Calculation of Effective Doses for External Neutrons

Monte Carlo calculations of the effective dose, on the basis of 1CRP Publication 60, were performed for external neutrons from thermal energy to 18.3 MeV for five irradiation geometries: AP, PA, RLAT, ROT and ISO. A unisex anthropomorphic phantom and the MORSE-CG code were used in conjunction with a nuclear data set based on the JENDL-3 library. The effective dose was found to be superior to the effective dose equivalent, the former quantity, for neutrons below about 1 MeV and inferior above this energy for all the geometries. The ambient dose equivalent based on the new Q-L relationship proposed in the Publication was found not necessarily to give a conservative estimate of the effective dose for the AP and PA geometries. The results obtained here were in good agreement with those calculated with a different computer code and a different nuclear data set.     

Organ dose conversion coefficients for external neutron irradiation based on the Chinese mathematical phantom (CMP)

A group of Monte Carlo simulations has been performed for external neutron dosimetry calculation based on a whole-body mathematical model. The Chinese mathematical phantom (CMP) is a mathematical human body model developed based on methods of ORNL (Oak ridge National Laboratory) mathematical phantom series (OMPS), and data from Chinese reference man and reference Asian man. Fluence-to-absorbed dose conversion coefficients of 24 organs and tissues for monoenergetic neutron beams ranging from 10^?9 to 10² MeV were calculated using the Monte Carlo code MCNPX. Irradiation conditions include anterior–posterior, posterior–anterior, right lateral, left lateral, rotational, and isotropic geometries. Results for the different organs are compared with those recommended in International Commission of Radiological Protection (ICRP) publication 74 and results obtained based on the visible Chinese human (VCH) phantom. Overall the consistency among the three sets of data was observed, but significant deviations up to 30–50% were also found in the AP, PA and lateral irradiation conditions. Since CMP represents the Chinese population, this work is helpful as a reference to investigate the difference of the neutron induced organ doses due to the anatomical variation between the Chinese and the Caucasians, and that between the average population and an individual.     

用蒙特卡罗方法计算光子外照射对人体产生的有效剂量

采用雌雄同体的成人人体模型和蒙特卡罗方法(MCNP4C)计算了环境γ射线外照射对人体产生的有效剂量.为了便于比较,计算中选用了ICRP 74号出版物中给出的20种不同的γ光子能量以及从前向后照射和从后向前照射两种辐照几何源.对计算结果进行比较发现,MCNP4C程序计算得到的结果与ICRP 74号出版物中给出的结果非常吻合.     

微波暴露人体比吸收率(SAR)的分布研究

本文采用时域有限差分法和仿真人体电磁模型,计算并比较了E、H二种极化方向和前向、后向、左侧向、右侧向四种照射几何条件下,3GHz微波人体暴露的全身平均比吸收率(SAR)、器官平均SAR和最大峰值SAR。结果表明,H极化、前向照射几何条件下人体的平均SAR较高,其中眼睛和睾丸的器官剂量最高。上述结果为3GHz微波生物效应的实验设计提供了科学依据。     

女性蹲姿曲面模型光子外照射剂量研究

基于中国女性参考人曲面模型建立女性蹲姿曲面模型,采用蒙特卡罗方法,针对6种标准光子外照射几何,计算光子能量0.01～10 MeV范围内21个能量点的器官吸收剂量转换系数和有效剂量转换系数,并与直立姿势的剂量数据进行了对比。结果表明:两种姿势中某些器官的吸收剂量转换系数在前后、后前以及侧向照射方式下差异较大。其中,后前照射方式下,光子能量为0.03 MeV时,乳腺的吸收剂量转换系数比直立姿势高115.1%。在不同照射方式下,大部分能量点的有效剂量转换系数的差异在10%范围内。转换系数的差异主要是由于胳膊和腿位置的改变,以及蹲姿时因身体前倾造成器官在照射方向上厚度发生改变而产生的。     

