Ring Artifacts Correction Based on Global-Local Features Interaction Guidance in the Projection Domain

Ring artifacts are common artifacts in CT imaging, typically caused by inconsistent responses of detector units to X-rays, resulting in stripe artifacts in the projection data. Under circular scanning mode, such artifacts manifest as concentric rings radiating from the center of rotation, severely degrading image quality. In the Radon transform domain, even if the object's density function is piecewise discontinuous in certain regions, the projection images remain nearly continuous in the angular direction, making the ideal projections exhibit a smooth global low-frequency characteristic. In practical scanning, the local disturbances of the same detector unit at different scanning angles lead to a prominent high-frequency locality of stripe artifacts. Existing studies generally model ring artifacts disturbances as fixed additive errors, which overlooks the dynamic variation of detector responses during practical scanning. However, the degree of detector response inconsistency is a function of the projection values, as revealed in our experiments, thereby requiring consideration of the interaction between global and local features in the process of stripe artifacts extraction and correction. Therefore, we propose a CT ring artifacts correction method based on global and local features in the projection domain. We employ the VSS block and Dense block to respectively correct the low-frequency sub-band, which capture the global correlations of the projection, and the high-frequency sub-band, which contain local stripe artifacts after wavelet decomposition. Specifically, the accuracy of artifacts correction is enhanced by the interaction guidance between global and local features. Extensive experiments demonstrate that our method achieves superior performance in both quantitative metrics and visual quality, verifying its robustness and practical applicability.