CT Scans: Internal 3-D Images Employed with Caution

Thursday, September 16, 2010

ROCHESTER, Minn. — Computerized tomography (CT) scans are an increasingly popular imaging technology. But their popularity comes with some controversy. The September issue of Mayo Clinic Women's HealthSource looks at why this widely used technology is raising concerns.

A CT scan can quickly produce detailed three-dimensional views inside the body, and are used to detect internal injuries or bleeding as well as locate tumors, infection or blood clots. They can help determine if cancerous tumors are responding to treatment. These scans can identify blockages that might lead to heart attacks. Using CT scans, doctors can perform minimally invasive procedures to repair damaged blood vessels, avoiding riskier open procedures. CT scans have greatly reduced the need for exploratory surgery.

The use of CT scans and other advanced imaging has increased sixfold since the 1980s. That increased use is the crux of the concern because these scans expose patients to more radiation than a traditional X-ray. For example, a traditional chest X-ray, two views, is 0.1 millisieverts (mSv) of radiation while a CT scan of the chest is 7 mSv. In comparison, the average annual exposure from radiation in the natural environment is 1 to 10 mSv.

Studies have suggested that a small percentage of current or future cancers may be caused by radiation exposure of a similar magnitude to a CT scan. So far, no cases of cancer have been directly linked to a CT scan. And there's no clear evidence that the radiation dose used in a typical CT scan increases cancer risk.

Nonetheless, the potential risk of medical radiation is under increasing scrutiny. Guidelines are now in place to prevent unnecessary scans. Imaging experts are looking for ways to reduce the radiation levels when CT scans are performed. The U.S. Food and Drug Administration has launched an initiative to reduce unnecessary exposure to medical radiation.

In most cases, experts say the benefits of a CT scan outweigh any risks. When imaging studies are needed for medical care, patients should always talk with their doctors about benefits and risks.

Mayo Clinic Women's HealthSource is published monthly to help women enjoy healthier, more productive lives. Revenue from subscriptions is used to support medical research at Mayo Clinic. To subscribe, please call 800-876-8633, extension 9751, (toll-free) or visit Mayo Clinic's Online Bookstore.

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