Abstract: The invention relates to a computed tomography apparatus in which the measuring data acquired in a first measuring window enter the reconstruction with a weight other than that of the measuring data that can be acquired in a second measuring window, the second measuring window being situated centrally relative to the first measuring window and being smaller than the first measuring window. Depending on the weighting of the measuring data, the resultant CT image exhibits either smaller motional artefacts or a spatially more uniform noise.

Abstract: The invention relates to a computed tomography method in which a rebinning operation is carried out so as to form parallel fan beams whose rays traverse a plane, containing the axis of rotation, in equidistant puncture points. Reconstruction is performed for rays which extend perpendicularly to said planes. Such a transition from a cone beam geometry to a parallel beam geometry enables very fast reconstruction which can be carried out notably for CT fluoroscopy.

Abstract: The invention relates to a computed tomography apparatus in which measuring data of a patient is acquired along a helical trajectory by means of a conical radiation beam. The size of the detector window is then a factor of 3, 5, 7 . . . larger than the distance between neighboring turns of the helix. In order to select from among the acquired redundant data the data which is suitable for completely filling the Radon domain so as to achieve exact reconstruction, in accordance with the invention it is proposed to provide a cardiac motion signal detection device for the detection of a cardiac motion signal representing the cardiac motion and to arrange the reconstruction unit so as to select such measuring data from among the measuring data regionally redundantly filling the Radon domain that the Radon domain is completely and homogeneously filled with measuring data from cardiac motion phases with as little motion as possible.

Abstract: A fluoroscopy intervention method to obtain an image of an object (11) together with radiopaque intervention means (30), the method using a rotating cone-beam X-ray source (8,9) and a corresponding two-dimensional X-ray detector (6) with the object (11) and the intervention means (30) positioned between the X-ray source (8) and the X-ray detector (6). Due to a cone-beam acquisition and a multi-slice reconstruction (9′) the intervention means (30) can have a substantial angulation with respect to the image slices (9′), providing the operator's hand (4) being outside the primary X-ray beam (9). This reduces the X-ray dose the operator. By providing additional lighting means (60), delineating the primary X-ray source at its periphery, the operator is supplied with an information about the spatial position of the X-ray radiation. The lighting means (60) can be further used to position an X-ray shield (65) of a surface of the patient to reduce the X-ray dose due to scattered radiation.

Abstract: A fluoroscopy intervention method to obtain an image of an object (11) together with radiopaque intervention means (30), the method using a rotating cone-beam X-ray source (8,9) and a corresponding two-dimensional X-ray detector (6) with the object (11) and the intervention means (30) positioned between the X-ray source (8) and the X-ray detector (6). Due to a cone-beam acquisition and a multi-slice reconstruction (9′) the intervention means (30) can have a substantial angulation with respect to the image slices (9′), providing the operator's hand (4) being outside the primary X-ray beam (9). This reduces the X-ray dose the operator. By providing additional lighting means (60), delineating the primary X-ray source at its periphery, the operator is supplied with an information about the spatial position of the X-ray radiation. The lighting means (60) can be further used to position an X-ray shield (65) of a surface of the patient to reduce the X-ray dose due to scattered radiation.

Abstract: The invention relates to a computed tomography apparatus in which measuring data of a patient is acquired along a helical trajectory by means of a conical radiation beam. The size of the detector window is then a factor of 3, 5, 7 . . . larger than the distance between neighboring turns of the helix. In order to select from among the acquired redundant data the data which is suitable for completely filling the Radon domain so as to achieve exact reconstruction, in accordance with the invention it is proposed to provide a cardiac motion signal detection device for the detection of a cardiac motion signal representing the cardiac motion and to arrange the reconstruction unit so as to select such measuring data from among the measuring data regionally redundantly filling the Radon domain that the Radon domain is completely and homogeneously filled with measuring data from cardiac motion phases with as little motion as possible.

Abstract: The invention relates to a computed tomography method for forming images of an object to be examined which is arranged in an examination zone. The examination zone is scanned by means of a conical X-ray beam.

Abstract: The reconstruction in Cone-beam CT scanner requires a high accuracy of the tabletop (1) position determination. In sequential as well as in helical acquisitions projection data (20) from different tabletop (1) positions are combined. Additional position markers, manufactured as insertions (10) of a contrast material relative to the material of the tabletop (1), are introduced into the tabletop (1). These insertions (10) allow the determination of the true position of the tabletop (1) from projection data. This information can be used to either control the scanner mechanics or as a correction information for the reconstruction process.

Abstract: The reconstruction in Cone-beam CT scanner requires a high accuracy of the tabletop (1) position determination. In sequential as well as in helical acquisitions projection data (20) from different tabletop (1) positions are combined. Additional position markers, manufactured as insertions (10) of a contrast material relative to the material of the tabletop (1), are introduced into the tabletop (1). These insertions (10) allow the determination of the true position of the tabletop (1) from projection data. This information can be used to either control the scanner mechanics or as a correction information for the reconstruction process.

