (MC) system does not provide a spiral CT source model for the simulation of spiral CT scanning. We developed and validated a spiral CT phase-space source model in the BEAMnrc/EGSnrc system. The spiral phase-space source model was implemented in the DOSXYZnrc user code of the BEAMnrc/EGSnrc system by analyzing the geometry of spiral CT scan-scan range, initial angle, rotational direction, pitch, slice thickness, etc. Table movement was simulated by changing the coordinates of the isocenter as a function of beam angles. Some parameters such as pitch, slice thickness and translation per rotation were also incorporated into the model to make the new phase-space source model, designed specifically for spiral CT scan simulations. The source model was hard-coded by modifying the 'ISource = 8: Phase-Space Source Incident from Multiple Directions' in the srcxyznrc.mortran and dosxyznrc.mortran files in the DOSXYZnrc user code. In order to verify the implementation, spiral CT scans were simulated in a CT dose index phantom using the validated x-ray tube model of a commercial CT simulator for both the original multi-direction source (ISOURCE = 8) and the new phase-space source model in the DOSXYZnrc system. Then the acquired 2D and 3D dose distributions were analyzed with respect to the input parameters for various pitch values. In addition, surface-dose profiles were also measured for a patient CT scan protocol using radiochromic film and were compared with the MC simulations. The new phase-space source model was found to simulate the spiral CT scanning in a single simulation run accurately. It also produced the equivalent dose distribution of the ISOURCE = 8 model for the same CT scan parameters. The MC-simulated surface profiles were well matched to the film measurement overall within 10%. The new spiral CT phase-space source model was implemented in the BEAMnrc/EGSnrc system. This work will be beneficial in estimating the spiral

Investigation on a Novel Discontinuous Pulse-Width Modulation Algorithm for Single-phase Voltage Source Rectifier

DEFF Research Database (Denmark)

Qu, Hao; Yang, Xijun; Guo, Yougui

2014-01-01

Single-phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). Single-phase VSC...

Micro CT based truth estimation of nodule volume

Science.gov (United States)

Kinnard, L. M.; Gavrielides, M. A.; Myers, K. J.; Zeng, R.; Whiting, B.; Lin-Gibson, S.; Petrick, N.

2010-03-01

With the advent of high-resolution CT, three-dimensional (3D) methods for nodule volumetry have been introduced, with the hope that such methods will be more accurate and consistent than currently used planar measures of size. However, the error associated with volume estimation methods still needs to be quantified. Volume estimation error is multi-faceted in the sense that there is variability associated with the patient, the software tool and the CT system. A primary goal of our current research efforts is to quantify the various sources of measurement error and, when possible, minimize their effects. In order to assess the bias of an estimate, the actual value, or "truth," must be known. In this work we investigate the reliability of micro CT to determine the "true" volume of synthetic nodules. The advantage of micro CT over other truthing methods is that it can provide both absolute volume and shape information in a single measurement. In the current study we compare micro CT volume truth to weight-density truth for spherical, elliptical, spiculated and lobulated nodules with diameters from 5 to 40 mm, and densities of -630 and +100 HU. The percent differences between micro CT and weight-density volume for -630 HU nodules range from [-21.7%, -0.6%] (mean= -11.9%) and the differences for +100 HU nodules range from [-0.9%, 3.0%] (mean=1.7%).

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.

Modeling and Design of High-Efficiency Single-Photon Sources

DEFF Research Database (Denmark)

Gregersen, Niels; Nielsen, Per Kær; Mørk, Jesper

2013-01-01

be electrically driven. Several design strategies addressing these requirements have been proposed. In the cavity-based source, light emission is controlled using resonant cavity quantum electrodynamics effects, whereas in the waveguide-based source, broadband electric field screening effects are employed......Solid-state sources capable of emitting single photons on demand are of great interest in quantum information applications. Ideally, such a source should emit exactly one photon into the collection optics per trigger, the emitted photons should be indistinguishable, and the source should...

Open source deformable image registration system for treatment planning and recurrence CT scans. Validation in the head and neck region

International Nuclear Information System (INIS)

Zukauskaite, Ruta; Brink, Carsten; Hansen, Christian Roenn; Bertelsen, Anders; Johansen, Joergen; Eriksen, Jesper Grau; Grau, Cai

2016-01-01

Clinical application of deformable registration (DIR) of medical images remains limited due to sparse validation of DIR methods in specific situations, e. g. in case of cancer recurrences. In this study the accuracy of DIR for registration of planning CT (pCT) and recurrence CT (rCT) images of head and neck squamous cell carcinoma (HNSCC) patients was evaluated. Twenty patients treated with definitive IMRT for HNSCC in 2010-2012 were included. For each patient, a pCT and an rCT scan were used. Median interval between the scans was 8.5 months. One observer manually contoured eight anatomical regions-of-interest (ROI) twice on pCT and once on rCT. pCT and rCT images were deformably registered using the open source software elastix. Mean surface distance (MSD) and Dice similarity coefficient (DSC) between contours were used for validation of DIR. A measure for delineation uncertainty was estimated by assessing MSD from the re-delineations of the same ROI on pCT. DIR and manual contouring uncertainties were correlated with tissue volume and rigidity. MSD varied 1-3 mm for different ROIs for DIR and 1-1.5 mm for re-delineated ROIs performed on pCT. DSC for DIR varied between 0.58 and 0.79 for soft tissues and was 0.79 or higher for bony structures, and correlated with the volumes of ROIs (r = 0.5, p < 0.001) and tissue rigidity (r = 0.54, p < 0.001). DIR using elastix in HNSCC on planning and recurrence CT scans is feasible; an uncertainty of the method is close to the voxel size length of the planning CT images. (orig.) [de

Open source deformable image registration system for treatment planning and recurrence CT scans : Validation in the head and neck region.

Science.gov (United States)

Zukauskaite, Ruta; Brink, Carsten; Hansen, Christian Rønn; Bertelsen, Anders; Johansen, Jørgen; Grau, Cai; Eriksen, Jesper Grau

2016-08-01

Clinical application of deformable registration (DIR) of medical images remains limited due to sparse validation of DIR methods in specific situations, e. g. in case of cancer recurrences. In this study the accuracy of DIR for registration of planning CT (pCT) and recurrence CT (rCT) images of head and neck squamous cell carcinoma (HNSCC) patients was evaluated. Twenty patients treated with definitive IMRT for HNSCC in 2010-2012 were included. For each patient, a pCT and an rCT scan were used. Median interval between the scans was 8.5 months. One observer manually contoured eight anatomical regions-of-interest (ROI) twice on pCT and once on rCT. pCT and rCT images were deformably registered using the open source software elastix. Mean surface distance (MSD) and Dice similarity coefficient (DSC) between contours were used for validation of DIR. A measure for delineation uncertainty was estimated by assessing MSD from the re-delineations of the same ROI on pCT. DIR and manual contouring uncertainties were correlated with tissue volume and rigidity. MSD varied 1-3 mm for different ROIs for DIR and 1-1.5 mm for re-delineated ROIs performed on pCT. DSC for DIR varied between 0.58 and 0.79 for soft tissues and was 0.79 or higher for bony structures, and correlated with the volumes of ROIs (r = 0.5, p elastix in HNSCC on planning and recurrence CT scans is feasible; an uncertainty of the method is close to the voxel size length of the planning CT images.

CT-Urography

International Nuclear Information System (INIS)

Dalla Palma, Ludovico; Grotto, Maurizio; Morra, Aldo

2005-01-01

In this paper we present an overview of CT-Urography. With the advent of multislice CT scanners and the evolution of image processing methods this technique now affords optimal urographic images comparable to those obtained with conventional techniques. We describe the acquisition techniques and protocols used by the various authors. Effective radiation dose has conditioned the use of CT-Urography so that the tendency today is to reduce the number of scans by performing, after the non enhanced scan, a single contrast-enhanced scan comprising both the nephrographic and urographic phase. With the use of multislice CT the quality of the urogram improves with the number of slices. We illustrate a variety of processing techniques, multiplanar reconstruction (MPR), maximum (MIP) and average intensity projection (AIP) and volume rendering (VR) and present a series of upper urinary tract tumours testifying to the superiority of the AIP technique over MIP. We then review the results of comparative studies of CT-Urography with conventional urography in upper urinary tract diagnostics. Finally, we describe the advantages and limitations of CT-Urography [it

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.)

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.

Implementation of a split-bolus single-pass CT protocol at a UK major trauma centre to reduce excess radiation dose in trauma pan-CT

International Nuclear Information System (INIS)

Leung, V.; Sastry, A.; Woo, T.D.; Jones, H.R.

2015-01-01

Aim: To quantify the dose reduction and ensure that the use of a split-bolus protocol provided sufficient vascular enhancement. Materials and methods: Between 1 January 2014 and 31 May 2014, both split bolus and traditional two-phase scans were performed on a single CT scanner (SOMATOM Definition AS+, Siemens Healthcare) using a two-pump injector (Medrad Stellant). Both protocols used Siemens' proprietary tube current and tube voltage modulation techniques (CARE dose and CARE kV). The protocols were compared retrospectively to assess the dose–length product (DLP), aortic radiodensity at the level of the coeliac axis and radiodensity of the portal vein. Results: There were 151 trauma CT examinations during this period. Seventy-eight used the split-bolus protocol. Seventy-one had traditional two-phase imaging. One patient was excluded as they were under the age of 18 years. The radiodensity measurements for the portal vein were significantly higher (p<0.001) in the split-bolus protocol. The mean aortic enhancement in both protocols exceeded 250 HU, although the traditional two-phase protocol gave greater arterial enhancement (p<0.001) than the split-bolus protocol. The split-bolus protocol had a significantly lower (p<0.001) DLP with 43.5% reduction in the mean DLP compared to the traditional protocol. Conclusion: Split-bolus CT imaging offers significant dose reduction for this relatively young population while retaining both arterial and venous enhancement. -- Highlights: •We implemented a split bolus pan-CT protocol for trauma CT. •We compared the radiation dose and vascular enhancement of the split bolus protocol to a traditional two phase protocol. •The split bolus protocol had a 43.5% reduction in mean DLP

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

Dual energy CTA of the supraaortic arteries: Technical improvements with a novel dual source CT system

International Nuclear Information System (INIS)

Lell, Michael M.; Hinkmann, Fabian; Nkenke, Emeka; Schmidt, Bernhard; Seidensticker, Peter; Kalender, Willi A.; Uder, Michael; Achenbach, Stephan

2010-01-01

Objectives: Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts. Materials and methods: Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140 kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1 = poor; 3 = excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n = 26) with a 5-point scale (1 = poor; 5 = excellent), CTA source data served as the reference. Results: Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations 10% resulting in a total luminal reduction 50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries. Conclusions: Excellent bone suppression could be achieved, DE imaging with 100 and 140 kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.

High brightness single photon sources based on photonic wires

DEFF Research Database (Denmark)

Claudon, J.; Bleuse, J.; Bazin, M.

2009-01-01

We present a novel single-photon-source based on the emission of a semiconductor quantum dot embedded in a single-mode photonic wire. This geometry ensures a very large coupling (> 95%) of the spontaneous emission to the guided mode. Numerical simulations show that a photon collection efficiency...

Construction of Korean male tomographic model segmented from PET-CT data

International Nuclear Information System (INIS)

Lee, Choon Sik; Park, Sang Kyun; Lee, Jai Ki

2004-01-01

Tomographic human models provide currently the most realistic representation of human anatomy for radiation dosimetry calculation. Most of the models have been constructed by using computed tomographic (CT) or magnetic resonance (MR) images obtained from a single individual. Each scan has its inherent advantages and disadvantages. CT scan gives a considerable radiation dose to a subject, and MR scan takes too long time to get clear images of an immobile subject. An emerging source of medical images for the construction of tomographic models is PET-CT, which is performed when looking for cancer. In this study, a tomographic model of Korean adult male was developed by processing whole-body CT images of a PET-CT-scanned healthy volunteer. The 343 slices of the CT images were semi-automatically segmented layer by layer using a graphic software and screen digitizer. The 3rd Korean tomographic model, named KRMAN-2, consisting of 300x150x344 voxels of a size of 2x2x5mm 3 , was constructed. Examples of application to Monte Carlo radiation dosimetry calculation in idealized whole-body irradiations were given and discussed

Entangling quantum-logic gate operated with an ultrabright semiconductor single-photon source.

Science.gov (United States)

Gazzano, O; Almeida, M P; Nowak, A K; Portalupi, S L; Lemaître, A; Sagnes, I; White, A G; Senellart, P

2013-06-21

We demonstrate the unambiguous entangling operation of a photonic quantum-logic gate driven by an ultrabright solid-state single-photon source. Indistinguishable single photons emitted by a single semiconductor quantum dot in a micropillar optical cavity are used as target and control qubits. For a source brightness of 0.56 photons per pulse, the measured truth table has an overlap with the ideal case of 68.4±0.5%, increasing to 73.0±1.6% for a source brightness of 0.17 photons per pulse. The gate is entangling: At a source brightness of 0.48, the Bell-state fidelity is above the entangling threshold of 50% and reaches 71.0±3.6% for a source brightness of 0.15.

CT urography

Energy Technology Data Exchange (ETDEWEB)

Korobkin, M. [Dept. of Radiology, Univ. of Michigan, Ann Arbor, MI (United States)

2005-11-15

With the advent of multidetector row CT scanners, evaluation of the urothelium of the entire urinary tract with high-resolution thin sections during a single breath-hold has become a reality. Multidetector CT urography (MDCTU) is a single examination that allows evaluation of potential urinary tract calculi, renal parenchymal masses, and both benign and malignant urothelial lesions. Initial results with this new technique are encouraging. Current investigations of MDCTU focus on methods to improve opacification and distension of the upper urinary tract - the collecting systems, pelvis, and ureters. The role of abdominal compression, infusion of saline and/or furosemide, and optimal time delay of excretory phase imaging is being explored. Upper tract urothelial malignancies, including small lesions less the 5 mmin diameter, can be detected with high sensitivity. Methods to reduce radiation exposure are being explored, including split-bolus contrast injection techniques that combine nephrographic and excretory phases into a single phase. It is likely that in the near future, radiological evaluation of significant unexplained hematuria or of known or prior urothelial malignancy will consist of a single examination - MDCTU. (orig.)

Children's (Pediatric) CT (Computed Tomography)

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called "multislice CT" or "multidetector CT," ... prescribed procedure with your doctor, the medical facility staff and/or your insurance provider to get a ...

Children's (Pediatric) CT (Computed Tomography)

Medline Plus

Full Text Available ... scanners to obtain multiple slices in a single rotation. These scanners, called "multislice CT" or "multidetector CT," ... best for your child. top of page Additional Information and Resources The Alliance for Radiation Safety in ...

Prediction of sentinel lymph node status using single-photon emission computed tomography (SPECT)/computed tomography (CT) imaging of breast cancer.

Science.gov (United States)

Tomiguchi, Mai; Yamamoto-Ibusuki, Mutsuko; Yamamoto, Yutaka; Fujisue, Mamiko; Shiraishi, Shinya; Inao, Touko; Murakami, Kei-ichi; Honda, Yumi; Yamashita, Yasuyuki; Iyama, Ken-ichi; Iwase, Hirotaka

2016-02-01

Single-photon emission computed tomography (SPECT)/computed tomography (CT) improves the anatomical identification of sentinel lymph nodes (SNs). We aimed to evaluate the possibility of predicting the SN status using SPECT/CT. SN mapping using a SPECT/CT system was performed in 381 cases of clinically node-negative, operable invasive breast cancer. We evaluated and compared the values of SN mapping on SPECT/CT, the findings of other modalities and clinicopathological factors in predicting the SN status. Patients with SNs located in the Level I area were evaluated. Of the 355 lesions (94.8 %) assessed, six cases (1.6 %) were not detected using any imaging method. According to the final histological diagnosis, 298 lesions (78.2 %) were node negative and 83 lesions (21.7 %) were node positive. The univariate analysis showed that SN status was significantly correlated with the number of SNs detected on SPECT/CT in the Level I area (P = 0.0048), total number of SNs detected on SPECT/CT (P = 0.011), findings of planar lymphoscintigraphy (P = 0.011) and findings of a handheld gamma probe during surgery (P = 0.012). According to the multivariate analysis, the detection of multiple SNs on SPECT/CT imaging helped to predict SN metastasis. The number of SNs located in the Level I area detected using the SPECT/CT system may be a predictive factor for SN metastasis.

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

Single source dual-energy computed tomography in the diagnosis of gout: Diagnostic reliability in comparison to digital radiography and conventional computed tomography of the feet

International Nuclear Information System (INIS)

Kiefer, Tobias; Diekhoff, Torsten; Hermann, Sandra; Stroux, Andrea; Mews, Jürgen; Blobel, Jörg; Hamm, Bernd; Hermann, Kay-Geert A.

2016-01-01

Objectives: To investigate the diagnostic value of single-source dual-energy computed tomography (SDECT) in gouty arthritis and to compare its capability to detect urate depositions with digital radiography (DR) and conventional computed tomography (CT). Methods: Forty-four patients who underwent SDECT volume scans of the feet for suspected gouty arthritis were retrospectively analyzed. SDECT, CT (both n = 44) and DR (n = 36) were scored by three blinded readers for presence of osteoarthritis, erosions, and tophi. A diagnosis was made for each imaging modality. Results were compared to the clinical diagnosis using the American College of Rheumatology (ACR) classification criteria. Results: The patient population was divided into a gout (n = 21) and control (n = 23) group based on final clinical diagnosis. Osteoarthritis was evident in 15 joints using CT and 30 joints using DR (p = 0.165). There were 134 erosions detected by CT compared to 38 erosions detected by DR (p < 0.001). In total 119 tophi were detected by SDECT, compared to 85 tophi by CT (p = 0.182) and 25 tophi by DR (p < 0.001). SDECT had best diagnostic value for diagnosis of gout compared to DR and conventional CT (sensitivity and specificity for SDECT: 71.4% and 95.7%, CT: 71.4% and 91.3% and DR: 44.4% and 83.3%, respectively). For all three readers, Cohen’s kappa for DR and conventional CT were substantial for all scoring items and ranged from 0.75 to 0.77 and 0.72–0.76, respectively. For SDECT Cohen’s kappa was good to almost perfect with 0.77–0.84. Conclusions: SDECT is capable to detect uric acid depositions with good sensitivity and high specificity in feet, therefore diagnostic confidence is improved. Using SDECT, inter-reader variance can be markedly reduced for the detection of gouty tophi.

Single source dual-energy computed tomography in the diagnosis of gout: Diagnostic reliability in comparison to digital radiography and conventional computed tomography of the feet

Energy Technology Data Exchange (ETDEWEB)

Kiefer, Tobias; Diekhoff, Torsten [Department of Radiology, Charité—Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität, Berlin, Charitéplatz 1, 10117 Berlin (Germany); Hermann, Sandra [Department of Rheumatology and Clinical Immunology, Charité—Universitätsmedizin Berlin Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Charitéplatz 1, 10117 Berlin (Germany); Stroux, Andrea [Department of Medical Informatics, Biometry and Epidemiology, Freie Universität Berlin, Berlin (Germany); Mews, Jürgen; Blobel, Jörg [Toshiba Medical Systems Europe, BV, Zilverstraat 1, 2701 RP Zoetermeer (Netherlands); Hamm, Bernd [Department of Radiology, Charité—Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität, Berlin, Charitéplatz 1, 10117 Berlin (Germany); Hermann, Kay-Geert A., E-mail: kghermann@gmail.com [Department of Radiology, Charité—Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität, Berlin, Charitéplatz 1, 10117 Berlin (Germany)

2016-10-15

Objectives: To investigate the diagnostic value of single-source dual-energy computed tomography (SDECT) in gouty arthritis and to compare its capability to detect urate depositions with digital radiography (DR) and conventional computed tomography (CT). Methods: Forty-four patients who underwent SDECT volume scans of the feet for suspected gouty arthritis were retrospectively analyzed. SDECT, CT (both n = 44) and DR (n = 36) were scored by three blinded readers for presence of osteoarthritis, erosions, and tophi. A diagnosis was made for each imaging modality. Results were compared to the clinical diagnosis using the American College of Rheumatology (ACR) classification criteria. Results: The patient population was divided into a gout (n = 21) and control (n = 23) group based on final clinical diagnosis. Osteoarthritis was evident in 15 joints using CT and 30 joints using DR (p = 0.165). There were 134 erosions detected by CT compared to 38 erosions detected by DR (p < 0.001). In total 119 tophi were detected by SDECT, compared to 85 tophi by CT (p = 0.182) and 25 tophi by DR (p < 0.001). SDECT had best diagnostic value for diagnosis of gout compared to DR and conventional CT (sensitivity and specificity for SDECT: 71.4% and 95.7%, CT: 71.4% and 91.3% and DR: 44.4% and 83.3%, respectively). For all three readers, Cohen’s kappa for DR and conventional CT were substantial for all scoring items and ranged from 0.75 to 0.77 and 0.72–0.76, respectively. For SDECT Cohen’s kappa was good to almost perfect with 0.77–0.84. Conclusions: SDECT is capable to detect uric acid depositions with good sensitivity and high specificity in feet, therefore diagnostic confidence is improved. Using SDECT, inter-reader variance can be markedly reduced for the detection of gouty tophi.

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

PET/CT-guided percutaneous liver mass biopsies and ablations: Targeting accuracy of a single 20 s breath-hold PET acquisition

International Nuclear Information System (INIS)

Shyn, P.B.; Tatli, S.; Sahni, V.A.; Sadow, C.A.; Forgione, K.; Mauri, G.; Morrison, P.R.; Catalano, P.J.; Silverman, S.G.

2014-01-01

Aim: To determine whether a single 20 s breath-hold positron-emission tomography (PET) acquisition obtained during combined PET/computed tomography (CT)-guided percutaneous liver biopsy or ablation procedures has the potential to target 2-[ 18 F]-fluoro-2-deoxy-D-glucose (FDG)-avid liver masses as accurately as up to 180 s breath-hold PET acquisitions. Materials and methods: This retrospective study included 10 adult patients with 13 liver masses who underwent FDG PET/CT-guided percutaneous biopsies (n = 5) or ablations (n = 5). PET was acquired as nine sequential 20 s, monitored, same-level breath-hold frames and CT was acquired in one monitored breath-hold. Twenty, 40, 60, and 180 s PET datasets were reconstructed. Two blinded readers marked tumour centres on randomized PET and CT datasets. Three-dimensional spatial localization differences between PET datasets and either 180 s PET or CT were analysed using multiple regression analyses. Statistical tests were two-sided and p < 0.05 was considered significant. Results: Targeting differences between 20 s PET and 180 s PET ranged from 0.7–20.3 mm (mean 5.3 ± 4.4 mm; median 4.3) and were not statistically different from 40 or 60 s PET (p = 0.74 and 0.91, respectively). Targeting differences between 20 s PET and CT ranged from 1.4–36 mm (mean 9.6 ± 7.1 mm; median 8.2 mm) and were not statistically different from 40, 60, or 180 s PET (p = 0.84, 0.77, and 0.35, respectively). Conclusion: Single 20 s breath-hold PET acquisitions from PET/CT-guided percutaneous liver procedures have the potential to target FDG-avid liver masses with equivalent accuracy to 180 s summed, breath-hold PET acquisitions and may facilitate strategies that improve image registration and shorten procedure times

Image Quality of 3rd Generation Spiral Cranial Dual-Source CT in Combination with an Advanced Model Iterative Reconstruction Technique: A Prospective Intra-Individual Comparison Study to Standard Sequential Cranial CT Using Identical Radiation Dose.

Science.gov (United States)

Wenz, Holger; Maros, Máté E; Meyer, Mathias; Förster, Alex; Haubenreisser, Holger; Kurth, Stefan; Schoenberg, Stefan O; Flohr, Thomas; Leidecker, Christianne; Groden, Christoph; Scharf, Johann; Henzler, Thomas

2015-01-01

To prospectively intra-individually compare image quality of a 3rd generation Dual-Source-CT (DSCT) spiral cranial CT (cCT) to a sequential 4-slice Multi-Slice-CT (MSCT) while maintaining identical intra-individual radiation dose levels. 35 patients, who had a non-contrast enhanced sequential cCT examination on a 4-slice MDCT within the past 12 months, underwent a spiral cCT scan on a 3rd generation DSCT. CTDIvol identical to initial 4-slice MDCT was applied. Data was reconstructed using filtered backward projection (FBP) and 3rd-generation iterative reconstruction (IR) algorithm at 5 different IR strength levels. Two neuroradiologists independently evaluated subjective image quality using a 4-point Likert-scale and objective image quality was assessed in white matter and nucleus caudatus with signal-to-noise ratios (SNR) being subsequently calculated. Subjective image quality of all spiral cCT datasets was rated significantly higher compared to the 4-slice MDCT sequential acquisitions (pspiral compared to sequential cCT datasets with mean SNR improvement of 61.65% (p*Bonferroni0.05spiral cCT with an advanced model IR technique significantly improves subjective and objective image quality compared to a standard sequential cCT acquisition acquired at identical dose levels.

Visualization of portal venous system by single photon emission CT

Energy Technology Data Exchange (ETDEWEB)

Kashiwagi, T; Ikawa, T; Azuma, M; Matsuda, H; Yoshioka, H; Mitsutani, N; Koizumi, T

1987-03-01

Single photon emission CT (SPECT) was performed for the intra-abdominal blood pool with /sup 99m/Tc autologous red blood cells (RBC) in 15 patients with liver cirrhosis. Twenty mCi of /sup 99m/Tc-RBC labeled by in vivo technique were administered intravenously and tomographic imaging of the intra-abdominal vascular blood pool was performed as follows. For each subject, 64 views were obtained over 360 deg of elliptic rotation at 30 seconds per view using a high resolution low energy parallel-hole collimator. Portal vein and portosystemic collaterals were clearly observed in coronal images. In 12 of 15 patients, portal vein was delineated. Portosystemic collaterals such as coronary vein, splenorenal shunt and umbilical vein were also shown in 12 patients. These images were consistent with images obtained by scintiphotosplenoportography or arterial portography. Therefore, it is considered that SPECT study for the intra-abdominal blood pool is clinically very useful for the diagnosis of abnormality of portal venous system in portal hypertension.

