[Physical and technical quality assurance in German breast cancer screening: progress report of the Reference Center...

German breast cancer screening is monitored by a large physical quality assurance program. This report refers to the first experiences of the Reference Center (RC) Muenster after three years of the technical quality control of digital and analog mammography units (MU). This paper also shows whether the presently used quality assurance (QA) method is able to ensure that the MUs in the screening program are functioning without any serious problems.

RC Muenster supervises 95 units (May 2008). The daily, weekly and monthly quality assurance of these units is controlled by web-based QA software named "MammoConrol" and developed by RC Muenster. The annual QA for the units must be conducted in the form of an on-site inspection by medical physics experts of the RC and is scored by an objective ranking system. The results of these QA routines were evaluated and analyzed for this paper.

During the period from 3/1/2006 to 5/31/2008, 8 % of the analog systems and 1 % of the digital systems exhibited problems in the daily QA. For 9 % of the analog MUs and 17 % of the digital MUs, failures appeared in the monthly QA. In the annual control, 86.7 % of the analog units exhibited slight problems and 13.3 % had serious problems. With respect to the digital units, 12 % were without any defects, 58 % had slight problems, 27 % had serious failures and 3 % had to be reported to the responsible authorities and were temporarily shut down.

The special quality control requirements for German breast cancer screening, including annual on-site checks of the units, have shown in the last three years that QA with a high monitoring standard can be ensured for a large number of decentralized MUs. The currently used QA method sufficiently ensures that the screening program is technically safe. Further studies must show whether the density and focus of the QA measures must be reconfigured.