Harvard Health Letter

Ask the doctor: Should I worry about x-rays?

Anthony L. Komaroff, M.D.

Q. I always worry about cancer risks when I have -x-rays or airport screenings. Am I overreacting?

A. We use a lot of x-rays in medicine and in other places (like airports). Too much radiation exposure over time definitely can have adverse effects on health. So you're right to be careful, and to ask if you really need a test that involves radiation when your doctor orders one. How can you assess how much radiation you're getting, and how much is too much?

The biological effects of radiation on the body are described by a measurement called a millisievert (mSv). We are all exposed to some amount of natural radiation from the sun, from the earth, and even from some natural chemicals in our bodies. The average natural background radiation in the United States is 3.7 mSv per year.

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