【作者】 石会路；

【导师】 庹先国；

【作者基本信息】 成都理工大学 ， 信号与信息处理， 2009， 硕士

【摘要】 随着核技术与辐射技术的迅速发展,民用非核动力中子技术在各个领域已经得到了广泛的应用,如中子测井、中子诱发测井、中子照相、中子治癌、中子活化分析等,在给社会带来巨大利益的同时,也时常发生涉及人员损伤的放射事故。当人体受到中子辐照后,不同能量的中子同人体组织中的元素发生相互作用,所产生的具有一定能量的次级带电粒子能够引起电离和激发,从而使肌体受到损伤,可引起较γ射线更为严重的骨髓造血抑制、出血、感染及免疫功能低下等病症,并易导致早期死亡,后果相当严重。本论文旨在集成先进的核探测、电路设计、信号采集与信息处理等技术,研制开发出便携式高精度的血液中子辐照剂量检测仪,能够快速、准确测量人体受到中子辐照的剂量,为医学临床提供诊断及救治的依据。中子探测一般借助于中子和靶核相互作用所产生的带电粒子实现,部分核素被中子照射后俘获中子而变成放射性核素,测定其放射性活度便可以求得辐照中子剂量。在核事故或中子辐射事故中,中子受照剂量的估算比较困难,当人体受到中子辐照以后,体内元素会发生活化反应,产物具有一定的放射性,通过定性定量的测量该产物放射性可以推断人体受到中子辐照的剂量。目前通过测量人体血液中的钠(23Na)俘获中子后产生的放射性核素24Na的活度是估算中子照射剂量的主要方法。本仪器根据γ射线的探测原理,对受中子辐照的患者血液中24Na衰变产生的γ射线进行定性、定量测量,根据测得的γ射线活度推算患者受到中子辐照剂量。仪器选用NaI(Tl)探测器,探测器中含有前置放大器和高压模块,采用低本底装置屏蔽。硬件设计以嵌入式单片机为控制平台,主要由信号获取模块和主控模块两部分构成。信号获取模块将前置放大器输出的弱信号进行放大,通过整形滤波,然后经过脉冲峰值捕捉与保持,输入到主控模块。在主控模块中,利用微控制器本身自带的高速ADC将模拟电压脉冲信号转换成数字信号并存储,微控制器可以对数据进行分析,实现多道脉冲幅度分析器功能,并将结果在LCD上以谱线的形式显示或者通过USB接口把数据上传给PC机。软件设计包括信号获取模块软件和主控模块软件两部分,信号获取模块软件主要完成测量时间的定时,中断内获取数据并形成谱线,保存数据在本地存储区、通过串口通信软件将数据传输到主控模块等。主控模块软件用于实现人机交互,主要包括菜单部分、谱线显示部分、参数设置窗口以及对信号获取模块的控制,包括通过串口通信传输当前谱线、进行启动、停止测量和设置测量时间等控制。通过系统的软硬件开发,基本实现了对受中子辐照的血液中24Na活度的测定,从而根据24Na活度推算中子辐照剂量。此外该仪器体积小、重量轻、本底低、功耗小、具有良好的人机界面和较高的测量精度。更多还原

【Abstract】 With the development of nuclear technology and radiation technology rapidly,the neutron technology of the civil passive nuclear machinery was extensively applied in various fields such as neutron log, log induced by neutron, neutron photography, neutron carcinogenesis, neutron activation analysis and so on, which bring us enormous benefits,at the same time, lead to radiation accidents with concern for casualties. When people are exposed by neutron, different forms of energy of the neutron are interacted with the element of body tissues, in this process, generates secondary electronics with a specific energy could induced ionization and excitation,which are even more serious than gamma ray, because it could make the body injured or cause bone marrow suppression, hemorrhage, contagion, weakened immune system and so on, which increase the risk of early death, so the consequences is too serious. This paper aims to integrate advanced nuclear detection, circuit design, acquisition of signal and information processing, research and develop a portable, high-precision blood neutron irradiation dose detector.Neutron detection is usually with the help of the charged particle generated with the interaction of neutron with target. Some nuclides turn into radio nuclides by neutron irradiation, we can calculate the dose of neutron by measurement the radioactivity of these radio nuclides. In the accident of nuclear or neutron irradiation, estimation of neutron irradiation dose is difficult, when people are irradiated by neutron, activation reaction take place, the products of the activation reaction are radioactive, through making the qualitative and quantitative measurement of the radioactive of the product can calculate the dose of neutron of the patient. At the present time, the primary method is measureing the activity of radionuclide 24Na, which is generated by 23Na capture of neutron, in the blood of the human body. The instrument according to the principles of gamma ray detection, making the qualitative and quantitative measurement of gamma ray which is generated by 24Na decays that in the blood of the patient who is irradiated by neutron, and then according to the activity of gamma ray to calculate the neutron dose of the patient. This instrument chooses NaI (Tl) detector, which contains preamplifier and high voltage module, is shielded in low-background measurement set. Hardware design take the embedded Single-Chip computer as the control platform, consisted of signal acquisition module and master processor module, signal acquisition module amplify the weak signal from preamplifier, through reshaping and filtering of the signal, and then catching and keeping of the pulse peak, input the signal to the host module, the high-speed ADC of the micro-controller convert analog the voltage pulse signal in to digital signal and then save it. The micro-controller can analyze the data to achieve the function of Multi-Channel Amplitude Analyzer. The result is displayed as spectral line on LCD or uploads to PC by USB. Software design can be divided into two types, signal acquisition module software and master processor module software. Signal acquisition module software is mainly for timing measurement, data acquisition in interrupt time, formation of spectral line, saving the data in local storage, data transmission to master processor module by serial port and so on. Master processor module software is mainly for interaction between man and machine, which contain menu, spectral line display, windows of parameter setting and master processor module controlling, which contain spectral line transmission by serial port,starting and stopping of the measurement, setting the measuring time and so on.Through the system’s software and hardware design, On the whole the instrument has basically access to measure the activity of 24Na in the blood of the patient who is irradiated by neutron,and then calculate the neutron dose. In addition, it is small in size, light in weight, low background, low power consumption it also has good human-computer interface and high precision.更多还原