One Year of Experience with Remote Quality Assurance of Digital Mammography Systems in the Flemish Breast Cancer Screening Program

Abstract

The European Guidelines on Digital Mammography (EUREF) prescribe that regularly the homogeneity of the used digital systems should be tested. In a decentralized screening environment with centralized quality control (QC) supervision this can become a time consuming work. Therefore we developed a novel method to simplify remote QC. Exposures of a homogeneous plate of PMMA are made daily under clinical conditions and are sent to our locally installed analysis software. Several parameters are calculated for the complete image, for 6 reference regions of interest (ROIs) and for series of small adjacent ROIs all over the image. These calculated parameters are summarized in maps that are treated as thumbnail images. Analysis results are sent to the reference site where they are supervised by a trained physicist and compared with the results of previous tests. Several artifacts could be traced with the thumbnail images. These include: dirt on phosphor cassettes, scanline artifacts, scratches on the IP and burned-in markers for CR units. For DR units, increasing ghost image factors, lag images, crystallization of detector material, defective pixel artifacts and several electrical artifacts were noticed. Our initial experience indicates that failures with digital mammography devices can be traced remotely via thumbnail images of the above parameters that are electronically sent to our reference center, instead of the full-size image.