A CT Geometry With Multiple Centers Of Rotation For Solving Sparse View Problem

Abstract

With the emergence of CNT (Carbon nanotube), static and instant CT scanning becomes possible. By transforming the traditionally rotated thermal source into a static ring array source composed of multiple CNTs, the imaging system can achieve high temporal resolution in scanning. However, due to the non-negligible packaging size of CNTs, the static CT based on CNTs faces sparse view problem, which affects the image quality by introducing streak artifacts. In this study, we based on the local correlation equation (LCE) to address the sparse view problem of static CT. The LCE is a series of partial differential equations (PDEs) to describe the local correlation of Radon transform in a neighborhood projection domain. Based on LCE, we analyze the characteristic of sparse view projection and propose a scanning geometry with multiple rotation centers, which is different from existing CT devices that acquires the projection around one rotation center. Specifically, in the proposed scanning geometry, the circular ring array X-ray sources is divided into several arcs while the sources of each arc share one rotation center. All rotation centers of the arcs are uniformly distributed on a small circle. The optimal distribution of the rotation centers can be optimized by the radius of the circle. Moreover, to elevate the image quality under the sparse view reconstruction, we employed the LCE to interpolate unmeasured projections. Compared to the single rotation center scheme used in existing CT geometries, the multiple rotation centers scan contributes to a more even projection distribution with same view number. The simulated results demonstrated the efficiency and potential applications of the proposed method in static CT reconstructions.