Characterization of a direct, full-field flat-panel digital mammography detector

Our work is to investigate the imaging performance of a direct, full-field prototype digital mammography detector as a function of x-ray exposure and detector operational conditions for digital mammography and advanced applications such as tomosynthesis. Theoretical and experimental methods previously developed for the study of small-area prototype detectors have been applied to the investigation of spatial frequency dependent detective quantum efficiency [DQE(f)] of the full-field prototype detector, which has 2816 × 2048 pixels with 85 μm pixel size. The focus of our study is the impact of scaling up the detector design on imaging performance, e.g. electronic noise, readout rate and image artifacts. The results showed that DQE(f) of the full-field detectors is in the same range as that measured from the small-area prototype detector, both of which are superior to existing technologies based on indirect detection. However DQE(f) drops more rapidly than the small-area prototype as exposure decreases, which is to be expected from the higher electronic noise of the full-field detector. Lag and ghosting, both of which can introduce image artifacts, were studied at typical screening mammography image intervals. The effect of lag can be eliminated with frequent update of the offset images. Ghosting at x-ray dose equivalent to a single view mammogram is negligible.