Radiation doses due to breast imaging in Manitoba: 1978-1988

The number of mammographic examinations performed annually in the province of Manitoba, Canada, and their associated radiation doses (total collective breast dose and average glandular dose [AGD] per view) are reported for the period 1978-1988. These data indicate that the total number of examinations performed annually increased by a factor of five during the 11-year study. The total annual collective breast dose, meanwhile, increased at a much slower rate, from 40 person-Gy in 1978 to 97 person-Gy in 1988; this difference is attributable to the gradual replacement of xeroradiography by screen-film mammography and to changes in technique. In the late 1980s, the AGD due to xeroradiography for a craniocaudal view was 3.3 mGy, a factor of 2.4 greater than the corresponding dose associated with dedicated screen-film units.