Radiation therapy is a treatment with the help of high-vitality x-beams or different particles to obliterate growth cells. It is mainly of two types only; external and internal radiotherapy. Cranial radiation treatment (CRT) is used to treat an extensive variety of threatening and benevolent conditions. It is a curial therapy in treatment of cancer. There is some side effect of radiation therapy in treatment of cancer. These side effect may be short term or may be long term. In other words, radiation not only kills or slows the growth of cancer cells, it can also affect nearby healthy cells. Damage to healthy cells can cause side effects.