Cardiac CT for the assessment of chest pain: Imaging techniques and clinical results

International Nuclear Information System (INIS)

Becker, Hans-Christoph; Johnson, Thorsten

2012-01-01

Immediate and efficient risk stratification and management of patients with acute chest pain in the emergency department is challenging. Traditional management of these patients includes serial ECG, laboratory tests and further on radionuclide perfusion imaging or ECG treadmill testing. Due to the advances of multi-detector CT technology, dedicated coronary CT angiography provides the potential to rapidly and reliably diagnose or exclude acute coronary artery disease. Life-threatening causes of chest pain, such as aortic dissection and pulmonary embolism can simultaneously be assessed with a single scan, sometimes referred to as “triple rule out” scan. With appropriate patient selection, cardiac CT can accurately diagnose heart disease or other sources of chest pain, markedly decrease health care costs, and reliably predict clinical outcomes. This article reviews imaging techniques and clinical results for CT been used to evaluate patients with chest pain entering the emergency department.

The effect of pitch in multislice spiral/helical CT

International Nuclear Information System (INIS)

Wang, G.; Vannier, M.W.

2000-01-01

The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the detector collimation, and the table increment per x-ray source rotation. The pitch in multislice spiral CT is defined as the ratio of the table increment over the detector collimation in this study. In parallel to the current framework for studying longitudinal image resolution, the central fan-beam rays of direct and opposite directions are considered, assuming a narrow cone-beam angle. Generally speaking, sampling in the Radon domain by the direct and opposite central rays is nonuniform along the longitudinal axis. Using a recently developed methodology for quantifying the sensibility of signal reconstruction from non-uniformly sampled finite points, the effect of pitch on raw data interpolation is analyzed in multislice spiral CT. Unlike single-slice spiral CT, in which image quality decreases monotonically as the pitch increases, the sensibility of raw data interpolation in multislice spiral CT increases, suggesting that image quality does not decrease monotonically in this case. The most favorable pitch can be found from the sensitivity-slice spiral CT is provided. The study on the effect of pitch using the sensitivity analysis approach reveals the fundamental characteristics of raw data interpolation in multislice spiral CT, and gives insights into interaction between pitch and image quality. These results may be valuable for design of multislice spiral CT scanners and imaging protocol optimization in clinical applications. (authors)

Dedicated breast CT: radiation dose for circle-plus-line trajectory

International Nuclear Information System (INIS)

Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew; Noo, Frederic

2012-01-01

Purpose: Dedicated breast CT prototypes used in clinical investigations utilize single circular source trajectory and cone-beam geometry with flat-panel detectors that do not satisfy data-sufficiency conditions and could lead to cone beam artifacts. Hence, this work investigated the glandular dose characteristics of a circle-plus-line trajectory that fulfills data-sufficiency conditions for image reconstruction in dedicated breast CT. Methods: Monte Carlo-based computer simulations were performed using the GEANT4 toolkit and was validated with previously reported normalized glandular dose coefficients for one prototype breast CT system. Upon validation, Monte Carlo simulations were performed to determine the normalized glandular dose coefficients as a function of x-ray source position along the line scan. The source-to-axis of rotation distance and the source-to-detector distance were maintained constant at 65 and 100 cm, respectively, in all simulations. The ratio of the normalized glandular dose coefficient at each source position along the line scan to that for the circular scan, defined as relative normalized glandular dose coefficient (RD g N), was studied by varying the diameter of the breast at the chest wall, chest-wall to nipple distance, skin thickness, x-ray beam energy, and glandular fraction of the breast. Results: The RD g N metric when stated as a function of source position along the line scan, relative to the maximum length of line scan needed for data sufficiency, was found to be minimally dependent on breast diameter, chest-wall to nipple distance, skin thickness, glandular fraction, and x-ray photon energy. This observation facilitates easy estimation of the average glandular dose of the line scan. Polynomial fit equations for computing the RD g N and hence the average glandular dose are provided. Conclusions: For a breast CT system that acquires 300-500 projections over 2π for the circular scan, the addition of a line trajectory with equal

Single-photon sources for quantum technologies - Results of the joint research project SIQUTE

DEFF Research Database (Denmark)

Kück, S.; López, M.; Rodiek, B.

2017-01-01

In this presentation, the results of the joint research project “Single-Photon Sources for Quantum Technologies” (SIQUTE) [1] will be presented. The focus will be on the development of absolutely characterized single-photon sources, on the realization of an efficient waveguide-based single-photon......-photon source at the telecom wavelengths of 1.3 µm and 1.55 µm, on the implementation of the quantum-enhanced resolution in confocal fluorescence microscopy and on the development of a detector for very low photon fluxes...

Atlas of Skeletal SPECT/CT Clinical Images

International Nuclear Information System (INIS)

2016-01-01

The atlas focuses specifically on single photon emission computed tomography/computed tomography (SPECT/CT) in musculoskeletal imaging, and thus illustrates the inherent advantages of the combination of the metabolic and anatomical component in a single procedure. In addition, the atlas provides information on the usefulness of several sets of specific indications. The publication, which serves more as a training tool rather than a textbook, will help to further integrate the SPECT and CT experience in clinical practice by presenting a series of typical cases with many different patterns of SPECT/CT seen in bone scintigraphy

Dual energy CTA of the supraaortic arteries: Technical improvements with a novel dual source CT system

Energy Technology Data Exchange (ETDEWEB)

Lell, Michael M., E-mail: Michael.lell@uk-erlangen.de [Department of Radiology, University Erlangen, Maximiliansplatz 1, 91054 Erlangen (Germany); Hinkmann, Fabian [Department of Radiology, University Erlangen, Maximiliansplatz 1, 91054 Erlangen (Germany); Nkenke, Emeka [Department of Maxillofacial Surgery, University Erlangen (Germany); Schmidt, Bernhard [Bayer-Schering Healthcare, Berlin (Germany); Seidensticker, Peter [Siemens Healthcare, CT-Division, Forchheim (Germany); Kalender, Willi A. [Institute of Medical Physics, University Erlangen (Germany); Uder, Michael [Department of Radiology, University Erlangen, Maximiliansplatz 1, 91054 Erlangen (Germany); Achenbach, Stephan [Department of Cardiology, University Erlangen (Germany)

2010-11-15

Objectives: Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts. Materials and methods: Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140 kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1 = poor; 3 = excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n = 26) with a 5-point scale (1 = poor; 5 = excellent), CTA source data served as the reference. Results: Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries. Conclusions: Excellent bone suppression could be achieved, DE imaging with 100 and 140 kV lead to improved image quality and vessel integrity in the shoulder region than previously

Single-photon emission CT in the assessment of low back pain in young athletes

International Nuclear Information System (INIS)

Johnson, G.T.; Lagatutta, F.P.; Lazarus, M.L.; Faulkner, T.J.; Nolan, J.P.

1991-01-01

Fifty-two teenage and young adult athletes (ages 12-24 years) with low back pain (LBP) underwent routine lumbar radiography and bone scintigraphy including planar and single-photon CT and SPECT imaging. This paper illustrates the significant limitations of routine radiography and the importance of SPECT bone scintigraphy in evaluating young athletes with LBP and suspected spondylolysis; the increased sensitivity and specificity of SPECT compared to planar scintigraphy in the diagnosis of spondylolysis; and the potential utility of follow-up SPECT studies in evaluating success of therapy in athletes with initially positive diagnostic indicators for spondylolysis or impending spondylolysis

Geometrical co-calibration of a tomographic optical system with CT for intrinsically co-registered imaging

Energy Technology Data Exchange (ETDEWEB)

Cao Liji; Breithaupt, Mathies; Peter, Joerg [Division of Medical Physics in Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)], E-mail: l.cao@dkfz.de

2010-03-21

A mathematical approach for geometric co-calibration of a dual-modal small-animal imaging system is presented. The system comprises an optical imaging setup for in vivo bioluminescence and fluorescence detection, as well as an x-ray CT, both mounted on a common rotatable gantry enabling fully simultaneous imaging at axially overlapping fields-of-view. Geometric co-calibration is performed once by imaging a single cylindrical light-emitting source with both modalities over 360 deg. at two axial positions, respectively. Given the three-dimensional coordinates of the source positions in the reconstructed CT volume data along with their two-dimensional locations projected at the optical detector plane, the following intrinsic system parameters are calculated: (i) the intrinsic geometric parameters of the optical detection system-five parameters for each view and (ii) the relative positional relationship between the optical and CT systems-two parameters for each view. After co-calibration is performed, experimental studies using phantoms demonstrate the high degree of intrinsic positional accuracy between the optical and CT measurements. The most important advantage of this approach is that dual-modal data fusion is accomplished without any post-registration strategies.

Image quality and absorbed dose comparison of single- and dual-source cone-beam computed tomography.

Science.gov (United States)

Miura, Hideharu; Ozawa, Shuichi; Okazue, Toshiya; Kawakubo, Atsushi; Yamada, Kiyoshi; Nagata, Yasushi

2018-04-17

Dual-source cone-beam computed tomography (DCBCT) is currently available in the Vero4DRT image-guided radiotherapy system. We evaluated the image quality and absorbed dose for DCBCT and compared the values with those for single-source CBCT (SCBCT). Image uniformity, Hounsfield unit (HU) linearity, image contrast, and spatial resolution were evaluated using a Catphan phantom. The rotation angle for acquiring SCBCT and DCBCT images is 215° and 115°, respectively. The image uniformity was calculated using measurements obtained at the center and four peripheral positions. The HUs of seven materials inserted into the phantom were measured to evaluate HU linearity and image contrast. The Catphan phantom was scanned with a conventional CT scanner to measure the reference HU for each material. The spatial resolution was calculated using high-resolution pattern modules. Image quality was analyzed using ImageJ software ver. 1.49. The absorbed dose was measured using a 0.6-cm 3 ionization chamber with a 16-cm-diameter cylindrical phantom, at the center and four peripheral positions of the phantom, and calculated using weighted cone-beam CT dose index (CBCTDI w ). Compared with that of SCBCT, the image uniformity of DCBCT was slightly reduced. A strong linear correlation existed between the measured HU for DCBCT and the reference HU, although the linear regression slope was different from that of the reference HU. DCBCT had poorer image contrast than did SCBCT, particularly with a high-contrast material. There was no significant difference between the spatial resolutions of SCBCT and DCBCT. The absorbed dose for DCBCT was higher than that for SCBCT, because in DCBCT, the two x-ray projections overlap between 45° and 70°. We found that the image quality was poorer and the absorbed dose was higher for DCBCT than for SCBCT in the Vero4DRT. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of

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.

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.

Functional CT imaging: load-dependent visualization of the subchondral mineralization by means of CT osteoabsorptionmetry (CT-OAM)

International Nuclear Information System (INIS)

Linsenmaier, U.; Schlichtenhorst, K.; Pfeifer, K.J.; Reiser, M.; Kersting, S.; Putz, R.; Mueller-Gerbl, M.

2003-01-01

Purpose: Functional computed tomography for visualization and quantification of subchondral bone mineralization using CT osteoabsorptiometry (CT-OAM). Materials and Methods: Tarsometatarsal (TMT) and metatarsophalangeal (MTP) joints of 46 human hallux valgus (HV) specimens were examined (sagittal 1/1/1 mm) on a single slice CT scanner SCT (Somatom Plus 4, Siemens AG). Subchondral bone pixels were segmented and assigned to 10 density value groups (triangle 100 HU, range 200 - 1200 HU) the pixels using volume rendering technique (VRT). The data analysis considered the severity of HV as determined by the radiographically measured HV-angle (a.p. projection). Results: CT-OAM could generate reproducible densitograms of the distribution pattern of the subchondral bone density for all four joint surfaces (TMT and MTP joints). The bone density localization enables the assignment to different groups, showing a characteristic HV-angle-dependent distribution of the maximum bone mineralization of the load-dependent densitogram (p [de

Efficient fiber-coupled single-photon sources based on quantum dots

DEFF Research Database (Denmark)

Daveau, Raphaël Sura

refrigeration with coupled quantum wells. Many photonic quantum information processing applications would benet from a highbrightness, ber-coupled source of triggered single photons. This thesis presents a study of such sources based on quantum dots coupled to unidirectional photonic-crystal waveguide devices.......6 %. This latter method opens a promising future for increasing the eciency and reliability of planar chip-based single-photon sources. Refrigeration of a solid-state system with light has potential applications for cooling small-scale electronic and photonic circuits. We show theoretically that two coupled...... semiconductor quantum wells are ecient cooling media because they support long-lived indirect electron-hole pairs. These pairs can be thermally excited to distinct higher-energy states with faster radiative recombination, thereby creating an ecient escape channel to remove thermal energy from the system. From...

Ultra-high pitch chest computed tomography at 70 kVp tube voltage in an anthropomorphic pediatric phantom and non-sedated pediatric patients: Initial experience with 3rd generation dual-source CT.

Science.gov (United States)

Hagelstein, Claudia; Henzler, Thomas; Haubenreisser, Holger; Meyer, Mathias; Sudarski, Sonja; Schoenberg, Stefan O; Neff, K Wolfgang; Weis, Meike

2016-12-01

Minimizing radiation dose while at the same time preserving image quality is of particular importance in pediatric chest CT. Very recently, CT imaging with a tube voltage of 70 kVp has become clinically available. However, image noise is inversely proportional to the tube voltage. We aimed to investigate radiation dose and image quality of pediatric chest CT performed at 70 kVp in an anthropomorphic pediatric phantom as well as in clinical patients. An anthropomorphic pediatric phantom, which resembles a one-year-old child in physiognomy, was scanned on the 3 rd generation dual-source CT (DSCT) system at 70 kVp and 80 kVp and a fixed ultra low tube-current of 8 mAs to solely evaluate the impact of lowering tube voltage. After the phantom measurements, 18 pediatric patients (mean 29.5 months; range 1-91 months; 21 examinations) underwent 3.2 high-pitch chest CT on the same DSCT system at 70 kVp tube voltage without any sedation. Radiation dose and presence of motion artifacts was compared to a retrospectively identified patient cohort examined at 80 kVp on a 16-slice single-source-CT (SSCT; n=15; 14/15 with sedation; mean 30.7 months; range 0-96 months; pitch=1.5) or on a 2 nd generation DSCT without any sedation (n=6; mean 32.8 months; range 4-61 months; pitch=3.2). Radiation dose in the phantom scans was reduced by approximately 40% when using a tube voltage of 70 kVp instead of 80 kVp. In the pediatric patient group examined at 70 kVp age-specific effective dose (ED; mean 0.5±0.2 mSv) was significantly lower when compared to the retrospective cohort scanned at 80 kVp on the 16-slice-SSCT (mean ED: 1.0±0.3 mSv; pCT examinations showed any motion artifacts whereas 13/15 examinations of the retrospective patient cohort scanned at 80 kVp with a pitch of 1.5 showed motion artifacts. 3.2 high-pitch chest CT performed with 70 kVp significantly reduces radiation dose when compared to 80 kVp while at the same time provides good image quality without any motion artifacts

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

A prototype table-top inverse-geometry volumetric CT system

International Nuclear Information System (INIS)

Schmidt, Taly Gilat; Star-Lack, Josh; Bennett, N. Robert; Mazin, Samuel R.; Solomon, Edward G.; Fahrig, Rebecca; Pelc, Norbert J.

2006-01-01

A table-top volumetric CT system has been implemented that is able to image a 5-cm-thick volume in one circular scan with no cone-beam artifacts. The prototype inverse-geometry CT (IGCT) scanner consists of a large-area, scanned x-ray source and a detector array that is smaller in the transverse direction. The IGCT geometry provides sufficient volumetric sampling because the source and detector have the same axial, or slice direction, extent. This paper describes the implementation of the table-top IGCT scanner, which is based on the NexRay Scanning-Beam Digital X-ray system (NexRay, Inc., Los Gatos, CA) and an investigation of the system performance. The alignment and flat-field calibration procedures are described, along with a summary of the reconstruction algorithm. The resolution and noise performance of the prototype IGCT system are studied through experiments and further supported by analytical predictions and simulations. To study the presence of cone-beam artifacts, a ''Defrise'' phantom was scanned on both the prototype IGCT scanner and a micro CT system with a ±5 deg.cone angle for a 4.5-cm volume thickness. Images of inner ear specimens are presented and compared to those from clinical CT systems. Results showed that the prototype IGCT system has a 0.25-mm isotropic resolution and that noise comparable to that from a clinical scanner with equivalent spatial resolution is achievable. The measured MTF and noise values agreed reasonably well with theoretical predictions and computer simulations. The IGCT system was able to faithfully reconstruct the laminated pattern of the Defrise phantom while the micro CT system suffered severe cone-beam artifacts for the same object. The inner ear acquisition verified that the IGCT system can image a complex anatomical object, and the resulting images exhibited more high-resolution details than the clinical CT acquisition. Overall, the successful implementation of the prototype system supports the IGCT concept for

Room-Temperature Single-Photon Source for Secure Quantum Communication

Data.gov (United States)

National Aeronautics and Space Administration — We are asking for four years of support for PhD student Justin Winkler's work on a research project entitled "Room temperature single photon source for secure...

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

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.

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.

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.

The clinical application of PET/CT: a contemporary review

International Nuclear Information System (INIS)

Brady, Z.; Partridge, M.; Trapp, J.V.

2008-01-01

Full text: The combination of positron emission tomography (PET) scanners and x-ray computed tomography (CT) scanners into a single PET CT scanner has resulted in significant improvements in the diagnosis and staging of disease, particularly in the field of oncology. A decade on from the publication of the details of the first PET/CT scanner, we review the technology and applications of the modality. We examine the design aspects of combining two different imaging types into a single scanner, and the artefacts produced such as attenuation correction, motion and CT truncation artefacts. The article also provides a discussion and literature review of the applications of PET/CT to date, covering detection of tumours, radiotherapy treatment planning, patient management, and applications external to the field of oncology.

Propagation characteristics of audible noise generated by single corona source under positive DC voltage

Directory of Open Access Journals (Sweden)

Xuebao Li

2017-10-01

Full Text Available The directivity and lateral profile of corona-generated audible noise (AN from a single corona source are measured through experiments carried out in the semi-anechoic laboratory. The experimental results show that the waveform of corona-generated AN consists of a series of random sound pressure pulses whose pulse amplitudes decrease with the increase of measurement distance. A single corona source can be regarded as a non-directional AN source, and the A-weighted SPL (sound pressure level decreases 6 dB(A as doubling the measurement distance. Then, qualitative explanations for the rationality of treating the single corona source as a point source are given on the basis of the Ingard’s theory for sound generation in corona discharge. Furthermore, we take into consideration of the ground reflection and the air attenuation to reconstruct the propagation features of AN from the single corona source. The calculated results agree with the measurement well, which validates the propagation model. Finally, the influence of the ground reflection on the SPL is presented in the paper.

Sub-megahertz linewidth single photon source

Directory of Open Access Journals (Sweden)

Markus Rambach

2016-12-01

Full Text Available We report 100% duty cycle generation of sub-MHz single photon pairs at the rubidium D1 line using cavity-enhanced spontaneous parametric downconversion. The temporal intensity cross correlation function exhibits a bandwidth of 666±16 kHz for the single photons, an order of magnitude below the natural linewidth of the target transition. A half-wave plate inside our cavity helps to achieve triple resonance between pump, signal, and idler photon, reducing the bandwidth and simplifying the locking scheme. Additionally, stabilisation of the cavity to the pump frequency enables the 100% duty cycle. The quantum nature of the source is confirmed by the idler-triggered second-order autocorrelation function at τ=0 to be gs,s(2(0= 0.016±0.002 for a heralding rate of 5 kHz. The generated photons are well-suited for storage in quantum memory schemes with sub-natural linewidths, such as gradient echo memories.

Stable single-photon source in the near infrared

International Nuclear Information System (INIS)

Gaebel, T; Popa, I; Gruber, A; Domhan, M; Jelezko, F; Wrachtrup, J

2004-01-01

Owing to their unsurpassed photostability, defects in solids may be ideal candidates for single-photon sources. Here we report on generation of single photons by optical excitation of a yet unexplored defect in diamond, the nickel-nitrogen complex (NE8) centre. The most striking feature of the defect is its emission bandwidth of 1.2 nm at room temperature. The emission wavelength of the defect is around 800 nm, which is suitable for telecom fibres. In addition, in this spectral region little background light from the diamond bulk material is detected. Consequently, a high contrast in antibunching measurements is achieved

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...

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)

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.

CT of submandibular gland sialolithiasis

International Nuclear Information System (INIS)

Avrahami, E.; Englender, M.; Chen, E.; Shabtay, D.; Katz, R.; Harell, M.

1996-01-01

We emphasise the importance of high-resolution CT with reconstruction in the demonstration of submandibular gland (SMG) sialolithiasis and its role in monitoring treatment. We studied 76 patients with swollen and tender SMG, some with fever. They underwent conventional radiography, sonography (US) and high-resolution CT with reconstructions. Conventional radiographs demonstrated single stones in 29 patients. Axial CT, before reconstructions, demonstrated single stones in 63 patients and multiple stones in another 5. Following CT reconstructions, multiple stones were demonstrated in 37 patients. On US stones were diagnosed in only 33 patients, and multiple stones in only 1. All 68 patients with stones shown on imaging and 2 without stones underwent surgery, with good clinical results. Total removal of the SMG and its duct was performed in patients with multiple stones, chronic inflammatory changes in the SMG, or a solitary stone in the SMG or deep in the duct. A small incision for removal of a solitary stone in the distal aspects of Wharton's duct was performed in 15 patients, with excellent clinical results. Another 14 patients with multiple salivary glad stones, diagnosed on CT reconstructions, did not improve following this procedure and needed further surgery; clinical improvement occurred following excision of the SMG and Wharton's duct. Histological examination in all of these confirmed the presence of additional stones. Conservative anti-inflammatory treatment was recommended for 6 patients in whom CT reconstructions did not demonstrate stones. (orig.)

CT-Urography; Urografia CT

Energy Technology Data Exchange (ETDEWEB)

Dalla Palma, Ludovico; Grotto, Maurizio [Trieste Univ., Trieste (Italy). Dipartimento di scienze cliniche, morfologiche e tecnologiche, UCO di radiologia; Morra, Aldo [CRO, Aviano (Italy). Reparto di radiologia

2005-09-15

In this paper we present an overview of CT-Urography. With the advent of multislice CT scanners and the evolution of image processing methods this technique now affords optimal urographic images comparable to those obtained with conventional techniques. We describe the acquisition techniques and protocols used by the various authors. Effective radiation dose has conditioned the use of CT-Urography so that the tendency today is to reduce the number of scans by performing, after the non enhanced scan, a single contrast-enhanced scan comprising both the nephrographic and urographic phase. With the use of multislice CT the quality of the urogram improves with the number of slices. We illustrate a variety of processing techniques, multiplanar reconstruction (MPR), maximum (MIP) and average intensity projection (AIP) and volume rendering (VR) and present a series of upper urinary tract tumours testifying to the superiority of the AIP technique over MIP. We then review the results of comparative studies of CT-Urography with conventional urography in upper urinary tract diagnostics. Finally, we describe the advantages and limitations of CT-Urography. [Italian] Gli Autori presentano una panoramica sulla Urografia TC (Uro TC). L'avvento della TC multistrato e l'evoluzione delle tecniche di elaborazione consentono di ottenere dei quadri urografici ottimali comparativi con quelli convenzionali. Vengono ricordate le varie tecniche di acquisizione e i protocolli usati dai vari Autori. La dose effettiva di radiazioni ha rappresentato uno dei fattori condizionanti per cui oggi prevale l'orientamento di ridurre il numero di scansioni, considerando dopo la scansione senza mezzo di contrasto un'unica scansione contrasto grafica comprendente sia la fase nefrografica che quella urografica. Con l'uso della TC multistrato la qualita dell'urogramma migliora con l'aumento del numero degli strati. Vengono descritte le varie tecniche di elaborazione, la

Single photon ECT

International Nuclear Information System (INIS)

Maeda, Toshio; Matsuda, Hiroshi; Tada, Akira; Bunko, Hisashi; Koizumi, Kiyoshi

1982-01-01

The detectability of lesions located deep in a body or overlapped with a physiologically increased activity improve with the help of single photon ECT. In some cases, the ECT is superior to the conventional gamma camera images and X-ray CT scans in the evaluation of the location and size of lesion. The single photon ECT of the brain compares favorably with the contrast enhansed X-ray CT scans. The most important adaptation of the single photon ECT are the detection of recurrent brain tumors after craniotomy and the evaluation of ischemic heart diseases. (author)

CT-guided transthoracic cutting needle biopsy of intrathoracic lesions: Comparison between coaxial and single needle technique

International Nuclear Information System (INIS)

Wu, Reng-Hong; Tzeng, Wen-Sheng; Lee, Wei-Jing; Chang, Shih-Chin; Chen, Chia-Huei; Fung, Jui-Lung; Wang, Yen-Jen; Mak, Chee-Wai

2012-01-01

Purpose: To evaluate the complication rates and diagnostic accuracy of two different CT-guided transthoracic cutting needle biopsy techniques: coaxial method and single needle method. Methods: This study involved 198 consecutive subjects with 198 intrathoracic lesions. The first 98 consecutive subjects received a single needle cutting technique and the next 100 consecutive subjects received a coaxial technique. Both groups were compared in relation the diagnostic accuracy and complication rates. Results: No significant difference was found between the two groups concerning patient characteristics, lesions and procedure variables. There was a borderline statistical difference in the incidence of pneumothorax at within 24-h post biopsy between patients in the single needle group (5%) and the coaxial group (13%) (P = 0.053). Little difference was found in the pneumothorax rate at immediately post biopsy between the two groups, which was 28% in the single needle group and 31% in the coaxial group. There was no significant difference in the hemoptysis rate between the two groups, which was 9.2% in the single needle group and 11% in the coaxial group. Both techniques yielded an overall diagnostic accuracy of 98% for malignant lesions with similar sensitivity (single needle: 96.9% vs. coaxial: 96.4%) and specificity (single needle: 100% vs. coaxial: 100%). Conclusion: There is little difference in the pneumothorax rates and bleeding complications between patients who either received a single needle or a coaxial transthoracic cutting biopsy. Both techniques produce an overall diagnostic accuracy of 98% for malignant lesions.

