The Designation And Optimization For Micro-PET Detector Block

This paper is based on the project: small animal molecular medical imaging, which mainly aims to integrate four modes in one system, including CT(Computed Tomography),Micro-PET (Positron Emission Tomography),SPECT(Single-Photon Emission computed Tomography) and FMT(Fluorescence Molecular Tomography).The content of this paper is about Micro-PET, to design the structure of the probe and research on the methods about improving the performance of the probe. Micro-PET, which is also known as small animal PET, reflects the functional information about specific area of the living body by three dimensional pictures in the level of biological molecules, and has a broad application prospect in the basic medicine and new drug research. The detector block of Micro-PET, including crystals and detectors, is used to receive theγphotons into electrical signals. The size of one crystal pixel determines the Micro-PET resolution, so the detector block, which is one of the most important aspects for Micro-PET, has a direct impact on the performance of Micro-PET.First, this paper gives a detailed discussion on the import role in the biomedical filed, and also gives a detailed analysis on the history of Micro-PET and the research status of the probe at home and abroad.Second, the paper introduces the principle of Micro-PET, and compares to the commonly used scintillation crystals and the detectors. The electronic circuit ,Following the probes, is used for processing the signals produced by the probes, including the first stage amplification,shaping,the second amplification,constant fraction discriminator and coincidence etc. This paper gives a detailed introduction, especially for the amplifiers in practical application.Third, DOI (Depth of interaction) is a very import concept. In this paper, the DOI of the ring PET,the planar PET and the arc PET is compared. This paper focuses on the analysis of arc PET, and after comparing the DOI of the three structures, the ring PET will be used.Fourth, in Micro-PET, the crystals and the detectors are all key parts, so it is need to do a lot of testing experiments on crystals and detectors. In this paper, the performance of two kinds of crystals is compared by experiments to ensure the excellent performance of the crystals, and the characteristics of the signals produced by the probes are observed. The most import part of paper is that a method—Crystal Crossing Technology for improving the resolution of Micro-PET will be put forward, and it is also need to do a lot of experiments to prove the feasibility of the method.Fifth, according to the fast rise/fall time of the signals produced by the probes, in this paper a circuit called peak hold circuit are designed, to broaden the signals in the condition of not distortion, in order to observe the signals using some instruments. The method for improving the resolution of Micro-PET needs the according circuit, so a circuit is designed.