Abstract: A method for determining assignment data is carried out in a method for determining a geometry calibration. The 3D calibration phantom features a calibration object with a number of calibration elements, which are arranged so that a descriptor based on the spatial arrangement is projectively invariant. Based upon the descriptor the calibration elements mapped in the 2D transmission element can be assigned to the calibration elements of the calibration object, so that the geometry calibration is determined on the basis of this assignment and the arrangement of the calibration elements in the three-dimensional space as well as on the 2D image.

Abstract: A method for determining assignment data is carried out in a method for determining a geometry calibration. The 3D calibration phantom features a calibration object with a number of calibration elements, which are arranged so that a descriptor based on the spatial arrangement is projectively invariant. Based upon the descriptor the calibration elements mapped in the 2D transmission element can be assigned to the calibration elements of the calibration object, so that the geometry calibration is determined on the basis of this assignment and the arrangement of the calibration elements in the three-dimensional space as well as on the 2D image.

Abstract: A method for reducing image artifacts caused, for example, by beam hardening includes acquiring at least two projections of a transirradiated object are acquired from different perspectives by an X-ray emitter and an X-ray detector defining a projection plane. A correction model that is linear in parameters and is valid for the at least two projections is determined. At least two epipolar lines corresponding to a common epipolar plane are identified in the projection planes of the at least two projections. The parameters of the correction model are determined by optimization, taking account of data terms that are independent of the parameters. The data terms quantify a consistency condition of the at least two projections that applies to the epipolar lines. Artifact-reduced image data is determined based on the determined parameters.

Abstract: A method for reducing image artifacts caused, for example, by beam hardening includes acquiring at least two projections of a transirradiated object are acquired from different perspectives by an X-ray emitter and an X-ray detector defining a projection plane. A correction model that is linear in parameters and is valid for the at least two projections is determined. At least two epipolar lines corresponding to a common epipolar plane are identified in the projection planes of the at least two projections. The parameters of the correction model are determined by optimization, taking account of data terms that are independent of the parameters. The data terms quantify a consistency condition of the at least two projections that applies to the epipolar lines. Artifact-reduced image data is determined based on the determined parameters.