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: External—radiation is delivered by a machine that shoots particles at the cells from outside the body
Internal—radioactive materials are placed in the body near the cancer cells (also called implant radiation or brachytherapy)
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: Control the growth or spread of cancerAttempt to cure cancerReduce pain or other symptoms caused by cancer—palliative radiation
Radiation therapy is commonly used to treat: Solid tumors, such as prostate cancer, breast cancer, and head and neck cancers
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: FatigueSkin changes (redness, irritation)Reduced white blood cell countHair loss
Nausea, vomiting, or
Discuss the specific side effects that you may have with your doctor.
Factors that may increase the risk of complications include: Previous radiation therapy
A personal history of
systemic lupus erythematosus,
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 lie on an exam table. A CT scan will be used to define the exact place(s) where radiation will be directed. The exact area on your skin may be marked with colored ink. You may also have a small tattoo (or several) placed on your skin. This is as a permanent mark to help aim the radiation beam.Depending on the type of treatment required, you may also be measured for devices like braces that will help you stay still during treatment.
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.
External Radiation of a Tumor
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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.
After arriving home, contact your doctor if any of the following occur: Signs of infection, including fever and chillsDiarrhea or loss of appetiteUnexplained weight lossFrequent urination, particularly if it is associated with pain or burning sensationNew or unusual swelling or lumpsNausea and/or vomiting that you cannot control with the medications you were givenPain that does not go awayUnusual changes in skin, including bruises, rashes, discharge, or bleedingCough, shortness of breath, or chest painAny other symptom your nurse or doctor told you to look forAny new or unexpected symptoms
If you think you have an emergency, call for emergency medical services right away.
Radiation. Oncolink, University of Pennsylvania Cancer Center website. Available at:
http://www.oncolink.org/treatment/treatment.cfm?c=5. Accessed February 24, 2015.
Radiation therapy for cancer. National Cancer Institute website. Available at:
http://www.cancer.gov/about-cancer/treatment/types/radiation-therapy/radiation-fact-sheet. Accessed February 24, 2015.
Last reviewed March 2016 by Mohei Abouzied, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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