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Sample records for dynamic computed tomography

  1. Arterioportal shunts on dynamic computed tomography

    SciTech Connect

    Nakayama, T.; Hiyama, Y.; Ohnishi, K.; Tsuchiya, S.; Kohno, K.; Nakajima, Y.; Okuda, K.

    1983-05-01

    Thirty-two patients, 20 with hepatocelluar carcinoma and 12 with liver cirrhosis, were examined by dynamic computed tomography (CT) using intravenous bolus injection of contrast medium and by celiac angiography. Dynamic CT disclosed arterioportal shunting in four cases of hepatocellular carcinoma and in one of cirrhosis. In three of the former, the arterioportal shunt was adjacent to a mass lesion on CT, suggesting tumor invasion into the portal branch. In one with hepatocellular carcinoma, the shunt was remote from the mass. In the case with cirrhosis, there was no mass. In these last two cases, the shunt might have been caused by prior percutaneous needle puncture. In another case of hepatocellular carcinoma, celiac angiography but not CT demonstrated an arterioportal shunt. Thus, dynamic CT was diagnostic in five of six cases of arteriographically demonstrated arterioportal shunts.

  2. Static and dynamic assessment of myocardial perfusion by computed tomography.

    PubMed

    Danad, Ibrahim; Szymonifka, Jackie; Schulman-Marcus, Joshua; Min, James K

    2016-08-01

    Recent developments in computed tomography (CT) technology have fulfilled the prerequisites for the clinical application of myocardial CT perfusion (CTP) imaging. The evaluation of myocardial perfusion by CT can be achieved by static or dynamic scan acquisitions. Although both approaches have proved clinically feasible, substantial barriers need to be overcome before its routine clinical application. The current review provides an outline of the current status of CTP imaging and also focuses on disparities between static and dynamic CTPs for the evaluation of myocardial blood flow. PMID:27013250

  3. Computed Tomography

    NASA Astrophysics Data System (ADS)

    Castellano, Isabel; Geleijns, Jacob

    After its clinical introduction in 1973, computed tomography developed from an x-ray modality for axial imaging in neuroradiology into a versatile three dimensional imaging modality for a wide range of applications in for example oncology, vascular radiology, cardiology, traumatology and even in interventional radiology. Computed tomography is applied for diagnosis, follow-up studies and screening of healthy subpopulations with specific risk factors. This chapter provides a general introduction in computed tomography, covering a short history of computed tomography, technology, image quality, dosimetry, room shielding, quality control and quality criteria.

  4. Dynamic ventilation imaging from four-dimensional computed tomography

    NASA Astrophysics Data System (ADS)

    Guerrero, Thomas; Sanders, Kevin; Castillo, Edward; Zhang, Yin; Bidaut, Luc; Pan, Tinsu; Komaki, Ritsuko

    2006-02-01

    A novel method for dynamic ventilation imaging of the full respiratory cycle from four-dimensional computed tomography (4D CT) acquired without added contrast is presented. Three cases with 4D CT images obtained with respiratory gated acquisition for radiotherapy treatment planning were selected. Each of the 4D CT data sets was acquired during resting tidal breathing. A deformable image registration algorithm mapped each (voxel) corresponding tissue element across the 4D CT data set. From local average CT values, the change in fraction of air per voxel (i.e. local ventilation) was calculated. A 4D ventilation image set was calculated using pairs formed with the maximum expiration image volume, first the exhalation then the inhalation phases representing a complete breath cycle. A preliminary validation using manually determined lung volumes was performed. The calculated total ventilation was compared to the change in contoured lung volumes between the CT pairs (measured volume). A linear regression resulted in a slope of 1.01 and a correlation coefficient of 0.984 for the ventilation images. The spatial distribution of ventilation was found to be case specific and a 30% difference in mass-specific ventilation between the lower and upper lung halves was found. These images may be useful in radiotherapy planning.

  5. Quantifying thumb opposition kinematics using dynamic computed tomography.

    PubMed

    Kerkhof, F D; Brugman, E; D'Agostino, P; Dourthe, B; van Lenthe, G H; Stockmans, F; Jonkers, I; Vereecke, E E

    2016-06-14

    Current motion capture techniques all have shortcomings when applied to the 3D quantitative evaluation of thumb base motion. Dynamic CT might overcome these shortcomings but, so far, robustness of this technique in more than one specimen has not yet been demonstrated. The aim of the current study is to further evaluate the use of dynamic CT for quantification of thumb motion in a larger cadaveric study using a protocol which is feasible in a clinical context. A dynamic CT scan was acquired from six cadaveric human forearms, while a motion simulator imposed thumb opposition. After image acquisition and segmentation, carpal bone motion was quantified using helical axes. To enable comparisons between specimens, intersection points of the instantaneous helical axis with an anatomically defined plane were determined. Precision of the dynamic CT method, measured as variation in distances between silicon nitride beads between frames of a dynamic scan, was 0.43mm (+/-0.09mm) when fixed to the skin and 0.13mm (+/-0.04mm) when embedded into the bone. Absolute deviation between known and measured distances were not larger than 0.34mm. We could demonstrate and quantify that thumb opposition is associated with motion at the trapeziometacarpal and scaphotrapezotrapezoidal joints. High consistency in motion patterns between specimen were found, while the radiation dose was limited. We conclude that dynamic CT can be used to visualize and quantify 3D thumb kinematics, making it a promising method to explore kinematics in vivo. PMID:27198890

  6. Computed Tomography (CT) - Spine

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Spine Computed tomography (CT) of the spine is a diagnostic imaging ... Spine? What is CT Scanning of the Spine? Computed tomography, more commonly known as a CT or CAT ...

  7. Computational fluid dynamics modelling of perfusion measurements in dynamic contrast-enhanced computed tomography: development, validation and clinical applications

    NASA Astrophysics Data System (ADS)

    Peladeau-Pigeon, M.; Coolens, C.

    2013-09-01

    Dynamic contrast-enhanced computed tomography (DCE-CT) is an imaging tool that aids in evaluating functional characteristics of tissue at different stages of disease management: diagnostic, radiation treatment planning, treatment effectiveness, and monitoring. Clinical validation of DCE-derived perfusion parameters remains an outstanding problem to address prior to perfusion imaging becoming a widespread standard as a non-invasive quantitative measurement tool. One approach to this validation process has been the development of quality assurance phantoms in order to facilitate controlled perfusion ex vivo. However, most of these systems fail to establish and accurately replicate physiologically relevant capillary permeability and exchange performance. The current work presents the first step in the development of a prospective suite of physics-based perfusion simulations based on coupled fluid flow and particle transport phenomena with the goal of enhancing the understanding of clinical contrast agent kinetics. Existing knowledge about a controllable, two-compartmental fluid exchange phantom was used to validate the computational fluid dynamics (CFD) simulation model presented herein. The sensitivity of CFD-derived contrast uptake curves to contrast injection parameters, including injection duration and flow rate, were quantified and found to be within 10% accuracy. The CFD model was employed to evaluate two commonly used clinical kinetic algorithms used to derive perfusion parameters: Fick's principle and the modified Tofts model. Neither kinetic model was able to capture the true transport phenomena it aimed to represent but if the overall contrast concentration after injection remained identical, then successive DCE-CT evaluations could be compared and could indeed reflect differences in regional tissue flow. This study sets the groundwork for future explorations in phantom development and pharmaco-kinetic modelling, as well as the development of novel contrast

  8. Comparison Between Perfusion Computed Tomography and Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Rectal Cancer

    SciTech Connect

    Kierkels, Roel G.J.; Backes, Walter H.; Janssen, Marco H.M.; Buijsen, Jeroen; Beets-Tan, Regina G.H.; Lambin, Philippe; Lammering, Guido; Oellers, Michel C.; Aerts, Hugo J.W.L.

    2010-06-01

    Purpose: To compare pretreatment scans with perfusion computed tomography (pCT) vs. dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in rectal tumors. Methods and Materials: Nineteen patients diagnosed with rectal cancer were included in this prospective study. All patients underwent both pCT and DCE-MRI. Imaging was performed on a dedicated 40-slice CT-positron emission tomography system and a 3-T MRI system. Dynamic contrast enhancement was measured in tumor tissue and the external iliac artery. Tumor perfusion was quantified in terms of pharmacokinetic parameters: transfer constant K{sup trans}, fractional extravascular-extracellular space v{sub e}, and fractional plasma volume v{sub p}. Pharmacokinetic parameter values and their heterogeneity (by 80% quantile value) were compared between pCT and DCE-MRI. Results: Tumor K{sup trans} values correlated significantly for the voxel-by-voxel-derived median (Kendall's tau correlation, tau = 0.81, p < 0.001) and 80% quantile (tau = 0.54, p = 0.04), as well as for the averaged uptake (tau = 0.58, p = 0.03). However, no significant correlations were found for v{sub e} and v{sub p} derived from the voxel-by-voxel-derived median and 80% quantile and derived from the averaged uptake curves. Conclusions: This study demonstrated for the first time that pCT provides K{sup trans} values comparable to those of DCE-MRI. However, no correlation was found for the v{sub e} and v{sub p} parameters between CT and MRI. Computed tomography can serve as an alternative modality to MRI for the in vivo evaluation of tumor angiogenesis in terms of the transfer constant K{sup trans}.

  9. Knowledge-Based Dynamic Volumetric Cardiac Computed Tomography With Saddle Curve Trajectory

    PubMed Central

    Bharkhada, Deepak; Yu, Hengyong; Wang, Ge

    2010-01-01

    Motion artifact is still a major issue in cardiac computed tomography because the current motion correction and electrocardiogram gating techniques have not fully addressed this problem. The image quality can be significantly improved by using information about the actual state of the heart and an exact reconstruction algorithm. We propose to extend a cardiac computed tomographic technique, using the knowledge of the volume and the relation between the state and the phase of the heart, to a saddle curve trajectory. This will optimize the image quality by reducing the artifacts resulting from approximate reconstruction and solve the long-object problem. Necessary background is provided, and the effectiveness of the algorithms is demonstrated in numerical simulations with the dynamic thorax phantom. PMID:19204459

  10. Synchrotron-based dynamic computed tomography of tissue motion for regional lung function measurement

    PubMed Central

    Dubsky, Stephen; Hooper, Stuart B.; Siu, Karen K. W.; Fouras, Andreas

    2012-01-01

    During breathing, lung inflation is a dynamic process involving a balance of mechanical factors, including trans-pulmonary pressure gradients, tissue compliance and airway resistance. Current techniques lack the capacity for dynamic measurement of ventilation in vivo at sufficient spatial and temporal resolution to allow the spatio-temporal patterns of ventilation to be precisely defined. As a result, little is known of the regional dynamics of lung inflation, in either health or disease. Using fast synchrotron-based imaging (up to 60 frames s−1), we have combined dynamic computed tomography (CT) with cross-correlation velocimetry to measure regional time constants and expansion within the mammalian lung in vivo. Additionally, our new technique provides estimation of the airflow distribution throughout the bronchial tree during the ventilation cycle. Measurements of lung expansion and airflow in mice and rabbit pups are shown to agree with independent measures. The ability to measure lung function at a regional level will provide invaluable information for studies into normal and pathological lung dynamics, and may provide new pathways for diagnosis of regional lung diseases. Although proof-of-concept data were acquired on a synchrotron, the methodology developed potentially lends itself to clinical CT scanning and therefore offers translational research opportunities. PMID:22491972

  11. Sinogram smoothing techniques for myocardial blood flow estimation from dose-reduced dynamic computed tomography

    PubMed Central

    Modgil, Dimple; Alessio, Adam M.; Bindschadler, Michael D.; La Rivière, Patrick J.

    2014-01-01

    Abstract. Dynamic contrast-enhanced computed tomography (CT) could provide an accurate and widely available technique for myocardial blood flow (MBF) estimation to aid in the diagnosis and treatment of coronary artery disease. However, one of its primary limitations is the radiation dose imparted to the patient. We are exploring techniques to reduce the patient dose by either reducing the tube current or by reducing the number of temporal frames in the dynamic CT sequence. Both of these dose reduction techniques result in noisy data. In order to extract the MBF information from the noisy acquisitions, we have explored several data-domain smoothing techniques. In this work, we investigate two specific smoothing techniques: the sinogram restoration technique in both the spatial and temporal domains and the use of the Karhunen–Loeve (KL) transform to provide temporal smoothing in the sinogram domain. The KL transform smoothing technique has been previously applied to dynamic image sequences in positron emission tomography. We apply a quantitative two-compartment blood flow model to estimate MBF from the time-attenuation curves and determine which smoothing method provides the most accurate MBF estimates in a series of simulations of different dose levels, dynamic contrast-enhanced cardiac CT acquisitions. As measured by root mean square percentage error (% RMSE) in MBF estimates, sinogram smoothing generally provides the best MBF estimates except for the cases of the lowest simulated dose levels (tube current=25  mAs, 2 or 3 s temporal spacing), where the KL transform method provides the best MBF estimates. The KL transform technique provides improved MBF estimates compared to conventional processing only at very low doses (<7  mSv). Results suggest that the proposed smoothing techniques could provide high fidelity MBF information and allow for substantial radiation dose savings. PMID:25642441

  12. Liver metastasis from hepatoid adenocarcinoma of the stomach mimicking hepatocellular carcinoma: Dynamic computed tomography findings

    PubMed Central

    Lin, Yang-Yu; Chen, Chien-Ming; Huang, Yu-Hsiu; Lin, Cheng-Yu; Chu, Sung-Yu; Hsu, Ming-Yi; Pan, Kuang-Tse; Tseng, Jeng-Hwei

    2015-01-01

    AIM: To evaluate the dynamic computed tomography (CT) findings of liver metastasis from hepatoid adenocarcinoma of the stomach (HAS) and compared them with hepatocellular carcinoma (HCC). METHODS: Between January 2000 and January 2015, 8 patients with pathologically proven HAS and liver metastases were enrolled. Basic tumor status was evaluated for the primary tumor location and metastatic sites. The CT findings of the liver metastases were analyzed for tumor number and size, presence of tumor necrosis, hemorrhage, venous tumor thrombosis, and dynamic enhancing pattern. RESULTS: The body and antrum were the most common site for primary HAS (n = 7), and observed metastatic sites included the liver (n = 8), lymph nodes (n = 7), peritoneum (n = 4), and lung (n = 2). Most of the liver metastases exhibited tumor necrosis regardless of tumor size. By contrast, tumor hemorrhage was observed only in liver lesions larger than 5 cm (n = 4). Three patterns of venous tumor thrombosis were identified: direct venous invasion by the primary HAS (n = 1), direct venous invasion by the liver metastases (n = 7), and isolated portal vein tumor thrombosis (n = 2). Dynamic CT revealed arterial hyperattenuation and late phase washout in all the liver metastases. CONCLUSION: On dynamic CT, liver metastasis from HAS shared many imaging similarities with HCC. For liver nodules, the presence of isolated portal vein tumor thrombosis and a tendency for tumor necrosis are imaging clues that suggest the diagnosis of HAS. PMID:26730164

  13. Usefulness of Preoperative Assessment of Perigastric Vascular Anatomy by Dynamic Computed Tomography for Laparoscopic Gastrectomy

    PubMed Central

    Osaki, Tomohiro; Saito, Hiroaki; Murakami, Yuki; Miyatani, Kozo; Kuroda, Hirohiko; Matsunaga, Tomoyuki; Fukumoto, Youji; Ikeguchi, Masahide

    2015-01-01

    Background Laparoscopic surgery requires a more detailed understanding of local anatomy than does conventional open surgery. The aim of this study was to examine the usefulness of dynamic computed tomography (D-CT) for identification of the location of the left gastric vein (LGV) and existence of the aberrant left hepatic artery (ALHA) compared with conventional enhanced computed tomography (E-CT). Methods Sixty-eight patients underwent laparoscopic-assisted gastrectomy (LAG). E-CT and D-CT were performed in 32 and 36 patients, respectively, and three-dimensional computed tomographic angiography (3D-CTA) was performed in addition to D-CT. The location of the LGV and existence of the ALHA were confirmed during LAG, and these results were compared with those determined preoperatively by CT imaging. Results The location of the LGV as detected by preoperative E-CT and D-CT was consistent with that identified during LAG in 28 (87.5%) and 31 (88.9%) patients, respectively, with no statistical differences. The existence of the ALHA as detected by preoperative E-CT and D-CT was consistent with that identified during gastrectomy in 24 (75%) and 36 (100%) patients, respectively, with a statistical difference (P = 0.005). Furthermore, the type of ALHA could be identified in 10 of 12 patients (83.3%) by D-CT. Conclusion D-CT can produce excellent images of the vascular supply, and thus undoubtedly contributes to the preoperative planning of LAG. Preoperative D-CT might be an informative tool with which to help overcome the disadvantages of LAG. PMID:26740734

  14. Regorafenib Effects on Human Colon Carcinoma Xenografts Monitored by Dynamic Contrast-Enhanced Computed Tomography with Immunohistochemical Validation

    PubMed Central

    Cyran, Clemens C.; Kazmierczak, Philipp M.; Hirner, Heidrun; Moser, Matthias; Ingrisch, Michael; Havla, Lukas; Michels, Alexandra; Eschbach, Ralf; Schwarz, Bettina; Reiser, Maximilian F.; Bruns, Christiane J.; Nikolaou, Konstantin

    2013-01-01

    Objective To investigate dynamic contrast-enhanced computed tomography for monitoring the effects of regorafenib on experimental colon carcinomas in rats by quantitative assessments of tumor microcirculation parameters with immunohistochemical validation. Materials and Methods Colon carcinoma xenografts (HT-29) implanted subcutaneously in female athymic rats (n = 15) were imaged at baseline and after a one-week treatment with regorafenib by dynamic contrast-enhanced computed tomography (128-slice dual-source computed tomography). The therapy group (n = 7) received regorafenib daily (10 mg/kg bodyweight). Quantitative parameters of tumor microcirculation (plasma flow, mL/100 mL/min), endothelial permeability (PS, mL/100 mL/min), and tumor vascularity (plasma volume, %) were calculated using a 2-compartment uptake model. Dynamic contrast-enhanced computed tomography parameters were validated with immunohistochemical assessments of tumor microvascular density (CD-31), tumor cell apoptosis (TUNEL), and proliferation (Ki-67). Results Regorafenib suppressed tumor vascularity (15.7±5.3 to 5.5±3.5%; p<0.05) and tumor perfusion (12.8±2.3 to 8.8±2.9 mL/100 mL/min; p = 0.063). Significantly lower microvascular density was observed in the therapy group (CD-31; 48±10 vs. 113±25, p<0.05). In regorafenib-treated tumors, significantly more apoptotic cells (TUNEL; 11844±2927 vs. 5097±3463, p<0.05) were observed. Dynamic contrast-enhanced computed tomography tumor perfusion and tumor vascularity correlated significantly (p<0.05) with microvascular density (CD-31; r = 0.84 and 0.66) and inversely with apoptosis (TUNEL; r = −0.66 and −0.71). Conclusions Regorafenib significantly suppressed tumor vascularity (plasma volume) quantified by dynamic contrast-enhanced computed tomography in experimental colon carcinomas in rats with good-to-moderate correlations to an immunohistochemical gold standard. Tumor response biomarkers assessed by dynamic contrast

  15. Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography

    NASA Astrophysics Data System (ADS)

    Doebrich, Marcus; Markstaller, Klaus; Karmrodt, Jens; Kauczor, Hans-Ulrich; Eberle, Balthasar; Weiler, Norbert; Thelen, Manfred; Schreiber, Wolfgang G.

    2005-04-01

    In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous distribution of exponentially decaying time constants. The simulations proved the feasibility of the method. The influence of experimental noise could be well evaluated. Analysis of the in vivo data showed that in healthy lungs ventilation processes can be more likely characterized by discrete TCs whereas in ARDS lungs continuous distributions of TCs are observed. The temporal behaviour of lung inflation and deflation can be characterized objectively using the described new methodology. This study indicates that continuous distributions of TCs reflect lung ventilation mechanics more accurately compared to discrete TCs.

  16. Three-dimensional dynamic thermal imaging of structural flaws by dual-band infrared computed tomography

    SciTech Connect

    Del Grande, N.K.; Dolan, K.W.; Durbin, P.F.; Gorvad, M.R.; Kornblum, B.T.; Perkins, D.E.; Schneberk, D.J.; Shapiro, A.B.

    1993-04-01

    We discuss three-dimensional (3D) dynamic thermal imaging of structure flaws using dual-band infrared (DBIR) computed tomography. Conventional thermography provides single-band infrared images which are difficult to interpret. Standard procedures yield imprecise (or qualitative) information about subsurface flaw sites which are typically masked by surface clutter. We use a DBIR imaging unique pioneered at LLNL to capture the time history of surface temperature difference for flash-heated targets. We relate these patterns to the location, size, shape and depth of subsurface flaws. We have demonstrated temperature accuracies of 0.2{degree}C, timing synchronizations of 3 ms (after onset of heat flash) and intervals of 42 ms, between images, during an 8 s cooling (and hearing) interval characterizing the front (and back) surface temperature-time history of an epoxy-glue disbond site in a flash-heated aluminum lap joint. This type of disbond played a significant role in causing damage to the Aloha Aircraft fuselage on the aged Boeing 737 jetliner. By ratioing DBIR images (near 5 and 10 micron), we located surface temperature patterns (generated by weak heat flow anomalies at subsurface flaw sites) and removed the emissivity mask (from surface roughness variations). We compared measurements with calculations from the three-dimensional, finite element computer code: TOPAZ3D. We combined infrared, ultrasound and x-ray imaging methods to characterize the lap joint disbond site spatial, bond quality, and material differences.

  17. Hemodynamic assessment of partial mechanical circulatory support: data derived from computed tomography angiographic images and computational fluid dynamics.

    PubMed

    Karmonik, Christof; Partovi, Sasan; Rengier, Fabian; Meredig, Hagen; Farag, Mina Berty; Müller-Eschner, Matthias; Arif, Rawa; Popov, Aron-Frederik; Kauczor, Hans-Ulrich; Karck, Matthias; Ruhparwar, Arjang

    2015-04-01

    Partial mechanical circulatory support represents a new concept for the treatment of advanced heart failure. The Circulite Synergy Micro Pump(®), where the inflow cannula is connected to the left atrium and the outflow cannula to the right subclavian artery, was one of the first devices to introduce this concept to the clinic. Using computational fluid dynamics (CFD) simulations, hemodynamics in the aortic tree was visualized and quantified from computed tomography angiographic (CTA) images in two patients. A realistic computational model was created by integrating flow information from the native heart and from the Circulite device. Diastolic flow augmentation in the descending aorta but competing/antagonizing flow patterns in the proximal innominate artery was observed. Velocity time curves in the ascending aorta correlated well with those in the left common carotid, the left subclavian and the descending aorta but poorly with the one in the innominate. Our results demonstrate that CFD may be useful in providing a better understanding of the main flow patterns in mechanical circulatory support devices. PMID:25984458

  18. Micro/Nano-Computed Tomography Technology for Quantitative Dynamic, Multi-scale Imaging of Morphogenesis

    PubMed Central

    Gregg, Chelsea L.; Recknagel, Andrew K.; Butcher, Jonathan T.

    2015-01-01

    Tissue morphogenesis and embryonic development are dynamic events challenging to quantify, especially considering the intricate events that happen simultaneously in different locations and time. Micro-, and more recently nano-computed tomography (micro/nanoCT), has been used for the past 15 years to characterize large 3D fields of tortuous geometries at high spatial resolution. We and others have advanced micro/nanoCT imaging strategies for quantifying tissue and organ level fate changes throughout morphogenesis. Exogenous soft tissue contrast media enables visualization of vascular lumens and tissues via extravasation. Furthermore, the emergence of antigen specific tissue contrast enables direct quantitative visualization of protein and mRNA expression. Micro-CT X-ray doses appear to be non-embryotoxic, enabling longitudinal imaging studies in live embryos. In this paper we present established soft tissue contrast protocols for obtaining high quality micro/nanoCT images and the image processing techniques useful for quantifying anatomical and physiological information from the datasets. PMID:25245686

  19. Micro/nano-computed tomography technology for quantitative dynamic, multi-scale imaging of morphogenesis.

    PubMed

    Gregg, Chelsea L; Recknagel, Andrew K; Butcher, Jonathan T

    2015-01-01

    Tissue morphogenesis and embryonic development are dynamic events challenging to quantify, especially considering the intricate events that happen simultaneously in different locations and time. Micro- and more recently nano-computed tomography (micro/nanoCT) has been used for the past 15 years to characterize large 3D fields of tortuous geometries at high spatial resolution. We and others have advanced micro/nanoCT imaging strategies for quantifying tissue- and organ-level fate changes throughout morphogenesis. Exogenous soft tissue contrast media enables visualization of vascular lumens and tissues via extravasation. Furthermore, the emergence of antigen-specific tissue contrast enables direct quantitative visualization of protein and mRNA expression. Micro-CT X-ray doses appear to be non-embryotoxic, enabling longitudinal imaging studies in live embryos. In this chapter we present established soft tissue contrast protocols for obtaining high-quality micro/nanoCT images and the image processing techniques useful for quantifying anatomical and physiological information from the data sets. PMID:25245686

  20. Analysis and Correction of Dynamic Geometric Misalignment for Nano-Scale Computed Tomography at BSRF.

    PubMed

    Fu, Jian; Li, Chen; Liu, Zhenzhong

    2015-01-01

    Due to its high spatial resolution, synchrotron radiation x-ray nano-scale computed tomography (nano-CT) is sensitive to misalignments in scanning geometry, which occurs quite frequently because of mechanical errors in manufacturing and assembly or from thermal expansion during the time-consuming scanning. Misalignments degrade the imaging results by imposing artifacts on the nano-CT slices. In this paper, the geometric misalignment of the synchrotron radiation nano-CT has been analyzed by partial derivatives on the CT reconstruction algorithm and a correction method, based on cross correlation and least-square sinusoidal fitting, has been reported. This work comprises a numerical study of the method and its experimental verification using a dataset measured with the full-field transmission x-ray microscope nano-CT at the beamline 4W1A of the Beijing Synchrotron Radiation Facility. The numerical and experimental results have demonstrated the validity of the proposed approach. It can be applied for dynamic geometric misalignment and needs neither phantom nor additional correction scanning. We expect that this method will simplify the experimental operation of synchrotron radiation nano-CT. PMID:26509552

  1. Analysis and Correction of Dynamic Geometric Misalignment for Nano-Scale Computed Tomography at BSRF

    PubMed Central

    Fu, Jian; Li, Chen; Liu, Zhenzhong

    2015-01-01

    Due to its high spatial resolution, synchrotron radiation x-ray nano-scale computed tomography (nano-CT) is sensitive to misalignments in scanning geometry, which occurs quite frequently because of mechanical errors in manufacturing and assembly or from thermal expansion during the time-consuming scanning. Misalignments degrade the imaging results by imposing artifacts on the nano-CT slices. In this paper, the geometric misalignment of the synchrotron radiation nano-CT has been analyzed by partial derivatives on the CT reconstruction algorithm and a correction method, based on cross correlation and least-square sinusoidal fitting, has been reported. This work comprises a numerical study of the method and its experimental verification using a dataset measured with the full-field transmission x-ray microscope nano-CT at the beamline 4W1A of the Beijing Synchrotron Radiation Facility. The numerical and experimental results have demonstrated the validity of the proposed approach. It can be applied for dynamic geometric misalignment and needs neither phantom nor additional correction scanning. We expect that this method will simplify the experimental operation of synchrotron radiation nano-CT. PMID:26509552

  2. Framework for cognitive analysis of dynamic perfusion computed tomography with visualization of large volumetric data

    NASA Astrophysics Data System (ADS)

    Hachaj, Tomasz; Ogiela, Marek R.

    2012-10-01

    The proposed framework for cognitive analysis of perfusion computed tomography images is a fusion of image processing, pattern recognition, and image analysis procedures. The output data of the algorithm consists of: regions of perfusion abnormalities, anatomy atlas description of brain tissues, measures of perfusion parameters, and prognosis for infracted tissues. That information is superimposed onto volumetric computed tomography data and displayed to radiologists. Our rendering algorithm enables rendering large volumes on off-the-shelf hardware. This portability of rendering solution is very important because our framework can be run without using expensive dedicated hardware. The other important factors are theoretically unlimited size of rendered volume and possibility of trading of image quality for rendering speed. Such rendered, high quality visualizations may be further used for intelligent brain perfusion abnormality identification, and computer aided-diagnosis of selected types of pathologies.

  3. Dynamic computed tomography findings of an accessory spleen in the pelvis: a case report.

    PubMed

    Ota, Hiroshi; Ojima, Yasutomo; Sumitani, Daisuke; Okajima, Masazumi

    2016-12-01

    We report the case of a 60-year-old man with an accessory spleen in the pelvis. He visited our outpatient clinic because of abdominal discomfort. Computed tomography (CT) showed an enhanced mass (40 mm in diameter) in the pelvis. Preoperative diagnosis was difficult even after magnetic resonance imaging and colonoscopy. The patient underwent surgery for suspicion of a gastrointestinal stromal tumor or malignant lymphoma of the rectum. Intraoperative findings showed a mass in the pelvis and a long cord-like tissue reaching the mass and arising from the great omentum; the mass was excised. Histopathologic examination indicated that the mass was splenic tissue, and feeding vessels were found in the cord-like tissue, which were determined to be derived from the left gastroepiploic artery and vein. Thus, we diagnosed it as an accessory spleen in the pelvis. An accessory spleen is not rare and can occur anywhere in the abdominal cavity. However, an accessory spleen in the pelvis is an infrequent finding, and only 9 other cases of an accessory spleen in the pelvis have been reported. Therefore, it is very difficult to make a correct diagnosis preoperatively. However, 7 of the 9 cases (77.8 %) of a pelvic accessory spleen had vascular pedicles from the great omentum or splenic hilum as feeding vessels; hence, determining the feeding blood vessels on dynamic CT may be useful for diagnosing an accessory spleen in the pelvis. Additionally, if the accessory spleen is symptomatic or has a vascular pedicle, surgeons should attempt to resect the accessory spleen in the pelvis using minimally invasive laparoscopy. PMID:26970956

  4. Four-dimensional computed tomography and detection of dynamic capitate subluxation.

    PubMed

    Repse, Stephen E; Amis, Benjamin; Troupis, John M

    2015-06-01

    Midcarpal instability syndrome is often misdiagnosed, leading to delayed recognition, treatment and possibly poor clinical outcome. Four-dimensional computed tomography (4D CT) has previously proved useful in assessment of the acromioclavicular joint and wrist motion, allowing clinicians and radiologists to gain an understanding of abnormalities in function as well as morphology, which often contribute to patient symptoms. We present the case of a 25-year-old male with no history of trauma who presents with several months of a right wrist clunk on both passive and active (load bearing) motion. Plain film and 1.5 Tesla MRI with intra-articular contrast demonstrates a normal appearance, without joint space, tendon or ligament disturbance. We further investigated this condition using a wide volume detector CT scanning technique (4D CT). Data from the patient's asymptomatic wrist was utilized as a comparison for this study. Assessment of cine movie files from the symptomatic wrist revealed abnormal subluxation of the capitate from the lunate when compared with the normal wrist, in which the capitate did not deviate from the concavity of the lunate and did not cross the perpendicular line from the superior pole of the lunate in any phase of motion, which we defined as capitate subluxation. 4D CT allows for detection of capitate subluxation in an earlier stage of disease progression, constituting earlier recognition and providing the opportunity for earlier treatment of the disease, potentially mitigating significant patient morbidity. We have been able to confidently identify capitate subluxation both visually (assessment of the sagittal RLC axis) and objectively (documentation of percent subluxation of the capitate beyond the superior pole of the lunate). We propose that 4D CT investigation of all functional carpal instability syndromes may be beneficial as this technique has the potential to significantly increase our knowledge of dynamic carpal bone abnormalities

  5. Performance assessment of a new dynamic scan mode for perfusion computed tomography using a biological phantom

    NASA Astrophysics Data System (ADS)

    Haberland, U.; Klotz, E.,; Abolmaali, N.

    2010-04-01

    Perfusion computed tomography is increasingly being used for stroke and tumor assessment. Using continuous periodic table movement the spatial coverage can be increased beyond the detector width with a new adaptive spiral scanning technique (A4DS). The purpose of this study was to compare perfusion values acquired with the A4DS technique with results from standard dynamic scans at different temporal sampling rates. A biological perfusion phantom (preserved porcine kidney) was scanned with both techniques. In standard mode three scans were performed at adjacent overlapping positions (detector width 38.4 mm) covering the whole phantom. Data were reconstructed with temporal resolutions of 0.5, 1 and 1.5 s. The A4DS scan was performed with a cycle time of 1.5 s and scan ranges of 100 and 148 mm respectively. The phantom was not repositioned between scans in order to assure that identical image slices showed identical phantom slices. Tissue flow was calculated with a deconvolution type algorithm. Regions of interest were drawn in strongly and moderately enhancing areas and around the whole cortex in three slices in the upper, central and lower portion of the phantom. In the flow range of 40 to 100 ml/100ml/min values did not differ by more than 5 ml/100ml/min between any of the scan protocols used. The correlation between the continuous table movement modes and the 0.5 s standard mode was excellent (r2>0.98) indicating that the new mode is well suited for perfusion measurements and allows increasing the coverage by almost a factor of four.

