A 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 acquire 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 required position is reduced, wherein the position error of the flat-panel detector is defined as 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. 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 required position is reduced, wherein the position error of the flat-panel detector is defined as 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. 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.