Analytical formula for two-dimensional ring artefact suppression

Abstract

Ring artefacts are the most disturbing artefacts when reconstructed volumes are segmented. A lot of effort has already been put into better X-ray optics, scintillators and detectors in order to minimize the appearance of these artefacts. However, additional processing is often required after standard flatfield correction. Several methods exist to suppress artefacts. One group of methods is based on minimization of the Tikhonov functional. An analytical formula for processing of a single sinogram was developed. In this paper a similar approach is used and a formula for processing two-dimensional projections is found. Thus suppression of ring artefacts is organized as a twodimensional convolution of 'averaged' projections with a given filter. Several approaches are discussed in order to find elements of the filter in a faster and accurate way. Examples of experimental datasets processed by the proposed method are considered.