Nuke

Study Raises Concerns About Patients' Exposure to Radiation in Medical Testing

By Alicia Chang
Associated Press
Thursday, August 27, 2009

LOS ANGELES -- As many as two-thirds of adults underwent a medical test
in the past few years that exposed them to radiation and, in some cases,
a potentially higher risk of cancer, a study in five areas of the United
States suggests.

It is the latest large-scale 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 of adults 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 Thursday'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 as MRI scans,
which do not involve radiation, could be used instead.

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.

Nearly 70 percent had at least one medical test between 2005 and 2007
that exposed them to radiation doses double than what would be expected
from natural sources in the environment such as radon in soil and cosmic
energy from the sun, the researchers said.

The annual average radiation exposure was small -- less than 3
millisieverts, a measure of dose. However, about 20 percent in the study
had moderate exposure (3 to 20 millisieverts) and 2 percent had high
exposure (20 to 50 millisieverts).

Given these findings, the researchers estimated that medical imaging
exposes 4 million non-elderly adults to radiation doses greater than 20
millisieverts a year. The annual safe limit is 50 millisieverts. High
radiation exposure is a known risk factor for cancer.

Far more women had imaging procedures than men -- 79 percent vs. 58
percent. This is a concern because women live longer and face a higher
risk of developing radiation-induced cancer.

James H. Thrall, chief radiologist at Massachusetts General Hospital,
said a major limitation of the study was the lack of information about
why the tests were done. Without it, he said, it's impossible to know
whether the test was medically necessary.

"There's a risk that people who need a lifesaving or life-improving
imaging procedure might not get one" because of radiation worries, said
Thrall, who is also chairman of the American College of Radiology's
board of chancellors.