A present invention, in one form, is a method for removing artifacts from image data due to detector degradation. Particularly, data is obtained from a CT system including a detector and an x-ray source. The detector is formed from a plurality of detector cells. In accordance with one form of the invention, a detector degradation signature (S(i)) vector is generated prior to scanning a patient. Subsequent to scanning the patient, if the image data contains a ring error, a detector cell contributing to the error is identified using the detector degradation signature vector. The system then determines if the cell a degraded cell. If such cell is a degraded cell, ring error correction processing is then performed on the image data.