Research On Compton Backscatter Imaging Simulation And Image Reconstruction Technology

Back scattering imaging technology based on Compton effect is an important research direction in the field of X-ray imaging technology.It uses the backscattered photons generated by the interaction between X-ray and matter to image.Compared with the traditional transmission imaging,its ray source and detector are located on the same side of the target to be tested,which can realize the non-destructive detection of large-scale objects,and has higher contrast when imaging low atomic number substances,so it has certain advantages in the detection of dangerous chemicals,drugs and so on.The conventional image reconstruction methods of Compton Backscatter Imaging include accurate focusing method and energy spectrum analysis method.The traditional accurate focusing method needs to scan point by point,and the scanning time is long and the ray utilization rate is low.The energy spectrum analysis relies on the detector with high time resolution,so the energy spectrum data obtained is limited,and the reconstruction algorithm has high computational complexity and long time-consuming.Therefore,on the premise of accurate focusing method,a Compton Backscatter Imaging System Based on linear array detector is proposed and studiedThe conventional image reconstruction methods of Compton Backscatter Imaging include accurate focusing method and energy spectrum analysis method.The traditional accurate focusing method uses unit detector,which needs three-dimensional scanning during imaging,and the imaging time is long;the energy spectrum analysis method relies on the detector with high time resolution,and the detector can not distinguish the energy spectrum data when there are a large number of scattered photons.Based on the accurate focusing method,this paper proposes a Compton Backscatter Imaging System Based on linear array detector,which can image only through two-dimensional scanning,which can effectively improve the imaging speed.The main contents of this paper are as follows :Based on the interaction between ray and material,the working conditions of Compton effect are determined.Based on the precise focusing method,the Compton Backscatter Imaging System Based on linear array detector is designed.The problem of "overlapping of detection areas of adjacent detection units" is analyzed,and the simulation model of backscatter imaging is constructed.The Compton Backscatter Imaging Simulation is completed by GEANT4 Really.The simulation results based on the accurate focusing linear array detection model are consistent with the results of the energy spectrum detection model,which proves that the Compton Backscatter Imaging System designed in this paper is feasible.In the process of image reconstruction,the attenuation correction model is established based on the ray attenuation law,and the electron density of each depth point is corrected.The attenuation correction model established in this paper only uses the number of backscattered photons collected by the linear array detector to complete the attenuation correction,and the reconstructed image quality after the ray attenuation correction is better than that of the uncorrected reconstructed image.The work done in this paper has a certain guiding significance for the design of Compton backscattered imaging system.