便携式康普顿背散射成像仪研究

【作者】 吴建中；

【导师】 顾大强；

【作者基本信息】 浙江大学 ， 机械设计及理论， 2003， 硕士

【摘要】 康普顿背散射(Compton Back-scattering)技术是一种新型的无损检测技术。其突出的优点是：射线源与检测器可置于被检测物体的同一侧，能够解决透射式CT所无法解决的一些无损检测问题。但该技术存在一些不足之处，主要是背散射信号微弱，检测困难。而目前世界上对康普顿背散射的应用研究基本上限于高能CT，装置的体积大、重量重，无法应用于需要便携式的场合；同时康普顿背散射技术的应用尚缺乏成熟的理论指导。 本文的主要内容包括： 1．综合国内外的有关文献，对康普顿背散射技术的研究现状进行评述。详细地阐述了康普顿背散射的概念，系统地阐述了γ射线康普顿背散射技术的应用理论基础。 2．针对墙体检测这个实际问题，在必要的理论分析计算基础上，提出了康普顿背散射成像仪的总体设计方案。其主要内容包括入射源的选择，散射粒子的理论计算，发现异物的最低条件计算以及系统的一些重要参数的确定，主要包括：γ放射源的选择，散射角的确定，后准直器的形状与尺寸，前准直器的尺寸，前准直孔的大小，检测器的种类与型号，检测器的效率等。 3．根据需要自行设计了一种新型的安全的源容器。其特点是工作的各准直孔径位置和安全位置可通过计算机控制自动进行切换，使用灵活、方便、安全，以满足我们多种检测的需要。针对所选择的辐射源和该源容器作辐射安全的检测、分析和评估，包括源容器的包装的达标情况，以及当源容器处于工作状态时辐射工作人员的累积剂量情况。制订了源容器的操作规范及管理措施。 4．进行了康普顿背散射成像仪的探测采传系统设计。介绍了闪烁计数管探测器的工作原理。提出了考核该系统性能的重要指标及考核的具体方法。主要内容包括：探测器GDB坪曲线的考核，探测器能量分辨率的考核，探测器探测效率的考核，高压稳定性考核，电压变化与道位关系的考核，多道能量的标定，模数变换器输出稳定性考核，甑别器阈值稳定性的考核，软硬件卡阈一致性的考核，本底谱的考核，探测采传系统电子学噪声考核，电磁兼容性的考核，接地电阻考核和预热时间的选定。 5.进行了康普顿背散射成像仪的自动控制系统设计。明确指出了该子系统的控制对象，阐述了控制的原理，根据工作要求确定电机及驱动模块的型号。论述了该系统的性能特点与技术指标。 6.进行了康普顿背散射成像仪的应用软件设计。指明了本应用软件的功能，主要是控制三维扫描运动和源的工作位置、数据采集和处理以及文件管理和帮助等;给出了程序结构模块，从中列出了软件所含的主要目录;给出了几个主要的程序模块的界面，简要说明了界面中各操作对象的含义。 7.研制成功了具有自主知识产权的便携式康普顿背散射成像仪，经实验及现场试用，其性能达到设计目标的要求，该仪器在工程、军事、公安、海关等领域中有较广阔的应用前景。更多还原

【Abstract】 Compton Back-Scattering is a new type of non-destructive inspection technology. Its best advantage is that the radiation source and the detector can be positioned in the same one side of the object being inspected. It can resolve some difficulties of non-destructive inspection that TICT can’t do. Mainly its disadvantage is that the back-scattering beam is very weak, that the signal-to-noise ratio is lower. Recently the research of Compton Back-scattering in the world is belonged to high energy CT. The device is very big, much heavy, isn’t suitable to the portable use. In the same time, up to now there isn’t a complete application theory of Compton Back-Scattering.The main contents of the thesis are as follows:1. Synthetically evaluate the latest application case of Compton Back-scattering according to the papers at home and aboard. Describe the concept and the application theory of Compton Back-scattering in detail.2. Do some necessary calculations and decide on the general scheme of Compton Back-Scattering Imaging Scanner to the real wall inspection. Include the selection of radioactive source, the calculation of Compton Back-scattering beam, the calculation of the basic condition of finding out the different materials and the determination of some important parameters as well.3. Design a new kind of safe shielding container of radioactive source. Its feature is that the work position of all pre-collimator’s holes can be selected and put into the use by the computer automatically.4. Design the system of detection and data acquisition and transmission of Compton Back-Scattering Imaging Scanner, provide some important indexes and methods that are used to assess this system.5. Design the scanning movement control unit of Compton Back-Scattering Imaging Scanner, mainly point out the control targets clearly, describe the control principle, etc. Discuss the features and technical indexes of this unit.6. Design the software of Compton Back-Scattering Imaging Scanner, point out the functions of this software. Give out the program modules in which the directory andcontents of this software is included. Give out the interfaces of the main program modules and describe the meanings of operating elements on these program interfaces briefly.7. According to the application theory of Compton Back-scattering that the writer had researched, he developed and produced its portable application devices successfully. After the experiment and on-the-spot application, its efficiency is as good as even better than the design indexes. It could be widely used in the areas such as the engineering, the military, the police and the customs.更多还原