Object removal in gradient domain of cone-beam CT projections

Abstract

We propose a method to reduce streak artifacts in cone-beam CT reconstructions that arise from the edges of dense objects outside the 3D field-of-view. To this end, ramp filtering is decomposed into a derivative- and a Hilbert transform step. This allows for spectral inpainting directly in gradient domain, such that only contributions of sharp edges are removed. We applied our approach to weight-bearing knee imaging data, where plastic pipes outside the field-of-view introduce notable streak artifacts. Streak artifacts in the reconstructions are reduced and on semi-simulated data the correlation coefficient could be improved from 0.88 to 0.99. The method is applicable for arbitrary object shapes and can be easily integrated into existing FDK reconstruction algorithms.