Study Of Conventional X-ray Source-based Phase-contrast Imaging Methods

X-ray phase-contrast imaging(XPCI)can get high contrast and resolution for light or densitysimilar materials.It has unique superiority compared with conventional absorption-based imaging and has important application value in many fields,such as medicine,biomedical and materials science.Nowadays,XPCI is a hotspot in the field of X-ray imaging.The conventional X-ray sourcebased XPCI techniques has extremely important significance and is the key to the popularization of XPCI.However,there are still many problems in imaging methods in the conventional X-ray sourcebased XPCI techniques.In this work,a numerical simulation model is built according to the geometric optics.We focus on the study of conventional X-ray source-based XPCI methods,two implementation methods,i.e.analyzer-based imaging(ABI)and coded-aperture based imaging(CBI)are studied.Researches are carried out to solve the problems existed in the information extraction method,imaging method,and physical design.The main work and results are summarized as follows:Firstly,the extraction characteristics of multiple-image radiography(MIR)in ABI method are studied in the condition of the conventional X-ray sources.The extraction results get worse with the increase of Poisson noise,when the photon counting is larger than 1000 per pixel,the effect is negligible.The acquisition scheme is related to the noise levels and refraction-angle signals.The three kinds of information,absorption,refraction,and USAXS are interfered with each other,where the effects of refraction and USAXS are significant.The effects of noise,acquisition scheme,and information interference should be considered in practical applications.Secondly,a quantitative information extraction method based on the slope of the illumination curve is proposed in the CBI method.The dependencies of the refraction-angle sensitivity and the extraction accuracy on the source size are studied.The results show that our proposed method can extract a more accurate refraction-angle result.In addition,the impact of source size on refractionangle sensitivity is acceptable,indicating that the CBI method is suitable for conventional X-ray sources.Thirdly,on the basis of the standard CBI method(DM-DS)and existing single-shot CBI method(SM-SS),an alternative single-shot CBI method(DM-SS)is proposed.The characteristics of these methods are compared under different influence conditions.The results show that DM-SS has relatively better performance,its nature of contrast enhancement and single-shot helps for the translation of the EI-XPCI techniques into practical applicationsLastly,the physical design of the CBI system and the prefabrication of the coded-aperture are carried out.The composition,layout and hardware parameters of the system are presented.On the basis of these,the performance of the designed CBI system is evaluated in terms of image contrast and imaging time,etc.In addition,the application of the melting method in the fabrication of codedaperture is explored.The prefabrication of the coded-aperture is carried out using two kinds of powders(lead and gold).The experimental results show that the melting method is a potential approach for fabricating of the coded-aperture,but still needs to be improved and perfected.