Multi-slice CT for visualization of acute pulmonary embolism: single breath-hold subtraction technique

International Nuclear Information System (INIS)

Wildberger, J.E.; Mahnken, A.H.; Spuentrup, E.; Guenther, R.W.; Klotz, E.; Ditt, H.

2005-01-01

Purpose: the purpose of our preliminary animal study was to evaluate the feasibility of a new subtraction technique for visualization of perfusion defects within the lung parenchyma in segmental and subsegmental pulmonary embolism (PE). Materials and methods: in three healthy pigs, PE were artificially induced by fresh human clot material. Within a single breath-hold, CT angiography (CTA) was performed on a 16-slice multi-slice CT scanner (SOMATOM Sensation 16; Siemens, Forchheim, Germany) before and after intravenous application of 80 mL of contrast-medium, followed by a saline chaser. Scan parameters were 120 kV and 100 mAs eff. , using a collimation of 16 x 1.5 mm and a table speed/rot. of 36 mm (pitch: 1.5; rotation time: 0.5 s). A new 3D subtraction technique was developed, which is based on automated segmentation, non-linear spatial filtering and non-rigid registration. Data were analysed using a color-encoded ''compound view'' of parenchymal enhancement and CTA information displayed in axial, coronal and sagittal orientation. Results: subtraction was technically feasible in all three data sets. The mean scan time for each series was 4.7 s, interscan delay was 14.7 s, respectively. Therefore, an average breath-hold of approximately 24 s was required for the overall scanning procedure. Downstream of occluded segmental and subsegmental arteries, perfusion defects were clearly assessable, showing lower or missing enhancement compared to normally perfused lung parenchyma. In all pigs, additional peripheral areas with triangular shaped perfusion defects were delineated, considered typical for PE. Conclusions: our initial results from the animal model studied slow that perfusion imaging of PE is feasible within a single breath-hold. It allows a comprehensive assessment of perfusion deficits as the direct proof of a pulmonary embolus, can be combined with an indirect visual quantification of the density changes in the adjacent lung tissue. (orig.)

Overranging at multisection CT: an underestimated source of excess radiation exposure.

NARCIS (Netherlands)

Schilham, A.; Molen, A.J. van der; Prokop, M.; Jong, H.W. de

2010-01-01

To reconstruct the first and last sections of a helical computed tomographic (CT) scan, the scan length is automatically extended beyond the planned image boundaries, a phenomenon known as overranging. With common 16-section CT scanning protocols, the overrange length is between 3 and 6 cm. For

Incorporating multislice imaging into x-ray CT polymer gel dosimetry

Energy Technology Data Exchange (ETDEWEB)

Johnston, H., E-mail: holly.johnston@utsw.edu [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2 (Canada); Hilts, M. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada and Medical Physics, BC Cancer Agency, Vancouver Island Centre, Victoria, British Columbia V8R 6V5 (Canada); Jirasek, A. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada and Department of Physics, University of British Columbia—Okanagan Campus, Kelowna, British Columbia V1V 1V7 (Canada)

2015-04-15

Purpose: To evaluate multislice computed tomography (CT) scanning for fast and reliable readout of radiation therapy (RT) dose distributions using CT polymer gel dosimetry (PGD) and to establish a baseline assessment of image noise and uniformity in an unirradiated gel dosimeter. Methods: A 16-slice CT scanner was used to acquire images through a 1 L cylinder filled with water. Additional images were collected using a single slice machine. The variability in CT number (N{sub CT}) associated with the anode heel effect was evaluated and used to define a new slice-by-slice background subtraction artifact removal technique for CT PGD. Image quality was assessed for the multislice system by evaluating image noise and uniformity. The agreement in N{sub CT} for slices acquired simultaneously using the multislice detector array was also examined. Further study was performed to assess the effects of increasing x-ray tube load on the constancy of measured N{sub CT} and overall scan time. In all cases, results were compared to the single slice machine. Finally, images were collected throughout the volume of an unirradiated gel dosimeter to quantify image noise and uniformity before radiation is delivered. Results: Slice-by-slice background subtraction effectively removes the variability in N{sub CT} observed across images acquired simultaneously using the multislice scanner and is the recommended background subtraction method when using a multislice CT system. Image noise was higher for the multislice system compared to the single slice scanner, but overall image quality was comparable between the two systems. Further study showed N{sub CT} was consistent across image slices acquired simultaneously using the multislice detector array for each detector configuration of the slice thicknesses examined. In addition, the multislice system was found to eliminate variations in N{sub CT} due to increasing x-ray tube load and reduce scanning time by a factor of 4 when compared to

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

An incidentally found inflamed uterine myoma Causing low abdominal pain, using TC-99m-tektrotyd single photon emission computed tomography-CT hybrid imaging

Energy Technology Data Exchange (ETDEWEB)

Zandieh, Shahin; Schuetz, Matthias; Bernt, Reinhard; Zwerina, Jochen; Haller, Joerg [Hanusch-Hospital, Teaching Hospital of Medical University of Vienna, Vienna (Australia)

2013-10-15

We report the case of a 50-year-old woman presented with a history of right hemicolectomy due to an ileocecal neuroendocrine tumor and left breast metastasis. Owing to a slightly elevated chromogranin A-level and lower abdominal pain, single photon emission computed tomography-computer tomography (SPECT-CT) was performed. There were no signs of recurrence on the SPECT-CT scan, but the patient was incidentally found to have an inflamed intramural myoma. We believe that the slightly elevated chromogranin A-level was caused by the hypertension that the patient presented. In the clinical context, this is a report of an inflamed uterine myoma seen as a false positive result detected by TC-99m-Tc-EDDA/HYNIC-Tyr3-Octreotide (Tektrotyd) SPECT-CT hybrid imaging.

CT of tracheal agenesis

International Nuclear Information System (INIS)

Strouse, Peter J.; Hernandez, Ramiro J.; Newman, Beverley

2006-01-01

Tracheal agenesis is a rare and usually lethal anomaly. In the past, opaque contrast medium was injected via the esophagus to demonstrate the anatomy. To demonstrate the utility of helical and multidetector CT in delineating the aberrant anatomy in newborns with tracheal agenesis. Four newborns with tracheal agenesis were identified from three institutions. Imaging studies and medical records were reviewed. Each child was imaged with chest radiography. One child was imaged on a single-detector helical CT scanner and the other three on multidetector scanners. Helical and multidetector CT with 2D and 3D reconstructions clearly delineated the aberrant tracheobronchial and esophageal anatomy in each infant. Minimum intensity projection reformatted CT images were particularly helpful. One infant each had type I and type II tracheal agenesis. Two infants had type III tracheal agenesis. All four infants died. CT is a useful tool for delineating the aberrant anatomy of newborns with tracheal agenesis and thus helps in making rational clinical decisions. (orig.)

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.)

Localizing gravitational wave sources with single-baseline atom interferometers

Science.gov (United States)

Graham, Peter W.; Jung, Sunghoon

2018-02-01

Localizing sources on the sky is crucial for realizing the full potential of gravitational waves for astronomy, astrophysics, and cosmology. We show that the midfrequency band, roughly 0.03 to 10 Hz, has significant potential for angular localization. The angular location is measured through the changing Doppler shift as the detector orbits the Sun. This band maximizes the effect since these are the highest frequencies in which sources live for several months. Atom interferometer detectors can observe in the midfrequency band, and even with just a single baseline they can exploit this effect for sensitive angular localization. The single-baseline orbits around the Earth and the Sun, causing it to reorient and change position significantly during the lifetime of the source, and making it similar to having multiple baselines/detectors. For example, atomic detectors could predict the location of upcoming black hole or neutron star merger events with sufficient accuracy to allow optical and other electromagnetic telescopes to observe these events simultaneously. Thus, midband atomic detectors are complementary to other gravitational wave detectors and will help complete the observation of a broad range of the gravitational spectrum.

Prediction of postoperative pulmonary function. Preliminary comparison of single-breath dual-energy xenon CT with three conventional methods

International Nuclear Information System (INIS)

Yanagita, Hisami; Honda, Norinari; Nakayama, Mitsuo

2013-01-01

The purpose of this study was to assess the use of xenon ventilation maps (Xe-images) for predicting postoperative pulmonary function. After study approval by the institutional review board, written informed consent was obtained from 30 patients with lung tumors who underwent pre- and postoperative spirometry, pulmonary perfusion single photon emission computed tomography (SPECT) and dual-energy CT (80 kV and 140 kV/Sn) after single-breath inspiration of 35% xenon. Xe-images were calculated by three-material decomposition. Sum of pixel values of the part to be resected (A) and of the whole lung (B) on Xe-images or lung perfusion SPECT, and volumes or the number of segments of the part to be resected (A) and of the whole lung (B) on Xe-images were enumerated, respectively. We multiplied (1-A/B) by each preoperative value from spirometry for prediction. Predictions by each of the four methods were compared with postoperative values. Predicted values for vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV 1 ) by the four methods regressed significantly with measured values (R 2 =0.56-0.77, p 1 with accuracy comparable to that of CT volumetry. (author)

Demonstration of acoustic source localization in air using single pixel compressive imaging

Science.gov (United States)

Rogers, Jeffrey S.; Rohde, Charles A.; Guild, Matthew D.; Naify, Christina J.; Martin, Theodore P.; Orris, Gregory J.

2017-12-01

Acoustic source localization often relies on large sensor arrays that can be electronically complex and have large data storage requirements to process element level data. Recently, the concept of a single-pixel-imager has garnered interest in the electromagnetics literature due to its ability to form high quality images with a single receiver paired with shaped aperture screens that allow for the collection of spatially orthogonal measurements. Here, we present a method for creating an acoustic analog to the single-pixel-imager found in electromagnetics for the purpose of source localization. Additionally, diffraction is considered to account for screen openings comparable to the acoustic wavelength. A diffraction model is presented and incorporated into the single pixel framework. In this paper, we explore the possibility of applying single pixel localization to acoustic measurements. The method is experimentally validated with laboratory measurements made in an air waveguide.

Quantification of coronary artery stenoses. Comparison of 64-slice and dual source CT angiography with cardiac catheterization

International Nuclear Information System (INIS)

Busch, Stephanie; Nikolaou, K.; Johnson, T.; Rist, C.; Knez, A.; Reiser, M.; Becker, C.

2007-01-01

Until now stenoses of the coronary arteries have been evaluated visually with CT angiography. Therefore, the results were highly dependent on subjective factors inherent in the examiner. New software tools for semiquantitative analysis (CT-QCA, quantitative coronary assessment) might be adequate to improve the diagnostic accuracy und reproducibility. CTAs of 20 patients were analyzed. Ten patients each were evaluated using 64-slice CT (64SCT) and dual source CT (DSCT) (Somatom Sensation 64 and Somatom Definition, Siemens Medical Solutions, Forchheim), respectively. Two radiologists independently evaluated the data visually and with the help of a software tool (Syngo Circulation, Siemens Medical Solutions, Forchheim). The results of the quantitative assessment of the invasive heart catheterization served as the reference standard. Sensitivity and specificity as well as the correlation coefficient, the systematic error, and the interobserver agreement (kappa) were determined. In each of both patient groups 12 stenoses were detected. For the detection of stenoses >75%, sensitivity and specificity for the visual evaluation using the 64SCT were 100% and 90%, and with the CT-QCA both were 100%. For the DSCT sensitivity and specificity were 100% for both the visual and semiautomated evaluation. The Bland-Altman plot of the results of the 64SCT showed an overestimation of 3.3% (±62.7%/56.2%) compared to the heart catheterization. The results of the DSCT exhibited an overestimation of 6.2% (±33.1%/19.8%). The interobserver agreement of the CT-QCA and the visual evaluation showed a kappa value of 0.75 and for DSCT of 1.0. The results showed a good correlation of grading stenosis between the software-assisted evaluation and the results of the coronary catheter angiography. The promising results of the DSCT are due to a superior temporal resolution compared to the 64SCT. Confirmation of these data by trials in larger patient collectives is warranted. (orig.) [de

Single-source mechanical loading system produces biaxial stresses in cylinders

Science.gov (United States)

Flower, J. F.; Stafford, R. L.

1967-01-01

Single-source mechanical loading system proportions axial-to-hoop tension loads applied to cylindrical specimens. The system consists of hydraulic, pneumatic, and lever arrangements which produce biaxial loading ratios.

An Oblivious O(1)-Approximation for Single Source Buy-at-Bulk

KAUST Repository

Goel, Ashish; Post, Ian

2009-01-01

We consider the single-source (or single-sink) buy-at-bulk problem with an unknown concave cost function. We want to route a set of demands along a graph to or from a designated root node, and the cost of routing x units of flow along an edge

76 FR 31964 - Announcement of the Award of Nine Single-Source Expansion Supplement Grants

Science.gov (United States)

2011-06-02

... the Award of Nine Single-Source Expansion Supplement Grants AGENCY: Office of Refugee Resettlement, ACF, HHS. ACTION: Notice to announce the award of nine single-source expansion supplement grants to.... Maintaining Funding Level of Matching Grant Program (a) Maintaining Funding Level--Subject to the availability...

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.

MICROORGANISMS: A MARVELOUS SOURCE OF SINGLE CELL PROTEINS

Directory of Open Access Journals (Sweden)

Agam Nangul

2013-08-01

Full Text Available The increasing global population living below the poverty line is driving the scientific community to search for non-conventional protein sources that can replace conventional expensive ones. Microbial proteins, or single-cell protein (SCP, represent a potential future nutrient source for human food and animal feed. These microbial proteins can be grown rapidly on substrates with minimum dependence on soil, water and climate conditions. They can be produced from algae, fungi and bacteria the chief sources of SCP. It is convenient to use microorganisms for production of SCP as they grow rapidly and have high protein content. Industrially, they can be produced from algal biomass, yeast, fungi. There are several other ways of getting SCP as well. Despite numerous advantages of SCP, they have disadvantages and toxic effects too, especially related to mycotoxins and bacterial toxins.

Comparison of {sup 131}I whole-body imaging, {sup 131}I SPECT/CT, and {sup 18}F-FDG PET/CT in the detection of metastatic thyroid cancer

Energy Technology Data Exchange (ETDEWEB)

Oh, Jong-Ryool; Chong, Ari; Kim, Jahae; Kang, Sae-Ryung; Song, Ho-Chun; Bom, Hee-Seung [Chonnam National University Hospital, Department of Nuclear Medicine, Clinical Medicine Research Center, Gwangju (Korea, Republic of); Byun, Byung-Hyun; Hong, Sun-Pyo; Yoo, Su-Woong [Chonnam National University Hwasun Hospital, Department of Nuclear Medicine, Clinical Medicine Research Center, Hwasun, Jeonnam (Korea, Republic of); Kim, Dong-Yeon [Dongguk University, Department of Chemistry, Seoul (Korea, Republic of); Chonnam National University Hospital, Department of Nuclear Medicine, Clinical Medicine Research Center, Gwangju (Korea, Republic of); Min, Jung-Joon [Chonnam National University Hwasun Hospital, Department of Nuclear Medicine, Clinical Medicine Research Center, Hwasun, Jeonnam (Korea, Republic of); Center for Biomedical Human Resources at Chonnam National University, Brain Korea 21 Project, Gwangju (Korea, Republic of)

2011-08-15

The aim of this study was to compare {sup 131}I whole-body scintigraphy (WBS), WBS with {sup 131}I single photon emission computed tomography/computed tomography (SPECT/CT), and {sup 18}F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the detection of distant metastases of differentiated thyroid cancer (DTC). A total of 140 patients with 258 foci of suspected distant metastases were evaluated. {sup 131}I WBS, {sup 131}I SPECT/CT, and {sup 18}F-FDG PET/CT images were interpreted separately. The final diagnosis was obtained from histopathologic study, serum thyroglobulin level, other imaging modalities, and/or clinical follow-up. Of the 140 patients with 258 foci, 46 patients with 166 foci were diagnosed as positive for distant metastasis. The sensitivity, specificity, and diagnostic accuracy of each imaging modality were 65, 55, and 59%, respectively, for {sup 131}I WBS; 65, 95, and 85% for {sup 131}I SPECT/CT, respectively; and 61, 98, and 86%, respectively, for {sup 18}F-FDG PET/CT in patient-based analyses. Lesion-based analyses demonstrated that both SPECT/CT and PET/CT were superior to WBS (p<0.001) in all patient groups. SPECT/CT was superior to WBS and PET/CT (p<0.001) in patients who received a single challenge of radioiodine therapy, whereas PET/CT was superior to WBS (p=0.005) and SPECT/CT (p=0.013) in patients who received multiple challenges. Both SPECT/CT and PET/CT demonstrated high diagnostic performance in detecting metastatic thyroid cancer. SPECT/CT was highly accurate in patients who underwent a single challenge of radioiodine therapy. In contrast, {sup 18}F-FDG PET/CT presented the highest diagnostic performance in patients who underwent multiple challenges of radioiodine therapy. (orig.)

Intervertebral anticollision constraints improve out-of-plane translation accuracy of a single-plane fluoroscopy-to-CT registration method for measuring spinal motion

International Nuclear Information System (INIS)

Lin, Cheng-Chung; Tsai, Tsung-Yuan; Hsu, Shih-Jung; Lu, Tung-Wu; Shih, Ting-Fang; Wang, Ting-Ming

2013-01-01

Purpose: The study aimed to propose a new single-plane fluoroscopy-to-CT registration method integrated with intervertebral anticollision constraints for measuring three-dimensional (3D) intervertebral kinematics of the spine; and to evaluate the performance of the method without anticollision and with three variations of the anticollision constraints via an in vitro experiment. Methods: The proposed fluoroscopy-to-CT registration approach, called the weighted edge-matching with anticollision (WEMAC) method, was based on the integration of geometrical anticollision constraints for adjacent vertebrae and the weighted edge-matching score (WEMS) method that matched the digitally reconstructed radiographs of the CT models of the vertebrae and the measured single-plane fluoroscopy images. Three variations of the anticollision constraints, namely, T-DOF, R-DOF, and A-DOF methods, were proposed. An in vitro experiment using four porcine cervical spines in different postures was performed to evaluate the performance of the WEMS and the WEMAC methods. Results: The WEMS method gave high precision and small bias in all components for both vertebral pose and intervertebral pose measurements, except for relatively large errors for the out-of-plane translation component. The WEMAC method successfully reduced the out-of-plane translation errors for intervertebral kinematic measurements while keeping the measurement accuracies for the other five degrees of freedom (DOF) more or less unaltered. The means (standard deviations) of the out-of-plane translational errors were less than −0.5 (0.6) and −0.3 (0.8) mm for the T-DOF method and the R-DOF method, respectively. Conclusions: The proposed single-plane fluoroscopy-to-CT registration method reduced the out-of-plane translation errors for intervertebral kinematic measurements while keeping the measurement accuracies for the other five DOF more or less unaltered. With the submillimeter and subdegree accuracy, the WEMAC method was

Impact of CT in patients with sepsis of unknown origin

International Nuclear Information System (INIS)

Barkhausen, J.; Stoeblen, F.; Mueller, R.D.

1999-01-01

Purpose: To evaluate the diagnostic relevance of CT in patients with sepsis of unknown origin. Material and Methods: Sixty-three consecutive intensive care patients with suspicion of an abscess and negative or inconclusive previous radiological examinations were included. CT was performed using the helical technique. A total of 45 abdominal and 38 chest examinations were evaluated. Results: 5/38 examinations of the chest revealed the source of sepsis (pleural empyema 2, lung abscess 1, mediastinitis 1, retrosternal abscess 1). 7/45 abdominal CT examinations showed the source of sepsis (intraabdominal abscess 2, hepatic abscess 3, intestinal perforation 1, gangrenous colitis 1). Conclusion: CT is useful for the evaluation of patients with fever or sepsis without a known source. Due to the detection of a spetic focus by CT, 19% of the patients in our study could be immediately referred to causal therapy as percutaneous drainage or surgery. (orig.)

Impact of CT in patients with sepsis of unknown origin

Energy Technology Data Exchange (ETDEWEB)

Barkhausen, J.; Stoeblen, F.; Mueller, R.D. [University Hospital Essen (Germany). Dept. of Radiology; Dominguez-Fernandez, E. [University Hospital Essen (Germany). Dept. of General Surgery; Henseke, P. [Nycomed-Amersham Arzneimittel GmbH, Muenchen (Germany)

1999-09-01

Purpose: To evaluate the diagnostic relevance of CT in patients with sepsis of unknown origin. Material and Methods: Sixty-three consecutive intensive care patients with suspicion of an abscess and negative or inconclusive previous radiological examinations were included. CT was performed using the helical technique. A total of 45 abdominal and 38 chest examinations were evaluated. Results: 5/38 examinations of the chest revealed the source of sepsis (pleural empyema 2, lung abscess 1, mediastinitis 1, retrosternal abscess 1). 7/45 abdominal CT examinations showed the source of sepsis (intraabdominal abscess 2, hepatic abscess 3, intestinal perforation 1, gangrenous colitis 1). Conclusion: CT is useful for the evaluation of patients with fever or sepsis without a known source. Due to the detection of a spetic focus by CT, 19% of the patients in our study could be immediately referred to causal therapy as percutaneous drainage or surgery. (orig.)

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.

FDG-PET/CT in oncology. German guideline

International Nuclear Information System (INIS)

Krause, B.J.; Beyer, T.; Bockisch, A.; Delbeke, D.; Kotzerke, J.; Minkov, V.; Reiser, M.; Willich, N.

2007-01-01

FDG-PET/CT examinations combine metabolic and morphologic imaging within an integrated procedure. Over the past decade PET/CT imaging has gained wide clinical acceptance in the field of oncology. This FDG-PET/CT guideline focuses on indications, data acquisition and processing as well as documentation of FDG-PET/CT examinations in oncologic patients within a clinical and social context specific to Germany. Background information and definitions are followed by examples of clinical and research applications of FDG-PET/CT. Furthermore, protocols for CT scanning (low dose and contrast-enhanced CT) and PET emission imaging are discussed. Documentation and reporting of examinations are specified. Image interpretation criteria and sources of errors are discussed. Quality control for FDG and PET/CT-systems, qualification requirements of personnel as well as legal aspects are presented. (orig.)

Time-domain single-source integral equations for analyzing scattering from homogeneous penetrable objects

KAUST Repository

Valdés, Felipe

2013-03-01

Single-source time-domain electric-and magnetic-field integral equations for analyzing scattering from homogeneous penetrable objects are presented. Their temporal discretization is effected by using shifted piecewise polynomial temporal basis functions and a collocation testing procedure, thus allowing for a marching-on-in-time (MOT) solution scheme. Unlike dual-source formulations, single-source equations involve space-time domain operator products, for which spatial discretization techniques developed for standalone operators do not apply. Here, the spatial discretization of the single-source time-domain integral equations is achieved by using the high-order divergence-conforming basis functions developed by Graglia alongside the high-order divergence-and quasi curl-conforming (DQCC) basis functions of Valdés The combination of these two sets allows for a well-conditioned mapping from div-to curl-conforming function spaces that fully respects the space-mapping properties of the space-time operators involved. Numerical results corroborate the fact that the proposed procedure guarantees accuracy and stability of the MOT scheme. © 2012 IEEE.

Single-Session CT-Guided Percutaneous Microwave Ablation of Bilateral Adrenal Gland Hyperplasia Due to Ectopic ACTH Syndrome

International Nuclear Information System (INIS)

Sarma, Asha; Shyn, Paul B.; Vivian, Mark A.; Ng, Ju-Mei; Tuncali, Kemal; Lorch, Jorchen H.; Zaheer, Sarah N.; Gordon, Michael S.; Silverman, Stuart G.

2015-01-01

Bilateral adrenalectomy is currently the only available treatment for adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome (ectopic ACTH syndrome) that is refractory to pharmacologic therapy. We describe two patients with refractory ectopic ACTH syndrome who were treated with CT-guided percutaneous microwave ablation of both hyperplastic adrenal glands in a single session: One was not a surgical candidate, and the other had undergone unsuccessful surgery. Following the procedure, both patients achieved substantial decreases in serum cortisol, symptomatic improvement, and decreased anti-hypertensive medication requirements

Single-Session CT-Guided Percutaneous Microwave Ablation of Bilateral Adrenal Gland Hyperplasia Due to Ectopic ACTH Syndrome

Energy Technology Data Exchange (ETDEWEB)

Sarma, Asha, E-mail: ashasarma@gmail.com; Shyn, Paul B., E-mail: pshyn@partners.org [Brigham and Women’s Hospital, Department of Radiology (United States); Vivian, Mark A. [University of Manitoba, Department of Radiology (Canada); Ng, Ju-Mei [Brigham and Women’s Hospital, Department of Anesthesiology (United States); Tuncali, Kemal [Brigham and Women’s Hospital, Department of Radiology (United States); Lorch, Jorchen H. [Dana Farber Cancer Institute, Department of Medicine (United States); Zaheer, Sarah N.; Gordon, Michael S. [Brigham and Women’s Hospital, Department of Endocrinology (United States); Silverman, Stuart G. [Brigham and Women’s Hospital, Department of Radiology (United States)

2015-10-15

Bilateral adrenalectomy is currently the only available treatment for adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome (ectopic ACTH syndrome) that is refractory to pharmacologic therapy. We describe two patients with refractory ectopic ACTH syndrome who were treated with CT-guided percutaneous microwave ablation of both hyperplastic adrenal glands in a single session: One was not a surgical candidate, and the other had undergone unsuccessful surgery. Following the procedure, both patients achieved substantial decreases in serum cortisol, symptomatic improvement, and decreased anti-hypertensive medication requirements.

