Large Cancer Risk Behind CT Scans

Ever wondered how your body might feel if you survived a nuclear bomb attack? If you are so inclined, just ask a friend you know who decided on his or her own to have a full-body computed tomography (CT) scan, a trend I've heard about for a while through non-stop radio commercials. (This trends is particularly prominent in this country, where Americans make up a growing proportion of the 65 million or so CT scans performed each year.)

But I bet all those commercials never took the time to outline the risks, especially one outlined in a new study: Patients who have CT scans are exposed to a radiation dose equivalent to that received by some survivors of the Hiroshima and Nagasaki atomic bombs! As a result, this exposure has been linked with a significant rise in cancer mortality and younger patients are especially at risk.

During a CT procedure, the body absorbs a radiation dose of about 13 milliSieverts from each scan, researchers said, equalling the dosage absorbed by people living 2.4 kilometres from the center of the World War II atomic blasts in Japan, he says. In fact, some scanners can produce 33 percent more radiation than this.

The chance of dying from cancer due to this kind of exposure is minute (.08 percent) but cumulative. One scientist pointed out, should the average 45-year-old elect to have a CT scan annually for 30 years, he or she increases their risk of dying of cancer to about 2 percent, or comparable to the chance of dying in a car accident.

In a separate study, researchers discovered the risks and rewards of such CT scans were explained to only 7 percent of those who received them. Another huge problem: False positives that usually involve more extensive, costly and stressful tests.

New Scientist August 31, 2004

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