Phase contrast x-ray imaging is an important technique for investigation of materials consisted of light atoms, such as soft biological tissues. The tunable monochromatic x-ray source based on Parametric X-ray Radiation (PXR), which was developed at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University, provides x-rays with a high spatial coherence which is an essential property required for phase contrast imaging. In preliminary experiment, refraction contrast images for leaf tissues of a tree and animal specimen have been obtained successfully with the LEBRA-PXR x-rays. In the imaging system, the x-ray that passed through the sample once reflects off the silicon perfect-crystal x-ray analyzer at the Bragg angle, and then enters the imaging plate. The bright-field and the dark-field phase contrast images have been obtained by infinitesimal rotations of the analyzer, showing the evidence of contrast reversal. Although the conventional radiograph by absorption contrast was also taken with the LEBRA-PXR, significant differences are found between the radiograph and the phase contrast images.
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