| PET/CT(Positron Emission Tomography/Computed Tomography) imager is a new type of medical imaging instrument which combines PET(functional metabolism imaging) and CT(anatomical imaging) two advanced imaging techniques. Dedicated breast PET/CT is a medical imaging technology specially designed for breast disease diagnosis according to it’s own features, it plays an important role in the diagnosis and treatment of early breast cancer. Integrated PET/CT scanners achieved rapid flight fusion with functional PET imaging and anatomical CT imaging, it appears higher reliability compared with individual CT or PET in cancer diagnosis and staging. Improving the spatial resolution of imaging system is an issue that being concerned during the fast development of breast PET/CT technique. Spatial resolution of the PET component is the main factors that influencing the spatial resolution of the PET/CT system. Therefore, the design of high resolution PET detector is the key to improve the performance of PET/CT imaging system, it is currently also the focus breakthrough direction of the research and development of PET instrument and PET/CT instrument.In this paper, design and test on the experiment platform of high resolution breast PET/CT detector are studied, respectively finished the design and preliminary performance tests on the experiment platform of CT detector and PET detector. Using the amorphous silicon flat paneldetector as CT detector to design the experiment platform, and using new photodetector, silicon photomultiplier tubes(SiPM), combined with LYSO scintillation crystals to design the dual-end readout PET detector which has depth resolution. Compared to the traditional photodetector such as photomultiplier tubes(PMT) and avalanche photodiode(APD),SiPM at the same time has a low work voltage, small volume, high signal-to-noise ratio, high gain, etc, is the best choice for designing high performance PET detector.The main study of this paper as follows:Firstly, we’ve made an introduction and analysis to the imaging principle of CT, PET and PET/CT respectively in detail, and done analysis and comparison on the performance of CT and PET detector.Then the experiment platform of CT and PET detector was designed respectively.(1) Constructed a hardware platform for the CT detector experiment system with a four shaft high precision motion platform, an amorphous silicon digital flat panel detector and a micro focal spot X-ray source as the core component. Design and debugging the PC control software for the experimental system modules based on the Visual Studio2008 software development environment. And designed a high reliability method, slit method, for testing the modulation transfer function(MTF) of the flat panel detector on the basis of the designed experiment platform for CT detector, the resolution performance of the flat panel detector was verified.(2) Analysis of main parameters which influence the properties of PET detector, design the dual-end readout PET detector which has depth resolution based on SiPM. Designed two signal readout schemes respectively, resistance network readout scheme and sum readout scheme with row and column of capacitance network. Testing and comparative analysis the performance of the designed SiPM readout circuit andcommercial position sensitive PMT(PSPMT) detector using the constructed experimental test platform, verified the feasibility and advantage of the dual-end resistance network readout scheme based on SiPMs. On the side of software and algorithm, designed some of algorithms including the energy spectrum graph, calculation of DOI depth,calculation the flood histogram of crystals and segmentation algorithms for crystal cells, and implementation through MATLAB programming,completed crystal cell segmentation through the VS2008 software developing platform. The depth resolution of the disigned PET detector clear to 3mm.Finally, summarizing the work of the project, analyzing and expounding the existing problems and subsequent work needs to be done. |
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