NCPA - National Center for Policy Analysis


September 9, 2004

Each year, thousands of people with no symptoms of disease undergo whole-body computed tomography scans -- called CT or CAT scans -- often without the knowledge of their primary doctor. The aim is to check the body for any cancerous tumors or cardiovascular conditions even before symptoms arise, in order to start treatment as early as possible.

In a finding that may further fuel the debate over the wisdom of elective whole-body CT scans, researchers from Columbia University say the radiation from these increasingly popular screenings could increase a person's risk of death from cancer.

The study suggests the radiation dose from a full-body scan can be almost as high as the dose received by some survivors of the 1945 atomic bombings of Hiroshima and Nagasaki. By examining mortality data from 100,000 survivors of the atomic bombings, researchers projected the probability of death from cancer that could be expected in people exposed to similar levels of radiation in whole-body scans.

  • Survivors of the 1945 bombings received doses ranging from 5 to 50 millisieverts (MsVs), with a mean dosage of 20, according to the study.
  • Researchers said the effective dose for one full-body CT scan, which uses rotating X-rays to create images, would be 12 MsVs; that's equivalent to an estimated 600 conventional chest X-rays, or about 100 mammograms.
  • Americans already get about 3.6 millisieverts a year from natural resources but last year, some 57 million CT scans were performed in the United States, including thousands of whole-body scans, according to the American College of Radiology.

Critics says the new study has its limits, for in comparing Japanese bomb survivors with the general U.S. population, researchers are assessing two geographically and ethnically different populations, with different genetic make-ups.

Source: Christopher Windham "Study Cites Risks of Full-Body Scans," Wall Street Journal, August 31, 2004; and David J. Brenner and Carl D. Elliston, "Estimated Radiation Risks Potentially Associated with Full-Body CT Screening," Annual Report 2003, Center for Radiological Research, Columbia University.

For WSJ text (Subscription required),,SB109390922407505224,00.html


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