目的 解决LiF:Mg,Cu,P热释光剂量计20～50 keV区域能量响应过高问题,改善热释光剂量计的能量响应,提高其测量精度.方法 通过在热释光片前设置补偿滤片,减少20～50 keV X/γ射线在热释光片的能量沉积,降低该能量区域的能量响应.结合实验测量现有BIRM?1000型LiF:Mg,Cu,P热释光剂量计性能参数,使用蒙特卡罗方法模拟计算改进后的热释光剂量计能量响应.结果 在热释光片前加装厚度0.6 mm带孔304不锈钢片,光片后加装厚度10 mm金属铍片,可降低热释光剂量计在20～50 keV区域能量响应,此时的热释光剂量计的探测阈值≤1.31×10?4 mGy,方向性差异<7％.结论 在热释光片前加装0.6 mm带孔304不锈钢片,可有效改善LiF:Mg,Cu,P热释光剂量计能量响应曲线,提高其测量精度.

There are differences and inconsistencies to some degree in the radioactive contamination control level of personnel′s body surface availiable in many national standards, thus puzzling the users. Therefore, it is proposed to compare the applicable scope, conditions and differences between relevant national standards, and combine with similar clinical nuclear medicine standards of radiological protection content to presevent recommendations on the contamination control level that should be correctly applied in an event of nuclear and radiological emergency. Based on the discussion of similar standards, the contaminated personnel with α of 0.04-10 Bq/cm 2 and β of 0.4-100 Bq/cm 2 are advised to be treated in the institutions with higher than secondary medical insititution. Both α econtamination control levels less than 0.04 Bq/cm 2 and β levels less than 0.4 Bq/cm 2 could be achivable, if fully decontaminated.

获得外照射条件下的大鼠器官剂量,对于放射医学剂量-效应关系研究具有重要意义.本文基于大鼠微型CT图像建立大鼠体素模型,并研究光子外照射情况下大鼠器官剂量.大鼠体素模型质量323.7 g,单个体素尺寸为0.16 mm×0.16 mm×2 mm,包含大鼠大部分关键器官和组织.利用蒙特卡罗模拟程序MCNP计算获得了4种照射几何条件、21个单能(10 keV～10 MeV)平行光子束外照射情况下的器官剂量转换系数,最后对器官剂量随光子能量的变化进行了分析与讨论.

目的 了解某设备实验条件下不同位置脉冲X射线电离辐射水平,提出适当的防护建议.方法 采用热释光测量方法,分别在设备舱周围不同方向不同距离布放热释光剂量计,累积一定数量脉冲辐射后进行测量;采用电离室型X、γ剂量率仪(FJ-347A)实时测量工作状态下不同距离处电离辐射剂量率水平.依据《电离辐射防护与辐射源安全基本标准》(GB 18871-2002)规定的职业照射人员和公众个人剂量限值提出不同工作位辐射防护建议.结果 热释光剂量计累计接收3 000个脉冲辐射,设备舱外壁0.01～8.98 mGy,项部0.01～15.67 mGy,距外壁1～12m之间0.01～2.18 mGy,工作位0 mGy.工作状态下,X射线剂量率仪测得距设备舱外侧壁1～20 m之间空气比释动能率范围0.26～16 mGy/h.结论 热释光剂量计、电离室型剂量率仪测量结果基本一致,说明两种方法均可用于脉冲X射线测量;工作状态下设备舱外近距离处辐射剂量率较高,可通过采取防护措施或者限制人员工作量以满足辐射防护要求.

目的 为了研究便携式探测器是否可用于核事故现场内污染的快速筛查,需要对肺计数探测器的探头类型、探测效率、探测灵敏度、测量距离等技术参数与测量方法进行预先理论研究.方法 利用蒙特卡罗粒子输运模拟程序(Monte Carlo N-particle code,MCNP),建立包含肺组织的简易躯干数学模型,将均匀分布在肺组织的典型放射性核素作为模拟辐射源,模拟计算高纯锗(high purity germanium,HPGe)和碘化钠[NaI(Tl)]两种探测器在不同胸壁厚度、不同测量距离下的探测效率,计算探测器的最小可探测活度,即探测灵敏度,通过比较分析,了解适用于现场便携式内污染计数器的技术参数与测量方法.结果 计算获得了典型核素内照射情况下两种探测器的探测效率和最小可探测活度.结论 初步确定了现场内污染肺计数器的关键技术参数和测量规律,便携式探测器可用于核事故现场内污染的快速筛查.

A newly voxel rat model was developed from Micro-CT images of a rat to study rat organ dose for external photon irradiation. The voxel model with voxel size of 0.16 × 0.16 × 2 mm3 weighed about 323 g and contained most of the key organs or tissues. Monte Carlo N-particle code (MCNP) version 4C was utilized to calculate organ dose conversion coefficients for 21 external monoenergetic parallel photon beams between 10 keV and 10 MeV under four different irradiation geometries conditions (left lateral, right lateral, dorsal-ventral, ventral-dorsal). The calculated organ dose conversion coefficients were presented in tables and compared with published data based on a mouse model to investigate the effect of size and weight difference on organ dose. The calculated and comparison results show that the organ dose conversion for both mouse model and rat model exhibited similar energy dependence under the four ideal irradiation geometries, and the organ dose is sensitive to size and weight difference especially at photon energy below 0.1 MeV and above 2 MeV.

