Darvish-Molla S, Prestwich W V, Byun S H
Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1
Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada L8S 4K1.
Radiat Prot Dosimetry. 2016 Dec;171(4):421-430. doi: 10.1093/rpd/ncv428. Epub 2015 Oct 13.
In order to investigate the radiation dose dependence on the incident proton energy, neutron and gamma-ray doses were measured using a tissue-equivalent proportional counter in the proton energy range of 1.95-2.50 MeV for the McMaster Li(p,n) neutron facility. Microdosimetric spectra were collected, and absorbed doses were determined at various positions inside the irradiation cavity, along the lateral axis and outside the shield to find out the spatial distributions of neutron and gamma-ray doses for each proton energy. In parallel with the absorbed dose measurements, MCNP Monte Carlo simulations were carried out and neutron fluence spectra were computed at various positions, which enabled determination of the neutron weighting factors. It was found that neutrons make a substantially dominant contribution to the total equivalent dose for most proton energies and positions. The effective dose for a human subject increased from 0.058 to 1.306 μSv μA min with the increase of proton energy from 1.95 to 2.5 MeV. It is expected that the reported data will be useful for Li(p,n) accelerator neutron users.
为了研究辐射剂量对入射质子能量的依赖性，利用组织等效正比计数器在麦克马斯特大学的Li(p,n)中子设施中，在1.95 - 2.50 MeV的质子能量范围内测量了中子和γ射线剂量。收集了微剂量谱，并在辐照腔内沿横轴的不同位置以及屏蔽体外确定了吸收剂量，以找出每种质子能量下中子和γ射线剂量的空间分布。在进行吸收剂量测量的同时，开展了MCNP蒙特卡罗模拟，并计算了不同位置的中子注量谱，从而能够确定中子权重因子。结果发现，对于大多数质子能量和位置，中子对总当量剂量的贡献占主导地位。随着质子能量从1.95 MeV增加到2.5 MeV，人体受试者的有效剂量从0.058增加到1.306 μSv/μA·min。预计所报告的数据将对Li(p,n)加速器中子用户有用。
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