Assessment of tomosynthesis images with the new ACR phantom

Many QC phantoms are available for regular quality control (QC) of clinical full field digital mammography (FFDM) systems. In particular, the ACR (American College of Radiology) mammography phantom has been used for accreditation and routine QC for many years. Recently the FDA approved the use of the new ACR (2017) phantom to accredit DBT systems. While the old ACR phantom has been used to ensure adequate image quality in 2D systems, the extent to which the new phantom can capture deficiencies and artifacts in reconstructed 3D images is not well known. The purpose of this work is to investigate how sensitive the new ACR phantom is to degradations and failures of DBT imaging systems. The phantom was imaged on a custom-built benchtop system where physical degradations in the DBT system can be modeled. The physical factors studied were inaccuracies in reporting focal spot (FS) position and the presence of dead pixels due to detector failure. Readers scored the degraded images according to the new ACR guidelines. In general, while dead pixels were visible in the reconstructed images, the reader scores were only mildly sensitive to the errors in FS positioning.