Radiation therapy is a treatment for cancer and other diseases. It uses high-energy particles to damage the genetic code (DNA) in the cancer cells. This makes the cells unable to grow or divide.
There are 2 main types of radiation therapy:
In certain cases, your doctor may recommend a combination of these. Radiation is often used with other types of treatment, such as surgery, chemotherapy, and immunotherapy (stimulates the immune system to fight infection).
This fact sheet will focus on external radiation therapy.
This procedure may be done to:
Radiation therapy is commonly used to treat:
External radiation does not cause your body to become radioactive. It can cause side effects, as the radiation damages your own healthy cells as well as the cancer cells. Common side effects of radiation include, but are not limited to:
Discuss the specific side effects that you may have with your doctor.
Factors that may increase the risk of complications include:
A woman who is pregnant or could be pregnant should avoid exposure to radiation. It could harm a developing fetus.
You will go through a process called simulation. This takes between 30 minutes and 2 hours.
You will be positioned on the treatment table or chair. The radiation therapist will leave the room and enter a control room. The machine will deliver radiation to certain areas of your body. The most common sources of radiation are x-rays, electron beams, and cobalt-60 gamma rays.
You must be still during treatment. The therapist can see you on a screen. You can talk with the therapist if you feel uncomfortable or sick.
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The treatment takes 1-5 minutes. You should allow at least 30 minutes for each session. Most treatments last 2-8 weeks. They are given once a day, 5 days per week. In some cases, you may be treated twice daily or only 3 times a week. Treatment schedules will depend on different factors. Talk to your radiation oncologist about the schedule planned for you.
There is no hospital stay. External radiation is typically done at an office visit.
During treatment, your doctor will want to see you at least once a week. You may have routine blood tests to check for the effects of radiation on your blood cells.
After treatment is completed, you will have regular visits to monitor healing and to make sure the treatment affected the disease as planned. Follow-up care will vary for each person. Care may include further testing, medications, or rehabilitative treatment.
Call your doctor if any of these occur:
If you think you have an emergency, call for emergency medical services right away.
American Cancer Society
Radiology Info—Radiological Society of North America
Canadian Association of Radiologists
Canadian Cancer Society
External beam therapy (EBT). Radiological Society of North America Radiology Info website. Available at: https://www.radiologyinfo.org/en/info.cfm?pg=ebt. Updated May 8, 2017. Accessed March 29, 2018.
Radiation. Oncolink, University of Pennsylvania Cancer Center website. Available at: https://www.oncolink.org/cancer-treatment/radiation. Accessed March 29, 2018.
Radiation therapy. American Cancer Society website. Available at: https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/radiation.html. Accessed March 29, 2018.
Radiation therapy for cancer. National Cancer Institute website. Available at: https://www.cancer.gov/about-cancer/treatment/types/radiation-therapy/radiation-fact-sheet. Accessed March 29, 2018.
Last reviewed March 2018 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP Last Updated: 3/18/2013