Report Raises Questions About Safety of CT Scans In a report in this week's New England Journal of Medicine, researchers say that doctors are over-proscribing CT scans, which deliver radiation doses 50 to 200 times higher than most X-rays. Other experts counter that the concern is exaggerated, and worry that patients will be scared away from having necessary scans.

Report Raises Questions About Safety of CT Scans

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And now, a dustup among doctors. It was kicked off by a report in this week's New England Journal of Medicine about the hazards of CT scans. Columbia University researchers now warned that today's CT scans will cause some of tomorrow's cancers.

But cancer experts and radiologists are taking issue with that warning as NPR's Richard Knox reports.

RICHARD KNOX: The American Cancer Society's chief medical officer Dr. Otis Brawley is among those who were skeptical about the new report.

Dr. OTIS BRAWLEY (Chief Medical Officer, American Cancer Society): There's one statement that they make that I find hard to believe; that eventually, 2 percent of all cancers are caused by diagnostic radiation. I can't speak factually about this, but my gut feeling is that that is an overestimation.

KNOX: But Brawley actually agrees with the main point of the New England Journal paper - a lot of people are getting unnecessary CT scans.

Dr. BRAWLEY: CT scanning is a mixed blessing. It's clearly saved numerous lives, has clearly eliminated a lot of suffering, decreased their need for exploratory surgery, but it's also been overused. Perhaps 20 to 50 percent of the CT scanning done in the United States really doesn't need to be done.

KNOX: David Brenner of Columbia University says he and his colleague, Eric Hall, wrote the paper because doctors order a growing number of these scans every year to diagnose everything from appendicitis to brain tumors.

Dr. DAVID BRENNER (Professor, Radiation Oncology and Public Health, Center for Radiological Research, Columbia University Medical Center): The real issue is that CT scans are increasing in frequency dramatically now. We're now at the stage when about 60 million CT scans are being done every year in this country. And we have a population of 300 million, so that means, on average, you have a one in five chance of having a CT scan every year.

KNOX: And the number of CT scans is likely to grow even faster, as CTs get used for new screening tests for colon cancer, lung cancer and heart disease. Brenner says even many doctors don't realize how much radiation a CT scan delivers.

Dr. BRENNER: Because it takes many, many X-ray images and combines them to produce this pretty three-dimensional picture, the radiation dose that is given in a CT scan is far greater than in a conventional X-ray exam - much, much larger.

KNOX: Fifty to 200 times larger. Brenner says CT scans expose patients to about the same X-ray dose as survivors of the atomic bombs at Hiroshima and Nagasaki got a couple of miles from the epicenter. Decades later, cancer among those survivors was 2 percent higher than among similar people who weren't exposed; that's the basis for the new paper's most controversial assertion.

Dr. BRENNER: Thirty years from now, maybe one and a half - 2 percent of all the cancers in this country will be related to the CT scans that we're doing now.

KNOX: That suggests tens of thousands of Americans will eventually get cancers caused by CT scans they're getting today. Some are crying foul about that such as Dr. Arl Van Moore, chairman of the American College of Radiology.

Dr. ARL VAN MOORE (Chairman, American College of Radiology): The study obviously admit that there are currently no published studies directly linking CT scans or even multiple CT scans to cancer.

KNOX: But there's a lot of agreement that CT scans should be avoided when possible for children.

Dr. BRENNER: Children are far more sensitive than adults to radiation - 10 times more sensitive. Children have a lot more dividing cells because they're growing, and cancer is a disease of cell division going wrong.

KNOX: Even Van Moore of the College of Radiology agrees that patients and parents of patients should ask doctors before getting a CT scan.

Dr. MOORE: Why do I need this exam? How will this exam improve my health care or benefit me? Are there any alternatives that don't use radiation which are equally good?

KNOX: Meanwhile, Brenner says the makers of CT scanners are getting the message. They're working on ways to minimize the radiation dose of each CT scan.

Richard Knox, NPR News.

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