REGION-BASED MOTION-COMPENSATED ITERATIVE RECONSTRUCTION TECHNIQUE FOR DYNAMIC COMPUTED TOMOGRAPHY

Abstract

Current state-of-the-art motion-based dynamic computed tomography reconstruction techniques estimate the deformation by considering motion models in the entire object volume although occasionally the proper change is local. In this article, we address this issue by introducing the region-based Motion-compensated Iterative Reconstruction Technique (rMIRT). It aims to accurately reconstruct the object being locally deformed during the scan, while identifying the deformed regions consistently with the motion models. Moreover, the motion parameters that correspond to the deformation in those areas are also estimated. In order to achieve these goals, we consider a mathematical optimization problem whose objective function depends on the reconstruction, the deformed regions and the motion parameters. While dynamic CT methods that specifically locate the regional changes in the object volume are not widely found in the literature, our method exploits the analytical derivative towards these changing regions, which allows for efficient reconstruction using gradient-based optimizers.