Prior Image Guided Ring Artifact Correction for Photon-Counting Detector Data in Hybrid Spectral CT.

Objective: Photon-counting detector (PCD) is an advanced and innovative X-ray detector, that offers significant advantages such as improved spatial resolution and higher 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. To address this challenge, we propose a novel image-domain post-processing method to effectively correct ring artifacts in PCD-reconstructed images.

Method: The method is specifically designed for a self-developed hybrid spectral CT system equipped with both a PCD and an energy integration detector (EID). The ring artifact-free EID-reconstructed images are used as prior images to guide the correction of ring artifacts in the PCD-reconstructed images. In addition, a carefully designed weight is introduced in the optimization model to prevent the degradation of boundary details in the target images caused by blurred edges in prior images.

Results: The effectiveness of the proposed method is validated on both simulated data and real data, demonstrating that the proposed method can efficiently and effectively correct ring artifacts in the reconstructed images of PCD.

Significance: This confirms that the proposed method provides a practical solution for hybrid spectral CT imaging.