A device for slot scanning phase contrast x-ray imaging, includes an x-ray emitter, a plurality of x-ray gratings, a patient couch, and an x-ray detector. Position marker elements are arranged and configured in the beam path of the x-ray emitter such that the position marker elements are visible in an x-ray image. In the x-ray image, a relative position of an object on the patient couch in relation to an x-ray beam fan of the x-ray emitter may be established from a location and a distance of the position marker elements from one another.