Estimating internal dose coefficients of short-lived radionuclides in accordance with ICRP 2007 recommendations

For radiation protection in high-energy accelerator facilities, internal dose coefficients of short-lived radionuclides were estimated using the dosimetric methodology in accordance with the International Commission on Radiological Protection (ICRP) 2007 Recommendations. A computational program was developed for estimating the dose coefficients. The program was verified by confirming whether it could reproduce the dose coefficients provided by ICRP for intakes of representative radionuclides. In addition, the estimated dose coefficients of short-lived radionuclides were compared to the values generated by Dose and risk CALculation software (DCAL), which is based on a dosimetric methodology that is in accordance with the ICRP 1990 Recommendations, to discuss the reasons why the dose coefficients were changed by the revision of the dosimetric methodologies. The comparison revealed a decreasing trend of dose coefficients in the case of inhalation upon revision of the dosimetric methodologies. By contrast, in the case of ingestion, the dose coefficients tended to increase.     

基于蒙特卡罗方法的航空机组人员辐射剂量评估北大核心CSCD

采用辐射仿真人体面元模型和数字化飞机模型,基于蒙特卡罗方法开展了航空机组人员的航空辐射剂量研究。选取昆明至北京航线为例,评估了航空机组人员在该航线飞行时受到的航空辐射有效剂量率,分析了人体参数对航空辐射有效剂量率的影响,并探索了航线参数变化时机组人员受到的航空辐射有效剂量率的变化。结果表明,机组人员在昆明至北京航线受到的航空辐射有效剂量率为2.114μSv/h,基于中国人参考生理特征的体模和高加索人体参数体模的有效剂量率评估结果差异为25.3%;航线参数中航线的高度是最主要的影响因素,14 km飞行高度的航空辐射有效剂量率达到10 km高度时的1.8倍,同时,航线纬度升高时,机组人员受到的航空辐射有效剂量率也会产生显著的提升。该研究对航空机组人员的辐射剂量评估具有一定的参考和指导意义。     

New Technical Approach to Monitoring of Low-Level Environmental Gamma Radiation Using NaX(Tl) Scintillation Instrument

The environmental dose evaluation around a nuclear facility is usually performed by means of calculational methods on the basis of effluent monitoring at a release point. It has been desired to develop practical techniques of direct monitoring in the environment, because the Japan Atomic Energy Commission set up 5 mrem/yr as an objective dose value for the whole-body exposure due to normal operation of LWRs on a single site.

In evaluating gaseous plume doses less than 5 mrem/yr in routine monitoring, there are many difficult problems to be solved. We have developed two techniques for separation of the plume exposures less than 1 mrem/yr from the background radiation, using a NaI(Tl) scintillation counter having flat energy response.

One technique is based on the difference in energy spectrum distribution between plume gamma and natural gamma radiation. And, separation of the respective exposures is made by analysis of the two informations obtained by a two-channel monitoring system. Another technique is to reduce the natural gamma radiation components by using a special concave lead shield for the NaI(Tl) scintillation probe. A combination of the techniques can much improve the efficiency of separation of ⁴¹Ar plume radiation from fluctuating background radiation.     

Sex-Specific per capita Dose due to Background Radiation in Japan

The collective dose due to the background radiation outdoors in Japan was analyzed, and the influence of the time trend of the population movement on the per capita dose was estimated. Only the external dose was considered. It was previously shown that the per capita dose calculated for each year between 1952 and 1980 by the use of the surveyed background levels along with the registered population data has been decreasing continuously. In this work, the latest data in 1981 was added, and male and female statistics were processed separately. The result showed that the male values of the per capita dose have been always lower than the female values, if the deficit is small. It was also shown previously that the prevailing population movement from countryside toward urban areas (often plains of volcanic ash) would be the cause which have changed the per capita dose, i.e. population-weighted mean dose of the whole country. In this work, it was anticipated that the gross population movement from the South-West toward the North-East Japan would be another cause of the decrease.     

L3000型电子直线加速器屋顶厚度的最优化计算

使用具有角分布Ｘ射线辐射源的屋顶厚度计算方法计算出Ｌ３０００型９ＭｅＶ电子直线加速器产生的Ｘ射线所需的最优化的屋顶屏蔽厚度为３０ｃｍ。竣工后检测,天空回散照射的剂量当量率为本底水平,达到了合理的尽量低的水平。     

辐射加工级电子束量热计设计

为设计一种可以用于测量辐射加工级电子束吸收剂量的量热计,采用高纯石墨为吸收体,发泡聚苯乙烯（EPS）为绝热层材料,结合MCNP吸收剂量模拟结果设计各个部分的结构,利用ANSYS模拟分析软件进行热分析,确定各个部分的具体尺寸。以此量热计为基础,在某公司的10 MeV电子加速器下进行实验,采用microK250高精密测温电桥测量电阻阻值,获得10 MeV标称能量下的电子束吸收剂量的测量结果,得到吸收体被照射时间变化与吸收剂量的比例关系。探讨量热计准确性的影响因素,在能量为10 MeV时测量电子束吸收剂量的总不确定度为1.43,本研究结果可为辐射加工级电子束的吸收剂量测量提供参考。     

