A scanning system for chest radiography with regional exposure control: theoretical considerations.
A scanning system for chest radiography with regional exposure control: theoretical considerations.
复制标题
具有区域曝光控制的胸部放射线摄影扫描系统：理论考虑。
DOI：
10.1118/1.595327
复制
发表时间：
1983
期刊：
影响因子：
3.8
通讯作者：
Plewes,DB
中科院分区：
文献类型：
--
作者：
Plewes,DB
传统的胸部X线摄影受到散射辐射的存在和X线胶片有效曝光范围小的限制。一个计算机辅助扫描系统，以尽量减少这两个影响的概述。该系统使用一个小的辐射束以光栅模式扫过患者的胸部，以曝光传统的胶片盒，而在患者和胶片之间扫描的狭缝准直器用于拒绝散射光子。微型计算机通过放置在胶片后面的探测器测量患者的射束衰减，该探测器反过来自动调整X射线管输出，以最大限度地减少射束扫描时胶片曝光的偏移。本文提出了一种将病人传输和胶片曝光分布联系起来的形式，并给出了系统的传递函数。它示出，这样的系统作为一个空间滤波器，衰减的空间频率小于反向扫描光束宽度的结构的电影对比度。通过操纵反馈网络的软件参数，可以改变该滤波器并产生具有低空间频率增强、衰减或对比度反转的射线照片。
Conventional chest radiography is limited by the presence of scattered radiation and the small useful exposure range of radiographic film. A computer‐assisted scanning system to minimize these two effects is outlined. The system uses a small beam of radiation swept over the patient's chest in a raster pattern to expose a conventional film cassette, while a slit collimator scanning between the patient and the film serves to reject scattered photons. A microcomputer measures beam attenuation by the patient with a detector placed behind the film which in turn automatically adjusts the x‐ray tube output to minimize excursions in film exposure as the beam scans. A formalism which relates the patient transmission and film exposure distribution is developed and a system transfer function is given. It is shown that such a system operates as a spatial filter which attenuates film contrast for structures of spatial frequency less than the inverse scanning beam width. By manipulating the software parameters of the feedback network, it is possible to alter this filter and produce radiographs with low spatial frequency enhancement, attenuation, or contrast inversion.