The present invention relates to phase contrast X-ray imaging of an object. In order to provide phase contrast information in more than one direction, an X-ray imaging system is provided that comprises an X-ray source (12), an X-ray detector arrangement (16), and a grating arrangement (18) with a phase-grating structure (46) and an analyser-grating structure (48). The X-ray detector arrangement comprises at least eight line-detector units (40) parallel to each other in a first direction (42), the line-detector units extending linearly in a direction (44) perpendicular to the first direction. The X-ray source, the X-ray detector arrangement and the grating arrangement are adapted to perform an acquisition movement in relation to an object in a scanning direction parallel to the first direction. The phase-grating structure has a number of linear phase-gratings, each of which is arranged in fixed association with an assigned line of the at least eight line-detector units； a first part as first phase-gratings with slits in the first direction, and a second part as second phase-gratings with slits in a second direction different to the first direction. The analyser-grating structure has a number of linear analyser-gratings, each of which is arranged in fixed association with an assigned line of the at least eight line-detector units； a first part as first analyser-gratings with slits in the first direction, and a second part as second analyser-gratings with slits in the second direction. At least four adjacent lines of the line-detector units are associated with the first phase-gratings and the first analyser-gratings and at least four adjacent lines of the line-detector units are associated with the second phase-gratings and the second analyser-gratings. The grating arrangement may comprise a source-grating structure arranged between the X-ray source and the phase-grating structure, to provide sufficient coherence to the X-ray beam passing the source-grating structure,