  6. Extracellular volume quantification by dynamic equilibrium cardiac computed tomography in cardiac amyloidosis

    PubMed Central

    Treibel, Thomas A.; Bandula, Steve; Fontana, Marianna; White, Steven K.; Gilbertson, Janet A.; Herrey, Anna S.; Gillmore, Julian D.; Punwani, Shonit; Hawkins, Philip N.; Taylor, Stuart A.; Moon, James C.

    2015-01-01

    Background Cardiac involvement determines outcome in patients with systemic amyloidosis. There is major unmet need for quantification of cardiac amyloid burden, which is currently only met in part through semi-quantitative bone scintigraphy or Cardiovascular Magnetic Resonance (CMR), which measures ECVCMR. Other accessible tests are needed. Objectives To develop cardiac computed tomography to diagnose and quantify cardiac amyloidosis by measuring the myocardial Extracellular Volume, ECVCT. Methods Twenty-six patients (21 male, 64 ± 14 years) with a biopsy-proven systemic amyloidosis (ATTR n = 18; AL n = 8) were compared with twenty-seven patients (19 male, 68 ± 8 years) with severe aortic stenosis (AS). All patients had undergone echocardiography, bone scintigraphy, NT-pro-BNP measurement and EQ-CMR. Dynamic Equilibrium CT (DynEQ-CT) was performed using a prospectively gated cardiac scan prior to and after (5 and 15 minutes) a standard Iodixanol (1 ml/kg) bolus to measure ECVCT. ECVCT was compared to the reference ECVCMR and conventional amyloid measures: bone scintigraphy and clinical markers of cardiac amyloid severity (NT-pro-BNP, Troponin, LVEF, LV mass, LA and RA area). Results ECVCT and ECVCMR results were well correlated (r2 = 0.85 vs r2 = 0.74 for 5 and 15 minutes post bolus respectively). ECVCT was higher in amyloidosis than AS (0.54 ± 0.11 vs 0.28 ± 0.04, p<0.001) with no overlap. ECVCT tracked clinical markers of cardiac amyloid severity (NT-pro-BNP, Troponin, LVEF, LV mass, LA and RA area), and bone scintigraphy amyloid burden (p<0.001). Conclusion Dynamic Equilibrium CT, a 5 minute contrast-enhanced gated cardiac CT, has potential for non-invasive diagnosis and quantification of cardiac amyloidosis. PMID:26209459

  7. Porcine Ex Vivo Liver Phantom for Dynamic Contrast-Enhanced Computed Tomography: Development and Initial Results

    PubMed Central

    Thompson, Scott M.; Giraldo, Juan C. Ramirez; Knudsen, Bruce; Grande, Joseph P.; Christner, Jodie A.; Xu, Man; Woodrum, David A.; McCollough, Cynthia H.; Callstrom, Matthew R.

    2011-01-01

    Objectives To demonstrate the feasibility of developing a fixed, dual-input, biological liver phantom for dynamic contrast-enhanced computed tomography (CT) imaging and to report initial results of use of the phantom for quantitative CT perfusion imaging. Materials and Methods Porcine livers were obtained from completed surgical studies and perfused with saline and fixative. The phantom was placed in a body-shaped, CT-compatible acrylic container and connected to a perfusion circuit fitted with a contrast injection port. Flow-controlled contrast-enhanced imaging experiments were performed using a 128-slice and 64 slice, dual-source multidetector CT scanners. CT angiography protocols were employed to obtain portal venous and hepatic arterial vascular enhancement, reproduced over a period of four to six months. CT perfusion protocols were employed at different input flow rates to correlate input flow with calculated tissue perfusion, to test reproducibility and demonstrate the feasibility of simultaneous dual input liver perfusion. Histologic analysis of the liver phantom was also performed. Results CT angiogram 3D reconstructions demonstrated homogenous tertiary and quaternary branching of the portal venous system out to the periphery of all lobes of the liver as well as enhancement of the hepatic arterial system to all lobes of the liver and gallbladder throughout the study period. For perfusion CT, the correlation between the calculated mean tissue perfusion in a volume of interest and input pump flow rate was excellent (R2 = 0.996) and color blood flow maps demonstrated variations in regional perfusion in a narrow range. Repeat perfusion CT experiments demonstrated reproducible time-attenuation curves and dual-input perfusion CT experiments demonstrated that simultaneous dual input liver perfusion is feasible. Histologic analysis demonstrated that the hepatic microvasculature and architecture appeared intact and well preserved at the completion of four to six

  8. Computed Tomography Status

    DOE R&D Accomplishments Database

    Hansche, B. D.

    1983-01-01

    Computed tomography (CT) is a relatively new radiographic technique which has become widely used in the medical field, where it is better known as computerized axial tomographic (CAT) scanning. This technique is also being adopted by the industrial radiographic community, although the greater range of densities, variation in samples sizes, plus possible requirement for finer resolution make it difficult to duplicate the excellent results that the medical scanners have achieved.

  9. Computed tomography status

    SciTech Connect

    Hansche, B.D.

    1983-01-01

    Computed tomography (CT) is a relatively new radiographic technique which has become widely used in the medical field, where it is better known as computerized axial tomographic (CAT) scanning. This technique is also being adopted by the industrial radiographic community, although the greater range of densities, variation in samples sizes, plus possible requirement for finer resolution make it difficult to duplicate the excellent results that the medical scanners have achieved.

  10. Quantitative Functional Imaging Using Dynamic Positron Computed Tomography and Rapid Parameter Estimation Techniques

    NASA Astrophysics Data System (ADS)

    Koeppe, Robert Allen

    Positron computed tomography (PCT) is a diagnostic imaging technique that provides both three dimensional imaging capability and quantitative measurements of local tissue radioactivity concentrations in vivo. This allows the development of non-invasive methods that employ the principles of tracer kinetics for determining physiological properties such as mass specific blood flow, tissue pH, and rates of substrate transport or utilization. A physiologically based, two-compartment tracer kinetic model was derived to mathematically describe the exchange of a radioindicator between blood and tissue. The model was adapted for use with dynamic sequences of data acquired with a positron tomograph. Rapid estimation techniques were implemented to produce functional images of the model parameters by analyzing each individual pixel sequence of the image data. A detailed analysis of the performance characteristics of three different parameter estimation schemes was performed. The analysis included examination of errors caused by statistical uncertainties in the measured data, errors in the timing of the data, and errors caused by violation of various assumptions of the tracer kinetic model. Two specific radioindicators were investigated. ('18)F -fluoromethane, an inert freely diffusible gas, was used for local quantitative determinations of both cerebral blood flow and tissue:blood partition coefficient. A method was developed that did not require direct sampling of arterial blood for the absolute scaling of flow values. The arterial input concentration time course was obtained by assuming that the alveolar or end-tidal expired breath radioactivity concentration is proportional to the arterial blood concentration. The scale of the input function was obtained from a series of venous blood concentration measurements. The method of absolute scaling using venous samples was validated in four studies, performed on normal volunteers, in which directly measured arterial concentrations

  11. Imaging and modeling of flow in porous media using clinical nuclear emission tomography systems and computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Boutchko, Rostyslav; Rayz, Vitaliy L.; Vandehey, Nicholas T.; O'Neil, James P.; Budinger, Thomas F.; Nico, Peter S.; Druhan, Jennifer L.; Saloner, David A.; Gullberg, Grant T.; Moses, William W.

    2012-01-01

    This paper presents experimental and modeling aspects of applying nuclear emission tomography to study fluid flow in laboratory packed porous media columns of the type frequently used in geophysics, geochemistry and hydrology research. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are used as non-invasive tools to obtain dynamic 3D images of radioactive tracer concentrations. Dynamic sequences obtained using 18F-FDG PET are used to trace flow through a 5 cm diameter × 20 cm tall sand packed column with and without an impermeable obstacle. In addition, a custom-made rotating column setup placed in a clinical two-headed SPECT camera is used to image 99mTc-DTPA tracer propagation in a through-flowing column (10 cm diameter × 30 cm tall) packed with recovered aquifer sediments. A computational fluid dynamics software package FLUENT is used to model the observed flow dynamics. Tracer distributions obtained in the simulations in the smaller column uniformly packed with sand and in the column with an obstacle are remarkably similar to the reconstructed images in the PET experiments. SPECT results demonstrate strongly non-uniform flow patterns for the larger column slurry-packed with sub-surface sediment and slow upward flow. In the numerical simulation of the SPECT study, two symmetric channels with increased permeability are prescribed along the column walls, which result in the emergence of two well-defined preferential flow paths. Methods and results of this work provide new opportunities in hydrologic and biogeochemical research. The primary target application for developed technologies is non-destructive, non-perturbing, quantitative imaging of flow dynamics within laboratory scale porous media systems.

  12. Dynamic computed tomography of the pituitary gland using a single slice scanner in dogs with pituitary-dependent hypercortisolism.

    PubMed

    Del Magno, Sara; Grinwis, Guy C M; Voorhout, George; Meij, Björn P

    2016-08-01

    Selective removal of the pituitary adenoma has not been advocated in dogs with pituitary-dependent hypercortisolism because the pituitary adenoma is usually not visualized on routine computed tomography (CT). Dynamic pituitary CT scanning is aimed at the detection of the pituitary flush and, indirectly, at the presence and position of the adenoma. The first aim of this retrospective study was to compare findings of a multiple slice dynamic scanning protocol with those of a single slice dynamic protocol using a single slice CT scanner. The second aim was to compare the CT findings with surgical findings, and surgical findings with histopathological findings. Computed tomography with single and multiple slice dynamic scanning protocols was performed in 86 dogs with pituitary-dependent hypercortisolism. Thirty dogs underwent transsphenoidal hypophysectomy and pituitary specimens were collected as tumor, normal, mixed and neurohypophyseal samples and processed for histology. The pituitary flush was not detected more frequent in multiple slice dynamic scanning series than in single slice dynamic scanning series. However, in non-enlarged pituitaries, the flush was seen significantly more frequently than in enlarged pituitaries. Prediction of the nature of the tissue during hypophysectomy by the surgeon was inconclusive. In conclusion, when using a single slice CT scanner, both single or multiple slice dynamic scanning protocols can be used for localization of the neurohypophyseal flush, and, indirectly, the adenoma. However, based on this study, the aim of surgery in dogs with pituitary-dependent hypercortisolism remains total adenohypophysectomy, and when the neurophypophysis is recognized, it may be left in situ. PMID:27473973

  13. Impact of hemodynamics on lumen boundary displacements in abdominal aortic aneurysms by means of dynamic computed tomography and computational fluid dynamics.

    PubMed

    Piccinelli, Marina; Vergara, Christian; Antiga, Luca; Forzenigo, Laura; Biondetti, Pietro; Domanin, Maurizio

    2013-11-01

    The aim of the present work is to quantitatively assess the three-dimensional distributions of the displacements experienced during the cardiac cycle by the luminal boundary of abdominal aortic aneurysm (AAA) and to correlate them with the local bulk hemodynamics. Ten patients were acquired by means of time resolved computed tomography, and each patient-specific vascular morphology was reconstructed for all available time frames. The AAA lumen boundary motion was tracked, and the lumen boundary displacements (LBD) computed for each time frame. The intra-aneurysm hemodynamic quantities, specifically wall shear stress (WSS), were evaluated with computational fluid dynamics simulations. Co-localization of LBD and WSS distributions was evaluated by means of Pearson correlation coefficient. A clear anisotropic distribution of LBD was evidenced in both space and time; a combination of AAA lumen boundary inward- and outward-directed motions was assessed. A co-localization between largest outward LBD and high WSS was demonstrated supporting the hypothesis of a mechanistic relationship between anisotropic displacement and hemodynamic forces related to the impingement of the blood on the lumen boundary. The presence of anisotropic displacement of the AAA lumen boundary and their link to hemodynamic forces have been assessed, highlighting a new possible role for hemodynamics in the study of AAA progression. PMID:23446648

  14. Computed tomography of electronics

    NASA Astrophysics Data System (ADS)

    Bossi, Richard H.; Kruse, Robert J.; Knutson, Benjamin W.

    1989-12-01

    The application of Computed Tomography (CT) and laminography was tested on a variety of electronic components. The effort was performed as a preliminary testing task assignment in the Advanced Development of X ray Computed Tomography Application program. A key area for testing was printed circuit boards for the inspection of solder bonds and in particular for leadless chip carrier devices. During the course of the task assignment several other categories of electronic devices were examined including transformers, connectors, switches from solution and contrast sensitivity phantoms developed for the programs were used to establish quantitative measures of capability used to generate images. This preliminary testing of electronics lead to the conclusion that higher resolution CT scanning is needed to resolve details of interest. CT testing on commercially available system could resolve high contrast details in the range of 2 to 4 lp/mm; however, in many electronic components finer resolution is needed to detect microcracking, voiding and other features. Further testing on high resolution system is recommended. Two areas of immediate potential economic payback for electronics inspection were identified; the inspection of high volume printed circuit board production using high speed laminography and nondestructive failure analysis studies components using high-resolution CT.

  15. Tumor Delineation Based on Time-Activity Curve Differences Assessed With Dynamic Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Rectal Cancer Patients

    SciTech Connect

    Janssen, Marco Aerts, Hugo; Ollers, Michel C.; Bosmans, Geert; Lee, John A.; Buijsen, Jeroen; Ruysscher, Dirk de; Lambin, Philippe; Lammering, Guido; Dekker, Andre L.A.J.

    2009-02-01

    Purpose: To develop an unsupervised tumor delineation method based on time-activity curve (TAC) shape differences between tumor tissue and healthy tissue and to compare the resulting contour with the two tumor contouring methods mostly used nowadays. Methods and Materials: Dynamic positron emission tomography-computed tomography (PET-CT) acquisition was performed for 60 min starting directly after fluorodeoxyglucose (FDG) injection. After acquisition and reconstruction, the data were filtered to attenuate noise. Correction for tissue motion during acquisition was applied. For tumor delineation, the TAC slope values were k-means clustered into two clusters. The resulting tumor contour (Contour I) was compared with a contour manually drawn by the radiation oncologist (Contour II) and a contour generated using a threshold of the maximum standardized uptake value (SUV; Contour III). Results: The tumor volumes of Contours II and III were significantly larger than the tumor volumes of Contour I, with both Contours II and III containing many voxels showing flat TACs at low activities. However, in some cases, Contour II did not cover all voxels showing upward TACs. Conclusion: Both automated SUV contouring and manual tumor delineation possibly incorrectly assign healthy tissue, showing flat TACs, as being malignant. On the other hand, in some cases the manually drawn tumor contours do not cover all voxels showing steep upward TACs, suspected to be malignant. Further research should be conducted to validate the possible superiority of tumor delineation based on dynamic PET analysis.

  16. Stored luminescence computed tomography.

    PubMed

    Cong, Wenxiang; Wang, Chao; Wang, Ge

    2014-09-01

    Phosphor nanoparticles made of doped semiconductors and pre-excited by x-ray radiation were recently reported for their luminescence emission in the range of 650-770 nm upon near-infrared (NIR) light stimulation. These nanophosphors can be functionalized as optical probes for molecular imaging. In this paper, we present stored luminescence computed tomography to reconstruct a nanophosphor distribution in an object. The propagation of x rays in a biological object allows significantly better localization and deeper penetration. Moreover, the nanophosphors, which are pre-excited with collimated x-ray beams or focused x-ray waves, can be successively stimulated for stored luminescence emissions by variable NIR stimulation patterns. The sequentially detected luminescence signals provide more information of a nanophosphor spatial distribution for more accurate image reconstruction and higher image resolution. A realistic numerical study is performed to demonstrate the feasibility and merits of the proposed approach. PMID:25321362

  17. Computed Tomography Measuring Inside Machines

    NASA Technical Reports Server (NTRS)

    Wozniak, James F.; Scudder, Henry J.; Anders, Jeffrey E.

    1995-01-01

    Computed tomography applied to obtain approximate measurements of radial distances from centerline of turbopump to leading edges of diffuser vanes in turbopump. Use of computed tomography has significance beyond turbopump application: example of general concept of measuring internal dimensions of assembly of parts without having to perform time-consuming task of taking assembly apart and measuring internal parts on coordinate-measuring machine.

  18. Micro-computed tomography based computational fluid dynamics for the determination of shear stresses in scaffolds within a perfusion bioreactor.

    PubMed

    Zermatten, Emilie; Vetsch, Jolanda Rita; Ruffoni, Davide; Hofmann, Sandra; Müller, Ralph; Steinfeld, Aldo

    2014-05-01

    Perfusion bioreactors are known to exert shear stresses on cultured cells, leading to cell differentiation and enhanced extracellular matrix deposition on scaffolds. The influence of the scaffold's porous microstructure is investigated for a polycaprolactone (PCL) scaffold with a regular microarchitecture and a silk fibroin (SF) scaffold with an irregular network of interconnected pores. Their complex 3D geometries are imaged by micro-computed tomography and used in direct pore-level simulations of the entire scaffold-bioreactor system to numerically solve the governing mass and momentum conservation equations for fluid flow through porous media. The velocity field and wall shear stress distribution are determined for both scaffolds. The PCL scaffold exhibited an asymmetric distribution with peak and plateau, while the SF scaffold exhibited a homogenous distribution and conditioned the flow more efficiently than the PCL scaffold. The methodology guides the design and optimization of the scaffold geometry. PMID:24492950

  19. Method for Studying the Myocardial Blood Flow Reserve by Load Dynamic Single-Photon Emission Computed Tomography.

    PubMed

    Mochula, A V; Zavadovsky, K V; Lishmanov, Yu B

    2016-04-01

    We developed a method for collection and processing of scintigraphic data to estimate myocardial reserve in a gamma-chamber with cadmium-zinc-telluride detectors. Dynamic single-photon emission computed tomography of the heart with (99m)Tc-Technetril was performed in 16 coronary heart disease patients at rest and during pharmacological load. During data processing, regions of interest from the cavity and the myocardium of the left ventricle were formed and activity-time curves were constructed. The index of myocardial blood fl ow reserve was calculated as the difference between two ratios of the mean gamma-count from the myocardial area to the area under the left ventricle cavity curve (peak) during load and at rest. The mean indices of myocardial reserve in healthy volunteers and patients with coronary artery atherosclerosis were 1.86 (1.59; 2.20) and 1.39 (1.12; 1.69), respectively. The development of the method for studying myocardial reserve by single-photon emission computed tomography is an urgent problem and requires further investigations. PMID:27165060

  20. Dynamic Computed Tomography Angiography: Role in the Evaluation of Popliteal Artery Entrapment Syndrome

    SciTech Connect

    Anil, Gopinathan Tay, Kiang-Hiong; Howe, Tse-Chiang; Tan, Bien-Soo

    2011-04-15

    This study reviews our experience with dynamic computed tomographic angiography (CTA) as an imaging modality in the evaluation of popliteal artery entrapment syndrome (PAES). Eight patients with surgically proven PAES were included in this study. Dynamic CTA studies performed with the feet in neutral and plantar flexed positions were reviewed for the detailed anatomy of the region and to define the location and extent of the stenosis, occlusions and collateral circulation. These findings were compared with intraoperative observations. CTA provided adequate angiographic and anatomic information required to arrive at the diagnosis and make a surgical decision. Thirteen limbs were affected in eight patients. There was popliteal artery occlusion in four limbs, stenosis at rest that was accentuated on stress imaging in two limbs, and patent popliteal artery with marked stenosis on stress imaging in seven limbs. Long-segment stenosis was seen in functional entrapment compared to short-segment stenosis in anatomic PAES. Anteroposterior compression of the popliteal artery in anatomic PAES unlike the side-to-side compression in functional PAES was a unique observation in this study. The CTA and surgical characterisation and classification of PAES matched in all the patients, except for misinterpretation of compressing fibrous bands as accessory slips of muscles in three limbs. In conclusion, dynamic CTA is a robust diagnostic tool that provides clinically relevant information and serves as a rapidly performed and easily available 'one-stop-shop' imaging modality in the management of PAES.

  1. Puffed-cheek computed tomography: a dynamic maneuver for imaging oral cavity tumors.

    PubMed

    Erdogan, Nezahat; Bulbul, Erdogan; Songu, Murat; Uluc, Engin; Onal, Kazim; Apaydin, Melda; Katilmis, Huseyin

    2012-09-01

    We conducted a prospective study to compare the effectiveness of conventional computed tomography (CT) and puffed-cheek CT in detecting the presence and extension of oral cavity malignant tumors. We enrolled 11 patients--5 men and 6 women, aged 32 to 85 years--who had a primary squamous cell carcinoma of the oral cavity. These tumors were located in the floor of the mouth in 4 patients, in the buccal mucosa in 4, in both the buccal mucosa and retromolar trigone in 2, and in the retromolar trigone only in 1. First, conventional contrast-enhanced axial CT was obtained through the oral cavity and neck in each patient. Next, axial imaging was obtained through the oral cavity while patients inflated their cheeks, pursed their lips, and held their breath. We found that the puffed-cheek CTs provided more information regarding the size and extent of the squamous cell carcinomas than did the conventional CTs. For example, in 8 patients, conventional CT could not differentiate the tumor from the normal mucosal surface, but puffed-cheek images clearly showed the surface of the tumor as distinct from the normal mucosa. More disconcerting was the fact that in the other 3 patients, conventional CTs were evaluated as normal, even though puffed-cheek imaging clearly showed the mass in each case. We conclude that puffed-cheek CT is superior to conventional CT for evaluating the mucosal surfaces of the oral cavity. It provides a clearer and more detailed picture with no downside. PMID:22996710

  2. Dynamic positron computed tomography of the heart with a high sensitivity positron camera and nitrogen-13 ammonia

    SciTech Connect

    Tamaki, N.; Senda, M.; Yonekura, Y.; Saji, H.; Kodama, S.; Konishi, Y.; Ban, T.; Kambara, H.; Kawai, C.; Torizuka, K.

    1985-06-01

    Dynamic positron computed tomography (PCT) of the heart was performed with a high-sensitivity, whole-body multislice PCT device and (/sup 13/N)ammonia. Serial 15-sec dynamic study immediately after i.v. (/sup 13/N)ammonia injection showed blood pool of the ventricular cavities in the first scan and myocardial images from the third scan in normal cases. In patients with myocardial infarction and mitral valve disease, tracer washout from the lung and myocardial peak time tended to be longer, suggesting presence of pulmonary congestion. PCT delineated tracer retention in the dorsal part of the lung. Serial 5-min late dynamic study in nine cases showed gradual increase in myocardial activity for 30 min in all normal segments and 42% of infarct segments, while less than 13% activity increase was observed in 50% of infarct segments. Thus, serial dynamic PCT with (/sup 13/N)ammonia assessing tracer kinetics in the heart and lung is a valuable adjunct to the static myocardial perfusion imaging for evaluation of various cardiac disorders.

  3. Computed tomography of the body

    SciTech Connect

    Lee, J.K.T.; Stanley, R.J.

    1982-01-01

    By the end of the fourth year of clinical use, the number of articles dealing with computed body tomography (CT) had increased exponentially. Over 100 articles were published during this review period. This chapter examines new application of CT in the neck, musculoskeletal system and the breast. The chapter begins with an examination of the technical aspects of the operation and performance of CT scanners during this review period. The anatomy of various regions of the body, such as neck, chest, liver and biliary system, genitourinary tract, and pelvis are examined. Brief discussions of pediatric computed tomography, computed tomography-guided biopsy, and radiation therapy are presented. (KRM)

  4. Integrated 18F-Fluorodeoxyglucose–Positron Emission Tomography/Dynamic Contrast-Enhanced Computed Tomography to Phenotype Non–Small Cell Lung Carcinoma

    PubMed Central

    Shastry, Manu; Miles, Kenneth A.; Win, Thida; Janes, Sam M.; Endozo, Raymond; Meagher, Marie; Ell, Peter J.; Groves, Ashley M.

    2012-01-01

    We applied modern molecular and functional imaging to the pretreatment assessment of lung cancer using combined dynamic contrast-enhanced computed tomography (DCE-CT) and 18F-fluorodeoxyglucose–positron emission tomography (18F-FDG-PET) to phenotype tumors. Seventy-four lung cancer patients were prospectively recruited for 18F-FDG-PET/DCE-CT using PET/64-detector CT. After technical failures, there were 64 patients (35 males, 29 females; mean age [± SD] 67.5 ± 7.9 years). DCE-CT yielded tumor peak enhancement (PE) and standardized perfusion value (SPV). The uptake of 18F-FDG quantified on PET as the standardized uptake value (SUVmax) assessed tumor metabolism. The median values for SUVmax and SPV were used to define four vascular-metabolic phenotypes. There were associations (Spearman rank correlation [rs]) between tumor size and vascular-metabolic parameters: SUVmax versus size (rs = .40, p = .001) and SUV/PE versus size (r = .43, p < .001). Patients with earlier-stage (I–IIA, n = 30) disease had mean (± SD) SUV/PE 0.36 ± 0.28 versus 0.56 ± 0.32 in later-stage (stage IIB–IV, n = 34) disease (p = .007). The low metabolism with high vascularity phenotype was significantly more common among adenocarcinomas (p = .018), whereas the high metabolism with high vascularity phenotype was more common among squamous cell carcinomas (p = .024). Other non–small cell lung carcinoma tumor types demonstrated a high prevalence of the high metabolism with low vascularity phenotype (p = .028). We show that tumor subtypes have different vascular-metabolic associations, which can be helpful clinically in managing lung cancer patients to hone targeted therapy. PMID:22954179

  5. Integrated 18F-fluorodeoxyglucose-positron emission tomography/dynamic contrast-enhanced computed tomography to phenotype non-small cell lung carcinoma.

    PubMed

    Shastry, Manu; Miles, Kenneth A; Win, Thida; Janes, Sam M; Endozo, Raymond; Meagher, Marie; Ell, Peter J; Groves, Ashley M

    2012-01-01

    We applied modern molecular and functional imaging to the pretreatment assessment of lung cancer using combined dynamic contrast-enhanced computed tomography (DCE-CT) and (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET) to phenotype tumors. Seventy-four lung cancer patients were prospectively recruited for (18)F-FDG-PET/DCE-CT using PET/64-detector CT. After technical failures, there were 64 patients (35 males, 29 females; mean age [± SD] 67.5 ± 7.9 years). DCE-CT yielded tumor peak enhancement (PE) and standardized perfusion value (SPV). The uptake of (18)F-FDG quantified on PET as the standardized uptake value (SUV(max)) assessed tumor metabolism. The median values for SUV(max) and SPV were used to define four vascular-metabolic phenotypes. There were associations (Spearman rank correlation [rs]) between tumor size and vascular-metabolic parameters: SUV(max) versus size (rs  =  .40, p  =  .001) and SUV/PE versus size (r  =  .43, p < .001). Patients with earlier-stage (I-IIA, n  =  30) disease had mean (± SD) SUV/PE 0.36 ± 0.28 versus 0.56 ± 0.32 in later-stage (stage IIB-IV, n  =  34) disease (p  =  .007). The low metabolism with high vascularity phenotype was significantly more common among adenocarcinomas (p  =  .018), whereas the high metabolism with high vascularity phenotype was more common among squamous cell carcinomas (p  =  .024). Other non-small cell lung carcinoma tumor types demonstrated a high prevalence of the high metabolism with low vascularity phenotype (p  =  .028). We show that tumor subtypes have different vascular-metabolic associations, which can be helpful clinically in managing lung cancer patients to hone targeted therapy. PMID:22954179

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

    NASA Astrophysics Data System (ADS)

    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

  7. Neuroanatomy of cranial computed tomography

    SciTech Connect

    Kretschmann, H.J.; Weinrich, W.

    1985-01-01

    Based on the fundamental structures visualized by means of computed tomography, the authors present the functional systems which are relevant in neurology by means of axial cross-sections. All drawings were prepared from original preparations by means of a new technique which is similar to the grey values of X-ray CT and nuclear magnetic resonance tomography. A detailed description is given of the topics of neurofunctional lesions.

  8. On how X-ray (micro) computed tomography on turbidites can help us unravel paleoflow successions, directions and dynamics

    NASA Astrophysics Data System (ADS)

    Van Daele, Maarten; Cnudde, Veerle; Boone, Marijn; Deprez, Maxim; De Batist, Marc

    2016-04-01

    Even though X-ray computed tomography (CT) is becoming an increasingly widespread technique in many disciplines - among which sedimentology -, applications are still scarce in turbidite research. In the past few years we showed that medical X-ray CT scans of sediment cores can provide a wealth of information about turbidites and especially their internal structures. In Aysén fjord (Chile) as well as several Chilean and Alaskan lakes, we showed that sedimentary structures such as ripples can be used to reconstruct flow directions, as they can be visualized in 3D. When sedimentary structures are absent, fabrics (e.g. grain imbrication) can also be used. However, the resolution of medical X-ray CT scans is usually not sufficient to visualize single grains or clasts inside the sediment cores. Therefore, medical X-ray CT scans do not allow the determination of single grain orientations. Recently, however, subsamples of sediment cores from a Swiss and an Alaskan lake were scanned at the Centre for X-ray Tomography (UGCT, Ghent University) to obtain μCT data with a resolution of 2 μm. The data allows to isolate single grains that are larger than medium silt, determine their grain size, orientation, as well as other parameters. However, all these grains with variable parameters will react differently to certain flow conditions. While mud clasts are often imbricated, coarse silt grains seem to be only oriented parallel to the flow direction. Studying more turbidites with different compositions and comparing with results from modelling studies (analogue and numerical), will allow to better understand the relationship between flow direction, flow dynamics and grain orientation (for each type of particle). From such an improved understanding not only turbidite paleoseismology, but also many other research disciplines related to fluid flow and particle deposition will benefit.

  9. Coded aperture computed tomography

    NASA Astrophysics Data System (ADS)

    Choi, Kerkil; Brady, David J.

    2009-08-01

    Diverse physical measurements can be modeled by X-ray transforms. While X-ray tomography is the canonical example, reference structure tomography (RST) and coded aperture snapshot spectral imaging (CASSI) are examples of physically unrelated but mathematically equivalent sensor systems. Historically, most x-ray transform based systems sample continuous distributions and apply analytical inversion processes. On the other hand, RST and CASSI generate discrete multiplexed measurements implemented with coded apertures. This multiplexing of coded measurements allows for compression of measurements from a compressed sensing perspective. Compressed sensing (CS) is a revelation that if the object has a sparse representation in some basis, then a certain number, but typically much less than what is prescribed by Shannon's sampling rate, of random projections captures enough information for a highly accurate reconstruction of the object. This paper investigates the role of coded apertures in x-ray transform measurement systems (XTMs) in terms of data efficiency and reconstruction fidelity from a CS perspective. To conduct this, we construct a unified analysis using RST and CASSI measurement models. Also, we propose a novel compressive x-ray tomography measurement scheme which also exploits coding and multiplexing, and hence shares the analysis of the other two XTMs. Using this analysis, we perform a qualitative study on how coded apertures can be exploited to implement physical random projections by "regularizing" the measurement systems. Numerical studies and simulation results demonstrate several examples of the impact of coding.

