The Design Of Digital SPECT Forepart Detector System Based On FPGA

Nuclear medical instrument is widely used in the field of clinic diagnoses and medical researches. Nuclear medical imaging is functional imaging, and can reflect the dynamic change of human organs. It has important status in disease diagnoses especially in tumors' early diagnoses. Now the most widely used nuclear medical instrument in clinic is Single Photon Emission Computed Tomography (SPECT).SPECT is composed of forepart detector; machine rack for instrument rotation and movement and computer. The forepart detector is the part of gathering originally data and processing these data. The main task of it is gathering γ events and selecting the valid events transferring the position and energy information of each valid event to main computer. The programs run in main computer correcting these data and reconstructing the images. This part directly influences the whole system's sensitivity and resolution, the system's precision and the quality of the image.This thesis mainly introduces the design of digital SPECT forepart detector. This design uses digital circuit based on Field Programmable Gate Array (FPGA) instead of analog electronics circuits. The signals coming from photomultipliers are amplified by preamplifier and programmable amplifier, then processed by high-speed analog-to-digital (A/D) converter and is transferred to FPGA. In FPGA it has following processes to calculate the position and energy of γ events. And it also adds hardware correction parts in FPGA in order to realize data's real-time correction. This design uses StratixII FPGA of Altera Company. It has quantity high-density logic cells and has abundant Digital Signal Processing (DSP) modules. And the QuartusII design software is used to make our design easily.This thesis introduces the electronic circuits design in forepart detector in detail. It includes analog part and digital part. Analog part has two amplifiers; signal shaped circuit; high-speed A/D converter and so on. Digital part mainly includes the design...