The goal of radiation therapy is to slow or control tumor growth. It uses painless X-rays (or other radioactive particles) to destroy tumor cells. Radiation therapy can be used alone. Or it can be used with other types of treatment such as surgery or chemotherapy. If your doctor advises radiation therapy for you, you may get one of several types of external beam radiation or internal radiation (brachytherapy).
There are several types of external beam radiation therapy.
3-D conformal radiation therapy (3DCRT) directs radiation from many directions to reduce damage to nearby tissues.
Intensity modulated radiation therapy (IMRT) uses a computer-driven machine that moves around the person's head as it delivers radiation. Both the angles of the radiation beams and the strength of the radiation can be changed to fit the shape of the tumor.
Proton beam radiation therapy uses proton beams instead of X-rays. The proton beams release their energy at a certain distance. This reduces damage to nearby tissues. Other heavy ion beams are also under study for use.
Whole brain radiation is used to treat multiple tumors or cancer that has spread through the brain. It sends radiation to the entire brain. It may have more severe side effects.
Stereotactic radiosurgery involves a single high dose of radiation. Sometimes it may be several high doses aimed right at the tumor from many different directions. Since it is very focused, the normal tissue around the tumor gets little or no radiation. A machine will beam the radiation to the tumor. Two of the most common machines used are the Gamma Knife, which sends gamma rays, and the linear accelerator, which sends X-rays.
Small radioactive seeds are placed in or near the tumor during surgery or through tubes called catheters. The radiation only travels a short distance in the body so damage to surrounding tissue is reduced. Stronger radioactive seeds are used more commonly. They may be removed after minutes or up to 7 days. Weaker seeds may stay in place permanently and become inactive.
Side effects will vary with the type and strength of radiation used, the tumor type, and where the tumor is, among other variables.
Short-term side effects and risks are brain swelling, fatigue, nausea, vomiting, infection, bleeding, dizziness, headache, seizures, hair loss, hearing loss, and skin changes in the treated area.
Long-term side effects and risks are memory loss, trouble thinking, permanent hair loss, hormonal changes, and death of surrounding tissue (necrosis).