Use of medical radiographs: extent of variation and associated active bone marrow doses

An analysis of radiologic practice in five areas of Maine was undertaken for three purposes: to identify those radiologic examinations associated with the highest variation in use so that guidelines can be instituted to correct for excess use; to identify the major contributors to absorbed dose to the active bone marrow; and to estimate annual and cumulative dose to the active bone marrow as a function of age. Our data indicate that variation in radiologic use is no larger, on average, than is variation in the use of surgical procedures and that the largest variations are found in mammograms and films of the skull and lumbar spine. For all patient age groups, four types of examinations contribute 75%-85% of the annual dose to the active bone marrow: examinations of the stomach and intestines using barium contrast material, intravenous urograms, studies of the biliary tract, and lumbar spine films. Over 80% of the total dose to the active bone marrow from diagnostic radiology in patients occurs after age 40 and nearly 60% after age 55; this suggests that the potential number of induced leukemias from diagnostic radiology may be lower than previously estimated.