运用滤波反投影来还原若当变换后的CT图像，并通过改变滤波器类型与插值方法评价还原图像好坏。运行前需修改文件路径-Filter backprojection is used to restore the CT image after Randon transformation, and the image quality is　uated by changing the filter type and interpolation method. Before the operation，you need to modify the file path