Control System Development For Linear Scanning CT Platform And Experimental Study

The linear scanning Computed Tomography(CT)achieves projection data by relatively parallel linear scanning of the X-ray source and flat-panel detector(FPD).The linear scanning CT system does not use the traditional CT slip ring,which can simplify system structure,reduce cost,and has a wide application prospect.This paper develops a control system for a linear scanning CT experimental platform and carries out the experimental study of CT imaging.The main research work is as follows:(1)The linear scanning CT imaging method and related image reconstruction algorithms are analyzed.Firstly,the geometric model,scanning mode and sampling mode of linear scanning CT are introduced.Then the system composition,selection and function of linear CT experimental platform are described in detail.Finally,the algorithms of linear scanning CT image reconstruction are derived,including FeldkampDavis-Kress(FDK)and simultaneous iterative reconstruction technique(SIRT).(2)The control system of the linear scanning CT experimental platform is developed.The overall design of the linear scan CT control system is completed.According to the design requirements of the control system,the motion control analysis and control software were completed,and the CT scanning control and the system power control are realized.(3)The data acquisition and data correction of FPD are studied.The data acquisition principle of FPD is studied,and the data correction methods,including dark-field correction,gain correction and bad pixel correction,are analyzed.The data correction experiment of FPD is completed.(4)CT imaging experiments are completed.The results of FDK and SIRT image reconstruction algorithms,equiangular and equidistant sampling,and different linear scanning mode are compared.The results show that,under the same scanning parameters,the FDK reconstruction algorithm has a faster reconstruction speed,while the SIRT reconstruction algorithm performs better in the processing of noise,and the image quality is better.The image quality of equiangular sampling is better than that of equidistant sampling because the projection data of equiangular sampling is more evenly distributed.The image quality of equiangular sampling is similar to that of circular scanning mode.Due to the limitation of the projection angle,the 1T scanning mode cannot achieve the accurate reconstruction CT image,while the image quality of more than 1T scanning mode is better than that of the 1T scanning mode.