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Sample records for low-dose x-ray computed

  1. Statistical models and regularization strategies in statistical image reconstruction of low-dose X-ray computed tomography: a survey

    CERN Document Server

    Zhang, Hao; Ma, Jianhua; Lu, Hongbing; Liang, Zhengrong

    2014-01-01

    Statistical image reconstruction (SIR) methods have shown potential to substantially improve the image quality of low-dose X-ray computed tomography (CT) as compared to the conventional filtered back-projection (FBP) method for various clinical tasks. According to the maximum a posterior (MAP) estimation, the SIR methods can be typically formulated by an objective function consisting of two terms: (1) data-fidelity (or equivalently, data-fitting or data-mismatch) term modeling the statistics of projection measurements, and (2) regularization (or equivalently, prior or penalty) term reflecting prior knowledge or expectation on the characteristics of the image to be reconstructed. Existing SIR methods for low-dose CT can be divided into two groups: (1) those that use calibrated transmitted photon counts (before log-transform) with penalized maximum likelihood (pML) criterion, and (2) those that use calibrated line-integrals (after log-transform) with penalized weighted least-squares (PWLS) criterion. Accurate s...

  2. Reducing Noises and Artifacts Simultaneously of Low-Dosed X-Ray Computed Tomography Using Bilateral Filter Weighted by Gaussian Filtered Sinogram

    Directory of Open Access Journals (Sweden)

    Shaoxiang Hu

    2012-01-01

    Full Text Available Existing sinogram restoration methods cannot handle noises and nonstationary artifacts simultaneously. Although bilateral filter provides an efficient way to preserve image details while denoising, its performance in sinogram restoration for low-dosed X-ray computed tomography (LDCT is unsatisfied. The main reason for this situation is that the range filter of the bilateral filter measures similarity by sinogram values, which are polluted seriously by noises and nonstationary artifacts of LDCT. In this paper, we propose a simple method to obtain satisfied restoration results for sinogram of LDCT. That is, the range filter weighs the similarity by Gaussian smoothed sinogram. Since smoothed sinogram can reduce the influence of both noises and nonstationary artifacts for similarity measurement greatly, our new method can provide more satisfied denoising results for sinogram restoration of LDCT. Experimental results show that our method has good visual quality and can preserve anatomy details in sinogram restoration even in both noises and non-stationary artifacts.

  3. 20 percent lower lung cancer mortality with low-dose CT vs chest X-ray

    Science.gov (United States)

    Scientists have found a 20 percent reduction in deaths from lung cancer among current or former heavy smokers who were screened with low-dose helical computed tomography (CT) versus those screened by chest X-ray.

  4. Noise Estimation for Single-Slice Sinogram of Low-Dose X-Ray Computed Tomography Using Homogenous Patch

    Directory of Open Access Journals (Sweden)

    Zhiwu Liao

    2012-01-01

    Full Text Available We present a new method to estimate noise for a single-slice sinogram of low-dose CT based on the homogenous patches centered at a special pixel, called center point, which has the smallest variance among all sinogram pixels. The homogenous patch, composed by homogenous points, is formed by the points similar to the center point using similarity sorting, similarity decreasing searching, and variance analysis in a very large neighborhood (VLN to avoid manual selection of parameter for similarity measures.Homogenous pixels in the VLN allow us find the largest number of samples, who have the highest similarities to the center point, for noise estimation, and the noise level can be estimated according to unbiased estimation.Experimental results show that for the simulated noisy sinograms, the method proposed in this paper can obtain satisfied noise estimation results, especially for sinograms with relatively serious noises.

  5. Feasibility study for application of the compressed-sensing framework to interior computed tomography (ICT) for low-dose, high-accurate dental x-ray imaging

    Science.gov (United States)

    Je, U. K.; Cho, H. M.; Cho, H. S.; Park, Y. O.; Park, C. K.; Lim, H. W.; Kim, K. S.; Kim, G. A.; Park, S. Y.; Woo, T. H.; Choi, S. I.

    2016-02-01

    In this paper, we propose a new/next-generation type of CT examinations, the so-called Interior Computed Tomography (ICT), which may presumably lead to dose reduction to the patient outside the target region-of-interest (ROI), in dental x-ray imaging. Here an x-ray beam from each projection position covers only a relatively small ROI containing a target of diagnosis from the examined structure, leading to imaging benefits such as decreasing scatters and system cost as well as reducing imaging dose. We considered the compressed-sensing (CS) framework, rather than common filtered-backprojection (FBP)-based algorithms, for more accurate ICT reconstruction. We implemented a CS-based ICT algorithm and performed a systematic simulation to investigate the imaging characteristics. Simulation conditions of two ROI ratios of 0.28 and 0.14 between the target and the whole phantom sizes and four projection numbers of 360, 180, 90, and 45 were tested. We successfully reconstructed ICT images of substantially high image quality by using the CS framework even with few-view projection data, still preserving sharp edges in the images.

  6. Data Acquisition System of Low-dose X-ray for People and Package Synchronous Detection

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Shuai; ZHANG; Guo-guang; FENG; Shu-qiang

    2015-01-01

    Low-dose X-ray system for people and parcel detection at the same time is a system of double angle one-dimensional array detector scanning imaging.It’s front detector using LYSO crystal of UM-MicroC Si-PMT.Each 16pixels package for a small module,and export signals.Each 8small modules composite one floor(128pixels

  7. Low-dose X-ray radiation induces structural alterations in proteins.

    Science.gov (United States)

    Borshchevskiy, Valentin; Round, Ekaterina; Erofeev, Ivan; Weik, Martin; Ishchenko, Andrii; Gushchin, Ivan; Mishin, Alexey; Willbold, Dieter; Büldt, Georg; Gordeliy, Valentin

    2014-10-01

    X-ray-radiation-induced alterations to protein structures are still a severe problem in macromolecular crystallography. One way to avoid the influence of radiation damage is to reduce the X-ray dose absorbed by the crystal during data collection. However, here it is demonstrated using the example of the membrane protein bacteriorhodopsin (bR) that even a low dose of less than 0.06 MGy may induce structural alterations in proteins. This dose is about 500 times smaller than the experimental dose limit which should ideally not be exceeded per data set (i.e. 30 MGy) and 20 times smaller than previously detected specific radiation damage at the bR active site. To date, it is the lowest dose at which radiation modification of a protein structure has been described. Complementary use was made of high-resolution X-ray crystallography and online microspectrophotometry to quantitatively study low-dose X-ray-induced changes. It is shown that structural changes of the protein correlate with the spectroscopically observed formation of the so-called bR orange species. Evidence is provided for structural modifications taking place at the protein active site that should be taken into account in crystallographic studies which aim to elucidate the molecular mechanisms of bR function.

  8. Exposure to Low-Dose X-Ray Radiation Alters Bone Progenitor Cells and Bone Microarchitecture.

    Science.gov (United States)

    Lima, Florence; Swift, Joshua M; Greene, Elisabeth S; Allen, Matthew R; Cunningham, David A; Braby, Leslie A; Bloomfield, Susan A

    2017-08-03

    Exposure to high-dose ionizing radiation during medical treatment exerts well-documented deleterious effects on bone health, reducing bone density and contributing to bone growth retardation in young patients and spontaneous fracture in postmenopausal women. However, the majority of human radiation exposures occur in a much lower dose range than that used in the radiation oncology clinic. Furthermore, very few studies have examined the effects of low-dose ionizing radiation on bone integrity and results have been inconsistent. In this study, mice were irradiated with a total-body dose of 0.17, 0.5 or 1 Gy to quantify the early (day 3 postirradiation) and delayed (day 21 postirradiation) effects of radiation on bone microarchitecture and bone marrow stromal cells (BMSCs). Female BALBc mice (4 months old) were divided into four groups: irradiated (0.17, 0.5 and 1 Gy) and sham-irradiated controls (0 Gy). Micro-computed tomography analysis of distal femur trabecular bone from animals at day 21 after exposure to 1 Gy of X-ray radiation revealed a 21% smaller bone volume (BV/TV), 22% decrease in trabecular numbers (Tb.N) and 9% greater trabecular separation (Tb.Sp) compared to sham-irradiated controls (P < 0.05). We evaluated the differentiation capacity of bone marrow stromal cells harvested at days 3 and 21 postirradiation into osteoblast and adipocyte cells. Osteoblast and adipocyte differentiation was decreased when cells were harvested at day 3 postirradiation but enhanced in cells isolated at day 21 postirradiation, suggesting a compensatory recovery process. Osteoclast differentiation was increased in 1 Gy irradiated BMSCs harvested at day 3 postirradiation, but not in those harvested at day 21 postirradiation, compared to controls. This study provides evidence of an early, radiation-induced decrease in osteoblast activity and numbers, as well as a later recovery effect after exposure to 1 Gy of X-rays, whereas osteoclastogenesis was enhanced. A better

  9. Low dose digital X-ray imaging with avalanche amorphous selenium

    Science.gov (United States)

    Scheuermann, James R.; Goldan, Amir H.; Tousignant, Olivier; Léveillé, Sébastien; Zhao, Wei

    2015-03-01

    Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depth-independent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

  10. Low dose X -ray effects on catalase activity in animal tissue

    Science.gov (United States)

    Focea, R.; Nadejde, C.; Creanga, D.; Luchian, T.

    2012-12-01

    This study was intended to investigate the effect of low-dose X ray-irradiation upon the activity of catalase (CAT) in freshly excised chicken tissues (liver, kidney, brain, muscle). The tissue samples were irradiated with 0.5Gy and 2Gy respectively, in a 6 MV photon beam produced by a clinical linear accelerator (VARIAN CLINAC 2100SC). The dose rate was of 260.88cGy/min. at 100 cm source to sample distance. The catalase level was assayed spectrophotometrically, based on reaction kinetics, using a catalase UV assay kit (SIGMA). Catalase increased activity in various tissue samples exposed to the studied X ray doses (for example with 24 % in the liver cells, pantioxidant enzyme biosynthesis within several hours after exposure at doses of 0.5 Gy and 2 Gy; the putative enzyme inactivation could also occur (due to the injuries on the hydrogen bonds that ensure the specificity of CAT active site) but the resulted balance of the two concurrent processes indicates the cell ability of decomposing the hydrogen peroxide-with benefits for the cell physiology restoration for the chosen low dose radiation.

  11. Low-dose x-ray phase-contrast and absorption CT using equally sloped tomography

    Science.gov (United States)

    Fahimian, Benjamin P.; Mao, Yu; Cloetens, Peter; Miao, Jianwei

    2010-09-01

    Tomographic reconstruction from undersampled and noisy projections is often desirable in transmission CT modalities for purposes of low-dose tomography and fast acquisition imaging. However under such conditions, due to the violation of the Nyquist sampling criteria and the presence of noise, reconstructions with acceptable accuracy may not be possible. Recent experiments in transmission electron tomography and coherent diffraction microscopy have shown that the technique of equally sloped tomography (EST), an exact tomographic method utilizing an oversampling iterative Fourier-based reconstruction, provides more accurate image reconstructions when the number of projections is significantly undersampled relative to filtered back projection and algebraic iterative methods. Here we extend this technique by developing new reconstruction algorithms which allow for the incorporation of advanced mathematical regularization constraints, such as the nonlocal means total variational model, in a manner that is consistent with experimental projections. We then evaluate the resulting image quality of the developed algorithm through simulations and experiments at the European Synchrotron Radiation Facility on image quality phantoms using the x-ray absorption and phase contrast CT modalities. Both our simulation and experimental results have indicated that the method can reduce the number of projections by 60-75% in parallel beam modalities, while achieving comparable or better image quality than the conventional reconstructions. As large-scale and compact synchrotron radiation facilities are currently under rapid development worldwide, the implementation of low-dose x-ray absorption and phase-contrast CT can find broad applications in biology and medicine using these advanced x-ray sources.

  12. Low-dose x-ray phase-contrast and absorption CT using equally sloped tomography

    Energy Technology Data Exchange (ETDEWEB)

    Fahimian, Benjamin P; Miao Jianwei [Department of Physics and Astronomy, and the California NanoSystems Institute, University of California, Los Angeles, CA 90095 (United States); Mao Yu [Department of Mathematics, University of California, Los Angeles, CA 90095 (United States); Cloetens, Peter, E-mail: miao@physics.ucla.ed, E-mail: fahimian@stanford.ed [European Synchrotron Radiation Facility, BP 220, 6 Rue Jules Horowitz, 38043 Grenoble Cedex (France)

    2010-09-21

    Tomographic reconstruction from undersampled and noisy projections is often desirable in transmission CT modalities for purposes of low-dose tomography and fast acquisition imaging. However under such conditions, due to the violation of the Nyquist sampling criteria and the presence of noise, reconstructions with acceptable accuracy may not be possible. Recent experiments in transmission electron tomography and coherent diffraction microscopy have shown that the technique of equally sloped tomography (EST), an exact tomographic method utilizing an oversampling iterative Fourier-based reconstruction, provides more accurate image reconstructions when the number of projections is significantly undersampled relative to filtered back projection and algebraic iterative methods. Here we extend this technique by developing new reconstruction algorithms which allow for the incorporation of advanced mathematical regularization constraints, such as the nonlocal means total variational model, in a manner that is consistent with experimental projections. We then evaluate the resulting image quality of the developed algorithm through simulations and experiments at the European Synchrotron Radiation Facility on image quality phantoms using the x-ray absorption and phase contrast CT modalities. Both our simulation and experimental results have indicated that the method can reduce the number of projections by 60-75% in parallel beam modalities, while achieving comparable or better image quality than the conventional reconstructions. As large-scale and compact synchrotron radiation facilities are currently under rapid development worldwide, the implementation of low-dose x-ray absorption and phase-contrast CT can find broad applications in biology and medicine using these advanced x-ray sources.

  13. Low-dose CT of the paranasal sinuses. Minimizing X-ray exposure with spectral shaping

    Energy Technology Data Exchange (ETDEWEB)

    Wuest, Wolfgang [Friedrich-Alexander-University Erlangen-Nuremberg, Radiological Institute, Erlangen (Germany); Radiological Institute, Erlangen (Germany); May, Matthias; Saake, Marc; Brand, Michael; Uder, Michael; Lell, Michael [Friedrich-Alexander-University Erlangen-Nuremberg, Radiological Institute, Erlangen (Germany)

    2016-11-15

    Shaping the energy spectrum of the X-ray beam has been shown to be beneficial in low-dose CT. This study's aim was to investigate dose and image quality of tin filtration at 100 kV for pre-operative planning in low-dose paranasal CT imaging in a large patient cohort. In a prospective trial, 129 patients were included. 64 patients were randomly assigned to the study protocol (100 kV with additional tin filtration, 150mAs, 192 x 0.6-mm slice collimation) and 65 patients to the standard low-dose protocol (100 kV, 50mAs, 128 x 0.6-mm slice collimation). To assess the image quality, subjective parameters were evaluated using a five-point scale. This scale was applied on overall image quality and contour delineation of critical anatomical structures. All scans were of diagnostic image quality. Bony structures were of good diagnostic image quality in both groups, soft tissues were of sufficient diagnostic image quality in the study group because of a high level of noise. Radiation exposure was very low in both groups, but significantly lower in the study group (CTDI{sub vol} 1.2 mGy vs. 4.4 mGy, p < 0.001). Spectral optimization (tin filtration at 100 kV) allows for visualization of the paranasal sinus with sufficient image quality at a very low radiation exposure. (orig.)

  14. Low-Dose CT of the Paranasal Sinuses: Minimizing X-Ray Exposure with Spectral Shaping.

    Science.gov (United States)

    Wuest, Wolfgang; May, Matthias; Saake, Marc; Brand, Michael; Uder, Michael; Lell, Michael

    2016-11-01

    Shaping the energy spectrum of the X-ray beam has been shown to be beneficial in low-dose CT. This study's aim was to investigate dose and image quality of tin filtration at 100 kV for pre-operative planning in low-dose paranasal CT imaging in a large patient cohort. In a prospective trial, 129 patients were included. 64 patients were randomly assigned to the study protocol (100 kV with additional tin filtration, 150mAs, 192x0.6-mm slice collimation) and 65 patients to the standard low-dose protocol (100 kV, 50mAs, 128 × 0.6-mm slice collimation). To assess the image quality, subjective parameters were evaluated using a five-point scale. This scale was applied on overall image quality and contour delineation of critical anatomical structures. All scans were of diagnostic image quality. Bony structures were of good diagnostic image quality in both groups, soft tissues were of sufficient diagnostic image quality in the study group because of a high level of noise. Radiation exposure was very low in both groups, but significantly lower in the study group (CTDIvol 1.2 mGy vs. 4.4 mGy, p image quality at a very low radiation exposure. • Spectral optimization (tin filtration) is beneficial to low-dose parasinus CT • Tin filtration at 100 kV yields sufficient image quality for pre-operative planning • Diagnostic parasinus CT can be performed with an effective dose <0.05 mSv.

  15. X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kalender, Willi A [Institute of Medical Physics, University Erlangen-Nuernberg, Henkestr. 91, D-91052 Erlangen (Germany)

    2006-07-07

    X-ray computed tomography (CT), introduced into clinical practice in 1972, was the first of the modern slice-imaging modalities. To reconstruct images mathematically from measured data and to display and to archive them in digital form was a novelty then and is commonplace today. CT has shown a steady upward trend with respect to technology, performance and clinical use independent of predictions and expert assessments which forecast in the 1980s that it would be completely replaced by magnetic resonance imaging. CT not only survived but exhibited a true renaissance due to the introduction of spiral scanning which meant the transition from slice-by-slice imaging to true volume imaging. Complemented by the introduction of array detector technology in the 1990s, CT today allows imaging of whole organs or the whole body in 5 to 20 s with sub-millimetre isotropic resolution. This review of CT will proceed in chronological order focussing on technology, image quality and clinical applications. In its final part it will also briefly allude to novel uses of CT such as dual-source CT, C-arm flat-panel-detector CT and micro-CT. At present CT possibly exhibits a higher innovation rate than ever before. In consequence the topical and most recent developments will receive the greatest attention. (review)

  16. New quantum detection system for very low dose X-ray radiology

    CERN Document Server

    Hilt, B; Prevot, G

    2000-01-01

    A new X-ray radiology system has been devised that significantly reduces the dose of radiation administered to patients in spinal X-ray examinations. The apparatus scans the patient, using a high-efficiency linear solid-state detector and highly sensitive electronics, operating in counting mode. Two specific integrated circuits were developed, one of which contains an automatic offset correction. The detection system characterization data will be briefly presented. Data is acquired in real time by a high-speed computer-controlled VME system. The scan parameters and image filtering are also computer-controlled. The first images recorded using this new apparatus are given, along with the preliminary comparative dosimetric analysis.

  17. The effects of rat's sperm bioassay for low dose X-ray

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Gye Hwan; Min, Soo Young; Lee, Sang Bock; Lee, Sam Yul; Lee, Jun Haeng [Nambu Univ., Gwangju (Korea, Republic of); Park, Jong Bae [Juseong College, Cheongwon (Korea, Republic of)

    2007-12-15

    In order to investigate the enhancement effects of low dose radiation on biological activation, this study applied low dose X-ray to the whole body of male rats to find out whether hormesis is induced in male germ cells. Total 36 Sprague-Dawley (SD) rats as experimental animal were subdivided into 6 groups(in 6 rats per group) such as control, 10 mGy, 20 mGy, 50 mGy, 100 mGy and 200 mGy radiation group. All the groups showed slightly increasing number of sperms per 0.1 g semen (14.216 x 10{sup 6}, 13.901 x 10{sup 6}, 14.153 x 10{sup 6}, 13.831 x 10{sup 6}, 14.137 x 10{sup 6}, 14.677 x 10{sup 6} respectively), and the motility of sperms amounted to 50.9%, 49.5%, 55.1%, 54.3%, 48.0% and 52.2% respectively. Particularly, compared to the control, the other 5 groups showed higher male hormone level, and the microscopic observations of testicle tissues showed no vacuolization in seminiferous tubules and testis cells. In the results of this experiment, no harmful effect was observed on Sprague-Dawley (SD) rats for which the dose of radiation was controlled as regulated legally by the Ministry of Science and Technology and the Ministry of Health and Welfare. However, as these results were obtained from a limited number of animals, we cannot maintain that the same effect will be observed in the human body. Therefore, there should be further research on the effect on other animals and ultimately on the human body.

  18. Low-dose 4D myocardial perfusion with x-ray micro-CT

    Science.gov (United States)

    Clark, D. P.; Badea, C. T.

    2017-03-01

    X-ray CT is widely used, both clinically and pre-clinically, for fast, high-resolution, anatomic imaging; however, compelling opportunities exist to expand its use in functional imaging applications. For instance, temporally-resolved CT data can detail cardiac motion and blood flow dynamics for one-stop cardiovascular CT imaging procedures. In previous work, we demonstrated efficient, low-dose projection acquisition and reconstruction strategies for cardiac micro-CT imaging and for multiple-injection micro-CT perfusion imaging. Here, we extend this previous work with regularization based on rank-sparse kernel regression and on filtration with the Karhunen-Loeve transform. Using a dual source, prospectively gated sampling strategy which produces an approximately uniform distribution of projections, we apply this revised algorithm to the assessment of both myocardial perfusion and cardiac functional metrics from the same set of projection data. We test the algorithm in simulations using a modified version of the MOBY mouse phantom which contains realistic perfusion and cardiac dynamics. The proposed algorithm reduces the reconstruction error by 81% relative to unregularized, algebraic reconstruction. The results confirm our ability to simultaneously solve for cardiac temporal motion and perfusion dynamics. In future work, we will apply the algorithm and sampling protocol to small animal cardiac studies.

  19. Low-dose phase-based X-ray imaging techniques for in situ soft tissue engineering assessments.

    Science.gov (United States)

    Izadifar, Zohreh; Honaramooz, Ali; Wiebe, Sheldon; Belev, George; Chen, Xiongbiao; Chapman, Dean

    2016-03-01

    In tissue engineering, non-invasive imaging of biomaterial scaffolds and tissues in living systems is essential to longitudinal animal studies for assessments without interrupting the repair process. Conventional X-ray imaging is inadequate for use in soft tissue engineering due to the limited absorption difference between the soft tissue and biomaterial scaffolds. X-ray phase-based imaging techniques that derive contrast from refraction or phase effects rather than absorption can provide the necessary contrast to see low-density biomaterial scaffolds and tissues in large living systems. This paper explores and compares three synchrotron phase-based X-ray imaging techniques-computed tomography (CT)-diffraction enhanced imaging (DEI), -analyzer based imaging (ABI), and -phase contrast imaging (PCI)-for visualization and characterization of low-density biomaterial scaffolds and tissues in situ for non-invasive soft tissue engineering assessments. Intact pig joints implanted with polycaprolactone scaffolds were used as the model to assess and compare the imaging techniques in terms of different qualitative and quantitative criteria. For long-term in vivo live animal imaging, different strategies for reducing the imaging radiation dose and scan time-reduced number of CT projections, region of interest, and low resolution imaging-were examined with the presented phase-based imaging techniques. The results demonstrated promising capabilities of the phase-based techniques for visualization of biomaterial scaffolds and soft tissues in situ. The low-dose imaging strategies were illustrated effective for reducing the radiation dose to levels appropriate for live animal imaging. The comparison among the imaging techniques suggested that CT-DEI has the highest efficiency in retaining image contrast at considerably low radiation doses.

  20. SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) for low dose x-ray imaging: Spatial resolution

    OpenAIRE

    2008-01-01

    An indirect flat panel imager (FPI) with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose and high resolution x-ray imaging. It is made by optically coupling a structured x-ray scintillator, e.g., thallium (Tl) doped cesium iodide (CsI), to an amorphous selenium (a-Se) avalanche photoconductor called high-gain avalanche rushing amorphous photoconductor (HARP). The charge image created by the scintillator∕HARP (SHARP) combination is read out ...

  1. A Model of Regularization Parameter Determination in Low-Dose X-Ray CT Reconstruction Based on Dictionary Learning

    Directory of Open Access Journals (Sweden)

    Cheng Zhang

    2015-01-01

    Full Text Available In recent years, X-ray computed tomography (CT is becoming widely used to reveal patient’s anatomical information. However, the side effect of radiation, relating to genetic or cancerous diseases, has caused great public concern. The problem is how to minimize radiation dose significantly while maintaining image quality. As a practical application of compressed sensing theory, one category of methods takes total variation (TV minimization as the sparse constraint, which makes it possible and effective to get a reconstruction image of high quality in the undersampling situation. On the other hand, a preliminary attempt of low-dose CT reconstruction based on dictionary learning seems to be another effective choice. But some critical parameters, such as the regularization parameter, cannot be determined by detecting datasets. In this paper, we propose a reweighted objective function that contributes to a numerical calculation model of the regularization parameter. A number of experiments demonstrate that this strategy performs well with better reconstruction images and saving of a large amount of time.

  2. Watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice modulates oxidative damage induced by low dose X-ray in mice.

    Science.gov (United States)

    Mohammad, Mohd Khairul Amran; Mohamed, Muhamad Idham; Zakaria, Ainul Mardhiyah; Abdul Razak, Hairil Rashmizal; Saad, Wan Mazlina Md

    2014-01-01

    Watermelon is a natural product that contains high level of antioxidants and may prevent oxidative damage in tissues due to free radical generation following an exposure to ionizing radiation. The present study aimed to investigate the radioprotective effects of watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice against oxidative damage induced by low dose X-ray exposure in mice. Twelve adult male ICR mice were randomly divided into two groups consisting of radiation (Rx) and supplementation (Tx) groups. Rx received filtered tap water, while Tx was supplemented with 50% (v/v) watermelon juice for 28 days ad libitum prior to total body irradiation by 100 μGy X-ray on day 29. Brain, lung, and liver tissues were assessed for the levels of malondialdehyde (MDA), apurinic/apyrimidinic (AP) sites, glutathione (GSH), and superoxide dismutase (SOD) inhibition activities. Results showed significant reduction of MDA levels and AP sites formation of Tx compared to Rx (P Citrullus lanatus (Thunb.) Matsum. and Nakai) juice could modulate oxidative damage induced by low dose X-ray exposure.

  3. Watermelon (Citrullus lanatus (Thunb. Matsum. and Nakai Juice Modulates Oxidative Damage Induced by Low Dose X-Ray in Mice

    Directory of Open Access Journals (Sweden)

    Mohd Khairul Amran Mohammad

    2014-01-01

    Full Text Available Watermelon is a natural product that contains high level of antioxidants and may prevent oxidative damage in tissues due to free radical generation following an exposure to ionizing radiation. The present study aimed to investigate the radioprotective effects of watermelon (Citrullus lanatus (Thunb. Matsum. and Nakai juice against oxidative damage induced by low dose X-ray exposure in mice. Twelve adult male ICR mice were randomly divided into two groups consisting of radiation (Rx and supplementation (Tx groups. Rx received filtered tap water, while Tx was supplemented with 50% (v/v watermelon juice for 28 days ad libitum prior to total body irradiation by 100 μGy X-ray on day 29. Brain, lung, and liver tissues were assessed for the levels of malondialdehyde (MDA, apurinic/apyrimidinic (AP sites, glutathione (GSH, and superoxide dismutase (SOD inhibition activities. Results showed significant reduction of MDA levels and AP sites formation of Tx compared to Rx (P<0.05. Mice supplemented with 50% watermelon juice restore the intracellular antioxidant activities by significantly increased SOD inhibition activities and GSH levels compared to Rx. These findings may postulate that supplementation of 50% watermelon (Citrullus lanatus (Thunb. Matsum. and Nakai juice could modulate oxidative damage induced by low dose X-ray exposure.

  4. Rapid, low dose X-ray diffractive imaging of the malaria parasite Plasmodium falciparum

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Michael W.M., E-mail: michael.jones@latrobe.edu.au [ARC Centre of Excellence for Coherent X-Ray Science, Department of Physics, La Trobe University, Victoria 3086 (Australia); Dearnley, Megan K. [ARC Centre of Excellence for Coherent X-Ray Science, Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Victoria 3010 (Australia); Riessen, Grant A. van [ARC Centre of Excellence for Coherent X-Ray Science, Department of Physics, La Trobe University, Victoria 3086 (Australia); Abbey, Brian [ARC Centre of Excellence for Coherent X-Ray Science, Department of Physics, La Trobe University, Victoria 3086 (Australia); Melbourne Centre for Nanofabrication, Victoria 3168 (Australia); Putkunz, Corey T. [ARC Centre of Excellence for Coherent X-Ray Science, School of Physics, The University of Melbourne, Victoria 3010 (Australia); Junker, Mark D. [ARC Centre of Excellence for Coherent X-Ray Science, Department of Physics, La Trobe University, Victoria 3086 (Australia); Vine, David J. [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); McNulty, Ian [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Centre for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Nugent, Keith A. [ARC Centre of Excellence for Coherent X-Ray Science, Department of Physics, La Trobe University, Victoria 3086 (Australia); Peele, Andrew G. [ARC Centre of Excellence for Coherent X-Ray Science, Department of Physics, La Trobe University, Victoria 3086 (Australia); Australian Synchrotron, 800 Blackburn Road, Clayton 3168 (Australia); Tilley, Leann [ARC Centre of Excellence for Coherent X-Ray Science, Department of Biochemistry and Molecular Biology, Bio21 Institute, The University of Melbourne, Victoria 3010 (Australia)

    2014-08-01

    Phase-diverse X-ray coherent diffractive imaging (CDI) provides a route to high sensitivity and spatial resolution with moderate radiation dose. It also provides a robust solution to the well-known phase-problem, making on-line image reconstruction feasible. Here we apply phase-diverse CDI to a cellular sample, obtaining images of an erythrocyte infected by the sexual stage of the malaria parasite, Plasmodium falciparum, with a radiation dose significantly lower than the lowest dose previously reported for cellular imaging using CDI. The high sensitivity and resolution allow key biological features to be identified within intact cells, providing complementary information to optical and electron microscopy. This high throughput method could be used for fast tomographic imaging, or to generate multiple replicates in two-dimensions of hydrated biological systems without freezing or fixing. This work demonstrates that phase-diverse CDI is a valuable complementary imaging method for the biological sciences and ready for immediate application. - Highlights: • Phase-diverse coherent X-ray diffraction microscopy provides high-resolution and high-contrast images of intact biological samples. • Rapid nanoscale resolution imaging is demonstrated at orders of magnitude lower dose than previously possible. • Phase-diverse coherent X-ray diffraction microscopy is a robust technique for rapid, quantitative, and correlative X-ray phase imaging.

  5. Low Dose X-Ray Sources and High Quantum Efficiency Sensors: The Next Challenge in Dental Digital Imaging?

    Directory of Open Access Journals (Sweden)

    Arnav R. Mistry

    2014-01-01

    Full Text Available Objective(s. The major challenge encountered to decrease the milliamperes (mA level in X-ray imaging systems is the quantum noise phenomena. This investigation evaluated dose exposure and image resolution of a low dose X-ray imaging (LDXI prototype comprising a low mA X-ray source and a novel microlens-based sensor relative to current imaging technologies. Study Design. A LDXI in static (group 1 and dynamic (group 2 modes was compared to medical fluoroscopy (group 3, digital intraoral radiography (group 4, and CBCT scan (group 5 using a dental phantom. Results. The Mann-Whitney test showed no statistical significance (α=0.01 in dose exposure between groups 1 and 3 and 1 and 4 and timing exposure (seconds between groups 1 and 5 and 2 and 3. Image resolution test showed group 1 > group 4 > group 2 > group 3 > group 5. Conclusions. The LDXI proved the concept for obtaining a high definition image resolution for static and dynamic radiography at lower or similar dose exposure and smaller pixel size, respectively, when compared to current imaging technologies. Lower mA at the X-ray source and high QE at the detector level principles with microlens could be applied to current imaging technologies to considerably reduce dose exposure without compromising image resolution in the near future.

  6. Early effects of low dose 12C6+ ion or X-ray irradiation on human peripheral blood lymphocytes

    Science.gov (United States)

    Chen, Yingtai; Li, Yumin; Zhang, Hong; Xie, Yi; Chen, Xuezhong; Ren, Jinyu; Zhang, Xiaowei; Zhu, Zijiang; Liu, Hongliang; Zhang, Yawei

    2010-04-01

    The aim of this study was to estimate the acute effects of low dose 12C6+ ions or X-ray radiation on human immune function. The human peripheral blood lymphocytes (HPBL) of seven healthy donors were exposed to 0.05 Gy 12C6+ ions or X-ray radiation and cell responses were measured at 24 h after exposure. The cytotoxic activities of HPBL were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT); the percentages of T and NK cells subsets were detected by flow cytometry; mRNA expression of interleukin (IL)-2, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were examined by real time quantitative RT-PCR (qRT-PCR); and these cytokines protein levels in supernatant of cultured cells were assayed by enzyme-linked immunosorbent assays (ELISA). The results showed that the cytotoxic activity of HPBL, mRNA expression of IL-2, IFN-γ and TNF-α in HPBL and their protein levels in supernatant were significantly increased at 24 h after exposure to 0.05 Gy 12C6+ ions radiation and the effects were stronger than observed for X-ray exposure. However, there was no significant change in the percentage of T and NK cells subsets of HPBL. These results suggested that 0.05 Gy high linear energy transfer (LET) 12C6+ radiation was a more effective approach to host immune enhancement than that of low LET X-ray. We conclude that cytokines production might be used as sensitive indicators of acute response to LDI.

  7. Biphasic and triphasic dose responses in zebrafish embryos to low-dose 150 kV X-rays with different levels of hardness.

    Science.gov (United States)

    Kong, Eva Yi; Cheng, Shuk Han; Yu, Kwan Ngok

    2016-07-01

    The in vivo low-dose responses of zebrafish (Danio rerio) embryos to 150 kV X-rays with different levels of hardness were examined through the number of apoptotic events revealed at 24 h post fertilization by vital dye acridine orange staining. Our results suggested that a triphasic dose response was likely a common phenomenon in living organisms irradiated by X-rays, which comprised an ultra-low-dose inhibition, low-dose stimulation and high-dose inhibition. Our results also suggested that the hormetic zone (or the stimulation zone) was shifted towards lower doses with application of filters. The non-detection of a triphasic dose response in previous experiments could likely be attributed to the use of hard X-rays, which shifted the hormetic zone into an unmonitored ultra-low-dose region. In such cases where the subhormetic zone was missed, a biphasic dose response would be reported instead.

  8. SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) for low dose x-ray imaging: spatial resolution.

    Science.gov (United States)

    Li, Dan; Zhao, Wei

    2008-07-01

    An indirect flat panel imager (FPI) with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose and high resolution x-ray imaging. It is made by optically coupling a structured x-ray scintillator, e.g., thallium (Tl) doped cesium iodide (CsI), to an amorphous selenium (a-Se) avalanche photoconductor called high-gain avalanche rushing amorphous photoconductor (HARP). The charge image created by the scintillator/HARP (SHARP) combination is read out by the electron beams emitted from the FEA. The proposed detector is called scintillator avalanche photoconductor with high resolution emitter readout (SAPHIRE). The programmable avalanche gain of HARP can improve the low dose performance of indirect FPI while the FEA can be made with pixel sizes down to 50 microm. Because of the avalanche gain, a high resolution type of CsI (Tl), which has not been widely used in indirect FPI due to its lower light output, can be used to improve the high spatial frequency performance. The purpose of the present article is to investigate the factors affecting the spatial resolution of SAPHIRE. Since the resolution performance of the SHARP combination has been well studied, the focus of the present work is on the inherent resolution of the FEA readout method. The lateral spread of the electron beam emitted from a 50 microm x 50 microm pixel FEA was investigated with two different electron-optical designs: mesh-electrode-only and electrostatic focusing. Our results showed that electrostatic focusing can limit the lateral spread of electron beams to within the pixel size of down to 50 microm. Since electrostatic focusing is essentially independent of signal intensity, it will provide excellent spatial uniformity.

  9. Bone mineral density assessment using the EOS low-dose X-ray device: a feasibility study.

    Science.gov (United States)

    Sapin, E; Briot, K; Kolta, S; Gravel, P; Skalli, W; Roux, C; Mitton, D

    2008-11-01

    To predict bone strength in the case of osteoporosis, it could be a real benefit to assess the three-dimensional (3D) geometry and the bone mineral density (BMD) with a single low-dose X-ray device, such as the EOS system (Biospace Med, Paris, France). EOS 3D reconstructions of the spine have already been validated. Thus, this study aims at evaluating the accuracy of this low-dose system as a densitometer first ex vivo. The European Spine Phantom (ESP) (number 129) was scanned ten times using both the EOS and a Hologic device (Hologic, Inc., Massachusetts, USA). Accuracy was given by the sum of the systematic error (difference between BMDs assessed and true values given by the phantom manufacturer) and the random error (coefficient of variation). EOS BMDs and Hologic BMDs of 41 ex-vivo vertebrae were calculated and compared. The reproducibility of the method evaluating the EOS BMD was assessed giving the coefficient of variation of three measurements of the 41 vertebrae. The accuracy of the EOS system is below 5.2 per cent, versus 7.2 per cent for the Hologic system in the same conditions. EOS BMDs are significantly higher than Hologic BMDs, but they are strongly correlated. The reproducibility of the method of assessment is equal to 0.95 per cent. The EOS system is accurate for ex-vivo BMD assessments, which is promising regarding the use of this new system to predict vertebral strength.

  10. Proceedings of the workshop on X-ray computed microtomography

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    This report consists of vugraphs from the nine presentations at the conference. Titles of the presentations are: CMT: Applications and Techniques; Computer Microtomography Using X-rays from Third Generation Synchrotron X-ray; Approaches to Soft-X-ray Nanotomography; Diffraction Enhanced Tomography; X-ray Computed Microtomography Applications at the NSLS; XCMT Applications in Forestry and Forest Products; 3DMA: Investigating Three Dimensional Pore Geometry from High Resolution Images; X-ray Computed Microtomography Studies of Volcanic Rock; and 3-D Visualization of Tomographic Volumes.

  11. Effects of X-Ray Dose On Rhizosphere Studies Using X-Ray Computed Tomography.

    Directory of Open Access Journals (Sweden)

    Susan Zappala

    Full Text Available X-ray Computed Tomography (CT is a non-destructive imaging technique originally designed for diagnostic medicine, which was adopted for rhizosphere and soil science applications in the early 1980s. X-ray CT enables researchers to simultaneously visualise and quantify the heterogeneous soil matrix of mineral grains, organic matter, air-filled pores and water-filled pores. Additionally, X-ray CT allows visualisation of plant roots in situ without the need for traditional invasive methods such as root washing. However, one routinely unreported aspect of X-ray CT is the potential effect of X-ray dose on the soil-borne microorganisms and plants in rhizosphere investigations. Here we aimed to i highlight the need for more consistent reporting of X-ray CT parameters for dose to sample, ii to provide an overview of previously reported impacts of X-rays on soil microorganisms and plant roots and iii present new data investigating the response of plant roots and microbial communities to X-ray exposure. Fewer than 5% of the 126 publications included in the literature review contained sufficient information to calculate dose and only 2.4% of the publications explicitly state an estimate of dose received by each sample. We conducted a study involving rice roots growing in soil, observing no significant difference between the numbers of root tips, root volume and total root length in scanned versus unscanned samples. In parallel, a soil microbe experiment scanning samples over a total of 24 weeks observed no significant difference between the scanned and unscanned microbial biomass values. We conclude from the literature review and our own experiments that X-ray CT does not impact plant growth or soil microbial populations when employing a low level of dose (<30 Gy. However, the call for higher throughput X-ray CT means that doses that biological samples receive are likely to increase and thus should be closely monitored.

  12. Adrenergic pathways in dopamine modulation of K+ transport in cortex slices after low dose X-Rays

    Energy Technology Data Exchange (ETDEWEB)

    Kulikova, I.A.; Dvoretsky, A.I. [Laboratoire of Radiobiology et Radioecology, Science Research Institute of Biology, Dnipropetrovsk State University (Ukraine)

    1997-03-01

    Using the method of surviving brain cortex slices it has been shown that prolonged whole body acute or chronic 25 cGy X-irradiation (1 cGy/day at dose rate of 2.22 mGy/min) essentially modified dopamine (DA) modulating influence upon Na, K-pump in nervous tissue. Obtained results pointed to that normally DA had the defined biphasic effect upon active K{sup +} transport with lower level activation (by 24.0 %) and higher level inhibition (by 42.1 %). The patterns of the Na,K-pump reaction to DA was not changed after irradiation, but percentage of the total DA suppression was increased by 15.1 % in average after single X-ray exposure and by 34.5 % after chronic one. The decisive role of {beta}-adrenergic mechanisms in realization of postirradiation interaction between systems of catecholamine and active K{sup +} transfer across neuronal membrane has been determined. Experimental data obtained with the use of 10 {mu}M phentolamine and 10 {mu}M propranolol, respectively {alpha}- and {beta}-adrenergic antagonists, supported that metabolic DA effect was mediated via {alpha}-AR normally, and via {beta}-AR after low dose-rate irradiation. (authors)

  13. Three-dimensional measurements of the lower extremity in children and adolescents using a low-dose biplanar X-ray device

    Energy Technology Data Exchange (ETDEWEB)

    Gheno, Ramon [Centre Hospitalier Regional Universitaire de Lille, Hopital Roger Salengro, Department of Musculoskeletal Radiology, Lille (France); Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre (Brazil); Hopital Roger Salengro, Service de Radiologie Osteo-articulaire, Lille Cedex (France); Nectoux, Eric; Herbaux, Bernard [Centre Hospitalier Regional Universitaire de Lille, Hopital Jeanne de Flandre, Department of Pediatric Surgery and Orthopaedics, Lille (France); Baldisserotto, Matteo [Pontificia Universidade Catolica do Rio Grande do Sul, Department of Radiology, Porto Alegre (Brazil); Glock, Luiz [Pontificia Universidade Catolica do Rio Grande do Sul, Department of Statistics, Porto Alegre (Brazil); Cotten, Anne [Centre Hospitalier Regional Universitaire de Lille, Hopital Roger Salengro, Department of Musculoskeletal Radiology, Lille (France); Boutry, Nathalie [Centre Hospitalier Regional Universitaire de Lille, Hopital Roger Salengro and Jeanne de Flandre, Department of Musculoskeletal and Pediatric Radiology, Lille (France)

    2012-04-15

    To evaluate three-dimensional (3D) measurements of the lower extremity using a biplanar low-dose X-ray device in children and adolescents. Firstly, 3D measurements of eight dried bones were analysed by a biplanar low-dose X-ray device (LDX) using stereoscopic software and compared with 3D computed tomography (CT). Secondly, 47 lower limbs of children and adolescents were studied using LDX two-dimensional (2D) and 3D measurements. Both parts were evaluated for femoral and tibial lengths and mechanical angles, frontal and lateral knee angulations, and the femoral neck-shaft angle. The 3D specimen comparison between LDX and CT measurements showed no significant differences: femoral length (P = 0.069), tibial length (P = 0.059), femoral mechanical angle (P = 0.475), tibial mechanical angle (P = 0.067), frontal knee angulation (P = 0.198), lateral knee angulation (P = 0.646) and femoral neck-shaft angle (P = 0.068). The comparison between LDX 2D and 3D measurements showed significant differences in tibial length (P = 0.003), femoral mechanical angle (P < 0.001) and femoral neck-shaft angle (P = 0.001); other parameters were unremarkable. The 3D LDX system presented reliable measurements compared with 3D CT. Differences between LDX 2D and 3D measurements were noted in the femoral mechanical angle, femoral neck-shaft angle and tibial length. Moderate to good interobserver agreement for the 3D LDX measurements were found. (orig.)

  14. Parental exposure to low-dose X-rays in Drosophila melanogaster induces early emergence in offspring, which can be modulated by transplantation of polar cytoplasm

    Energy Technology Data Exchange (ETDEWEB)

    Kanao, Tomoko; Okamoto, Takehito; Miyachi, Yukihisa; Nohara, Norimasa

    2003-06-19

    In recent years there has been growing concern over the biological effects of low-dose X-rays, but few studies have addressed this issue. Our laboratory had observed flies (Drosophila melanogaster) irradiated with low-dose X-rays tend to emerge earlier than normal flies. This observation led us to quantitatively examine the effects of low-dose X-irradiation on development in the fly. Following exposure of prepupal (day 5) flies to 0.5 Gy X-rays, the time to emergence was slightly shorter than in the sham controls. This tendency was increased when the X-ray exposure came during the pupal stage (day 7). In these flies, the time to eclosion decreased significantly, by an average of 30 h sooner than sham controls. A further experiment examined whether such radiation effects could be observed in the unexposed F1 generation of exposed individuals. Greater radiation effects on early F1 emergence were seen when the time between exposure and mating was 3 days, indicating an effect on early spermatid development. Early F1 emergence was also observed after exposure of female flies to X-rays during late previtellogeny. Furthermore, rapid emergence could be induced in the F1 embryos of unexposed parents by transferring the polar cytoplasm (precursor cells of the germ cell line) from F1 embryos of exposed flies. These results show that radiation-induced effects can be transmitted to the next generation through the germ cell line.

  15. REVIEW: X-ray computed tomography

    Science.gov (United States)

    Kalender, Willi A.

    2006-07-01

    X-ray computed tomography (CT), introduced into clinical practice in 1972, was the first of the modern slice-imaging modalities. To reconstruct images mathematically from measured data and to display and to archive them in digital form was a novelty then and is commonplace today. CT has shown a steady upward trend with respect to technology, performance and clinical use independent of predictions and expert assessments which forecast in the 1980s that it would be completely replaced by magnetic resonance imaging. CT not only survived but exhibited a true renaissance due to the introduction of spiral scanning which meant the transition from slice-by-slice imaging to true volume imaging. Complemented by the introduction of array detector technology in the 1990s, CT today allows imaging of whole organs or the whole body in 5 to 20 s with sub-millimetre isotropic resolution. This review of CT will proceed in chronological order focussing on technology, image quality and clinical applications. In its final part it will also briefly allude to novel uses of CT such as dual-source CT, C-arm flat-panel-detector CT and micro-CT. At present CT possibly exhibits a higher innovation rate than ever before. In consequence the topical and most recent developments will receive the greatest attention.

  16. Cytogenetics dosimetry: dose-response curve for low doses of X-ray; Dosimetria citogenetica: curva dosis-respuesta para bajas dosis de rayos-X

    Energy Technology Data Exchange (ETDEWEB)

    Lara, Virginia E. Noval; Pineda Bolivar, William R.; Riano, Victor M. Pabon, E-mail: venovall.15@hotmail.com, E-mail: wrpineda@misena.edu.co, E-mail: vmpabonr@udistrital.edu.co [Universidad Distrital Francisco Jose de Caldas (UD), Bogota (Colombia). Grupo de Investigacion en Ciencia y Tecnologia Nuclear; Ureana, Cecilia Crane, E-mail: cecicrane@yahoo.com [Instituto Nacional de Salud (INS), Bogota (Colombia). Laboratorio de Genetica

    2013-07-01

    The purpose of this study was to conduct a preliminary study for the standardization in the future, the dose-response curve for low doses of X-rays, through the analysis of in vitro cultures of peripheral blood samples of 3 men and 3 women occupationally not exposed to artificial sources of ionizing radiation, age 18-40 years, where possible nonsmokers.

  17. An indirect flat-panel detector with avalanche gain for low dose x-ray imaging: SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout)

    Science.gov (United States)

    Zhao, Wei; Li, Dan; Rowlands, J. A.; Egami, N.; Takiguchi, Y.; Nanba, M.; Honda, Y.; Ohkawa, Y.; Kubota, M.; Tanioka, K.; Suzuki, K.; Kawai, T.

    2008-03-01

    An indirect flat-imager with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose x-ray imaging with high resolution. It is made by optically coupling a structured x-ray scintillator CsI (Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The charge image created by HARP is read out by electron beams generated by the FEA. The proposed detector is called SAPHIRE (Scintillator Avalanche Photoconductor with HIgh Resolution Emitter readout). The avalanche gain of HARP depends on both a-Se thickness and applied electric field E Se. At E Se of > 80 V/μm, the avalanche gain can enhance the signal at low dose (e.g. fluoroscopy) and make the detector x-ray quantum noise limited down to a single x-ray photon. At high exposure (e.g. radiography), the avalanche gain can be turned off by decreasing E Se to < 70 V/μm. In this paper the imaging characteristics of the FEA readout method, including the spatial resolution and noise, were investigated experimentally using a prototype optical HARP-FEA image sensor. The potential x-ray imaging performance of SAPHIRE, especially the aspect of programmable gain to ensure wide dynamic range and x-ray quantum noise limited performance at the lowest exposure in fluoroscopy, was investigated.

  18. Quantitative cone beam X-ray luminescence tomography/X-ray computed tomography imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dongmei; Zhu, Shouping, E-mail: zhusp2009@gmail.com; Chen, Xueli; Chao, Tiantian; Cao, Xu; Zhao, Fengjun; Huang, Liyu; Liang, Jimin [Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education and School of Life Science and Technology, Xidian University, Xi' an, Shaanxi 710071 (China)

    2014-11-10

    X-ray luminescence tomography (XLT) is an imaging technology based on X-ray-excitable materials. The main purpose of this paper is to obtain quantitative luminescence concentration using the structural information of the X-ray computed tomography (XCT) in the hybrid cone beam XLT/XCT system. A multi-wavelength luminescence cone beam XLT method with the structural a priori information is presented to relieve the severe ill-posedness problem in the cone beam XLT. The nanophosphors and phantom experiments were undertaken to access the linear relationship of the system response. Then, an in vivo mouse experiment was conducted. The in vivo experimental results show that the recovered concentration error as low as 6.67% with the location error of 0.85 mm can be achieved. The results demonstrate that the proposed method can accurately recover the nanophosphor inclusion and realize the quantitative imaging.

  19. The color of X-rays: Spectral X-ray computed tomography using energy sensitive pixel detectors

    NARCIS (Netherlands)

    Schioppa, E.J.

    2014-01-01

    Energy sensitive X-ray imaging detectors are produced by connecting a semiconductor sensor to a spectroscopic pixel readout chip. In this thesis, the applicability of such detectors to X-ray Computed Tomography (CT) is studied. A prototype Medipix based silicon detector is calibrated using X-ray flu

  20. Parental exposure to low-dose X-rays in Drosophila melanogaster induces early emergence offspring, which can be modulated by transplantation of polar cytoplasm

    Energy Technology Data Exchange (ETDEWEB)

    Kanao, T.; Okamoto, T.; Miyachi, Y.

    2004-07-01

    In recent years there has been growing concern over the biological effects of low-dose X-rays, but few studies have addressed this issue. Our laboratory had observed files (Drosophila melanogaster) irradiated with low dose X-rays tend to emerge earlier than normal flies. This observation led us to quantitatively examine the effects of low dose X-irradiation on development in the fly Following exposure of prepupal (day 5) flies to 0.5 Gy X-rays, the time to emergence was slightly shorter than in the sham controls. This tendency was increased when the X-ray exposure came during the pupal stage (day 7). In these flies, the time to eclosion decreased significantly, by an average of thirty hours sooner than sham controls. Exposure of pre pupa to 0.5 Gy results in marked changes in the puffing patterns of salivary gland chromosomes. A 0.5 Gy exposure induces puffing at 75B specific loci; this pattern of induced puffs shows little developmental specificity. A further experiment examined whether such radiation effects could be observed in the unexposed F1 generation of exposed individuals Greater radiation effects on early Fi emergence were seen when the time between exposure and mating was 3 days, indicating an effect on early spermatid development. Early F1 emergence was also observed after exposure of female flies to X-rays during late previtellogeny. furthermore, rapid emergence could be induced in the F1 embryos of unexposed parents by transferring the polar cytoplasm (precursor cells of the germ cell line) from F1 embryos of exposed flies. furthermore pumilio mutant arrested the assembly of polar cytoplasm did not induce the early emergency even after 0.5 Gy exposure. These results show that radiation-induced effects can be transmitted to the next generation through the germ cell line. (Author)

  1. Modeling and characterization of X-ray yield in a polychromatic, lab-scale, X-ray computed tomography system

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, J.C.E.; Chawla, Nikhilesh, E-mail: nchawla@asu.edu

    2015-05-21

    A modular X-ray computed micro-tomography (µXCT) system is characterized in terms of X-ray yield resulting both from the generated X-ray spectrum and from X-ray detection with an energy-sensitive detector. The X-ray computed tomography system is composed of a commercially available cone-beam microfocus X-ray source and a modular optically-coupled-CCD-scintillator X-ray detector. The X-ray yield is measured and reported in units independent from exposure time, X-ray tube beam target current, and cone-beam-to-detector geometry. The polychromatic X-ray source is modeled as a broad Bremsstrahlung X-ray spectrum in order to understand the effect of the controllable parameters, that is, X-ray tube accelerating voltage and X-ray beam filtering. An approach is adopted which expresses the absolute number of emitted X-rays. The response of the energy-sensitive detector to the modeled spectrum is modeled as a function of scintillator composition and thickness. The detection efficiency model for the polychromatic X-ray detector considers the response of the light collection system and the electronic imaging array in order to predict absolute count yield under the studied conditions. The modeling approach is applied to the specific hardware implemented in the current µXCT system. The model's predictions for absolute detection rate are in reasonable agreement with measured values under a range of conditions applied to the system for X-ray microtomography imaging, particularly for the LuAG:Ce scintillator material.

  2. A method for high-energy, low-dose mammography using edge illumination x-ray phase-contrast imaging

    Science.gov (United States)

    Diemoz, Paul C.; Bravin, Alberto; Sztrókay-Gaul, Anikó; Ruat, Marie; Grandl, Susanne; Mayr, Doris; Auweter, Sigrid; Mittone, Alberto; Brun, Emmanuel; Ponchut, Cyril; Reiser, Maximilian F.; Coan, Paola; Olivo, Alessandro

    2016-12-01

    Since the breast is one of the most radiosensitive organs, mammography is arguably the area where lowering radiation dose is of the uttermost importance. Phase-based x-ray imaging methods can provide opportunities in this sense, since they do not require x-rays to be stopped in tissue for image contrast to be generated. Therefore, x-ray energy can be considerably increased compared to those usually exploited by conventional mammography. In this article we show how a novel, optimized approach can lead to considerable dose reductions. This was achieved by matching the edge-illumination phase method, which reaches very high angular sensitivity also at high x-ray energies, to an appropriate image processing algorithm and to a virtually noise-free detection technology capable of reaching almost 100% efficiency at the same energies. Importantly, while proof-of-concept was obtained at a synchrotron, the method has potential for a translation to conventional sources.

  3. Low Dose Studies with Focused X-Rays in cell and Tissue Models: Mechanisms of Bystander and Genomic Instability Responses

    Energy Technology Data Exchange (ETDEWEB)

    Kathy Held; Kevin Prise; Barry Michael; Melvyn Folkard

    2002-12-14

    The management of the risks of exposure of people to ionizing radiation is important in relation to its uses in industry and medicine, also to natural and man-made radiation in the environment. The vase majority of exposures are at a very low level of radiation dose. The risks are of inducing cancer in the exposed individuals and a smaller risk of inducing genetic damage that can be indicate that they are low. As a result, the risks are impossible to detect in population studies with any accuracy above the normal levels of cancer and genetic defects unless the dose levels are high. In practice, this means that our knowledge depends very largely on the information gained from the follow-up of the survivors of the atomic bombs dropped on Japanese cities. The risks calculated from these high-dose short-duration exposures then have to be projected down to the low-dose long-term exposures that apply generally. Recent research using cells in culture has revealed that the relationship between high- and low-dose biological damage may be much more complex than had previously been thought. The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept that the processes by which radiation induces cancer start where the individual tracks of radiation impact on cells and tissues. At the dose levels of most low-dose exposures, these events are rare and any individual cells only ''sees'' radiation tracks at intervals averaging from weeks to years apart. This contrasts with the atomic bomb exposures where, on average, each cell was hit by hundreds of tracks instantaneously. We have therefore developed microbeam techniques that enable us to target cells in culture with any numbers of tracks, from one upwards. This approach enables us to study

  4. Low Dose Studies with Focused X-Rays in cell and Tissue Models: Mechanisms of Bystander and Genomic Instability Responses

    Energy Technology Data Exchange (ETDEWEB)

    Kathy Held; Kevin Prise; Barry Michael; Melvyn Folkard

    2002-12-14

    The management of the risks of exposure of people to ionizing radiation is important in relation to its uses in industry and medicine, also to natural and man-made radiation in the environment. The vase majority of exposures are at a very low level of radiation dose. The risks are of inducing cancer in the exposed individuals and a smaller risk of inducing genetic damage that can be indicate that they are low. As a result, the risks are impossible to detect in population studies with any accuracy above the normal levels of cancer and genetic defects unless the dose levels are high. In practice, this means that our knowledge depends very largely on the information gained from the follow-up of the survivors of the atomic bombs dropped on Japanese cities. The risks calculated from these high-dose short-duration exposures then have to be projected down to the low-dose long-term exposures that apply generally. Recent research using cells in culture has revealed that the relationship between high- and low-dose biological damage may be much more complex than had previously been thought. The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept that the processes by which radiation induces cancer start where the individual tracks of radiation impact on cells and tissues. At the dose levels of most low-dose exposures, these events are rare and any individual cells only ''sees'' radiation tracks at intervals averaging from weeks to years apart. This contrasts with the atomic bomb exposures where, on average, each cell was hit by hundreds of tracks instantaneously. We have therefore developed microbeam techniques that enable us to target cells in culture with any numbers of tracks, from one upwards. This approach enables us to study

  5. The effects of pre-emptive low-dose X-ray irradiation on MIA induced inflammatory pain in rats

    Science.gov (United States)

    Hahm, Suk-Chan; Lee, Go-Eun; Kim, Eun-Hye; Kim, Junesun; Lee, Taewoong; Lee, Wonho

    2013-07-01

    This study was performed to determine the effect of pre-emptive low-dose irradiation on the development of inflammatory pain and to characterize the potential mechanisms underlying this effect in osteoarthritis (OA) animal model. Whole-body X-irradiations with 0.1, 0.5, 1 Gy or sham irradiations were performed for 3 days before the induction of ostearthritis with monosodium iodoacetate (MIA) (40 µl, in saline) into the right knee joint in male Sprague Dawley rats. Behavioral tests for arthritic pain including evoked and non-evoked pain were conducted before and after MIA injection and inducible nitric-oxide synthase (iNOS) expression level was measured by western blot. Low-dose radiation significantly prevented the development of mechanical allodynia and thermal hyperalgesia and reduction in weight bearing that is regarded as a behavioral signs of non-evoked pain following MIA injection. Low-dose radiation significantly inhibited the increase in iNOS expression after MIA injection in spinal L3-5 segments in rat. These data suggest that low-dose X-irradiation is able to prevent the development of arthritic pain through modulation of iNOS expression in the spinal cord dorsal horn. Thus, low-dose radiotherapy could be substituted in part for treatment with drugs for patients with chronic inflammatory disease in clinical setting.

  6. Low Dose Studies with Focused X-rays in Cell and Tissue Models: Mechanisms of Bystander and Genomic Instability Responses

    Energy Technology Data Exchange (ETDEWEB)

    Barry D. Michael; Kathryn Held; Kevin Prise

    2002-12-19

    The management of the risks of exposure of people to ionizing radiation is important in relation to its uses in industry and medicine, also to natural and man-made radiation in the environment. The vase majority of exposures are at a very low level of radiation dose. The risks are of inducing cancer in the exposed individuals and a smaller risk of inducing genetic damage that can be transmitted to children conceived after exposure. Studies of these risks in exposed population studies with any accuracy above the normal levels of cancer and genetic defects unless the dose levels are high. In practice, this means that our knowledge depends very largely on the information gained from the follow-up of the survivors of the atomic bombs dropped on Japanese cities. The risks calculated from these high-dose short-duration exposures then have to be projected down to the low-dose long-term exposures that apply generally. Recent research using cells in culture has revealed that the relations hi between high- and low-dose biological damage may be much more complex than had previously been thought. The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept that the processes by which radiation induces cancer start where the individual tracks of radiation impact on cells and tissues. At the dose levels of most low-dose exposures, these events are rare and any individual cells only ''sees'' radiation tracks at intervals averaging from weeks to years apart. This contracts with the atomic bomb exposures where, on average, each cell was hit by hundreds of tracks instantaneously. We have therefore developed microbeam techniques that enable us to target cells in culture with any number of tracks, from one upwards. This approach enables us to

  7. Increased apoptosis and DNA double-strand breaks in the embryonic mouse brain in response to very low-dose X-rays but not 50 Hz magnetic fields.

    Science.gov (United States)

    Saha, Shreya; Woodbine, Lisa; Haines, Jackie; Coster, Margaret; Ricket, Nicole; Barazzuol, Lara; Ainsbury, Elizabeth; Sienkiewicz, Zenon; Jeggo, Penny

    2014-11-06

    The use of X-rays for medical diagnosis is enhancing exposure to low radiation doses. Exposure to extremely low-frequency electromagnetic or magnetic fields is also increasing. Epidemiological studies show consistent associations of childhood leukaemia with exposure to magnetic fields but any causal relationship is unclear. A limitation in assessing the consequence of such exposure is the availability of sensitive assays. The embryonic neuronal stem and progenitor cell compartments are radiosensitive tissues. Using sensitive assays, we report a statistically significant increase in DNA double-strand break (DSB) formation and apoptosis in the embryonic neuronal stem cell compartment following in utero exposure to 10-200 mGy X-rays. Both endpoints show a linear response. We also show that DSB repair is delayed following exposure to doses below 50 mGy compared with 100 mGy. Thus, we demonstrate in vivo consequences of low-dose radiation. In contrast to these impacts, we did not observe any significant induction of DSBs or apoptosis following exposure to 50 Hz magnetic fields (100 or 300 µT). We conclude that any DSB induction by treatment with magnetic fields is lower than following exposure to 10 mGy X-rays. For comparison, certain procedures involving computed tomography scanning are equivalent to 1-5 mGy X-rays.

  8. Selective brain responses to acute and chronic low-dose X-ray irradiation in males and females.

    Science.gov (United States)

    Silasi, Greg; Diaz-Heijtz, Rochellys; Besplug, Jill; Rodriguez-Juarez, Rocio; Titov, Viktor; Kolb, Bryan; Kovalchuk, Olga

    2004-12-24

    Radiation exposure is known to have profound effects on the brain, leading to precursor cell dysfunction and debilitating cognitive declines [Nat. Med. 8 (2002) 955]. Although a plethora of data exist on the effects of high radiation doses, the effects of low-dose irradiation, such as ones received during repetitive diagnostic and therapeutic exposures, are still under-investigated [Am. J. Otolaryngol. 23 (2002) 215; Proc. Natl. Acad. Sci. USA 97 (2000) 889; Curr. Opin. Neurol. 16 (2003) 129]. Furthermore, most studies of the biological effects of ionizing radiation have been performed using a single acute dose, while clinically and environmentally relevant exposures occur predominantly under chronic/repetitive conditions. Here, we have used a mouse model to compare the effects of chronic/repetitive and acute low-dose radiation (LDR) exposure (0.5Gy) to ionizing radiation on the brain in vivo. We examined the LDR effects on p42/44 MAPK (ERK1/ERK2), CaMKII, and AKT signaling-the interconnected pathways that have been previously shown to be crucial for neuronal survival upon irradiation. We report perturbations in ERK1/2, AKT, and CREB upon acute and chronic/repetitive low-dose exposure in the hippocampus and frontal cortex of mice. These studies were paralleled by the analysis of radiation effects on neurogenesis and cellular proliferation. Repetitive exposure had a much more pronounced effect on cellular signaling and neurogenesis than acute exposure. These results suggest that studies of single acute exposures might be limited in terms of their predictive value. We also present the first evidence of sex differences in radiation-induced signaling in the hippocampus and frontal cortex. We show the role of estrogens in brain radiation responses and discuss the implications of the observed changes.

  9. Low doses of X-rays induce prolonged and ATM-independent persistence of γH2AX foci in human gingival mesenchymal stem cells.

    Science.gov (United States)

    Osipov, Andreyan N; Pustovalova, Margarita; Grekhova, Anna; Eremin, Petr; Vorobyova, Natalia; Pulin, Andrey; Zhavoronkov, Alex; Roumiantsev, Sergey; Klokov, Dmitry Y; Eremin, Ilya

    2015-09-29

    Diagnostic imaging delivering low doses of radiation often accompany human mesenchymal stem cells (MSCs)-based therapies. However, effects of low dose radiation on MSCs are poorly characterized. Here we examine patterns of phosphorylated histone H2AX (γH2AX) and phospho-S1981 ATM (pATM) foci formation in human gingiva-derived MSCs exposed to X-rays in time-course and dose-response experiments. Both γH2AX and pATM foci accumulated linearly with dose early after irradiation (5-60 min), with a maximum induction observed at 30-60 min (37 ± 3 and 32 ± 3 foci/cell/Gy for γH2AX and pATM, respectively). The number of γH2AX foci produced by intermediate doses (160 and 250 mGy) significantly decreased (40-60%) between 60 and 240 min post-irradiation, indicating rejoining of DNA double-strand breaks. In contrast, γH2AX foci produced by low doses (20-80 mGy) did not change after 60 min. The number of pATM foci between 60 and 240 min decreased down to control values in a dose-independent manner. Similar kinetics was observed for pATM foci co-localized with γH2AX foci. Collectively, our results suggest differential DNA double-strand break signaling and processing in response to low vs. intermediate doses of X-rays in human MSCs. Furthermore, mechanisms governing the prolonged persistence of γH2AX foci in these cells appear to be ATM-independent.

  10. EFFECT OF POLYPHENOLIC COMPLEX FROM WINE ON RATS ANTIOXIDANT ENZYMES ACTIVITY AT X-RAY IRRADIATION LOW DOSES

    Directory of Open Access Journals (Sweden)

    U. V. Datsyuk

    2014-04-01

    Full Text Available It is shown that the consumption of natural polyphenolic complex from grape wine in drinking water in the daily dose 2.5 ± 1.1 mg polyphenols/kg body mass of rats during the 10 day before exposure to radiation leads to increased of superoxide dismutase and gluthathione reductase activities in peripheral blood on 24 and 48 hours after full body X-ray irradiation (30 cGy. The of catalase, gluthathione peroxidase activities and the of the reactive thiobarbituric acid substances content in total lysates of peripheral blood within 72 hours after exposure are comparable to those in control rats. Marked decreased of catalase and superoxide dismutase activities at 24, 48 and 24 hours, respectively, was observed after exposure to ionizing radiation and increased content of lipid peroxidation products in all above mentioned time points. The decreased of superoxide dismutase and gluthathione peroxidase activities in lysates of rats aorta at 48 hour and increased content of the reactive thiobarbituric acid substances during 72 hours after radiation exposure were observed. The consumption of polyphenolic complex from wine did not change the superoxide dismutase and catalase activities in lysates of aorta rats treated with ionizing radiation, whereas gluthathione reductase and gluthathione peroxidase activities was increased during 72 hours after radiation influence. The content of TBA reactive substances was significantly decreased in lysates of aorta rats that were exposed to radiation and polyphenols of grape wine, compared with those of animals that were exposed to radiation alone.

  11. Changes in telomere length distribution in low-dose X-ray-irradiated human umbilical vein endothelial cells.

    Science.gov (United States)

    Guan, Jing-Zhi; Guan, Wei Ping; Maeda, Toyoki; Makino, Naoki

    2014-11-01

    Ionizing radiation (IR) is known to be a cause of telomere dysfunction in tumor cells; however, very few studies have investigated X-ray-related changes in telomere length and the telomerase activity in normal human cells, such as umbilical vein endothelial cells (HUVECs). The loss of a few hundred base pairs from a shortened telomere has been shown to be important with respect to cellular senescence, although it may not be detected according to traditional mean telomere length [assessed as the terminal restriction fragment (TRF)] analyses. In the present study, a continuous time window from irradiation was selected to examine changes in the telomere length, including the mean TRF length, percentage of the telomere length, telomerase activity, apoptotic rate, and survival rate in HUVECs from the first day to the fourth day after the administration of a 0.5-Gy dose of irradiation. The mean TRF length in the irradiated HUVECs showed shorter telomere length in first 3 days, but they were not statistically significant. On the other hand, according to the percentage analysis of the telomere length, a decreasing tendency was noted in the longer telomere lengths (9.4-4.4 kb), with a significant increase in the shortest telomeres (4.4-2.3 kb) among the irradiated cells versus the controls from the first day to the third after irradiation; no significant differences were noted on the fourth day. These results suggest that the shortest telomeres are sensitive to the late stage of radiation damage. The proliferation of irradiated cells was suppressed after IR in contrast to the non-irradiated cells. The apoptotic rate was elevated initially both in IR- and non-IR-cells, but that of IR-cells was maintained at an elevated level thereafter in contrast to that of non-IR-cells decreasing promptly. Therefore, a 0.5-Gy dose of IR induces persistent apoptosis leading to an apparent growth arrest of the normal HUVECs.

  12. Radiolytic yield of ozone in air for low dose neutron and x-ray/gamma-ray radiation

    Science.gov (United States)

    Cole, J.; Su, S.; Blakeley, R. E.; Koonath, P.; Hecht, A. A.

    2015-01-01

    Radiation ionizes surrounding air and produces molecular species, and these localized effects may be used as a signature of, and for quantification of, radiation. Low-level ozone production measurements from radioactive sources have been performed in this work to understand radiation chemical yields at low doses. The University of New Mexico AGN-201 M reactor was used as a tunable radiation source. Ozone levels were compared between reactor-on and reactor-off conditions, and differences (0.61 to 0.73 ppb) well below background levels were measured. Simulations were performed to determine the dose rate distribution and average dose rate to the air sample within the reactor, giving 35 mGy of mixed photon and neutron dose. A radiation chemical yield for ozone of 6.5±0.8 molecules/100 eV was found by a variance weighted average of the data. The different contributions of photons and neutrons to radiolytic ozone production are discussed.

  13. Computing Composition/Depth Profiles From X-Ray Diffraction

    Science.gov (United States)

    Wiedemann, K. E.; Unnam, J.

    1986-01-01

    Diffraction-intensity bands deconvolved relatively quickly. TIBAC constructs composition/depth profiles from X-ray diffraction-intensity bands. Intensity band extremely sensitive to shape of composition/depth profile. TIBAC incorporates straightforward transformation of intensity band that retains accuracy of earlier simulation models, but is several orders of magnitude faster in total computational time. TIBAC written in FORTRAN 77 for batch execution.

  14. Soil Macropore Structure Characterized by X-Ray Computed Tomography

    Institute of Scientific and Technical Information of China (English)

    FENG Jie; ZHANG Jia-Bao; ZHU An-Ning; BI Jing-Wei

    2003-01-01

    Undisturbed soil core with many macropores and disturbed soil core with only one macropore (diameter is 10 mm) were probed by x-ray computed tomography (CT). The size, number, shape and continuity of macropores in the transverse and vertical sections of soil were characterized using CT scanning images. The probability densities of macropores in the transverse section of soil core exhibited a logarithmic Γ distribution.Results indicated that CT scanning was a promising nondestructive method for characterizing macropores in soils.

  15. X-ray energy optimisation in computed microtomography.

    Science.gov (United States)

    Spanne, P

    1989-06-01

    Expressions describing the absorbed dose and the number of incident photons necessary for the detection of a contrasting detail in x-ray transmission CT imaging of a circular phantom are derived as functions of the linear attenuation coefficients of the materials comprising the object and the detail. A shell of a different material can be included to allow simulation of CT imaging of the skulls of small laboratory animals. The equations are used to estimate the optimum photon energy in x-ray transmission computed microtomography. The optimum energy depends on whether the number of incident photons or the absorbed dose at a point in the object is minimised. For a water object of 300 mm diameter the two optimisation criteria yield optimum photon energies differing by an order of magnitude.

  16. The color of X-rays Spectral X-ray computed tomography using energy sensitive pixel detectors

    CERN Document Server

    Schioppa, Enrico Junior

    Energy sensitive X-ray imaging detectors are produced by connecting a semiconductor sensor to a spectroscopic pixel readout chip. In this thesis, the applicability of such detectors to X-ray Computed Tomography (CT) is studied. A prototype Medipix based silicon detector is calibrated using X-ray fluorescence. The charge transport properties of the sensor are characterized using a high energy beam of charged particles at the Super Proton Synchrotron (SPS) at the European Center for Nuclear Research (CERN). Monochromatic X-rays at the European Synchrotron Radiation Facility (ESRF) are used to determined the energy response function. These data are used to implement a physics-based CT projection operator that accounts for the transmission of the source spectrum through the sample and detector effects. Based on this projection operator, an iterative spectral CT reconstruction algorithm is developed by extending an Ordered Subset Expectation Maximization (OSEM) method. Subsequently, a maximum likelihood based algo...

