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External Beam Therapy

What is external beam therapy?

External beam therapy is a commonly used type of therapeutic radiology. Radiation is delivered from a machine directed to the part of the body where cancer is present. The type of machine used will be determined by the radiation oncologist.

How does external beam therapy work?

External beam therapy delivers ionizing radiation to the cancer, destroying cancer cells.

To give healthy cells time to heal, you will get small doses (fractions) of radiation at one time. This helps protect the healthy body tissue around the diseased area.

Most people get radiation treatments on an outpatient basis. A typical schedule is to have therapy once a day for 5 days a week over 2 to 9 weeks. Palliative treatment aims to relieve symptoms rather than for cure. It may last only 2 to 3 weeks. The treatment process usually takes 10 to 30 minutes a day with much of the time spent positioning your body. Treatment duration depends on the method of treatment delivery and the dose of radiation.

The radiation oncologist will monitor your progress and response to each treatment. Depending on the response, changes may be made to the radiation dose, the number of treatments, or the length of treatment.

Research is being done to study the effects of hyperfractionated external beam therapy is underway. This is when smaller doses of radiation are given more than once a day rather than just once a day. The results have been promising for certain types of tumors and cancers.

Although each facility may have specific protocols in place, generally, external beam therapy follows this process:

  1. Generally, you will get external beam therapy 4 or 5 times a week over several weeks.

  2. Depending on the location of the cancer, you may need to remove clothing. If so, you will be given a gown to wear.

  3. You will be carefully positioned so that the area under treatment will get the right amount of radiation. Special molds and other equipment may be used to ensure proper body position.

  4. Shields may be used to protect normal body tissues from the radiation.

  5. Once the positioning and shielding have been completed, the treatment will begin. You will need to stay very still during the treatment so that the radiation beam will reach the cancer with the proper dose.

  6. When external beam therapy starts, the technologist will closely monitor you on a TV in another room.

  7. The treatment will be painless, and will last for only a few minutes.

Online Medical Reviewer: Fetterman, Anne, RN, BSN
Online Medical Reviewer: Grossman, Neil, MD
Date Last Reviewed: 6/14/2015
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