Spurious Structures Created by Interpolation-Based CT Metal Artifact Reduction

Under normal circumstances the quality of images reconstructed with the classic FBP CT reconstruction algorithm is adequate for medical diagnosis. However, in some special cases the assumptions made by this method are violated because of non-linearities in the underlying physical imaging process. Especially in the presence of metal implants in the field of view, effects like beam hardening, scatter and photon starvation result in serious streaking and banding artifacts around and between these objects. In order to reduce these artifacts, several different types of correction methods were introduced during the last decades. One of the most prominent approaches, is to use an interpolation scheme to replace all corrupted beam data in the shadow of the metal with artificially generated values. Although this leads to a reduction of the most severe artifacts, typically the results are not that satisfying. Instead of removing all artifacts, new streak artifacts are likely to be introduced.