  17. Advances in X-ray detectors for clinical and preclinical Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Panetta, Daniele

    2016-02-11

    Computed tomography (CT) is a non-invasive X-ray diagnostic technique that allows reconstructing cross sections of a patient's body, providing detailed information about structure and anatomy of organs and, in some extent, also about their functionality. Since the development of the first CT scanner for clinical use in the ‘70s, several improvements especially in solid-state X-ray detector technology with growing detection efficiency and fast response have led to the current configuration of modern ultra-fast, low dose whole body CT scanners. Such developments brought great advantages in the clinical settings in terms of image quality, dose effectiveness, imaging throughput, but also extending considerably the field of clinical application that were initially foreseen. Parallel to the roadmap of clinical CT technology, dedicated systems for high-resolution preclinical CT (or micro-CT) have seen a considerable growth in the last two decades, taking advantage of the modern technology of high granularity flat-panel X-ray detectors (FPD). This article aims at reviewing the milestones of the evolution of X-ray detector technology that have traced the roadmap of development of CT and micro-CT. An outlook of the current and future trends on energy resolved clinical and preclinical CT with photon counting detectors will be also given. - Highlights: • Evolution of X-ray detectors has marked the roadmap of CT technology development. • Digital flat-panel detectors have lead to the introduction of the CBCT concept. • CBCT systems with resolution below 0.1 mm are widely used in the preclinical field. • Photon-counting spectral imaging is foreseen to dominate the future of CT roadmap.

  18. The effect of pre-low-dose X-ray radiation on tumor inhibition of HepG2 cells in tumor-bearing nude mice

    Institute of Scientific and Technical Information of China (English)

    Weihua Sun; Hongsheng Yu; Qingjun Shang

    2012-01-01

    Objective: The aim of this study was to discuss the effect of pre-low-dose X-ray radiation on P53, Bcl-2 and apoptosis of HepG2 cells in tumor-bearing nude mouse, and further explore the mechanism of low doses radiation. Methods: HepG2 cells were implanted subcutaneously into nude mice. 14 days after the implanting, these mice were divided into 6 groups randomly, S group (sham-irradiation 0 cGy), D1 group (7.5 cGy, dosage rate = 7.5 cGy/min), D2 group, (200 cGy, dosage rate = 100 cGy/min), D1 + 2 h + D2 group, D1 + 6 h + D2 group and D1 + 12 h + D2 group. Tumor-bearing mice in each experimental group were executed at 24 h after the last irradiation. P53 and Bcl-2 were detected by immunohistochem-ical staining, the tumor tissues apoptosis were detected in site (Tunel). Results: Each combined exposure groups (D1 + 2 h + D2 group, D1 + 6 h + D2 group and D1 + 12 h + D2 group) compared with the D2 group, the percentages of positive P53 and Bcl-2 were decreased obviously, and the apoptotic indexs were increased (P< 0.01). Conclusion: Pre-low-dose radiation combined with the conventional radiation can increase the apoptosis of tumor tissues by decreasing the expression of P53 and Bcl-2, it can enhance the anti-tumor effect of conventional radiation, and it can have actual clinical significance on supporting radiotherapy.

  19. Fast X-ray luminescence computed tomography imaging.

    Science.gov (United States)

    Liu, Xin; Liao, Qimei; Wang, Hongkai

    2014-06-01

    X-ray luminescence computed tomography (XLCT) opens new possibilities to perform molecular imaging with X-ray. However, challenges remain in dynamic XLCT imaging, where short scan time, good spatial resolution, and whole-body field of view should be considered simultaneously. In this paper, by the use of a single-view XLCT reconstruction method based on a compressive sensing (CS) technique, incorporating a cone beam XLCT imaging system, we implement fast 3-D XLCT imaging. To evaluate the performance of the method, two types of phantom experiments were performed based on a cone beam XLCT imaging system. In Case 1, one tube filled with the X-ray-excitable nanophosphor (Gd 2O 3 :Eu (3+)) was immerged in different positions in the phantom to evaluate the effect of the source position on single-view XLCT reconstruction accuracy. In Case 2, two tubes filled with Gd 2O 3 :Eu (3+) were immerged in different heights in the phantom to evaluate the whole-body imaging performance of single-view XLCT reconstruction. The experimental results indicated that the tubes used in previous phantom experiments can be resolved from single-view XCLT reconstruction images. The location error is less than 1.2 mm. In addition, since only one view data are needed to implement 3-D XLCT imaging, the acquisition time can be greatly reduced (∼1 frame/s) compared with previous XLCT systems. Hence, the technique is suited for imaging the fast distribution of the X-ray-excitable nanophosphors within a biological object.

  20. A Gaussian Mixture MRF for Model-Based Iterative Reconstruction with Applications to Low-Dose X-ray CT

    CERN Document Server

    Zhang, Ruoqiao; Pal, Debashish; Thibault, Jean-Baptiste; Sauer, Ken D; Bouman, Charles A

    2016-01-01

    Markov random fields (MRFs) have been widely used as prior models in various inverse problems such as tomographic reconstruction. While MRFs provide a simple and often effective way to model the spatial dependencies in images, they suffer from the fact that parameter estimation is difficult. In practice, this means that MRFs typically have very simple structure that cannot completely capture the subtle characteristics of complex images. In this paper, we present a novel Gaussian mixture Markov random field model (GM-MRF) that can be used as a very expressive prior model for inverse problems such as denoising and reconstruction. The GM-MRF forms a global image model by merging together individual Gaussian-mixture models (GMMs) for image patches. In addition, we present a novel analytical framework for computing MAP estimates using the GM-MRF prior model through the construction of surrogate functions that result in a sequence of quadratic optimizations. We also introduce a simple but effective method to adjust...

  1. SU-F-18C-13: Low-Dose X-Ray CT Reconstruction Using a Hybrid First-Order Method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L; Lin, W [Tianjin University, Tianjin (China); Jin, M [University of Texas at Arlington, Arlington, TX (United States)

    2014-06-15

    Purpose: To develop a novel reconstruction method for X-ray CT that can lead to accurate reconstruction at significantly reduced dose levels combining low X-ray incident intensity and few views of projection data. Methods: The noise nature of the projection data at low X-ray incident intensity was modeled and accounted by the weighted least-squares (WLS) criterion. The total variation (TV) penalty was used to mitigate artifacts caused by few views of data. The first order primal-dual (FOPD) algorithm was used to minimize TV in image domain, which avoided the difficulty of the non-smooth objective function. The TV penalized WLS reconstruction was achieved by alternated FOPD TV minimization and projection onto convex sets (POCS) for data fidelity constraints. The proposed FOPD-POCS method was evaluated using the FORBILD jaw phantom and the real cadaver head CT data. Results: The quantitative measures, root mean square error (RMSE) and contrast-to-noise ratio (CNR), demonstrate the superior denoising capability of WLS over LS-based TV iterative reconstruction. The improvement of RMSE (WLS vs. LS) is 15%∼21% and that of CNR is 17%∼72% when the incident counts per ray are ranged from 1×10{sup 5} to 1×10{sup 3}. In addition, the TV regularization can accurately reconstruct images from about 50 views of the jaw phantom. The FOPD-POCS reconstruction reveals more structural details and suffers fewer artifacts in both the phantom and real head images. The FOPD-POCS method also shows fast convergence at low X-ray incident intensity. Conclusion: The new hybrid FOPD-POCS method, based on TV penalized WLS, yields excellent image quality when the incident X-ray intensity is low and the projection views are limited. The reconstruction is computationally efficient since the FOPD minimization of TV is applied only in the image domain. The characteristics of FOPD-POCS can be exploited to significantly reduce radiation dose of X-ray CT without compromising accuracy for diagnosis

  2. X-ray computed tomography investigations of Cucuteni ceramic statuettes

    Directory of Open Access Journals (Sweden)

    Carmen Pavel

    2013-12-01

    Full Text Available Deciphering the internal structure of prehistoric artefacts can provide spectacular insights that might help us understand the people who made them. In order to preserve the integrity of these relics of past civilisations, it is desirable to make such investigations using non-destructive techniques. Recent decades have witnessed a growth in the X-ray computed tomography (CT applications in the study of cultural heritage objects. This paper presents and discusses tomographic investigations of two Cucuteni ceramic statuettes discovered in Romania. The study was made with a CT device specially designed for archaeometric applications.

  3. Advanced Computational Approaches for Characterizing Stochastic Cellular Responses to Low Dose, Low Dose Rate Exposures

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Bobby, R., Ph.D.

    2003-06-27

    OAK - B135 This project final report summarizes modeling research conducted in the U.S. Department of Energy (DOE), Low Dose Radiation Research Program at the Lovelace Respiratory Research Institute from October 1998 through June 2003. The modeling research described involves critically evaluating the validity of the linear nonthreshold (LNT) risk model as it relates to stochastic effects induced in cells by low doses of ionizing radiation and genotoxic chemicals. The LNT model plays a central role in low-dose risk assessment for humans. With the LNT model, any radiation (or genotoxic chemical) exposure is assumed to increase one¡¯s risk of cancer. Based on the LNT model, others have predicted tens of thousands of cancer deaths related to environmental exposure to radioactive material from nuclear accidents (e.g., Chernobyl) and fallout from nuclear weapons testing. Our research has focused on developing biologically based models that explain the shape of dose-response curves for low-dose radiation and genotoxic chemical-induced stochastic effects in cells. Understanding the shape of the dose-response curve for radiation and genotoxic chemical-induced stochastic effects in cells helps to better understand the shape of the dose-response curve for cancer induction in humans. We have used a modeling approach that facilitated model revisions over time, allowing for timely incorporation of new knowledge gained related to the biological basis for low-dose-induced stochastic effects in cells. Both deleterious (e.g., genomic instability, mutations, and neoplastic transformation) and protective (e.g., DNA repair and apoptosis) effects have been included in our modeling. Our most advanced model, NEOTRANS2, involves differing levels of genomic instability. Persistent genomic instability is presumed to be associated with nonspecific, nonlethal mutations and to increase both the risk for neoplastic transformation and for cancer occurrence. Our research results, based on

  4. Advanced Computational Approaches for Characterizing Stochastic Cellular Responses to Low Dose, Low Dose Rate Exposures

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Bobby, R., Ph.D.

    2003-06-27

    OAK - B135 This project final report summarizes modeling research conducted in the U.S. Department of Energy (DOE), Low Dose Radiation Research Program at the Lovelace Respiratory Research Institute from October 1998 through June 2003. The modeling research described involves critically evaluating the validity of the linear nonthreshold (LNT) risk model as it relates to stochastic effects induced in cells by low doses of ionizing radiation and genotoxic chemicals. The LNT model plays a central role in low-dose risk assessment for humans. With the LNT model, any radiation (or genotoxic chemical) exposure is assumed to increase one¡¯s risk of cancer. Based on the LNT model, others have predicted tens of thousands of cancer deaths related to environmental exposure to radioactive material from nuclear accidents (e.g., Chernobyl) and fallout from nuclear weapons testing. Our research has focused on developing biologically based models that explain the shape of dose-response curves for low-dose radiation and genotoxic chemical-induced stochastic effects in cells. Understanding the shape of the dose-response curve for radiation and genotoxic chemical-induced stochastic effects in cells helps to better understand the shape of the dose-response curve for cancer induction in humans. We have used a modeling approach that facilitated model revisions over time, allowing for timely incorporation of new knowledge gained related to the biological basis for low-dose-induced stochastic effects in cells. Both deleterious (e.g., genomic instability, mutations, and neoplastic transformation) and protective (e.g., DNA repair and apoptosis) effects have been included in our modeling. Our most advanced model, NEOTRANS2, involves differing levels of genomic instability. Persistent genomic instability is presumed to be associated with nonspecific, nonlethal mutations and to increase both the risk for neoplastic transformation and for cancer occurrence. Our research results, based on

  5. Denoising Message Passing for X-ray Computed Tomography Reconstruction

    CERN Document Server

    Perelli, Alessandro; Can, Ali; Davies, Mike E

    2016-01-01

    X-ray Computed Tomography (CT) reconstruction from sparse number of views is becoming a powerful way to reduce either the radiation dose or the acquisition time in CT systems but still requires a huge computational time. This paper introduces an approximate Bayesian inference framework for CT reconstruction based on a family of denoising approximate message passing (DCT-AMP) algorithms able to improve both the convergence speed and the reconstruction quality. Approximate Message Passing for Compressed Sensing has been extensively analysed for random linear measurements but there are still not clear solutions on how AMP should be modified and how it performs with real world problems. In particular to overcome the convergence issues of DCT-AMP with structured measurement matrices, we propose a disjoint preconditioned version of the algorithm tailored for both the geometric system model and the noise model. In addition the Bayesian DCT-AMP formulation allows to measure how the current estimate is close to the pr...

  6. Low-dose computed tomography to diagnose fetal bone dysplasias.

    Science.gov (United States)

    Montoya Filardi, A; Guasp Vizcaíno, M; Gómez Fernández-Montes, J; Llorens Salvador, R

    We present a case of cleidocranial dysplasia diagnosed by low-dose fetal computed tomography (CT) in the 25th week of gestation. Severe bone dysplasia was suspected because of the fetus' low percentile in long bones length and the appearance of craniosynostosis on sonography. CT found no abnormalities incompatible with life. The effective dose was 5 mSv, within the recommended range for this type of examination. Low-dose fetal CT is a new technique that makes precision study of the bony structures possible from the second trimester of pregnancy. In Spain, abortion is legal even after the 22nd week of gestation in cases of severe fetal malformations. Therefore, in cases in which severe bone dysplasia is suspected, radiologists must know the strategies for reducing the dose of radiation while maintaining sufficient diagnostic quality, and they must also know which bony structures to evaluate. Copyright © 2016 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Geoscience Applications of Synchrotron X-ray Computed Microtomography

    Science.gov (United States)

    Rivers, M. L.

    2009-05-01

    Computed microtomography is the extension to micron spatial resolution of the CAT scanning technique developed for medical imaging. Synchrotron sources are ideal for the method, since they provide a monochromatic, parallel beam with high intensity. High energy storage rings such as the Advanced Photon Source at Argonne National Laboratory produce x-rays with high energy, high brilliance, and high coherence. All of these factors combine to produce an extremely powerful imaging tool for earth science research. Techniques that have been developed include: - Absorption and phase contrast computed tomography with spatial resolution approaching one micron - Differential contrast computed tomography, imaging above and below the absorption edge of a particular element - High-pressure tomography, imaging inside a pressure cell at pressures above 10GPa - High speed radiography, with 100 microsecond temporal resolution - Fluorescence tomography, imaging the 3-D distribution of elements present at ppm concentrations. - Radiographic strain measurements during deformation at high confining pressure, combined with precise x- ray diffraction measurements to determine stress. These techniques have been applied to important problems in earth and environmental sciences, including: - The 3-D distribution of aqueous and organic liquids in porous media, with applications in contaminated groundwater and petroleum recovery. - The kinetics of bubble formation in magma chambers, which control explosive volcanism. - Accurate crystal size distributions in volcanic systems, important for understanding the evolution of magma chambers. - The equation-of-state of amorphous materials at high pressure using both direct measurements of volume as a function of pressure and also by measuring the change x-ray absorption coefficient as a function of pressure. - The formation of frost flowers on Arctic sea-ice, which is important in controlling the atmospheric chemistry of mercury. - The distribution of

  8. Novel photon-counting low-dose computed tomography using a multi-pixel photon counter

    Science.gov (United States)

    Morita, H.; Oshima, T.; Kataoka, J.; Arimoto, M.; Nitta, H.

    2017-06-01

    X-ray computed tomography (CT) is widely used in diagnostic imaging. Owing to a strong radiation exposure associated with this method, numerous proposals have been made for reducing the radiation dose. In addition, conventional CT does not provide information on the energy associated with each X-ray photon because intensity is rather high, typically amounts to 10 7 - 9 cps /mm2 . Here, we propose a novel, low-dose photon-counting CT system based on a multi-pixel photon counter (MPPC) and a high-speed scintillator. To demonstrate high signal-to-noise ratio utilizing the internal gain and the fast time response of the MPPC, we compared CT images acquired under the same conditions among a photodiode (PD), an avalanche photodiode and a MPPC. In particular, the images' contrast-to-noise ratio (CNR) acquired using the MPPC improved 12.6-fold compared with the images acquired in conventional CT using a PD. We also performed energy-resolved imaging by adopting 4 energy thresholds of 20, 40, 60, and 80 keV. We confirmed a substantial improvement of the imaging contrast as well as a reduction in the beam hardening for the CT images. We conclude that the proposed MPPC-based detector is likely to be a promising device for use in future CT scanners.

  9. ADVANCES IN X-RAY COMPUTED MICROTOMOGRAPHY AT THE NSLS.

    Energy Technology Data Exchange (ETDEWEB)

    DOWD,B.A.

    1998-08-07

    The X-Ray Computed Microtomography workstation at beamline X27A at the NSLS has been utilized by scientists from a broad range of disciplines from industrial materials processing to environmental science. The most recent applications are presented here as well as a description of the facility that has evolved to accommodate a wide variety of materials and sample sizes. One of the most exciting new developments reported here resulted from a pursuit of faster reconstruction techniques. A Fast Filtered Back Transform (FFBT) reconstruction program has been developed and implemented, that is based on a refinement of the ''gridding'' algorithm first developed for use with radio astronomical data. This program has reduced the reconstruction time to 8.5 sec for a 929 x 929 pixel{sup 2} slice on an R10,000 CPU, more than 8x reduction compared with the Filtered Back-Projection method.

  10. Advances in x-ray computed microtomography at the NSLS

    Energy Technology Data Exchange (ETDEWEB)

    Dowd, B.A.; Andrews, A.B.; Marr, R.B.; Siddons, D.P.; Jones, K.W.; Peskin, A.M.

    1998-08-01

    The X-Ray Computed Microtomography workstation at beamline X27A at the NSLS has been utilized by scientists from a broad range of disciplines from industrial materials processing to environmental science. The most recent applications are presented here as well as a description of the facility that has evolved to accommodate a wide variety of materials and sample sizes. One of the most exciting new developments reported here resulted from a pursuit of faster reconstruction techniques. A Fast Filtered Back Transform (FFBT) reconstruction program has been developed and implemented, that is based on a refinement of the gridding algorithm first developed for use with radio astronomical data. This program has reduced the reconstruction time to 8.5 sec for a 929 x 929 pixel{sup 2} slice on an R10,000 CPU, more than 8x reduction compared with the Filtered Back-Projection method.

  11. X-ray computed tomography of PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Pfrang, Andreas; Veyret, Damien; Tsotridis, Georgios [Commission of the European Communities, Petten (Netherlands). Joint Reseach Centre, Inst. for Energy; Janssen, Gaby [Energy Research Centre of the Netherlands ECN, Petten (Netherlands). Dept. of Hydrogen and Clean Fossil Fuels

    2010-07-01

    Proton exchange membrane (PEM) fuel cells were investigated by 3D x-ray computed tomography at a voxel size of 0.7 {mu}m. It is shown that this lab-based technique is not only suitable for the investigation of gas diffusion layers (GDL) as well as the investigation of membrane electrode assemblies (MEA), but also allows the calculation of macroscopic physical properties. The resolution of computed tomography is clearly sufficient to image the carbon fiber structure of gas diffusion layers in the as received GDLs as well as GDLs integrated into membrane electrode assemblies. It is also possible to visualize the catalyst layer within the MEA, which allows the investigation of layer thickness and structural defects on a larger scale than with conventional techniques. The macroscopic effective thermal conductivities of the gas diffusion layers were computed based on the 3D GDL structure reconstructed from tomography data to produce more reliable input data for fuel cell modeling. The computation was carried out by solving the energy equation considering a pure thermal conduction problem. The computations show - in agreement with the expectation and experimental data - that the through-plane thermal conductivities are lower than the in-plane thermal conductivities. (orig.)

  12. Measuring physiological and pathological femoral anteversion using a biplanar low-dose X-ray system: validity, reliability, and discriminative ability in cerebral palsy

    Energy Technology Data Exchange (ETDEWEB)

    Thepaut, Matthias [Laboratoire de Traitement de l' Information Medicale, INSERM U1101, Brest (France); CHRU de Brest, Hopital Morvan, Service de chirurgie pediatrique, Brest (France); Brochard, Sylvain [Laboratoire de Traitement de l' Information Medicale, INSERM U1101, Brest (France); CHRU de Brest, Hopital Morvan, Service de Medecine Physique et de Readaptation, Brest (France); Universite de Bretagne Occidentale, Brest (France); Leboucher, Julien [Laboratoire de Traitement de l' Information Medicale, INSERM U1101, Brest (France); Lempereur, Mathieu [Laboratoire de Traitement de l' Information Medicale, INSERM U1101, Brest (France); CHRU de Brest, Hopital Morvan, Service de Medecine Physique et de Readaptation, Brest (France); Stindel, Eric [Laboratoire de Traitement de l' Information Medicale, INSERM U1101, Brest (France); CHRU de Brest, La Cavale Blanche, Service d' Orthopedie-Traumatologie, Brest (France); Universite de Bretagne Occidentale, Brest (France); Tissot, Valentin [CHRU de Brest, Service de radiologie, Brest (France); Borotikar, Bhushan S. [Laboratoire de Traitement de l' Information Medicale, INSERM U1101, Brest (France); Institut Mines-Telecom, Telecom Bretagne, Brest (France)

    2016-02-15

    The aims of this study were to evaluate the concurrent validity and reliability of a low-dose biplanar X-ray system (Ld-BPR) for the measurement of femoral anteversion (FA) by comparing Ld-BPR-based three-dimensional measures with CT-scan-based measures and to assess the discriminative ability of this method in children with cerebral palsy. Fifty dry femora were scanned using both a CT scan and the Ld-BPR system. Ten femora were artificially modified to mimic a range of anteversion from -30 to +60 and scanned by both modalities. FA was quantified using the images from both modalities and statistically compared for concurrent validity. Intra- and inter-observer reliability of the Ld-BPR system was also determined. Further, Ld-BPR data from 16 hemiplegic and 22 diplegic children were analyzed for its discriminative ability. The concurrent validity between the Ld-BPR and CT-scan measures was excellent (R {sup 2} = 0.83-0.84) and no significant differences were found. The intra- and inter-trial reliability were excellent (ICCs = 0.98 and 0.97) with limits of agreement of (-2.28 ; +2.65 ) and (-2.76 ; +3.38 ) respectively. Further, no significant effects of angle or method were found in the sample of modified femora. Ld-BPR measures for FA were significantly different between healthy and impaired femora. The excellent concurrent validity with the CT scan modality, the excellent reliability, and the ability to discriminate pathological conditions evaluated by this study make this radiological method suitable for a validated use across hospitals and research institutes. (orig.)

  13. Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Tobias J.; Pfirrmann, Christian W.A.; Pankalla, Katja; Buck, Florian M. [Orthopedic University Hospital Balgrist, Department of Radiology, Zurich (Switzerland); University of Zurich, Zurich (Switzerland); Schwab, Alexander [University of Zurich, Zurich (Switzerland); Orthopedic University Hospital Balgrist, Department of Finances, Zurich (Switzerland)

    2013-07-15

    To compare the radiation dose, workflow, patient comfort, and financial break-even of a standard digital radiography and a biplanar low-dose X-ray system. A standard digital radiography system (Ysio, Siemens Healthcare, Erlangen, Germany) was compared with a biplanar X-ray unit (EOS, EOS imaging, Paris, France) consisting of two X-ray tubes and slot-scanning detectors, arranged at an angle of 90 allowing simultaneous vertical biplanar linear scanning in the upright patient position. We compared data of standing full-length lower limb radiographs and whole spine radiographs of both X-ray systems. Dose-area product was significantly lower for radiographs of the biplanar X-ray system than for the standard digital radiography system (e.g. whole spine radiographs; standard digital radiography system: 392.2 {+-} 231.7 cGy*cm{sup 2} versus biplanar X-ray system: 158.4 {+-} 103.8 cGy*cm{sup 2}). The mean examination time was significantly shorter for biplanar radiographs compared with standard digital radiographs (e.g. whole spine radiographs: 449 s vs 248 s). Patients' comfort regarding noise was significantly higher for the standard digital radiography system. The financial break-even point was 2,602 radiographs/year for the standard digital radiography system compared with 4,077 radiographs/year for the biplanar X-ray unit. The biplanar X-ray unit reduces radiation exposure and increases subjective noise exposure to patients. The biplanar X-ray unit demands a higher number of examinations per year for the financial break-even point, despite the lower labour cost per examination due to the shorter examination time. (orig.)

  14. A computer code to simulate X-ray imaging techniques

    Energy Technology Data Exchange (ETDEWEB)

    Duvauchelle, Philippe E-mail: philippe.duvauchelle@insa-lyon.fr; Freud, Nicolas; Kaftandjian, Valerie; Babot, Daniel

    2000-09-01

    A computer code was developed to simulate the operation of radiographic, radioscopic or tomographic devices. The simulation is based on ray-tracing techniques and on the X-ray attenuation law. The use of computer-aided drawing (CAD) models enables simulations to be carried out with complex three-dimensional (3D) objects and the geometry of every component of the imaging chain, from the source to the detector, can be defined. Geometric unsharpness, for example, can be easily taken into account, even in complex configurations. Automatic translations or rotations of the object can be performed to simulate radioscopic or tomographic image acquisition. Simulations can be carried out with monochromatic or polychromatic beam spectra. This feature enables, for example, the beam hardening phenomenon to be dealt with or dual energy imaging techniques to be studied. The simulation principle is completely deterministic and consequently the computed images present no photon noise. Nevertheless, the variance of the signal associated with each pixel of the detector can be determined, which enables contrast-to-noise ratio (CNR) maps to be computed, in order to predict quantitatively the detectability of defects in the inspected object. The CNR is a relevant indicator for optimizing the experimental parameters. This paper provides several examples of simulated images that illustrate some of the rich possibilities offered by our software. Depending on the simulation type, the computation time order of magnitude can vary from 0.1 s (simple radiographic projection) up to several hours (3D tomography) on a PC, with a 400 MHz microprocessor. Our simulation tool proves to be useful in developing new specific applications, in choosing the most suitable components when designing a new testing chain, and in saving time by reducing the number of experimental tests.

  15. Centre of Rotation Determination Using Projection Data in X-ray Micro Computed Tomography

    OpenAIRE

    Olander, Birger

    1994-01-01

    There are several methods available to determine the Centre Of Rotation, COR, and align detectors and X-ray focus to COR in X-ray computed tomography. Some methods use narrow rods/needles or specially made alignment objects or phantoms. In X-ray Micro Computed Tomography (or Computerized Micro Tomography), μCT (CMT), methods using sample projection data for COR measurements are preferred since the replacement of alignment objects with samples often displace translation stages and make the ali...

  16. Conceptual challenges and computational progress in X-ray simulation

    CERN Document Server

    Pia, Maria Grazia; Begalli, Marcia; Kim, Chan-Hyeung; Quintieri, Lina; Saracco, Paolo; Seo, Hee; Sudhakar, Manju; Weidenspointner, Georg; Zoglauer, Andreas

    2010-01-01

    Recent developments and validation tests related to the simulation of X-ray fluorescence and PIXE with Geant4 are reviewed. They concern new models for PIXE, which has enabled the first Geant4-based simulation of PIXE in a concrete experimental application, and the experimental validation of the content of the EADL data library relevant to the simulation of X-ray fluorescence. Achievements and open issues in this domain are discussed.

  17. X-ray computed tomography for additive manufacturing: a review

    Science.gov (United States)

    Thompson, A.; Maskery, I.; Leach, R. K.

    2016-07-01

    In this review, the use of x-ray computed tomography (XCT) is examined, identifying the requirement for volumetric dimensional measurements in industrial verification of additively manufactured (AM) parts. The XCT technology and AM processes are summarised, and their historical use is documented. The use of XCT and AM as tools for medical reverse engineering is discussed, and the transition of XCT from a tool used solely for imaging to a vital metrological instrument is documented. The current states of the combined technologies are then examined in detail, separated into porosity measurements and general dimensional measurements. In the conclusions of this review, the limitation of resolution on improvement of porosity measurements and the lack of research regarding the measurement of surface texture are identified as the primary barriers to ongoing adoption of XCT in AM. The limitations of both AM and XCT regarding slow speeds and high costs, when compared to other manufacturing and measurement techniques, are also noted as general barriers to continued adoption of XCT and AM.

  18. Arbutin: Isolation, X-ray structure and computional studies

    Science.gov (United States)

    Nycz, Jacek E.; Malecki, Grzegorz; Morag, Monika; Nowak, Gerard; Ponikiewski, Lukasz; Kusz, Joachim; Switlicka, Anna

    2010-09-01

    Arbutin, an active component originated from Serratula quinquefolia for skin-whitening use and treating skin related allergic inflammation, was characterized by microanalysis, FTIR, UV-Vis, multinuclear NMR spectroscopy, and single crystal X-ray diffraction method. The geometries of the studied compound were optimized in singlet states using the density functional theory (DFT) method with B3LYP functional. Electronic spectra were calculated by TDDFT method. In general, the predicted bond lengths and angles are in a good agreement with the values based on the X-ray crystal structure data.

  19. Low dose computed tomography of the chest : Applications and limitations

    NARCIS (Netherlands)

    Gietema, H.A.

    2007-01-01

    In areas with a high intrinsic contrast such as the chest, radiation dose can be reduced for specific indications. Low dose chest CT is feasible and cannot only be applied for lung cancer screening, but also in daily routine and for early detection of lung destruction. We showed in a small sample of

  20. Miniature, mobile X-ray computed radiography system

    Energy Technology Data Exchange (ETDEWEB)

    Watson, Scott A; Rose, Evan A

    2017-03-07

    A miniature, portable x-ray system may be configured to scan images stored on a phosphor. A flash circuit may be configured to project red light onto a phosphor and receive blue light from the phosphor. A digital monochrome camera may be configured to receive the blue light to capture an article near the phosphor.

  1. Computer Simulation and X-ray Diffraction of Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    X-ray diffraction of structure in nanocrystalline α-Fe and Cu was studied by atomistic simulation. Atomic position equilibrium was reached by using molecular dynamics method to simulate nanocrystalline structure with Finnis potentials to model interatomic interactions. lt was found that the boundary component exhibits short-range order, and the distortion in crystalline component increases with the decrease of grain size.

  2. Fast and low-dose computed laminography using compressive sensing based technique

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Sajid, E-mail: scho@kaist.ac.kr; Park, Miran, E-mail: scho@kaist.ac.kr; Cho, Seungryong, E-mail: scho@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of)

    2015-03-31

    Computed laminography (CL) is well known for inspecting microstructures in the materials, weldments and soldering defects in high density packed components or multilayer printed circuit boards. The overload problem on x-ray tube and gross failure of the radio-sensitive electronics devices during a scan are among important issues in CL which needs to be addressed. The sparse-view CL can be one of the viable option to overcome such issues. In this work a numerical aluminum welding phantom was simulated to collect sparsely sampled projection data at only 40 views using a conventional CL scanning scheme i.e. oblique scan. A compressive-sensing inspired total-variation (TV) minimization algorithm was utilized to reconstruct the images. It is found that the images reconstructed using sparse view data are visually comparable with the images reconstructed using full scan data set i.e. at 360 views on regular interval. We have quantitatively confirmed that tiny structures such as copper and tungsten slags, and copper flakes in the reconstructed images from sparsely sampled data are comparable with the corresponding structure present in the fully sampled data case. A blurring effect can be seen near the edges of few pores at the bottom of the reconstructed images from sparsely sampled data, despite the overall image quality is reasonable for fast and low-dose NDT.

  3. BraX-Ray: an X-ray of the Brazilian computer science graduate programs.

    Directory of Open Access Journals (Sweden)

    Luciano A Digiampietri

    Full Text Available Research productivity assessment is increasingly relevant for allocation of research funds. On one hand, this assessment is challenging because it involves both qualitative and quantitative analysis of several characteristics, most of them subjective in nature. On the other hand, current tools and academic social networks make bibliometric data web-available to everyone for free. Those tools, especially when combined with other data, are able to create a rich environment from which information on research productivity can be extracted. In this context, our work aims at characterizing the Brazilian Computer Science graduate programs and the relationship among themselves. We (i present views of the programs from different perspectives, (ii rank the programs according to each perspective and a combination of them, (iii show correlation between assessment metrics, (iv discuss how programs relate to another, and (v infer aspects that boost programs' research productivity. The results indicate that programs with a higher insertion in the coauthorship network topology also possess a higher research productivity between 2004 and 2009.

  4. BraX-Ray: an X-ray of the Brazilian computer science graduate programs.

    Science.gov (United States)

    Digiampietri, Luciano A; Mena-Chalco, Jesús P; Vaz de Melo, Pedro O S; Malheiro, Ana P R; Meira, Dânia N O; Franco, Laryssa F; Oliveira, Leonardo B

    2014-01-01

    Research productivity assessment is increasingly relevant for allocation of research funds. On one hand, this assessment is challenging because it involves both qualitative and quantitative analysis of several characteristics, most of them subjective in nature. On the other hand, current tools and academic social networks make bibliometric data web-available to everyone for free. Those tools, especially when combined with other data, are able to create a rich environment from which information on research productivity can be extracted. In this context, our work aims at characterizing the Brazilian Computer Science graduate programs and the relationship among themselves. We (i) present views of the programs from different perspectives, (ii) rank the programs according to each perspective and a combination of them, (iii) show correlation between assessment metrics, (iv) discuss how programs relate to another, and (v) infer aspects that boost programs' research productivity. The results indicate that programs with a higher insertion in the coauthorship network topology also possess a higher research productivity between 2004 and 2009.

  5. X-ray luminescence computed tomography via selective excitation: a feasibility study.

    Science.gov (United States)

    Pratx, Guillem; Carpenter, Colin M; Sun, Conroy; Xing, Lei

    2010-12-01

    X-ray luminescence computed tomography (XLCT) is proposed as a new molecular imaging modality based on the selective excitation and optical detection of X-ray-excitable phosphor nanoparticles. These nano-sized particles can be fabricated to emit near-infrared (NIR) light when excited with X-rays, and, because because both X-rays and NIR photons propagate long distances in tissue, they are particularly well suited for in vivo biomedical imaging. In XLCT, tomographic images are generated by irradiating the subject using a sequence of programmed X-ray beams, while sensitive photo-detectors measure the light diffusing out of the subject. By restricting the X-ray excitation to a single, narrow beam of radiation, the origin of the optical photons can be inferred regardless of where these photons were detected, and how many times they scattered in tissue. This study presents computer simulations exploring the feasibility of imaging small objects with XLCT, such as research animals. The accumulation of 50 nm phosphor nanoparticles in a 2-mm-diameter target can be detected and quantified with subpicomolar sensitivity using less than 1 cGy of radiation dose. Provided sufficient signal-to-noise ratio, the spatial resolution of the system can be made as high as needed by narrowing the beam aperture. In particular, 1 mm spatial resolution was achieved for a 1-mm-wide X-ray beam. By including an X-ray detector in the system, anatomical imaging is performed simultaneously with molecular imaging via standard X-ray computed tomography (CT). The molecular and anatomical images are spatially and temporally co-registered, and, if a single-pixel X-ray detector is used, they have matching spatial resolution.

  6. SU-D-204-06: Dose and Image Quality Evaluation of a Low-Dose Slot-Scanning X-Ray System for Pediatric Orthopedic Studies

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z; Hoerner, M; Lamoureux, R; Rill, L; Arreola, M [Univ Florida, Jacksonville Beach, FL (United States)

    2015-06-15

    Purpose: Children in early teens with scoliosis require repeated radiographic exams over a number of years. The EOS (EOS imaging S.A., Paris, France) is a novel low-dose slot-scanning digital radiographic system designed to produce full-spine images of a free-standing patient. The radiation dose and image quality characteristics of the EOS were evaluated relative to those of a Computed Radiography (CR) system for scoliosis imaging. Methods: For dose evaluation, a full-torso anthropomorphic phantom was scanned five times using the default standard clinical protocols for both the EOS and a CR system, which include both posteroanterior and lateral full-spine views. Optically stimulated luminescent dosimeters (OSLDs), also known as nanoDots™ (Landauer, Inc., Glenwood, IL), were placed on the phantom’s surface to measure entrance skin dose. To assess image quality, MTF curves were generated from sampling the noise levels within the high-contrast regions of a line-pair phantom. Vertical and horizontal distortions were measured for the square line-pair phantom with the EOS system to evaluate the effects of geometric magnification and misalignment with the indicated imaging plane. Results: The entrance skin dose was measured to be 0.4 to 1.1 mGy for the EOS, and 0.7 to 3.6 mGy for the CR study. MTF comparison shows that CR greatly outperforms the EOS, despite both systems having a limiting resolution at 1.8 line-pairs per mm. Vertical distortion was unaffected by phantom positioning, because of the EOS slot-scanning geometry. Horizontal distortion increased linearly with miscentering distance. Conclusion: The EOS system resulted in approximately 70% lower radiation dose than CR for full-spine images. Image quality was found to be inferior to CR. Further investigation is required to see if EOS system is an acceptable modality for performing clinically diagnostic scoliosis examinations.

  7. Features of dual-energy X-ray computed tomography

    Science.gov (United States)

    Torikoshi, M.; Tsunoo, T.; Ohno, Y.; Endo, M.; Natsuhori, M.; Kakizaki, T.; Ito, N.; Uesugi, K.; Yagi, N.

    2005-08-01

    We proposed dual-energy X-ray CT for direct measurement of electron densities to make treatment planning for heavy ion radiotherapy more accurate. The accuracy was proved to be about 1% using synchrotron radiation in previous experiments carried out at SPring-8 and PF-AR. The electron densities of some porcine organs were measured in this method at SPring-8, and compared with data of ICRU Report. Besides, the atomic number of the object is also obtained as a byproduct. Comparing the CT-number given in conventional CT scanning is an important information. Images of the electron density and atomic number may give new information to medical diagnosis.

  8. Deterministic Computer-Controlled Polishing Process for High-Energy X-Ray Optics

    Science.gov (United States)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    A deterministic computer-controlled polishing process for large X-ray mirror mandrels is presented. Using tool s influence function and material removal rate extracted from polishing experiments, design considerations of polishing laps and optimized operating parameters are discussed

  9. X-Ray Micro-Computed Tomography Imaging of the Buzzard Coulee Chondrite

    Science.gov (United States)

    Melanson, D.; Samson, C.; Herd, R. K.; Fry, C.; McCausland, P. J. A.; Umoh, J.; Holdsworth, D. W.

    2012-03-01

    This abstract outlines research and some results of X-ray micro-computed tomography imaging of the Buzzard Coulee H4 chondrite. A comparison of bulk density results and an analysis of radio-density profile curves are discussed.

  10. Model-based image reconstruction in X-ray computed tomography

    NARCIS (Netherlands)

    Zbijewski, Wojciech Bartosz

    2006-01-01

    The thesis investigates the applications of iterative, statistical reconstruction (SR) algorithms in X-ray Computed Tomography. Emphasis is put on various aspects of system modeling in statistical reconstruction. Fundamental issues such as effects of object discretization and algorithm initializatio

  11. X-ray computed tomography for virtually unrolling damaged papyri

    Energy Technology Data Exchange (ETDEWEB)

    Allegra, Dario; Ciliberto, Paolo; Stanco, Filippo [Universita degli Studi di Catania, Dipartimento di Matematica ed Informatica, Catania (Italy); Ciliberto, Enrico [Universita degli Studi di Catania, Dipartimento di Scienze Chimiche, Catania (Italy); Petrillo, Giuseppe; Trombatore, Claudia [Universita degli Studi di Catania, Dipartimento di Scienze Mediche Chirurgiche e Tecnologie Avanzate, Catania (Italy)

    2016-03-15

    The regular format for ancient works of literature was the papyrus roll. Recently many efforts to perform virtual restoration of this archeological artifact have been done. In fact the case of ancient rolled papyrus is very intriguing. Old papyruses are the substrates of very important historical information, probably being the use of papyrus dated to the Pre-Dynastic Period. Papyrus degradation is often very hard so that physical unrolling is sometime absolutely impossible. In this paper, authors describe their effort in setting a new virtual restoration methodology based on software manipulation of X-ray tomographic images. A realistic model, obtained by painting a hieroglyph inscription of Thutmosis III on a papyrus substrate made by the original method described by Plinius the Elder and by pigments and binders compatible with the Egyptian use (ochers with natural glue), was made for the X-ray investigation. A GE Optima 660 64 slice was used to obtain a stack of tomographic slices of the rolled model. Each slice appears as spiral. The intensity variations along the cross-sectional result from ink on the papyrus. The files were elaborated with original software, written by the use of MATLAB high-level language, and the final result was quite similar to the radiography of the physically unrolled sheet. (orig.)

  12. X-ray structures and computational studies of several cathinones

    Science.gov (United States)

    Nycz, Jacek E.; Malecki, Grzegorz; Zawiazalec, Marcin; Pazdziorek, Tadeusz

    2011-09-01

    2-(Ethylamino)-1-(4-methylphenyl)propan-1-one (shortly named 4-MEC) ( 1a), 1-(1,3-benzodioxol-5-yl)-2-(methylamino)propan-1-one (shortly named methylone or 3,4-methylenedioxymethcathinone) ( 1b), 1-(3,4-dimethylphenyl)-2-(methylamino)propan-1-one ( 1c), 2-methylamino-1-(4-methylphenyl)propan-1-one (shortly named mephedrone; 4-MMC or 4-methylmethcathinone) ( 1d) and 2-(methylamino)-1-phenylbutan-1-one (shortly named buphedrone) ( 1e) and their aminium salts ( 2a-e), are examples of cathinones which were characterized by FTIR, UV-Vis, multinuclear NMR spectroscopy. By single crystal X-ray diffraction method structures of 2a, 2b, 2c and 2d were determined. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, ethyl, N-methyl or N-ethyl groups. The diastereotopic methylene protons of 1a appear as an ABX 3, and 1e and 2e appear as an ABMX 3 system. The geometries of the studied compounds were optimized in singlet states using the density functional theory (DFT) method with B3LYP functional. Electronic spectra were calculated by TDDFT method. In general, the predicted bond lengths and angles are in good agreement with the values based on the X-ray crystal structure data.

  13. Computational modelling of semiconducting X-ray detectors

    CERN Document Server

    Fowler, R F; Greenough, C S

    2002-01-01

    The design of high-performance semiconductor detectors is dominated by requirements on position and energy resolution and speed of operation. We investigate the contribution that three-dimensional transient device modelling can make to understanding these and the potential for its use in the design cycle. Simulations are performed using the EVEREST software to solve the drift-diffusion equations. Extra functionality has been added to allow the generation of electron-hole pairs by, for example, the absorption of an X-ray. Careful time integration can measure the time of arrival of the charge packet at the collecting well. By time integrating the current arriving in the collecting well the spatial distribution of charge can be determined. A simple analytic theory is developed and compared with simulations of a large pixel detector. Comparisons with simulations of a two pixel device show that the analytic approximation is reasonable if the X-ray is absorbed beyond 100 mu m from the well, but events closer show a...

  14. X-ray computed tomography for virtually unrolling damaged papyri

    Science.gov (United States)

    Allegra, Dario; Ciliberto, Enrico; Ciliberto, Paolo; Petrillo, Giuseppe; Stanco, Filippo; Trombatore, Claudia

    2016-03-01

    The regular format for ancient works of literature was the papyrus roll. Recently many efforts to perform virtual restoration of this archeological artifact have been done. In fact the case of ancient rolled papyrus is very intriguing. Old papyruses are the substrates of very important historical information, probably being the use of papyrus dated to the Pre-Dynastic Period. Papyrus degradation is often very hard so that physical unrolling is sometime absolutely impossible. In this paper, authors describe their effort in setting a new virtual restoration methodology based on software manipulation of X-ray tomographic images. A realistic model, obtained by painting a hieroglyph inscription of Thutmosis III on a papyrus substrate made by the original method described by Plinius the Elder and by pigments and binders compatible with the Egyptian use (ochers with natural glue), was made for the X-ray investigation. A GE Optima 660 64 slice was used to obtain a stack of tomographic slices of the rolled model. Each slice appears as spiral. The intensity variations along the cross-sectional result from ink on the papyrus. The files were elaborated with original software, written by the use of MATLAB high-level language, and the final result was quite similar to the radiography of the physically unrolled sheet.

  15. Dictionary learning based denoising of low-dose X-ray CT image%基于字典学习的低剂量X-ray CT图像去噪

    Institute of Scientific and Technical Information of China (English)

    朱永成; 陈阳; 罗立民; Toumoulin Christine

    2012-01-01

    介绍了一种基于字典学习的去噪方法,并将其应用于降低低剂量CT图像噪声水平的研究.针对体模图像和病人图像,分别选择低剂量CT图像和正常剂量CT图像作为训练样本,采用K-SVD算法,通过迭代学习构建图像字典;然后,结合正交匹配跟踪算法,实现图像稀疏表示,稀疏成分对应于图像的有用信息,其他成分对应于图像噪声;最后,依据图像的稀疏成分重建图像,达到去除噪声的目的.实验结果表明:字典的大小、稀疏表示的约束条件等参数会显著影响所提算法的去噪结果;相比低剂量CT图像,将正常剂量CT图像作为训练样本可以得到更好的去噪结果;在相同的噪声水平下,所提算法与传统图像去噪算法相比可以更好地去除图像噪声,且保留了图像的细节信息.%A dictionary learning based denoising method is introduced to eliminate the noise in low-dose computed-tomography (LDCT) image. Aiming at the phantom and patient images, the &-means singular value decomposition (K-SVD) algorithm is adopted to train image dictionary itera-tively based on LDCT and normal-dose CT (NDCT) images. Then, based on the orthogonal matching pursuit algorithm, the sparse representation decomposes the noise image into sparse component which is related to image information and remains which are regarded as noise. Finally, noises can be suppressed by reconstructing image only with its sparse components. The experimental results show that the performance of the proposed method is strongly affected by the dictionary size and the constraints for sparsity in dictionary training. The better performance can be achieved when training samples are extracted from NDCT image instead of LDCT image. Under the same noise level, compared with the traditional de-noising methods, the proposed method is more effective in suppressing noise and improving the visual effect while maintaining more diagnostic image details.

  16. Element-sensitive computed tomography by fine tuning of PXR-based X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, Y., E-mail: yahayak@lebra.nihon-u.ac.jp [Laboratory for Electron Beam Research and Application, Nihon University, Narashinodai 7-24-1, Funabashi 274-8501 (Japan); Hayakawa, K.; Inagaki, M. [Laboratory for Electron Beam Research and Application, Nihon University, Narashinodai 7-24-1, Funabashi 274-8501 (Japan); Kaneda, T. [Nihon University School of Dentistry at Matsudo, Sakaecho-Nishi 2-870-1, Matsudo 271-8587 (Japan); Nakao, K.; Nogami, K. [Laboratory for Electron Beam Research and Application, Nihon University, Narashinodai 7-24-1, Funabashi 274-8501 (Japan); Sakae, T.; Sakai, T. [Nihon University School of Dentistry at Matsudo, Sakaecho-Nishi 2-870-1, Matsudo 271-8587 (Japan); Sato, I. [Laboratory for Electron Beam Research and Application, Nihon University, Narashinodai 7-24-1, Funabashi 274-8501 (Japan); Takahashi, Y. [Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Oho, Tsukuba 305-8501 (Japan); Tanaka, T. [Laboratory for Electron Beam Research and Application, Nihon University, Narashinodai 7-24-1, Funabashi 274-8501 (Japan)

    2015-07-15

    Element-sensitive computed tomography (CT) experiments were carried out based on the absorption edge of a specific element using a finely tunable X-ray beam generated by parametric X-ray radiation (PXR). Tomographic images of specimens containing strontium were measured at energies both lower and higher than that of the Sr absorption edge. The difference between the images of the two energies successfully reveals the three-dimensional distributions of Sr. The results demonstrate that this method is effective for elemental analysis of considerably thick samples and could complement X-ray fluorescence analysis.

  17. Aberrant cell divisions in root meristeme of maize following exposure to X-rays low doses compared to similar effects of 50 Hz electromagnetic exposure

    Science.gov (United States)

    Focea, R.; Capraru, G.; Racuciu, M.; Creanga, D.; Luchian, T.

    2012-04-01

    The response of maize to radiation exposure was investigated by two cytogenetic methods considering the importance of the geno-toxic effect for environmental and agricultural purposes. Uniform genophond seeds, freshly germinated, were exposed to relatively low radiation doses using a radiotherapy X-ray applicator from a hospital irradiation device and to a 50 Hz electromagnetic field with about 10 mT magnetic induction (generated within laboratory assembled electromagnetic coils). Radicular meristeme tissue aliquots were prevailed for cytogenetic investigation based on microscopic observations and cell counting. Microscope slides were prepared following a specific procedure (squash technique and Feulgen method based on modified Carr reactive coloration). Mitotic index as well as chromosomal aberration percentage were calculated for more than 30,000 cells taken into account. From a qualitative viewpoint, chromosomal aberrations such as interchromatidian bridges, lagging and expelled chromosomes and multipolar divisions were evidenced - no distinct situation for either ionizing radiation or electromagnetic field being identified. The main quantitative difference consisted in the increased mitotic index for electromagnetic exposure increased times compared with the diminished mitotic index in the case of low X-ray doses.

  18. Early effects comparison of X-rays delivered at high-dose-rate pulses by a plasma focus device and at low dose rate on human tumour cells.

    Science.gov (United States)

    Virelli, A; Zironi, I; Pasi, F; Ceccolini, E; Nano, R; Facoetti, A; Gavoçi, E; Fiore, M R; Rocchi, F; Mostacci, D; Cucchi, G; Castellani, G; Sumini, M; Orecchia, R

    2015-09-01

    A comparative study has been performed on the effects of high-dose-rate (DR) X-ray beams produced by a plasma focus device (PFMA-3), to exploit its potential medical applications (e.g. radiotherapy), and low-DR X-ray beams produced by a conventional source (XRT). Experiments have been performed at 0.5 and 2 Gy doses on a human glioblastoma cell line (T98G). Cell proliferation rate and potassium outward currents (IK) have been investigated by time lapse imaging and patch clamp recordings. The results showed that PFMA-3 irradiation has a greater capability to reduce the proliferation rate activity with respect to XRT, while it does not affect IK of T98G cells at any of the dose levels tested. XRT irradiation significantly reduces the mean IK amplitude of T98G cells only at 0.5 Gy. This work confirms that the DR, and therefore the source of radiation, is crucial for the planning and optimisation of radiotherapy applications.

  19. Visualization of x-ray computer tomography using computer-generated holography

    Science.gov (United States)

    Daibo, Masahiro; Tayama, Norio

    1998-09-01

    The theory converted from x-ray projection data to the hologram directly by combining the computer tomography (CT) with the computer generated hologram (CGH), is proposed. The purpose of this study is to offer the theory for realizing the all- electronic and high-speed seeing through 3D visualization system, which is for the application to medical diagnosis and non- destructive testing. First, the CT is expressed using the pseudo- inverse matrix which is obtained by the singular value decomposition. CGH is expressed in the matrix style. Next, `projection to hologram conversion' (PTHC) matrix is calculated by the multiplication of phase matrix of CGH with pseudo-inverse matrix of the CT. Finally, the projection vector is converted to the hologram vector directly, by multiplication of the PTHC matrix with the projection vector. Incorporating holographic analog computation into CT reconstruction, it becomes possible that the calculation amount is drastically reduced. We demonstrate the CT cross section which is reconstituted by He-Ne laser in the 3D space from the real x-ray projection data acquired by x-ray television equipment, using our direct conversion technique.

  20. Dynamic angle selection in X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Dabravolski, Andrei, E-mail: andrei.dabravolski@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Batenburg, Kees Joost, E-mail: joost.batenburg@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Centrum Wiskunde and Informatica (CWI), Science Park 123, 1098 XG Amsterdam (Netherlands); Sijbers, Jan, E-mail: jan.sijbers@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium)

    2014-04-01

    Highlights: • We propose the dynamic angle selection algorithm for CT scanning. • The approach is based on the concept of information gain over a set of solutions. • Projection angles are selected based on the already available projection data. • The approach can lead to more accurate results from fewer projections. - Abstract: In X-ray tomography, a number of radiographs (projections) are recorded from which a tomogram is then reconstructed. Conventionally, these projections are acquired equiangularly, resulting in an unbiased sampling of the Radon space. However, especially in case when only a limited number of projections can be acquired, the selection of the angles has a large impact on the quality of the reconstructed image. In this paper, a dynamic algorithm is proposed, in which new projection angles are selected by maximizing the information gain about the object, given the set of possible new angles. Experiments show that this approach can select projection angles for which the accuracy of the reconstructed image is significantly higher compared to the standard angle selections schemes.

  1. X-Ray or Computed Tomography Which Comes First?

    Directory of Open Access Journals (Sweden)

    Sancar Serbest

    2013-10-01

    The glenohumeral joint is the most commonly dislocated joint in the human body. Anterior dislocatin is the most common type and posterior dislocations account for <1% of shoulder dislocations.  A 28-yearold man was brought to the emergency department by ambulance. At the time of admission he was suffering left shoulder pain. On local physical examination, there was severe pain on the proximal humerus. The left arm was in internal rotation in the adducted position. On local physical examination, there was severe pain on the left proximal humerus. Active and passive movements of the left shoulder were painful and limited. The neurovascular examination of the left upper extremity revealed no deficit. There was no pathologic finding in other system examinations. Radiographs of his left shoulder were performed and no significant pathology was identified in the left shoulder anteroposterior (AP X-ray (Figure 1. Axillary radiography could not be performed because of painful arm movements. Therefore, CT was performed to clarify any existing shoulder pathology (Figure 2. Then intravenous Access was provided; sedation and analgesia was maintained. Closed reduction under conscious sedation was performed with longitudinal and lateral traction on the arm to protect the humeral head. Control CT was performed and this revealed that reduction had improved the shoulder (Figure 3. He was then treated with an arm sling and discharged with an outpatient orthopaedic control visit.

  2. INVOLVEMENT OF THE Ca2+-PROTEIN KINASE C AND ADENYLATE CYCLACE SIGNAL PATHWAYS IN THE ACTIVATION OF THYMOCYTES IN RESPONSE TO WHOLE-BODY IRRADIATION WITH LOW DOSE X-RAYS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective. To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation.Methods. Thymocytes from Kunming mice exposed to whole-body irradiation(WBI) with different doses of X-rays were analyzed for the changes in signal molecules of the phospholipase C-phosphatidylinositol biphosphate(PLC-IP2) and G protein-adenylate cyclase(AC) pathways.Results.It was found that[Ca2+]i increased in response to doses within 0.2 Gy which was most marked after 0.075 Gy and the increase was accentuated in the presence of Con A. The changes in CD3 and calcineurin(CN) expression of the thymocytes followed the same pattern as the alterations in [Ca2+]i after LDR. The expression of α,β1 and β2 isoforms of protein kinase C(PKC) was all up-regulated after 0.075 Gy with the increase in PKC-β1 expression being most marked. The cAMP/cGMP ratio and PKA activity of the thymocytes was lowered after low dose radiation and increased after doses above 0.5 Gy in a dose-dependent manner, thus giving rise to J-shaped dose-response curves. The Ca antagonist TMB-8 and cAMP stimulant cholera toxin suppressed the augmented thymocyte proliferation induced by LDR.Conclusion.Data presented in the present paper suggest that activation of the PLC-PIP2 signal pathway and suppression of the AC-cAMP signal pathway are involved in the stimulation of the thymocytes following WBI with low dose X-rays.

  3. Three dimensional subsurface elemental identification of minerals using confocal micro-X-ray fluorescence and micro-X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Cordes, Nikolaus L., E-mail: ncordes@lanl.gov [Polymers and Coatings Group, Material Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Seshadri, Srivatsan, E-mail: srivatsan.seshadri@zeiss.com [Carl Zeiss X-ray Microscopy, Inc., Pleasanton, CA 94588 (United States); Havrilla, George J. [Chemical Diagnostics and Engineering, Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Yuan, Xiaoli [Julius Kruttschnitt Mineral Research Centre, University of Queensland, Indooroopilly, Brisbane, QLD 4068 (Australia); Feser, Michael [Carl Zeiss X-ray Microscopy, Inc., Pleasanton, CA 94588 (United States); Patterson, Brian M. [Polymers and Coatings Group, Material Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2015-01-01

    Current non-destructive elemental characterization methods, such as scanning electron microscopy-based energy dispersive spectroscopy (SEM–EDS) and micro-X-ray fluorescence spectroscopy (MXRF), are limited to either elemental identification at the surface (SEM–EDS) or suffer from an inability to discriminate between surface or depth information (MXRF). Thus, a non-destructive elemental characterization of individual embedded particles beneath the surface is impossible with either of these techniques. This limitation can be overcome by using laboratory-based 3D confocal micro-X-ray fluorescence spectroscopy (confocal MXRF). This technique utilizes focusing optics on the X-ray source and detector which allows for spatial discrimination in all three dimensions. However, the voxel-by-voxel serial acquisition of a 3D elemental scan can be very time-intensive (~ 1 to 4 weeks) if it is necessary to locate individual embedded particles of interest. As an example, if each point takes a 5 s measurement time, a small volume of 50 × 50 × 50 pixels leads to an acquisition time of approximately 174 h, not including sample stage movement time. Initially screening the samples for particles of interest using micro-X-ray computed tomography (micro-CT) can significantly reduce the time required to spatially locate these particles. Once located, these individual particles can be elementally characterized with confocal MXRF. Herein, we report the elemental identification of high atomic number surface and subsurface particles embedded in a mineralogical matrix by coupling micro-CT and confocal MXRF. Synergistically, these two X-ray based techniques first rapidly locate and then elementally identify individual subsurface particles. - Highlights: • Coupling of confocal X-ray fluorescence spectroscopy and X-ray computed tomography • Qualitative elemental identification of surface and subsurface mineral particles • Non-destructive particle size measurements • Utilization of

  4. Scattering-compensated cone beam x-ray luminescence computed tomography

    Science.gov (United States)

    Gao, Peng; Rong, Junyan; Pu, Huangsheng; Liu, Wenlei; Liao, Qimei; Lu, Hongbing

    2016-04-01

    X-ray luminescence computed tomography (XLCT) opens new possibilities to perform molecular imaging with x-ray. It is a dual modality imaging technique based on the principle that some nanophosphors can emit near-infrared (NIR) light when excited by x-rays. The x-ray scattering effect is a great issue in both CT and XLCT reconstruction. It has been shown that if the scattering effect compensated, the reconstruction average relative error can be reduced from 40% to 12% in the in the pencil beam XLCT. However, the scattering effect in the cone beam XLCT has not been proved. To verify and reduce the scattering effect, we proposed scattering-compensated cone beam x-ray luminescence computed tomography using an added leading to prevent the spare x-ray outside the irradiated phantom in order to decrease the scattering effect. Phantom experiments of two tubes filled with Y2O3:Eu3+ indicated that the proposed method could reduce the scattering by a degree of 30% and can reduce the location error from 1.8mm to 1.2mm. Hence, the proposed method was feasible to the general case and actual experiments and it is easy to implement.

  5. Methylation changes in muscle and liver tissues of male and female mice exposed to acute and chronic low-dose X-ray-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kovalchuk, Olga; Burke, Paula; Besplug, Jill; Slovack, Mark; Filkowski, Jody; Pogribny, Igor

    2004-04-14

    The biological and genetic effects of chronic low-dose radiation (LDR) exposure and its relationship to carcinogenesis have received a lot of attention in the recent years. For example, radiation-induced genome instability, which is thought to be a precursor of tumorogenesis, was shown to have a transgenerational nature. This indicates a possible involvement of epigenetic mechanisms in LDR-induced genome instability. Genomic DNA methylation is one of the most important epigenetic mechanisms. Existing data on radiation effects on DNA methylation patterns is limited, and no one has specifically studied the effects of the LDR. We report the first study of the effects of whole-body LDR exposure on global genome methylation in muscle and liver tissues of male and female mice. In parallel, we evaluated changes in promoter methylation and expression of the tumor suppressor gene p16{sup INKa} and DNA repair gene O{sup 6}-methylguanine-DNA methyltransferase (MGMT). We observed different patterns of radiation-induced global genome DNA methylation in the liver and muscle of exposed males and females. We also found sex and tissue-specific differences in p16{sup INKa} promoter methylation upon LDR exposure. In male liver tissue, p16{sup INKa} promoter methylation was more pronounced than in female tissue. In contrast, no significant radiation-induced changes in p16{sup INKa} promoter methylation were noted in the muscle tissue of exposed males and females. Radiation also did not significantly affect methylation status of MGMT promoter. We also observed substantial sex differences in acute and chronic radiation-induced expression of p16{sup INKa} and MGMT genes. Another important outcome of our study was the fact that chronic low-dose radiation exposure proved to be a more potent inducer of epigenetic effects than the acute exposure. This supports previous findings that chronic exposure leads to greater genome destabilization than acute exposure.

  6. Low-dose computed tomographic imaging in orbital trauma

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, A.; Whitehouse, R.W. (Manchester Univ. (United Kingdom). Dept. of Diagnostic Radiology)

    1993-08-01

    The authors review findings in 75 computed tomographic (CT) examinations of 66 patients with orbital trauma who were imaged using a low-radiation-dose CT technique. Imaging was performed using a dynamic scan mode and exposure factors of 120 kVp and 80 mAs resulting in a skin dose of 11 mGy with an effective dose-equivalent of 0.22 mSv. Image quality was diagnostic in all cases and excellent in 73 examinations. Soft-tissue abnormalities within the orbit including muscle adhesions were well demonstrated both on primary axial and reconstructed multiplanar images. The benefits of multiplanar reconstructions are stressed and the contribution of soft-tissue injuries to symptomatic diplopia examined. (author).

  7. X-Ray Computed Tomography for Advanced Materials and Processes.

    Science.gov (United States)

    1992-06-30

    percent. In this example, we have assumed $I M, $5(X)K and $200K CT systems operating at 10 percent of the capital investment per year for maintenance...Computed Tomo &:aphy of Composites," WRDC-TR-90-4014, July 1990. 5. P. Burstein and R. H. Bossi, "A Guide to Computed Tomography System Specifications," WRDC...Lannutti, "Applications of High- Resolution Computed Tomography," Proceedings of the 1991 Industrial Computed Tomography II Topical Conference, May 20-24

  8. Optimization of X-ray tomography through a cooperative computing system in grid

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Moin, E-mail: mmoinhhasan@gmail.com; Goraya, Major Singh, E-mail: mjrsingh@yahoo.com [Department of Computer Science and Engineering, SLIET (Longowal) (India)

    2015-08-28

    Cooperative Computing implemented as Cooperative Computing System (CCS) in grid has been proved a considerably reliable technique to execute the tasks with real time constraints in a grid environment. This technique can be applied in many high performance distributed computing applications. HPC has a large number of applications in various fields of physics. One such application in radiation physics is X-ray tomography. X-Ray tomography contains numerous applications in various fields of science, technology and research. As the technology is changing from analog to digital in almost all the scenarios, this paper presents an idea towards the attachment of X-ray tomography assembly to HPC environment so as to obtain the highly reliable optimization.

  9. Measuring the efficacy of a root biobarrier with x-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Tollner, E.W.; Murphy, C.E. Jr. (Georgia Univ., Griffin, GA (USA). Dept. of Agricultural Engineering)

    1990-08-16

    X-ray computed tomography is a useful tool for investigating soil physical properties nondestructively. There is a need to develop proper calibration relationships between soil properties and the x-ray absorption coefficient. The objective of the work was to evaluate soil factors affecting the x-ray absorption coefficient. Based on a theoretical analysis, experimental data from five soils and on results of several other investigators, it was concluded that for many applications, one calibration relationship is applicable to a wide range of soils. The montmorillinitic clay used in the study required special handling due to the extreme shrinkage of this soil upon drying. Knowledge of chemical composition enables approximations but not exact predictions of the x-ray absorption coefficient. The results suggested some reasonable alternative to exhaustive calibration for each anticipated soil condition. Quantification of root activity in terms of root growth and indirectly through water uptake is necessary for understanding plant growth dynamics. X-ray computed tomography (CT) enables qualitative as well as two quantitative outputs, one of which can lead to conclusions regarding root activity. A greenhouse study involving soil columns (Lakeland sand, bulk density 1.4 Mg/m{sup 3}) planted to soybean, Bahiagras, and control (no vegetation) was conducted in 1989. A treflan based on chemical barrier was placed in half of the soil column of each species. The mean x-ray absorption correlated to water content. Results suggested that root presence can also be indirectly inferred based on water content drawn down during planned stress events. It was concluded that x-ray CT may have a niche in soil-water-plant relation studies, particularly when plant species have large roots. 35 refs., 13 figs., 8 tabs.

  10. Building a Unified Computational Model for the Resonant X-Ray Scattering of Strongly Correlated Materials

    Energy Technology Data Exchange (ETDEWEB)

    Bansil, Arun [Northeastern Univ., Boston, MA (United States)

    2016-12-01

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspects of this grand challenge of X-ray science. In particular, our Collaborative Research Team (CRT) focused on understanding and modeling of elastic and inelastic resonant X-ray scattering processes. We worked to unify the three different computational approaches currently used for modeling X-ray scattering—density functional theory, dynamical mean-field theory, and small-cluster exact diagonalization—to achieve a more realistic material-specific picture of the interaction between X-rays and complex matter. To achieve a convergence in the interpretation and to maximize complementary aspects of different theoretical methods, we concentrated on the cuprates, where most experiments have been performed. Our team included both US and international researchers, and it fostered new collaborations between researchers currently working with different approaches. In addition, we developed close relationships with experimental groups working in the area at various synchrotron facilities in the US. Our CRT thus helped toward enabling the US to assume a leadership role in the theoretical development of the field, and to create a global network and community of scholars dedicated to X-ray scattering research.

  11. Dose evaluation for paediatric chest x-ray examinations in Brazil and Sudan: low doses and reliable examinations can be achieved in developing countries

    Energy Technology Data Exchange (ETDEWEB)

    Mohamadain, K E M [FIOCRUZ-Escola Nacional de Saude Publica-CESTEH, Rua Leopoldo Bulhoes 1480, Manguinhos, 21041-210 Rio de Janeiro (Brazil); Rosa, L A R da [Departamento de FIsica Medica, Instituto de Radioprotecao e Dosimetria, Comissao Nacional de Energia Nuclear, 22780-160 Rio de Janeiro (Brazil); Azevedo, A C P [FIOCRUZ-Escola Nacional de Saude Publica-CESTEH, Rua Leopoldo Bulhoes 1480, Manguinhos, 21041-210 Rio de Janeiro (Brazil); Guebel, M R N [Instituto de Pediatria e Puericultura Martagao Gesteira, UFRJ, 21490-910 Rio de Janeiro (Brazil); Boechat, M C B [FIOCRUZ-Instituto Fernandes Figueira, Rio de Janeiro (Brazil); Habani, F [Physics Department, Faculty of Sciences, Khartoum University, Khartoum (Sudan)

    2004-03-21

    Radiation protection in paediatric radiology deserves special attention since it is assumed that children are more sensitive to radiation than adults. The aim of this work is to estimate the entrance skin dose (ESD), the body organ dose (BOD) and the effective dose (E) for chest x-ray exposure of paediatric patients in five large units, three in Sudan and two in Brazil, and to compare the results obtained in both countries with each other and with other values obtained by some European countries. Two examination projections have been investigated, namely, postero-anterior (PA) and antero-posterior (AP). The age intervals considered were: 0-1 year, 1-5 years, 5-10 years and 10-15 years. The results have been obtained with the use of a software called DoseCal. Results of mean ESD for the age interval 1-5 years and AP projection are: 66 {mu}Gy (Instituto de Pediatria e Puericultura Martagao Gesteira-IPPMG Hospital), 41, 86 and 68 {mu}Gy (Instituto Fernandes Figueira-IFF Hospital), 161 {mu}Gy (Omdurman Hospital), 395 {mu}Gy (Khartoum Hospital) and 23 {mu}Gy (Ahmed Gasim Hospital). In the case of the IFF Hospital, the results refer, respectively, to rooms 1, 2 and for the six mobile equipments. The reference dose values given by the European Guidelines were exceeded in the Khartoum Hospital whilst in all the other hospitals results obtained were below CEC reference values and comparable with the results found in Sweden, Germany, Spain and Italy. The mean E for the same age interval was 11 {mu}Sv in the IPPMG, 6, 15 and 11 {mu}Sv in the IFF, respectively for rooms 1, 2 and the 6 mobiles, 25 {mu}Sv in the Omdurman Hospital, 45 {mu}Sv in the Khartoum Hospital and 3 {mu}Sv in the Ahmed Gasim Hospital. These are some examples of the large discrepancies that have been detected in this survey.

  12. Dose evaluation for paediatric chest x-ray examinations in Brazil and Sudan: low doses and reliable examinations can be achieved in developing countries

    Science.gov (United States)

    Mohamadain, K. E. M.; da Rosa, L. A. R.; Azevedo, A. C. P.; Guebel, M. R. N.; Boechat, M. C. B.; Habani, F.

    2004-03-01

    Radiation protection in paediatric radiology deserves special attention since it is assumed that children are more sensitive to radiation than adults. The aim of this work is to estimate the entrance skin dose (ESD), the body organ dose (BOD) and the effective dose (E) for chest x-ray exposure of paediatric patients in five large units, three in Sudan and two in Brazil, and to compare the results obtained in both countries with each other and with other values obtained by some European countries. Two examination projections have been investigated, namely, postero-anterior (PA) and antero-posterior (AP). The age intervals considered were: 0-1 year, 1-5 years, 5-10 years and 10-15 years. The results have been obtained with the use of a software called DoseCal. Results of mean ESD for the age interval 1-5 years and AP projection are: 66 µGy (Instituto de Pediatria e Puericultura Martagão Gesteira—IPPMG Hospital), 41, 86 and 68 µGy (Instituto Fernandes Figueira—IFF Hospital), 161 µGy (Omdurman Hospital), 395 µGy (Khartoum Hospital) and 23 µGy (Ahmed Gasim Hospital). In the case of the IFF Hospital, the results refer, respectively, to rooms 1, 2 and for the six mobile equipments. The reference dose values given by the European Guidelines were exceeded in the Khartoum Hospital whilst in all the other hospitals results obtained were below CEC reference values and comparable with the results found in Sweden, Germany, Spain and Italy. The mean E for the same age interval was 11 µSv in the IPPMG, 6, 15 and 11 µSv in the IFF, respectively for rooms 1, 2 and the 6 mobiles, 25 µSv in the Omdurman Hospital, 45 µSv in the Khartoum Hospital and 3 µSv in the Ahmed Gasim Hospital. These are some examples of the large discrepancies that have been detected in this survey.

  13. Characterization of Scalar Mixing in Dense Gaseous Jets Using X-Ray Computed Tomography

    Science.gov (United States)

    Dunnmon, Jared; Kim, Tae Wook; Kovscek, Anthony; Fahrig, Rebecca; Ihme, Matthias

    2014-11-01

    An experimental technique based on X-Ray Computed Tomography (XCT) is used to characterize scalar mixing of gaseous jets at Reynolds numbers up to 20,000. In this study, the mixing of a krypton jet with ambient air is considered. The high radiodensity of the krypton gas enables non-intrusive volumetric measurements of gas density and mixture composition based on spatial variations in x-ray attenuation. Comparisons to theoretical and computational results are presented, and the viability of this diagnostic technique is assessed. Important aspects of x-ray attenuation theory and practice are considered in data processing and their impacts on future development of this technique are discussed. Support from DoD through the NDSEG Fellowship Program and from NIH through S10 Shared Instrumentation Grant S10RR026714-01 are gratefully acknowledged.

  14. Characterization of scalar mixing in dense gaseous jets using X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Dunnmon, Jared; Sobhani, Sadaf; Ihme, Matthias [Stanford University, Department of Mechanical Engineering, Stanford, CA (United States); Kim, Tae Wook; Kovscek, Anthony [Stanford University, Department of Energy Resources Engineering, Stanford, CA (United States)

    2015-10-15

    An experimental technique based on X-ray computed tomography (XCT) is used to characterize scalar mixing of a krypton jet with air at turbulent conditions. The high radiodensity of the krypton gas enables non-intrusive volumetric measurements of gas density and mixture composition based on spatial variations in X-ray attenuation. Comparisons of these measurements to both computational results from large-eddy simulations and data from previous experiments are presented, and the viability of this diagnostic technique is assessed. Important aspects of X-ray attenuation theory, XCT practice, and relevant error analysis are considered in data processing, and their impacts on the future development of this technique are discussed. (orig.)

  15. Synthesis, quantum chemical computations and x-ray ...

    African Journals Online (AJOL)

    Benyza N

    2017-05-01

    May 1, 2017 ... structure using DFT method with B3LYP functional at 6-31G (d,p) and (LANL2DZ) levels in vacuo. 2. ... Formula weight (g mol. -1. ) ..... All the computations of mentioned complex were performed using the Gaussian 09 program ...

