The aim of this paper was to investigate the diagnostic potential of tomosynthesis imaging compared with the performance of 2-D digital mammography in terms of radiation dose and image quality. In particular, suitable dosimeter and phantom were used for quantifying the average glandular dose and image quality parameters, respectively. First, according to standard protocols and European guidelines, the characterization of the used tomosynthesis system was carried out to verify the reliability of characteristic parameters of the system. Successively, the absorbed dose was calculated by means of experimental measurements and the application of estimation methods. The calculated dose was then compared with the value provided by the system; this approach has confirmed the tendency of mammography equipment manufacturers to underestimate the mean glandular dose. Finally, the detection capability of different details with different contrasts was objectively assessed for both breast tomosynthesis and 2-D mammography.