Irradiation:The use of high-energyradiationfrom x-rays, gamma rays, neutrons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beamradiation therapy) or from materials called radioisotopes. Radioisotopes produce radiation and can be placed in or near the tumor or in the area near cancer cells. This type of radiation treatment is called internal radiation therapy, implant radiation,interstitialradiation, or brachytherapy. Systemic radiation therapy uses a radioactive substance, such as a radiolabeledmonoclonal antibody, that circulates throughout the body.Irradiationis also called radiation therapy,radiotherapy, andx-raytherapy.
