Abstarct: Nowadays canser is one of the most dangerous disease of humans and takes into account as an important factor of morbidity that it's treatment limited into three methods: surgery, radiotherapy and chemotherapy. Radiation therapy was carried out in distant years by devices that are still in the radiotherapy hospital departments throughout Iran. In recent years, other treatments for cancer have been developed using radiotherapy techniques that have more advanced technology. Gamma knife's device in the process of treatment of tumors of the skull area treats canser faster than radiation therapy. In the manufacture of Cyberknife, many of the problems associated with the old radiation therapy devices and even the Gamma knife device have been resolved and help the Cancer patients in terms of treatment, time and cost. This dissertation attempts to make a comparison between the dosage received in distant and near radiation sources in the radiation therapy device and the Gamma knife system, as well as points related to healthy and cancerous tissues in the skull area, to determine which Radiotherapy devices are less harmful to healthy tissues while it radiates to cancerous tissues. After performing the simulation, the radiation therapy device did not have a one-dimensional strain on the cancerous area. Gamma knife device with 201 sources of radiation in different directions is more appropriate than radiotherapy, but in the Gamma knife system, it only works in the skull area and does not eliminate the need for cancer tissues in other areas of body. The Cyberknife system covers many areas of the body in the face of cancer, and because of its robotic arm and radiation in different directions, the amount of received doses in the cancerous tissue reaches its maximum, and in other areas it reaches its minimum. The Cyberknife system, with a pre-designed program of radiation from different angles on cancerous tissue, causes a healthy tissue that receives less doses of radiation between the radiation source and the cancerous area, thereby destroying the cancerous tumor and the The tissue around the tumor remains healthy.