Alberta Stroke Program Early CT Score applied to CT angiography source images is a strong predictor of futile recanalization in acute ischemic stroke

International Nuclear Information System (INIS)

Kawiorski, Michal M.; Alonso de Lecinana, Maria; Martinez-Sanchez, Patricia; Fuentes, Blanca; Sanz-Cuesta, Borja E.; Marin, Begona; Ruiz-Ares, Gerardo; Diez-Tejedor, Exuperio; Garcia-Pastor, Andres; Diaz-Otero, Fernando; Calleja, Patricia; Lourido, Daniel; Vicente, Agustina; Fandino, Eduardo; Sierra-Hidalgo, Fernando

2016-01-01

Reliable predictors of poor clinical outcome despite successful revascularization might help select patients with acute ischemic stroke for thrombectomy. We sought to determine whether baseline Alberta Stroke Program Early CT Score (ASPECTS) applied to CT angiography source images (CTA-SI) is useful in predicting futile recanalization. Data are from the FUN-TPA study registry (ClinicalTrials.gov; NCT02164357) including patients with acute ischemic stroke due to proximal arterial occlusion in anterior circulation, undergoing reperfusion therapies. Baseline non-contrast CT and CTA-SI-ASPECTS, time-lapse to image acquisition, occurrence, and timing of recanalization were recorded. Outcome measures were NIHSS at 24 h, symptomatic intracranial hemorrhage, modified Rankin scale score, and mortality at 90 days. Futile recanalization was defined when successful recanalization was associated with poor functional outcome (death or disability). Included were 110 patients, baseline NIHSS 17 (IQR 12; 20), treated with intravenous thrombolysis (IVT; 45 %), primary mechanical thrombectomy (MT; 16 %), or combined IVT + MT (39 %). Recanalization rate was 71 %, median delay of 287 min (225; 357). Recanalization was futile in 28 % of cases. In an adjusted model, baseline CTA-SI-ASPECTS was inversely related to the odds of futile recanalization (OR 0.5; 95 % CI 0.3-0.7), whereas NCCT-ASPECTS was not (OR 0.8; 95 % CI 0.5-1.2). A score ≤5 in CTA-SI-ASPECTS was the best cut-off to predict futile recanalization (sensitivity 35 %; specificity 97 %; positive predictive value 86 %; negative predictive value 77 %). CTA-SI-ASPECTS strongly predicts futile recanalization and could be a valuable tool for treatment decisions regarding the indication of revascularization therapies. (orig.)

Alberta Stroke Program Early CT Score applied to CT angiography source images is a strong predictor of futile recanalization in acute ischemic stroke

Energy Technology Data Exchange (ETDEWEB)

Kawiorski, Michal M.; Alonso de Lecinana, Maria [Hospital Universitario La Paz, IdiPAZ, Universidad Autonoma de Madrid, Madrid (Spain); Hospital Universitario Ramon y Cajal, IRYCIS, Universidad de Alcala de Henares, Madrid (Spain); Martinez-Sanchez, Patricia; Fuentes, Blanca; Sanz-Cuesta, Borja E.; Marin, Begona; Ruiz-Ares, Gerardo; Diez-Tejedor, Exuperio [Hospital Universitario La Paz, IdiPAZ, Universidad Autonoma de Madrid, Madrid (Spain); Garcia-Pastor, Andres; Diaz-Otero, Fernando [Hospital Universitario Gregorio Maranon, IiSGM, Universidad Complutense de Madrid, Madrid (Spain); Calleja, Patricia [Hospital Universitario 12 de Octubre, Universidad Autonoma de Madrid, Madrid (Spain); Lourido, Daniel; Vicente, Agustina; Fandino, Eduardo [Hospital Universitario Ramon y Cajal, IRYCIS, Universidad de Alcala de Henares, Madrid (Spain); Sierra-Hidalgo, Fernando [Hospital Universitario 12 de Octubre, Universidad Autonoma de Madrid, Madrid (Spain); Hospital Universitario Infanta Leonor, Universidad Complutense de Madrid, Madrid (Spain)

2016-05-15

Reliable predictors of poor clinical outcome despite successful revascularization might help select patients with acute ischemic stroke for thrombectomy. We sought to determine whether baseline Alberta Stroke Program Early CT Score (ASPECTS) applied to CT angiography source images (CTA-SI) is useful in predicting futile recanalization. Data are from the FUN-TPA study registry (ClinicalTrials.gov; NCT02164357) including patients with acute ischemic stroke due to proximal arterial occlusion in anterior circulation, undergoing reperfusion therapies. Baseline non-contrast CT and CTA-SI-ASPECTS, time-lapse to image acquisition, occurrence, and timing of recanalization were recorded. Outcome measures were NIHSS at 24 h, symptomatic intracranial hemorrhage, modified Rankin scale score, and mortality at 90 days. Futile recanalization was defined when successful recanalization was associated with poor functional outcome (death or disability). Included were 110 patients, baseline NIHSS 17 (IQR 12; 20), treated with intravenous thrombolysis (IVT; 45 %), primary mechanical thrombectomy (MT; 16 %), or combined IVT + MT (39 %). Recanalization rate was 71 %, median delay of 287 min (225; 357). Recanalization was futile in 28 % of cases. In an adjusted model, baseline CTA-SI-ASPECTS was inversely related to the odds of futile recanalization (OR 0.5; 95 % CI 0.3-0.7), whereas NCCT-ASPECTS was not (OR 0.8; 95 % CI 0.5-1.2). A score ≤5 in CTA-SI-ASPECTS was the best cut-off to predict futile recanalization (sensitivity 35 %; specificity 97 %; positive predictive value 86 %; negative predictive value 77 %). CTA-SI-ASPECTS strongly predicts futile recanalization and could be a valuable tool for treatment decisions regarding the indication of revascularization therapies. (orig.)

CT diagnosis of peritoneal metastasis tumor

International Nuclear Information System (INIS)

Deng Xueying; Chen Xiaoqi; Qi Le; Huang Feng

2005-01-01

Objective: To study the CT findings and diagnosis of peritoneal metastasis. Methods: The CT findings of 17 cases with surgical- pathologically proved peritoneal metastasis were analyzed retrospectively. Results The CT findings of peritoneal metastasis included: (1)ascites (12 cases ); (2)the aternation of parietal peritoneum including broad band thickening (7 cases), nodular sign (2 cases), and massive thickening (1 cases); (3) the involved omentum and mesenterium: 'smut' appearances (7 cases), nodular sign (2 cases), 'omental cake' (5 cases); (4) the invlovement of mesenteric vessels; (5) single-or multi-cystic lesions within peritoneum (1 case) . Conclusion: CT scan is the first choice for metastasis of peritoneum. (authors)

Processing of transmission data from an uncollimated single photon source

International Nuclear Information System (INIS)

Dikaios, N.; Dinelle, K.; Spinks, T.; Nikita, K.; Thielemans, K.

2006-01-01

The EXACT 3D PET scanner uses a Cs-137 single photon rotating point source for the transmission scan. As the source is un-collimated, the transmission data are contaminated by scatter. It has been suggested that segmentation of the reconstructed image can restore the quantitative information in the image. We study here if the results can be further improved by the application of a scale factor for every transaxial plane

Single and multi-frequency impedance characterization of symmetric activated carbon single capacitor cells

Directory of Open Access Journals (Sweden)

Suzana Sopčić

2018-05-01

Full Text Available Electrochemical impedance spectroscopy (EIS technique is used for characterization of single cell symmetric capacitors having different mass loadings of activated carbon (AC. Relevant values of charge storage capacitance (CT and internal resistance (ESR were evaluated by the single frequency and multi-frequency analyses of measured impedance spectra. Curve fittings were based on the non-ideal R-C model that takes into account the parasitic inductance, contributions from electrode materials/contacts and the effects of AC porosity. Higher CT and lower ESR values were obtained not only for the cell with higher mass of AC, but also using the single vs. multi-frequency approach. Lower CT and higher values of ESR that are generally obtained using the multi-frequency method and curve fittings should be related to the not ideal capacitive response of porous AC material and too high frequency chosen in applying the single frequency analysis.

Ultra-high pitch chest computed tomography at 70 kVp tube voltage in an anthropomorphic pediatric phantom and non-sedated pediatric patients. Initial experience with 3{sup rd} generation dual-source CT

Energy Technology Data Exchange (ETDEWEB)

Hagelstein, Claudia; Henzler, Thomas; Haubenreisser, Holger; Meyer, Mathias; Sudarski, Sonja; Schoenberg, Stefan O.; Neff, K. Wolfgang; Weis, Meike [Univ. Medical Center Mannheim (Germany). Inst. of Clinical Radiology and Nuclear Medicine

2016-07-01

Minimizing radiation dose while at the same time preserving image quality is of particular importance in pediatric chest CT. Very recently, CT imaging with a tube voltage of 70 kVp has become clinically available. However, image noise is inversely proportional to the tube voltage. We aimed to investigate radiation dose and image quality of pediatric chest CT performed at 70 kVp in an anthropomorphic pediatric phantom as well as in clinical patients. An anthropomorphic pediatric phantom, which resembles a one-year-old child in physiognomy, was scanned on the 3{sup rd} generation dual-source CT (DSCT) system at 70 kVp and 80 kVp and a fixed ultra low tube-current of 8 mAs to solely evaluate the impact of lowering tube voltage. After the phantom measurements, 18 pediatric patients (mean 29.5 months; range 1-91 months; 21 examinations) underwent 3.2 high-pitch chest CT on the same DSCT system at 70 kVp tube voltage without any sedation. Radiation dose and presence of motion artifacts was compared to a retrospectively identified patient cohort examined at 80 kVp on a 16-slice single-source-CT (SSCT; n = 15; 14/15 with sedation; mean 30.7 months; range 0-96 months; pitch = 1.5) or on a 2{sup nd} generation DSCT without any sedation (n = 6; mean 32.8 months; range 4-61 months; pitch = 3.2). Radiation dose in the phantom scans was reduced by approximately 40% when using a tube voltage of 70 kVp instead of 80 kVp. In the pediatric patient group examined at 70 kVp age-specific effective dose (ED; mean 0.5 ± 0.2 mSv) was significantly lower when compared to the retrospective cohort scanned at 80 kVp on the 16-slice-SSCT (mean ED: 1.0 ± 0.3 mSv; p < 0.0001) and also considerably lower when compared to the cohort scanned at 80 kVp on the 2{sup nd} generation DSCT (mean ED: 0.9 ± 0.5 mSv). None of the prospective, sedation-free CT examinations showed any motion artifacts whereas 13/15 examinations of the retrospective patient cohort scanned at 80 kVp with a pitch of 1

CT-SPECT fusion to correlate radiolabeled monoclonal antibody uptake with abdominal CT findings

International Nuclear Information System (INIS)

Kramer, E.L.; Noz, M.E.; Sanger, J.J.; Megibow, A.J.; Maguire, G.Q.

1989-01-01

To enhance the information provided by computed tomography (CT) and single photon emission computed tomography (SPECT) performed with radiolabeled, anti-carcinoembryonic antigen monoclonal antibody (MoAb), the authors performed fusion of these types of images from eight subjects with suspected colorectal adenocarcinoma. Section thickness and pixel size of the two studies were matched, coordinates of corresponding points from each study were identified, and CT sections were translated, rotated, and reprojected to match the corresponding SPECT scans. The CT-SPECT fusion enabled identification of anatomic sites of tumor-specific MoAb accumulation in four cases, showed non-specific MoAb accumulation in two, and helped confirm information only suggested by the two studies separately in one

Imaging features of primary Sarcomas of the great vessels in CT, MRI and PET/CT: a single-center experience

International Nuclear Information System (INIS)

Falck, Christian von; Meyer, Bernhard; Fegbeutel, Christine; Länger, Florian; Bengel, Frank; Wacker, Frank; Rodt, Thomas

2013-01-01

To investigate the imaging features of primary sarcomas of the great vessels in CT, MRI and 18 F-FDG PET/CT. Thirteen patients with a primary sarcoma of the great vessels were retrospectively evaluated. All available images studies including F-18 FDG PET(/CT) (n = 4), MDCT (n = 12) and MRI (n = 6) were evaluated and indicative image features of this rare tumor entity were identified. The median interval between the first imaging study and the final diagnosis was 11 weeks (0–12 weeks). The most frequently observed imaging findings suggestive of malignant disease in patients with sarcomas of the pulmonary arteries were a large filling defect with vascular distension, unilaterality and a lack of improvement despite effective anticoagulation. In patients with aortic sarcomas we most frequently observed a pedunculated appearance and an atypical location of the filling defect. The F-18 FDG PET(/CT) examinations demonstrated an unequivocal hypermetabolism of the lesion in all cases (4/4). MRI proved lesion vascularization in 5/6 cases. Intravascular unilateral or atypically located filling defects of the great vessels with vascular distension, a pedunculated shape and lack of improvement despite effective anticoagulation are suspicious for primary sarcoma on MDCT or MRI. MR perfusion techniques can add information on the nature of the lesion but the findings may be subtle and equivocal. F-18 FDG PET/CT may have a potential role in these patients and may be considered as part of the imaging workup

High-efficiency single-photon source: The photonic wire geometry

DEFF Research Database (Denmark)

Claudon, J.; Bazin, Maela; Malik, Nitin S.

2009-01-01

We present a single-photon-source design based on the emission of a quantum dot embedded in a semiconductor (GaAs) nanowire. The nanowire ends are engineered (efficient metallic mirror and tip taper) to reach a predicted record-high collection efficiency of 90% with a realistic design. Preliminar...

Comparison of SPECT/CT, MRI and CT in diagnosis of skull base bone invasion in nasopharyngeal carcinoma.

Science.gov (United States)

Zhang, Shu-xu; Han, Peng-hui; Zhang, Guo-qian; Wang, Rui-hao; Ge, Yong-bin; Ren, Zhi-gang; Li, Jian-sheng; Fu, Wen-hai

2014-01-01

Early detection of skull base invasion in nasopharyngeal carcinoma (NPC) is crucial for correct staging, assessing treatment response and contouring the tumor target in radiotherapy planning, as well as improving the patient's prognosis. To compare the diagnostic efficacy of single photon emission computed tomography/computed tomography (SPECT/CT) imaging, magnetic resonance imaging (MRI) and computed tomography (CT) for the detection of skull base invasion in NPC. Sixty untreated patients with histologically proven NPC underwent SPECT/CT imaging, contrast-enhanced MRI and CT. Of the 60 patients, 30 had skull base invasion confirmed by the final results of contrast-enhanced MRI, CT and six-month follow-up imaging (MRI and CT). The diagnostic efficacy of the three imaging modalities in detecting skull base invasion was evaluated. The rates of positive findings of skull base invasion for SPECT/CT, MRI and CT were 53.3%, 48.3% and 33.3%, respectively. The sensitivity, specificity and accuracy were 93.3%, 86.7% and 90.0% for SPECT/CT fusion imaging, 96.7%, 100.0% and 98.3% for contrast-enhanced MRI, and 66.7%, 100.0% and 83.3% for contrast-enhanced CT. MRI showed the best performance for the diagnosis of skull base invasion in nasopharyngeal carcinoma, followed closely by SPECT/CT. SPECT/CT had poorer specificity than that of both MRI and CT, while CT had the lowest sensitivity.

Sourcing for Quality: Cooperating with a Single Supplier or Developing Two Competing Suppliers?

Directory of Open Access Journals (Sweden)

Jingxian Chen

2016-01-01

Full Text Available Supplier efforts regarding product quality are an important issue in outsourcing and play a critical role in a manufacturer’s choice of sourcing strategy. Consider a manufacturer that wants to outsource the manufacturing of two substitute products to external suppliers. This paper studies the strategic interactions under two sourcing strategies: single and dual sourcing. A four-stage noncooperative game model is established to describe each member’s decisions. We further propose four decision scenarios: single sourcing with and without manufacturer quality investment sharing and dual sourcing when suppliers cooperate or do not cooperate on quality decisions. By the backward induction approach, we obtain analytical equilibrium solutions for each decision scenario. By comparing each pair of equilibrium profiles, we find that an appropriate proportion of quality investment sharing by the manufacturer can enable a cooperating strategy with a single supplier to be the dominant strategy. When the manufacturer does not want to share or does not want to share a relatively large portion of its supplier’s quality investment, it will always prefer to develop two competing suppliers when the cost of dual sourcing is sufficiently low. However, dual sourcing can be extremely risky for the manufacturer because the suppliers could provide a relatively low product quality level by cooperating on the quality decision to extract the manufacturer’s profit.

Assessment of consistency of the whole tumor and single section perfusion imaging with 256-slice spiral CT: a preliminary study

International Nuclear Information System (INIS)

Sun Hongliang; Xu Yanyan; Hu Yingying; Tian Yuanjiang; Wang Wu

2014-01-01

Objective: To determine the consistency between quantitative CT perfusion measurements of colorectal cancer obtained from single section with maximal tumor dimension and from average of whole tumor, and compare intra- and inter-observer consistency of the two analysis methods. Methods: Twenty-two patients with histologically proven colorectal cancer were examined prospectively with 256-slice CT and the whole tumor perfusion images were obtained. Perfusion parameters were obtained from region of interest (ROI) inserted in single section showing maximal tumor dimension, then from ROI inserted in all tumor-containing sections by two radiologists. Consistency between values of blood flow (BF), blood volume (BV) and time to peak (TTP) calculated by two methods was assessed. Intra-observer consistency was evaluated by comparing repeated measurements done by the same radiologist using both methods after 3 months. Perfusion measurements were done by another radiologist independently to assess inter-observer consistency of both methods. The results from different methods were compared using paired t test and Bland-Altman plot. Results: Twenty-two patients were examined successfully. The perfusion parameters BF, BV and TTP obtained by whole tumor perfusion and single-section analysis were (35.59 ± 14.59) ml · min -1 · 100 g -1 , (17.55 ±4.21) ml · 100 g -1 , (21.30 ±7.57) s and (34.64 ± 13.29)ml · min -1 · 100 g -1 , (17.61 ±6.39)ml · 100 g -1 , (19.82 ±9.01) s, respectively. No significant differences were observed between the means of the perfusion parameters (BF, BV, TTP) calculated by the two methods (t=0.218, -0.033, -0.668, P>0.05, respectively). The intra-observer 95% limits of consistency of perfusion parameters were BF -5.3% to 10.0%, BV -13.8% to 10.8%, TTP -15.0% to 12.6% with whole tumor analysis, respectively; BF -14.3% to 16.5%, BV -24.2% to 22.2%, TTP -19.0% to 16.1% with single section analysis, respectively. The inter-observer 95% limits of

Molecular imaging agents for SPECT (and SPECT/CT)

International Nuclear Information System (INIS)

Gnanasegaran, Gopinath; Ballinger, James R.

2014-01-01

The development of hybrid single photon emission computed tomography/computed tomography (SPECT/CT) cameras has increased the diagnostic value of many existing single photon radiopharmaceuticals. Precise anatomical localization of lesions greatly increases diagnostic confidence in bone imaging of the extremities, infection imaging, sentinel lymph node localization, and imaging in other areas. Accurate anatomical localization is particularly important prior to surgery, especially involving the parathyroid glands and sentinel lymph node procedures. SPECT/CT plays a role in characterization of lesions, particularly in bone scintigraphy and radioiodine imaging of metastatic thyroid cancer. In the development of novel tracers, SPECT/CT is particularly important in monitoring response to therapies that do not result in an early change in lesion size. Preclinical SPECT/CT devices, which actually have spatial resolution superior to PET/CT devices, have become essential in characterization of the biodistribution and tissue kinetics of novel tracers, allowing coregistration of serial studies within the same animals, which serves both to reduce biological variability and reduce the number of animals required. In conclusion, SPECT/CT increases the utility of existing radiopharmaceuticals and plays a pivotal role in the evaluation of novel tracers. (orig.)

Molecular imaging agents for SPECT (and SPECT/CT)

Energy Technology Data Exchange (ETDEWEB)

Gnanasegaran, Gopinath [Guy' s and St Thomas' NHS Foundation Trust, Department of Nuclear Medicine, London (United Kingdom); Ballinger, James R. [Guy' s and St Thomas' NHS Foundation Trust, Department of Nuclear Medicine, London (United Kingdom); King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom)

2014-05-15

The development of hybrid single photon emission computed tomography/computed tomography (SPECT/CT) cameras has increased the diagnostic value of many existing single photon radiopharmaceuticals. Precise anatomical localization of lesions greatly increases diagnostic confidence in bone imaging of the extremities, infection imaging, sentinel lymph node localization, and imaging in other areas. Accurate anatomical localization is particularly important prior to surgery, especially involving the parathyroid glands and sentinel lymph node procedures. SPECT/CT plays a role in characterization of lesions, particularly in bone scintigraphy and radioiodine imaging of metastatic thyroid cancer. In the development of novel tracers, SPECT/CT is particularly important in monitoring response to therapies that do not result in an early change in lesion size. Preclinical SPECT/CT devices, which actually have spatial resolution superior to PET/CT devices, have become essential in characterization of the biodistribution and tissue kinetics of novel tracers, allowing coregistration of serial studies within the same animals, which serves both to reduce biological variability and reduce the number of animals required. In conclusion, SPECT/CT increases the utility of existing radiopharmaceuticals and plays a pivotal role in the evaluation of novel tracers. (orig.)

Surface characterization of III-V MOCVD films from heterocyclic single-source precursors; Oberflaechencharakterisierung von III-V MOCVD-Filmen aus heterozyklischen Single Source Precursoren

Energy Technology Data Exchange (ETDEWEB)

Seemayer, Andreas

2009-07-13

In the present thesis the sublimation and evaporation properties of heterocyclic gallium and antimony containing single-source precursors as well as the chemical composition and morphology of the films fabricated from this were studied. The single-source precursors available by a new synthesis route were characterized concerning their evaporation properties and the obtained films studied surface-physically. By this way the process parameters were optimized and the applicability of the single-source precursors in HV-MOCVD processes studied. By evaporation experiments in the UHV it could be shown that thereby lighter ligands like ethyl- and methyl-groups lead to a lower contamination of the reaction space with carbon containing molecules. Furthermore it was expected that the 6-rings synthetized with short ligands exhibit a high stability. This however could not be confirmed. By unwanted parasitary reactions in the gaseous phase respectively dissociative sublimation in the gaseous phase a deposition of GaSb with these precursors was not possible. The 4-ring stabilized with tertiary-butyl and ethyl-groups caused in the evaporation the largest contamination of the gaseous phase, becauselonger-chain hydrocarbons exhibil only a bad pump cross section. By parasitary reactions originating elementary antimony is detectable in the gaseous phase. The films were studied concerning their chemical composition and their transport- respectively storage-conditioned surface contamination. Furthermore it has become clear that not only a purely synthetized precursor substance but also the reactor design is deciding for a successful deposition and a high film quality. First by successive optimization of the evaporation geometry it was possible to reduce the roughness of the produced GaSb films down to about 10 nm-30 nm.

Methods of forming single source precursors, methods of forming polymeric single source precursors, and single source precursors formed by such methods

Science.gov (United States)

Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin; Margulieux, Kelsey R.; Holland, Andrew W.

2014-09-09

Methods of forming single source precursors (SSPs) include forming intermediate products having the empirical formula 1/2{L.sub.2N(.mu.-X).sub.2M'X.sub.2}.sub.2, and reacting MER with the intermediate products to form SSPs of the formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2, wherein L is a Lewis base, M is a Group IA atom, N is a Group IB atom, M' is a Group IIIB atom, each E is a Group VIB atom, each X is a Group VIIA atom or a nitrate group, and each R group is an alkyl, aryl, vinyl, (per)fluoro alkyl, (per)fluoro aryl, silane, or carbamato group. Methods of forming polymeric or copolymeric SSPs include reacting at least one of HE.sup.1R.sup.1E.sup.1H and MER with one or more substances having the empirical formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2 or L.sub.2N(.mu.-X).sub.2M'(X).sub.2 to form a polymeric or copolymeric SSP. New SSPs and intermediate products are formed by such methods.

Importance of SPECT/CT for knee and hip joint prostheses; Stellenwert der SPECT/CT bei Knie- und Hueftgelenkprothesen

Energy Technology Data Exchange (ETDEWEB)

Strobel, K.; Steurer-Dober, I.; Huellner, M.W.; Veit-Haibach, P.; Allgayer, B. [Luzerner Kantonsspital (Switzerland). Institut fuer Nuklearmedizin und Roentgendiagnostik

2012-07-15

Complications, such as loosening or infections are common problems after hip or knee arthroplasty. If conventional X-rays are equivocal bone scintigraphy is the classical second-line imaging modality. Single photon emission computed tomography/computed tomography (SPECT/CT) offers metabolic and morphologic information in one imaging step and is becoming increasingly more available in larger hospitals. The SPECT/CT procedure is a promising method and is increasingly being used in daily routine to evaluate joint arthroplasty. The additional benefit compared with classical conventional bone scintigraphy has to be evaluated in further prospective studies. In our hospital SPECT/CT regularly gives important additional information regarding prosthetic joint complications. SPECT/CT is increasingly being used as the second step imaging standard modality if conventional X-rays are equivocal. (orig.) [German] Komplikationen wie Lockerung und Infekt stellen ein haeufiges Problem nach Hueft- und Kniegelenkprothesen dar. Wenn die konventionelle Roentgenaufnahme nicht zum Ziel fuehrt, ist die klassische konventionelle Skelettszintigraphie die am haeufigsten verwendete ''Second-line''-Bildgebung. Die ''single photon emission computed tomography''/CT (SPECT/CT) bietet metabolische und morphologische Informationen bzgl. Prothesenkomplikationen in einem Untersuchungsgang und ist zunehmend in groesseren Kliniken verfuegbar. Die SPECT/CT ist eine viel versprechende Methode und wird im klinischen Alltag bei der Evaluation von Gelenkprothesen zunehmend eingesetzt. Es sind noch mehr prospektive Studien noetig, um die Leistungsfaehigkeit und den Zusatznutzen gegenueber der klassischen Szintigraphie zu evaluieren. In unserer Klinik wird die Knochenszintigraphie bei der Abklaerung von Prothesenkomplikationen zumeist mit einer SPECT/CT kombiniert und liefert regelmaessig wichtige Zusatzinformationen. Die SPECT/CT entwickelt sich zunehmend zum Standard

Prospectively ECG-triggered high-pitch coronary angiography with third-generation dual-source CT at 70 kVp tube voltage: feasibility, image quality, radiation dose, and effect of iterative reconstruction.

