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Daily, remotely controlled Quality Control (QC) in mammography has been a requirement of our breast cancer screening organization for accepting digital mammography in the screening programme. This set the scene for the development of an automated platform for daily QC supervision in digital mammography more than 15 years ago. While there was general acceptance of the need to supervise the first digital detectors installed in the mid-2000s, later digital systems have been more robust. One could question whether daily QC is of benefit for modern units. In this retrospective study we will illustrate and quantify the types of problems encountered with daily QC during the period January 2015 – January 2020. All issues were categorized as either localized artefacts (‘pixels’), line or line segment artefacts (‘lines’), special pattern or detector blocks visible (‘blocks’), lag and ghosts (‘ghosts’), sudden changes (in exposure) (‘reprod’), inhomogeneities, collimator problems and other. Trend analysis was then performed over the complete period. The number of issues found was 259, distributed over the categories as follows: 138 pixels, 28 lines, 14 blocks, 38 ghosts, 18 reprod, 15 inhomogeneities, 7 collimator problems and 1 other. Trend analysis revealed 44/103 stable systems, 54 systems with sudden changes in exposure (related to new software or new settings) and 7 of these 54 systems had periods with high variability in exposure settings. In 5 systems there was a steady but notable change in parameters over time. Daily QC applied to current units still detects a large number of issues. Remotely controlled daily QC supervision ensures constant quality of the systems on a daily basis and detects problems before they have any large impact on the clinical practice. The effort is considered worthwhile.
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