Radiotherapy is the process of using ionizing radiation produced by radioactive materials to change the physical and chemical properties of biological tissues. Radiation for industrial or research purposes may be used or accelerated for medical clinical purposes if there is a medical indication for the treatment or diagnosis of disease. This is called radioisotope therapy. Types of radiotherapy include external beam radiation therapy (primarily using beta and gamma radiation), proton therapy, or interstitial radiation therapy. These types of therapies are used for various cancer sites, as well as for other purposes including functional organ damage (brain, heart, liver), cosmetic enhancements, specialty research, and other therapeutic applications. In some cases, a solution of a radioactive isotope is injected into the cancerous tissue. Radiation cancer (from “radio” - glow, that is, “radiation therapy”) is a term used in relation to individuals who have received such a radiation dose that there is an increased likelihood of developing a malignant tumor in surrounding healthy individuals who will be exposed to such rays from the already deceased sick. Therefore, persons exposed near a given cancer hospital, on the territory of which there was a radioactive source, may subsequently be exposed to radiation from these patients for several months.