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中华放射学杂志 1991年第3期25卷 179-180页

作者：沈复兴陈堤谢从林吴琮琏中国人民解放军南京军区南京总医院

1972年,Hounsfield发明计算机体层扫描装置(CT),为医学影像诊断开拓了一个新的领域,但由于CT检测器接受信息有限,空间分辨率远低于传统x线图像。据Ter-pogossion氏测定,要提高一倍空间分辨率,需增加八倍曝射量。国外研制各种为CT机专用... 详细信息

1972年,Hounsfield发明计算机体层扫描装置(CT),为医学影像诊断开拓了一个新的领域,但由于CT检测器接受信息有限,空间分辨率远低于传统x线图像。据Ter-pogossion氏测定,要提高一倍空间分辨率,需增加八倍曝射量。国外研制各种为CT机专用的大功率x线管,价格昂贵,曝光次数仍低于常规x线机用x线管。

关键词：体层摄影术 x线计算机/仪器和设备

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广西CT机应用质量现状调查和建议

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中华放射医学与防护杂志 2008年第2期28卷 -页

作者：黄金庭陆梅英广西壮族自治区卫生监督所南宁530021

CT机的临床应用及不断升级换代,提高了疾病诊断效果.然而CT机的不断普及,显著增加了放射诊断医疗照射所致全民集体剂量[1].鉴于CT检查对受检者所致剂量不小,应提高重视其合理应用,并特别注重加强CT机的质量控制检测,优化选取操作条件和... 详细信息

CT机的临床应用及不断升级换代,提高了疾病诊断效果.然而CT机的不断普及,显著增加了放射诊断医疗照射所致全民集体剂量[1].鉴于CT检查对受检者所致剂量不小,应提高重视其合理应用,并特别注重加强CT机的质量控制检测,优化选取操作条件和参数,合理降低受检者剂量.

关键词：广西[壮族自治区] 流行病学方法体层摄影术 x线计算机/仪器和设备质量控制人类

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CT机x线管国产化尝试

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中华放射学杂志 1992年第12期26卷 852-853页

作者：王炳昆中国人民解放军第二五一医院放射科

EMI CT5005机型系美国二代全身 CT 扫描机,目前国内有相当数量用户。因该机在美国已渐淘汰,战备件来源紧张,特别是 x 线管。我科购进的旧机于1988午6月正式启用,至1989年底,原机 x 丝管损坏。直到1990年3月才从美国购来一支新品。时过2

关键词：体层摄影术 x线计算机/仪器和设备

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基于弦图的CT图像环形伪影校正

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第四军医大学学报 2009年第3期30卷 207-209页

作者：余晓锷罗君芳陈武凡南方医科大学生物医学工程学院广东广州510515

目的:基于弦图去除CT图像环形伪影.方法:在含有环形伪影数据的CT投影弦图中,通过中值滤波,Sobel检测器的边缘检测函数edge对边缘数据进行标记.结合Hough或bwlabel变换,找到弦图上线状伪影的位置.利用插值算法,去除环形伪影投影数据.并... 详细信息

目的:基于弦图去除CT图像环形伪影.方法:在含有环形伪影数据的CT投影弦图中,通过中值滤波,Sobel检测器的边缘检测函数edge对边缘数据进行标记.结合Hough或bwlabel变换,找到弦图上线状伪影的位置.利用插值算法,去除环形伪影投影数据.并采用计算机模拟对方法进行了验证.结果:实验证明测试算法有效可行.结论:Hough变换可以用于基于弦图的环形伪影校正,此外,优化结果还需调整其它一些相关参数.

