Study On The Performance Of γ Photon Detector Based On Scintillator Ring

The front-endγphoton detector is one of the core components of the PET system,and its performance is directly related to the quality of the reconstructed image of PET system.Aiming at improving the limited sensitivity,simplifying the procedure of assembly and reducing the cost of traditional detector based on discrete crystal arrays,the idea of using a monolithic scintillator ring to build a front-end gamma photon detector is proposed.And the overall performance of the detector was evaluated through image reconstruction experiments firstly.The radiation detecting performances of the detector based on scintillator ring were also evaluated.Finally,we proposed an improved detector structure--the front-end detector structure based on semi-monolithic scintillator ring to improve the mediocre decoding performance in height direction based on the study of monolithic scintillator ring.And its decoding performance was evaluated preliminary.The design of the front-end detector based on scintillator ring and the construction of experimental platform were introduced firstly.Image reconstruction results show that the minimum aperture of the Derenzo Phantom that can be reconstructed is 1.1 mm.The FWHM of the gray image projected in the circumferential direction with a 0.9 mm aperture is 2.0 mm.the outline of the brain can be clearly distinguished through the reconstructed image of the mouse in vivo imaging experiment.Then,based on the unique structure of the scintillator ring,the positioning ability of the monolithic scintillator ring detector for detectingγradioactive source was evaluated with the Monte Carlo simulation tool—GATE as well as experiments.Two algorithms,including direct light distribution method（DLDM）and circumferential decoding method（CDM）,were proposed for locating radioactive source.The simulation results show that the radioactive source with an activity of 1 m Ci from 10.5 meters away can be detected with an absolute deviation of less than 5°within 30 seconds’data.The detection absolute deviation of less than 2°can be achieved within 60 seconds’data when the distance is no more than53.85 cm by carrying on two-dimensional radiation experiments with a ²²Na radioactive source with an activity of 80μCi.Finally,based on previous research,a front-end detector structure based on semi-monolithic scintillator ring and readout channel reduction method was proposed,designed,and built.Experimental results of uniform irradiation indicate that the channel reduction method of the sidewall readout electron system is feasible,which characterized by Row-and-Column energy spectrum.10 LYSO crystal slices were resolved in Flood Map in height direction except the two of the edge by utilizing local Center-of-Gravity method,which provides a reference for the construction of a high-resolution detector based on ring-shaped scintillator.