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New CT scan studies provide more evidence of the dangers of unnecessary diagnostic tests

The overuse of computed tomography (CT) scans is subjecting people to high levels of radiation that may eventually cause thousands of extra cancer deaths, according to a new study released Monday.

Specifically, the study, published in the current issue of the Archives of Internal Medicine, found that 15,000 people may die from cancer over the next two decades as a direct result of the CT scans they received in 2007 alone.

That year, some 72 million CT scans (more than 19,500 a day) were done in the United States, up from 3 million in 1980 and 21 million in 1995.  

Each person who undergoes CT scanning is subjected to the equivalent of 30 to 442 chest X-rays per scan.

Although CT scans can be life-saving, they are often used for unproven health strategies, such as screening for coronary artery calcification to determine if someone is at risk for heart disease.

The younger the patient, the greater the risk from CT scans, the study found. And the risk is higher for women than for men. About 1 in 270 women and 1 in 600 men who have a CT scan at age 40 will develop cancer as a result, the study projects.That risk approximately doubles for 20-year-olds — and drops by about half for 60-year-olds.

Radiation doses vary widely
A second study published in the same journal found that the radiation doses of the same CT scan performed at different medical institutions — or even on different equipment within the same institution — vary by as much as 13-fold.

Even the median doses were found to be four times higher than they’re supposed to be, notes Rita Redberg, M.D., a California cardiologist and current editor of the Archives of Internal Medicine, in an editorial that accompanied the two studies.

That’s troubling, to say the least, particularly given the almost cavalier attitude toward CT scans in some institutions.

“Although there are clear instances when CT scans help determine the treatment course for patients,” writes Redberg, “more and more often patients go directly from the emergency department to the CT scanner even before they are seen by a physician or brought to their hospital room.”

‘Tragic waste of money’
In a second editorial — one that specifically address the questionable use of CT scans for coronary artery calcification (CAC) screening — Patrick O’Malley, M.D., of the Uniformed Services University of Health Sciences in Bethesda, Md., is even more condemning of physician overuse of the technology. There is no evidence that CAC screening results in improved outcomes, he points out, which makes the use of CT scans for this purpose, at best, “a very expensive endeavor,” but, more likely “a tragic waste of money.”

The motives behind the popularity of CAC screening is far from pure. Writes O’Malley:

There are members of our own profession who are not only endorsing this practice but also profiting from it. In short, screening coronary CT as currently implemented, is a costly practice with unclear benefit and theoretical potential net harm. Hence, my double take whenever I see patients who present to discuss what their follow-up CAC score means or, worse yet, when I see the written recommendation from the interpreting radiologist or cardiologist to get their follow-up scan in another 1 to 5 years! …
Since it seems that the medical community is unwilling to self-regulate in this probably enormously wasteful endeavor, it will require policy makers to be more forceful in reining in the madness, whether it be the Food and Drug Administration or financiers of health care.

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Comments (2)

  1. Submitted by Pat Thompson on 12/15/2009 - 07:22 pm.

    *15,000 people may die from cancer over the next two decades as a direct result of the CT scans they received in 2007 alone.*

    Yet people are outraged that the U.S. Preventive Services Task Force recommended against mammograms for women in their 40s, which prevents one death for every 1,904 women screened for 10 years.

    Sometimes I think we’re still in that naive period when people got their feet x-rayed at the shoe store to see if their feet had grown…

  2. Submitted by Mike Wyatt on 12/22/2009 - 09:53 am.

    It’s hard to tell who is wagging the dog’s tail right now. All these “studies” coming out during the health care debate. Am I being conditioned to expect fewer medical services?

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