2018 Volume 27 Issue 2 Pages 167-172
There have been many reports regarding radiation exposure dose evaluations of digital breast tomosynthesis（DBT）that have assumed standard breast composition, but few reports have taken differences in breast composition into account. In this study we therefore assessed DBT radiation exposure dose ratios in relation to ２D mammography（DBT/２D）by taking differences in breast composition, i.e., breast thickness and mammary gland density, and image acquisition method into account. The results showed that the DBT/２D ratios varied from about１to ５ times according to breast composition and image acquisition method, but the values tended to decrease with increasing breast thickness and breast density, and to increase with increasing size of the oscillation angle. There are problems to be surmounted in the future, including in regard to image quality evaluation, but from the standpoint of radiation exposure, the results suggested the usefulness of DBT for dense breasts.