Iterative Reconstruction for X-Ray Dark Field Imaging CT: Artifacts Reduction for Hard and Soft Mixture Tissue

Naoki Sunaguchi, Tetsuya Yuasa, and Masami Ando

Keywords

Iterative reconstruction algorithm, Analyzerbased phase constrast CT, Refractive index, Computed tomography, Synchrotron xray

Abstract

Phase-contrast x-ray CT using refraction angle analyzer crystal can delineate biological soft tissues in a much higher contrast than that of conventional absorption-contrast CT. However, if an object includes bones or calcified tissues region, they generate radial artifacts similar to the metal artifacts occurring in clinical CT because their refraction-indices are much higher than those of soft tissues, leading to impaired observation. In order to well observe an object composed of bones or calcified tissues and soft tissues, the artifacts should be removed. In this research, we propose a reconstruction algorithm for analyzer-based phase-contrast computed tomography (CT) applicable to biological samples including hard tissues. The algorithm is an iterative procedure that goes back and forth between a tomogram and its sinogram through the Radon transform and CT reconstruction while imposing a priori information in individual regions. We demonstrate the efficacy of the algorithm using synthetic data generated by computer simulation reflecting actual experimental conditions and actual data acquired from a foot of rat including rheumatoid arthritis by a dark field imaging system.

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