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Computed Tomographic Angiography (CTA) in Vascular Trauma
M. Tehrai
Iranian Journal of Radiology , 2007,
Abstract: In the evaluation of trauma patients, computed tomo-graphy and CT angiography (CTA) are powerful non-invasive tools that provide a large amount of informa-tion in so little time that they have virtually replaced plain film radiography and catheter angiography. In our hospital, CTA has replaced catheter angiogra-phy for diagnosing most vascular injuries, resulting from penetrating and blunt trauma to head, neck, thorax, abdomen and extremities. This lecture will cover current imaging protocols with MSCT, the spectrum of diagnostic findings in vascular trauma and the role of CTA in the planning of vascular injury management.
Coronary computed tomography angiography in coronary artery disease  [cached]
Zhonghua Sun,Kwan-Hoong Ng
World Journal of Cardiology , 2011, DOI: 10.4330/wjc.v3.i9.303
Abstract: AIM: To investigate the research directions of coronary computed tomography (CT) angiography in the diagnosis of coronary artery disease (CAD) based on a systematic review of the literature. METHODS: A search of articles on coronary CT angiography in the diagnosis of CAD was performed during a 6-year-period between 2005 and 2010 from five main radiology journals namely, Radiology, American Journal of Roentgenology, European Radiology, European Journal of Radiology and British Journal of Radiology. Analysis of the references was focused on the research directions of coronary CT angiography with regard to the type of studies in terms of diagnostic value, application of dose-reduction strategies and resultant effective radiation doses with use of these techniques. RESULTS: One hundred and forty two studies were identified which met the selection criteria and were included in the analysis. 64-slice CT (single source and dual-source CT) dominated 78% of the coronary CT angiography studies. Prior to 2007, research was focused on the diagnostic value of coronary CT angiography, but since 2008 more attention has been paid to radiation dose reduction. Radiation dose was reported in 64 studies, representing 45% of total studies published in the five radiology journals. Various dose-saving strategies have been implemented and prospective electrocardiography-triggering and high pitch techniques were found to be the most effective approaches for radiation dose reduction, with the corresponding mean effective dose being 3.5 ± 1.9 mSv and 1.7 ± 0.6 mSv, respectively. CONCLUSION: This review shows that the current research in coronary CT angiography has shifted from the previous focus on diagnostic accuracy in CAD to more emphasis on radiation dose reduction.
Use of Computed Tomography Angiography in Hodgkin Lymphoma Survivors  [cached]
Serhan Kupeli
Arsiv Kaynak Tarama Dergisi , 2013,
Abstract: In the treatment of Hodgkin lymphoma, anthracyclines known to be cardiotoxic and radiotherapy to the involved lymphatic areas are frequently used. In literature deaths from myocardial infarction at young ages after Hodgkin lymphoma have been reported. The real incidence of cardiovascular diseases in patients treated for Hodgkin lymphoma is not known. There is a significant correlation between mediastinal radiotherapy and development of a coronary artery abnormality. Coronary computed tomography angiography is an useful and noninvasive tool for early diagnosis of coronary artery disease in patients who were treated with mediastinal radiotherapy and/or cardiotoxic chemotherapy like most of the cases with Hodgkin lymphoma. [Archives Medical Review Journal 2013; 22(4.000): 543-564]
Topography induced optical spectral shifts and finite size effect of focal spot  [PDF]
V. Tishkova,W. S. Bacsa
Physics , 2010,
Abstract: We observe topography induced spectral shifts using high resolution grating spectrometers which we attribute to the fact that the focal spot has a finite size. The topography induced spectral shifts depend on spectrometer grating orientation and numerical aperture of the microscope objective. This is demonstrated by spectroscopic imaging trenches in GaAs in directions parallel and perpendicular the spectrometer entrance slit. Differences along the two directions of the LO phonon band show that the spectral shift is due to the variation of the grating angle across the non uniform illuminated focal spot caused by topography. Alignment errors of the optical axis lead to additional spectral shifts. Topography induced spectral shifts can be detected by recording spectra by scanning the sample in two perpendicular orientations with respect to the spectrometer entrance slit.