  10. Development and validation of a segmentation-free polyenergetic algorithm for dynamic perfusion computed tomography.

    PubMed

    Lin, Yuan; Samei, Ehsan

    2016-07-01

    Dynamic perfusion imaging can provide the morphologic details of the scanned organs as well as the dynamic information of blood perfusion. However, due to the polyenergetic property of the x-ray spectra, beam hardening effect results in undesirable artifacts and inaccurate CT values. To address this problem, this study proposes a segmentation-free polyenergetic dynamic perfusion imaging algorithm (pDP) to provide superior perfusion imaging. Dynamic perfusion usually is composed of two phases, i.e., a precontrast phase and a postcontrast phase. In the precontrast phase, the attenuation properties of diverse base materials (e.g., in a thorax perfusion exam, base materials can include lung, fat, breast, soft tissue, bone, and metal implants) can be incorporated to reconstruct artifact-free precontrast images. If patient motions are negligible or can be corrected by registration, the precontrast images can then be employed as a priori information to derive linearized iodine projections from the postcontrast images. With the linearized iodine projections, iodine perfusion maps can be reconstructed directly without the influence of various influential factors, such as iodine location, patient size, x-ray spectrum, and background tissue type. A series of simulations were conducted on a dynamic iodine calibration phantom and a dynamic anthropomorphic thorax phantom to validate the proposed algorithm. The simulations with the dynamic iodine calibration phantom showed that the proposed algorithm could effectively eliminate the beam hardening effect and enable quantitative iodine map reconstruction across various influential factors. The error range of the iodine concentration factors ([Formula: see text]) was reduced from [Formula: see text] for filtered back-projection (FBP) to [Formula: see text] for pDP. The quantitative results of the simulations with the dynamic anthropomorphic thorax phantom indicated that the maximum error of iodine concentrations can be reduced from

  11. Interobserver and Intraobserver Reproducibility with Volume Dynamic Contrast Enhanced Computed Tomography (DCE-CT) in Gastroesophageal Junction Cancer

    PubMed Central

    Lundsgaard Hansen, Martin; Fallentin, Eva; Axelsen, Thomas; Lauridsen, Carsten; Norling, Rikke; Svendsen, Lars Bo; Nielsen, Michael Bachmann

    2016-01-01

    The purpose of this study was to assess inter- and intra-observer reproducibility of three different analytic methods to evaluate quantitative dynamic contrast-enhanced computed tomography (DCE-CT) measures from gastroesophageal junctional cancer. Twenty-five DCE-CT studies with gastroesophageal junction cancer were selected from a previous longitudinal study. Three radiologists independently reviewed all scans, and one repeated the analysis eight months later for intraobserver analysis. Review of the scans consisted of three analysis methods: (I) Four, fixed small sized regions of interest (2-dimensional (2D) fixed ROIs) placed in the tumor periphery, (II) 2-dimensional regions of interest (2D-ROI) along the tumor border in the tumor center, and (III) 3-dimensional volumes of interest (3D-VOI) containing the entire tumor volume. Arterial flow, blood volume and permeability (ktrans) were recorded for each observation. Inter- and intra-observer variability were assessed by Intraclass Correlation Coefficient (ICC) and Bland-Altman statistics. Interobserver ICC was excellent for arterial flow (0.88), for blood volume (0.89) and for permeability (0.91) with 3D-VOI analysis. The 95% limits of agreement were narrower for 3D analysis compared to 2D analysis. Three-dimensional volume DCE-CT analysis of gastroesophageal junction cancer provides higher inter- and intra-observer reproducibility with narrower limits of agreement between readers compared to 2D analysis. PMID:26838804

  12. The use of a dynamic real-time jaw tracking device and cone beam computed tomography simulation

    PubMed Central

    He, Shushu; Kau, Chung How; Liao, Lina; Kinderknecht, Keith; Ow, Andrew; Saleh, Tayem Abou

    2016-01-01

    Background: The aim was to introduce and preliminarily evaluate a new software application, SICAT Function, which can directly combine and merge three-dimensional cone beam computed tomography (CBCT) and electronic SICAT jaw motion tracking (JMT) data. Methods: A detailed description of the methods and dynamic clinical simulation of mandibular movements of a patient are demonstrated. Functional jaw movements on 3 days were recorded by JMT tracking system. The simulation was performed by merging CBCT and JMT data in the software SICAT Function suite. The condylar position simulated by SICAT Function suite was compared with real condyle position showed by a CBCT of the patient. Results: The incisor ranges of functional movements were displayed by JMT tracking system. The visualization of patient-specific mandibular movement including the translation of the condyles was displayed after data merge. The recordings of mandibular movements of the patient were similar on 3 different days. The condylar position simulated by SICAT was coincident with real condyle position by CBCT data with the same amount of mouth opening. Conclusions: The SICAT Function software is a system capable of measuring and visualizing patient-specific jaw movement relative to the patient-specific anatomy of the jaw. Further studies are needed to validate its accuracy and its potential for future use. PMID:27563619

  13. Scale-up of an electrical capacitance tomography sensor for imaging pharmaceutical fluidized beds and validation by computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Wang, Haigang; Yang, Wuqiang

    2011-10-01

    The aim of this research is to apply electrical capacitance tomography (ECT) in pharmaceutical fluidized beds and scale up the application of ECT from a lab-scale fluidized bed to a production-scale fluidized bed. The objective is to optimize the design of the production-scale fluidized bed and to improve the operation efficiency of the fluidization processes. This is the first time that ECT has been scaled up to a production-scale fluidized bed of 1.0 m diameter and batch process capacity of 100 kg in a real industrial environment. With a large-scale fluidized bed in a real industrial environment, some key issues on the ECT sensor design must be addressed. To validate ECT measurement results, a two-phase flow model has been used to simulate the process in a lab-scale and pilot-scale fluidized bed. The key process parameters include solid concentration, average concentration profiles, the frequency spectrum of signal fluctuation obtained by the fast Fourier transfer (FFT) and multi-level wavelet decomposition in the time domain. The results show different hydrodynamic behaviour of fluidized beds of different scales. The time-averaged parameters from ECT and computational fluid dynamics are compared. Future work on the ECT sensor design for large-scale fluidized beds are given in the end of the paper.

  14. In situ flash x-ray high-speed computed tomography for the quantitative analysis of highly dynamic processes

    NASA Astrophysics Data System (ADS)

    Moser, Stefan; Nau, Siegfried; Salk, Manfred; Thoma, Klaus

    2014-02-01

    The in situ investigation of dynamic events, ranging from car crash to ballistics, often is key to the understanding of dynamic material behavior. In many cases the important processes and interactions happen on the scale of milli- to microseconds at speeds of 1000 m s-1 or more. Often, 3D information is necessary to fully capture and analyze all relevant effects. High-speed 3D-visualization techniques are thus required for the in situ analysis. 3D-capable optical high-speed methods often are impaired by luminous effects and dust, while flash x-ray based methods usually deliver only 2D data. In this paper, a novel 3D-capable flash x-ray based method, in situ flash x-ray high-speed computed tomography is presented. The method is capable of producing 3D reconstructions of high-speed processes based on an undersampled dataset consisting of only a few (typically 3 to 6) x-ray projections. The major challenges are identified, discussed and the chosen solution outlined. The application is illustrated with an exemplary application of a 1000 m s-1 high-speed impact event on the scale of microseconds. A quantitative analysis of the in situ measurement of the material fragments with a 3D reconstruction with 1 mm voxel size is presented and the results are discussed. The results show that the HSCT method allows gaining valuable visual and quantitative mechanical information for the understanding and interpretation of high-speed events.

  15. Infection Dynamics and Response to Chemotherapy in a Rabbit Model of Tuberculosis using [18F]2-Fluoro-Deoxy-d-Glucose Positron Emission Tomography and Computed Tomography

    PubMed Central

    Via, Laura E.; Schimel, Dan; Weiner, Danielle M.; Dartois, Veronique; Dayao, Emmanuel; Cai, Ying; Yoon, Young-Soon; Dreher, Matthew R.; Kastenmayer, Robin J.; Laymon, Charles M.; Carny, J. Eoin; Flynn, JoAnne L.; Herscovitch, Peter

    2012-01-01

    With a host of new antitubercular chemotherapeutics in development, methods to assess the activity of these agents beyond mouse efficacy are needed to prioritize combinations for clinical trials. Lesions in Mycobacterium tuberculosis-infected rabbits are hypoxic, with histopathologic features that closely resemble those of human tuberculous lesions. Using [18F]2-fluoro-deoxy-d-glucose ([18F]FDG) positron emission tomography–computed tomography (PET-CT) imaging, we studied the dynamics of tuberculosis infection in rabbits, revealing an initial inflammatory response followed by a consolidative chronic disease. Five weeks after infection, as much as 23% of total lung volume was abnormal, but this was contained and to some extent reversed naturally by 9 weeks. During development of this chronic state, individual lesions in the same animal had very different fates, ranging from complete resolution to significant progression. Lesions that remained through the initial stage showed an increase in volume and tissue density over time by CT. Initiation of chemotherapy using either isoniazid (INH) or rifampin (RIF) during chronic infection reduced bacterial load with quantitative changes in [18F]FDG uptake, lesion density and total lesion volume measured by CT. The [18F]FDG PET uptake in lesions was significantly reduced with as little as 1 week of treatment, while the volume and density of lesions changed more slowly. The results from this study suggest that rabbits may be a useful surrogate species for evaluating novel chemotherapies and understanding changes in both PET and CT scans in human clinical trials. PMID:22687508

  16. Computed tomography:the details.

    SciTech Connect

    Doerry, Armin Walter

    2007-07-01

    Computed Tomography (CT) is a well established technique, particularly in medical imaging, but also applied in Synthetic Aperture Radar (SAR) imaging. Basic CT imaging via back-projection is treated in many texts, but often with insufficient detail to appreciate subtleties such as the role of non-uniform sampling densities. Herein are given some details often neglected in many texts.

  17. Atlas of Computed Tomography Variants

    SciTech Connect

    Kuhns, L.R.; Seeger, J.

    1983-01-01

    Atlas of Computed Tomography Variants is unique in that, while others of its kind may include plain film, roentgen variants, it concentrates solely on CT images of variants which may simulate disease. Organized into four regions, it presents dicussions covering CT variants of the skull, neck and spine; thorax; abdomen; and extremities-featuring a section on the head.

  18. X-ray Computed Tomography.

    ERIC Educational Resources Information Center

    Michael, Greg

    2001-01-01

    Describes computed tomography (CT), a medical imaging technique that produces images of transaxial planes through the human body. A CT image is reconstructed mathematically from a large number of one-dimensional projections of a plane. The technique is used in radiological examinations and radiotherapy treatment planning. (Author/MM)

  19. Computed tomography of intramuscular myxoma

    SciTech Connect

    Ekelund, L.; Herrlin, K.; Rydholm, A.

    1982-11-01

    Computed tomography (CT) was performed in seven patients with intramuscular myxoma. All lesions were well demarcated, of homogeneous appearance and attenuation values ranging from 10 to 60 (HU). The tumor size, as estimated at CT, correlated well with the size of the surgical specimen, which is in contrast to the findings in some high grade malignant sarcomas.

  20. Viewing Welds By Computer Tomography

    NASA Technical Reports Server (NTRS)

    Pascua, Antonio G.; Roy, Jagatjit

    1990-01-01

    Computer tomography system used to inspect welds for root penetration. Source illuminates rotating welded part with fan-shaped beam of x rays or gamma rays. Detectors in circular array on opposite side of part intercept beam and convert it into electrical signals. Computer processes signals into image of cross section of weld. Image displayed on video monitor. System offers only nondestructive way to check penetration from outside when inner surfaces inaccessible.

  1. Optical tracking of contrast medium bolus to optimize bolus shape and timing in dynamic computed tomography

    NASA Astrophysics Data System (ADS)

    Eisa, Fabian; Brauweiler, Robert; Peetz, Alexander; Hupfer, Martin; Nowak, Tristan; Kalender, Willi A.

    2012-05-01

    One of the biggest challenges in dynamic contrast-enhanced CT is the optimal synchronization of scan start and duration with contrast medium administration in order to optimize image contrast and to reduce the amount of contrast medium. We present a new optically based approach, which was developed to investigate and optimize bolus timing and shape. The time-concentration curve of an intravenously injected test bolus of a dye is measured in peripheral vessels with an optical sensor prior to the diagnostic CT scan. The curves can be used to assess bolus shapes as a function of injection protocols and to determine contrast medium arrival times. Preliminary results for phantom and animal experiments showed the expected linear behavior between dye concentration and absorption. The kinetics of the dye was compared to iodinated contrast medium and was found to be in good agreement. The contrast enhancement curves were reliably detected in three mice with individual bolus shapes and delay times of 2.1, 3.5 and 6.1 s, respectively. The optical sensor appears to be a promising approach to optimize injection protocols and contrast enhancement timing and is applicable to all modalities without implying any additional radiation dose. Clinical tests are still necessary.

  2. Cardiac Computed Tomography (Multidetector CT, or MDCT)

    MedlinePlus

    ... High Blood Pressure Tools & Resources Stroke More Cardiac Computed Tomography (Multidetector CT, or MDCT) Updated:Sep 3,2015 ... facts MDCT is a very fast type of computed tomography (CT) scan. MDCT creates pictures of the healthy ...

  3. Radiation protection issues in dynamic contrast-enhanced (perfusion) computed tomography.

    PubMed

    Brix, Gunnar; Lechel, Ursula; Nekolla, Elke; Griebel, Jürgen; Becker, Christoph

    2015-12-01

    Dynamic contrast-enhanced (DCE) CT studies are increasingly used in both medical care and clinical trials to improve diagnosis and therapy management of the most common life-threatening diseases: stroke, coronary artery disease and cancer. It is thus the aim of this review to briefly summarize the current knowledge on deterministic and stochastic radiation effects relevant for patient protection, to present the essential concepts for determining radiation doses and risks associated with DCE-CT studies as well as representative results, and to discuss relevant aspects to be considered in the process of justification and optimization of these studies. For three default DCE-CT protocols implemented at a latest-generation CT system for cerebral, myocardial and cancer perfusion imaging, absorbed doses were measured by thermoluminescent dosimeters at an anthropomorphic body phantom and compared with thresholds for harmful (deterministic) tissue reactions. To characterize stochastic radiation risks of patients from these studies, life-time attributable cancer risks (LAR) were estimated using sex-, age-, and organ-specific risk models based on the hypothesis of a linear non-threshold dose-response relationship. For the brain, heart and pelvic cancer studies considered, local absorbed doses in the imaging field were about 100-190 mGy (total CTDI(vol), 200 mGy), 15-30 mGy (16 mGy) and 80-270 mGy (140 mGy), respectively. According to a recent publication of the International Commission on Radiological Protection (ICRP Publication 118, 2012), harmful tissue reactions of the cerebro- and cardiovascular systems as well as of the lenses of the eye become increasingly important at radiation doses of more than 0.5 Gy. The LARs estimated for the investigated cerebral and myocardial DCE-CT scenarios are less than 0.07% for males and 0.1% for females at an age of exposure of 40 years. For the considered tumor location and protocol, the corresponding LARs are more than 6 times as high

  4. Delayed uptake and washout of contrast in non-viable infarcted myocardium shown with dynamic computed tomography

    PubMed Central

    Laugesen, Sofie; Agger, Peter; Hønge, Jesper; Smerup, Morten; Udholm, Nichlas; Bøtker, Hans Erik; Bøttcher, Morten

    2014-01-01

    Background Assessment of ischemic but potentially viable myocardium plays an important role in the planning of coronary revascularization. Until now SPECT, PET, and MRI have been used to identify viable myocardium. Computed tomography (CT) is increasingly used to diagnose coronary atherosclerosis. Objective To evaluate the feasibility of CT enhancement as a viability marker by investigating myocardial contrast distribution over time in pigs with experimentally induced antero-septal myocardial infarctions. Methods Twelve pigs were subjected to 60 min of balloon occlusion of the left anterior descending artery, followed by removal of the balloon and reperfusion. Four pigs died due to refractory ventricular fibrillation. After 6 weeks, dynamic cardiac CT was performed assessing both wall motion and contrast attenuation. Measurements of attenuation values in Hounsfield units (HU) in the infarct zone and the normal lateral wall were performed at 20 s, and 1, 3, 5, 8 and 12 min after contrast injection. Results We found highly significant differences in attenuation values between the two zones at all-time points except t =1 min (ANOVA P=0.85). The normal myocardium showed higher uptake- and washout-rates of contrast than the infarct zone (84±15 vs. 58±8 at 20 s, P=0.0001 and 27±12 vs. 81±13 at 12 min, P=0.0001). Specifically, the ratio between early (20 s) and late (12 min) uptake is a valid marker of viable myocardium. In all animals this ration was above one in the normal zone and below one in the infarct zone. Conclusions Delayed infarct related uptake and washout of contrast shows promise for future clinical application of CT in a combined assessment of coronary atherosclerosis and myocardial viability. PMID:25414821

  5. Using Micro-Computed Tomography to Evaluate the Dynamics of Orthodontically Induced Root Resorption Repair in a Rat Model

    PubMed Central

    Yang, Fengxue; Wei, Shicheng; Dai, Hongwei

    2016-01-01

    Objective To observe dynamic changes in root resorption repair, tooth movement relapse and alveolar bone microstructure following the application of orthodontic force. Materials and Methods Forces of 20 g, 50 g or 100 g were delivered to the left maxillary first molars of fifteen 10-week-old rats for 14 days. Each rat was subjected to micro-computed tomography scanning at 0, 3, 7, 10, 14, 28 and 42 days after force removal. The root resorption crater volume, tooth movement relapse and alveolar bone microarchitecture were measured at each time point. Results From day 3 to day 14, the root resorption volume decreased significantly in each group. In the 20-g force group, the root resorption volume gradually stabilized after 14 days, whereas in the 50-g and 100-g force groups, it stabilized after 28 days. In all groups, tooth movement relapsed significantly from day 0 to day 14 and then remained stable. From day 3 to day 10, the 20-g group exhibited faster relapse than the 50-g and 100-g groups. In all groups, the structure model index and trabecular separation decreased slowly from day 0 to day 10 and eventually stabilized. Trabecular number increased slowly from day 0 to day 7 and then stabilized. Conclusions The initial stage of root resorption repair did not change significantly and was followed by a dramatic repair period before stabilizing. The most serious tooth movement relapse occurred immediately after the appliance was removed, and then the tooth completely returned to the original position. PMID:26930605

  6. Positron emission tomography/computed tomography.

    PubMed

    Townsend, David W

    2008-05-01

    Accurate anatomical localization of functional abnormalities obtained with the use of positron emission tomography (PET) is known to be problematic. Although tracers such as (18)F-fluorodeoxyglucose ((18)F-FDG) visualize certain normal anatomical structures, the spatial resolution is generally inadequate for accurate anatomic localization of pathology. Combining PET with a high-resolution anatomical imaging modality such as computed tomography (CT) can resolve the localization issue as long as the images from the two modalities are accurately coregistered. However, software-based registration techniques have difficulty accounting for differences in patient positioning and involuntary movement of internal organs, often necessitating labor-intensive nonlinear mapping that may not converge to a satisfactory result. Acquiring both CT and PET images in the same scanner obviates the need for software registration and routinely provides accurately aligned images of anatomy and function in a single scan. A CT scanner positioned in line with a PET scanner and with a common patient couch and operating console has provided a practical solution to anatomical and functional image registration. Axial translation of the couch between the 2 modalities enables both CT and PET data to be acquired during a single imaging session. In addition, the CT images can be used to generate essentially noiseless attenuation correction factors for the PET emission data. By minimizing patient movement between the CT and PET scans and accounting for the axial separation of the two modalities, accurately registered anatomical and functional images can be obtained. Since the introduction of the first PET/CT prototype more than 6 years ago, numerous patients with cancer have been scanned on commercial PET/CT devices worldwide. The commercial designs feature multidetector spiral CT and high-performance PET components. Experience has demonstrated an increased level of accuracy and confidence in the

  7. Cranial computed tomography and MRI

    SciTech Connect

    Lee, S.H.; Rao, K.C.V.G.

    1987-01-01

    This book appears to be a hybrid between an atlas and a text. The second edition attempts to depict the current status of both computed tomography (CT) and magnetic resonance (MR) imaging in neuroradiology. Although only the final chapter of the book is completely devoted to cranial MR imaging, MR images are scattered throughout various other chapters. There is coverage of the major anatomic and pathophysiologic entities. There are 17 chapters with images, tables, and diagrams.

  8. Computed tomography of gynecologic diseases

    SciTech Connect

    Gross, B.H.; Moss, A.A.; Mihara, K.; Goldberg, H.I.; Glazer, G.M.

    1983-10-01

    Although computed tomography (CT) provides superb images of all areas of the body, sonography, because of its lack of ionizing radiation and its real-time and multiplanar capacities, has become the preferred initial method of evaluating the female pelvis. This has resulted in a relative paucity of information in the literature concerning CT features of benign pelvic disorders in particular and prompted the authors to review our experience with third-generation CT scanning of the uterus and ovaries.

  9. Hermaphroditism demonstrated by computed tomography

    SciTech Connect

    Gale, M.E.

    1983-07-01

    The categorization of disorders of gender differentiation is based on chromosome analysis, physical examination, gonadal histology, and endocrine evaluation. In most cases of hermaphroditism, radiologic studies have been limited to assessment of associated urinary tract anomalies before surgical revconstruction. Noninvasive evaluation with computed tomography (CT) or sonography is potentially useful for investigation of internal pelvic anatomy in these cases. A case report of a 65-year-old man is reported. (KRM)

  10. Computed Tomography software and standards

    SciTech Connect

    Azevedo, S.G.; Martz, H.E.; Skeate, M.F.; Schneberk, D.J.; Roberson, G.P.

    1990-02-20

    This document establishes the software design, nomenclature, and conventions for industrial Computed Tomography (CT) used in the Nondestructive Evaluation Section at Lawrence Livermore National Laboratory. It is mainly a users guide to the technical use of the CT computer codes, but also presents a proposed standard for describing CT experiments and reconstructions. Each part of this document specifies different aspects of the CT software organization. A set of tables at the end describes the CT parameters of interest in our project. 4 refs., 6 figs., 1 tab.

  11. Computed tomography of facial fractures.

    PubMed

    Furlow, Bryant

    2014-01-01

    Facial skeletal fractures are common, potentially serious, and frequently associated with other life-threatening conditions, such as traumatic brain injuries. Facial fractures can be simple or complex and sometimes involve serious complications. Computed tomography has revolutionized the rapid and precise assessment of craniofacial and neck fractures in patients with severe facial trauma. This article introduces readers to the epidemiology, skeletal anatomy and biomechanics, complications, and diagnostic imaging of facial fractures. In addition, this article describes efforts to develop and validate a quantitative scoring system for facial fracture severity and reviews treatment strategies for facial skeletal fractures. PMID:24806070

  12. Computed Tomography Imaging in Oncology.

    PubMed

    Forrest, Lisa J

    2016-05-01

    Computed tomography (CT) imaging has become the mainstay of oncology, providing accurate tumor staging and follow-up imaging to monitor treatment response. Presurgical evaluation of tumors is becoming commonplace and guides surgeons as to the extent and whether complete tumor resection is possible. CT imaging plays a crucial role in radiotherapy treatment planning. CT imaging in oncology has become ubiquitous in veterinary medicine because of increased availability of this imaging modality. This article focuses on CT cancer staging in veterinary oncology, CT imaging for surgical planning, and advances in CT simulation for radiation therapy planning. PMID:26851976

  13. Computed tomography of parosteal osteosarcoma

    SciTech Connect

    Hudson, T.M.; Springfield, D.S.; Benjamin, M.; Bertoni, F.; Present, D.A.

    1985-05-01

    Twelve patients with parosteal osteosarcomas were evaluated by computed tomography (CT). CT accurately defined the extent of the tumors for purposes of surgical planning, although tumor bone often could not be distinguished from thickened host bone. Nine tumors invaded the medullary cavity, a feature that implies a poorer prognosis when the tumor also contains high-grade areas. Six CT studies accurately detected the medullary invasion, but three did not. Lucent areas within dense tumors contained either benign tissue or high- or low-grade tumor; CT did not differentiate among these different tissues. CT also did not reveal small satellite nodules of tumor beyond the main tumor mass.

  14. Dynamic enhancement patterns of intrahepatic cholangiocarcinoma in cirrhosis on contrast-enhanced computed tomography: risk of misdiagnosis as hepatocellular carcinoma

    PubMed Central

    Li, Rui; Cai, Ping; Ma, Kuan-sheng; Ding, Shi-Yi; Guo, De-Yu; Yan, Xiao-Chu

    2016-01-01

    This study aimed to assess the features of intrahepatic cholangiocarcinoma (ICC) at computerized tomography (CT) and verify the risk of misdiagnosis of ICC as hepatocellular carcinoma (HCC) in cirrhosis. CT appearances of 98 histologically confirmed ICC nodules from 84 cirrhotic patients were retrospectively reviewed, taking into consideration the pattern and dynamic contrast uptake during the arterial, portal venous and delayed phases. During the arterial phase, 53 nodules (54.1%) showed peripheral rim-like enhancement, 35 (35.7%) hyperenhancement, 9 (9.2%) hypoenhancement and 1 (1.0%) isoenhancement. The ICC nodules showed heterogeneous dynamic contrast patterns, being progressive enhancement in 35 nodules (35.7%), stable enhancement in 28 nodules (28.6%), wash-in and wash-out pattern in 15 nodules (15.3%) and all other enhancement patterns in 20 nodules (20.4%). There were no significant differences in the dynamic vascular patterns of ICC according to nodule size (p > 0.05). ICC in cirrhosis has varied enhancement patterns at contrast-enhanced multiphase multidetector CT. Though the majority of ICC did not display typical radiological hallmarks of HCC, if dynamic CT scan was used as the sole modality for the non-invasive diagnosis of nodules in cirrhosis, the risk of misdiagnosis of ICC for HCC is not negligible. PMID:27226026

  15. Dynamic enhancement patterns of intrahepatic cholangiocarcinoma in cirrhosis on contrast-enhanced computed tomography: risk of misdiagnosis as hepatocellular carcinoma.

    PubMed

    Li, Rui; Cai, Ping; Ma, Kuan-Sheng; Ding, Shi-Yi; Guo, De-Yu; Yan, Xiao-Chu

    2016-01-01

    This study aimed to assess the features of intrahepatic cholangiocarcinoma (ICC) at computerized tomography (CT) and verify the risk of misdiagnosis of ICC as hepatocellular carcinoma (HCC) in cirrhosis. CT appearances of 98 histologically confirmed ICC nodules from 84 cirrhotic patients were retrospectively reviewed, taking into consideration the pattern and dynamic contrast uptake during the arterial, portal venous and delayed phases. During the arterial phase, 53 nodules (54.1%) showed peripheral rim-like enhancement, 35 (35.7%) hyperenhancement, 9 (9.2%) hypoenhancement and 1 (1.0%) isoenhancement. The ICC nodules showed heterogeneous dynamic contrast patterns, being progressive enhancement in 35 nodules (35.7%), stable enhancement in 28 nodules (28.6%), wash-in and wash-out pattern in 15 nodules (15.3%) and all other enhancement patterns in 20 nodules (20.4%). There were no significant differences in the dynamic vascular patterns of ICC according to nodule size (p > 0.05). ICC in cirrhosis has varied enhancement patterns at contrast-enhanced multiphase multidetector CT. Though the majority of ICC did not display typical radiological hallmarks of HCC, if dynamic CT scan was used as the sole modality for the non-invasive diagnosis of nodules in cirrhosis, the risk of misdiagnosis of ICC for HCC is not negligible. PMID:27226026

  16. Computer tomography imaging of fast plasmachemical processes

    SciTech Connect

    Denisova, N. V.; Katsnelson, S. S.; Pozdnyakov, G. A.

    2007-11-15

    Results are presented from experimental studies of the interaction of a high-enthalpy methane plasma bunch with gaseous methane in a plasmachemical reactor. The interaction of the plasma flow with the rest gas was visualized by using streak imaging and computer tomography. Tomography was applied for the first time to reconstruct the spatial structure and dynamics of the reagent zones in the microsecond range by the maximum entropy method. The reagent zones were identified from the emission of atomic hydrogen (the H{sub {alpha}} line) and molecular carbon (the Swan bands). The spatiotemporal behavior of the reagent zones was determined, and their relation to the shock-wave structure of the plasma flow was examined.

  17. Value of two-phase dynamic multidetector computed tomography in differential diagnosis of post-inflammatory strictures from esophageal cancer

    PubMed Central

    Karmazanovsky, Grigory G; Buryakina, Svetlana A; Kondratiev, Evgeny V; Yang, Qin; Ruchkin, Dmitry V; Kalinin, Dmitry V

    2015-01-01

    AIM: To characterize the computed tomography (CT) findings in patients with post-inflammatory esophageal strictures (corrosive and peptic) and reveal the optimal scanning phase protocols for distinguishing post-inflammatory esophageal stricture and esophageal cancer. METHODS: Sixty-five patients with esophageal strictures of different etiology were included in this study: 24 patients with 27 histopathologically confirmed corrosive strictures, 10 patients with 12 peptic strictures and 31 patients with esophageal cancer were evaluated with a two-phase dynamic contrast-enhanced MDCT. Arterial and venous phases at 10 and 35 s after the attenuation of 200 HU were obtained at the descending aorta, with a delayed phase at 6-8 min after the start of injection of contrast media. For qualitative analysis, CT scans of benign strictures were reviewed for the presence/absence of the following features: “target sign”, luminal mass, homogeneity of contrast medium uptake, concentric wall thickening, conically shaped suprastenotic dilatation, smooth boundaries of stenosis and smooth mucous membrane at the transition to stenosis, which were compared with a control group of 31 patients who had esophageal cancer. The quantitative analysis included densitometric parameter acquisition using regions-of-interest measurement of the zone of stenosis and normal esophageal wall and the difference between those measurements (ΔCT) at all phases of bolus contrast enhancement. Esophageal wall thickening, length of esophageal wall thickening and size of the regional lymph nodes were also evaluated. RESULTS: The presence of a concentric esophageal wall, conically shaped suprastenotic dilatation, smooth upper and lower boundaries, “target sign” and smooth mucous membrane at the transition to stenosis were suggestive of a benign cause, with sensitivities of 92.31%, 87.17%, 94.87%, 76.92% and 82.05%, respectively, and specificities of 70.96%, 89.66%, 80.65%, 96.77% and 93.55%, respectively

  18. Single photon emission computed tomography

    SciTech Connect

    Piez, C.W. Jr.; Holman, B.L.

    1985-07-01

    Single photon emission computed tomography (SPECT) is becoming an increasingly important part of routine clinical nuclear medicine. By providing tomographic reconstructions in multiple planes through the patient, SPECT expands the clinical applications in nuclear medicine as well as providing better contrast, edge definition and separation of target from background activities. Imaging techniques have been developed for the evaluation of regional cerebral blood flow using radiolabeled amines. Thus, cerebral functional imaging can be used in the diagnosis of acute cerebral infarction, cerebral vascular disease, dementia and epilepsy. SPECT plays a complementary role in the evaluation of coronary artery disease, particularly when it is coupled with thallium-201 and exercise testing. SPECT extends our diagnostic capabilities in additional areas, such as liver and bone scintigraphy as well as tumor imaging with gallium-67.

  19. Computed tomography of calcaneal fractures

    SciTech Connect

    Heger, L.; Wulff, K.; Seddiqi, M.S.A.

    1985-07-01

    Computed tomography (CT) of 25 fractured calcanei was performed to investigate the potential of CT in evaluating the pattern and biomechanics of these fractures. The characteristic findings of typical fractures are presented, including the number and type of principal fragments, size and dislocation of the sustentacular fragment, and involvement of the anterior and posterior facets of the subtalar joint. In 17 cases, the calcaneus consisted of four or more fragments. Furthermore, in 17 cases the sustentacular fragment included all or part of the posterior facet joint. In 18 of the 25 cases, the sustentacular fragment was displaced. It is concluded that well performed CT is an invaluable adjunct in understanding the fracture mechanism and in detecting pain-provoking impingement between the fibular malleolus and the tuberosity fragment.

  20. Computed tomography of splenic trauma

    SciTech Connect

    Jeffrey, R.B.; Laing, F.C.; Federle, M.P.; Goodman, P.C.

    1981-12-01

    Fifty patients with abdominal trauma and possible splenic injury were evaluated by computed tomography (CT). CT correctly diagnosed 21 of 22 surgically proved traumatic sesions of the spleen (96%). Twenty-seven patients had no evidence of splenic injury. This was confirmed at operation in 1 patient and clinical follow-up in 26. There were one false negative and one false positive. In 5 patients (10%), CT demonstrated other clinically significant lesions, including hepatic or renal lacerations in 3 and large retroperitoneal hematomas in 2. In adolescents and adults, CT is an accurate, noninvasive method of rapidly diagnosing splenic trauma and associated injuries. Further experience is needed to assess its usefulness in evaluating splenic injuries in infants and small children.

  1. Computed tomography of cryogenic cells

    SciTech Connect

    Schneider, Gerd; Anderson, E.; Vogt, S.; Knochel, C.; Weiss, D.; LeGros, M.; Larabell, C.

    2001-08-30

    Due to the short wavelengths of X-rays and low numerical aperture of the Fresnel zone plates used as X-ray objectives, the depth of field is several microns. Within the focal depth, imaging a thick specimen is to a good approximation equivalent to projecting the specimen absorption. Therefore, computed tomography based on a tilt series of X-ray microscopic images can be used to reconstruct the local linear absorption coefficient and image the three-dimensional specimen structure. To preserve the structural integrity of biological objects during image acquisition, microscopy is performed at cryogenic temperatures. Tomography based on X-ray microscopic images was applied to study the distribution of male specific lethal 1 (MSL-1), a nuclear protein involved in dosage compensation in Drosophila melanogaster, which ensures that males with single X chromosome have the same amount of most X-linked gene products as females with two X chromosomes. Tomographic reconstructions of X-ray microscopic images were used to compute the local three-dimensional linear absorption coefficient revealing the arrangement of internal structures of Drosophila melanogaster cells. Combined with labelling techniques, nanotomography is a new technique to study the 3D distribution of selected proteins inside whole cells. We want to improve this technique with respect to resolution and specimen preparation. The resolution in the reconstruction can be significantly improved by reducing the angular step size to collect more viewing angles, which requires an automated data acquisition. In addition, fast-freezing with liquid ethane instead of cryogenic He gas will be applied to improve the vitrification of the hydrated samples. We also plan to apply cryo X-ray nanotomography in order to study different types of cells and their nuclear protein distributions.