Abstract: The invention relates to a computed tomography apparatus in which the measuring data acquired in a first measuring window enter the reconstruction with a weight other than that of the measuring data that can be acquired in a second measuring window, the second measuring window being situated centrally relative to the first measuring window and being smaller than the first measuring window. Depending on the weighting of the measuring data, the resultant CT image exhibits either smaller motional artefacts or a spatially more uniform noise.

Abstract: An imaging modality, in particular a mobile CT system, comprises an imaging system for imaging an object to be examined. The imaging modality is also provided with an image guided surgery system which includes a position measuring system for measuring positions within the object and a data processor for deriving a transformation between positions within the object and the corresponding positions in the image. The position measuring device is also arranged to measure the position of the imaging system and the data processor is arranged to derive the transformation from the position and/or orientation of the imaging system. The position measuring system is notably an optical position measuring system which is arranged to measure the position of the gantry of the CT system. The data processor is arranged to derive the transformation from the measured position of the gantry.

Abstract: The invention relates to a method of forming a scannogram for a computed tomography apparatus. During the acquisition of the measured values for the scannogram, the scanning unit or the radiation source rotates about the examination zone and a 3D data set is reconstructed from the measured values acquired during the acquisition. A synthetic projection image which acts as the scannogram can be calculated from such a 3D data set.

Abstract: A computed tomography system includes a gantry provided with an examination opening. The computed tomography system is provided with a position measuring system for measuring the position of the gantry. Preferably, an optical position measuring system which includes a camera unit is employed. The camera unit is suspended from a suspension point above the gantry.

Abstract: The invention relates to a computed tomography apparatus whose radiation source emits a conical radiation beam and is capable of scanning the examination zone along a trajectory in the form of a helix. The detector unit that is connected to the radiation source consists of a plurality of spatially separated detector segments that are mutually offset in the axial direction and each of which is arranged in such a manner that a projection onto the helix covers at least two neighboring turns of the helix. A CT image having an improved and spatially more uniformly distributed signal-to-noise ratio can be reconstructed from the CT data acquired by means of such a detector unit.

Abstract: The invention relates to a computed tomography method which involves a conical radiation beam which irradiates the examination zone along at least two trajectories that are offset relative to one another in the direction of the axis of rotation, the distance between the trajectories being chosen to be so large that voxels in an intermediate region are not completely irradiated neither in one trajectory nor in the other trajectory. The absorption distribution in this intermediate region can be reconstructed without loss of image quality when measuring data from both trajectories are combined.

Abstract: Method and device for forming a 3D image of an object to be examined by combining at least two reconstruction images, acquired by an X-ray device, by weighted addition. Specifically, each reconstruction image is weighted with a respective weighting function which describes at least approximately the distribution of noise and/or the distribution of artifacts in the reconstruction image. The image quality of the resultant three-dimensional image is thus significantly improved.

Abstract: The invention relates to a computed tomography apparatus whose radiation source emits a conical radiation beam and is capable of scanning the examination zone along a trajectory in the form of a helix. The detector unit that is connected to the radiation source consists of a plurality of spatially separated detector segments that are mutually offset in the axial direction and each of which is arranged in such a manner that a projection onto the helix covers at least two neighboring turns of the helix. A CT image having an improved and spatially more uniformly distributed signal-to-noise ratio can be reconstructed from the CT data acquired by means of such a detector unit.

Abstract: The invention relates to a computed tomography method which involves a conical radiation beam which irradiates the examination zone along at least two trajectories that are offset relative to one another in the direction of the axis of rotation, the distance between the trajectories being chosen to be so large that voxels in an intermediate region are not completely irradiated neither in one trajectory nor in the other trajectory. The absorption distribution in this intermediate region can be reconstructed without loss of image quality when measuring data from both trajectories are combined.

Abstract: The invention relates to a method of forming a scannogram for a computed tomography apparatus. During the acquisition of the measured values for the scannogram, the scanning unit or the radiation source rotates about the examination zone and a 3D data set is reconstructed from the measured values acquired during the acquisition. A synthetic projection image which acts as the scannogram can be calculated from such a 3D data set.

Abstract: The invention relates to an imaging method for medical examinations, notably MR examinations, in which a set of measurement values is acquired from measuring points which are irregularly distributed in the frequency domain (or in the k-space). Before an image in the space domain is generated from these measurement values by a Fourier transformation, the measurement values must be weighted in dependence on the density of the measuring points in the frequency domain. To this end, the measurement values are weighted in conformity with the magnitude of the Voronoi cells.