外照射的转换系数

本文介绍了ＩＣＲＰ既将出版的新的报告中关于外照射剂量测量的实用量，并结合ＩＣＲＰ６０号出版物对此进行了简要讨论。     

外照射情况下有效剂量（E）与有效剂量当量（HE）的比较

ＩＣＲＰ第６０号出版物引入了对外照射辐射剂量学的几个重大变化,６０号出版物推荐的辐射加权方法和基本防护量的技术规格与２６号出版的推荐有很大的不同,本文依据ＩＣＲＰ第７４号出版物给出的数据和讨论,对在各种照射几何条件下对不同能量的光子,中子及电子辐射场计算的有效剂量（Ｅ）与有效剂量当量（ＨＥ）的数值差别作了评述。     

Dose Conversion Coefficients for External Photons Based on ICRP 1990 Recommendations

Monte Carlo calculations were performed to estimate the effective doses E for external photons based on the recent proposals in the ICRP 1990 Recommendations. Twelve photon energies between 17 keV and 8.5 MeV and eleven irradiation geometries were selected to be applicable to many exposure conditions encountered in the working and living environment. A MIRD-based unisex phantom was used in conjunction with the Monte Carlo transport code MORSE-CG. The results were presented as a form of dose conversion coefficients transforming the air kerma or fluence in free air to the effective dose. These coefficients were given in graphical and tabular forms. Analyses of organs' fractional contribution to E showed that the gonadal exposure has generally a great contribution for all the geometries except the incidence from above. A comparison of conversion coefficients with other results gave a reasonably satisfactory agreement. Finally, the ambient dose equivalent H ^*(10), one of the operational quantities proposed by the ICRU, was found to give conservative estimates of E for most of the irradiation geometries considered, but it gives a considerable overestimate of E at the incidences from above and below.     

中国成年女性精细乳房模型的建立及其在外照射防护中的应用

乳腺是对辐射致癌最敏感的器官之一,2007年国际放射防护委员会(ICRP)将乳腺的组织权重因子由0.05提升为0.12,使乳腺剂量的准确评估变得更为重要。本文利用数学建模方法建立了精细乳房模型,包括输乳窦、输乳管、小叶和脂肪组织,模型体素化后与中国成年女性参考人体素模型进行了融合。利用该模型计算了光子AP照射时乳腺腺体的剂量转换系数,并与原来模型的计算结果进行对比。结果显示,光子能量较低时两个模型的计算结果相差30%,光子能量在0.03 MeV以上时差别不大。     

光子注量到空气比释动能转换系数的Monte-Carlo模拟

本文采用蒙特卡罗程序EGS5模拟计算单位注量的10keV～10MeV的光子在空气中所产生的空气比释动能,并将计算结果拟合成公式。模拟计算结果与ICRP74号报告中建议值的相对偏差在±2.0%以内,与ICRU47号报告中建议值的相对偏差在±3.5%以内;拟合值与前者的相对偏差在±4.0%以内,与后者的相对偏差在±7.0%范围内。     

ICRP Publication 115. Lung cancer risk from radon and progeny and statement on radon

Recent epidemiological studies of the association between lung cancer and exposure to radon and its decay products are reviewed. Particular emphasis is given to pooled case-control studies of residential exposures, and to cohorts of underground miners exposed to relatively low levels of radon. The residential and miner epidemiological studies provide consistent estimates of the risk of lung cancer, with significant associations observed at average annual concentrations of approximately 200 Bq/m3 and cumulative occupational levels of approximately 50 working level months (WLM), respectively. Based on recent results from combined analyses of epidemiological studies of miners, a lifetime excess absolute risk of 5 × 10?? per WLM [14 × 10?? per (mJh/m3)] should now be used as the nominal probability coefficient for radon- and radon-progeny-induced lung cancer, replacing the previous Publication 65 (ICRP, 1993) value of 2.8 × 10?? per WLM [8 × 10?? per (mJh/m3)]. Current knowledge of radon-associated risks for organs other than the lungs does not justify the selection of a detriment coefficient different from the fatality coefficient for radon-induced lung cancer. Publication 65 (ICRP, 2003) recommended that doses from radon and its progeny should be calculated using a dose conversion convention based on epidemiological data. It is now concluded that radon and its progeny should be treated in the same way as other radionuclides within the ICRP system of protection; that is, doses from radon and its progeny should be calculated using ICRP biokinetic and dosimetric models. ICRP will provide dose coefficients per unit exposure to radon and its progeny for different reference conditions of domestic and occupational exposure, with specified equilibrium factors and aerosol characteristics.     

