Meertens H, van Herk M, Weeda J
Phys Med Biol. 1985 Apr;30(4):313-21. doi: 10.1088/0031-9155/30/4/004.
Experiments with an ionisation detector were performed in order to determine whether it was possible to obtain high energy photon beam images for radiotherapy treatment verification. A small prototype detector with a field of view of 78 mm X 78 mm and constructed from printed circuit boards was used. The imaging area was a matrix ionisation chamber, filled with air or liquid (2,2,4-trimethylpentane). A minicomputer was used to control the data acquisition electronics and to reconstruct and restore the images. The images were displayed on a viewing console for computed tomography images. The liquid filled detector with a front-rear board separation of 1.0 mm gave the best results. The spatial resolution was about 3.8 mm with a density resolution of 0.5% for a data acquisition time of 120 s. Comparison of the liquid detector images with corresponding metal screen-film detector images showed that the image qualities were the same. An important advantage of the ionisation detector image is that grey scale modification, sharpening and smoothing by digital processing can easily be performed.
为了确定是否有可能获得用于放射治疗验证的高能光子束图像，进行了电离探测器实验。使用了一个由印刷电路板制成的、视野为78毫米×78毫米的小型原型探测器。成像区域是一个矩阵电离室，填充有空气或液体（2,2,4-三甲基戊烷）。使用一台小型计算机来控制数据采集电子设备，并重建和恢复图像。图像显示在用于计算机断层扫描图像的观察控制台上。前后板间距为1.0毫米的液体填充探测器给出了最佳结果。对于120秒的数据采集时间，空间分辨率约为3.8毫米，密度分辨率为0.5%。将液体探测器图像与相应的金属屏片探测器图像进行比较表明，图像质量相同。电离探测器图像的一个重要优点是可以很容易地通过数字处理进行灰度修改、锐化和平滑处理。
