Over-Exposure Correction in CT Using Optimization-Based Multiple Cylinder Fitting

Abstract

Flat-Panel Computed Tomography (CT) has found its commonly used applications in the healthcare field by providing an approach of examining 3D structural information of a human’s body. The popular CT reconstruction algorithms are based on a filtered backprojection (FBP) scheme, which would face challenges when imaging the knee. This because in some views, the X-rays are highly attenuated when traveling through both thigh bones. In the same view, X-rays also travel through soft tissue that absorbs much less energy with respect to bone. When these high intensity X-rays arrive at the detector they cause detector saturation and the generated sinogram suffers from overexposure. Reconstructing an overexposed sinogram results in images with streaking and cupping artifacts, which are unusable for diagnostics. In this paper we propose a method to correct overexposure artifacts using an optimization approach. Parameters describing a specific geometry are determined by thc optimization and then used to extrapolate the overexposed acquisition data.