说明：  图像重建的算法有迭代算法，滤波反投影，加权算法等，此为图像迭代算法。
(Set of functions performing ct reconstruction tasks like a radon transformation, a simple backprojection, a filtered backprojection using a convolution in the spatial domain, a filtered backprojection using a 2D Fourier transformation, and a filtered back projection using the central slice theorem.)