Science.gov (United States)

Hell, Michaela M; Bittner, Daniel; Schuhbaeck, Annika; Muschiol, Gerd; Brand, Michael; Lell, Michael; Uder, Michael; Achenbach, Stephan; Marwan, Mohamed

2014-01-01

Low tube voltage reduces radiation exposure in coronary CT angiography (CTA). Using 70 kVp tube potential has so far not been possible because CT systems were unable to provide sufficiently high tube current with low voltage. We evaluated feasibility, image quality (IQ), and radiation dose of coronary CTA using a third-generation dual-source CT system capable of producing 450 mAs tube current at 70 kVp tube voltage. Coronary CTA was performed in 26 consecutive patients with suspected coronary artery disease, selected for body weight Image noise was lower in IR vs FBP (60 ± 10 HU vs 74 ± 8 HU; P < .001). In patients <100 kg and with a regular heart rate <60 beats/min, third-generation dual-source CT using high-pitch spiral acquisition and 70 kVp tube voltage is feasible and provides both robust IQ and very low radiation exposure. Copyright © 2014 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Comparison of Single-Photon Emission Computed Tomography-Computed Tomography (SPECT/CT) and Conventional Planar Lymphoscintigraphy for Sentinel Node Localization in Patients with Cutaneous Malignancies.

Science.gov (United States)

Doepker, Matthew P; Yamamoto, Maki; Applebaum, Matthew A; Patel, Nupur U; Jaime Montilla-Soler, M; Sarnaik, Amod A; Wayne Cruse, C; Sondak, Vernon K; Zager, Jonathan S

2017-02-01

Accurate preoperative lymphoscintigraphy is vital to performing sentinel lymph node biopsy (SLNB) for cutaneous malignancies. Potential advantages of single-photon emission computed tomography with integrated computed tomography (SPECT/CT) include the ability to readily identify aberrant drainage patterns as well as provide the surgeon with three-dimensional anatomic landmarks not seen on conventional planar lymphoscintigraphy (PLS). Patients with cutaneous malignancies who underwent SLNB with preoperative imaging using both SPECT/CT and PLS from 2011 to 2014 were identified. Both SPECT/CT and PLS were obtained in 351 patients (median age, 69 years; range, 5-94 years) with cutaneous malignancies (melanoma = 300, Merkel cell carcinoma = 33, squamous cell carcinoma = 8, other = 10) after intradermal injection of 99m technetium sulfur colloid (median dose 300 µCi). A mean of 4.3 hot spots were identified on SPECT/CT compared to 3.0 on PLS (p CT and PLS, while 172 (49 %) had additional hot spots identified on SPECT/CT compared to only 24 (6.8 %) additional on PLS. SPECT/CT demonstrated additional nodal basins in 103 patients (29.4 %), compared to only 11 patients (3.1 %) with additional basins on PLS. SPECT/CT is a useful adjunct that can help with sentinel node localization in challenging cases. It identified additional hot spots not seen on PLS in almost 50 % of patients. Because PLS identified hot spots not seen on SPECT/CT in 6.8 % of patients, we recommend using both modalities jointly. Long-term follow-up will be required to validate the clinical significance of the additional hot spots identified by SPECT/CT.

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.

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.

Imaging the Parasinus Region with a Third-Generation Dual-Source CT and the Effect of Tin Filtration on Image Quality and Radiation Dose.

Science.gov (United States)

Lell, M M; May, M S; Brand, M; Eller, A; Buder, T; Hofmann, E; Uder, M; Wuest, W

2015-07-01

CT is the imaging technique of choice in the evaluation of midface trauma or inflammatory disease. We performed a systematic evaluation of scan protocols to optimize image quality and radiation exposure on third-generation dual-source CT. CT protocols with different tube voltage (70-150 kV), current (25-300 reference mAs), prefiltration, pitch value, and rotation time were systematically evaluated. All images were reconstructed with iterative reconstruction (Advanced Modeled Iterative Reconstruction, level 2). To individually compare results with otherwise identical factors, we obtained all scans on a frozen human head. Conebeam CT was performed for image quality and dose comparison with multidetector row CT. Delineation of important anatomic structures and incidental pathologic conditions in the cadaver head was evaluated. One hundred kilovolts with tin prefiltration demonstrated the best compromise between dose and image quality. The most dose-effective combination for trauma imaging was Sn100 kV/250 mAs (volume CT dose index, 2.02 mGy), and for preoperative sinus surgery planning, Sn100 kV/150 mAs (volume CT dose index, 1.22 mGy). "Sn" indicates an additional prefiltration of the x-ray beam with a tin filter to constrict the energy spectrum. Exclusion of sinonasal disease was possible with even a lower dose by using Sn100 kV/25 mAs (volume CT dose index, 0.2 mGy). High image quality at very low dose levels can be achieved by using a Sn100-kV protocol with iterative reconstruction. The effective dose is comparable with that of conventional radiography, and the high image quality at even lower radiation exposure favors multidetector row CT over conebeam CT. © 2015 by American Journal of Neuroradiology.

Post-processing with linear optics for improving the quality of single-photon sources

International Nuclear Information System (INIS)

Berry, Dominic W; Scheel, Stefan; Myers, Casey R; Sanders, Barry C; Knight, Peter L; Laflamme, Raymond

2004-01-01

Triggered single-photon sources produce the vacuum state with non-negligible probability, but produce a much smaller multiphoton component. It is therefore reasonable to approximate the output of these photon sources as a mixture of the vacuum and single-photon states. We show that it is impossible to increase the probability for a single photon using linear optics and photodetection on fewer than four modes. This impossibility is due to the incoherence of the inputs; if the inputs were pure-state superpositions, it would be possible to obtain a perfect single-photon output. In the more general case, a chain of beam splitters can be used to increase the probability for a single photon, but at the expense of adding an additional multiphoton component. This improvement is robust against detector inefficiencies, but is degraded by distinguishable photons, dark counts or multiphoton components in the input

Clinical applications of SPECT/CT: New hybrid nuclear medicine imaging system

International Nuclear Information System (INIS)

2008-08-01

Interest in multimodality imaging shows no sign of subsiding. New tracers are spreading out the spectrum of clinical applications and innovative technological solutions are preparing the way for yet more modality marriages: hybrid imaging. Single photon emission computed tomography (SPECT) has enabled the evaluation of disease processes based on functional and metabolic information of organs and cells. Integration of X ray computed tomography (CT) into SPECT has recently emerged as a brilliant diagnostic tool in medical imaging, where anatomical details may delineate functional and metabolic information. SPECT/CT has proven to be valuable in oncology. For example, in the case of a patient with metastatic thyroid cancer, neither SPECT nor CT alone could identify the site of malignancy. SPECT/CT, a hybrid image, precisely identified where the surgeon should operate. However SPECT/CT is not just advantageous in oncology. It may also be used as a one-stop-shop for various diseases. Clinical applications with SPECT/CT have started and expanded in developed countries. It has been reported that moving from SPECT alone to SPECT/CT could change diagnoses in 30% of cases. Large numbers of people could therefore benefit from this shift all over the world. This report presents an overview of clinical applications of SPECT/CT and a relevant source of information for nuclear medicine physicians, radiologists and clinical practitioners. This information may also be useful for decision making when allocating resources dedicated to the health care system, a critical issue that is especially important for the development of nuclear medicine in developing countries. In this regard, the IAEA may be heavily involved in the promotion of programmes aimed at the IAEA's coordinated research projects and Technical Cooperation projects

Bright quantum dot single photon source based on a low Q defect cavity

DEFF Research Database (Denmark)

Maier, Sebastian; Gold, Peter; Forchel, A.

2014-01-01

The quasi-planar single photon source presented in this paper shows an extraction efficiency of 42% without complex photonic resonator geometries or lithography steps as well as a high purity with a g2(0) value of 0.023.......The quasi-planar single photon source presented in this paper shows an extraction efficiency of 42% without complex photonic resonator geometries or lithography steps as well as a high purity with a g2(0) value of 0.023....

Cross correlations of quantum key distribution based on single-photon sources

International Nuclear Information System (INIS)

Dong Shuangli; Wang Xiaobo; Zhang Guofeng; Sun Jianhu; Zhang Fang; Xiao Liantuan; Jia Suotang

2009-01-01

We theoretically analyze the second-order correlation function in a quantum key distribution system with real single-photon sources. Based on single-event photon statistics, the influence of the modification caused by an eavesdropper's intervention and the effects of background signals on the cross correlations between authorized partners are presented. On this basis, we have shown a secure range of correlation against the intercept-resend attacks.

Adding bevacizumab to single agent chemotherapy for the treatment of platinum-resistant recurrent ovarian cancer: A cost effectiveness analysis of the AURELIA trial.

Science.gov (United States)

Wysham, Weiya Z; Schaffer, Elisabeth M; Coles, Theresa; Roque, Dario R; Wheeler, Stephanie B; Kim, Kenneth H

2017-05-01

AURELIA, a randomized phase III trial of adding bevacizumab (B) to single agent chemotherapy (CT) for the treatment of platinum-resistant recurrent ovarian cancer, demonstrated improved progression free survival (PFS) in the B+CT arm compared to CT alone. We aimed to evaluate the cost effectiveness of adding B to CT in the treatment of platinum-resistant recurrent ovarian cancer. A decision tree model was constructed to evaluate the cost effectiveness of adding bevacizumab (B) to single agent chemotherapy (CT) based on the arms of the AURELIA trial. Costs, quality-adjusted life years (QALYs), and progression free survival (PFS) were modeled over fifteen months. Model inputs were extracted from published literature and public sources. Incremental cost effectiveness ratios (ICERs) per QALY gained and ICERs per progression free life year saved (PF-LYS) were calculated. One-way sensitivity analyses were performed to evaluate the robustness of results. The ICER associated with B+CT is $410,455 per QALY gained and $217,080 per PF-LYS. At a willingness to pay (WTP) threshold of $50,000/QALY, adding B to single agent CT is not cost effective for this patient population. Even at a WTP threshold of $100,000/QALY, B+CT is not cost effective. These findings are robust to sensitivity analyses. Despite gains in QALY and PFS, the addition of B to single agent CT for treatment of platinum-resistant recurrent ovarian cancer is not cost effective. Benefits, risks, and costs associated with treatment should be taken into consideration when prescribing chemotherapy for this patient population. Copyright © 2017 Elsevier Inc. All rights reserved.

High brightness fiber laser pump sources based on single emitters and multiple single emitters

Science.gov (United States)

Scheller, Torsten; Wagner, Lars; Wolf, Jürgen; Bonati, Guido; Dörfel, Falk; Gabler, Thomas

2008-02-01

Driven by the potential of the fiber laser market, the development of high brightness pump sources has been pushed during the last years. The main approaches to reach the targets of this market had been the direct coupling of single emitters (SE) on the one hand and the beam shaping of bars and stacks on the other hand, which often causes higher cost per watt. Meanwhile the power of single emitters with 100μm emitter size for direct coupling increased dramatically, which also pushed a new generation of wide stripe emitters or multi emitters (ME) of up to 1000μm emitter size respectively "minibars" with apertures of 3 to 5mm. The advantage of this emitter type compared to traditional bars is it's scalability to power levels of 40W to 60W combined with a small aperture which gives advantages when coupling into a fiber. We show concepts using this multiple single emitters for fiber coupled systems of 25W up to 40W out of a 100μm fiber NA 0.22 with a reasonable optical efficiency. Taking into account a further efficiency optimization and an increase in power of these devices in the near future, the EUR/W ratio pushed by the fiber laser manufacturer will further decrease. Results will be shown as well for higher power pump sources. Additional state of the art tapered fiber bundles for photonic crystal fibers are used to combine 7 (19) pump sources to output powers of 100W (370W) out of a 130μm (250μm) fiber NA 0.6 with nominal 20W per port. Improving those TFB's in the near future and utilizing 40W per pump leg, an output power of even 750W out of 250μm fiber NA 0.6 will be possible. Combined Counter- and Co-Propagated pumping of the fiber will then lead to the first 1kW fiber laser oscillator.

Coronary artery stent imaging with 128-slice dual-source CT using high-pitch spiral acquisition in a cardiac phantom: comparison with the sequential and low-pitch spiral mode

International Nuclear Information System (INIS)

Wolf, Florian; Loewe, Christian; Plank, Christina; Schernthaner, Ruediger; Bercaczy, Dominik; Lammer, Johannes; Leschka, Sebastian; Goetti, Robert; Marincek, Borut; Alkadhi, Hatem; Homolka, Peter; Friedrich, Guy; Feuchtner, Gudrun

2010-01-01

To evaluate coronary stents in vitro using 128-slice-dual-source computed tomography (CT). Twelve different coronary stents placed in a non-moving cardiac/chest phantom were examined by 128-slice dual-source CT using three CT protocols [high-pitch spiral (HPS), sequential (SEQ) and conventional spiral (SPIR)]. Artificial in-stent lumen narrowing (ALN), visible inner stent area (VIA), artificial in-stent lumen attenuation (ALA) in percent, image noise inside/outside the stent and CTDIvol were measured. Mean ALN was 46% for HPS, 44% for SEQ and 47% for SPIR without significant difference. Mean VIA was similar with 31% for HPS, 30% for SEQ and 33% for SPIR. Mean ALA was, at 5% for HPS, significantly lower compared with -11% for SPIR (p = 0.024), but not different from SEQ with -1%. Mean image noise was significantly higher for HPS compared with SEQ and SPIR inside and outside the stent (p < 0.001). CTDIvol was lower for HPS (5.17 mGy), compared with SEQ (9.02 mGy) and SPIR (55.97 mGy), respectively. The HPS mode of 128-slice dual-source CT yields fewer artefacts inside the stent lumen compared with SPIR and SEQ, but image noise is higher. ALN is still too high for routine stent evaluation in clinical practice. Radiation dose of the HPS mode is markedly (less than about tenfold) reduced. (orig.)

Myocardial delayed-enhancement CT: initial experience in children and young adults

Energy Technology Data Exchange (ETDEWEB)

Goo, Hyun Woo [University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Asan Medical Center, Seoul (Korea, Republic of)

2017-10-15

Clinical utility of myocardial delayed enhancement CT has not been reported in children and young adults. To describe initial experience of myocardial delayed enhancement CT regarding image quality, radiation dose and identification of myocardial lesions in children and young adults. Between August 2013 and November 2016, 29 consecutive children and young adults (median age 16 months) with suspected coronary artery or myocardial abnormality underwent arterial- and delayed-phase cardiac CT at our institution. We measured CT densities in normal myocardium, left ventricular cavity, and arterial and delayed hypo-enhancing and delayed hyperenhancing myocardial lesions. We then compared the extent of delayed hyperenhancing lesions with delayed-enhancement MRI or thallium single-photon emission CT. Normal myocardium and left ventricular cavity showed significantly higher CT numbers on arterial-phase CT than on delayed-phase CT (t-test, P<0.0001). Contrast-to-noise ratios of the arterial and delayed hypo-enhancing and delayed hyperenhancing lesions on CT were 26.7, 17.6 and 18.7, respectively. Delayed-phase CT findings were equivalent to those of delayed-enhancement MRI in all cases (7/7) and to those of thallium single-photon emission CT in 70% (7/10). Myocardial delayed-enhancement CT can be added to evaluate myocardial lesions in select children and young adults with suspected coronary artery or myocardial abnormality. (orig.)

Myocardial delayed-enhancement CT: initial experience in children and young adults

International Nuclear Information System (INIS)

Goo, Hyun Woo

2017-01-01

Clinical utility of myocardial delayed enhancement CT has not been reported in children and young adults. To describe initial experience of myocardial delayed enhancement CT regarding image quality, radiation dose and identification of myocardial lesions in children and young adults. Between August 2013 and November 2016, 29 consecutive children and young adults (median age 16 months) with suspected coronary artery or myocardial abnormality underwent arterial- and delayed-phase cardiac CT at our institution. We measured CT densities in normal myocardium, left ventricular cavity, and arterial and delayed hypo-enhancing and delayed hyperenhancing myocardial lesions. We then compared the extent of delayed hyperenhancing lesions with delayed-enhancement MRI or thallium single-photon emission CT. Normal myocardium and left ventricular cavity showed significantly higher CT numbers on arterial-phase CT than on delayed-phase CT (t-test, P<0.0001). Contrast-to-noise ratios of the arterial and delayed hypo-enhancing and delayed hyperenhancing lesions on CT were 26.7, 17.6 and 18.7, respectively. Delayed-phase CT findings were equivalent to those of delayed-enhancement MRI in all cases (7/7) and to those of thallium single-photon emission CT in 70% (7/10). Myocardial delayed-enhancement CT can be added to evaluate myocardial lesions in select children and young adults with suspected coronary artery or myocardial abnormality. (orig.)

Coronary artery anomalies: Assessment with electrocardiography-gate multidetector-row CT at a single center in Korea

International Nuclear Information System (INIS)

Yi, Bo Ram; Sun, Joo Sung; Yang, Hyoung Mo; Kang, Doo Kyoung

2015-01-01

To determine the prevalence of coronary anomalies using coronary computed tomography angiography (CCTA) and to evaluate the relationship between coronary artery anomalies and chest pain. A total of 12676 patients underwent CCTA scans at our institution between December 2006 and April 2013 using a 64-slice CT and a 128-slice dual-source CT. We determined the prevalence of coronary artery anomalies according to the classification system proposed by Greenberg. The presence or absence of chest pain with each coronary artery anomaly was also evaluated. Coronary anomalies were found in 176 patients (1.39%) at our institute. Anomalies of origination, course, and termination were detected in 118 (0.93%), 28 (0.22%), and 30 (0.24%) patients, respectively. After the exclusion of 32 patients with combined heart disease, typical (n = 16; 11.1%) or atypical (n = 28; 19.4%) chest pain was present in 44 (30.6%) of the 144 patients at the time of diagnosis. The prevalence of coronary artery anomalies was 1.39% at our hospital. After the exclusion of patients with combined heart disease, 11.1% had typical chest pain at the time of diagnosis.

Clinical applications of SPECT-CT

Energy Technology Data Exchange (ETDEWEB)

Ahmadzadehfar, Hojjat; Biersack, Hans-Juergen (eds.) [University Hospital Bonn (Germany). Dept. of Nuclear Medicine

2014-06-01

Covers the full spectrum of clinical applications of SPECT/CT in diagnosis of benign and malignant diseases. Includes chapters on the use of SPECT/CT for dosimetry and for therapy planning. Completely up to date. Many helpful illustrations. SPECT/CT cameras have considerably improved diagnostic accuracy in recent years. Such cameras allow direct correlation of anatomic and functional information, resulting in better localization and definition of scintigraphic findings. In addition to this anatomic referencing, CT coregistration provides superior quantification of radiotracer uptake based on the attenuation correction capabilities of CT. Useful applications of SPECT/CT have been identified not only in oncology but also in other specialties such as orthopedics and cardiology. This book covers the full spectrum of clinical applications of SPECT/CT in diagnosis and therapy planning of benign and malignant diseases. Opening chapters discuss the technology and physics of SPECT/CT and its use for dosimetry. The role of SPECT/CT in the imaging of a range of pathologic conditions is then addressed in detail. Applications covered include, among others, imaging of the thyroid, bone, and lungs, imaging of neuroendocrine tumors, cardiac scintigraphy, and sentinel node scintigraphy. Individual chapters are also devoted to therapy planning in selective internal radiation therapy of liver tumors and bremsstrahlung SPECT/CT. Readers will find this book to be an essential and up-to-date source of information on this invaluable hybrid imaging technique.

On-demand generation of background-free single photons from a solid-state source

Science.gov (United States)

Schweickert, Lucas; Jöns, Klaus D.; Zeuner, Katharina D.; Covre da Silva, Saimon Filipe; Huang, Huiying; Lettner, Thomas; Reindl, Marcus; Zichi, Julien; Trotta, Rinaldo; Rastelli, Armando; Zwiller, Val

2018-02-01

True on-demand high-repetition-rate single-photon sources are highly sought after for quantum information processing applications. However, any coherently driven two-level quantum system suffers from a finite re-excitation probability under pulsed excitation, causing undesirable multi-photon emission. Here, we present a solid-state source of on-demand single photons yielding a raw second-order coherence of g(2 )(0 )=(7.5 ±1.6 )×10-5 without any background subtraction or data processing. To this date, this is the lowest value of g(2 )(0 ) reported for any single-photon source even compared to the previously reported best background subtracted values. We achieve this result on GaAs/AlGaAs quantum dots embedded in a low-Q planar cavity by employing (i) a two-photon excitation process and (ii) a filtering and detection setup featuring two superconducting single-photon detectors with ultralow dark-count rates of (0.0056 ±0.0007 ) s-1 and (0.017 ±0.001 ) s-1, respectively. Re-excitation processes are dramatically suppressed by (i), while (ii) removes false coincidences resulting in a negligibly low noise floor.

Implications of CT noise and artifacts for quantitative 99mTc SPECT/CT imaging

International Nuclear Information System (INIS)

Hulme, K. W.; Kappadath, S. C.

2014-01-01

Purpose: This paper evaluates the effects of computed tomography (CT) image noise and artifacts on quantitative single-photon emission computed-tomography (SPECT) imaging, with the aim of establishing an appropriate range of CT acquisition parameters for low-dose protocols with respect to accurate SPECT attenuation correction (AC). Methods: SPECT images of two geometric and one anthropomorphic phantom were reconstructed iteratively using CT scans acquired at a range of dose levels (CTDI vol = 0.4 to 46 mGy). Resultant SPECT image quality was evaluated by comparing mean signal, background noise, and artifacts to SPECT images reconstructed using the highest dose CT for AC. Noise injection was performed on linear-attenuation (μ) maps to determine the CT noise threshold for accurate AC. Results: High levels of CT noise (σ ∼ 200–400 HU) resulted in low μ-maps noise (σ ∼ 1%–3%). Noise levels greater than ∼10% in 140 keV μ-maps were required to produce visibly perceptible increases of ∼15% in 99m Tc SPECT images. These noise levels would be achieved at low CT dose levels (CTDI vol = 4 μGy) that are over 2 orders of magnitude lower than the minimum dose for diagnostic CT scanners. CT noise could also lower (bias) the expected μ values. The relative error in reconstructed SPECT signal trended linearly with the relative shift in μ. SPECT signal was, on average, underestimated in regions corresponding with beam-hardening artifacts in CT images. Any process that has the potential to change the CT number of a region by ∼100 HU (e.g., misregistration between CT images and SPECT images due to motion, the presence of contrast in CT images) could introduce errors in μ 140 keV on the order of 10%, that in turn, could introduce errors on the order of ∼10% into the reconstructed 99m Tc SPECT image. Conclusions: The impact of CT noise on SPECT noise was demonstrated to be negligible for clinically achievable CT parameters. Because CT dose levels that affect

Three-Level Z-Source Inverters Using a Single LC Impedance Network

DEFF Research Database (Denmark)

Loh, Poh Chiang; Lim, Sok Wei; Gao, Feng

2007-01-01

two LC impedance networks and two isolated dc sources, which can significantly increase the overall system cost and require a more complex modulator for balancing the network inductive voltage boosting. Offering a number of less costly alternatives, this letter presents the design and control of two...... three-level Z-source inverters, whose output voltage can be stepped down or up using only a single LC impedance network connected between the dc input source and either a neutral-point-clamped (NPC) or dc-link cascaded inverter circuitry. Through careful design of their modulation scheme, both inverters...

Three-dimensional versus conventional CT in the evaluation of facial trauma

International Nuclear Information System (INIS)

Mayer, J.S.; Yeakley, J.W.; Kulkarni, M.V.; Wainwright, D.J.; Lee, K.F.; Harris, J.H. Jr.

1987-01-01

An accurate knowledge of the three-dimensional pattern of facial fractures is surgically important. This exhibit shows how this may be difficult if not impossible to obtain using axial and reconstructed CT images and how 3D CT is superior in this regard. 3D CT displays the course of anterior and lateral facial fractures and the spatial orientation of bone fragments that can be missed when using other CT techniques. 3D CT and facial CT images can be generated from a single CT examination and are complementary. Together they display posttraumatic facial anatomy better than conventional planar CT images

Assessment of thoracic aortic elasticity: a preliminary study using electrocardiographically gated dual-source CT

International Nuclear Information System (INIS)

Li, Ning; Guo, Lijun; Sun, Haitao; Gao, Fei; Liu, Cheng; Beck, Thomas; Chen, Jiuhong; Biermann, Christina

2011-01-01

To gain a new insight into the elastic properties of the thoracic aorta in patients without aortic diseases using electrocardiographically (ECG)-gated dual-source (DS) CT. 56 subjects with no cardiovascular disease, selected from 2,700 people undergoing ECG-gated DSCT examination, were divided into three groups according to their age. CT data were reconstructed in 5% step throughout the RR interval. Diameter and area were measured at the curve of the ascending aorta (AA) and at the same level of the descending aorta (DA). The pulsation and elasticity of the aorta were evaluated. Aortic diameter changes were noted throughout the cardiac cycle. The maximum average diameter was seen at an RR interval of 24.02 ± 4.99% for the AA and 25.63 ± 4.77% for the DA. The minimum was at 93.5 ± 4.04% for the AA and 96.6 ± 4.58% for the DA. There was an age-dependent decrease in elasticity, while different correlation coefficients were found between various age groups and different elastic parameters. The properties of aortic pulsation and wall elasticity could be well shown by ECG-gated DSCT. The new findings regarding segment difference and age relevance were significant and should be taken into account in clinical trials and treatments for the elasticity related cardiovascular diseases. (orig.)

