Tests From One Heart Attack Equivalent To 725 X-Rays
Posted on: Tuesday, 17 November 2009, 14:01 CST
Researchers reported on Monday that the long process of tests given to a patient having a heart attack in the U.S. adds up to a dose of radiation equivalent to 725 x-rays. That’s about a third the annual maximum accumulation permitted for workers in nuclear power plants.
The radiation comes from tests such as computed tomography (CT) scans, cardiac catheterizations, and artery-clearing angioplasties.
Too much radiation can increase the risk of developing some cancers, although the benefits of such tests typically outweigh the risks when it comes to diagnosing and treating heart attacks. The cancer risk associated with an angioplasty or with a CT scan -- which delivers about 500 times more radiation than an X-ray -- is hard to measure.
Prashant Kaul, M.D., the lead study author and a cardiovascular fellow at Duke University Medical Center, in Durham, North Carolina, stresses that many cardiac tests that use radiation are necessary and appropriate.
"We're not saying those should be withheld," he says. "We're just trying to increase awareness so that when physicians are ordering tests, they bear in mind the indications."
It's unclear if there's a risk associated with a radiation dose less than 100 millisieverts, which is an amount of radiation about seven times greater than the average dose seen in the study, says Thomas C. Gerber, M.D., Ph.D., a professor of medicine and radiology at the Mayo Clinic's College of Medicine, in Jacksonville, Florida.
Exposure to radiation during occasional tests is safer than a relatively large dose in a short period of time, experts say.
"Having 17 millisieverts in January and another 17 millisieverts in October isn't the same as having 34 millisieverts all at the same time," says Gerber. "Small amounts of radiation in certain increments don't mean the same as one large dose of radiation at the same time."
Patients shouldn't be afraid to ask their doctor if a test is truly necessary, he says. "There's nothing wrong with patients asking their doctor, 'How will this test change what you do for me?' If it doesn't, that test may not be necessary."
Heart attack patients shouldn't forgo a test simply because of concerns about radiation, says Kaul. Doing so could prevent doctors from diagnosing a dangerous problem or treating a patient to the best of their ability.
"We don't want to scare people into thinking they're going into the hospital and their risk of cancer's going to suddenly increase," says Kaul. "It's a balance between the hypothetical risk of cancer with the risks of not performing an imaging study."
The average American can expect to receive about 3 millisieverts a year from ground radon or flying in an airplane.
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Source: RedOrbit Staff & Wire Reports
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User Comments (1)
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Posted by Marie C. on 11/17/2009, 14:33 Thanks for this information. |
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