Development of phase contrast x-ray imaging system

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Phase-contrast x-ray imaging generated by the differences in refractive indices has great potential to reveal the structures inside soft tissues because about 1000 times higher sensitivity is obtained with this method compared to the conventional method depending on the differences of x-ray absorption.Then the development of phase-contrast x-ray imaging system has performed to understand what was revealed in the human pathological specimens. Human cancer cells such as colon cancer, hepatocellular carcinoma and breast cancer had low refractive index ddelta compared to normal liver tissue. Fat tissue had very low ddelta less than that of water. Fibrotic tissues had relatively high ddelta in these pathological specimens. Necrosis had high ddelta.However in the present phase-contrast x-ray imaging, the view size of the object was limited to 5 mm x 5 mm due to the small size of the x-ray interferometer. To increase the field of view to image large samples, the triple Laue-case large x-ray interferometer was cut out of a 10-cm in diameter highly perfect single-crystal silicon ingot. In this non-separated type of large interferometer, the expected field of view with 30 mm x 25 mm was obtained. Visibility of this interferometer was sufficient to obtain the phase-contrast x-ray imaging and excellent quality of projection image was obtained.Using the phase-contrast x-ray imaging, the inner structures of biological specimens can differentiated without an contrast agents. In addition, the ddelta changes among tissues were differentiated clearly. As the largest interferometer in the world was manufactured, we can obtain the phase-contrast x-ray imaging of large object (about 30 mm).