All-periodically poled, high-power, continuous-wave, single-frequency tunable UV source.

Science.gov (United States)

Aadhi, A; Chaitanya N, Apurv; Jabir, M V; Singh, R P; Samanta, G K

2015-01-01

We report on experimental demonstration of an all-periodically poled, continuous-wave (CW), high-power, single-frequency, ultra-violet (UV) source. Based on internal second-harmonic-generation (SHG) of a CW singly resonant optical parametric oscillator (OPO) pumped in the green, the UV source provides tunable radiation across 398.94-417.08 nm. The compact source comprising of a 25-mm-long MgO-doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) crystal of period Λ(SLT)=8.5  μm for OPO and a 5-mm-long, multi-grating (Λ(KTP)=3.3, 3.4, 3.6 and 3.8 μm), periodically poled potassium titanium phosphate (PPKTP) for intra-cavity SHG, provides as much as 336 mW of UV power at 398.94 nm, corresponding to a green-to-UV conversion efficiency of ∼6.7%. In addition, the singly resonant OPO (SRO) provides 840 mW of idler at 1541.61 nm and substantial signal power of 108 mW at 812.33 nm transmitted through the high reflective cavity mirrors. UV source provides single-frequency radiation with instantaneous line-width of ∼18.3  MHz and power >100  mW in Gaussian beam profile (ellipticity >92%) across the entire tuning range. Access to lower UV wavelengths requires smaller grating periods to compensate high phase-mismatch resulting from high material dispersion in the UV wavelength range. Additionally, we have measured the normalized temperature and spectral acceptance bandwidth of PPKTP crystal in the UV wavelength range to be ∼2.25°C·cm and ∼0.15  nm·cm, respectively.

HDRMC, an accelerated Monte Carlo dose calculator for high dose rate brachytherapy with CT-compatible applicators

Energy Technology Data Exchange (ETDEWEB)

Chibani, Omar, E-mail: omar.chibani@fccc.edu; C-M Ma, Charlie [Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States)

2014-05-15

Purpose: To present a new accelerated Monte Carlo code for CT-based dose calculations in high dose rate (HDR) brachytherapy. The new code (HDRMC) accounts for both tissue and nontissue heterogeneities (applicator and contrast medium). Methods: HDRMC uses a fast ray-tracing technique and detailed physics algorithms to transport photons through a 3D mesh of voxels representing the patient anatomy with applicator and contrast medium included. A precalculated phase space file for the{sup 192}Ir source is used as source term. HDRM is calibrated to calculated absolute dose for real plans. A postprocessing technique is used to include the exact density and composition of nontissue heterogeneities in the 3D phantom. Dwell positions and angular orientations of the source are reconstructed using data from the treatment planning system (TPS). Structure contours are also imported from the TPS to recalculate dose-volume histograms. Results: HDRMC was first benchmarked against the MCNP5 code for a single source in homogenous water and for a loaded gynecologic applicator in water. The accuracy of the voxel-based applicator model used in HDRMC was also verified by comparing 3D dose distributions and dose-volume parameters obtained using 1-mm{sup 3} versus 2-mm{sup 3} phantom resolutions. HDRMC can calculate the 3D dose distribution for a typical HDR cervix case with 2-mm resolution in 5 min on a single CPU. Examples of heterogeneity effects for two clinical cases (cervix and esophagus) were demonstrated using HDRMC. The neglect of tissue heterogeneity for the esophageal case leads to the overestimate of CTV D90, CTV D100, and spinal cord maximum dose by 3.2%, 3.9%, and 3.6%, respectively. Conclusions: A fast Monte Carlo code for CT-based dose calculations which does not require a prebuilt applicator model is developed for those HDR brachytherapy treatments that use CT-compatible applicators. Tissue and nontissue heterogeneities should be taken into account in modern HDR

Indeterminate lesions on planar bone scintigraphy in lung cancer patients: SPECT, CT or SPECT-CT?

International Nuclear Information System (INIS)

Sharma, Punit; Kumar, Rakesh; Singh, Harmandeep; Bal, Chandrasekhar; Malhotra, Arun; Julka, Pramod Kumar; Thulkar, Sanjay

2012-01-01

The objective of the present study was to compare the role of single photon emission computed tomography (SPECT), computed tomography (CT) and SPECT-CT of selected volume in lung cancer patients with indeterminate lesions on planar bone scintigraphy (BS). The data of 50 lung cancer patients (53 ± 10.3 years; range 30-75; male/female 38/12) with 65 indeterminate lesions on planar BS (January 2010 to November 2010) were retrospectively evaluated. All of them underwent SPECT-CT of a selected volume. SPECT, CT and SPECT-CT images were independently evaluated by two experienced readers (experience in musculoskeletal imaging, including CT: 5 and 7 years) in separate sessions. A scoring scale of 1 to 5 was used, in which 1 is definitely metastatic, 2 is probably metastatic, 3 is indeterminate, 4 is probably benign and 5 is definitely benign. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for each modality, taking a score ≤2 as metastatic. With receiver operating characteristic (ROC) curve analysis, areas under the curve (AUC) were calculated for each modality and compared. Clinical and imaging follow-up and/or histopathology were taken as reference standard. For both readers SPECT was inferior to CT (P = 0.004, P = 0.022) and SPECT-CT (P = 0.003, P = 0.037). However, no significant difference was found between CT and SPECT-CT for reader 1 (P = 0.847) and reader 2 (P = 0.592). The findings were similar for lytic as well as sclerotic lesions. Moderate inter-observer agreement was seen for SPECT images (κ = 0.426), while almost perfect agreement was seen for CT (κ = 0.834) and SPECT-CT (κ = 0.971). CT alone and SPECT-CT are better than SPECT for accurate characterisation of indeterminate lesions on planar BS in lung cancer patients. CT alone is not inferior to SPECT-CT for this purpose and might be preferred because of shorter acquisition time and wider availability. (orig.)

Piling up technology of goods irradiated by single plate source

International Nuclear Information System (INIS)

Xia Hezhou; Chen Yuxia; Cao Hongyun; Lin Yong; Zhou guoquan

1999-01-01

In the irradiation process of piling up goods in static state, four irradiation working sites and single plate source was adopted. The results showed that piling up in this way remarkably raised the irradiation quality of goods. The utilization rate of radioactive ray reached 22.27%

Controlling light emission from single-photon sources using photonic nanowires

DEFF Research Database (Denmark)

Gregersen, Niels; Chen, Yuntian; Mørk, Jesper

2012-01-01

The photonic nanowire has recently emerged as an promising alternative to microcavity-based single-photon source designs. In this simple structure, a geometrical effect ensures a strong coupling between an embedded emitter and the optical mode of interest and a combination of tapers and mirrors a...

Application of single- and dual-energy CT brain tissue segmentation to PET monitoring of proton therapy

Science.gov (United States)

Berndt, Bianca; Landry, Guillaume; Schwarz, Florian; Tessonnier, Thomas; Kamp, Florian; Dedes, George; Thieke, Christian; Würl, Matthias; Kurz, Christopher; Ganswindt, Ute; Verhaegen, Frank; Debus, Jürgen; Belka, Claus; Sommer, Wieland; Reiser, Maximilian; Bauer, Julia; Parodi, Katia

2017-03-01

The purpose of this work was to evaluate the ability of single and dual energy computed tomography (SECT, DECT) to estimate tissue composition and density for usage in Monte Carlo (MC) simulations of irradiation induced β + activity distributions. This was done to assess the impact on positron emission tomography (PET) range verification in proton therapy. A DECT-based brain tissue segmentation method was developed for white matter (WM), grey matter (GM) and cerebrospinal fluid (CSF). The elemental composition of reference tissues was assigned to closest CT numbers in DECT space (DECTdist). The method was also applied to SECT data (SECTdist). In a validation experiment, the proton irradiation induced PET activity of three brain equivalent solutions (BES) was compared to simulations based on different tissue segmentations. Five patients scanned with a dual source DECT scanner were analyzed to compare the different segmentation methods. A single magnetic resonance (MR) scan was used for comparison with an established segmentation toolkit. Additionally, one patient with SECT and post-treatment PET scans was investigated. For BES, DECTdist and SECTdist reduced differences to the reference simulation by up to 62% when compared to the conventional stoichiometric segmentation (SECTSchneider). In comparison to MR brain segmentation, Dice similarity coefficients for WM, GM and CSF were 0.61, 0.67 and 0.66 for DECTdist and 0.54, 0.41 and 0.66 for SECTdist. MC simulations of PET treatment verification in patients showed important differences between DECTdist/SECTdist and SECTSchneider for patients with large CSF areas within the treatment field but not in WM and GM. Differences could be misinterpreted as PET derived range shifts of up to 4 mm. DECTdist and SECTdist yielded comparable activity distributions, and comparison of SECTdist to a measured patient PET scan showed improved agreement when compared to SECTSchneider. The agreement between predicted and measured PET

Angiogenesis in hepatocellular carcinoma: correlation of single-level dynamic spiral CT scans in arterial phase and expression of α-smooth muscle actin

International Nuclear Information System (INIS)

Liu Yan; Min Pengqiu; Chen Weixia; Zhang Lin

2005-01-01

Objective: To investigate the correlation between the single-level dynamic spiral CT scans (SDCT) of hepatocellular carcinoma (HCC) in arterial phase (AP) and the immunohistochemistry expression of α-smooth muscle actin (ASMA). Methods: 33 cases of suspected HCC undergoing spiral CT plain scan of the whole liver, the single-level dynamic scan of the target level of lesion in AP and finally the whole liver scan in portal-venous phase before operations and proved after were included into the study. After the SDCT, a time-density curve (T-DC) was drawn according to the density change of the region of interest (ROI) of the tumor parenchyma with some parameters calculated, and signs of enhancement evaluated. Slices of post-operation specimen underwent hemotoxylin-eosin (HE) and ASMA immunohistochemistry staining. Then the slices were evaluated with emphases on the ASMA-positive neovasculatures in the parenchyma and mesenchyma of carcinomas, and the average count in a low microscopic field (x 100) was recorded (5 low microscopic field were observed and then an average was calculated.). Finally the immunohistochemistry and histologic results were correlated with image findings. Results: According to the PV of the tumor parenchyma, T-DC was divided into type I, II and III in which the criteria were PV>80, 40 HU< PV< 80 HU and PV<40 HU respectively. In the 33 cases, type I, II and III of T-DC were 3, 17 and 13 cases with PV of 103.30, 57.65 and 33.55 HU respectively. In ASMA immunohistochemistry study, ASMA-positive neovasculatures were devided into type A with a thick wall and B with a thin wall. The mean count of neovasculatures of tumor parenchyma in type I, II and III of T-DC were 10, 4.59 and 1 respectively. Statistically, different types of T-DC were significantly correlated with the count of neovasculatures in the parenchyma of carcinomas (r=-0.567, P<0.01). Homogeneous and inhomogeneous enhancement of carcinomas during SDCT in AP were correlated with the

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

Dual source multidetector CT-angiography before transcatheter aortic valve implantation (TAVI) using a high-pitch spiral acquisition mode

Energy Technology Data Exchange (ETDEWEB)

Wuest, W.; Anders, K.; May, M.S.; Uder, M. [University of Erlangen, Department of Radiology, Erlangen (Germany); Schuhbaeck, A.; Gauss, S.; Marwan, M.; Arnold, M.; Muschiol, G.; Daniel, W.G.; Achenbach, S. [University of Erlangen, Department of Cardiology, Erlangen (Germany); Ensminger, S. [University of Erlangen, Department of Cardiac Surgery, Erlangen (Germany)

2012-01-15

Transcatheter Aortic Valve Implantation (TAVI) is an alternative to surgical valve replacement in high risk patients. Angiography of the aortic root, aorta and iliac arteries is required to select suitable candidates, but contrast agents can be harmful due to impaired renal function. We evaluated ECG-triggered high-pitch spiral dual source Computed Tomography (CT) with minimized volume of contrast agent to assess aortic root anatomy and vascular access. 42 patients (82 {+-} 6 years) scheduled for TAVI underwent dual source (DS) CT angiography (CTA) of the aorta using a prospectively ECG-triggered high-pitch spiral mode (pitch = 3.4) with 40 mL iodinated contrast agent. We analyzed aortic root/iliac dimensions, attenuation, contrast to noise ratio (CNR), image noise and radiation exposure. Aortic root/iliac dimensions and distance of coronary ostia from the annulus could be determined in all cases. Mean aortic and iliac artery attenuation was 320 {+-} 70 HU and 340 {+-} 77 HU. Aortic/iliac CNR was 21.7 {+-} 6.8 HU and 14.5 {+-} 5.4 HU using 100 kV (18.8 {+-} 4.1 HU and 8.7 {+-} 2.6 HU using 120 kV). Mean effective dose was 4.5 {+-} 1.2 mSv. High-pitch spiral DSCTA can be used to assess the entire aorta and iliac arteries in TAVI candidates with a low volume of contrast agent while preserving diagnostic image quality. (orig.)

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.

Low tube voltage dual source computed tomography to reduce contrast media doses in adult abdomen examinations: A phantom study

Energy Technology Data Exchange (ETDEWEB)

Thor, Daniel [Department of Diagnostic Medical Physics, Karolinska University Hospital, Stockholm 14186 (Sweden); Brismar, Torkel B., E-mail: torkel.brismar@gmail.com; Fischer, Michael A. [Department of Clinical Science, Intervention and Technology at Karolinska Institutet and Department of Radiology, Karolinska University Hospital in Huddinge, Stockholm 14186 (Sweden)

2015-09-15

Purpose: To evaluate the potential of low tube voltage dual source (DS) single energy (SE) and dual energy (DE) computed tomography (CT) to reduce contrast media (CM) dose in adult abdominal examinations of various sizes while maintaining soft tissue and iodine contrast-to-noise ratio (CNR). Methods: Four abdominal phantoms simulating a body mass index of 16 to 35 kg/m{sup 2} with four inserted syringes of 0, 2, 4, and 8 mgI/ml CM were scanned using a 64-slice DS-CT scanner. Six imaging protocols were used; one single source (SS) reference protocol (120 kV, 180 reference mAs), four low kV SE protocols (70 and 80 kV using both SS and DS), and one DE protocol at 80/140 kV. Potential CM reduction with unchanged CNRs relative to the 120 kV protocol was calculated along with the corresponding increase in radiation dose. Results: The potential contrast media reductions were determined to be approximately 53% for DS 70 kV, 51% for SS 70 kV, 44% for DS 80 kV, 40% for SS 80 kV, and 20% for DE (all differences were significant, P < 0.05). Constant CNR could be achieved by using DS 70 kV for small to medium phantom sizes (16–26 kg/m{sup 2}) and for all sizes (16–35 kg/m{sup 2}) when using DS 80 kV and DE. Corresponding radiation doses increased by 60%–107%, 23%–83%, and 6%–12%, respectively. Conclusions: DS single energy CT can be used to reduce CM dose by 44%–53% with maintained CNR in adult abdominal examinations at the cost of an increased radiation dose. DS dual-energy CT allows reduction of CM dose by 20% at similar radiation dose as compared to a standard 120 kV single source.

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.

Comparison of CT- and radiograph-based post-implant dosimetry for transperineal 125I prostate brachytherapy using single seeds and a commercial treatment-planning software

International Nuclear Information System (INIS)

Siebert, F.A.; Kohr, P.; Kovacs, G.

2006-01-01

Background and purpose: the objective of this investigation was a direct comparison of the dosimetry of CT-based and radiograph-based postplanning procedures for seed implants. Patients and methods: CT- and radiograph-based postplans were carried out for eight iodine-125 ( 125 I) seed implant patients with a commercial treatment-planning system (TPS). To assess a direct comparison of the dosimetric indices (D90, V100, V400), the radiograph-based seed coordinates were transformed to the coordinate system of the CT postplan. Afterwards, the CT-based seed positions were replaced by the radiograph-based coordinates in the TPS and the dose distribution was recalculated. Results: the computations demonstrated that the radiograph-based dosimetric values for the prostate (D p 90, V p 100, and V p 400) were on average lower than the values of the CT postplan. Normalized to the CT postplan the following mean values were found: D p 90: 90.6% (standard deviation [SD]: 9.0%), V p 100: 86.1% (SD: 14.7%), and V p 400: 79.4% (SD: 14.4%). For three out of the eight patients the D p 90 decreased to 90% of the initial CT postplan values. The reason for this dosimetric difference is supposed to be evoked by an error of the reconstruction software used. It was detected that the TPS algorithm assigned some sources to wrong coordinates, partly out of the prostate gland. Conclusion: the radiograph-based postplanning technique of the investigated TPS should only be used in combination with CT postplanning. Furthermore, complex testing procedures of reconstruction algorithms are recommended to minimize calculation errors. (orig.)

Reprojection method using CT data. New means of visualization by improved technique

International Nuclear Information System (INIS)

Ishimori, Yoshiyuki; Tanaka, Masato; Komuro, Hiroyuki

1995-01-01

Reprojection Method (RPM) using computed tomography (CT) data can create simulating images of plain X-ray film. We could create material extracted images by selecting projected CT values, and created tomographic images by selecting spatial values. Virtual X-ray source can be set anywhere. So it can create stereographic images composed of a pair of beam's eye view, and can create panoramic images to set the source inside the volume data. Since RPM does not need the binaryzation process, the densities of the image reflect the original CT value of each voxel. RPM using CT data is a useful method to get the most information regarding X-ray attenuation and to cope with the fast scan CT system. (author)

Image quality and radiation dose of lower extremity CT angiography at 70 kVp on an integrated circuit detector dual-source computed tomography.

Science.gov (United States)

Qi, Li; Zhao, Yan'E; Zhou, Chang Sheng; Spearman, James V; Renker, Matthias; Schoepf, U Joseph; Zhang, Long Jiang; Lu, Guang Ming

2015-06-01

Despite the well-established requirement for radiation dose reduction there are few studies examining the potential for lower extremity CT angiography (CTA) at 70 kVp. To compare the image quality and radiation dose of lower extremity CTA at 70 kVp using a dual-source CT system with an integrated circuit detector to similar studies at 120 kVp. A total of 62 patients underwent lower extremity CTA. Thirty-one patients were examined at 70 kVp using a second generation dual-source CT with an integrated circuit detector (70 kVp group) and 31 patients were evaluated at 120 kVp using a first generation dual-source CT (120 kVp group). The attenuation and image noise were measured and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists assessed image quality. Radiation dose was compared. The mean attenuation of the 70 kVp group was higher than the 120 kVp group (575 ± 149 Hounsfield units [HU] vs. 258 ± 38 HU, respectively, P < 0.001) as was SNR (44.0 ± 22.0 vs 32.7 ± 13.3, respectively, P = 0.017), CNR (39.7 ± 20.6 vs 26.6 ± 11.7, respectively, P = 0.003) and the mean image quality score (3.7 ± 0.1 vs. 3.2 ± 0.3, respectively, P < 0.001). The inter-observer agreement was good for the 70 kVp group and moderate for the 120 kVp group. The dose-length product was lower in the 70 kVp group (264.5 ± 63.1 mGy × cm vs. 412.4 ± 81.5 mGy × cm, P < 0.001). Lower extremity CTA at 70 kVp allows for lower radiation dose with higher SNR, CNR, and image quality when compared with standard 120 kVp. © The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

The origins of SPECT and SPECT/CT

Energy Technology Data Exchange (ETDEWEB)

Hutton, Brian F. [University College London, Institute of Nuclear Medicine, London (United Kingdom); University of Wollongong, Centre for Medical Radiation Physics, Wollongong, NSW (Australia)

2014-05-15

Single photon emission computed tomography (SPECT) has a long history of development since its initial demonstration by Kuhl and Edwards in 1963. Although clinical utility has been dominated by the rotating gamma camera, there have been many technological innovations with the recent popularity of organ-specific dedicated SPECT systems. The combination of SPECT and CT evolved from early transmission techniques used for attenuation correction with the initial commercial systems predating the release of PET/CT. The development and acceptance of SPECT/CT has been relatively slow with continuing debate as to what cost/performance ratio is justified. Increasingly, fully diagnostic CT is combined with SPECT so as to facilitate optimal clinical utility. (orig.)

Radiation exposure in CT-guided interventions

Energy Technology Data Exchange (ETDEWEB)

Kloeckner, Roman, E-mail: Roman.Kloeckner@unimedizin-mainz.de [Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz (Germany); Santos, Daniel Pinto dos; Schneider, Jens [Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz (Germany); Kara, Levent [Department of Radiology, Inselspital Bern, Freiburgstraße 18, 3010 Bern (Switzerland); Dueber, Christoph; Pitton, Michael B. [Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University, Langenbeckstraße 1, 55131 Mainz (Germany)

2013-12-01

Purpose: To investigate radiation exposure in computed tomography (CT)-guided interventions, to establish reference levels for exposure, and to discuss strategies for dose reduction. Materials and methods: We analyzed 1576 consecutive CT-guided procedures in 1284 patients performed over 4.5 years, including drainage placements; biopsies of different organs; radiofrequency and microwave ablations (RFA/MWA) of liver, bone, and lung tumors; pain blockages, and vertebroplasties. Data were analyzed with respect to scanner settings, overall radiation doses, and individual doses of planning CT series, CT intervention, and control CT series. Results: Eighy-five percent of the total radiation dose was applied during the pre- and post-interventional CT series, leaving only 15% applied by the CT-guided intervention itself. Single slice acquisition was associated with lower doses than continuous CT-fluoroscopy (37 mGy cm vs. 153 mGy cm, p < 0.001). The third quartile of radiation doses varied considerably for different interventions. The highest doses were observed in complex interventions like RFA/MWA of the liver, followed by vertebroplasty and RFA/MWA of the lung. Conclusions: This paper suggests preliminary reference levels for various intervention types and discusses strategies for dose reduction. A multicenter registry of radiation exposure including a broader spectrum of scanners and intervention types is needed to develop definitive reference levels.

77 FR 38070 - Office of Refugee Resettlement; Announcing the Award of a Single-Source Program Expansion...

Science.gov (United States)

2012-06-26

....676] Office of Refugee Resettlement; Announcing the Award of a Single- Source Program Expansion... (BCFS) in San Antonio, TX AGENCY: Office of Refugee Resettlement, ACF, HHS. ACTION: The Office of Refugee Resettlement announces the award of a single-source program expansion supplement grant from its...

Computed tomography as a source of electron density information for radiation treatment planning

International Nuclear Information System (INIS)

Skrzynski, Witold; Slusarczyk-Kacprzyk, Wioletta; Bulski, Wojciech; Zielinska-Dabrowska, Sylwia; Wachowicz, Marta; Kukolowicz, Pawel F.

2010-01-01

Purpose: to evaluate the performance of computed tomography (CT) systems of various designs as a source of electron density (ρ el ) data for treatment planning of radiation therapy. Material and methods: dependence of CT numbers on relative electron density of tissue-equivalent materials (HU-ρ el relationship) was measured for several general-purpose CT systems (single-slice, multislice, wide-bore multislice), for radiotherapy simulators with a single-slice CT and kV CBCT (cone-beam CT) options, as well as for linear accelerators with kV and MV CBCT systems. Electron density phantoms of four sizes were used. Measurement data were compared with the standard HU-ρ el relationships predefined in two commercial treatment-planning systems (TPS). Results: the HU-ρ el relationships obtained with all of the general-purpose CT scanners operating at voltages close to 120 kV were very similar to each other and close to those predefined in TPS. Some dependency of HU values on tube voltage was observed for bone-equivalent materials. For a given tube voltage, differences in results obtained for different phantoms were larger than those obtained for different CT scanners. For radiotherapy simulators and for kV CBCT systems, the information on ρ el was much less precise because of poor uniformity of images. For MV CBCT, the results were significantly different than for kV systems due to the differing energy spectrum of the beam. Conclusion: the HU-ρ el relationships predefined in TPS can be used for general-purpose CT systems operating at voltages close to 120 kV. For nontypical imaging systems (e.g., CBCT), the relationship can be significantly different and, therefore, it should always be measured and carefully analyzed before using CT data for treatment planning. (orig.)

Dose reduction strategies for cardiac CT

International Nuclear Information System (INIS)

Midgley, S.M.; Einsiedel, P.; Langenberg, F.; Lui, E.

2010-01-01

Full text: Recent advances in CT technology have produced brighter X-ray sources. gantries capable of increased rotation speeds, faster scintil lation materials arranged into multiple rows of detectors, and associated advances in 3D reconstruction methods. These innovations have allowed multi-detector CT to be turned to the diagnosis of cardiac abnormalities and compliment traditional imaging techniques such as coronary angiography. This study examines the cardiac imaging solution offered by the Siemens Somatom Definition Dual Source 64 slice CT scanner. Our dose reduction strategies involve optimising the data acquisition protocols according to diagnostic task, patient size and heart rate. The relationship between scan parameters, image quality and patient dose is examined and verified against measurements with phantoms representing the standard size patient. The dose reduction strategies are reviewed with reference to survey results of patient dose. Some cases allow the insertion of shielding to protect radiosensitive organs, and results are presented to quantify the dose saving.

Recent advances in iterative reconstruction for clinical SPECT/PET and CT.

Science.gov (United States)

Hutton, Brian F

2011-08-01

Statistical iterative reconstruction is now widely used in clinical practice and has contributed to significant improvement in image quality in recent years. Although primarily used for reconstruction in emission tomography (both single photon emission computed tomography (SPECT) and positron emission tomography (PET)) there is increasing interest in also applying similar algorithms to x-ray computed tomography (CT). There is increasing complexity in the factors that are included in the reconstruction, a demonstration of the versatility of the approach. Research continues with exploration of methods for further improving reconstruction quality with effective correction for various sources of artefact.

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.

Synthesis of anisotropic CdS nanostructures via a single-source route

CSIR Research Space (South Africa)

Rajasekhar Pullabhotla, VSR

2011-02-01

Full Text Available A cadmium tetrahydroisoquinoline dithiocarbamate (DTC) complex has been used as single-source precursor for the synthesis of highly faceted hexadecylamine (HDA) capped CdS nanoparticles. Hexagonal and close to cubic shaped particles with distinct...

