Radiation Safety FAQ

Common Questions about Radiation

Does radiation cause cancer?

Only high radiation doses are known to increase the likelihood of getting cancer, but not by much. For instance, follow-up studies of 82,000 exposed Japanese A-bomb survivors have produced an estimated 250 radiation-induced cancers. Low doses have not been proven to cause cancer, but for safety concerns, we still try to keep radiation exposure to a minimum.

Is it true that little is known about the effects of radiation, other than that it is very dangerous?

This is untrue. We probably know more about radiation than any other agent that causes cancer (carcinogen) or mutations (mutagen), physical or chemical. Experience goes back about 80 years and the information is probably better documented than that for any other carcinogen. Radiation is, in fact, a relatively weak carcinogen and mutagen.

Can radiation exposure from a diagnostic radiologic procedure be more dangerous than the associated illness?

This is almost always untrue. For a patient undergoing a diagnostic radiologic procedure, the benefits of the procedure are much greater than the risks.

After being X-rayed for a diagnostic examination, how much radiation stays in my body?

No X-rays remain in your body. The X-rays are gone as soon as the X-ray machine shuts off, just as the light from a light bulb vanishes when someone switches it off.

X-rays must not be confused with radioactivity, where the radiation slowly decreases with time. If a patient undergoes a procedure in nuclear medicine, some radiation will remain in his or her body. It will disappear after one or two days.

I have had several X-ray exams over the past couple of years. Will this sterilize me?

No. The radiation dose required to sterilize (500-600 rems) is at least a factor of 100 larger than the gonadal radiation exposure from even several X-ray exams, even if the exams are directly of the gonadal area. If the X-ray exams are directed at other regions, the radiation exposure to the gonads is even less.

What is background radiation?

Background radiation is radiation from natural sources and is present at very low levels all the time. Its intensity varies from place to place -part of it comes from the sun and outer space, and part of it comes from tiny amounts of radioactive materials which are always present in the earth, buildings around us and even in our bodies. Manmade sources, such as radioactivity in consumer products, radioactive fall-out from past nuclear explosions and nuclear power add a small amount to our background. Two to three days of background radiation are equivalent to one chest X-ray.

Are there additional resources that talk about radiation safety?

Yes. You can visit “Ask the Experts” maintained by the Health Physics Society and Radiation Answers, both of which are reliable sources.

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