Of Spect Data Acquisition And Processing System Design

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.