probability assessment of photoneutron production of varian-clinac ix linear accelerator using monte carlo simulation

Overdose in the patient’s body disrupts the treatment process and may have devastating effects. on the other hand, if the particle is a neutron, this effect would be multiplied. because neutrons in the energy range of about 0.1 to 2 mev produced in medical linear accelerators have a quality factor (qa) of 20, which creates a high equivalent dose in the tissue. in this paper, the photoneutron production probability of components of the 18 mv varian-clinac ix linear accelerator has been performed using the monte carlo simulation. the contribution of each gantry component of the accelerator and phantom in neutron production per gray of photons was calculated. results showed that the largest ratio in the production of photoneutrons belongs to the primary collimator per photon gray per square centimetre. also, in the target, which is the first source of photon neutron production, the flux of thermal neutrons is calculated at zero.