Studies Quantify Cancer Risks From CT Scans

Dec. 15 -- MONDAY, Dec. 14 (HealthDay News) -- Commonly performed CT scans are exposing patients to far more radiation than previously thought and in doses that could cause tens of thousands of cancers a year, two new studies claim.

Based on the findings, reported in the Dec. 14/28 issue of the Archives of Internal Medicine, the study authors, joined by Archives editor Dr. Rita F. Redberg, are calling on clinicians to limit radiation exposure to patients.

"CT has become so quick that we are using it so commonly, and we have lowered our threshold for using it -- meaning we use it for patients who really are unlikely to have any underlying disease," said Dr. Rebecca Smith-Bindman, a professor in residence in the department of radiology at the University of California, San Francisco, and lead author of one of the studies. Although it's a "fabulous diagnostic tool," she said she believes "we have lowered it to the point where there may be no benefit in some patients."

Redberg, who specializes in cardiovascular CT imaging, urged clinicians to carefully assess the benefits of each CT scan and inform patients of the known risks of radiation.

"In light of these data, physicians (and their patients) cannot be complacent about the hazards of radiation or we risk creating a public health time bomb," she wrote.

In the United States, the total number of CT (or computed tomography) scans performed annually has swelled from 3 million in 1980 to nearly 70 million in 2007, according to data cited by Smith-Bindman's team.

CT scans combine computer and X-ray technology to produce detailed, cross-sectional images of the body that can help clinicians diagnose and treat medical conditions.

However, because CT scans typically expose patients to a higher dose of radiation than conventional X-rays, the dramatic rise in the use of this technology has become a reason for concern.

In fact, the new data suggest that its overuse may be doing more harm than good.