目的 利用RNA免疫沉淀技术和深度测序方法寻找人骨肉瘤细胞U2OS中与DNA依赖蛋白激酶催化亚单位(DNA-PKcs)蛋白结合的RNA,进一步研究特定RNA的功能.方法 提取对照组及8 Gy剂量照射组的U2OS细胞核蛋白,选择DNA-PKcs蛋白进行免疫沉淀,将复合体中RNA分离纯化并进行鉴定,行高通量测序分析.通过生物信息学分析得到与DNA-PKcs蛋白结合的所有RNA种类和染色体分布,KEGG和GO分析得到RNA的功能分类.最后选取特定RNA分子,利用qRT-PCR方法分别对U2OS细胞总RNA及RIP提取的RNA进行表达验证.结果 U2OS细胞经8 Gy照射后DNA-PKcs蛋白结合的RNA与对照组相比,与细胞黏附相关的基因:整合素α3(integrinα3,ITGA3)、α5(ITGA5)和αV(ITGAV),以及白细胞分化抗原分化簇44(cluster of differentiation44,CD44)和多配体聚糖4(syndecan 4,SDC4)均有更强的富集.结论 成功获得了与U2OS细胞DNA-PKcs蛋白结合的RNA高通量测序库;通过测序寻找到了DNA-PKcs蛋白结合的特定RNA分子,为下一步研究其功能奠定了基础.

PURPOSE:Intracellular electroporation occurs when the cells are exposed to nanosecond pulsed electric field (nsPEF). It is believed the electroporation (formation and extension of pores on the membrane induced by external electric field) is affected significantly by the transmembrane potential. This paper analyzed transmembrane potential induced by nsPEF in the term of pulse frequency spectrum, aiming to provide a theoretical explanation to intracellular bio-effects.METHODS:Based on the double-shelled spherical cell model, the frequency dependence of transmembrane potential was obtained by solving Laplace's equation, while the time course of transmembrane potential was obtained by a method combined with discrete Fourier transform and Laplace transform. First-order Debye equation was used to describe the dielectric relaxation of the cell medium.RESULTS:Frequency-domain analysis showed that when the electric field frequency was higher than 105 Hz, the transmembrane potential on the organelle membrane (ΔΦo) was increasing to exceed the transmembrane potential on the cellular membrane (ΔΦc). In the time-domain analysis, transmembrane potentials induced by four nsPEF (short trapezoid, long trapezoid, bipolar and sine shapes) with the same field strength were compared with each other. It showed that ΔΦo is obviously larger than ΔΦc if the curve of the normalized frequency spectrum of the pulse is more similar with the curve of normalized ΔΦo in frequency domain. Pulses with major frequency components higher than 108 Hz lead to both small ΔΦo and ΔΦc. This may explain why high power pulsed microwave lead to unobvious bio-effects of cells than nsPEF with trapezoid form.CONCLUSION:Through the pulse frequency spectrum it is clearer to understand the relationship between nsPEF and the transmembrane potential.

目的 计算和测量医用诊断X射线与物质相互作用的能量及强度变化规律,研究其防护措施.方法 根据X射线变化规律,计算直射线、散射线与透射线的能谱分布,分析并实验测量不同物质对X射线的屏蔽效果.结果X射线经物质衰减后,强度变低,平均能量提高,能谱变窄;散射线能量和强度都小于直射线.不同物质对X射线屏蔽效果不同.结论 铅是防护医用诊断X射线的理想材料.

A set of fluence-to-dose conversion coefficients has been calculated for neutrons with energies <20 MeV using a developed voxel mouse model and Monte Carlo N-particle code (MCNP), for the purpose of neutron radiation effect evaluation. The calculation used 37 monodirectional monoenergetic neutron beams in the energy range 10−9MeV to 20 MeV, under five different source irradiation configurations: l...

The power absorbed by the human brain has possible implications in the study of the central nervous system-related biological effects of electromagnetic fields. In order to determine the specific absorption rate (SAR) of radio frequency (RF) waves in the human brain, and to investigate the effects of geometry and polarisation on SAR value, the finite-difference time-domain method was applied for the SAR computation. An anatomically realistic model scaled to a height of 1.70 m and a mass of 63 kg was selected, which included 14 million voxels segmented into 39 tissue types. The results suggested that high SAR values were found in the brain, i.e. ∼250 MHz for vertical polarisation and 900-1200 MHz both for vertical and horizontal polarisation, which may be the result of head resonance at these frequencies.

