Ct method uses array linear detectors to perform high - resolution tomography and yield relative image of linear attenuation coefficient 测出的线衰减系数是相对的，成像要求高分辨。 tgs装置用的是同轴大体积hpge探测器。
2.
Tgs method utilizes a high - purity germanium ( hpge ) detector with large volume to perform low - resolution tomographic transmission scans on each layer and yield absolute images of the matrix ' density 测出的线衰减系数是绝对值，成像只要求低分辨。然而， tgs有ct测量所没有的发射测量和图像重建的问题。
