Are x-rays completely safe?

October 5, 2007  |  General

Doctors do a lot of x-rays on children. Is there a risk to that, or are x-rays completely safe? The answer, for chest, bone, and abdominal x-rays, is that they are very, very, very safe, but not totally risk-free. All of us are constantly exposed to radiation similar to x-rays. It comes primarily from naturally-occurring radioactive things around us, such as radon gas seeping up through the ground, or from outer space in the form of cosmic rays. People living at higher altitudes receive higher doses of such background radiation, amounting to about half again as much for someone living on the Colorado plateau compared with someone at sea level. To put things in perspective, the radiation dose in a single chest x-ray, on average, is similar to the background radiation most of us receive during a ten day time span living our normal lives.

There are several important things to remember about radiation risks. High radiation doses definitely cause death and disease (primarily cancer); the atomic bomb and the disaster at Chernobyl clearly showed this. A second key point is that radiation risk is cumulative over a lifetime. This is an important consideration for children, since they have most of their life ahead of them. Children are also more sensitive to the effects of x-rays than are adults. Still, it is logical to think of routine chest, arm and leg, and abdominal x-rays as being virtually without risk unless the child has already gotten for some reason a large radiation dose in the past.

Computed tomographic scans, CT scans, are another form of x-rays. We most commonly use CT scans to look at a child’s head, chest, or abdomen. The technology produces good images of the organs inside those body regions, and CT scanning has revolutionized how medicine and surgery are practiced. But CT must be used judiciously, particularly in children, because it subjects the child to much more radiation than does a simple chest or abdomen x-ray–200 to 300 times more, depending upon the particular technique used. So if a chest x-ray is the equivalent of ten days of background radiation exposure, a child getting a CT scan receives the same radiation dose as anywhere from five to ten years of normal living. I’ve written more about CT scan risk here.

The future cancer risk to a child from a single CT scan is still vanishingly small, and the benefits of getting the information the CT provides nearly always outweigh this tiny risk. However, this may not be the case for children who get many CT scans or have been exposed to other radiation in the past. Fortunately, this represents a relatively small number of children. There are ways of using reduced radiation doses in children, compared to the doses adults receive for CT. If you are concerned about this issue, ask your child’s doctor about it, or you can read more about it here.

I’ve also posted here about what medical risk means.

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104 Comments


  1. Dr. Johnson,

    Thank you so much for your response. I agree that patients should always ask the why and the risk/benefit questions — that is why I am now, 3 years after my daughter’s x-ray — finding myself unable to sleep and wracked with fear and guilt. We did not ask those questions. The one-year x-ray seemed to be a standard protocol and unfortunately we put ourselves in the position of “doctor knows best” instead of asking and proceeding with the level of information and comfort that would have been best. It’s too bad not all doctors are as open and encouraging of these conversations as you are! But I take the ultimate responsibility which is weighing heavy on my heart.

    I was wondering if a chest/abdomen x-ray is equivalent to maybe 10 days of background radiation, could you put the dose of a hip x-ray in similar terms? I may be doing nothing but making myself feel worse, but maybe some other parent will happen upon this and make a more informed choice than we did.

  2. The data I found were for adult hip x-rays, which put the radiation exposure at about 8 times that of a chest x-ray, or about 80 days of normal life’s background radiation at sea level.

    Here’s a good link with lots of information about background radiation.

    http://www.physics.isu.edu/radinf/risk.htm

    I know it’s difficult not to worry, but really the risk of driving your child in your car to the x-ray machine is much higher than is the risk of the x-ray itself. Yet we take the drive without worrying about it.

  3. Hi Christopher, my son had a few head xrays at 5 months old because he had a ridged suture and his anterior fontanel was hard to feel. They were normal and now I have horrible guilt. I wish I would have refused the xrays. He is at increased risk for cancer due to a few head head xrays to look at the skull bones? thanks.

  4. Julie:

    Those skull x-rays do not significantly increase his risk for future cancer. And, as usual in situations like this, you need to ask yourself about the risk of not doing the study, of not getting the information — that’s important, too. For any test, ask the doctor if the risk of the test is outweighed by the benefits of getting the information the test will yield.

    But don’t worry about those few films.

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  1. CT scans and cancer: thinking about the meaning of risk | Christopher Johnson M.D. PICU Author
  2. Reducing radiation exposure in x-rays for children: the Image Gently program | Christopher Johnson M.D. PICU Author