Radiation therapy (also called radiotherapy) is the use of high-energy rays to destroy tumor cells and stop them from growing and multiplying.

Radiation therapy is a local therapy. This means that it affects only the cells targeted. It does not harm cells elsewhere in the body or even elsewhere in the brain or spinal cord.

The therapy is administered in one of two ways:

• External radiation uses a high-energy beam of radiation targeted at the tumor. The beam travels through the skin, the skull, healthy brain tissue and other tissues to get at the tumor. The treatments are usually given five days a week for four or six weeks. Each treatment takes only a few minutes.
  
  Another type of external radiation treatment is known as stereotactic radiosurgery. Gamma knife treatment is one kind of radiosurgery. This procedure is most often used to destroy brain tumors as an alternative to open surgery and is performed in a single session.
• Internal or implant radiation uses a tiny radioactive capsule that is placed inside the tumor itself. The radiation emitted from the capsule destroys the tumor. The radioactivity of the capsule decreases a little each day. The amount of radioactivity of the capsule is carefully calculated to run out when the optimal dose has been given. You need to stay in the hospital for several days while receiving this treatment.