Radiation Therapy
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Radiation Therapy

(Ionizing Radiation; Radiotherapy; Brachytherapy)

En Español (Spanish Version)


Radiation therapy is the treatment of cancer and other diseases with penetrating beams of high-energy waves or streams of particles. It is delivered by machines or radioactive substances.

Radiation therapy works by damaging cancer cells that divide and grow more quickly than normal cells. Once damaged, the cancer cells cannot grow. Although some normal cells may be damaged too, they are able to repair themselves and function properly.

There are two main types of radiation therapy:

  • External—radiation is delivered by a machine 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, some doctors may recommend a combination of internal and external radiation. Radiation is often used with other types of treatment, such as surgery, chemotherapy , and immunotherapy (the stimulation of the immune system to fight infection).

External Radiation of a Tumor

Radiation of Tumor

© 2008 Nucleus Medical Art, Inc.

Parts of the Body Involved

Depends on the type of cancer treated

Reasons for Procedure

  • Control the growth or spread of cancer
  • Cure disease by completely eliminating growth
  • Alleviate or reduce the symptoms of pain, bleeding, or other local symptoms caused by the cancer (This is called palliative radiation.)

Radiation therapy is commonly used to treat:

Risk Factors for Complications During the Procedure

A woman who is pregnant or could possibly be pregnant should avoid exposure to radiation. This will prevent harm to her developing fetus.

What to Expect

Prior to Procedure

External Radiation

You will go through a process called simulation. This takes between 30 minutes and two hours. During simulation, you will:

  • Lie on an exam table. A radiation therapist uses an x-ray machine to define the exact place(s) where radiation will be directed. The therapist may mark the exact radiation area 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 undergo:
    • CT scan —a type of x-ray that uses a computer to make pictures of the inside of the body
    • Measurement with immobilization devices to help you stay still during treatment

Internal Radiation

You will be given general or local anesthesia. You will not feel pain when the doctor places the holder for the radioactive material in your body.

Tell your doctor if you experience these side effects . Many side effects can be controlled with medication or diet. Your doctor may change or delay the course of your treatment if the side effects are dramatic. Most side effects will gradually go away after treatment.

During Procedure

External Radiation

You will remove any jewelry. You might change into a hospital gown.

Internal Radiation

In many hospitals, the radioactive material is placed in its holder or applicator after you return to your room. This is done so other patients, staff, and visitors are not exposed to radiation.

Implants may be removed after a short time or left in place permanently. If they are left in place, the radioactive substance used will lose radiation quickly and become non-radioactive in a short time.


External Radiation


Internal Radiation

Local or general anesthesia

Description of the Procedure

External Radiation

The radiation therapist positions you on the treatment table or chair. Then the therapist leaves the room and enters a control room. In the room he controls the movements of the radiation machine (called a linear accelerator). The machine delivers radiation to the predetermined areas on your body. The most common sources of radiation are x-rays, electron beams, and cobalt-60 gamma rays.

You will need to be very still during treatment. The therapist can see you on a television screen. You can talk with the therapist if you feel uncomfortable or sick.

Internal Radiation

The doctor places the radiation source inside your body on or near the affected area. This provides higher doses of radiation in a shorter time than external radiation. The radioactive sources (such as cesium, iridium, palladium, or iodine) are in the form of wires, seeds, or rods. This treatment is mostly used for cancers of the head and neck, breast, uterus, thyroid , cervix, and prostate. The two main types of internal radiation are:

  • Interstitial radiation—Rods, ribbons, or wires placed inside the affected tissue on a temporary or permanent basis
  • Intracavitary radiation—A container of radioactive material placed inside a body cavity, such as the uterus, vagina, or windpipe (This is always temporary.)

Rods for Internal Radiation

brachtherapy seeds

© 2008 Nucleus Medical Art, Inc.

After Procedure

External Radiation

You will leave and resume your normal activities. You are not radioactive and you are not a threat to anyone else around you, in terms of radiation exposure.

Internal Radiation

You will return to a hospital room while the implant is in place. While the radiation is implanted, you will follow these precautions to prevent transmitting radiation to others:

  • Limited visitation
    • Many hospitals do not allow children under 18 years old or pregnant women to visit a patient undergoing implant radiation. They may visit once the implant is removed. If visitors are allowed, they will need to sit at least six feet from the bed. Their visits will be limited to a short time (10-30 minutes). Staff may place a shield beside the bed to protect visitors and staff from radiation exposure.
  • Limited contact with the staff
    • Although the staff will be available to you at all times, be aware that they may speak to you from the doorway. They may also come and go very quickly to avoid excessive radiation exposure.

How Long Will It Take?

External Radiation

The treatment takes 1-5 minutes. But 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 schedule will depend on different factors. Talk to your radiation oncologist about the schedule planned for you.

Internal Radiation

This depends on the type of cancer treated and the method of internal radiation used.

Will It Hurt?

External Radiation


Internal Radiation

Anesthesia prevents pain during the procedure.

Possible Complications

External radiation does not cause your body to become radioactive.

However, external and internal can both cause side effects. These will vary depending on the type and location of treatment. Common side effects of radiation include, but are not limited, to:


  • Fatigue
  • Skin changes (redness, irritation)
  • Reduced white blood cell count
  • Hair loss


  • Dryness or itchiness of the breasts
  • Breast or nipple soreness
  • Fluid build-up
  • Tanning in irradiated area

Pelvic Region

Mouth, Stomach, or Intestine

  • Appetite loss
  • Nausea, vomiting, or diarrhea
  • Mouth ulcers
  • Difficulty swallowing

Average Hospital Stay

External Radiation

None. External radiation is typically done on an outpatient basis.

Internal Radiation

You will stay in the hospital until the implant is removed, or in the case of a permanent implant, when the radioactivity has decreased. Doctors usually remove high-dosage implants within a matter of minutes. Low-dosage implants may remain in for a few days. Permanent implants lose their radioactivity within a few days.

Postoperative Care

External Radiation and Internal Radiation

During treatment, your doctor will want to see you at least once a week. You may have routine blood tests to check the effect of radiation on your blood cells. After treatment is completed, you will have regular visits to monitor healing, and check for signs of recurrent disease. Follow-up care will vary for each person. Care may include further testing, medication, or rehabilitative treatment.


Ideally, radiation therapy will shrink or eliminate the cancerous or diseased area.

Call Your Doctor If Any of the Following Occurs

After you leave the hospital, call your doctor if any of the following occurs:

  • Signs of infection, including fever and chills
  • Cough , shortness of breath, or chest pain
  • Pain that doesn't go away, especially if it's always in the same place
  • New or unusual lumps, bumps, or swelling
  • Nausea, vomiting, diarrhea , or loss of appetite
  • Unexplained weight loss
  • Unusual rashes, bruises, or bleeding
  • Any symptoms that you are concerned about
  • Any other warning signs mentioned by your doctor or nurse


National Cancer Institute

Oncolink, Abramson Cancer Center, University of Pennsylvania


Canadian Cancer Society

Cancer Care Ontario


Definition of radiation therapy. National Cancer Institute website. Available at: http://www.cancer.gov/Templates/db_alpha.aspx?CdrID=44971 . Accessed June 17, 2008.

Cancer treatment information. Oncolink, University of Pennsylvania Cancer Center website. Available at: http://www.oncolink.upenn.edu/treatment/ . Accessed June 17, 2008.

Radiation therapy fact sheets. CancerNet, National Cancer Institute website. Available at: http://cancernet.nci.nih.gov/cancertopics/wtk/index . Accessed June 17, 2008.

Last reviewed March 2008 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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