Patent ID: 8582855

Claim:
An apparatus for producing a corrected image of a region of interest from acquired projection data, the apparatus including: a reconstructing unit that reconstructs an uncorrected intermediate image of the region of interest from the acquired projection data, a correction unit that corrects artifacts within the uncorrected intermediate image to generate a corrected intermediate image, a classifying unit that classifies image elements of the corrected intermediate image at least into high density, medium density and low density classes, an image element replacement unit that replaces image element values of image elements of the corrected intermediate image that are of the high density and low density classes by image element values which depend on the image element values of the low density class to generate a synthetic image, a forward projecting unit that forward projects the synthetic image to generate synthetic projection data, and a projection replacement unit that replaces acquired projection data contributing to the image elements of the high density class with corresponding synthetic projection data to generate corrected projection data, wherein the reconstruction unit reconstructs a corrected image of the region of interest from the corrected projection data; wherein the correction unit comprises an identification unit for identifying high density image elements within the uncorrected intermediate image for correcting artifacts generated by the high density image elements and wherein the classifying unit is adapted for classifying the image elements of the corrected intermediate image into the high density class by using the identified high density image elements of the uncorrected intermediate image such that the image elements of the high density class of the corrected intermediate image correspond to the identified high density image elements of the uncorrected intermediate image.