  16. X-ray fluorescence computed tomography (XFCT) imaging of gold nanoparticle-loaded objects using 110 kVp x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Seong-Kyun; Jones, Bernard L; K Siddiqi, Arsalan; Liu, Fang; Manohar, Nivedh; Cho, Sang Hyun [Nuclear and Radiological Engineering and Medical Physics Programs, Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)], E-mail: scho@gatech.edu

    2010-02-07

    A conventional x-ray fluorescence computed tomography (XFCT) technique requires monochromatic synchrotron x-rays to simultaneously determine the spatial distribution and concentration of various elements such as metals in a sample. However, the synchrotron-based XFCT technique appears to be unsuitable for in vivo imaging under a typical laboratory setting. In this study we demonstrated, for the first time to our knowledge, the possibility of performing XFCT imaging of a small animal-sized object containing gold nanoparticles (GNPs) at relatively low concentrations using polychromatic diagnostic energy range x-rays. Specifically, we created a phantom made of polymethyl methacrylate plastic containing two cylindrical columns filled with saline solution at 1 and 2 wt% GNPs, respectively, mimicking tumors/organs within a small animal. XFCT scanning of the phantom was then performed using microfocus 110 kVp x-ray beam and cadmium telluride (CdTe) x-ray detector under a pencil beam geometry after proper filtering of the x-ray beam and collimation of the detector. The reconstructed images clearly identified the locations of the two GNP-filled columns with different contrast levels directly proportional to gold concentration levels. On the other hand, the current pencil-beam implementation of XFCT is not yet practical for routine in vivo imaging tasks with GNPs, especially in terms of scanning time. Nevertheless, with the use of multiple detectors and a limited number of projections, it may still be used to image some objects smaller than the current phantom size. The current investigation suggests several modification strategies of the current XFCT setup, such as the adoption of the quasi-monochromatic cone/fan x-ray beam and XFCT-specific spatial filters or pinhole detector collimators, in order to establish the ultimate feasibility of a bench-top XFCT system for GNP-based preclinical molecular imaging applications.

  17. X-ray fluorescence computed tomography (XFCT) imaging of gold nanoparticle-loaded objects using 110 kVp x-rays.

    Science.gov (United States)

    Cheong, Seong-Kyun; Jones, Bernard L; Siddiqi, Arsalan K; Liu, Fang; Manohar, Nivedh; Cho, Sang Hyun

    2010-02-07

    A conventional x-ray fluorescence computed tomography (XFCT) technique requires monochromatic synchrotron x-rays to simultaneously determine the spatial distribution and concentration of various elements such as metals in a sample. However, the synchrotron-based XFCT technique appears to be unsuitable for in vivo imaging under a typical laboratory setting. In this study we demonstrated, for the first time to our knowledge, the possibility of performing XFCT imaging of a small animal-sized object containing gold nanoparticles (GNPs) at relatively low concentrations using polychromatic diagnostic energy range x-rays. Specifically, we created a phantom made of polymethyl methacrylate plastic containing two cylindrical columns filled with saline solution at 1 and 2 wt% GNPs, respectively, mimicking tumors/organs within a small animal. XFCT scanning of the phantom was then performed using microfocus 110 kVp x-ray beam and cadmium telluride (CdTe) x-ray detector under a pencil beam geometry after proper filtering of the x-ray beam and collimation of the detector. The reconstructed images clearly identified the locations of the two GNP-filled columns with different contrast levels directly proportional to gold concentration levels. On the other hand, the current pencil-beam implementation of XFCT is not yet practical for routine in vivo imaging tasks with GNPs, especially in terms of scanning time. Nevertheless, with the use of multiple detectors and a limited number of projections, it may still be used to image some objects smaller than the current phantom size. The current investigation suggests several modification strategies of the current XFCT setup, such as the adoption of the quasi-monochromatic cone/fan x-ray beam and XFCT-specific spatial filters or pinhole detector collimators, in order to establish the ultimate feasibility of a bench-top XFCT system for GNP-based preclinical molecular imaging applications.

  18. DNA–PKcs–SIN1 complexation mediates low-dose X-ray irradiation (LDI)-induced Akt activation and osteoblast differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yong; Fang, Shi-ji [The Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou 215000 (China); Zhu, Li-juan [Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and Institute of Neuroscience, Soochow University, Suzhou, Jiangsu 215021 (China); Zhu, Lun-qing, E-mail: xiaodongwangsz@163.com [The Center of Diagnosis and Treatment for Children’s Bone Diseases, The Children’s Hospital Affiliated to Soochow University, Suzhou, Jiangsu 215000 (China); Zhou, Xiao-zhong, E-mail: zhouxz@suda.edu.cn [The Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou 215000 (China)

    2014-10-24

    Highlights: • LDI increases ALP activity, promotes type I collagen (Col I)/Runx2 mRNA expression. • LDI induces DNA–PKcs activation, which is required for osteoblast differentiation. • Akt activation mediates LDI-induced ALP activity and Col I/Runx2 mRNA increase. • DNA–PKcs–SIN1 complexation mediates LDI-induced Akt Ser-473 phosphorylation. • DNA–PKcs–SIN1 complexation is important for osteoblast differentiation. - Abstract: Low-dose irradiation (LDI) induces osteoblast differentiation, however the underlying mechanisms are not fully understood. In this study, we explored the potential role of DNA-dependent protein kinase catalytic subunit (DNA–PKcs)–Akt signaling in LDI-induced osteoblast differentiation. We confirmed that LDI promoted mouse calvarial osteoblast differentiation, which was detected by increased alkaline phosphatase (ALP) activity as well as mRNA expression of type I collagen (Col I) and runt-related transcription factor 2 (Runx2). In mouse osteoblasts, LDI (1 Gy) induced phosphorylation of DNA–PKcs and Akt (mainly at Ser-473). The kinase inhibitors against DNA–PKcs (NU-7026 and NU-7441) or Akt (LY294002, perifosine and MK-2206), as well as partial depletion of DNA–PKcs or Akt1 by targeted-shRNA, dramatically inhibited LDI-induced Akt activation and mouse osteoblast differentiation. Further, siRNA-knockdown of SIN1, a key component of mTOR complex 2 (mTORC2), also inhibited LDI-induced Akt Ser-473 phosphorylation as well as ALP activity increase and Col I/Runx2 expression in mouse osteoblasts. Co-immunoprecipitation (Co-IP) assay results demonstrated that LDI-induced DNA–PKcs–SIN1 complexation, which was inhibited by NU-7441 or SIN1 siRNA-knockdown in mouse osteoblasts. In summary, our data suggest that DNA–PKcs–SIN1 complexation-mediated Akt activation (Ser-473 phosphorylation) is required for mouse osteoblast differentiation.

  19. Development of a Computer-Controlled Polishing Process for X-Ray Optics

    Science.gov (United States)

    Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian

    2009-01-01

    The future X-ray observatory missions require grazing-incidence x-ray optics with angular resolution of polished mandrels from which the shells are replicated. With an aim to fabricate better shells, and reduce the cost/time of mandrel production, a computer-controlled polishing machine is developed for deterministic and localized polishing of mandrels. Cylindrical polishing software is also developed that predicts the surface residual errors under a given set of operating parameters and lap configuration. Design considerations of the polishing lap are discussed and the effects of nonconformance of the lap and the mandrel are presented.

  20. Visualization of self-healing materials by X-ray computed micro-tomography at UGCT

    OpenAIRE

    Bultreys, Tom; Masschaele, Bert; Hillewaere, Xander; Dierick, Manuel; Van Loo, Denis; Van Hoorebeke, Luc; Cnudde, Veerle

    2013-01-01

    This work presents recent advancements in X-ray micro-computed tomography (XRMCT) of self-healing materials at Ghent University’s Centre for X-ray Tomography (UGCT). Results of XRMCT imaging in a self-healing polymer system are shown to demonstrate the use of XRMCT in self-healing studies. Furthermore, two new XRMCT scanners are presented. The HECTOR scanner was designed for large samples and strongly attenuating samples, and is therefore well suited to study self-healing concrete. The EMCT s...

  1. Hafnium-Based Contrast Agents for X-ray Computed Tomography.

    Science.gov (United States)

    Berger, Markus; Bauser, Marcus; Frenzel, Thomas; Hilger, Christoph Stephan; Jost, Gregor; Lauria, Silvia; Morgenstern, Bernd; Neis, Christian; Pietsch, Hubertus; Sülzle, Detlev; Hegetschweiler, Kaspar

    2017-05-15

    Heavy-metal-based contrast agents (CAs) offer enhanced X-ray absorption for X-ray computed tomography (CT) compared to the currently used iodinated CAs. We report the discovery of new lanthanide and hafnium azainositol complexes and their optimization with respect to high water solubility and stability. Our efforts culminated in the synthesis of BAY-576, an uncharged hafnium complex with 3:2 stoichiometry and broken complex symmetry. The superior properties of this asymmetrically substituted hafnium CA were demonstrated by a CT angiography study in rabbits that revealed excellent signal contrast enhancement.

  2. Observations on the Performance of X-Ray Computed Tomography for Dimensional Metrology

    Science.gov (United States)

    Corcoran, H. C.; Brown, S. B.; Robson, S.; Speller, R. D.; McCarthy, M. B.

    2016-06-01

    X-ray computed tomography (XCT) is a rising technology within many industries and sectors with a demand for dimensional metrology, defect, void analysis and reverse engineering. There are many variables that can affect the dimensional metrology of objects imaged using XCT, this paper focusses on the effects of beam hardening due to the orientation of the workpiece, in this case a holeplate, and the volume of material the X-rays travel through. Measurements discussed include unidirectional and bidirectional dimensions, radii of cylinders, fit point deviations of the fitted shapes and cylindricity. Results indicate that accuracy and precision of these dimensional measurements are affected in varying amounts, both by the amount of material the X-rays have travelled through and the orientation of the object.

  3. Metal artifact removal (MAR) analysis for the security inspections using the X-ray computed tomography

    Science.gov (United States)

    Cho, Hyo Sung; Woo, Tae Ho; Park, Chul Kyu

    2016-10-01

    Using the metal artifact property, it is analyzed for the X-ray computed tomography (CT) in the aspect of the security on the examined places like airport and surveillance areas. Since the importance of terror prevention strategy has been increased, the security application of X-ray CT has the significant remark. One shot X-ray image has the limitation to find out the exact shape to property in the closed box, which could be solved by the CT scanning without the tearing off the box in this work. Cleaner images can be obtained by the advanced technology if the CT scanning is utilized in the security purposes on the secured areas. A metal sample is treated by the metal artifact removal (MAR) method for the enhanced image. The mimicked explosive is experimented for the imaging processing application where the cleaner one is obtained. The procedure is explained and the further study is discussed.

  4. OBSERVATIONS ON THE PERFORMANCE OF X-RAY COMPUTED TOMOGRAPHY FOR DIMENSIONAL METROLOGY

    Directory of Open Access Journals (Sweden)

    H. C. Corcoran

    2016-06-01

    Full Text Available X-ray computed tomography (XCT is a rising technology within many industries and sectors with a demand for dimensional metrology, defect, void analysis and reverse engineering. There are many variables that can affect the dimensional metrology of objects imaged using XCT, this paper focusses on the effects of beam hardening due to the orientation of the workpiece, in this case a holeplate, and the volume of material the X-rays travel through. Measurements discussed include unidirectional and bidirectional dimensions, radii of cylinders, fit point deviations of the fitted shapes and cylindricity. Results indicate that accuracy and precision of these dimensional measurements are affected in varying amounts, both by the amount of material the X-rays have travelled through and the orientation of the object.

  5. Estimation of measurement uncertainties in X-ray computed tomography metrology using the substitution method

    DEFF Research Database (Denmark)

    Müller, Pavel; Hiller, Jochen; Dai, Y.

    2014-01-01

    This paper presents the application of the substitution method for the estimation of measurement uncertainties using calibrated workpieces in X-ray computed tomography (CT) metrology. We have shown that this, well accepted method for uncertainty estimation using tactile coordinate measuring...

  6. Using x-ray computed tomography in hydrology: Systems, resolutions, and limitations

    DEFF Research Database (Denmark)

    Wildenschild, Dorthe; Hopmans, J.W.; Vaz, C.M.P.;

    2002-01-01

    A combination of advances in experimental techniques and mathematical analysis has made it possible to characterize phase distribution and pore geometry in porous media using non-destructive X-ray computed tomography (CT). We present qualitative and quantitative CT results for partially saturated...

  7. Computer Evaluation Of Real-Time X-Ray And Acoustic Images

    Science.gov (United States)

    Jacoby, M. H.; Loe, R. S.; Dondes, P. A.

    1983-03-01

    The weakest link in the inspection process is the subjective interpretation of data by inspectors. To overcome this troublesome fact computer based analysis systems have been developed. In the field of nondestructive evaluation (NDE) there is a large class of inspections that can benefit from computer analysis. X-ray images (both film and fluoroscopic) and acoustic images lend themselves to automatic analysis as do the one-dimensional signals associated with ultrasonic, eddy current and acoustic emission testing. Computer analysis can enhance and evaluate subtle details. Flaws can be located and measured, and accept-ance decisions made by computer in a consistent and objective manner. This paper describes the interactive, computer-based analysis of real-time x-ray images and acoustic images of graphite/epoxy adhesively bonded structures.

  8. Monochromatic computed tomography with a compact laser-driven X-ray source.

    Science.gov (United States)

    Achterhold, K; Bech, M; Schleede, S; Potdevin, G; Ruth, R; Loewen, R; Pfeiffer, F

    2013-01-01

    A laser-driven electron-storage ring can produce nearly monochromatic, tunable X-rays in the keV energy regime by inverse Compton scattering. The small footprint, relative low cost and excellent beam quality provide the prospect for valuable preclinical use in radiography and tomography. The monochromaticity of the beam prevents beam hardening effects that are a serious problem in quantitative determination of absorption coefficients. These values are important e.g. for osteoporosis risk assessment. Here, we report quantitative computed tomography (CT) measurements using a laser-driven compact electron-storage ring X-ray source. The experimental results obtained for quantitative CT measurements on mass absorption coefficients in a phantom sample are compared to results from a rotating anode X-ray tube generator at various peak voltages. The findings confirm that a laser-driven electron-storage ring X-ray source can indeed yield much higher CT image quality, particularly if quantitative aspects of computed tomographic imaging are considered.

  9. Low-dose computed tomography screening for lung cancer : Results of the first screening round

    NARCIS (Netherlands)

    Horeweg, Nanda; Nackaerts, Kristiaan; Oudkerk, Matthijs; de Koning, Harry J.

    Evaluation of: National Lung Screening Trial Research Team, Church TR, Black WC, Aberle DR et al. Results of initial low-dose computed tomographic screening for lung cancer. N. Engl. J. Med. 368, 1980-1991 (2013). In 2011, the US NLST trial demonstrated that mortality from lung cancer can be reduced

  10. Dental cone-beam CT reconstruction from limited-angle view data based on compressed-sensing (CS) theory for fast, low-dose X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Je, Uikyu; Cho, Hyosung; Lee, Minsik; Oh, Jieun; Park, Yeonok; Hong, Daeki; Park, Cheulkyu; Cho, Heemoon; Choi, Sungil; Koo, Yangseo [Yonsei University, Wonju (Korea, Republic of)

    2014-06-15

    Recently, reducing radiation doses has become an issue of critical importance in the broader radiological community. As a possible technical approach, especially, in dental cone-beam computed tomography (CBCT), reconstruction from limited-angle view data (< 360 .deg. ) would enable fast scanning with reduced doses to the patient. In this study, we investigated and implemented an efficient reconstruction algorithm based on compressed-sensing (CS) theory for the scan geometry and performed systematic simulation works to investigate the image characteristics. We also performed experimental works by applying the algorithm to a commercially-available dental CBCT system to demonstrate its effectiveness for image reconstruction in incomplete data problems. We successfully reconstructed CBCT images with incomplete projections acquired at selected scan angles of 120, 150, 180, and 200 .deg. with a fixed angle step of 1.2 .deg. and evaluated the reconstruction quality quantitatively. Both simulation and experimental demonstrations of the CS-based reconstruction from limited-angle view data show that the algorithm can be applied directly to current dental CBCT systems for reducing the imaging doses and further improving the image quality.

  11. [Hardware-software system for monitoring parameters and characteristics of X-ray computer tomographs under operation conditions].

    Science.gov (United States)

    Blinov, N N; Zelikman, M I; Kruchinin, S A

    2007-01-01

    The results of testing of hardware and software for monitoring parameters (mean number of CT units, noise, field uniformity, high-contrast spatial resolution, layer width, dose) and characteristics (modulation transfer function) of X-ray computer tomographs are presented. The developed hardware and software are used to monitor the stability of X-ray computer tomograph parameters under operation conditions.

  12. A meta-analysis: is low-dose computed tomography a superior method for risky lung cancers screening population?

    Science.gov (United States)

    Fu, Cuiping; Liu, Zilong; Zhu, Fen; Li, Shanqun; Jiang, Liyan

    2016-05-01

    Low-dose computed tomography (LDCT) has been proposed to be a new screening method to discover lung cancers in an early stage, especially those patients who are in a high risk of lung cancer. The primary objective of this meta-analysis is to systematically review the effect of LDCT on screening for lung cancers among the risky population who are older than 49 years old and with smoking exposure. We searched randomized controlled clinical trials (RCTs) about comparing LDCT and chest X-ray or usual caring from MEDLINE, EMBASE, and the Cochrane Library, Web of Knowledge and SpringerLink databases (January 1994 to September 2013). Nine RCTs met criteria for inclusion. Screening for lung cancer using LDCT resulted in a significantly higher number of stage I lung cancers [odds ratio (OR) 2.15, 95% confidence interval (CI) 1.88-2.47], higher number of total lung cancers (OR 1.31, 95% CI 1.20-1.43) than the control. Four of the nine studies indicated that the screening method did not decrease all-cause mortality (OR 0.96, 95% CI 0.90-1.02), but decreased lung cancer-specific mortality (OR 0.84, 95% CI 0.74-0.96). Five studies showed that LDCT had higher false-positive rates (OR 8.7, 95% CI 7.43-10.19) than the group of control. Among the risky population, LDCT screening find out more stage I lung cancers and total lung cancers compared with chest X-ray or no screening, and also shows advantages in decreasing lung cancer-specific mortality, but the screening method does not decrease all-cause mortality and have a higher false-positive rates in diagnosis. © 2014 John Wiley & Sons Ltd.

  13. Cone Beam X-ray Luminescence Computed Tomography Based on Bayesian Method.

    Science.gov (United States)

    Zhang, Guanglei; Liu, Fei; Liu, Jie; Luo, Jianwen; Xie, Yaoqin; Bai, Jing; Xing, Lei

    2017-01-01

    X-ray luminescence computed tomography (XLCT), which aims to achieve molecular and functional imaging by X-rays, has recently been proposed as a new imaging modality. Combining the principles of X-ray excitation of luminescence-based probes and optical signal detection, XLCT naturally fuses functional and anatomical images and provides complementary information for a wide range of applications in biomedical research. In order to improve the data acquisition efficiency of previously developed narrow-beam XLCT, a cone beam XLCT (CB-XLCT) mode is adopted here to take advantage of the useful geometric features of cone beam excitation. Practically, a major hurdle in using cone beam X-ray for XLCT is that the inverse problem here is seriously ill-conditioned, hindering us to achieve good image quality. In this paper, we propose a novel Bayesian method to tackle the bottleneck in CB-XLCT reconstruction. The method utilizes a local regularization strategy based on Gaussian Markov random field to mitigate the ill-conditioness of CB-XLCT. An alternating optimization scheme is then used to automatically calculate all the unknown hyperparameters while an iterative coordinate descent algorithm is adopted to reconstruct the image with a voxel-based closed-form solution. Results of numerical simulations and mouse experiments show that the self-adaptive Bayesian method significantly improves the CB-XLCT image quality as compared with conventional methods.

  14. X-ray Computed Tomographic Investigation of the Porosity and Morphology of Plasma Electrolytic Oxidation Coatings.

    Science.gov (United States)

    Zhang, Xun; Aliasghari, Sepideh; Němcová, Aneta; Burnett, Timothy L; Kuběna, Ivo; Šmíd, Miroslav; Thompson, George E; Skeldon, Peter; Withers, Philip J

    2016-04-06

    Plasma electrolytic oxidation (PEO) is of increasing interest for the formation of ceramic coatings on metals for applications that require diverse coating properties, such as wear and corrosion resistance, low thermal conductivity, and biocompatibility. Porosity in the coatings can have an important impact on the coating performance. However, the quantification of the porosity in coatings can be difficult due to the wide range of pore sizes and the complexity of the coating morphology. In this work, a PEO coating formed on titanium is examined using high resolution X-ray computed tomography (X-ray CT). The observations are validated by comparisons of surface views and cross-sectional views of specific coating features obtained using X-ray CT and scanning electron microscopy. The X-ray CT technique is shown to be capable of resolving pores with volumes of at least 6 μm(3). Furthermore, the shapes of large pores are revealed and a correlation is demonstrated between the locations of the pores, nodules on the coating surface, and depressions in the titanium substrate. The locations and morphologies of the pores, which constitute 5.7% of the coating volume, indicate that they are generated by release of oxygen gas from the molten coating.

  15. Energy-discriminating X-ray computed tomography system utilizing a cadmium telluride detector

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Eiichi, E-mail: eiichisato@hotmail.co [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba 028-3694 (Japan); Abderyim, Purkhet [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba 028-3694 (Japan); Enomoto, Toshiyuki; Watanabe, Manabu [The 3rd Department of Surgery, Toho University School of Medicine, 2-17-6 Ohashi, Meguro-ku, Tokyo 153-8515 (Japan); Hitomi, Keitaro [Department of Electronics and Intelligent Systems, Tohoku Institute of Technology, 35-1 Yagiyama Kasumi-cho, Taihaku-ku, Sendai 982-8577 (Japan); Takahasi, Kiyomi; Sato, Shigehiro [Department of Microbiology, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka 020-8505 (Japan); Ogawae, Akira [Department of Neurosurgery, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka 020-8505 (Japan); Onagawa, Jun [Department of Electronics, Faculty of Engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo 985-8537 (Japan)

    2010-07-21

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type with a cadmium telluride (CdTe) detector, and a projection curve is obtained by translation scanning using the CdTe detector in conjunction with an x-stage. An object is rotated by the rotation step angle using a turntable between the translation scans. Thus, CT is carried out by repeating the translation scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a multi-channel analyzer, and the number of photons is counted by a counter card. Demonstration of enhanced iodine K-edge X-ray CT was carried out by selecting photons with energies just beyond the iodine K-edge energy of 33.2 keV.

  16. Computer simulation tools for X-ray analysis scattering and diffraction methods

    CERN Document Server

    Morelhão, Sérgio Luiz

    2016-01-01

    The main goal of this book is to break down the huge barrier of difficulties faced by beginners from many fields (Engineering, Physics, Chemistry, Biology, Medicine, Material Science, etc.) in using X-rays as an analytical tool in their research. Besides fundamental concepts, MatLab routines are provided, showing how to test and implement the concepts. The major difficult in analyzing materials by X-ray techniques is that it strongly depends on simulation software. This book teaches the users on how to construct a library of routines to simulate scattering and diffraction by almost any kind of samples. It provides to a young student the knowledge that would take more than 20 years to acquire by working on X-rays and relying on the available textbooks. In this book, fundamental concepts in applied X-ray physics are demonstrated through available computer simulation tools. Using MatLab, more than eighty routines are developed for solving the proposed exercises, most of which can be directly used in experimental...

  17. A hyperspectral X-ray computed tomography system for enhanced material identification

    Science.gov (United States)

    Wu, Xiaomei; Wang, Qian; Ma, Jinlei; Zhang, Wei; Li, Po; Fang, Zheng

    2017-08-01

    X-ray computed tomography (CT) can distinguish different materials according to their absorption characteristics. The hyperspectral X-ray CT (HXCT) system proposed in the present work reconstructs each voxel according to its X-ray absorption spectral characteristics. In contrast to a dual-energy or multi-energy CT system, HXCT employs cadmium telluride (CdTe) as the x-ray detector, which provides higher spectral resolution and separate spectral lines according to the material's photon-counter working principle. In this paper, a specimen containing ten different polymer materials randomly arranged was adopted for material identification by HXCT. The filtered back-projection algorithm was applied for image and spectral reconstruction. The first step was to sort the individual material components of the specimen according to their cross-sectional image intensity. The second step was to classify materials with similar intensities according to their reconstructed spectral characteristics. The results demonstrated the feasibility of the proposed material identification process and indicated that the proposed HXCT system has good prospects for a wide range of biomedical and industrial nondestructive testing applications.

  18. Porous Media Contamination: 3-Dimensional Visualization and Quantification Using X-Ray Computed Tomography

    Science.gov (United States)

    Goldstein, L.; Prasher, S. O.; Ghoshal, S.

    2004-05-01

    Non-aqueous phase liquids (NAPLs), if spilled into the subsurface, will migrate downward, and a significant fraction will become trapped in the soil matrix. These trapped NAPL globules partition into the water and/or vapor phase, and serve as continuous sources of contamination (e.g. source zones). At present, the presence of NAPL in the subsurface is typically inferred from chemical analysis data. There are no accepted methodologies or protocols available for the direct characterization of NAPLs in the subsurface. Proven and cost-effective methodologies are needed to allow effective implementation of remediation technologies at NAPL contaminated sites. X-ray Computed Tomography (CT) has the potential to non-destructively quantify NAPL mass and distribution in soil cores due to this technology's ability to detect small atomic density differences of solid, liquid, gas, and NAPL phases present in a representative volume element. We have demonstrated that environmentally significant NAPLs, such as gasoline and other oil products, chlorinated solvents, and PCBs possess a characteristic and predictable X-ray attenuation coefficient that permits their quantification in porous media at incident beam energies, typical of medical and industrial X-ray CT scanners. As part of this study, methodologies were developed for generating and analyzing X-ray CT data for the study of NAPLs in natural porous media. Columns of NAPL-contaminated soils were scanned, flushed with solvents and water to remove entrapped NAPL, and re-scanned. X-ray CT data was analyzed to obtain numerical arrays of soil porosity, NAPL saturation, and NAPL volume at a spatial resolution of 1 mm. This methodology was validated using homogeneous and heterogeneous soil columns with known quantities of gasoline and tetrachloroethylene. NAPL volumes computed using X-ray CT data was compared with known volumes from volume balance calculations. Error analysis revealed that in a 5 cm long and 2.5 cm diameter soil

  19. Analysis of reservoir properties based on X-ray computed tomography of sludge

    Science.gov (United States)

    Kadyrov, Rail

    2017-04-01

    Modern methods of oil fields developing require drilling with coring, but the cost of such operations is very high. In contrast, sludge drilling allows reducing the cost of the work more than two times. Core is used for the standard geological and technical research, especially it is important for definition of porosity and permeability. However, the same result can be achieved using X-ray computed tomography of sludge. In the course of the research, experiments on the comparison of porosity achieved by standard method of liquid saturation and X-Ray computed tomography in different resolutions were done. The best porosity representation scales depends on rock type and its minimal permeable for liquid pore size. It is shown that the porosity of the sample is due to matrix porosity generally. Another problem solved in the research was a destruction of strongly fractured, friable and fine lithotypes in a well and crumbling of drilled rocks. Statistical analysis of geometrical properties of porous space, such as multifractal parameters, allowed distinguishing the samples from different levels. The same pores are responsible for permeability in the investigated range 100-10 μm, regardless to the observation scale. Permeability was computed using digital 3D models and correlated with data obtained by water permeability testing system. Thus, the technology of reservoir properties analysis based on X-Ray computed tomography of sludge was developed.

  20. X-Ray Digital Radiography and Computed Tomography Characterization of Targets

    Energy Technology Data Exchange (ETDEWEB)

    Sain, J D; Brown, W D; Chinn, D J; Martz Jr., H E; Morales, K E; Schneberk, D J; Updike, E O

    2008-04-16

    The summary of this report is: (1) The Xradia Micro XCT and LLNL CCAT x-ray systems are used to nondestructively characterize a variety of materials, assemblies, and reference standard components; (2) The digital radiograph (DR) and computed tomography (CT) image data may be used for metrology, quality control, and defect detection; and (3) The ability to detect and characterize imperfections leads to improvements in the manufacturing processes for assemblies.

  1. Three dimensional analysis of coelacanth body structure by computer graphics and X-ray CT images

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Naoki (Jikei Univ., Tokyo (Japan). School of Medicine); Hamada, Takashi

    1990-06-01

    Three dimensional imaging processes were applied for the structural and functional analyses of the modern coelacanth (Latimeria chalumnae). Visualization of the obtained images is performed with computer graphics on the basis of serial images by an X-ray CT scanning method. Reconstruction of three dimensional images of the body structure of coelacanth using the volume rendering and surface rendering methods provides us various information about external and internal shapes of this exquisite fish. (author).

  2. Optimizing spatial resolution with the mechanical design of an X-ray computed tomography scanner

    Science.gov (United States)

    Harris, Lowell D.; Bernardi, Richard T.; Hughes, Simon H. C.; Slocum, Robert E.

    The most important factor limiting spatial resolution in a well-designed CT scanner - the width of the X-ray beam as it passes through the object being examined - is described. The Advanced Computed Tomography Inspection System (ACTIS), a second-generation CT scanner that has a variable geometry to allow a wide variety of objects to be scanned at peak spatial resolution, even with different radiation sources, is described.

  3. Utilisation of X-Ray computed microtomography for evaluation of iron sulphide distribution in roofing slate

    Science.gov (United States)

    Souček, Kamil; Daněk, Tomáš; Vavro, Martin; Botula, Jiří

    2016-04-01

    Roofing slate represents a traditional natural stone used for centuries for roofing and other construction applications in various types of buildings. Quality roofing slate must be primarily splittable into large, thin and waterproof tiles. In addition, it must be stable in colour and resistant against weathering. The abundance of mineral phases that weather easily or minerals that are long-term unstable has the effect of reducing the durability of slates in exterior conditions. One of the most problematic rock components, which are in a larger or smaller extent present in almost all slates, are iron sulphides, such as pyrite, marcasite or pyrrhotite. Under common atmospheric conditions, these minerals tend to oxidise, which leads to the formation of limonite and sulphuric acid. As a consequence of the origin of red-brown Fe oxyhydroxides, the undesirable colour changes of the slate may occur. But the most serious problem which occurs during this process is the changes in volume. This can cause disintegration of slate depending on the form of the iron sulphide occurrence. The content and size distribution of iron sulphides in roofing slate is normally determined using the microscopic analysis in transmitted light, combined with the observation in reflected light. For quantitative determination of iron sulphides in slate, the X-Ray powder diffraction is also often used. The results of the microscopic and X-Ray analyses need to be mutually compared and should not differ fundamentally. This paper is focused on the assessing the possibility of application of the X-Ray computed microtomography (CT) as a new complementary technique enabling the analysis of content and size (volume) distribution of iron sulphides in roofing slate. The X-Ray CT study was conducted using an XT H 225 ST industrial micro-tomographic system made by Nikon Metrology NV. Studied samples were reconstructed using the CT Pro 3D software (Nikon Metrology NV). The visualisation and analysis software

  4. Development of X-ray Emission Computed Tomography for Laser-Plasma.

    Science.gov (United States)

    Shao'En, Jiang; Zhongli, Liu; Nan, Li; Zhijian, Zheng; Dao'Yuan, Tang; Yongkun, Ding; Xin, Hu

    1996-11-01

    A computed tomography (CT) technique has been developed to diagnose laser produced plasma using X-ray emission. The three dimensional X-ray distribution was reconstructed by using a multiplicate algebraic reconstruction technique (MART) from five pinhole camera images obtained along different sight directions. A three dimensional reconstruction program (CT3D) has been worked out, the accuracy of which reaches 92% and 86%, without and with noise (S/N-10), respectively. The experimental data, obtained from the ICF on the ``Xinguang-II'' facilities (λ = 0.35 μm, EL = 100J, τ = 700ps), are processed by using the CT3D program and good reconstruction results have been obtained.

  5. A new solid-conversion gas detector for high energy X-ray industrial computed tomography

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ri-feng; CHEN Wei-min; DUAN Xiao-jiao

    2011-01-01

    A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography(H ECT).The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platform to simulate the transport process of photons and electrons in the detector.The simulation results show that the conversion efficiency could be more than 65%,if the X-ray beam width is less than about 0.2 mm,and a tungsten slab with 0.2 mum thickness and 30 mm length is employed as a radiation conversion medium.Meanwhile the results indicate that this new detector has higher conversion efficiency as well as less volume.Theoretically this new kind of detector could take place of the traditional scintillation detector for HECT.

  6. Quantification of Soil Pore Network Complexity with X-ray Computed Tomography and Gas Transport Measurements

    DEFF Research Database (Denmark)

    Katuwal, Sheela; Arthur, Emmanuel; Tuller, Markus

    2015-01-01

    Flow and transport of gases through soils are largely controlled by pore structural attributes. The quantification of pore network characteristics is therefore essential for accurate prediction of air permeability and gas diffusivity. In this study, the pore network characteristics of seven...... different soils subjected to 22 mo of field regeneration were quantified with X-ray computed tomography (CT) and compared with functional pore characteristics estimated from measurements of air permeability and gas diffusivity. Furthermore, predictive models for air permeability and gas diffusivity were...... equivalent pore diameter in predictive gas diffusivity and air permeability models significantly improved their performance. The obtained results suggest that the application of X-ray CT-derived pore-structural parameters has great potential for predicting gas diffusivity and air permeability....

  7. Computational Models of X-Ray Burst Quenching Times and 12C Nucleosynthesis Following a Superburst

    Energy Technology Data Exchange (ETDEWEB)

    Fisker, J L

    2009-03-19

    Superbursts are energetic events on neutron stars that are a thousand times more powerful than ordinary type I X-ray bursts. They are believed to be powered by a thermonuclear explosion of accumulated {sup 12}C. However, the source of this {sup 12}C remains elusive to theoretical calculations and its concentration and ignition depth are both unknown. Here we present the first computational simulations of the nucleosynthesis during the thermal decay of a superbust, where X-ray bursts are quenched. Our calculations of the quenching time verify previous analytical calculations and shed new light on the physics of stable burning at low accretion rates. We show that concentrated (X{sub {sup 12}C} {approx}> 0.40), although insufficient, amounts of {sup 12}C are generated during the several weeks following the superburst where the decaying thermal flux of the superburst stabilizes the burning of the accreted material.

  8. Heterogeneous computing for vertebra detection and segmentation in x-ray images.

    Science.gov (United States)

    Lecron, Fabian; Mahmoudi, Sidi Ahmed; Benjelloun, Mohammed; Mahmoudi, Saïd; Manneback, Pierre

    2011-01-01

    The context of this work is related to the vertebra segmentation. The method we propose is based on the active shape model (ASM). An original approach taking advantage of the edge polygonal approximation was developed to locate the vertebra positions in a X-ray image. Despite the fact that segmentation results show good efficiency, the time is a key variable that has always to be optimized in a medical context. Therefore, we present how vertebra extraction can efficiently be performed in exploiting the full computing power of parallel (GPU) and heterogeneous (multi-CPU/multi-GPU) architectures. We propose a parallel hybrid implementation of the most intensive steps enabling to boost performance. Experimentations have been conducted using a set of high-resolution X-ray medical images, showing a global speedup ranging from 3 to 22, by comparison with the CPU implementation. Data transfer times between CPU and GPU memories were included in the execution times of our proposed implementation.

  9. The CT Scanner Facility at Stellenbosch University: An open access X-ray computed tomography laboratory

    Science.gov (United States)

    du Plessis, Anton; le Roux, Stephan Gerhard; Guelpa, Anina

    2016-10-01

    The Stellenbosch University CT Scanner Facility is an open access laboratory providing non-destructive X-ray computed tomography (CT) and a high performance image analysis services as part of the Central Analytical Facilities (CAF) of the university. Based in Stellenbosch, South Africa, this facility offers open access to the general user community, including local researchers, companies and also remote users (both local and international, via sample shipment and data transfer). The laboratory hosts two CT instruments, i.e. a micro-CT system, as well as a nano-CT system. A workstation-based Image Analysis Centre is equipped with numerous computers with data analysis software packages, which are to the disposal of the facility users, along with expert supervision, if required. All research disciplines are accommodated at the X-ray CT laboratory, provided that non-destructive analysis will be beneficial. During its first four years, the facility has accommodated more than 400 unique users (33 in 2012; 86 in 2013; 154 in 2014; 140 in 2015; 75 in first half of 2016), with diverse industrial and research applications using X-ray CT as means. This paper summarises the existence of the laboratory's first four years by way of selected examples, both from published and unpublished projects. In the process a detailed description of the capabilities and facilities available to users is presented.

  10. The CT Scanner Facility at Stellenbosch University: An open access X-ray computed tomography laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Plessis, Anton du, E-mail: anton2@sun.ac.za [CT Scanner Facility, Central Analytical Facilities, Stellenbosch University, Stellenbosch (South Africa); Physics Department, Stellenbosch University, Stellenbosch (South Africa); Roux, Stephan Gerhard le, E-mail: lerouxsg@sun.ac.za [CT Scanner Facility, Central Analytical Facilities, Stellenbosch University, Stellenbosch (South Africa); Guelpa, Anina, E-mail: aninag@sun.ac.za [CT Scanner Facility, Central Analytical Facilities, Stellenbosch University, Stellenbosch (South Africa)

    2016-10-01

    The Stellenbosch University CT Scanner Facility is an open access laboratory providing non-destructive X-ray computed tomography (CT) and a high performance image analysis services as part of the Central Analytical Facilities (CAF) of the university. Based in Stellenbosch, South Africa, this facility offers open access to the general user community, including local researchers, companies and also remote users (both local and international, via sample shipment and data transfer). The laboratory hosts two CT instruments, i.e. a micro-CT system, as well as a nano-CT system. A workstation-based Image Analysis Centre is equipped with numerous computers with data analysis software packages, which are to the disposal of the facility users, along with expert supervision, if required. All research disciplines are accommodated at the X-ray CT laboratory, provided that non-destructive analysis will be beneficial. During its first four years, the facility has accommodated more than 400 unique users (33 in 2012; 86 in 2013; 154 in 2014; 140 in 2015; 75 in first half of 2016), with diverse industrial and research applications using X-ray CT as means. This paper summarises the existence of the laboratory’s first four years by way of selected examples, both from published and unpublished projects. In the process a detailed description of the capabilities and facilities available to users is presented.

  11. High-resolution x-ray computed tomography to understand ruminant phylogeny

    Science.gov (United States)

    Costeur, Loic; Schulz, Georg; Müller, Bert

    2014-09-01

    High-resolution X-ray computed tomography has become a vital technique to study fossils down to the true micrometer level. Paleontological research requires the non-destructive analysis of internal structures of fossil specimens. We show how X-ray computed tomography enables us to visualize the inner ear of extinct and extant ruminants without skull destruction. The inner ear, a sensory organ for hearing and balance has a rather complex three-dimensional morphology and thus provides relevant phylogenetical information what has been to date essentially shown in primates. We made visible the inner ears of a set of living and fossil ruminants using the phoenix x-ray nanotom®m (GE Sensing and Inspection Technologies GmbH). Because of the high absorbing objects a tungsten target was used and the experiments were performed with maximum accelerating voltage of 180 kV and a beam current of 30 μA. Possible stem ruminants of the living families are known in the fossil record but extreme morphological convergences in external structures such as teeth is a strong limitation to our understanding of the evolutionary history of this economically important group of animals. We thus investigate the inner ear to assess its phylogenetical potential for ruminants and our first results show strong family-level morphological differences.

  12. An automated system for lung nodule detection in low-dose computed tomography

    CERN Document Server

    Gori, I; Martinez, A Preite; Retico, A

    2007-01-01

    A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector helical Computed Tomography (CT) images was developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, a dot-enhancement filter for nodule candidate selection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The results obtained on the collected database of low-dose thin-slice CT scans are shown in terms of free response receiver operating characteristic (FROC) curves and discussed.

  13. Validation of a low dose simulation technique for computed tomography images.

    Directory of Open Access Journals (Sweden)

    Daniela Muenzel

    Full Text Available PURPOSE: Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT images from an original higher dose scan. MATERIALS AND METHODS: Original CT scan data (100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, 10 mAs; 100 kV of a swine were acquired (approved by the regional governmental commission for animal protection. Simulations of CT acquisition with a lower dose (simulated 10-80 mAs were calculated using a low-dose simulation algorithm. The simulations were compared to the originals of the same dose level with regard to density values and image noise. Four radiologists assessed the realistic visual appearance of the simulated images. RESULTS: Image characteristics of simulated low dose scans were similar to the originals. Mean overall discrepancy of image noise and CT values was -1.2% (range -9% to 3.2% and -0.2% (range -8.2% to 3.2%, respectively, p>0.05. Confidence intervals of discrepancies ranged between 0.9-10.2 HU (noise and 1.9-13.4 HU (CT values, without significant differences (p>0.05. Subjective observer evaluation of image appearance showed no visually detectable difference. CONCLUSION: Simulated low dose images showed excellent agreement with the originals concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques.

  14. Computational time-resolved and resonant x-ray scattering of strongly correlated materials

    Energy Technology Data Exchange (ETDEWEB)

    Bansil, Arun [Northeastern Univ., Boston, MA (United States)

    2016-11-09

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source, literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspects of this grand challenge of x-ray science. In particular, our Collaborative Research Team (CRT) focused on developing viable computational schemes for modeling x-ray scattering and photoemission spectra of strongly correlated materials in the time-domain. The vast arsenal of formal/numerical techniques and approaches encompassed by the members of our CRT were brought to bear through appropriate generalizations and extensions to model the pumped state and the dynamics of this non-equilibrium state, and how it can be probed via x-ray absorption (XAS), emission (XES), resonant and non-resonant x-ray scattering, and photoemission processes. We explored the conceptual connections between the time-domain problems and other second-order spectroscopies, such as resonant inelastic x-ray scattering (RIXS) because RIXS may be effectively thought of as a pump-probe experiment in which the incoming photon acts as the pump, and the fluorescent decay is the probe. Alternatively, when the core-valence interactions are strong, one can view K-edge RIXS for example, as the dynamic response of the material to the transient presence of a strong core-hole potential. Unlike an actual pump-probe experiment, here there is no mechanism for adjusting the time-delay between the pump and the probe. However, the core hole

  15. Patient size and x-ray technique factors in head computed tomography examinations. I. Radiation doses.

    Science.gov (United States)

    Huda, Walter; Lieberman, Kristin A; Chang, Jack; Roskopf, Marsha L

    2004-03-01

    We investigated how patient age, size and composition, together with the choice of x-ray technique factors, affect radiation doses in head computed tomography (CT) examinations. Head size dimensions, cross-sectional areas, and mean Hounsfield unit (HU) values were obtained from head CT images of 127 patients. For radiation dosimetry purposes patients were modeled as uniform cylinders of water. Dose computations were performed for 18 x 7 mm sections, scanned at a constant 340 mAs, for x-ray tube voltages ranging from 80 to 140 kV. Values of mean section dose, energy imparted, and effective dose were computed for patients ranging from the newborn to adults. There was a rapid growth of head size over the first two years, followed by a more modest increase of head size until the age of 18 or so. Newborns have a mean HU value of about 50 that monotonically increases with age over the first two decades of life. Average adult A-P and lateral dimensions were 186+/-8 mm and 147+/-8 mm, respectively, with an average HU value of 209+/-40. An infant head was found to be equivalent to a water cylinder with a radius of approximately 60 mm, whereas an adult head had an equivalent radius 50% greater. Adult males head dimensions are about 5% larger than for females, and their average x-ray attenuation is approximately 20 HU greater. For adult examinations performed at 120 kV, typical values were 32 mGy for the mean section dose, 105 mJ for the total energy imparted, and 0.64 mSv for the effective dose. Increasing the x-ray tube voltage from 80 to 140 kV increases patient doses by about a factor of 5. For the same technique factors, mean section doses in infants are 35% higher than in adults. Energy imparted for adults is 50% higher than for infants, but infant effective doses are four times higher than for adults. CT doses need to take into account patient age, head size, and composition as well as the selected x-ray technique factors.

  16. Ptychographic X-ray computed tomography of extended colloidal networks in food emulsions

    DEFF Research Database (Denmark)

    Schou Nielsen, Mikkel; Bøgelund Munk, Merete; Diaz, Ana

    2016-01-01

    of suitable non-destructive 3D imaging techniques with submicron resolution. We present results of quantitative ptychographic X-ray computed tomography applied to a palm kernel oil based oil-in-water emulsion. The measurements were carried out at ambient pressure and temperature. The 3D structure...... of the extended colloidal network of fat globules was obtained with a resolution of around 300 nm. Through image analysis of the network structure, the fat globule size distribution was computed and compared to previous findings. In further support, the reconstructed electron density values were within 4...

  17. Contribute to quantitative identification of casting defects based on computer analysis of X-ray images

    Directory of Open Access Journals (Sweden)

    Z. Ignaszak

    2007-12-01

    Full Text Available The forecast of structure and properties of casting is based on results of computer simulation of physical processes which are carried out during the casting processes. For the effective using of simulation system it is necessary to validate mathematica-physical models describing process of casting formation and the creation of local discontinues, witch determinate the casting properties.In the paper the proposition for quantitative validation of VP system using solidification casting defects by information sources of II group (methods of NDT was introduced. It was named the VP/RT validation (virtual prototyping/radiographic testing validation. Nowadays identification of casting defects noticeable on X-ray images bases on comparison of X-ray image of casting with relates to the ASTM. The results of this comparison are often not conclusive because based on operator’s subjective assessment. In the paper the system of quantitative identification of iron casting defects on X-ray images and classification this defects to ASTM class is presented. The methods of pattern recognition and machine learning were applied.

  18. Reverse projection retrieval in edge illumination x-ray phase contrast computed tomography

    Science.gov (United States)

    Hagen, Charlotte K.; Endrizzi, Marco; Diemoz, Paul C.; Olivo, Alessandro

    2016-06-01

    Edge illumination (EI) x-ray phase contrast computed tomography (CT) can provide three-dimensional distributions of the real and imaginary parts of the complex refractive index (n=1-δ +\\text{i}β ) of the sample. Phase retrieval, i.e. the separation of attenuation and refraction data from projections that contain a combination of both, is a key step in the image reconstruction process. In EI-based x-ray phase contrast CT, this is conventionally performed on the basis of two projections acquired in opposite illumination configurations (i.e. with different positions of the pre-sample mask) at each CT angle. Displacing the pre-sample mask at each projection makes the scan susceptible to motor-induced misalignment and prevents a continuous sample rotation. We present an alternative method for the retrieval of attenuation and refraction data that does not require repositioning the pre-sample mask. The method is based on the reverse projection relation published by Zhu et al (2010 Proc. Natl Acad. Sci. USA 107 13576-81) for grating interferometry-based x-ray phase contrast CT. We use this relation to derive a simplified acquisition strategy that allows acquiring data with a continuous sample rotation, which can reduce scan time when combined with a fast read-out detector. Besides discussing the theory and the necessary alignment of the experimental setup, we present tomograms obtained with reverse projection retrieval and demonstrate their agreement with those obtained with the conventional EI retrieval.

  19. 3D printing of preclinical X-ray computed tomographic data sets.

    Science.gov (United States)

    Doney, Evan; Krumdick, Lauren A; Diener, Justin M; Wathen, Connor A; Chapman, Sarah E; Stamile, Brian; Scott, Jeremiah E; Ravosa, Matthew J; Van Avermaete, Tony; Leevy, W Matthew

    2013-03-22

    Three-dimensional printing allows for the production of highly detailed objects through a process known as additive manufacturing. Traditional, mold-injection methods to create models or parts have several limitations, the most important of which is a difficulty in making highly complex products in a timely, cost-effective manner.(1) However, gradual improvements in three-dimensional printing technology have resulted in both high-end and economy instruments that are now available for the facile production of customized models.(2) These printers have the ability to extrude high-resolution objects with enough detail to accurately represent in vivo images generated from a preclinical X-ray CT scanner. With proper data collection, surface rendering, and stereolithographic editing, it is now possible and inexpensive to rapidly produce detailed skeletal and soft tissue structures from X-ray CT data. Even in the early stages of development, the anatomical models produced by three-dimensional printing appeal to both educators and researchers who can utilize the technology to improve visualization proficiency. (3, 4) The real benefits of this method result from the tangible experience a researcher can have with data that cannot be adequately conveyed through a computer screen. The translation of pre-clinical 3D data to a physical object that is an exact copy of the test subject is a powerful tool for visualization and communication, especially for relating imaging research to students, or those in other fields. Here, we provide a detailed method for printing plastic models of bone and organ structures derived from X-ray CT scans utilizing an Albira X-ray CT system in conjunction with PMOD, ImageJ, Meshlab, Netfabb, and ReplicatorG software packages.

  20. Identifying unknown minerals and compounds from X-ray diffraction patterns using the Johnson and Vand FORTRAN 4 computer program

    Science.gov (United States)

    Kyte, F. T.

    1976-01-01

    Automated computer identification of minerals and compounds from unknown samples is provided along with detailed instructions and worked examples for use in graduate level courses in mineralogy and X-ray analysis applications.

  1. Data Acquisition, Control, Communication and Computation System of Solar X-ray Spectrometer (SOXS) Mission

    Indian Academy of Sciences (India)

    Amish B. Shah; N. M. Vadher; Rajmal Jain; Hemant Dave; Vishal Shah; K. S. B. Manian; Satish Kayasth; Vinod Patel; Girish Ubale; Kirit Shah; Chirag Solanki; M. R. Deshpande; Ramkrishna Sharma; C. N. Umapathy; N. Viswanath; Ravi Kulkarni; P. S. Kumar

    2006-06-01

    The Solar X-ray Spectrometer (SOXS) mission onboard GSAT-2 Indian Spacecraft was launched on 08 May 2003 using GSLV–D2 rocket by Indian Space Research Organization (ISRO). SOXS aims to study solar flares, which are the most violent and energetic phenomena in the solar system, in the energy range of 4–56 keV with high spectral and temporal resolution. SOXS employs state-of-the-art semiconductor devices, viz., Si-Pin and CZT detectors to achieve sub-keV energy resolution requirements. In this paper, we present an overview of data acquisition, control, communication and computation of low energy payload of the SOXS mission.

  2. Inside marginal adaptation of crowns by X-ray micro-computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Dos Santos, T. M.; Lima, I.; Lopes, R. T. [Nuclear Instrumentation Laboratory, Nuclear Engineering Program, Federal University of Rio de Janeiro, RJ, (Brazil); Author, S. B. Jr. [Department of Physics, Colorado State University, Ft. Collins, CO 80523, (United States)

    2015-07-01

    The objective of this work was to access dental arcade by using X-ray micro-computed tomography. For this purpose high resolution system was used and three groups were studied: Zirkonzahn CAD-CAM system, IPS e.max Press, and metal ceramic. The three systems assessed in this study showed results of marginal and discrepancy gaps clinically accepted. The great result of 2D and 3D evaluations showed that the used technique is a powerful method to investigate quantitative characteristics of dental arcade. (authors)

  3. Improvement of Image Quality in Transmission Computed Tomography Using Synchrotron Monochromatic X-Ray Sheet Beam

    Science.gov (United States)

    2001-10-25

    7] T. Takeda, M. Kazama, T. Zeniya, T. Yuasa, M. Akiba, A. Uchida, K. Hyodo, T. Akatsuka, M. Ando, and Y. Itai , “Development of a Mono- chromatic X...Uyama (Springer-Verlag, Tokyo), pp. 103-110 (1998). [8] Y. Itai , T. Takeda, T. Akatsuka, T. Maeda, K. Hyodo, A. Uchida, T. Yuasa, M. Kazama, J. Wu...T. Yuasa, K. Hyodo, M. Ando, T. Akatsuka, and Y. Itai , “Performance Study of Monochromatic Synchro- tron X-ray Computed Tomography using a Linear

  4. Computer-aided diagnosis of pulmonary diseases using x-ray darkfield radiography

    DEFF Research Database (Denmark)

    Einarsdottir, Hildur; Yaroshenko, Andre; Velroyen, Astrid;

    2015-01-01

    In this work we develop a computer-aided diagnosis (CAD) scheme for classification of pulmonary disease for grating-based x-ray radiography. In addition to conventional transmission radiography, the grating-based technique provides a dark-field imaging modality, which utilizes the scattering...... of three stages: (i) automatic lung segmentation; (ii) feature extraction from lung shape and dark-field image intensities; (iii) classification between healthy, emphysema and fibrosis lungs. A study of 102 mice was conducted with 34 healthy, 52 emphysema and 16 fibrosis subjects. Each image was manually...

  5. The Effect of Experimental Variables on Industrial X-Ray Micro-Computed Sensitivity

    Science.gov (United States)

    Roth, Don J.; Rauser, Richard W.

    2014-01-01

    A study was performed on the effect of experimental variables on radiographic sensitivity (image quality) in x-ray micro-computed tomography images for a high density thin wall metallic cylinder containing micro-EDM holes. Image quality was evaluated in terms of signal-to-noise ratio, flaw detectability, and feature sharpness. The variables included: day-to-day reproducibility, current, integration time, voltage, filtering, number of frame averages, number of projection views, beam width, effective object radius, binning, orientation of sample, acquisition angle range (180deg to 360deg), and directional versus transmission tube.

  6. Three dimensional image correlation from X-Ray computed tomography of solid foam

    CERN Document Server

    Roux, Stephane; Viot, Philippe; Bernard, Dominique

    2007-01-01

    A new methodology is proposed to estimate 3D displacement fields from pairs of images obtained from X-Ray Computed Micro Tomography (XCMT). Contrary to local approaches, a global approach is followed herein that evaluates {\\em continuous} displacement fields. Although any displacement basis could be considered, the procedure is specialized to finite element shape functions. The method is illustrated with the analysis of a compression test on a polypropylene solid foam (independently studied in a companion paper). A good stability of the measured displacement field is obtained for cubic element sizes ranging from 16 voxels to 6 voxels.

  7. Assessment of asthmatic inflammation using hybrid fluorescence molecular tomography-x-ray computed tomography

    Science.gov (United States)

    Ma, Xiaopeng; Prakash, Jaya; Ruscitti, Francesca; Glasl, Sarah; Stellari, Fabio Franco; Villetti, Gino; Ntziachristos, Vasilis

    2016-01-01

    Nuclear imaging plays a critical role in asthma research but is limited in its readings of biology due to the short-lived signals of radio-isotopes. We employed hybrid fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) for the assessment of asthmatic inflammation based on resolving cathepsin activity and matrix metalloproteinase activity in dust mite, ragweed, and Aspergillus species-challenged mice. The reconstructed multimodal fluorescence distribution showed good correspondence with ex vivo cryosection images and histological images, confirming FMT-XCT as an interesting alternative for asthma research.

  8. Effects of low dose of X-ray radiation on the actin cytoskeleton of osteoblasts%低剂量X线照射对成骨细胞纤维肌动蛋白的影响

    Institute of Scientific and Technical Information of China (English)

    黄群; 董启榕; 陈明; 徐炜; 王创利; 史高龙

    2015-01-01

    Objective To observe the effects of different doses of X-ray irradiation on the morphology,mierostructure changes and actin cytoskeleton of osteoblasts.The findings of this research will provide evidence for further study of low dose X-ray irradiation biological effects.Methods MC3T3-E1 cells were exposed to irradiation of 0.5,5.0 Gy.We investigated cellular morphological changes by phase contrast microscope and transmission electron microscopy.The organization of actin microfilaments was determined by immunofluorescence.Results After 2 h exposure to irradiation,the F-actin fluorescence intensity of ceils in 0.5,5.0 Gy group were significantly lower than non-irradiated group (25.329 ± 12.209,27.021 ± 13.049 vs.29.107 ± 13.296,P < 0.05).But 24 hours later,the fluorescence intensity of F-actin in 0.5,5.0 Gy group increased gradually and the fiber stress also increased.The most significant changes appeared in the third day after X-ray irrddiation (38.687 ± 18.072,36.039 ± 12.128 vs.35.645 ± 17.213).However,these changes gradually returned to normal in the fifth day,close to 0 Gy group (28.527 ±14.107,27.258 ±13.322 vs.27.309±15.039).Conclusion Thecytoskeleton of MC3TE-E cells were destroyed after 2 hours,exposure to X-ray irradiation.Howerver,0.5,5.0 Gy X-ray irradiation induced reorganization of actin filaments of MC3T3 cells 1 d later.%目的 观察不同剂量X线照射成骨细胞后,细胞形态、胞内微结构及纤维肌动蛋白的变化.方法 采用医用直线加速器以0、0.5、5.0Gy作用成骨细胞(MC3T3-E1)后,用倒置相差显微镜观察细胞形态变化,透射电镜观察细胞内微结构变化以及异硫酸氢荧光素-鬼笔环肽(FITC-phalloidin)对各实验组细胞的纤维肌动蛋白(F-actin)进行染色,荧光显微镜下观察各实验组F-actin细胞骨架的变化.结果 X线照射后2h,0.5、5.0Gy组细胞F-actin绿色荧光强度明显低于未照射组(25.329±12.209、27.021±13.049比29.107±13.296),

  9. Computer-aided detection of early interstitial lung diseases using low-dose CT images

    Science.gov (United States)

    Park, Sang Cheol; Tan, Jun; Wang, Xingwei; Lederman, Dror; Leader, Joseph K.; Kim, Soo Hyung; Zheng, Bin

    2011-02-01

    This study aims to develop a new computer-aided detection (CAD) scheme to detect early interstitial lung disease (ILD) using low-dose computed tomography (CT) examinations. The CAD scheme classifies each pixel depicted on the segmented lung areas into positive or negative groups for ILD using a mesh-grid-based region growth method and a multi-feature-based artificial neural network (ANN). A genetic algorithm was applied to select optimal image features and the ANN structure. In testing each CT examination, only pixels selected by the mesh-grid region growth method were analyzed and classified by the ANN to improve computational efficiency. All unselected pixels were classified as negative for ILD. After classifying all pixels into the positive and negative groups, CAD computed a detection score based on the ratio of the number of positive pixels to all pixels in the segmented lung areas, which indicates the likelihood of the test case being positive for ILD. When applying to an independent testing dataset of 15 positive and 15 negative cases, the CAD scheme yielded the area under receiver operating characteristic curve (AUC = 0.884 ± 0.064) and 80.0% sensitivity at 85.7% specificity. The results demonstrated the feasibility of applying the CAD scheme to automatically detect early ILD using low-dose CT examinations.

  10. Computer-aided detection of early interstitial lung diseases using low-dose CT images

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Cheol; Kim, Soo Hyung [School of Electronics and Computer Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Tan, Jun; Wang Xingwei; Lederman, Dror; Leader, Joseph K; Zheng Bin, E-mail: zhengb@upmc.edu [Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15213 (United States)

    2011-02-21

    This study aims to develop a new computer-aided detection (CAD) scheme to detect early interstitial lung disease (ILD) using low-dose computed tomography (CT) examinations. The CAD scheme classifies each pixel depicted on the segmented lung areas into positive or negative groups for ILD using a mesh-grid-based region growth method and a multi-feature-based artificial neural network (ANN). A genetic algorithm was applied to select optimal image features and the ANN structure. In testing each CT examination, only pixels selected by the mesh-grid region growth method were analyzed and classified by the ANN to improve computational efficiency. All unselected pixels were classified as negative for ILD. After classifying all pixels into the positive and negative groups, CAD computed a detection score based on the ratio of the number of positive pixels to all pixels in the segmented lung areas, which indicates the likelihood of the test case being positive for ILD. When applying to an independent testing dataset of 15 positive and 15 negative cases, the CAD scheme yielded the area under receiver operating characteristic curve (AUC = 0.884 {+-} 0.064) and 80.0% sensitivity at 85.7% specificity. The results demonstrated the feasibility of applying the CAD scheme to automatically detect early ILD using low-dose CT examinations.

  11. Effect of oblique X-ray incidence in flat-panel computed tomography of the breast.

    Science.gov (United States)

    Badano, Aldo; Kyprianou, Iacovos S; Freed, Melanie; Jennings, Robert J; Sempau, Josep

    2009-05-01

    We quantify the variation in resolution due to anisotropy caused by oblique X-ray incidence in indirect flat-panel detectors for computed tomography breast imaging systems. We consider a geometry and detector type utilized in breast computed tomography (CT) systems currently being developed. Our methods rely on mantis, a combined X-ray, electron, and optical Monte Carlo transport open source code. The physics models are the most accurate available in general-purpose Monte Carlo packages in the diagnostic energy range. We consider maximum-obliquity angles of 10 ( degrees ) and 13 ( degrees ) at the centers of the 30 and 40 cm detector edges, respectively, and 16 ( degrees ) at the corner of the detector. Our results indicate that blur is asymmetric and that the resolution properties vary significantly with the angle (or location) of incidence. Our results suggest that the asymmetry can be as high as a factor of 2.6 between orthogonal directions. Anisotropy maps predicted by mantis provide an understanding of the effect that such variations have on the imaging system and allow more accurate modeling and optimization of breast CT systems. These maps of anisotropy across the detector could lead to improved reconstruction and help motivate physics-based strategies for computer detection of breast lesions.

  12. X-Ray Computed Tomography Inspection of the Stardust Heat Shield

    Science.gov (United States)

    McNamara, Karen M.; Schneberk, Daniel J.; Empey, Daniel M.; Koshti, Ajay; Pugel, D. Elizabeth; Cozmuta, Ioana; Stackpoole, Mairead; Ruffino, Norman P.; Pompa, Eddie C.; Oliveras, Ovidio; hide

    2010-01-01

    The "Stardust" heat shield, composed of a PICA (Phenolic Impregnated Carbon Ablator) Thermal Protection System (TPS), bonded to a composite aeroshell, contains important features which chronicle its time in space as well as re-entry. To guide the further study of the Stardust heat shield, NASA reviewed a number of techniques for inspection of the article. The goals of the inspection were: 1) to establish the material characteristics of the shield and shield components, 2) record the dimensions of shield components and assembly as compared with the pre-flight condition, 3) provide flight infonnation for validation and verification of the FIAT ablation code and PICA material property model and 4) through the evaluation of the shield material provide input to future missions which employ similar materials. Industrial X-Ray Computed Tomography (CT) is a 3D inspection technology which can provide infonnation on material integrity, material properties (density) and dimensional measurements of the heat shield components. Computed tomographic volumetric inspections can generate a dimensionally correct, quantitatively accurate volume of the shield assembly. Because of the capabilities offered by X-ray CT, NASA chose to use this method to evaluate the Stardust heat shield. Personnel at NASA Johnson Space Center (JSC) and Lawrence Livermore National Labs (LLNL) recently performed a full scan of the Stardust heat shield using a newly installed X-ray CT system at JSC. This paper briefly discusses the technology used and then presents the following results: 1. CT scans derived dimensions and their comparisons with as-built dimensions anchored with data obtained from samples cut from the heat shield; 2. Measured density variation, char layer thickness, recession and bond line (the adhesive layer between the PICA and the aeroshell) integrity; 3. FIAT predicted recession, density and char layer profiles as well as bondline temperatures Finally suggestions are made as to future uses

  13. The quantum X-ray radiology apparatus

    CERN Document Server

    Hilt, B; Prevot, G

    2000-01-01

    The paper entitled 'New Quantum Detection System for Very Low Dose X-ray Radiology', presented at the talk session, discusses the preliminary data obtained using a new quantum X-ray radiology system with a high-efficiency solid-state detector and highly sensitive electronics, making it possible to reduce significantly the dose administered to a patient in X-ray radiology examinations. The present paper focuses more on the technological aspects of the apparatus, such as the integration of the detector with the two Asics, and the computer system. Namely, it is shown how the computer system calibrates the detection system, acquires the data in real time, and controls the scan parameters and image filtering process.

  14. Photoelectronic radiology 1983; X-ray imaging with the computer-assisted technologies

    Science.gov (United States)

    Chalaqui, Jean; Sylvestre, Jacques; Robillard, Pierre; Dussault, Robert

    The development of the discipline of radiology has continued to progress from initial images depicting the structure of organs, to the exploration of dynamic and physiologic phenomena, improvements in the power of X-ray generators and with the refinement of non-toxic contrast media. Until the early part of the 1970s, radiology consisted in extrapolations from a two-dimensional image of a three-dimensional organ, and advances in diagnostic quality related chiefly to improvements in spatial resolution of the flat image. With the advent of cross-sectional imaging using computer reconstruction the emphasis has shifted to contrast resolution, to the acquisition of "pure" images in the XY plane and to an area-related approach in diagnosis, rather than to the traditional organ-oriented method. This new trend has only been made possible because of the influence of recent developments in the digital and electronics industry. This history of diagnostic radiology up to 1972 is reviewed, followed by a discussion of the major areas of interaction between X-rays and the computer, as represented by the major leading edge technologies that have already received broad acceptance by the health care profession.

  15. An investigation of low-dose 3D scout scans for computed tomography

    Science.gov (United States)

    Gomes, Juliana; Gang, Grace J.; Mathews, Aswin; Stayman, J. Webster

    2017-03-01

    Purpose: Commonly 2D scouts or topograms are used prior to CT scan acquisition. However, low-dose 3D scouts could potentially provide additional information for more effective patient positioning and selection of acquisition protocols. We propose using model-based iterative reconstruction to reconstruct low exposure tomographic data to maintain image quality in both low-dose 3D scouts and reprojected topograms based on those 3D scouts. Methods: We performed tomographic acquisitions on a CBCT test-bench using a range of exposure settings from 16.6 to 231.9 total mAs. Both an anthropomorphic phantom and a 32 cm CTDI phantom were scanned. The penalized-likelihood reconstructions were made using Matlab and CUDA libraries and reconstruction parameters were tuned to determine the best regularization strength and delta parameter. RMS error between reconstructions and the highest exposure reconstruction were computed, and CTDIW values were reported for each exposure setting. RMS error for reprojected topograms were also computed. Results: We find that we are able to produce low-dose (0.417 mGy) 3D scouts that show high-contrast and large anatomical features while maintaining the ability to produce traditional topograms. Conclusions: We demonstrated that iterative reconstruction can mitigate noise in very low exposure CT acquisitions to enable 3D CT scout. Such additional 3D information may lead to improved protocols for patient positioning and acquisition refinements as well as a number of advanced dose reduction strategies that require localization of anatomical features and quantities that are not provided by simple 2D topograms.

  16. Clogging evaluation of porous asphalt concrete cores in conjunction with medical x-ray computed tomography

    Science.gov (United States)

    Su, Yu-Min; Hsu, Chen-Yu; Lin, Jyh-Dong

    2014-03-01

    This study was to assess the porosity of Porous Asphalt Concrete (PAC) in conjunction with a medical X-ray computed tomography (CT) facility. The PAC was designed as the surface course to achieve the target porosity 18%. There were graded aggregates, soils blended with 50% of coarse sand, and crushed gravel wrapped with geotextile compacted and served as the base, subbase, and infiltration layers underneath the PAC. The test site constructed in 2004 is located in Northern of Taiwan in which the daily traffic has been light and limited. The porosity of the test track was investigated. The permeability coefficient of PAC was found severely degraded from 2.2×10-1 to 1.2×10-3 -cm/sec, after nine-year service, while the permeability below the surface course remained intact. Several field PAC cores were drilled and brought to evaluate the distribution of air voids by a medical X-ray CT nondestructively. The helical mode was set to administrate the X-ray CT scan and two cross-sectional virtual slices were exported in seconds for analyzing air voids distribution. It shows that the clogging of voids occurred merely 20mm below the surface and the porosity can reduce as much about 3%. It was also found that the roller compaction can decrease the porosity by 4%. The permeability reduction in this test site can attribute to the voids of PAC that were compacted by roller during the construction and filled by the dusts on the surface during the service.

  17. Computer simulation of the CSPAD, ePix10k, and RayonixMX170HS X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tina, Adrienne

    2015-08-21

    The invention of free-electron lasers (FELs) has opened a door to an entirely new level of scientific research. The Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory is an X-ray FEL that houses several instruments, each with its own unique X-ray applications. This light source is revolutionary in that while its properties allow for a whole new range of scientific opportunities, it also poses numerous challenges. For example, the intensity of a focused X-ray beam is enough to damage a sample in one mere pulse; however, the pulse speed and extreme brightness of the source together are enough to obtain enough information about that sample, so that no further measurements are necessary. An important device in the radiation detection process, particularly for X-ray imaging, is the detector. The power of the LCLS X-rays has instigated a need for better performing detectors. The research conducted for this project consisted of the study of X-ray detectors to imitate their behaviors in a computer program. The analysis of the Rayonix MX170-HS, CSPAD, and ePix10k in particular helped to understand their properties. This program simulated the interaction of X-ray photons with these detectors to discern the patterns of their responses. A scientist’s selection process of a detector for a specific experiment is simplified from the characterization of the detectors in the program.

  18. HIGH-PERFORMANCE COMPUTING FOR THE STUDY OF EARTH AND ENVIRONMENTAL SCIENCE MATERIALS USING SYNCHROTRON X-RAY COMPUTED MICROTOMOGRAPHY.

    Energy Technology Data Exchange (ETDEWEB)

    FENG,H.; JONES,K.W.; MCGUIGAN,M.; SMITH,G.J.; SPILETIC,J.

    2001-10-12

    Synchrotron x-ray computed microtomography (CMT) is a non-destructive method for examination of rock, soil, and other types of samples studied in the earth and environmental sciences. The high x-ray intensities of the synchrotron source make possible the acquisition of tomographic volumes at a high rate that requires the application of high-performance computing techniques for data reconstruction to produce the three-dimensional volumes, for their visualization, and for data analysis. These problems are exacerbated by the need to share information between collaborators at widely separated locations over both local and tide-area networks. A summary of the CMT technique and examples of applications are given here together with a discussion of the applications of high-performance computing methods to improve the experimental techniques and analysis of the data.

  19. Low-dose computed tomography image denoising based on joint wavelet and sparse representation.

    Science.gov (United States)

    Ghadrdan, Samira; Alirezaie, Javad; Dillenseger, Jean-Louis; Babyn, Paul

    2014-01-01

    Image denoising and signal enhancement are the most challenging issues in low dose computed tomography (CT) imaging. Sparse representational methods have shown initial promise for these applications. In this work we present a wavelet based sparse representation denoising technique utilizing dictionary learning and clustering. By using wavelets we extract the most suitable features in the images to obtain accurate dictionary atoms for the denoising algorithm. To achieve improved results we also lower the number of clusters which reduces computational complexity. In addition, a single image noise level estimation is developed to update the cluster centers in higher PSNRs. Our results along with the computational efficiency of the proposed algorithm clearly demonstrates the improvement of the proposed algorithm over other clustering based sparse representation (CSR) and K-SVD methods.

  20. Automated detection of lung nodules in low-dose computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Cascio, D. [Dipt. di Fisica e Tecnologie Relative, Univ. di Palermo (Italy); Cheran, S.C. [Dipt. di Fisica, Univ. di Genova (Italy); Ist. Nazionale di Fisica Nucleare, Sezione di Torino (Italy); Chincarini, A. [Ist. Nazionale di Fisica Nucleare, Sezione di Genova (Italy); De Nunzio, G. [Dipt. di Scienza dei Materiali, Univ. di Lecce (Italy); Delogu, P.; Fantacci, M.E. [Dipt. di Fisica, Univ. di Pisa (Italy); Ist. Nazionale di Fisica Nucleare, Sezione di Pisa (Italy); Gargano, G. [Dipt. Interateneo di Fisica M. Merlin, Univ. di Bari (Italy); Ist. Nazionale di Fisica Nucleare, Sezione di Bari (Italy); Gori, I.; Retico, A. [Ist. Nazionale di Fisica Nucleare, Sezione di Pisa (Italy); Masala, G.L. [Struttura Dipartimentale di Matematica e Fisica, Univ. di Sassari (Italy); Ist. Nazionale di Fisica Nucleare, Sezione di Cagliari (Italy); Preite Martinez, A. [Centro Studi e Ricerche Enrico Fermi, Roma (Italy); Santoro, M. [Dipt. di Scienze Fisiche, Univ. di Napoli (Italy); Spinelli, C. [Unita Operativa Radiodiagnostica 2, Azienda Ospedaliera Universitaria Pisana, Pisa (Italy); Tarantino, T. [Divisione di Radiologia Diagnostica e Interventistica del Dipt. di Oncologia, Trapianti e Nuove Tecnologie in Medicina, Univ. di Pisa (Italy)

    2007-06-15

    A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector computed-tomography (CT) images has been developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, consisting in a 3D dot-enhancement filter for nodule detection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The database used in this study consists of 17 low-dose CT scans reconstructed with thin slice thickness ({proportional_to}300 slices/scan). The preliminary results are shown in terms of the FROC analysis reporting a good sensitivity (85% range) for both internal and sub-pleural nodules at an acceptable level of false positive findings (1-9 FP/scan); the sensitivity value remains very high (75% range) even at 1-6 FP/scan. (orig.)

  1. Automated detection of lung nodules in low-dose computed tomography

    CERN Document Server

    Cascio, D; Chincarini, A; De Nunzio, G; Delogu, P; Fantacci, M E; Gargano, G; Gori, I; Masala, G L; Martinez, A Preite; Retico, A; Santoro, M; Spinelli, C; Tarantino, T

    2007-01-01

    A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector computed-tomography (CT) images has been developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, consisting in a 3D dot-enhancement filter for nodule detection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The database used in this study consists of 17 low-dose CT scans reconstructed with thin slice thickness (~300 slices/scan). The preliminary results are shown in terms of the FROC analysis reporting a good sensitivity (85% range) for both internal and sub-pleural nodules at an acceptable level of false positive findings (1-9 FP/scan); the sensitivity value remains very hig...

