摘要:
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.
摘要:
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.
摘要:
The invention relates to a method for performing computer tomography, and to a computed tomography (CT) apparatus, in which a) for scanning an object by a cone-shaped beam exiting from a focal point and by a matrix-like detector array for detecting the beam, the focal point is moved in relation to the object on a spiral path, whose center axis corresponds to a system axis, and the detector array provides output data corresponding to the received radiation; and b) for imaging an object region that executes a periodic motion, a signal that reproduces the course over time of the periodic motion is obtained during the scanning; c) from output data furnished during the motion of the focal point on a spiral segment, images with an inclined image plane are reconstructed, the image planes being inclined relative to the system axis both about a first axis, which perpendicularly intersects the system axis, by an angle of inclination &ggr; and about a second axis, which perpendicularly intersects both the first axis and the system axis, by a tilt angle &dgr;; and spiral segments that immediately succeed one another overlap one another by an overlap angle that is greater than or equal to zero; and the spiral segments are selected, taking into account the signal that reproduces the course over time of the periodic motion, such that they correspond to a phase of the periodic motion that is to be imaged.
摘要:
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 γ around a first axis intersecting the system axis at a right angle and also are inclined by a tilt angle δ 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.
摘要:
An imaging method is for a multi-slice spiral CT scan with 3D back projection. Use is made, for the reconstruction of the absorption value of at least one voxel, of the measured and filtered data that are produced by rays which penetrate the at least one voxel. A CT unit is further used to carry out the method. In the method, the filtering of the data, required for the reconstruction, in the image of the virtual detector is performed in the direction of the projection of spiral segments imaged thereon which are produced by the spiral scanning over a prescribed angular range. The CT unit includes a device for carrying out directional filtering of this type.
摘要:
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.
摘要:
A method is disclosed for production of tomographic slice images of an examination object using a computed tomography scanner. In order to scan an examination object, at least two X-ray beams are produced, which each are at offset angles and fan out from a focus to an opposite detector and scan the examination object. The scans at least partially overlap. Detector output data which is emitted from the detector elements is measured together with physical orientation data of the beams and is converted to projection data sets. Slice images are then calculated. In order to calculate the complete slice images, data which is redundant from the measured data of the at least two X-ray beams from overlapping projection intervals is used for each complete slice image. The size of the overlap area of the projection data used from the individual X-ray beams is defined before the calculation of the slice images, in order to vary time resolution and image quality.
摘要:
A method is disclosed for production of tomographic slice images of an examination object using a computed tomography scanner. In order to scan an examination object, at least two X-ray beams are produced, which each are at offset angles and fan out from a focus to an opposite detector and scan the examination object. The scans at least partially overlap. Detector output data which is emitted from the detector elements is measured together with physical orientation data of the beams and is converted to projection data sets. Slice images are then calculated. In order to calculate the complete slice images, data which is redundant from the measured data of the at least two X-ray beams from overlapping projection intervals is used for each complete slice image. The size of the overlap area of the projection data used from the individual X-ray beams is defined before the calculation of the slice images, in order to vary time resolution and image quality.
摘要:
A method is disclosed for a multislice computer assisted tomograph, capable of carrying out a spiral scan of an object volume with a pitch p selected to be small enough that each slice of the object volume is multiply detected during the spiral scan. The method includes calculating, using measured data of two temporally consecutive at least one of revolutions and half revolutions, an image of the object volume from which a change inside the object volume between the two temporally consecutive at least one of revolutions and half revolutions is directly visible. An embodiment of the method can permit, for example, the detection and visualization of dynamic processes with an enhanced time resolution.
摘要:
A detector for x-ray computer tomography scanners, includes a number of adjacent detector lines extending in an x direction, whereby each detector line is formed from a multitude of adjacent scintillator elements. In order to increase the resolution in the z direction and to simplify the design of the detector, the surface of the scintillator elements are partially covered, which further serves to reduce the size of the aperture in the z direction.