  2. Implementation of a Phase Detection Algorithm for Dynamic Cardiac Computed Tomography Analysis Based on Time Dependent Contrast Agent Distribution

    PubMed Central

    Kendziorra, Carsten; Meyer, Henning; Dewey, Marc

    2014-01-01

    This paper presents a phase detection algorithm for four-dimensional (4D) cardiac computed tomography (CT) analysis. The algorithm detects a phase, i.e. a specific three-dimensional (3D) image out of several time-distributed 3D images, with high contrast in the left ventricle and low contrast in the right ventricle. The purpose is to use the automatically detected phase in an existing algorithm that automatically aligns the images along the heart axis. Decision making is based on the contrast agent distribution over time. It was implemented in KardioPerfusion – a software framework currently being developed for 4D CT myocardial perfusion analysis. Agreement of the phase detection algorithm with two reference readers was 97% (95% CI: 82–100%). Mean duration for detection was 0.020 s (95% CI: 0.018–0.022 s), which was times less than the readers needed (s, ). Thus, this algorithm is an accurate and fast tool that can improve work flow of clinical examinations. PMID:25545863

  3. [Computed tomography and cranial paleoanthropology].

    PubMed

    Cabanis, Emmanuel Alain; Badawi-Fayad, Jackie; Iba-Zizen, Marie-Thérèse; Istoc, Adrian; de Lumley, Henry; de Lumley, Marie-Antoinette; Coppens, Yves

    2007-06-01

    Since its invention in 1972, computed tomography (C.T.) has significantly evolved. With the advent of multi-slice detectors (500 times more sensitive than conventional radiography) and high-powered computer programs, medical applications have also improved. CT is now contributing to paleoanthropological research. Its non-destructive nature is the biggest advantage for studying fossil skulls. The second advantage is the possibility of image analysis, storage, and transmission. Potential disadvantages include the possible loss of files and the need to keep up with rapid technological advances. Our experience since the late 1970s, and a recent PhD thesis, led us to describe routine applications of this method. The main contributions of CT to cranial paleoanthropology are five-fold: --Numerical anatomy with rapid acquisition and high spatial resolution (helicoidal and multidetector CT) offering digital storage and stereolithography (3D printing). --Numerical biometry (2D and 3D) can be used to create "normograms" such as the 3D craniofacial reference model used in maxillofacial surgery. --Numerical analysis offers thorough characterization of the specimen and its state of conservation and/or restoration. --From "surrealism" to virtual imaging, anatomical structures can be reconstructed, providing access to hidden or dangerous zones. --The time dimension (4D imaging) confers movement and the possibility for endoscopic simulation and internal navigation (see Iconography). New technical developments will focus on data processing and networking. It remains our duty to deal respectfully with human fossils. PMID:18402165

  4. Radiological protection in computed tomography and cone beam computed tomography.

    PubMed

    Rehani, M M

    2015-06-01

    The International Commission on Radiological Protection (ICRP) has sustained interest in radiological protection in computed tomography (CT), and ICRP Publications 87 and 102 focused on the management of patient doses in CT and multi-detector CT (MDCT) respectively. ICRP forecasted and 'sounded the alarm' on increasing patient doses in CT, and recommended actions for manufacturers and users. One of the approaches was that safety is best achieved when it is built into the machine, rather than left as a matter of choice for users. In view of upcoming challenges posed by newer systems that use cone beam geometry for CT (CBCT), and their widened usage, often by untrained users, a new ICRP task group has been working on radiological protection issues in CBCT. Some of the issues identified by the task group are: lack of standardisation of dosimetry in CBCT; the false belief within the medical and dental community that CBCT is a 'light', low-dose CT whereas mobile CBCT units and newer applications, particularly C-arm CT in interventional procedures, involve higher doses; lack of training in radiological protection among clinical users; and lack of dose information and tracking in many applications. This paper provides a summary of approaches used in CT and MDCT, and preliminary information regarding work just published for radiological protection in CBCT. PMID:25816279

  5. Fundamentals and recent advances in X-ray micro computed tomography (microCT) applied on thermal-fluid dynamics and multiphase flows

    NASA Astrophysics Data System (ADS)

    Santini, Maurizio

    2015-11-01

    X-ray computed tomography (CT) is a well-known technique nowadays, since its first practical application by Sir. G. Hounsfield (Nobel price for medicine 1979) has continually benefited from optimising improvements, especially in medical applications. Indeed, also application of CT in various engineering research fields provides fundamental informations on a wide range of applications, considering that the technique is not destructive, allowing 3D visualization without perturbation of the analysed material. Nowadays, it is technologically possible to design and realize an equipment that achieve a micrometric resolution and even improve the sensibility in revealing differences in materials having very radiotransparency, allowing i.e. to distinguish between different fluids (with different density) or states of matter (like with two-phase flows). At the University of Bergamo, a prototype of an X-ray microCT system was developed since 2008, so being fully operative from 2012, with specific customizations for investigations in thermal-fluid dynamics and multiphase flow researches. A technical session held at the UIT International Conference in L'Aquila (Italy), at which this paper is referring, has presented some microCT fundamentals, to allow the audience to gain basics to follow the “fil-rouge” that links all the instrumentation developments, till the recent applications. Hereinafter are reported some applications currently developed at Bergamo University at the X-ray computed micro-tomography laboratory.

  6. Mantle dynamics and seismic tomography.

    PubMed

    Tanimoto, T; Lay, T

    2000-11-01

    Three-dimensional imaging of the Earth's interior, called seismic tomography, has achieved breakthrough advances in the last two decades, revealing fundamental geodynamical processes throughout the Earth's mantle and core. Convective circulation of the entire mantle is taking place, with subducted oceanic lithosphere sinking into the lower mantle, overcoming the resistance to penetration provided by the phase boundary near 650-km depth that separates the upper and lower mantle. The boundary layer at the base of the mantle has been revealed to have complex structure, involving local stratification, extensive structural anisotropy, and massive regions of partial melt. The Earth's high Rayleigh number convective regime now is recognized to be much more interesting and complex than suggested by textbook cartoons, and continued advances in seismic tomography, geodynamical modeling, and high-pressure-high-temperature mineral physics will be needed to fully quantify the complex dynamics of our planet's interior. PMID:11035784

  7. Quantitative computed tomography of bone.

    PubMed

    Rüegsegger, P; Stebler, B; Dambacher, M

    1982-07-01

    Computed tomography (CT) is well accepted as an imaging procedure, but comparatively little effort has been made to utilize the potential capability of CT to quantify tissue densities and composition. There are two reasons for this. First, precision and accuracy of quantification are limited by nonlinear effects. These effects are nonlocal and are object and scanner dependent. Second, intraindividual and interindividual variations of tissue compositions are considerable. Single energy measurements require restrictive assumptions on tissue compositions. The diagnosis and treatment monitoring of osteopenic bone diseases with low-dose CT is given as an example of a successful application of quantitative CT. With a special-purpose CT system and an analytic procedure for the quantification of bone at peripheral measuring sites, longitudinal examinations were performed. Low-dose quantitative CT permitted quantification, on an individual basis, of the bone loss of immobilization osteoporosis on a week-by-week basis. Changes due to postmenopausal osteoporosis are less drastic, and so measurement at intervals of months is adequate. In women after menopause, 3-month intervals were used in evaluating the natural course of osteoporosis and in quantifying the effects of sodium fluoride treatment on trabecular bone. Low-dose quantitative CT has proved to be a sensitive and highly reproducible procedure for the noninvasive evaluation of bone loss or bone accretion. During a disease or therapy, each patient can be evaluated individually. PMID:7121079

  8. Absolute quantification of cerebral blood flow in neurologically normal volunteers: dynamic-susceptibility contrast MRI-perfusion compared with computed tomography (CT)-perfusion.

    PubMed

    Ziegelitz, Doerthe; Starck, Göran; Mikkelsen, Irene K; Tullberg, Mats; Edsbagge, Mikael; Wikkelsö, Carsten; Forssell-Aronson, Eva; Holtås, Stig; Knutsson, Linda

    2009-07-01

    To improve the reproducibility of arterial input function (AIF) registration and absolute cerebral blood flow (CBF) quantification in dynamic-susceptibility MRI-perfusion (MRP) at 1.5T, we rescaled the AIF by use of a venous output function (VOF). We compared CBF estimates of 20 healthy, elderly volunteers, obtained by computed tomography (CT)-perfusion (CTP) and MRP on two consecutive days. MRP, calculated without the AIF correction, did not result in any significant correlation with CTP. The rescaled MRP showed fair to moderate correlation with CTP for the central gray matter (GM) and the whole brain. Our results indicate that the method used for correction of partial volume effects (PVEs) improves MRP experiments by reducing AIF-introduced variance at 1.5T. PMID:19253361

  9. Nondestructive computed tomography for pit inspections

    SciTech Connect

    Martz, H.; Logan, C.; Haskins, J.; Johansson, E.; Perkins, D.; Hernandez, J.M.; Schneberk, D.; Dolan, K.

    1997-02-07

    Objective is to develop new approaches to electronically capture digital radiography and computed tomography images at high x-ray energies to satisfy spatial and contrast requirements for inspection of high-density weapons components.

  10. Interlaced X-ray diffraction computed tomography

    PubMed Central

    Vamvakeros, Antonios; Jacques, Simon D. M.; Di Michiel, Marco; Senecal, Pierre; Middelkoop, Vesna; Cernik, Robert J.; Beale, Andrew M.

    2016-01-01

    An X-ray diffraction computed tomography data-collection strategy that allows, post experiment, a choice between temporal and spatial resolution is reported. This strategy enables time-resolved studies on comparatively short timescales, or alternatively allows for improved spatial resolution if the system under study, or components within it, appear to be unchanging. The application of the method for studying an Mn–Na–W/SiO2 fixed-bed reactor in situ is demonstrated. Additionally, the opportunities to improve the data-collection strategy further, enabling post-collection tuning between statistical, temporal and spatial resolutions, are discussed. In principle, the interlaced scanning approach can also be applied to other pencil-beam tomographic techniques, like X-ray fluorescence computed tomography, X-ray absorption fine structure computed tomography, pair distribution function computed tomography and tomographic scanning transmission X-ray microscopy. PMID:27047305

  11. Single Photon Emission Computed Tomography (SPECT)

    MedlinePlus

    ... High Blood Pressure Tools & Resources Stroke More Single Photon Emission Computed Tomography (SPECT) Updated:Sep 11,2015 ... Persantine) or dobutamine. The tests may take between 2 and 2 1/2 hours. What happens after ...

  12. Computed Tomography For Internal Inspection Of Castings

    NASA Technical Reports Server (NTRS)

    Hanna, Timothy L.

    1995-01-01

    Computed tomography used to detect internal flaws in metal castings before machining and otherwise processing them into finished parts. Saves time and money otherwise wasted on machining and other processing of castings eventually rejected because of internal defects. Knowledge of internal defects gained by use of computed tomography also provides guidance for changes in foundry techniques, procedures, and equipment to minimize defects and reduce costs.

  13. Advanced Computed-Tomography Inspection System

    NASA Technical Reports Server (NTRS)

    Harris, Lowell D.; Gupta, Nand K.; Smith, Charles R.; Bernardi, Richard T.; Moore, John F.; Hediger, Lisa

    1993-01-01

    Advanced Computed Tomography Inspection System (ACTIS) is computed-tomography x-ray apparatus revealing internal structures of objects in wide range of sizes and materials. Three x-ray sources and adjustable scan geometry gives system unprecedented versatility. Gantry contains translation and rotation mechanisms scanning x-ray beam through object inspected. Distance between source and detector towers varied to suit object. System used in such diverse applications as development of new materials, refinement of manufacturing processes, and inspection of components.

  14. Computed tomography of the central nervous system

    SciTech Connect

    Bentson, J.R.

    1982-01-01

    The objective of this chapter is to review the most pertinent articles published during the past year on the subject of computed tomography of the central nervous system. The chapter contains sections on pediatric computed tomography, and on the diagnostic use of CT in white matter disease, in infectious disease, for intracranial aneurysms, trauma, and intracranial tumors. Metrizamide flow studies and contrast enhancement are also examined. (KRM)

  15. Computed Tomography of Pancreatitis and Pancreatic Cancer.

    PubMed

    Furlow, Bryant

    2015-01-01

    Pancreatic disease often is asymptomatic until tissue damage and complications occur or until malignancies have reached advanced stages and have metastasized. Contrast-enhanced multidetector computed tomography plays a central role in diagnosing, staging, and treatment planning for pancreatitis and pancreatic cancer. This article introduces the functional anatomy of the pancreas and common bile duct and the epidemiology, pathobiology, and computed tomography imaging of pancreatitis, calculi, and pancreatic cancer. PMID:26199449

  16. Experimental polyethylene-hydroxyapatite carrier-based endodontic system: an in vitro study on dynamic thermomechanical properties, sealing ability, and measurements of micro-computed tomography voids.

    PubMed

    Alhashimi, Raghad A; Mannocci, Francesco; Sauro, Salvatore

    2016-06-01

    The dynamic thermomechanical properties, sealing ability, and voids formation of an experimental obturation hydroxyapatite-reinforced polyethylene (HA/PE) composite/carrier system were investigated and compared with those of a commercial system [GuttaCore (GC)]. The HA/PE system was specifically designed using a melt-extrusion process. The viscoelastic properties of HA/PE were determined using a dynamic thermomechanical analyser. Human single-rooted teeth were endodontically instrumented and obturated using HA/PE or GC systems, and then sealing ability was assessed using a fluid filtration system. In addition, micro-computed tomography (μCT) was used to quantify apparent voids within the root-canal space. The data were statistically analysed using one-way anova and post hoc tests. The HA/PE composite exhibited important modulus and damping changes with an increase of temperature. The HA/PE system was more flexible than GC as the modulus of GC appeared to be significantly higher than that of HA/PE as a result of the high positive glass transition temperature (Tg ). However, HA/PE and GC presented similar sealing abilities. In conclusion, because sealing ability and voids formation were comparable between the tested materials, the experimental HA/PE system may be considered a suitable alternative material for root-canal obturation. Moreover, HA/PE possesses specific viscoelastic behaviour and lower melting points, which may facilitate root-canal retreatments. PMID:27041355

  17. Panoramic cone beam computed tomography

    SciTech Connect

    Chang Jenghwa; Zhou Lili; Wang Song; Clifford Chao, K. S.

    2012-05-15

    Purpose: Cone-beam computed tomography (CBCT) is the main imaging tool for image-guided radiotherapy but its functionality is limited by a small imaging volume and restricted image position (imaged at the central instead of the treatment position for peripheral lesions to avoid collisions). In this paper, the authors present the concept of ''panoramic CBCT,'' which can image patients at the treatment position with an imaging volume as large as practically needed. Methods: In this novel panoramic CBCT technique, the target is scanned sequentially from multiple view angles. For each view angle, a half scan (180 deg. + {theta}{sub cone} where {theta}{sub cone} is the cone angle) is performed with the imaging panel positioned in any location along the beam path. The panoramic projection images of all views for the same gantry angle are then stitched together with the direct image stitching method (i.e., according to the reported imaging position) and full-fan, half-scan CBCT reconstruction is performed using the stitched projection images. To validate this imaging technique, the authors simulated cone-beam projection images of the Mathematical Cardiac Torso (MCAT) thorax phantom for three panoramic views. Gaps, repeated/missing columns, and different exposure levels were introduced between adjacent views to simulate imperfect image stitching due to uncertainties in imaging position or output fluctuation. A modified simultaneous algebraic reconstruction technique (modified SART) was developed to reconstruct CBCT images directly from the stitched projection images. As a gold standard, full-fan, full-scan (360 deg. gantry rotation) CBCT reconstructions were also performed using projection images of one imaging panel large enough to encompass the target. Contrast-to-noise ratio (CNR) and geometric distortion were evaluated to quantify the quality of reconstructed images. Monte Carlo simulations were performed to evaluate the effect of scattering on the image quality and

  18. Bone dynamics in the upward direction after a maxillary sinus floor elevation procedure: serial segmentation using synchrotron radiation micro-computed tomography

    PubMed Central

    Seo, Seung-Jun; Bark, Chung Wung; Lim, Jae-Hong; Kim, Yong-Gun

    2015-01-01

    Objective Maxillary sinus floor augmentation has been shown to be the most predictable surgical technique for enhancing the bone volume in the posterior area of the maxilla. The purpose of this study was to analyze the serial slice image segmentation of newly formed bone and bone substitutes after sinus floor elevation using synchrotron radiation X-ray micro-computed tomography (SR-μCT). Materials and methods Bone biopsy specimens were collected after 6 months of sinus floor augmentation. From the six bone biopsy specimens, the cross-sectional images at every 8 μm along the apical direction from the inferior border using serial segmentation from three-dimensional reconstructed X-ray images were analyzed. The amount of new bone and bone substitutes were measured at each slicing image (300–430 images per specimen). Results The bone dynamics between the new bone and bone substitutes along the inferior–superior direction in humans after maxillary sinus floor elevation (MSFE) were analyzed using the whole sample region. Although these observations suggest that the specimens are structurally inhomogeneous, sinus floor elevation was confirmed to be a reliable surgical procedure for increasing the amount of bone. Conclusion SR-μCT is highly effective for obtaining high-resolution images. An analysis of biological specimens using SR-μCT is quite reliable and this technique will be an important tool in the wide field of tissue engineering. PMID:26347146

  19. Evaluation of the characteristics of hepatic focal nodular hyperplasia: correlation between dynamic contrast-enhanced multislice computed tomography and pathological findings

    PubMed Central

    Zhang, Hai-Tao; Gao, Xin-Yi; Xu, Qin-Sha; Chen, Yu-Tang; Song, Yu-Piao; Yao, Zhen-Wei

    2016-01-01

    Objective To evaluate the characteristics of enhancement of focal nodular hyperplasia (FNH) of the liver by analyzing the dynamic contrast-enhanced multislice computed tomography (MSCT) features and correlating them with pathological findings. Patients and methods Nine males and 16 females with pathologically confirmed FNH and complete preoperative contrast-enhanced MSCT data were recruited for this study. The imaging features of FNH on the pre- and postcontrast MSCT were analyzed by two experienced radiologists by consensus. Results Pathology showed central scars and abnormal blood vessels in 17 and 21 of 25 lesions, respectively, while MSCT with multiphase enhancement showed central scars in eight of the 17 lesions (47.1%) and abnormal arteries or draining veins in 13 of the 21 lesions (61.9%). Furthermore, abnormal draining veins in five lesions were found to be diagnostic, which is another important finding. Conclusion Multiphase scanning can provide the panorama of FNH lesions and reveal their enhancement patterns and pathological characteristics. Abnormal blood vessels within or around the lesion are demonstrated more often than central scar, and both should be observed for FNH diagnosis. PMID:27578988

  20. The Effect of Lumbar Lordosis on Screw Loosening in Dynesys Dynamic Stabilization: Four-Year Follow-Up with Computed Tomography

    PubMed Central

    Kuo, Chao-Hung; Chang, Peng-Yuan; Tu, Tsung-Hsi; Fay, Li-Yu; Chang, Hsuan-Kan; Wu, Jau-Ching; Huang, Wen-Cheng; Cheng, Henrich

    2015-01-01

    Introduction. This study aimed to evaluate the effects of Dynesys dynamic stabilization (DDS) on clinical and radiographic outcomes, including spinal pelvic alignment. Method. Consecutive patients who underwent 1- or 2-level DDS for lumbar spondylosis, mild degenerative spondylolisthesis, or degenerative disc disease were included. Clinical outcomes were evaluated by Visual Analogue Scale for back and leg pain, Oswestry Disability Index, and the Japanese Orthopedic Association scores. Radiographic outcomes were assessed by radiographs and computed tomography. Pelvic incidence and lumbar lordosis (LL) were also compared. Results. In 206 patients with an average follow-up of 51.1 ± 20.8 months, there were 87 screws (8.2%) in 42 patients (20.4%) that were loose. All clinical outcomes improved at each time point after operation. Patients with loosened screws were 45 years older. Furthermore, there was a higher risk of screw loosening in DDS involving S1, and these patients were more likely to have loosened screws if the LL failed to increase after the operation. Conclusions. The DDS screw loosening rate was overall 8.2% per screw and 20.4% per patient at more than 4 years of follow-up. Older patients, S1 involvement, and those patients who failed to gain LL postoperatively were at higher risk of screw loosening. PMID:26779532

  1. Physical evaluation of a high-frame-rate extended dynamic range flat panel detector for real-time cone beam computed tomography applications

    NASA Astrophysics Data System (ADS)

    Boyce, Sarah J.; Chawla, Amarpreet; Samei, Ehsan

    2005-04-01

    The use of flat panel detectors in computed tomography (CT) systems can improve resolution, reduce system cost, and add operational flexibility by combining fluoroscopy and radiography applications within CT systems. However, some prior studies have suggested that flat panel detectors would not perform well in CT applications due to their lack of high dynamic range, lag artifacts, and inadequate frame rate. The purpose of this study was to perform a physical evaluation of a prototype flat panel detector capable of high frame rates and extended dynamic range. The flat panel detector used had a pixel size of 194 microns and a matrix size of 2048x1536. The detector could be configured for several combinations of frame rate and matrix size up to 750 frames per second for a 512x16 matrix size with 4x4 binning. The evaluation was performed in terms of the MTF and DQE as a function of frame rate and exposure at the IEC RQA5 (~75 kVp, 21 mm Al) beam quality. The image lag was evaluated in terms of temporal-frequency dependent transfer function. Offset shift were also evaluated. Preliminary results indicate 0.1 MTF at 0.92 cycles/mm and DQE(0) of approximately 0.8, 0.6, 0.4, and 0.22 at 0.144, 0.065, 0.035, and 0.008 mR per frame exposures. The temporal MTF exhibited a low-frequency drop and a value of 0.5 at the Nyquist frequency. Offset shift was negligible. Considering high frame rate capabilities of the new detector, the results suggest that the detector has potential for use in real-time CT applications including CT angiography.

  2. Computed tomography demonstration of cholecystogastric fistula.

    PubMed

    Chou, Chung Kuao

    2016-06-01

    Cholecystogastric fistula is a rare complication of chronic cholecystitis or long-standing cholelithiasis. It results from the gradual erosion of the approximated, chronically inflamed wall of the gall bladder and stomach with fistulous tract formation. The present case describes the direct visualization of a cholecystogastric fistula by computed tomography in a patient without prior biliary system complaints. PMID:27257453

  3. Computed Tomography For Inspection Of Thermistors

    NASA Technical Reports Server (NTRS)

    Schaefer, Lloyd A.

    1991-01-01

    Computed tomography (CT) enables identification of cracked thermistors without disassembly of equipment containing them. CT unit used to scan equipment and locate thermistors. Further scans made in various radial orientations perpendicular to plane of devices to find cracks. Cracks invisible in conventional x-radiographs seen.

  4. Computed tomography in the evaluation of trauma

    SciTech Connect

    Federle, M.P.; Brant-Zawadzki, M.

    1982-01-01

    This book is intended to be the current standard for computed tomography in the evaluation of trauma. It summarizes two years of experience at San Francisco General Hospital. The book is organized into seven chapters, covering head, maxillofacial, laryngeal, spinal, chest, abdominal, acetabular, and pelvic trauma. Extremity trauma is not discussed.

  5. Neutron computed tomography of rat lungs.

    PubMed

    Metzke, R W; Runck, H; Stahl, C A; Schillinger, B; Calzada, E; Mühlbauer, M; Schulz, M; Schneider, M; Priebe, H-J; Wall, W A; Guttmann, J

    2011-01-01

    Using conventional methods, three-dimensional imaging of the lung is challenging because of the low contrast between air and tissue and the large differences in dimensions between various pulmonary structures. The small distal airway structures and the high air-to-tissue ratio of lung tissue require an imaging technique which reliably discriminates between air and water. The objective of this study was to assess whether neutron computed tomography would satisfy such a requirement. This method utilizes the unique characteristic of neutrons of directly interacting with the atomic nucleus rather than being scattered by the atomic shell. Neutron computed tomography was tested in rats and allowed differentiation of larger lung structures (e.g., lobes) and distal airways. Airways could be identified reliably down to the sixth bronchial generation, in some cases even down to the tenth generation. The lung could be stabilized for sufficiently long exposure times to achieve an image resolution of 50-60 µm, which is the current physical resolution limit of the neutron computed tomography facility. Neutron computed tomography allowed excellent lung imaging without the need for additional tissue preparation or contrast media. The enhanced structural resolution obtained by applying this new research technique may improve understanding of lung physiology and respiratory therapy. PMID:21119223

  6. Computed tomography in trauma: An atlas approach

    SciTech Connect

    Toombs, B.D.; Sandler, C.

    1986-01-01

    This book discussed computed tomography in trauma. The text is organized according to mechanism of injury and site of injury. In addition to CT, some correlation with other imaging modalities is included. Blunt trauma, penetrating trauma, complications and sequelae of trauma, and use of other modalities are covered.

  7. Cerebral computed tomography, 3rd Edition

    SciTech Connect

    Weisberg, L.; Nice, C.

    1988-01-01

    This book is an introduction to the utilization of computed tomography in evaluating patients with intracranial and orbital disorders. It features clinical correlations and provides an overview of general principles, performance, and normal anatomy of CT. It covers evaluation of specific neurologic signs and symptoms, including stroke, metastatic disease, increased intracranial pressure, head injury, pediatric conditions, and more.

  8. Computed Tomography Analysis of NASA BSTRA Balls

    SciTech Connect

    Perry, R L; Schneberk, D J; Thompson, R R

    2004-10-12

    Fifteen 1.25 inch BSTRA balls were scanned with the high energy computed tomography system at LLNL. This system has a resolution limit of approximately 210 microns. A threshold of 238 microns (two voxels) was used, and no anomalies at or greater than this were observed.

  9. Computed Tomography Angiography of the Neurovascular Circulation.

    PubMed

    Mohan, Suyash; Agarwal, Mohit; Pukenas, Bryan

    2016-01-01

    Computed tomography angiography of the head and neck is a powerful tool for imaging and diagnosis of a plethora of disorders of the cervicocerebral vasculature. This article reviews the technique, indications, and interpretation of many of these disorders. A standard report checklist is also presented. PMID:26654397

  10. Respirator triggering of electron beam computed tomography (EBCT): evaluation of dynamic changes during mechanical expiration in the traumatized patient

    NASA Astrophysics Data System (ADS)

    Recheis, Wolfgang A.; Kleinsasser, Axel; Hatschenberger, Robert; Knapp, Rudolf; zur Nedden, Dieter; Hoermann, Christoph

    1999-05-01

    The purpose of this project is to evaluate the dynamic changes during expiration at different levels of positive end- expiratory pressure (PEEP) in the ventilated patient. We wanted to discriminate between normal lung function and acute respiratory distress syndrome (ARDS). After approval by the local Ethic Committee we studied two ventilated patients: (1) with normal lung function; (2) ARDS). We used the 50 ms scan mode of the EBCT. The beam was positioned 1 cm above the diaphragm. The table position remained unchanged. An electronic trigger was developed, that utilizes the respirators synchronizing signal to start the EBCT at the onset of expiration. During controlled mechanical expiration at two levels of PEEP (0 and 15 cm H2O), pulmonary aeration was rated as: well-aerated (-900HU/-500HU), poorly- aerated (-500HU/-100HU) and non-aerated (-100HU/+100HU). Pathological and normal lung function showed different dynamic changes (FIG.4-12). The different PEEP levels resulted in a significant change of pulmonary aeration in the same patient. Although we studied only a very limited number of patients, respirator triggered EBCT may be accurate in discriminating pathological changes due to the abnormal lung function in the mechanically ventilated patient.

  11. Parallel Computing for the Computed-Tomography Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Lee, Seungwon

    2008-01-01

    This software computes the tomographic reconstruction of spatial-spectral data from raw detector images of the Computed-Tomography Imaging Spectrometer (CTIS), which enables transient-level, multi-spectral imaging by capturing spatial and spectral information in a single snapshot.

  12. Longitudinal Evaluation of Sympathetic Nervous System and Perfusion in Normal and Spontaneously Hypertensive Rat Hearts with Dynamic Single-Photon Emission Computed Tomography.

    PubMed

    Zan, Yunlong; Boutchko, Rostyslav; Huang, Qiu; Li, Biao; Chen, Kewei; Gullberg, Grant T

    2015-01-01

    The objective of this work was to evaluate the sympathetic nervous system and structure remodeling during the progression of heart failure in a rodent model using dynamic cardiac single-photon emission computed tomography (SPECT). The spontaneously hypertensive rat (SHR) model was used to study changes in the nervous system innervation and perfusion in the left ventricular (LV) myocardium with the progression of left ventricular hypertrophy (LVH) to heart failure. Longitudinal dynamic SPECT studies were performed with seven SHR and seven Wistar-Kyoto (WKY) rats over 1.5 years using a dual-head SPECT scanner with pinhole collimators. Time-activity curves (TACs) of the 123I-MIBG and 201Tl distribution in the LV blood pool and myocardium were extracted from dynamic SPECT data and fitted to compartment models to determine the influx rate, washout rate, and distribution volume (DV) of 123I-MIBG and 201Tl in the LV myocardium. The standardized uptake values (SUVs) of 123I-MIBG and 201Tl in the LV myocardium were also calculated from the static reconstructed images. The influx and washout rates of 123I-MIBG did not show a significant difference between SHRs and WKY rats. The DVs of 123I-MIBG were greater in the SHRs than in the WKY rats (p = .0028). Specifically, the DV of 123I-MIBG became greater in the SHRs by 6 months of age (p = .0017) and was still significant at the age of 22 months. The SUV of 123I-MIBG in SHRs exhibited abnormal values compared to WKY rats from the age of 18 months. There was no difference in the influx rate and the washout rate of 201Tl between the SHRs and WKY rats. The SHRs exhibited greater DV of 201Tl than WKY rats after the age of 18 months (p = .034). The SUV of 201Tl in SHRs did not show any significant difference from WKY at all ages. The higher DV of 123I-MIBG in the LV myocardium reveals abnormal nervous system activity of the SHRs at an age of 6 months, whereas a greater DV of 201Tl in the LV myocardium can only be detected at an age

  13. Computational fluid dynamics

    NASA Technical Reports Server (NTRS)

    1989-01-01

    An overview of computational fluid dynamics (CFD) activities at the Langley Research Center is given. The role of supercomputers in CFD research, algorithm development, multigrid approaches to computational fluid flows, aerodynamics computer programs, computational grid generation, turbulence research, and studies of rarefied gas flows are among the topics that are briefly surveyed.

  14. Computed tomography of the spine

    SciTech Connect

    Haughton, V.M.; Williams, A.L.

    1982-01-01

    The book describes the computed tomographic (CT) techniques for imaging the different elements comprising the spinal column and canal. The use of intravenous and intrathecal contrast enhancement and of xenon enhancement is briefly mentioned. Reconstruction techniques and special problems regarding CT of the spine are presented. CT of the spinal cord, meninges and subarachnoid space, epidural space, intervertebral discs, facet joints, and vertebrae present normal anatomy, and several common pathologic conditions. (KRM)

  15. Real-time computed optical interferometric tomography

    NASA Astrophysics Data System (ADS)

    Shemonski, Nathan D.; Liu, Yuan-Zhi; Ahmad, Adeel; Adie, Steven G.; Carney, P. Scott; Boppart, Stephen A.

    2014-03-01

    High-resolution tomography is of great importance to many areas of biomedical imaging, but with it comes several apparent tradeoffs such as a narrowing depth-of-field and increasing optical aberrations. Overcoming these challenges has attracted many hardware and computational solutions. Hardware solutions, though, can become bulky or expensive and computational approaches can require high computing power or large processing times. This study demonstrates memory efficient implementations of interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO) - two computational approaches for overcoming the depthof- field limitation and the effect of optical aberrations in optical coherence tomography (OCT). Traditionally requiring lengthy post processing, here we report implementations of ISAM and CAO on a single GPU for real-time in vivo imaging. Real-time, camera-limited ISAM processing enabled reliable acquisition of stable data for in vivo imaging, and CAO processing on the same GPU is shown to quickly correct static aberrations. These algorithmic advances hold the promise for high-resolution volumetric imaging in time-sensitive situations as well as enabling aberrationfree cellular-level volumetric tomography.

  16. Computed tomography of Tietze syndrome.

    PubMed

    Edelstein, G; Levitt, R G; Slaker, D P; Murphy, W A

    1984-02-01

    Six patients with clinical features suggestive of Tietze syndrome had a thoracic computed tomographic (CT) examination following a normal plain film or tomographic examination (or both) of the affected costochondral junction. A chest wall mass was excluded in all six patients. The CT findings included enlargement of the costal cartilage at the site of complaint (two patients), ventral angulation of the involved costal cartilage (two patients), and normal anatomy of the costochondral junction (two patients). Exclusion of a chest wall mass by CT may obviate the need for operative intervention. PMID:6690519

  17. Computed tomography of the medulla

    SciTech Connect

    Daniels, D.L.; Williams, A.L.; Haughton, V.M.

