Radially-dependent nonlinear sinogram filtering

This work concentrates on the effects of angular sinogram filtering in nonlinear backprojection (NBP). Previous studies have shown that angular filtering of a sinogram may introduce nonuniform resolution loss in the reconstruction. To counteract this effect, we have introduced nonlinear filtering with angular characteristics dependent on distance from the center of the sinogram of the region where they are applied. First, the effects of variable-length linear angular filtering as a pre-processing before filtered backprojection has been studied; the same principles are then applied to NBP.