Radiotherapy may help achieve different treatment goals. For example, it may increase the effectiveness of surgery, help prevent cancer from spreading, or reduce symptoms of advanced cancer. Most radiation therapy devices use photon beams. Photons are also used in X-rays, but at lower doses. Photon beams can reach tumors deep in the body. When photon beams pass through the body, they scatter some radiation along the way. These rays do not stop once they reach the tumor, but also go to the normal tissue. Radiation therapy is one of the types of cancer treatment methods that uses high-energy particles or waves such as X-rays, gamma rays, electron beams or by using a certain type of energy to stop the growth and division of cancer cells. As a result, the cell will gradually shrink and die. The goal of radiation therapy is to destroy cancer cells with minimal damage to healthy cells, but sometimes this treatment also damages healthy cells adjacent to the cancer tissue, or stops them from growing and dividing by destroying their DNA. Also, radiotherapy can be part of the treatment and prevent tumor recurrence after surgery to remove the malignant tumor. Radiation therapy increases the effect of chemotherapy and is used in sensitive tumors before, after and simultaneously with chemotherapy.