  2. 低剂量X射线照射对缺血皮瓣成活影响的实验研究%Experimental study on the effect of low-dose irradiation X-ray irradiation on ischemic flap survival

    Institute of Scientific and Technical Information of China (English)

    左志诚; 王培吉; 赵家举; 江波; 张勇; 陈伟健

    2015-01-01

    目的 探讨低剂量X射线照射(LDI)对缺血皮瓣成活的影响及其可能的机制. 方法 2014年6月至2014年12月,选取SD大鼠80只,将大鼠随机分为2组,每组40只,分别为实验组A、对照组B.于大鼠背部逆行掀起1个长宽为9 cm×3 cm的蒂部靠尾侧的缺血随意皮瓣,将经消毒处理的生物隔离膜垫于皮瓣下以阻断肌层与皮瓣的血供联系,然后原位间断缝合.A组皮瓣术后立即给予总剂量值为0.2 Gy的低剂量X射线单次局部照射,B组术后不予照射.术后1~14d分别对两组皮瓣行大体观察、组织苏木精-伊红(HE)染色和Western-blot检测,计算皮瓣成活率、微血管新生情况以及皮瓣中VEGF和MMP-9的含量. 结果 术后3d、7d和14 d实验组皮瓣成活率分别为(66.46±4.37)%、(44.30±3.86)%和(32.20±4.22)%,均分别高于对照组的(43.15±5.03)%、(27.71±3.20)%、(16.40±5.34)%,差异有统计学意义(P<0.01).HE染色实验组皮瓣内可见成纤维细胞浸润及新生血管形成明显多于对照组,且皮瓣内血管管腔排列较整齐,对照组可见组织水肿较明显,新生血管数量少,管腔不规则.术后3d和7d实验组皮瓣MVD值(条/mm2)分别为(85.54±6.12)、(44.32±3.56),均高于对照组(49.35±4.75)、(18.75±2.89),差异有统计学意义(P<0.01).术后7d实验组皮瓣中VEGF和MMP-9蛋白含量明显高于对照组. 结论 LDI能够促进缺血皮瓣成活,其可能机制为LDI能够增加缺血皮瓣中VEGF和MMP-9的表达,从而促进皮瓣内血管新生.%Objective To explore the effects of low-dose X-ray irradiation effects on ischemic flap survival and its possible mechanism.Methods From June, 2014 to December, 2014, 80 SD rats were include in the study, the rats were randomly divided into 2 groups: the experimental group A and control group B.There were 40 rats in each group.The ischemic flaps with the size of 9 cm × 3 cm were designed on the back of the rats.The pedicle of the flaps was near

  3. X-ray Absorption Spectroscopy and Coherent X-ray Diffraction Imaging for Time-Resolved Investigation of the Biological Complexes: Computer Modelling towards the XFEL Experiment

    Science.gov (United States)

    Bugaev, A. L.; Guda, A. A.; Yefanov, O. M.; Lorenz, U.; Soldatov, A. V.; Vartanyants, I. A.

    2016-05-01

    The development of the next generation synchrotron radiation sources - free electron lasers - is approaching to become an effective tool for the time-resolved experiments aimed to solve actual problems in various fields such as chemistry’ biology’ medicine’ etc. In order to demonstrate’ how these experiments may be performed for the real systems to obtain information at the atomic and macromolecular levels’ we have performed a molecular dynamics computer simulation combined with quantum chemistry calculations for the human phosphoglycerate kinase enzyme with Mg containing substrate. The simulated structures were used to calculate coherent X-ray diffraction patterns’ reflecting the conformational state of the enzyme, and Mg K-edge X-ray absorption spectra, which depend on the local structure of the substrate. These two techniques give complementary information making such an approach highly effective for time-resolved investigation of various biological complexes, such as metalloproteins or enzymes with metal-containing substrate, to obtain information about both metal-containing active site or substrate and the atomic structure of each conformation.

  4. Low-dose computed tomography to detect body-packing in an animal model

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, M.H., E-mail: martin.maurer@charite.de [Klinik fuer Strahlenheilkunde, Charite - Universitaetsmedizin, Berlin (Germany); Niehues, S.M.; Schnapauff, D.; Grieser, C.; Rothe, J.H. [Klinik fuer Strahlenheilkunde, Charite - Universitaetsmedizin, Berlin (Germany); Waldmueller, D. [Bildungs- und Wissenschaftszentrum der Bundesfinanzverwaltung, Berlin (Germany); Chopra, S.S. [Klinik fuer Allgemein-, Viszeral- und Transplantationschirurgie, Charite - Universitaetsmedizin, Berlin (Germany); Hamm, B.; Denecke, T. [Klinik fuer Strahlenheilkunde, Charite - Universitaetsmedizin, Berlin (Germany)

    2011-05-15

    Objective: To assess the possible extent of dose reduction for low-dose computed tomography (CT) in the detection of body-packing (ingested drug packets) as an alternative to plain radiographs in an animal model. Materials and methods: Twelve packets containing cocaine (purity >80%) were introduced into the intestine of an experimental animal (crossbred pig), which was then repeatedly examined by abdominal CT with stepwise dose reduction (tube voltage, 80 kV; tube current, 10-350 mA). Three blinded readers independently evaluated the CT datasets starting with the lowest tube current and noted the numbers of packets detected at the different tube currents used. In addition, 1 experienced reader determined the number of packets detectable on plain abdominal radiographs and ultrasound. Results: The threshold for correct identification of all 12 drug packets was 100 mA for reader 1 and 125 mA for readers 2 and 3. Above these thresholds all 3 readers consistently identified all 12 packets. The effective dose of a low-dose CT scan with 125 mA (including scout view) was 1.0 mSv, which was below that of 2 conventional abdominal radiographs (1.2 mSv). The reader interpreting the conventional radiographs identified a total of 9 drug packets and detected 8 packets by abdominal ultrasound. Conclusions: Extensive dose reduction makes low-dose CT a valuable alternative imaging modality for the examination of suspected body-packers and might replace conventional abdominal radiographs as the first-line imaging modality.

  5. Image recovery techniques for x-ray computed tomography in limited data environments

    Energy Technology Data Exchange (ETDEWEB)

    Aufderheide, M B; Goodman, D M; Jackson, J A; Johansson, E M

    1999-03-01

    There is an increasing requirement throughout LLNL for nondestructive evaluation using X-ray computed tomography (CT). In many cases, restrictions on data acquisition time, imaging geometry, and budgets make it unfeasible to acquire projection data over enough views to achieve desired spatial resolution using conventional CT methods. In particular, conventional CT methods are non-iterative algorithms that have the advantage of low computational effort, but they are not sufficiently adaptable to incorporate prior information or non-Gaussian statistics. Most currently existing iterative tomography algorithms are based on methods that are time consuming because they converge very flowingly, if at all. The goal of the work was to develop a set of limited data CT reconstruction tools and then demonstrate their usefulness by applying them to a variety of problems of interest to LLNL. In this project they continued their development of reconstruction tools and they have demonstrated their effectiveness on several important problems.

  6. Evaluation on correction factor for in-line X-ray phase contrast computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Mingli; Huang, Zhifeng; Zhang, Li; Zhang, Ran [Tsinghua Univ., Beijing (China). Dept. of Engineering Physics; Ministry of Education, Beijing (China). Key Laboratory of Particle and Radiation Imaging; Yin, Hongxia; Liu, Yunfu; Wang, Zhenchang [Capital Medical Univ., Beijing (China). Medical Imaging Center; Xiao, Tiqiao [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Applied Physics

    2011-07-01

    X-ray in-line phase contrast computed tomography (CT) is an effective nondestructive tool, providing 3D distribution of the refractive index of weakly absorbing low-Z object with high resolution and image contrast, especially with high-brilliance third-generation synchrotron radiation sources. Modified Bronnikov's algorithm (MBA), one of the in-line phase contrast CT reconstruction algorithms, can reconstruct the refractive index distribution of a pure phase object with a single computed tomographic data set. The key idea of the MBA is to use a correction factor in the filter function to stabilize the behavior at low frequencies. In this paper, we evaluate the influences of the correction factor to the final reconstruction results of the absorption-phase-mixed objects with analytical simulation and actual experiments. The limitations of the MBA are discussed finally. (orig.)

  7. Investigation of X-ray fluorescence computed tomography (XFCT) and K-edge imaging.

    Science.gov (United States)

    Bazalova, Magdalena; Kuang, Yu; Pratx, Guillem; Xing, Lei

    2012-08-01

    This work provides a comprehensive Monte Carlo study of X-ray fluorescence computed tomography (XFCT) and K-edge imaging system, including the system design, the influence of various imaging components, the sensitivity and resolution under various conditions. We modified the widely used EGSnrc/DOSXYZnrc code to simulate XFCT images of two acrylic phantoms loaded with various concentrations of gold nanoparticles and Cisplatin for a number of XFCT geometries. In particular, reconstructed signal as a function of the width of the detector ring, its angular coverage and energy resolution were studied. We found that XFCT imaging sensitivity of the modeled systems consisting of a conventional X-ray tube and a full 2-cm-wide energy-resolving detector ring was 0.061% and 0.042% for gold nanoparticles and Cisplatin, respectively, for a dose of ∼ 10 cGy. Contrast-to-noise ratio (CNR) of XFCT images of the simulated acrylic phantoms was higher than that of transmission K-edge images for contrast concentrations below 0.4%.

  8. Visualization of subcutaneous insulin injections by x-ray computed tomography

    Science.gov (United States)

    Thomsen, M.; Poulsen, M.; Bech, M.; Velroyen, A.; Herzen, J.; Beckmann, F.; Feidenhans'l, R.; Pfeiffer, F.

    2012-11-01

    We report how the three-dimensional structure of subcutaneous injections of soluble insulin can be visualized by x-ray computed tomography using an iodine based contrast agent. The injections investigated are performed ex vivo in porcine adipose tissue. Full tomography scans carried out at a laboratory x-ray source with a total acquisition time of about 1 min yield CT-images with an effective pixel size of 109 × 109 μm2. The depots are segmented using a modified Chan-Vese algorithm and we are able to observe differences in the shape of the injection depot and the position of the depot in the skin among equally performed injections. To overcome the beam hardening artefacts, which affect the quantitative prediction of the volume injected, we additionally present results concerning the visualization of two injections using synchrotron radiation. The spatial concentration distribution of iodine is calculated to show the dilution of the insulin drug inside the depot. Characterisation of the shape of the depot and the spatial concentration profile of the injected fluid is important knowledge when improving the clinical formulation of an insulin drug, the performance of injection devices and when predicting the effect of the drug through biomedical simulations.

  9. Coded aperture x-ray diffraction imaging with transmission computed tomography side-information

    Science.gov (United States)

    Odinaka, Ikenna; Greenberg, Joel A.; Kaganovsky, Yan; Holmgren, Andrew; Hassan, Mehadi; Politte, David G.; O'Sullivan, Joseph A.; Carin, Lawrence; Brady, David J.

    2016-03-01

    Coded aperture X-ray diffraction (coherent scatter spectral) imaging provides fast and dose-efficient measurements of the molecular structure of an object. The information provided is spatially-dependent and material-specific, and can be utilized in medical applications requiring material discrimination, such as tumor imaging. However, current coded aperture coherent scatter spectral imaging system assume a uniformly or weakly attenuating object, and are plagued by image degradation due to non-uniform self-attenuation. We propose accounting for such non-uniformities in the self-attenuation by utilizing an X-ray computed tomography (CT) image (reconstructed attenuation map). In particular, we present an iterative algorithm for coherent scatter spectral image reconstruction, which incorporates the attenuation map, at different stages, resulting in more accurate coherent scatter spectral images in comparison to their uncorrected counterpart. The algorithm is based on a spectrally grouped edge-preserving regularizer, where the neighborhood edge weights are determined by spatial distances and attenuation values.

  10. Cone beam x-ray luminescence computed tomography reconstruction with a priori anatomical information

    Science.gov (United States)

    Lo, Pei-An; Lin, Meng-Lung; Jin, Shih-Chun; Chen, Jyh-Cheng; Lin, Syue-Liang; Chang, C. Allen; Chiang, Huihua Kenny

    2014-09-01

    X-ray luminescence computed tomography (XLCT) is a novel molecular imaging modality that reconstructs the optical distribution of x-ray-excited phosphor particles with prior informational of anatomical CT image. The prior information improves the accuracy of image reconstruction. The system can also present anatomical CT image. The optical system based on a high sensitive charge coupled device (CCD) is perpendicular with a CT system. In the XLCT system, the xray was adopted to excite the phosphor of the sample and CCD camera was utilized to acquire luminescence emitted from the sample in 360 degrees projection free-space. In this study, the fluorescence diffuse optical tomography (FDOT)-like algorithm was used for image reconstruction, the structural prior information was incorporated in the reconstruction by adding a penalty term to the minimization function. The phosphor used in this study is Gd2O2S:Tb. For the simulation and experiments, the data was collected from 16 projections. The cylinder phantom was 40 mm in diameter and contains 8 mm diameter inclusion; the phosphor in the in vivo study was 5 mm in diameter at a depth of 3 mm. Both the errors were no more than 5%. Based on the results from these simulation and experimental studies, the novel XLCT method has demonstrated the feasibility for in vivo animal model studies.

  11. X-ray-induced acoustic computed tomography with an ultrasound transducer ring-array

    Science.gov (United States)

    Tang, S.; Nguyen, D. H.; Zarafshani, A.; Ramseyer, C.; Zheng, B.; Liu, H.; Xiang, L.

    2017-03-01

    The objective of this study is to develop and test a unique X-ray-induced acoustic computed tomography system that combines the advantages of high X-ray imaging contrast and high ultrasonic spatial resolution. The system features a 5 MHz 128-element ultrasound transducer ring-array formed into a full circular aperture. A parallel data receiver, which consists of a dedicated 128-channel preamplifier and a 128-channel data acquisition module, provides full tomographic imaging at a speed of up to 25 frames per second. Details of the system design and calibration are presented, along with the characteristic results of the imaging resolution. The tomographic imaging performance is demonstrated through images of a phantom with a spatial resolution up to 138 μm. The study results indicate that this imaging device and the methodology provide a rapid and high resolution approach for the dynamic imaging of information, and it may have the potential for becoming a promising noninvasive imaging modality to be used in future applications.

  12. Investigation of soil structure development and properties of macropore networks with X-ray computed tomography

    Science.gov (United States)

    Pagenkemper, Sebastian; Uteau Puschmann, Daniel; Peth, Stephan; Horn, Rainer

    2014-05-01

    X-ray computed tomography provides a non-destructive method to visualize and quantify three-dimensional pore networks. Geometrical and morphological parameters of the complex pore system such as connectivity, tortuosity, porosity and pore surface area would be very useful for modeling and simulating of transport and exchange processes. Thus, quantitative data on relevant soil structural features and their modification by soil management could be provided. The scope of this study was to analyze and quantify the development of soil structure in the subsoil depending on three different precrop species (alfalfa, chicory and fescue), at three depths (45, 60 and 75 cm) and three cultivation periods (1, 2 and 3 yrs) on an experimental field trial (Germany) with a Haplic Luvisol as major soil type. Morphological (air-filled porosity, pore surface area) and geometrical (pore diameter, connectivity, continuity, tortuosity) parameters were gathered with X-ray CT and evaluated with image analysis. Furthermore, the results were linked with air-capacity data from laboratory measurements to validate the data and with tortuosity/connectivity data from diffusion-based measurements. Air-filled porosity was highest for alfalfa (3 yrs, 75 cm). Tortuosity values ranged between 1.3 and 4.38, while alfalfa (3 yrs) showed the highest value, which may indicate structural development due to crack formation by enhanced root water uptake. An increase in accessible surfaces may improve water and nutrient supply for plants, whereas the high tortuosity values may also assume that oxygen supply is limited.

  13. Positioning Standardized Acupuncture Points on the Whole Body Based on X-Ray Computed Tomography Images.

    Science.gov (United States)

    Kim, Jungdae; Kang, Dae-In

    2014-02-01

    Objective: The goal of this research was to position all the standardized 361 acupuncture points on the entire human body based on a 3-dimensional (3D) virtual body. Materials and Methods: Digital data from a healthy Korean male with a normal body shape were obtained in the form of cross-sectional images generated by X-ray computed tomography (CT), and the 3D models for the bones and the skin's surface were created through the image-processing steps. Results: The reference points or the landmarks were positioned based on the standard descriptions of the acupoints, and the formulae for the proportionalities between the acupoints and the reference points were presented. About 37% of the 361 standardized acupoints were automatically linked with the reference points, the reference points accounted for 11% of the 361 acupoints, and the remaining acupoints (52%) were positioned point-by-point by using the OpenGL 3D graphics libraries. Based on the projective 2D descriptions of the standard acupuncture points, the volumetric 3D acupoint model was developed; it was extracted from the X-ray CT images. Conclusions: This modality for positioning acupoints may modernize acupuncture research and enable acupuncture treatments to be more personalized.

  14. The exploration study of fire damage to concrete specimen using x-ray computed tomography

    Science.gov (United States)

    Su, Yu-Min; Lee, Min-Gin; Chen, Guan-Ying

    2015-04-01

    Portland Cement Concrete (PCC) loses the evaporable water at about 100 °C, decomposes C-S-H at about 200 °C, and dehydrates CH at about 500 °C, and deconstruct C-S-H at about 900°C. The concrete degradation or cracks are caused by several possible parameters, such as vapor pressure in pores, thermal gradient, and varied expansion rates of cement pastes and aggregates. The objective of the exploration study was to assess the porosity before and after conditioning of high temperature in the laboratory with the medical X-ray computed tomography. The experimental program was determined to identify the mineral properties of the aggregates used and determine the consensus properties of compressive, splitting tensile, and flexural strengths. Concrete cylinders were subject with one temperature conditioning, namely 400°C, but two different heat conditioning time namely four and eight hours. The X-ray CT, before and after high temperature conditioning, was administrated on the concrete cylinders to inspect the depth of the damage zone, which shall consist of more porosity than undamaged one. The damage zone will be examined and identified through the changes in porosity of concrete paste and aggregates within a concrete cylinder. The significance of the exploration study was to provide an in-depth insight to define the damaged zone for a better understanding of the following repairing and reinforced work.

  15. Characterizing soil macroporosity by X-ray microfocus computed tomography and quantification of the coring damages.

    Directory of Open Access Journals (Sweden)

    Caner L.

    2010-06-01

    Full Text Available X-ray Computed Tomography (X-ray µCT was employed to characterize vertical variations of structural porosity of a soil profile (pore dimension higher than 5.103 µm3. Three distinct horizons of a Cambisol have been studied for a total depth of 75 cm: L, S1/S2 and S2/SFe horizons. Samples have been cored in situ by driving in PVC tubes (inner diameter 10 cm. From reconstructed and filtered volumes, pores segmentation allows to study variations of structural porosity within the profile. Two kinds of porosity were identified: biological pores (tube-like and physical pores (fracture-like. Structural porosity content varies strongly according to the horizons: from 5.48% in the L horizon to 6.48% in the S1/S2 horizon. The 3D connectivity of both of these pore types was also assessed. During sampling, soil shearing induced damages around the cores. Identification and quantification of the damaged zone was performed from the calculation of porosity profile from core surface to core heart. In average, the damaged zone reaches a depth of 1 cm. Porosity loss (compaction or porosity increase (fracturing was observed according to the studied profile.

  16. Application of X-ray Computed Tomography to Cultural Heritage diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Morigi, M.P.; Casali, F.; Bettuzzi, M.; Brancaccio, R.; D' Errico, V. [University of Bologna, Department of Physics, Bologna (Italy)

    2010-09-15

    Physical methods of diagnosis are more and more frequently applied in the field of Cultural Heritage either for scientific investigations or for restoration and conservation purposes. X-ray Computed Tomography (CT) is one of the most powerful non-destructive testing techniques for the full-volume inspection of an object, as it is able to give morphological and physical information on the inner structure of the investigated sample. The great variety of size and composition that characterizes archaeological findings and art objects requires the development of tomographic systems specifically designed for Cultural Heritage analysis. In the last few years our research group has developed several acquisition systems for Digital Radiography and X-ray CT. We are able to perform high resolution micro-tomography of small objects (voxel size of few microns) as well as CT of large objects (up to 2 m of size). In this paper we will mainly focus the attention on the results of the investigation recently performed on two Japanese wooden statues with our CT system for large works of art. The CT analysis was carried out on site at the Conservation and Restoration Center ''La Venaria Reale'', where the statues have been restored before their exposition at the Oriental Art Museum in Turin. (orig.)

  17. High energy x-ray radiography and computed tomography of bridge pins

    Energy Technology Data Exchange (ETDEWEB)

    Green, R E; Logan, C M; Martz, H E; Updike, E; Waters, A M

    1999-05-01

    Bridge pins were used in the hanger assemblies for some multi-span steel bridges built prior to the 1980's, and are sometimes considered fracture critical elements of a bridge. During a test on a bridge conducted by the Federal Highway Administration (FHWA), ultrasonic field inspection results indicated that at least two pins contained cracks. Several pins were removed and selected for further examination. This provided an excellent opportunity to learn more about these pins and the application of x-ray systems at Lawrence Livermore National Laboratory (LLNL), as well as to learn more about the application of different detectors recently obtained by LLNL. Digital radiographs and computed tomography (CT) were used to characterize the bridge pins, using a LINAC x-ray source with a 9-MV bremsstrahlung spectrum. We will describe the performance of two different digital radiographic detectors. One is a detector system frequently used at LLNL consisting of a scintillator glass optically coupled to a CCD camera. The other detector is a new amorphous silicon detector recently acquired by LLNL.

  18. Accelerating statistical image reconstruction algorithms for fan-beam x-ray CT using cloud computing

    Science.gov (United States)

    Srivastava, Somesh; Rao, A. Ravishankar; Sheinin, Vadim

    2011-03-01

    Statistical image reconstruction algorithms potentially offer many advantages to x-ray computed tomography (CT), e.g. lower radiation dose. But, their adoption in practical CT scanners requires extra computation power, which is traditionally provided by incorporating additional computing hardware (e.g. CPU-clusters, GPUs, FPGAs etc.) into a scanner. An alternative solution is to access the required computation power over the internet from a cloud computing service, which is orders-of-magnitude more cost-effective. This is because users only pay a small pay-as-you-go fee for the computation resources used (i.e. CPU time, storage etc.), and completely avoid purchase, maintenance and upgrade costs. In this paper, we investigate the benefits and shortcomings of using cloud computing for statistical image reconstruction. We parallelized the most time-consuming parts of our application, the forward and back projectors, using MapReduce, the standard parallelization library on clouds. From preliminary investigations, we found that a large speedup is possible at a very low cost. But, communication overheads inside MapReduce can limit the maximum speedup, and a better MapReduce implementation might become necessary in the future. All the experiments for this paper, including development and testing, were completed on the Amazon Elastic Compute Cloud (EC2) for less than $20.

  19. The X-ray system of crystallographic programs for any computer having a PIDGIN FORTRAN compiler

    Science.gov (United States)

    Stewart, J. M.; Kruger, G. J.; Ammon, H. L.; Dickinson, C.; Hall, S. R.

    1972-01-01

    A manual is presented for the use of a library of crystallographic programs. This library, called the X-ray system, is designed to carry out the calculations required to solve the structure of crystals by diffraction techniques. It has been implemented at the University of Maryland on the Univac 1108. It has, however, been developed and run on a variety of machines under various operating systems. It is considered to be an essentially machine independent library of applications programs. The report includes definition of crystallographic computing terms, program descriptions, with some text to show their application to specific crystal problems, detailed card input descriptions, mass storage file structure and some example run streams.

  20. X-ray computed tomography datasets for forensic analysis of vertebrate fossils.

    Science.gov (United States)

    Rowe, Timothy B; Luo, Zhe-Xi; Ketcham, Richard A; Maisano, Jessica A; Colbert, Matthew W

    2016-06-07

    We describe X-ray computed tomography (CT) datasets from three specimens recovered from Early Cretaceous lakebeds of China that illustrate the forensic interpretation of CT imagery for paleontology. Fossil vertebrates from thinly bedded sediments often shatter upon discovery and are commonly repaired as amalgamated mosaics grouted to a solid backing slab of rock or plaster. Such methods are prone to inadvertent error and willful forgery, and once required potentially destructive methods to identify mistakes in reconstruction. CT is an efficient, nondestructive alternative that can disclose many clues about how a specimen was handled and repaired. These annotated datasets illustrate the power of CT in documenting specimen integrity and are intended as a reference in applying CT more broadly to evaluating the authenticity of comparable fossils.

  1. Gorham disease of the craniocervical junction: X-ray, computed tomography, and magnetic resonance imaging findings.

    Science.gov (United States)

    Kilicoglu, Z Gamze; Kizildemir Kis, Naciye; Vardar Aker, Fügen; Berkman, M Zafer; Simsek, M Masum

    2013-05-01

    Gorham disease of massive osteolysis is a spontaneous, idiopathic, and progressive form of primary osteolysis. It has no age, sex, or race predilection, and patients are mostly asymptomatic until severe deformity or pathological fracture becomes evident. A patient with craniocervical involvement is presented, describing imaging findings with a review of the literature to provide an insight into the disorder. Case report and review of the literature. X-ray, computed tomography, and magnetic resonance imaging findings of a patient with findings related to the site of involvement. All images demonstrate osteolysis typically described for the disease. Differential diagnosis and key features are indicated. Operative findings and pathological analysis were also consistent with the findings. Patient's follow-up is also reported. This benign appearing yet disabling disease may become fatal in relation to the site involved. Acknowledging imaging findings may provide early diagnosis for timely intervention or supportive management. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Prediction of intramuscular fat levels in Texel lamb loins using X-ray computed tomography scanning.

    Science.gov (United States)

    Clelland, N; Bunger, L; McLean, K A; Conington, J; Maltin, C; Knott, S; Lambe, N R

    2014-10-01

    For the consumer, tenderness, juiciness and flavour are often described as the most important factors for meat eating quality, all of which have a close association with intramuscular fat (IMF). X-ray computed tomography (CT) can measure fat, muscle and bone volumes and weights, in vivo in sheep and CT predictions of carcass composition have been used in UK sheep breeding programmes over the last few decades. This study aimed to determine the most accurate combination of CT variables to predict IMF percentage of M. longissimus lumborum in Texel lambs. As expected, predicted carcass fat alone accounted for a moderate amount of the variation (R(2)=0.51) in IMF. Prediction accuracies were significantly improved (Adj R(2)>0.65) using information on fat and muscle densities measured from three CT reference scans, showing that CT can provide an accurate prediction of IMF in the loin of purebred Texel sheep.

  3. Determination of Diffusion Profiles in Altered Wellbore Cement Using X-ray Computed Tomography Methods

    Energy Technology Data Exchange (ETDEWEB)

    Mason, Harris E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Walsh, Stuart D. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); DuFrane, Wyatt L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Carroll, Susan A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-06-17

    The development of accurate, predictive models for use in determining wellbore integrity requires detailed information about the chemical and mechanical changes occurring in hardened Portland cements. X-ray computed tomography (XRCT) provides a method that can nondestructively probe these changes in three dimensions. Here, we describe a method for extracting subvoxel mineralogical and chemical information from synchrotron XRCT images by combining advanced image segmentation with geochemical models of cement alteration. The method relies on determining “effective linear activity coefficients” (ELAC) for the white light source to generate calibration curves that relate the image grayscales to material composition. The resulting data set supports the modeling of cement alteration by CO2-rich brine with discrete increases in calcium concentration at reaction boundaries. The results of these XRCT analyses can be used to further improve coupled geochemical and mechanical models of cement alteration in the wellbore environment.

  4. Study on Sintering Mechanism of Stainless Steel Fiber Felts by X-ray Computed Tomography

    Directory of Open Access Journals (Sweden)

    Jun Ma

    2016-01-01

    Full Text Available The microstructure evolution of Fe-17 wt. % Cr-12 wt. % Ni-2 wt. % Mo stainless steel fiber felts during the fast sintering process was investigated by the synchrotron radiation X-ray computed tomography technique. The equation of dynamics of stable inter-fiber neck growth was established for the first time based on the geometry model of sintering joints of two fibers and Kucsynski’s two-sphere model. The specific evolutions of different kinds of sintering joints were observed in the three-dimensional images. The sintering mechanisms during sintering were proposed as plastic flow and grain boundary diffusion, the former leading to a quick growth of sintering joints.

  5. Synchrotron X-ray microprobe and computed microtomography for characterization of nanocatalysts

    Science.gov (United States)

    Jones, K. W.; Feng, H.; Lanzirotti, A.; Mahajan, D.

    2005-12-01

    Gas-to-liquids (GTL) is a viable pathway for synthesis of clean fuels from natural gas. One of the attractive synthesis options is the Fischer-Tropsch (F-T) method using an iron catalyst to yield a broad range of hydrocarbons. We collected catalyst samples during three separate F-T runs that utilized nanophase (mean particle diameter (MPD): 3 nm and 20-80 nm) and micrometer-sized (32.5 μm) Fe2O3 that served as catalyst precursors. The collected samples were characterized with micro-X-ray fluorescence and computed microtomography at the National Synchrotron Light Source (NSLS). Results found with two different measurement techniques indicated that there was heterogeneity on a spatial scale corresponding to volumes of roughly 103 μm3.

  6. A convolutional neural network approach to calibrating the rotation axis for X-ray computed tomography.

    Science.gov (United States)

    Yang, Xiaogang; De Carlo, Francesco; Phatak, Charudatta; Gürsoy, Dogˇa

    2017-03-01

    This paper presents an algorithm to calibrate the center-of-rotation for X-ray tomography by using a machine learning approach, the Convolutional Neural Network (CNN). The algorithm shows excellent accuracy from the evaluation of synthetic data with various noise ratios. It is further validated with experimental data of four different shale samples measured at the Advanced Photon Source and at the Swiss Light Source. The results are as good as those determined by visual inspection and show better robustness than conventional methods. CNN has also great potential for reducing or removing other artifacts caused by instrument instability, detector non-linearity, etc. An open-source toolbox, which integrates the CNN methods described in this paper, is freely available through GitHub at tomography/xlearn and can be easily integrated into existing computational pipelines available at various synchrotron facilities. Source code, documentation and information on how to contribute are also provided.

  7. Correlating Gas Transport Parameters and X-ray Computed Tomography Measurements in Porous Media

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Hamamoto, Shoichiro; Kawamoto, Ken

    2013-01-01

    -dried and partially saturated conditions. Gas transport parameters including gas dispersivity (α), diffusivity (DP/D0), and permeability (ka) were measured using a unified measurement system (UMS). The 3DMA-Rock computational package was used for analysis of three-dimensional CT data. A strong linear relationship...... was found between α and tortuosity calculated from gas transport parameters (Equation (Uncited) Image Tools), indicating that gas dispersivity has a linear and inverse relationship with gas diffusivity. A linear relationship was also found between ka and d50/TUMS2, indicating a strong dependency of ka...... on mean particle size and direct correlation with gas diffusivity. Tortuosity (TMFX) and equivalent pore diameter (deq.MFX) analyzed from microfocus X-ray CT increased linearly with increasing d50 for both Granusil and Accusand and further showing no effect of particle shape. The TUMS values showed...

  8. Computational Methods for Nanoscale X-ray Computed Tomography Image Analysis of Fuel Cell and Battery Materials

    Science.gov (United States)

    Kumar, Arjun S.

    Over the last fifteen years, there has been a rapid growth in the use of high resolution X-ray computed tomography (HRXCT) imaging in material science applications. We use it at nanoscale resolutions up to 50 nm (nano-CT) for key research problems in large scale operation of polymer electrolyte membrane fuel cells (PEMFC) and lithium-ion (Li-ion) batteries in automotive applications. PEMFC are clean energy sources that electrochemically react with hydrogen gas to produce water and electricity. To reduce their costs, capturing their electrode nanostructure has become significant in modeling and optimizing their performance. For Li-ion batteries, a key challenge in increasing their scope for the automotive industry is Li metal dendrite growth. Li dendrites are structures of lithium with 100 nm features of interest that can grow chaotically within a battery and eventually lead to a short-circuit. HRXCT imaging is an effective diagnostics tool for such applications as it is a non-destructive method of capturing the 3D internal X-ray absorption coefficient of materials from a large series of 2D X-ray projections. Despite a recent push to use HRXCT for quantitative information on material samples, there is a relative dearth of computational tools in nano-CT image processing and analysis. Hence, we focus on developing computational methods for nano-CT image analysis of fuel cell and battery materials as required by the limitations in material samples and the imaging environment. The first problem we address is the segmentation of nano-CT Zernike phase contrast images. Nano-CT instruments are equipped with Zernike phase contrast optics to distinguish materials with a low difference in X-ray absorption coefficient by phase shifting the X-ray wave that is not diffracted by the sample. However, it creates image artifacts that hinder the use of traditional image segmentation techniques. To restore such images, we setup an inverse problem by modeling the X-ray phase contrast

  9. Learned Shrinkage Approach for Low-Dose Reconstruction in Computed Tomography

    Directory of Open Access Journals (Sweden)

    Joseph Shtok

    2013-01-01

    Full Text Available We propose a direct nonlinear reconstruction algorithm for Computed Tomography (CT, designed to handle low-dose measurements. It involves the filtered back-projection and adaptive nonlinear filtering in both the projection and the image domains. The filter is an extension of the learned shrinkage method by Hel-Or and Shaked to the case of indirect observations. The shrinkage functions are learned using a training set of reference CT images. The optimization is performed with respect to an error functional in the image domain that combines the mean square error with a gradient-based penalty, promoting image sharpness. Our numerical simulations indicate that the proposed algorithm can manage well with noisy measurements, allowing a dose reduction by a factor of 4, while reducing noise and streak artifacts in the FBP reconstruction, comparable to the performance of a statistically based iterative algorithm.

  10. Development of Kilovoltage X-ray Dosimetry Methods and Their Application to Cone Beam Computed Tomography

    Science.gov (United States)

    Lawless, Michael J.

    The increase in popularity of pre-treatment imaging procedures in radiation therapy, such as kilovoltage cone beam computed tomography (CBCT), has been accompanied by an increase in the dose delivered to the patient from these imaging procedures. The measurement of dose from CBCT scans is complicated, as currently available kilovoltage dosimetry protocols are based on air-kerma standards and radiation detectors exhibit large energy responses at the low photon energies used in the imaging procedures. This work aims to provide the tools and methodology needed to measure the dose from these scans more accurately and precisely. Through the use of a validated Monte Carlo (MC) model of the moderately filtered (M-series) x-ray beams at the University of Wisconsin Accredited Dosimetry Calibration Laboratory, dose-to-water rates were obtained in a water phantom for the M-series x-ray beams with tube potentials from 40-250 kVp. The resulting dose-to-water rates were consistent with previously established methods, but had significantly reduced uncertainties. While detectors are commonly used to measure dose in phantom, previous investigations of the energy response of common detectors in the kilovoltage energy range have been limited to in-air geometries. The newly determined dose-to-water rates were used to characterize the in-phantom energy and depth response of thermoluminescent dosimeters and ionization chambers. When compared to previous investigations of the in-air detector response, the impact of scatter and absorption of the photon beam by the water medium was found to have a significant impact on the response of certain detectors. The dose to water in the NIST-traceable M-series x-ray beams was transferred to clinical CBCT beams and the resulting doses agreed with other dose-to-water measurement techniques. The dose to water in the CBCT beams was used to characterize the energy and depth responses of a number of detectors. The energy response in the CBCT beams agreed

  11. Characterization of impact damage in metallic/nonmetallic composites using x-ray computed tomography imaging

    Science.gov (United States)

    Green, William H.; Wells, Joseph M.

    1999-12-01

    Characterizing internal impact damage in composites can be difficult, especially in structurally complex composites or those consisting of many materials. Many methods for nondestructive inspection/nondestructive testing (NDI/NDT) of materials have been known and in use for many years, including x-ray film, real-time, and digital radiographic techniques, and ultrasonic techniques. However, these techniques are generally not capable of three-dimensional (3D) mapping of complex damage patterns, which is necessary to visualize and understand damage cracking modes. Conventional x-ray radiography suffers from the loss of 3D information. Structural complexity and signal dispersion in materials with many interfaces significantly effect ultrasonic inspection techniques. This makes inspection scan interpretation difficult, especially in composites containing a number of different materials (i.e., polymer, ceramic, and metallic). X-ray computed tomography (CT) is broadly applicable to any material or test object through which a beam of penetrating radiation may be passed and detected, including metals, plastics, ceramics, metallic/nonmetallic composites, and assemblies. The principal advantage of CT is that it provides densitometric (that is, radiological density and geometry) images of thin cross sections through an object. Because of the absence of structural superposition, images are much easier to interpret than conventional radiological images. The user can quickly learn to read CT data because images correspond more closely to the way the human mind visualizes 3D structures than projection radiology (that is, film radiography, real-time radiography (RTR), and digital radiography (DR)). Any number of CT images, or slices, from scanning an object can be volumetrically reconstructed to produce a 3D attenuation map of the object. The 3D attenuation data can be rendered using multiplanar or 3D solid visualization. In multiplanar visualization there are four planes of view

  12. 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 < 0.3% was 2 × 105. The average percent difference between calculation and 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

  13. Non-invasive classification of breast microcalcifications using x-ray coherent scatter computed tomography

    Science.gov (United States)

    Ghammraoui, Bahaa; Popescu, Lucretiu M.

    2017-02-01

    We investigate the use of energy dispersive x-ray coherent scatter computed tomography (ED-CSCT) as a non-invasive diagnostic method to differentiate between type I and type II breast calcifications. This approach is sensitive to the differences of composition and internal crystal structure of different types of microcalcifications. The study is carried out by simulating a CSCT system with a scanning pencil beam, considering a polychromatic x-ray source and an energy-resolving photon counting detector. In a first step, the multidimensional angle and energy distributed CSCT data is reduced to the projection-space distributions of only a few components, corresponding to the expected target composition: adipose, glandular tissue, weddellite (calcium oxalate) for type I calcifications, and hydroxyapatite for type II calcifications. The maximum-likelihood estimation of scatter components algorithm used, operating in the projection space, takes into account the polychromatic source, the detector response function and the energy dependent attenuation. In the second step, component images are reconstructed from the corresponding estimated component projections using filtered backprojection. In a preliminary step the coherent scatter differential cross sections for hydroxyapatite and weddellite minerals were determined experimentally. The classification of type I or II calcifications is done using the relative contrasts of their components as the criterion. Simulation tests were carried out for different doses and energy resolutions for multiple realizations. The results were analyzed using relative/receiver operating characteristic methodology and show good discrimination ability at medium and higher doses. The noninvasive CSCT technique shows potential to further improve the breast diagnostic accuracy and reduce the number of breast biopsies.

  14. Computer-aided diagnosis of pulmonary diseases using x-ray darkfield radiography

    Science.gov (United States)

    Einarsdóttir, Hildur; Yaroshenko, Andre; Velroyen, Astrid; Bech, Martin; Hellbach, Katharina; Auweter, Sigrid; Yildirim, Önder; Meinel, Felix G.; Eickelberg, Oliver; Reiser, Maximilian; Larsen, Rasmus; Kjær Ersbøll, Bjarne; Pfeiffer, Franz

    2015-12-01

    In this work we develop a computer-aided diagnosis (CAD) scheme for classification of pulmonary disease for grating-based x-ray radiography. In addition to conventional transmission radiography, the grating-based technique provides a dark-field imaging modality, which utilizes the scattering properties of the x-rays. This modality has shown great potential for diagnosing early stage emphysema and fibrosis in mouse lungs in vivo. The CAD scheme is developed to assist radiologists and other medical experts to develop new diagnostic methods when evaluating grating-based images. The scheme consists of three stages: (i) automatic lung segmentation; (ii) feature extraction from lung shape and dark-field image intensities; (iii) classification between healthy, emphysema and fibrosis lungs. A study of 102 mice was conducted with 34 healthy, 52 emphysema and 16 fibrosis subjects. Each image was manually annotated to build an experimental dataset. System performance was assessed by: (i) determining the quality of the segmentations; (ii) validating emphysema and fibrosis recognition by a linear support vector machine using leave-one-out cross-validation. In terms of segmentation quality, we obtained an overlap percentage (Ω) 92.63  ±  3.65%, Dice Similarity Coefficient (DSC) 89.74  ±  8.84% and Jaccard Similarity Coefficient 82.39  ±  12.62%. For classification, the accuracy, sensitivity and specificity of diseased lung recognition was 100%. Classification between emphysema and fibrosis resulted in an accuracy of 93%, whilst the sensitivity was 94% and specificity 88%. In addition to the automatic classification of lungs, deviation maps created by the CAD scheme provide a visual aid for medical experts to further assess the severity of pulmonary disease in the lung, and highlights regions affected.

  15. Microstructural analysis of TRISO particles using multi-scale X-ray computed tomography

    Science.gov (United States)

    Lowe, T.; Bradley, R. S.; Yue, S.; Barii, K.; Gelb, J.; Rohbeck, N.; Turner, J.; Withers, P. J.

    2015-06-01

    TRISO particles, a composite nuclear fuel built up by ceramic and graphitic layers, have outstanding high temperature resistance. TRISO fuel is the key technology for High Temperature Reactors (HTRs) and the Generation IV Very High Temperature Reactor (VHTR) variant. TRISO offers unparalleled containment of fission products and is extremely robust during accident conditions. An understanding of the thermal performance and mechanical properties of TRISO fuel requires a detailed knowledge of pore sizes, their distribution and interconnectivity. Here 50 nm, nano-, and 1 μm resolution, micro-computed tomography (CT), have been used to quantify non-destructively porosity of a surrogate TRISO particle at the 0.3-10 μm and 3-100 μm scales respectively. This indicates that pore distributions can reliably be measured down to a size approximately 3 times the pixel size which is consistent with the segmentation process. Direct comparison with Scanning Electron Microscopy (SEM) sections indicates that destructive sectioning can introduce significant levels of coarse damage, especially in the pyrolytic carbon layers. Further comparative work is required to identify means of minimizing such damage for SEM studies. Finally since it is non-destructive, multi-scale time-lapse X-ray CT opens the possibility of intermittently tracking the degradation of TRISO structure under thermal cycles or radiation conditions in order to validate models of degradation such as kernel movement. X-ray CT in-situ experimentation of TRISO particles under load and temperature could also be used to understand the internal changes that occur in the particles under accident conditions.

  16. Microstructural analysis of TRISO particles using multi-scale X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, T., E-mail: tristan.lowe@manchester.ac.uk [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); Bradley, R.S. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); Yue, S. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); The Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); Barii, K. [School of Mechanical Engineering, University of Manchester, M13 9PL (United Kingdom); Gelb, J. [Zeiss Xradia Inc., Pleasanton, CA (United States); Rohbeck, N. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); Turner, J. [School of Mechanical Engineering, University of Manchester, M13 9PL (United Kingdom); Withers, P.J. [Manchester X-ray Imaging Facility, School of Materials, University of Manchester, M13 9PL (United Kingdom); The Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom)

    2015-06-15

    TRISO particles, a composite nuclear fuel built up by ceramic and graphitic layers, have outstanding high temperature resistance. TRISO fuel is the key technology for High Temperature Reactors (HTRs) and the Generation IV Very High Temperature Reactor (VHTR) variant. TRISO offers unparalleled containment of fission products and is extremely robust during accident conditions. An understanding of the thermal performance and mechanical properties of TRISO fuel requires a detailed knowledge of pore sizes, their distribution and interconnectivity. Here 50 nm, nano-, and 1 μm resolution, micro-computed tomography (CT), have been used to quantify non-destructively porosity of a surrogate TRISO particle at the 0.3–10 μm and 3–100 μm scales respectively. This indicates that pore distributions can reliably be measured down to a size approximately 3 times the pixel size which is consistent with the segmentation process. Direct comparison with Scanning Electron Microscopy (SEM) sections indicates that destructive sectioning can introduce significant levels of coarse damage, especially in the pyrolytic carbon layers. Further comparative work is required to identify means of minimizing such damage for SEM studies. Finally since it is non-destructive, multi-scale time-lapse X-ray CT opens the possibility of intermittently tracking the degradation of TRISO structure under thermal cycles or radiation conditions in order to validate models of degradation such as kernel movement. X-ray CT in-situ experimentation of TRISO particles under load and temperature could also be used to understand the internal changes that occur in the particles under accident conditions.

  17. Quantitative wood-adhesive penetration with X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Paris, Jesse L.; Kamke, Frederick A. [Oregon State U.

    2017-03-21

    Micro X-ray computed tomography (XCT) was used to analyze the 3D adhesive penetration behavior of different wood–adhesive bondlines. Three adhesives, a phenol formaldehyde (PF), a polymeric diphenylmethane diisocyanate (pMDI), and a hybrid polyvinyl acetate (PVA), all tagged with iodine for enhanced X-ray attenuation, were used to prepare single-bondline laminates in two softwoods, Douglas-fir and loblolly pine, and one hardwood, a hybrid polar. Adhesive penetration depth was measured with two separate calculations, and results were compared with 2D fluorescent micrographs. A total of 54 XCT scans were collected, representing six replicates of each treatment type; each replicate, however, consisted of approximately 1500 individual, cross-section slices stacked along the specimen length. As these adhesives were highly modified, the presented results do not indicate typical behavior for their broader adhesive classes. Still, clear penetration differences were observed between each adhesive type, and between wood species bonded with both the PF and pMDI adhesives. Furthermore, penetration results depended on the calculation method used. Two adhesive types with noticeably different resin distributions in the cured bondline, showed relatively similar penetration depths when calculated with a traditional effective penetration equation. However, when the same data was calculated with a weighted penetration calculation, which accounts for both adhesive area and depth, the results appeared to better represent the different distributions depicted in the photomicrographs and tomograms. Additionally, individual replicate comparisons showed variation due to specimen anatomy, not easily observed or interpreted from 2D images. Finally, 3D views of segmented 3D adhesive phases offered unique, in-situ views of the cured adhesive structures. In particular, voids formed by CO2 bubbles generated during pMDI cure were clearly visible in penetrated columns of the solidified

  18. DEVELOPMENTS IN SYNCHROTRON X-RAY COMPUTED MICROTOMOGRAPHY AT THE NATIONAL SYNCHROTRON LIGHT SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    DOWD,B.A.

    1999-07-23

    Last year, the X27A beamline at the National Synchrotron Light Source (NSLS) became dedicated solely to X-Ray Computed Microtomography (XCMT). This is a third-generation instrument capable of producing tomographic volumes of 1-2 micron resolution over a 2-3mm field of view. Recent enhancements will be discussed. These have focused on two issues: the desire for real-time data acquisition and processing and the need for highly monochromatic beam (.1 % energy bandpass). The latter will permit k-edge subtraction studies and will provide improved image contrast from below the Cr (6 keV) up to the Cs (36 keV) k-edge. A range of applications that benefit from these improvements will be discussed as well. These two goals are somewhat counterproductive, however; higher monochromaticity yields a lower flux forcing longer data acquisition times. To balance the two, a more efficient scintillator for X-ray conversion is being developed. Some testing of a prototype scintillator has been performed; preliminary results will be presented here. In the meantime, data reconstruction times have been reduced, and the entire tomographic acquisition, reconstruction and volume rendering process streamlined to make efficient use of synchrotron beam time. A Fast Filtered Back Transform (FFBT) reconstruction program recently developed helped to reduce the time to reconstruct a volume of 150 x 150 x 250 pixels{sup 3} (over 5 million voxels) from the raw camera data to 1.5 minutes on a dual R10,000 CPU. With these improvements, one can now obtain a ''quick look'' of a small tomographic volume ({approximately}10{sup 6}voxels) in just over 15 minutes from the start of data acquisition.

  19. X-ray scatter correction method for dedicated breast computed tomography: improvements and initial patient testing

    Science.gov (United States)

    Ramamurthy, Senthil; D'Orsi, Carl J.; Sechopoulos, Ioannis

    2016-02-01

    A previously proposed x-ray scatter correction method for dedicated breast computed tomography was further developed and implemented so as to allow for initial patient testing. The method involves the acquisition of a complete second set of breast CT projections covering 360° with a perforated tungsten plate in the path of the x-ray beam. To make patient testing feasible, a wirelessly controlled electronic positioner for the tungsten plate was designed and added to a breast CT system. Other improvements to the algorithm were implemented, including automated exclusion of non-valid primary estimate points and the use of a different approximation method to estimate the full scatter signal. To evaluate the effectiveness of the algorithm, evaluation of the resulting image quality was performed with a breast phantom and with nine patient images. The improvements in the algorithm resulted in the avoidance of introduction of artifacts, especially at the object borders, which was an issue in the previous implementation in some cases. Both contrast, in terms of signal difference and signal difference-to-noise ratio were improved with the proposed method, as opposed to with the correction algorithm incorporated in the system, which does not recover contrast. Patient image evaluation also showed enhanced contrast, better cupping correction, and more consistent voxel values for the different tissues. The algorithm also reduces artifacts present in reconstructions of non-regularly shaped breasts. With the implemented hardware and software improvements, the proposed method can be reliably used during patient breast CT imaging, resulting in improvement of image quality, no introduction of artifacts, and in some cases reduction of artifacts already present. The impact of the algorithm on actual clinical performance for detection, diagnosis and other clinical tasks in breast imaging remains to be evaluated.

  20. Imaging biofilms in porous media using X-ray computed micro-tomography

    Science.gov (United States)

    Davit, Y.; Debenest, G.; Quintard, M.

    2009-12-01

    In soils and rivers subsurface, bacterial biofilms growth induce modifications of mass and momentum transport dynamics. Evidence for these modifications have been developed essentially by inspection, that is, observation of the reduction of hydraulic conductivity, permeability, changes in porosity and anomalous transport. Deeper understanding of these sessile communities in porous media environments and of the multiscale/multiphase complexity of the system requires 3-D informations concerning the pore-scale/biofilm-scale geometry. Additionnally, breakthroughs in imaging techniques are likely to trigger breakthroughs in the theoretical analysis. In this study, we develop a new technique for direct observation and imaging of unstrained biofilms in porous media using X-ray computed micro-tomography. The biofilms are grown for ten days on polyamide and expanded polystyrene beads placed in small plastic columns. A circulation of water from the river Garonne (France) is imposed using peristaltic pumps. No particular bacterial strain is introduced, the micro-organisms being naturally present in the water from the river. The X-ray acquisition is performed by a Skyscan-1174 micro-CT. A special experimental technique, based on two different contrast agents, has been designed to solve the challenging problem of imaging 3 phases of initial similar absorption coefficients. On the one hand, we use a suspension of barium sulfate to enhance the contrast of the water-phase. On the other hand, the absorption of the biofilm-phase is increased using iodine which diffuses into the polymeric matrix. Examples of reconstructed images are given to illustrate the effectiveness of the method. We demonstrate how to combine the 3-D measurements with upscaling techniques such as volume averaging, by calculating the modifications of the permeability of the system when biofilms grow. At last, we aim to couple these 3-D measurements with upscaled reactive models to describe the Darcy

  1. Computer-aided recognition of dental implants in X-ray images

    Science.gov (United States)

    Morais, Pedro; Queirós, Sandro; Moreira, António H. J.; Ferreira, Adriano; Ferreira, Ernesto; Duque, Duarte; Rodrigues, Nuno F.; Vilaça, João. L.

    2015-03-01

    Dental implant recognition in patients without available records is a time-consuming and not straightforward task. The traditional method is a complete user-dependent process, where the expert compares a 2D X-ray image of the dental implant with a generic database. Due to the high number of implants available and the similarity between them, automatic/semi-automatic frameworks to aide implant model detection are essential. In this study, a novel computer-aided framework for dental implant recognition is suggested. The proposed method relies on image processing concepts, namely: (i) a segmentation strategy for semi-automatic implant delineation; and (ii) a machine learning approach for implant model recognition. Although the segmentation technique is the main focus of the current study, preliminary details of the machine learning approach are also reported. Two different scenarios are used to validate the framework: (1) comparison of the semi-automatic contours against implant's manual contours of 125 X-ray images; and (2) classification of 11 known implants using a large reference database of 601 implants. Regarding experiment 1, 0.97±0.01, 2.24±0.85 pixels and 11.12±6 pixels of dice metric, mean absolute distance and Hausdorff distance were obtained, respectively. In experiment 2, 91% of the implants were successfully recognized while reducing the reference database to 5% of its original size. Overall, the segmentation technique achieved accurate implant contours. Although the preliminary classification results prove the concept of the current work, more features and an extended database should be used in a future work.

  2. Success rates for computed tomography-guided musculoskeletal biopsies performed using a low-dose technique

    Energy Technology Data Exchange (ETDEWEB)

    Motamedi, Kambiz; Levine, Benjamin D.; Seeger, Leanne L.; McNitt-Gray, Michael F. [UCLA Health System, Radiology, Los Angeles, CA (United States)

    2014-11-15

    To evaluate the success rate of a low-dose (50 % mAs reduction) computed tomography (CT) biopsy technique. This protocol was adopted based on other successful reduced-CT radiation dose protocols in our department, which were implemented in conjunction with quality improvement projects. The technique included a scout view and initial localizing scan with standard dose. Additional scans obtained for further guidance or needle adjustment were acquired by reducing the tube current-time product (mAs) by 50 %. The radiology billing data were searched for CT-guided musculoskeletal procedures performed over a period of 8 months following the initial implementation of the protocol. These were reviewed for the type of procedure and compliance with the implemented protocol. The compliant CT-guided biopsy cases were then retrospectively reviewed for patient demographics, tumor pathology, and lesion size. Pathology results were compared to the ultimate diagnoses and were categorized as diagnostic, accurate, or successful. Of 92 CT-guided procedures performed during this period, two were excluded as they were not biopsies (one joint injection and one drainage), 19 were excluded due to non-compliance (operators neglected to follow the protocol), and four were excluded due to lack of available follow-up in our electronic medical records. A total of 67 compliant biopsies were performed in 63 patients (two had two biopsies, and one had three biopsies). There were 32 males and 31 females with an average age of 50 (range, 15-84 years). Of the 67 biopsies, five were non-diagnostic and inaccurate and thus unsuccessful (7 %); five were diagnostic but inaccurate and thus unsuccessful (7 %); 57 were diagnostic and accurate thus successful (85 %). These results were comparable with results published in the radiology literature. The success rate of CT-guided biopsies using a low-dose protocol is comparable to published rates for conventional dose biopsies. The implemented low-dose protocol

  3. A Computer Program for Calculation of Calibration Curves for Quantitative X-Ray Diffraction Analysis.

    Science.gov (United States)

    Blanchard, Frank N.

    1980-01-01

    Describes a FORTRAN IV program written to supplement a laboratory exercise dealing with quantitative x-ray diffraction analysis of mixtures of polycrystalline phases in an introductory course in x-ray diffraction. Gives an example of the use of the program and compares calculated and observed calibration data. (Author/GS)

  4. A Computer Program for Calculation of Calibration Curves for Quantitative X-Ray Diffraction Analysis.

    Science.gov (United States)

    Blanchard, Frank N.

    1980-01-01

    Describes a FORTRAN IV program written to supplement a laboratory exercise dealing with quantitative x-ray diffraction analysis of mixtures of polycrystalline phases in an introductory course in x-ray diffraction. Gives an example of the use of the program and compares calculated and observed calibration data. (Author/GS)

  5. DETERMINATION OF HLW GLASS MELT RATE USING X-RAY COMPUTED TOMOGRAPHY

    Energy Technology Data Exchange (ETDEWEB)

    Choi, A.; Miller, D.; Immel, D.

    2011-10-06

    , a significant amount of glassy material interspersed among the gas bubbles will be excluded, thus underestimating the melt rate. Likewise, if they are drawn too high, many large voids will be counted as glass, thus overestimating the melt rate. As will be shown later in this report, there is also no guarantee that a given distribution of glass and gas bubbles along a particular sectioned plane will always be representative of the entire sample volume. Poor reproducibility seen in some LMR data may be related to these difficulties of the visual method. In addition, further improvement of the existing melt rate model requires that the overall impact of feed chemistry on melt rate be reflected on measured data at a greater quantitative resolution on a more consistent basis than the visual method can provide. An alternate method being pursued is X-ray computed tomography (CT). It involves X-ray scanning of glass samples, performing CT on the 2-D X-ray images to build 3-D volumetric data, and adaptive segmentation analysis of CT results to not only identify but quantify the distinct regions within each sample based on material density and morphologies. The main advantage of this new method is that it can determine the relative local density of the material remaining in the beaker after the heat treatment regardless of its morphological conditions by selectively excluding all the voids greater than a given volumetric pixel (voxel) size, thus eliminating much of the subjectivity involved in the visual method. As a result, the melt rate data obtained from CT scan will give quantitative descriptions not only on the fully-melted glass, but partially-melted and unmelted feed materials. Therefore, the CT data are presumed to be more reflective of the actual melt rate trends in continuously-fed melters than the visual data. In order to test the applicability of X-ray CT scan to the HLW glass melt rate study, several new series of HLW simulant/frit mixtures were melted in the

  6. X-ray - skeleton

    Science.gov (United States)

    ... x-ray particles pass through the body. A computer or special film records the images. Structures that ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  7. Analytical computation of stray light in nested mirror modules for x-ray telescopes

    Science.gov (United States)

    Spiga, Daniele

    2015-09-01

    Stray light in X-ray telescopes are a well-known issue. Unlike rays focused via a double reflection by usual grazing-incidence geometries such as the Wolter-I, stray rays coming from off-axis sources are reflected only once by either the parabolic or the hyperbolic segment. Although not focused, stray light may represent a major source of background and ghost images especially when observing a field of faint sources in the vicinities of another, more intense, just outside the field of view of the telescope. The stray light problem is faced by mounting a pre-collimator in front of the mirror module, in order to shade a part of the reflective surfaces that may give rise to singly-reflected rays. Studying the expected stray light impact, and consequently designing a pre-collimator, is a typical ray-tracing problem, usually time and computation consuming, especially if we consider that rays propagate throughout a densely nested structure. This in turn requires one to pay attention to all the possible obstructions, increasing the complexity of the simulation. In contrast, approaching the problems of stray light calculation from an analytical viewpoint largely simplifies the problem, and may also ease the task of designing an effective pre-collimator. In this work we expose an analytical formalism that can be used to compute the stray light in a nested optical module in a fast and effective way, accounting for obstruction effects.

  8. Spectral x-ray computed tomography scanner using a cadmium telluride detector

    Science.gov (United States)

    Sato, Eiichi; Oda, Yasuyuki; Yamaguchi, Satoshi; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Watanabe, Manabu; Kusachi, Shinya

    2016-10-01

    To obtain four tomograms with four different photon energy ranges simultaneously, we have developed a quad-energy Xray photon counter with a cadmium telluride (CdTe) detector and four sets of comparators and frequency-voltage converters (FVCs). X-ray photons are detected using the CdTe detector, and the event pulses from a shaping amplifier are sent to four comparators simultaneously to regulate four threshold energies of 20, 35, 50 and 65 keV. Using this counter, the energy ranges are 20-100, 35-100, 50-100 and 65-100 keV; the maximum energy corresponds to the tube voltage. Xray photons in the four ranges are counted using the comparators, and the logical pulses from the comparators are input to the FVCs. The outputs from the four FVCs are input to a personal computer through an analog-digital converter (ADC) to carry out quad-energy imaging. To observe contrast variations with changes in the threshold energy, we performed spectral computed tomography utilizing the quad-energy photon counter at a tube voltage of 100 kV and a current of 8.0 μA. In the spectral CT, four tomograms were obtained simultaneously with four energy ranges. The image contrast varied with changes in the threshold energy, and the exposure time for tomography was 9.8 min.

  9. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography

    Science.gov (United States)

    Walton, Lucy A.; Bradley, Robert S.; Withers, Philip J.; Newton, Victoria L.; Watson, Rachel E. B.; Austin, Clare; Sherratt, Michael J.

    2015-05-01

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons.

  10. Lung cancer screening with low-dose computed tomography: Canadian experience

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, H.C.; Patsios, D.; Paul, N.S. [Univ. Health Network, Dept. of Medical Imaging, Toronto, Ontario (Canada)]. E-mail: Heidi.Roberts@uhn.on.ca (and others)

    2007-10-15

    In 2003, the department of medical imaging at the University Health Network in Toronto, Ontario, became the first Canadian site of the International Early Lung Cancer Action Program (I-ELCAP). We report the results from the first 1000 baseline studies. Between June 2003 and December 2005, we enrolled 1000 high-risk smokers (that is, smokers with a history of a least 10 pack years, or the equivalent of one pack daily for 10 years), aged 55 years or older. A low-dose helical computed tomography (CT) (40 to 60 mA, 120 kV) was performed with 1.0mm to 1.25 collimation. Nodules found at baseline were followed according to the I-ELCAP protocol: 1) no noncalcified nodules (NCNs) or NCNs {<=} 4 mm or nonsolid nodules < 8 mm, annual repeat: 2) NCNs {>=} 5mm or nonsolid nodules {>=} 8 mm, 3-month follow up: or 3) nonsolid nodules {>=} 15 mm, antibiotics and 1-month follow-up. The first 100 study participants were aged 63 years, standard deviation (SD) 6 years, with a smoking history of 38 pack years, SD 22 pack years; 662 (66%) were former smokers, and 338 (34%) were current smokers; 453 (45%) were men, and 547 (55%) were women. Of the participants, 256 (26%) had a positive baseline low-dose computed tomography (LCDT) scan; 227 (23%) were followed after 3 months and 15 (1.6%) after 1 month; 7 (0.7%) received a contrast-enhanced CT and 6 (0.6%) an immediate CT-guided biopsy. Twenty-six invasive procedures were performed: 22 CT-guided biopsies, 1 ultrasound-guided lymph node metastasis biopsy, 1 bronchoscopic biopsy and 2 surgeries. The malignancy rate of the invasive procedures was 85%. Overall, the malignancy prevalence is 2.2%. Of the malignancies, 20 are lung carcinomas: 19 non-small-cell lung carcinomas (NSCLCs) (14 adenocarcinoma or bronchioalveolar carcinoma [BAC], 4 squamous carcinoma, and 1 large-cell carcinoma) and 1 small-cell carcinoma; 15 (78%) of the NSCLCs are Stage 1. Fourteen patients underwent surgery (1 pneumonectomy, 9 lobectomies, and 4 segmentectomies

  11. X-ray crystallography

    Science.gov (United States)

    2001-01-01

    X-rays diffracted from a well-ordered protein crystal create sharp patterns of scattered light on film. A computer can use these patterns to generate a model of a protein molecule. To analyze the selected crystal, an X-ray crystallographer shines X-rays through the crystal. Unlike a single dental X-ray, which produces a shadow image of a tooth, these X-rays have to be taken many times from different angles to produce a pattern from the scattered light, a map of the intensity of the X-rays after they diffract through the crystal. The X-rays bounce off the electron clouds that form the outer structure of each atom. A flawed crystal will yield a blurry pattern; a well-ordered protein crystal yields a series of sharp diffraction patterns. From these patterns, researchers build an electron density map. With powerful computers and a lot of calculations, scientists can use the electron density patterns to determine the structure of the protein and make a computer-generated model of the structure. The models let researchers improve their understanding of how the protein functions. They also allow scientists to look for receptor sites and active areas that control a protein's function and role in the progress of diseases. From there, pharmaceutical researchers can design molecules that fit the active site, much like a key and lock, so that the protein is locked without affecting the rest of the body. This is called structure-based drug design.

  12. Evaluation of pore structures and cracking in cement paste exposed to elevated temperatures by X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwang Yeom, E-mail: kimky@kict.re.kr [Korea Institute of Construction Technology, 283 Goyangdae-ro, Ilsanseo-gu, Goyang 411-712 (Korea, Republic of); Yun, Tae Sup, E-mail: taesup@yonsei.ac.kr [School of Civil and Environmental Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Park, Kwang Pil, E-mail: bamtol97@kict.re.kr [Korea Institute of Construction Technology, 283 Goyangdae-ro, Ilsanseo-gu, Goyang 411-712 (Korea, Republic of)

    2013-08-15

    When cement-based materials are exposed to the high temperatures induced by fire, which can rapidly cause temperatures of over 1000 °C, the changes in pore structure and density prevail. In the present study, mortar specimens were subjected to a series of increasing temperatures to explore the temperature-dependent evolution of internal pore structure. High-performance X-ray computed tomography (CT) was used to observe the evolution of temperature-induced discontinuities at the sub-millimeter level. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate the cause of physical changes in the heated mortar specimens. Results exhibit the changes in pore structure caused by elevated temperatures, and thermally induced fractures. We discuss the progressive formation of thermally induced fracture networks, which is a prerequisite for spalling failure of cement-based materials by fire, based on visual observations of the 3D internal structures revealed by X-ray CT.

  13. Poly-ε-caprolactone tungsten oxide nanoparticles as a contrast agent for X-ray computed tomography.

    Science.gov (United States)

    Jakhmola, Anshuman; Anton, Nicolas; Anton, Halina; Messaddeq, Nadia; Hallouard, François; Klymchenko, Andrey; Mely, Yves; Vandamme, Thierry F

    2014-03-01

    Inorganic nanomaterials based on heavy elements represent a new class of contrast agents for X-ray computed tomography (CT). Recent advances have shown that these materials are highly suited for CT imaging due to their high density and X-ray absorption capabilities. In this contribution, we demonstrated that tungsten oxide (WO3) nanoparticles coated by poly-ε-caprolactone (PCL) can be used as efficient contrast agent for CT imaging. The obtained particles were characterized by electron microscopy (TEM and SEM), and dynamic light scattering (DLS). We also validated their use for enhanced in vivo imaging, since these nanoparticles were observed to display high X-ray attenuation properties and circulation time (up to 3 h), permitting blood pool imaging.

  14. Cybersecurity, massive data processing, community interaction, and other developments at WWW-based computational X-ray Server

    Science.gov (United States)

    Stepanov, Sergey

    2013-03-01

    X-Ray Server (x-server.gmca.aps.anl.gov) is a WWW-based computational server for modeling of X-ray diffraction, reflection and scattering data. The modeling software operates directly on the server and can be accessed remotely either from web browsers or from user software. In the later case the server can be deployed as a software library or a data fitting engine. As the server recently surpassed the milestones of 15 years online and 1.5 million calculations, it accumulated a number of technical solutions that are discussed in this paper. The developed approaches to detecting physical model limits and user calculations failures, solutions to spam and firewall problems, ways to involve the community in replenishing databases and methods to teach users automated access to the server programs may be helpful for X-ray researchers interested in using the server or sharing their own software online.

  15. Characterization of a spectroscopic detector for application in x-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Dooraghi, A. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fix, B. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Smith, J. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brown, W. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Azevedo, S. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martz, H. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-04-21

    Recent advances in cadmium telluride (CdTe) energy-discriminating pixelated detectors have enabled the possibility of Multi-Spectral X-ray Computed Tomography (MSXCT) to incorporate spectroscopic information into CT. MultiX ME 100 V2 is a CdTe-based spectroscopic x-ray detector array capable of recording energies from 20 to 160 keV in 1.1 keV energy bin increments. Hardware and software have been designed to perform radiographic and computed tomography tasks with this spectroscopic detector. Energy calibration is examined using the end-point energy of a bremsstrahlung spectrum and radioisotope spectral lines. When measuring the spectrum from Am-241 across 500 detector elements, the standard deviation of the peak-location and FWHM measurements are ±0.4 and ±0.6 keV, respectively. As these values are within the energy bin size (1.1 keV), detector elements are consistent with each other. The count rate is characterized, using a nonparalyzable model with a dead time of 64 ± 5 ns. This is consistent with the manufacturer’s quoted per detector-element linear-deviation at 2 Mpps (million photons per sec) of 8.9% (typical) and 12% (max). When comparing measured and simulated spectra, a low-energy tail is visible in the measured data due to the spectral response of the detector. If no valid photon detections are expected in the low-energy tail, then a background subtraction may be applied to allow for a possible first-order correction. If photons are expected in the low-energy tail, a detailed model must be implemented. A radiograph of an aluminum step wedge with a maximum height of about 20 mm shows an underestimation of attenuation by about 10% at 60 keV. This error is due to partial energy deposition from higher-energy (> 60 keV) photons into a lower-energy (~60 keV) bin, reducing the apparent attenuation. A radiograph of a PTFE cylinder taken using a bremsstrahlung spectrum from an x-ray voltage of 100 kV filtered by 1.3 mm Cu is reconstructed using Abel inversion

  16. Phase transitions in diglyceride monolayers studied by computer simulations, pressure-area isotherms and x-ray diffraction

    DEFF Research Database (Denmark)

    Peters, Günther H.J.; Toxværd, S.; Larsen, N.B.

    1994-01-01

    1,2-sn-diglyceride monolayers exhibit unique and complex phase transitions as a function of surface pressure. The dynamical response of the layer on expanding the film has been investigated by computer simulations, (π-A) isotherms and grazing-incidence X-ray diffraction. Good agreement is found b...

  17. An experimental method for ripple minimization in transmission data for industrial X-ray computed tomography imaging system

    Indian Academy of Sciences (India)

    Umesh Kumar; G S Ramakrishna; S S Datta; Gursharan Singh

    2002-06-01

    Industrial Computed Tomographic (ICT) imaging systems based on X-rays require a high stability source. This emanates from the fact that in a computed tomographic imaging system, statistical variation inherent in the penetrating radiation used to probe the specimen, electronic noise generated in the detection system and reconstruction errors play an important role in the overall quality of the image. A conventional industrial X-ray machine used for routine radiography work is not suitable for tomographic imaging applications because of its output dose variations. In this paper, an experiment is described to utilise a general-purpose 160 kV constant potential industrial X-ray machine with significant ripple in its output beam, in an experimental Computed Industrial Tomographic Imaging System (CITIS) developed at Isotope Applications Division of Bhabha Atomic Research Centre. Studies carried out include the analysis of temporal profile of X-ray beam intensity and online averaging of detected signals for the minimization of periodic ripple, which mainly showed up, at the power line frequency. A tomographic image of a typical specimen, reconstructed with the processed projection data is analysed. It was observed that the mean value of reconstructed linear absorption coefficients and standard deviation computed over a window within a constant density region of the object were stable.

  18. Physical characterization and performance evaluation of an x-ray micro-computed tomography system for dimensional metrology applications

    DEFF Research Database (Denmark)

    Hiller, Jochen; Maisl, Michael; Reindl, Leonard M

    2012-01-01

    This paper presents physical and metrological characterization measurements conducted for an industrial x-ray micro-computed tomography (CT) system. As is well known in CT metrology, many factors, e.g., in the scanning and reconstruction process, the image processing, and the 3D data evaluation...

  19. How little data is enough? Phase-diagram analysis of sparsity-regularized X-ray computed tomography

    DEFF Research Database (Denmark)

    Jørgensen, Jakob Sauer; Sidky, E. Y.

    2015-01-01

    We introduce phase-diagram analysis, a standard tool in compressed sensing (CS), to the X-ray computed tomography (CT) community as a systematic method for determining how few projections suffice for accurate sparsity-regularized reconstruction. In CS, a phase diagram is a convenient way to study...

  20. MAX--An Interactive Computer Program for Teaching Identification of Clay Minerals by X-ray Diffraction.

    Science.gov (United States)

    Kohut, Connie K.; And Others

    1993-01-01

    Discusses MAX, an interactive computer program for teaching identification of clay minerals based on standard x-ray diffraction characteristics. The program provides tutorial-type exercises for identification of 16 clay standards, self-evaluation exercises, diffractograms of 28 soil clay minerals, and identification of nonclay minerals. (MDH)

  1. MAX--An Interactive Computer Program for Teaching Identification of Clay Minerals by X-ray Diffraction.

    Science.gov (United States)

    Kohut, Connie K.; And Others

    1993-01-01

    Discusses MAX, an interactive computer program for teaching identification of clay minerals based on standard x-ray diffraction characteristics. The program provides tutorial-type exercises for identification of 16 clay standards, self-evaluation exercises, diffractograms of 28 soil clay minerals, and identification of nonclay minerals. (MDH)

  2. Fatigue damage assessment of uni-directional non-crimp fabric reinforced polyester composite using X-ray computed tomography

    DEFF Research Database (Denmark)

    Jespersen, Kristine Munk; Zangenberg Hansen, Jens; Lowe, Tristan

    2016-01-01

    In this study, the progression of tension-tension fatigue (R=0.1) damage in a unidirectional (UD) composite made from a non-crimp glass fibre fabric used for wind turbine blades is investigated using multi-scale 3D X-ray computed tomography (CT). Initially, a representative volume is examined...

  3. [Rupture of an intracerebral dermoid cyst. Apropos of a case: x-ray computed tomographic aspects].

