Improving the visual quality of median root prior images in PET and SPECT reconstruction

The median root prior (MRP) iterative reconstruction algorithm favors locally monotonic images. MRP preserves sharp edges while reducing noise at the same time. Quantitative properties of MRP are good, because a sufficiently high number of iterations can be run. In order to make the visual quality of MRP images more conventional, the standard median was replaced by other order statistic operations, the L- and FMH-filters. They allow for smoother appearance as they apply linear weighting together with nonlinear operations. The images reconstructed using the new MRP-L and MRP-FMH priors are visually more appealing. Good quantitative properties of MRP are not significantly altered by the new priors.