Device for reducing ring artefacts in CT images

摘要

A device for reducing annular artefacts positioned concentrically to the centre of the area of examination of a computer tomograph and superimposed on the reconstructed image of the computer tomograph, the device having a filter which filters the image values of the reconstructed image along straight lines through the centre of the area of examination in such a manner that at the output of the filter, correction image values are generated which virtually now only represent those image structures with a radial width which corresponds to the radial width of the artefacts, the amplitudes of the correction image values being obtained from the image values at the location of the image structures reduced by the image values representing the respective image background in the vicinity of the image structures, and a first subtracting stage being provided which subtracts the correction image values from the reconstructed image values. <IMAGE>