Objective To calculate the electric field intensity and transmembrane voltage of spherical cells and ellipsoi -dal red blood cells ( RBC) in an extremely low frequency electromagnetic field .Through this calculation , we can provide reference to the search for interaction targets and mechanics between the extremely low frequency electromagnetic field and organisms.Methods The Finite Element Method was used in the numerical computation for the spherical cell model and the ellipsoidal RBC model .Results The electric field intensity of the two types of cells on the cellular membrane was both significantly higher than the applied electric field strength , and the values of the induced field strength and transmembrane voltage varied with the direction of the electric field periodically .Conclusion The cell shape and direction of the applied electric field are not the main determinants of the cellular membrane electric field intensity and the transmembrane voltage compared with electromagnetic parameters .The distribution of the electric field intensity and transmembrane voltage are re-lated to the direction of the applied electric field.

超大城市是指市区非农业人口超过200万人的特大城市，如上海、北京等。

重大活动是指具有特定规模的政治、经济、文化、体育及其他重大社会活动。核与辐射突发事件是指突然发生的，由放射性物质或其他放射源造成或可能造成严重影响公众健康的紧急事件。核与辐射突发事件主要包括：核与辐射事故和核与辐射恐怖袭击两大类型。重大活动中的核与辐射突发事件以核恐怖袭击为主。

上海世博会三防医学应急救援保障中，由3个单位抽组人员组成三防医学救援队，分别为三防主力队，专家组，医疗救治组。由于人员数量偏少，核化救援分队的各组人员共用。辐射侦检组由1名辐射专业人员和1名防化专业人员组成。当执行辐射应急时，主要由辐射专业人员主持侦检工作，另1名成员作风速、风向测量及记录数据等配合工作。

<正>中子照射事故中,人体受照剂量的测量方法是核科学中一个重要的研究课题。笔者介绍了国内外临界事故中人体受中子照射的剂量估算方法,重点阐述了24Na活度的测量方法。由于研究人员对辐射类型、中子源能谱、辐射入射角、人与辐射源之间屏蔽物的厚度、受照期间人体在辐射场中的取向及人体与辐射源的相对距离等影响受照剂量的因素认识不同,修正因子的取值差异较大,使得估算结果和实际结果相差超过50%。文章对这些因素作了描述。

本文系统介绍了60年来军事医学科学院放射与辐射医学研究所从防原医学至放射与辐射医学研究各个阶段辐射剂量学研究的主要情况,包括核试验剂量保证、生物效应照射实验条件及剂量学方法的建立、事故照射剂量重建技术、辐射防护学及其剂量评价、医疗和诊断剂量学、辐射加工剂量及辐照工艺、辐射剂量测量技术、核设施事故剂量学、辐射剂量标准、微波剂量学等所获得的成果和经验,在此基础上,对该所辐射剂量学发展方向和研究重点进行了分析和论述.

目的 在意外中子照射情况下,研究人体受到的中子照射剂量与固定测最条件下的计数率的关系.方法 测量人体血液中的元素23Na在热中子活化作用下生成的放射性同位素24Na衰变时的γ光子计数来估算人体受照剂量.结果 在获得的血液样品的γ谱中,能够清晰地获得24Na的含有本底的特征峰和去本底的特征峰,通过解谱可降低本底中40K的1.461MeV的γ峰的干扰,其计数不确定度均小于10%.结论 简化了测量步骤,提高了测量速度,适用于快速为中子受照人员的医学救治提供具有较高可信度的剂量学数据.

A set of conversion coefficients from kerma free-in-air to the organ absorbed dose for external photon beams from 10 keV to 10 MeV are presented based on a newly developed voxel mouse model, for the purpose of radiation effect evaluation. The voxel mouse model was developed from colour images of successive cryosections of a normal nude male mouse, in which 14 organs or tissues were segmented manually and filled with different colours, while each colour was tagged by a specific ID number for implementation of mouse model in Monte Carlo N-particle code (MCNP). Monte Carlo simulation with MCNP was carried out to obtain organ dose conversion coefficients for 22 external monoenergetic photon beams between 10 keV and 10 MeV under five different irradiation geometries conditions (left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic). Organ dose conversion coefficients were presented in tables and compared with the published data based on a rat model to investigate the effect of body size and weight on the organ dose. The calculated and comparison results show that the organ dose conversion coefficients varying the photon energy exhibits similar trend for most organs except for the bone and skin, and the organ dose is sensitive to body size and weight at a photon energy approximately <0.1 MeV.

Objective To construct a voxel mouse model combining with Monte Carlo method used for radiation dose calculation.Methods A set of slice images obtained from a nude male mouse (28 g) was utilized,all slice images were registered,some organs or tissues were identified,segmented and filled with specific color,and finally the physical property was defined by MCNP application.Results A mouse model with a voxel size of 0.2 mm×0.2 mm×0.2 mm,consisting of 14 organs or tissues,was constructed,which could satisfy the requirement of precision for radiation dose distribution calculation and moderate computing time.Conclusion The voxel mouse model can be used to calculate the quantity of ionization radiation dosimetry in related areas including radiological medicine,nuclear medicine and space radiation medicine.