SPECT数据采集处理系统设计

【作者】 张大伟；

【导师】 赵书俊；

【作者基本信息】 郑州大学 ， 测试计量技术及仪器， 2007， 硕士

【摘要】 单光子发射计算机断层(SPECT)又称具有断层显像功能的γ照相机，是目前临床上应用最广泛的核医学影像设备，能够进行断层图像显像，提高了临床疾病诊断的准确性。论文首先简要介绍了SPECT的系统结构、工作原理、成像方式、采集方式、断层图像重建原理及方法、计算机软硬件系统及质量控制。论文的重点包括以下两方面的内容：第一、SPECT晶体探测器测试系统的设计。该系统以AVR单片机ATmeg128作为主控制器，采用性能优越的高速器件设计阈值电路、峰值保持电路、以模数转换器AD9220(10MSPS)为核心的高速模数转换电路及数据存储器扩展电路。在ATmeg128协调之下，准确采集SPECT探头光电倍增管输出的窄脉冲信号(1～2μs)峰值，采集速率达到3MS／S。该系统采用USB1.1接口技术，不仅可以方便地对SPECT探头上的每个光电倍增管进行标定，单独测量SPECT前端核电子学电路所输出有关γ事件的任一种信息。而且还可将其作为单独的多道脉冲分析器，应用于核探测其它领域。第二、基于采集卡PCI9810 SPECT采集模式的设计。SPECT采集模式分为静态旋转采集模式和动态旋转采集模式，后者主要是心电门控旋转采集模式。文中详细介绍了这两种采集模式的工作原理，并给出了实现方案。其中，在心电门控旋转采集模式中，利用采集卡DAQ2213采集心电信号，采用自适应差分阈值法检测出心电R波峰值点的时间信息，对PCI9810采集到的数据进行分位相存储，进行数据重组得到后续断层重建所需的正弦图。更多还原

【Abstract】 Single photon emission computed tomography is also named gamma camera which has the function of tomography imaging, and has become the most widely used nuclear medical image instrument currently. It can display tomography imaging, improving the veracity of clinic diagnosis.At first, this thesis introduced several aspects about SPECT, including system configuration, principle of work, imaging manner, acquisition manner, principle and method of tomography reconstruction, hardware and soft system of computer and quality control simply.The emphasis of the thesis mainly included two aspects in the following:Firstly, the design of SPECT crystal detector testing system. The system made use of AVR chip microprocessor ATmegl28 as controller, adopted high-speed CMOS chips prossessing excellent performance to design threshold circuit, peak value holding circuit, based on AD9220 high-speed analog-to-digital circuit and data memory expanded circuit. It was controlled by ATmegl28 to acquire the peak value of narrow pulse signal coming from PMT of SPECT forepart detector by rule and line, acquisition speed was up to 3MS/s. The system adopted USB1.1 interface technology, so it not only calibrated every PMT of SPECT forepart detector, and measured any kind information ofγincident coming form SPECT forepart nuclear electronics circuit by oneself, but also was used as one single multi-channel pulse analyzer applied in other nuclear detection domain.Secondly, the design of SPECT acquisition mode based data acquisition card PCI9810. SPECT acquisition mode mainly includes static rotary acquisition mode and dynamic rotary acquisition mode, the latter is mainly electrocardiograph(ECG) gating rotary acquisition mode. The thesis introduced principle of work of the two modes detailedly and presented project of realization. In the cardiac gating rotary acquisition mode, making use of data acquisition card DAQ2213 acquired electrocardiograph, adopting auto-adaptation difference threshold arithmetic got the time of R-wave peak value, storing and recombining data acquired by PCI9810 in relevant phase, getting sine image needed by latter tomography reconstruction.更多还原