Abstract: A method is for image reconstruction for computed tomography with a non-one-dimensional, extended detector. The rays of the detector are weighted during the backprojection as a function of their position in the beam.

Abstract: A method is for imaging in computer tomography, in which a periodically moved object to be examined is scanned with the aid of a beam of rays coming from a focus. A two-dimensionally designed detector array generates output data which are filtered in a suitable way and back-projected in order to obtain at least one sectional image which represents the absorption values of the section of the object to be examined in a particular movement state. In the method, on the one hand, a weighting function which weights the spatial distance of a ray in question from the voxel in question is used for the back-projection. Further, on the other hand, a weighting function which represents the time difference from the examination area movement state to be represented in each case is also used.

Abstract: A method is for window-controlled filtering of CT images. A CT raw data record is acquired, for example, with the aid of a CT unit or of a C-arc unit. A primary data record is then reconstructed from the CT raw data record by way of, for example, a sharp convolution core and, for example, a narrow slice sensitivity profile. A transfer function is then provided as functional relationship between window width and image sharpness. The image sharpness of the CT image of a selected slice is then automatically calculated, situated in the primary data record, as a function of a selected window width for the selected slice by way of an image processing procedure on the basis of the transfer function.

Abstract: A method is for organ-specific image optimization in computed tomography. In this case, the HU values of a layer of the body previously recorded with a CT device are calculated and, on this basis, a first CT image is created. For this first CT image, a histogram is also created, in which the frequency distribution of the HU values is reproduced. In a histogram, at least one organ-specific HU region is defined and the latter is allocated an HU-dependent transfer function. Furthermore, a second CT image is created on the basis of the previously calculated HU values for the layer of the body which has been recorded. The first and second CT image are filtered with the HU-dependent transfer function and, finally, the filtered first CT image is mixed with the filtered second CT image.

Abstract: In a spiral scan cone beam computed tomography method and apparatus, the output data are divided into sub-segments being shorter than the length required for the reconstruction of a CT image. Segment images having inclined image plane relative to the system axis are reconstructed for the sub-segments. A signal reproducing the time curve of the periodic motion is acquired during the scanning. A z-position on the system axis and a time position with respect to the periodic motion are allocated to the segment images. Segment images belonging to a desired range of z-positions and a desired range of time positions are selected such that the corresponding sub-segments have an overall length adequate for the reconstruction of a CT image. The selected segment images are at least indirectly combined into a resulting CT image with respect to a target image plane.

Abstract: In a method and apparatus for computed tomography, a subject is scanned with a conical ray beam emanating from a focus and the attenuated beam is detected with a matrix-like detector array. The focus is moved on a spiral path around a system axis relative to the subject, and the detector array supplies output data corresponding to the received radiation. The output data are supplied during the motion of the focus on a spiral segment and have a length adequate for the reconstruction of a CT image, and are divided into output datasets with respect to sub-segments. Segment images having an inclined image plane relative to the system axis are reconstructed for the sub-segments. The segment images respectively belonging to the sub-segments are combined into a partial image with respect to a target image plane, and the partial images are combined into a resulting CT image with respect to the target image plane.

Abstract: In a computed tomography system equipped with a data-acquisition system and a method for operating such a computed tomography system, the computed tomography system has a radiation detector with at least one linear detector array composed of a row several detector elements aligned adjacent to one another. The data-acquisition system reads out the detector elements and forms difference signals from signals read out from pairs of adjacent detector elements.

Abstract: A method for correcting stray radiation for measured values of intensity is proposed that are obtained in an X-ray computer tomography scanner by means of a detector matrix that is situated in a tomography measuring field of the computer tomography scanner and has a multiplicity of detector elements arranged next to one another in a plurality of superimposed detector rows. According to the invention, it is provided in this case that firstly at least one reference distribution of the stray radiation intensity is determined in the row direction of the detector matrix, and that then a stray radiation component of each measured value of intensity is determined starting from this at least one reference distribution, and the measured values of intensity are corrected as a function of their respective stray radiation component.

Abstract: A method for computed tomography, includes, in order to scan an object to be examined with a conical beam originating from a focus and with a matrix-like detector array for detecting the beam, the focus is moved, relative to the object to be examined, on a focal path around a system axis. A detector array supplies an output data corresponding to received radiation. The output data is filtered, and the filtered output data is backprojected three-dimensionally in order to produce at least one slice of a layer of the, which has a layer thickness. The slice represents absorption values obtained from the output data of a voxel belonging to the layer for the radiation from the beam. Filtering is carried out at least also in the direction of the tangent to the focal path belonging to a respective focal position, and normalization is carried out for each voxel considered.

Abstract: In an image reconstruction method for imaging a periodically moving object with a computed tomography apparatus employing a multi-line detector unit, suitable selection of the rotational speed of the carrier of the computed tomography apparatus and employment of a three-dimensional back-projection algorithm, allow qualitatively high-great images of the object to be produced in every motion phase.