The focus of light - linear polarization breaks the rotational symmetry of the focal spot  [PDF]
Ralf Dorn,Susanne Quabis,Gerd Leuchs
Physics , 2003, DOI: 10.1080/09500340308235246
Abstract: We experimentally demonstrate for the first time that a linearly polarized beam is focussed to an asymmetric spot when using a high-numerical aperture focussing system. This asymmetry was predicted by Richards and Wolf [Proc.R.Soc.London A, 253, 358 (1959)] and can only be measured when a polarization insensitive sensor is placed in the focal region. We used a specially modified photodiode in a knife edge type set up to obtain highly resolved images of the total electric energy density distribution at the focus. The results are in good agreement with the predictions of a vectorial focussing theory.
Reduced Radiation Exposure for Face Transplant Surgical Planning Computed Tomography Angiography  [PDF]
Kurt Schultz, Elizabeth George, Katherine M. Mullen, Michael L. Steigner, Dimitrios Mitsouras, Ericka M. Bueno, Bohdan Pomahac, Frank J. Rybicki, Kanako K. Kumamaru
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063079
Abstract: Objective To test the hypothesis that wide area detector face transplant surgical planning CT angiograms with simulated lower radiation dose and iterative reconstruction (AIDR3D) are comparable in image quality to those with standard tube current and filtered back projection (FBP) reconstruction. Materials and Methods The sinograms from 320-detector row CT angiography of four clinical candidates for face transplantation were processed utilizing standard FBP, FBP with simulated 75, 62, and 50% tube current, and AIDR3D with corresponding dose reduction. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured at muscle, fat, artery, and vein. Image quality for each reconstruction strategy was assessed by two independent readers using a 4-point scale. Results Compared to FBP, the median SNR and CNR for AIDR3D images were higher at all sites for all 4 different tube currents. The AIDR3D with simulated 50% tube current achieved comparable SNR and CNR to FBP with standard dose (median muscle SNR: 5.77 vs. 6.23; fat SNR: 6.40 vs. 5.75; artery SNR: 43.8 vs. 45.0; vein SNR: 54.9 vs. 55.7; artery CNR: 38.1 vs. 38.6; vein CNR: 49.0 vs. 48.7; all p-values >0.19). The interobserver agreement in the image quality score was good (weighted κ = 0.7). The overall score and the scores for smaller arteries were significantly lower when FBP with 50% dose reduction was used. The AIDR3D reconstruction images with 4 different simulated doses achieved a mean score ranging from 3.68 to 3.82 that were comparable to the scores from images reconstructed using FBP with original dose (3.68–3.77). Conclusions Simulated radiation dose reduction applied to clinical CT angiography for face transplant planning suggests that AIDR3D allows for a 50% reduction in radiation dose, as compared to FBP, while preserving image quality.
High-Pitch Computed Tomography Coronary Angiography—A New Dose-Saving Algorithm: Estimation of Radiation Exposure  [PDF]
Dominik Ketelsen,Markus Buchgeister,Andreas Korn,Michael Fenchel,Bernhard Schmidt,Thomas G. Flohr,Christoph Thomas,Christoph Schabel,Ilias Tsiflikas,Roland Syha,Claus D. Claussen,Martin Heuschmid
Radiology Research and Practice , 2012, DOI: 10.1155/2012/724129
Abstract: Purpose. To estimate effective dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. Materials and Methods. For dose measurements, an Alderson-Rando phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a second-generation dual-source scanner (SOMATOM Definition Flash, Siemens Medical Solutions, Germany). The following scan parameters were used: 320?mAs per rotation, 100 and 120?kV, pitch 3.4 for prospectively ECG-triggered high-pitch CTCA, scan range of 13.5?cm, collimation ?mm with z-flying focal spot, gantry rotation time 280?ms, and simulated heart rate of 60 beats per minute. Results. Depending on the applied tube potential, the effective whole-body dose of the cardiac scan ranged from 1.1?mSv to 1.6?mSv and from 1.2 to 1.8?mSv for males and females, respectively. The radiosensitive breast tissue in the range of the primary beam caused an increased female-specific effective dose of % compared to males. Decreasing the tube potential, a significant reduction of the effective dose of 35.8% and 36.0% can be achieved for males and females, respectively ( ). Conclusion. The radiologist and the CT technician should be aware of this new dose-saving strategy to keep the radiation exposure as low as reasonablly achievable. 