Medical radiation and cancer: minimizing the risk from CT scans
Ionizing radiation is a known carcinogen. Many medical imaging tests employ ionizing radiation to capture detailed pictures of internal organs for diagnosing injury or disease. Radiation-related cancer risk from the scans is small at the individual level, however, small risks could result in a large number of future cancers in the total U.S. population. Because of the increasing use of computed tomographic (CT) scans in the U.S. (in 2007 the average was 70 million scans annually), it is important to discern which type of scans—and the ages at which they are given—contribute most to overall cancer risk.
IRP researchers led by Amy Berrington de Gonzalez, D.Phil., estimated that 29,000 future cancers could be related to CT scans performed in the U.S. in 2007 alone. They found that the largest contribution to cancer risk comes from the scans of the abdomen/pelvis, chest, head, and whole body.
Following the research results, the NIH Clinical Center updated its protocol to require documentation of the ionizing radiation dosage received for each CT scan, and professional groups in the U.S. and overseas have adjusted their guidelines, especially for pediatric use of CT. Between 2011 and 2013, CT procedure volume dropped 11% in the U.S., with about 10 million fewer scans.
Berrington de G, Mahesh M, Kim KP, Bhargavan M, Lewis R, Mettler F, Land C. (2009). Projected cancer risks from computed tomographic scans performed in the United States in 2007. Arch Intern Med. 169(22), 2071-7.
Pearce M, Salotti JA, Little MP, McHugh K, Lee C, Kim KP, Howe NL, Ronckers CM, Rajaraman P, Sir Craft AW, Parker L, Berrington de González A. (2012). Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet. 380(9840), 499-505.