    1982-10-01

    The medulla was studied in cadavers and in 100 patients both with and without the intrathecal administration of contrast material. The computed tomographic (CT) anatomy was correlated with the appearance on anatomic dissections. The pyramids, olives, and inferior cerebellar peduncles produced characteristic contours on cross sections of the medulla. The hypoglossal nerve by its location and course in the medullary cistern could be distinguished from the glossopharyngeal, vagal, and spinal accessory nerves. For optimal evaluation of the medulla, intrathecal administration of metrizamide and 5- and/or 1.5-mm-thick axial and coronal sections are recommended.

  18. Introducing Seismic Tomography with Computational Modeling

    NASA Astrophysics Data System (ADS)

    Neves, R.; Neves, M. L.; Teodoro, V.

    2011-12-01

    Learning seismic tomography principles and techniques involves advanced physical and computational knowledge. In depth learning of such computational skills is a difficult cognitive process that requires a strong background in physics, mathematics and computer programming. The corresponding learning environments and pedagogic methodologies should then involve sets of computational modelling activities with computer software systems which allow students the possibility to improve their mathematical or programming knowledge and simultaneously focus on the learning of seismic wave propagation and inverse theory. To reduce the level of cognitive opacity associated with mathematical or programming knowledge, several computer modelling systems have already been developed (Neves & Teodoro, 2010). Among such systems, Modellus is particularly well suited to achieve this goal because it is a domain general environment for explorative and expressive modelling with the following main advantages: 1) an easy and intuitive creation of mathematical models using just standard mathematical notation; 2) the simultaneous exploration of images, tables, graphs and object animations; 3) the attribution of mathematical properties expressed in the models to animated objects; and finally 4) the computation and display of mathematical quantities obtained from the analysis of images and graphs. Here we describe virtual simulations and educational exercises which enable students an easy grasp of the fundamental of seismic tomography. The simulations make the lecture more interactive and allow students the possibility to overcome their lack of advanced mathematical or programming knowledge and focus on the learning of seismological concepts and processes taking advantage of basic scientific computation methods and tools.

  19. Optimization of acquisition parameters and accuracy of target motion trajectory for four-dimensional cone-beam computed tomography with a dynamic thorax phantom.

    PubMed

    Shimohigashi, Yoshinobu; Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Nakato, Kengo; Nagasue, Nozomu; Kai, Yudai

    2015-01-01

    Our purpose in this study was to evaluate the performance of four-dimensional computed tomography (4D-CBCT) and to optimize the acquisition parameters. We evaluated the relationship between the acquisition parameters of 4D-CBCT and the accuracy of the target motion trajectory using a dynamic thorax phantom. The target motion was created three dimensionally using target sizes of 2 and 3 cm, respiratory cycles of 4 and 8 s, and amplitudes of 1 and 2 cm. The 4D-CBCT data were acquired under two detector configurations: "small mode" and "medium mode". The projection data acquired with scan times ranging from 1 to 4 min were sorted into 2, 5, 10, and 15 phase bins. The accuracy of the measured target motion trajectories was evaluated by means of the root mean square error (RMSE) from the setup values. For the respiratory cycle of 4 s, the measured trajectories were within 2 mm of the setup values for all acquisition times and target sizes. Similarly, the errors for the respiratory cycle of 8 s were <4 mm. When we used 10 or more phase bins, the measured trajectory errors were within 2 mm of the setup values. The trajectory errors for the two detector configurations showed similar trends. The acquisition times for achieving an RMSE of 1 mm for target sizes of 2 and 3 cm were 2 and 1 min, respectively, for respiratory cycles of 4 s. The results obtained in this study enable optimization of the acquisition parameters for target size, respiratory cycle, and desired measurement accuracy. PMID:25287015

  20. Evaluation of liver parenchyma and perfusion using dynamic contrast-enhanced computed tomography and contrast-enhanced ultrasonography in captive green iguanas (Iguana iguana) under general anesthesia

    PubMed Central

    2014-01-01

    Background Contrast-enhanced diagnostic imaging techniques are considered useful in veterinary and human medicine to evaluate liver perfusion and focal hepatic lesions. Although hepatic diseases are a common occurrence in reptile medicine, there is no reference to the use of contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography (CECT) to evaluate the liver in lizards. Therefore, the aim of this study was to evaluate the pattern of change in echogenicity and attenuation of the liver in green iguanas (Iguana iguana) after administration of specific contrast media. Results An increase in liver echogenicity and density was evident during CEUS and CECT, respectively. In CEUS, the mean ± SD (median; range) peak enhancement was 19.9% ± 7.5 (18.3; 11.7-34.6). Time to peak enhancement was 134.0 ± 125.1 (68.4; 59.6-364.5) seconds. During CECT, first visualization of the contrast medium was at 3.6 ± 0.5 (4; 3-4) seconds in the aorta, 10.7 ± 2.2 (10.5; 7-14) seconds in the hepatic arteries, and 15 ± 4.5 (14.5; 10-24) seconds in the liver parenchyma. Time to peak was 14.1 ± 3.4 (13; 11-21) and 31 ± 9.6 (29; 23-45) seconds in the aorta and the liver parenchyma, respectively. Conclusion CEUS and dynamic CECT are practical means to determine liver hemodynamics in green iguanas. Distribution of contrast medium in iguana differed from mammals. Specific reference ranges of hepatic perfusion for diagnostic evaluation of the liver in iguanas are necessary since the use of mammalian references may lead the clinician to formulate incorrect diagnostic suspicions. PMID:24885935

  1. 21 CFR 892.1200 - Emission computed tomography system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Emission computed tomography system. 892.1200... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1200 Emission computed tomography system. (a) Identification. An emission computed tomography system is a device intended to detect...

  2. Metabolomics of Breast Cancer Using High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopy: Correlations with 18F-FDG Positron Emission Tomography-Computed Tomography, Dynamic Contrast-Enhanced and Diffusion-Weighted Imaging MRI

    PubMed Central

    Yoon, Haesung; Yoon, Dahye; Yun, Mijin; Choi, Ji Soo; Park, Vivian Youngjean; Kim, Eun-Kyung; Jeong, Joon; Koo, Ja Seung; Yoon, Jung Hyun; Moon, Hee Jung; Kim, Suhkmann; Kim, Min Jung

    2016-01-01

    Purpose Our goal in this study was to find correlations between breast cancer metabolites and conventional quantitative imaging parameters using high-resolution magic angle spinning (HR-MAS) magnetic resonance spectroscopy (MRS) and to find breast cancer subgroups that show high correlations between metabolites and imaging parameters. Materials and methods Between August 2010 and December 2013, we included 53 female patients (mean age 49.6 years; age range 32–75 years) with a total of 53 breast lesions assessed by the Breast Imaging Reporting and Data System. They were enrolled under the following criteria: breast lesions larger than 1 cm in diameter which 1) were suspicious for malignancy on mammography or ultrasound (US), 2) were pathologically confirmed to be breast cancer with US-guided core-needle biopsy (CNB) 3) underwent 3 Tesla MRI with dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI) and positron emission tomography-computed tomography (PET-CT), and 4) had an attainable immunohistochemistry profile from CNB. We acquired spectral data by HR-MAS MRS with CNB specimens and expressed the data as relative metabolite concentrations. We compared the metabolites with the signal enhancement ratio (SER), maximum standardized FDG uptake value (SUV max), apparent diffusion coefficient (ADC), and histopathologic prognostic factors for correlation. We calculated Spearman correlations and performed a partial least squares-discriminant analysis (PLS-DA) to further classify patient groups into subgroups to find correlation differences between HR-MAS spectroscopic values and conventional imaging parameters. Results In a multivariate analysis, the PLS-DA models built with HR-MAS MRS metabolic profiles showed visible discrimination between high and low SER, SUV, and ADC. In luminal subtype breast cancer, compared to all cases, high SER, ADV, and SUV were more closely clustered by visual assessment. Multiple metabolites were correlated with SER and SUV in

  3. X ray computed tomography for failure analysis

    NASA Astrophysics Data System (ADS)

    Bossi, Richard H.; Crews, Alan R.; Georgeson, Gary E.

    1992-08-01

    Under a preliminary testing task assignment of the Advanced Development of X-Ray Computed Tomography Application program, computed tomography (CT) has been studied for its potential as a tool to assist in failure analysis investigations. CT provides three-dimensional spatial distribution of material that can be used to assess internal configurations and material conditions nondestructively. This capability has been used in failure analysis studies to determine the position of internal components and their operation. CT is particularly advantageous on complex systems, composite failure studies, and testing under operational or environmental conditions. CT plays an important role in reducing the time and effort of a failure analysis investigation. Aircraft manufacturing or logistical facilities perform failure analysis operations routinely and could be expected to reduce schedules, reduce costs and/or improve evaluation on about 10 to 30 percent of the problems they investigate by using CT.

  4. Computed tomography of the calcaneus: normal anatomy

    SciTech Connect

    Heger, L.; Wulff, K.

    1985-07-01

    The normal sectional anatomy of the calcaneus was studied as the background for interpretation of computed tomography (CT) of fractures. Multiplanar CT examination of the normal calcaneus was obtained, and sections were matched with a simplified anatomic model. Sectional anatomy in the four most important planes is described. This facilitates three-dimensional understanding of the calcaneus from sections and interpretation of CT sections obtained in any atypical plane.

  5. Computed tomography of ancient Egyptian mummies.

    PubMed

    Harwood-Nash, D C

    1979-12-01

    This first report of the application of computed tomography (CT) to the study of ancient mummies, the desiccated brain of a boy and the body of a young woman within her cartonnage, shows that CT is uniquely suitable for the study of such antiquities, a study that does not necessitate destruction of the mummy or its cartonnage. Exquisite images result that are of great paleoanatomical, paleopathological, and archeological significance. PMID:389964

  6. Single photon emission computed tomography and other selected computer topics

    SciTech Connect

    Price, R.R.; Gilday, D.L.; Croft, B.Y.

    1980-01-01

    This volume includes an overview of single photon emission computed tomography and numerous papers that describe and evaluate specific systems and techniques. Papers cover such topics as Auger cameras; seven-pinhole and slant-hole collimators; brain; cardiac; and gated blood-pool studies; and the BICLET and SPECT systems.

  7. Single photon emission computed tomography-guided Cerenkov luminescence tomography

    NASA Astrophysics Data System (ADS)

    Hu, Zhenhua; Chen, Xueli; Liang, Jimin; Qu, Xiaochao; Chen, Duofang; Yang, Weidong; Wang, Jing; Cao, Feng; Tian, Jie

    2012-07-01

    Cerenkov luminescence tomography (CLT) has become a valuable tool for preclinical imaging because of its ability of reconstructing the three-dimensional distribution and activity of the radiopharmaceuticals. However, it is still far from a mature technology and suffers from relatively low spatial resolution due to the ill-posed inverse problem for the tomographic reconstruction. In this paper, we presented a single photon emission computed tomography (SPECT)-guided reconstruction method for CLT, in which a priori information of the permissible source region (PSR) from SPECT imaging results was incorporated to effectively reduce the ill-posedness of the inverse reconstruction problem. The performance of the method was first validated with the experimental reconstruction of an adult athymic nude mouse implanted with a Na131I radioactive source and an adult athymic nude mouse received an intravenous tail injection of Na131I. A tissue-mimic phantom based experiment was then conducted to illustrate the ability of the proposed method in resolving double sources. Compared with the traditional PSR strategy in which the PSR was determined by the surface flux distribution, the proposed method obtained much more accurate and encouraging localization and resolution results. Preliminary results showed that the proposed SPECT-guided reconstruction method was insensitive to the regularization methods and ignored the heterogeneity of tissues which can avoid the segmentation procedure of the organs.

  8. Reconstructive tomography in gas dynamics and plasma physics

    NASA Astrophysics Data System (ADS)

    Pikalov, Valerii Vladimirovich; Preobrazhenskii, Nikolai Georgievich

    The physics, mathematics, and principal applications of reconstructive tomography are examined with particular reference to problems in aerodynamics, gas dynamics, and plasma physics. The discussion covers fluoroscopic tomography and tomosynthesis, tomography with a priori constraints, mathematical formalisms of the linear tomography of asymmetric objects, theoretical principles of the linear tomography of two-dimensional objects, and algorithms of two-dimensional linear tomography. Some problems in three-dimensional linear tomography are also discussed.

  9. Computed tomography to quantify tooth abrasion

    NASA Astrophysics Data System (ADS)

    Kofmehl, Lukas; Schulz, Georg; Deyhle, Hans; Filippi, Andreas; Hotz, Gerhard; Berndt-Dagassan, Dorothea; Kramis, Simon; Beckmann, Felix; Müller, Bert

    2010-09-01

    Cone-beam computed tomography, also termed digital volume tomography, has become a standard technique in dentistry, allowing for fast 3D jaw imaging including denture at moderate spatial resolution. More detailed X-ray images of restricted volumes for post-mortem studies in dental anthropology are obtained by means of micro computed tomography. The present study evaluates the impact of the pipe smoking wear on teeth morphology comparing the abraded tooth with its contra-lateral counterpart. A set of 60 teeth, loose or anchored in the jaw, from 12 dentitions have been analyzed. After the two contra-lateral teeth were scanned, one dataset has been mirrored before the two datasets were registered using affine and rigid registration algorithms. Rigid registration provides three translational and three rotational parameters to maximize the overlap of two rigid bodies. For the affine registration, three scaling factors are incorporated. Within the present investigation, affine and rigid registrations yield comparable values. The restriction to the six parameters of the rigid registration is not a limitation. The differences in size and shape between the tooth and its contra-lateral counterpart generally exhibit only a few percent in the non-abraded volume, validating that the contralateral tooth is a reasonable approximation to quantify, for example, the volume loss as the result of long-term clay pipe smoking. Therefore, this approach allows quantifying the impact of the pipe abrasion on the internal tooth morphology including root canal, dentin, and enamel volumes.

  10. Monitoring the Effects of Anti-angiogenesis on the Radiation Sensitivity of Pancreatic Cancer Xenografts Using Dynamic Contrast-Enhanced Computed Tomography

    SciTech Connect

    Cao, Ning; Cao, Minsong; Chin-Sinex, Helen; Mendonca, Marc; Ko, Song-Chu; Stantz, Keith M.

    2014-02-01

    Purpose: To image the intratumor vascular physiological status of pancreatic tumors xenografts and their response to anti-angiogenic therapy using dynamic contrast-enhanced computed tomography (DCE-CT), and to identify parameters of vascular physiology associated with tumor x-ray sensitivity after anti-angiogenic therapy. Methods and Materials: Nude mice bearing human BxPC-3 pancreatic tumor xenografts were treated with 5 Gy of radiation therapy (RT), either a low dose (40 mg/kg) or a high dose (150 mg/kg) of DC101, the anti-VEGF receptor-2 anti-angiogenesis antibody, or with combination of low or high dose DC101 and 5 Gy RT (DC101-plus-RT). DCE-CT scans were longitudinally acquired over a 3-week period post-DC101 treatment. Parametric maps of tumor perfusion and fractional plasma volume (F{sub p}) were calculated and their averaged values and histogram distributions evaluated and compared to controls, from which a more homogeneous physiological window was observed 1-week post-DC101. Mice receiving a combination of DC101-plus-RT(5 Gy) were imaged baseline before receiving DC101 and 1 week after DC101 (before RT). Changes in perfusion and F{sub p} were compared with alternation in tumor growth delay for RT and DC101-plus-RT (5 Gy)-treated tumors. Results: Pretreatment with low or high doses of DC101 before RT significantly delayed tumor growth by an average 7.9 days compared to RT alone (P ≤ .01). The increase in tumor growth delay for the DC101-plus-RT-treated tumors was strongly associated with changes in tumor perfusion (ΔP>−15%) compared to RT treated tumors alone (P=.01). In addition, further analysis revealed a trend linking the tumor's increased growth delay to its tumor volume-to-DC101 dose ratio. Conclusions: DCE-CT is capable of monitoring changes in intratumor physiological parameter of tumor perfusion in response to anti-angiogenic therapy of a pancreatic human tumor xenograft that was associated with enhanced radiation response.

  11. Positron computed tomography: current state, clinical results and future trends

    SciTech Connect

    Schelbert, H.R.; Phelps, M.E.; Kuhl, D.E.

    1980-09-01

    An overview is presented of positron computed tomography: its advantages over single photon emission tomography, its use in metabolic studies of the heart and chemical investigation of the brain, and future trends. (ACR)

  12. Positron Computed Tomography: Current State, Clinical Results and Future Trends

    DOE R&D Accomplishments Database

    Schelbert, H. R.; Phelps, M. E.; Kuhl, D. E.

    1980-09-01

    An overview is presented of positron computed tomography: its advantages over single photon emission tomography, its use in metabolic studies of the heart and chemical investigation of the brain, and future trends. (ACR)

  13. Emerging clinical applications of computed tomography

    PubMed Central

    Liguori, Carlo; Frauenfelder, Giulia; Massaroni, Carlo; Saccomandi, Paola; Giurazza, Francesco; Pitocco, Francesca; Marano, Riccardo; Schena, Emiliano

    2015-01-01

    X-ray computed tomography (CT) has recently been experiencing remarkable growth as a result of technological advances and new clinical applications. This paper reviews the essential physics of X-ray CT and its major components. Also reviewed are recent promising applications of CT, ie, CT-guided procedures, CT-based thermometry, photon-counting technology, hybrid PET-CT, use of ultrafast-high pitch scanners, and potential use of dual-energy CT for material differentiations. These promising solutions and a better knowledge of their potentialities should allow CT to be used in a safe and effective manner in several clinical applications. PMID:26089707

  14. Emerging clinical applications of computed tomography.

    PubMed

    Liguori, Carlo; Frauenfelder, Giulia; Massaroni, Carlo; Saccomandi, Paola; Giurazza, Francesco; Pitocco, Francesca; Marano, Riccardo; Schena, Emiliano

    2015-01-01

    X-ray computed tomography (CT) has recently been experiencing remarkable growth as a result of technological advances and new clinical applications. This paper reviews the essential physics of X-ray CT and its major components. Also reviewed are recent promising applications of CT, ie, CT-guided procedures, CT-based thermometry, photon-counting technology, hybrid PET-CT, use of ultrafast-high pitch scanners, and potential use of dual-energy CT for material differentiations. These promising solutions and a better knowledge of their potentialities should allow CT to be used in a safe and effective manner in several clinical applications. PMID:26089707

  15. Calcium Scoring and Cardiac Computed Tomography.

    PubMed

    Parikh, Swapnesh; Budoff, Matthew J

    2016-01-01

    Although recent advances in noninvasive imaging technologies have potentially improved diagnostic efficiency and clinical outcomes of patients with acute chest pain, controversy remains regarding much of the accumulated evidence. This article reviews the role of coronary computed tomography (CT) angiography in the assessment of coronary risk, and its usefulness in the emergency department in facilitating appropriate disposition decisions. Also discussed is coronary artery calcification incidentally found on CT scans when done for indications such as evaluation of pulmonary embolism or lung cancer. The evidence base and clinical applications for both techniques are described, together with cost-effectiveness and radiation exposure considerations. PMID:26567977

  16. Computed tomography of infantile hepatic hemangioendothelioma

    SciTech Connect

    Lucaya, J.; Enriquez, G.; Amat, L.; Gonzalez-Rivero, M.A.

    1985-04-01

    Computed tomography (CT) was performed on five infants with hepatic hemangioendothelioma. Precontrast scans showed solitary or multiple, homogeneous, circumscribed areas with reduced attenuation values. Tiny tumoral calcifications were identified in two patients. Serial scans, after injection of a bolus of contrast material, showed early massive enhancement, which was either diffuse or peripheral. On delayed scans, multinocular tumors became isodense with surrounding liver, while all solitary ones showed varied degrees of centripetal enhancement and persistent central cleftlike unenhanced areas. The authors believe that these CT features are characteristic and obviate arteriographic confirmation.

  17. Computed tomography of cardiac pseudotumors and neoplasms.

    PubMed

    Anavekar, Nandan S; Bonnichsen, Crystal R; Foley, Thomas A; Morris, Michael F; Martinez, Matthew W; Williamson, Eric E; Glockner, James F; Miller, Dylan V; Breen, Jerome F; Araoz, Philip A

    2010-07-01

    Important features of cardiac masses can be clearly delineated on cardiac computed tomography (CT) imaging. This modality is useful in identifying the presence of a mass, its relationship with cardiac and extracardiac structures, and the features that distinguish one type of mass from another. A multimodality approach to the evaluation of cardiac tumors is advocated, with the use of echocardiography, CT imaging and magnetic resonance imaging as appropriately indicated. In this article, various cardiac masses are described, including pseudotumors and true cardiac neoplasms, and the CT imaging findings that may be useful in distinguishing these rare entities are presented. PMID:20705174

  18. Cone Beam Computed Tomography - Know its Secrets

    PubMed Central

    Kumar, Mohan; Shanavas, Muhammad; Sidappa, Ashwin; Kiran, Madhu

    2015-01-01

    Cone-beam computed tomography (CBCT) is an advanced imaging modality that has high clinical applications in the field of dentistry. CBCT proved to be a successful investigative modality that has been used for dental and maxillofacial imaging. Radiation exposure dose from CBCT is 10 times less than from conventional CT scans during maxillofacial exposure. Furthermore, CBCT is highly accurate and can provide a three-dimensional volumetric data in axial, sagittal and coronal planes. This article describes the basic technique, difference in CBCT from CT and main clinical applications of CBCT. PMID:25859112

  19. Algebraic and analytic reconstruction methods for dynamic tomography.

    PubMed

    Desbat, L; Rit, S; Clackdoyle, R; Mennessier, C; Promayon, E; Ntalampeki, S

    2007-01-01

    In this work, we discuss algebraic and analytic approaches for dynamic tomography. We present a framework of dynamic tomography for both algebraic and analytic approaches. We finally present numerical experiments. PMID:18002059

  20. Coronary Computed Tomography and Magnetic Resonance Imaging

    PubMed Central

    Kantor, Birgit; Nagel, Eike; Schoenhagen, Paul; Barkhausen, Jörg; Gerber, Thomas C.

    2009-01-01

    Cardiac computed tomography and magnetic resonance are relatively new imaging modalities that can exceed the ability of established imaging modalities to detect present pathology or predict patient outcomes. Coronary calcium scoring may be useful in asymptomatic patients at intermediate risk. Computed tomographic coronary angiography is a first-line indication to evaluate congenitally abnormal coronary arteries and, along with stress magnetic resonance myocardial perfusion imaging, is useful in symptomatic patients with nondiagnostic conventional stress tests. Cardiac magnetic resonance is indicated for visualizing cardiac structure and function, and delayed enhancement magnetic resonance is a first-line indication for assessing myocardial viability. Imaging plaque and molecular mechanisms related to plaque rupture holds great promise for the presymptomatic detection of patients at risk for coronary events but is not yet suitable for routine clinical use. PMID:19269527

  1. Space shuttle main engine computed tomography applications

    NASA Technical Reports Server (NTRS)

    Sporny, Richard F.

    1990-01-01

    For the past two years the potential applications of computed tomography to the fabrication and overhaul of the Space Shuttle Main Engine were evaluated. Application tests were performed at various government and manufacturer facilities with equipment produced by four different manufacturers. The hardware scanned varied in size and complexity from a small temperature sensor and turbine blades to an assembled heat exchanger and main injector oxidizer inlet manifold. The evaluation of capabilities included the ability to identify and locate internal flaws, measure the depth of surface cracks, measure wall thickness, compare manifold design contours to actual part contours, perform automatic dimensional inspections, generate 3D computer models of actual parts, and image the relationship of the details in a complex assembly. The capabilities evaluated, with the exception of measuring the depth of surface flaws, demonstrated the existing and potential ability to perform many beneficial Space Shuttle Main Engine applications.

  2. Microscopic x-ray luminescence computed tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zhu, Dianwen; Zhang, Kun; Li, Changqing

    2015-03-01

    X-ray luminescence computed tomography (XLCT) was emerged as a new hybrid imaging modality, in which the x-rays are used to excite phosphors emitting optical photons to be measured for imaging. In this paper, we reported a microscopic x-ray luminescence computed tomography (microXLCT) with a spatial resolution up to hundreds of micrometers for deep targets. We use a superfine x-ray pencil beam to scan the phosphor targets. The superfine x-ray pencil beam is generated by a small collimator mounted in front of a powerful x-ray tube (93212, Oxford Instrument). A CT detector is used to image the x-ray beam. We have generated an x-ray beam with a diameter of 192 micrometers with a collimator of 100 micrometers in diameter. The emitted optical photons on the top surface of phantom are reflected by a mirror and acquired by an electron multiplier charge-coupled device (EMCCD) camera (C9100-13, Hamamatsu Photonics). The microXLCT imaging system is built inside an x-ray shielding and light tight cabinet. The EMCCD camera is placed in a lead box. All the imaging components are controlled by a VC++ program. The optical photon propagation is modeled with the diffusion equation solved by the finite element method. We have applied different regularization methods including L2 and L1 in the microXLCT reconstruction algorithms. Numerical simulations and phantom experiments are used to validate the microXLCT imaging system.

  3. Comparison of computed tomography dose reporting software.

    PubMed

    Abdullah, A; Sun, Z; Pongnapang, N; Ng, K-H

    2012-08-01

    Computed tomography (CT) dose reporting software facilitates the estimation of doses to patients undergoing CT examinations. In this study, comparison of three software packages, i.e. CT-Expo (version 1.5, Medizinische Hochschule, Hannover, Germany), ImPACT CT Patients Dosimetry Calculator (version 0.99×, Imaging Performance Assessment on Computed Tomography, www.impactscan.org) and WinDose (version 2.1a, Wellhofer Dosimetry, Schwarzenbruck, Germany), has been made in terms of their calculation algorithm and the results of calculated doses. Estimations were performed for head, chest, abdominal and pelvic examinations based on the protocols recommended by European guidelines using single-slice CT (SSCT) (Siemens Somatom Plus 4, Erlangen, Germany) and multi-slice CT (MSCT) (Siemens Sensation 16, Erlangen, Germany) for software-based female and male phantoms. The results showed that there are some differences in final dose reporting provided by these software packages. There are deviations of effective doses produced by these software packages. Percentages of coefficient of variance range from 3.3 to 23.4 % in SSCT and from 10.6 to 43.8 % in MSCT. It is important that researchers state the name of the software that is used to estimate the various CT dose quantities. Users must also understand the equivalent terminologies between the information obtained from the CT console and the software packages in order to use the software correctly. PMID:22155753

  4. Computed Tomography Technology: Development and Applications for Defence

    NASA Astrophysics Data System (ADS)

    Baheti, G. L.; Saxena, Nisheet; Tripathi, D. K.; Songara, K. C.; Meghwal, L. R.; Meena, V. L.

    2008-09-01

    Computed Tomography(CT) has revolutionized the field of Non-Destructive Testing and Evaluation (NDT&E). Tomography for industrial applications warrants design and development of customized solutions catering to specific visualization requirements. Present paper highlights Tomography Technology Solutions implemented at Defence Laboratory, Jodhpur (DLJ). Details on the technological developments carried out and their utilization for various Defence applications has been covered.

  5. Computational fluid dynamic control

    NASA Technical Reports Server (NTRS)

    Hartley, Tom T.; Deabreu-Garcia, Alex

    1989-01-01

    A general technique is presented for modeling fluid, or gas, dynamic systems specifically for the development of control systems. The numerical methods which are generally used in computational fluid dynamics are borrowed to create either continuous-time or discrete-time models of the particular fluid system. The resulting equations can be either left in a nonlinear form, or easily linearized about an operating point. As there are typically very many states in these systems, the usual linear model reduction methods can be used on them to allow a low-order controller to be designed. A simple example is given which typifies many internal flow control problems. The resulting control is termed computational fluid dynamic control.

  6. Single-photon emission computed tomography (SPECT): Applications and potential

    SciTech Connect

    Holman, B.L.; Tumeh, S.S. )

    1990-01-26

    Single-photon emission computed tomography has received increasing attention as radiopharmaceuticals that reflect perfusion, metabolism, and receptor and cellular function have become widely available. Perfusion single-photon emission computed tomography of the brain provides functional information useful for the diagnosis and management of stroke, dementia, and epilepsy. Single-photon emission computed tomography has been applied to myocardial, skeletal, hepatic, and tumor scintigraphy, resulting in increased diagnostic accuracy over planar imaging because background activity and overlapping tissues interfere far less with activity from the target structure when tomographic techniques are used. Single-photon emission computed tomography is substantially less expensive and far more accessible than positron emission tomography and will become an increasingly attractive alternative for transferring the positron emission tomography technology to routine clinical use.

  7. Quality assessment of clinical computed tomography

    NASA Astrophysics Data System (ADS)

    Berndt, Dorothea; Luckow, Marlen; Lambrecht, J. Thomas; Beckmann, Felix; Müller, Bert

    2008-08-01

    Three-dimensional images are vital for the diagnosis in dentistry and cranio-maxillofacial surgery. Artifacts caused by highly absorbing components such as metallic implants, however, limit the value of the tomograms. The dominant artifacts observed are blowout and streaks. Investigating the artifacts generated by metallic implants in a pig jaw, the data acquisition for the patients in dentistry should be optimized in a quantitative manner. A freshly explanted pig jaw including related soft-tissues served as a model system. Images were recorded varying the accelerating voltage and the beam current. The comparison with multi-slice and micro computed tomography (CT) helps to validate the approach with the dental CT system (3D-Accuitomo, Morita, Japan). The data are rigidly registered to comparatively quantify their quality. The micro CT data provide a reasonable standard for quantitative data assessment of clinical CT.

  8. Ultra-high resolution computed tomography imaging

    DOEpatents

    Paulus, Michael J.; Sari-Sarraf, Hamed; Tobin, Jr., Kenneth William; Gleason, Shaun S.; Thomas, Jr., Clarence E.

    2002-01-01

    A method for ultra-high resolution computed tomography imaging, comprising the steps of: focusing a high energy particle beam, for example x-rays or gamma-rays, onto a target object; acquiring a 2-dimensional projection data set representative of the target object; generating a corrected projection data set by applying a deconvolution algorithm, having an experimentally determined a transfer function, to the 2-dimensional data set; storing the corrected projection data set; incrementally rotating the target object through an angle of approximately 180.degree., and after each the incremental rotation, repeating the radiating, acquiring, generating and storing steps; and, after the rotating step, applying a cone-beam algorithm, for example a modified tomographic reconstruction algorithm, to the corrected projection data sets to generate a 3-dimensional image. The size of the spot focus of the beam is reduced to not greater than approximately 1 micron, and even to not greater than approximately 0.5 microns.

  9. Computed tomography of radioactive objects and materials

    NASA Astrophysics Data System (ADS)

    Sawicka, B. D.; Murphy, R. V.; Tosello, G.; Reynolds, P. W.; Romaniszyn, T.

    1990-12-01

    Computed tomography (CT) has been performed on a number of radioactive objects and materials. Several unique technical problems are associated with CT of radioactive specimens. These include general safety considerations, techniques to reduce background-radiation effects on CT images and selection criteria for the CT source to permit object penetration and to reveal accurate values of material density. In the present paper, three groups of experiments will be described, for objects with low, medium and high levels of radioactivity. CT studies on radioactive specimens will be presented. They include the following: (1) examination of individual ceramic reactor-fuel (uranium dioxide) pellets, (2) examination of fuel samples from the Three Mile Island reactor, (3) examination of a CANDU (CANada Deuterium Uraniun: registered trademark) nuclear-fuel bundle which underwent a simulated loss-of-coolant accident resulting in high-temperature damage and (4) examination of a PWR nuclear-reactor fuel assembly.

  10. System Matrix Analysis for Computed Tomography Imaging

    PubMed Central

    Flores, Liubov; Vidal, Vicent; Verdú, Gumersindo

    2015-01-01

    In practical applications of computed tomography imaging (CT), it is often the case that the set of projection data is incomplete owing to the physical conditions of the data acquisition process. On the other hand, the high radiation dose imposed on patients is also undesired. These issues demand that high quality CT images can be reconstructed from limited projection data. For this reason, iterative methods of image reconstruction have become a topic of increased research interest. Several algorithms have been proposed for few-view CT. We consider that the accurate solution of the reconstruction problem also depends on the system matrix that simulates the scanning process. In this work, we analyze the application of the Siddon method to generate elements of the matrix and we present results based on real projection data. PMID:26575482

  11. System Matrix Analysis for Computed Tomography Imaging.

    PubMed

    Flores, Liubov; Vidal, Vicent; Verdú, Gumersindo

    2015-01-01

    In practical applications of computed tomography imaging (CT), it is often the case that the set of projection data is incomplete owing to the physical conditions of the data acquisition process. On the other hand, the high radiation dose imposed on patients is also undesired. These issues demand that high quality CT images can be reconstructed from limited projection data. For this reason, iterative methods of image reconstruction have become a topic of increased research interest. Several algorithms have been proposed for few-view CT. We consider that the accurate solution of the reconstruction problem also depends on the system matrix that simulates the scanning process. In this work, we analyze the application of the Siddon method to generate elements of the matrix and we present results based on real projection data. PMID:26575482

  12. Clinically applicable gated cardiac computed tomography

    SciTech Connect

    Cipriano, P.R.; Nassi, M.; Brody, W.R.

