Correcting The Intensity Drift Effect And Computed Tomography In Grating-based Phase Contrast Imaging

X-ray phase imaging has attracted increasing attention during the past few decades, substance composed of light elements, such as biological soft tissue, which generate poor contrast by conventional x-ray absorbing imaging, Grating based phase constrast imaging with a Talbot-Lau interferometer could use conventional x-ray source instead of expensive synchrotron radiation (SR) source. Moreover, the phase-stepping data acquisition method in grating-based phase contrast imaging provides not only refraction images, but also absorbing images and small angle scatter signals. This method is fully compatible with existing computed tomography (CT) and can generate two additional images, which makes it one of the most potential technique applied in clinical practice and non-destructive testing.The thesis’experiment was carried out in the National Synchrotron Radiation Lab-oratory (NSRL) of the University of Science and Technology of China (USTC) using grating-based x-ray phase contrast imaging setup,we used phase-stepping technique to acquire data and data post-processing about information retrieval.In actual experiment, we found that the photon intensity drift of the x-ray source would influence the final images, especially the refraction images. After analyzing the phase-stepping curve, we proposed a correction method to fix the wrong image due to the effect of intensity drift. Experimental results showed the method could solve this problem and get the right re-sults successfully.In the conventional X-ray imaging, computed tomography technique (CT) can reconstruct the object’s cross-section detailed images with projections from a series of angles around axial direction. With CT technique, we can achieve the purpose of non-destructive testing, and X-ray phase contrast imaging tomographic has little dif-ference with conventional X-ray CT,in the thesis we explained the theories of CT re-construction and made numerical simulation about a phantom,then we discussed the CT reconstruction of phase contrast imaging.In the last part of the thesis we proposed a software framework with GUI about information retrieval and tomography reconstruction,featuring with ease of use, cross-platform and scalability. Then this framework can help us analysising data, furtherly lays a good foundation for future study about phase-contrast tomography.