An X ray system (2) for acquiring an image of an object has an X ray detector (8) which is segmented into a plurality of neighboring detector tiles. In particular the image can be a two dimensional projection image but also a three dimensional volume of the object reconstructed from a tomosynthesis acquisition. An X ray detector moving mechanism (18) is adapted for moving the X ray detector (8) at least between a first X ray detector position and a second X ray detector position during operation of the X ray system. An X ray source (4) a collimator (22) and the X ray detector (8) of the X ray system (2) are adapted for acquiring a plurality of partial X ray images through the adjacent detector tiles while irradiating the object with X ray beams from a plurality of tomographic angles a. The processing unit is adapted for generating a two dimension image of the object and/or for reconstructing a three dimensional volume of the object from the acquired partial images.
