Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. There are two types of radiation therapy. 

• External radiation therapy uses a machine outside the body to send radiation toward the cancer.
• Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer.

Radiosurgery is a method of delivering radiation directly to the tumor with little damage to healthy tissue. It does not involve surgery and may be used to treat certain tumors in patients who cannot have surgery. The way the radiation therapy is given depends on the type and stage of the cancer being treated.