Document Type : Original Paper
Department of Physics, Payame Noor University (PNU), Tehran, Iran
Kerman Graduate University of Advance Technology
Department of Electrical and Computer Engineering, Graduate University of Advanced Technology, Haftbagh Blvd., Kerman, Iran
Neutron contamination in medical linear accelerators is a major concern in radiation therapy. Estimating the amount of these neutrons is widely discussed in many studies. In most of these methods, in order to extract the simulation results, electronic equipment is needed. The following study has proposed an innovative method for neutron detection which does not require a complex electrical circuit system.
Materials and methods
Neutron contamination is produced in VARIAN linear accelerators by interaction of energetic photons with heavy elements of accelerator head such as Tungsten. Investigation of neutron contamination in VARIAN linear accelerators using Thick Gas Electron Multiplier (THGEM) detector in Self-Quenching Streamer (SQS) mode by Monte Carlo simulation is the aim of this study. In detection system proposed in this study, a convert material is needed for converting neutron to proton. After directing the protons to THGEM and by applying the special voltage, the SQS mode is investigated. Results
Results show that in the proposed detection system, a distance of 0.5 cm from the converter is a suitable position for the THGEM and when minimum voltage of the THGEM is 700 volts, SQS mode is happened in almost every hole of THGEM. Also, in this proposed detection system, the variation in the neutron flux is proportional to the variation in the number of holes in the SQS mode.
Results show that the neutron contamination of VARIAN linear accelerator in treatment room could be investigated by applying THGEM detector in SQS mode. Also, the proposed detection system for estimating neutron contamination is simpler than similar types and less electrical tolerances are used in it. Cheap price and light weight are other advantages of this detection system and it could be made in different sizes.