A survey of clinical factors and patient dose in mammography

A survey was conducted to estimate the mean glandular dose (MGD) for women undergoing mammography and to report the distribution of doses, compressed breast thickness, glandular tissue content, and mammographic technique fact ors used. From 24 471 mammograms, of 6006 women, clinical data were collect ed. The survey data included mammograms from seven modern units using a mol ybdenum (Mo) anode and either Mo or rhodium (Rh) filter. Exposure factors f or each mammogram were recorded automatically onto a floppy disk on each un it. All mammography units were calibrated individually using breast tissue equivalent attenuation slabs of varying glandular content, so the breast gl andular content could be estimated on the basis of exposure factors and com pressed breast thickness. The MGD was estimated for each mammogram based on the normalized glandular dose and calculated entrance exposure in air. The survey found a median MGD of 2.6 mGy. The median breast glandular tissue c ontent was 28% and the median compressed breast thickness was 5.1 cm. Also, patient attenuation data were converted to equivalent BR-12 and acrylic th ickness to help determine appropriate phantom thicknesses required for mamm ography unit automatic exposure control performance assessment. (C) 2001 Am erican Association of Physicists in Medicine.