P001] Screen-film and digital mammography: Two novel phantoms to perform quality controls

Abstract

Introduction Mammography consists in imaging the female breast using X-rays with low contrast, and high resolution. At present, it is possible to distinguish between screen-film and digital mammography. In any case, to guarantee correct diagnoses, it is necessary to establish and actively maintain regular Quality Assurance (QA) procedures that take into account medical, organisational and technical aspects. The QA procedures should include periodic controls referred to as Quality Controls (QC), that permit the identification of image quality degradation, and of possible equipment malfunction. For this reason, periodic QCs have been recommended by manufacturers and medical physicists’ organizations. The European Guidelines for Quality Assurance in mammography screening focuses on the routine tests and tests frequencies required for mammography devices. To perform these procedures different dedicated phantoms are required for each specific QC protocol, that could be also different for screen-film and digital mammography devices. In this context, we propose two novel phantoms that could be used indifferently on screen-film and digital mammography devices, coupled with dedicated procedures. Materials and methods The first phantom consists of polymethylmetacrylate (PMMA) double pyramid water filled characterized by 6 steps. All the steps were 1.0 cm width, 0.4 cm height and 0.1 cm thick. The second one is represented by a round-shaped polycarbonate insert, 3.5 cm in diameter characterized by a series of 0.5 mm x 0.5 mm squared holes. The insert, during measurements, has been placed inside a water bath, to achieve a low contrast condition. Results Using these phantoms different QC parameters (eg uniformity, spatial resolution, contrast to noise ratio, etc.), have been determined. In addition, the F-test demonstrated that there is no statistically significant difference between the results obtained using the proposed phantoms and the commercial ones. Conclusions The new phantoms provide an innovative, accurate, easily applicable determination of parameters that are crucial in QCs. In all cases, results obtained using the proposed new procedures were compatible with other commonly used ones but provided an immediate determination of parameters for both screen-film and digital devices, thus confirming the flexibility of the method, its simplicity and reproducibility as an efficient tool for quick inspections.