Abstract: In a computed tomography method and apparatus, having a subject with a conical ray beam emanating from a focus and with a matrix-like detector array for detecting the ray beam, while the focus is moved on a spiral path around a system axis relative to the subject, and the detector array supplies output data corresponding to the received radiation. The output data respectively supplied during the motion of the focus on a spiral segment and having a length adequate for the reconstruction of a CT image are divided into output data with respect to sub-segments, with the length of each sub-segments being shorter than the length required for the reconstruction of a CT image. Segment images having an inclined image plane relative to the system axis are reconstructed for the sub-segments. A signal reproducing the time curve of the periodic motion is acquired during the scanning. A z-position on the system axis and a time position with respect to the periodic motion are allocated to the segment images.

Abstract: In a method and filter and computer product for adaptive filtering of projection data acquired by a medical diagnostic apparatus, raw data-based filtering of the acquired projection data is undertaken using a filter with a filter kernel having a constant filter width, and the filtered projection data are mixed with the acquired projection data with a fixing of the respective quantitative relationships of filtered projection data to acquired projection data ensuing dependent on respective subsets of the acquired projection data.

Abstract: In a method and apparatus for computed tomography, a subject is scanned with a conical ray beam emanating from a focus and the attenuated beam is detected with a matrix-like detector array. The focus is moved on a spiral path around a system axis relative to the subject, and the detector array supplies output data corresponding to the received radiation. The output data are supplied during the motion of the focus on a spiral segment and have a length adequate for the reconstruction of a CT image, and are divided into output datasets with respect to sub-segments. Segment images having an inclined image plane relative to the system axis are reconstructed for the sub-segments. The segment images respectively belonging to the sub-segments are combined into a partial image with respect to a target image plane, and the partial images are combined into a resulting CT image with respect to the target image plane.

Abstract: In a method and apparatus for three-dimensional imaging of a moving examination subject, particularly heart imaging with an examination apparatus having at least one C-arm with a radiation source and a radiation receiver, the C-arm rotates around the examination subject at least once through 180° plus the radiation fan angle during the time span in which a contrast agent is in the examination subject for the registration of the two-dimensional projection images, on the basis of which a three-dimensional image reconstruction ensues.

Abstract: In a method for computed tomography and a computed tomography apparatus for scanning a subject with a conical ray beam emanating from a focus that detects a matrix-like detector array, the focus is moved relative to the subject on a spiral path around a system axis, and the detector array supplies output data corresponding to the incident radiation, and images having an inclined image plane are reconstructed from output data respectively supplied during the movement of the focus on a spiral segment, the image planes of these images are inclined by an inclination angle &ggr; around a first axis intersecting the system axis at a right angle and also are inclined by a tilt angle &dgr; with respect to the system axis around a second axis that intersects the first axis as well as the system axis at a right angle.

Abstract: A system and method for 3D image reconstruction in a spiral scan cone beam computed tomography (CT) imaging system that allows the pitch of spiral scan projection to be reduced by a factor of 1/n (where n=3, 5, 7, 9, etc), thereby increasing the x-ray dosage to obtain a higher S/N (signal-to-noise) ratio, while achieving efficient use of a fixed-size detector. In addition, an image reconstruction protocol computes a correction factor for integration planes that intersect the reduced-pitch spiral path (which surrounds a ROI) at only M<n locations within an angular range that is determined, e.g., for M=1 planes, based on mask boundaries applied to the cone beam data. Despite the reduced pitch, the M<n integration planes do not provide increased flux (in contrast to other integration planes that intersect the object and scan path in M∃n locations).

Abstract: An x-ray diagnostic device has an x-ray source, with a two dimensional detector arranged opposite thereto for detecting x-rays emitted from the x-ray source as a conical x-ray beam, and with a positioning device for an examination subject arranged between the x-ray source and the detector. The x-ray source in tandem with the detector can be rotated in an oscillating manner around a system axis. The x-ray source and the detector, and the positioning device are linearly adjustable relative to one another substantially in the direction of the system axis and a computer reconstructs images of the examination subject from the output signals of the detector occurring thereby.

Abstract: In a method and apparatus for reducing line artifacts in a CT image D1, which is acquired during a scan by a CT device with a detector system having a number of proper detector channels and at least one defective detector channel, the image M1 is obtained first by a median filtering the image D1, which contains a circle artifact on a circle K1. A difference value image F1=D1−M1 is then produced. Filtering then is carried out in each picture element of the image F1 in the direction of the tangents t11 and t21 to the circle K1 extending through the respective picture element in order to produce two resulting images G11 and G21. A correction image D2 is subsequently produced by subtracting the resulting images G11 and G21 from D1.

Abstract: In a computed tomography system equipped with a data-acquisition system and a method for operating such a computed tomography system, the computed tomography system has a radiation detector with at least one linear detector array composed of a row several detector elements aligned adjacent to one another. The data-acquisition system reads out the detector elements and forms difference signals from signals read out from pairs of adjacent detector elements.

Abstract: In a method and apparatus for reducing line artifacts in a CT image D1, which is acquired during a scan by a CT device with a detector system having a number of proper detector channels and at least one defective detector channel, the image M1 is obtained first by a median filtering. the image D1, which contains a circle artifact on a circle K1. A difference value image F1=D1−M1 is then produced. Filtering then is carried out in each picture element of the image F1 in the direction of the tangents t11 and t21 to the circle K1 extending through the respective picture element in order to produce two resulting images G11 and G21. A correction image D2 is subsequently produced by subtracting the resulting images G11 and G21 from D1.