The invention relates to a rotational X-ray device (100), for example a CT scanner, for generating phase contrast images of an object (1). In a particular embodiment of the device (100), a plurality of X-ray sources (11), an X-ray detector (30), and an analyzer grating (G2) are attached to a rotatable gantry (20), while a ring-shaped phase grating (G1) is stationary. The X-ray sources are disposed such that X-rays first pass an object under study before traversing the phase grating (G1) and subsequently the analyzer grating (G2). This is achieved by either shifting the X-ray sources axially with respect to the ring-shaped phase grating (G1) or by disposing the X-ray sources in the interior of the ring. Moreover, the phase grating (G1) and the analyzer (G2) shall have spatially varying relative phase (and/or periodicity), for example realized by line grids that are tilted with respect to each other. During the rotation of the gantry (20), the synchronized activation of X-ray sources (11) allows to generate projection images of an object (1) from the same viewing angle with different relative positions (and therefore phases) between the phase grating (G1) and the analyzer (G2).
