Evaluation of digital breast tomosynthesis systems

In this study, two digital breast tomosynthesis (DBT) systems were evaluated: Siemens Mammomat Inspiration TOMO (Siemens Healthineers, Erlangen, Germany) and GE Senographe Pristina (GE, Buc, France). Along with differences such as angular range and detectors type, the systems use different reconstruction algorithms. One was available for the GE system, based on iterative reconstruction (IR). Two algorithms were available for the Siemens system: TOMO_STANDARD, using filtered back projection (FBP) and EMPIRE, FBP with statistically based artifact reduction. Two commercially available DBT phantoms (CIRS model 020 & 021), with heterogeneous and homogenous background respectively, were used to calculate signal-difference-to-noise-ratio (SDNR) in key structures for varying phantom thickness (30, 45 & 70 mm) and average glandular dose (AGD). Key phantom structures include calcifications and lesion masses of different sizes. Results show a positive correlation between SDNR and AGD except for the EMPIRE algorithm where there was a negative SDNR/AGD trend for one of the microcalcification specks in the heterogeneous phantom. The highest overall SDNR was acquired using the EMPIRE algorithm. Both systems are well within the recommended dose limits but could increase their dose levels in order to achieve higher SDNR. This indicates that there may be room for dose optimization in DBT systems used in screening programs, confirming the importance of continuous evaluation and optimization.