Design Of Small Animal PET System Based On Continuous LYSO Crystal Ring And Monte Carlo Simulation Analysis

Positron Emission Tomography(PET)can be used to monitor the internal tissues of organisms at a very small size during the metabolic process.In the process of researching new clinical drugs,small animal PET systems are very important.Important application.At present,small animal PET systems based on discrete crystals are relatively bulky,and due to the limitations of resolution and sensitivity characteristics,there is still a gap in the application of accurate detection of small metastatic lesions.Combining the high sensitivity and high resolution characteristics of continuous crystals and exploring the limit of comprehensive performance,this paper proposes a small animal PET system based on continuous LYSO crystal rings,and analyzes the system design and imaging performance.First,the material and device selection of the continuous LYSO crystal ring small animal PET system was determined,the coupling mode of the traditional PET system detector crystal and the photoelectric sensor was optimized,and three different coupling schemes between the Si PM array and the crystal were designed.Secondly,the article carried out Monte Carlo simulation analysis through the GATE simulation platform,taking the double-end coupling scheme as an example,and used ROOT data analysis software to pre-analyze the simulation results to obtain an energy spectrum that meets the event.The distribution was visually analyzed to verify the feasibility of the system.Then,by simulating different heights and angles of incident gamma photons,the article compares and analyzes the resolution and error of the photon positioning in the two design schemes of double-end coupling and inner wall coupling.Large and have similar decoding rules.The decoding situation of the double-end coupling scheme in the height direction is better than that of the inner wall coupling scheme,and the average error of the two in the effective field of view is ± 0.23 mm and ± 0.38 mm,respectively.There is an edge effect on the inner wall coupling(the edge error reaches ± 1.76 mm),resulting in a reduced field of view(only 19 mm),and its decoding at different heights fluctuates greatly.The comprehensive design of the system determines the final design of the system as Doubleended coupling.Then,the self-compiler was used to extract coincidence events from the simulation results and convert them into coincidence line LOR information.The MLEM image reconstruction algorithm was used to perform image reconstruction analysis on the point source model to verify the computerized tomography capability of the system.Refer to the relevant NEMA,the standard evaluates the relevant performance of the system.The results show that the resolution in the XY plane is 0.3 mm and the resolution in the height direction is 1.1 mm.The spatial resolution is relative to the traditional small crystal PET system with discrete crystal structures.Improved.Finally,an image reconstruction analysis was performed on the Derenzo phantom source,and the imaging results under different iteration times were compared.The optimal iteration times were selected as 30 ? 50 times.The results show that the design scheme can clearly distinguish cylinders with a radius of more than 0.5 mm.The source has verified that the system has a uniform image reconstruction capability in the imaging field of view.The peak-to-valley ratio of the contour map of each area is basically the same,and the average peak-to-valley ratio is 2.55.The continuous LYSO crystal ring small animal PET system provides powerful support for the research of many basic medical projects such as lesion modeling at the early stage of the disease,new drug research and invention,and oncology,and provides new ideas for the development of small animal PET imaging equipment in China And related technologies.