Medical Scans a Significant Source of Radiation

Aug. 27 -- WEDNESDAY, Aug. 26 (HealthDay News) -- Medical imaging tests nearly double the amount of radiation Americans would otherwise be exposed to, new research shows.

CT scans and nuclear imaging contributed to more than three-quarters of the exposure, and more than 80 percent of the procedures were performed on an outpatient, said Dr. Reza Fazel, senior author of a study appearing in the Aug. 27 issue of the New England Journal of Medicine.

"We don't want to scare people and have them refuse procedures. The individual risk in any patient is very small. If it's going to benefit the patient, it's well worth the risk," said Fazel, who is an assistant professor of medicine in the division of cardiology at Emory University School of Medicine in Atlanta.

But one expert called for further research on the subject.

"It's striking that such a large proportion of the non-elderly population is being exposed to at least a moderate amount of radiation," said Dr. Michael S. Lauer, who wrote an accompanying perspective in the same issue of the journal. "This is an opportunity to stimulate us to do the trials we need to do to figure out the value of all these tests."

In the meantime, he added, "physicians need to know about the risks and communicate them, and patients need to talk with their doctor and understand why they're getting the procedure."

Although there are masses of trials demonstrating the benefit of mammographies, the values of other types of tests, most notably cardiovascular ones, are much less clear.

"We're actually working in a knowledge vacuum," said Lauer, who is director of the Divisions of Prevention and Population Sciences and of Cardiovascular Diseases at the U.S. National Heart, Lung, and Blood Institute. "What we know is that the radiation exposure that people are getting now might entail a risk but we don't know the benefit."

Up to 2 percent of all cancers in the United States may be due to CT scans, Lauer added.