Fast Monte Carlo calculation of scatter corrections for CBCT images

Abstract

A very fast Monte Carlo algorithm for the calculation of the scatter contribution in cone beam computed tomography, implemented within the EGSnrc framework, is presented. Based on the combination of several variance reduction techniques, an efficiency improvement of three orders of magnitude over an analog simulation is obtained. A denoising algorithm applied to the computed scatter distribution is shown to further increase the efficiency of the calculation by about a factor of 10. An iterative scatter correction algorithm is proposed and its feasibility is demonstrated on three different phantoms.