通讯机构：
[Zhou, QZ ] U;Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.
关键词：
Thoron;Progeny;Regulatory;CFD simulation
摘要：
The impact of the radiation dose produced by
$${^{222}\hbox {Rn}}$$
/
$${^{220}{\hbox {Rn}}}$$
and its progeny on human health has garnered increasing interest in the nuclear research field. The establishment of robust, regulatory, and competent
$${^{220}{\hbox {Rn}}}$$
chambers is crucial for accurately measuring radioactivity levels. However, studying the uniformity of the
$${^{220}{\hbox {Rn}}}$$
progeny through experimental methods is challenging, because measuring the concentration of
$${^{220}{\hbox {Rn}}}$$
and its progeny in multiple spatial locations simultaneously and in real time using experimental methods is difficult. Therefore, achieving precise control of the concentration of
$${^{220}{\hbox {Rn}}}$$
and its progeny as well as the reliable sampling of the progeny pose significant challenges. To solve this problem, this study uses computational fluid dynamics to obtain the flow-field data of the
$${^{220}{\hbox {Rn}}}$$
chamber under different wind speeds and progeny-replenishment rates. Qualitative analysis of the concentration distribution of the progeny and quantitative analysis of the progeny concentration and uniformity of the progeny concentration are conducted. The research findings indicated that the progeny concentration level is primarily influenced by wind speed and the progeny-complement rate. Wind speed also plays a crucial role in determining progeny concentration uniformity, whereas the progeny-complement rate has minimal impact on uniformity. To ensure the accuracy of
$${^{220}{\hbox {Rn}}}$$
progeny concentration sampling, we propose a methodology for selecting an appropriate sampling area based on varying progeny concentrations. This study holds immense importance for enhancing the regulation and measurement standards of
$${^{220}{\hbox {Rn}}}$$
and its progeny.
作者机构：
[Xiao, Detao; Hu, Yihao; Wu, Haibiao; Xiao, DT] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Zhang, Peng; Wang, Baoyi; Cao, Xingzhong; Li, Chong; Wei, Long; Liu, Fuyan; Wei, L; Kuang, Peng; Cao, XZ] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.;[Wang, Baoyi; Cao, Xingzhong; Wei, Long; Wei, L; Cao, XZ] Univ Chinese Acad Sci, Beijing 100039, Peoples R China.;[Wu, Haibiao] Univ South China, Affilated Hosp 1, Hengyang 421001, Peoples R China.
通讯机构：
[Wei, L ; Cao, XZ] C;[Xiao, DT ] U;Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.;Univ Chinese Acad Sci, Beijing 100039, Peoples R China.
关键词：
Monte Carlo simulation;multi-elemental targets;muonic x-ray;distribution of muonic atoms
摘要：
<jats:title>Abstract</jats:title>
<jats:p>Determining the distribution of muonic atoms is essential for <jats:italic>μ</jats:italic>-X ray imaging. In this study, the generation and de-excitation of muonic atoms in multi-elemental targets were simulated using the Monte Carlo software toolkit Geant4. An approach that reconstructs the production sites of muonic atoms from the <jats:italic>μ</jats:italic>-X ray momentum is proposed. The imaging results indicated a high simulated spatial resolution of 0.1 mm and a significant increase in the detection efficiency compared to that achieved by the 3-mm pinhole imaging technique. In addition, an analysis of the image quality index (<jats:italic>Q</jats:italic>) revealed that a superior image quality can be achieved for elements with high and medium atomic numbers. The proposed method has the potential to be further developed into an accurate and efficient technique for positioning the distribution of elements.</jats:p>
作者机构：
[伍海彪; 肖德涛] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;[吴亚茹; 张鹏; 刘福雁] Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China;University of Chinese Academy of Sciences, Beijing, 100049, China;[曹兴忠; 于润升; 彭雄刚; 王宝义; 张红强] Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China, University of Chinese Academy of Sciences, Beijing, 100049, China;[王垒] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
通讯机构：
[Xiao, D.] S;[Liu, F.] I;Institute of High Energy Physics, China;School of Nuclear Science and Technology, China
作者：
Bo Yu;Xiangyuan Deng;Haibiao Wu;Chengtao Yue;Detao Xiao
期刊：
Journal of Physics: Conference Series,2023年2437(1):012063 ISSN：1742-6588
通讯作者：
Xiao, Detao(xiaodt@usc.edu.cn)
作者机构：
