External beam radiation therapy is delivered by means of a linear accelerator. Linear accelerators use powerful generators to create the high energy x-rays for external beam radiation therapy. The linear accelerator has a special set of lead shutters, called collimators, which focus and direct the x-rays to the tumor. Interstitial irradiation, and intracavitary irradiation are types of brachytherapy. Some patients may receive both types of treatment.
Linear accelerators produce x-rays at various energies.
Multiple angles allow the maximum amount of radiation to be delivered to the tumor while delivering a minimal amount of radiation to the surrounding healthy tissue. Gamma Rays and Cobalt Therapy Systems Gamma rays are another form of photons used in radiotherapy. Each element decays at a specific rate and gives off energy in the form of gamma rays and other particles. X-rays and gamma rays have the same effect on cancer cells. Many of the original cobalt gamma ray systems have been replaced with linear accelerators.