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 two 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.
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 two 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 very still during treatment. The therapist can see you on a screen. You can talk with them 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, five days per week. In some cases, you may be treated twice daily or only three 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.
Be sure to follow your doctor’s instructions .
You will leave and resume your normal activities. You are not radioactive. You are not a threat to anyone else around you, in terms of radiation exposure.
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, medicine, or rehabilitative treatment.
Tell your doctor if you experience side effects. Many side effects can be controlled with medicine or diet. Your doctor may change or delay the course of your treatment if the side effects are too much. Most side effects will gradually go away after treatment.
After arriving home, contact your doctor if any of the following occur:
In case of an emergency, call for medical help right away.
National Cancer Institute
Oncolink, Abramson Cancer Center, University of Pennsylvania
Canadian Cancer Society
Cancer Care Ontario
Cancer treatment information. Oncolink, University of Pennsylvania Cancer Center website. Available at: http://www.oncolink.upenn.edu/treatment . Accessed June 17, 2008.
Definition of radiation therapy. National Cancer Institute website. Available at: http://www.cancer.gov/Templates/db_alpha.aspx?CdrID=44971 . Accessed June 17, 2008.
Radiation therapy fact sheets. CancerNet, National Cancer Institute website. Available at: http://www.cancer.gov . Accessed June 17, 2008.
Radiation therapy for cancer: questions and answers. National Cancer Institute website. Available at http://www.cancer.gov/cancertopics/factsheet/Therapy/radiation . Accessed September 29, 2009.
Last reviewed September 2012 by Igor Puzanov, 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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