Techniques and radiation in mammography

With the increasing use of mammography in the diagnosis and follow-up of breast cancer, the question of radiation hazard has become of considerable interest (Ostrum, Becker and Isard, 1973; Samuel, 1973). There can be no doubt that ionizing radiation, given in sufficient quantity, is carcinogenic. There is evidence in a number of clinical reports (MacKenzie, 1965; Myrden and Hiltz, 1969; Mettler, 1969; Mole, 1973; Wanebo et al., 1968) as well as additional evidence from experimental work (Shellabargar et al., 1957). Whether one or two sets of mammograms are sufficient to induce malignant change in a breast is more doubtful. However, in problem cases of breast disease, and in screening procedure for breast cancer where yearly mammograms are the custom, irradiation of the breast can mount up rapidly, and apparently dangerous levels of radiation can be reached. Such levels can be greatly reduced if the rads per exposure are kept low (Young, 1974). There has been speculation on the probable increased incidence of breast carcinoma in patients who have had repeated mammograms (Ellis, 1972). But, on the available evidence, any calculations on the incidence of radiation-induced carcinoma (Table I) should be viewed with some scepticism. Except in the series reported by Wranebo et al. from the Miyagi Prefecture in Japan, the number of cases is relatively small.