A comparison of quadratic versus edge-preserving penalties for both penalized-likelihood and KCR approaches. Reconstructions of a single pedicle screw implant (truth image near the implant shown in the yellow inset) are shown for A) PL with quadratic penalty, B) PL with edge-preserving penalty, C) KCR with quadratic penalty, and D) KCR with edge-preserving penalty. The regularization parameters for PL and KCR are matched for each choice of penalty, but the edge-preserving penalty has been optimized for PL image quality. While the edge-preserving penalty may be tuned to mitigate artifacts associated with the implant in the PL reconstruction, KCR can provide nearly artifact-free reconstructions across a range of parameter choices.