1. A mammography X-ray system for acquiring an image of an object, the system comprising: an X-ray source, an X-ray detector, a collimator, an X-ray source moving mechanism, an X-ray detector moving mechanism, and a processing unit, wherein the X-ray source moving mechanism is adapted for moving the X-ray source into different tomographic angles α relative to a detection surface of the X-ray detector, wherein the X-ray detector is segmented into a plurality of neighboring detector tiles wherein delimiting edges of neighboring detector tiles are distanced to each other, wherein the distance is the width of a detector tile or less, wherein the X-ray detector moving mechanism is adapted for moving the X-ray detector at least between a first X-ray detector position and a second X-ray detector position during operation of the X-ray system, and wherein the X-ray source, the collimator and the X-ray detector are adapted for acquiring a plurality of partial X-ray images through the neighboring detector tiles while irradiating the object with X-ray beams from a plurality of tomographic angles α, wherein the processing unit is adapted for reconstructing an image of the object from the acquired partial images.