Urban populations in Morocco receive free medical drugs as prescribed by doctors in district health centres.To explore the exposure pathway of ^(238)U and^(232)Th and their decay products on the skin of patients,these...Urban populations in Morocco receive free medical drugs as prescribed by doctors in district health centres.To explore the exposure pathway of ^(238)U and^(232)Th and their decay products on the skin of patients,these radionuclides were measured in various medical drugs by using solid-state nuclear track detectors(SSNTDs).The measured concentrations range of ^(238)U and ^(232)Th in the medical drug samples of interest vary from(4.3±0.3) to(11.1±0.7) mBq 1^(-1) and(0.49±0.03) to(1.3±0.1)mBq 1^(-1),respectively.A new dosimetric model,based on the concept of specific alpha-dose and alpha-particle residual energy,was developed for evaluating radiation doses to skin following the application of different medical drugs by patients.The maximum total equivalent effective dose to skin due to the ^(238)U and ^(232)Th series from cutaneous application of different medical drugs by patients was found to be 2.8 mSv year^(-1) cm^(-2).展开更多
The radioisotope actinium-225(^(225)Ac)has been successfully used for targeted alpha therapy in preclinical and clinical applications because of its excellent nuclear characteristics.Medium-and high-energy proton-spal...The radioisotope actinium-225(^(225)Ac)has been successfully used for targeted alpha therapy in preclinical and clinical applications because of its excellent nuclear characteristics.Medium-and high-energy proton-spallation reactions on thorium are the most important methods for producing^(225)Ac.This study examines the possibility of producing^(225)Ac by irradiating thorium oxide with medium-energy protons.Thorium-oxide sheets were irradiated with 40-,50-,60-,70-,and 80-Me V protons on the Associated Proton-beam Experiment Platform(APEP)of the China Spallation Neutron Source(CSNS).The cross sections for the formation of^(225)Ac were measured using the activation method and offline gamma-ray spectrometric technique.The experimental results were compared with the existing data from EXFOR as well as the theoretical data from the TALYS-based evaluated nuclear-data library.Based on the experimental cross section and theoretical calculations,the production yield of^(225)Ac in the irradiated thorium targets was examined.The results showed that APEP can produce sufficient quantities of^(225)Ac for purification and clinical therapy.This work is the first measurement of proton-induced nuclearreaction cross sections at the CSNS APEP.展开更多
Statistical biases may be introduced by imprecisely quantifying background radiation reference levels. It is, therefore, imperative to devise a simple, adaptable approach for precisely describing the reference backgro...Statistical biases may be introduced by imprecisely quantifying background radiation reference levels. It is, therefore, imperative to devise a simple, adaptable approach for precisely describing the reference background levels of naturally occurring radionuclides (NOR) in mining sites. As a substitute statistical method, we suggest using Bayesian modeling in this work to examine the spatial distribution of NOR. For naturally occurring gamma-induced radionuclides like 232Th, 40K, and 238U, statistical parameters are inferred using the Markov Chain Monte Carlo (MCMC) method. After obtaining an accurate subsample using bootstrapping, we exclude any possible outliers that fall outside of the Highest Density Interval (HDI). We use MCMC to build a Bayesian model with the resampled data and make predictions about the posterior distribution of radionuclides produced by gamma irradiation. This method offers a strong and dependable way to describe NOR reference background values, which is important for managing and evaluating radiation risks in mining contexts.展开更多
快速可靠的230Th/232Th比值测定方法在230Th定年法中非常重要。实验室在前期工作基础上,建立了高分辨电感耦合等离子体质谱法(HR-ICP-MS)测定天然样品中230Th/232Th比值的方法。影响230Th/232Th比值精确测定的主要因素是测量过程中强峰...快速可靠的230Th/232Th比值测定方法在230Th定年法中非常重要。实验室在前期工作基础上,建立了高分辨电感耦合等离子体质谱法(HR-ICP-MS)测定天然样品中230Th/232Th比值的方法。影响230Th/232Th比值精确测定的主要因素是测量过程中强峰拖尾效应和仪器的质量歧视等。238U在236U处的强峰拖尾系数236U/238U可用于230Th/232Th比值的强峰拖尾校正,通过测量不同230Th/232Th比值的标准溶液可获得仪器测量230Th/232Th比值的质量歧视校正因子。采取四酸密闭消解法对砂岩样品进行消解,用Bio-rad AG 1×8 Cl-型阴离子交换树脂对钍进行分离,进一步纯化后稀释到一定体积在HR-ICPMS上进行测量。采用空白-标准-空白样品的测量模式对230Th/232Th比值进行测量。实验室标样的测量结果为(7.29±0.34)×10-6,与参考值(7.33±0.17)×10-6一致。展开更多
基金under an URAC-15 research contract with the CNRST,Rabat,Morocco
文摘Urban populations in Morocco receive free medical drugs as prescribed by doctors in district health centres.To explore the exposure pathway of ^(238)U and^(232)Th and their decay products on the skin of patients,these radionuclides were measured in various medical drugs by using solid-state nuclear track detectors(SSNTDs).The measured concentrations range of ^(238)U and ^(232)Th in the medical drug samples of interest vary from(4.3±0.3) to(11.1±0.7) mBq 1^(-1) and(0.49±0.03) to(1.3±0.1)mBq 1^(-1),respectively.A new dosimetric model,based on the concept of specific alpha-dose and alpha-particle residual energy,was developed for evaluating radiation doses to skin following the application of different medical drugs by patients.The maximum total equivalent effective dose to skin due to the ^(238)U and ^(232)Th series from cutaneous application of different medical drugs by patients was found to be 2.8 mSv year^(-1) cm^(-2).
