How Risky are those CT Scans?

New England Journal of Medicine researchers conclude that millions of Americans may be exposed to high doses of radiation from medical imaging. The study says that an estimated "400,000 of those patients receive very high doses, more than the maximum annual exposure allowed for nuclear power plant employees or anyone else who works with radioactive material."

Yet the radiation dose limits for nuclear workers are absurdly low. Our public health committee is looking at articles on radiation doses from imaging studies. We have a lot of information on doses. But there is nothing on actual cancer rates. Radiation doses from medical imaging began increasing in the 1980s, so significant time has elapsed. If there were an increase in cancer that could be blamed on CT scans, I'll bet the lawyers would've found it by now!

Predictions of increased cancer are based on the "linear no threshold" model, invented by Linus Pauling. It works by extrapolating the effects of high dosage/impact back through the zero point at the origin. So if 1 person dies from ingesting 1,000 aspirin tablets at once, we conclude that one out of 1,000 persons will die if each takes one aspirin, and two out of 2,000 people will die if each takes one. This model is supported by no evidence, contradicted by large amounts of evidence, and is absurd on its face.

Comments (7)

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  1. Linda Gorman says:

    For context, 50mSv is the highest annual dose allowed for those with occupational radiation exposure according to Tufts Health Plan. Background annual radiation exposure is 1.5-3 mSv a year. Move to Denver from sea level and you get an extra 0.3 to 0.4 mSv a year. Go to Leadville, CO at 10,000 feet and you get an extra 1.25 mSv a year.

    The average chest x-ray is 0.1 mSv. The Health Physics Society calculates that the risk of dying from cancer with a 1 mSv radiation exposure is about the same as smoking 70 cigarettes or traveling 7,500 miles by car.

  2. Devon Herrick says:

    A researcher, quoted in the New York Times, suggested the radiation from excess imaging “would probably result in tens of thousands of additional cancers.” Yet when the actual risk is explained, it seems trivial.

  3. hoads says:

    Just more agenda driven “research” to use as propaganda for the statists healthcare plan. The proposed implication then is that patients need protection from overwrought physicians ordering too many imaging studies and so let’s regulate imaging. The Baucus Senate Healthcare Bill Outline posted back in early summer included “regional medical imaging regulators” who would review research on imaging, recommend appropriate use and monitor imaging usage. Okay, let’s take them at face value and cede that imaging studies increase the risk of cancer. Do people with symptoms of tumor, stroke, heart disease, joint injuries or over the age of 60 want to be diagnosed by history and exam and forego an imaging study? What’s worse–living with symptoms or risk factors without a verifiable diagnosis or being exposed to radiation?

    And, can’t we have some confidence that the technology will continue to be perfected with better resolutions and lower exposures to radiation? Not if Obamacare rules the day.

  4. Nancy says:

    Thanks, Jane.

  5. Ken says:

    I think you are going to see a lot of articles questioning the value of scanning anad other diagnostic tests as a way of getting the public prepared for the day when obamaCare takes away a lot of these services.

  6. Linda Gorman says:

    Along with nuclear power plant workers people with exposure include miners, people who work with and develop nuclear materials in medicine, people who decommission radioactive sites and tools, people who use it for real time engineering process imaging, people working on nuclear power for spacecraft, and people who work with it in general labs.

    The piece that I used for the occupational exposure numbers is.Pub date is 2007. It is a little strange in that it cites 50 mSv as associated with increased cancer risk and “Highest dose allowed annually with occupational exposure.” Another source clarifies saying that it is the highest dose allowed in any one year. Perhaps the comment would benefit from that clarification.

  7. Ken says:

    Thanks, Linda.