Hardware based contrast enhancement and cupping reduction in industrial MeV Cone Beam Computed Tomography

This work investigates a detector sided filter concept for contrast enhancement and cupping reduction in an industrial Mega Electronvolt (MeV) Cone Beam Computed Tomography (CBCT) system employing a 6 MeV linear accelerator source and a commercial Gadox based flat panel imager. The method was evaluated using a steel step cylinder sample in order to test the efficiency of the hardware based improvement for various material transmission lengths. An overall improvement of the reconstructed signal for the suggested detector filter configurations with respect to the non-filtered measurements can be observed. Furthermore, equivalent source sided filtrations are shown to be less effective than their detector sided counterpart. Of the detector filter configurations studied in this work, a 2 mm lead filter caused the maximal contrast enhancement, while a 5 mm copper filter lead to better results with regard to cupping artefact reduction.