External Beam Radiation Therapy. Radiation treatment for prostate cancer, where a high dose of radiation is delivered from an outside source into the prostate to kill the cancer. The radiation must transverse through healthy tissue to reach the cancerous area. Treatments are generally 5 days a week for 7-8 weeks. Each treatment last only a few minutes. Newer forms of external beam radiation, called three-dimensional conformal radiation (3D-CRT) and intensity modulated radiotherapy (IMRT) more accurately target the prostate and are considered the preferred method when using external beam radiation for the initial treatment of prostate cancer. With these newer therapies the patient is immobilized and subjected to radiation beams aimed from several directions.

external beam radiation treatment that can include conventional photons, or use protons, neutrons, or electrons. This may be given conventionally or with 3D conformal techniques; see also IMRT.

External beam radiation therapy. A form of radiation therapy in which radiation from an outside source is focused on the on the prostate gland to kill cancer cells.