Siemens Aktiengesellschaft

Karl Schwarz

Thomas Flohr

Herbert Bruder

Karl Stierstorfer

Rainer Raupach

Martin Petersilka

Bernd Ohnesorge

Helmut Kropfeld

Johan Sunnegardh

Annabella Rauscher

A method, a computation unit and a CT system are disclosed for reconstructing CT image data, which includes a plurality of image voxels, by way of a weighted filtered back-projection. To weight the projection data during the filtered back-projection, a weight function is used, which weights the projection data from central beams which strike a detector row relatively close to the edge of the row relatively less, and which weights the projection data of central beams, which strike a detector row more relatively centrally, relatively more.

Method for reconstructing CT image data with weighted backprojection, including computation unit and CT system for the method

A method is disclosed for reconstructing image data of an examination object from measured data, wherein the measured data was captured previously during a relative rotary motion between a radiation source of a computed tomography system and the examination object. In at least one embodiment, the measured data is modified to achieve a particular grayscale characteristic of the image data to be reconstructed. The image data is calculated by way of an iterative algorithm using the modified measured data, wherein no arithmetic step for reducing noise is employed in the iterations.

Iterative reconstruction of CT images without a regularization term

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.

Method of creating images in computed tomography (CT), and CT device

An imaging method is disclosed for variable pitch spiral CT. In at least one embodiment, the method includes spiral scanning of an examination object lying on a patient table, with the aid of a beam emanating from at least one focus, and the aid of a detector arrangement of planar design lying opposite the focus, the detector arrangement supplying output data that represent the attenuation of the beams during passage through the examination object; filtering the output data; weighted back projection of the filtered output data; and visualizing a layer or a volume on a display unit on the basis of the back projected output data. In at least one embodiment, a non constant pitch of the spiral scanning is taken into account computationally during the back projection. In at least one embodiment, a CT machine is disclosed for carrying out the above named method.

Imaging method for variable pitch spiral CT and a CT machine for carrying out the method

A method is disclosed for compiling computer tomographic representations using a CT system with at least two angularly offset ray sources. A first ray cone with a relatively larger fan angle and a second ray cone with a relatively smaller fan angle scan an object circularly or spirally. The first ray cone generates a first dataset A and the second ray cone generates a dataset B. The dataset B of the smaller ray cone is supplemented with other data at the edge to give an expanded dataset B+ for reconstruction of the CT representation. The expanded dataset B+ of the second, smaller ray cone and the dataset A of the first, larger ray cone is subjected to a convolution operation to give datasets B+' and A&#x2032;. Finally, a back projection to reconstruct sectional images or volume data is respectively carried out from the convoluted datasets B+&#x2032; and A&#x2032;. The dataset B is supplemented with data of the dataset A and supplementary data are removed from the dataset B+&#x2032; after the convolution but before the back projection.

Method for compiling computer tomographic representations using a CT system with at least two angularly offset ray sources

In a method for correcting a calibration table T(n,k) of a CT apparatus that contains calibration values, the CT apparatus having a detector system with N&gE;2 rows of detector elements following one another in the z-direction that include a first active row of detector elements in the z-direction and a last active row of detector elements in the z-direction, for correcting the calibration values of the aforementioned first and last active rows of detector elements, a reference vector R(k) is produced, the error is determined with respect to the first and last active rows of detector elements, and the error F(n,k) of the first and last active rows of detector elements is subtracted from the corresponding calibration values of the calibration table T(n,k) for determining corrected calibration values T (n,k) with respect to the first and last active rows of detector elements.

Method for correcting calibration values in a calibration table of computed tomography apparatus

In a computed tomography (CT) device for generating tomograms of slices of an examination object, which are inclined relative to the longitudinal axis of a patient support plate that is provided for an examination subject, the gantry of the CT device and the support plate can be tilted relative to one another and in the tilted state, the support plate and the gantry can be linearly adjusted relative to one another substantially in the direction of the system axis of the CT device for generating a relative movement between the gantry and the support plate.

CT device for generating tomograms of slices of a subject which are inclined relative to the longitudinal axis of a patient support

In a method for image reconstruction in a computed tomography (CT) device, which picks up projections of a region located in a measuring field of an examination subject having an extent which exceeds this measuring field, the projections are identified in which the measuring field was exceeded, and extrapolated measurement points representing the detected cut-off projections, are added to the series of &ldquo;actual&rdquo; measurement points in such a way that each series of measurement points representing a detected projection is completed in an optimally realistic manner, and begins and ends with a measurement point whose measurement value is substantially zero.

Method for image reconstruction in a computed tomography device

In a method for image reconstruction in imaging technology for the implementation of a fast convolution with the transformation length M while allowing slight over-convolution errors, each of p or 2p out of n measured projections of the length N are convolved with a modified filter kernel h (k) using Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) simultaneously in one step.

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Roth, Germany

Karl Schwarz