[Bo Yu; Xiangyuan Deng; Haibiao Wu; Chengtao Yue; Detao Xiao] School of Nuclear Science and Technology, University of South China, Hunan, Hengyang;421001, China;Radon Key Laboratory of Hunan Province, University of South China, Hunan, Hengyang;[Bo Yu; Xiangyuan Deng; Haibiao Wu; Detao Xiao] 421001, China <&wdkj&> Radon Key Laboratory of Hunan Province, University of South China, Hunan, Hengyang;[Bo Yu; Xiangyuan Deng; Haibiao Wu; Chengtao Yue; Detao Xiao] 421001, China
摘要：
<jats:title>Abstract</jats:title>
<jats:p>Radon is a naturally occurring radioactive inert gas that poses a significant threat to the human health. Coconut shell activated carbon has been verified to be the best radon adsorbing material, but its radon adsorption capacity still cannot meet the requirement of industrial applications. Activated carbon modification using liquid nitrogen is an effective method for improving the radon adsorption capacity, but it is necessary to determine the conditions for large-scale production. In this study, the influence of environmental temperature, container geometry, and amount of activated carbon and liquid nitrogen on the modification effect are examined. The results show that the activated carbon has the best modification effect when the container is placed in a water bath at 50 °C. The container geometry and activated carbon mass have a minor influence on the modification effect. Further, the radon adsorption capacity is increased by 36% when 6.5 L of liquid nitrogen is added to 1 kg of activated carbon. The characterization results reveal that the chemical structure and elemental content of the activated carbon do not change after modification, but the number of micropores is significantly increased, especially the micropores with a size of 0.5-0.6 nm, which is related to the radon adsorption capacity of the modified activated carbon. Overall, the liquid-nitrogen-based modification is a simple, environment-friendly, and low-cost method to improve the radon adsorption capacity of activated carbon, which can be used in the large-scale production of highly efficient radon adsorbents.</jats:p>
通讯机构：
[Hai Wang] S;[Jian Zheng] N;National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, 491 Anagawa, Inage, Chiba, 263-8555, Japan<&wdkj&>School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China<&wdkj&>National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, 491 Anagawa, Inage, Chiba, 263-8555, Japan
期刊：
Fusion Engineering and Design,2021年172:112746 ISSN：0920-3796
通讯作者：
Xiao, Detao(xiaodt@usc.edu.cn)
作者机构：
[Xiao, Detao; Wang, Zhen; Wu, Haibiao] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Zhu, Te; Zhang, Peng; Wang, Baoyi; Cao, Xingzhong; Wang, Zhen; Song, Yamin] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.;[Wu, Haibiao] Univ South China, Affilated Hosp 1, Hengyang 421001, Peoples R China.
通讯机构：
[Detao Xiao] S;[Xingzhong Cao] I;School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China<&wdkj&>Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
关键词：
W and W-5wt%Re;Helium ions;Microdefects;Irradiation temperature;DBS;TEM;SEM
摘要：
W and W-5wt%Re alloy were irradiated by 50 keV helium ions at RT, 200 degrees C, 350 degrees C and 500 degrees C to investigate the influence of temperature on the microdefects and surface morphology in the sample. The microdefects in the subsurface region and the surface damage caused by irradiation were characterized by Doppler broadening spectroscopy (DBS) of slow positron beam, transmission electron microscope (TEM) and scanning electron microscopy (SEM), respectively. The results show that a large number of vacancy-type defects were produced after helium ions irradiation, especially at 500 degrees C, the vacancy-type defects of W alloy are higher than that of W-5wt% Re alloy, which indicated that Re restricted the behavior of vacancy-type defects in tungsten to some extent. The surface irradiation damage such as crystal gap enlargement, grain fell off and pores were observed at different irradiation temperatures. Compared with the coral-like structure observed in W, the circular objects and Hillygully structure were observed in W-5wt%Re alloy, and both of them increased and grew with the increase of irradiation temperature. It was speculated that the presence of Re led to the difference by analyzing the formation mechanism of the coral-like structure and the Hilly-gully structure.
