Abstract: A method and a device for determining attenuation coefficients for an object using a movable X-ray source and a detector, which is provided for recording projections, is provided. The method includes specifying a trajectory for the movable X-ray source, specifying positions on the trajectory for determining a derivative of projections recorded by the detector, specifying a plurality of scanning positions for each of the specified positions, following the trajectory with the X-ray source and recording a projection for each scanning position, numerically calculating a projection derivative in relation to the trajectory path for each of the positions using the projections recorded for the associated plurality of scanning positions, and determining attenuation coefficients for the object from the calculated projection derivatives using a theoretically exact or approximate rule for the reconstruction.

Abstract: A method for determining absorption coefficients corrected with polychromy artifacts for an object composed of a plurality of material types differentiated with absorption attributes is provided. A plurality of x-ray beam projections of the object are recorded with monochrome x-rays from different positions. The recorded projections are reconstructed to determine a first set of absorption coefficients. The projections are calculated by reprojection. The recorded projections are corrected by the calculated projections. A second set of absorption coefficients corrected with polychromy artifacts is finally determined by reconstructing the corrected projections. A formula-based description of a rule taking account of polychromy is used in the calculation. The rule includes parameters to be determined by the reprojection in the course of the calculation of projections. The method combines steps of conventional methods and is thus more efficient.

Abstract: A method for determining attenuation coefficients for an object using a movable x-ray source and a detector for recording projections is provided. The method includes defining a trajectory for the movable x-ray source, defining filtering lines for the filtering of projection data, and defining positions on the filtering lines, at which the projection derivative is to be formed using a mathematical algorithm for a back-projection. The method also includes defining sampling positions on the trajectory, traversing, by the x-ray source, the trajectory and recording a projection for each sampling position. Projection derivatives with respect to the trajectory path are calculated numerically for each of the positions directly on the filtering lines, and using a mathematical algorithm, attenuation coefficients are determined for the object from the calculated projection derivatives, for the reconstruction.

Abstract: In a method and device spatially resolved quality information is provided for an x-ray imaging procedure in which a data field representing the examination subject is reconstructed from a number of exposures of an examination subject. Quality information that indicates the reliability of the reconstructed data field for the corresponding element is determined for a number of elements of the data field.

Abstract: A method for determining absorption coefficients corrected with polychromy artifacts for an object composed of a plurality of material types differentiated with absorption attributes is provided. A plurality of x-ray beam projections of the object are recorded with monochrome x-rays from different positions. The recorded projections are reconstructed to determine a first set of absorption coefficients. The projections are calculated by reprojection. The recorded projections are corrected by the calculated projections. A second set of absorption coefficients corrected with polychromy artifacts is finally determined by reconstructing the corrected projections. A formula-based description of a rule taking account of polychromy is used in the calculation. The rule includes parameters to be determined by the reprojection in the course of the calculation of projections. The method combines steps of conventional methods and is thus more efficient.

Abstract: A method for determining attenuation coefficients for an object using a movable x-ray source and a detector for recording projections is provided. The method includes defining a trajectory for the movable x-ray source, defining filtering lines for the filtering of projection data, and defining positions on the filtering lines, at which the projection derivative is to be formed using a mathematical algorithm for a back-projection. The method also includes defining sampling positions on the trajectory, traversing, by the x-ray source, the trajectory and recording a projection for each sampling position. Projection derivatives with respect to the trajectory path are calculated numerically for each of the positions directly on the filtering lines, and using a mathematical algorithm, attenuation coefficients are determined for the object from the calculated projection derivatives, for the reconstruction.

Abstract: A method and a device for determining attenuation coefficients for an object using a movable X-ray source and a detector, which is provided for recording projections, is provided. The method includes specifying a trajectory for the movable X-ray source, specifying positions on the trajectory for determining a derivative of projections recorded by the detector, specifying a plurality of scanning positions for each of the specified positions, following the trajectory with the X-ray source and recording a projection for each scanning position, numerically calculating a projection derivative in relation to the trajectory path for each of the positions using the projections recorded for the associated plurality of scanning positions, and determining attenuation coefficients for the object from the calculated projection derivatives using a theoretically exact or approximate rule for the reconstruction.

Abstract: An improvement in image quality when determining an image using iterative reconstruction is provided by taking account of focus shifts. In order to take into consideration the influence of focus shift in calculated projections, several different projections are calculated for each section of the focus path on a section-by-section basis. The several different calculated projections for a section are averaged for comparison with a projection recorded in the section. Improved image quality is provided, for example, in tomosynthesis applications in which a large number of recordings are made with a stationary detector.

Abstract: To enable an artifact free reconstruction even in the case of large regions of interest and with scanning paths of below 360°, provision is made for a method, with which a three-dimensional image volume is reconstructed from a number of two-dimensional projection images of a region of interest, which were recorded about the region of interest during a rotation of a recording system, comprising an x-ray source with a focal point and a detector, by calculating the gray scale values of the voxels of the image volume by back projection of the projection images, with which each two-dimensional projection images is composed in each instance from at least two individual projection images to form an extended two-dimensional projection image, with the respectively at least two individual projection images being recorded with a constant relative position between the focal point and the region of interest.

Abstract: To enable an artifact free reconstruction even in the case of large regions of interest and with scanning paths of below 360°, provision is made for a method, with which a three-dimensional image volume is reconstructed from a number of two-dimensional projection images of a region of interest, which were recorded about the region of interest during a rotation of a recording system, comprising an x-ray source with a focal point and a detector, by calculating the gray scale values of the voxels of the image volume by back projection of the projection images, with which each two-dimensional projection images is composed in each instance from at least two individual projection images to form an extended two-dimensional projection image, with the respectively at least two individual projection images being recorded with a constant relative position between the focal point and the region of interest.