The reduction of radiation and exposure time in mammography

Abstract

The reduction of exposure time in mammography is important to reduce movement blurring, and low radiation dosage becomes significant in repeated examinations. The use of an X-ray tube with a rotating molybdenum anode results in a reduction in exposure time, as the molybdenum produces a larger radiation output, mainly characteristic radiation, than does tungsten at 30 kVp. A single film with a back-mounted high-definition intensifying screen, vacuum packed in a thin polyethylene envelope will allow a further reduction in exposure time and radiation dosage. This causes minimal loss of resolution, but this is compensated for by increased contrast in the film. By these means an exposure of 0·4 seconds at 30 kVp and 200 mA can be achieved using Ilford G film at 70 cm FFD.