Public Health

Heart Stress Tests Pump Up Radiation Dose

If you ask around, you'll probably find that most people you know have had an X-ray, CT scan or other test that exposed them to radiation in the last few years.

budget director peter orszag testifies
CarbonNYC/Flickr

Some researchers crunched numbers from insurance claims during a three-year period ending in 2007 and determined more than two-thirds of people had at least one scan involving radiation, and they didn't even count dental X-rays.

That's a lot of scans and, potentially, a lot of radiation, which boosts the risk of cancer over time. Factor in the doses, and about 4 million people between 18 and 64 are exposed to "high" or "very high" levels of radiation each year, the authors of the study published in current New England Journal of Medicine conclude.

The findings don't mean the tests performed weren't worth the risk. But the rise in testing and the lack of evidence that some of the tests make a meaningful difference in medical outcomes for patients heighten concerns. The study authors say it's time to do a better job making sure tests are appropriate and advising patients about the risks.

Take, for instance, the nuclear cardiac stress test, the worst radiation offender in the study—accounting for 22 percent of the dose from all procedures in the study.

The test, technically called myocardial perfusion imaging, gets your heart pumping on a bike or treadmill so you can a shot of radioactive material that later lights up in a scan of the heart to show where blood flow is good. The wrong dark spots could spell trouble and set you up for more scans and procedures.

An accompanying editorial says myocardial perfusion imaging keeps rising, despite a lack of justification "based on disease rates, health care disparities, or newly published, definitive randomized trials."

The commentary author, the National Institute of Health's Michael S. Lauer, has argued the scans detect problems that powerfully "predict future events" for heart patients and can guide therapy to prevent them. "But this logic represents a hypothesis, not a proof," he writes, because well-designed trials just haven't been done.

"The imaging technology today is amazing, it's amazing how quickly it's advanced, yet we haven't answered the fundamental question of whether we're actually helping people by doing this," Lauer said pointedly at an NIH meeting last year, theheart.org reported.

Talk with your doctor about the risks and benefits of a test for you. As radiologist James Thrall of Massachusetts General Hospital told the Associated Press, "There's a risk that people who need a lifesaving or life-improving imaging procedure might not get one" because of radiation worries.

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