文摘在第四代反应堆的发展中,钍基反应堆(例如钍基熔盐堆)是其中一个重要的研究方向.由于钍的储量大等因素,利用中子诱发^(232)Th发生辐射俘获反应产生^(233)Th是钍基反应堆中的一个重要反应,用于产生易裂变核素^(233)U.本研究采用Monte Carlo方法,定义了一种评价靶材和中子利用效率的综合利用系数,利用多项式拟合得到了综合利用系数和靶材厚度关系,并考虑了不同入射中子数目的影响,最后得到进行此反应的靶材最佳厚度为(1.980±0.002) cm.
基金supported by the National Natural Science Foundation of China(No.12075135)the National Natural Science Foundation of China(No.12375127)。
文摘The radioisotope actinium-225(^(225)Ac)has been successfully used for targeted alpha therapy in preclinical and clinical applications because of its excellent nuclear characteristics.Medium-and high-energy proton-spallation reactions on thorium are the most important methods for producing^(225)Ac.This study examines the possibility of producing^(225)Ac by irradiating thorium oxide with medium-energy protons.Thorium-oxide sheets were irradiated with 40-,50-,60-,70-,and 80-Me V protons on the Associated Proton-beam Experiment Platform(APEP)of the China Spallation Neutron Source(CSNS).The cross sections for the formation of^(225)Ac were measured using the activation method and offline gamma-ray spectrometric technique.The experimental results were compared with the existing data from EXFOR as well as the theoretical data from the TALYS-based evaluated nuclear-data library.Based on the experimental cross section and theoretical calculations,the production yield of^(225)Ac in the irradiated thorium targets was examined.The results showed that APEP can produce sufficient quantities of^(225)Ac for purification and clinical therapy.This work is the first measurement of proton-induced nuclearreaction cross sections at the CSNS APEP.
文摘Statistical biases may be introduced by imprecisely quantifying background radiation reference levels. It is, therefore, imperative to devise a simple, adaptable approach for precisely describing the reference background levels of naturally occurring radionuclides (NOR) in mining sites. As a substitute statistical method, we suggest using Bayesian modeling in this work to examine the spatial distribution of NOR. For naturally occurring gamma-induced radionuclides like 232Th, 40K, and 238U, statistical parameters are inferred using the Markov Chain Monte Carlo (MCMC) method. After obtaining an accurate subsample using bootstrapping, we exclude any possible outliers that fall outside of the Highest Density Interval (HDI). We use MCMC to build a Bayesian model with the resampled data and make predictions about the posterior distribution of radionuclides produced by gamma irradiation. This method offers a strong and dependable way to describe NOR reference background values, which is important for managing and evaluating radiation risks in mining contexts.
文摘快速可靠的230Th/232Th比值测定方法在230Th定年法中非常重要。实验室在前期工作基础上,建立了高分辨电感耦合等离子体质谱法(HR-ICP-MS)测定天然样品中230Th/232Th比值的方法。影响230Th/232Th比值精确测定的主要因素是测量过程中强峰拖尾效应和仪器的质量歧视等。238U在236U处的强峰拖尾系数236U/238U可用于230Th/232Th比值的强峰拖尾校正,通过测量不同230Th/232Th比值的标准溶液可获得仪器测量230Th/232Th比值的质量歧视校正因子。采取四酸密闭消解法对砂岩样品进行消解,用Bio-rad AG 1×8 Cl-型阴离子交换树脂对钍进行分离,进一步纯化后稀释到一定体积在HR-ICPMS上进行测量。采用空白-标准-空白样品的测量模式对230Th/232Th比值进行测量。实验室标样的测量结果为(7.29±0.34)×10-6,与参考值(7.33±0.17)×10-6一致。
