Irradiation measurement in X-ray mammograhy with Dy-CaSO4 thermoluminescent dosimeters

As a result of this work it is possible to measure very accurately the X-irradiation doses entering, leaving and consequently absorbed by the breast. Owing to a method based on the remarkable thermoluminescence properties of dysprosium-doped calcium sulphate a precision of a few millirads is now obtainable, which means that commercial films are worth studying selectively as a function of their responses to doses as low as possible. This fine dosimetry has shown that the doses corresponding to work with standard films still in use recently are considerable, reaching 3000 to 10000 mrads per irradiation according to breast thickness and exposure time. Intensifying screen-backed films, new on the market, need an 'output dose' of only 40 mrads corresponding to an input dose of 300 to 500 mrads, a range in accumulated dose terms very far from the critical level of 90 rads. In future it may be possible to repeat the examination more often than in the past and hence it is essential from now on, every time a mammograph is performed, to be able to call on a means of fine dosimetry in order to avoid all risk of cancer induction. Thermoluminescent dosimeters meet this demand