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Definition of Therapy, external beam radiation
Medically reviewed by Dr. Otari Nergadze, Neurosurgeon | Updated: January 2026
Therapy, external beam radiation: Radiation focused from a source outside the body on the affected area (a cancer) within the body. It's much like getting a diagnostic x-ray, but using a more potent x-ray beam and giving it over a longer period of time per dose with usually multiple doses given over multiple days.