A Monte Carlo simulation-based study of 235U distribution effect on lung counter detection efficiency
10.3760/cma.j.cn112271-20240725-00276
- VernacularTitle:基于蒙特卡罗模拟的 235U分布对肺计数器探测效率的影响
- Author:
Jie LIU
1
;
Yunlong JI
1
;
Xu XU
1
;
Xiaomin ZHANG
1
;
Dawei LI
1
;
Yuxin ZHANG
1
;
Jing NING
1
Author Information
1. 军事科学院军事医学研究院，北京 100039
- Publication Type:Journal Article
- Keywords:
Monte Carlo simulation;
Biokinetic model;
Radioactive internal contamination;
Detection efficiency
- From:
Chinese Journal of Radiological Medicine and Protection
2025;45(3):223-228
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the effect of nuclide distribution with time from the in vivo metabolism based on measurement of radioactive contamination using lung counting method. Methods:The distribution of nuclides in the body with time was calculated on a basis of a single inhalation of aerosols containing 235U and the International Commission of Radiological Protection(ICRP) nuclide metabolism compartment model. A passive efficiency calibration of the lung counter, was performed using the simulation and calculation software Geant4 to obtain the contribution of the tissue or organs of interest to the lung counter, and to investigate the effect of the nuclide distribution on the lung counting method. Results:The time elapsed after inhalation of radionuclides, as well as their physicochemical state, has the effect on their distribution in the body and on the detection efficiency of the lung counter. Radionuclides with smaller particulate sizes have a higher initial retention in the lungs, and those with an activity median aerodynamic diameter (ADAM) of 1 μm contributed more fraction to the lung counter than those with an ADAM of 5 μm. F-type compounds were metabolized more rapidly by the respiratory system, and after 8 h of ingestion, nuclides were distributed in the lungs. F-type compounds were metabolized in the respiratory system at a relatively fast rate, and 8 h after inhalation, the fraction of nuclides retained in the lung contributed no more than 30% to the lung counter. Within 3 d after ingestion of M-type and S-type compounds, radioactive particulats largely deposites in the nasopharyngeal region. With biological metabolization and clearance, the fraction contributed by lung to counter is in rising, and the fraction to the lung counter typically remained larger than 80% after 3 d.Conclusions:Radionuclide metabolization in the body varies with their physicochemical properties and measurement time and site. For estimating internal contamination, consideration should be given to the distribution of nuclides, in order to avoid the overestimation.
