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Photothermal modulation of x-ray phase contrast images

The in-line x-ray phase-contrast imaging method relies on changes in index of refraction within a body to produce image contrast. In soft tissue, index of refraction variations arise from density changes so that phase contrast imaging provides a map of density gradients within a body. An intense, short pulse laser beam that is differentially absorbed by an object within a body will produce a thermal wave with an associated density change that propagates outwardly from the interface between the object and the body. Experiments are described where a pulsed Nd:YLF laser is synchronized to an image intensifier to record the effects of the energy deposited by a pulsed laser.