Automatic volumetric breast density in mammography screening using digital mammography and digital breast tomosynthesis

Mammography screening using conventional digital mammography (DM) has lower sensitivity and specificity in women with dense compared to non-dense breasts, as breast tissue can mask or imitate cancer. Digital breast tomosynthesis (DBT) is gradually replacing DM, enabling reconstruction pseudo 3D images. This can reduce the issue of masking but might come at a cost of increased radiation dose. Radiologists assess breast density using a subjective density scale. Recently, software has become available for objective and automatic assessment of breast density. The first aim of this study was to compare subjective and software-based breast density assessment through a reader study using women sampled from the Oslo Tomosynthesis Screening Trial - OTST. The second aim was to compare the diagnostic performance and radiation dose of DBT vs. DM in subgroups of breast density in OTST. Overall, the results of this thesis show that automatic breast density assessment would ensure objective density assessment, removing the inter-observer variability of current radiologist assessment. Introducing DBT would benefit women with all breast densities at a minor increase of radiation dose