Two-thirds of adults get tests with radiation

LOS ANGELES (AP) — As many as two-thirds of adults underwent a medical test in the last few years that exposed them to radiation and in some cases, a potentially higher risk of cancer, a study in five areas of the U.S. suggests.

It is the latest big attempt to measure how much radiation Americans are getting from sometimes unnecessary medical imaging.

Though the annual average radiation exposure from X-rays, CT scans and other tests was low, researchers found about 20 percent were exposed to moderate radiation doses and 2 percent were exposed to high levels. “Super X-rays” to check for heart problems accounted for nearly a quarter of the radiation people received.

“Given the growing use of medical imaging procedures, our findings have important implications for the health of the general population,” the researchers reported in today’s New England Journal of Medicine.

The study did not directly address whether medical imaging is being overused, but some doctors are concerned that advanced tests such as CT scans are being overprescribed, and that evidence of their value in certain situations is lacking. In some cases, tests such MRI scans, which do not involve radiation, could be used instead.

In the last three decades, CT scans have emerged as a popular way to get a 3-D peek inside the body. Some 83 million CT scans were performed in 2007. Doctors use them to get detailed views of the brain, chest, abdomen and pelvis. The radiation risk from a single CT, or computed tomography, to an individual is small, but some doctors are worried about the buildup over time.

Some insurers, citing spiraling costs and safety concerns, are requiring pre-authorizations and setting other limits before patients can receive these scans.

For their study, researchers led by Emory University analyzed insurance claims from 952,420 people between ages 18 and 64 to determine how many had an imaging test and the estimated radiation dose. All were covered by UnitedHealthcare in five regions: Arizona, Dallas, Wisconsin and two areas of Florida.