DuDo-RAC: Dual-domain optimization for ring artifact correction in photon counting CT.

Background And Objective: Due to the inconsistent response of photon counting detectors (PCDs) pixels to X-rays, there is an obvious presence of low-frequency ring artifacts in CT reconstructed images. Traditional CT ring artifact correction methods are ineffective in correcting low-frequency ring artifacts. Although the pixel-wise polynomial correction method can correct low-frequency ring artifacts, there may still remain residual artifacts due to the inaccuracy in the coefficient measurement and the inability of polynomial functions to perfectly model the relationship between the thickness and post-log raw data.