    1983-03-01

    Several attempts have been made to improve cardiac images obtained with x-ray transmission computed tomography (CT) by stopping cardiac motion through electrocardiographic gating. These methods reconstruct images that correspond to time intervals of the cardiac cycle identified by electrocardiography using either a pulsed x-ray beam at a selected time in the cardiac cycle or selected measurements in retrospect from regularly pulsed measurements made over several cardiac cycles. Missing CT angles of view (line integrals) have been a major problem contributing to degradation of such gated cardiac CT images. A new method for CT reconstruction from an incomplete set of projection data is presented that can be used clinically with a standard fan-beam reconstruction algorithm to improve gated cardiac CT images.

  13. Computed tomography of the abnormal thymus

    SciTech Connect

    Baron, R.L.; Lee, J.K.T.; Sagel, S.S.; Levitt, R.G.

    1982-01-01

    Computed tomography (CT) should be the imaging method of choice following plain chest radiographs when a suspected thymic abnormality requires further evaluation. Based upon a six-year experience, including the evaluation of 25 patients with thymic pathology, CT was found useful in suggesting or excluding a diagnosis of thymoma and in distinguishing thymic hyperplasis from thymoma in patients with myasthenia gravis. The thickness of the thymic lobes determined by CT was found to be a more accurate indicator of infiltrative disease (thymic hyperplasia and lymphoma) than the width. CT was helpful in differentiating benign thymic cysts from solid tumors, and in defining the extent of a thymic neoplasms. On occasion, CT may suggest the specific histologic nature of a thymic lesion.

  14. Computed tomography in intracranial supratentorial osteochondroma

    SciTech Connect

    Matz, S.; Israeli, Y.; Shalit, M.N.; Cohen, M.L.

    1981-02-01

    A case of a huge intracranial frontoparietal osteochondroma in a 20-year-old man is reported. The presenting symptoms were headache, vomiting, and blurred vision. Apart from papilledema, no other abnormal neurological signs were present. A specific preoperative diagnosis could not be reached from the information provided by plain skull films, angiography, and radionuclide scan. The findings on computed tomography were those of a high density mass interspersed with small foci of lower densities, producing a honeycomb appearance, and surrounded by deposits of nodular calcification. The postcontrast scan showed a moderate degree of enhancement with preservation of the precontrast honeycomb pattern. These particular features may enable a correct preoperative histological diagnosis to be offered with a high degree of probability.

  15. Computed tomography of osteosarcoma after intraarterial chemotherapy

    SciTech Connect

    Shirkhoda, A.; Jaffe, N.; Wallace, S.; Ayala, A.; Lindell, M.M.; Zornoza, J.

    1985-01-01

    The response to intraarterial cis-diamminedichloroplatinum II (CDP) chemotherapy was evaluated by computed tomography (CT) in 33 patients with pathologically proved osteosarcoma of the long or flat bones. Twenty-one of the 33 patients had a CT scan before chemotherapy was started. In the other 12 patients, a CT scan was obtained after at least two courses of treatment, and additional studies were performed during the course of therapy. In those patients responding to treatment, the posttherapy scan revealed a remarkable decrease or complete disappearance of the associated soft-tissue mass and clear reestablishment of the fat planes between the muscle bundles that had been obscured. There was sharp definition of the peripheral margins of the calcified healing neoplasm, and the calcification in the healing tumor could be differentiated easily from that of the original bone neoplasm. CT was more accurate than conventional studies in detecting healing process and diagnosis of remission.

  16. Myocardial hypoperfusion on conventional contrast computed tomography.

    PubMed

    Ching, Shing; Chung, Tak Shun

    2015-10-01

    Non–electrocardiogram (ECG)–gated contrast computed tomography (CT) is commonly performed to exclude aortic dissection in chest pain patients. Besides evaluating the aorta for dissection flap, attention should be paid to the myocardium for areas of hypoenhancement that may suggest ischemia. Current models of multidetector CT enable assessment of myocardial perfusion with minimal motion artifact even without ECG gating. Transmural hypoenhancement with preserved wall thickness in a coronary distribution is highly specific for acute myocardial infarction. We report 2 cases of acute chest pain with initial nondiagnostic studies that underwent CT aortogram to exclude dissection. Instead, the CT showed myocardial hypoenhancement in left anterior descending artery territory. Myocardial hypoenhancement occurred before ST-segment elevation on ECG, suggesting that recognition of this important finding may lead to earlier revascularization decisions. PMID:26321167

  17. Method and device for computed tomography

    SciTech Connect

    Lux, P.W.; Op De Beek, J.C.A.; Van Leiden, H.F.

    1983-09-06

    A computer tomography device in which the detectors are asymmetrically arranged with respect to the connecting line between the X-ray source, the center of rotation of the source, and the detectors is disclosed. The detector device produces an incomplete profile of measuring values which are supplemented with ''zeros'' during processing in order to form a number of measuring values of a complete profile. In order to avoid artefacts which are produced by the acute transients between measuring values and ''zeros'', a number of measuring values adjoining the acute transients are projected around the center of rotation and multipled by a factor so that from the zeros a smoothly increasing series of adapted measuring values is obtained.

  18. Computed tomography on small explosive parts

    SciTech Connect

    Ryon, R.W.

    1994-05-01

    We have investigated three small explosive parts for the Pantex Plant in Amarillo, Texas using computed tomography (CT). A medium resolution, fan beam system was used to test imaging capabilities for small holes drilled into one of the parts, and to identify any inhomogeneities, cracks, voids, and inclusions if present in the other two parts. This system provides volumetric imaging. Its information is qualitative in that is allows us to see interior features but it cannot provide quantitative attenuation data. A second part of the investigation was to perform effective atomic number computed tomography on the parts using energy dispersive spectroscopy methods. We wanted to experimentally identify the {open_quotes}average{close_quotes} chemical composition of the materials in the explosive and its shell and to detect any possible inhomogeneities in composition. A single beam, nuclear spectroscopy based system was used for this work. The radiation source was a silver anode x-ray tube. By measuring x-ray attenuation at specific energies (characteristic lines and narrow bands of continuum) we are able to quantitatively determine linear attenuation coefficients. By using ratios of such measurements, density cancels out and we effectively have ratios of mass attenuation coefficients. Through a look-up scheme of mass attenuation coefficients for different elements, we can determine the weighted average chemical composition, as averaged by x-ray attenuation. We call this averaged composition the effective atomic number ({open_quotes}Z{sub eff}{close_quotes}). We thereby obtain cross sectional images of a parameter related to the averaged chemistry of the object. Such images and the underlying data can reveal, for instance, segregation of explosive and binder.

  19. Giant intracranial aneurysms: rapid sequential computed tomography

    SciTech Connect

    Pinto, R.S.; Cohen, W.A.; Kricheff, I.I.; Redington, R.W.; Berninger, W.H.

    1982-11-01

    Giant intracranial aneurysms often present as mass lesions rather than with subarachnoid hemorrhage. Routine computed tomographic (CT) scans with contrast material will generally detect them, but erroneous diagnosis of basal meningioma is possible. Rapid sequential scanning (dynamic CT) after bolus injection of 40 ml of Renografin-76 can conclusively demonstrate an intracranial aneurysm, differentiating it from other lesions by transit-time analysis of the passage of contrast medium. In five patients, the dynamics of contrast bolus transit in aneurysms were consistently different from the dynamics in pituitary tumors, craniopharyngiomas, and meningiomas, thereby allowing a specific diagnosis. Dynamic CT was also useful after treatment of the aneurysms by carotid artery ligation and may be used as an alternative to angiographic evaluation in determining luminal patency or thrombosis.

  20. Depiction of ventriculoperitoneal shunt obstruction with single-photon emission computed tomography/computed tomography

    PubMed Central

    Aksoy, Sabire Yılmaz; Vatankulu, Betül; Uslu, Lebriz; Halac, Metin

    2016-01-01

    An 83-year-old male patient with ventriculoperitoneal shunt underwent radionuclide shunt study using single-photon emission computed tomography/computed tomography (SPECT/CT) to evaluate the shunt patency. The planar images showed activity at the cranial region and spinal canal but no significant activity at the peritoneal cavity. However, SPECT/CT images clearly demonstrated accumulation of activity at the superior part of bifurcation level with no activity at the distal end of shunt as well as no spilling of radiotracer into the peritoneal cavity indicating shunt obstruction. SPECT/CT makes the interpretation of radionuclide shunt study more accurate and easier as compared with traditional planar images. PMID:27385906

  1. 21 CFR 892.1200 - Emission computed tomography system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Emission computed tomography system. 892.1200 Section 892.1200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1200 Emission computed tomography system. (a) Identification. An...

  2. 21 CFR 1020.33 - Computed tomography (CT) equipment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Computed tomography (CT) equipment. 1020.33 Section 1020.33 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) RADIOLOGICAL HEALTH PERFORMANCE STANDARDS FOR IONIZING RADIATION EMITTING PRODUCTS § 1020.33 Computed tomography (CT) equipment....

  3. Computed tomography and magnetic resonance findings in lipoid pneumonia.

    PubMed Central

    Bréchot, J M; Buy, J N; Laaban, J P; Rochemaure, J

    1991-01-01

    A case of exogenous lipoid pneumonia was documented by computed tomography and magnetic resonance imaging. Although strongly suggesting the presence of fat on T1 weighted images, magnetic resonance does not produce images specific for this condition. Computed tomography is the best imaging modality for its diagnosis. Images PMID:1750024

  4. Terahertz Computed Tomography of NASA Thermal Protection System Materials

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Reyes-Rodriguez, S.; Zimdars, D. A.; Rauser, R. W.; Ussery, W. W.

    2011-01-01

    A terahertz axial computed tomography system has been developed that uses time domain measurements in order to form cross-sectional image slices and three-dimensional volume renderings of terahertz-transparent materials. The system can inspect samples as large as 0.0283 cubic meters (1 cubic foot) with no safety concerns as for x-ray computed tomography. In this study, the system is evaluated for its ability to detect and characterize flat bottom holes, drilled holes, and embedded voids in foam materials utilized as thermal protection on the external fuel tanks for the Space Shuttle. X-ray micro-computed tomography was also performed on the samples to compare against the terahertz computed tomography results and better define embedded voids. Limits of detectability based on depth and size for the samples used in this study are loosely defined. Image sharpness and morphology characterization ability for terahertz computed tomography are qualitatively described.

  5. Computational Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Chung, T. J.

    2002-03-01

    Computational fluid dynamics (CFD) techniques are used to study and solve complex fluid flow and heat transfer problems. This comprehensive text ranges from elementary concepts for the beginner to state-of-the-art CFD for the practitioner. It discusses and illustrates the basic principles of finite difference (FD), finite element (FE), and finite volume (FV) methods, with step-by-step hand calculations. Chapters go on to examine structured and unstructured grids, adaptive methods, computing techniques, and parallel processing. Finally, the author describes a variety of practical applications to problems in turbulence, reacting flows and combustion, acoustics, combined mode radiative heat transfer, multiphase flows, electromagnetic fields, and relativistic astrophysical flows. Students and practitioners--particularly in mechanical, aerospace, chemical, and civil engineering--will use this authoritative text to learn about and apply numerical techniques to the solution of fluid dynamics problems.

  6. Computational fluid dynamics research

    NASA Technical Reports Server (NTRS)

    Chandra, Suresh; Jones, Kenneth; Hassan, Hassan; Mcrae, David Scott

    1992-01-01

    The focus of research in the computational fluid dynamics (CFD) area is two fold: (1) to develop new approaches for turbulence modeling so that high speed compressible flows can be studied for applications to entry and re-entry flows; and (2) to perform research to improve CFD algorithm accuracy and efficiency for high speed flows. Research activities, faculty and student participation, publications, and financial information are outlined.

  7. Texture classification of lung computed tomography images

    NASA Astrophysics Data System (ADS)

    Pheng, Hang See; Shamsuddin, Siti M.

    2013-03-01

    Current development of algorithms in computer-aided diagnosis (CAD) scheme is growing rapidly to assist the radiologist in medical image interpretation. Texture analysis of computed tomography (CT) scans is one of important preliminary stage in the computerized detection system and classification for lung cancer. Among different types of images features analysis, Haralick texture with variety of statistical measures has been used widely in image texture description. The extraction of texture feature values is essential to be used by a CAD especially in classification of the normal and abnormal tissue on the cross sectional CT images. This paper aims to compare experimental results using texture extraction and different machine leaning methods in the classification normal and abnormal tissues through lung CT images. The machine learning methods involve in this assessment are Artificial Immune Recognition System (AIRS), Naive Bayes, Decision Tree (J48) and Backpropagation Neural Network. AIRS is found to provide high accuracy (99.2%) and sensitivity (98.0%) in the assessment. For experiments and testing purpose, publicly available datasets in the Reference Image Database to Evaluate Therapy Response (RIDER) are used as study cases.

  8. Computed Tomography in Diagnosis of Admantinoma

    PubMed Central

    Misra, Akansha; Misra, Deepankar; Rai, Shalu; Panjwani, Sapna; Ranjan, Vikash; Prabhat, Mukul; Bhalla, Kanika; Bhatnagar, Puneet

    2015-01-01

    Context: Admantinoma is second most common benign odontogenic tumor which clinically appears as an aggressive odontogenic tumor, often asymptomatic and slow growing, associated with symptoms such as swelling, dental malocclusion, pain, and paresthesia of the affected area. The radiographic appearance may vary from unilocular to multilocular radiolucencies, imparting a characteristic honey comb, soap bubble appearance or may resemble a caricature of spider. Case Report: This report highlights the importance of conventional and advanced imaging in the diagnosis of large and invasive lesions. Patient reported with complaint of swelling in jaw, which progressively increased; and was found to be bony hard, both intra- and extraorally. Radiographs revealed large multilocular radiolucency on left body and ramus of mandible with soap bubble pattern and knife edged root resorption. Computed tomographic examination evaluated the extent of the lesion, internal structure, and relation to adjacent structures; further a reconstructed image was obtained to evaluate extent of destruction in three dimensions. Conclusion: Computed tomography has an important role in the diagnosis and treatment planning is imperative as it is superior in revealing the cortical destruction and extension into the neighboring soft tissues than conventional radiography. PMID:26110136

  9. Computational reacting gas dynamics

    NASA Technical Reports Server (NTRS)

    Lam, S. H.

    1993-01-01

    In the study of high speed flows at high altitudes, such as that encountered by re-entry spacecrafts, the interaction of chemical reactions and other non-equilibrium processes in the flow field with the gas dynamics is crucial. Generally speaking, problems of this level of complexity must resort to numerical methods for solutions, using sophisticated computational fluid dynamics (CFD) codes. The difficulties introduced by reacting gas dynamics can be classified into three distinct headings: (1) the usually inadequate knowledge of the reaction rate coefficients in the non-equilibrium reaction system; (2) the vastly larger number of unknowns involved in the computation and the expected stiffness of the equations; and (3) the interpretation of the detailed reacting CFD numerical results. The research performed accepts the premise that reacting flows of practical interest in the future will in general be too complex or 'untractable' for traditional analytical developments. The power of modern computers must be exploited. However, instead of focusing solely on the construction of numerical solutions of full-model equations, attention is also directed to the 'derivation' of the simplified model from the given full-model. In other words, the present research aims to utilize computations to do tasks which have traditionally been done by skilled theoreticians: to reduce an originally complex full-model system into an approximate but otherwise equivalent simplified model system. The tacit assumption is that once the appropriate simplified model is derived, the interpretation of the detailed numerical reacting CFD numerical results will become much easier. The approach of the research is called computational singular perturbation (CSP).

  10. Malignant uveal melanoma and similar lesions studied by computed tomography

    SciTech Connect

    Mafee, M.F.; Peyman, G.A.; McKusick, M.A.

    1985-08-01

    Forty-four patients with intraocular disease were studied by computed tomography (CT); in 19 cases malignant uveal melanoma was considered the likely diagnosis. CT proved to be accurate in determining the location and size of uveal melanomas, demonstrating scleral invasion, and differentiating melanoma from choroidal detachment or angioma, toxocariasis, and senile macular degeneration. On CT, uveal melanomas appeared as hyperdense lesions with slight to moderate contrast enhancement. Tumors thinner than 2 mm could not be seen. Using dynamic CT, the authors noted moderate peak amplitude, normal or delayed tissue transit time, and persistently elevated washout phase (downslope), indicating increased permeability as the result of an impaired tumor blood barrier. Histological types of uveal melanoma could not be differentiated on the basis of circulatory patterns. Dynamic CT may be useful in distinguishing uveal melanoma from choroidal hemangioma or hematoma.

  11. Dedicated breast computed tomography: Basic aspects

    SciTech Connect

    Sarno, Antonio; Mettivier, Giovanni Russo, Paolo

    2015-06-15

    X-ray mammography of the compressed breast is well recognized as the “gold standard” for early detection of breast cancer, but its performance is not ideal. One limitation of screening mammography is tissue superposition, particularly for dense breasts. Since 2001, several research groups in the USA and in the European Union have developed computed tomography (CT) systems with digital detector technology dedicated to x-ray imaging of the uncompressed breast (breast CT or BCT) for breast cancer screening and diagnosis. This CT technology—tracing back to initial studies in the 1970s—allows some of the limitations of mammography to be overcome, keeping the levels of radiation dose to the radiosensitive breast glandular tissue similar to that of two-view mammography for the same breast size and composition. This paper presents an evaluation of the research efforts carried out in the invention, development, and improvement of BCT with dedicated scanners with state-of-the-art technology, including initial steps toward commercialization, after more than a decade of R and D in the laboratory and/or in the clinic. The intended focus here is on the technological/engineering aspects of BCT and on outlining advantages and limitations as reported in the related literature. Prospects for future research in this field are discussed.

  12. Intraperitoneal tuberculous abscess: Computed tomography features

    PubMed Central

    Dong, Peng; Chen, Jing-Jing; Wang, Xi-Zhen; Wang, Ya-Qin

    2015-01-01

    AIM: To evaluate the computed tomography (CT) features of intraperitoneal tuberculous abscess (IPTA). METHODS: Eight patients with IPTA confirmed by pathology were analyzed retrospectively. The clinical symptoms, medical images, and surgical findings were evaluated. Involvement of the intestine, peritoneum, viscera, and lymph nodes was also assessed. RESULTS: All 8 patients had a history of abdominal discomfort for 1 to 6 mo. Physical examination revealed a palpable abdominal mass in 6 patients. Three patients had no evidence of pulmonary tuberculosis (TB). All IPTAs (11 abscesses) were seen as a multiseptated, peripherally enhanced, hypodense mass with enlarged, rim-enhanced lymph nodes. The largest abscess diameter ranged from 4.5 cm to 12.2 cm. CT showed 2 types of IPTA: Lymph node fusion and encapsulation. Of the 8 patients, one had liver tuberculosis and one had splenic and ovarian tuberculosis. Two cases showed involvement of the terminal ileum and ileocecal junction. Ascites were found in 4 cases. Three patients had peritonitis and mesenteritis. Three patients showed involvement of the omentum. Three patients had histological evidence of caseating granuloma, and 5 had histological evidence of acid-fast bacilli. CONCLUSION: CT is crucial in the detection and characterization of IPTA. Certain CT findings are necessary for correct diagnosis. PMID:26435779

  13. Portable Digital Radiography and Computed Tomography Manual

    SciTech Connect

    Not Available

    2007-11-01

    This user manual describes the function and use of the portable digital radiography and computed tomography (DRCT) scanner. The manual gives a general overview of x-ray imaging systems along with a description of the DRCT system. An inventory of the all the system components, organized by shipping container, is also included. In addition, detailed, step-by-step procedures are provided for all of the exercises necessary for a novice user to successfully collect digital radiographs and tomographic images of an object, including instructions on system assembly and detector calibration and system alignment. There is also a short section covering the limited system care and maintenance needs. Descriptions of the included software packages, the DRCT Digital Imager used for system operation, and the DRCT Image Processing Interface used for image viewing and tomographic data reconstruction are given in the appendixes. The appendixes also include a cheat sheet for more experienced users, a listing of known system problems and how to mitigate them, and an inventory check-off sheet suitable for copying and including with the machine for shipment purposes.

  14. Shape threat detection via adaptive computed tomography

    NASA Astrophysics Data System (ADS)

    Masoudi, Ahmad; Thamvichai, Ratchaneekorn; Neifeld, Mark A.

    2016-05-01

    X-ray Computed Tomography (CT) is used widely for screening purposes. Conventional x-ray threat detection systems employ image reconstruction and segmentation algorithms prior to making threat/no-threat decisions. We find that in many cases these pre-processing steps can degrade detection performance. Therefore in this work we will investigate methods that operate directly on the CT measurements. We analyze a fixed-gantry system containing 25 x-ray sources and 2200 photon counting detectors. We present a new method for improving threat detection performance. This new method is a so-called greedy adaptive algorithm which at each time step uses information from previous measurements to design the next measurement. We utilize sequential hypothesis testing (SHT) in order to derive both the optimal "next measurement" and the stopping criterion to insure a target probability of error Pe. We find that selecting the next x-ray source according to such a greedy adaptive algorithm, we can reduce Pe by a factor of 42.4× relative to the conventional measurement sequence employing all 25 sources in sequence.

  15. Beam Hardening Corrections in Quantitative Computed Tomography

    SciTech Connect

    Vedula, Venumadhav; Venugopal, Manoharan; Raghu, C.; Pandey, Pramod

    2007-03-21

    Volumetric computed tomography (VCT) is the emerging 3D NDE inspection technique that gives highest throughput and better image quality. Industrial components in general demands higher x-ray energy for inspection for which polychromatic x-ray sources are used in common. Polychromatic nature of the x-rays gives rise to non-linear effects in the VCT projection data measurements called to be the beam hardening (BH) effects. BH produces prominent artifacts in the reconstructed images thereby deteriorating the image quality. Quantitative analysis such as density quantification, dimensional analysis etc., becomes difficult with the presence of these artifacts. This paper describes the BH correction using preprocessing technique for the homogeneous materials. Selection of effective energy at which the monoenergetic linear attenuation coefficient of a particular material equals to that of the polyenergetic beam is critical for BH correction. Various methods to determine the effective energy and their consequence in the quantitative measurements have been investigated in the present study. In this paper, BH corrections for heterogeneous materials have also been explored.

  16. Three energy computed tomography with synchrotron radiation

    SciTech Connect

    Menk, R.H.; Thomlinson, W.; Zhong, Z.; Charvet, A.M.; Arfelli, F. |; Chapman, L.

    1997-09-01

    Preliminary experiments for digital subtraction computed tomography (CT) at the K-edge of iodine (33.1 keV) were carried out at SMERF (Synchrotron Medical Research Facility X17B2) at the National Synchrotron Light Source, Brookhaven National Laboratory. The major goal was to evaluate the availability of this kind of imaging for in vivo neurological studies. Using the transvenous coronary angiography system, CT images of various samples and phantoms were taken simultaneously at two slightly different energies bracketing the K-absorption edge of iodine. The logarithmic subtraction of the two images resulted in the contrast enhancement of iodine filled structures. An additional CT image was taken at 99.57 keV (second harmonic of the fundamental wave). The third energy allowed the calculation of absolute iodine, tissue and bone images by means of a matrix inversion. A spatial resolution of 0.8 LP/mm was measured in single energy images and iodine concentrations down to 0.082 mg/ml in a 1/4 diameter detail were visible in the reconstructed subtraction image.

  17. A Detector for Proton Computed Tomography

    SciTech Connect

    Blazey, G.; et al.,

    2013-12-06

    Radiation therapy is a widely recognized treatment for cancer. Energetic protons have distinct features that set them apart from photons and make them desirable for cancer therapy as well as medical imaging. The clinical interest in heavy ion therapy is due to the fact that ions deposit almost all of their energy in a sharp peak – the Bragg peak- at the very end of their path. Proton beams can be used to precisely localize a tumor and deliver an exact dose to the tumor with small doses to the surrounding tissue. Proton computed tomography (pCT) provides direct information on the location on the target tumor, and avoids position uncertainty caused by treatment planning based on imaging with X-ray CT. The pCT project goal is to measure and reconstruct the proton relative stopping power distribution directly in situ. To ensure the full advantage of cancer treatment with 200 MeV proton beams, pCT must be realized.

  18. Cosine fitting radiography and computed tomography

    NASA Astrophysics Data System (ADS)

    Li, Pan-Yun; Zhang, Kai; Huang, Wan-Xia; Yuan, Qing-Xi; Wang, Yan; Ju, Zai-Qiang; Wu, Zi-Yu; Zhu, Pei-Ping

    2015-06-01

    A new method in diffraction-enhanced imaging computed tomography (DEI-CT) that follows the idea developed by Chapman et al. [Chapman D, Thomlinson W, Johnston R E, Washburn D, Pisano E, Gmur N, Zhong Z, Menk R, Arfelli F and Sayers D 1997 Phys. Med. Biol. 42 2015] in 1997 is proposed in this paper. Merged with a “reverse projections” algorithm, only two sets of projection datasets at two defined orientations of the analyzer crystal are needed to reconstruct the linear absorption coefficient, the decrement of the real part of the refractive index and the linear scattering coefficient of the sample. Not only does this method reduce the delivered dose to the sample without degrading the image quality, but, compared with the existing DEI-CT approaches, it simplifies data-acquisition procedures. Experimental results confirm the reliability of this new method for DEI-CT applications. Project supported by the National Basic Research Program of China (Grant No. 2012CB825800), the National Natural Science Foundation of China (Grant Nos. 11205189, 11375225, and U1332109), the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos. KJCX2-YW-N42, Y4545320Y2, and 542014IHEPZZBS50659).

  19. Computed tomography imaging and angiography - principles.

    PubMed

    Kamalian, Shervin; Lev, Michael H; Gupta, Rajiv

    2016-01-01

    The evaluation of patients with diverse neurologic disorders was forever changed in the summer of 1973, when the first commercial computed tomography (CT) scanners were introduced. Until then, the detection and characterization of intracranial or spinal lesions could only be inferred by limited spatial resolution radioisotope scans, or by the patterns of tissue and vascular displacement on invasive pneumoencaphalography and direct carotid puncture catheter arteriography. Even the earliest-generation CT scanners - which required tens of minutes for the acquisition and reconstruction of low-resolution images (128×128 matrix) - could, based on density, noninvasively distinguish infarct, hemorrhage, and other mass lesions with unprecedented accuracy. Iodinated, intravenous contrast added further sensitivity and specificity in regions of blood-brain barrier breakdown. The advent of rapid multidetector row CT scanning in the early 1990s created renewed enthusiasm for CT, with CT angiography largely replacing direct catheter angiography. More recently, iterative reconstruction postprocessing techniques have made possible high spatial resolution, reduced noise, very low radiation dose CT scanning. The speed, spatial resolution, contrast resolution, and low radiation dose capability of present-day scanners have also facilitated dual-energy imaging which, like magnetic resonance imaging, for the first time, has allowed tissue-specific CT imaging characterization of intracranial pathology. PMID:27432657

  20. Industrial computed tomography image size measurement

    NASA Astrophysics Data System (ADS)

    Ping, Chen; Jin-Xiao, Pan; Bin, Liu

    2009-09-01

    As one of the most useful modern detection technologies, Industrial Computed Tomography (ICT) image size measurement can correctly non-destructively measure the size of workpieces' inner construction, and it is considered as the standard for quality assurance and reverse engineering. In view of the advantages and disadvantages compared to conventional methods, this paper improves the precision of image size measurement with a new algorithm that uses an approximate function to describe edge degradation. First, this algorithm constructs the approximate function and determines the optimal point of edge detection, based on image intensity and inflexions. Then, in order to accurately extract the image edge, this algorithm is used to revise the primary image, completing construction of the CT image. Excellent results are obtained from simulations and experiments. The experimental results indicate that the relative error is 2% for the CT image when the step evolution of the image edge is pooled. The relative error of this method is decreased by as much as 1.5% compared to wavelet transformation and ridgelet transformation. Therefore, this new algorithm demonstrates increased effectiveness in extracting an accurate measurement of the CT image edge.

  1. Perfusion computed tomography in renal cell carcinoma.

    PubMed

    Das, Chandan J; Thingujam, Usha; Panda, Ananya; Sharma, Sanjay; Gupta, Arun Kumar

    2015-07-28

    Various imaging modalities are available for the diagnosis, staging and response evaluation of patients with renal cell carcinoma (RCC). While contrast enhanced computed tomography (CT) is used as the standard of imaging for size, morphological evaluation and response assessment in RCC, a new functional imaging technique like perfusion CT (pCT), goes down to the molecular level and provides new perspectives in imaging of RCC. pCT depicts regional tumor perfusion and vascular permeability which are indirect parameters of tumor angiogenesis and thereby provides vital information regarding tumor microenvironment. Also response evaluation using pCT may predate the size criteria used in Response Evaluation Criteria in Solid Tumors, as changes in the perfusion occurs earlier following tissue kinase inhibitors before any actual change in size. This may potentially help in predicting prognosis, better selection of therapy and more accurate and better response evaluation in patients with RCC. This article describes the techniques and role of pCT in staging and response assessment in patients with RCCs. PMID:26217456

  2. Electrode Models for Electric Current Computed Tomography

    PubMed Central

    CHENG, KUO-SHENG; ISAACSON, DAVID; NEWELL, J. C.; GISSER, DAVID G.

    2016-01-01

    This paper develops a mathematical model for the physical properties of electrodes suitable for use in electric current computed tomography (ECCT). The model includes the effects of discretization, shunt, and contact impedance. The complete model was validated by experiment. Bath resistivities of 284.0, 139.7, 62.3, 29.5 Ω · cm were studied. Values of “effective” contact impedance z used in the numerical approximations were 58.0, 35.0, 15.0, and 7.5 Ω · cm2, respectively. Agreement between the calculated and experimentally measured values was excellent throughout the range of bath conductivities studied. It is desirable in electrical impedance imaging systems to model the observed voltages to the same precision as they are measured in order to be able to make the highest resolution reconstructions of the internal conductivity that the measurement precision allows. The complete electrode model, which includes the effects of discretization of the current pattern, the shunt effect due to the highly conductive electrode material, and the effect of an “effective” contact impedance, allows calculation of the voltages due to any current pattern applied to a homogeneous resistivity field. PMID:2777280

  3. Quantitative investigations of megavoltage computed tomography

    NASA Astrophysics Data System (ADS)

    Rogers, Myron; Kerr, Andrew; Salomons, Greg; Schreiner, L. John

    2005-04-01

    Megavoltage computed tomography (MVCT) has been an active area of research and development in image guided radiation therapy. We have been investigating a particular implementation of MVCT in conjunction with studies of the potential for tomotherapy with a Cobalt-60 radiation source. In this paper, we present results comparing MVCT using a Co-60 source and a 4 MV linear accelerator to conventional kVCT imaging. The Co-60 and linac MVCT measurements were obtained with a first generation benchtop CT imager; the KVCT measurements were obtained using a Philips AcQSim CT Simulator). Phantoms containing various inserts ranging in density from air, through lung, soft tissue and bone equivalent materials and extending to high atomic number metals were imaged with the three modalities. The results enable characterization of image artifacts, CT number linearity and beam hardening. The MVCT images have sufficient contrast that soft tissue regions with 2.8% difference in electron density can be visualized. In MVCT, a linear relationship between CT numbers and electron densities extends to materials with Z ~ 60. In the 4MV CT imaging there is a position dependence of the CT numbers within a uniform water phantom, which is absent in Co-60 CT images, indicating the presence of beam hardening artifacts in the linac MVCT images. The differences between kVCT and MVCT will be discussed considering the variation of the photon interactions dominating the images. Our investigations indicate that MVCT has properties that may potentially extend its utility beyond radiation therapy.

  4. Modelling the penumbra in Computed Tomography1

    PubMed Central

    Kueh, Audrey; Warnett, Jason M.; Gibbons, Gregory J.; Brettschneider, Julia; Nichols, Thomas E.; Williams, Mark A.; Kendall, Wilfrid S.

    2016-01-01

    BACKGROUND: In computed tomography (CT), the spot geometry is one of the main sources of error in CT images. Since X-rays do not arise from a point source, artefacts are produced. In particular there is a penumbra effect, leading to poorly defined edges within a reconstructed volume. Penumbra models can be simulated given a fixed spot geometry and the known experimental setup. OBJECTIVE: This paper proposes to use a penumbra model, derived from Beer’s law, both to confirm spot geometry from penumbra data, and to quantify blurring in the image. METHODS: Two models for the spot geometry are considered; one consists of a single Gaussian spot, the other is a mixture model consisting of a Gaussian spot together with a larger uniform spot. RESULTS: The model consisting of a single Gaussian spot has a poor fit at the boundary. The mixture model (which adds a larger uniform spot) exhibits a much improved fit. The parameters corresponding to the uniform spot are similar across all powers, and further experiments suggest that the uniform spot produces only soft X-rays of relatively low-energy. CONCLUSIONS: Thus, the precision of radiographs can be estimated from the penumbra effect in the image. The use of a thin copper filter reduces the size of the effective penumbra. PMID:27232198

  5. Computed tomography experiments of Pantex high explosives

    NASA Astrophysics Data System (ADS)

    Perkins, D. E.; Martz, H. E.; Hester, L. O.; Sobczak, G.; Pratt, C. L.