    Science.gov (United States)

    Baudrillard, J C; Scherpereel, B; Rousseaux, P; Lerais, J M; Toubas, O; Auquier, F; Guyot, J F; Lacour, P Y

    1986-02-01

    We report the C.T. findings of a dermoid cyst communicating with ventricular system and ruptured in the subarachnoid space. A fat-fluid level and calcifications were present on the plain skull X rays.

  4. Fourier transform based iterative method for x-ray differential phase-contrast computed tomography

    CERN Document Server

    Cong, Wenxiang; Wang, Ge

    2011-01-01

    Biological soft tissues encountered in clinical and pre-clinical imaging mainly consist of light element atoms, and their composition is nearly uniform with little density variation. Thus, x-ray attenuation imaging suffers from low image contrast resolution. By contrast, x-ray phase shift of soft tissues is about a thousand times greater than x-ray absorption over the diagnostic energy range, thereby a significantly higher sensitivity can be achieved in terms of phase shift. In this paper, we propose a novel Fourier transform based iterative method to perform x-ray tomographic imaging of the refractive index directly from differential phase shift data. This approach offers distinct advantages in cases of incomplete and noisy data than analytic reconstruction, and especially suitable for phase-contrast interior tomography by incorporating prior knowledge in a region of interest (ROI). Biological experiments demonstrate the merits of the proposed approach.

  5. SU-C-209-06: Improving X-Ray Imaging with Computer Vision and Augmented Reality

    Energy Technology Data Exchange (ETDEWEB)

    MacDougall, R.D.; Scherrer, B [Boston Children’s Hospital, Boston, MA (United States); Don, S [Washington University, St. Louis, MO (United States)

    2016-06-15

    Purpose: To determine the feasibility of using a computer vision algorithm and augmented reality interface to reduce repeat rates and improve consistency of image quality and patient exposure in general radiography. Methods: A prototype device, designed for use with commercially available hardware (Microsoft Kinect 2.0) capable of depth sensing and high resolution/frame rate video, was mounted to the x-ray tube housing as part of a Philips DigitalDiagnost digital radiography room. Depth data and video was streamed to a Windows 10 PC. Proprietary software created an augmented reality interface where overlays displayed selectable information projected over real-time video of the patient. The information displayed prior to and during x-ray acquisition included: recognition and position of ordered body part, position of image receptor, thickness of anatomy, location of AEC cells, collimated x-ray field, degree of patient motion and suggested x-ray technique. Pre-clinical data was collected in a volunteer study to validate patient thickness measurements and x-ray images were not acquired. Results: Proprietary software correctly identified ordered body part, measured patient motion, and calculated thickness of anatomy. Pre-clinical data demonstrated accuracy and precision of body part thickness measurement when compared with other methods (e.g. laser measurement tool). Thickness measurements provided the basis for developing a database of thickness-based technique charts that can be automatically displayed to the technologist. Conclusion: The utilization of computer vision and commercial hardware to create an augmented reality view of the patient and imaging equipment has the potential to drastically improve the quality and safety of x-ray imaging by reducing repeats and optimizing technique based on patient thickness. Society of Pediatric Radiology Pilot Grant; Washington University Bear Cub Fund.

  6. Method for beam hardening correction in quantitative computed X-ray tomography

    Science.gov (United States)

    Yan, Chye Hwang (Inventor); Whalen, Robert T. (Inventor); Napel, Sandy (Inventor)

    2001-01-01

    Each voxel is assumed to contain exactly two distinct materials, with the volume fraction of each material being iteratively calculated. According to the method, the spectrum of the X-ray beam must be known, and the attenuation spectra of the materials in the object must be known, and be monotonically decreasing with increasing X-ray photon energy. Then, a volume fraction is estimated for the voxel, and the spectrum is iteratively calculated.

  7. Lung cancer screening beyond low-dose computed tomography: the role of novel biomarkers.

    Science.gov (United States)

    Hasan, Naveed; Kumar, Rohit; Kavuru, Mani S

    2014-10-01

    Lung cancer is the most common and lethal malignancy in the world. The landmark National lung screening trial (NLST) showed a 20% relative reduction in mortality in high-risk individuals with screening low-dose computed tomography. However, the poor specificity and low prevalence of lung cancer in the NLST provide major limitations to its widespread use. Furthermore, a lung nodule on CT scan requires a nuanced and individualized approach towards management. In this regard, advances in high through-put technology (molecular diagnostics, multi-gene chips, proteomics, and bronchoscopic techniques) have led to discovery of lung cancer biomarkers that have shown potential to complement the current screening standards. Early detection of lung cancer can be achieved by analysis of biomarkers from tissue samples within the respiratory tract such as sputum, saliva, nasal/bronchial airway epithelial cells and exhaled breath condensate or through peripheral biofluids such as blood, serum and urine. Autofluorescence bronchoscopy has been employed in research setting to identify pre-invasive lesions not identified on CT scan. Although these modalities are not yet commercially available in clinic setting, they will be available in the near future and clinicians who care for patients with lung cancer should be aware. In this review, we present up-to-date state of biomarker development, discuss their clinical relevance and predict their future role in lung cancer management.

  8. Standardization and Optimization of Computed Tomography Protocols to Achieve Low-Dose

    Science.gov (United States)

    Chin, Cynthia; Cody, Dianna D.; Gupta, Rajiv; Hess, Christopher P.; Kalra, Mannudeep K.; Kofler, James M.; Krishnam, Mayil S.; Einstein, Andrew J.

    2014-01-01

    The increase in radiation exposure due to CT scans has been of growing concern in recent years. CT scanners differ in their capabilities and various indications require unique protocols, but there remains room for standardization and optimization. In this paper we summarize approaches to reduce dose, as discussed in lectures comprising the first session of the 2013 UCSF Virtual Symposium on Radiation Safety in Computed Tomography. The experience of scanning at low dose in different body regions, for both diagnostic and interventional CT procedures, is addressed. An essential primary step is justifying the medical need for each scan. General guiding principles for reducing dose include tailoring a scan to a patient, minimizing scan length, use of tube current modulation and minimizing tube current, minimizing-tube potential, iterative reconstruction, and periodic review of CT studies. Organized efforts for standardization have been spearheaded by professional societies such as the American Association of Physicists in Medicine. Finally, all team members should demonstrate an awareness of the importance of minimizing dose. PMID:24589403

  9. Evaluation with low-dose dual-phase helical computed tomography of patients with thyroid lesions

    Institute of Scientific and Technical Information of China (English)

    Li Lin; Wang Yong; Zhao Yanfeng; Zou Shuangmei; Lin Meng; Yu Xiaoduo; Tang Wei

    2014-01-01

    Background The incidence of thyroid cancer has been increasing.Our aim was to evaluate the efficacy of low-dose dualphase helical computed tomography (CT) in the characterization of thyroid lesions,and to discuss the relationship between image characteristics and their pathology.Methods One hundred and six patients with thyroid lesions underwent low-dose dual-phase helical CT after the injection of contrast material.CT scans were obtained at arterial and venous phase with delays of 25 and 65 seconds,and tube current of 60 and 120 mA,respectively.The attenuation change in the lesion between the arterial and venous phase was analyzed and categorized as "increased," "decreased," "mixed" or "no change." Results Histopathologic diagnosis was obtained by surgery in 106 patients (115 lesions).Of the 106 patients,45 had nodular goiter,5 thyroid adenoma,6 thyroiditis,and 50 papillary thyroid carcinoma (PTC) (59 lesions).The attenuation value showed a significant difference (P <0.05) between the arterial and venous phase for the high attenuation area.There was statistical significant difference in terms of attenuation value in high attenuation areas at both phases and in low attenuation areas on arterial phase between nodular goiter and PTC (P <0.05).However,there was no significant difference in attenuation value between adenoma and PTC.Twenty-nine cases (76.3%) of goiter manifested mixed type,3 cases (3/5) of adenoma showed decreased type,6 cases (6/6) of thyroiditis showed increased type,and 55 cases (93.2%) of PTC showed decreased type attenuation.The sensitivity,specificity for thyroid carcinoma by dual-phase CT were 94.9% and 80.4% respectively.The overall diagnostic accuracy for thyroid lesions by dual-phase CT was 87.8%.Conclusions The performance of dual-phase helical CT is related to the pathological structure of the lesions.The analysis of enhancement patterns by using dual-phase helical CT will be helpful in the differential diagnosis of thyroid

  10. Probing the Dynamics of Biomineralization at the Pore Scale Using X-ray Computed Tomography

    Science.gov (United States)

    Armstrong, R. T.; Ajo Franklin, J. B.

    2009-12-01

    Biomineralization is a natural subsurface process that upon stimulation can dramatically affect soil mechanics and hydraulics. This work presents the results of a study where synchrotron based X-Ray Computed Microtomography (CMT) is used to investigate temporal cementation dynamics and the spatial distribution of biogenic CaCO3 at the pore-scale, thus, shedding light on pore clogging and contact cementation. To facilitate these studies we have developed a family of flow-through bioreactors (ID 8 mm) which can be scanned continuously during precipitation experiments. The reactor is also equipped with differential pressure transducers to allow measurement of sample permeability. Porosity permeability correlations, cementation morphology, CaCO3 spatial distribution, and bulk cementation are addressed herein. Sporosarcina pasteurii (formally Bacillus pasteurii), our model organism, is a prevalent aerobic, motile, soil microbe with a very active urease enzyme. Hydrolysis of urea by the urease enzyme generates carbonate ions, ammonium and an increase in pH which favors carbonate precipitation if appropriate metal cations (e.g. Ca2+) are available. Brightfield microscope results show that precipitation occurs within close proximity of the cell membrane reducing microbial motility and forming a CaCO3 precipitate with a "fluffy" appearance. Besides providing an aqueous environment favorable for mineralization S. pasteurii also provides nucleation sites on its cell membrane. Since this microbe is very effective at inducing carbonate precipitation over a relativity short time span (2-3 days), it was used exclusively in our experiments. Prior to CMT imaging the feasibility of temporal imaging was investigated. Viable cell counts taken before and after imaging showed that a considerable amount of bacteria survived the monochromatic (30 KeV) X-ray exposure. Cementation experiments initiated with inoculation of the CMT column with microbes and urea media, cells were allowed to

  11. Low-dose helical computed tomography (CT) in the perioperative workup of adolescent idiopathic scoliosis

    Energy Technology Data Exchange (ETDEWEB)

    Abul-Kasim, Kasim; Overgaard, Angelica; Maly, Pavel [Malmoe University Hospital, Department of Radiology, Section of Neuroradiology, University of Lund, Malmoe (Sweden); Ohlin, Acke [Malmoe University Hospital, Department of Orthopaedic Surgery, University of Lund, Malmoe (Sweden); Gunnarsson, Mikael [Malmoe University Hospital, Department of Radiation Physics, University of Lund, Malmoe (Sweden); Sundgren, Pia C. [University of Michigan Health Systems, Department of Radiology, Division of Neuroradiology, Ann Arbor (United States)

    2009-03-15

    The study aims were to estimate the radiation dose in patients examined with low dose spine CT and to compare it with that received by patients undergoing standard CT for trauma of the same region, as well as to evaluate the impact of dose reduction on image quality. Radiation doses in 113 consecutive low dose spine CTs were compared with those in 127 CTs for trauma. The inter- and intraobserver agreement in measurements of pedicular width, and vertebral rotation, measurements of signal-to-noise ratio and assessment of hardware status were the indicators in the evaluation of image quality. The effective dose of the low dose spine CT (0.37 mSv) was 20 times lower than that of a standard CT for trauma (13.09 mSv). This dose reduction conveyed no impact on image quality. This low dose spine CT protocol allows detailed evaluation that is necessary for preoperative planning and postoperative evaluation. (orig.)

  12. First multimodal embolization particles visible on x-ray/computed tomography and magnetic resonance imaging.

    Science.gov (United States)

    Bartling, Soenke H; Budjan, Johannes; Aviv, Hagit; Haneder, Stefan; Kraenzlin, Bettina; Michaely, Henrik; Margel, Shlomo; Diehl, Steffen; Semmler, Wolfhard; Gretz, Norbert; Schönberg, Stefan O; Sadick, Maliha

    2011-03-01

    Embolization therapy is gaining importance in the treatment of malignant lesions, and even more in benign lesions. Current embolization materials are not visible in imaging modalities. However, it is assumed that directly visible embolization material may provide several advantages over current embolization agents, ranging from particle shunt and reflux prevention to improved therapy control and follow-up assessment. X-ray- as well as magnetic resonance imaging (MRI)-visible embolization materials have been demonstrated in experiments. In this study, we present an embolization material with the property of being visible in more than one imaging modality, namely MRI and x-ray/computed tomography (CT). Characterization and testing of the substance in animal models was performed. To reduce the chance of adverse reactions and to facilitate clinical approval, materials have been applied that are similar to those that are approved and being used on a routine basis in diagnostic imaging. Therefore, x-ray-visible Iodine was combined with MRI-visible Iron (Fe3O4) in a macroparticle (diameter, 40-200 μm). Its core, consisting of a copolymerized monomer MAOETIB (2-methacryloyloxyethyl [2,3,5-triiodobenzoate]), was coated with ultra-small paramagnetic iron oxide nanoparticles (150 nm). After in vitro testing, including signal to noise measurements in CT and MRI (n = 5), its ability to embolize tissue was tested in an established tumor embolization model in rabbits (n = 6). Digital subtraction angiography (DSA) (Integris, Philips), CT (Definition, Siemens Healthcare Section, Forchheim, Germany), and MRI (3 Tesla Magnetom Tim Trio MRI, Siemens Healthcare Section, Forchheim, Germany) were performed before, during, and after embolization. Imaging signal changes that could be attributed to embolization particles were assessed by visual inspection and rated on an ordinal scale by 3 radiologists, from 1 to 3. Histologic analysis of organs was performed. Particles provided a

  13. X-ray computed tomography and additive manufacturing in medicine: a review

    Directory of Open Access Journals (Sweden)

    Thompson Adam

    2017-01-01

    Full Text Available The use of X-ray computed tomography (XCT with additive manufacture (AM within a medical context is examined in this review. The seven AM process families and various XCT scanning techniques are explained in brief, and the use of these technologies together is detailed over time. The transition of these technologies from a simple method of medical modelling to a robust method of customised implant manufacture is described, and the state-of-the-art for XCT and AM is examined in detail. XCT and AM are identified as having the potential to improve gold standards in both modelling and implant production, and in the conclusions of this review, primary barriers to the increased adoption of AM and XCT technologies are identified in reference to the main applications of XCT and AM technologies. The primary prohibitive factors generally relate to the cost of production across all of the examined applications, as well as the need for further clinical trials in surgical guidance and applications involving implantation.

  14. Data fusion in X-ray computed tomography using a superiorization approach.

    Science.gov (United States)

    Schrapp, Michael J; Herman, Gabor T

    2014-05-01

    X-ray computed tomography (CT) is an important and widespread inspection technique in industrial non-destructive testing. However, large-sized and heavily absorbing objects cause artifacts due to either the lack of penetration of the specimen in specific directions or by having data from only a limited angular range of views. In such cases, valuable information about the specimen is not revealed by the CT measurements alone. Further imaging modalities, such as optical scanning and ultrasonic testing, are able to provide data (such as an edge map) that are complementary to the CT acquisition. In this paper, a superiorization approach (a newly developed method for constrained optimization) is used to incorporate the complementary data into the CT reconstruction; this allows precise localization of edges that are not resolvable from the CT data by itself. Superiorization, as presented in this paper, exploits the fact that the simultaneous algebraic reconstruction technique (SART), often used for CT reconstruction, is resilient to perturbations; i.e., it can be modified to produce an output that is as consistent with the CT measurements as the output of unmodified SART, but is more consistent with the complementary data. The application of this superiorized SART method to measured data of a turbine blade demonstrates a clear improvement in the quality of the reconstructed image.

  15. X-ray computed microtomography for drop shape analysis and contact angle measurement.

    Science.gov (United States)

    Santini, Maurizio; Guilizzoni, Manfredo; Fest-Santini, Stephanie

    2013-11-01

    The interaction between an atomized fluid and a solid surface has a great importance in many fields, both in adiabatic conditions and when heat transfer is involved. To investigate the behavior of many drops in contact with a surface, the first step is to study a single one of them and in that, surface wettability is key parameter. Wettability analyses are usually performed by contact angle measurement, in most cases using the sessile drop or captive bubble techniques. Such techniques require optical acquisition of a side view of the drop or bubble, with a series of drawbacks when conventional optics are used, in particular for not uniform, not planar or rough base surfaces. X-ray micro-computed tomography is therefore used to acquire a 3D scan of a drop gently deposited on a surface, with the aim to reconstruct the drop surface and to perform contact angle measurements on true cross-sections of the drop-surface couple. Comparison with contact angle measurements performed on conventional images is performed. The results evidence that the proposed technique is very promising for surface characterization and to get more accurate and detailed information about wettability characteristics.

  16. Relationship of brain imaging with radionuclides and with x-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, D.E.

    1981-03-03

    Because of high sensitivity and specificity for altered local cerebral structure, x-ray computed tomography (CT) is the preferred initial diagnostic imaging study under most circumstances when cerebral disease is suspected. CT has no competitor for detecting fresh intracerebral hemorrhage. Radionuclide imaging (RN) scan is preferred when relative perfusion is to be assessed, in patients allergic to contrast media, and when an adequate CT study is not technically possible. (RN) plays an important complementary role to CT, especially for patients suspected of subacute or chronic subdura hematoma, cerebral infarction, arteriovenous malformations, meningitis, encephalitis, normal pressure hydrocephalus, or when CT findings are inconclusive. When CT is not available, RN serves as a good screening study for suspected cerebral tumor, infection, recent infarction, arteriovenous malformation, and chronic subdural hematoma. Future improvement in radionuclide imaging by means of emission composition potential. The compound plating approacl threshold for all the investigated transistors and fast neutron spectra lies within the raal. The value of the potential slightly changes with the coordinate change in this region, i.e. the charge on a collecting electrode is not practically guided up to a certain moment of time during the movement of nonequilibrium carriers.

  17. A reconstruction method for cone-beam differential x-ray phase-contrast computed tomography.

    Science.gov (United States)

    Fu, Jian; Velroyen, Astrid; Tan, Renbo; Zhang, Junwei; Chen, Liyuan; Tapfer, Arne; Bech, Martin; Pfeiffer, Franz

    2012-09-10

    Most existing differential phase-contrast computed tomography (DPC-CT) approaches are based on three kinds of scanning geometries, described by parallel-beam, fan-beam and cone-beam. Due to the potential of compact imaging systems with magnified spatial resolution, cone-beam DPC-CT has attracted significant interest. In this paper, we report a reconstruction method based on a back-projection filtration (BPF) algorithm for cone-beam DPC-CT. Due to the differential nature of phase contrast projections, the algorithm restrains from differentiation of the projection data prior to back-projection, unlike BPF algorithms commonly used for absorption-based CT data. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a micro-focus x-ray tube source. Moreover, the numerical simulation and experimental results demonstrate that the proposed method can deal with several classes of truncated cone-beam datasets. We believe that this feature is of particular interest for future medical cone-beam phase-contrast CT imaging applications.

  18. Heterogeneous vesiculation of 2011 El Hierro xeno-pumice revealed by X-ray computed microtomography

    Science.gov (United States)

    Berg, S. E.; Troll, V. R.; Deegan, F. M.; Burchardt, S.; Krumbholz, M.; Mancini, L.; Polacci, M.; Carracedo, J. C.; Soler, V.; Arzilli, F.; Brun, F.

    2016-12-01

    During the first week of the 2011 El Hierro submarine eruption, abundant light-coloured pumiceous, high-silica volcanic bombs coated in dark basanite were found floating on the sea. The composition of the light-coloured frothy material (`xeno-pumice') is akin to that of sedimentary rocks from the region, but the textures resemble felsic magmatic pumice, leaving their exact mode of formation unclear. To help decipher their origin, we investigated representative El Hierro xeno-pumice samples using X-ray computed microtomography for their internal vesicle shapes, volumes, and bulk porosity, as well as for the spatial arrangement and size distributions of vesicles in three dimensions (3D). We find a wide range of vesicle morphologies, which are especially variable around small fragments of rock contained in the xeno-pumice samples. Notably, these rock fragments are almost exclusively of sedimentary origin, and we therefore interpret them as relicts an the original sedimentary ocean crust protolith(s). The irregular vesiculation textures observed probably resulted from pulsatory release of volatiles from multiple sources during xeno-pumice formation, most likely by successive release of pore water and mineral water during incremental heating and decompression of the sedimentary protoliths.

  19. X-ray beam hardening correction for measuring density in linear accelerator industrial computed tomography

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ri-Feng; WANG Jue; CHEN Wei-Min

    2009-01-01

    Due to X-ray attenuation being approximately proportional to material density, it is possible to measure the inner density through Industrial Computed Tomography (ICT) images accurately. In practice, however, a number of factors including the non-linear effects of beam hardening and diffuse scattered radia-tion complicate the quantitative measurement of density variations in materials. This paper is based on the linearization method of beam hardening correction, and uses polynomial fitting coefficient which is obtained by the curvature of iron polychromatic beam data to fit other materials. Through theoretical deduction, the paper proves that the density measure error is less than 2% if using pre-filters to make the spectrum of linear accelerator range mainly 0.3 MeV to 3 MeV. Experiment had been set up at an ICT system with a 9 MeV electron linear accelerator. The result is satisfactory. This technique makes the beam hardening correction easy and simple, and it is valuable for measuring the ICT density and making use of the CT images to recognize materials.

  20. X-rays computed tomographic scans of lower limb and trunk muscles in facioscapulohumeral muscular dystrophy

    Energy Technology Data Exchange (ETDEWEB)

    Horikawa, Hirosei; Mano, Yukio; Takayanagi, Tetsuya (Nara Medical Univ., Kashihara (Japan)); Takahashi, Keiichi; Nishio, Hisahide

    1992-10-01

    X-rays computed tomographic (CT) scans of muscles of the lower limbs and the trunk in 14 patients with facioscapulohumeral muscular dystrophy (FSH) were studied. The CT scans showed that the affected muscles were decreased in density and size. The laterality of muscular involvement was sometimes observed. The muscular lesions in the lower limbs showed proximal distribution. In the thigh, the hamstrings were affected first, the adductor muscles second, and then the muscular involvement progressed to the quadriceps femoris muscle. In the lower leg, the gastrocnemius and soleus muscles were relatively spared as compared with the tibialis anterior muscle. In the lumbar girdle, the abdominal muscles were involved first, the gluteal muscles second, the back muscles third, and the psoas major muscle were relatively spared. The muscular weakness of this distribution exacerbated lumbar lordosis. The neck muscles were less affected than those of the lumbar girdle. The CT scans in FSH demonstrated the characteristic pattern of muscular involvement, which differed from the inherited muscular diseases such as Duchenne muscular dystrophy, myotonic dystrophy, and others. (author).

  1. Three Dimensional Digital Sieving of Asphalt Mixture Based on X-ray Computed Tomography

    Directory of Open Access Journals (Sweden)

    Chichun Hu

    2017-07-01

    Full Text Available In order to perform three-dimensional digital sieving based on X-ray computed tomography images, the definition of digital sieve size (DSS was proposed, which was defined as the minimum length of the minimum bounding squares of all possible orthographic projections of an aggregate. The corresponding program was developed to reconstruct aggregate structure and to obtain DSS. Laboratory experiments consisting of epoxy-filled aggregate specimens were conducted to investigate the difference between mechanical sieve analysis and the digital sieving technique. It was suggested that concave surface of aggregate was the possible reason for the disparity between DSS and mechanical sieve size. A comparison between DSS and equivalent diameter was also performed. Moreover, the digital sieving technique was adopted to evaluate the gradation of stone mastic asphalt mixtures. The results showed that the closest proximity of the laboratory gradation curve was achieved by calibrated DSS, among gradation curves based on calibrated DSS, un-calibrated DSS and equivalent diameter.

  2. Volumetric characterization of human patellar cartilage matrix on phase contrast x-ray computed tomography

    Science.gov (United States)

    Abidin, Anas Z.; Nagarajan, Mahesh B.; Checefsky, Walter A.; Coan, Paola; Diemoz, Paul C.; Hobbs, Susan K.; Huber, Markus B.; Wismüller, Axel

    2015-03-01

    Phase contrast X-ray computed tomography (PCI-CT) has recently emerged as a novel imaging technique that allows visualization of cartilage soft tissue, subsequent examination of chondrocyte patterns, and their correlation to osteoarthritis. Previous studies have shown that 2D texture features are effective at distinguishing between healthy and osteoarthritic regions of interest annotated in the radial zone of cartilage matrix on PCI-CT images. In this study, we further extend the texture analysis to 3D and investigate the ability of volumetric texture features at characterizing chondrocyte patterns in the cartilage matrix for purposes of classification. Here, we extracted volumetric texture features derived from Minkowski Functionals and gray-level co-occurrence matrices (GLCM) from 496 volumes of interest (VOI) annotated on PCI-CT images of human patellar cartilage specimens. The extracted features were then used in a machine-learning task involving support vector regression to classify ROIs as healthy or osteoarthritic. Classification performance was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC). The best classification performance was observed with GLCM features correlation (AUC = 0.83 +/- 0.06) and homogeneity (AUC = 0.82 +/- 0.07), which significantly outperformed all Minkowski Functionals (p GLCM-derived statistical features can distinguish between healthy and osteoarthritic tissue with high accuracy.

  3. A minute fossil phoretic mite recovered by phase-contrast X-ray computed tomography.

    Science.gov (United States)

    Dunlop, Jason A; Wirth, Stefan; Penney, David; McNeil, Andrew; Bradley, Robert S; Withers, Philip J; Preziosi, Richard F

    2012-06-23

    High-resolution phase-contrast X-ray computed tomography (CT) reveals the phoretic deutonymph of a fossil astigmatid mite (Acariformes: Astigmata) attached to a spider's carapace (Araneae: Dysderidae) in Eocene (44-49 Myr ago) Baltic amber. Details of appendages and a sucker plate were resolved, and the resulting three-dimensional model demonstrates the potential of tomography to recover morphological characters of systematic significance from even the tiniest amber inclusions without the need for a synchrotron. Astigmatids have an extremely sparse palaeontological record. We confirm one of the few convincing fossils, potentially the oldest record of Histiostomatidae. At 176 µm long, we believe this to be the smallest arthropod in amber to be CT-scanned as a complete body fossil, extending the boundaries for what can be recovered using this technique. We also demonstrate a minimum age for the evolution of phoretic behaviour among their deutonymphs, an ecological trait used by extant species to disperse into favourable environments. The occurrence of the fossil on a spider is noteworthy, as modern histiostomatids tend to favour other arthropods as carriers.

  4. Computer assisted gamma and X-ray tomography: Applications to multiphase flow systems

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S.B.; Dudukovic, M.

    1998-01-01

    In process vessels, involving two or three phases it is often important not only to know the volume fraction (holdup) of each phase but also the spatial distribution of such holdups. This information is needed in control, trouble shooting and assessment of flow patterns and can be observed noninvasively by the application of Computed Tomography (CT). This report presents a complete overview of X-ray and gamma ray transmission tomography principles, equipment design to specific tasks and application in process industry. The fundamental principles of tomography, the algorithms for image reconstruction, the measurement method and the possible sources of error are discussed in detail. A case study highlights the methodology involved in designing a scanning system for the study of a given process unit, e.g., reactor, separations column etc. Results obtained in the authors` laboratory for the gas holdup distribution in bubble columns are also presented. Recommendations are made for the Advanced Fuels Development Unit (AFDU) in LaPorte, TX.

  5. A convolutional neural network approach to calibrating the rotation axis for X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaogang; De Carlo, Francesco; Phatak, Charudatta; Gürsoy, Dogˇa

    2017-01-24

    This paper presents an algorithm to calibrate the center-of-rotation for X-ray tomography by using a machine learning approach, the Convolutional Neural Network (CNN). The algorithm shows excellent accuracy from the evaluation of synthetic data with various noise ratios. It is further validated with experimental data of four different shale samples measured at the Advanced Photon Source and at the Swiss Light Source. The results are as good as those determined by visual inspection and show better robustness than conventional methods. CNN has also great potential forreducing or removingother artifacts caused by instrument instability, detector non-linearity,etc. An open-source toolbox, which integrates the CNN methods described in this paper, is freely available through GitHub at tomography/xlearn and can be easily integrated into existing computational pipelines available at various synchrotron facilities. Source code, documentation and information on how to contribute are also provided.

  6. Analytical computation of stray light in nested mirror modules for X-ray telescopes

    CERN Document Server

    Spiga, Daniele

    2016-01-01

    Stray light in X-ray telescopes is a well-known issue. Unlike rays focused via a double reflection by usual grazing-incidence geometries such as the Wolter-I, stray rays coming from off-axis sources are reflected only once by either the parabolic or the hyperbolic segment. Although not focused, stray light may represent a major source of background and ghost images especially when observing a field of faint sources in the vicinities of another, more intense, just outside the field of view of the telescope. The stray light problem is faced by mounting a pre-collimator in front of the mirror module, in order to shade a part of the reflective surfaces that may give rise to singly-reflected rays. Studying the expected stray light impact, and consequently designing a pre-collimator, is a typical ray-tracing problem, usually time and computation consuming, especially if we consider that rays propagate throughout a densely nested structure. This in turn requires one to pay attention to all the possible obstructions,...

  7. Revealing Soil Structure and Functional Macroporosity along a Clay Gradient Using X-ray Computed Tomography

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Møldrup, Per; Arthur, Emmanuel

    2013-01-01

    The influence of clay content in soil-pore structure development and the relative importance of macroporosity in governing convective fluid flow are two key challenges toward better understanding and quantifying soil ecosystem functions. In this study, soil physical measurements (soil......-water retention and air permeability) and x-ray computed tomography (CT) scanning were combined and used from two scales on intact soil columns (100 and 580 cm3). The columns were sampled along a natural clay gradient at six locations (L1, L2, L3, L4, L5 and L6 with 0.11, 0.16, 0.21, 0.32, 0.38 and 0.46 kg kg−1...... clay content, respectively) at a field site in Lerbjerg, Denmark. The water-holding capacity of soils markedly increased with increasing soil clay content, while significantly higher air permeability was observed for the L1 to L3 soils than for the L4 to L6 soils. Higher air permeability values...

  8. Computer simulations of X-ray six-beam diffraction in a perfect silicon crystal. I.

    Science.gov (United States)

    Kohn, V G; Khikhlukha, D R

    2016-05-01

    This paper reports computer simulations of the transmitted-beam intensity distribution for the case of six-beam (000, 220, 242, 044, -224, -202) diffraction of X-rays in a perfect silicon crystal of thickness 1 mm. Both the plane-wave angular dependence and the six-beam section topographs, which are usually obtained in experiments with a restricted beam (two-dimensional slit), are calculated. The angular dependence is calculated in accordance with Ewald's theory. The section topographs are calculated from the angular dependence by means of the fast Fourier transformation procedure. This approach allows one to consider, for the first time, the transformation of the topograph's structure due to the two-dimensional slit sizes and the distance between the slit and the detector. The results are in good agreement with the results of other works and with the experimental data. This method of calculation does not require a supercomputer and it was performed on a standard laptop. A detailed explanation of the main features of the diffraction patterns at different distances between the slit and the detector is presented.

  9. Studying fatigue damage evolution in uni-directional composites using x-ray computed tomography

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    , it will be possible to lower the costs of energy for wind energy based electricity. In the present work, a lab-source x-ray computed tomography equipment (Zeiss Xradia 520 Versa) has been used in connection with ex-situ fatigue testing of uni-directional composites in order to identify fibre failure during...... the fatigue loading. The load carrying laminates in wind turbine blades is typically based on a number of non-crimp fabrics in which the load carrying fibres are oriented in the axial direction of the blades. In order to ease the handling of the fabric during the dry fabric layup and to ensure a good...... alignment of the final laminates, approximately 10% of the fibres are oriented in secondary directions as so-called backing bundles and stitched to the uni-directionally oriented bundles. Due to the coarse structure of the non-crimp fabric, test samples with a larger cross-section (compared to other...

  10. Mirrors for X-ray telescopes: Fresnel diffraction-based computation of Point Spread Functions from metrology

    CERN Document Server

    Raimondi, Lorenzo

    2014-01-01

    The imaging sharpness of an X-ray telescope is chiefly determined by the optical quality of its focusing optics, which in turn mostly depends on the shape accuracy and the surface finishing of the grazing incidence X-ray mirrors that compose the optical modules. In order to ensure the imaging performance during the mirror manufacturing, a fundamental step is represented by the prediction of the mirror Point Spread Function (PSF) from the metrology of its surface. Traditionally, the PSF computation in X-rays is assumed to be different depending on whether the surface defects are classified as figure errors or roughness [...] The aim of this work is to overcome this limit, providing analytical formulae, valid at any light wavelength, to compute the PSF of an X-ray mirror shell from the measured longitudinal profiles and the roughness Power Spectral Density (PSD), without distinguishing spectral ranges with different treatments. The method we adopted is based on the Huygens-Fresnel principle to compute the diffr...

  11. Three-dimensional pore space quantification of apple tissue using X-ray computed microtomography.

    Science.gov (United States)

    Mendoza, Fernando; Verboven, Pieter; Mebatsion, Hibru K; Kerckhofs, Greet; Wevers, Martine; Nicolaï, Bart

    2007-08-01

    The microstructure and the connectivity of the pore space are important variables for better understanding of the complex gas transport phenomena that occur in plant tissues. In this study, we present an experimental procedure for image acquisition and image processing to quantitatively characterize in 3D the pore space of apple tissues (Malus domestica Borkh.) for two cultivars (Jonagold and Braeburn) taken from the fleshy part of the cortex using X-ray computer microtomography. Preliminary sensitivity analyses were performed to determine the effect of the resolution and the volume size (REV, representative elementary volume analysis) on the computed porosity of apple samples. For comparison among cultivars, geometrical properties such as porosity, specific surface area, number of disconnected pore volumes and their distribution parameters were extracted and analyzed in triplicate based on the 3D skeletonization of the pore space (medial axis analysis). The results showed that microtomography provides a resolution at the micrometer level to quantitatively analyze and characterize the 3D topology of the pore space in apple tissue. The computed porosity was confirmed to be highly dependent of the resolution used, and the minimum REV of the cortical flesh of apple fruit was estimated to be 1.3 mm(3). Comparisons among the two cultivars using a resolution of 8.5 mum with a minimum REV cube showed that in spite of the complexity and variability of the pore space network observed in Jonagold and Braeburn apples, the extracted parameters from the medial axis were significantly different (P-value < 0.05). Medial axis parameters showed potential to differentiate the microstructure between the two evaluated apple cultivars.

  12. Computer-Controlled Cylindrical Polishing Process for Large X-Ray Mirror Mandrels

    Science.gov (United States)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    We are developing high-energy grazing incidence shell optics for hard-x-ray telescopes. The resolution of a mirror shells depends on the quality of cylindrical mandrel from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation software is developed to model the residual surface figure errors of a mandrel due to the polishing process parameters and the tools used, as well as to compute the optical performance of the optics. The study carried out using the developed software was focused on establishing a relationship between the polishing process parameters and the mid-spatial-frequency error generation. The process parameters modeled are the speeds of the lap and the mandrel, the tool s influence function, the contour path (dwell) of the tools, their shape and the distribution of the tools on the polishing lap. Using the inputs from the mathematical model, a mandrel having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. The preliminary results of a series of polishing experiments demonstrate a qualitative agreement with the developed model. We report our first experimental results and discuss plans for further improvements in the polishing process. The ability to simulate the polishing process is critical to optimize the polishing process, improve the mandrel quality and significantly reduce the cost of mandrel production

  13. Analysis of computed X-ray tomography of the brain in incontinence patients with senile dementia

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yasuyuki; Machida, Toyohei; Oishi, Yukihiko (Jikei Univ., Tokyo (Japan). School of Medicine); Kamachi, Chikahumi; Okabe, Tsutomu; Akazawa, Kouhei; Takasaka, Satoshi

    1994-02-01

    To evaluate the condition of incontinence in patients with senile dementia, we performed computed tomography X-rays to the brain and analyzed the relationship among the circulatory defect of the brain, the brain atrophy and the degree of incontinence. There were 92 patients subjected to this study who were hospitalised due to senile dementia; 74 patients had vascular dementia, 10 patients had senile dementia of Alzheimer type, and 8 patients had the mixed type. (age range: 54-95 years; mean: 80.3 years). The degree of incontinence in these patients varied as follows: 18 patients with continence, 16 patients with moderate incontinence, 58 patients with total incontinence. The diagnosis of circulatory defect of the brain was based on computed tomography observation of periventricular lucency (P.V.L.), and the degree of brain atrophy was evaluated based on 4 criteria: the Lateral body ratio, the Huckman number, the Evans ratio, and the enlargement of the subarachnoid space. Among the 92 patients, P.V.L. was present in 31 patients, among them 27 patients suffered from incontinence. There was a significant correlation between P.V.L. and incontinence (p<0.001). As the incontinence progressively worsened (Continence, Moderate incontinence, Total incontinence), the lateral body ratio increased to 24.8, 27.8, 28.6, (p<0.05). The Huckman number also increased to 18.3, 19.3, 21.3, (p<0.01), and the evans ratio likewise 29.9, 32.3, 33.7 (p<0.01). The enlargement of the subarachnoid space was also correlated with the severity of incontinence. We conclude that urinary incontinence originating from senile dememtia is connected to brain atrophy and is strongly influenced by the circulatory disorders of the brain. (author).

  14. Characterization of feed channel spacer performance using geometries obtained by X-ray computed tomography

    KAUST Repository

    Haaksman, Viktor A.

    2016-09-09

    Spiral-wound membrane modules used in water treatment for water reuse and desalination make use of spacer meshes for keeping the membrane leaves apart and for enhancing the mass transfer. Computational fluid dynamics (CFD) has gained importance in the design of new spacers with optimized hydrodynamic characteristics, but this requires a precise description of the spacer geometry. This study developed a method to obtain accurate three-dimensional (3-D) geometry representations for any given spacer design from X-ray computed tomography (CT) scans. The method revealed that the filaments of industrial spacers have a highly variable cross-section size and shape, which impact the flow characteristics in the feed channel. The pressure drop and friction factors were calculated from numerical simulations on five commercially available feed spacers used in practice. Model solutions compared well to experimental data measured using a flow cell for average velocities up to 0.2 m/s, as used in industrial reverse osmosis and nanofiltration membrane operations. A newly-proposed spacer geometry with alternating strand thickness was tested, which was found to yield a lower pressure drop while being highly efficient in converting the pumping power into membrane shear. Numerical model solutions using CFD with geometries from CT scans were closer to measurements than those obtained using the traditional circular cross-section strand simplification, indicating that CT scans are very well suitable to approximate real feed spacer geometries. By providing detailed insight on the spacer filament shape, CT scans allow better quantification of local distribution of velocity and shear, possibly leading to more accurate estimations of fouling and concentration polarization. © 2016 Elsevier B.V.

  15. Increased apoptosis and DNA double-strand breaks in the embryonic mouse brain in response to very low-dose X-rays but not 50 Hz magnetic fields

    OpenAIRE

    Saha, Shreya; Woodbine, Lisa; Haines, Jacqueline; Coster, Margaret; Ricket, Nicole; Barazzuol, Lara; Ainsbury, Elizabeth; Sienkiewicz, Zenon; Jeggo, Penny

    2014-01-01

    The use of X-rays for medical diagnosis is enhancing exposure to low radiation doses. Exposure to extremely low-frequency electromagnetic or magnetic fields is also increasing. Epidemiological studies show consistent associations of childhood leukaemia with exposure to magnetic fields but any causal relationship is unclear. A limitation in assessing the consequence of such exposure is the availability of sensitive assays. The embryonic neuronal stem and progenitor cell compartments are radios...

  16. Characteristics of changes in the number of yH2AX and Rad51 protein foci in human skin fibroblasts after prolonged exposure to low-dose rate X-ray radiation

    Directory of Open Access Journals (Sweden)

    Ozerov I.V.

    2014-12-01

    Full Text Available Aim: to compare the repair process of DNA double-strand breaks in mammalian cells after acute versus prolonged exposure to X-ray irradiation with different dose rates. Material and methods. Studies were performed on primary human fibroblasts isolated from skin biopsies of healthy volunteers (women, 29 and 30 years. Cells were irradiated using an X-ray machine RUB RUST-M1 (JSC "Ruselectronics", Moscow, Russia at 37°C temperature with a dose rate of 400 mGy/min (200 kV, 2*2.4 mA, a filter of 1.5mm AI or 4 mGy/min (50 kV, 2*0.4 mA, a filter of 1.5 mm AI. Immuno-cytochemical protein staining was utilized for yH2AX and Rad51 foci analysis. Results. Phosphorylated histone H2AX (yH2AX and the key protein of homologous recombination Rad51 foci formation and disappearance kinetics were investigated simultaneously in primary human dermal fibroblasts after acute and prolonged exposure to X-ray radiation at a same dose. It was shown that the relative yield of yH2AX foci per dose reduces with decrease in dose rate, while the relative yield of Rad51 foci conversely increases. Conclusion. Our findings suggest the fundamental differences in the ratio of non-homologous end joining and homologous recombination DNA repair in acute versus prolonged irradiated cells.

  17. DETERMINATION OF HLW GLASS MELT RATE USING X-RAY COMPUTED TOMOGRAPHY

    Energy Technology Data Exchange (ETDEWEB)

    Choi, A.; Miller, D.; Immel, D.

    2011-10-06

    , a significant amount of glassy material interspersed among the gas bubbles will be excluded, thus underestimating the melt rate. Likewise, if they are drawn too high, many large voids will be counted as glass, thus overestimating the melt rate. As will be shown later in this report, there is also no guarantee that a given distribution of glass and gas bubbles along a particular sectioned plane will always be representative of the entire sample volume. Poor reproducibility seen in some LMR data may be related to these difficulties of the visual method. In addition, further improvement of the existing melt rate model requires that the overall impact of feed chemistry on melt rate be reflected on measured data at a greater quantitative resolution on a more consistent basis than the visual method can provide. An alternate method being pursued is X-ray computed tomography (CT). It involves X-ray scanning of glass samples, performing CT on the 2-D X-ray images to build 3-D volumetric data, and adaptive segmentation analysis of CT results to not only identify but quantify the distinct regions within each sample based on material density and morphologies. The main advantage of this new method is that it can determine the relative local density of the material remaining in the beaker after the heat treatment regardless of its morphological conditions by selectively excluding all the voids greater than a given volumetric pixel (voxel) size, thus eliminating much of the subjectivity involved in the visual method. As a result, the melt rate data obtained from CT scan will give quantitative descriptions not only on the fully-melted glass, but partially-melted and unmelted feed materials. Therefore, the CT data are presumed to be more reflective of the actual melt rate trends in continuously-fed melters than the visual data. In order to test the applicability of X-ray CT scan to the HLW glass melt rate study, several new series of HLW simulant/frit mixtures were melted in the

  18. Improving early diagnosis of pulmonary infections in patients with febrile neutropenia using low-dose chest computed tomography

    NARCIS (Netherlands)

    Gerritsen, M G; Willemink, M J; Pompe, E; van der Bruggen, T; van Rhenen, A; Lammers, J W J|info:eu-repo/dai/nl/071697624; Wessels, F; Sprengers, R W; de Jong, Pim|info:eu-repo/dai/nl/287955672; Minnema, M C|info:eu-repo/dai/nl/171618149

    2017-01-01

    We performed a prospective study in patients with chemotherapy induced febrile neutropenia to investigate the diagnostic value of low-dose computed tomography compared to standard chest radiography. The aim was to compare both modalities for detection of pulmonary infections and to explore

  19. A computer simulation platform for the estimation of measurement uncertainties in dimensional X-ray computed tomography

    DEFF Research Database (Denmark)

    Hiller, Jochen; Reindl, Leonard M

    2012-01-01

    into account the main error sources for the measurement. This method has the potential to deal with all kinds of systematic and random errors that influence a dimensional CT measurement. A case study demonstrates the practical application of the VCT simulator using numerically generated CT data and statistical......The knowledge of measurement uncertainty is of great importance in conformance testing in production. The tolerance limit for production must be reduced by the amounts of measurement uncertainty to ensure that the parts are in fact within the tolerance. Over the last 5 years, industrial X......-ray computed tomography (CT) has become an important technology for dimensional quality control. In this paper a computer simulation platform is presented which is able to investigate error sources in dimensional CT measurements. The typical workflow in industrial CT metrology is described and methods...

  20. A brief measure of Smokers' knowledge of lung cancer screening with low-dose computed tomography

    Directory of Open Access Journals (Sweden)

    Lisa M. Lowenstein

    2016-12-01

    Full Text Available We describe the development and psychometric properties of a new, brief measure of smokers' knowledge of lung cancer screening with low-dose computed tomography (LDCT. Content experts identified key facts smokers should know in making an informed decision about lung cancer screening. Sample questions were drafted and iteratively refined based on feedback from content experts and cognitive testing with ten smokers. The resulting 16-item knowledge measure was completed by 108 heavy smokers in Houston, Texas, recruited from 12/2014 to 09/2015. Item difficulty, item discrimination, internal consistency and test-retest reliability were assessed. Group differences based upon education levels and smoking history were explored. Several items were dropped due to ceiling effects or overlapping constructs, resulting in a 12-item knowledge measure. Additional items with high item uncertainty were retained because of their importance in informed decision making about lung cancer screening. Internal consistency reliability of the final scale was acceptable (KR-20 = 0.66 and test-retest reliability of the overall scale was 0.84 (intraclass correlation. Knowledge scores differed across education levels (F = 3.36, p = 0.04, while no differences were observed between current and former smokers (F = 1.43, p = 0.24 or among participants who met or did not meet the 30-pack-year screening eligibility criterion (F = 0.57, p = 0.45. The new measure provides a brief, valid and reliable indicator of smokers' knowledge of key concepts central to making an informed decision about lung cancer screening with LDCT, and can be part of a broader assessment of the quality of smokers' decision making about lung cancer screening.

  1. X-ray phase computed tomography for nanoparticulated imaging probes and therapeutics: preliminary feasibility study

    Science.gov (United States)

    Tang, Xiangyang; Yang, Yi; Tang, Shaojie

    2011-03-01

    With the scientific progress in cancer biology, pharmacology and biomedical engineering, the nano-biotechnology based imaging probes and therapeutical agents (namely probes/agents) - a form of theranostics - are among the strategic solutions bearing the hope for the cure of cancer. The key feature distinguishing the nanoparticulated probes/agents from their conventional counterparts is their targeting capability. A large surface-to-volume ratio in nanoparticulated probes/agents enables the accommodation of multiple targeting, imaging and therapeutic components to cope with the intra- and inter-tumor heterogeneity. Most nanoparticulated probes/agents are synthesized with low atomic number materials and thus their x-ray attenuation are very similar to biological tissues. However, their microscopic structures are very different, which may result in significant differences in their refractive properties. Recently, the investigation in the x-ray grating-based differential phase contrast (DPC) CT has demonstrated its advantages in differentiating low-atomic materials over the conventional attenuation-based CT. We believe that a synergy of x-ray grating-based DPC CT and nanoparticulated imaging probes and therapeutic agents may play a significant role in extensive preclinical and clinical applications, or even become a modality for molecular imaging. Hence, we propose to image the refractive property of nanoparticulated imaging probes and therapeutical agents using x-ray grating-based DPC CT. In this work, we conduct a preliminary feasibility study with a focus to characterize the contrast-to-noise ratio (CNR) and contrast-detail behavior of the x-ray grating-based DPC CT. The obtained data may be instructive to the architecture design and performance optimization of the x-ray grating-based DPC CT for imaging biomarker-targeted imaging probes and therapeutic agents, and even informative to the translation of preclinical research in theranostics into clinical applications.

  2. X-ray computed tomography in the post treatment evaluation of carcinoma of the cervix

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Hiroshi

    1988-12-01

    The diagnostic value of X-ray computed tomography scan for early detection of recurrence and/or metastasis were analyzed as an index of a sensitivity, a specificity, a positive predictive value, a negative predictive value and an accuracy among one hundred and thirty-one patients with carcinoma of the cervix as part of post-treatment evaluation during a period from 1980 to 1987. The diagnostic points of CT scan was the following criteria which including (1) parametrial involvement, (2) enlargement of uterine cervix, (3) invasion to vaginal wall, (4) bladder and/or rectal invasion, (5) pyometra, (6) enlargement of pelvic and/or paraaortic lymph nodes, (7) laterality of pelvic muscle, (8) intrapelvic abnormal shadow or ascites retension, (9) hydronephrosis, and (10) distant metastasis. (1) Among the patients treated with surgery, accuracy of each diagnostic point for early detection of recurrence was as follows: (8) 73%, (6) 60%, (9) 47%, (10) 47%, (3) 40%, (1) 33%, (4) 27%, (7) 27%, respectively. (2) Among the patients reated with radiotherapy, accuracy of each diagnostic point for early detection of recurrence was as follws: (1) 65%, (8) 64%, (5) 63%, (4) 61%, (10) 58%, (6) 55%, (9) 53%, (2) 42%, (3) 41%, (7) 41%, respectively. (3) Among the patients treated with surgery and radiotherapy, accuracy of each diagnostic point for early detection of recurrence was as follows: (8) 76%, (10) 76%, (9) 57%, (6) 52%, (1) 48%, (4) 43%, (7) 33%, (3) 19%, respectively. In conclusion, CT findings such as paraaortic lymphadenopathy and invasion to vaginal wall including distant metastasis were most important for early detection of recurrence during the follow-up study.

  3. Developing advanced X-ray scattering methods combined with crystallography and computation.

    Science.gov (United States)

    Perry, J Jefferson P; Tainer, John A

    2013-03-01

    The extensive use of small angle X-ray scattering (SAXS) over the last few years is rapidly providing new insights into protein interactions, complex formation and conformational states in solution. This SAXS methodology allows for detailed biophysical quantification of samples of interest. Initial analyses provide a judgment of sample quality, revealing the potential presence of aggregation, the overall extent of folding or disorder, the radius of gyration, maximum particle dimensions and oligomerization state. Structural characterizations include ab initio approaches from SAXS data alone, and when combined with previously determined crystal/NMR, atomistic modeling can further enhance structural solutions and assess validity. This combination can provide definitions of architectures, spatial organizations of protein domains within a complex, including those not determined by crystallography or NMR, as well as defining key conformational states of a protein interaction. SAXS is not generally constrained by macromolecule size, and the rapid collection of data in a 96-well plate format provides methods to screen sample conditions. This includes screening for co-factors, substrates, differing protein or nucleotide partners or small molecule inhibitors, to more fully characterize the variations within assembly states and key conformational changes. Such analyses may be useful for screening constructs and conditions to determine those most likely to promote crystal growth of a complex under study. Moreover, these high throughput structural determinations can be leveraged to define how polymorphisms affect assembly formations and activities. This is in addition to potentially providing architectural characterizations of complexes and interactions for systems biology-based research, and distinctions in assemblies and interactions in comparative genomics. Thus, SAXS combined with crystallography/NMR and computation provides a unique set of tools that should be considered

  4. Interstitial pneumonitis in patients with systemic sclerosis. Analysis by chest x-ray high-resolution computed tomography (HRCT)

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Kana [Toho Univ., Tokyo (Japan). School of Medicine

    1999-01-01

    Systemic sclerosis (SSc) is a severe systemic collagen vascular disease of unknown cause characterized by marked vascular and connective tissue abnormalities in the skin and other organs. The lungs are frequently involved in patients with SSc, and pulmonary disease continues to be a significant cause of morbidity and mortality. High-resolution computed tomography (HRCT) is a sensitive technique potentially useful in detecting occult interstitial lung disease in patients with SSc. In the present study, chest X-ray HRCT findings were analyzed in 26 SSc patients in order to identify the characteristic morphological changes of interstitial pneumonitis in SSc patients. Interstitial pneumonitis was found in 21 patients (81%) with SSc. Chest X-ray CT findings in SSc patients were quite uniform and were characterized by sharply bordering dense attenuation and the predominance of ring-like lesions. Main lesions were located in the lower and posterior lung fields in a peripheral lobular pattern. There was no correlation between the extent of the interstitial lung disease and the duration from onset of SSc. In conclusion, it was found that, in patients with SSc, interstitial pneumonitis can be identified by characteristic chest X-ray CT findings. Furthermore, analysis of chest X-ray CT findings is useful in assessing the severity, clinical course and prognosis of patients with SSc. (author)

  5. Experimental Realisation of High-sensitivity Laboratory X-ray Grating-based Phase-contrast Computed Tomography.

    Science.gov (United States)

    Birnbacher, Lorenz; Willner, Marian; Velroyen, Astrid; Marschner, Mathias; Hipp, Alexander; Meiser, Jan; Koch, Frieder; Schröter, Tobias; Kunka, Danays; Mohr, Jürgen; Pfeiffer, Franz; Herzen, Julia

    2016-04-04

    The possibility to perform high-sensitivity X-ray phase-contrast imaging with laboratory grating-based phase-contrast computed tomography (gbPC-CT) setups is of great interest for a broad range of high-resolution biomedical applications. However, achieving high sensitivity with laboratory gbPC-CT setups still poses a challenge because several factors such as the reduced flux, the polychromaticity of the spectrum, and the limited coherence of the X-ray source reduce the performance of laboratory gbPC-CT in comparison to gbPC-CT at synchrotron facilities. In this work, we present our laboratory X-ray Talbot-Lau interferometry setup operating at 40 kVp and describe how we achieve the high sensitivity yet unrivalled by any other laboratory X-ray phase-contrast technique. We provide the angular sensitivity expressed via the minimum resolvable refraction angle both in theory and experiment, and compare our data with other differential phase-contrast setups. Furthermore, we show that the good stability of our high-sensitivity setup allows for tomographic scans, by which even the electron density can be retrieved quantitatively as has been demonstrated in several preclinical studies.

  6. Tuberculosis contact investigation using interferon-gamma release assay with chest x-ray and computed tomography.

    Science.gov (United States)

    Fujikawa, Akira; Fujii, Tatsuya; Mimura, Satoshi; Takahashi, Ryota; Sakai, Masao; Suzuki, Shinya; Kyoto, Yukishige; Uwabe, Yasuhide; Maeda, Shinji; Mori, Toru

    2014-01-01

    Between September 2009 and January 2010, 6 members of the Japanese Eastern Army, who had completed the same training program, were diagnosed with active tuberculosis (TB) on different occasions. The Ministry of Defense conducted a contact investigation of all members who had come into contact with the infected members. The purpose of this study was to verify the efficacy of the TB screening protocol used in this investigation. A total of 884 subjects underwent interferon-gamma release assay (IGRA) and chest X-ray. The 132 subjects who were IGRA positive or with X-ray findings suggestive of TB subsequently underwent chest computer tomography (CT). Chest CT was performed for 132 subjects. Based on CT findings, 24 (2.7%) subjects were classified into the active TB group, 107 (12.1%) into the latent tuberculosis infection (LTBI) group, and 753 (85.2%) into the non-TB group. The first 2 groups underwent anti-TB therapy, and all 3 groups were followed for 2 years after treatment. Although one subject in the active TB group experienced relapse during the follow-up period, no patient in the LTBI or non-TB groups developed TB. IGRA and chest X-ray, followed by chest CT for those IGRA positive or with suspicious X-ray findings, appears to be an effective means of TB contact screening and infection prevention.

  7. Automatic coronary calcium scoring in low-dose chest computed tomography

    NARCIS (Netherlands)

    Isgum, I.; Prokop, M.; Niemeijer, M.; Viergever, M.; Ginneken, B. van

    2012-01-01

    The calcium burden as estimated from non-ECGsynchronized CT exams acquired in screening of heavy smokers has been shown to be a strong predictor of cardiovascular events. We present a method for automatic coronary calcium scoring with low-dose, non-contrast-enhanced, non-ECG-synchronized chest CT. F

  8. Computational dosimetry of a simulated combined standard X-Rays and BNCT treatment

    Energy Technology Data Exchange (ETDEWEB)

    Casal, M.R., E-mail: mcasal@cnea.gov.ar [Instituto de Oncologia ' Angel H. Roffo' , Universidad de Buenos Aires, Av. San Martin 5481, Bs.As. (Argentina)] [Comision Nacional de Energia Atomica, Av. General Paz 1499, San Martin, Buenos Aires (Argentina); Herrera, M.S., E-mail: mariettaherrera@gmail.com [Comision Nacional de Energia Atomica, Av. General Paz 1499, San Martin, Buenos Aires (Argentina)] [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) Av. Rivadavia 191, Buenos Aires (Argentina)] [Escuela de Ciencia y Tecnologia, Universidad de General San Martin, 25 de Mayo and M. de Irigoyen, San Martin (Argentina); Gonzalez, S.J., E-mail: srgonzal@cnea.gov.ar [Comision Nacional de Energia Atomica, Av. General Paz 1499, San Martin, Buenos Aires (Argentina)] [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) Av. Rivadavia 191, Buenos Aires (Argentina)

    2011-12-15

    There has been increasing interest in combining Boron Neutron Capture Therapy (BNCT) with standard radiotherapy, either concomitantly or as a BNCT treatment of a recurrent tumor that was previously irradiated with a medical electron linear accelerator (LINAC). In this work we report the simulated dosimetry of treatments combining X-rays and BNCT

  9. High pressure behaviour of TbN: an X-ray diffraction and computational study

    DEFF Research Database (Denmark)

    Jakobsen, J.M.; Madsen, G.K.H.; Jorgensen, J.E.;

    2002-01-01

    In the present work, we report an X-ray powder diffraction study of TbN up to an applied hydrostatic pressure of 43 GPa. TbN was found to be stable in the 131 (NaCl structure) within the examined pressure interval, and the zero pressure bulk modulus was determined to be 176(7) GPa. The electronic...

  10. X-ray Digital Radiography and Computed Tomography of ICF and HEDP Materials, Subassemblies and Targets

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W D; Martz Jr., H E

    2006-05-31

    Inertial confinement fusion (ICF) and high energy density physics (HEDP) research are being conducted at large laser facilities, such as the University of Rochester's Laboratory for Laser Energetics OMEGA facility and the Lawrence Livermore National Laboratory's (LLNL) National Ignition Facility (NIF). At such facilities, millimeter-sized targets with micrometer structures are studied in a variety of hydrodynamic, radiation transport, equation-of-state, inertial confinement fusion and high-energy density experiments. The extreme temperatures and pressures achieved in these experiments make the results susceptible to imperfections in the fabricated targets. Targets include materials varying widely in composition ({approx}3 < Z < {approx}82), density ({approx}0.03 to {approx}20 g/cm{sup 3}), geometry (planar to spherical) and embedded structures (joints to subassemblies). Fabricating these targets with structures to the tolerances required is a challenging engineering problem the ICF and HEDP community are currently undertaking. Nondestructive characterization (NDC) provides a valuable tool in material selection, component inspection, and the final pre-shot assemblies inspection. X-rays are a key method used to NDC these targets. In this paper we discuss X-ray attenuation, X-ray phase effects, and the X-ray system used, its performance and application to characterize low-temperature Raleigh-Taylor and non-cryogenic double-shell targets.

  11. Computer-based training increases efficiency in x-ray image : Interpretation by aviation security screeners

    NARCIS (Netherlands)

    Michel, S.; Ruiter, C.J. de; Hogervorst, M.A.; Koller, S.M.; Moerland, R.; Schwaninger, R.A.

    2007-01-01

    X-Ray screening of passenger bags is an essential component of airport security. Large investments into technology have been made in recent years. However, the most expensive equipment is of limited value, if th humans who operate it are not selected and trained appropriately. Scientific studies hav

  12. Concept of effective atomic number and effective mass density in dual-energy X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bonnin, Anne, E-mail: annebonnin@free.fr [ESRF, 6 Jules Horowitz, F-38073 Grenoble Cedex (France); LVA, Vibrations and Acoustic Laboratory, INSA-Lyon, Université de Lyon, F-69621 Villeurbanne Cedex (France); Duvauchelle, Philippe, E-mail: philippe.duvauchelle@insa-lyon.fr [LVA, Vibrations and Acoustic Laboratory, INSA-Lyon, Université de Lyon, F-69621 Villeurbanne Cedex (France); Kaftandjian, Valérie [LVA, Vibrations and Acoustic Laboratory, INSA-Lyon, Université de Lyon, F-69621 Villeurbanne Cedex (France); Ponard, Pascal [Thales Electron Devices SAS, 2 Rue Marcel Dassault, BP23 78141 Vélizy, Villacoublay Cedex (France)

    2014-01-01

    This paper focuses on dual-energy X-ray computed tomography and especially the decomposition of the measured attenuation coefficient in a mass density and atomic number basis. In particular, the concept of effective atomic number is discussed. Although the atomic number is well defined for chemical elements, the definition of an effective atomic number for any compound is not an easy task. After reviewing different definitions available in literature, a definition related to the method of measurement and X-ray energy, is suggested. A new concept of effective mass density is then introduced in order to characterize material from dual-energy computed tomography. Finally, this new concept and definition are applied on a simulated case, focusing on explosives identification in luggage.

  13. Automated X-ray and Optical Analysis of the Virtual Observatory and Grid Computing

    Science.gov (United States)

    Ptak, A.; Krughoff, S.; Connolly, A.

    2011-07-01

    We are developing a system to combine the Web Enabled Source Identification with X-Matching (WESIX) web service, which emphasizes source detection on optical images,with the XAssist program that automates the analysis of X-ray data. XAssist is continuously processing archival X-ray data in several pipelines. We have established a workflow in which FITS images and/or (in the case of X-ray data) an X-ray field can be input to WESIX. Intelligent services return available data (if requested fields have been processed) or submit job requests to a queue to be performed asynchronously. These services will be available via web services (for non-interactive use by Virtual Observatory portals and applications) and through web applications (written in the Django web application framework). We are adding web services for specific XAssist functionality such as determining the exposure and limiting flux for a given position on the sky and extracting spectra and images for a given region. We are improving the queuing system in XAssist to allow for "watch lists" to be specified by users, and when X-ray fields in a user's watch list become publicly available they will be automatically added to the queue. XAssist is being expanded to be used as a survey planning tool when coupled with simulation software, including functionality for NuStar, eRosita, IXO, and the Wide-Field Xray Telescope (WFXT), as part of an end-to-end simulation/analysis system. We are also investigating the possibility of a dedicated iPhone/iPad app for querying pipeline data, requesting processing, and administrative job control. This work was funded by AISRP grant NNG06GE59G.

  14. Automated X-ray and Optical Analysis of the Virtual Observatory and Grid Computing

    Science.gov (United States)

    Ptak, A.; Krughoff, S.; Connolly, A.

    2011-01-01

    We are developing a system to combine the Web Enabled Source Identification with X-Matching (WESIX) web service, which emphasizes source detection on optical images,with the XAssist program that automates the analysis of X-ray data. XAssist is continuously processing archival X-ray data in several pipelines. We have established a workflow in which FITS images and/or (in the case of X ray data) an X-ray field can be input to WESIX. Intelligent services return available data (if requested fields have been processed) or submit job requests to a queue to be performed asynchronously. These services will be available via web services (for non-interactive use by Virtual Observatory portals and applications) and through web applications (written in the Django web application framework). We are adding web services for specific XAssist functionality such as determining .the exposure and limiting flux for a given position on the sky and extracting spectra and images for a given region. We are improving the queuing system in XAssist to allow for "watch lists" to be specified by users, and when X-ray fields in a user's watch list become publicly available they will be automatically added to the queue. XAssist is being expanded to be used as a survey planning 1001 when coupled with simulation software, including functionality for NuStar, eRosita, IXO, and the Wide Field Xray Telescope (WFXT), as part of an end to end simulation/analysis system. We are also investigating the possibility of a dedicated iPhone/iPad app for querying pipeline data, requesting processing, and administrative job control.

  15. Use of X-ray computed microtomography for non-invasive determination of wood anatomical characteristics.

    Science.gov (United States)

    Steppe, Kathy; Cnudde, Veerle; Girard, Catherine; Lemeur, Raoul; Cnudde, Jean-Pierre; Jacobs, Patric

    2004-10-01

    Quantitative analysis of wood anatomical characteristics is usually performed using classical microtomy yielding optical micrographs of stained thin sections. It is time-consuming to obtain high quality cross-sections from microtomy, and sections can be damaged. This approach, therefore, is often impractical for those who need quick acquisition of quantitative data on vessel characteristics in wood. This paper reports results of a novel approach using X-ray computed microtomography (microCT) for non-invasive determination of wood anatomy. As a case study, stem wood samples of a 2-year-old beech (Fagus sylvatica L.) and a 3-year-old oak (Quercus robur L.) tree were investigated with this technique, beech being a diffuse-porous and oak a ring-porous tree species. MicroCT allowed non-invasive mapping of 2-D transverse cross-sections of both wood samples with micrometer resolution. Self-developed software 'microCTanalysis' was used for image processing of the 2-D cross-sections in order to automatically determine the inner vessel diameters, the transverse cross-sectional surface area of the vessels, the vessel density and the porosity with computer assistance. Performance of this new software was compared with manual analysis of the same micrographs. The automatically obtained results showed no significant statistical differences compared to the manual measurements. Visual inspection of the microCT slices revealed very good correspondence with the optical micrographs. Statistical analysis confirmed this observation in a more quantitative way, and it was, therefore, argued that anatomical analysis of optical micrographs can be readily substituted by automated use of microCT, and this without loss of accuracy. Furthermore, as an additional application of microCT, the 3-D renderings of the internal microstructure of the xylem vessels for both the beech and the oak sample could be reconstructed, clearly showing the complex nature of vessel networks. It can be concluded

  16. Numerical research on the anisotropic transport of thermal neutron in heterogeneous porous media with micron X-ray computed tomography

    OpenAIRE

    Yong Wang; Wenzheng Yue; Mo Zhang

    2016-01-01

    The anisotropic transport of thermal neutron in heterogeneous porous media is of great research interests in many fields. In this paper, it is the first time that a new model based on micron X-ray computed tomography (CT) has been proposed to simultaneously consider both the separation of matrix and pore and the distribution of mineral components. We apply the Monte Carlo method to simulate thermal neutrons transporting through the model along different directions, and meanwhile detect those ...

  17. The interpretation of X-ray computed microtomography images of rocks as an application of volume image processing and analysis

    OpenAIRE

    Kaczmarczyk, J.; Dohnalik, M; Zalewska, J; Cnudde, Veerle

    2010-01-01

    X-ray computed microtomography (CMT) is a non-destructive method of investigating internal structure of examined objects. During the reconstruction of CMT measurement data, large volume images are generated. Therefore, the image processing and analysis are very important steps in CMT data interpretation. The first step in analyzing the rocks is image segmentation. The differences in density are shown on the reconstructed image as the differences in gray level of voxel, so the proper threshold...

  18. Diagnostic Performance on Low Dose Computed Tomography For Acute Appendicitis Among Attending and Resident Radiologists

    Directory of Open Access Journals (Sweden)

    Chang

    2016-01-01

    Full Text Available Background Low-dose computed tomography (LDCT techniques can reduce exposure to radiation. Several previous studies have shown that radiation dose reduction in LDCT does not decrease the diagnostic performance for appendicitis among attending radiologists. But, the LDCT diagnostic performance for acute appendicitis in radiology residents with variable training levels has not been well discussed. Objectives To compare inter-observer and intra-observer differences of diagnostic performance on non-enhanced LDCT (NE-LDCT and contrast-enhanced standard dose CT (CE-SDCT for acute appendicitis among attending and resident radiologists. Patients and Methods This retrospective study included 101 patients with suspected acute appendicitis who underwent NE-LDCT and CE-SDCT. The CT examinations were interpreted and recorded on a five-point scale independently by three attending radiologists and three residents with 4, 1 and 1 years of training. Diagnostic performance for acute appendicitis of all readers on both examinations was represented by area under receiver operating characteristic (ROC curves. Inter-observer and intra-observer AUC values were compared using Jackknife FROC software on both modalities. The diagnostic accuracy of each reader on NE-LDCT was compared with body mass index (BMI subgroups and noise using independent T test. Results Diagnostic performances for acute appendicitis were not statistically different for attending radiologists at both examinations. Better performance was noted on the CE-SDCT with a borderline significant difference (P = 0.05 for senior radiology resident. No statistical difference of AUC values was observed between attending radiologists and fourth year resident on both examinations. Statistically significant differences of AUC values were observed between attending radiologists and first year residents (P = 0.001 ~ 0.018 on NE-LDCT. Diagnostic accuracies of acute appendicitis on NE-LDCT for each reader were not

  19. Possible Radiation-Induced Damage to the Molecular Structure of Wooden Artifacts Due to Micro-Computed Tomography, Handheld X-Ray Fluorescence, and X-Ray Photoelectron Spectroscopic Techniques

    Directory of Open Access Journals (Sweden)

    Madalena Kozachuk

    2016-05-01

    Full Text Available This study was undertaken to ascertain whether radiation produced by X-ray photoelectron spectroscopy (XPS, micro-computed tomography (μCT and/or portable handheld X-ray fluorescence (XRF equipment might damage wood artifacts during analysis. Changes at the molecular level were monitored by Fourier transform infrared (FTIR analysis. No significant changes in FTIR spectra were observed as a result of μCT or handheld XRF analysis. No substantial changes in the collected FTIR spectra were observed when XPS analytical times on the order of minutes were used. However, XPS analysis collected over tens of hours did produce significant changes in the FTIR spectra.

  20. Non-destructive X-ray Computed Tomography (XCT) Analysis of Sediment Variance in Marine Cores

    Science.gov (United States)

    Oti, E.; Polyak, L. V.; Dipre, G.; Sawyer, D.; Cook, A.

    2015-12-01

    Benthic activity within marine sediments can alter the physical properties of the sediment as well as indicate nutrient flux and ocean temperatures. We examine burrowing features in sediment cores from the western Arctic Ocean collected during the 2005 Healy-Oden TransArctic Expedition (HOTRAX) and from the Gulf of Mexico Integrated Ocean Drilling Program (IODP) Expedition 308. While traditional methods for studying bioturbation require physical dissection of the cores, we assess burrowing using an X-ray computed tomography (XCT) scanner. XCT noninvasively images the sediment cores in three dimensions and produces density sensitive images suitable for quantitative analysis. XCT units are recorded as Hounsfield Units (HU), where -999 is air, 0 is water, and 4000-5000 would be a higher density mineral, such as pyrite. We rely on the fundamental assumption that sediments are deposited horizontally, and we analyze the variance over each flat-lying slice. The variance describes the spread of pixel values over a slice. When sediments are reworked, drawing higher and lower density matrix into a layer, the variance increases. Examples of this can be seen in two slices in core 19H-3A from Site U1324 of IODP Expedition 308. The first slice, located 165.6 meters below sea floor consists of relatively undisturbed sediment. Because of this, the majority of the sediment values fall between 1406 and 1497 HU, thus giving the slice a comparatively small variance of 819.7. The second slice, located 166.1 meters below sea floor, features a lower density sediment matrix disturbed by burrow tubes and the inclusion of a high density mineral. As a result, the Hounsfield Units have a larger variance of 1,197.5, which is a result of sediment matrix values that range from 1220 to 1260 HU, the high-density mineral value of 1920 HU and the burrow tubes that range from 1300 to 1410 HU. Analyzing this variance allows us to observe changes in the sediment matrix and more specifically capture

  1. X-Ray Computed Tomography: The First Step in Mars Sample Return Processing

    Science.gov (United States)

    Welzenbach, L. C.; Fries, M. D.; Grady, M. M.; Greenwood, R. C.; McCubbin, F. M.; Zeigler, R. A.; Smith, C. L.; Steele, A.

    2017-01-01

    The Mars 2020 rover mission will collect and cache samples from the martian surface for possible retrieval and subsequent return to Earth. If the samples are returned, that mission would likely present an opportunity to analyze returned Mars samples within a geologic context on Mars. In addition, it may provide definitive information about the existence of past or present life on Mars. Mars sample return presents unique challenges for the collection, containment, transport, curation and processing of samples [1] Foremost in the processing of returned samples are the closely paired considerations of life detection and Planetary Protection. In order to achieve Mars Sample Return (MSR) science goals, reliable analyses will depend on overcoming some challenging signal/noise-related issues where sparse martian organic compounds must be reliably analyzed against the contamination background. While reliable analyses will depend on initial clean acquisition and robust documentation of all aspects of developing and managing the cache [2], there needs to be a reliable sample handling and analysis procedure that accounts for a variety of materials which may or may not contain evidence of past or present martian life. A recent report [3] suggests that a defined set of measurements should be made to effectively inform both science and Planetary Protection, when applied in the context of the two competing null hypotheses: 1) that there is no detectable life in the samples; or 2) that there is martian life in the samples. The defined measurements would include a phased approach that would be accepted by the community to preserve the bulk of the material, but provide unambiguous science data that can be used and interpreted by various disciplines. Fore-most is the concern that the initial steps would ensure the pristine nature of the samples. Preliminary, non-invasive techniques such as computed X-ray tomography (XCT) have been suggested as the first method to interrogate and

  2. The Astromaterials X-Ray Computed Tomography Laboratory at Johnson Space Center

    Science.gov (United States)

    Zeigler, R. A.; Coleff, D. M.; McCubbin, F. M.

