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Find A Radiation Oncologist

External Beam Therapy

Radiation therapy is the use of various types of radiation to safely and effectively treat cancer and other diseases. The radiation beam usually comes from a machine called a linear accelerator, or linac. The radiation beam is painless and treatment itself lasts only a few minutes. In most cases the beam is made of high-energy X-rays, but sometimes specialized approaches may be used.

Before beginning treatment, you will be scheduled for a planning session to map out the area that your radiation oncologist wishes to treat. This procedure is called a simulation. Simulation involves having X-rays and/or a CT scan. Usually, a plastic custom mask is made to keep you in position during treatment.

Often, the whole brain is treated. When the whole brain needs radiation treatments for brain metastases, treatments are usually given daily, Monday through Friday, for two to three weeks.

In some cases, a single high-dose radiation treatment called stereotactic radiosurgery can be used. With stereotactic radiosurgery, doctors only target a small part of the brain with X-rays or less commonly protons, another particle used that is effective and precise. Sometimes combining both stereotactic radiosurgery with whole brain radiation therapy can be helpful.

Tailoring each of the radiation beams allows doctors to target more of the cancer cells while sparing nearby organs, such as the eyes and normal brain.