Study On Linear CT Scanning For Experiment System

Computed tomography(CT),a digital radiography inspection technique,can show the interior structures,material components,defects of the inspected object in accurate image.It is an advanced technique for medical diagnosis and industrial nondestructive testing(NDT).CT image reconstruction process is using the projection data from multi-direction to obtain the inner information of object.Therefore,in order to acquiring the sufficient angle projection data,modern medical CT system generally use the slip ring to complete the rotation movement of X-ray source and the detector.As a result,a gantry with a slip ring is indispensable,which is expensive and difficult to be moved around.Hence,modern medical CT system is expensive,which results in that some developing countries and regions can't afford the cost for research and usage.On the other hand,the complex CT system limits its application in the field of detection,such as disaster scenes,and battle fields.Hence,the research and development of new CT imaging system with mobile,simple structure and low cost has great practical significance.In 2014,a novel CT scanning method,which is based on the reverse translation of the tube/detectors,was proposed by Professor Ge Wang at Resselaer Polytechnic Institute of USA and Professor Fenglin Liu at Chongqing University of China.The system uses the linear motion of the source and detector instead of the rotational motion,which has the characteristics of low cost,simple structure and movable.The paper mainly completes design of the CT platform and test work,which provides a theoretical basis for the actual system construction.The main contents of the paper are as follows:(1)Based on the theory of circular trajectory CT scanning CT,The scanning process of linear scanning CT was deduced and the similarities,and differences between 1T,2T,3T and 4T scanning patterns were compared,which provide theoretical support for later experimental design.The paper proposed a short scan method of linear scanning CT,which has the characteristics of low radiation dose and high detection efficiency;According to the characteristics of linear scanning CT sampling method,the paper analyzed the uniformity of equiangle sampling is better,and equidistant sampling is more simple in motion control.Finally,based on the system testing requirements,the maximum travel scan model and the maximum field scanning model are proposed,and the optimal parameters of scanning parameters are completed.(2)The overall design of the CT system platform is completed,which provides a feasible solution for the actual system construction.The full investigation is completed for the selection of main components of the system.The control structure of the CT system is put forward,which provides the communication foundation for the coordination of the subsystems.Finally,designed the corresponding software interface.(3)The relevant test verification in the simulation environment and the existing system are completed.The paper tests the image quality reconstructed with the projection data acquired by the two sampling methods.The simulation results show that the uniformity of the projection data acquired by equidistant sampling is poor,which causes the reconstructed image artifacts;According to the selected hardware parameters,the optimal scanning parameters of 2T,3T and 4T are determined,the simulation results show that the parameter deviation model result in the reconstructed images with serious artifacts,and images reconstructed by optimal scanning parameters are clear;6T scanning is completed in the existing system,the reconstructed image structure with FDK algorithm is clear and the internal information is rich.