"There are some serious concerns about the methodology used," but the authors "have brought to attention some real serious potential public health issues," said Dr. Arl Van Moore, head of the American College of Radiology's board of chancellors.
The risk from a single CT, or computed tomography, scan to an individual is small. But "we are very concerned about the built-up public health risk over a long period of time," said Eric J. Hall, who wrote the report with fellow Columbia University medical physicist David J. Brenner.
It was published in today's New England Journal of Medicine and paid for by federal grants.
The average American's total radiation exposure has nearly doubled since 1980, largely because of CT scans. Medical radiation now accounts for more than half of the population's total exposure; it used to be just one-sixth, and the top source was the normal background rate in the environment, from things like radon in soil and cosmic energy from the sun.
A previous study by the same scientists in 2001 led the federal Food and Drug Administration to recommend ways to limit scans and risks in children.
But CT use continued to soar. About 62 million scans were done in the United States last year, up from 3 million in 1980. More than 4 million were in children.
Ultrasound and MRI, or magnetic resonance imaging, scans often are safer options that do not expose people to radiation, Brenner and Hall contend.
