Simulation of X-ray phase-contrast imaging with partially coherence source

An X-ray diffraction imaging model based on microfocus X-ray tube was presented. The model used the scalar diffraction and partial coherent X-ray diffraction theories, taking the hard X-ray features in consideration. In this model, the Fresnel integral was performed in the spatial frequency domain, and the X-ray diffraction field was calculated by means of the fast Fourier transform (FFT). According to the partial coherent theory, the X-ray intensity in the image plane was the convolution of the intensity of object irradiated by the X-ray beam from an ideal point source with the intensity distribution of the expanded source. Thus the intensity distribution in the image plane can be obtained by transforming the convolution in the real space to the multiplication in the spatial frequency domain, and its calculation efficiency can be improved by using the FFT. The simulation results show that the image contrast is determined by the distance from the source to object plane, by the energy of X-ray photon, and by the size of X-ray focal spot. The simulation is helpful for the design of X-ray phase contrast imaging system based on the free space propagation.