    1992-04-01

    X-ray computed tomography is an advanced imaging technique which provide three-dimensional nondestructive characterization of materials, components and assemblies. The CT Project group at Lawrence Livermore National Laboratory (LLNL) and the Pantex Plant are cooperating to examine the use of CT technology to inspect and characterize high-explosives pressings (e.g., PBX-9502, LX-10-2). High-explosives pressings manufactured by Pantex must be characterized prior to assembling into weapons systems; a nondestructive examination of all assembly parts would be preferable to the current sampling and destructive testing. The earlier in the processing cycle this can be done the more cost effective it will be. We have performed experiments that show that this characterization can be performed at the pressed billet stage using CT. We have detected 2-mm inclusions in a 15-cm diameter billet and 3.5-mm voids in a 20-cm diameter billet. Based on these results we show calculations that can be used to design production CT systems for characterization of high-explosives.

  6. Important Advances in Technology and Unique Applications to Cardiovascular Computed Tomography

    PubMed Central

    Chaikriangkrai, Kongkiat; Choi, Su Yeon; Nabi, Faisal; Chang, Su Min

    2014-01-01

    For the past decade, multidetector cardiac computed tomography and its main application, coronary computed tomography angiography, have been established as a noninvasive technique for anatomical assessment of coronary arteries. This new era of coronary artery evaluation by coronary computed tomography angiography has arisen from the rapid advancement in computed tomography technology, which has led to massive diagnostic and prognostic clinical studies in various patient populations. This article gives a brief overview of current multidetector cardiac computed tomography systems, developing cardiac computed tomography technologies in both hardware and software fields, innovative radiation exposure reduction measures, multidetector cardiac computed tomography functional studies, and their newer clinical applications beyond coronary computed tomography angiography. PMID:25574342

  7. Important advances in technology and unique applications to cardiovascular computed tomography.

    PubMed

    Chaikriangkrai, Kongkiat; Choi, Su Yeon; Nabi, Faisal; Chang, Su Min

    2014-01-01

    For the past decade, multidetector cardiac computed tomography and its main application, coronary computed tomography angiography, have been established as a noninvasive technique for anatomical assessment of coronary arteries. This new era of coronary artery evaluation by coronary computed tomography angiography has arisen from the rapid advancement in computed tomography technology, which has led to massive diagnostic and prognostic clinical studies in various patient populations. This article gives a brief overview of current multidetector cardiac computed tomography systems, developing cardiac computed tomography technologies in both hardware and software fields, innovative radiation exposure reduction measures, multidetector cardiac computed tomography functional studies, and their newer clinical applications beyond coronary computed tomography angiography. PMID:25574342

  8. Acute Calculous Cholecystitis Missed on Computed Tomography and Ultrasound but Diagnosed with Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography

    PubMed Central

    Aparici, Carina Mari; Win, Aung Zaw

    2016-01-01

    We present a case of a 69-year-old patient who underwent ascending aortic aneurysm repair with aortic valve replacement. On postsurgical day 12, he developed leukocytosis and low-grade fevers. The chest computed tomography (CT) showed a periaortic hematoma which represents a postsurgical change from aortic aneurysm repair, and a small pericardial effusion. The abdominal ultrasound showed cholelithiasis without any sign of cholecystitis. Finally, a fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT examination was ordered to find the cause of fever of unknown origin, and it showed increased FDG uptake in the gallbladder wall, with no uptake in the lumen. FDG-PET/CT can diagnose acute cholecystitis in patients with nonspecific clinical symptoms and laboratory results. PMID:27625897

  9. Acute Calculous Cholecystitis Missed on Computed Tomography and Ultrasound but Diagnosed with Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography.

    PubMed

    Aparici, Carina Mari; Win, Aung Zaw

    2016-01-01

    We present a case of a 69-year-old patient who underwent ascending aortic aneurysm repair with aortic valve replacement. On postsurgical day 12, he developed leukocytosis and low-grade fevers. The chest computed tomography (CT) showed a periaortic hematoma which represents a postsurgical change from aortic aneurysm repair, and a small pericardial effusion. The abdominal ultrasound showed cholelithiasis without any sign of cholecystitis. Finally, a fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT examination was ordered to find the cause of fever of unknown origin, and it showed increased FDG uptake in the gallbladder wall, with no uptake in the lumen. FDG-PET/CT can diagnose acute cholecystitis in patients with nonspecific clinical symptoms and laboratory results. PMID:27625897

  10. Diagnosis of sacral perineural cysts by computed tomography.

    PubMed

    Tabas, J H; Deeb, Z L

    1986-07-01

    Three cases of sacral perineural cysts associated with chronic low-back pain are described with their myelography, computed tomography, and plain film findings. Significant findings include multiple cystic dilatations of lumbosacral nerve root sheaths, enlargement of the sacral foramina by masses isodense with cerebrospinal fluid, and asymmetric epidural fat distribution. Recognition of these findings on unenhanced computed tomography scans should preclude further evaluation by myelography and intrathecal metrizamide (Amipaque) computed tomography. These cysts are usually not the primary cause of back and leg pain. PMID:2942338

  11. Abdominal alterations in disseminated paracoccidioidomycosis: computed tomography findings*

    PubMed Central

    Vermelho, Marli Batista Fernandes; Correia, Ademir Silva; Michailowsky, Tânia Cibele de Almeida; Suzart, Elizete Kazumi Kuniyoshi; Ibanês, Aline Santos; Almeida, Lanamar Aparecida; Khoury, Zarifa; Barba, Mário Flores

    2015-01-01

    Objective To evaluate the incidence and spectrum of abdominal computed tomography imaging findings in patients with paracoccidioidomycosis. Materials and Methods Retrospective analysis of abdominal computed tomography images of 26 patients with disseminated paracoccidioidomycosis. Results Abnormal abdominal tomographic findings were observed in 18 patients (69.2%), while no significant finding was observed in the other 8 (30.8%) patients. Conclusion Computed tomography has demonstrated to play a relevant role in the screening and detection of abdominal abnormalities in patients with disseminated paracoccidioidomycosis. PMID:25987748

  12. Non-uniform projection angle processing in computed tomography

    NASA Astrophysics Data System (ADS)

    Simo, Yanic; Tayag, Tristan J.

    In this paper, we present a novel approach for the collection of computed tomography data. Non-uniform increments in projection angle may be used to reduce data acquisition time with minimal reduction in the accuracy of the reconstructed profile. The key is to exploit those projection angles which correspond to regions where the object contains few high spatial frequency components. This technique is applicable to optical phase computed tomography, as well as X-ray computed tomography. We present simulation results on intraocular lenses used in cataract surgery.

  13. Simulation study of respiratory-induced errors in cardiac positron emission tomography/computed tomography

    SciTech Connect

    Fitzpatrick, Gianna M.; Wells, R. Glenn

    2006-08-15

    Heart disease is a leading killer in Canada and positron emission tomography (PET) provides clinicians with in vivo metabolic information for diagnosing heart disease. Transmission data are usually acquired with {sup 68}Ge, although the advent of PET/CT scanners has made computed tomography (CT) an alternative option. The fast data acquisition of CT compared to PET may cause potential misregistration problems, leading to inaccurate attenuation correction (AC). Using Monte Carlo simulations and an anthropomorphic dynamic computer phantom, this study determines the magnitude and location of respiratory-induced errors in radioactivity uptake measured in cardiac PET/CT. A homogeneous tracer distribution in the heart was considered. The AC was based on (1) a time-averaged attenuation map (2) CT maps from a single phase of the respiratory cycle, and (3) CT maps phase matched to the emission data. Circumferential profiles of the heart uptake were compared and differences of up to 24% were found between the single-phase CT-AC method and the true phantom values. Simulation results were supported by a PET/CT canine study which showed differences of up to 10% in the heart uptake in the lung-heart boundary region when comparing {sup 68}Ge- to CT-based AC with the CT map acquired at end inhalation.

  14. Computational fluid dynamic applications

    SciTech Connect

    Chang, S.-L.; Lottes, S. A.; Zhou, C. Q.

    2000-04-03

    The rapid advancement of computational capability including speed and memory size has prompted the wide use of computational fluid dynamics (CFD) codes to simulate complex flow systems. CFD simulations are used to study the operating problems encountered in system, to evaluate the impacts of operation/design parameters on the performance of a system, and to investigate novel design concepts. CFD codes are generally developed based on the conservation laws of mass, momentum, and energy that govern the characteristics of a flow. The governing equations are simplified and discretized for a selected computational grid system. Numerical methods are selected to simplify and calculate approximate flow properties. For turbulent, reacting, and multiphase flow systems the complex processes relating to these aspects of the flow, i.e., turbulent diffusion, combustion kinetics, interfacial drag and heat and mass transfer, etc., are described in mathematical models, based on a combination of fundamental physics and empirical data, that are incorporated into the code. CFD simulation has been applied to a large variety of practical and industrial scale flow systems.

  15. Signal transport in Computed Tomography detectors

    NASA Astrophysics Data System (ADS)

    Heismann, B. J.; Bätz, L.; Pham-Gia, K.; Metzger, W.; Niederlöhner, D.; Wirth, S.

    2008-06-01

    In Computed Tomography (CT) X-ray intensities are measured by large-scale solid-state detectors. The standard set-up comprises a scintillator pixel array attached to a matrix of photo sensors, which in turn is read out by analog-to-digital conversion electronics. We have developed and validated a three-dimensional system model describing the cascaded system process. The first step comprises a Monte-Carlo (MC) tracking of the primary X-ray quanta energy deposition, taking into account the relevant fluorescence and scattering processes. The second step models the transport of optical photons in the scintillator pixels formed by a solid-state bulk with surrounding back-scattering TiO 2 walls. In a third step the individual events are integrated to a read-out signal and analyzed for their statistical properties. The system model is verified by a comparison to optical measurements. A scintillator array is excited by a needle beam X-ray source. The emitted light field is read out by a high-resolution CCD sensor. A good agreement between simulation and experiments is found, with a typical deviation in the range of 5%. The detector response function D( E, E') is used to quantify the spectral behavior. It yields the probability to measure an energy E' for an incoming quantum energy E. We calculate the expected energy < E'( E)> and link the deviations from proportionality in E to properties of the signal transport. Finally the impact of the signal transport statistics on the output signal-to-noise ratio is analyzed.

  16. Dose in x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Kalender, Willi A.

    2014-02-01

    Radiation dose in x-ray computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. This review aims to present an overview of current concepts for both scanner output metrics and for patient dosimetry and will comment on their strengths and weaknesses. Controversial issues such as the appropriateness of the CT dose index (CTDI) are discussed in detail. A review of approaches to patient dose assessment presently in practice, of the dose levels encountered and options for further dose optimization are also given and discussed. Patient dose assessment remains a topic for further improvement and for international consensus. All approaches presently in use are based on Monte Carlo (MC) simulations. Estimates for effective dose are established, but they are crude and not patient-specific; organ dose estimates are rarely available. Patient- and organ-specific dose estimates can be provided with adequate accuracy and independent of CTDI phantom measurements by fast MC simulations. Such information, in particular on 3D dose distributions, is important and helpful in optimization efforts. Dose optimization has been performed very successfully in recent years and even resulted in applications with effective dose values of below 1 mSv. In general, a trend towards lower dose values based on technical innovations has to be acknowledged. Effective dose values are down to clearly below 10 mSv on average, and there are a number of applications such as cardiac and pediatric CT which are performed routinely below 1 mSv on modern equipment.

  17. Predicting cancer risks from dental computed tomography.

    PubMed

    Wu, T-H; Lin, W-C; Chen, W-K; Chang, Y-C; Hwang, J-J

    2015-01-01

    Dental computed tomography (CT) has become a common tool when carrying out dental implants, yet there is little information available on its associated cancer risk. The objective of this study was to estimate the lifetime-attributable risk (LAR) of cancer incidence that is associated with the radiation dose from dental CT scans and to evaluate the effect of scan position, sex, and age on the cancer risk. This retrospective cohort study involved 505 participants who underwent CT scans. The mean effective doses for male and female patients in the maxilla group were 408 and 389 µSv (P = 0.055), respectively, whereas the mean effective doses for male and female patients in the mandible groups were 475 and 450 µSv (P < 0.001), respectively. The LAR for cancer incidence after mandible CT scanning varied from 1 in 16,196 for a 30-y-old woman to 1 in 114,680 for a 70-y-old man. The organ-specific cancer risks for thyroid cancer, other cancers, leukemia, and lung cancer account for 99% of the LAR. Among patients of all ages, the estimated LAR of a mandible scan was higher than that of a maxilla scan. Furthermore, the LAR for female thyroid cancer had a peak before age 45 y. The risk for a woman aged 30 y is roughly 8 times higher than that of a woman aged 50 y. After undergoing a dental CT scan, the possible cancer risks related to sex and age across various different anatomical regions are not similar. The greatest risk due to a dental CT scan is for a mandible scan when the woman is younger than 45 y. Given the limits of the sample size, machine parameters, and the retrospective nature of this study, the results need to be interpreted within the context of this patient population. Future studies will be of value to corroborate these findings. PMID:25359782

  18. Dose in x-ray computed tomography.

    PubMed

    Kalender, Willi A

    2014-02-01

    Radiation dose in x-ray computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. This review aims to present an overview of current concepts for both scanner output metrics and for patient dosimetry and will comment on their strengths and weaknesses. Controversial issues such as the appropriateness of the CT dose index (CTDI) are discussed in detail. A review of approaches to patient dose assessment presently in practice, of the dose levels encountered and options for further dose optimization are also given and discussed. Patient dose assessment remains a topic for further improvement and for international consensus. All approaches presently in use are based on Monte Carlo (MC) simulations. Estimates for effective dose are established, but they are crude and not patient-specific; organ dose estimates are rarely available. Patient- and organ-specific dose estimates can be provided with adequate accuracy and independent of CTDI phantom measurements by fast MC simulations. Such information, in particular on 3D dose distributions, is important and helpful in optimization efforts. Dose optimization has been performed very successfully in recent years and even resulted in applications with effective dose values of below 1 mSv. In general, a trend towards lower dose values based on technical innovations has to be acknowledged. Effective dose values are down to clearly below 10 mSv on average, and there are a number of applications such as cardiac and pediatric CT which are performed routinely below 1 mSv on modern equipment. PMID:24434792

  19. Computed Tomography Staging of Middle Ear Cholesteatoma

    PubMed Central

    Razek, Ahmed Abdel Khalek Abdel; Ghonim, Mohamed Rashad; Ashraf, Bassem

    2015-01-01

    Summary Background To establish computed tomography (CT) staging of middle ear cholesteatoma and assess its impact on the selection of the surgical procedure. Material/Methods Prospective study was conducted on 61 consecutive patients (mean age 26.8 years) with middle ear cholesteatoma. CT scan of the temporal bone and surgery were performed in all patients. CT staging classified cholesteatoma according to its location in the tympanic cavity (T); extension into the mastoid (M); and associated complications (C). Cholesteatoma was staged as stage I (T1, T2), stage II (T3, M1, M2, C1), and stage III (C2). Results The overall sensitivity of CT staging of cholesteatoma compared to surgery was 88% with excellent agreement and correlation between CT findings and intra-operative findings (K=0.863, r=0.86, P=0.001). There was excellent agreement and correlation of CT staging with surgical findings for T location (K=0.811, r=0.89, P=0.001), good for M extension (K=0.734, r=0.88, P=0.001), and excellent for associated C complications (K=1.00, r=1.0, P=0.001). Atticotympanotomy was carried out in stage I (n=14), intact canal wall surgery was performed in stage II (n=38), and canal wall down surgery was done in stage III (n=5) and stage II (n=4). Conclusions We established CT staging of middle ear cholesteatoma that helps surgeons to select an appropriate surgery. PMID:26171086

  20. Helical x-ray differential phase contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Qi, Zhihua; Thériault-Lauzier, Pascal; Bevins, Nicholas; Zambelli, Joseph; Li, Ke; Chen, Guang-Hong

    2011-03-01

    Helical computed tomography revolutionized the field of x-ray computed tomography two decades ago. The simultaneous translation of an image object with a standard computed tomography acquisition allows for fast volumetric scan for long image objects. X-ray phase sensitive imaging methods have been studied over the past few decades to provide new contrast mechanisms for imaging an object. A Talbot-Lau grating interferometer based differential phase contrast imaging method has recently demonstrated its potential for implementation in clinical and industrial applications. In this work, the principles of helical computed tomography are extended to differential phase contrast imaging to produce volumetric reconstructions based on fan-beam data. The method demonstrates the potential for helical differential phase contrast CT to scan long objects with relatively small detector coverage in the axial direction.

  1. Use of computed tomography in nondestructive testing of polymeric materials

    SciTech Connect

    Persson, S.; Oestman, E.

    1985-12-01

    Computed tomography has been used to detect imperfections and to measure cross-link density gradients in polymeric products, such as airplane tires, rubber shock absorbers, and filament-wound high-pressure tanks.

  2. Computed tomography of the liver in von Gierke's disease.

    PubMed

    Biondetti, P R; Fiore, D; Muzzio, P C

    1980-10-01

    The computed tomography findings in the liver of a patient with von Gierke's disease are presented. Precontrast scans demonstrated diffuse decreased density throughout the liver. In the postcontrast scans, a focal right sided hyperdense area was visualized. PMID:6931833

  3. Dynamics of bubble-bubble interaction in sheared low-viscosity magma imaged by X-ray computed micro-tomography

    NASA Astrophysics Data System (ADS)

    Helo, C.; Flaws, A.; Hess, K.-U.; Franz, A.; Clague, D. A.; Dingwell, D. B.

    2012-04-01

    X-ray computed tomography of vesicles in basaltic pyroclastic glass fragments has been used to investigate the syn-eruptive shear environment and resulting bubble-bubble interaction during mild pyroclastic eruptions in a mid-ocean ridge environment. We have imaged vesicles present in two different types of pyroclastic fragments produced by mildly explosive activity on Axial Seamount, limu o Pele, that is, thin glass films often described as bubble walls, and tube scoria fragments. Rapid quenching of the glass has prevented extensive bubble relaxation preserving the syn-eruptive geometry of the bubbles in these fragments. Isolated, ellipsoid-shaped vesicles in low-vesicular limu o Pele indicate deformation in a simple shear environment. Under these shear conditions higher vesiculated parts of the erupting magma show strong bubble-bubble interactions partially leading to coalscence and formation of tubular vesicles. These tubular vesicles can reach significant lengths, exceeding the dimensions of the small glass fragments (2 mm). Their unreformed radius can be more then one order of magnitude larger than that of the isolated vesicles in the limu o Pele fragments. We can distinguish two principle modes of interaction based on the relative orientation of the bubbles. Interaction along the sidewalls of two bubbles, and tip-to-tip interaction. At interdistances of less than a few tens of micrometre, interaction of the sidewalls results in deformation of the bubbles to more irregular shapes, with depressions caused by close, small bubbles or in some cases bubbles being partially mantled around tubular bubbles. This often leads to a more close packing of bubbles. At distances of less than a few microns, the melt films between the bubbles destabilize leading to coalescence. This mechanism appears to involve a bulging of the larger bubble into the smaller, followed by melt film rapture and coalescence. The complete digestion of one bubble by the other is the slow rate

  4. Computer aided stress analysis of long bones utilizing computer tomography

    SciTech Connect

    Marom, S.A.

    1986-01-01

    A computer aided analysis method, utilizing computed tomography (CT) has been developed, which together with a finite element program determines the stress-displacement pattern in a long bone section. The CT data file provides the geometry, the density and the material properties for the generated finite element model. A three-dimensional finite element model of a tibial shaft is automatically generated from the CT file by a pre-processing procedure for a finite element program. The developed pre-processor includes an edge detection algorithm which determines the boundaries of the reconstructed cross-sectional images of the scanned bone. A mesh generation procedure than automatically generates a three-dimensional mesh of a user-selected refinement. The elastic properties needed for the stress analysis are individually determined for each model element using the radiographic density (CT number) of each pixel with the elemental borders. The elastic modulus is determined from the CT radiographic density by using an empirical relationship from the literature. The generated finite element model, together with applied loads, determined from existing gait analysis and initial displacements, comprise a formatted input for the SAP IV finite element program. The output of this program, stresses and displacements at the model elements and nodes, are sorted and displayed by a developed post-processor to provide maximum and minimum values at selected locations in the model.

  5. Tuned Aperture Computed Tomography to Evaluate Osseous Healing

    PubMed Central

    Nair, M.K.; Seyedain, A.; Agarwall, S.; Webber, R.L.; Nair, U.P.; Piesco, N.P.; Mooney, M.P.; Grondahl, H.-G.

    2016-01-01

    Quantification of osseous healing is a challenging task, requiring expensive advanced imaging modalities. To improve diagnostic osseous imaging, we undertook this prospective study to explore the potential of Tuned Aperture Computed Tomography®. Eighty defects in 20 rabbit mandibles, randomly carrying an osteoblast suspension or a polymer matrix or a combination thereof or no treatment, were imaged at 3, 6, 9, and 12 weeks post-surgery. TACT slices, iteratively restored TACT, and conventional digital radiographs were evaluated. Mean-gray-value distribution within regions of interest was correlated with histomorphometric data. Lesions treated with osteoblast/polymer-matrix delivery systems demonstrated the highest mean gray-value, while the diagnostic efficacy of TACT-IR was significantly better than that of other imaging modalities (p < 0.001). Thus, TACT is an accurate imaging modality for non-destructive quantification of osseous dynamics. PMID:11597021

  6. Ultrafast three-dimensional x-ray computed tomography

    SciTech Connect

    Bieberle, Martina; Barthel, Frank; Hampel, Uwe; Menz, Hans-Juergen; Mayer, Hans-Georg

    2011-01-17

    X-ray computed tomography (CT) is a well established visualization technique in medicine and nondestructive testing. However, since CT scanning requires sampling of radiographic projections from different viewing angles, common CT systems with mechanically moving parts are too slow for dynamic imaging, for instance of multiphase flows or live animals. Here, we introduce an ultrafast three-dimensional x-ray CT method based on electron beam scanning, which achieves volume rates of 500 s{sup -1}. Primary experiments revealed the capability of this method to recover the structure of phase boundaries in gas-solid and gas-liquid two-phase flows, which undergo three-dimensional structural changes in the millisecond scale.

  7. Ultrafast three-dimensional x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Bieberle, Martina; Barthel, Frank; Menz, Hans-Jürgen; Mayer, Hans-Georg; Hampel, Uwe

    2011-01-01

    X-ray computed tomography (CT) is a well established visualization technique in medicine and nondestructive testing. However, since CT scanning requires sampling of radiographic projections from different viewing angles, common CT systems with mechanically moving parts are too slow for dynamic imaging, for instance of multiphase flows or live animals. Here, we introduce an ultrafast three-dimensional x-ray CT method based on electron beam scanning, which achieves volume rates of 500 s-1. Primary experiments revealed the capability of this method to recover the structure of phase boundaries in gas-solid and gas-liquid two-phase flows, which undergo three-dimensional structural changes in the millisecond scale.

  8. Cone beam computed tomography in Endodontics - a review.

    PubMed

    Patel, S; Durack, C; Abella, F; Shemesh, H; Roig, M; Lemberg, K

    2015-01-01

    Cone beam computed tomography (CBCT) produces undistorted three-dimensional information of the maxillofacial skeleton, including the teeth and their surrounding tissues with a lower effective radiation dose than computed tomography. The aim of this paper is to: (i) review the current literature on the applications and limitations of CBCT; (ii) make recommendations for the use of CBCT in Endodontics; (iii) highlight areas of further research of CBCT in Endodontics. PMID:24697513

  9. Multiple Energy Computer Tomography (MECT) at the NSLS: Status report

    SciTech Connect

    Dilmanian, F.A.; Wu, X.Y.; Chen, Z.; Ren, B.; Slatkin, D.N.; Chapman, D.; Schleifer, M.; Staicu, F.A.; Thomlinson, W.

    1994-09-01

    Status of the synchrotron-based computed tomography (CT) system Multiple Energy Computed Tomography (MECT) system is described. MECT, that uses monochromatic beams from the X17 superconducting wiggler beam line at the National Synchrotron Light Source (NSLS), will be used for imaging the human head and neck. An earlier prototype MECT produced images of phantoms and living rodents. This report summarizes the studies with the prototype, and describes the design, construction, and test results of the Clinical MECT system components.

  10. Image analysis of particle field by means of computed tomography

    NASA Technical Reports Server (NTRS)

    Nakayama, Mitsushige

    1987-01-01

    In order to visualize and investigate spray structures, computed tomography technique is applied to analyze droplet information. From the transmitted light intensity through the spray and/or the data of particle size distribution obtained from a Fraunhofer diffraction principle, the quantitative volume of spray droplet or local particle size was calculated and the reconstruction of spray structures was made. The background of computed tomography is described along with some experimental results of the structure of intermittent spray such as diesel spray.

  11. [Value of positron emission tomography and computer tomography (PET/CT) for urologic malignancies].

    PubMed

    Boujelbene, N; Prior, J O; Boubaker, A; Azria, D; Schaffer, M; Gez, E; Jichlinski, P; Meuwly, J-Y; Mirimanoff, R O; Ozsahin, M; Zouhair, A

    2011-07-01

    Positron emission tomography is a functional imaging technique that allows the detection of the regional metabolic rate, and is often coupled with other morphological imaging technique such as computed tomography. The rationale for its use is based on the clearly demonstrated fact that functional changes in tumor processes happen before morphological changes. Its introduction to the clinical practice added a new dimension in conventional imaging techniques. This review presents the current and proposed indications of the use of positron emission/computed tomography for prostate, bladder and testes, and the potential role of this exam in radiotherapy planning. PMID:21507695

  12. Skeletal dosimetry in cone beam computed tomography

    SciTech Connect

    Walters, B. R. B.; Ding, G. X.; Kramer, R.; Kawrakow, I.

    2009-07-15

    Cone beam computed tomography (CBCT) is a relatively new patient imaging technique that has proved invaluable for treatment target verification and patient positioning during image-guided radiotherapy (IGRT). It has been shown that CBCT results in additional dose to bone that may amount to 10% of the prescribed dose. In this study, voxelized human phantoms, FAX06 (adult female) and MAX06 (adult male), are used together with phase-space data collected from a realistic model of a CBCT imager to calculate dose in the red bone marrow (RBM) and bone surface cells (BSCs), the two organs at risk within the bone spongiosa, during simulated head and neck, chest and pelvis CBCT scans. The FAX06/MAX06 phantoms model spongiosa based on micro-CT images, filling the relevant phantom voxels, which are 0.12x0.12x0.12 cm{sup 3}, with 17x17x17 {mu}m{sup 3} microvoxels to form a micromatrix of trabecular bone and bone marrow. FAX06/MAX06 have already been implemented in an EGSnrc-based Monte Carlo code to simulate radiation transport in the phantoms; however, this study required significant modifications of the code to allow use of phase-space data from a simulated CBCT imager as a source and to allow scoring of total dose, RBM dose and BSC dose on a voxel-by-voxel basis. In simulated CBCT scans, the BSC dose is significantly greater than the dose to other organs at risk. For example, in a simulated head and neck scan, the average BSC dose is 25% higher than the average dose to eye lens ({approx}8.3 cGy), and 80% greater than the average dose to brain (5.7 cGy). Average dose to RBM, on the other hand, is typically only {approx}50% of the average BSC dose and less than the dose to other organs at risk (54% of the dose to eye lens and 76% of dose to brain in a head and neck scan). Thus, elevated dose in bone due to CBCT results in elevated BSC dose. This is potentially of concern when using CBCT in conjunction with radiotherapy treatment.

  13. Application of Computer Tomography for Life Detection

    NASA Technical Reports Server (NTRS)

    Tsapin, A.; Nealson, K.

    2001-01-01

    Perhaps one of the most fundamentally difficult challenges facing those who would search for life is that of scale determination. Spatial scales of life on Earth range over more than 15 orders of magnitude in mass and volume, and more than 8 orders of magnitude in 2 dimensional space. If the distribution of life is sparse in comparison to the background on which it is found, then the choice of the right scale is critical to finding that life. But how does one identify the proper scale? To put this in other words, how does one recognize the "haystacks" in which the needles (biosignatures and evidence of life) might be most profitably searched for? The problem is further exacerbated when conditions get extreme because much of the life moves from the clement surface environment into the pores and more clement environments inside of rocks, minerals and soils. Once encased in their lithic homes, these microbes become nearly impossible to study by standard techniques because of the opacity of the rocks. It is this problem that we propose to address in the work proposed here. Computer Tomography (CT) has been a very valuable tool in medicine, where the best resolution available has typically been of the order of about 0.5 mm. However, to adapt the approach for life detection of microbial endoliths, the resolution needs to be moved to the micrometer and even submicrometer levels. Thus for the studies proposed here, we begin with a commercially available instrument that can yield resolution of approximately 10 micrometers. The rational for this is twofold: first, this is the "state of the art" in laboratory instruments; and second, that while the usual size of a microbial cell is about 1 micron, microorganisms tend to live in communities that usually exceed the 10 micrometer size range. The resolution also depends on the sample size itself, so having a small lab instrument into which small samples can be placed will be beneficial to the resolution. We have now used several

  14. Skeletal dosimetry in cone beam computed tomography.

    PubMed

    Walters, B R B; Ding, G X; Kramer, R; Kawrakow, I

    2009-07-01

    Cone beam computed tomography (CBCT) is a relatively new patient imaging technique that has proved invaluable for treatment target verification and patient positioning during image-guided radiotherapy (IGRT). It has been shown that CBCT results in additional dose to bone that may amount to 10% of the prescribed dose. In this study, voxelized human phantoms, FAX06 (adult female) and MAX06 (adult male), are used together with phase-space data collected from a realistic model of a CBCT imager to calculate dose in the red bone marrow (RBM) and bone surface cells (BSCs), the two organs at risk within the bone spongiosa, during simulated head and neck, chest and pelvis CBCT scans. The FAX06/MAX06 phantoms model spongiosa based on micro-CT images, filling the relevant phantom voxels, which are 0.12 x 0.12 x 0.12 cm3, with 17 x 17 x 17 microm3 microvoxels to form a micromatrix of trabecular bone and bone marrow. FAX06/ MAX06 have already been implemented in an EGSnrc-based Monte Carlo code to simulate radiation transport in the phantoms; however, this study required significant modifications of the code to allow use of phase-space data from a simulated CBCT imager as a source and to allow scoring of total dose, RBM dose and BSC dose on a voxel-by-voxel basis. In simulated CBCT scans, the BSC dose is significantly greater than the dose to other organs at risk. For example, in a simulated head and neck scan, the average BSC dose is 25% higher than the average dose to eye lens (approximately 8.3 cGy), and 80% greater than the average dose to brain (5.7 cGy). Average dose to RBM, on the other hand, is typically only approximately 50% of the average BSC dose and less than the dose to other organs at risk (54% of the dose to eye lens and 76% of dose to brain in a head and neck scan). Thus, elevated dose in bone due to CBCT results in elevated BSC dose. This is potentially of concern when using CBCT in conjunction with radiotherapy treatment. PMID:19673190

  15. Computational hemodynamics of abdominal aortic aneurysms: Three-dimensional ultrasound versus computed tomography.

    PubMed

    Owen, Benjamin; Lowe, Christopher; Ashton, Neil; Mandal, Parthasarathi; Rogers, Steven; Wein, Wolfgang; McCollum, Charles; Revell, Alistair

    2016-03-01

    The current criterion for surgical intervention in abdominal aortic aneurysms, based upon a maximal aortic diameter, is considered conservative due to the high mortality rate in case of rupture. The research community is actively investigating the use of computational mechanics tools combined with patient-specific imaging to help identify more accurate criteria. Widespread uptake of a successful metric will however be limited by the need for computed tomography, which is at present the primary image extraction method on account of the location and complex shape of the aneurysms. The use of three-dimensional ultrasound as the scanning method is more attractive on account of increased availability, reduced cost and reduced risk to patients. The suitability of three-dimensional ultrasound is assessed for this purpose in the present work; computational fluid dynamics simulations were performed on geometries obtained from the same patient using both ultrasound and computed tomography. The influence of different smoothing algorithms is investigated in the geometry preparation stage and Taubin's low-pass filter was found to best preserve geometry features. Laminar, Newtonian, steady-state simulation analysis identified haemodynamic characteristics to be qualitatively similar in terms of wall shear stress, velocity and vorticity. The study demonstrates the potential for three-dimensional ultrasound to be integrated into a more accessible patient-specific modelling tool able to identify the need for surgical intervention of abdominal aortic aneurysms. PMID:26893226

  16. Pore scale definition and computation from tomography data

    NASA Astrophysics Data System (ADS)

    Dupuy, P. M.; Austin, P.; Delaney, G. W.; Schwarz, M. P.

