实现了标准shepp-logan三维图形的重建，程序采用经典的代数替代重建算法-achieve the standard shepp - logan 3D reconstruction, procedures used to replace the classical algebraic reconstruction algorithm

实现了标准shepp-logan三维图形的重建，程序采用经典的代数替代重建算法-achieve the standard shepp- logan 3D reconstruction, procedures used to replace the classical algebraic reconstruction algorithm

filtered back projection method