Threshold target thickness calculated using a model observer as a quality control metric for digital mammography

Abstract

Task-based measures estimated by model observers may provide a more clinically relevant and objective way of assessing image quality and system performance for quality control of digital mammography. One approach is to calculate the required threshold thickness (tt) of a material necessary to render test objects just visible, using the detectability index (d') calculated from measured system parameters and a non-prewhitening observer model incorporating an eye-filter and internal noise (NPWE). Our previous work developed methodology for simply measuring the parameters required to calculate d' and tt using a NPWE model. Here we test the sensitivity of t t to changes in image quality by varying entrance exposure and by imaging with and without a grid. Calculated tt values are compared with those reported by automated analysis of CDMAM (™) phantom images (CDCOM). Sensitivity to dose changes was seen, and good correlation was achieved between CDCOM and our model. © 2014 Springer International Publishing.