A Norwegian Survey of Image Quality, Doses and Film Processing in Mammography, with Reference to Two Technical Phantoms

The performance of 45 mammography units in Norway has been compared by means of two commercial phantoms, a Nordic phantom and another used as part of the American College of Radiology accreditation system (ACR). Three images of both phantoms were obtained from each unit, and corresponding dose measurements and sensitometric tests were performed. The results were evaluated according to Nordic recommendations and the phantom image quality criteria set by ACR. Large variations were found, although glandular doses were all kept below 2 mGy. The contrast and sensitivity of the film were shown to influence the image contrast and the dose considerably. Image quality criteria based on image quality parameters that can be assessed with technical phantoms are discussed. These should be separately linked to grid and non-grid techniques, and might be used as references for future quality control programmes based onthese phantoms.