Towards Optimization of Image Quality as a Function of Breast Thickness in Mammography: An Investigation of the Breast Thickness Compensation Schemes on Analogue and Digital Mammography Units

Abstract

Historically, with film/screen mammography systems image quality as a function of breast thickness was constrained by the necessity to maintain constant dose to the film across all thicknesses. With digital units, no such constraint is placed upon the AEC system and different manufacturers have designed their own breast thickness compensation schemes. In this study, threshold contrast detail detectability measurements were made at three different simulated breast thicknesses using a CDMAM phantom on analogue and digital mammography units. The purpose was to understand how the design of the different AEC systems affected the image quality for thicker breasts in particular, when compared with that for a standard breast thickness on the same unit. The results showed that relative image quality for thicker breasts compared with standard breasts varies greatly with unit type, depending on the thickness compensation scheme implemented by the particular AEC system. The work highlights an urgent need for a more evidence based approach to determining optimal task-based image quality as a function of breast thickness.