说明：  本程序在matlab中运行。 Generate_SystemMatrix是一个计算OSEM，MLEM迭代图像算法中系统矩阵的函数，其用法Generate_SystemMatrix（pixel），为所要重建图像的大小，一般为64,128,256，pixel也大运算越慢。 里面的diedai-test文件是一个简单的MLEM重建算法，其中要加载SystemMatrix矩阵就是Generate_SystemMatrix(128)的结果，注意如果要运行diedai-test，生成的系统矩阵名要保存为SystemMatrix，否则出错。 testsino是一个正弦图实例，就是MLEM算法中的投影矩阵，机算是数据。
(This program is run in matlab. The Generate_SystemMatrix is ​ ​ a calculation of the OSEM, a function of the system matrix MLEM iterative image algorithm, its use Generate_SystemMatrix (pixel) to rebuild the image size, usually 64,128,256, pixel also large computing slower. Inside diedai-test file is a simple MLEM reconstruction algorithm, which load SystemMatrix matrix is ​ ​ the result of Generate_SystemMatrix (128), pay attention to if you want to to run diedai-test, the generated system matrix is ​ ​ saved as SystemMatrix, otherwise an error. testsino instance of a sinogram projection matrix MLEM algorithm, machine be regarded as data.)