【作者】 王玥；

【导师】 康雁；

【作者基本信息】 东北大学 ， 生物医学工程， 2013， 硕士

【摘要】 正电子发射计算机断层扫描装置(Positron Emission Tomography, PET)可非侵入地提供生物活体中放射性示踪剂分布的断层图像,是当今最高层次的核医学诊断与研究技术之一。本文对PET快电子脉冲时间信息捕获过程所涉及的关键问题进行了研究,并在以下几个方面取得进展。针对常规的单片高速AD芯片采样PET快电子脉冲成本过高的问题,本文将多片低速AD并行交替采样技术引入到快电子脉冲数字化过程,以有效降低时间信息捕获系统成本。分析了交替采样理论的数学原理,设计了主控芯片控制下两片AD并行交替采样的脉冲数据采集和显示软硬件系统,完整且不失真地重构了原始输入信号。为深入认识PET快电子脉冲启动时间的发生规律,预测堆积脉冲的发生概率,基于核医学开发工具包GATE (Geant4Application for Tomographic Emission),建立了LYSO闪烁晶体PET探测器环的计算机仿真模型,以二维和三维两种方式采集了典型的放射活度下伽马光子与探测器的作用时间序列。在上述工作的基础上,本文开发了快电子脉冲启动时间间隙提取的源代码,利用计算机仿真模型的输出提取出相关数据,建立了PET快电子脉冲启动时间间隙的概率分布直方图。研究了负指数分布极大似然参数估计的数学实现过程,求解参数并进行假设检验,为PET时间甄别系统关键技术参数设计提供指导依据。更多还原

【Abstract】 Positron emission tomography (PET) is one of the most advanced nucleus medicine diagnosis and research techniques which can provide the tomographic image of the distribution of the radiotracer in the living organism noninvasively. This thesis concentrated on the research of capturing the time in the fast electronic pulse in PET and the related key issues. We gained the progress in the following aspects.For the high cost of the normal single high-speed analog-digital convertor sampling the fast electronic pulse in PET, the thesis led the technique of multi-chip AD parallel sampling into the process of digitalizing the fast electronic pulse in order to reduce the cost of the time information capturing system. First, analyze the mathematical theory of parallel sampling. Then design the software and hardware system of electronic pulse sampling and displaying via micro-controller unit controlling two chips of ADC. At last, reconstruct the original input signal without distortion and completely.In order to grasp the law of the fast electronic pulse’switching time in PET more deeply, predict the probability of accumulated pulses’occurrence. The thesis constructed the scintillation crystal LYSO PET detector ring’s computer simulation model based on the nuclear medicine development tools-----GATE (Geant4Application for Tomographic Emission). Furthermore, gathered the action time information of gamma photon and detectors under the typical radioactive intensity via2D and3D two different methods.In the foundation of the works above, the thesis developed the source code to extract the fast electronic pulse switching time interval, using the computer simulation model’s output to extract the related data, constructing the probability distribution histogram of the fast electronic pulse switching time interval. Researching the maximum likelihood parameter estimation of negative exponential distribution and its mathematical implementation process, solving the parameter and doing the hypothesis testing which provided the guidance basis to the parameter designing in the PET time screening system.更多还原