tomosynthesis
Digital Breast Tomosynthesis (DBT) — the X-ray tube sweeps a limited arc (typically ±7.5° to ±25° depending on vendor) acquiring ~9–25 low-dose projections of the compressed breast, then reconstructs thin (1 mm) "slices" through the breast volume. Reduces overlap-related masking that limits 2D mammography on dense tissue. Paired clinically with C-View synthesized 2D since 2013, eliminating the need for a separate 2D acquisition.
Why it matters to buyers: Clinical standard since the 2010s. First commercial PMA: Hologic Selenia Dimensions (2011); subsequent vendor PMAs followed. DBT improves cancer detection and reduces recall rates versus 2D-only, particularly in dense-breast populations. Tomo licensing is separate from hardware — confirm in writing on any refurb deal. A Selenia Dimensions without active tomo licensing is materially less capable than one with it.
Why it matters to engineers: Tube-head positional accuracy during the arc sweep is the key calibration. Tomo reconstruction artifacts trace to geometry calibration or software / detector issues. Phantom QA on tomo geometry is part of the MQSA physicist survey.