Many patients unaware of radiation risks from CT scans

Consumer Reports News: January 03, 2013 01:38 PM

Last time you had a CT scan did your doctor tell you that it would expose you to radiation? Probably not, according to a study out this week. And even if you were told, you might underestimate the radiation dose, too.

Researchers from the University of Washington School of Medicine's radiology department in Seattle surveyed 235 patients who had undergone non-urgent computed tomography (CT) or single photon emission computed tomography (SPECT) cardiac scans from February through December 2011. About a third of the patients said they did not know that the scans exposed them to radiation. And of the 154 patients who did understood that, only 45 percent said that the health care provider who ordered the imaging test had informed them about the radiation exposure.

Almost 90 percent of the patients said they were not worried about scan radiation. But about the same percentage (85 percent) underestimated their exposure, and only 5 percent understood that scan radiation might increase their lifetime risk of cancer. The study was published this week in Archives of Internal Medicine.

As we've reported, CT scans can provide essential diagnostic information. But they pose risks, too. Radiation from CT scans--which are equivalent to between 100 and 500 chest X-rays--might contribute to an estimated 29,000 future cancers a year, a 2009 study suggests. Yet some hospitals, including several large, well-known ones, continue to order too many of them, exposing patients to needless risk and expense, according our updated hospital Ratings.

Bottom line: The survey was small and conducted at a single academic medical center, so the results may not apply to other patient populations. But the findings suggest that some health care providers may do a poor job of informing patients about the radiation dose and the associated health risks of common imaging tests.

"There is no excuse for patients to be uninformed about risks as basic as radiation," says John Santa, M.D., director of the Consumer Reports Health Ratings Center. "It suggests that those providing these tests do not have an appropriate perspective on the risks. Technology can be difficult for patients to understand but it is the physician's job to make sure that each patient is well informed of benefits and risks."

Avoiding unnecessary tests once you're in the hospital is challenging, because you or someone who cares for you must ask difficult questions of the staff. So even before checking into a hospital, consider checking our hospital Ratings. If a doctor orders a CT scan, for example, ask whether an imaging test that doesn't emit radiation, such as an MRI or an ultrasound, could be used instead. And if you're told you need a double CT scan, one with a contrast agent (which can make the image clearer) and another without, ask whether it's really necessary. And see our article How Safe Is Your Hospital and our tips for staying safe in the hospital.


Patient Knowledge and Understanding of Radiation From Diagnostic Imaging [Archives of Internal Medicine]

Doug Podolsky

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