Our clinical practice transitioned from digital mammography (DM) to digital breast tomosynthesis (DBT) screening in 2011. This study analyzes the radiation dose of diagnostic exams after recall from screening in two cohorts, before (I) and after (II) the transition to screening with four Hologic Selenia Dimensions DM/DBT systems. We considered four different imaging modes: DM, magnification DM, and the 2D and 3D components of DBT. Diagnostic exams were classified into four groups based on screening recalled finding: asymmetry, architectural distortion, masses, and calcifications. The study set consisted of 7,409 images from 1,857 women (mean age 55.3±10 yrs.) acquired at two time periods (2010-11, cohort I; 2012-13, cohort II). The average glandular dose (AGD) for the population was computed from the sum of all exposures and analyzed by finding type. The AGD, breast thickness, and exposure settings were obtained using an automated dose-reporting software that stores DICOM metadata in a database for real-time data exploration. The average AGD per patient was 5.82 mGy for cohort I (4.95, 5.40, 6.01 and 8.96 mGy for masses, asymmetry, architectural distortion and calcifications, respectively) and 7.15 mGy for cohort II (6.23, 7.19, 7.61 and 9.03 mGy, respectively). While the AGD for calcifications remained the same after the transition, a dose increase of 23% was found due to the addition of 3D imaging for the other findings. The implementation of DBT in the diagnostic setting results in increased radiation dose to the diagnostic population. However, due to the reduction of recalled patients from screening, we achieved a 15.4% reduction in the utilization of diagnostic imaging. This resulted in a net increase of only 4.0% in the total radiation dose to the screening population arising from diagnostic imaging at recall.