A dual‐domain regularization method for ring artifact removal of X‐ray CT

Background Photon‐counting detectors (PCDs) offer improved spatial resolution and dose efficiency. However, as a new X‐ray detection device, PCD faces technical challenges, particularly the non‐uniformity among detector units, which can lead to ring artifacts in reconstructed CT images. Purpose To address this challenge, we propose a dual‐domain regularization model to effectively remove ring artifacts while maintaining the integrity of the original CT image. Methods The proposed model corrects the vertical stripe artifacts on the sinogram by innovatively updating the response inconsistency compensation coefficients of detector units, which is achieved by employing the group sparse constraint and the projection‐view direction sparse constraint on the stripe artifacts. Simultaneously, we apply the sparse constraint on the reconstructed image to further rectify ring artifacts in the image domain. The key advantage of the proposed method lies in considering the relationship between the response inconsistency compensation coefficients of the detector units and the projection views, which enables a more accurate correction of the response of the detector units. An alternating minimization method is designed to solve the model. Results Comparative experiments on simulated data and real PCD data demonstrate that the proposed method outperforms existing correction methods in artifact suppression while better preserving structural details. Conclusions The proposed method can effectively mitigate ring artifacts in PCD‐reconstructed CT images while preserving details, thereby enhancing image quality and improving the reliability of clinical diagnosis.