CT radiation risks coming into clearer focus

Recent attention to the cancer risks of ionizing radiation has prompted vigorous debate about how to quantify the risks of diagnostic imaging, and whether or how these risks ought to be incorporated into our decision making process as we participate in patient care.

In the past, models of the carcinogenic risks of ionizing radiation have primarily relied on long term surveillance of the Japanese atomic bomb survivors, which showed significant increases in the incidence of cancer after effective doses greater than about 50 mSv.1 2 The relative paucity of direct data in the lower dose range delivered by diagnostic imaging has led to conflicting opinions about the shape and slope of the radiation dose-response curve.

In a linked study (doi:10.1136/bmj.f2360), Mathews and colleagues present compelling data on the magnitude of the cancer risk attributable to ionizing radiation.3 This well designed study examined a cohort of nearly 11 million young patients in the Australian national Medicare system and compared subsequent incidence of cancer in the 680 000 patients exposed to …