How are people exposed to x-rays and gamma rays?

People may be exposed to this type of radiation from 3 main sources:

  • Natural background radiation comes from cosmic rays from our solar system and radioactive elements normally present in the soil. This is the major contributor to worldwide radiation exposure.
  • Medical radiation is used for x-rays, CT scans, and other tests, as well as for radiation therapy. Radiation therapy is used to treat some types of cancer and involves dosages many thousand times higher than those used in diagnostic x-rays.
  • Non-medical, man-made radiation is used in small amounts in food irradiation, airport security scanners, and some consumer products. Exposure to man-made radiation can happen in certain workplaces, or in communities as a result of above ground nuclear weapons testing and nuclear accidents.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: February 24, 2015 Last Revised: February 24, 2015

American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.