Method for calibrating a radiation penetration system comprising a radiation source, a flat-panel detector for generating radiation penetration raw images of an object, a manipulator which is implemented to change a relative position between the radiation source, the object and the flat-panel detector, wherein the axes system is defined by at least one movement axis of the manipulator and one beam axis between the radiation source and the flat-panel detector, and a preprocessor for applying correction data to the radiation penetration raw images of the object to obtain radiation penetration images of the object, comprising generating radiation penetration raw images of a calibration object in different relative positions changed with respect to each other by the manipulator between the radiation source, the calibration object and the flat-panel detector on the basis of radiation which penetrates the calibration object between the radiation source and the flat-panel detector, by the flat-panel detector; and readjusting the correction data depending on the radiation penetration raw images of the calibration object so that the application of the readjusted correction data leads to a geometrical correction of the radiation penetration raw images, so that a change of a projection of the object in the radiation penetration raw image due to a position error of the flat-panel detector in the axes system relative to a necessitated position is reduced, wherein the position error of the flat-panel detector is defined as a tilting of an image plane of the flat-panel detector from a perpendicular orientation to a beam axis between the radiation source and the flat-panel detector, or a tilting of a column or line direction of the flat-panel detector relative to a rotation or translation positioning axis of the manipulator, or a tilting of the column or line direction of the flat-panel detector relative to a trajectory along which the flat-panel detector moves relative to the object between the plurality of radiation penetration raw images, characterized in that the preprocessor applies the correction data to the radiation penetration raw images of the object so that radiation penetration images of the object obtained therefrom comprise a lower resolution than the radiation penetration raw images of the object and that readjusting executes a readjustment of the correction data depending on the radiation penetration raw images of the calibration object such that applying the readjusted correction data leads to a geometrical correction of the radiation penetration raw images of the object, the geometrical correction taking place in a resolution which is higher than the resolution of the radiation penetration images of the object. a tilting of an image plane of the flat-panel detector from a perpendicular orientation to a beam axis between the radiation source and the flat-panel detector, or a tilting of a column or line direction of the flat-panel detector relative to a rotation or translation positioning axis of the manipulator, or a tilting of the column or line direction of the flat-panel detector relative to a trajectory along which the flat-panel detector moves relative to the object between the plurality of radiation penetration raw images,