Abstract: Positron emission tomography technology is an emerging nuclear medicine imaging technique that can provide the physiological metabolic level of functional imaging, has wide application in many fields, such as disease diagnosis, pathology research, and drug research and so on. The core of PET technology is detector and scan structures design. Scanning structures include ring-static scanning, ring-dynamic scanning, flatbed-static scanning, flatbed-dynamic scanning and so on. A variety of detector structures have developed: PMT coupled to a single crystal, PMT coupled multi-block crystals, PSPMT coupled crystal array, SPM coupled crystal array and so on. The author began to engage in medical PET studies from 1983, this paper reviews several PET machines that author has developed, and describe the development of the PET detector and scan structures.