Evaluation of a software package for automated quality assessment of contrast detail images--comparison with subjective visual assessment.

Contrast detail analysis is commonly used to assess image quality (IQ) associated with diagnostic imaging systems. Applications include routine assessment of equipment performance and optimization studies. Most frequently, the evaluation of contrast detail images involves human observers visually detecting the threshold contrast detail combinations in the image. However, the subjective nature of human perception and the variations in the decision threshold pose limits to the minimum image quality variations detectable with reliability. Objective methods of assessment of image quality such as automated scoring have the potential to overcome the above limitations. A software package (CDRAD analyser) developed for automated scoring of images produced with the CDRAD test object was evaluated. Its performance to assess absolute and relative IQ was compared with that of an average observer. Results show that the software does not mimic the absolute performance of the average observer. The software proved more sensitive and was able to detect smaller low-contrast variations. The observer's performance was superior to the software's in the detection of smaller details. Both scoring methods showed frequent agreement in the detection of image quality variations resulting from changes in kVp and KERMA(detector), which indicates the potential to use the software CDRAD analyser for assessment of relative IQ.