15 keV~1.5 MeV单能光子及窄谱系列H*(10)/Kα转换系数的蒙特卡罗模拟

为克服由于不同标准实验室内X、γ射线照射装置所用X射线管型号及整体结构不相同,导致转换系数产生一定偏差的问题,本研究采用MCNP5程序建立照射装置模型,计算15 keV~1.5 MeV单能光子及N-40~N-200窄谱系列对应的H*(10)/Kα转换系数;利用自主研制的H*(10)次级标准电离室测量辐射场参考点处周围剂量当量率并作为参考值,与转换系数法进行对比以验证转换系数法计算结果的正确性。结果表明,蒙特卡罗模拟转换系数与ISO 4037-3推荐值的相对偏差在±4%以内,转换系数法与次级标准电离室法测量结果的相对偏差在3%以内,证明利用蒙特卡罗方法计算H*(10)/Kα转换系数可行,对于“非匹配参考辐射场”,可使用此方法进行周围剂量当量定值。     

Annals of the ICRP. A report of: doses to infants from ingestion of radionuclides in mothers' milk

In the present report, ICRP provides information on radiation doses to the infant due to intakes of radionuclides in maternal milk. As in Publication 88 (ICRP, 2001) on doses to the embryo and fetus following intakes of radionuclides by the mother, intakes by female members of the public and female workers are addressed. Acute and chronic intakes are considered at various times before and during pregnancy as well as during the period of breastfeeding. Dose coefficients per unit intake by the mother (Sv/Bq) are given for the selected radionuclides of the same 31 elements for which age-specific biokinetic models were given in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995a,b). For these elements, doses were calculated for the most radiologically significant natural or artificial radionuclides that might be released into the environment due to various human activities. Dose coefficients are also given in this report for radionuclides of an additional four elements: sodium, magnesium,phosphorus, and potassium. Relevant human and animal data on elemental and radionuclide transfer to milk are reviewed. The biokinetic models for adults given in earlier ICRP publications are adapted to include transfer to milk. Model predictions of fractional transfer of ingested or inhaled activity to milk are discussed in the report, and the corresponding dose coefficients for the infant are compared with dose coefficients for in utero exposure, as given in Publication 88 (ICRP, 2001). Illustrative information is also given on doses to the female breast from radionuclides in breastmilk, and external doses received by the child from radionuclides retained in the tissues of the mother. For the additional elements considered in this report, but not in Publication 88 (ICRP,2001), information is also given on doses to the embryo and fetus following maternal intakes of radioisotopes during or before pregnancy. A CD-ROM is to be issued giving data that will supplement the information given in this report. In addition to the dose coefficients given here, committed equivalent doses to the various organs and tissues of the offspring will be given. Dose coefficients will also be given for inhalation of a range of aerosol sizes for the selected radionuclides of the elements covered by this report.     

空间质子辐射有效剂量测量的闪烁探测器理论设计

有效剂量可解决航天员在空间飞行中所受质子辐射的危害比较与评价问题,在空间辐射危害评价中具有重要应用。为实现空间质子辐射有效剂量监测,针对空间各向同性质子辐射,利用蒙特卡罗程序设计了一种闪烁探测器。通过对探测器结构的特殊设计,在20-400 Me V能量范围内,各向同性质子在该探测器内沉积的能量与国际辐射防护委员会(International Commission on Radiological Protection,ICRP)116号报告提供的质子有效剂量基本成正比。通过探测质子沉积能量来监测质子辐射有效剂量,克服了直接测量有效剂量所存在的困难。对AP8MIN模型地球俘获带质子能谱与随机抽样质子辐射能谱,经数值计算,探测器给出的有效剂量与ICRP116号报告给出的有效剂量的相对偏差均小于±8%。     

