Simulation Research Of X-ray Phase Contrast Imaging Of High Pressure Gas Interface And Phase Recovery

X-ray phase-shifting effect on low-density materials is far greater than absorption effect,which makes X-ray phase-contrast imaging have better effect than traditional absorption contrast imaging in detecting low-density materials such as gas and human soft tissue.In recent years,X-ray phase contrast imaging has been more and more widely used in biology,fluid dynamics and other fields.At present,imaging of solid-liquid interface and gas-liquid interface has been achieved.However,there are few research on high pressure gas interface.The turbulence of high-pressure gas generated by engine during operation is mainly composed of hydrogen and oxygen.Therefore,using phase shift information to imaging are more reliable than attenuation information when detecting substances composed of light elements.On this basis,this paper further proposes the idea of using X-ray phase contrast imaging technology to detect and image the high-pressure gas interface.In order to prove that phase contrast imaging can be applied to the high-pressure gas interface and obtain the best phase contrast imaging results,it is necessary to design an accurate and reliable numerical simulation tool,which can select the optimal parameters of the X-ray phase contrast imaging system.The randomness of the Monka method can real simulate the process of interaction between X-ray and matter.Therefore,the Monte Carlo method of the Geent4 platform has been utilized to add the function of statistical the changes of X-ray phase in the software.And the Fresnel diffraction process by the free propagation of X-ray is further simulated to obtain the diffraction pattern.Through the secondary development of Geent4,we can track the X-ray phase information after penetrating the model of high-pressure gas,and the process of diffraction is also be simulated to complete the whole simulation analysis of X-ray phase contrast imaging.Finally,taking the model of high-pressure gas as the research object,the phase contrast imaging effect is discussed under three aspects of X-ray energy,pressure and the thickness of model.In addition,a phase reconstruction method based on generating confrontation network is proposed according to the characteristics of phase image.On the basis of the initial structure,the high-frequency features of the object diffraction image can be obtained more accurately by increasing the number of layers of the down-sampling,And the low-frequency image information can be shared through the jump connection.Which realizes the reverse process of obtaining the object information from the phase information of a single diffraction image in practical applications,provides anew way for phase recovery.Finally,the reconstruction result is compared quantitatively and qualitatively with the traditional iterative phase recovery algorithm,like ER algorithm and HIO algorithm.Compared with the traditional iterative method,the peak signal-to-noise ratio PSNR is improved by about 72%,and the structural similarity SSIM is improved by about 7%.In this paper,the phase reconstruction method based on the generation of confrontation network can realize the reconstruction of phase information from the single diffraction intensity map which obtained by the free propagation method,also can achieve better reconstruction effect than the iterative phase recovery algorithm.