1. Introduction At present, computed tomography coronary angiography (CTCA) is an important, widely accepted diagnostic tool for the assessment of coronary artery disease. Several studies have shown the potential of different dose-saving strategies to keep the radiation exposure as low as reasonablly achievable. Hausleiter et al. reported in an international multicenter trial (PROTECTION I) a mean effective dose of 12?mSv in CTCA, ranging from 5 to 30?mSv [1]. Radiation exposure can be reduced substantially by currently available strategies, but these possibilities are used infrequently [1]. Since the introduction of a second-generation dual-source scanner system, a new scanning mode with increased table feed is available. Compared to retrospective ECG-gated and prospective ECG-triggered CTCA, this high-pitch, prospective triggered scanning mode has the potential for drastic dose reduction due to a gapless imaging of the heart within one heartbeat with no overlapping data acquisition. The aim of the study was to estimate effective whole-body dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. 2. Material and Methods 2.1. Dosimetry The experiments were performed by using an anthropomorphic,
Multislice computed tomography angiography in the diagnosis of coronary artery disease

Sun Zhong-Hua,Cao Yan,Li Hua-Feng,

老年心脏病学杂志(英文版) , 2011,
Abstract: Multislice CT angiography represents one of the most exciting technological revolutions in cardiac imaging and it has been increasingly used in the diagnosis of coronary artery disease. Rapid improvements in multislice CT scanners over the last decade have allowed this technique to become a potentially effective alternative to invasive coronary angiography in patients with suspected coronary artery disease. High diagnostic value has been achieved with multislice CT angiography with use of 64- and more slice CT scanners. In addition, multislice CT angiography shows accurate detection and analysis of coronary calcium, characterization of coronary plaques, as well as prediction of the disease progression and major cardiac events. Thus, patients can benefit from multislice CT angiography that provides a rapid and accurate diagnosis while avoiding unnecessary invasive coronary angiography procedures. The aim of this article is present an overview of the clinical applications of multislice CT angiography in coronary artery disease with a focus on the diagnostic accuracy of coronary artery disease; prognostic value of coronary artery disease with regard to the prediction of major cardiac events; detection and quantification of coronary calcium and characterization of coronary plaques. Limitations of multislice CT angiography in coronary artery disease are also briefly discussed, and future directions are highlighted.
Multislice computed tomography angiography in the diagnosis of coronary artery disease
Zhong-Hua Sun,Yan Cao,Hua-Feng Li
老年心脏病学杂志(英文版) , 2011,
Abstract: Multislice CT angiography represents one of the most exciting technological revolutions in cardiac imaging and it has been increasingly used in the diagnosis of coronary artery disease. Rapid improvements in multislice CT scanners over the last decade have allowed this technique to become a potentially effective alternative to invasive coronary angiography in patients with suspected coronary artery disease. High diagnostic value has been achieved with multislice CT angiography with use of 64- and more slice CT scanners. In addition, multislice CT angiography shows accurate detection and analysis of coronary calcium, characterization of coronary plaques, as well as prediction of the disease progression and major cardiac events. Thus, patients can benefit from multislice CT angiography that provides a rapid and accurate diagnosis while avoiding unnecessary invasive coronary angiography procedures. The aim of this article is present an overview of the clinical applications of multislice CT angiography in coronary artery disease with a focus on the diagnostic accuracy of coronary artery disease; prognostic value of coronary artery disease with regard to the prediction of major cardiac events; detection and quantification of coronary calcium and characterization of coronary plaques. Limitations of multislice CT angiography in coronary artery disease are also briefly discussed, and future directions are highlighted.
The Analysis of Focal Spot of Geodesic Lenses
光波导短程透镜焦点特性的分析

刘支华,石邦任,武继江,孔梅
光子学报 , 2005,
Abstract: Utilization of geometric optical characters of geodesic lenses, the equivalent light trail and phase transfer function are given. Simultaneously the distributing model is obtained. The focal spot intensity distribution of theory corresponds with the experiments.
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