    2011-10-01

    During recent years characterisation capabilities of porous media have been transformed by advances in computation and visualisation technologies. It is now possible to obtain detailed topological and hydrodynamic information of porous media by combining tomographic and computational fluid dynamic studies. Despite the existence of these new capabilities, the characterisation process itself is based on the same antiquated experimental macroscopic concepts. We are interested in an up-scaling process where we can keep key information for every pore size present in the media in order to feed multi-scale transport models. Hydrometallurgical, environmental, food, pharmaceutical and chemical engineering are industries with process outcomes based on homogeneous and heterogeneous reactions and therefore sensitive to the reaction and transport processes happening at different pore scales. The present work addresses a key step in the information up-scaling process, i.e. a pore identification algorithm similar to alternating sequential filters. In a preliminary study, topological and hydrodynamic variables are correlated with the pore size. Micrometre and millimetre resolution tomographies are used to characterise the pore size distribution of a packed column and different rocks. Finally, we compute the inter-pore-scale redistribution function which is a measure of the heterogeneity of the media and magnitude needed in multi-scale modelling.

  17. Whole-body magnetic resonance imaging and positron emission tomography-computed tomography in oncology.

    PubMed

    Schmidt, Gerwin P; Kramer, Harald; Reiser, Maximilian F; Glaser, Christian

    2007-06-01

    The advent of positron emission tomography-computed tomography (PET-CT) and whole-body magnetic resonance imaging (WB-MRI) has introduced tumor imaging with a systemic and functional approach compared with established sequential, multimodal diagnostic algorithms.Whole-body PET with [18F]-fluoro-2-desoxy-glucose is a useful imaging procedure for tumor staging and monitoring that can visualize active tumor tissue by detecting pathological glucose metabolism. The combination of PET with the detailed anatomical information of multislice computed tomography as dual-modality scanners has markedly increased lesion localization and diagnostic accuracy compared with both modalities as standalone applications.Hardware innovations, such as the introduction of multi-receiver channel whole-body MRI scanners at 1.5 and, recently, 3 T, combined with acquisition acceleration techniques, have made high-resolution WB-MRI clinically feasible. Now, a dedicated assessment of individual organs with various soft tissue contrast, spatial resolution, and contrast media dynamics can be combined with whole-body anatomical coverage in a multiplanar imaging approach. More flexible protocols (eg, T1-weighted turbo spin-echo and short inversion recovery imaging, dedicated lung imaging or dynamic contrast-enhanced studies of the abdomen) can be performed within 45 minutes.Whole-body magnetic resonance imaging has recently been proposed for tumor screening of asymptomatic individuals, and potentially life-changing diagnoses, such as formerly unknown malignancy, have been reported. However, larger patient cohort studies will have to show the cost efficiency and the clinical effectiveness of such an approach.For initial tumor staging, PET-CT has proved more accurate for the definition of T-stage and lymph node assessment, mainly because of the missing metabolic information in WB-MRI. However, new applications, such as magnetic resonance whole-body diffusion-weighted imaging or lymphotropic contrast

  18. Dynamic Positron Emission Tomography Imaging of Renal Clearable Gold Nanoparticles.

    PubMed

    Chen, Feng; Goel, Shreya; Hernandez, Reinier; Graves, Stephen A; Shi, Sixiang; Nickles, Robert J; Cai, Weibo

    2016-05-01

    Optical imaging has been the primary imaging modality for nearly all of the renal clearable nanoparticles since 2007. Due to the tissue depth penetration limitation, providing accurate organ kinetics non-invasively has long been a huge challenge. Although a more quantitative imaging technique has been developed by labeling nanoparticles with single-photon emission computed tomography (SPECT) isotopes, the low temporal resolution of SPECT still limits its potential for visualizing the rapid dynamic process of renal clearable nanoparticles in vivo. The dynamic positron emission tomography (PET) imaging of renal clearable gold (Au) nanoparticles by labeling them with copper-64 ((64) Cu) to form (64) Cu-NOTA-Au-GSH is reported. Systematic nanoparticle synthesis and characterizations are performed to demonstrate the efficient renal clearance of as-prepared nanoparticles. A rapid renal clearance of (64) Cu-NOTA-Au-GSH is observed (>75%ID at 24 h post-injection) with its elimination half-life calculated to be less than 6 min, over 130 times shorter than previously reported similar nanoparticles. Dynamic PET imaging not only addresses the current challenges in accurately and non-invasively acquiring the organ kinetics, but also potentially provides a highly useful tool for studying renal clearance mechanism of other ultra-small nanoparticles, as well as the diagnosis of kidney diseases in the near future. PMID:27062146

  19. Endocrine radionuclide scintigraphy with fusion single photon emission computed tomography/computed tomography

    PubMed Central

    Wong, Ka-Kit; Gandhi, Arpit; Viglianti, Benjamin L; Fig, Lorraine M; Rubello, Domenico; Gross, Milton D

    2016-01-01

    AIM: To review the benefits of single photon emission computed tomography (SPECT)/computed tomography (CT) hybrid imaging for diagnosis of various endocrine disorders. METHODS: We performed MEDLINE and PubMed searches using the terms: “SPECT/CT”; “functional anatomic mapping”; “transmission emission tomography”; “parathyroid adenoma”; “thyroid cancer”; “neuroendocrine tumor”; “adrenal”; “pheochromocytoma”; “paraganglioma”; in order to identify relevant articles published in English during the years 2003 to 2015. Reference lists from the articles were reviewed to identify additional pertinent articles. Retrieved manuscripts (case reports, reviews, meta-analyses and abstracts) concerning the application of SPECT/CT to endocrine imaging were analyzed to provide a descriptive synthesis of the utility of this technology. RESULTS: The emergence of hybrid SPECT/CT camera technology now allows simultaneous acquisition of combined multi-modality imaging, with seamless fusion of three-dimensional volume datasets. The usefulness of combining functional information to depict the bio-distribution of radiotracers that map cellular processes of the endocrine system and tumors of endocrine origin, with anatomy derived from CT, has improved the diagnostic capability of scintigraphy for a range of disorders of endocrine gland function. The literature describes benefits of SPECT/CT for 99mTc-sestamibi parathyroid scintigraphy and 99mTc-pertechnetate thyroid scintigraphy, 123I- or 131I-radioiodine for staging of differentiated thyroid carcinoma, 111In- and 99mTc- labeled somatostatin receptor analogues for detection of neuroendocrine tumors, 131I-norcholesterol (NP-59) scans for assessment of adrenal cortical hyperfunction, and 123I- or 131I-metaiodobenzylguanidine imaging for evaluation of pheochromocytoma and paraganglioma. CONCLUSION: SPECT/CT exploits the synergism between the functional information from radiopharmaceutical imaging and anatomy

  20. Computational Fluid Dynamics Library

    Energy Science and Technology Software Center (ESTSC)

    2005-03-04

    CFDLib05 is the Los Alamos Computational Fluid Dynamics LIBrary. This is a collection of hydrocodes using a common data structure and a common numerical method, for problems ranging from single-field, incompressible flow, to multi-species, multi-field, compressible flow. The data structure is multi-block, with a so-called structured grid in each block. The numerical method is a Finite-Volume scheme employing a state vector that is fully cell-centered. This means that the integral form of the conservation lawsmore » is solved on the physical domain that is represented by a mesh of control volumes. The typical control volume is an arbitrary quadrilateral in 2D and an arbitrary hexahedron in 3D. The Finite-Volume scheme is for time-unsteady flow and remains well coupled by means of time and space centered fluxes; if a steady state solution is required, the problem is integrated forward in time until the user is satisfied that the state is stationary.« less

  1. Computed tomography in penetrating injury to the eye.

    PubMed

    Bhimani, S; Virapongse, C; Sarwar, M; Twist, J F

    1984-05-01

    We used computed tomography to detect and localize foreign bodies in two unusual cases of penetrating injury to the eyes. In one case, a large broken twig appeared to have penetrated the globe and the inferior rectus muscle; in the other, the globe was ruptured by many glass shards . In the first case surgery showed the computed tomographic impression to be incorrect. The globe and the inferior rectus muscle were intact and vision and motility were normal postoperatively. In the second case, swelling made direct visualization impossible, and computed tomography was used to locate the foreign bodies. PMID:6720836

  2. Computed tomography in the evaluation of Crohn disease

    SciTech Connect

    Goldberg, H.I.; Gore, R.M.; Margulis, A.R.; Moss, A.A.; Baker, E.L.

    1983-02-01

    The abdominal and pelvic computed tomographic examinations in 28 patients with Crohn disease were analyzed and correlated with conventional barium studies, sinograms, and surgical findings. Mucosal abnormalities such as aphthous lesions, pseudopolyps, and ulcerations were only imaged by conventional techniques. Computed tomography proved superior in demonstrating the mural, serosal, and mesenteric abnormalities such as bowel wall thickening (82%), fibrofatty proliferation of mesenteric fat (39%), mesenteric abscess (25%), inflammatory reaction of the mesentery (14%), and mesenteric lymphadenopathy (18%). Computed tomography was most useful clinically in defining the nature of mass effects, separation, or displacement of small bowel segments seen on small bowel series. Although conventional barium studies remain the initial diagnostic procedure in evaluating Crohn disease, computed tomography can be a useful adjunct in resolving difficult clinical and radiologic diagnostic problems.

  3. Development of a proton Computed Tomography detector system

    NASA Astrophysics Data System (ADS)

    Naimuddin, Md.; Coutrakon, G.; Blazey, G.; Boi, S.; Dyshkant, A.; Erdelyi, B.; Hedin, D.; Johnson, E.; Krider, J.; Rukalin, V.; Uzunyan, S. A.; Zutshi, V.; Fordt, R.; Sellberg, G.; Rauch, J. E.; Roman, M.; Rubinov, P.; Wilson, P.

    2016-02-01

    Computer tomography is one of the most promising new methods to image abnormal tissues inside the human body. Tomography is also used to position the patient accurately before radiation therapy. Hadron therapy for treating cancer has become one of the most advantegeous and safe options. In order to fully utilize the advantages of hadron therapy, there is a necessity of performing radiography with hadrons as well. In this paper we present the development of a proton computed tomography system. Our second-generation proton tomography system consists of two upstream and two downstream trackers made up of fibers as active material and a range detector consisting of plastic scintillators. We present details of the detector system, readout electronics, and data acquisition system as well as the commissioning of the entire system. We also present preliminary results from the test beam of the range detector.

  4. Domain identification in impedance computed tomography by spline collocation method

    NASA Technical Reports Server (NTRS)

    Kojima, Fumio

    1990-01-01

    A method for estimating an unknown domain in elliptic boundary value problems is considered. The problem is formulated as an inverse problem of integral equations of the second kind. A computational method is developed using a splice collocation scheme. The results can be applied to the inverse problem of impedance computed tomography (ICT) for image reconstruction.

  5. Evaluating iterative reconstruction performance in computed tomography

    SciTech Connect

    Chen, Baiyu Solomon, Justin; Ramirez Giraldo, Juan Carlos; Samei, Ehsan

    2014-12-15

    Purpose: Iterative reconstruction (IR) offers notable advantages in computed tomography (CT). However, its performance characterization is complicated by its potentially nonlinear behavior, impacting performance in terms of specific tasks. This study aimed to evaluate the performance of IR with both task-specific and task-generic strategies. Methods: The performance of IR in CT was mathematically assessed with an observer model that predicted the detection accuracy in terms of the detectability index (d′). d′ was calculated based on the properties of the image noise and resolution, the observer, and the detection task. The characterizations of image noise and resolution were extended to accommodate the nonlinearity of IR. A library of tasks was mathematically modeled at a range of sizes (radius 1–4 mm), contrast levels (10–100 HU), and edge profiles (sharp and soft). Unique d′ values were calculated for each task with respect to five radiation exposure levels (volume CT dose index, CTDI{sub vol}: 3.4–64.8 mGy) and four reconstruction algorithms (filtered backprojection reconstruction, FBP; iterative reconstruction in imaging space, IRIS; and sinogram affirmed iterative reconstruction with strengths of 3 and 5, SAFIRE3 and SAFIRE5; all provided by Siemens Healthcare, Forchheim, Germany). The d′ values were translated into the areas under the receiver operating characteristic curve (AUC) to represent human observer performance. For each task and reconstruction algorithm, a threshold dose was derived as the minimum dose required to achieve a threshold AUC of 0.9. A task-specific dose reduction potential of IR was calculated as the difference between the threshold doses for IR and FBP. A task-generic comparison was further made between IR and FBP in terms of the percent of all tasks yielding an AUC higher than the threshold. Results: IR required less dose than FBP to achieve the threshold AUC. In general, SAFIRE5 showed the most significant dose reduction

  6. Synchrotron Radiation Computed Tomography (SRCT) of Ruled Laser Targets

    SciTech Connect

    Kinney, J H; Haupt, D L

    2002-03-15

    High spatial resolution tomography benefits from a high brightness source (photons/(mr{sup 2} x source area)). A synchrotron radiation source provides extremely high continuous brightness with spectral characteristics suited to a wide variety of imaging needs. Therefore, during the initial testing of the new synchrotron radiation computed tomography (SRCT) system at Stanford Synchrotron Radiation Laboratory, it was suggested that we image a ruled target designed for NIF experiments. This is a detailed report of that imaging effort.

  7. Stress Computed Tomography Myocardial Perfusion Imaging: A New Topic in Cardiology.

    PubMed

    Seitun, Sara; Castiglione Morelli, Margherita; Budaj, Irilda; Boccalini, Sara; Galletto Pregliasco, Athena; Valbusa, Alberto; Cademartiri, Filippo; Ferro, Carlo

    2016-02-01

    Since its introduction about 15 years ago, coronary computed tomography angiography has become today the most accurate clinical instrument for noninvasive assessment of coronary atherosclerosis. Important technical developments have led to a continuous stream of new clinical applications together with a significant reduction in radiation dose exposure. Latest generation computed tomography scanners (≥ 64 slices) allow the possibility of performing static or dynamic perfusion imaging during stress by using coronary vasodilator agents (adenosine, dipyridamole, or regadenoson), combining both functional and anatomical information in the same examination. In this article, the emerging role and state-of-the-art of myocardial computed tomography perfusion imaging are reviewed and are illustrated by clinical cases from our experience with a second-generation dual-source 128-slice scanner (Somatom Definition Flash, Siemens; Erlangen, Germany). Technical aspects, data analysis, diagnostic accuracy, radiation dose and future prospects are reviewed. PMID:26774540

  8. Pigmented villonodular synovitis mimics metastases on fluorine 18 fluorodeoxyglucose position emission tomography-computed tomography

    PubMed Central

    Elumogo, Comfort O.; Kochenderfer, James N.; Civelek, A. Cahid

    2016-01-01

    Pigmented villonodular synovitis (PVNS) is a benign joint disease best characterized on magnetic resonance imaging (MRI). The role of fluorine 18 fluorodeoxyglucose (18F-FDG) position emission tomography-computed tomography (PET-CT) in the diagnosis or characterization remains unclear. PVNS displays as a focal FDG avid lesion, which can masquerade as a metastatic lesion, on PET-CET. We present a case of PVNS found on surveillance imaging of a lymphoma patient. PMID:27190776

  9. Single-photon emission computed tomography/computed tomography in lung cancer and malignant lymphoma.

    PubMed

    Schillaci, Orazio

    2006-10-01

    In nuclear oncology, despite the fast-growing diffusion of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), single-photon emission computed tomography (SPECT) studies can still play an useful clinical role in several applications. The main limitation of SPECT imaging with tumor-seeking agents is the lack of the structural delineation of the pathologic processes they detect; this drawback sometimes renders SPECT interpretation difficult and can diminish its diagnostic accuracy. Fusion with morphological studies can overcome this limitation by giving an anatomical map to scintigraphic data. In the past, software-based fusion of independently performed SPECT and CT images proved to be time-consuming and impractical for routine use. The recent development of dual-modality integrated imaging systems that provide functional (SPECT) and anatomical (CT) images in the same scanning session, with the acquired images coregistered by means of the hardware, has opened a new era in this field. The first reports indicate that SPECT/CT is very useful in cancer imaging because it is able to provide further information of clinical value in several cases. In SPECT, studies of lung cancer and malignant lymphomas using different radiopharmaceutical, hybrid images are of value in providing the correct localization of tumor sites, with a precise detection of the involved organs, and the definition of their functional status, and in allowing the exclusion of disease in sites of physiologic tracer uptake. Therefore, in lung cancer and lymphomas, hybrid SPECT/CT can play a role in the diagnosis of the primary tumor, in the staging of the disease, in the follow-up, in the monitoring of therapy, in the detection of recurrence, and in dosimetric estimations for target radionuclide therapy. PMID:16950145

  10. Continuous analog of multiplicative algebraic reconstruction technique for computed tomography

    NASA Astrophysics Data System (ADS)

    Tateishi, Kiyoko; Yamaguchi, Yusaku; Abou Al-Ola, Omar M.; Kojima, Takeshi; Yoshinaga, Tetsuya

    2016-03-01

    We propose a hybrid dynamical system as a continuous analog to the block-iterative multiplicative algebraic reconstruction technique (BI-MART), which is a well-known iterative image reconstruction algorithm for computed tomography. The hybrid system is described by a switched nonlinear system with a piecewise smooth vector field or differential equation and, for consistent inverse problems, the convergence of non-negatively constrained solutions to a globally stable equilibrium is guaranteed by the Lyapunov theorem. Namely, we can prove theoretically that a weighted Kullback-Leibler divergence measure can be a common Lyapunov function for the switched system. We show that discretizing the differential equation by using the first-order approximation (Euler's method) based on the geometric multiplicative calculus leads to the same iterative formula of the BI-MART with the scaling parameter as a time-step of numerical discretization. The present paper is the first to reveal that a kind of iterative image reconstruction algorithm is constructed by the discretization of a continuous-time dynamical system for solving tomographic inverse problems. Iterative algorithms with not only the Euler method but also the Runge-Kutta methods of lower-orders applied for discretizing the continuous-time system can be used for image reconstruction. A numerical example showing the characteristics of the discretized iterative methods is presented.

  11. Diagnosis of dementia with single photon emission computed tomography

    SciTech Connect

    Jagust, W.J.; Budinger, T.F.; Reed, B.R.

    1987-03-01

    Single photon emission computed tomography is a practical modality for the study of physiologic cerebral activity in vivo. We utilized single photon emission computed tomography and N-isopropyl-p-iodoamphetamine iodine 123 to evaluate regional cerebral blood flow in nine patients with Alzheimer's disease (AD), five healthy elderly control subjects, and two patients with multi-infarct dementia. We found that all subjects with AD demonstrated flow deficits in temporoparietal cortex bilaterally, and that the ratio of activity in bilateral temporoparietal cortex to activity in the whole slice allowed the differentiation of all patients with AD from both the controls and from the patients with multi-infarct dementia. Furthermore, this ratio showed a strong correlation with disease severity in the AD group. Single photon emission computed tomography appears to be useful in the differential diagnosis of dementia and reflects clinical features of the disease.

  12. Tissue Characterization Using Energy-Selective Computed Tomography

    NASA Astrophysics Data System (ADS)

    Alvarez, Robert E.; Marshall, William H.; Lewis, Roger

    1981-07-01

    Energy-selective computed tomography has several important properties useful for in-vivo tissue characterization. Most importantly, it produces more information than conventional computed tomography. This information can be considered to be an added dimension which can be used to eliminate the ambiguities in conventional CT data. The noise in energy-selective computed tomography is also two dimensional and an un-correlated coordinate system can be defined which is needed for studying the capabilities of the technique for characterizing tissues. By using the calibration material basis set, the information from energy-selective CT can be extracted with extreme accuracy. Our preliminary experiments indicate that the technique is accurate enough to characterize the difference between gray and white matter. Most conventional systems have difficulty in distinguishing these materials, much less characterizing the reason for their differing attenuation. Thus energy-selective CT has the promise of providing extremely accurate tissue characterization based on its physical properties.

  13. C-Arm Computed Tomography Compared With Positron Emission Tomography/Computed Tomography for Treatment Planning Before Radioembolization

    SciTech Connect

    Becker, Christoph Waggershauser, Tobias; Tiling, Reinhold; Weckbach, Sabine; Johnson, Thorsten; Meissner, Oliver; Klingenbeck-Regn, Klaus; Reiser, Maximilian; Hoffmann, Ralf Thorsten

    2011-06-15

    The purpose of this study was to determine whether rotational C-arm computed tomography (CT) allows visualization of liver metastases and adds relevant information for radioembolization (RE) treatment planning. Technetium angiography, together with C-arm CT, was performed in 47 patients to determine the feasibility for RE. C-arm CT images were compared with positron emission tomography (PET)/CT images for the detection of liver tumors. The images were also rated according one of the following three categories: (1) images that provide no additional information compared with DSA alone; (2) images that do provide additional information compared with DSA; and (2) images that had an impact on eligibility determination for and planning of the RE procedure. In all patients, 283 FDG-positive liver lesions were detected by PET. In venous contrast-phase CT, 221 (78.1%) and 15 (5.3%) of these lesions were either hypodense or hyperdense, respectively. In C-arm CT, 103 (36.4%) liver lesions were not detectable because they were outside of either the field of view or the contrast-enhanced liver segment. Another 25 (8.8%) and 98 (34.6%) of the liver lesions were either hyperdense or presented primarily as hypodense lesions with a rim enhancement, respectively. With PET/CT as the standard of reference, venous CT and C-arm CT failed to detect 47 (16.6%) and 57 (20.1%) of all liver lesions, respectively. For RE planning, C-arm CT provided no further information, provide some additional information, or had an impact on the procedure in 20 (42.5%), 15 (31.9%) and 12 (25.6%) of patients, respectively. We conclude that C-arm CT may add decisive information in patients scheduled for RE.

  14. Direct sagital computed tomography of the temporomandibular joint

    SciTech Connect

    Manzione, J.V.; Seltzer, S.E.; Katzberg, R.W.; Hammerschlag, S.B.; Chiango, B.F.

    1983-01-01

    Temporomandibular joint dysfunction is a common clinical problem that has been reported to affect 4%-28% of adults. Temporomandibular joint arthrography has shown that many of these patients have intraarticular abnormalities involving the meniscus. A noninvasive test that could demonstrate the meniscus as well as bony abnormalities of the joint would be an important advance. In an attempt to develop such a noninvasive test, we have performed direct sagittal computed tomography (CT) on cadaver temporomandibular joints and have correlated the images with anatomic sections. We are currently applying this technique clinically and report one representative example in which direct sagittal computed tomography of the temporomandibular joint accurately demonstrated an anteriorly displaced meniscus.

  15. Computed Tomography Angiography of the Small Bowel and Mesentery.

    PubMed

    Raman, Siva P; Fishman, Elliot K

    2016-01-01

    Multidetector computed tomography (MDCT) has largely supplanted other available radiologic modalities in the evaluation of a wide variety of different vascular and inflammatory abnormalities of the small bowel, with computed tomography angiography (CTA) playing a major role in the diagnostic efficacy of MDCT for these diseases. Improvements in CTA imaging have proved particularly valuable in the evaluation of small bowel vascular and inflammatory disorders, diagnoses in which arterial phase images might be able to offer greater information than standard venous phase imaging. This article details the MDCT imaging findings of several small bowel vascular and inflammatory disorders. PMID:26654393

  16. Real-time in vivo computed optical interferometric tomography.

    PubMed

    Ahmad, Adeel; Shemonski, Nathan D; Adie, Steven G; Kim, Hee-Seok; Hwu, Wen-Mei W; Carney, P Scott; Boppart, Stephen A

    2013-06-01

    High-resolution real-time tomography of scattering tissues is important for many areas of medicine and biology(1-6). However, the compromise between transverse resolution and depth-of-field in addition to low sensitivity deep in tissue continue to impede progress towards cellular-level volumetric tomography. Computed imaging has the potential to solve these long-standing limitations. Interferometric synthetic aperture microscopy (ISAM)(7-9) is a computed imaging technique enabling high-resolution volumetric tomography with spatially invariant resolution. However, its potential for clinical diagnostics remains largely untapped since full volume reconstructions required lengthy postprocessing, and the phase-stability requirements have been difficult to satisfy in vivo. Here we demonstrate how 3-D Fourier-domain resampling, in combination with high-speed optical coherence tomography (OCT), can achieve high-resolution in vivo tomography. Enhanced depth sensitivity was achieved over a depth-of-field extended in real time by more than an order of magnitude. This work lays the foundation for high-speed volumetric cellular-level tomography. PMID:23956790

  17. An Exploratory Study Into the Role of Dynamic Contrast-Enhanced Magnetic Resonance Imaging or Perfusion Computed Tomography for Detection of Intratumoral Hypoxia in Head-and-Neck Cancer

    SciTech Connect

    Newbold, Kate Castellano, Isabel; Charles-Edwards, Elizabeth; Mears, Dorothy; Sohaib, Aslam; Leach, Martin; Rhys-Evans, Peter; Clarke, Peter; Fisher, Cyril; Harrington, Kevin; Nutting, Christopher

    2009-05-01

    Purpose: Hypoxia in patients with head-and-neck cancer (HNC) is well established and known to cause radiation resistance and treatment failure in the management of HNC. This study examines the role of parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and perfusion computed tomography (CT) as surrogate markers of intratumoral hypoxia, defined by using the exogenous marker of hypoxia pimonidazole and the endogenous marker carbonic anhydrase 9 (CA9). Methods and Materials: Patients with HNC underwent preoperative DCE-MRI, perfusion CT, and pimonidazole infusion. Imaging parameters were correlated with pimonidazole and CA9 staining. The strength of correlations was tested by using a two-tailed Spearman's rank correlation coefficient. Results: Twenty-three regions of interest were analyzed from the 7 patients who completed the DCE-MRI studies. A number of statistically significant correlations were seen between DCE-MRI parameters (volume transfer between blood plasma and extracellular extravascular space [EES], volume of EES, rate constant between EES and blood plasma, time at arrival of contrast inflow, time to peak, average gradient, and time to onset) and areas with a pimonidazole score of 4. In the case of CA9 staining, only a weak correlation was shown with wash-in rate. There were no significant correlations between perfusion CT parameters and pimonidazole staining or CA9 expression. Conclusion: Intratumoral hypoxia in patients with HNC may be predicted by using DCE-MRI; however, perfusion CT requires further investigation.

  18. Spectrum of single photon emission computed tomography/computed tomography findings in patients with parathyroid adenomas

    PubMed Central

    Chakraborty, Dhritiman; Mittal, Bhagwant Rai; Harisankar, Chidambaram Natrajan Balasubramanian; Bhattacharya, Anish; Bhadada, Sanjay

    2011-01-01

    Primary hyperparathyroidism results from excessive parathyroid hormone secretion. Approximately 85% of all cases of primary hyperparathyroidism are caused by a single parathyroid adenoma; 10–15% of the cases are caused by parathyroid hyperplasia. Parathyroid carcinoma accounts for approximately 3–4% of cases of primary disease. Technetium-99m-sestamibi (MIBI), the current scintigraphic procedure of choice for preoperative parathyroid localization, can be performed in various ways. The “single-isotope, double-phase technique” is based on the fact that MIBI washes out more rapidly from the thyroid than from abnormal parathyroid tissue. However, not all parathyroid lesions retain MIBI and not all thyroid tissue washes out quickly, and subtraction imaging is helpful. Single photon emission computed tomography (SPECT) provides information for localizing parathyroid lesions, differentiating thyroid from parathyroid lesions, and detecting and localizing ectopic parathyroid lesions. Addition of CT with SPECT improves the sensitivity. This pictorial assay demonstrates various SPECT/CT patterns observed in parathyroid scintigraphy. PMID:21969785

  19. Computed tomography of the orbit - A review and an update.

    PubMed

    Tawfik, Hatem A; Abdelhalim, Ahmed; Elkafrawy, Mamdouh H

    2012-10-01

    Computed tomography (CT) and magnetic resonance imaging (MRI) of the orbit have been competing for the hearts and minds of health care providers for well over 2 decades. While several drawbacks pertaining to CT have been outlined since the introduction of MRI, CT remains the standard diagnostic test for evaluating cross-sectional, 2 or 3-dimensional images of the body. PMID:23961026

  20. Micro-computed tomography: an alternative method for shark ageing.

    PubMed

    Geraghty, P T; Jones, A S; Stewart, J; Macbeth, W G

    2012-04-01

    Micro-computed tomography (microCT) produced 3D reconstructions of shark Carcharhinus brevipinna vertebrae that could be virtually sectioned along any desired plane, and upon which growth bands were readily visible. When compared to manual sectioning, it proved to be a valid and repeatable means of ageing and offers several distinct advantages over other ageing methods. PMID:22497384

  1. Incarcerated obturator hernia: early diagnostic using helical computed tomography.

    PubMed

    Avaro, J-P; Biance, N; Savoie, P-H; Peycru, T; Pauleau, G; Richez, P; Charpentier, R; Balandraud, P

    2008-04-01

    Obturator hernia is a rare event with poor clinical signs. Delayed diagnosis is a cause of increased mortality due to ruptured gangrenous bowel. We report a case of incarcerated obturator hernia which highlights the usefulness of computed tomography (CT) scanning in diagnosing this condition. PMID:17628737

  2. An Easily Assembled Laboratory Exercise in Computed Tomography

    ERIC Educational Resources Information Center

    Mylott, Elliot; Klepetka, Ryan; Dunlap, Justin C.; Widenhorn, Ralf

    2011-01-01

    In this paper, we present a laboratory activity in computed tomography (CT) primarily composed of a photogate and a rotary motion sensor that can be assembled quickly and partially automates data collection and analysis. We use an enclosure made with a light filter that is largely opaque in the visible spectrum but mostly transparent to the near…

  3. Computed Tomography-Enhanced Anatomy Course Using Enterprise Visualization

    ERIC Educational Resources Information Center

    May, Hila; Cohen, Haim; Medlej, Bahaa; Kornreich, Liora; Peled, Nathan; Hershkovitz, Israel

    2013-01-01

    Rapid changes in medical knowledge are forcing continuous adaptation of the basic science courses in medical schools. This article discusses a three-year experience developing a new Computed Tomography (CT)-based anatomy curriculum at the Sackler School of Medicine, Tel Aviv University, including describing the motivations and reasoning for the…

  4. RADIAL COMPUTED TOMOGRAPHY OF AIR CONTAMINANTS USING OPTICAL REMOTE SENSING

    EPA Science Inventory

    The paper describes the application of an optical remote-sensing (ORS) system to map air contaminants and locate fugitive emissions. Many ORD systems may utilize radial non-overlapping beam geometry and a computed tomography (CT) algorithm to map the concentrations in a plane. In...

  5. Evolution of the Cranial Computed Tomography Scan in Child Abuse.

    ERIC Educational Resources Information Center

    Feldman, Kenneth W.; And Others

    1995-01-01

    A retrospective review of medical charts for 34 children with a diagnosis of child abuse, who had cranial computed tomography scans performed, revealed that some scans initially interpreted as normal were subsequently reinterpreted as abnormal, and some children's repeat scannings were interpreted as abnormal, modifying the medical and legal…

  6. 21 CFR 892.1200 - Emission computed tomography system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Emission computed tomography system. 892.1200 Section 892.1200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... location and distribution of gamma ray- and positron-emitting radionuclides in the body and produce...

  7. 21 CFR 892.1200 - Emission computed tomography system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Emission computed tomography system. 892.1200 Section 892.1200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... location and distribution of gamma ray- and positron-emitting radionuclides in the body and produce...

  8. 21 CFR 892.1200 - Emission computed tomography system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Emission computed tomography system. 892.1200 Section 892.1200 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... location and distribution of gamma ray- and positron-emitting radionuclides in the body and produce...

  9. Cystosarcoma phylloides: calcified pulmonary metastases detected by computed tomography.

    PubMed

    Samuels, T; Kerenyi, N; Hamilton, P

    1990-08-01

    We report the appearance of calcifications on computed tomography (CT) images of pulmonary metastases from a rare breast tumor, malignant cystosarcoma phylloides. Histologic examination of the pulmonary masses revealed malignant spindle cells with osteoid and cartilage components in the cellular stroma. This appearance has not been described previously. PMID:2169970

  10. Computed tomography studies of lung ventilation and perfusion.

    PubMed

    Hoffman, Eric A; Chon, Deokiee

    2005-01-01

    With the emergence of multidetector-row computed tomography (CT) it is now possible to image both structure and function via use of a single imaging modality. Breath-hold spiral CT provides detail of the airway and vascular trees along with texture reflective of the state of the lung parenchyma. Use of stable xenon gas wash-in and/or wash-out methods using an axial mode of the CT scanner whereby images are acquired through gating to the respiratory cycle provide detailed images of regional ventilation with isotropic voxel dimensions now on the order of 0.4 mm. Axial scanning during a breath hold and gating to the electrocardiogram during the passage of a sharp bolus injection of iodinated contrast agent provide detailed images of regional pulmonary perfusion. These dynamic CT methods for the study of regional lung function are discussed in the context of other methods that have been used to study heterogeneity of lung function. PMID:16352755