Medical Definition of Therapy, external beam radiation
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.
Quick GuideUnderstanding Cancer: Metastasis, Stages of Cancer, and More
Subscribe to MedicineNet's Cancer Report Newsletter