An optimized method for neutron dose evaluation based on 24Na activity distribution in the human body. (1st March 2023)

• Record Type: Journal Article
• Authors: Xu, Xu; Xiaomin, Zhang; Jing, Ning; Xiangdong, Xie; Yong, Yuan
• Is Part Of: Journal of radiological protection. Volume 43:Number 1(2023)
• Publication Date: 2023-03-01
• Subjects: 24Na distribution -- absorbed dose -- computational phantom -- characteristic γ ray -- γ fluence; Radiation -- Safety measures -- Periodicals; Health Physics -- Periodicals; Radiation Monitoring -- Periodicals; Radiation Protection -- Periodicals; Rayonnement -- Sécurité -- Mesures -- Périodiques; Electronic journals; Fulltext; Internet Resource; Periodical; 363.179905
• DOI: 10.1088/1361-6498/acb3d7
• Languages: English
• ISSNs: 0952-4746

Abstract

Abstract: The neutron dose resulting from external irradiation can be evaluated by measuring the counts of characteristic γ rays produced by 24 Na in the human body. The detection geometry with the highest detection efficiency for measuring the whole-body 24 Na activity has not been studied. In this work, the MCNP code is used to calculate the spatial distribution of 24 Na in the human body irradiated by neutrons with different energies in different irradiation geometries. The fluence distribution of 24 Na characteristic γ rays on the body surface is calculated. The counts of 24 Na characteristic γ rays induced by monochromatic neutron irradiation are simulated to fit the scenarios of neutron irradiation by a continuous energy spectrum neutron. When the spontaneous neutrons from 252 Cf with 1Gy dose irradiate the human body, (3.63–4.35) × 10 10 24 Na atoms are produced. The lower detection limit for the neutron absorption dose is reduced from ∼100 to less than 1 mGy when the radiation detector is placed over the back of the human body close to the liver. The relative error between the measured counts of 24 Na characteristic γ rays caused by 252 Cf neutron irradiation and the counts fitted by monochromatic neutron irradiation data is less than 5.7%. The neutron dose received from a continuous energy spectrum neutron can be acquired quickly and accurately by weighted summing of the data for monochromatic neutron irradiations calculated in this paper, which is more convenient and practical than the previous method.