中文说明：用于仿真实现三维锥束CT正投影算法，该算法是运用射线穿过重建区域时用射线束也模体的交线的长度与体素值的累加乘积，这样得出的正投影数据精度高。
English Description：
Used for simulating three-dimensional cone-beam CT orthographic projection algorithm, which is the product of the beam length and the cumulative value of the voxel phantoms cross the line when you are using the rays pass through the reconstruction area, high accuracy of the data so obtained orthographic .