Experimental Estimation of Effective Dose for Irradiation Geometries in Working Places According to ICRP 1990 Recommendations

Conversion coefficients for the equivalent dose in tissue or organ and the effective dose were estimated experimentally with BeO-TLDs inside a male RANDO phantom against external photon radiation. The experiments were performed for Superior-Inferior and Inferior-Superior geometries in cases of unusual irradiation conditions which were occasionally seen in high radiation areas. For these geometries, a parallel photon beam to the long axis of phantom was irradiated. To evaluate the shielding effect of legs in the Inferior-Superior geometry, measurements with and without legs were done by linking a leg phantom, made of tissue equivalent material. The difference of effective dose by the leg phantom was found to be about 20% in the energy range studied.

The effective dose was calculated from the equivalent dose in tissues or organs by modifying the tissue weighting factors given in ICRP Publ. 60 for males, and the effective dose equivalent according to ICRP Publ. 26 was also derived to be compared with the effective dose. In this experiment, the effective dose was estimated lower than the effective dose equivalent about 40% for Superior-Inferior geometry and about 20% for Inferior-Superior geometry due to the change in tissue weighting factors. However, there was no remarkable difference for Anterior-Posterior geometry.     

参考中子辐射注量－周围剂量当量换算系数的计算

基于ＩＣＲＰ第６０号出版物推荐的中子Ｑ值的拟合函数和Ｗａｇｎｅｒ等人提出的统一的剂量换算函数，对ＩＳＯ推荐的参考中子辐射计算了注量－周围剂量当换算系数，并就有关问题进行了讨论。     

Basic anatomical and physiological data for use in radiological protection: reference values: ICRP Publication 89

This report presents detailed information on age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. These reference values provide needed input to prospective dosimetry calculations for radiation protection purposes for both workers and members of the general public.The purpose of this report is to consolidate and unify in one publication, important new information on reference anatomical and physiological values that has become available since Publication 23 was published by the ICRP in 1975. There are two aspects of this work. The first is to revise and extend the information in Publication 23 as appropriate. The second is to provide additional information on individual variation among grossly normal individuals resulting from differences in age, gender, race, or other factors.This publication collects, unifies, and expands the updated ICRP reference values for the purpose of providing a comprehensive and consistent set of age- and gender-specific reference values for anatomical and physiological features of the human body pertinent to radiation dosimetry. The reference values given in this report are based on: (a) anatomical and physiological information not published before by the ICRP; (b) recent ICRP publications containing reference value information; and (c) information in Publication 23 that is still considered valid and appropriate for radiation protection purposes.Moving from the past emphasis on ‘Reference Man’, the new report presents a series of reference values for both male and female subjects of six different ages: newborn, 1 year, 5 years, 10 years, 15 years, and adult. In selecting reference values, the Commission has used data on Western Europeans and North Americans because these populations have been well studied with respect to antomy, body composition, and physiology. When appropriate, comparisons are made between the chosen reference values and data from several Asian populations.The first section of the report provides summary tables of all the anatomical and physiological parameters given as reference values in this publication. These results give a comprehensive view of reference values for an individual as influenced by age and gender.The second section describes characteristics of dosimetric importance for the embryo and fetus. Information is provided on the development of the total body and the timing of appearance and development of the various organ systems. Reference values are provided on the mass of the total body and selected organs and tissues, as well as a number of physiological parameters.The third section deals with reference values of important anatomical and physiological characteristics of reference individuals from birth to adulthood. This section begins with details on the growth and composition of the total body in males and females. It then describes and quantifies anatomical and physiological characteristics of various organ systems and changes in these characteristics during growth, maturity, and pregnancy. Reference values are specified for characteristics of dosimetric importance.The final section gives a brief summary of the elemental composition of individuals. Focusing on the elements of dosimetric importance, information is presented on the body content of 13 elements: calcium, carbon, chloride, hydrogen, iodine, iron, magnesium, nitrogen, oxygen, potassium, sodium, sulphur, and phosphorus.     

