Evaluation of photon and neutron dose distribution in radiotherapy room from the Varian Clinac 2300EX 10 MV and 15 MV medical LINAC for radiation protection purposes using MCNP6

Abstract

The photons and neutron beam characteristics of the variant Clinac 2300EX were obtained from simulation and computation using the MCNP6 software. The electron beam energies of 10 MeV and 15 MeV were applied in this study. The source of the electrons is the cathode, which is a filament accelerated at high voltage until it hits the target metal and produces X-rays. The X-rays are directed towards the phantom which is 100 cm from the source. The primary purpose of these measurements is the radiation safety for radiation workers and the public. Measurement of photon and neutron doses are carried out on the patient table, operator station, behind doors and in waiting rooms. The results were the neutron dose rate when 10 MV on the patient table, operator station, behind the wall, and waiting room were (1.183 ± 0.040) × 10−4, respectively; 0; (6.836 ± 0.719) × 10−11; (4.100 ± 0.710) × 10−11 Sv / s, while the respective photon dose rates are (2.643 ± 0.006 × 10−3; 0; 0; 0) Sv / s. At 15 MV the results of the neutron dose rate were on the patient table, operator’s station, behind the door, and the waiting room for (6.888 ± 0.007) ± 10−3; (6.068 ± 0.461) ± 10−10; (4.360 ± 0.019) ± 10−9; (2.025 ± 0.125) ± 10−9 Sv / s, while their respective photon dose rates were (6.711 ± 0.004) ± 10−3; 0; 0; 0) Sv / s. From the results of dose rate measurement, the total effective dose received by radiation workers and the public in the radiotherapy unit was predicted and the results were compared with the dose limit value (NBD) set by Bapeten. The result is that the total effective dose received by workers and the public waiting for the patient does not exceed the set threshold value.