Radiation doses received in the UK Breast Screening Programme in 1997 and 1998

The mean glandular doses (MGDs) to samples of women attending for mammographic screening are measured routinely at screening centres in the UK Breast Screening Programme (NHSBSP). This paper reviews the data collected during screening in the NHSBSP in 1997 and 1998 for 23,752 films, using 171 X-ray sets, for 8745 women. Average MGD was 2.03 mGy per oblique film and 1.65 mGy per craniocaudal film, similar to the MGDs found previously in the NHSBSP for the years 1994 and 1995. MGD was found to increase with compressed breast thickness where the tube potential was selected manually, so that the average dose for 10 cm thick breasts was 2.7 times the average for all breasts. For large breasts (> 70 mm) the use of X-ray sets such as the IGE DMR, which automatically select the beam quality for each breast, resulted in lower doses compared with sets using manual tube potential selection. MGD to the standard breast was found to vary from 0.7 to 2.2 mGy and to be correlated with the average MGD per mediolateral oblique film for the women screened on that system (R = 0.79). No correlation between age and MGD was found within the invited age range of 50-64 years.