    2017-01-01

    The Astromaterials Acquisition and Curation Office at NASA's Johnson Space Center (hereafter JSC curation) is the past, present, and future home of all of NASA's astromaterials sample collections. JSC curation currently houses all or part of nine different sample collections: (1) Apollo samples (1969), (2) Lunar samples (1972), (3) Antarctic meteorites (1976), (4) Cosmic Dust particles (1981), (5) Microparticle Impact Collection (1985), (6) Genesis solar wind atoms (2004); (7) Stardust comet Wild-2 particles (2006), (8) Stardust interstellar particles (2006), and (9) Hayabusa asteroid Itokawa particles (2010). Each sample collection is housed in a dedicated clean room, or suite of clean rooms, that is tailored to the requirements of that sample collection. Our primary goals are to maintain the long-term integrity of the samples and ensure that the samples are distributed for scientific study in a fair, timely, and responsible manner, thus maximizing the return on each sample. Part of the curation process is planning for the future, and we also perform fundamental research in advanced curation initiatives. Advanced Curation is tasked with developing procedures, technology, and data sets necessary for curating new types of sample collections, or getting new results from existing sample collections [2]. We are (and have been) planning for future curation, including cold curation, extended curation of ices and volatiles, curation of samples with special chemical considerations such as perchlorate-rich samples, and curation of organically- and biologically-sensitive samples. As part of these advanced curation efforts we are augmenting our analytical facilities as well. A micro X-Ray computed tomography (micro-XCT) laboratory dedicated to the study of astromaterials will be coming online this spring within the JSC Curation office, and we plan to add additional facilities that will enable nondestructive (or minimally-destructive) analyses of astromaterials in the near

  3. Predicting tissue distribution and partitioning in terminal sire sheep using x-ray computed tomography.

    Science.gov (United States)

    Macfarlane, J M; Lewis, R M; Emmans, G C; Young, M J; Simm, G

    2009-01-01

    The utility of x-ray computed tomography (CT) scanning in predicting carcass tissue distribution and fat partitioning in vivo in terminal sire sheep was examined using data from 160 lambs representing combinations of 3 breeds (Charollais, Suffolk, and Texel), 3 genetic lines, and both sexes. One-fifth of the lambs were slaughtered at each of 14, 18, and 22 wk of age, and the remaining two-fifths at 26 wk of age. The left side of each carcass was dissected into 8 joints with each joint dissected into fat (intermuscular and subcutaneous), lean, and bone. Chemical fat content of the LM was measured. Tissue distribution was described by proportions of total carcass tissue and lean weight contained within the leg, loin, and shoulder regions of the carcass and within the higher-priced joints. Fat partitioning variables included proportion of total carcass fat contained in the subcutaneous depot and intramuscular fat content of the LM. Before slaughter, all lambs were CT scanned at 7 anatomical positions (ischium, midshaft of femur, hip, second and fifth lumbar vertebrae, sixth and eighth thoracic vertebrae). Areas of fat, lean, and bone (mm(2)) and average fat and lean density (Hounsfield units) were measured from each cross-sectional scan. Areas of intermuscular and subcutaneous fat were measured on 2 scans (ischium and eighth thoracic vertebra). Intramuscular fat content was predicted with moderate accuracy (R(2) = 56.6) using information from only 2 CT scans. Four measures of carcass tissue distribution were predicted with moderate to high accuracy: the proportion of total carcass (R(2) = 54.7) and lean (R(2) = 46.2) weight contained in the higher-priced joints and the proportion of total carcass (R(2) = 77.7) and lean (R(2) = 55.0) weight in the leg region. Including BW in the predictions did not improve their accuracy (P > 0.05). Although breed-line-sex combination significantly affected fit of the regression for some tissue distribution variables, the values

  4. Complex path flows in geological media imaged by X-Ray computed tomography

    Science.gov (United States)

    Neuville, Amélie; Ebner, Marcus; Toussaint, Renaud; Renard, François; Koehn, Daniel; Flekkøy, Eirik; Cochard, Alain

    2013-04-01

    Stylolites as well as fractures are reported as major conduits in geological media (1, 2). The flow circulation has a strong influence on hydro-mecanico-chemical processes, in particular on crystallization and dissolution (3, 4). For instance hydrothermal ore deposits are frequently located in stylolites and fractures at depth. The fluid pressure also intervenes as a thermodynamic parameter in chemical reactions, and is in addition responsible for elastic deformations of the medium. Using tridimensional numerical simulations, we aim at better characterizing the flow circulation in complex structures, and at investigating on how the flow modifies the geological medium. First, X-Ray computed tomography scans of a complete stylolite structure (i.e. calcareous matrix, clay layering in the aperture, and the very thin aperture itself), and that of a fractured sandstone sample were performed. Then, image processing is required in order to extract the geometry of the porous medium of each sample. The geometries are actually more complicated than that of classical fractures, because of the existence of non connected -- or barely connected -- void spaces. We report on the influence of this image processing on the aperture geometry and on the computed permeability. This is addressed by first performing a numerical simulation of the tridimensional velocity field, using a coupled lattice Boltzmann method that solves the complete Navier-Stokes equation. After calculating the velocity field we then question the link between the geometry of complex stylolites and fractures, and the spatial auto-correlation of the velocity field. This correlation might indeed be important for dispersion processes. A first approach is to compute this correlation from the simulated velocity field. Another approach is to compute analytically the correlation function, from the knowledge of the aperture correlation. This is however developed in the perturbative limit of small aperture variations, that

  5. Effects of low dose x-ray on development and differentiation of cerebral cortex, 13. Observation of construction of cerebral cortex in mice irradiated at 17 days of gestational age

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, K.; Hayashi, Y.; Ito, Y.; Kameyama, Y. (Nagoya Univ. (Japan). Research Inst. of Environmental Medicine)

    1980-03-01

    ICR mice were irradiated with 25 or 100 R of x-ray at 17 days of pregnancy, and /sup 3/H-thymidine was injected immediately after the irradiation. The brain of progenies which were born from irradiated ICR mice was extracted 4 weeks after their birth, and histoautoradiography of the cerebram were made. Distribution of nerve cells labelled strongly with /sup 3/H-thymidine was observed, and the construction of cerebral cortex was discussed. Abnormality in parietal region of new cerebral cortex in which nerve cells labelled strongly with /sup 3/H-thymidine distributed was not found, but a count of nerve cells distributing tended to decrease according to exposure dose.

  6. Congenital Vertebral Malformations In French Bulldogs: X-Ray Vs Computed Tomography

    Directory of Open Access Journals (Sweden)

    Lucia Madalina CORLAT

    2017-05-01

    Full Text Available Congenital vertebral malformations of the thoracolumbar area can have an important impact in the clinical evolution of French Bulldogs due to the instability it creates at the spinal level. The aim of this study is to show the differences between x-ray and CT scans in vertebral malformations of the French Bulldog. CT scans can offer a higher degree of certainty in the diagnosis of congenital vertebral malformations of the dogs. The VR model can offer a more thorough evaluation of the existing modifications of the vertebral body, allowing the examiner to circumvent the superposition effect than can be observed in the x-ray views and offering the chance to evaluate whether there is scoliosis or kyphosis present.

  7. Iodinated silica/porphyrin hybrid nanoparticles for X-ray computed tomography/fluorescence dual-modal imaging of tumors

    Directory of Open Access Journals (Sweden)

    Koichiro Hayashi

    2014-12-01

    Full Text Available Silica nanoparticles containing covalently linked iodine and a near-infrared (NIR fluorescence dye, namely porphyrin, have been synthesized through a one-pot sol–gel reaction. These particles are called iodinated silica/porphyrin hybrid nanoparticles (ISP HNPs. The ISP HNPs have both high X-ray absorption coefficient and NIR fluorescence. The ISP HNPs modified with folic acid (FA and polyethylene glycol (PEG, denoted as FA-PEG-ISP HNPs, enabled the successful visualization of tumors in mice by both X-ray computed tomography (CT and fluorescence imaging (FI. Thus, the FA-PEG-ISP HNPs are useful as contrast agents or probes for CT/FI dual-modal imaging.

  8. Dark-count-less photon-counting x-ray computed tomography system using a YAP-MPPC detector

    Science.gov (United States)

    Sato, Eiichi; Sato, Yuich; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2012-10-01

    A high-sensitive X-ray computed tomography (CT) system is useful for decreasing absorbed dose for patients, and a dark-count-less photon-counting CT system was developed. X-ray photons are detected using a YAP(Ce) [cerium-doped yttrium aluminum perovskite] single crystal scintillator and an MPPC (multipixel photon counter). Photocurrents are amplified by a high-speed current-voltage amplifier, and smooth event pulses from an integrator are sent to a high-speed comparator. Then, logical pulses are produced from the comparator and are counted by a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The image contrast of gadolinium medium slightly fell with increase in lower-level voltage (Vl) of the comparator. The dark count rate was 0 cps, and the count rate for the CT was approximately 250 kcps.

  9. A simulation-based study on the influence of beam hardening in X-ray computed tomography for dimensional metrology.

    Science.gov (United States)

    Lifton, Joseph J; Malcolm, Andrew A; McBride, John W

    2015-01-01

    X-ray computed tomography (CT) is a radiographic scanning technique for visualising cross-sectional images of an object non-destructively. From these cross-sectional images it is possible to evaluate internal dimensional features of a workpiece which may otherwise be inaccessible to tactile and optical instruments. Beam hardening is a physical process that degrades the quality of CT images and has previously been suggested to influence dimensional measurements. Using a validated simulation tool, the influence of spectrum pre-filtration and beam hardening correction are evaluated for internal and external dimensional measurements. Beam hardening is shown to influence internal and external dimensions in opposition, and to have a greater influence on outer dimensions compared to inner dimensions. The results suggest the combination of spectrum pre-filtration and a local gradient-based surface determination method are able to greatly reduce the influence of beam hardening in X-ray CT for dimensional metrology.

  10. Computational Studies of X-ray Framing Cameras for the National Ignition Facility

    Science.gov (United States)

    2013-06-01

    Livermore National Laboratory 7000 East Avenue Livermore, CA 94550 USA Abstract The NIF is the world’s most powerful laser facility and is...a phosphor screen where the output is recorded. The x-ray framing cameras have provided excellent information. As the yields at NIF have increased...experiments on the NIF . The basic operation of these cameras is shown in Fig. 1. Incident photons generate photoelectrons both in the pores of the MCP and

  11. A Comparison of Shadowgraphy and X-ray Computed Tomography in Liquid Spray Analysis

    Science.gov (United States)

    2014-11-14

    atomizers, the orifice diameter, d0, is Table 1: Dimensionless and dimensional parameters for each nozzle and experiment generally around 150 µm...volumetric flow into a graduated cylinder after one minute. Using the calculated volumetric flow rate along with the known orifice size of each...The X-ray source was located 1422 mm away from the rotation axis of the spray system, and the detector was 398 mm on the opposite side . Operating at

  12. Maximum-likelihood estimation of scatter components algorithm for x-ray coherent scatter computed tomography of the breast.

    Science.gov (United States)

    Ghammraoui, Bahaa; Badal, Andreu; Popescu, Lucretiu M

    2016-04-21

    Coherent scatter computed tomography (CSCT) is a reconstructive x-ray imaging technique that yields the spatially resolved coherent-scatter cross section of the investigated object revealing structural information of tissue under investigation. In the original CSCT proposals the reconstruction of images from coherently scattered x-rays is done at each scattering angle separately using analytic reconstruction. In this work we develop a maximum likelihood estimation of scatter components algorithm (ML-ESCA) that iteratively reconstructs images using a few material component basis functions from coherent scatter projection data. The proposed algorithm combines the measured scatter data at different angles into one reconstruction equation with only a few component images. Also, it accounts for data acquisition statistics and physics, modeling effects such as polychromatic energy spectrum and detector response function. We test the algorithm with simulated projection data obtained with a pencil beam setup using a new version of MC-GPU code, a Graphical Processing Unit version of PENELOPE Monte Carlo particle transport simulation code, that incorporates an improved model of x-ray coherent scattering using experimentally measured molecular interference functions. The results obtained for breast imaging phantoms using adipose and glandular tissue cross sections show that the new algorithm can separate imaging data into basic adipose and water components at radiation doses comparable with Breast Computed Tomography. Simulation results also show the potential for imaging microcalcifications. Overall, the component images obtained with ML-ESCA algorithm have a less noisy appearance than the images obtained with the conventional filtered back projection algorithm for each individual scattering angle. An optimization study for x-ray energy range selection for breast CSCT is also presented.

  13. Maximum-likelihood estimation of scatter components algorithm for x-ray coherent scatter computed tomography of the breast

    Science.gov (United States)

    Ghammraoui, Bahaa; Badal, Andreu; Popescu, Lucretiu M.

    2016-04-01

    Coherent scatter computed tomography (CSCT) is a reconstructive x-ray imaging technique that yields the spatially resolved coherent-scatter cross section of the investigated object revealing structural information of tissue under investigation. In the original CSCT proposals the reconstruction of images from coherently scattered x-rays is done at each scattering angle separately using analytic reconstruction. In this work we develop a maximum likelihood estimation of scatter components algorithm (ML-ESCA) that iteratively reconstructs images using a few material component basis functions from coherent scatter projection data. The proposed algorithm combines the measured scatter data at different angles into one reconstruction equation with only a few component images. Also, it accounts for data acquisition statistics and physics, modeling effects such as polychromatic energy spectrum and detector response function. We test the algorithm with simulated projection data obtained with a pencil beam setup using a new version of MC-GPU code, a Graphical Processing Unit version of PENELOPE Monte Carlo particle transport simulation code, that incorporates an improved model of x-ray coherent scattering using experimentally measured molecular interference functions. The results obtained for breast imaging phantoms using adipose and glandular tissue cross sections show that the new algorithm can separate imaging data into basic adipose and water components at radiation doses comparable with Breast Computed Tomography. Simulation results also show the potential for imaging microcalcifications. Overall, the component images obtained with ML-ESCA algorithm have a less noisy appearance than the images obtained with the conventional filtered back projection algorithm for each individual scattering angle. An optimization study for x-ray energy range selection for breast CSCT is also presented.

  14. Feasibility study of Compton cameras for x-ray fluorescence computed tomography with humans.

    Science.gov (United States)

    Vernekohl, Don; Ahmad, Moiz; Chinn, Garry; Xing, Lei

    2016-12-21

    X-ray fluorescence imaging is a promising imaging technique able to depict the spatial distributions of low amounts of molecular agents in vivo. Currently, the translation of the technique to preclinical and clinical applications is hindered by long scanning times as objects are scanned with flux-limited narrow pencil beams. The study presents a novel imaging approach combining x-ray fluorescence imaging with Compton imaging. Compton cameras leverage the imaging performance of XFCT and abolish the need for pencil beam excitation. The study examines the potential of this new imaging approach on the base of Monte-Carlo simulations. In the work, it is first presented that the particular option of slice/fan-beam x-ray excitation has advantages in image reconstruction in regard of processing time and image quality compared to traditional volumetric Compton imaging. In a second experiment, the feasibility of the approach for clinical applications with tracer agents made from gold nano-particles is examined in a simulated lung scan scenario. The high energy of characteristic x-ray photons from gold is advantageous for deep tissue penetration and has lower angular blurring in the Compton camera. It is found that Doppler broadening in the first detector stage of the Compton camera adds the largest contribution on the angular blurring; physically limiting the spatial resolution. Following the analysis of the results from the spatial resolution test, resolutions in the order of one centimeter are achievable with the approach in the center of the lung. The concept of Compton imaging allows one to distinguish to some extent between scattered photons and x-ray fluorescent photons based on their difference in emission position. The results predict that molecular sensitivities down to 240 pM l(-1) for 5 mm diameter lesions at 15 mGy for 50 nm diameter gold nano-particles are achievable. A 45-fold speed up time for data acquisition compared to traditional pencil beam XFCT could

  15. Feasibility study of Compton cameras for x-ray fluorescence computed tomography with humans

    Science.gov (United States)

    Vernekohl, Don; Ahmad, Moiz; Chinn, Garry; Xing, Lei

    2016-12-01

    X-ray fluorescence imaging is a promising imaging technique able to depict the spatial distributions of low amounts of molecular agents in vivo. Currently, the translation of the technique to preclinical and clinical applications is hindered by long scanning times as objects are scanned with flux-limited narrow pencil beams. The study presents a novel imaging approach combining x-ray fluorescence imaging with Compton imaging. Compton cameras leverage the imaging performance of XFCT and abolish the need for pencil beam excitation. The study examines the potential of this new imaging approach on the base of Monte-Carlo simulations. In the work, it is first presented that the particular option of slice/fan-beam x-ray excitation has advantages in image reconstruction in regard of processing time and image quality compared to traditional volumetric Compton imaging. In a second experiment, the feasibility of the approach for clinical applications with tracer agents made from gold nano-particles is examined in a simulated lung scan scenario. The high energy of characteristic x-ray photons from gold is advantageous for deep tissue penetration and has lower angular blurring in the Compton camera. It is found that Doppler broadening in the first detector stage of the Compton camera adds the largest contribution on the angular blurring; physically limiting the spatial resolution. Following the analysis of the results from the spatial resolution test, resolutions in the order of one centimeter are achievable with the approach in the center of the lung. The concept of Compton imaging allows one to distinguish to some extent between scattered photons and x-ray fluorescent photons based on their difference in emission position. The results predict that molecular sensitivities down to 240 pM l-1 for 5 mm diameter lesions at 15 mGy for 50 nm diameter gold nano-particles are achievable. A 45-fold speed up time for data acquisition compared to traditional pencil beam XFCT could

  16. Development of a Radiation Dose Reporting Software for X-ray Computed Tomography (CT)

    Science.gov (United States)

    Ding, Aiping

    X-ray computed tomography (CT) has experienced tremendous technological advances in recent years and has established itself as one of the most popular diagnostic imaging tools. While CT imaging clearly plays an invaluable role in modern medicine, its rapid adoption has resulted in a dramatic increase in the average medical radiation exposure to the worldwide and United States populations. Existing software tools for CT dose estimation and reporting are mostly based on patient phantoms that contain overly simplified anatomies insufficient in meeting the current and future needs. This dissertation describes the development of an easy-to-use software platform, “VirtualDose”, as a service to estimate and report the organ dose and effective dose values for patients undergoing the CT examinations. “VirtualDose” incorporates advanced models for the adult male and female, pregnant women, and children. To cover a large portion of the ignored obese patients that frequents the radiology clinics, a new set of obese male and female phantoms are also developed and applied to study the effects of the fat tissues on the CT radiation dose. Multi-detector CT scanners (MDCT) and clinical protocols, as well as the most recent effective dose algorithms from the International Commission on Radiological Protection (ICRP) Publication 103 are adopted in “VirtualDose” to keep pace with the MDCT development and regulatory requirements. A new MDCT scanner model with both body and head bowtie filter is developed to cover both the head and body scanning modes. This model was validated through the clinical measurements. A comprehensive slice-by-slice database is established by deriving the data from a larger number of single axial scans simulated on the patient phantoms using different CT bowtie filters, beam thicknesses, and different tube voltages in the Monte Carlo N-Particle Extended (MCNPX) code. When compared to the existing CT dose software packages, organ dose data in this

  17. CdTe and CdZnTe detectors behavior in X-ray computed tomography conditions

    CERN Document Server

    Ricq, S; Garcin, M

    2000-01-01

    The application of CdTe and CdZnTe 2D array detectors for medical X-ray Computed Tomography (XCT) is investigated. Different metallic electrodes have been deposited on High-Pressure Bridgman Method CdZnTe and on Traveling Heater Method CdTe:Cl. These detectors are exposed to X-rays in the CT irradiation conditions and are characterized experimentally in current mode. Detectors performances such as sensitivity and response speed are studied. They are correlated with charge trapping and de-trapping. The trapped carrier space charges may influence the injection from the electrodes. This enables one to get information on the nature of the predominant levels involved. The performances achieved are encouraging: dynamic ranges higher than 4 decades and current decreases of 3 decades in 4 ms after X-ray beam cut-off are obtained. Nevertheless, these detectors are still limited by high trap densities responsible for the memory effect that makes them unsuitable for XCT.

  18. How little data is enough? Phase-diagram analysis of sparsity-regularized X-ray computed tomography.

    Science.gov (United States)

    Jørgensen, J S; Sidky, E Y

    2015-06-13

    We introduce phase-diagram analysis, a standard tool in compressed sensing (CS), to the X-ray computed tomography (CT) community as a systematic method for determining how few projections suffice for accurate sparsity-regularized reconstruction. In CS, a phase diagram is a convenient way to study and express certain theoretical relations between sparsity and sufficient sampling. We adapt phase-diagram analysis for empirical use in X-ray CT for which the same theoretical results do not hold. We demonstrate in three case studies the potential of phase-diagram analysis for providing quantitative answers to questions of undersampling. First, we demonstrate that there are cases where X-ray CT empirically performs comparably with a near-optimal CS strategy, namely taking measurements with Gaussian sensing matrices. Second, we show that, in contrast to what might have been anticipated, taking randomized CT measurements does not lead to improved performance compared with standard structured sampling patterns. Finally, we show preliminary results of how well phase-diagram analysis can predict the sufficient number of projections for accurately reconstructing a large-scale image of a given sparsity by means of total-variation regularization.

  19. K-edge imaging in x-ray computed tomography using multi-bin photon counting detectors.

    Science.gov (United States)

    Roessl, E; Proksa, R

    2007-08-07

    After passage through matter, the energy spectrum of a polychromatic beam of x-rays contains valuable information about the elemental composition of the absorber. Conventional x-ray systems or x-ray computed tomography (CT) systems, equipped with scintillator detectors operated in the integrating mode, are largely insensitive to this type of spectral information, since the detector output is proportional to the energy fluence integrated over the whole spectrum. The main purpose of this paper is to investigate to which extent energy-sensitive photon counting devices, operated in the pulse-mode, are capable of revealing quantitative information about the elemental composition of the absorber. We focus on the detection of element-specific, K-edge discontinuities of the photo-electric cross-section. To be specific, we address the question of measuring and imaging the local density of a gadolinium-based contrast agent, in the framework of a generalized dual-energy pre-processing. Our results are very promising and seem to open up new possibilities for the imaging of the distribution of elements with a high atomic number Z in the human body using x-ray attenuation measurements. To demonstrate the usefulness of the detection and the appropriate processing of the spectral information, we present simulated images of an artherosclerotic coronary vessel filled with gadolinium-based contrast agent. While conventional systems, equipped with integrating detectors, often fail to differentiate between contrast filled lumen and artherosclerotic plaque, the use of an energy-selective detection system based on the counting of individual photons reveals a strong contrast between plaque and contrast agent.

  20. Transfer of students' learning about X-rays and computer-assisted tomography from physics to medical imaging

    Science.gov (United States)

    Kalita, Spartak A.

    In this study we explored students' transfer of learning in the X-ray medical imaging context, including the X-ray-based computer-assisted tomography (or CAT). For this purpose we have conducted a series of clinical and teaching interviews. The investigation was a part of a bigger research effort to design teaching-learning materials for pre-medical students who are completing their algebra-based physics course. Our students brought to the discussion pieces of knowledge transferred from very different sources such as their own X-ray experiences, previous learning and the mass media. This transfer seems to result in more or less firm mental models, although often not internally consistent or coherent. Based on our research on pre-med students' models of X-rays we designed a hands-on lab using semi-transparent Lego bricks to model CAT scans. Without "surgery" (i.e. without intrusion into the Lego "body") students determined the shape of an object, which was built out of opaque and translucent Lego bricks and hidden from view. A source of light and a detector were provided upon request. Using a learning cycle format, we introduced CAT scans after students successfully have completed this task. By comparing students' ideas before and after teaching interview with the groups of 2 or 3 participants, we have investigated transfer of learning from basic physics and everyday experience to a complex medical technology and how their peer interactions trigger and facilitate this process. During the last phase of our research we also introduced a CAT-scan simulation problem into our teaching interview routine and compared students' perception of this simulation and their perception of the hands-on activity.

  1. Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy.

    Directory of Open Access Journals (Sweden)

    Hiroaki Hasegawa

    Full Text Available The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT fluoroscopy using the integrated dose ratio (IDR of an X-ray dose profile derived from an optically stimulated luminescent (OSL dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (-50 to -6 mm, 50 to 6 mm was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies.

  2. Skull x-ray

    Science.gov (United States)

    X-ray - head; X-ray - skull; Skull radiography; Head x-ray ... There is low radiation exposure. X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most ...

  3. Neck x-ray

    Science.gov (United States)

    X-ray - neck; Cervical spine x-ray; Lateral neck x-ray ... There is low radiation exposure. X-rays are monitored so that the lowest amount of radiation is used to produce the image. Pregnant women and ...

  4. High pressure behaviour of TbN: an X-ray diffraction and computational study

    DEFF Research Database (Denmark)

    Jakobsen, J.M.; Madsen, G.K.H.; Jorgensen, J.E.

    2002-01-01

    In the present work, we report an X-ray powder diffraction study of TbN up to an applied hydrostatic pressure of 43 GPa. TbN was found to be stable in the 131 (NaCl structure) within the examined pressure interval, and the zero pressure bulk modulus was determined to be 176(7) GPa. The electronic...... to be itinerant and well described by standard DFT functionals. No pressure-induced phase transitions were found below 250 GPa with the LDA + U and GGA + U methods....

  5. X-ray Reflection

    Science.gov (United States)

    Fabian, A. C.; Ross, R. R.

    2010-12-01

    Material irradiated by X-rays produces backscattered radiation which is commonly known as the Reflection Spectrum. It consists of a structured continuum, due at high energies to the competition between photoelectric absorption and electron scattering enhanced at low energies by emission from the material itself, together with a complex line spectrum. We briefly review the history of X-ray reflection in astronomy and discuss various methods for computing the reflection spectrum from cold and ionized gas, illustrated with results from our own work reflionx. We discuss how the reflection spectrum can be used to obtain the geometry of the accretion flow, particularly the inner regions around black holes and neutron stars.

  6. Structural analysis of advanced polymeric foams by means of high resolution X-ray computed tomography

    Science.gov (United States)

    Nacucchi, M.; De Pascalis, F.; Scatto, M.; Capodieci, L.; Albertoni, R.

    2016-06-01

    Advanced polymeric foams with enhanced thermal insulation and mechanical properties are used in a wide range of industrial applications. The properties of a foam strongly depend upon its cell structure. Traditionally, their microstructure has been studied using 2D imaging systems based on optical or electron microscopy, with the obvious disadvantage that only the surface of the sample can be analysed. To overcome this shortcoming, the adoption of X-ray micro-tomography imaging is here suggested to allow for a complete 3D, non-destructive analysis of advanced polymeric foams. Unlike metallic foams, the resolution of the reconstructed structural features is hampered by the low contrast in the images due to weak X-ray absorption in the polymer. In this work an advanced methodology based on high-resolution and low-contrast techniques is used to perform quantitative analyses on both closed and open cells foams. Local structural features of individual cells such as equivalent diameter, sphericity, anisotropy and orientation are statistically evaluated. In addition, thickness and length of the struts are determined, underlining the key role played by the achieved resolution. In perspective, the quantitative description of these structural features will be used to evaluate the results of in situ mechanical and thermal test on foam samples.

  7. Computed Tomography with X-rays and Fast Neutrons for Restoration of Wooden Artwork

    Science.gov (United States)

    Osterloh, Kurt; Bellon, Carsten; Hohendorf, Stefan; Kolkoori, Sanjeevareddy; Wrobel, Norma; Nusser, Amélie; Freitag, Markus; Bücherl, Thomas; Bar, Doron; Mor, Ilan; Tamin, Noam; Weiss-Babai, Ruth; Bromberger, Benjamin; Dangendorf, Volker; Tittelmeier, Kai

    The objects of this investigation were sculptures taken from a ca. three hundred years old baroque epitaph of a church in Tönning, a town in Northern Germany. Around 1900 it was found in a disastrous state heavily damaged by wood-worm. At that time, the whole artwork was treated with the tar extract carbolineum as a remedy. Nowadays, this substance has been identified as carcinogenic, and its presence can be perceived by its stench and visually at certain spots on the surface where it has penetrated the covering paint. A gold-painted sculpture of a massive wooden skull was interrogated with X-rays and fast neutrons to investigate the internal distribution of the carbolineum. The X-ray tomography, with its excellent spatial resolution revealed galleries left over from the worm infestation in the outer areas and cracks in the central region. The golden color coating appeared as a thick and dense layer. In comparison the tomography with fast neutrons, though being of lower resolution and yet unresolved artefacts revealed sections of slightly different densities in the bulk of the wood. These differences we attribute to the differences in the distribution of the impregnant in the wood, visible due to its higher hydrogen content making it less transparent for neutrons.

  8. X-ray beam-shaping via deformable mirrors: analytical computation of the required mirror profile

    CERN Document Server

    Spiga, Daniele; Svetina, Cristian; Zangrando, Marco; 10.1016/j.nima.2012.10.117

    2013-01-01

    X-ray mirrors with high focusing performances are in use in both mirror mod- ules for X-ray telescopes and in synchrotron and FEL (Free Electron Laser) beamlines. A degradation of the focus sharpness arises in general from geo- metrical deformations and surface roughness, the former usually described by geometrical optics and the latter by physical optics. In general, technological developments are aimed at a very tight focusing, which requires the mirror profile to comply with the nominal shape as much as possible and to keep the roughness at a negligible level. However, a deliberate deformation of the mirror can be made to endow the focus with a desired size and distribution, via piezo actuators as done at the EIS-TIMEX beamline of FERMI@Elettra. The resulting profile can be characterized with a Long Trace Profilometer and correlated with the expected optical quality via a wavefront propagation code. However, if the roughness contribution can be neglected, the com- putation can be performed via a ray-tracin...

  9. Application of X-ray computed micro-tomography to the study of damage and oxidation kinetics of thermostructural composites

    Energy Technology Data Exchange (ETDEWEB)

    Caty, Olivier, E-mail: caty@lcts.u-bordeaux1.fr [Laboratory of Thermostructural Composites (LCTS), Université de Bordeaux, CNRS, SAFRAN, CEA, 3 Allée La Boétie, 33600 Pessac (France); Ibarroule, Philippe; Herbreteau, Mathieu; Rebillat, Francis [Laboratory of Thermostructural Composites (LCTS), Université de Bordeaux, CNRS, SAFRAN, CEA, 3 Allée La Boétie, 33600 Pessac (France); Maire, Eric [MATEIS Laboratory, INSA Lyon, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex (France); Vignoles, Gérard L. [Laboratory of Thermostructural Composites (LCTS), Université de Bordeaux, CNRS, SAFRAN, CEA, 3 Allée La Boétie, 33600 Pessac (France)

    2014-04-01

    Thermostructural composites are three-dimensionally (3D) structured materials. Weakening phenomena (mechanical and chemical) take place inside the material following its 3D structure and are thus hard to describe accurately. X-ray computed micro-tomography (μCT) is a recent solution that allows their experimental investigation. The technique is applied here to the study of failure under tensile loading and to the self healing processes during oxidation. Results are useful data to verify or invalidate hypotheses or estimations made in current models.

  10. Evaluation of low-dose dual energy computed tomography for in vivo assessment of renal/ureteric calculus composition.

    Science.gov (United States)

    Mahalingam, Harshavardhan; Lal, Anupam; Mandal, Arup K; Singh, Shrawan Kumar; Bhattacharyya, Shalmoli; Khandelwal, Niranjan

    2015-08-01

    This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. A total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis. A total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv. Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.

  11. Quantitative strain analysis in analogue modelling experiments: insights from X-ray computed tomography and tomographic image correlation

    Science.gov (United States)

    Adam, J.; Klinkmueller, M.; Schreurs, G.; Wieneke, B.

    2009-04-01

    The combination of scaled analogue modelling experiments, advanced research in analogue material mechanics (Lohrmann et al. 2003, Panien et al. 2006), X-ray computed tomography and new high-resolution deformation monitoring techniques (2D/3D Digital Image Correlation) is a new powerful tool not only to examine the evolution and interaction of faulting in analogue models, but also to evaluate relevant controlling factors such as mechanics, sedimentation, erosion and climate. This is of particular interest for applied problems in the energy sector (e.g., structurally complex reservoirs, LG & CO2 underground storage) because the results are essential for geological and seismic interpretation as well as for more realistically constrained fault/fracture simulations and reservoir characterisation. X-ray computed tomography (CT) analysis has been successfully applied to analogue models since the late 1980s. This technique permits visualisation of the interior of an analogue model without destroying it. Technological improvements have resulted in more powerful X-ray CT scanners that allow periodic acquisition of volumetric data sets thus making it possible to follow the 3-D evolution of the model structures with time (e.g. Schreurs et al., 2002, 2003). Optical strain monitoring (Digital Image Correlation, DIC) in analogue experiments (Adam et al., 2005) represents an important advance in quantitative physical modelling and in helping to understand non-linear rock deformation processes. Optical non-intrusive 2D/3D strain and surface flow analysis by DIC is a new methodology in physical modelling that enables the complete quantification of localised and distributed model deformation. The increase in spatial/temporal strain data resolution of several orders of magnitude makes physical modelling - used for decades to visualize the kinematic processes of geological deformation processes - a unique research tool to determine what fundamental physical processes control tectonic

  12. A general method for motion compensation in x-ray computed tomography

    Science.gov (United States)

    Biguri, Ander; Dosanjh, Manjit; Hancock, Steven; Soleimani, Manuchehr

    2017-08-01

    Motion during data acquisition is a known source of error in medical tomography, resulting in blur artefacts in the regions that move. It is critical to reduce these artefacts in applications such as image-guided radiation therapy as a clearer image translates into a more accurate treatment and the sparing of healthy tissue close to a tumour site. Most research in 4D x-ray tomography involving the thorax relies on respiratory phase binning of the acquired data and reconstructing each of a set of images using the limited subset of data per phase. In this work, we demonstrate a motion-compensation method to reconstruct images from the complete dataset taken during breathing without recourse to phase-binning or breath-hold techniques. As long as the motion is sufficiently well known, the new method can accurately reconstruct an image at any time during the acquisition time span. It can be applied to any iterative reconstruction algorithm.

  13. A General Method for Motion Compensation in X-ray Computed Tomography

    CERN Document Server

    AUTHOR|(CDS)2067162; Dosanjh, Manjit; Soleimani, Manuchehr

    2017-01-01

    Motion during data acquisition is a known source of error in medical tomography, resulting in blur artefacts in the regions that move. It is critical to reduce these artefacts in applications such as image-guided radiation therapy as a clearer image translates into a more accurate treatment and the sparing of healthy tissue close to a tumour site. Most research in 4D X-ray tomography involving the thorax relies on respiratory phase binning of the acquired data and reconstructing each of a set of images using the limited subset of data per phase. In this work, we demonstrate a motion-compensation method to reconstruct images from the complete dataset taken during breathing without recourse to phase-binning or breath-hold techniques. As long as the motion is sufficiently well known, the new method can accurately reconstruct an image at any time during the acquisition time span. It can be applied to any iterative reconstruction algorithm.

  14. Path-based Iterative Reconstruction (PBIR) for X-ray Computed Tomography

    CERN Document Server

    Wu, Meng; Yang, Qiao; Fahrig, Rebecca

    2015-01-01

    Model-based iterative reconstruction (MBIR) techniques have demonstrated many advantages in X-ray CT image reconstruction. The MBIR approach is often modeled as a convex optimization problem including a data fitting function and a penalty function. The tuning parameter value that regulates the strength of the penalty function is critical for achieving good reconstruction results but difficult to choose. In this work, we describe two path seeking algorithms that are capable of efficiently generating a series of MBIR images with different strengths of the penalty function. The root-mean-squared-differences of the proposed path seeking algorithms are below 4 HU throughout the entire reconstruction path. With the efficient path seeking algorithm, we suggest a path-based iterative reconstruction (PBIR) to obtain complete information from the scanned data and reconstruction model.

  15. X-ray computed tomography system for laboratory small-object imaging: Enhanced tomography solutions.

    Science.gov (United States)

    Kharfi, F; Yahiaoui, M L; Boussahoul, F

    2015-07-01

    A portable X-ray tomography system has been installed and actually being tested at our medical imaging laboratory. This tomography system employs a combination of scintillator screen and CCD camera as image detector. The limit of spatial resolution of 290 μm of this imaging system is determined by the establishment of its modulation transfer function (MTF). In this work, we present attempts to address some issues such as limited resolution and low contrast through the development of affordable post-acquisition solutions based on the application of super-resolution method (projection onto convex sets, POCS) to create new projections set enabling the reconstruction of an improved 3D image in terms of contrast, resolution and noise. In addition to small-object examination, this tomography system is used for hands-on training activities involving students and scientists.

  16. Segmentation-free x-ray energy spectrum estimation for computed tomography

    CERN Document Server

    Zhao, Wei; Niu, Tianye

    2016-01-01

    X-ray energy spectrum plays an essential role in imaging and related tasks. Due to the high photon flux of clinical CT scanners, most of the spectrum estimation methods are indirect and are usually suffered from various limitations. The recently proposed indirect transmission measurement-based method requires at least the segmentation of one material, which is insufficient for CT images of highly noisy and with artifacts. To combat for the bottleneck of spectrum estimation using segmented CT images, in this study, we develop a segmentation-free indirect transmission measurement based energy spectrum estimation method using dual-energy material decomposition. The general principle of the method is to compare polychromatic forward projection with raw projection to calibrate a set of unknown weights which are used to express the unknown spectrum together with a set of model spectra. After applying dual-energy material decomposition using high- and low-energy raw projection data, polychromatic forward projection ...

  17. Performance Evaluation of a Modular Detector Unit for X-Ray Computed Tomography

    Directory of Open Access Journals (Sweden)

    Guangshu Hu

    2013-04-01

    Full Text Available A research prototype CT scanner is currently under development in our lab. One of the key components in this project is the CT detector. This paper describes the design and performance evaluation of the modular CT detector unit for our proposed scanner. It consists of a Photodiode Array Assembly which captures irradiating X-ray photons and converts the energy into electrical current, and a mini Data Acquisition System which performs current integration and converts the analog signal into digital samples. The detector unit can be easily tiled together to form a CT detector. Experiments were conducted to characterize the detector performance both at the single unit level and system level. The noise level, linearity and uniformity of the proposed detector unit were reported and initial imaging studies were also presented which demonstrated the potential application of the proposed detector unit in actual CT scanners.

  18. Quantitative X-ray fluorescence computed tomography for low-Z samples using an iterative absorption correction algorithm

    Science.gov (United States)

    Huang, Rong; Limburg, Karin; Rohtla, Mehis

    2017-05-01

    X-ray fluorescence computed tomography is often used to measure trace element distributions within low-Z samples, using algorithms capable of X-ray absorption correction when sample self-absorption is not negligible. Its reconstruction is more complicated compared to transmission tomography, and therefore not widely used. We describe in this paper a very practical iterative method that uses widely available transmission tomography reconstruction software for fluorescence tomography. With this method, sample self-absorption can be corrected not only for the absorption within the measured layer but also for the absorption by material beyond that layer. By combining tomography with analysis for scanning X-ray fluorescence microscopy, absolute concentrations of trace elements can be obtained. By using widely shared software, we not only minimized the coding, took advantage of computing efficiency of fast Fourier transform in transmission tomography software, but also thereby accessed well-developed data processing tools coming with well-known and reliable software packages. The convergence of the iterations was also carefully studied for fluorescence of different attenuation lengths. As an example, fish eye lenses could provide valuable information about fish life-history and endured environmental conditions. Given the lens's spherical shape and sometimes the short distance from sample to detector for detecting low concentration trace elements, its tomography data are affected by absorption related to material beyond the measured layer but can be reconstructed well with our method. Fish eye lens tomography results are compared with sliced lens 2D fluorescence mapping with good agreement, and with tomography providing better spatial resolution.

  19. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography

    Energy Technology Data Exchange (ETDEWEB)

    Paixao, L.; Oliveira, B. B.; Nogueira, M. do S. [Centro de Desenvolvimento da Tecnologia Nuclear, Post-graduation in Science and Technology of Radiations, Minerals and Materials, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Viloria, C. [UFMG, Departamento de Engenharia Nuclear, Post-graduation in Nuclear Sciences and Techniques, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Alves de O, M. [UFMG, Department of Anatomy and Imaging, Prof. Alfredo Balena 190, 30130-100 Belo Horizonte (Brazil); Araujo T, M. H., E-mail: lpr@cdtn.br [Dr Maria Helena Araujo Teixeira Clinic, Guajajaras 40, 30180-100 Belo Horizonte (Brazil)

    2014-08-15

    It is widely accepted that the mean glandular dose (D{sub G}) for the glandular tissue is the more useful magnitude for characterizing the breast cancer risk. The procedure to estimate the D{sub G}, for being difficult to measure it directly in the breast, it is to make the use of conversion factors that relate incident air kerma (K{sub i}) at this dose. Generally, the conversion factors vary with the x-ray spectrum half-value layer and the breast composition and thickness. Several authors through computer simulations have calculated such factors by the Monte Carlo (Mc) method. Many spectral models for D{sub G} computer simulations purposes are available in the diagnostic range. One of the models available generates unfiltered spectra. In this work, the Monte Carlo EGSnrc code package with the C++ class library (eg spp) was employed to derive filtered tungsten x-ray spectra used in digital mammography systems. Filtered spectra for rhodium and aluminium filters were obtained for tube potentials between 26 and 32 kV. The half-value layer of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F and Mam Detector Platinum and 8201023-C Xi Base unit Platinum Plus w m As in a Hologic Selenia Dimensions system using a Direct Radiography mode. Calculated half-value layer values showed good agreement compared to those obtained experimentally. These results show that the filtered tungsten anode x-ray spectra and the EGSnrc Mc code can be used for D{sub G} determination in mammography. (Author)

  20. Comparative review of computed tomography of the spinal column and conventional x-ray films

    Energy Technology Data Exchange (ETDEWEB)

    Shin, H.; Yamaura, A.; Horie, T.; Makino, H. (Chiba Univ. (Japan). School of Medicine)

    1982-04-01

    Computerized tomography (CT) of the cervical spinal column was carried out in 39 patients using a GE.CT/T or Toshiba TCT60A scanner. There were 22 cervical disk lesions, 4 spinal neoplasms, 5 narrow spinal canals with or without ossification of the posterior longitudinal ligament, 2 syringomyelias, 5 traumas, and one Arnold-Chiari malformation. In all the patients, tomography was done after conventional spinal X-ray studies. The correlation between the CT findings and conventional X-ray films revealed the excellent capability of the CT. The measurement of the midline sagittal diameter of the spinal canal in the patient with the narrowest canal in this series showed 7.4 mm when done by CT and 9.6 mm when done by the conventional plain film at the C/sub 5/ level. To ascertain the precise sagittal diameter of the cord itself, CT myelography is indispensable after the intrathecal injection of metrizamide A; metrizamide CT myelogram is useful in determining the nature of the disease, the risk of and best approach to surgery, and the evaluation after a surgical procedure. Although the range of motion of cervical joints and intervertebral foramen are visible with the conventional films, the size of the spinal tumors, the degree of bony change, and the tumor extension to the paraspinal connective tissue can be precisely demonstrated only by CT. A CT study of the spine is a simple procedure and is less likely to produce complication, even with a metrizamide CT myelogram, though there are certain limitations in the examination.

  1. Bone mineral density in renal osteodystrophy: Comparison of dual energy X-ray absorptiometry and quantitative computed tomography. Vergleichende Untersuchungen mit der quantitativen Computertomographie und der Dual-Energy-X-Ray-Absorptiometrie zur Knochendichte bei renaler Osteopathie

    Energy Technology Data Exchange (ETDEWEB)

    Funke, M.; Maeurer, J.; Grabbe, E. (Abt. Roentgendiagnostik, Klinikum, Goettingen Univ. (Germany)); Scheler, F. (Abt. Nephrologie und Rheumatologie, Klinikum, Goettingen Univ. (Germany))

    1992-08-01

    Measurements of bone density were carried out in 25 patients on dialysis for terminal renal insufficiency, using quantitative computed tomography (QCT) and dual energy X-ray absorptiometry (DXA). Unlike in subjects with normal kidneys, there was no significant correlation between these methods in this series. Ten patients showed an increase in bone density of the vertebral spongiosa on QCT measurements, which was interpreted as due to osteosclerotic bone changes in renal osteopathy. QCT showed advantages over DXA in demonstrating these changes. (orig.).

  2. Improving abdomen tumor low-dose CT images using a fast dictionary learning based processing

    Science.gov (United States)

    Chen, Yang; Yin, Xindao; Shi, Luyao; Shu, Huazhong; Luo, Limin; Coatrieux, Jean-Louis; Toumoulin, Christine

    2013-08-01

    In abdomen computed tomography (CT), repeated radiation exposures are often inevitable for cancer patients who receive surgery or radiotherapy guided by CT images. Low-dose scans should thus be considered in order to avoid the harm of accumulative x-ray radiation. This work is aimed at improving abdomen tumor CT images from low-dose scans by using a fast dictionary learning (DL) based processing. Stemming from sparse representation theory, the proposed patch-based DL approach allows effective suppression of both mottled noise and streak artifacts. The experiments carried out on clinical data show that the proposed method brings encouraging improvements in abdomen low-dose CT images with tumors.

  3. A compressed sensing based reconstruction algorithm for synchrotron source propagation-based X-ray phase contrast computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Melli, Seyed Ali, E-mail: sem649@mail.usask.ca [Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK (Canada); Wahid, Khan A. [Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK (Canada); Babyn, Paul [Department of Medical Imaging, University of Saskatchewan, Saskatoon, SK (Canada); Montgomery, James [College of Medicine, University of Saskatchewan, Saskatoon, SK (Canada); Snead, Elisabeth [Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK (Canada); El-Gayed, Ali [College of Medicine, University of Saskatchewan, Saskatoon, SK (Canada); Pettitt, Murray; Wolkowski, Bailey [College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK (Canada); Wesolowski, Michal [Department of Medical Imaging, University of Saskatchewan, Saskatoon, SK (Canada)

    2016-01-11

    Synchrotron source propagation-based X-ray phase contrast computed tomography is increasingly used in pre-clinical imaging. However, it typically requires a large number of projections, and subsequently a large radiation dose, to produce high quality images. To improve the applicability of this imaging technique, reconstruction algorithms that can reduce the radiation dose and acquisition time without degrading image quality are needed. The proposed research focused on using a novel combination of Douglas–Rachford splitting and randomized Kaczmarz algorithms to solve large-scale total variation based optimization in a compressed sensing framework to reconstruct 2D images from a reduced number of projections. Visual assessment and quantitative performance evaluations of a synthetic abdomen phantom and real reconstructed image of an ex-vivo slice of canine prostate tissue demonstrate that the proposed algorithm is competitive in reconstruction process compared with other well-known algorithms. An additional potential benefit of reducing the number of projections would be reduction of time for motion artifact to occur if the sample moves during image acquisition. Use of this reconstruction algorithm to reduce the required number of projections in synchrotron source propagation-based X-ray phase contrast computed tomography is an effective form of dose reduction that may pave the way for imaging of in-vivo samples.

  4. Comparison of lens- and fiber-coupled CCD detectors for X-ray computed tomography.

    Science.gov (United States)

    Uesugi, K; Hoshino, M; Yagi, N

    2011-03-01

    X-ray imaging detectors with an identical phosphor and a CCD chip but employing lens- and fiber-coupling between them have been compared. These are designed for X-ray imaging experiments, especially computed tomography, at the medium-length beamline at the SPring-8 synchrotron radiation facility. It was found that the transmittance of light to the CCD is about four times higher in the fiber-coupled detector. The uniformity of response in the lens-coupled detector has a global shading of up to 40%, while pixel-to-pixel variation owing to a chicken-wire pattern was dominant in the fiber-coupled detector. Apart from the higher transmittance, the fiber-coupled detector has a few characteristics that require attention when it is used for computed tomography, which are browning of the fiber, discontinuity in the image, image distortion, and dark spots in the chicken-wire pattern. Thus, it is most suitable for high-speed tomography of samples that tend to deform, for example biological and soft materials.

  5. Priori mask guided image reconstruction (p-MGIR) for ultra-low dose cone-beam computed tomography

    Science.gov (United States)

    Park, Justin C.; Zhang, Hao; Chen, Yunmei; Fan, Qiyong; Kahler, Darren L.; Liu, Chihray; Lu, Bo

    2015-11-01

    Recently, the compressed sensing (CS) based iterative reconstruction method has received attention because of its ability to reconstruct cone beam computed tomography (CBCT) images with good quality using sparsely sampled or noisy projections, thus enabling dose reduction. However, some challenges remain. In particular, there is always a tradeoff between image resolution and noise/streak artifact reduction based on the amount of regularization weighting that is applied uniformly across the CBCT volume. The purpose of this study is to develop a novel low-dose CBCT reconstruction algorithm framework called priori mask guided image reconstruction (p-MGIR) that allows reconstruction of high-quality low-dose CBCT images while preserving the image resolution. In p-MGIR, the unknown CBCT volume was mathematically modeled as a combination of two regions: (1) where anatomical structures are complex, and (2) where intensities are relatively uniform. The priori mask, which is the key concept of the p-MGIR algorithm, was defined as the matrix that distinguishes between the two separate CBCT regions where the resolution needs to be preserved and where streak or noise needs to be suppressed. We then alternately updated each part of image by solving two sub-minimization problems iteratively, where one minimization was focused on preserving the edge information of the first part while the other concentrated on the removal of noise/artifacts from the latter part. To evaluate the performance of the p-MGIR algorithm, a numerical head-and-neck phantom, a Catphan 600 physical phantom, and a clinical head-and-neck cancer case were used for analysis. The results were compared with the standard Feldkamp-Davis-Kress as well as conventional CS-based algorithms. Examination of the p-MGIR algorithm showed that high-quality low-dose CBCT images can be reconstructed without compromising the image resolution. For both phantom and the patient cases, the p-MGIR is able to achieve a clinically

  6. Screening for lung cancer with low-dose CT.

    Science.gov (United States)

    Coche, E

    2008-01-01

    Lung cancer represents the leading cause of cancer-related mortality in the world. In the past, many attempts were made to detect the disease at an early stage and subsequently reduce its mortality. Chest X-ray was abandoned for this purpose. For several years low-dose computed tomography has been introduced as a potential tool for early screening in a high-risk population. As demonstrated in several papers, the task is not easy and researchers are faced with many difficulties. This paper reviews mainly the role of low-dose CT for early cancer screening. Results of past and current trials, controversies related to the high rate of lung nodules, cost-effectiveness, and delivered radiation dose to the patient are presented. Finally some limitations of low dose CT for lung cancer detection are explained.

  7. Design of a computer software for calculation of required barrier against radiation at the diagnostic x-ray units

    Directory of Open Access Journals (Sweden)

    S.A. Rahimi

    2005-01-01

    Full Text Available Background and purpose : Instalation of protective barrier against diagnostic x-ray is generally done based on the recommendations of NCRP49. There are analytic methods for designing protective barriers howerer, they lack sufficient efficiency and considering the NCRP49 reports, designing mechanical protective barrier in order to protect the initial x-ray radiation and absorption of the ray quality of such radiation is different.Therefore, the protective barrier for each radiation is measured separately. In this study, a computer software was designed to calculate the needed barrier with high accuracy.Materials and methods: Calculation of required protective barrier particularly when two or more generators are in use at diagnostic x-ray units and or installed diagnostic equipments do not have proper room space and the limitations for other clanges in parameters which are time- consuming and impossible to be manually calculated. For proper determination of thichness of the protective barrier, relevant information about curves of radiation weakness, dose limit etc should be entered. This program was done in windows and designed in such a way that the operator works easily, flexibility of the program is acceptable and its accuracy and sensitivity is high.Results : Results of this program indicate that, in most cases, in x-ray units required protective barrier was not used. Meanwhile sometimes shielding is more than what required which lacks technical standards and cost effectiveness. When the application index is contrasting zero, thichness of NCRP49 calculation is about 20% less than the calculated rate done by the method of this study. When the applied index is equal to zero (that is the only situation where the second barrier is considered, thickness of requined barrier is about 15% less than the lead barrier and concrete barrier calculated in this project is 8% less than that calculated by McGuire method.Conclusion : In this study proper

  8. Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging

    DEFF Research Database (Denmark)

    Markl, Daniel; Zeitler, J Axel; Rasch, Cecilie

    2016-01-01

    PURPOSE: A 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed...... imaging (TPI). METHODS: Printing was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed...... was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3). CONCLUSIONS: The 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from...

  9. Three-dimensional X-ray Computed Tomography: a new diagnostic tool for artistic and Cultural Heritage

    Directory of Open Access Journals (Sweden)

    Maria Pia Morigi

    2010-06-01

    Full Text Available Born in the early Seventies for medical applications, X-ray Computed Tomography is currently playing an increasingly important role in the field of Cultural Heritage diagnostics. It represents a powerful non-destructive investigation technique, capable of displaying in a three-dimensional way the volume and the internal structure of the investigated objects, also thanks to modern 3D rendering techniques. This article presents the results of some diagnostic tests carried out by our research group, in collaboration with major restoration centers, using transportable tomographic systems developed by us. In particular it will deal with case studies that highlight the versatility and potential of computed tomography as a tool of knowledge in the field of artistic and cultural heritage.

  10. X-Ray Crystallographic Analysis, EPR Studies, and Computational Calculations of a Cu(II) Tetramic Acid Complex

    Science.gov (United States)

    Matiadis, Dimitrios; Tsironis, Dimitrios; Stefanou, Valentina; Igglessi–Markopoulou, Olga; McKee, Vickie; Sanakis, Yiannis; Lazarou, Katerina N.

    2017-01-01

    In this work we present a structural and spectroscopic analysis of a copper(II) N-acetyl-5-arylidene tetramic acid by using both experimental and computational techniques. The crystal structure of the Cu(II) complex was determined by single crystal X-ray diffraction and shows that the copper ion lies on a centre of symmetry, with each ligand ion coordinated to two copper ions, forming a 2D sheet. Moreover, the EPR spectroscopic properties of the Cu(II) tetramic acid complex were also explored and discussed. Finally, a computational approach was performed in order to obtain a detailed and precise insight of product structures and properties. It is hoped that this study can enrich the field of functional supramolecular systems, giving place to the formation of coordination-driven self-assembly architectures. PMID:28316540

  11. Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging

    DEFF Research Database (Denmark)

    Markl, Daniel; Zeitler, J Axel; Rasch, Cecilie

    2017-01-01

    PURPOSE: A 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed...... imaging (TPI). METHODS: Printing was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed...... was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3). CONCLUSIONS: The 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from...

  12. Diagnostic accuracy of full-body linear X-ray scanning in multiple trauma patients in comparison to computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Joeres, A.P.W.; Heverhagen, J.T.; Bonel, H. [Inselspital - University Hospital Bern (Switzerland). Univ. Inst. of Diagnostic, Interventional and Pediatric Radiology; Exadaktylos, A. [Inselspital - University Hospital Bern (Switzerland). Dept. of Emergency Medicine; Klink, T. [Inselspital - University Hospital Bern (Switzerland). Univ. Inst. of Diagnostic, Interventional and Pediatric Radiology; Wuerzburg Univ. (Germany). Inst. of Diagnostic and Interventional Radiology

    2016-02-15

    The purpose of this study was to evaluate the diagnostic accuracy of full-body linear X-ray scanning (LS) in multiple trauma patients in comparison to 128-multislice computed tomography (MSCT). 106 multiple trauma patients (female: 33; male: 73) were retrospectively included in this study. All patients underwent LS of the whole body, including extremities, and MSCT covering the neck, thorax, abdomen, and pelvis. The diagnostic accuracy of LS for the detection of fractures of the truncal skeleton and pneumothoraces was evaluated in comparison to MSCT by two observers in consensus. Extremity fractures detected by LS were documented. The overall sensitivity of LS was 49.2%, the specificity was 93.3%, the positive predictive value was 91%, and the negative predictive value was 57.5%. The overall sensitivity for vertebral fractures was 16.7%, and the specificity was 100%. The sensitivity was 48.7% and the specificity 98.2% for all other fractures. Pneumothoraces were detected in 12 patients by CT, but not by LS.40 extremity fractures were detected by LS, of which 4 fractures were dislocated, and 2 were fully covered by MSCT. The diagnostic accuracy of LS is limited in the evaluation of acute trauma of the truncal skeleton. LS allows fast whole-body X-ray imaging, and may be valuable for detecting extremity fractures in trauma patients in addition to MSCT.

  13. Numerical research on the anisotropic transport of thermal neutron in heterogeneous porous media with micron X-ray computed tomography

    Science.gov (United States)

    Wang, Yong; Yue, Wenzheng; Zhang, Mo

    2016-06-01

    The anisotropic transport of thermal neutron in heterogeneous porous media is of great research interests in many fields. In this paper, it is the first time that a new model based on micron X-ray computed tomography (CT) has been proposed to simultaneously consider both the separation of matrix and pore and the distribution of mineral components. We apply the Monte Carlo method to simulate thermal neutrons transporting through the model along different directions, and meanwhile detect those unreacted thermal neutrons by an array detector on the other side of the model. Therefore, the anisotropy of pore structure can be imaged by the amount of received thermal neutrons, due to the difference of rock matrix and pore-filling fluids in the macroscopic reaction cross section (MRCS). The new model has been verified by the consistent between the simulated data and the pore distribution from X-ray CT. The results show that the evaluation of porosity can be affected by the anisotropy of media. Based on the research, a new formula is developed to describe the correlation between the resolution of array detectors and the quality of imaging. The formula can be further used to analyze the critical resolution and the suitable number of thermal neutrons emitted in each simulation. Unconventionally, we find that a higher resolution cannot always lead to a better image.

  14. 3D algebraic iterative reconstruction for cone-beam x-ray differential phase-contrast computed tomography.

    Science.gov (United States)

    Fu, Jian; Hu, Xinhua; Velroyen, Astrid; Bech, Martin; Jiang, Ming; Pfeiffer, Franz

    2015-01-01

    Due to the potential of compact imaging systems with magnified spatial resolution and contrast, cone-beam x-ray differential phase-contrast computed tomography (DPC-CT) has attracted significant interest. The current proposed FDK reconstruction algorithm with the Hilbert imaginary filter will induce severe cone-beam artifacts when the cone-beam angle becomes large. In this paper, we propose an algebraic iterative reconstruction (AIR) method for cone-beam DPC-CT and report its experiment results. This approach considers the reconstruction process as the optimization of a discrete representation of the object function to satisfy a system of equations that describes the cone-beam DPC-CT imaging modality. Unlike the conventional iterative algorithms for absorption-based CT, it involves the derivative operation to the forward projections of the reconstructed intermediate image to take into account the differential nature of the DPC projections. This method is based on the algebraic reconstruction technique, reconstructs the image ray by ray, and is expected to provide better derivative estimates in iterations. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a mini-focus x-ray tube source. It is shown that the proposed method can reduce the cone-beam artifacts and performs better than FDK under large cone-beam angles. This algorithm is of interest for future cone-beam DPC-CT applications.

  15. Permeability of laboratory-formed methane-hydrate-bearing sand: Measurements and observations using x-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, T. J.; Seol, Y.; Gupta, A.; Tomutsa, L.

    2010-09-15

    Methane hydrate was formed in two moist sands and a sand/silt mixture under a confining stress in an X-ray-transparent pressure vessel. Three initial water saturations were used to form three different methane-hydrate saturations in each medium. X-ray computed tomography (CT) was used to observe location-specific density changes caused by hydrate formation and flowing water. Gas-permeability measurements in each test for the dry, moist, frozen, and hydrate-bearing states are presented. As expected, the effective permeabilities (intrinsic permeability of the medium multiplied by the relative permeability) of the moist sands decreased with increasing moisture content. In a series of tests on a single sample, the effective permeability typically decreased as the pore space became more filled, in the order of dry, moist, frozen, and hydrate-bearing. In each test, water was flowed through the hydrate-bearing medium and we observed the location-specific changes in water saturation using CT scanning. We compared our data to a number of models, and our relative permeability data compare most favorably with models in which hydrate occupies the pore bodies rather than the pore throats. Inverse modeling (using the data collected from the tests) will be performed to extend the relative permeability measurements.

  16. X-ray computed tomography contrast agents prepared by seeded growth of gold nanoparticles in PEGylated dendrimer

    Science.gov (United States)

    Kojima, Chie; Umeda, Yasuhito; Ogawa, Mikako; Harada, Atsushi; Magata, Yasuhiro; Kono, Kenji

    2010-06-01

    Gold nanoparticles (Au NPs) are a potential x-ray computed tomography (CT) contrast agent. A biocompatible and bioinactive surface is necessary for application of gold nanoparticle to CT imaging. Polyethylene glycol (PEG)-attached dendrimers have been used as a drug carrier with long blood circulation. In this study, the Au NPs were grown in the PEGylated dendrimer to produce a CT contrast agent. The Au NPs were grown by adding gold ions and ascorbic acid at various equivalents to the Au NP-encapsulated dendrimer solution. Both size and surface plasmon absorption of the grown Au NPs increased with adding a large number of gold ions. The x-ray attenuation of the Au NPs also increased after the seeded growth. The Au NPs grown in the PEG-attached dendrimer at the maximum under our conditions exhibited a similar CT value to a commercial iodine agent, iopamidol, in vitro. The Au NP-loaded PEGylated dendrimer and iopamidol were injected into mice and CT images were obtained at different times. The Au NP-loaded PEGylated dendrimer achieved a blood pool imaging, which was greater than a commercial iodine agent. Even though iopamidol was excreted rapidly, the PEGylated dendrimer loading the grown Au NP was accumulated in the liver.

  17. Nondestructive material characterization of meteorites with synchrotron-based high energy x-ray phase micro-computed tomography

    Science.gov (United States)

    Liu, Huiqiang; Xiao, Tiqiao; Xie, Honglan; Fu, Yanan; Zhang, Xueliang; Fan, Xiaoxi

    2017-02-01

    Synchrotron radiation based x-ray propagation-based micro-computed tomography (SRPCT) has been widely used to nondestructively access 3D structural information in many fields in the last decade. However, for strongly absorbed objects with small density-differential compositions, conventional SRPCT technique fails in providing high-contrast images for visualization of objects characteristic information except edge-enhancements at interfaces or boundaries of samples. In this study, we successfully employed the SRPCT technique with phase retrieval, the high energy x-ray phase-attenuation-duality (PAD) algorithm, into nondestructive material characterization of invaluable meteorite samples due to the greatly enhanced phase-contrast of different bulk material areas, as compared to conventional SRPCT on equal dose basis. Our experimental results demonstrated the PAD-SRPCT technique is superior to conventional SRPCT technique to access density and structure distributions of different meteorite compositions with high density resolution, owing to the striking contrast-to-noise ratio (CNR). In addition, a new mass-density measurement method was presented to estimate the mass density of different compositions in the meteorite sample based on the calibration of the imaging system.

  18. X-ray computed tomography and aggregate image system (AIMS for studying hot mix asphalt and aggregates

    Directory of Open Access Journals (Sweden)

    Allex E. Álvarez Lugo

    2010-04-01

    Full Text Available Achieving reliable pavement design, durable roadway structures and effective maintenance and rehabilitation plans requires the suitable characterisation of the materials used in pavement construction. This paper describes two non-destructive techniques based on image acquisition and analysis and their successful application in pavement engi-neering: X-ray computed tomography (X-ray CT and aggregate imaging system (AIMS. The former has been used for characterising the internal structure of asphalt mixes to analyse and model their performance; it has been particu-larly used for studying the content, size, distribution and connectivity of air-voids and these variables’ relationship with moisture damage susceptibility, capillarity and permeability within the mixes. AIMS was intended for characterri-sing aggregates’ morphological properties (i.e., form, angularity and texture. This technique provides important ad-vantages regarding the standard methods used for obtaining the same aggregate properties: it is objective, reliable, reproducible and can be carried out quickly. This paper was aimed at describing these two techniques’ theoretical backgrounds, mention some recent applications and provide insight into how existing characterisation of materials used in pavement construction can be improved.

  19. Physical characterization and performance evaluation of an x-ray micro-computed tomography system for dimensional metrology applications

    Science.gov (United States)

    Hiller, Jochen; Maisl, Michael; Reindl, Leonard M.

    2012-08-01

    This paper presents physical and metrological characterization measurements conducted for an industrial x-ray micro-computed tomography (CT) system. As is well known in CT metrology, many factors, e.g., in the scanning and reconstruction process, the image processing, and the 3D data evaluation, influence the dimensional measurement properties of the system as a whole. Therefore, it is important to know what leads to, and what are the consequences of, e.g., a geometrical misalignment of the scanner system, image unsharpness (blurring), or noise or image artefacts. In our study, the two main components of a CT scanner, i.e. the x-ray tube and the flat-panel detector, are characterized. The contrast and noise transfer property of the scanner is obtained using image-processing methods based on linear systems theory. A long-term temperature measurement in the scanner cabinet has been carried out. The dimensional measurement property has been quantified by using a calibrated ball-bar and uncertainty budgeting. Information about the performance of a CT scanner system in terms of contrast and noise transmission and sources of geometrical errors will help plan CT scans more efficiently. In particular, it will minimize the user's influence by a systematic line of action, taking into account the physical and technical limitations and influences on dimensional measurements.

  20. Microstructure Characterization of SiC{sub f}/SiC Composites by X-ray Computed Microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Weon Ju; Kim, Dae Jong; Jung, Choong Hwan; Park, Ji Yeon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    There have also been efforts on applying the SiC{sub f}/SiC composites to fuel claddings of various types of reactors such as liquid salt-cooled advanced high temperature reactor (LSAHTR), gas-cooled fast reactor (GFR), sodium-cooled fast reactor (SFR), and light water reactor (LWR). In general, the chemical vapor infiltration (CVI) technique has been used most widely to produce SiC{sub f}/SiC composites. Although the technique produces a highly pure SiC matrix and thus an irradiation tolerant composite, it results in a complex distribution of porosity. The porosity consists of the interfiber micro porosity and interbundle/interply macro porosities. The complex geometry of porosity and fiber architecture also induces a highly anisotropic behavior of composite properties. The inhomogeneity of fiber reinforced composites renders the conventional, destructive metallographic techniques difficult to obtain representative microstructural features throughout the specimen volume. In this study, we applied X-ray computed microtomography (X-ray μCT) to nondestructively analyze the microstructure of SiC{sub f}/SiC composites. The pore structure and porosity distribution were analyzed for disk shape and triplex tubular SiC{sub f}/SiC composite specimens.

  1. A beam optics study of a modular multi-source X-ray tube for novel computed tomography applications

    Science.gov (United States)

    Walker, Brandon J.; Radtke, Jeff; Chen, Guang-Hong; Eliceiri, Kevin W.; Mackie, Thomas R.

    2017-10-01

    A modular implementation of a scanning multi-source X-ray tube is designed for the increasing number of multi-source imaging applications in computed tomography (CT). An electron beam array coupled with an oscillating magnetic deflector is proposed as a means for producing an X-ray focal spot at any position along a line. The preliminary multi-source model includes three thermionic electron guns that are deflected in tandem by a slowly varying magnetic field and pulsed according to a scanning sequence that is dependent on the intended imaging application. Particle tracking simulations with particle dynamics analysis software demonstrate that three 100 keV electron beams are laterally swept a combined distance of 15 cm over a stationary target with an oscillating magnetic field of 102 G perpendicular to the beam axis. Beam modulation is accomplished using 25 μs pulse widths to a grid electrode with a reverse gate bias of -500 V and an extraction voltage of +1000 V. Projected focal spot diameters are approximately 1 mm for 138 mA electron beams and the stationary target stays within thermal limits for the 14 kW module. This concept could be used as a research platform for investigating high-speed stationary CT scanners, for lowering dose with virtual fan beam formation, for reducing scatter radiation in cone-beam CT, or for other industrial applications.

  2. Synthesis, X-ray crystallographic, spectroscopic and computational studies of aminothiazole derivatives

    Science.gov (United States)

    Adeel, Muhammad; Braga, Ataualpa A. C.; Tahir, Muhammad Nawaz; Haq, Fazal; Khalid, Muhammad; Halim, Mohammad A.

    2017-03-01

    Aminothiazole organic compounds have diverse biological applications. Herein we report the synthesis of two aminothiazole derivatives: 4-(biphenyl-4-yl)thiazol-2-amine (1) and 4-(2‧,4‧-difluorobiphenyl-4-yl)thiazol-2-amine (2) via Suzuki-Miyaura cross coupling reaction. The chemical structures of 1 and 2 are confirmed using 1HNMR, 13CNMR, FT-IR, UV-Vis and single crystal x-ray studies. The XRD study reveals that the both solid state structures (1) and (2) are diffused to form poly chain structures due to presence of intra molecular hydrogen bonding (H.B). Furthermore, these compounds were analysed by density functional theory (DFT) at M06-2X/6-311G(d,p), B3LYP/6-31G(d) B3LYP/6-31G(d,p) and B3LYP/6-311G(2d,p) level of theories to obtain optimized geometry, electronic and spectroscopic properties. DFT optimized geometry supports the experimental XRD parameters. Natural bond orbital (NBO) calculation predicted the hyper conjugative interaction and hydrogen bonding in all derivatives. The FT-IR and thermodynamic studies also confirm the presence of hydrogen bonding network in the dimers which agrees well with the XRD results. Moreover, UV-Vis analysis reveals that maximum excitations take place in 1 and 2 due to HOMO → LUMO(98%) and HOMO → LUMO(97%) respectively which show good agreement to experimental data. The first order hyperpolarizability of both molecules is remarkably greater than the value of urea. The global reactivity parameters which are obtained by frontier molecular orbitals disclose that the molecules might be bioactive.

  3. Small-angle scattering computed tomography (SAS-CT) using a Talbot-Lau interferometerand a rotating anode x-ray tube:theory and experiments.

    Science.gov (United States)

    Chen, Guang-Hong; Bevins, Nicholas; Zambelli, Joseph; Qi, Zhihua

    2010-06-01

    X-ray differential phase contrast imaging methods, including projection imaging and the corresponding computed tomography (CT), have been implemented using a Talbot interferometer and either a synchrotron beam line or a low brilliance x-ray source generated by a stationary-anode x-ray tube. From small-angle scattering events which occur as an x-ray propagates through a medium, a signal intensity loss can be recorded and analyzed for an understanding of the micro-structures in an image object. This has been demonstrated using a Talbot-Lau interferometer and a stationary-anode x-ray tube. In this paper, theoretical principles and an experimental implementation of the corresponding CT imaging method are presented. First, a line integral is derived from analyzing the cross section of the small-angle scattering events. This method is referred to as small-angle scattering computed tomography (SAS-CT). Next, a Talbot-Lau interferometer and a rotating-anode x-ray tube were used to implement SAS-CT. A physical phantom and human breast tissue sample were used to demonstrate the reconstructed SAS-CT image volumes.

  4. Chest X Ray?

    Science.gov (United States)

    ... this page from the NHLBI on Twitter. Chest X Ray A chest x ray is a fast and painless imaging test ... tissue scarring, called fibrosis. Doctors may use chest x rays to see how well certain treatments are ...

  5. X-Rays

    Science.gov (United States)

    X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat ...

  6. Medical X-Rays

    Science.gov (United States)

    ... Benefits The discovery of X-rays and the invention of CT represented major advances in medicine. X- ... in X-ray and CT Examinations — X-ray definition, dose measurement, safety precautions, risk, and consideration with ...

  7. X-Ray Tomographic Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Bonnie Schmittberger

    2010-08-25

    Tomographic scans have revolutionized imaging techniques used in medical and biological research by resolving individual sample slices instead of several superimposed images that are obtained from regular x-ray scans. X-Ray fluorescence computed tomography, a more specific tomography technique, bombards the sample with synchrotron x-rays and detects the fluorescent photons emitted from the sample. However, since x-rays are attenuated as they pass through the sample, tomographic scans often produce images with erroneous low densities in areas where the x-rays have already passed through most of the sample. To correct for this and correctly reconstruct the data in order to obtain the most accurate images, a program employing iterative methods based on the inverse Radon transform was written. Applying this reconstruction method to a tomographic image recovered some of the lost densities, providing a more accurate image from which element concentrations and internal structure can be determined.

  8. X-ray microtomography at Shanghai Synchrotron Radiation facility

    Science.gov (United States)

    Chen, Rongchang; Xie, Honglan; Deng, Biao; Du, Guohao; Ren, Yuqi; Wang, Yudan; Zhou, Guangzhao; Tan, Hai; Yang, Yiming; Xu, Liang; Hu, Tao; Li, Qiao; Feng, Binggang; Wang, Feixiang; Xiao, Tiqiao

    2016-10-01

    BL13W, an X-ray imaging beamline has been built and opened to users since May 6, 2009. More than 70 user proposals per year are granted and implemented at the beamline, with about 500 user visits/year. Up to now, X-ray microtomography (XMCT) is the dominated method for BL13W user operation, more than 70% user experiments were carried out with XMCT, covering the research fields in material science, biomedicine, physics, environmental science, archaeology and paleontology. To meet the user requirements, micro-CT imaging methods based on a variety of contrast mechanisms, including absorption, phase contrast, X-ray fluorescence, have been developed. Algorithms and related software have been developed achieve the low dose and fast data collection. Quantitative analysis to the three dimensional CT images is highly emphasized and related software for 3D information extraction with high precision and high efficiency, has been developed. Three-dimensional structure evolution has been attracting more and more attention in many scientific research fields. Two-Hertz dynamic phase contrast CT based on monochromatic SR beam was established at SSRF. The limitation of fluorescence X-ray CT from practical applications is the data-collection efficiency. The ordered-subsets expectation maximization algorithm was inducted to improve practicability of X-ray fluorescence computed tomography (XFCT), greatly. A scheme for full field XFCT was also proposed.

