Radiation therapy, also called X-ray therapy, uses high levels of radiation to kill prostate cancer cells or keep them from growing and dividing, while minimizing damage to healthy cells.
Radiation can be produced from a machine outside the body (external radiation) and directed right at the prostate or by putting materials that produce radiation (radioisotopes) through thin plastic tubes into the cancer-infected area (internal radiation or brachytherapy).
Internal radiation therapy places radioactive implants directly into the tumor. These radioactive sources can be temporary (removed after the proper dose is reached) or permanent.