电子元器件总剂量辐照在线测试系统及其应用

本文对一种由计算机自动控制并进行数据采集的电子元器件总剂量辐照现场测试系统进行了描述，并通过应用该系统对ＣＭＯＳ数字电路ＣＣ４０６９进行与总剂量辐射同步的电参数在线测量，以及辐照后退火数据的快速采集，研究了ＣＭＯＳ数字电路总剂量辐照在响应特性和辐照后快速时间退火效应。     

~(99m)Tc诊断过程中辐射场特征及其源强测量

为了掌握~(99m)Tc诊断全过程中所产生辐射场特征和源强,利用HPGeγ谱仪及其无源效率刻度技术,分析了99Mo和~(99m)Tc发射的主要γ射线对辐射场的贡献。使用主动测量和被动测量相结合的方式,测量了~(99m)Tc诊断过程中各个操作环节中的辐射源强。实验结果表明:99Mo-~(99m)Tc发生器淋洗前、后主要的γ射线发射率之比变化较大;随着距离的增加,99Mo-~(99m)Tc发生器、注射器和病人表面的γ辐射空气吸收剂量率快速衰减;~(99m)Tc诊断一天,放射性药品操作人员手部剂量达到0.41 m Sv。     

二醋酸纤维素薄膜剂量计的制备和性能研究

为了改善醋酸纤维素薄膜剂量计在γ辐射剂量测定中稳定性欠佳的问题，拓展其辐射测量应用范围，采用离子液体均相乙酰化纤维素方法制得的二醋酸纤维素（CDA）粉末为原料，优化CDA薄膜制备工艺，研究其γ辐射变色性能及稳定性，制备适用于γ辐射剂量测量且性能优良的CDA薄膜剂量计。基于CDA的辐射变色机理，该薄膜剂量计在270 nm的单位厚度吸光度与吸收剂量存在良好的线性关系，剂量率、CDA的取代度和辐照气氛对薄膜的工作曲线影响较小。CDA薄膜剂量计的剂量检测量程为50~400 kGy，扩展不确定度为8.8%（K=2），辐照后24 h内吸光度测试稳定，具有良好的辐照稳定性，基本满足工业上对于辐射剂量计的使用要求，有望应用于γ辐射剂量的测量。     

高气压组织等效电离室用于混合辐射场测量的实验研究

介绍了基于复合理论的组织等效电离室的设计原理,利用该原理设计的区域中子、γ剂量当量仪可使用1个探头间接测量周围剂量当量、吸收剂量和品质因子。利用加速器和标准辐射场对该装置进行测试,测试结果表明,该装置对于中子和γ辐射场,尤其是对于高能γ、热能至几十MeV的中子具有较好的能量响应和较高的灵敏度,在剂量率高于几十μSv/h时,测量不确定度可控制在±50%以内。该系统可为存在中子、γ辐射场的场所提供必要的测量手段和监控技术。     

0.18 μm MOS差分对管总剂量失配效应研究

为明确深亚微米MOS差分对管在电离辐射环境下晶体管失配表征方法及损伤机理,本文针对0.18 μm NMOS、PMOS差分对管,进行了⁶⁰Co γ总剂量辐射效应研究。研究结果表明：与PMOS差分对管相比,NMOS差分对管对总剂量辐照更敏感,主要表现在：1) 辐照引起NMOS差分对管转移特征曲线失配增加;2) NMOS差分对管阈值电压失配随辐照总剂量的增加而增大;3) 栅极电流辐照后稍有增加,失配随栅极电压的增加而增大。而PMOS差分对管在整个辐照过程中,无论是曲线还是参数均未出现明显变化,且失配亦未随辐照总剂量的增加而增大。     

外照射个人剂量监测的测量不确定度评定

外照射个人剂量监测数据可作为放射性工作人员受到的职业照射剂量证明,具有法律效力,因此监测数据的准确可靠尤为重要。中核核电运行管理有限公司个人剂量监测中心于2017年先后取得中国计量认证(CMA)认证和放射卫生技术服务机构资质认证双资质,除了中心内部质量保证措施外,还定期参加年度全国放射卫生技术机构检测能力考核。文章基于2019年考核实验结果(合格)进行了数据分析以及测量不确定度评定,各实验组测量结果的相对扩展不确定度均在10%以内,中心外照射监测系统性能良好,确保了监测数据的准确性和可靠性。     

主动式电离辐射剂量仪的脉冲X射线响应特性研究

国际上对于辐射防护剂量学的研究主要针对连续辐射,然而脉冲式电离辐射在工业探伤、X射线诊断、闪光X射线照相技术、安检和科研等领域中得到了广泛应用。主动式电离辐射剂量仪采用稳态辐射场进行刻度,难以准确测量短脉冲、高剂量率的脉冲式电离辐射。为了解主动式电离辐射剂量仪的脉冲响应特性,基于毫秒级脉冲X射线机搭建脉冲X射线参考辐射场,针对常用4款主动式剂量仪开展脉冲X射线响应特性测试。测试结果表明,目前常用4款主动式剂量仪均不适用于短脉冲、高剂量率辐射场的剂量测量和预警。     

