The present invention relates to an apparatus for producing a corrected image of a region of interest from acquired projection data (60), wherein an uncorrected intermediate image (74) is reconstructed. The uncorrected intermediate image (74) is corrected and image elements of the corrected intermediate image (85) are classified. Image elements of the corrected 5 intermediate image (85) that are of a high density or low density class are replaced by image elements having values depending on values of the low density class to generate a synthetic image (90). Synthetic projection data (96) are generated by forward projecting the synthetic image (90), and acquired projection data contributing to the high density class are replaced by corresponding synthetic projection data (96) to generate corrected projection data (112). 10 The corrected projection data (112) are used for reconstructing the corrected image.