  9. Computer-Controlled Cylindrical Polishing Process for Development of Grazing Incidence Optics for Hard X-Ray Region

    Science.gov (United States)

    Khan, Gufran Sayeed; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    The presentation includes grazing incidence X-ray optics, motivation and challenges, mid spatial frequency generation in cylindrical polishing, design considerations for polishing lap, simulation studies and experimental results, future scope, and summary. Topics include current status of replication optics technology, cylindrical polishing process using large size polishing lap, non-conformance of polishin lap to the optics, development of software and polishing machine, deterministic prediction of polishing, polishing experiment under optimum conditions, and polishing experiment based on known error profile. Future plans include determination of non-uniformity in the polishing lap compliance, development of a polishing sequence based on a known error profile of the specimen, software for generating a mandrel polishing sequence, design an development of a flexible polishing lap, and computer controlled localized polishing process.

  10. Standard practice for digital imaging and communication in nondestructive evaluation (DICONDE) for X-ray computed tomography (CT) test methods

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice facilitates the interoperability of X-ray computed tomography (CT) imaging equipment by specifying image data transfer and archival storage methods in commonly accepted terms. This document is intended to be used in conjunction with Practice E2339 on Digital Imaging and Communication in Nondestructive Evaluation (DICONDE). Practice E2339 defines an industrial adaptation of the NEMA Standards Publication titled Digital Imaging and Communications in Medicine (DICOM, see http://medical.nema.org), an international standard for image data acquisition, review, storage and archival storage. The goal of Practice E2339, commonly referred to as DICONDE, is to provide a standard that facilitates the display and analysis of NDE test results on any system conforming to the DICONDE standard. Toward that end, Practice E2339 provides a data dictionary and a set of information modules that are applicable to all NDE modalities. This practice supplements Practice E2339 by providing information object definitio...

  11. Quantification of seed-soil contact of sugar beet (Beta vulgaris) using X-ray Computed Tomography.

    Science.gov (United States)

    Blunk, Sebastian; Malik, Ali Hafeez; de Heer, Martine I; Ekblad, Tobias; Bussell, Jennifer; Sparkes, Debbie; Fredlund, Kenneth; Sturrock, Craig J; Mooney, Sacha J

    2017-01-01

    Seed-soil contact is important to ensure successful germination, however, there is a paucity of reported studies that have quantified the microstructure at and around this critical interface, mainly due to the opacity of soil. Here we describe a novel methodology to non-destructively calculate the seed-soil contact area using X-ray Computed Tomography. Under controlled conditions, we observed that seed-soil contact was strongly influenced by the size and type of seed, with a seed-soil contact of ca. 15% for naked sugar beet seeds compared to ca. 32% for pelleted and coated seeds. Similar results were obtained for seeds sampled from the field albeit with a higher spatial variability. By application of this new quantification method it is hoped seed enhancement technologies can be optimised and ultimately seedbed preparation improved to ensure better germination.

  12. High cone-angle x-ray computed micro-tomography with 186 GigaVoxel datasets

    Science.gov (United States)

    Myers, Glenn R.; Latham, Shane J.; Kingston, Andrew M.; Kolomazník, Jan; Krajíček, Václav; Krupka, TomáÅ.¡; Varslot, Trond K.; Sheppard, Adrian P.

    2016-10-01

    X-ray computed micro-tomography systems are able to collect data with sub-micron resolution. This high- resolution imaging has many applications but is particularly important in the study of porous materials, where the sub-micron structure can dictate large-scale physical properties (e.g. carbonates, shales, or human bone). Sample preparation and mounting become diffiult for these materials below 2mm diameter: consequently, a typical ultra-micro-CT reconstruction volume (with sub-micron resolution) will be around 3k x 3k x 10k voxels, with some reconstructions becoming much larger. In this paper, we discuss the hardware (MPI-parallel CPU/GPU) and software (python/C++/CUDA) tools used at the ANU CTlab to reconstruct 186 GigaVoxel datasets.

  13. Evaluation of Microstructure and Transport Properties of Deteriorated Cementitious Materials from Their X-ray Computed Tomography (CT Images

    Directory of Open Access Journals (Sweden)

    Michael Angelo B. Promentilla

    2016-05-01

    Full Text Available Pore structure, tortuosity and permeability are considered key properties of porous materials such as cement pastes to understand their long-term durability performance. Three-dimensional image analysis techniques were used in this study to quantify pore size, effective porosity, tortuosity, and permeability from the X-ray computed tomography (CT images of deteriorated pastes that were subjected to accelerated leaching test. X-ray microtomography is a noninvasive three-dimensional (3D imaging technique which has been recently gaining attention for material characterization. Coupled with 3D image analysis, the digitized pore can be extracted and computational simulation can be applied to the pore network to measure relevant microstructure and transport properties. At a spatial resolution of 0.50 μm, the effective porosity (ψe was found to be in the range of 0.04 to 0.33. The characteristic pore size (d using a local thickness algorithm was found to be in the range of 3 to 7 μm. The geometric tortuosity (τg based on a 3D random walk simulation in the percolating pore space was found to be in the range of 2.00 to 7.45. The water permeability values (K using US NIST Permeability Stokes Solver range from an order of magnitudes of 10−14 to 10−17 m2. Indications suggest that as effective porosity increases, the geometric tortuosity increases and the permeability decreases. Correlation among these microstructure and transport parameters is also presented in this study.

  14. A combination of high dose rate (10X FFF/2400 MU/min/10 MV X-rays) and total low dose (0.5 Gy) induces a higher rate of apoptosis in melanoma cells in vitro and superior preservation of normal melanocytes.

    Science.gov (United States)

    Sarojini, Sreeja; Pecora, Andrew; Milinovikj, Natasha; Barbiere, Joseph; Gupta, Saakshi; Hussain, Zeenathual M; Tuna, Mehmet; Jiang, Jennifer; Adrianzen, Laura; Jun, Jaewook; Catello, Laurice; Sanchez, Diana; Agarwal, Neha; Jeong, Stephanie; Jin, Youngjin; Remache, Yvonne; Goy, Andre; Ndlovu, Alois; Ingenito, Anthony; Suh, K Stephen

    2015-10-01

    The aim of this study was to determine the apoptotic effects, toxicity, and radiosensitization of total low dose irradiation delivered at a high dose rate in vitro to melanoma cells, normal human epidermal melanocytes (HEM), or normal human dermal fibroblasts (HDF) and to study the effect of mitochondrial inhibition in combination with radiation to enhance apoptosis in melanoma cells. Cells irradiated using 10X flattening filter-free (FFF) 10 MV X-rays at a dose rate of 400 or 2400 MU/min and a total dose of 0.25-8 Gy were analyzed by cell/colony counting, MitoTracker, MTT, and DNA-damage assays, as well as by quantitative real-time reverse transcriptase PCR in the presence or absence of mitochondrial respiration inhibitors. A dose rate of 2400 MU/min killed on average five-fold more melanoma cells than a dose rate 400 MU/min at a total dose of 0.5 Gy and preserved 80% survival of HEM and 90% survival of HDF. Increased apoptosis at the 2400 MU/min dose rate is mediated by greater DNA damage, reduced cell proliferation, upregulation of apoptotic genes, and downregulation of cell cycle genes. HEM and HDF were relatively unharmed at 2400 MU/min. Radiation induced upregulation of mitochondrial respiration in both normal and cancer cells, and blocking the respiration with inhibitors enhanced apoptosis only in melanoma cells. A high dose rate with a low total dose (2400 MU/min, 0.5 Gy/10X FFF 10 MV X-rays) enhances radiosensitivity of melanoma cells while reducing radiotoxicity toward HEM and HDF. Selective cytotoxicity of melanoma cells is increased by blocking mitochondrial respiration.

  15. Structural assignment of 6-oxy purine derivatives through computational modeling, synthesis, X-ray diffraction, and spectroscopic analysis.

    Science.gov (United States)

    Zhao, Xinyun; Chen, Xi; Yang, Guang-Fu; Zhan, Chang-Guo

    2010-05-27

    6-Oxy purine derivatives have been considered as potential therapeutic agents in various drug discovery efforts reported in the literature. However, the structural assignment of this important class of compounds has been controversial concerning the specific position of a hydrogen atom in the structure. To theoretically determine the most favorable type of tautomeric form of 6-oxy purine derivatives, we have carried out first-principles electronic structure calculations on the possible tautomeric forms (A, B, and C) and their relative stability of four representative 6-oxy purine derivatives (compounds 1-4). The computational results in both the gas phase and aqueous solution clearly reveal that the most favorable type of tautomeric form of these compounds is A, in which a hydrogen atom bonds with the N1 atom on the purine ring. To examine the computational results, one of the 6-oxy purine derivatives (i.e., compound 4) has been synthesized and its structure has been characterized by X-ray diffraction and spectroscopic analysis. All of the obtained computational and experimental data are consistent with the conclusion that the 6-oxy purine derivative exists in tautomer A. The conclusive structural assignment reported here is expected to be valuable for future computational studies on 6-oxy purine derivative binding with proteins and for computational drug design involving this type of compounds.

  16. Screening for lung cancer with low-dose computed tomography: grand rounds discussion from the Beth Israel Deaconess Medical Center.

    Science.gov (United States)

    Smetana, Gerald W; Boiselle, Phillip M; Schwartzstein, Richard M

    2015-04-21

    In December 2013, the U.S. Preventive Services Task Force recommended screening for lung cancer with low-dose computed tomography (LDCT) for selected current and former smokers. The Task Force based the recommendation primarily on the results of the NLST (National Lung Screening Trial). In this trial, patients randomly assigned to LDCT screening for 3 years had lower rates of both lung cancer-specific mortality and all-cause mortality (relative risk reduction, 6.7% [95% CI, 1.2% to 13.6%]; absolute risk reduction, 0.46% [CI, 0% to 0.9%]). Clinicians and health systems confront questions and challenges as they begin to implement lung cancer screening. This paper summarizes a conference during which an internist and a radiologist discuss the application of the Task Force recommendation to an individual patient.

  17. A Fast local Reconstruction algorithm by selective backprojection for Low-Dose in Dental Computed Tomography

    CERN Document Server

    Bin, Yan; Yu, Han; Feng, Zhang; Chao, Wang Xian; Lei, Li

    2013-01-01

    High radiation dose in computed tomography (CT) scans increases the lifetime risk of cancer, which become a major clinical concern. The backprojection-filtration (BPF) algorithm could reduce radiation dose by reconstructing images from truncated data in a short scan. In dental CT, it could reduce radiation dose for the teeth by using the projection acquired in a short scan, and could avoid irradiation to other part by using truncated projection. However, the limit of integration for backprojection varies per PI-line, resulting in low calculation efficiency and poor parallel performance. Recently, a tent BPF (T-BPF) has been proposed to improve calculation efficiency by rearranging projection. However, the memory-consuming data rebinning process is included. Accordingly, the chose-BPF (C-BPF) algorithm is proposed in this paper. In this algorithm, the derivative of projection is backprojected to the points whose x coordinate is less than that of the source focal spot to obtain the differentiated backprojection...

  18. X-Ray Astronomy

    Science.gov (United States)

    Wu, S. T.

    2000-01-01

    Dr. S. N. Zhang has lead a seven member group (Dr. Yuxin Feng, Mr. XuejunSun, Mr. Yongzhong Chen, Mr. Jun Lin, Mr. Yangsen Yao, and Ms. Xiaoling Zhang). This group has carried out the following activities: continued data analysis from space astrophysical missions CGRO, RXTE, ASCA and Chandra. Significant scientific results have been produced as results of their work. They discovered the three-layered accretion disk structure around black holes in X-ray binaries; their paper on this discovery is to appear in the prestigious Science magazine. They have also developed a new method for energy spectral analysis of black hole X-ray binaries; four papers on this topics were presented at the most recent Atlanta AAS meeting. They have also carried Monte-Carlo simulations of X-ray detectors, in support to the hardware development efforts at Marshall Space Flight Center (MSFC). These computation-intensive simulations have been carried out entirely on the computers at UAH. They have also carried out extensive simulations for astrophysical applications, taking advantage of the Monte-Carlo simulation codes developed previously at MSFC and further improved at UAH for detector simulations. One refereed paper and one contribution to conference proceedings have been resulted from this effort.

  19. Application study of 640-slice computed tomography low dose coronary angiography

    Directory of Open Access Journals (Sweden)

    Ziqiao Lei

    2015-01-01

    Full Text Available Objective: The aim was to explore image quality and radiation dose in patients with different heart rates in 640-slice volume computed tomography (CT coronary angiography by using tube voltage of 100 kV. Materials and Methods: The 220 consecutive patients clinically suspected or confirmed of coronary artery disease were divided into three groups: 67 cases in 1 beat group (heart rate 80 bpm. When scanning was completed, the best phase for coronary arteries would be chosen. Various postprocessing reconstructions of coronary arteries and branches, such as volume reconstruction (VR, maximum density projection, multiplanar reconstruction, curved surface reconstruction, were used. We classified image quality and made statistical analysis according to 4-grades method. We also compared scalability of coronary arterial segments and radiation doses between the groups. Results: There were no significant differences in the scalability of coronary arterial segments between the groups. Effective radiation doses of the three groups were (2.5±0.8 mSv, (8.4±3.1 mSv and (11.2±3.8mSv. The radiation doses between the groups showed statistical difference (P < 0.05. Conclusion: 640-slice volume CT can be adapted to changes during heart rate, and ensure the image quality under the condition of 100 kV, and radiation doses were significantly reduced in patients with heart rate <65 bpm.

  20. Using Hounsfield Units to Assess Osteoporotic Status on Wrist Computed Tomography Scans: Comparison With Dual Energy X-Ray Absorptiometry.

    Science.gov (United States)

    Johnson, Christine C; Gausden, Elizabeth B; Weiland, Andrew J; Lane, Joseph M; Schreiber, Joseph J

    2016-07-01

    Rates of evaluation and treatment for osteoporosis following distal radius fragility fractures remain low. As a subset of patients with these fractures undergo diagnostic computed tomography (CT) scan of the wrist, utilizing bone mineral density (BMD) measurements available with this imaging can be used to detect osteopenia or osteoporosis. This information may consequently prompt intervention to prevent a subsequent fracture. The purpose of this study was to determine if Hounsfield unit (HU) measurements at the wrist correlate with BMD measurements of the hip, femoral neck, and lumbar spine and to assess the ability of these HU measurements to detect osteoporosis of the hip. Forty-five female patients with distal radius fractures who underwent CT scan and dual energy x-ray absorptiometry scan as part of the management of their wrist fracture were identified. Bone mineral density measurements were made using the regional cancellous bone HU value at the capitate and compared with values obtained by a dual energy x-ray absorptiometry scan. Hounsfield unit values at the capitate were significantly correlated with BMD and t scores at the femoral neck, hip, and lumbar spine. An HU threshold of 307 in the capitate optimized sensitivity (86%) and specificity (94%) for detecting osteoporotic patients. By demonstrating that capitate HU measurements from clinical CT scans are correlated with BMD and t scores at the hip, femoral neck, and lumbar spine, our data suggest that clinical CT scans should have a role in detecting osteopenia and osteoporosis. Diagnostic III. Copyright © 2016 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  1. The nondestructive evaluation of high temperature conditioned concrete in conjunction with acoustic emission and x-ray computed tomography

    Science.gov (United States)

    Su, Yu-Min; Hou, Tsung-Chin; Lin, Li-Chiang; Chen, Gwan-Ying; Pan, Huang-Hsing

    2016-04-01

    Portland Cement Concrete plays a vital part of protecting structural rebars or steels when high-temperature fire incidents occur, that induces loss of evaporate water, dehydration of CH, and deconstruction of C-S-H. The objective of the study was to assess fire-damaged concrete in conjunction with nondestructive evaluation methods of acoustic emission, visual inspections, and X-ray computed tomography. The experimental program was to mix an Ordinary Portland Cement concrete firstly. Concrete cylinders with twenty-day moisture cure were treated in a furnace with 400 and 600°C for one hour. After temperature is cooled down, the concrete cylinders were brought to air or moisture re-curing for ten days. Due to the incident of the furnace, acoustic emission associated with splitting tensile strength test was not able to continue. Future efforts are planned to resume this unfinished task. However, two proposed tasks were executed and completed, namely visual inspections and voids analysis on segments obtained from X-ray CT facility. Results of visual inspections on cross-sectional and cylindrical length of specimens showed that both aggregates and cement pastes turned to pink or red at 600°C. More surface cracks were generated at 600°C than that at 400°C. On the other hand, voids analysis indicated that not many cracks were generated and voids were remedied at 400°C. However, a clear tendency was found that remedy by moisture curing may heal up to 2% voids of the concrete cylinder that was previously subject to 600°C of high temperature conditioning.

  2. Dosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging.

    Science.gov (United States)

    Grünheid, Thorsten; Kolbeck Schieck, Jacquelyn R; Pliska, Benjamin T; Ahmad, Mansur; Larson, Brent E

    2012-04-01

    Cone-beam computed tomography (CBCT) has become a routine imaging modality for many orthodontic clinics. However, questions remain about the amount of radiation patients are exposed to during the scans. This study determined the amounts of radiation potentially absorbed by a patient during orthodontic imaging with a CBCT machine with various scan settings compared with a conventional 2-dimensional digital x-ray machine. The radiation exposures delivered by a next generation i-CAT CBCT machine (Imaging Sciences International, Hatfield, Pa) at various scan settings and orthopantomograph OP100/OC100 digital x-ray machine (Instrumentarium Dental, Tuusula, Finland) during panoramic and cephalometric radiography were recorded using thermoluminescent dosimeters placed inside a head and neck phantom. The manufacturer-recommended settings for an average adult male were used for both types of machines. Effective doses were calculated using the tissue-weighting factors recommended by the 2007 International Commission on Radiological Protection. The effective doses at various voxel sizes and field of view settings ranged from 64.7 to 69.2 μSv for standard resolution CBCT scans (scan time 8.9 s) and 127.3 to 131.3 μSv for high resolution full field of view scans (scan time 17.8 s), and measured 134.2 μSv for a high-resolution landscape scan with a voxel size as would be used for SureSmile (OraMetrix, Richardson, Tex) therapy (scan time 26.9 s). The effective doses for digital panoramic and lateral cephalometric radiographs measured 21.5 and 4.5 μSv, respectively. CBCT, although providing additional diagnostic and therapeutic benefits, also exposes patients to higher levels of radiation than conventional digital radiography. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  3. X-ray computed microtomography of three-dimensional microcracks and self-healing in engineered cementitious composites

    Science.gov (United States)

    Fan, Shuai; Li, Mo

    2015-01-01

    Concrete cracking and deterioration can potentially be addressed by innovative self-healing cementitious materials, which can autogenously regain transport properties and mechanical characteristics after the damage self-healing process. For the development of such materials, it is crucial, but challenging, to precisely characterize the extent and quality of self-healing due to a variety of factors. This study adopted x-ray computed microtomography (μCT) to derive three-dimensional morphological data on microcracks before and after healing in engineered cementitious composite (ECC). Scanning electron microscope and energy dispersive x-ray spectroscopy were also used to morphologically and chemically analyze the healing products. This work showed that the evolution of the microcrack 3D structure due to self-healing in cementitious materials can be directly and quantitatively characterized by μCT. A detailed description of the μCT image analysis method applied to ECC self-healing was presented. The results revealed that the self-healing extent and rate strongly depended on initial surface crack width, with smaller crack width favoring fast and robust self-healing. We also found that the self-healing mechanism in cementitious materials is dependent on crack depth. The region of a crack close to the surface (from 0 to around 50-150 μm below the surface) can be sealed quickly with crystalline precipitates. However, at greater depths the healing process inside the crack takes a significantly longer time to occur, with healing products more likely resulting from continued hydration and pozzolanic reactions. Finally, the μCT method was compared with other self-healing characterization methods, with discussions on its importance in generating new scientific knowledge for the development of robust self-healing cementitious materials.

  4. Mcps-range photon-counting X-ray computed tomography system utilizing an oscillating linear-YAP(Ce) photon detector

    Science.gov (United States)

    Oda, Yasuyuki; Sato, Eiichi; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Osawa, Akihiro; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sugimura, Shigeaki; Endo, Haruyuki; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2011-07-01

    High-speed X-ray photon counting is useful for discriminating photon energy, and the counting can be used for constructing an X-ray computed tomography (CT) system. A photon-counting X-ray CT system consists of an X-ray generator, a turntable, an oscillation linear detector, a two-stage controller, a multipixel photon counter (MPPC) module, a 1.0 mm-thick crystal (scintillator) of YAP(Ce) (cerium-doped yttrium aluminum perovskite), a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeating the linear scanning and the rotation of an object, and projection curves of the object are obtained by the linear scanning using the detector consisting of an MPPC module, the YAP(Ce), and a scan stage. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. Because the lower level of the photon energy was roughly determined by a comparator in the module, the average photon energy of the X-ray spectra increased with increase in the lower-level voltage of the comparator at a constant tube voltage. The maximum count rate was approximately 3 Mcps (mega counts per second), and photon-counting CT was carried out.

  5. High-speed classification of coherent X-ray diffraction patterns on the K computer for high-resolution single biomolecule imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tokuhisa, Atsushi [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Arai, Junya [The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Joti, Yasumasa [JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Ohno, Yoshiyuki; Kameyama, Toyohisa; Yamamoto, Keiji; Hatanaka, Masayuki; Gerofi, Balazs; Shimada, Akio; Kurokawa, Motoyoshi; Shoji, Fumiyoshi [RIKEN Advanced Institute for Computational Science, 7-1-26 Minatojima-minami-machi, Chuo-ku, Kobe, Hyogo 650-0047 (Japan); Okada, Kensuke [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Sugimoto, Takashi [JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Yamaga, Mitsuhiro; Tanaka, Ryotaro [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Yokokawa, Mitsuo; Hori, Atsushi [RIKEN Advanced Institute for Computational Science, 7-1-26 Minatojima-minami-machi, Chuo-ku, Kobe, Hyogo 650-0047 (Japan); Ishikawa, Yutaka, E-mail: ishikawa@is.s.u-tokyo.ac.jp [The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hatsui, Takaki, E-mail: ishikawa@is.s.u-tokyo.ac.jp [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Go, Nobuhiro [Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 (Japan)

    2013-11-01

    A code with an algorithm for high-speed classification of X-ray diffraction patterns has been developed. Results obtained for a set of 1 × 10{sup 6} simulated diffraction patterns are also reported. Single-particle coherent X-ray diffraction imaging using an X-ray free-electron laser has the potential to reveal the three-dimensional structure of a biological supra-molecule at sub-nanometer resolution. In order to realise this method, it is necessary to analyze as many as 1 × 10{sup 6} noisy X-ray diffraction patterns, each for an unknown random target orientation. To cope with the severe quantum noise, patterns need to be classified according to their similarities and average similar patterns to improve the signal-to-noise ratio. A high-speed scalable scheme has been developed to carry out classification on the K computer, a 10PFLOPS supercomputer at RIKEN Advanced Institute for Computational Science. It is designed to work on the real-time basis with the experimental diffraction pattern collection at the X-ray free-electron laser facility SACLA so that the result of classification can be feedback for optimizing experimental parameters during the experiment. The present status of our effort developing the system and also a result of application to a set of simulated diffraction patterns is reported. About 1 × 10{sup 6} diffraction patterns were successfully classificatied by running 255 separate 1 h jobs in 385-node mode.

  6. Screening for lung cancer with low-dose computed tomography; Bronchialkarzinom-Screening mit Niedrigdosis-CT. Aktueller Stand

    Energy Technology Data Exchange (ETDEWEB)

    Diederich, S.; Wormanns, D.; Heindel, W. [Muenster Univ. (Germany). Inst. fuer Klinische Radiologie

    2001-03-01

    Lung cancer is the most common cause of death from malignancy. It is characterized by a favourable prognosis when treated in early stages and a poor prognosis in advanced stages. Populations at risk are relatively well defined, i.e. heavy smokers and workers exposed to asbestos and radon. Therefore, early detection using diagnostic techniques promises reduction of mortality from this tumor. Previous studies using chest radiography and sputum cytology were, however, disappointing due to poor sensitivity of these tests for early tumor stages. The new technique of low-dose computed tomography provides both high sensitivity for small tumors and a comfortable examination. As small benign pulmonary nodules are common reliable non-invasive diagnostic algorithms are required for classification of nodules. Preliminary studies using low-dose CT screening in smokers have provided promising results. Prior to a wide application of the technique in clinical routine more data are required as to inclusion criteria, examination intervals and the effect of screening on mortality reduction. (orig.) [German] Das Bronchialkarzinom ist der am haeufigsten zum Tode fuehrende maligne Tumor. Seine Prognose ist bei einer Therapie in fruehen Stadien relativ gut, in fortgeschrittenen Erkrankungsstadien dagegen ausgesprochen schlecht. Die Risikopopulationen sind gut charakterisiert, v.a. starke Raucher und Personen mit einer beruflichen Asbest- bzw. Radonexposition. Vor diesem Hintergrund erscheinen Frueherkennungsuntersuchungen mittels diagnostischer Verfahren sinnvoll, um die Sterblichkeit an diesem Tumor zu senken. Bisherige Erfahrungen mit Thoraxroentgenaufnahmen und Sputumuntersuchungen waren aufgrund der geringen Sensitivitaet der Verfahren fuer fruehe Tumorstadien jedoch enttaeuschend. Das relativ neue Verfahren der Niedrigdosis-Computertomographie des Thorax verbindet eine hohe Sensitivitaet fuer kleine Tumoren mit einer geringen Belastung der untersuchten Person. Wegen der Haeufigkeit

  7. Measurement Uncertainty Evaluation in Dimensional X-ray Computed Tomography Using the Bootstrap Method

    DEFF Research Database (Denmark)

    Hiller, Jochen; Genta, Gianfranco; Barbato, Giulio

    2014-01-01

    Industrial applications of computed tomography (CT) for dimensional metrology on various components are fast increasing, owing to a number of favorable properties such as capability of non-destructive internal measurements. Uncertainty evaluation is however more complex than in conventional measu...

  8. Attenuation correction for X-ray emission computed tomography of laser-produced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yen-Wei; Nakao, Zensho [Ryukyus Univ., Nishihara, Okinawa (Japan). Faculty of Engineering; Tamura, Shinichi

    1996-08-01

    An attenuation correction method was proposed for laser-produced plasma emission computed tomography (ECT), which is based on a relation of the attenuation coefficient and the emission coefficient in plasma. Simulation results show that the reconstructed images are dramatically improved in comparison to the reconstructions without attenuation correction. (J.P.N.)

  9. Stabilizing dual-energy X-ray computed tomography reconstructions using patch-based regularization

    CERN Document Server

    Tracey, Brian H

    2014-01-01

    Recent years have seen growing interest in exploiting dual- and multi-energy measurements in computed tomography (CT) in order to characterize material properties as well as object shape. Material characterization is performed by decomposing the scene into constitutive basis functions, such as Compton scatter and photoelectric absorption functions. While well motivated physically, the joint recovery of the spatial distribution of photoelectric and Compton properties is severely complicated by the fact that the data are several orders of magnitude more sensitive to Compton scatter coefficients than to photoelectric absorption, so small errors in Compton estimates can create large artifacts in the photoelectric estimate. To address these issues, we propose a model-based iterative approach which uses patch-based regularization terms to stabilize inversion of photoelectric coefficients, and solve the resulting problem though use of computationally attractive Alternating Direction Method of Multipliers (ADMM) solu...

  10. Synchrotron X-ray computed laminography of the three-dimensional anatomy of tomato leaves.

    Science.gov (United States)

    Verboven, Pieter; Herremans, Els; Helfen, Lukas; Ho, Quang T; Abera, Metadel; Baumbach, Tilo; Wevers, Martine; Nicolaï, Bart M

    2015-01-01

    Synchrotron radiation computed laminography (SR-CL) is presented as an imaging method for analyzing the three-dimensional (3D) anatomy of leaves. The SR-CL method was used to provide 3D images of 1-mm² samples of intact leaves at a pixel resolution of 750 nm. The method allowed visualization and quantitative analysis of palisade and spongy mesophyll cells, and showed local venation patterns, aspects of xylem vascular structure and stomata. The method failed to image subcellular organelles such as chloroplasts. We constructed 3D computer models of leaves that can provide a basis for calculating gas exchange, light penetration and water and solute transport. The leaf anatomy of two different tomato genotypes grown in saturating light conditions was compared by 3D analysis. Differences were found in calculated values of tissue porosity, cell number density, cell area to volume ratio and cell volume and cell shape distributions of palisade and spongy cell layers. In contrast, the exposed cell area to leaf area ratio in mesophyll, a descriptor that correlates to the maximum rate of photosynthesis in saturated light conditions, was no different between spongy and palisade cells or between genotypes. The use of 3D image processing avoids many of the limitations of anatomical analysis with two-dimensional sections.

  11. A computationally efficient method for automatic registration of orthogonal x-ray images with volumetric CT data

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xin [ADSIP Research Centre, University of Central Lancashire, Preston (United Kingdom); Varley, Martin R [ADSIP Research Centre, University of Central Lancashire, Preston (United Kingdom); Shark, Lik-Kwan [ADSIP Research Centre, University of Central Lancashire, Preston (United Kingdom); Shentall, Glyn S [Rosemere Cancer Centre, Royal Preston Hospital, Preston (United Kingdom); Kirby, Mike C [Satellite Centres, Christie Hospital NHS Foundation Trust, Manchester (United Kingdom)

    2008-02-21

    The paper presents a computationally efficient 3D-2D image registration algorithm for automatic pre-treatment validation in radiotherapy. The novel aspects of the algorithm include (a) a hybrid cost function based on partial digitally reconstructed radiographs (DRRs) generated along projected anatomical contours and a level set term for similarity measurement; and (b) a fast search method based on parabola fitting and sensitivity-based search order. Using CT and orthogonal x-ray images from a skull and a pelvis phantom, the proposed algorithm is compared with the conventional ray-casting full DRR based registration method. Not only is the algorithm shown to be computationally more efficient with registration time being reduced by a factor of 8, but also the algorithm is shown to offer 50% higher capture range allowing the initial patient displacement up to 15 mm (measured by mean target registration error). For the simulated data, high registration accuracy with average errors of 0.53 mm {+-} 0.12 mm for translation and 0.61 deg, {+-} 0.29 deg. for rotation within the capture range has been achieved. For the tested phantom data, the algorithm has also shown to be robust without being affected by artificial markers in the image.

  12. A computationally efficient method for automatic registration of orthogonal x-ray images with volumetric CT data

    Science.gov (United States)

    Chen, Xin; Varley, Martin R.; Shark, Lik-Kwan; Shentall, Glyn S.; Kirby, Mike C.

    2008-02-01

    The paper presents a computationally efficient 3D-2D image registration algorithm for automatic pre-treatment validation in radiotherapy. The novel aspects of the algorithm include (a) a hybrid cost function based on partial digitally reconstructed radiographs (DRRs) generated along projected anatomical contours and a level set term for similarity measurement; and (b) a fast search method based on parabola fitting and sensitivity-based search order. Using CT and orthogonal x-ray images from a skull and a pelvis phantom, the proposed algorithm is compared with the conventional ray-casting full DRR based registration method. Not only is the algorithm shown to be computationally more efficient with registration time being reduced by a factor of 8, but also the algorithm is shown to offer 50% higher capture range allowing the initial patient displacement up to 15 mm (measured by mean target registration error). For the simulated data, high registration accuracy with average errors of 0.53 mm ± 0.12 mm for translation and 0.61° ± 0.29° for rotation within the capture range has been achieved. For the tested phantom data, the algorithm has also shown to be robust without being affected by artificial markers in the image.

  13. Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging.

    Science.gov (United States)

    Markl, Daniel; Zeitler, J Axel; Rasch, Cecilie; Michaelsen, Maria Høtoft; Müllertz, Anette; Rantanen, Jukka; Rades, Thomas; Bøtker, Johan

    2017-05-01

    A 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed imaging (TPI). Printing was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed compartmentalised structures and in vitro drug release determined. A clear difference in terms of pore structure between PVA and PLA prints was observed by extracting the porosity (5.5% for PVA and 0.2% for PLA prints), pore length and pore volume from the XμCT data. The print resolution and accuracy was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3). The 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from the designed model. The microstructural information extracted by XμCT and TPI will assist to gain a better understanding about the performance of 3D printed dosage forms.

  14. 3-D reconstruction of an ancient Egyptian mummy using X-ray computer tomography.

    Science.gov (United States)

    Baldock, C; Hughes, S W; Whittaker, D K; Taylor, J; Davis, R; Spencer, A J; Tonge, K; Sofat, A

    1994-12-01

    Computer tomography has been used to image and reconstruct in 3-D an Egyptian mummy from the collection of the British Museum. This study of Tjentmutengebtiu, a priestess from the 22nd dynasty (945-715 BC) revealed invaluable information of a scientific, Egyptological and palaeopathological nature without mutilation and destruction of the painted cartonnage case or linen wrappings. Precise details on the removal of the brain through the nasal cavity and the viscera from the abdominal cavity were obtained. The nature and composition of the false eyes were investigated. The detailed analysis of the teeth provided a much closer approximation of age at death. The identification of materials used for the various amulets including that of the figures placed in the viscera was graphically demonstrated using this technique.

  15. Internal structure of a vermicular ironstone as determined by X-ray computed tomography scanning

    Energy Technology Data Exchange (ETDEWEB)

    Zinn, Yuri Lopes, E-mail: ylzinn@dcs.ufla.br [Universidade Federal de Lavras (UFLA), Lavras, MG (Brazil). Departamento de Ciencia do Solo; Carducci, Carla Eloize [Universidade Federal de Santa Catarina (UFSC), Curitibanos, SC (Brazil). Departamento de Agronomia; Araujo, Marla Alessandra [Universidade Federal de Lavras (UFLA), Lavras, MG (Brazil). Programa de Pos-graduacao em Ciencia do Solo

    2015-03-15

    Ironstones or petroplinthites are common materials in soils under humid tropical climate, generally defined as the result of Fe oxide accumulation in areas where the water table oscillates, and may exhibit considerable morphological variability. The aim of this study was to examine the internal structure and porosity of an ironstone fragment from a Petroferric Acrudox in Minas Gerais, Brazil, by computed tomography (CT) and conventional techniques. The sample analyzed had total porosity of 59.5 %, with large macropores in the form of tubular channels and irregular vughs, the latter with variable degrees of infilling by material released from the ironstone walls or the soil matrix. The CT scan also showed that the ironstone has wide variation in the density of the solid phase, most likely due to higher concentrations or thick intergrowths of hematite and magnetite/maghemite, especially in its outer rims. The implications of these results for water retention and soil formation in ironstone environments are briefly discussed. (author)

  16. Electroencephalographic and computed X-ray tomographic findings in 99 Japanese cases of herpes simplex encephalitis

    Energy Technology Data Exchange (ETDEWEB)

    Kamei, Satoshi; Takasu, Toshiaki; Tamura, Masato; Otani, Sugishi.

    1988-10-01

    This is a retrospective analysis of electroencephalograms (EEG) and computed tomograms (CT) obtained from 99 Japanese patients with herpes simplex encephalitis (HSE). Abnormal findings of EEG were seen in 89 patients (99 %). Focal abnormality, which was frequently detected in the first EEG recording, was seen in 68 patients (76 %). Periodic synchronous discharge was observed in 25 patients (28 %). There were abnormal findings on CT in 88 patients (81 %). Low and high density areas were seen in 64 patients (73 %) and 26 patients (37 %), respectively, with the most frequent site being the temporal lobe. Mass effect was demonstrated in 33 patients (37 %). Electroencephalography detected the abnormal findings earlier than CT during the early stage of HSE in many instances. There was concordance between EEG and CT in the detection of HSE lesions in 45 patients (58 %). (Namekawa, K.).

  17. EFFECTS OF X-RAY BEAM ANGLE AND GEOMETRIC DISTORTION ON WIDTH OF EQUINE THORACOLUMBAR INTERSPINOUS SPACES USING RADIOGRAPHY AND COMPUTED TOMOGRAPHY

    DEFF Research Database (Denmark)

    Djernaes, Julie D.; Nielsen, Jon V.; Berg, Lise C.

    2017-01-01

    study was to determine whether X-ray beam angle has an effect on apparent widths of interspinous spaces. Thoracolumbar spine specimens were collected from six equine cadavers and left-right lateral radiographs and sagittal and dorsal reconstructed computed tomographic (CT) images were acquired...

  18. INTERNAL STRUCTURE OF A VERMICULAR IRONSTONE AS DETERMINED BY X-RAY COMPUTED TOMOGRAPHY SCANNING

    Directory of Open Access Journals (Sweden)

    Yuri Lopes Zinn

    2015-04-01

    Full Text Available Ironstones or petroplinthites are common materials in soils under humid tropical climate, generally defined as the result of Fe oxide accumulation in areas where the water table oscillates, and may exhibit considerable morphological variability. The aim of this study was to examine the internal structure and porosity of an ironstone fragment from a Petroferric Acrudox in Minas Gerais, Brazil, by computed tomography (CT and conventional techniques. The sample analyzed had total porosity of 59.5 %, with large macropores in the form of tubular channels and irregular vughs, the latter with variable degrees of infilling by material released from the ironstone walls or the soil matrix. The CT scan also showed that the ironstone has wide variation in the density of the solid phase, most likely due to higher concentrations or thick intergrowths of hematite and magnetite/maghemite, especially in its outer rims. The implications of these results for water retention and soil formation in ironstone environments are briefly discussed.

  19. X-ray micro computed tomography for the visualization of an atherosclerotic human coronary artery

    Science.gov (United States)

    Matviykiv, Sofiya; Buscema, Marzia; Deyhle, Hans; Pfohl, Thomas; Zumbuehl, Andreas; Saxer, Till; Müller, Bert

    2017-06-01

    Atherosclerosis refers to narrowing or blocking of blood vessels that can lead to a heart attack, chest pain or stroke. Constricted segments of diseased arteries exhibit considerably increased wall shear stress, compared to the healthy ones. One of the possibilities to improve patient’s treatment is the application of nano-therapeutic approaches, based on shear stress sensitive nano-containers. In order to tailor the chemical composition and subsequent physical properties of such liposomes, one has to know precisely the morphology of critically stenosed arteries at micrometre resolution. It is often obtained by means of histology, which has the drawback of offering only two-dimensional information. Additionally, it requires the artery to be decalcified before sectioning, which might lead to deformations within the tissue. Micro computed tomography (μCT) enables the three-dimensional (3D) visualization of soft and hard tissues at micrometre level. μCT allows lumen segmentation that is crucial for subsequent flow simulation analysis. In this communication, tomographic images of a human coronary artery before and after decalcification are qualitatively and quantitatively compared. We analyse the cross section of the diseased human coronary artery before and after decalcification, and calculate the lumen area of both samples.

  20. TU-A-9A-05: First Experimental Demonstration of the Anisotropic Detection Principle in X-Ray Fluorescence Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M; Bazalova, M; Fahrig, R; Xing, L [Stanford University, Stanford, CA (United States)

    2014-06-15

    Purpose: To improve the sensitivity of X-ray fluorescence computed tomography (XFCT) for in vivo molecular imaging. Is the maximum sensitivity achieved with an isotropic (4π) detector configuration? We prove that this is not necessarily true, and that a greater sensitivity is possible with anisotropic detector configuration. Methods: An XFCT imaging system was constructed consisting of 1) a collimated pencil beam x-ray source using a fluoroscopy grade x-ray tube; 2) a CdTe x-ray photon counting detector to detect fluorescent x-rays; and 3) a rotation/translation stage for tomographic imaging. We created a 6.5-cm diameter water phantom with 2-cm inserts of low gold concentration (0.25%–1%) to simulate tumors targeted by gold nano-particles. The placement of x-ray fluorescence detector were chosen to minimize scatter x-rays. XFCT imaging was performed at three different detector positions (60°, 90°, 145°) to determine the impact of forward-scatter, side-scatter, and back-scatter on imaging performance. The three data sets were also combined to estimate the imaging performance with an isotropic detector. Results: The highest imaging performance was achieved when the XF detector was in the backscatter 145° configuration. The signal-to-noise ratio (SNR) was 5.5 for the 0.25% gold concentration compared to SNRs of 1.4, 0, and 2.4 for 60°, 90°, and combined (60°+90°+145°) datasets. Only the 145° detector arrangement alone could detect the 0.25% concentration. The imaging dose was 14 mGy for each detector arrangement experiment. Conclusion: This study experimentally proves, for the fist time, the Anisotropic Detection Principle in XF imaging, which holds that optimized anisotropic x-ray fluorescence detection provides greater sensitivity than isotropic detection. The optimized detection arrangement was used to improve the sensitivity of the XFCT experiment. The achieved XFCT sensitivity is the highest ever for a phantom at least this large using a benchtop x-ray

  1. Photonic Material Selection of Scintillation Crystals Using Monte Carlo Method for X-Ray Detection in Industrial Computed Tomography

    Directory of Open Access Journals (Sweden)

    Peng He

    2014-01-01

    Full Text Available Currently industrial X-CT system is designed according to characteristics of test objects, and test objects determine industrial X-CT system structure, X-ray detector/sensor property, scanning mode, and so forth. So there are no uniform standards for the geometry size of scintillation crystals of detector. Moreover, scintillation crystals are usually mixed with some highly toxic impurity elements, such as Tl and Cd. Thus, it is indispensable for establishing guidelines of engineering practice to simulate X-ray detection performances of different scintillation crystals. This paper focuses on how to achieve high efficient X-ray detection in industrial X-CT system which used Monte Carlo (MC method to study X-ray energy straggling characteristics, full energy peak efficiency, and conversion efficiency of some scintillation crystals (e.g., CsI(Tl, NaI(Tl, and CdWO4 after X-ray interacted with these scintillation crystals. Our experimental results demonstrate that CsI(Tl scintillation crystal has the advantages of conversion efficiency, spectral matching, manufacturing process, and full energy peak efficiency; it is an ideal choice for high efficient X-ray detection in industrial X-CT system.

  2. 3D non-destructive fluorescent X-ray computed tomography (FXCT) with a CdTe array

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Chang Yeon; Lee, Won Ho; Kim, Young Hak [Dept. of Bio-convergence Engineering, Korea University Graduate School, Seoul (Korea, Republic of)

    2015-10-15

    In our research, the material was exposed to an X-ray and not only the conventional transmission image but also 3D images based on the information of characteristic X-ray detected by a 2D CdTe planar detector array were reconstructed. Since atoms have their own characteristic X-ray energy, our system was able to discriminate materials of even a same density if the materials were composed of different atomic numbers. We applied FXCT to distinguish various unknown materials with similar densities. The materials with similar densities were clearly distinguished in the 3D reconstructed images based on the information of the detected characteristic X-ray, while they were not discriminated from each other in the images based on the information of the detected transmission X-ray. In the fused images consisting of 3D transmitted and characteristic X-ray images, all of the positions, densities and atomic numbers of materials enclosed in plastic phantom or pipe were clearly identified by analyzing energy, position and amount of detected radiation.

  3. Petrophysical analysis of limestone rocks by nuclear logging and 3D high-resolution X-ray computed microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, M.F.S. [Nuclear Instrumentation Laboratory, COPPE-PEN, UFRJ, P.O. Box 68509, 21941-972 Rio de Janeiro, RJ (Brazil); Lima, I., E-mail: inaya@lin.ufrj.br [Nuclear Instrumentation Laboratory, COPPE-PEN, UFRJ, P.O. Box 68509, 21941-972 Rio de Janeiro, RJ (Brazil); Department of Mechanical Engineering and Energy, IPRJ-UERJ, Nova Friburgo, RJ (Brazil); Ferrucio, P.L.; Abreu, C.J.; Borghi, L. [Geology Department, Geosciences Institute, Rio de Janeiro Federal University, Rio de Janeiro, RJ (Brazil); Lopes, R.T. [Nuclear Instrumentation Laboratory, COPPE-PEN, UFRJ, P.O. Box 68509, 21941-972 Rio de Janeiro, RJ (Brazil)

    2011-10-01

    This study presents the pore-space system analysis of the 2-ITAB-1-RJ well cores, which were drilled in the Sao Jose do Itaborai Basin, in the state of Rio de Janeiro, Brasil. The analysis presented herein has been developed based on two techniques: nuclear logging and 3D high-resolution X-ray computed microtomography. Nuclear logging has been proven to be the technique that provides better quality and more quantitative information about the porosity using radioactive sources. The Density Gamma Probe and the Neutron Sonde used in this work provide qualitative information about bulk density variations and compensated porosity of the geological formation. The samples obtained from the well cores were analyzed by microtomography. The use of this technique in sedimentary rocks allows quantitative evaluation of pore system and generates high-resolution 3D images ({approx}microns order). The images and data obtained by microtomography were integrated with the response obtained by nuclear logging. The results obtained by these two techniques allow the understanding of the pore-size distribution and connectivity, as well as the porosity values. Both techniques are important and they complement each other.

  4. Computational modelling of the cerebral cortical microvasculature: effect of x-ray microbeams versus broad beam irradiation

    Science.gov (United States)

    Merrem, A.; Bartzsch, S.; Laissue, J.; Oelfke, U.

    2017-05-01

    Microbeam Radiation Therapy is an innovative pre-clinical strategy which uses arrays of parallel, tens of micrometres wide kilo-voltage photon beams to treat tumours. These x-ray beams are typically generated on a synchrotron source. It was shown that these beam geometries allow exceptional normal tissue sparing from radiation damage while still being effective in tumour ablation. A final biological explanation for this enhanced therapeutic ratio has still not been found, some experimental data support an important role of the vasculature. In this work, the effect of microbeams on a normal microvascular network of the cerebral cortex was assessed in computer simulations and compared to the effect of homogeneous, seamless exposures at equal energy absorption. The anatomy of a cerebral microvascular network and the inflicted radiation damage were simulated to closely mimic experimental data using a novel probabilistic model of radiation damage to blood vessels. It was found that the spatial dose fractionation by microbeam arrays significantly decreased the vascular damage. The higher the peak-to-valley dose ratio, the more pronounced the sparing effect. Simulations of the radiation damage as a function of morphological parameters of the vascular network demonstrated that the distribution of blood vessel radii is a key parameter determining both the overall radiation damage of the vasculature and the dose-dependent differential effect of microbeam irradiation.

  5. Changes in bone macro- and microstructure in diabetic obese mice revealed by high resolution microfocus X-ray computed tomography

    Science.gov (United States)

    Kerckhofs, G.; Durand, M.; Vangoitsenhoven, R.; Marin, C.; van der Schueren, B.; Carmeliet, G.; Luyten, F. P.; Geris, L.; Vandamme, K.

    2016-10-01

    High resolution microfocus X-ray computed tomography (HR-microCT) was employed to characterize the structural alterations of the cortical and trabecular bone in a mouse model of obesity-driven type 2 diabetes (T2DM). C57Bl/6J mice were randomly assigned for 14 weeks to either a control diet-fed (CTRL) or a high fat diet (HFD)-fed group developing obesity, hyperglycaemia and insulin resistance. The HFD group showed an increased trabecular thickness and a decreased trabecular number compared to CTRL animals. Midshaft tibia intracortical porosity was assessed at two spatial image resolutions. At 2 μm scale, no change was observed in the intracortical structure. At 1 μm scale, a decrease in the cortical vascular porosity of the HFD bone was evidenced. The study of a group of 8 week old animals corresponding to animals at the start of the diet challenge revealed that the decreased vascular porosity was T2DM-dependant and not related to the ageing process. Our results offer an unprecedented ultra-characterization of the T2DM compromised skeletal micro-architecture and highlight an unrevealed T2DM-related decrease in the cortical vascular porosity, potentially affecting the bone health and fragility. Additionally, it provides some insights into the technical challenge facing the assessment of the rodent bone structure using HR-microCT imaging.

  6. X-ray computed microtomography as a tool for the comparative morphological characterization of Proceratophrys bigibbosa species

    Energy Technology Data Exchange (ETDEWEB)

    Ahmann, Francielle da Silva; Evseev, Ivan; Paz, Manoela Guimaraes Ferreira da; Lingnau, Rodrigo, E-mail: evseev@utfpr.edu.b, E-mail: rodrigolingnau@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Francisco Beltrao, PR (Brazil); Ievsieieva, Ievgeniia; Assis, Joaquim T. de, E-mail: ievsieieva@iprj.uerj.b, E-mail: joaquim@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico; Alves, Haimon D.L. [Universidade Federal do Rio de Janeiro (PEN/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Energia Nuclear

    2011-07-01

    The Proceratophrys bigibbosa species group is characterized by the presence of postocular swellings and absence of hornlike palpebral appendages. A new member of this group was described recently from southern Brazil: Proceratophrys brauni. Its body size is between the smaller Proceratophrys avelinoi and the larger Proceratophrys bigibbosa species, both living in the same region. As the external appearance of these three members of the group is very similar to each other, it is interesting to discover a specific morphological categorization through internal characteristics, such as the cranium's proportions. In this paper, we report the preliminary results for comparative cranium's morphological characterization of Proceratophrys bigibbosa species from Brazil using the X-ray computed Microtomography technique through Skyscan 1174 system. Five samples of each three species, i.e., fifteen samples in total, were scanned. The tomographic slice images were reconstructed by SkyScan software. Then, these 2D images were used to create the cranium's models by 3D DOCTOR software. The main result is that some visible differences in the cranium's proportions of the species were observed. (author)

  7. Bayesian 3D X-ray computed tomography image reconstruction with a scaled Gaussian mixture prior model

    Science.gov (United States)

    Wang, Li; Gac, Nicolas; Mohammad-Djafari, Ali

    2015-01-01

    In order to improve quality of 3D X-ray tomography reconstruction for Non Destructive Testing (NDT), we investigate in this paper hierarchical Bayesian methods. In NDT, useful prior information on the volume like the limited number of materials or the presence of homogeneous area can be included in the iterative reconstruction algorithms. In hierarchical Bayesian methods, not only the volume is estimated thanks to the prior model of the volume but also the hyper parameters of this prior. This additional complexity in the reconstruction methods when applied to large volumes (from 5123 to 81923 voxels) results in an increasing computational cost. To reduce it, the hierarchical Bayesian methods investigated in this paper lead to an algorithm acceleration by Variational Bayesian Approximation (VBA) [1] and hardware acceleration thanks to projection and back-projection operators paralleled on many core processors like GPU [2]. In this paper, we will consider a Student-t prior on the gradient of the image implemented in a hierarchical way [3, 4, 1]. Operators H (forward or projection) and Ht (adjoint or back-projection) implanted in multi-GPU [2] have been used in this study. Different methods will be evalued on synthetic volume "Shepp and Logan" in terms of quality and time of reconstruction. We used several simple regularizations of order 1 and order 2. Other prior models also exists [5]. Sometimes for a discrete image, we can do the segmentation and reconstruction at the same time, then the reconstruction can be done with less projections.

  8. Application of X-ray Computed Tomography in Characterization Microstrueture Changes of Cement Pastes in Carbonation Process

    Institute of Scientific and Technical Information of China (English)

    HAN Jiande; SUN Wei; PAN Ganghua; WANG Caihui; RONG Hui

    2012-01-01

    The microstructure characteristics and meso-defect volume changes of hardened cement paste before and after carbonation were investigated by three-dimensional (3D) X-ray computed tomography (XCT),where three types water-to-cement ratio of 0.53,0.35 and 0.23 were considered.The high-resolution 3D images of microstructure and filtered defects were reconstructed by an XCT VG Studio MAX 2.0 software.The mesodefect volume fractions and size distribution were analyzed based on 3D images through add-on modules of 3D defect analysis.The 3D meso-defects volume fractions before carbonation were 0.79%,0.38% and 0.05%corresponding to w/c ratio=0.53,0.35 and 0.23,respectively.The 3D meso-defects volume fractions after carbonation were 2.44%,0.91% and 0.14% corresponding to w/c ratio=0.53,0.35 and 0.23,respectively.The experimental results suggest that 3D meso-defects volume fractions after carbonation for above three w/c ratio increased significantly.At the same time,meso-cracks distribution of the carbonation shrinkage and gray values changes of the different w/c ratio and carbonation reactions were also investigated.

  9. X-ray computed-tomography observations of water flow through anisotropic methane hydrate-bearing sand

    Energy Technology Data Exchange (ETDEWEB)

    Seol, Yongkoo; Kneafsey, Timothy J.

    2009-06-01

    We used X-ray computed tomography (CT) to image and quantify the effect of a heterogeneous sand grain-size distribution on the formation and dissociation of methane hydrate, as well as the effect on water flow through the heterogeneous hydrate-bearing sand. A 28 cm long sand column was packed with several segments having vertical and horizontal layers with sands of different grain-size distributions. During the hydrate formation, water redistribution occurred. Observations of water flow through the hydrate-bearing sands showed that water was imbibed more readily into the fine sand, and that higher hydrate saturation increased water imbibition in the coarse sand due to increased capillary strength. Hydrate dissociation induced by depressurization resulted in different flow patterns with the different grain sizes and hydrate saturations, but the relationships between dissociation rates and the grain sizes could not be identified using the CT images. The formation, presence, and dissociation of hydrate in the pore space dramatically impact water saturation and flow in the system.

  10. Level-set reconstruction algorithm for ultrafast limited-angle X-ray computed tomography of two-phase flows.

    Science.gov (United States)

    Bieberle, M; Hampel, U

    2015-06-13

    Tomographic image reconstruction is based on recovering an object distribution from its projections, which have been acquired from all angular views around the object. If the angular range is limited to less than 180° of parallel projections, typical reconstruction artefacts arise when using standard algorithms. To compensate for this, specialized algorithms using a priori information about the object need to be applied. The application behind this work is ultrafast limited-angle X-ray computed tomography of two-phase flows. Here, only a binary distribution of the two phases needs to be reconstructed, which reduces the complexity of the inverse problem. To solve it, a new reconstruction algorithm (LSR) based on the level-set method is proposed. It includes one force function term accounting for matching the projection data and one incorporating a curvature-dependent smoothing of the phase boundary. The algorithm has been validated using simulated as well as measured projections of known structures, and its performance has been compared to the algebraic reconstruction technique and a binary derivative of it. The validation as well as the application of the level-set reconstruction on a dynamic two-phase flow demonstrated its applicability and its advantages over other reconstruction algorithms. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  11. Compression-recovery model of absorptive glass mat (AGM) separator guided by X-ray micro-computed tomography analysis

    Science.gov (United States)

    Kameswara Rao, P. V.; Rawal, Amit; Kumar, Vijay; Rajput, Krishn Gopal

    2017-10-01

    Absorptive glass mat (AGM) separators play a key role in enhancing the cycle life of the valve regulated lead acid (VRLA) batteries by maintaining the elastic characteristics under a defined level of compression force with the plates of the electrodes. Inevitably, there are inherent challenges to maintain the required level of compression characteristics of AGM separators during the charge and discharge of the battery. Herein, we report a three-dimensional (3D) analytical model for predicting the compression-recovery behavior of AGM separators by formulating a direct relationship with the constituent fiber and structural parameters. The analytical model of compression-recovery behavior of AGM separators has successfully included the fiber slippage criterion and internal friction losses. The presented work uses, for the first time, 3D data of fiber orientation from X-ray micro-computed tomography, for predicting the compression-recovery behavior of AGM separators. A comparison has been made between the theoretical and experimental results of compression-recovery behavior of AGM samples with defined fiber orientation characteristics. In general, the theory agreed reasonably well with the experimental results of AGM samples in both dry and wet states. Through theoretical modeling, fiber volume fraction was established as one of the key structural parameters that modulates the compression hysteresis of an AGM separator.

  12. Combined high-energy synchrotron X-ray diffraction and computed tomography to characterize constitutive behavior of silica sand

    Energy Technology Data Exchange (ETDEWEB)

    Cil, Mehmet B., E-mail: mcil@utk.edu [Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Alshibli, Khalid, E-mail: Alshibli@utk.edu [Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Kenesei, Peter, E-mail: kenesei@aps.anl.gov [Argonne National Laboratory, Argonne, IL (United States); Lienert, Ulrich, E-mail: ulrich.lienert@desy.de [Deutsches Elektronen-Synchrotron, DESY Photon Science, Hamburg (Germany)

    2014-04-01

    The deformation behavior of silica sand particles under one-dimensional (1D) loading compression was investigated using nondestructive 3D synchrotron micro-computed tomography (SMT) and three dimensional X-ray diffraction (3DXRD). High-resolution SMT images were used to monitor particle-to-particle interactions, and the onset and propagation of fracture mechanism in a column composed of three silica sand particles. Particle-averaged lattice strain tensors within individual sand particles were measured using the 3DXRD technique and were then used to calculate the stress tensor components via the general elastic stress–strain relationship. The normal stress component in the axial direction (σ{sub zz}) exhibited a nearly linear increasing trend in all sand particles. Shear stress components were in general small relative to the normal stress components and displayed no systematic trend. Knowing lattice strains, stresses, and particle kinematic behavior, one can formulate and develop a micromechanics-based constitutive model to fully characterize strength properties and deformation characteristics of granular materials.

  13. Failure analysis of fuel cell electrodes using three-dimensional multi-length scale X-ray computed tomography

    Science.gov (United States)

    Pokhrel, A.; El Hannach, M.; Orfino, F. P.; Dutta, M.; Kjeang, E.

    2016-10-01

    X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Comparative tomography data sets are acquired for a conditioned beginning of life (BOL) and a degraded end of life (EOL) membrane electrode assembly subjected to cathode degradation by voltage cycling. Micro length scale analysis shows a five-fold increase in crack size and 57% thickness reduction in the EOL cathode catalyst layer, indicating widespread action of carbon corrosion. Complementary nano length scale analysis shows a significant reduction in porosity, increased pore size, and dramatically reduced effective diffusivity within the remaining porous structure of the catalyst layer at EOL. Collapsing of the structure is evident from the combination of thinning and reduced porosity, as uniquely determined by the multi-length scale approach. Additionally, a novel image processing based technique developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels shows an increase in ionomer volume fraction, Pt/C agglomerates, and severe carbon corrosion at the catalyst layer/membrane interface at EOL. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

  14. Potential and limitations of X-Ray micro-computed tomography in arthropod neuroanatomy: a methodological and comparative survey.

    Science.gov (United States)

    Sombke, Andy; Lipke, Elisabeth; Michalik, Peter; Uhl, Gabriele; Harzsch, Steffen

    2015-06-01

    Classical histology or immunohistochemistry combined with fluorescence or confocal laser scanning microscopy are common techniques in arthropod neuroanatomy, and these methods often require time-consuming and difficult dissections and sample preparations. Moreover, these methods are prone to artifacts due to compression and distortion of tissues, which often result in information loss and especially affect the spatial relationships of the examined parts of the nervous system in their natural anatomical context. Noninvasive approaches such as X-ray micro-computed tomography (micro-CT) can overcome such limitations and have been shown to be a valuable tool for understanding and visualizing internal anatomy and structural complexity. Nevertheless, knowledge about the potential of this method for analyzing the anatomy and organization of nervous systems, especially of taxa with smaller body size (e.g., many arthropods), is limited. This study set out to analyze the brains of selected arthropods with micro-CT, and to compare these results with available histological and immunohistochemical data. Specifically, we explored the influence of different sample preparation procedures. Our study shows that micro-CT is highly suitable for analyzing arthropod neuroarchitecture in situ and allows specific neuropils to be distinguished within the brain to extract quantitative data such as neuropil volumes. Moreover, data acquisition is considerably faster compared with many classical histological techniques. Thus, we conclude that micro-CT is highly suitable for targeting neuroanatomy, as it reduces the risk of artifacts and is faster than classical techniques. © 2015 Wiley Periodicals, Inc.

  15. Advanced characterization of pores and fractures in coals by nuclear magnetic resonance and X-ray computed tomography

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper demonstrates capabilities of low-field nuclear magnetic resonance (NMR) and microfocus X-ray computed tomography (μCT) in advanced, nondestructive, and quantitative characterization of pore types, producible porosity, pore structure, and spatial disposition of pore-fractures in coals. Results show that the NMR transverse relaxation time (T2) at 0.5–2.5, 20–50, and >100 ms correspond to pores of <0.1 μm, >0.1 μm, and fractures, respectively. A much higher T2 spectrum peak reflects a much better development of pores (or fractures) corresponding to the T2, and vice versa. Three basic components in coals, i.e., the pores (or fractures), coal matrix, and minerals have their distinctive range of CT numbers. Among these, the CT number of pores is commonly less than 600 HU. The producible porosity, which is a determination of permeability, can be calculated by T2 cutoff value (T2C) of coal NMR. The coal pore structure can be efficiently estimated by the newly proposed "T2C based model". Finally, μCT scan was proven capable of modeling and spatial visualization of pores and fractures.

  16. Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

    Energy Technology Data Exchange (ETDEWEB)

    Mitroglou, N.; Lorenzi, M.; Gavaises, M. [City University London, School of Mathematics Computer Science and Engineering, London (United Kingdom); Santini, M. [University of Bergamo, Department of Engineering, Bergamo (Italy)

    2016-11-15

    The flow inside a purpose built enlarged single-orifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and high-speed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can be a reliable tool for cavitation in nozzle orifices operating under nominal steady-state conditions. (orig.)

  17. Synchrotron-radiation-based X-ray micro-computed tomography reveals dental bur debris under dental composite restorations.

    Science.gov (United States)

    Hedayat, Assem; Nagy, Nicole; Packota, Garnet; Monteith, Judy; Allen, Darcy; Wysokinski, Tomasz; Zhu, Ning

    2016-05-01

    Dental burs are used extensively in dentistry to mechanically prepare tooth structures for restorations (fillings), yet little has been reported on the bur debris left behind in the teeth, and whether it poses potential health risks to patients. Here it is aimed to image dental bur debris under dental fillings, and allude to the potential health hazards that can be caused by this debris when left in direct contact with the biological surroundings, specifically when the debris is made of a non-biocompatible material. Non-destructive micro-computed tomography using the BioMedical Imaging & Therapy facility 05ID-2 beamline at the Canadian Light Source was pursued at 50 keV and at a pixel size of 4 µm to image dental bur fragments under a composite resin dental filling. The bur's cutting edges that produced the fragment were also chemically analyzed. The technique revealed dental bur fragments of different sizes in different locations on the floor of the prepared surface of the teeth and under the filling, which places them in direct contact with the dentinal tubules and the dentinal fluid circulating within them. Dispersive X-ray spectroscopy elemental analysis of the dental bur edges revealed that the fragments are made of tungsten carbide-cobalt, which is bio-incompatible.

  18. Analysis and accurate reconstruction of incomplete data in X-ray differential phase-contrast computed tomography.

    Science.gov (United States)

    Fu, Jian; Tan, Renbo; Chen, Liyuan

    2014-01-01

    X-ray differential phase-contrast computed tomography (DPC-CT) is a powerful physical and biochemical analysis tool. In practical applications, there are often challenges for DPC-CT due to insufficient data caused by few-view, bad or missing detector channels, or limited scanning angular range. They occur quite frequently because of experimental constraints from imaging hardware, scanning geometry, and the exposure dose delivered to living specimens. In this work, we analyze the influence of incomplete data on DPC-CT image reconstruction. Then, a reconstruction method is developed and investigated for incomplete data DPC-CT. It is based on an algebraic iteration reconstruction technique, which minimizes the image total variation and permits accurate tomographic imaging with less data. This work comprises a numerical study of the method and its experimental verification using a dataset measured at the W2 beamline of the storage ring DORIS III equipped with a Talbot-Lau interferometer. The numerical and experimental results demonstrate that the presented method can handle incomplete data. It will be of interest for a wide range of DPC-CT applications in medicine, biology, and nondestructive testing.

  19. X-ray detectors in axial computed tomography development; Sensori di radiazioni X negli sviluppi della tomografia assiale computerizzata

    Energy Technology Data Exchange (ETDEWEB)

    Gislon, R.; Imperiali, F. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Innovazione

    1996-12-01

    The increase of potentially of axial computed tomography as a non destructive investigation method in industrial field is particularly tied to the development of the X-rays detectors. The transition from the first gas ionization detectors to the last semiconductor detectors has indeed dramatically increased the performances of tomographic systems. In this report, after a quick analysis of fundamental principles of tomography, the most significant parameters for a detector to be used in a tomographic system are reviewed. The examination of the principal kinds of detectors that have been up to now used, with their working schemes, allows to delineate their characteristics and so to compare them with the ideal detector sketched above. The necessity of using high definition arrays brings to put into evidence the inadequacy of both gas and liquid ionization detectors and also of those types of light conversion devices which utilize for signal amplification a photomultiplier tube. Systems based on charge coupled devices or on a light conversion obtained with semiconductor photodiode arrays are definitely to be preferred. The progress of the last years in microelectronic technologies has brought great improvements in this field.

  20. Characterization of Fatigue Fractures in Closed-Cell Aluminum Foam Using x-ray Micro-Computed Tomography

    Science.gov (United States)

    Kafka, O. L.; Ingraham, M. D.; Morrison, D. J.; Issen, K. A.

    2014-03-01

    A post-mortem study of Alporas closed-cell aluminum foam specimens previously failed under strain-controlled fully reversed tension-compression fatigue was conducted using x-ray micro-computed tomography (μCT). Volumetric renders of the 3D structure of the material were produced. Fractures were identified and marked throughout voxel-based images of the specimens. This produced a 3D plot of fracture locations. At high strain amplitudes (0.175-0.5%), fractures formed an interconnected planar zone oriented approximately perpendicular to the loading axis; typically, the angle of the plane differed from that of a tension failure. Conversely, at low strain amplitudes (0.05-0.1%), short fractures have been formed diffusely within the specimen. In both cases, observed fractures were tortuous. Our previous work with surface strain mapping via digital image correlation (DIC) suggested that for all strain amplitudes, a crack, evidenced by a zone of high extensile strain, was formed and propagated through the material. This result was confirmed at high strain amplitudes, but not at low strain amplitudes. The discrepancy is attributed to three potential causes. Using DIC, short cracks cannot be accurately resolved with relatively coarse light intensity patterns. DIC images indicate fractures under load, while μCT imaging was conducted under zero load. Finally, the localized extension seen in DIC images could be attributed to strain with no resultant fractures.

  1. X-Ray Computed Tomography Analysis of Sajau Coal, Berau Basin, Indonesia: 3D Imaging of Cleat and Microcleat Characteristics

    Directory of Open Access Journals (Sweden)

    Ahmad Helman Hamdani

    2015-01-01

    Full Text Available The Pliocene Sajau coals of the Berau Basin area have a moderately to highly developed cleat system. Mostly the cleat fractures are well developed in both bright and dull bands, and these cleats are generally inclined or perpendicular to the bedding planes of the seam. The presence of cleat networks/fractures in coal seam is the important point in coalbed methane prospect. The 3D X-ray computed tomography (CT technique was performed to identify cleats characteristics in the Sajau coal seams, such as the direction of coal cleats, geometry of cleat, and cleats mineralization. By CT scan imaging technique two different types of natural fractures observed in Sajau coals have been identified, that is, face cleats and butt cleats. This technique also identified the direction of face cleats and butt cleats as shown in the resulting 3D images. Based on the images, face cleats show a NNE-SSW direction while butt cleats have a NW-SE direction. The crosscutting relationship indicated that NNE-SSW cleats were formed earlier than NW-SE cleats. The procedure also identified the types of minerals that filled the cleats apertures. Based on their density, the minerals are categorized as follows: very high density minerals (pyrite, high density minerals (anastase, and low density minerals (kaolinite, calcite were identified filling the cleats aperture.

  2. Mechanism to induce scoliosis in Duchenne muscular dystrophy; A study of paraspinal muscle by X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Noriaki; Fujimoto, Yasuyo (National Nishinara Hosital, Nara (Japan)); Takayanagi, Tetsuya; Mano, Yukio

    1992-09-01

    We studied the mechanism to induce scoliosis in Duchenne muscular dystrophy (DMD) by use of X-ray computed tomography (CT) of paraspinal muscles. CT examination of paraspinal muscles was performed on 15 DMD patients at the following six levels: (1) Th3 vertebrae (upper thoracic spine level); (2) Th6 vertebrae (middle thoracic spine level); (3) Th10 vertebrae (lower thoracic spine level); (4) L1 vertebrae (upper lumbar spine level); (5) L3 vertebrae (middle lumbar spine level); (6) L5 vertebrae (lower lumbar spine level). We evaluated the degeneration of paraspinal muscle by a decrese in ratio-density of the muscle which indicates infiltration of fatty tissue. The degeneration of the lateral portion of paraspinal muscle was more marked than that of the medial portion. The muscle was most severely affected at the middle lumbar spine level, showing a tendency to increase degeneration at the lower level of the spine. In cases showing laterality of the degeneration of paraspinal muscle, the less affected muscle on CT was located at the convex site of scoliosis. We speculate that the scoliosis occurs when DMD patients have asymmetrical paraspinal muscle degeneration, leading them to take compensatory posture. (author).

  3. X-ray phase-contrast computed tomography visualizes the microstructure and degradation profile of implanted biodegradable scaffolds after spinal cord injury

    Energy Technology Data Exchange (ETDEWEB)

    Takashima, Kenta, E-mail: takashima-k@med.tohoku.ac.jp [Tohoku University Graduate School of Medicine, Sendai (Japan); University of Tokyo, Tokyo (Japan); Hoshino, Masato; Uesugi, Kentaro; Yagi, Naoto [SPring-8, Hyogo (Japan); Matsuda, Shojiro [Gunze Limited, Shiga (Japan); Nakahira, Atsushi [Osaka Prefecture University, Osaka (Japan); Osumi, Noriko; Kohzuki, Masahiro [Tohoku University Graduate School of Medicine, Sendai (Japan); Onodera, Hiroshi [University of Tokyo, Tokyo (Japan)

    2015-01-01

    X-ray phase-contrast computed tomography imaging based on the Talbot grating interferometer is described, and the way it can visualize the polyglycolic acid scaffold, including its microfibres, after implantation into the injured spinal cord is shown. Tissue engineering strategies for spinal cord repair are a primary focus of translational medicine after spinal cord injury (SCI). Many tissue engineering strategies employ three-dimensional scaffolds, which are made of biodegradable materials and have microstructure incorporated with viable cells and bioactive molecules to promote new tissue generation and functional recovery after SCI. It is therefore important to develop an imaging system that visualizes both the microstructure of three-dimensional scaffolds and their degradation process after SCI. Here, X-ray phase-contrast computed tomography imaging based on the Talbot grating interferometer is described and it is shown how it can visualize the polyglycolic acid scaffold, including its microfibres, after implantation into the injured spinal cord. Furthermore, X-ray phase-contrast computed tomography images revealed that degradation occurred from the end to the centre of the braided scaffold in the 28 days after implantation into the injured spinal cord. The present report provides the first demonstration of an imaging technique that visualizes both the microstructure and degradation of biodegradable scaffolds in SCI research. X-ray phase-contrast imaging based on the Talbot grating interferometer is a versatile technique that can be used for a broad range of preclinical applications in tissue engineering strategies.

  4. Osteoporosis markers on low-dose lung cancer screening chest computed tomography scans predict all-cause mortality

    Energy Technology Data Exchange (ETDEWEB)

    Buckens, C.F. [University Medical Center Utrecht, Radiology Department, Utrecht (Netherlands); University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Utrecht (Netherlands); Graaf, Y. van der [University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Utrecht (Netherlands); Verkooijen, H.M.; Mali, W.P.; Jong, P.A. de [University Medical Center Utrecht, Radiology Department, Utrecht (Netherlands); Isgum, I.; Mol, C.P. [University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands); Verhaar, H.J. [University Medical Center Utrecht, Department of Geriatric Medicine, Utrecht (Netherlands); Vliegenthart, R.; Oudkerk, M. [Medical Center Groningen, Department of Radiology, Utrecht (Netherlands); Aalst, C.M. van; Koning, H.J. de [Erasmus MC Rotterdam, Department of Public Health, Rotterdam (Netherlands)

    2015-01-15

    Further survival benefits may be gained from low-dose chest computed tomography (CT) by assessing vertebral fractures and bone density. We sought to assess the association between CT-measured vertebral fractures and bone density with all-cause mortality in lung cancer screening participants. Following a case-cohort design, lung cancer screening trial participants (N = 3,673) who died (N = 196) during a median follow-up of 6 years (inter-quartile range: 5.7-6.3) were identified and added to a random sample of N = 383 from the trial. We assessed vertebral fractures using Genant and acute;s semiquantative method on sagittal reconstructions and measured bone density (Hounsfield Units (HU)) in vertebrae. Cox proportional hazards modelling was used to determine if vertebral fractures or bone density were independently predictive of mortality. The prevalence of vertebral fractures was 35 % (95 % confidence interval 30-40 %) among survivors and 51 % (44-58 %) amongst cases. After adjusting for age, gender, smoking status, pack years smoked, coronary and aortic calcium volume and pulmonary emphysema, the adjusted hazard ratio (HR) for vertebral fracture was 2.04 (1.43-2.92). For each 10 HU decline in trabecular bone density, the adjusted HR was 1.08 (1.02-1.15). Vertebral fractures and bone density are independently associated with all-cause mortality. (orig.)

