基于FPGA的TOF PET符合判选研究

发布时间：2018-04-15 21:24

本文选题：正电子断层发射扫描 + 可编程门阵列　；参考：《中国科学院研究生院（长春光学精密机械与物理研究所）》2012年硕士论文

【摘要】：正电子发射断层扫描(PET-Positron Emission Tomography)是当今最先进的核医学成像技术,属于功能成像技术。它利用放射性的示踪剂在分子水平上动态反映人体内各个器官的的代谢水平和生化反应。将飞行时间(TOF)技术应用于PET是一次伟大的技术革新,TOF技术可以将正电子符合湮灭的位置精确定位,减少重建该事件所涉及到的体素数量,局部的信息浓度高,使得定量更加精确、注射剂量更低、成像更快、临床图像的分辨率更高。要想实现对正电子湮灭的精确定位,TOF PET系统必须具有很高的时间分辨率。将FPGA引入到TOF PET时间测量电路和符合判选电路,使设计的电路具有结构简单、运算量少、体积小等优点,为模块化的TOF PET系统提供了可扩展性和再编程的灵活性。同时使电路获得非常高的处理速度,可满足TOF PET对时间分辨率的要求。本文以~l00ps的时间分辨率为目标,探讨TOF PET的时间数字转换器(TDC)和符合判选电路的设计实现和软件仿真。从系统的开发设计环境出发,介绍了FPGA的基本结构、开发环境和开发语言,讨论了TDC的实现技术,并进行了比较与分析,给出了本文所用技术的总体设计,之后进行了具体模块的设计与实现,获得了~l00ps的时间分辨率。在符合判选电路部分,基于一种模块化、低死时间快速符合系统的设计思路,比较了与逻辑符合方法和时间标记排序方法在时间分辨率和系统复杂度等方面的差别,提出了一种分级符合判选方法,使电路在使用很短时间标记的情况下得到了较好的时间分辨率(~l00ps),简化了系统复杂性。实验结果表明,这种基于FPGA的TDC电路和符合判选电路可以用较低的代价实现TOF PET符合判选。
[Abstract]:Positron Emission tomography (PET-Positron Emission tomography) is the most advanced nuclear medical imaging technology, which belongs to functional imaging technology.It uses radioactive tracer to dynamically reflect the metabolic level and biochemical reaction of various organs in the human body at the molecular level.The application of time-of-flight (TOF) technology to PET is a great technological innovation. It can accurately locate positron in the position of annihilation, reduce the number of voxels involved in the reconstruction of the event, and have a high local information concentration.It makes the quantification more accurate, the injection dose lower, the imaging faster, and the resolution of clinical images higher.In order to locate positron annihilation accurately, the TOF PET system must have high time resolution.This paper introduces FPGA into TOF PET time measurement circuit and coincidence selection circuit, which makes the designed circuit have the advantages of simple structure, less computation and small volume. It provides extensibility and reprogramming flexibility for the modular TOF PET system.At the same time, the circuit can achieve a very high processing speed, which can meet the time resolution requirements of TOF PET.Aiming at the time resolution of 100ps, this paper discusses the design and implementation of TOF PET time-digital converter and coincidence circuit and its software simulation.This paper introduces the basic structure, development environment and development language of FPGA, discusses the realization technology of TDC, compares and analyzes the technology used in this paper, and gives the overall design of the technology used in this paper.Then the specific module is designed and implemented, and the time resolution of 100 PS is obtained.In the part of coincidence selection circuit, based on a kind of modularization, low dead time fast coincidence system design idea, the difference of time resolution and system complexity between logic coincidence method and time label sorting method is compared.In this paper, a hierarchical coincidence selection method is proposed, which can get a better time resolution and simplify the system complexity under the condition that the circuit is marked in a very short time.The experimental results show that the TDC circuit based on FPGA and the coincidence selection circuit can realize TOF PET coincidence selection at a lower cost.
【学位授予单位】：中国科学院研究生院（长春光学精密机械与物理研究所）
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R814.42

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