Cancer is one of the most deadly diseases posing threat for our health. The most important method for eradicating of cancer cells is photoradiotherapy. Electrons accelerated by the accelerator are converted to photons in the process of bremsstrahlung. These photons are focused on diseased cells. Photon leaving accelerator head should assure a given dose intensity in cancer cells. Measuring of beam parameters at apparatus output is essential to determine the dose. In this study, Suleyman Demirel University research and education hospital in radiation Oncology department which has located at 18 MeV accelerator in energy gamma dose was measured.