Multifragmentation of a very heavy nuclear system (I): selection of single-source events

Energy Technology Data Exchange (ETDEWEB)

Frankland, J.D.; Bacri, Ch.O.; Borderie, B. [Paris-11 Univ., Inst. de Physique Nucleaire, 91 - Orsay (France)] [and others

2000-07-01

A sample of 'single-source' events, compatible with the multifragmentation of very heavy fused systems, are isolated among well-measured {sup 155}Gd + {sup nat}U 36 A.MeV reactions by examining the evolution of the kinematics of fragments with Z {>=} 5 as a function of the dissipated energy and loss of memory of the entrance channel. Single-source events are found to be the result of very central collisions. Such central collisions may also lead to multiple fragment emission due to the decay of excited projectile- and target-like nuclei and so-called 'neck' emission, and for this reason the isolation of single-source events is very difficult. Event-selection criteria based on centrality of collisions, or on the isotropy of the emitted fragments in each event, are found to be inefficient to separate the two mechanisms, unless they take into account the redistribution of fragments' kinetic energies into directions perpendicular to the beam axis. The selected events are good candidates to look for bulk effects in the multifragmentation process. (authors)

Multifragmentation of a very heavy nuclear system (I): selection of single-source events

International Nuclear Information System (INIS)

Frankland, J.D.; Bacri, Ch.O.; Borderie, B.; Rivet, M.F.; Squalli, M.; Auger, G.; Bellaize, N.; Bocage, F.; Bougault, R.; Brou, R.; Buchet, Ph.; Chbihi, A.; Colin, J.; Cussol, D.; Dayras, R.; Demeyer, A.; Dore, D.; Durand, D.; Galichet, E.; Genouin-Duhamel, E.; Gerlic, E.; Guinet, D.; Lautesse, Ph.; Laville, J.L.; Lecolley, J.F.; Legrain, R.; Le Neindre, N.; Lopez, O.; Louvel, M.; Maskay, A.M.; Nalpas, L.; Nguyen, A.D.; Parlog, M.; Peter, J.; Plagnol, E.; Rosato, E.; Saint-Laurent, F.; Salou, S.; Steckmeyer, J.C.; Stern, M.; Tabacaru, G.; Tamain, B.; Tirel, O.; Tassan-Got, L.; Vient, E.; Volant, C.; Wieleczko, J.P.

2001-01-01

A sample of 'single-source' events, compatible with the multifragmentation of very heavy fused systems, are isolated among well-measured 155 Gd+ nat U 36 A MeV reactions by examining the evolution of the kinematics of fragments with Z≥5 as a function of the dissipated energy and loss of memory of the entrance channel. Single-source events are found to be the result of very central collisions. Such central collisions may also lead to multiple fragment emission due to the decay of excited projectile- and target-like nuclei and so-called 'neck' emission, and for this reason the isolation of single-source events is very difficult. Event-selection criteria based on centrality of collisions, or on the isotropy of the emitted fragments in each event, are found to be inefficient to separate the two mechanisms, unless they take into account the redistribution of fragments' kinetic energies into directions perpendicular to the beam axis. The selected events are good candidates to look for bulk effects in the multifragmentation process

Virtual unenhanced second generation dual-source CT of the liver: Is it time to discard the conventional unenhanced phase?

International Nuclear Information System (INIS)

Barrett, T.; Bowden, D.J.; Shaida, N.; Godfrey, E.M.; Taylor, A.; Lomas, D.J.; Shaw, A.S.

2012-01-01

Introduction: Dual-energy dual source CT can almost simultaneously image patients using two different tube potentials, allowing material decomposition and creation of ‘virtual unenhanced’ (VU) images from post-contrast series. Methods: 75 patients undergoing triple-phase liver CT examinations were imaged using a second generation dual-source CT machine with tube potentials 140/100 kVp. Post-processing VU series were derived from arterial and portal phases. Regions-of-interest from liver parenchyma and within fat (‘noise’ assessment) were drawn to compare VU series to conventional unenhanced (CU) series. Subjective analysis assessed image quality and the suitability of VU to replace CU series. Results: Mean Hounsfield unit (HU) values of liver were higher in the VU series: portal 51.9 (SD = 10.29), arterial 51.1 (SD = 10.05), compared to the CU series 49.2 (SD = 9.11); P < 0.001. However, Pearson's correlation of the VU and CU series remained excellent: 0.838 (portal), 0.831 (arterial). Bland–Altman plots also showed good agreement between both VU and the CU datasets. Noise measurements were significantly lower in both VU series (P < 0.001). For subjective analysis, image quality was rated as very good/excellent in 100% of CU images, 93.3% of portal VU and 88.7% of arterial VU series. Overall, portal VU and arterial VU images were acceptable replacements for the CU series in 97.4% and 96.1%, respectively. Post-processing was noted to create a number of artefacts in VU images – knowledge of these is essential for interpretation. Conclusions: Portal and arterial-derived VU images objectively correlate to CU images and demonstrate good image quality and acceptability. VU image sets could replace the conventional unenhanced images in the vast majority of cases, significantly reducing radiation dose.

Towards radiocarbon dating of single foraminifera with a gas ion source

Science.gov (United States)

Wacker, L.; Lippold, J.; Molnár, M.; Schulz, H.

2013-01-01

Carbonate shells from foraminifera are often analysed for radiocarbon to determine the age of deep-sea sediments or to assess radiocarbon reservoir ages. However, a single foraminiferal test typically contains only a few micrograms of carbon, while most laboratories require more than 100 μg for radiocarbon dating with an accelerator mass spectrometry (AMS) system. The collection of the required amount of foraminifera for a single analyses is therefore time consuming and not always possible. Here, we present a convenient method to measure the radiocarbon content of foraminifera using an AMS system fitted with a gas ion source. CO2 is liberated from 150 to 1150 μg of carbonate in septum sealed vials by acid decomposition of the carbonate. The CO2 is collected on a zeolite trap and subsequently transferred to a syringe from where it is delivered to the ion source. A sample of 400 μg (50 μg C) typically gives a 12C- ion source current of 10-15 μA over 20 min, yielding a measurement precision of less than 7 per mil for a modern sample. Using this method, we were able to date a single 560 μg Cibicides pseudoungerianus test at 14,030 ± 160 radiocarbon years. Only a minor modification to our existing gas handling system was required and the system is fully automatable to further reduce the effort involved for sample preparation.

Towards radiocarbon dating of single foraminifera with a gas ion source

International Nuclear Information System (INIS)

Wacker, L.; Lippold, J.; Molnár, M.; Schulz, H.

2013-01-01

Carbonate shells from foraminifera are often analysed for radiocarbon to determine the age of deep-sea sediments or to assess radiocarbon reservoir ages. However, a single foraminiferal test typically contains only a few micrograms of carbon, while most laboratories require more than 100 μg for radiocarbon dating with an accelerator mass spectrometry (AMS) system. The collection of the required amount of foraminifera for a single analyses is therefore time consuming and not always possible. Here, we present a convenient method to measure the radiocarbon content of foraminifera using an AMS system fitted with a gas ion source. CO 2 is liberated from 150 to 1150 μg of carbonate in septum sealed vials by acid decomposition of the carbonate. The CO 2 is collected on a zeolite trap and subsequently transferred to a syringe from where it is delivered to the ion source. A sample of 400 μg (50 μg C) typically gives a 12 C − ion source current of 10–15 μA over 20 min, yielding a measurement precision of less than 7 per mil for a modern sample. Using this method, we were able to date a single 560 μg Cibicides pseudoungerianus test at 14,030 ± 160 radiocarbon years. Only a minor modification to our existing gas handling system was required and the system is fully automatable to further reduce the effort involved for sample preparation.

Towards radiocarbon dating of single foraminifera with a gas ion source

Energy Technology Data Exchange (ETDEWEB)

Wacker, L., E-mail: wacker@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Lippold, J. [Heidelberg Academy of Sciences, 69120 Heidelberg (Germany); Molnar, M. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Institute of Nuclear Research, Hungarian Academy of Sciences, 4026 Debrecen (Hungary); Schulz, H. [Institute for Geosciencies, University of Tuebingen, 72076 Tuebingen (Germany)

2013-01-15

Carbonate shells from foraminifera are often analysed for radiocarbon to determine the age of deep-sea sediments or to assess radiocarbon reservoir ages. However, a single foraminiferal test typically contains only a few micrograms of carbon, while most laboratories require more than 100 {mu}g for radiocarbon dating with an accelerator mass spectrometry (AMS) system. The collection of the required amount of foraminifera for a single analyses is therefore time consuming and not always possible. Here, we present a convenient method to measure the radiocarbon content of foraminifera using an AMS system fitted with a gas ion source. CO{sub 2} is liberated from 150 to 1150 {mu}g of carbonate in septum sealed vials by acid decomposition of the carbonate. The CO{sub 2} is collected on a zeolite trap and subsequently transferred to a syringe from where it is delivered to the ion source. A sample of 400 {mu}g (50 {mu}g C) typically gives a {sup 12}C{sup -} ion source current of 10-15 {mu}A over 20 min, yielding a measurement precision of less than 7 per mil for a modern sample. Using this method, we were able to date a single 560 {mu}g Cibicides pseudoungerianus test at 14,030 {+-} 160 radiocarbon years. Only a minor modification to our existing gas handling system was required and the system is fully automatable to further reduce the effort involved for sample preparation.

Detection of single-phase CTA occult vessel occlusions in acute ischemic stroke using CT perfusion-based wavelet-transformed angiography

Energy Technology Data Exchange (ETDEWEB)

Kunz, Wolfgang G.; Sommer, Wieland H.; Meinel, Felix G.; Ertl-Wagner, Birgit; Thierfelder, Kolja M. [Ludwig-Maximilian-University Hospital Munich, Institute for Clinical Radiology, Munich (Germany); Havla, Lukas; Dietrich, Olaf [Ludwig-Maximilian-University Hospital Munich, Josef Lissner Laboratory for Biomedical Imaging of the Institute for Clinical Radiology, Munich (Germany); Dorn, Franziska [Ludwig-Maximilian-University Hospital Munich, Department of Neuroradiology, Munich (Germany); Buchholz, Grete [Ludwig-Maximilian-University Hospital Munich, Department of Neurology, Munich (Germany)

2017-06-15

To determine the detection rate of intracranial vessel occlusions using CT perfusion-based wavelet-transformed angiography (waveletCTA) in acute ischemic stroke patients, in whom single-phase CTA (spCTA) failed to detect an occlusion. Subjects were selected from a cohort of 791 consecutive patients who underwent multiparametric CT including whole-brain CT perfusion. Inclusion criteria were (1) significant cerebral blood flow (CBF) deficit, (2) no evidence of vessel occlusion on spCTA and (3) follow-up-confirmed acute ischemic infarction. waveletCTA was independently analysed by two readers regarding presence and location of vessel occlusions. Logistic regression analysis was performed to identify predictors of waveletCTA-detected occlusions. Fifty-nine patients fulfilled the inclusion criteria. Overall, an occlusion was identified using waveletCTA in 31 (52.5 %) patients with negative spCTA. Out of 47 patients with middle cerebral artery infarction, 27 occlusions (57.4 %) were detected by waveletCTA, mainly located in the M2 (15) and M3 segments (8). The presence of waveletCTA-detected occlusions was associated with larger CBF deficit volumes (odds ratio (OR) = 1.335, p = 0.010) and shorter times from symptom onset (OR = 0.306, p = 0.041). waveletCTA is able to detect spCTA occult vessel occlusions in about half of acute ischemic stroke patients and may potentially identify more patients eligible for endovascular therapy. (orig.)

TU-F-CAMPUS-I-02: Validation of a CT X-Ray Source Characterization Technique for Dose Computation Using An Anthropomorphic Thorax Phantom

Energy Technology Data Exchange (ETDEWEB)

Sommerville, M; Tambasco, M [San Diego State University, San Diego, CA (United States); Poirier, Y [CancerCare Manitoba, Winnipeg, MB (Canada)

2015-06-15

Purpose: To experimentally validate a rotational kV x-ray source characterization technique by computing CT dose in an anthropomorphic thorax phantom using an in-house dose computation algorithm (kVDoseCalc). Methods: The lateral variation in incident energy spectra of a GE Optima big bore CT scanner was found by measuring the HVL along the internal, full bow-tie filter axis. The HVL and kVp were used to generate the x-ray spectra using Spektr software, while beam fluence was derived by dividing the integral product of the spectra and in-air mass-energy absorption coefficients by in-air dose measurements along the bow-tie filter axis. Beams produced by the GE Optima scanner were modeled at 80 and 140 kVp tube settings. kVDoseCalc calculates dose by solving the linear Boltzmann transport equation using a combination of deterministic and stochastic methods. Relative doses in an anthropomorphic thorax phantom (E2E SBRT Phantom) irradiated by the GE Optima scanner were measured using a (0.015 cc) PTW Freiburg ionization chamber, and compared to computations from kVDoseCalc. Results: The agreement in relative dose between dose computation and measurement for points of interest (POIs) within the primary path of the beam was within experimental uncertainty for both energies, however points outside the primary beam were not. The average absolute percent difference for POIs within the primary path of the beam was 1.37% and 5.16% for 80 and 140 kVp, respectively. The minimum and maximum absolute percent difference for both energies and all POIs within the primary path of the beam was 0.151% and 6.41%, respectively. Conclusion: The CT x-ray source characterization technique based on HVL measurements and kVp can be used to accurately compute CT dose in an anthropomorphic thorax phantom.

What is the difference in the hybrid imaging techniques - SPECT/CT and PET-CT and is there any advantage of their application?

International Nuclear Information System (INIS)

Kostadinova, I.

2012-01-01

The hybrid imaging methods - Single Photon Emission Tomography-Computer Tomography /SPECT-CT / and Positron Emission Tomography-Computer Tomography / PET-CT/ allow receiving of combined image of two different techniques. In such a way it is possible to superimpose detailed anatomical image of the multislice spiral computer tomography with specific and sensitive molecular images of the SPECT and PET in a single study, allowing utilization of the full possibilities of the both techniques. They have advantages and disadvantages, which basically stem from the differences in the used radiopharmaceuticals and their physical properties. In PET- CT - positron emitters are applied, most often 18F and 11C, while in SPECT-CT - single photon emitters, most often 99m Tc and 131 I. A disadvantage of PET is a high cost, which is produced in cyclotron and its logistics is complicated. The great advantage of PET is its better spatial resolution, compared to SPECT, because of the possibility for simultaneous detection of pared photons and better registration. These techniques, especially PET-CT are nowadays the most increasing imaging methods in the world in making diagnosis, staging and following the effect of treatment in patients with oncological, neurological, cardiological, orthopedic diseases and infections. Recently, they are applied for the purposes of radiotherapy planning on the basis of the metabolically active tumor. As a final result, compared to the conventional techniques - roentgenography, CT and MRI, it is possible in many cases to make an early and more precise diagnosis, saving patients' time and using most appropriate treatment. As a conclusion it is clear, that the hybrid imaging has future and its application will increase. (author)

Radiological diagnosis of chest wall tuberculosis: CT versus chest radiograph

International Nuclear Information System (INIS)

Liu Fugeng; Pan Jishu; Chen Qihang; Zhou Cheng; Yu Jingying; Tang Dairong

2006-01-01

Objective: To evaluate the role of CT or Chest radiograph in diagnosis of chest wall tuberculosis. Methods: The study population included 21 patients with chest wall tuberculosis confirmed by operation or biopsy. Chest radiograph and plain CT were performed in all eases, while enhanced CT in 9 cases, and all images were reviewed by 2 radiologists. Results: Single soft tissue mass of the chest wall was detected in all cases on CT, but not on chest radiograph(χ 2 =42.000, P 2 =4.421, P<0.05). Conclusion: CT, especially enhanced CT scan is the first choice in the diagnosis of chest wall tuberculosis. (authors)

Helical CT for secondary screening of lung cancer

International Nuclear Information System (INIS)

Mori, Kiyoshi; Onishi, Tsukasa; Tominaga, Keigo; Kishiro, Izumi; Yokoyama, Kohki.

1995-01-01

Helical CT was used on a trial basis for secondary screening of lung cancer, and its clinical usefulness is discussed in this report. The subjects of 157 patients with abnormal shadows on plain chest X-ray images were chosen between November 1993 and August 1994. Imaging parameters used for screening CT were as follows: 50 mA, 120 kV, a couch-top movement speed of 20 mm/s, and a beam width of 10 mm. The entire lung field was scanned during a single breath-hold. Reconstructed images were generated at 10-mm intervals by the 180deg interpolation method, and films were produced. Images of the entire lung field were made during a single breath-hold in all patients. Abnormal shadows were detected in 73 of 157 patients by screening CT. These 73 patients included 14 with lung cancer, 53 with benign lesions, one under observation, and five others. The average diameter of the tumors was 11.1 mm. The lung cancers detected all arose in the periphery, and were classified into stage I (10 patients), stage IIIA (3 patients), and stage IV with bone metastases (1 patient). Lung cancers in clinical stage I (3 patients) and stage IV (1 patient) were difficult to see on plain chest X-ray films. We conclude that screening CT is useful for early diagnosis of lung cancer because the entire lung field can be imaged during a single breath-hold. Therefore, helical CT can be expected to be useful in screening for lung cancer. (author)

Calibrate the aerial surveying instrument by the limited surface source and the single point source that replace the unlimited surface source

CERN Document Server

Lu Cun Heng

1999-01-01

It is described that the calculating formula and surveying result is found on the basis of the stacking principle of gamma ray and the feature of hexagonal surface source when the limited surface source replaces the unlimited surface source to calibrate the aerial survey instrument on the ground, and that it is found in the light of the exchanged principle of the gamma ray when the single point source replaces the unlimited surface source to calibrate aerial surveying instrument in the air. Meanwhile through the theoretical analysis, the receiving rate of the crystal bottom and side surfaces is calculated when aerial surveying instrument receives gamma ray. The mathematical expression of the gamma ray decaying following height according to the Jinge function regularity is got. According to this regularity, the absorbing coefficient that air absorbs the gamma ray and the detective efficiency coefficient of the crystal is calculated based on the ground and air measuring value of the bottom surface receiving cou...

On-demand semiconductor single-photon source with near-unity indistinguishability.

Science.gov (United States)

He, Yu-Ming; He, Yu; Wei, Yu-Jia; Wu, Dian; Atatüre, Mete; Schneider, Christian; Höfling, Sven; Kamp, Martin; Lu, Chao-Yang; Pan, Jian-Wei

2013-03-01

Single-photon sources based on semiconductor quantum dots offer distinct advantages for quantum information, including a scalable solid-state platform, ultrabrightness and interconnectivity with matter qubits. A key prerequisite for their use in optical quantum computing and solid-state networks is a high level of efficiency and indistinguishability. Pulsed resonance fluorescence has been anticipated as the optimum condition for the deterministic generation of high-quality photons with vanishing effects of dephasing. Here, we generate pulsed single photons on demand from a single, microcavity-embedded quantum dot under s-shell excitation with 3 ps laser pulses. The π pulse-excited resonance-fluorescence photons have less than 0.3% background contribution and a vanishing two-photon emission probability. Non-postselective Hong-Ou-Mandel interference between two successively emitted photons is observed with a visibility of 0.97(2), comparable to trapped atoms and ions. Two single photons are further used to implement a high-fidelity quantum controlled-NOT gate.

Discrimination and anatomical mapping of PET-positive lesions: comparison of CT attenuation-corrected PET images with coregistered MR and CT images in the abdomen

Energy Technology Data Exchange (ETDEWEB)

Kuhn, Felix P.; Crook, David W.; Mader, Caecilia E.; Appenzeller, Philippe; Schulthess, G.K. von; Schmid, Daniel T. [University Hospital Zurich, Department of Medical Radiology, Zurich (Switzerland)

2013-01-15

PET/MR has the potential to become a powerful tool in clinical oncological imaging. The purpose of this prospective study was to evaluate the performance of a single T1-weighted (T1w) fat-suppressed unenhanced MR pulse sequence of the abdomen in comparison with unenhanced low-dose CT images to characterize PET-positive lesions. A total of 100 oncological patients underwent sequential whole-body {sup 18}F-FDG PET with CT-based attenuation correction (AC), 40 mAs low-dose CT and two-point Dixon-based T1w 3D MRI of the abdomen in a trimodality PET/CT-MR system. PET-positive lesions were assessed by CT and MRI with regard to their anatomical location, conspicuity and additional relevant information for characterization. From among 66 patients with at least one PET-positive lesion, 147 lesions were evaluated. No significant difference between MRI and CT was found regarding anatomical lesion localization. The MR pulse sequence used performed significantly better than CT regarding conspicuity of liver lesions (p < 0.001, Wilcoxon signed ranks test), whereas no difference was noted for extrahepatic lesions. For overall lesion characterization, MRI was considered superior to CT in 40 % of lesions, equal to CT in 49 %, and inferior to CT in 11 %. Fast Dixon-based T1w MRI outperformed low-dose CT in terms of conspicuity and characterization of PET-positive liver lesions and performed similarly in extrahepatic tumour manifestations. Hence, under the assumption that the technical issue of MR AC for whole-body PET examinations is solved, in abdominal PET/MR imaging the replacement of low-dose CT by a single Dixon-based MR pulse sequence for anatomical lesion correlation appears to be valid and robust. (orig.)

Discrimination and anatomical mapping of PET-positive lesions: comparison of CT attenuation-corrected PET images with coregistered MR and CT images in the abdomen

International Nuclear Information System (INIS)

Kuhn, Felix P.; Crook, David W.; Mader, Caecilia E.; Appenzeller, Philippe; Schulthess, G.K. von; Schmid, Daniel T.

2013-01-01

PET/MR has the potential to become a powerful tool in clinical oncological imaging. The purpose of this prospective study was to evaluate the performance of a single T1-weighted (T1w) fat-suppressed unenhanced MR pulse sequence of the abdomen in comparison with unenhanced low-dose CT images to characterize PET-positive lesions. A total of 100 oncological patients underwent sequential whole-body 18 F-FDG PET with CT-based attenuation correction (AC), 40 mAs low-dose CT and two-point Dixon-based T1w 3D MRI of the abdomen in a trimodality PET/CT-MR system. PET-positive lesions were assessed by CT and MRI with regard to their anatomical location, conspicuity and additional relevant information for characterization. From among 66 patients with at least one PET-positive lesion, 147 lesions were evaluated. No significant difference between MRI and CT was found regarding anatomical lesion localization. The MR pulse sequence used performed significantly better than CT regarding conspicuity of liver lesions (p < 0.001, Wilcoxon signed ranks test), whereas no difference was noted for extrahepatic lesions. For overall lesion characterization, MRI was considered superior to CT in 40 % of lesions, equal to CT in 49 %, and inferior to CT in 11 %. Fast Dixon-based T1w MRI outperformed low-dose CT in terms of conspicuity and characterization of PET-positive liver lesions and performed similarly in extrahepatic tumour manifestations. Hence, under the assumption that the technical issue of MR AC for whole-body PET examinations is solved, in abdominal PET/MR imaging the replacement of low-dose CT by a single Dixon-based MR pulse sequence for anatomical lesion correlation appears to be valid and robust. (orig.)

Computed Tomography of the Head and Neck Region for Tumor Staging-Comparison of Dual-Source, Dual-Energy and Low-Kilovolt, Single-Energy Acquisitions.

Science.gov (United States)

May, Matthias Stefan; Bruegel, Joscha; Brand, Michael; Wiesmueller, Marco; Krauss, Bernhard; Allmendinger, Thomas; Uder, Michael; Wuest, Wolfgang

2017-09-01

The aim of this study was to intra-individually compare the image quality obtained by dual-source, dual-energy (DSDE) computed tomography (CT) examinations and different virtual monoenergetic reconstructions to a low single-energy (SE) scan. Third-generation DSDE-CT was performed in 49 patients with histologically proven malignant disease of the head and neck region. Weighted average images (WAIs) and virtual monoenergetic images (VMIs) for low (40 and 60 keV) and high (120 and 190 keV) energies were reconstructed. A second scan aligned to the jaw, covering the oral cavity, was performed for every patient to reduce artifacts caused by dental hardware using a SE-CT protocol with 70-kV tube voltages and matching radiation dose settings. Objective image quality was evaluated by calculating contrast-to-noise ratios. Subjective image quality was evaluated by experienced radiologists. Highest contrast-to-noise ratios for vessel and tumor attenuation were obtained in 40-keV VMI (all P image quality was also highest for 40-keV, but differences to 60-keV VMI, WAI, and 70-kV SE were nonsignificant (all P > 0.05). High kiloelectron volt VMIs reduce metal artifacts with only limited diagnostic impact because of insufficiency in case of severe dental hardware. CTDIvol did not differ significantly between both examination protocols (DSDE: 18.6 mGy; 70-kV SE: 19.4 mGy; P = 0.10). High overall image quality for tumor delineation in head and neck imaging were obtained with 40-keV VMI. However, 70-kV SE examinations are an alternative and modified projections aligned to the jaw are recommended in case of severe artifacts caused by dental hardware.

Ionization dual-zone static detector having single radioactive source

International Nuclear Information System (INIS)

Ried, L. Jr.; Wade, A.L.

1977-01-01

This ionization detector or combustion product detector includes a single radioactive source located in an ionization chamber, and the ionization chamber includes portions comprising a reference zone and a signal zone. Electrical circuitry connected to the reference and signal zones provides an output signal directly related to changes in voltages across the signal zone in relation to the amount of particulates of combustion present in the ionization chamber

Creation and recovery of a W(111) single atom gas field ion source

International Nuclear Information System (INIS)

Pitters, Jason L.; Urban, Radovan; Wolkow, Robert A.

2012-01-01

Tungsten single atom tips have been prepared from a single crystal W(111) oriented wire using the chemical assisted field evaporation and etching method. Etching to a single atom tip occurs through a symmetric structure and leads to a predictable last atom unlike etching with polycrystalline tips. The single atom tip formation procedure is shown in an atom by atom removal process. Rebuilds of single atom tips occur on the same crystalline axis as the original tip such that ion emission emanates along a fixed direction for all tip rebuilds. This preparation method could be utilized and developed to prepare single atom tips for ion source development.