  5. Low-dose computed tomography for lung cancer screening: comparison of performance between annual and biennial screen

    Energy Technology Data Exchange (ETDEWEB)

    Sverzellati, Nicola; Silva, M. [University of Parma, Radiology, Department of Surgical Sciences, Parma (Italy); Calareso, G.; Marchiano, A. [Fondazione IRCCS Istituto Nazionale dei Tumori, Department of Radiology, Milan (Italy); Galeone, C. [University of Milano-Bicocca, Department of Statistics and Quantitative Methods, Division of Biostatistics, Epidemiology and Public Health, Laboratory of Healthcare Research and Pharmacoepidemiology, Milan (Italy); Sestini, S.; Pastorino, U. [Fondazione IRCCS Istituto Nazionale dei Tumori, Department of Surgery, Section of Thoracic Surgery, Milan (Italy); Sozzi, G. [Fondazione IRCCS Istituto Nazionale dei Tumori, Tumor Genomics Unit, Department of Experimental Oncology and Molecular Medicine, Milan (Italy)

    2016-11-15

    To compare the performance metrics of two different strategies of lung cancer screening by low-dose computed tomography (LDCT), namely, annual (LDCT1) or biennial (LDCT2) screen. Recall rate, detection rate, interval cancers, sensitivity, specificity, positive and negative predictive values (PPV and NPV, respectively) were compared between LDCT1 and LDCT2 arms of the MILD trial over the first seven (T0-T6; median follow-up 7.3 years) and four rounds (T0-T3; median follow-up 7.3 years), respectively. 1152 LDCT1 and 1151 LDCT2 participants underwent a total of 6893 and 4715 LDCT scans, respectively. The overall recall rate was higher in LDCT2 arm (6.97 %) than in LDCT1 arm (5.81 %) (p = 0.01), which was counterbalanced by the overall lower number of LDCT scans. No difference was observed for the overall detection rate (0.56 % in both arms). The two LDCT arms had similar specificity (99.2 % in both arms), sensitivity (73.5 %, in LDCT2 vs. 68.5 % in LDCT1, p = 0.62), PPV (42.4 %, in LDCT2, vs. 40.6 %, in LDCT1, p = 0.83) and NPV (99.8 %, in LDCT2 vs. 99.7 %, in LDCT1, p = 0.71). Biennial screen may save about one third of LDCT scans with similar performance indicators as compared to annual screening. (orig.)

  6. The impact of iterative reconstruction in low-dose computed tomography on the evaluation of diffuse interstitial lung disease

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyun Ju; Chung, Myung Jin; Shin, Kyung Eun; Hwang, Hye Sun; Lee, Kyung Soo [Dept. of Radiology nd Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2016-11-15

    To evaluate the impact of iterative reconstruction (IR) on the assessment of diffuse interstitial lung disease (DILD) using CT. An American College of Radiology (ACR) phantom (module 4 to assess spatial resolution) was scanned with 10-100 effective mAs at 120 kVp. The images were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), with blending ratios of 0%, 30%, 70% and 100%, and model-based iterative reconstruction (MBIR), and their spatial resolution was objectively assessed by the line pair structure method. The patient study was based on retrospective interpretation of prospectively acquired data, and it was approved by the institutional review board. Chest CT scans of 23 patients (mean age 64 years) were performed at 120 kVp using 1) standard dose protocol applying 142-275 mA with dose modulation (high-resolution computed tomography [HRCT]) and 2) low-dose protocol applying 20 mA (low dose CT, LDCT). HRCT images were reconstructed with FBP, and LDCT images were reconstructed using FBP, ASIR, and MBIR. Matching images were randomized and independently reviewed by chest radiologists. Subjective assessment of disease presence and radiological diagnosis was made on a 10-point scale. In addition, semi-quantitative results were compared for the extent of abnormalities estimated to the nearest 5% of parenchymal involvement. In the phantom study, ASIR was comparable to FBP in terms of spatial resolution. However, for MBIR, the spatial resolution was greatly decreased under 10 mA. In the patient study, the detection of the presence of disease was not significantly different. The values for area under the curve for detection of DILD by HRCT, FBP, ASIR, and MBIR were as follows: 0.978, 0.979, 0.972, and 0.963. LDCT images reconstructed with FBP, ASIR, and MBIR tended to underestimate reticular or honeycombing opacities (-2.8%, -4.1%, and -5.3%, respectively) and overestimate ground glass opacities (+4.6%, +8.9%, and

  7. Extremity x-ray

    Science.gov (United States)

    ... degenerative) Bone tumor Broken bone (fracture) Dislocated bone Osteomyelitis (infection) Arthritis Other conditions for which the test ... Bone tumor Bone x-ray Broken bone Clubfoot Osteomyelitis X-ray Review Date 7/3/2016 Updated ...

  8. Abdominal x-ray

    Science.gov (United States)

    ... are, or may be, pregnant. Alternative Names Abdominal film; X-ray - abdomen; Flat plate; KUB x-ray ... Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also ...

  9. Effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low dose CT colonography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Sun [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of); Kim, Se Hyung, E-mail: shkim7071@gmail.com [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of); Im, Jong Pil; Kim, Sang Gyun [Department of Internal Medicine, Seoul National University Hospital (Korea, Republic of); Shin, Cheong-il; Han, Joon Koo; Choi, Byung Ihn [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of)

    2015-04-15

    Highlights: •We assessed the effect of reconstruction algorithms on CAD in ultra-low dose CTC. •30 patients underwent ultra-low dose CTC using 120 and 100 kVp with 10 mAs. •CT was reconstructed with FBP, ASiR and Veo and then, we applied a CAD system. •Per-polyp sensitivity of CAD in ULD CT can be improved with the IR algorithms. •Despite of an increase in the number of FPs with IR, it was still acceptable. -- Abstract: Purpose: To assess the effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low-dose CT colonography (ULD CTC). Materials and methods: IRB approval and informed consents were obtained. Thirty prospectively enrolled patients underwent non-contrast CTC at 120 kVp/10 mAs in supine and 100 kVp/10 mAs in prone positions, followed by same-day colonoscopy. Images were reconstructed with filtered back projection (FBP), 80% adaptive statistical iterative reconstruction (ASIR80), and model-based iterative reconstruction (MBIR). A commercial CAD system was applied and per-polyp sensitivities and numbers of false-positives (FPs) were compared among algorithms. Results: Mean effective radiation dose of CTC was 1.02 mSv. Of 101 polyps detected and removed by colonoscopy, 61 polyps were detected on supine and on prone CTC datasets on consensus unblinded review, resulting in 122 visible polyps (32 polyps <6 mm, 52 6–9.9 mm, and 38 ≥ 10 mm). Per-polyp sensitivity of CAD for all polyps was highest with MBIR (56/122, 45.9%), followed by ASIR80 (54/122, 44.3%) and FBP (43/122, 35.2%), with significant differences between FBP and IR algorithms (P < 0.017). Per-polyp sensitivity for polyps ≥ 10 mm was also higher with MBIR (25/38, 65.8%) and ASIR80 (24/38, 63.2%) than with FBP (20/38, 58.8%), albeit without statistical significance (P > 0.017). Mean number of FPs was significantly different among algorithms (FBP, 1.4; ASIR, 2.1; MBIR, 2.4) (P = 0.011). Conclusion: Although the performance of stand-alone CAD

  10. Low-dose head computed tomography in children: a single institutional experience in pediatric radiation risk reduction: clinical article.

    Science.gov (United States)

    Morton, Ryan P; Reynolds, Renee M; Ramakrishna, Rohan; Levitt, Michael R; Hopper, Richard A; Lee, Amy; Browd, Samuel R

    2013-10-01

    In this study, the authors describe their experience with a low-dose head CT protocol for a preselected neurosurgical population at a dedicated pediatric hospital (Seattle Children's Hospital), the largest number of patients with this protocol reported to date. All low-dose head CT scans between October 2011 and November 2012 were reviewed. Two different low-dose radiation dosages were used, at one-half or one-quarter the dose of a standard head CT scan, based on patient characteristics agreed upon by the neurosurgery and radiology departments. Patient information was also recorded, including diagnosis and indication for CT scan. Six hundred twenty-four low-dose head CT procedures were performed within the 12-month study period. Although indications for the CT scans varied, the most common reason was to evaluate the ventricles and catheter placement in hydrocephalic patients with shunts (70%), followed by postoperative craniosynostosis imaging (12%). These scans provided adequate diagnostic imaging, and no patient required a follow-up full-dose CT scan as a result of poor image quality on a low-dose CT scan. Overall physician comfort and satisfaction with interpretation of the images was high. An additional 2150 full-dose head CT scans were performed during the same 12-month time period, making the total number of CT scans 2774. This value compares to 3730 full-dose head CT scans obtained during the year prior to the study when low-dose CT and rapid-sequence MRI was not a reliable option at Seattle Children's Hospital. Thus, over a 1-year period, 22% of the total CT scans were able to be converted to low-dose scans, and full-dose CT scans were able to be reduced by 42%. The implementation of a low-dose head CT protocol substantially reduced the amount of ionizing radiation exposure in a preselected population of pediatric neurosurgical patients. Image quality and diagnostic utility were not significantly compromised.

  11. Mapping soil deformation around plant roots using in vivo 4D X-ray Computed Tomography and Digital Volume Correlation.

    Science.gov (United States)

    Keyes, S D; Gillard, F; Soper, N; Mavrogordato, M N; Sinclair, I; Roose, T

    2016-06-14

    The mechanical impedance of soils inhibits the growth of plant roots, often being the most significant physical limitation to root system development. Non-invasive imaging techniques have recently been used to investigate the development of root system architecture over time, but the relationship with soil deformation is usually neglected. Correlative mapping approaches parameterised using 2D and 3D image data have recently gained prominence for quantifying physical deformation in composite materials including fibre-reinforced polymers and trabecular bone. Digital Image Correlation (DIC) and Digital Volume Correlation (DVC) are computational techniques which use the inherent material texture of surfaces and volumes, captured using imaging techniques, to map full-field deformation components in samples during physical loading. Here we develop an experimental assay and methodology for four-dimensional, in vivo X-ray Computed Tomography (XCT) and apply a Digital Volume Correlation (DVC) approach to the data to quantify deformation. The method is validated for a field-derived soil under conditions of uniaxial compression, and a calibration study is used to quantify thresholds of displacement and strain measurement. The validated and calibrated approach is then demonstrated for an in vivo test case in which an extending maize root in field-derived soil was imaged hourly using XCT over a growth period of 19h. This allowed full-field soil deformation data and 3D root tip dynamics to be quantified in parallel for the first time. This fusion of methods paves the way for comparative studies of contrasting soils and plant genotypes, improving our understanding of the fundamental mechanical processes which influence root system development.

  12. Phase-contrast X-ray CT

    Energy Technology Data Exchange (ETDEWEB)

    Momose, Atsushi [Hitachi Ltd., Hatoyama, Saitama (Japan). Advanced Research Lab.

    1996-08-01

    X-ray transmission imaging that creates image contrast from the distribution of the X-ray absorption coefficient is not sensitive to materials consisting of light elements such as hydrogen, carbon, nitrogen, and oxygen. On the other hand, the X-ray phase shift caused by the light elements is substantial enough to be detected even when absorption is almost zero. Hence, phase-contrast X-ray imaging is a promising technique for observing the structure inside biological soft tissues without the need for staining and without serious radiation exposure. Using fringe scanning X-ray interferometry, the X-ray phase shift caused by an object was measured. Three-dimensional image reconstruction of cancerous tissues using the measured phase shifts was enabled under tomographic configuration phase-contrast X-ray computed tomography (CT). (author)

  13. X-Ray Supernovae

    CERN Document Server

    Immler, S; Immler, Stefan; Lewin, Walter H.G.

    2002-01-01

    We present a review of X-ray observations of supernovae (SNe). By observing the (~0.1--100 keV) X-ray emission from young SNe, physical key parameters such as the circumstellar matter (CSM) density, mass-loss rate of the progenitor and temperature of the outgoing and reverse shock can be derived as a function of time. Despite intensive search over the last ~25 years, only 15 SNe have been detected in X-rays. We review the individual X-ray observations of these SNe and discuss their implications as to our understanding of the physical processes giving rise to the X-ray emission.

  14. Long-term prognosis of patients with lung cancer detected on low-dose chest computed tomography screening.

    Science.gov (United States)

    Nawa, Takeshi; Nakagawa, Tohru; Mizoue, Tetsuya; Kusano, Suzushi; Chonan, Tatsuya; Fukai, Shimao; Endo, Katsuyuki

    2012-02-01

    The effectiveness of lung cancer screening using low-dose chest computed tomography (CT) remains elusive. The present study examined the prognosis of patients with lung cancer detected on CT screening in Japanese men and women. Subjects were 210 patients with primary lung cancer identified on CT screening at two medical facilities in Hitachi, Japan, where a total of 61,914 CT screenings were performed among 25,385 screenees between 1998 and 2006. Prognostic status of these patients was sought by examining medical records at local hospitals, supplemented by vital status information from local government. The 5-year survival rate was estimated according to the characteristics of patients and lung nodule. A total of 203 (97%) patients underwent surgery. During a 5.7-year mean follow-up period, 19 patients died from lung cancer and 6 died from other causes. The estimated 5-year survival rate for all patients and for those on stage IA was 90% and 97%, respectively. Besides cancer stage, smoking and nodule appearance were independent predictors of a poor survival; multivariable-adjusted hazard ratio (95% confidence interval) was 4.7 (1.3, 16.5) for current and past smokers versus nonsmokers and 4.6 (1.6, 13.9) for solid nodule versus others. Even patients with solid shadow had a 5-year survival of 82% if the lesion was 20mm or less in size. Results suggest that lung cancers detected on CT screening are mostly curative. The impact of CT screening on mortality at community level needs to be clarified by monitoring lung cancer deaths.

  15. Cost-effectiveness of screening for lung cancer with low-dose computed tomography: a systematic literature review.

    Science.gov (United States)

    Puggina, Anna; Broumas, Athanasios; Ricciardi, Walter; Boccia, Stefania

    2016-02-01

    On 31 December 2013, the US Preventive Services Task Force rated low-dose computed tomography (LDCT) for lung cancer screening as level 'B' recommendation. Yet, lung cancer screening implementation remains controversial, particularly when considering its cost-effectiveness. The aim of this work is to investigate the cost-effectiveness of LDCT screening program for lung cancer by performing a systematic literature review. We reviewed the published economic evaluations of LDCT in lung cancer screening. MEDLINE, ISI Web of Science and Cochrane databases were searched for literature retrieval up to 31 March 2015. Inclusion criteria included: studies reporting an original full economic evaluation; reports presenting the outcomes as Quality-Adjusted Life Years (QALYs) gained or as Life Years Gained. Nine economic evaluations met the inclusion criteria. All the cost-effectiveness analyses included high risk populations for lung cancer and compared the use of annual LDCT screening with no screening. Seven studies reported an incremental cost-effectiveness ratio below the threshold of US$ 100 000 per QALY gained. Cost-effectiveness of LDCT screening for lung cancer is an highly debatable issue. Currently available economic evaluations suggest the cost-effectiveness of LDCT for lung cancer screening compared with no screening and indicate that the implementation of LDCT should be considered when planning a national lung cancer screening program. Additional economic evaluations, especially from a societal perspective and in an EU-setting, are needed. © The Author 2015. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

  16. Prospective comparison of conventional radiography, low-dose computed tomography and magnetic resonance imaging in monoclonal gammopathies.

    Science.gov (United States)

    Minarik, Jiri; Krhovska, Petra; Hrbek, Jan; Pika, Tomas; Bacovsky, Jaroslav; Herman, Miroslav; Scudla, Vlastimil

    2016-06-01

    We carried out a prospective study in order to identify the best imaging approach for patients with newly diagnosed multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS). We assessed the extent of myeloma bone disease (MBD) in 112 individuals - 84 patients with MM and 28 individuals with MGUS. For the detection of osteolytic involvement we used whole-body magnetic resonance imaging (WB-MRI), low-dose computed tomography (LD-CT) and conventional radiography (CR). Each method assessed the presence of osteolytic involvement, compressive fractures and extramedullary involvement in the following regions: skull, spine and chest, pelvis and humerus and femur. We compared the difference in the number and extent of osteolytic involvement, especially the findings in CR negative patients. Conventional radiography showed no superiority in any of the evaluated regions, and failed in the detection of extramedullary massess and spine involvement. WB-MRI was best at imaging the spine including extramedullary involvement, however, detection of osteolytic lesions of the skull was limited in comparison with both CR and LD-CT. Both WB-MRI and LD-CT were comparable in imaging of lesions of pelvis, humerus, femur and the presence of extramedullary masses. LD-CT showed superiority in detection of skull lesions but lower sensitivity in spine compared to WB-MRI. Our results confirm that relying solely on CR in the diagnostics of MM is insufficient. We suggest that the most suitable method for primary assessment of osteolytic involvement in monoclonal gammopathies should include either whole-body MRI together with CR of the skull or, with an equivalent sensitivity, whole body LD-CT.

  17. X-ray computed tomography uncovers root-root interactions: quantifying spatial relationships between interacting root systems in three dimensions

    Directory of Open Access Journals (Sweden)

    Alexander Martin Paya

    2015-04-01

    Full Text Available Research in the field of plant biology has recently demonstrated that inter- and intra-specific interactions belowground can dramatically alter root growth. Our aim was to answer questions related to the effect of inter- vs. intra-specific interactions on the growth and utilization of undisturbed space by fine roots within three dimensions (3D using micro X-ray computed tomography. To achieve this, Populus tremuloides (quaking aspen and Picea mariana (black spruce seedlings were planted into containers as either solitary individuals, or inter-/intra-specific pairs, allowed to grow for two months, and 3D metrics developed in order to quantify their use of belowground space. In both aspen and spruce, inter-specific root interactions produced a shift in the vertical distribution of the root system volume, and deepened the average position of root tips when compared to intra-specifically growing seedlings. Inter-specific interactions also increased the minimum distance between root tips belonging to the same root system. There was no effect of belowground interactions on the radial distribution of roots, or the directionality of lateral root growth for either species. In conclusion, we found that significant differences were observed more often when comparing controls (solitary individuals and paired seedlings (inter- or intra-specific, than when comparing inter- and intra-specifically growing seedlings. This would indicate that competition between neighboring seedlings was more responsible for shifting fine root growth in both species than was neighbor identity. However, significant inter- vs. intra-specific differences were observed, which further emphasizes the importance of biological interactions in competition studies.

  18. Use of Computed X-ray Tomographic Data for Analyzing the Thermodynamics of a Dissociating Porous Sand/Hydrate Mixture

    Science.gov (United States)

    Freifeld, Barry M.; Kneafsey, Timothy J.; Tomutsa, Liviu; Stern, Laura A.; Kirby, Stephen H.

    2002-02-28

    X-ray computed tomography (CT) is a method that has been used extensively in laboratory experiments for measuring rock properties and fluid transport behavior. More recently, CT scanning has been applied successfully to detect the presence and study the behavior of naturally occurring hydrates. In this study, we used a modified medical CT scanner to image and analyze the progression of a dissociation front in a synthetic methane hydrate/sand mixture. The sample was initially scanned under conditions at which the hydrate is stable (atmospheric pressure and liquid nitrogen temperature, 77 K). The end of the sample holder was then exposed to the ambient air, and the core was continuously scanned as dissociation occurred in response to the rising temperature. CT imaging captured the advancing dissociation front clearly and accurately. The evolved gas volume was monitored as a function of time. Measured by CT, the advancing hydrate dissociation front was modeled as a thermal conduction problem explicitly incorporating the enthalpy of dissociation, using the Stefan moving-boundary-value approach. The assumptions needed to perform the analysis consisted of temperatures at the model boundaries. The estimated value for thermal conductivity of 2.6 W/m K for the remaining water ice/sand mixture is higher than expected based on conduction alone; this high value may represent a lumped parameter that incorporates the processes of heat conduction, methane gas convection, and any kinetic effects that occur during dissociation. The technique presented here has broad implications for future laboratory and field testing that incorporates geophysical techniques to monitor gas hydrate dissociation.

  19. Bilateral filtering using the full noise covariance matrix applied to x-ray phase-contrast computed tomography

    Science.gov (United States)

    Allner, S.; Koehler, T.; Fehringer, A.; Birnbacher, L.; Willner, M.; Pfeiffer, F.; Noël, P. B.

    2016-05-01

    The purpose of this work is to develop an image-based de-noising algorithm that exploits complementary information and noise statistics from multi-modal images, as they emerge in x-ray tomography techniques, for instance grating-based phase-contrast CT and spectral CT. Among the noise reduction methods, image-based de-noising is one popular approach and the so-called bilateral filter is a well known algorithm for edge-preserving filtering. We developed a generalization of the bilateral filter for the case where the imaging system provides two or more perfectly aligned images. The proposed generalization is statistically motivated and takes the full second order noise statistics of these images into account. In particular, it includes a noise correlation between the images and spatial noise correlation within the same image. The novel generalized three-dimensional bilateral filter is applied to the attenuation and phase images created with filtered backprojection reconstructions from grating-based phase-contrast tomography. In comparison to established bilateral filters, we obtain improved noise reduction and at the same time a better preservation of edges in the images on the examples of a simulated soft-tissue phantom, a human cerebellum and a human artery sample. The applied full noise covariance is determined via cross-correlation of the image noise. The filter results yield an improved feature recovery based on enhanced noise suppression and edge preservation as shown here on the example of attenuation and phase images captured with grating-based phase-contrast computed tomography. This is supported by quantitative image analysis. Without being bound to phase-contrast imaging, this generalized filter is applicable to any kind of noise-afflicted image data with or without noise correlation. Therefore, it can be utilized in various imaging applications and fields.

  20. Bayesian 3D X-ray computed tomography image reconstruction with a scaled Gaussian mixture prior model

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Li; Gac, Nicolas; Mohammad-Djafari, Ali [Laboratoire des Signaux et Systèmes 3, Rue Joliot-Curie 91192 Gif sur Yvette (France)

    2015-01-13

    In order to improve quality of 3D X-ray tomography reconstruction for Non Destructive Testing (NDT), we investigate in this paper hierarchical Bayesian methods. In NDT, useful prior information on the volume like the limited number of materials or the presence of homogeneous area can be included in the iterative reconstruction algorithms. In hierarchical Bayesian methods, not only the volume is estimated thanks to the prior model of the volume but also the hyper parameters of this prior. This additional complexity in the reconstruction methods when applied to large volumes (from 512{sup 3} to 8192{sup 3} voxels) results in an increasing computational cost. To reduce it, the hierarchical Bayesian methods investigated in this paper lead to an algorithm acceleration by Variational Bayesian Approximation (VBA) [1] and hardware acceleration thanks to projection and back-projection operators paralleled on many core processors like GPU [2]. In this paper, we will consider a Student-t prior on the gradient of the image implemented in a hierarchical way [3, 4, 1]. Operators H (forward or projection) and H{sup t} (adjoint or back-projection) implanted in multi-GPU [2] have been used in this study. Different methods will be evalued on synthetic volume 'Shepp and Logan' in terms of quality and time of reconstruction. We used several simple regularizations of order 1 and order 2. Other prior models also exists [5]. Sometimes for a discrete image, we can do the segmentation and reconstruction at the same time, then the reconstruction can be done with less projections.

  1. [Quantitative structure characteristics and fractal dimension of Chinese medicine granules measured by synchrotron radiation X-ray computed micro tomography].

    Science.gov (United States)

    Lu, Xiao-long; Zheng, Qin; Yin, Xian-zhen; Xiao, Guang-qing; Liao, Zu-hua; Yang, Ming; Zhang, Ji-wen

    2015-06-01

    The shape and structure of granules are controlled by the granulation process, which is one of the main factors to determine the nature of the solid dosage forms. In this article, three kinds of granules of a traditional Chinese medicine for improving appetite and promoting digestion, namely, Jianwei Granules, were prepared using granulation technologies as pendular granulation, high speed stirring granulation, and fluidized bed granulation and the powder properties of them were investigated. Meanwhile, synchrotron radiation X-ray computed micro tomography (SR-µCT) was applied to quantitatively determine the irregular internal structures of the granules. The three-dimensional (3D) structure models were obtained by 3D reconstruction, which were more accurately to characterize the three-dimensional structures of the particles through the quantitative data. The models were also used to quantitatively compare the structural differences of granules prepared by different granulation processes with the same formula, so as to characterize how the production process plays a role in the pharmaceutical behaviors of the granules. To focus on the irregularity of the particle structure, the box counting method was used to calculate the fractal dimensions of the granules. The results showed that the fractal dimension is more sensitive to reflect the minor differences in the structure features than the conventional parameters, and capable to specifically distinct granules in structure. It is proved that the fractal dimension could quantitatively characterize the structural information of irregular granules. It is the first time suggested by our research that the fractal dimension difference (Df,c) between two fractal dimension parameters, namely, the volume matrix fractal dimension and the surface matrix fractal dimension, is a new index to characterize granules with irregular structures and evaluate the effects of production processes on the structures of granules as a new

  2. Three-dimensional printing of X-ray computed tomography datasets with multiple materials using open-source data processing.

    Science.gov (United States)

    Sander, Ian M; McGoldrick, Matthew T; Helms, My N; Betts, Aislinn; van Avermaete, Anthony; Owers, Elizabeth; Doney, Evan; Liepert, Taimi; Niebur, Glen; Liepert, Douglas; Leevy, W Matthew

    2017-07-01

    Advances in three-dimensional (3D) printing allow for digital files to be turned into a "printed" physical product. For example, complex anatomical models derived from clinical or pre-clinical X-ray computed tomography (CT) data of patients or research specimens can be constructed using various printable materials. Although 3D printing has the potential to advance learning, many academic programs have been slow to adopt its use in the classroom despite increased availability of the equipment and digital databases already established for educational use. Herein, a protocol is reported for the production of enlarged bone core and accurate representation of human sinus passages in a 3D printed format using entirely consumer-grade printers and a combination of free-software platforms. The comparative resolutions of three surface rendering programs were also determined using the sinuses, a human body, and a human wrist data files to compare the abilities of different software available for surface map generation of biomedical data. Data shows that 3D Slicer provided highest compatibility and surface resolution for anatomical 3D printing. Generated surface maps were then 3D printed via fused deposition modeling (FDM printing). In conclusion, a methodological approach that explains the production of anatomical models using entirely consumer-grade, fused deposition modeling machines, and a combination of free software platforms is presented in this report. The methods outlined will facilitate the incorporation of 3D printed anatomical models in the classroom. Anat Sci Educ 10: 383-391. © 2017 American Association of Anatomists. © 2017 American Association of Anatomists.

  3. Phase segmentation of X-ray computer tomography rock images using machine learning techniques: an accuracy and performance study

    Science.gov (United States)

    Chauhan, Swarup; Rühaak, Wolfram; Anbergen, Hauke; Kabdenov, Alen; Freise, Marcus; Wille, Thorsten; Sass, Ingo

    2016-07-01

    Performance and accuracy of machine learning techniques to segment rock grains, matrix and pore voxels from a 3-D volume of X-ray tomographic (XCT) grayscale rock images was evaluated. The segmentation and classification capability of unsupervised (k-means, fuzzy c-means, self-organized maps), supervised (artificial neural networks, least-squares support vector machines) and ensemble classifiers (bragging and boosting) were tested using XCT images of andesite volcanic rock, Berea sandstone, Rotliegend sandstone and a synthetic sample. The averaged porosity obtained for andesite (15.8 ± 2.5 %), Berea sandstone (16.3 ± 2.6 %), Rotliegend sandstone (13.4 ± 7.4 %) and the synthetic sample (48.3 ± 13.3 %) is in very good agreement with the respective laboratory measurement data and varies by a factor of 0.2. The k-means algorithm is the fastest of all machine learning algorithms, whereas a least-squares support vector machine is the most computationally expensive. Metrics entropy, purity, mean square root error, receiver operational characteristic curve and 10 K-fold cross-validation were used to determine the accuracy of unsupervised, supervised and ensemble classifier techniques. In general, the accuracy was found to be largely affected by the feature vector selection scheme. As it is always a trade-off between performance and accuracy, it is difficult to isolate one particular machine learning algorithm which is best suited for the complex phase segmentation problem. Therefore, our investigation provides parameters that can help in selecting the appropriate machine learning techniques for phase segmentation.

  4. Internal Morphologies of Cycled Li-Metal Electrodes Investigated by Nano-Scale Resolution X-ray Computed Tomography.

    Science.gov (United States)

    Frisco, Sarah; Liu, Danny X; Kumar, Arjun; Whitacre, Jay F; Love, Corey T; Swider-Lyons, Karen E; Litster, Shawn

    2017-06-07

    While some commercially available primary batteries have lithium metal anodes, there has yet to be a commercially viable secondary battery with this type of electrode. Research prototypes of these cells typically exhibit a limited cycle life before dendrites form and cause internal cell shorting, an occurrence that is more pronounced during high-rate cycling. To better understand the effects of high-rate cycling that can lead to cell failure, we use ex situ nanoscale-resolution X-ray computed tomography (nano-CT) with the aid of Zernike phase contrast to image the internal morphologies of lithium metal electrodes on copper wire current collectors that have been cycled at low and high current densities. The Li that is deposited on a Cu wire and then stripped and deposited at low current density appears uniform in morphology. Those cycled at high current density undergo short voltage transients to >3 V during Li-stripping from the electrode, during which electrolyte oxidation and Cu dissolution from the current collector may occur. The effect of temperature is also explored with separate cycling experiments performed at 5 and 33 °C. The resulting morphologies are nonuniform films filled with voids that are semispherical in shape with diameters ranging from hundreds of nanometers to tens of micrometers, where the void size distributions are temperature-dependent. Low-temperature cycling elicits a high proportion of submicrometer voids, while the higher-temperature sample morphology is dominated by voids larger than 2 μm. In evaluating these morphologies, we consider the importance of nonidealities during extreme charging, such as electrolyte decomposition. We conclude that nano-CT is an effective tool for resolving features and aggressive cycling-induced anomalies in Li films in the range of 100 nm to 100 μm.

  5. An analytical method for optimizing imaging parameters in industrial x-ray computed tomography for dimensional measurements on multimaterial workpieces

    Science.gov (United States)

    Buratti, A.; Ferrucci, M.; Ben Achour, S.; Dewulf, W.; Schmitt, R. H.

    2016-10-01

    Industrial Computed Tomography (CT) has recently gained a prominent role in the field of dimensional metrology as a powerful 3D coordinate measurement technique. Its main advantage is the ability of measuring both inner and outer features of geometrically complex workpieces without altering or damaging them. The settings with which CT data are acquired can contribute to the uncertainty of measurements; these settings are chosen by the users in an intuitive way, resulting in high variability of the measurement outcome. There is currently no available holistic model that can (1) describe the relationship between CT setup parameters and measurement uncertainty, or (2) determine the optimal parameters for a given measurement task. In this study, we propose an analytical method to optimize imaging parameters for multimaterial measurements. The proposed method takes as input information about the nominal workpiece geometry and material composition. For a given workpiece position and orientation, the optimal photon energy is calculated to maximize edge detectability and minimize image noise. Subsequently, tube voltage and prefilter are chosen to ensure that the generated X-ray spectrum is quasi-monochromatic around the optimal photon energy. Focal spot size is chosen to minimize resolution, while also avoiding blurring. Then, the corresponding tube power is evaluated as well as the tube current. Finally, integration time is minimized so that the gray values of air are still in the linear range of the detector. The presented method was implemented into a software application and validated through simulation of CT scans of multimaterial workpieces. Measurements with predicted parameters were found to be more accurate than those performed with parameters chosen by expert users.

  6. Bilateral filtering using the full noise covariance matrix applied to x-ray phase-contrast computed tomography.

    Science.gov (United States)

    Allner, S; Koehler, T; Fehringer, A; Birnbacher, L; Willner, M; Pfeiffer, F; Noël, P B

    2016-05-21

    The purpose of this work is to develop an image-based de-noising algorithm that exploits complementary information and noise statistics from multi-modal images, as they emerge in x-ray tomography techniques, for instance grating-based phase-contrast CT and spectral CT. Among the noise reduction methods, image-based de-noising is one popular approach and the so-called bilateral filter is a well known algorithm for edge-preserving filtering. We developed a generalization of the bilateral filter for the case where the imaging system provides two or more perfectly aligned images. The proposed generalization is statistically motivated and takes the full second order noise statistics of these images into account. In particular, it includes a noise correlation between the images and spatial noise correlation within the same image. The novel generalized three-dimensional bilateral filter is applied to the attenuation and phase images created with filtered backprojection reconstructions from grating-based phase-contrast tomography. In comparison to established bilateral filters, we obtain improved noise reduction and at the same time a better preservation of edges in the images on the examples of a simulated soft-tissue phantom, a human cerebellum and a human artery sample. The applied full noise covariance is determined via cross-correlation of the image noise. The filter results yield an improved feature recovery based on enhanced noise suppression and edge preservation as shown here on the example of attenuation and phase images captured with grating-based phase-contrast computed tomography. This is supported by quantitative image analysis. Without being bound to phase-contrast imaging, this generalized filter is applicable to any kind of noise-afflicted image data with or without noise correlation. Therefore, it can be utilized in various imaging applications and fields.

  7. On-line multi-slice computed tomography interactive overlay with conventional X-ray: a new and advanced imaging fusion concept.

    Science.gov (United States)

    Garcia, Joel A; Bhakta, Shyam; Kay, Joseph; Chan, Kak-Chen; Wink, Onno; Ruijters, Danny; Carroll, John D

    2009-04-17

    Computed tomography (CT) has revolutionized noninvasive cardiovascular evaluations. Complicated percutaneous procedures require precise imaging guidance that conventional X-ray is often unable to provide. By combining X-ray imaging with real-time, interactive, CT-based landmarks, interventional procedures could be facilitated. We describe two cases using the first CT/Live X-ray overlay in which this technology shows its potential. A 31-year-old male with an anatomically complicated atrial septal defect (ASD) was referred for percutaneous closure. Transesophageal echocardiography (TEE) revealed an inferior location of the ASD complicated by it's proximity to a prominent Eustachian ridge. The CT was used to create a patient-specific physical model in preparation for the procedure and an in-lab real-time CT overlay allowing successful closure. A second case of a 41-year-old male with coronary artery disease status-post coronary artery bypass, aortic valve replacement (AVR), and aortic root replacement with an abnormal coronary computed tomography angiogram (CTA). In a prior procedure years ago the saphenous vein graft (SVG) to the left anterior descending artery (LAD) could not be cannulated during invasive angiography, given the patient's complicated and unusual anatomy. Using CT overlay, the superiorly and anteriorly located SVG was cannulated successfully. CT/Live X-ray overlay provided an adequate anatomical intra-procedural ASD evaluation, defect sizing, and guidance in one case and localization of an anatomically challenging graft ostium in the other case. Adding the CT landmarks as an overlay to traditional X-ray techniques provides a revolutionary and advanced imaging fusion concept that should improve procedural success.

  8. Primary diagnosis of multiple pheochromocytomas in the brother of a MEN-2 patient by simultaneous MIBG scintigraphy and low-dose computed tomography

    DEFF Research Database (Denmark)

    Kjaer, Andreas; Petersen, Claus Leth

    2002-01-01

    Metaiodobenzylguanidine (MIBG) scintigraphy is a well-established functional imaging method for localizing pheochromocytomas. However, the morphologic information revealed on the scintigram is often too sparse and thus, accordingly, supplemental computed tomography (CT) or magnetic resonance...... imaging are often performed. Recently, gamma cameras with built-in low-dose CT were introduced. The authors describe a patient with a high likelihood of pheochromocytoma who had simultaneous MIBG scintigraphy and low-dose CT performed as the primary examinations. The scan revealed pheochromocytomas...... in both adrenal glands and one extra-adrenal pheochromocytoma located in the liver. The combined imaging ensured the final diagnosis without any need for further imaging. Based on the findings of this case, the authors believe that combined MIBG scintigraphy and low-dose CT is a promising future single...

  9. X-Ray Micro-Computed Tomography of Apollo Samples as a Curation Technique Enabling Better Research

    Science.gov (United States)

    Ziegler, R. A.; Almeida, N. V.; Sykes, D.; Smith, C. L.

    2014-01-01

    X-ray micro-computed tomography (micro-CT) is a technique that has been used to research meteorites for some time and many others], and recently it is becoming a more common tool for the curation of meteorites and Apollo samples. Micro-CT is ideally suited to the characterization of astromaterials in the curation process as it can provide textural and compositional information at a small spatial resolution rapidly, nondestructively, and without compromising the cleanliness of the samples (e.g., samples can be scanned sealed in Teflon bags). This data can then inform scientists and curators when making and processing future sample requests for meteorites and Apollo samples. Here we present some preliminary results on micro-CT scans of four Apollo regolith breccias. Methods: Portions of four Apollo samples were used in this study: 14321, 15205, 15405, and 60639. All samples were 8-10 cm in their longest dimension and approximately equant. These samples were micro-CT scanned on the Nikon HMXST 225 System at the Natural History Museum in London. Scans were made at 205-220 kV, 135-160 microamps beam current, with an effective voxel size of 21-44 microns. Results: Initial examination of the data identify a variety of mineral clasts (including sub-voxel FeNi metal grains) and lithic clasts within the regolith breccias. Textural information within some of the lithic clasts was also discernable. Of particular interest was a large basalt clast (approx.1.3 cc) found within sample 60639, which appears to have a sub-ophitic texture. Additionally, internal void space, e.g., fractures and voids, is readily identifiable. Discussion: It is clear from the preliminary data that micro-CT analyses are able to identify important "new" clasts within the Apollo breccias, and better characterize previously described clasts or igneous samples. For example, the 60639 basalt clast was previously believed to be quite small based on its approx.0.5 sq cm exposure on the surface of the main mass

  10. Quantifying vertical stress transmission and compaction-induced soil structure using sensor mat and X-ray computed tomography

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Schjønning, Per; Keller, Thomas

    2016-01-01

    distributions, and (ii) a tactile sensor mat was employed for measuring stresses at the interface of the topsoil and subsoil columns. The resulting soil pore structure under applied stresses was quantified using X-ray CT and by air-permeability measurements. In topsoil discrete stress transmission patterns were...

  11. [Computation of the cross-sectional area of the cable in the power circuit of the X-ray machine].

    Science.gov (United States)

    Meng, Xin-min; Feng, Da-yu

    2007-01-01

    The source impedance of the power circuit in the x-ray machine is analyzed in the paper and based on the voltage drop generated by the impedance, the cross-sectional area of the cable is calculated. In the end, the cross-sectional areas of the cables, corresponding to their respective distances between the transformers and the switchboards are given.

  12. Comparison of diagnostic value of multidetector computed tomography and X-ray in the detection of body packing

    Energy Technology Data Exchange (ETDEWEB)

    Bulakci, Mesut, E-mail: mesutbulakci@yahoo.com [Department of Radiology, Haseki Training and Research Hospital, 34096 Aksaray, Istanbul (Turkey); Kalelioglu, Tuba, E-mail: tubakarsakarya@hotmail.com [Department of Radiology, Haseki Training and Research Hospital, 34096 Aksaray, Istanbul (Turkey); Bulakci, Betul Bozkurt, E-mail: dr.betulbozkurt@gmail.com [Department of Family Medicine, Istanbul University, Istanbul Faculty of Medicine, 34390 Capa, Istanbul (Turkey); Kiris, Adem, E-mail: ademkiris@hotmail.com [Department of Radiology, Haseki Training and Research Hospital, 34096 Aksaray, Istanbul (Turkey)

    2013-08-15

    Objective: Radiologists and other clinicians are facing an increasing number of illegal drug-related medical conditions. We aimed to draw attention to this growing global problem and to highlight some of the important points related to diagnosis and follow-up of body packing. We compare the diagnostic performance of unenhanced multidetector CT (MDCT) and abdomen X-ray for the detection of drug-filled packets. Materials and methods: Sixty-seven suspects, who underwent both CT and X-ray examinations, have been included in the study. All MDCT and X-ray images were independently and retrospectively reviewed by two observers with different degrees of experience in abdomen imaging. Fifty-two of them were identified as body packers finally. Interobserver agreement, sensitivity, specificity, positive and negative predictive value were calculated. Results: Two types of packets with different characteristics were identified in all body packers. Type 1 packets (solid-state drug) were found in 41 patients and type 2 packets (liquid cocaine) in 11 patients. All statistical analyses concern the detection of any packets. That is, the whole evaluation has been performed per patient. Sensitivity/specificity values of type 1 and type 2 packets for MDCT were 100–98%/100–100% and 100–100%/100–100%, respectively. Besides, sensitivity/specificity values of type 1 and type 2 packets for X-ray were 93–90%/100–91% and 64–45%/73–71%, respectively. In addition, interobserver agreements for detection of any packets were excellent (κ = 0.96) and good (κ = 0.75) for interpretation of MDCT and X-ray, respectively. Conclusion: Unenhanced MDCT is a fast, accurate and easily used diagnostic tool with high sensitivity and specificity for the exact diagnosis of body packing.

  13. Multiple-pressure-tapped core holder combined with X-ray computed tomography scanning for gas-water permeability measurements of methane-hydrate-bearing sediments

    Science.gov (United States)

    Konno, Yoshihiro; Jin, Yusuke; Uchiumi, Takashi; Nagao, Jiro

    2013-06-01

    We present a novel setup for measuring the effective gas-water permeability of methane-hydrate-bearing sediments. We developed a core holder with multiple pressure taps for measuring the pressure gradient of the gas and water phases. The gas-water flooding process was simultaneously detected using an X-ray computed tomography scanner. We successfully measured the effective gas-water permeability of an artificial sandy core with methane hydrate during the gas-water flooding test.

  14. X-Ray Polarimetry

    CERN Document Server

    Kaaret, Philip

    2014-01-01

    We review the basic principles of X-ray polarimetry and current detector technologies based on the photoelectric effect, Bragg reflection, and Compton scattering. Recent technological advances in high-spatial-resolution gas-filled X-ray detectors have enabled efficient polarimeters exploiting the photoelectric effect that hold great scientific promise for X-ray polarimetry in the 2-10 keV band. Advances in the fabrication of multilayer optics have made feasible the construction of broad-band soft X-ray polarimeters based on Bragg reflection. Developments in scintillator and solid-state hard X-ray detectors facilitate construction of both modular, large area Compton scattering polarimeters and compact devices suitable for use with focusing X-ray telescopes.

  15. Imaging characteristics of intraocular foreign bodies: a comparative study of plain film X-ray, computed tomography, ultrasound, and magnetic resonance imaging.

    Science.gov (United States)

    Modjtahedi, Bobeck S; Rong, Andrew; Bobinski, Mathew; McGahan, John; Morse, Lawrence S

    2015-01-01

    To determine the imaging features of common intraocular foreign bodies (IOFBs) and the ability to differentiate types of IOFBs. Four-mm IOFBs were inserted via through pars plana approach into cadaveric lamb eyes. Six metallic (aluminum, brass, copper, silver, steel, and lead) and seven nonmetallic (plastic [CF6 spectacle plastic and polyvinyl chloride pipe], glass [bottle glass and windshield glass], wood [dry and wet poplar], and stone [slate]) IOFBs were imaged using plain film x-ray, computed tomography scan, ultrasound, and magnetic resonance imaging (T1, T2, and gradient echo sequences). Plain film x-ray had limited ability to differentiate most IOFBs. Computed tomography findings can be divided into low attenuation objects (wood), moderate attenuation (CF6 spectacle plastic), high attenuation without surrounding artifact (polyvinyl chloride, slate, bottle glass, windshield glass, and aluminum), high attenuation with shadow artifact and minimal edge streak artifact (steel, brass, copper), and high attenuation with significant shadow artifact and prominent streak artifact (silver and lead). Density (in Hounsfield units) aided in differentiating the types of IOFBs. Gradient echo sequences on magnetic resonance imaging also held utility. Ultrasound images had considerable overlap in appearances. Imaging techniques can significantly aid in determining the IOFBs type, with computed tomography serving as the best initial modality. X-ray holds limited utility while ultrasound and magnetic resonance imaging are best reserved as adjunctive tests.

  16. Low-Dose Chest Computed Tomography for Lung Cancer Screening Among Hodgkin Lymphoma Survivors: A Cost-Effectiveness Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wattson, Daniel A., E-mail: dwattson@partners.org [Harvard Radiation Oncology Program, Boston, Massachusetts (United States); Hunink, M.G. Myriam [Departments of Radiology and Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands and Center for Health Decision Science, Harvard School of Public Health, Boston, Massachusetts (United States); DiPiro, Pamela J. [Department of Imaging, Dana-Farber Cancer Institute, Boston, Massachusetts (United States); Das, Prajnan [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Hodgson, David C. [Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Mauch, Peter M.; Ng, Andrea K. [Department of Radiation Oncology, Brigham and Women' s Hospital and Dana-Farber Cancer Institute, Boston, Massachusetts (United States)

    2014-10-01

    Purpose: Hodgkin lymphoma (HL) survivors face an increased risk of treatment-related lung cancer. Screening with low-dose computed tomography (LDCT) may allow detection of early stage, resectable cancers. We developed a Markov decision-analytic and cost-effectiveness model to estimate the merits of annual LDCT screening among HL survivors. Methods and Materials: Population databases and HL-specific literature informed key model parameters, including lung cancer rates and stage distribution, cause-specific survival estimates, and utilities. Relative risks accounted for radiation therapy (RT) technique, smoking status (>10 pack-years or current smokers vs not), age at HL diagnosis, time from HL treatment, and excess radiation from LDCTs. LDCT assumptions, including expected stage-shift, false-positive rates, and likely additional workup were derived from the National Lung Screening Trial and preliminary results from an internal phase 2 protocol that performed annual LDCTs in 53 HL survivors. We assumed a 3% discount rate and a willingness-to-pay (WTP) threshold of $50,000 per quality-adjusted life year (QALY). Results: Annual LDCT screening was cost effective for all smokers. A male smoker treated with mantle RT at age 25 achieved maximum QALYs by initiating screening 12 years post-HL, with a life expectancy benefit of 2.1 months and an incremental cost of $34,841/QALY. Among nonsmokers, annual screening produced a QALY benefit in some cases, but the incremental cost was not below the WTP threshold for any patient subsets. As age at HL diagnosis increased, earlier initiation of screening improved outcomes. Sensitivity analyses revealed that the model was most sensitive to the lung cancer incidence and mortality rates and expected stage-shift from screening. Conclusions: HL survivors are an important high-risk population that may benefit from screening, especially those treated in the past with large radiation fields including mantle or involved-field RT. Screening

  17. Lung nodule detection performance in five observers on computed tomography (CT) with adaptive iterative dose reduction using three-dimensional processing (AIDR 3D) in a Japanese multicenter study: Comparison between ultra-low-dose CT and low-dose CT by receiver-operating characteristic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nagatani, Yukihiro, E-mail: yatsushi@belle.shiga-med.ac.jp [Department of Radiology, Shiga University of Medical Science, Otsu 520-2192, Shiga (Japan); Takahashi, Masashi; Murata, Kiyoshi [Department of Radiology, Shiga University of Medical Science, Otsu 520-2192, Shiga (Japan); Ikeda, Mitsuru [Department of Radiological and Medical Laboratory Science, Nagoya University Graduate School of Medicine, Nagoya 461-8673, Aichi (Japan); Yamashiro, Tsuneo [Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara 903-0215, Okinawa (Japan); Miyara, Tetsuhiro [Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara 903-0215, Okinawa (Japan); Department of Radiology, Okinawa Prefectural Yaeyama Hospital, Ishigaki 907-0022, Okinawa (Japan); Koyama, Hisanobu [Department of Radiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Hyogo (Japan); Koyama, Mitsuhiro [Department of Radiology, Osaka Medical College, Takatsuki 569-8686, Osaka (Japan); Sato, Yukihisa [Department of Radiology, Osaka University Graduate School of Medicine, Suita 565-0871, Osaka (Japan); Department of Radiology, Osaka Medical Center of Cancer and Cardiovascular Diseases, Osaka 537-8511, Osaka (Japan); Moriya, Hiroshi [Department of Radiology, Ohara General Hospital, Fukushima 960-8611 (Japan); Noma, Satoshi [Department of Radiology, Tenri Hospital, Tenri 632-8552, Nara (Japan); Tomiyama, Noriyuki [Department of Radiology, Osaka University Graduate School of Medicine, Suita 565-0871, Osaka (Japan); Ohno, Yoshiharu [Department of Radiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Hyogo (Japan); Murayama, Sadayuki [Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara 903-0215, Okinawa (Japan)

    2015-07-15

    Highlights: • Using AIDR 3D, ULDCT showed comparable LND of solid nodules to LDCT. • Using AIDR 3D, LND of smaller GGN in ULDCT was inferior to that in LDCT. • Effective dose in ULDCT was about only twice of that in chest X-ray. • BMI values in study population were mostly in the normal range body habitus. - Abstract: Purpose: To compare lung nodule detection performance (LNDP) in computed tomography (CT) with adaptive iterative dose reduction using three dimensional processing (AIDR3D) between ultra-low dose CT (ULDCT) and low dose CT (LDCT). Materials and methods: This was part of the Area-detector Computed Tomography for the Investigation of Thoracic Diseases (ACTIve) Study, a multicenter research project being conducted in Japan. Institutional Review Board approved this study and informed consent was obtained. Eighty-three subjects (body mass index, 23.3 ± 3.2) underwent chest CT at 6 institutions using identical scanners and protocols. In a single visit, each subject was scanned using different tube currents: 240, 120 and 20 mA (3.52, 1.74 and 0.29 mSv, respectively). Axial CT images with 2-mm thickness/increment were reconstructed using AIDR3D. Standard of reference (SOR) was determined based on CT images at 240 mA by consensus reading of 2 board-certificated radiologists as to the presence of lung nodules with the longest diameter (LD) of more than 3 mm. Another 5 radiologists independently assessed and recorded presence/absence of lung nodules and their locations by continuously-distributed rating in CT images at 20 mA (ULDCT) and 120 mA (LDCT). Receiver-operating characteristic (ROC) analysis was used to evaluate LNDP of both methods in total and also in subgroups classified by LD (>4, 6 and 8 mm) and nodular characteristics (solid and ground glass nodules). Results: For SOR, 161 solid and 60 ground glass nodules were identified. No significant difference in LNDP for entire solid nodules was demonstrated between both methods, as area under ROC

  18. Hyperpolarized (3)He magnetic resonance imaging: comparison with four-dimensional x-ray computed tomography imaging in lung cancer.

    Science.gov (United States)

    Mathew, Lindsay; Wheatley, Andrew; Castillo, Richard; Castillo, Edward; Rodrigues, George; Guerrero, Thomas; Parraga, Grace

    2012-12-01

    Pulmonary functional imaging using four-dimensional x-ray computed tomographic (4DCT) imaging and hyperpolarized (3)He magnetic resonance imaging (MRI) provides regional lung function estimates in patients with lung cancer in whom pulmonary function measurements are typically dominated by tumor burden. The aim of this study was to evaluate the quantitative spatial relationship between 4DCT and hyperpolarized (3)He MRI ventilation maps. Eleven patients with lung cancer provided written informed consent to 4DCT imaging and MRI performed within 11 ± 14 days. Hyperpolarized (3)He MRI was acquired in breath-hold after inhalation from functional residual capacity of 1 L hyperpolarized (3)He, whereas 4DCT imaging was acquired over a single tidal breath of room air. For hyperpolarized (3)He MRI, the percentage ventilated volume was generated using semiautomated segmentation; for 4DCT imaging, pulmonary function maps were generated using the correspondence between identical tissue elements at inspiratory and expiratory phases to generate percentage ventilated volume. After accounting for differences in image acquisition lung volumes ((3)He MRI: 1.9 ± 0.5 L ipsilateral, 2.3 ± 0.7 L contralateral; 4DCT imaging: 1.2 ± 0.3 L ipsilateral, 1.3 ± 0.4 L contralateral), there was no significant difference in percentage ventilated volume between hyperpolarized (3)He MRI (72 ± 11% ipsilateral, 79 ± 12% contralateral) and 4DCT imaging (74 ± 3% ipsilateral, 75 ± 4% contralateral). Spatial correspondence between 4DCT and (3)He MRI ventilation was evaluated using the Dice similarity coefficient index (ipsilateral, 86 ± 12%; contralateral, 88 ± 12%). Despite rather large differences in image acquisition breathing maneuvers, good spatial and significant quantitative agreement was observed for ventilation maps on hyperpolarized (3)He MRI and 4DCT imaging, suggesting that pulmonary regions with good lung function are similar between modalities in this small group of patients with

  19. Influence of pore size distributions on decomposition of maize leaf residue: evidence from X-ray computed micro-tomography

    Science.gov (United States)

    Negassa, Wakene; Guber, Andrey; Kravchenko, Alexandra; Rivers, Mark

    2014-05-01

    Soil's potential to sequester carbon (C) depends not only on quality and quantity of organic inputs to soil but also on the residence time of the applied organic inputs within the soil. Soil pore structure is one of the main factors that influence residence time of soil organic matter by controlling gas exchange, soil moisture and microbial activities, thereby soil C sequestration capacity. Previous attempts to investigate the fate of organic inputs added to soil did not allow examining their decomposition in situ; the drawback that can now be remediated by application of X-ray computed micro-tomography (µ-CT). The non-destructive and non-invasive nature of µ-CT gives an opportunity to investigate the effect of soil pore size distributions on decomposition of plant residues at a new quantitative level. The objective of this study is to examine the influence of pore size distributions on the decomposition of plant residue added to soil. Samples with contrasting pore size distributions were created using aggregate fractions of five different sizes (soil samples. Dried pieces of maize leaves 2.5 mg in size (equivalent to 1.71 mg C g-1 soil) were added to half of the studied samples. Samples with and without maize leaves were incubated for 120 days. CO2 emission from the samples was measured at regular time intervals. In order to ensure that the observed differences are due to differences in pore structure and not due to differences in inherent properties of the studied aggregate fractions, we repeated the whole experiment using soil from the same aggregate size fractions but ground to soil size fractions of intact aggregates, and 40-50% in ground samples, respectively. The results of the incubation experiment demonstrated that, while greater C mineralization was observed in samples of all size fractions amended with leaf, the effect of leaf presence was most pronounced in the smaller aggregate fractions (0.05-0.1 mm and 0.05 mm) of intact aggregates. The results of

  20. Edible oil structures at low and intermediate concentrations. I. Modeling, computer simulation, and predictions for X ray scattering

    Science.gov (United States)

    Pink, David A.; Quinn, Bonnie; Peyronel, Fernanda; Marangoni, Alejandro G.

    2013-12-01

    found that TAGwoods aggregated via DLCA into clusters with fractal dimension D =1.7-1.8. As the simulations were run further, TAGwoods relaxed their positions in order to maximize the attractive interaction making the process look like reaction limited cluster-cluster aggregation with the fractal dimension increasing to D =2.0-2.1. For higher concentrations of CNPs, many TAGwood clusters were formed and, because of their weak interactions, were distributed randomly with D =3.0. We summarize the hierarchy of structures and make predictions for X-ray scattering.

  1. Comparison of x ray computed tomography number to proton relative linear stopping power conversion functions using a standard phantom

    Energy Technology Data Exchange (ETDEWEB)

    Moyers, M. F., E-mail: MFMoyers@roadrunner.com [Shanghai Proton and Heavy Ion Center, Shanghai, China 201321 (China)

    2014-06-15

    Purpose: Adequate evaluation of the results from multi-institutional trials involving light ion beam treatments requires consideration of the planning margins applied to both targets and organs at risk. A major uncertainty that affects the size of these margins is the conversion of x ray computed tomography numbers (XCTNs) to relative linear stopping powers (RLSPs). Various facilities engaged in multi-institutional clinical trials involving proton beams have been applying significantly different margins in their patient planning. This study was performed to determine the variance in the conversion functions used at proton facilities in the U.S.A. wishing to participate in National Cancer Institute sponsored clinical trials. Methods: A simplified method of determining the conversion function was developed using a standard phantom containing only water and aluminum. The new method was based on the premise that all scanners have their XCTNs for air and water calibrated daily to constant values but that the XCTNs for high density/high atomic number materials are variable with different scanning conditions. The standard phantom was taken to 10 different proton facilities and scanned with the local protocols resulting in 14 derived conversion functions which were compared to the conversion functions used at the local facilities. Results: For tissues within ±300 XCTN of water, all facility functions produced converted RLSP values within ±6% of the values produced by the standard function and within 8% of the values from any other facility's function. For XCTNs corresponding to lung tissue, converted RLSP values differed by as great as ±8% from the standard and up to 16% from the values of other facilities. For XCTNs corresponding to low-density immobilization foam, the maximum to minimum values differed by as much as 40%. Conclusions: The new method greatly simplifies determination of the conversion function, reduces ambiguity, and in the future could promote

  2. Comparison of x ray computed tomography number to proton relative linear stopping power conversion functions using a standard phantom.

    Science.gov (United States)

    Moyers, M F

    2014-06-01

    Adequate evaluation of the results from multi-institutional trials involving light ion beam treatments requires consideration of the planning margins applied to both targets and organs at risk. A major uncertainty that affects the size of these margins is the conversion of x ray computed tomography numbers (XCTNs) to relative linear stopping powers (RLSPs). Various facilities engaged in multi-institutional clinical trials involving proton beams have been applying significantly different margins in their patient planning. This study was performed to determine the variance in the conversion functions used at proton facilities in the U.S.A. wishing to participate in National Cancer Institute sponsored clinical trials. A simplified method of determining the conversion function was developed using a standard phantom containing only water and aluminum. The new method was based on the premise that all scanners have their XCTNs for air and water calibrated daily to constant values but that the XCTNs for high density/high atomic number materials are variable with different scanning conditions. The standard phantom was taken to 10 different proton facilities and scanned with the local protocols resulting in 14 derived conversion functions which were compared to the conversion functions used at the local facilities. For tissues within ±300 XCTN of water, all facility functions produced converted RLSP values within ±6% of the values produced by the standard function and within 8% of the values from any other facility's function. For XCTNs corresponding to lung tissue, converted RLSP values differed by as great as ±8% from the standard and up to 16% from the values of other facilities. For XCTNs corresponding to low-density immobilization foam, the maximum to minimum values differed by as much as 40%. The new method greatly simplifies determination of the conversion function, reduces ambiguity, and in the future could promote standardization between facilities. Although it

  3. Individual fibre segmentation from 3D X-ray computed tomography for characterising the fibre orientation in unidirectional composite materials

    DEFF Research Database (Denmark)

    Emerson, Monica Jane; Jespersen, Kristine Munk; Dahl, Anders Bjorholm

    2017-01-01

    The aim of this paper is to characterise the fibre orientation in unidirectional fibre reinforced polymers, namely glass and carbon fibre composites. The compression strength of the composite is related to the orientation of the fibres. Thus the orientation is essential when designing materials...... for wind turbine blades. The calculation of the fibre orientation distribution is based on segmenting the individual fibres from volumes that have been acquired through X-ray tomography. The segmentation method presented in this study can accurately extract individual fibres from low contrast X-ray scans...... of composites with high fibre volume fraction. From the individual fibre orientations, it is possible to obtain results which are independent of the scanning quality. The compression strength for both composites is estimated from the average fibre orientations and is found to be of the same order of magnitude...

  4. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography*

    Science.gov (United States)

    Paixão, Lucas; Oliveira, Bruno Beraldo; Viloria, Carolina; de Oliveira, Marcio Alves; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

    2015-01-01

    Objective Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography. PMID:26811553

  5. Orbital breathing effects in the computation of x-ray d-ion spectra in solids by ab initio wave-function-based methods

    Science.gov (United States)

    Bogdanov, Nikolay A.; Bisogni, Valentina; Kraus, Roberto; Monney, Claude; Zhou, Kejin; Schmitt, Thorsten; Geck, Jochen; Mitrushchenkov, Alexander O.; Stoll, Hermann; van den Brink, Jeroen; Hozoi, Liviu

    2017-01-01

    In existing theoretical approaches to core-level excitations of transition-metal ions in solids relaxation and polarization effects due to the inner core hole are often ignored or described phenomenologically. Here we set up an ab initio computational scheme that explicitly accounts for such physics in the calculation of x-ray absorption and resonant inelastic x-ray scattering spectra. Good agreement is found with experimental transition-metal L-edge data for the strongly correlated d 9 cuprate Li2CuO2, for which we determine the absolute scattering intensities. The newly developed methodology opens the way for the investigation of even more complex d n electronic structures of group VI B to VIII B correlated oxide compounds.

  6. Shieldings for X-ray radiotherapy facilities calculated by computer; Blindagens para instalacoes de radioterapia por raios-X calculada por computador

    Energy Technology Data Exchange (ETDEWEB)

    Pedrosa, Paulo S.; Farias, Marcos S. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Gavazza, Sergio [Universidade Gama Filho (UGF), Rio de Janeiro, RJ (Brazil)

    2005-07-01

    This work presents a methodology for calculation of X-ray shielding in facilities of radiotherapy with help of computer. Even today, in Brazil, the calculation of shielding for X-ray radiotherapy is done based on NCRP-49 recommendation establishing a methodology for calculating required to the elaboration of a project of shielding. With regard to high energies, where is necessary the construction of a labyrinth, the NCRP-49 is not very clear, so that in this field, studies were made resulting in an article that proposes a solution to the problem. It was developed a friendly program in Delphi programming language that, through the manual data entry of a basic design of architecture and some parameters, interprets the geometry and calculates the shields of the walls, ceiling and floor of on X-ray radiation therapy facility. As the final product, this program provides a graphical screen on the computer with all the input data and the calculation of shieldings and the calculation memory. The program can be applied in practical implementation of shielding projects for radiotherapy facilities and can be used in a didactic way compared to NCRP-49.

  7. Calculation of shielding of X rays in radiotherapy facilities with computer aid; Calculo de blindagem para instalacoes de radioterapia por raios X com auxilio de computador

    Energy Technology Data Exchange (ETDEWEB)

    Pedrosa, Paulo Sergio; Farias, Marcos Santana [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)]. E-mail: pedrosa@ien.gov.br; msantana@ien.gov.br; Gavazza, Sergio [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Dept. das Ciencias Fundamentais, Radiacao e Meio Ambiente]. E-mail: gavazza@ugf.br

    2005-07-01

    This work presents a methodology for calculation of shielding of X rays in radiotherapy facilities with computer aid. A friendly program, called RadTeraX, was developed in programming language Delphi that, through manual data input of a basic project of architecture and of some parameters, interprets the geometry and calculates the shielding of the walls, ground and roof of a radiotherapy installation for X rays. As a final product, this program supplies a graphic screen in the computer with all the input data and the calculation of the shielding, besides the respective calculation memory. Still today, in Brazil, the calculation of the shielding for radiotherapy facilities with X rays has been made based on recommendations of NCRP-49, that establishes a necessary calculation methodology to the elaboration of a shielding project. However, in high energies, where it is necessary the construction of a maze, NCRP-49 is insufficient, so that in this field, studies were made originating an article that proposes a solution for the problem and this solution was implemented in the program. The program can be applied in the practical execution of shielding projects for radiotherapy facilities and in didactic way in comparison with NCRP-49 and has been registered under number 00059420 at INPI - Instituto Nacional da Propriedade Industrial (National Institute of Industrial Property). (author)

  8. Note: A disposable x-ray camera based on mass produced complementary metal-oxide-semiconductor sensors and single-board computers

    Energy Technology Data Exchange (ETDEWEB)

    Hoidn, Oliver R.; Seidler, Gerald T., E-mail: seidler@uw.edu [Physics Department, University of Washington, Seattle, Washington 98195 (United States)

    2015-08-15

    We have integrated mass-produced commercial complementary metal-oxide-semiconductor (CMOS) image sensors and off-the-shelf single-board computers into an x-ray camera platform optimized for acquisition of x-ray spectra and radiographs at energies of 2–6 keV. The CMOS sensor and single-board computer are complemented by custom mounting and interface hardware that can be easily acquired from rapid prototyping services. For single-pixel detection events, i.e., events where the deposited energy from one photon is substantially localized in a single pixel, we establish ∼20% quantum efficiency at 2.6 keV with ∼190 eV resolution and a 100 kHz maximum detection rate. The detector platform’s useful intrinsic energy resolution, 5-μm pixel size, ease of use, and obvious potential for parallelization make it a promising candidate for many applications at synchrotron facilities, in laser-heating plasma physics studies, and in laboratory-based x-ray spectrometry.

  9. Computation of the off-axis effective area of the New Hard X-ray Mission modules by means of an analytical approach

    CERN Document Server

    Spiga, D

    2015-01-01

    One of the most important parameters determining the sensitivity of X-ray telescopes is their effective area as a function of the X-ray energy. The computation of the effective area of a Wolter-I mirror, with either a single layer or multilayer coating, is a very simple task for a source on-axis at astronomical distance. Indeed, when the source moves off-axis the calculation is more complicated, in particular for new hard X-ray imaging telescopes (NuSTAR, ASTRO-H, NHXM, IXO) beyond 10 keV, that will make use of multilayer coatings to extend the reflectivity band in grazing incidence. Unlike traditional single-layer coatings (in Ir or Au), graded multilayer coatings exhibit an oscillating reflectivity as a function of the incidence angle, which makes the effective area not immediately predictable for a source placed off-axis within the field of view. For this reason, the computation of the off-axis effective area has been so far demanded to ray- tracing codes, able to sample the incidence of photons onto the m...

  10. Computational Modeling of Laboratory X-ray Emission due to Low-Energy Collisions of H-like and He-like ions with H2

    Science.gov (United States)

    Miller, Ansley; Mullen, Patrick Dean; Cumbee, Renata; Stancil, Phillip C.; Leutenegger, Maurice A.

    2016-06-01

    Charge exchange between highly-charged ions and neutral molecules occurs when the solar wind, or other astrophysical plasmas, collide with cool gas. This process emits observable X-rays with specific line intensities. Recent CX experiments at Lawrence Livermore National Laboratory measured the X-ray hardness ratios of low-energy collisions between hydrogen- and helium-like ions with H2 (Leutenegger et al. 2010). Using our recently developed X-ray modeling package, Kronos_v2 (Mullen et al. 2016), which utilizes multi-channel Landau-Zener charge exchange cross sections, we have computed theoretical hydrogen-like hardness ratios to aid in interpretation of the experimental data. While the computed hardness ratios are somewhat smaller than the experiment, it shows better agreement than earlier classical trajectory predictions. We are also in the process of building Kronos_v3; further enhancing the comprehensive charge exchange database to include helium-like and multielectron ions to allow for comparison with experiments and for models of hot astrophysical environments such as supernova remnants, star-forming galaxies, and galaxy clusters.Leutenegger, M. et al. 2010, Phys. Rev. Lett., 105, 063201Mullen, P. D. et al., 2016, ApJS, in press

  11. Palladium(II) complex with thiazole containing tridentate ONN donor ligand: Synthesis, X-ray structure and DFT computation

    Science.gov (United States)

    Biswas, Sujan; Pramanik, Ajoy Kumar; Mondal, Tapan Kumar

    2015-05-01

    New palladium(II) complex with 2-(2-thiazolyl)-4-methylphenol (TAC) having general formula [Pd(TAC)Cl) (1) has been synthesized and characterized. The complex has been characterized by various spectroscopic techniques. Single crystal X-ray structure shows distorted square planar geometry around palladium(II). Cyclic voltammetric studies shows ligand based irreversible oxidation and reduction peaks. The electronic structure, redox properties and electronic excitations in the complex are interpreted by DFT and TDDFT calculations.

  12. Method to study sample object size limit of small-angle x-ray scattering computed tomography

    Science.gov (United States)

    Choi, Mina; Ghammraoui, Bahaa; Badal, Andreu; Badano, Aldo

    2016-03-01

    Small-angle x-ray scattering (SAXS) imaging is an emerging medical tool that can be used for in vivo detailed tissue characterization and has the potential to provide added contrast to conventional x-ray projection and CT imaging. We used a publicly available MC-GPU code to simulate x-ray trajectories in a SAXS-CT geometry for a target material embedded in a water background material with varying sample sizes (1, 3, 5, and 10 mm). Our target materials were water solution of gold nanoparticle (GNP) spheres with a radius of 6 nm and a water solution with dissolved serum albumin (BSA) proteins due to their well-characterized scatter profiles at small angles and highly scattering properties. The background material was water. Our objective is to study how the reconstructed scatter profile degrades at larger target imaging depths and increasing sample sizes. We have found that scatter profiles of the GNP in water can still be reconstructed at depths up to 5 mm embedded at the center of a 10 mm sample. Scatter profiles of BSA in water were also reconstructed at depths up to 5 mm in a 10 mm sample but with noticeable signal degradation as compared to the GNP sample. This work presents a method to study the sample size limits for future SAXS-CT imaging systems.

  13. Application of the Debye formula to the computation of x-ray diffraction patterns of nanostructured diffusion couples

    Science.gov (United States)

    Cheung, Charles; Kelly, Brian; Unruh, Karl; Decamp, Matthew

    Time resolved optical pump/x-ray probe techniques have made it possible to acquire x-ray diffraction patterns corresponding to very early diffusion times in nanostructured diffusion couples. The analysis of these diffraction patterns, however, is complicated by significant line broadening and other finite size effects that appear in samples containing a relatively small number of scatterers. In order to better quantify these issues, x-ray diffraction patterns have been calculated by the direct application of the Debye formula to core/shell and thin film diffusion couples. In particular a series of diffraction patterns have been calculated as a function of the sample size and composition profile determined from the appropriate solutions to Fick's second law. The results of these calculations have been used to guide the interpretation of the measured diffraction patterns of Pt/Ni core/shell nanoparticles and Pt/Ni thin film multilayers. This material is based upon work supported by the National Science Foundation under Grant No. 1410076.

  14. Structural and Computational Study of 4 New Solvatomorphs of Betulin: A Combined X-Ray, Hirshfeld Surface, and Thermal Analysis.

    Science.gov (United States)

    Yang, Dezhi; Gong, Ningbo; Zhang, Li; Lu, Yang; Du, Guanhua

    2017-03-01

    Four new solvatomorphs of betulin were reported and characterized by X-ray diffractometry as well as thermal and vibrational spectroscopic analyses. Single-crystal X-ray diffraction was used to analyze the X-ray structures of the compounds and confirmed the stoichiometric ratio between the host and guest molecules from thermal data. Results indicated that solvatomorphism occurred in several betulin solvates. Changes in intermolecular arrangements, stoichiometry, and hydrogen-bonding interactions of solvatomorphs were due to solvent incorporation to solvates. Hirshfeld surface analyses, especially dnorm surface and fingerprint plots, were used to determine intermolecular interactions in the crystal network. Solvent molecules played an important role in the construction of a 3D architecture. The stabilities of these solvates were evaluated by thermal analyses. Nonisothermal kinetic analysis was used to explain the kinetics of solid-solid phase transition (desolvation) of betulin solvates. The apparent activation energies were evaluated using Kissinger and Ozawa methods. Moreover, phase transitions were visually investigated by hot-stage microscopic analysis. Copyright © 2017. Published by Elsevier Inc.

  15. Phase-contrast X-ray CT

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-01

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

  16. X-Ray

    Science.gov (United States)

    ... You may be allowed to remain with your child during the test. If you remain in the room during the X-ray exposure, you'll likely be asked to wear a lead apron to shield you from unnecessary exposure. After the X-ray ...

  17. Dental x-rays

    Science.gov (United States)

    ... X-rays are a form of high energy electromagnetic radiation. The x-rays penetrate the body to form ... for detecting cavities, unless the decay is very advanced and deep. Many ... The amount of radiation given off during the procedure is less than ...

  18. X-Ray Surveys

    CERN Document Server

    Giommi, P; Perri, M

    1998-01-01

    A review of recent developments in the field of X-ray surveys, especially in the hard (2-10 and 5-10 keV) bands, is given. A new detailed comparison between the measurements in the hard band and extrapolations from ROSAT counts, that takes into proper account the observed distribution of spectral slopes, is presented. Direct comparisons between deep ROSAT and BeppoSAX images show that most hard X-ray sources are also detected at soft X-ray energies. This may indicate that heavily cutoff sources, that should not be detectable in the ROSAT band but are expected in large numbers from unified AGN schemes, are in fact detected because of the emerging of either non-nuclear components, or of reflected, or partially transmitted nuclear X-rays. These soft components may complic