Study Of Positron Emission Particle Tracking(PEPT) Technology In Flow Field

Positron annihilation detection,as a new detection technology,has great application value because of the strong anti-interference and good penetration of γ-rays.Positron emission particle tracking technology,which combines the principle of positron annihilation with the idea of particle tracking measurement,is commonly used in the study of industrial equipment and physical processes.In this paper,the positron emission particle tracking technology is extended to flow velocity measurement and flow pattern display in flow field environment by combining theoretical analysis with experimental verification.In theoretical analysis,the key algorithms of positron emission particle tracking technology are studied in this paper.Firstly,for single particle,two different localization algorithms based on Birmingham algorithm and line density algorithm are analyzed and compared.For multi-particles,two different localization algorithms based on line density algorithm and K-means clustering algorithm are analyzed and compared.Then the trajectory link is transformed into bipartite graph matching and a multi-trajectory link algorithm based on KM algorithm is proposed.Finally,the Kalman filter algorithm is studied and applied to the smoothing of the flow trajectory.In the aspect of simulation test,firstly,the simulation model of positron annihilation detection is built by GATE software,and the tracer particle parameters are initialized to obtain the response line data.Secondly,the lines of response are positioned and processed to study the difference of positioning accuracy and stability between different algorithms.Finally,different particle motion models are designed in the MATLAB environment,and the position data in the simulation slice is obtained to study the processing performance of the two algorithms.In the aspect of experimental testing,a circulating flow measurement system is built firstly,and then the particle position is obtained from the original trajectory section data of positron annihilation tomography scanner.Finally,the feasibility of positron emission particle tracking method in the state display,trace plotting and accurate velocity measurement of fluid is verified by single and multi-particle tracking experiments.