Iterative image reconstruction with variable resolution in CT

For some applications in computed tomography (CT), precise knowledge of the subject within a particular region of interest (ROI) is often desired, while rough (or little) knowledge outside the ROI is sufficient. Therefore, it is of practical merit to develop iterative algorithms for reconstructing a high-resolution ROI image while yielding a coarse image outside the ROI. Conventional iterative algorithms can only yield image values on the entire array of discrete grids. In this work, we investigate and develop an iterative algorithm for image reconstruction with variable spatial resolution. Our results show that the proposed approach can yield ROI images of high resolution.