Joint Reconstruction and Flat-Field Estimation using Support Estimation

Reconstructions from X-ray computed tomography scans often suffer from ring artefacts, caused by non-uniformity in the response of different detector pixels. To reduce these artefacts, flat-fields are obtained and used to normalize each subsequent scan. Any discrepancies between the acquired flat-field and the true flat-field at the time of scanning will still lead to ring artefacts. We propose a novel method in the class of joint reconstruction and estimation algorithms, in which we simultaneously calculate a reconstruction and estimate a flat-field. The proposed method models the reconstruction-estimation problem as a single system of linear equations, which can be solved using fast Krylov methods. Significant reduction of ring artefacts in both simulated and real data is shown.