Be alert to radiation risk from medical tests, advises the Harvard Heart Letter

With a little help from radiation, doctors can examine the heart and even clear clogged arteries without ever opening the chest. But there can be a price to pay for these advances, reports the April 2009 issue of the Harvard Heart Letter. Exposure to radiation can damage DNA and lead to uncontrolled cell division, the hallmark of cancer. The delicate balance between benefit and risk demands the judicious use of radiation for diagnosing and treating disease.

The amount of radiation delivered by medical tests or procedures varies widely. A chest x-ray delivers a tiny fraction of the amount of natural background radiation we receive each year. By comparison, computed tomography (CT) scans and some nuclear stress tests deliver up to 10 times the annual background dose.

In general, the cancer risk from a single medical test or procedure is low. For every 1,000 people exposed to the amount of radiation delivered by a cardiac CT scan, the radiation would add one extra case of cancer to the 420 cases that would normally occur. Still, it is estimated that radiation from CT scans now accounts for 1.5% of all cancers in the United States.

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