掺杂型羟基磷灰石剂量学性能研究进展

电离辐射可在掺杂型羟基磷灰石中诱发自由基,利用电子自旋共振(ESR)技术检测自由基含量,可以进行辐射剂量测量。本文介绍掺杂型羟基磷灰石的剂量学特性及其研究现状,分析讨论其作为新型辐射剂量计材料的可行性。     

Data analysis of dose map verification for IMRT

In this paper we analyze the results of dose map verifications for patient's IMRT (Intensity-modulated radiation therapy) plans and study the factors that may influence the accuracy of verification.MapCHECK,a two-dimensional diode array,was used to measure the dose maps for 1242 plans (14540 fields) from May 2004 to August 2008.The plans were designed with Pinnacle3 planning system.The passing rate of beams was determined when the acceptance criterion was 2%/2 mm,3%/3 mm and 4%/4 mm.And the data with 3%/3 mm criteria was analyzed in more detail.The considered factors were beam modeling,optimization mode and treatment site.The median passing rate of total fields was 93.5%,98.8%,and 100% when the acceptance criterion was 2%/2 mm,3%/3 mm and 4%/4 mm,and the interquartile range were 11.1%,3.8%,and 1.3%,respectively.The results of direct machine parameter optimization (DMPO) planning mode was better than those of multiple-step mode and beam modeling of new accelerators was better than that of old accelerators.These indicate that beam modeling is the key point of improving passing rate of IMRT verification and the influence of treatment site was little.The factors,the total number of segments,minimum area of segments and minimum monitor unit (MU) of segments,also influence the dosimetric accuracy of IMRT plan verification.     

Ionization radiation induced degradation of MOSFET channelfrequency response

A model is presented for the frequency response degradation of metal-oxide-semiconductor field-effect transistors (MOSFETs) exposed to ionizing radiation. It is shown that response degradation can be predicted by monitoring a single parameter, the gate-to-channel time-constant τ_GC, which is highly sensitive to the density of interface traps at the silicon-insulator interface. The value of τ_GC and its degradation with radiation dose are directly obtained by measuring the small signal impedance of a MOSFET. The measurement technique used enables the extraction of effective mobility of the inversion layer. Frequency response characteristics of two types of MOSFETs, fabricated using two different gate-insulator technologies and exposed to a total dose of 1 Mrad (Si), are compared     

同步辐射X射线小角散射溶液样品蠕动实验装置的研制

研制了用于同步辐射X射线小角散射实验的溶液样品蠕动实验装置,其主要特点为可有效抑制X射线对溶液样品的辐射损伤、密封性能好、操作简便,且背景散射低、消耗样品量小,还可根据实验要求实现对样品温度的控制,进行变温原位测量。此外,通过实验对该装置的进样量和蠕动速度进行了标定,对防辐射损伤效果进行了验证。结果表明,该装置控制精度高,并可有效减小X射线在测量过程中对样品的辐射损伤。     

线性集成电路的辐照响应和电离辐射损伤评估

利用用于电离辐射效应研究的运算放大器计算机测试系统以及测试分析和数据处理软件对十几种运算放大器进行了~(60)Coγ射线、1.5MeV电子的电离辐射损伤试验及其室温和加温退火特性研究。同时,探讨了运算放大器电离辐射损伤水平的评估方法和损伤机制。     

人体内O-(2-18F-氟代乙基)-L-酪氨酸辐射吸收剂量的估算

为评估人体内O-(2-^18F-氟代乙基)-L-酪氨酸(FET)吸收剂量，选择小鼠作为模型。由小鼠尾静脉注射FET后，在10、30、60、120和180min时处死动物，测定小鼠体内各脏器放射性分布，换算至标准人体内分布数据，按标准医学内照射吸收剂量(MIRD)计算法，估算人体内FET辐射吸收剂量。结果表明：人体骨内照射吸收剂量最高，其值为4．78pGy／Bq，脑和全身内照射吸收剂量最低，约为1．6pGy／Bq，其它脏器内照射吸收剂量为1．6～3．5pGy／Bq，有效剂量为9．0pSv／Bq。按一次静脉注射FET注射液370MBq估算，有效剂量为3．3mSv，其值处在常规核医学研究中可接受的有效剂量范围之内。     

低放辐照工程退役的辐射环境监测

采用室内外X-γ剂量率、室内β表面污染水平、样品取样及活度浓度分析等方法对某地需退役的低放辐照工程的辐照室、废物坑、废水池及其周边土壤进行辐射监测。结果表明:室外γ剂量率平均值为118.1 nGy/h,扣除宇宙射线本底后水平正常,属环境本底范围;室内γ剂量率平均值为259.9nGy/h,明显高于室外水平,且高值热点区域呈东北向展布;土壤取样结果呈现出核素在浅层土壤中富集、深层无明显异常的特征;水池中水体~(60)Co高异常为地下水管破裂导致,~(60)Co随水体沉积于池底底泥中。