National survey of CT colonography practice in Ireland

LENUS (Irish Health Repository)

Smyth, A.E.

2016-06-01

CT Colonography was first introduced to Ireland in 1999. Our aim of this study is to review current CT Colonography practices in the Republic of Ireland. A questionnaire on CT Colonography practice was sent to all non-maternity adult radiology departments in the Republic of Ireland with a CT scanner. The results are interpreted in the context of the recommendations on CT Colonography quality standards as published by the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus statement in the journal of European Radiology in 2013. Thirty centres provide CT Colonography; 21 of which responded (70%). Each centre performs median 90 studies per year; the majority follow accepted patient preparation and image acquisition protocols. Seventy-six percent of the centres repsonded that the majority of patients imaged are symptomatic. Of the 51 consultant radiologists reading CT Colonography, 37 (73%) have attended a CT Colonography course. In 17 (81%) of the centres the studies are single read although 81% of the centres have access to a second radiologist’s opinion. Fourteen (67%) of the centres reported limited access to CT scanner time as the major limiting factor to expanding their service. CT Colonography is widely

Highly efficient electron gun with a single-atom electron source

International Nuclear Information System (INIS)

Ishikawa, Tsuyoshi; Urata, Tomohiro; Cho, Boklae; Rokuta, Eiji; Oshima, Chuhei; Terui, Yoshinori; Saito, Hidekazu; Yonezawa, Akira; Tsong, Tien T.

2007-01-01

The authors have demonstrated highly collimated electron-beam emission from a practical electron gun with a single-atom electron source; ∼80% of the total emission current entered the electron optics. This ratio was two or three orders of magnitude higher than those of the conventional electron sources such as a cold field emission gun and a Zr/O/W Schottky gun. At the pressure of less than 1x10 -9 Pa, the authors observed stable emission of 20 nA, which generates the specimen current of 5 pA required for scanning electron microscopes

Impact in the facilities design and the personnel formation of the hybrid equipment s: PET-CT; Impacto en el diseno de instalaciones y en la formacion del personal de los equipos hibridos: PET-CT

Energy Technology Data Exchange (ETDEWEB)

Hernandez, R.; Soler, K.; Alonso, I., E-mail: ramon@orasen.co.cu [Centro Nacional de Seguridad Nuclear, Calle 28 No. 504, Miramar, La Habana (Cuba)

2014-08-15

The Positron Emission Tomography-Computed Tomography (PET-CT), in the last years has demonstrated to be an image technique very effective for the diagnosis and the treatments continuation in different medical applications, because provides a valuable clinical information for the patient handling. The PET-CT is a technology used in the nuclear medicine for diagnostic, because integrates two different image techniques in an only device and in a single exam or study combine the results of both techniques. Also, is a hybrid tomograph that provides in a single image the biochemical information of a technique and the anatomical information of the other, what means that unifies the spatial resolution of a technique and the contrast resolution of the other, allowing this way to obtain a more precise and detailed diagnostic information, opening new opportunities in diagnostic, Radiotherapy planning and treatments continuation to the patients, being generated new links among the different radiological medical specialties. In nuclear medicine facilities with PET-CT, the radiological protection presents particular characteristics, due to the photons coexistence of 511 keV (generated by the annihilation of the emitted positrons from the different exposure sources) together to the X-rays emitted by the CT, what impacts in a direct way in those design requirements of the areas. On the other hand, this combination of the two image techniques imposes additional requirements to the learning and training of personnel, not considered until the present time. In this article are exposed the general principles that should be considered in the design of a Nuclear Medicine Area with PET-CT, and the existent problems related to the learning and training of personnel to assume this new technology are also approached. (Author)

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.)

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.

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.)

Functional CT imaging: load-dependent visualization of the subchondral mineralization by means of CT osteoabsorptionmetry (CT-OAM); Funktionelle Computertomographie: Beanspruchungsabhaengige Darstellung der subchondralen Mineralisierung mittels CT gestuetzter Osteoabsorptiometrie (CTOAM)

Energy Technology Data Exchange (ETDEWEB)

Linsenmaier, U.; Schlichtenhorst, K.; Pfeifer, K.J.; Reiser, M. [Inst. fuer Klinische Radiologie, Innenstadt, Ludwig-Maximilians-Univ. Muenchen (Germany); Kersting, S.; Putz, R.; Mueller-Gerbl, M. [Anatomische Anstalt, Ludwig-Maximilians-Univ. Muenchen (Germany)

2003-05-01

Purpose: Functional computed tomography for visualization and quantification of subchondral bone mineralization using CT osteoabsorptiometry (CT-OAM). Materials and Methods: Tarsometatarsal (TMT) and metatarsophalangeal (MTP) joints of 46 human hallux valgus (HV) specimens were examined (sagittal 1/1/1 mm) on a single slice CT scanner SCT (Somatom Plus 4, Siemens AG). Subchondral bone pixels were segmented and assigned to 10 density value groups (triangle 100 HU, range 200 - 1200 HU) the pixels using volume rendering technique (VRT). The data analysis considered the severity of HV as determined by the radiographically measured HV-angle (a.p. projection). Results: CT-OAM could generate reproducible densitograms of the distribution pattern of the subchondral bone density for all four joint surfaces (TMT and MTP joints). The bone density localization enables the assignment to different groups, showing a characteristic HV-angle-dependent distribution of the maximum bone mineralization of the load-dependent densitogram (p < 0.001). Conclusion: CT-OAM is a functional CT technique for visualizing and quantifying the distribution of the subchondral bone density, enabling a noninvasive load-dependent assessment of the joint surfaces. Load-dependent densitograms of hallux valgus specimens show a characteristic correlation with an increase of the HV-angle. (orig.) [German] Ziel: Darstellung und Quantifizierung der subchondralen Mineralisierung in Abhaengigkeit von unterschiedlichen Beanspruchungssituationen mittels funktioneller Computertomographie als CT-Osteoabsorptiometrie (CT-OAM). Methode: An 46 humanen Praeparaten mit Hallux valgus (HV) wurden exemplarisch die TMT I (Tarsometatarsal)- und MTP I (Metatarsophalangeal)-Gelenke des ersten Strahles (sagittal 1/1/1 mm) an einem Singleslice Spiral-CT (SCT, Somatom Plus 4, Siemens AG) untersucht. Der subchondrale Knochen wurde segmentiert, den Pixel wurde mittels Volume Rendering Technik (VRT) 10 Graustufenbereiche (D100 HU

A single-phase embedded Z-source DC-AC inverter.

Science.gov (United States)

Kim, Se-Jin; Lim, Young-Cheol

2014-01-01

In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

Gearbox Fault Diagnosis in a Wind Turbine Using Single Sensor Based Blind Source Separation

Directory of Open Access Journals (Sweden)

Yuning Qian

2016-01-01

Full Text Available This paper presents a single sensor based blind source separation approach, namely, the wavelet-assisted stationary subspace analysis (WSSA, for gearbox fault diagnosis in a wind turbine. Continuous wavelet transform (CWT is used as a preprocessing tool to decompose a single sensor measurement data into a set of wavelet coefficients to meet the multidimensional requirement of the stationary subspace analysis (SSA. The SSA is a blind source separation technique that can separate the multidimensional signals into stationary and nonstationary source components without the need for independency and prior information of the source signals. After that, the separated nonstationary source component with the maximum kurtosis value is analyzed by the enveloping spectral analysis to identify potential fault-related characteristic frequencies. Case studies performed on a wind turbine gearbox test system verify the effectiveness of the WSSA approach and indicate that it outperforms independent component analysis (ICA and empirical mode decomposition (EMD, as well as the spectral-kurtosis-based enveloping, for wind turbine gearbox fault diagnosis.

The Role of Skull Modeling in EEG Source Imaging for Patients with Refractory Temporal Lobe Epilepsy.

Science.gov (United States)

Montes-Restrepo, Victoria; Carrette, Evelien; Strobbe, Gregor; Gadeyne, Stefanie; Vandenberghe, Stefaan; Boon, Paul; Vonck, Kristl; Mierlo, Pieter van

2016-07-01

We investigated the influence of different skull modeling approaches on EEG source imaging (ESI), using data of six patients with refractory temporal lobe epilepsy who later underwent successful epilepsy surgery. Four realistic head models with different skull compartments, based on finite difference methods, were constructed for each patient: (i) Three models had skulls with compact and spongy bone compartments as well as air-filled cavities, segmented from either computed tomography (CT), magnetic resonance imaging (MRI) or a CT-template and (ii) one model included a MRI-based skull with a single compact bone compartment. In all patients we performed ESI of single and averaged spikes marked in the clinical 27-channel EEG by the epileptologist. To analyze at which time point the dipole estimations were closer to the resected zone, ESI was performed at two time instants: the half-rising phase and peak of the spike. The estimated sources for each model were validated against the resected area, as indicated by the postoperative MRI. Our results showed that single spike analysis was highly influenced by the signal-to-noise ratio (SNR), yielding estimations with smaller distances to the resected volume at the peak of the spike. Although averaging reduced the SNR effects, it did not always result in dipole estimations lying closer to the resection. The proposed skull modeling approaches did not lead to significant differences in the localization of the irritative zone from clinical EEG data with low spatial sampling density. Furthermore, we showed that a simple skull model (MRI-based) resulted in similar accuracy in dipole estimation compared to more complex head models (based on CT- or CT-template). Therefore, all the considered head models can be used in the presurgical evaluation of patients with temporal lobe epilepsy to localize the irritative zone from low-density clinical EEG recordings.

New cardiac cameras: single-photon emission CT and PET.

Science.gov (United States)

Slomka, Piotr J; Berman, Daniel S; Germano, Guido

2014-07-01

measurements for this tracer. The availability of high-end CT component in most PET/CT configurations enables hybrid multimodality cardiac imaging protocols with calcium scoring or CT angiography or both. Copyright © 2014. Published by Elsevier Inc.

Evaluation of total workstation CT interpretation quality: a single-screen pilot study

Science.gov (United States)

Beard, David V.; Perry, John R.; Muller, Keith E.; Misra, Ram B.; Brown, P.; Hemminger, Bradley M.; Johnston, Richard E.; Mauro, J. Matthew; Jaques, P. F.; Schiebler, M.

1991-07-01

An interpretation report, generated with an electronic viewbox, is affected by two factors: image quality, which encompasses what can be seen on the display, and computer human interaction (CHI), which accounts for the cognitive load effect of locating, moving, and manipulating images with the workstation controls. While a number of subject experiments have considered image quality, only recently has the affect of CHI on total interpretation quality been measured. This paper presents the results of a pilot study conducted to evaluate the total interpretation quality of the FilmPlane2.2 radiology workstation for patient folders containing single forty-slice CT studies. First, radiologists interpreted cases and dictated reports using FilmPlane2.2. Requisition forms were provided. Film interpretation was provided by the original clinical report and interpretation forms generated from a previous experiment. Second, an evaluator developed a list of findings for each case based on those listed in all the reports for each case and then evaluated each report for its response on each finding. Third, the reports were compared to determine how well they agreed with one another. Interpretation speed and observation data was also gathered.

Cranial CT with 64-, 16-, 4- and single-slice CT systems-comparison of image quality and posterior fossa artifacts in routine brain imaging with standard protocols

Energy Technology Data Exchange (ETDEWEB)

Ertl-Wagner, Birgit; Eftimov, Lara; Becker, Christoph; Reiser, Maximilian [University of Munich, Grosshadern (Germany). Institute of Clinical Radiology; Blume, Jeffrey; Cormack, Jean [Brown University, Center for Statistical Sciences, Providence, RI (United States); Bruening, Roland; Brueckmann, Hartmut [University of Munich, Grosshadern (Germany). Department of Neuroradiology

2008-08-15

Posterior fossa artifacts constitute a characteristic limitation of cranial CT. To identify practical benefits and drawbacks of newer CT systems with reduced collimation in routine cranial imaging, we aimed to investigate image quality, posterior fossa artifacts and parenchymal delineation in non-enhanced CT (NECT) with 1-, 4-, 16- and 64-slice scanners using standard scan protocols. We prospectively enrolled 25 consecutive patients undergoing NECT on a 64-slice CT. Three groups with 25 patients having undergone NECT on 1-, 4- and 16-slice CT machines were matched regarding age and sex. Standard routine CT parameters were used on each CT system with helical acquisition in the posterior fossa; the parameters varied regarding collimation and radiation dose. Three blinded readers independently assessed the cases regarding image quality, infra- and supratentorial artifacts and delineation of brain parenchymal structures on a five-point ordinal scale. Reading orders were randomized. A proportional odds model that accounted for the correlated nature of the data was fit using generalized estimating equations. Posterior fossa artifacts were significantly reduced, and the delineation of infratentorial brain structures was significantly improved with the thinner collimation used for the newer CT systems (p<0.001). No significant differences were observed for midbrain structures (p>0.5). The thinner collimation available on modern CT systems leads to reduced posterior fossa artifacts and to a better delineation of brain parenchyma in the posterior fossa. (orig.)

75 FR 65494 - Award of Three Single-Source Expansion Supplements to The University of Colorado Health Sciences...

Science.gov (United States)

2010-10-25

... Single-Source Expansion Supplements to The University of Colorado Health Sciences Center in Aurora, CO...), Administration on Developmental Disabilities (ADD) has awarded three single-source expansion supplements for data... people with intellectual and developmental disabilities in all facets of community life. The University...

77 FR 58404 - Announcing the Award of Two Urgent Single-Source Grants To Support Unaccompanied Alien Children...

Science.gov (United States)

2012-09-20

...] Announcing the Award of Two Urgent Single-Source Grants To Support Unaccompanied Alien Children Program...) announces the award of two urgent single-source grants from the Unaccompanied Alien Children's Program to... providing services under the Unaccompanied Alien Children's program. Award Grantee organization Location...

Extramedullary pulmonary hematopoiesis causing pulmonary hypertension and severe tricuspid regurgitation detected by 99m technetium sulfur colloid bone marrow scan and single-photon emission computed tomography/CT

International Nuclear Information System (INIS)

Ali, Syed Zama; Clarke, Michael John; Kannivelu, Anbalagan; Chinchure, Dinesh; Srinivasan, Sivasubramanian

2014-01-01

Extramedullary pulmonary hematopoiesis is a rare entity with a limited number of case reports in the available literature only. We report the case of a 66-year-old man with known primary myelofibrosis, in whom a 99m technetium sulfur colloid bone marrow scan with single-photon emission computed tomography (SPECT)/CT revealed a pulmonary hematopoiesis as the cause of pulmonary hypertension and severe tricuspid regurgitation. To the best of our knowledge, this is the first description of 99m technetium sulfur colloid SPECT/CT imaging in this rare condition.

Methods of forming single source precursors, methods of forming polymeric single source precursors, and single source precursors and intermediate products formed by such methods

Science.gov (United States)

Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin; Margulieux, Kelsey R.; Holland, Andrew W.

2012-12-04

Methods of forming single source precursors (SSPs) include forming intermediate products having the empirical formula 1/2{L.sub.2N(.mu.-X).sub.2M'X.sub.2}.sub.2, and reacting MER with the intermediate products to form SSPs of the formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2, wherein L is a Lewis base, M is a Group IA atom, N is a Group IB atom, M' is a Group IIIB atom, each E is a Group VIB atom, each X is a Group VIIA atom or a nitrate group, and each R group is an alkyl, aryl, vinyl, (per)fluoro alkyl, (per)fluoro aryl, silane, or carbamato group. Methods of forming polymeric or copolymeric SSPs include reacting at least one of HE.sup.1R.sup.1E.sup.1H and MER with one or more substances having the empirical formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2 or L.sub.2N(.mu.-X).sub.2M'(X).sub.2 to form a polymeric or copolymeric SSP. New SSPs and intermediate products are formed by such methods.

Clinical assessment of SPECT/CT co-registration image fusion

International Nuclear Information System (INIS)

Zhou Wen; Luan Zhaosheng; Peng Yong

2004-01-01

Objective: Study the methodology of the SPECT/CT co-registration image fusion, and Assessment the Clinical application value. Method: 172 patients who underwent SPECT/CT image fusion during 2001-2003 were studied, 119 men, 53 women. 51 patients underwent 18FDG image +CT, 26 patients underwent 99m Tc-RBC Liver pool image +CT, 43 patients underwent 99mTc-MDP Bone image +CT, 18 patients underwent 99m Tc-MAA Lung perfusion image +CT. The machine is Millium VG SPECT of GE Company. All patients have been taken three steps image: X-ray survey, X-ray transmission and nuclear emission image (Including planer imaging, SPECT or 18 F-FDG of dual head camera) without changing the position of the patients. We reconstruct the emission image with X-ray map and do reconstruction, 18FDG with COSEM and 99mTc with OSEM. Then combine the transmission image and the reconstructed emission image. We use different process parameters in deferent image methods. The accurate rate of SPECT/CT image fusion were statistics, and compare their accurate with that of single nuclear emission image. Results: The nuclear image which have been reconstructed by X-ray attenuation and OSEM are apparent better than pre-reconstructed. The post-reconstructed emission images have no scatter lines around the organs. The outline between different issues is more clear than before. The validity of All post-reconstructed images is better than pre-reconstructed. SPECT/CT image fusion make localization have worthy bases. 138 patients, the accuracy of SPECT/CT image fusion is 91.3% (126/138), whereas 60(88.2%) were found through SPECT/CT image fusion, There are significant difference between them(P 99m Tc- RBC-SPECT +CT image fusion, but 21 of them were inspected by emission image. In BONE 99m Tc -MDP-SPECT +CT image fusion, 4 patients' removed bone(1-6 months after surgery) and their relay with normal bone had activity, their morphologic and density in CT were different from normal bones. 11 of 20 patients who could

Towards truly integrated hardware fusion with PET/CT

International Nuclear Information System (INIS)

Beyer, T.

2005-01-01

Combined PET/CT imaging is a non-invasive means of acquiring and reviewing both, the anatomy and the molecular pathways of a patient during a quasi-simultaneous examination. Since the introduction of the prototype PET/CT in 1998 this imaging technology has evolved rapidly. State-of-the-art PET/CT tomographs combine the latest technology in spiral, multi-slice CT and PET using novel scintillator materials and image reconstruction techniques. Together with novel patient positioning systems PET/CT tomographs allow to acquire complementary PET and CT data in a single exam with the best intrinsic co-registration. In addition to the hardware integration efforts have been made to integrate the acquisition and viewing software in PET/CT, thus making the diagnostic review and reporting more efficient. Based on the first clinical experiences and the technical evolution of combined imaging technology PET/CT has become a standard in diagnostic oncology. With high-performance imaging technology at hand today, standardized, high-quality PET/CT imaging protocols are needed to provide best oncology patient care. These protocols mandate the joint efforts of a multi-disciplinary team of physicians, physicists and radiochemists. (orig.)

Relationship between noise, dose, and pitch in cardiac multi-detector row CT.

Science.gov (United States)

Primak, Andrew N; McCollough, Cynthia H; Bruesewitz, Michael R; Zhang, Jie; Fletcher, Joel G

2006-01-01

In spiral computed tomography (CT), dose is always inversely proportional to pitch. However, the relationship between noise and pitch (and hence noise and dose) depends on the scanner type (single vs multi-detector row) and reconstruction mode (cardiac vs noncardiac). In single detector row spiral CT, noise is independent of pitch. Conversely, in noncardiac multi-detector row CT, noise depends on pitch because the spiral interpolation algorithm makes use of redundant data from different detector rows to decrease noise for pitch values less than 1 (and increase noise for pitch values > 1). However, in cardiac spiral CT, redundant data cannot be used because such data averaging would degrade the temporal resolution. Therefore, the behavior of noise versus pitch returns to the single detector row paradigm, with noise being independent of pitch. Consequently, since faster rotation times require lower pitch values in cardiac multi-detector row CT, dose is increased without a commensurate decrease in noise. Thus, the use of faster rotation times will improve temporal resolution, not alter noise, and increase dose. For a particular application, the higher dose resulting from faster rotation speeds should be justified by the clinical benefits of the improved temporal resolution. RSNA, 2006

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.

Experimental demonstration of passive acoustic imaging in the human skull cavity using CT-based aberration corrections.

Science.gov (United States)

Jones, Ryan M; O'Reilly, Meaghan A; Hynynen, Kullervo

2015-07-01

Experimentally verify a previously described technique for performing passive acoustic imaging through an intact human skull using noninvasive, computed tomography (CT)-based aberration corrections Jones et al. [Phys. Med. Biol. 58, 4981-5005 (2013)]. A sparse hemispherical receiver array (30 cm diameter) consisting of 128 piezoceramic discs (2.5 mm diameter, 612 kHz center frequency) was used to passively listen through ex vivo human skullcaps (n = 4) to acoustic emissions from a narrow-band fixed source (1 mm diameter, 516 kHz center frequency) and from ultrasound-stimulated (5 cycle bursts, 1 Hz pulse repetition frequency, estimated in situ peak negative pressure 0.11-0.33 MPa, 306 kHz driving frequency) Definity™ microbubbles flowing through a thin-walled tube phantom. Initial in vivo feasibility testing of the method was performed. The performance of the method was assessed through comparisons to images generated without skull corrections, with invasive source-based corrections, and with water-path control images. For source locations at least 25 mm from the inner skull surface, the modified reconstruction algorithm successfully restored a single focus within the skull cavity at a location within 1.25 mm from the true position of the narrow-band source. The results obtained from imaging single bubbles are in good agreement with numerical simulations of point source emitters and the authors' previous experimental measurements using source-based skull corrections O'Reilly et al. [IEEE Trans. Biomed. Eng. 61, 1285-1294 (2014)]. In a rat model, microbubble activity was mapped through an intact human skull at pressure levels below and above the threshold for focused ultrasound-induced blood-brain barrier opening. During bursts that led to coherent bubble activity, the location of maximum intensity in images generated with CT-based skull corrections was found to deviate by less than 1 mm, on average, from the position obtained using source-based corrections. Taken

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.)

The relationship between developmental lumbar spinal stenosis and its BMD value : comparison by single energy quantitative CT

International Nuclear Information System (INIS)

Kim, Hak Jin; Kim, Kun Il; Song, Keun Sung

1996-01-01

The purpose of this study is to evaluate the relationship between developmental lumbar spinal stenosis and its BMD value by using the single energy quantitative CT(SEQCT). Eighty normal volunteers(20-60years) were selected as a control group and 28 patients with developmental lumbar spinal stenosis were selected as a disease group. The two groups were divided into a younger (20-39 years) and an older subgroup (40-60 years), and were further divided into male and female subgroups. All the cases showed no evidence of metabolic disease, fracture, herniated nucleus pulposus, degererative spondylosis, infectious disease, tumors or had no history of absolute immobilization of more than two weeks. All underwent lumbar spine CT and SEQCT. we measured bone mineral density(BMD) at the cancellous bone of L1, 2, 3 and obtained the mean and its one standard deviation, and compared the data between each sub-group of the control and the disease group using ANOVA. There was a significant low BMD value in the younger male patient subgroup compared with the control subgroup(p<0.005). Developmental lumbar spinal stenosis in a young male may be a factor of decreasing BMD of the body of the spine

The relationship between developmental lumbar spinal stenosis and its BMD value : comparison by single energy quantitative CT

Energy Technology Data Exchange (ETDEWEB)

Kim, Hak Jin; Kim, Kun Il; Song, Keun Sung [Pusan National Univ. Hospital, Pusan (Korea, Republic of)

1996-03-01

The purpose of this study is to evaluate the relationship between developmental lumbar spinal stenosis and its BMD value by using the single energy quantitative CT(SEQCT). Eighty normal volunteers(20-60years) were selected as a control group and 28 patients with developmental lumbar spinal stenosis were selected as a disease group. The two groups were divided into a younger (20-39 years) and an older subgroup (40-60 years), and were further divided into male and female subgroups. All the cases showed no evidence of metabolic disease, fracture, herniated nucleus pulposus, degererative spondylosis, infectious disease, tumors or had no history of absolute immobilization of more than two weeks. All underwent lumbar spine CT and SEQCT. we measured bone mineral density(BMD) at the cancellous bone of L1, 2, 3 and obtained the mean and its one standard deviation, and compared the data between each sub-group of the control and the disease group using ANOVA. There was a significant low BMD value in the younger male patient subgroup compared with the control subgroup(p<0.005). Developmental lumbar spinal stenosis in a young male may be a factor of decreasing BMD of the body of the spine.

Dual-energy CT characteristics of colon and rectal cancer allows differentiation from stool by dual-source CT.

Science.gov (United States)

Özdeniz, İlknur; İdilman, İlkay S; Köklü, Seyfettin; Hamaloğlu, Erhan; Özmen, Mustafa; Akata, Deniz; Karçaaltıncaba, Muşturay

2017-01-01

We aimed to determine dual-energy computed tomography (DECT) characteristics of colorectal cancer and investigate effectiveness of DECT method in differentiating tumor from stool in patients with colorectal cancer. Fifty consecutive patients with colorectal tumors were enrolled. Staging was performed by DECT (80-140 kV) using dual-source CT after rectal air insufflation and without bowel preparation. Both visual and quantitative analyses were performed at 80 kV and 140 kV, on iodine map and virtual noncontrast (VNC) images. All colorectal tumors had homogeneous pattern on iodine map. Stools demonstrated heterogeneous pattern in 86% (43/50) and homogeneous pattern in 14% (7/50) on iodine maps and were less visible on VNC images. Median density of tumors was 54 HU (18-100 HU) on iodine map and 28 HU (11-56 HU) on VNC images. Median density of stool was 36.5 HU (8-165 HU) on iodine map and -135.5 HU (-438 HU to -13 HU) on VNC images. The density of stools was significantly lower than tumors on both iodine map and VNC images (P VNC images was -1 HU with area under the curve of 1 and a sensitivity and specificity of 100%. Density or visual analysis of iodine map and VNC DECT images allow accurate differentiation of tumor from stool.