A survey of radiation doses to patients in mammography

The results are given of a survey of skin doses received in mammography by a phantom breast containing a simulated spherical tumour. The survey covered the 18 centres in New Zealand where mammography was carried out in 1976. The techniques used included xeroradiography, non-screen film and film with a back screen. If the best parameters for each technique were chosen, the "tumour" could be readily seen. Unfortunately this was not often the case and in practice only xeroradiography produced mammograms where the tumour was clearly seen in both the cranio-caudal and medio-lateral views. No centre produced a mammogram of the highest quality with an entrance dose of less than 1 rad. Within each technique there was a very wide range of entrance doses for the same quality of mammogram. At two centres with large workloads, the entrance doses to 11 patients were measured and, in general, the skin doses received by the patients were within 25% of those measured with the Rando phantom.