[Devolvement of an objective rating system for the annual physical quality control for digital mammography systems].

PURPOSE:For the non-subjective evaluation of physical-technical defects of digital mammography systems within the German breast screening program, an automatic rating system (RS) on the basis of the annual quality control (AQC) was developed. The aim was to design a modular algorithm which could also be adjusted for other test procedures. MATERIALS AND METHODS:This algorithm enables the separate evaluation of different test parts of the AQC (PAS 1054 and EPQC). To take into account the value of different test positions (TP) in these two parts, a weighting scheme was used. This scheme relates to the scope of different TP as well as variability through different types of systems. For the creation of the final result, both scores of the different test parts must be merged together. The final result is divided into 4 categories. EVALUATION:The evaluation of the RS was based on the AQC. Here, the tester of the system was asked to classify the system in one of the 4 categories on the basis of his expert knowledge. In 78 % of the cases, the results of the tester were reproduced by the automatic RS, in 17 % the RS was more stringent and in 5 % the tester was more stringent. CONCLUSION:The RS allows non-subjective physical-technical evaluation of mammography systems. It acts as a good guide for the tester but is not a replacement for experience. In addition, the RS makes the results of different institutions and testers more comparable. The modular algorithm of the RS is able to react to future changes in the different test parts and can be modified for other X-ray modalities.