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Understanding radiation exposure

How it all adds up

Once rare, the use of medical imaging with high-dose radiation — CT scans in particular — have soared. Now considered a routine procedure, some estimates show one in 10 Americans undergo a CT scan every year, with many individuals receiving more than one per year.

CT scans can identify everything from cancer to heart disease to internal bleeding.

“They are widely recognized as a valuable medical tool,” says Dr. Tim Gutshall, vice president of medical management and chief medical officer at Wellmark Blue Cross and Blue Shield. “However, CT scans expose patients to radiation doses that are 100 times higher than conventional X-rays.”

Studies show CT scans expose patients to radiation that brings a greater risk of cancer later in life.

“It’s difficult to know how many cancers will result from overexposure to radiation,” says Gutshall. “Some experts say three percent of all cancers in 20–30 years will be a direct result of radiation from CT scans, others say 10 percent. You have to balance the need for a CT scan with the risks of overexposure,” says Dr. Gutshall.

With kids, less is more

Children less than 10 years of age are several times more sensitive to radiation than middle-aged adults. The factors include:

  • An unnecessary amount of radiation may be delivered when CT scanner parameters are not properly adjusted for patient size.
  • Overexposure can easily go unrecognized.

Children have more rapidly developing cells than adults and a longer life expectancy. Their odds of developing cancer later in life due to X-ray radiation are higher than adults.

Radiation exposure dangers

Since radiation has been linked to cancer risk, the U.S. Nuclear Regulatory Commission caps it at 50 millisieverts (mSv) a year for people working with radioactive material. As a point of comparison, airport scanners deliver only 0.00003 to 0.0001 mSv per scan.

Measuring radiation

To give you an idea of radiation exposure, here are the average radiation doses for some of the most commonly performed scans. 

  • Full set of dental X-rays: .0005 MSV
  • Chest X-ray: 0.1 MSV
  • Mammogram: 0.36 MSV
  • Abdominal X-ray: 0.7 MSV
  • CT scan of the head: 2.0 MSV
  • Cardiac calcium scoring: 2.0 MSV
  • Upper GI X-ray: 6.0 MSV
  • Barium enema: 8.0 MSV
  • CT scan of the abdomen/pelvis: 10.0 MSV
  • Virtual colonoscopy: 10.0 MSV
  • Whole-body CT scan: 10.0 MSV
  • Heart angiography: 20.0 MSV

Source: NCRP Report No. 160: Ionizing radiation exposure of the population of the United States

Choosing wisely

“When it comes to radiation, it’s important to be aware of the risks and make informed choices,” says Tom Evans, M.D., president and CEO of the Iowa Healthcare Collaborative.

“You may be concerned you will not have a thorough evaluation without an X-ray or CT scan. However, X-rays are not harmless,” says Evans.

Sometimes, you’re not sure what questions to ask, adds Evans. That’s why the Iowa Healthcare Collaborative is working to improve care through a campaign External Site called Choosing Wisely®.

Choosing Wisely provides lists of specific things physicians and patients should question related to more than 60 medical specialties.

“Choosing Wisely is really about helping patients and providers communicate to ensure the right care is delivered at the right time.”

Tom Evans, M.D., president and CEO of the Iowa Healthcare Collaborative

5 questions to ask

Choosing Wisely recommends five general questions to ask your health care provider before you get any test, treatment or procedure:

  1. Do I really need this test or procedure?
  2. What are the risks? Will there be side effects? What are the chances of getting results that aren’t accurate? Could that lead to more testing or another procedure?
  3. Are there simpler, safer options?
  4. What happens if I don’t do anything?
  5. How much will it cost? Are there less expensive tests, treatments or procedures that your insurance may cover?

Find more information at Consumerhealthchoices.org/Iowa External Site.

Choosing Wisely® is an initiative of the ABIM Foundation.

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