作者机构：
[Liang, Juncheng; Sun, Changhao] Division of Ionizing Radiation Metrology, National Institute of Metrology, Beijing 100029, China;[Xiao, Detao; Sun, Changhao] School of Nuclear Science and Technology, University of South China, Hengyang, Hunan 421001, China;[Wang, Yunxiang; Guo, Qiuju; Wang, Hao] State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China;[Wang, Shanqiang; Zhang, Lei; Wang, Hao] State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
摘要：
<jats:title>Abstract</jats:title>
<jats:p>The unattached fraction (fp) and activity concentration ratio of radon progeny (${\boldsymbol C}_{{}{}^{\bf 218}\bf{Po}}:{\boldsymbol C}_{{}{}^{\bf 214}\bf{Pb}}:{\boldsymbol C}_{{}{}^{\bf 214}\bf{Bi}}$) are important for radon exposure dose evaluation. For getting these characteristic parameters in dwellings, a series of field measurement was carried out. For comparison, a semi-continuous measurement was carried out in an office room and outdoors. Results show that the average fp is 4.5%±2.2% and 3.8%±1.7% in city dwellings and in rural dwellings, respectively. The average activity concentration ratios are 1:0.94:0.70 for radon progeny and 1:0.07:0.06 for unattached radon progeny in city dwellings, while those in rural dwellings are 1:0.88:0.66 and 1:0.09:0.07. The average values of fp are 5.1%±0.9% and 5.4%±3.1% in the office room and in outdoors without significant difference. The average activity concentration ratios are 1:0.88:0.77 for radon progeny and 1:0.11:0.11 for unattached radon progeny in outdoors.</jats:p>
作者机构：
[Renchuan Zheng; Detao Xiao] College of Nuclear Science and Technology, University of South China, Hengyang, Hunan, 421001, China;[Along Chen; Jinhan Zhu; Lixin Chen] State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, China;[Shengxiu Jiao] School of Physics and Engineering Technology, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
通讯机构：
[Lixin Chen] S;[Detao Xiao] C;College of Nuclear Science and Technology, University of South China, Hengyang, Hunan, 421001, China<&wdkj&>State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, China
摘要：
To test the basic dosimetry characteristics of a new high-resolution matrix and to perform a preliminary study on the three-dimensional (3D) dose verification of intensity-modulated treatment (IMRT).
The dosimetry characteristics of the new matrix were investigated, including repeatability, dose-rate response, and dose linearity. Twenty cases of nasopharyngeal carcinoma (NPC) and 20 cases with lung cancer were randomly selected for IMRT plans, and the novel matrix was employed for 3D dose verification. The measured results were evaluated using the gamma passing rate (GPR) and dose volume histogram (DVH). The action limit (AL) and tolerance limit (TL) of the target volume and each organ at risk (OAR) were calculated with reference to the American Association of Physicists in Medicine (AAPM) TG218 report.
The matrix performed well for all dosimetry characteristic tests, with a deviation of <1%. The average GPRs of the body were (99.32 ± 0.32)%, (98.36 ± 0.59)%, and (96.27 ± 1.20)% for NPC, and (99.17 ± 0.74)%, (98.09 ± 1.33)%, and (95.83 ± 2.22)% for lung cancer at the gamma standards of 3%/3 mm, 3%/2 mm, and 2%/2 mm. The average GPRs difference between the head-neck and thorax-abdomen plans were <1% for the same gamma standard. For both the target volumes and OARs, the average GPRs were >90% under the relatively strict standard of 2%/2 mm. The DVH showed that the measurement results of D98 and D95 for the target volumes were slightly lower and D2 were higher than those of treatment planning system (TPS) (P < 0.01). In addition, with the same standard, there may be significant differences in the values of AL and TL between different structures for target volumes and OARs, especially small-volume OARs such as the chiasma and optic nerve-L.
The new matrix showed good dosimetry characteristics and can be effectively applied to the treatment planning dose verification of the head-neck and lung cancer. Further research is needed to establish how to analyze the GPR and DVH of the target volume and OARs, and to determine more precise dose verification standards combined with the parameters of AL and TL to better guide 3D dose verification in clinic.
作者机构：
[过灵飞; 何正忠; 肖德涛; 黎世铖; 林姝婧] Radon Key Laboratory of Hunan Province, School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China
作者机构：
[孙昌昊; 肖德涛] Hunan Provincial Key Laboratory of Radon, School of Nuclear Science and Technology, University of South China, Hengyang;421001, China;[张磊; 王善强] State Key Laboratory of NBC Protection for Civilian, Beijing;102205, China;[郭秋菊] State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing
作者机构：
[王中旺; 肖德涛; 邓湘元; 罗诗慧; 过灵飞] Radon Hunan Provincial Key Laboratory, School of Nuclear Science and Technology, University of South China, Hengyang;421001, China;[王中旺; 肖德涛; 邓湘元; 罗诗慧; 过灵飞] 421001, China
通讯机构：
[Detao Xiao; Zhengzhong He] S;School of Nuclear Science and Technology, University of South China, Hunan, Hengyang, China<&wdkj&>School of Nuclear Science and Technology, University of South China, Hunan, Hengyang, China
关键词：
radon;aerosol;Article;calibration;concentration (parameter);progeny;radiological parameters;theoretical model
