Filtered backprojection implementation of the immediately-after-backprojection filtering.

In an iterative image reconstruction algorithm, it was demonstrated that the contrast-to-noise ratio in the final reconstruction could be improved if a low-pass filter was applied to the backprojction of the projection-domain discrepancy, and then this backprojection was used to update the image from the previous iteration. The goal of this paper is to extend this method to the weighted filtered backprojection (FBP) algorithm.