Research On Simulation Of Imaging Process Based On Virtual CT System

Virtual CT (Computed Tomography) simulation system become research focus, because it can design and optimize assembly performance parameter of the CT system, help design and optimize the hardware system, provide instructive suggestions for parameter hypothesis in the actual experiment, provide the method and key techniques of non-contact CT detection for the reconstruction precision and quality analysis. By taking virtual CT system as research object, this paper extracts and depicts the physical properties for virtual CT system imaging process. Then this paper integrates these physical properties into the procession simulation of virtual CT imaging, and establishes the simulation model which realistically reflect the actual the process of CT imaging. This model can provide the credible data for the research of visual CT system, and upgrade the applicability of virtual CT system.Firstly, based on analyzing the principle of CT imaging and simulation, the emission process of X-ray is simulated. By taking this simulation result as basic, some physical factors of CT imaging system are analyzed and integrated into the simulation model of projection process, which are the distribution of X-ray spectrum, the interaction with material's attenuation coefficient and the X-ray energy, the influence of radiation source focus size in radiography, and so on. Then the simulation algorithm, based on consecutive spectrum, is presented. In the realization process of projection simulation, the method of spectrum sampling is adopted based on adaptive Simpson. This method can adaptive add the spectrum according to the uptrend of energy spectrum distribution. So it can improve the precision and speed of simulation.Secondly, in the process of X-ray CT imaging, because of the impact of scatter, the contrast of CT image becomes low, the edge of CT image blur. So in the visual CT system, it is necessary that scatter is simulated, which can realistically reflect the actual the actual CT imaging system. This paper offer a handy and effective scatter process simulation method, which is the method of scatter simulation about virtual CT system, based on images fusion using ICA (Independent Component Analysis), according to the interaction with substances and X-ray and scatter impact for CT image. This method use ICA image fusion to realize images fusion, which are scatter-free image and scatter image, which are established by prior information and the model of scatter degradation. So the scatter process simulation about virtual CT system is realized.At last, the above simulation method is validated by simulation experiment. The results show the simulation method of X-ray emission, projection process and scatter process is viable. It realistically reflects the actual CT imaging system, and offers the credible data for the research of visual CT system.