Monte Carlo simulation of photoneutron for a 15 MV medical linear accelerator
10.3760/cma.j.cn112271-20230126-00015
- VernacularTitle:15 MV医用直线加速器光中子蒙特卡罗模拟
- Author:
Lei DENG
1
;
Shugen QU
;
Zhe WANG
;
Yishui CHEN
;
Yu TU
;
Lubing ZHANG
Author Information
1. 江西省职业病防治研究院，南昌 330006
- Keywords:
Medical electron Accelerator;
Photonuclear reaction;
Neutron ambient dose equivalent;
Monte Carlo
- From:
Chinese Journal of Radiological Medicine and Protection
2023;43(12):1010-1015
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To study the photoneutron radiation field caused by photonuclear reaction during the operation of high energy medical linac.Methods:Monte Carlo was used to simulate the photoneutron pollution of Clinic 2300CD medical electron accelerator in 15 MV X-ray mode. The photoneutron spectrum at different positions of the head and the variation in neutron ambient dose equivalent in different irradiation fields were investigated, and the dose distribution of photoneutron on the isocenter plane and the dose attenuation in the water model were analyzed.Results:When the collimator was closed, the average photoneutron energy at the lower surface of target, primary collimator, flattening filter and multi-leaf collimator was 1.08, 1.20, 0.35 and 0.30 MeV, respectively. The neutron ambient dose equivalent at the isocenter first increased and then decreased with the irradiation field expanding, reaching the maximum in about 30 cm × 30 cm irradiation field. With the increase in the depth of the measuring point in water phantom, the neutron fluent first increased and then decreased, while the neutron dose gradually decreased. In different irradiation fields, the photoneutron dose rate was almost close to the background when the depth of the water was 20 cm.Conclusions:By exploring the photoneutron spectrum and dose distribution characteristics of the high energy medical linac head, as well as the dose deposition mechanism of photoneutron in water phantom, this study provides data support for further research on the additional dose and secondary cancer effects on patients caused by photoneutron pollution from the high energy medical linac.