MC法计算γ射线外照射剂量转换因子

以剂量转换数学模型为基础,针对骨、软组织和水的等效组织球体剂量计算,采用蒙特卡罗软件MCNP5构建0.01~10 MeV的γ射线在这三种物质中的通量和能量沉积模拟模型,进而计算这三种物质的γ外照射剂量转换因子。同时给出这三种物质的γ外照射剂量转换因子对不同能量γ光子的拟合计算公式,并进行了数据验证。结果表明:剂量转换因子在γ射线能量低于0.15 MeV时,随着能量的增加按幂函数降低;高于0.15 MeV时,按指数函数上升;剂量转换因子模拟值与参考值随γ射线能量的变化规律相同。     

Basic anatomical and physiological data for use in radiological protection: reference values. A report of age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. ICRP Publication 89

This report presents detailed information on age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. These reference values provide needed input to prospective dosimetry calculations for radiation protection purposes for both workers and members of the general public. The purpose of this report is to consolidate and unify in one publication, important new information on reference anatomical and physiological values that has become available since Publication 23 was published by the ICRP in 1975. There are two aspects of this work. The first is to revise and extend the information in Publication 23 as appropriate. The second is to provide additional information on individual variation among grossly normal individuals resulting from differences in age, gender, race, or other factors. This publication collects, unifies, and expands the updated ICRP reference values for the purpose of providing a comprehensive and consistent set of age- and gender-specific reference values for anatomical and physiological features of the human body pertinent to radiation dosimetry. The reference values given in this report are based on: (a) anatomical and physiological information not published before by the ICRP; (b) recent ICRP publications containing reference value information; and (c) information in Publication 23 that is still considered valid and appropriate for radiation protection purposes. Moving from the past emphasis on 'Reference Man', the new report presents a series of reference values for both male and female subjects of six different ages: newborn, 1 year, 5 years, 10 years, 15 years, and adult. In selecting reference values, the Commission has used data on Western Europeans and North Americans because these populations have been well studied with respect to antomy, body composition, and physiology. When appropriate, comparisons are made between the chosen reference values and data from several Asian populations. The first section of the report provides summary tables of all the anatomical and physiological parameters given as reference values in this publication. These results give a comprehensive view of reference values for an individual as influenced by age and gender. The second section describes characteristics of dosimetric importance for the embryo and fetus. Information is provided on the development of the total body and the timing of appearance and development of the various organ systems. Reference values are provided on the mass of the total body and selected organs and tissues, as well as a number of physiological parameters. The third section deals with reference values of important anatomical and physiological characteristics of reference individuals from birth to adulthood. This section begins with details on the growth and composition of the total body in males and females. It then describes and quantifies anatomical and physiological characteristics of various organ systems and changes in these characteristics during growth, maturity, and pregnancy. Reference values are specified for characteristics of dosimetric importance. The final section gives a brief summary of the elemental composition of individuals. Focusing on the elements of dosimetric importance, information is presented on the body content of 13 elements: calcium, carbon, chloride, hydrogen, iodine, iron, magnesium, nitrogen, oxygen, potassium, sodium, sulphur, and phosphorus.     

基于N型同轴HPGe探测器获取过滤X射线注量谱

构建ISO 4037?1以外的过滤X射线参考辐射需射束注量谱计算平均能量、分辨率和转换系数等参数。为建立过滤X射线注量谱获取方法,采用N型同轴HPGe探测器测量了N?40?N?250窄谱系列过滤X射线参考辐射并得到了脉冲幅度谱,使用Geant4模拟了探测器对放射源的响应并用实测能谱进行了验证,进而建立了响应矩阵,并通过MAXED软件解谱计算得到了射束的注量谱。由解谱所得注量谱计算的空气比释动能到周围剂量当量和个人剂量当量的转换系数与ISO 4037?3推荐值的相对偏差在0?06%?2?55%之间。