关键词：体层摄影术 x线计算机/仪器和设备环形伪影弦图 Hough变换

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Transmission failure rate for computed tomography examinations in a filmless imaging department

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JOURNAL OF DIGITAL IMAGING 2000年第2期13卷 79-82页

作者： Reiner, B Siegel, E Kuzmak, P Severance, S Baltimore Vet Affairs Med Ctr Baltimore MD USA Univ Maryland Sch Med Baltimore MD 21201 USA Dept Vet Affairs Technol Serv Silver Spring MD USA

The purpose of the study was to determine the frequency and causes of unsuccessful computed tomography (CT) transmissions in a filmless imaging department and to determine the added efficiency gains provided by the sequential addition of modality worklist software and a major network upgrade. Prospective data on CT transmission error rates were recorded over an 18-month period. During the study interval, modality worklist functionality was added, followed by a network upgrade. Failed transmissions were categorized as to the source of the error (human v technical), and the specific problem encountered. Prior to the introduction of modality worklist software, the initial CT transmission failure rate was 7.6%, which was primarily the result of human error (69%), in the form of data entry error. Upon the introduction of modality worklist software, the transmission failure rate decreased to 3.5%, with human error accounting for only 16% of all failed transmissions. The subsequent addition of a network upgrade from shared Ethernet to switched Ethernet further reduced the transmission failure rate to 2.0%, which was believed to be the result of a reduction in the number of network collisions. Other sources of failed transmission occur at the levels of the CT scanner (network interface card), picture archiving and communication system (PACS)/hospital information system (HIS) interface, and modality gateway. When planning the transmission from film-based to filmless operation, one should consider various hardware, software, and infrastructural requirements to ensure successful PACS implementation. Software upgrades, in the form of modality worklist software, serve to improve technologist productivity by minimizing data entry error. Infrastructural changes, in the form of network upgrading, ensure proper dissemination of electronic data with decreased frequency of network collisions. Collectively, these improvements lead to enhanced transmission of digital images, resulting i

关键词：计算机通信网络效率设备失效分析放射学信息系统/仪器和设备软件体层摄影术 x线计算机/仪器和设备人类

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Cable modem access to picture archiving and communication system images using a web browser over the internet

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JOURNAL OF DIGITAL IMAGING 2000年第2期13卷 93-96页

作者： Bennett, WF Spigos, DG Vaswani, KV Terrell, JE Ohio State Univ Med Ctr Columbus OH 43210 USA

This presentation describes our experiences using a web-based viewing software and a browser to view our picture archiving and communication system (PACS) images at a remote site with cable modem-internet communications. Our testing shows that using a cable modem to access our radiology webserver produces acceptable transmission speeds to remote sites. The average time-to-display (TTD) for 16 computed tomography (CT) images on the web-based intranet system in our hospital was 7 to 8 seconds. Using a cable modem and comparable equipment at a remote site, the average TTD is 16 seconds over the internet. The TTD does not significantly change during various hours of the day. Security for our hospital-based PACS is provided by a firewall. Access through the firewall is accomplished using virtual private network (VPN) software, a secure ID, and encryption. We have found that this is a viable method for after-hours subspecialty radiology consultation. Copyright (C) 2000 by W.B. Saunders Company.

关键词：医学科学研究中心计算机安全计算机系统医院信息系统因特网/仪器和设备调制解调器俄亥俄放射学信息系统/仪器和设备软件设计远程放射学/仪器和设备体层摄影术 x线计算机/仪器和设备人类

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Registration using tomographic projection files

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PHYSICS IN MEDICINE AND BIOLOGY 1999年第2期44卷 495-507页

作者： Fitchard, EE Aldridge, JS Ruchala, K Fang, G Balog, J Pearson, DW Olivera, GH Schloesser, EA Wenman, D Reckwerdt, PJ Mackie, TR Univ Wisconsin Dept Med Phys Madison WI 53706 USA

An algorithm has been developed and experimentally verified for tomographic registration-a patient positioning method using internal anatomy and standard external fiducial marks. This algorithm improves patient set-up and verification to an accuracy sufficient for tomotherapy. By implementation of this technique, the time-consuming reconstruction process is avoided. Instead, offsets in the x, y and z directions are determined directly from sinogram data by an algorithm that utilizes cross-correlations and Fourier transforms. To verify the efficiency and stability of the algorithm, data were collected on the University of Wisconsin's dedicated tomotherapy research workbench. The experiment indicates offset statistical errors of less than +/-0.8 mm for offsets up to 30 mm. With standard clinical techniques, initial patient offsets are expected to be less than 5 mm, so the 30 mm limitation is of no consequence. The angular resolution for the direction of patient translation is within the +/-2 degrees needed for tomotherapy.

