Getting a CT Scan: What are the Risks Posed by Radiation?

Jan. 25, 2010— -- Medical radiation, long used to diagnose and treat patients, has saved countless lives in this country. But some doctors are now warning that more needs to be done to ensure the technology is used more safely.

The radiation from CT scans produces an exquisitely precise image, which is why Americans undergo 72 million scans a year to help diagnose their illnesses, according to a 2009 study from the Archives of Internal Medicine.

But there's a problem.

Dr. Rebecca Smith-Bindman, a professor of radiology at the University of California-San Francisco Medical Center, reviewed the CT images of a thousand patients at four of San Francisco's largest hospitals and found that radiation doses varied wildly. Some patients who underwent the same type of test received 20 times more radiation than others, often in the same hospital.

"The problem," said Smith-Bindman, who is also a visiting research scientist at the National Cancer Institute, "is we don't have a good sense of what's going on [in hospitals]. We don't have the standards that say this is allowable, this is not allowable. This is an area that really lacks close oversight." The net result, she said, "If you go for a CT scan, you have no idea if you're getting a safe dose of radiation or not."

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Radiologists, eager to get the clearest picture possible, can order higher doses of radiation but few hospitals bother to check, critics say.

Then there's the CT machine itself, with its sophisticated software tracking dozens of different measurements. But the most important, the actual radiation level is not clearly displayed.

"In terms of a single number, and 'this is the radiation dose the patient gets,' that's not there," Smith-Bindman said, pointing to a CT screen. "You have to calculate it. There no place on the screen that tells you right now how much radiation the patient is getting."