Too Many CT Scans Raise Cancer Risk
Cut down on unnecessary tests, experts advise
 (HealthDay News) -- Sometimes you can have too much of a good thing.
Though medical imaging techniques can often be lifesaving, detecting cancers that would have otherwise gone undiagnosed, the radiation used to uncover hidden disease can sometimes be harmful.
For example, the radiation dose from a CT scan is much higher than that of a standard X-ray. CT scans provide cross-sectional images of the body, rather than just a one-dimensional view, and the amount of radiation needed to produce that kind of imaging detail is 50 to 250 times more than a conventional X-ray.
And though the risk is small, exposure to this type of radiation can cause cancer in some people.
"The radiation doses from CT scans have been clearly demonstrated to increase cancer risk," David J. Brenner, director of the Center for Radiological Research at Columbia University College of Physicians and Surgeons in New York City, said at a news conference.
Brenner's colleague, Dr. Eric Hall, a professor of radiation oncology and radiology, said at the same news conference that a "CT scan of the abdomen in a child gives a risk of about one in 1,000 of an induced cancer."
That's not a big risk for any one individual, Brenner noted, "but a small risk applied to an increasingly large population spells trouble down the road."
CT scans are commonly used for both diagnosing and treating cancer, according to the National Cancer Institute. Generally, the potential risk from CT scans is far outweighed by the benefit they provide to cancer patients.
Of greater concern are CT scans that might be performed unnecessarily, Brenner said. About a third of the CT scans done each year in the United States are medically unnecessary, he said.
"Anyone presenting to an emergency room with a belly ache or chronic headache will automatically get a CT scan," he said. "Is this justified? Well, maybe not."
And part of the problem, Hall said, is that doctors are not always aware of the risks of CT scans. "We were astonished to find how many doctors, particularly emergency room physicians, really have no idea of the magnitude of the doses or the potential risks that are involved in CT scans," Hall said.
Brenner and Hall detailed their concerns in a report published in the New England Journal of Medicine .
Their concern doesn't mean that they believe people should forgo CT scans, however.
"Clearly, in a patient that's symptomatic, a CT is a wonderful diagnostic tool," Hall said. "What we are pushing for is to limit the use of CT to situations where it is really needed."
G. Donald Frey, a radiology professor at the Medical University of South Carolina, told HealthDay that the focus of concern needs to be on CT scans that are done inappropriately. "The whole community should work together to reduce inappropriate scans, but it would be absolutely tragic if a patient who needed a CT failed to get one because of concerns of the radiation dose," he said.
"When CT scans are done on modern equipment, where the dose can be adjusted to individual patient size, and when they are done in facilities that are accredited, the actual doses are being reduced," Frey said.
On the Web
To learn more about medical radiation doses, visit the Health Physics Society.
SOURCES:
HealthDay News ; David J. Brenner, Ph.D., D.Sc., director, Columbia University Center for Radiological Research, and professor of radiation oncology, College of Physicians and Surgeons, Columbia University, New York City; Eric J. Hall, Ph.D., D.Sc., professor of radiation oncology and radiology, Columbia University College of Physicians and Surgeons, New York City; G. Donald Frey, Ph.D., professor of radiology, Medical University of South Carolina, Charleston, S.C.; Nov. 29, 2007, New England Journal of Medicine ; National Cancer Institute (www.cancer.gov)
Author:
Serena Gordon
Publication Date:
Nov. 30, 2008
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