关键词：算法设备设计傅里叶分析模型理论体模显象术体位放射治疗计划计算机辅助/仪器和设备放射治疗计划计算机辅助/方法结果可重复性体层摄影术 x线计算机/仪器和设备体层摄影术 x线计算机/方法水人类

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A new needle-crystalline computed radiography detector

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JOURNAL OF DIGITAL IMAGING 2000年第2期13卷 117-120页

作者： Leblans, P Struye, L Willems, P Agfa Gevaert NV B-2640 Mortsel Belgium

The most successful digital radiography detectors to date have been storage phosphor plates used in computed radiography (CR), The detector is cheap, has good producibility, and is robust. Direct radiography (DR) systems are being developed based on flat-panel technology. Better image quality is claimed for some DR systems. On the other hand, DR detectors have low producibility and robustness, and a high price. A new CR detector is being developed at Agfa that combines the advantages of CR and DR. It is a storage phosphor plate made up of needle-shaped crystals. The phosphor efficiently converts absorbed x-ray quanta into photostimulable centers for efficient read out. It has a large dynamic range and its emision is efficiently detected with both photomultiplier tube (PMT) and charge coupled device (CCD). It is shown that CR systems based on the new detector offer image quality that matches that of the best DR systems. Copyright (C) 2000 by W.B. Saunders Company.

关键词：计算机存储设备设备设计 x线影像增强/仪器和设备工艺学放射学体层摄影术 x线计算机/仪器和设备 x线增感屏人类

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Shape-based grey-level image interpolation

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PHYSICS IN MEDICINE AND BIOLOGY 1999年第6期44卷 1565-1577页

作者： Chuang, KS Chen, CY Yuan, LJ Yeh, CK Natl Tsing Hua Univ Dept Nucl Sci Hsinchu 30043 Taiwan Atom Energy Council Inst Nucl Energy Res Div Phys Taipei Taiwan

The three-dimensional (3D) object data obtained from a CT scanner usually have unequal sampling frequencies in the x-, y- and z-directions. Generally, the 3D data are first interpolated between slices to obtain isotropic resolution, reconstructed, then operated on using object extraction and display algorithms. The traditional grey-level interpolation introduces a layer of intermediate substance and is not suitable for objects that are very different from the opposite background. The shape-based interpolation method transfers a pixel location to a parameter related to the object shape and the interpolation is performed on that parameter. This process is able to achieve a better interpolation but its application is limited to binary images only, in this paper, we present an improved shape-based interpolation method for grey-level images. The new method uses a polygon to approximate the object shape and performs the interpolation using polygon vertices as references. The binary images representing the shape of the object were first generated via image segmentation on the source images. The target object binary image was then created using regular shape-based interpolation. The polygon enclosing the object for each slice can be generated from the shape of that slice. We determined the relative location in the source slices of each pixel inside the target polygon using the vertices of a polygon as the reference. The target slice grey-level was interpolated from the corresponding source image pixels. The image quality of this interpolation method is better and the mean squared difference is smaller than with traditional grey-level interpolation.

关键词：图像增强/仪器和设备图像增强/方法模型理论体层摄影术 x线计算机/仪器和设备

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

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PHYSICS IN MEDICINE AND BIOLOGY 1999年第9期44卷 2201-2211页

作者： Watanabe, Y Columbia Univ Dept Radiat Oncol New York NY 10032 USA

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

关键词：近距离放射疗法模型生物学模型统计学体模显象术光子放射治疗计划计算机辅助/方法散射辐射体层摄影术 x线计算机/仪器和设备体层摄影术 x线计算机/方法人类

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