Effective detective quantum efficiency (eDQE) measured for a digital breast tomosynthesis system

Abstract

This paper presents effective detective quantum efficiency (eDQE) results for a digital breast tomosynthesis (DBT) system. Poly(methyl methacrylate) (PMMA) blocks of thickness 2, 4, 6 and 7 cm were imaged under automatic exposure control (AEC) in standard 2D digital (planar) mammography (with anti-scatter grid) and DBT mode (without anti-scatter grid). Modulation transfer function (MTF) for the projection images was measured in the front-back and left-right (i.e. tube-travel for DBT) directions using a 0.8 mm thick steel edge at positions 2, 4, 6 and 7 cm above the breast table. NNPS data required for eDQE calculation were calculated from the AEC projection images (the ∼0° projection AEC image for DBT). The eDQE at 0.5 mm-1 in planar mammography mode was relatively stable at ∼0.25 as PMMA thickness changed from 2 to 7 cm. For DBT, blurring from the focus motion and scattered radiation reduced eDQE at 6 and 7 cm PMMA. © 2014 Springer International Publishing.