说明：  CT图像重建，仿真人脑体模仿真数据与实际的CT图像数据进行滤波反投影重建，比较直接反投影与R--L和S-L滤波方法的重建结果
(CT image reconstruction, the simulation of the human brain to imitate true body CT image data and the actual data is filtered back projection reconstruction, more direct back-projection and R- L and SL reconstruction filtering method)