正电子发射断层扫描仪（PET）中机电控制系统的研制

【作者】 吕英杰；

【导师】 杨雷； 赵书俊；

【作者基本信息】 郑州大学 ， 测试计量技术及仪器， 2002， 硕士

【摘要】 正电子发射断层扫描仪(PET)是核医学仪器中一种具有较高特异性的功能成像设备，它能够对心脑血管疾病及肿瘤病变进行早期的无损诊断，在现代核医学领域里起着十分重要的作用。本文在介绍正电子发射断层扫描仪系统结构及工作原理的基础上，着重对该仪器机电控制系统的部分功能实现作了详尽描述，并且介绍了一种新型的高频时钟扇出电路的设计。 论文的第一部分和第二部分主要就PET系统的特点、工作原理及系统内各模块设计作了简要描述，突出了PET与其他医学成像仪器相比所特有的功能。 论文的第三部分重点说明了PET系统机电控制部分中主机箱控制板的设计，尤其突出介绍了用串行通信控制器AM85C30实现扩展串口，用RS-485总线传输标准实现的以该控制板为主机，机电控制部分其余子模块为从机的主从式多点总线型串行通信系统，在软件设计上引入了一种多任务非占先式编程的思想，使得该主控制板能够在系统允许的最小时间内完成与其余子模块之间的信息交换。 论文的第四部分介绍了为PET系统前端电子学模块提供时间基准而设计的一种新型高频时钟扇出电路。该电路利用了FPGA芯片来实现对高频时钟的分频与分配，用LVDS传输标准对生成的多路时钟进行传输，最大程度减少了输出各路时钟间的延时偏差，并且 摘 要 利用其低压差分信号的传输特性增强了信号的抗干扰能力。 在论文的最后分析了PET系统机电控制部分设计中出现的各 种干扰，并针对这些干扰提出了具体的硬件和软件抗干扰措施，保 证了本部分工作的稳定运行。更多还原

【Abstract】 Positron emission tomography (PET) is the functional imaging equipment with good specificity among the modern nuclear medicine instruments. It can make the noninvasive diagnosis of coronary artery disease (CAD), brain disease and tumor in their early changes. Therefore, it plays a very important role in the field of modern medicine. Based on the introduction of the systematic structure and working principle of PET, the thesis mainly described the realization of the partial function in the mechanical and electrical control system. Furthermore, the thesis referred the design of a new circuit of fan-out of high frequency clock.In the first and second parts of this thesis, the characteristics, working principle and mode designs of the PET system were described with the emphasis on the special functions of PET comparing with other nuclear imaging equipment.The third part stressed on the design of gantry control print circuit, especially on how to use AM85C30 to expand serial port and to realize the master-slave mode multi-point bus serial communication system with the principle gantry control circuit and other subordinate circuits using RS-485 bus standard. We developed an idea of more tasks and non-occupancy in programming to make sure that the circuit can complete the communication between the gantry control circuit and other circuits within the permissible minimum time in the system.A new circuit of fan-out of high frequency clock was designed to providea reference clock for the front electrical mode of PET system in the fourth’ part of the thesis. The circuit performed the division and fan-out of highfrequency clock by using FPGA, and transformed the clock in LVDA stylewith least disturbance as possible. At the same time, it reduced the delay difference between clocks.In the last part of this thesis, various electrical noises generated in the system were analyzed and the efficient measurements to improve the anti-interference feature on both hardware and software were employed to keep the stable operation of the system.更多还原