【作者】 成杰；

【导师】 谢向东；

【作者基本信息】 中国人民解放军军事医学科学院 ， 辐射防护与环境保护， 2011， 硕士

【摘要】 目的核与辐射突发事件发生后,快速确定人员的受照剂量,为后续的分类、诊断、治疗提供剂量学数据,是核医学救援的首要任务。在常见射线剂量测量中,中子剂量难于测量,是核与辐射医学应急救援研究的热点和难点。本文旨在建立一套能够快速准确测量人体受照中子剂量的技术方法,并开发相应的标准测量装置。方法测量人体血液中的元素23Na被热中子活化生成的放射性同位素24Na衰变时的γ光子数,使用比活度——中子剂量的转换系数估算人体受照剂量,提出多个影响剂量估算的因素,对直接使用剂量转换系数获得的剂量进行校正。结果在模拟实验中,使用NaI探测器对血液样品进行测量,获得了24Na的含有本底的特征峰和去本底的特征峰。通过解谱降低本底中40K能量为1.461MeV的γ峰的干扰,得出采集的3mL血样的绝对活度为14.8Bq。在使用ORNL提供的比活度——剂量转换系数进行计算后,得出其剂量为1.94~2.82Gy。结论本课题围绕人体受中子照射后,采用测量活化血液的方法来估算人体中子剂量,具体研究内容如下:1.分析了中子照射后人体剂量估算的技术环节,总结出一套完整的人体剂量估算方法。2.总结归纳出适用于核医学应急救援条件下的中子剂量标准测量流程。3.通过对比活度——中子剂量转换系数和影响因素进行分析,总结出主要的影响因素,提出修正的技术方法和思路,对其中的5个影响因素给出了修正值或表格数据。4.进行了便携式血液中子辐照剂量检测仪研发的模拟实验,检验该测量方法从设计思路到测量技术的可行性。5.研制出了一套便携式血液中子辐照剂量检测仪。对研发配套的血钠测量仪提出改良意见。一是仪器的屏蔽室对便携性影响太大,二是剂量转换系数的积累还不够,需要针对研发的仪器进行实验,积累与该仪器完全匹配、多条件下的剂量转换数据。本文规范了中子剂量的测量流程,利用该测量流程可在现场实现快速标准化测量;开发了一套便携式中子剂量测量仪,并对仪器进行了调试实验。更多还原

【Abstract】 Objective The chief task of medical rescue against nuclear accidents is to determine the exposure radiation dose so as to collect dosimetry data efficiently for the following classification, diagnosis and medical treatment. During the common process of determining the radiation dose, it is difficult to measure the neutron dose, which becomes the hotspot and difficult point of nuclear and radiation medical emergency rescue research. This paper aims to build a set of technical methods which can measure the exposure neutron dose of human body precisely and quickly, as well as to develop a set of measuring device.Method The isotope of 23Na contained in the human blood will becomes the radioactive isotope 24Na through capturing thermo neutrons. The quantity of gamma photons emitted by the decay of 24Na is measured,then is converted to the activity. A rough estimation of the exposure radiation dose can be estimated by using the specific activity-neutron dose coefficient. A multiple of factors that affect the dose estimation are analysed , and are used to correct the neutron dose.Results In simulating experiments, by measuring the blood samples with the NaI detector, both the characteristic peak with and without background of 24Na are found. After reducing the interference of theγpeak of 1.461MeV 40K from the background, it is found that the absolute activity of the collected 3mL blood samples is 14.8Bq. After using the effective activity, the dose transfer coefficient, provided by ORNL in the calculation, it founds that the dose is 1.94~2.82Gy.Conclusion This paper focuses on the method of estimating the neutron dose of human body after exposing to neutron radiation by measuring the activatory blood. The following are the details:1. It analyzes the technical process of human neutron radiation dose estimation after exposure, summarizing a whole method for human dose estimation.2. It concludes a standard neutron dose measuring flow for nuclear medical emergency rescue.3. By analyzing the effective activity-neutron dose transfer coefficient and the influencing factors, the chief effecting factors are found, and the regulating technical method and theory are suggested. Five factors are provided with correcting value or data.4. Simulating experiments on developing the portable blood neutron radiation dose inspection device is made. And the feasibility of its design principle and measuring technology are verified.5. A set of portable blood neutron radiation dose measuring device is developed. Two improving advices for the development of blood-contained Na measuring device are pointed out. One is that the shielding room has great influence on the portability of the device, and the other is that the available dose transfer coefficient data is not enough, and more experiments should be done on the development of devices and more related dose transfer data in different situations should be cumulated.This paper aims to regulate the neutron dose measuring flow, with which a quick standard measurement can be achieved in the site scene of an accident; meanwhile, a set of portable neutron dose measuring devices are developed and related adjustment experiments are made.更多还原