Siemens Aktiengesellschaft

Ernst-Peter Rührnschopf

Bernhard Scholz

Wolfgang Härer

Philipp Bernhardt

Alois Nöttling

Michael Zellerhoff

Michael Maschke

Karl Stierstorfer

Martin Hoheisel

Klaus Klingenbeck-Regn

Frank Dennerlein

Joachim Hornegger

Benno Heigl

Martin Sedlmair

Thomas Brunner

Klaus Klingenbeck

Bernd Schreiber

Karl Wiesent

Stefan Hoppe

Holger Scherl

Norbert Karl Strobel

Dr Klaus Klingenbeck-Regn

Lothar Bätz

3D reconstructions can be calculated from grayscale X-ray images taken at different angular positions of an X-ray source and detector rotatable about a common axis. In the present case, X-ray radiation is applied to the object to be imaged such that one half of the X-ray detector receives radiation which differs in one characteristic from the radiation received by the second half of the detector via the object. A kind of dual-energy imaging can then be carried out in a single pass through the angular positions, enabling two 3D reconstructions to be generated simultaneously and then merged.

Method for obtaining a 3D reconstruction of an object, and X-ray device

A method for acquiring a 3D image dataset for an image object based on a plurality of 2D image datasets relating to the image object is proposed. A scattered radiation is taken into account in an acquisition operator used in the method for the optimum reconstruction of the 3D image dataset. The acquisition operator should be as close as possible to the real mapping operator.

Method for acquiring a 3D image dataset for an image object

In a computer tomography method an object region of the object being examined is determined in that projection beams that are linked with maximum attenuation are sought in cropped projection images. A central point of the object region is then determined and the object sections associated with the projection beams plotted on the central point. The object region can be at least approximately determined using the end points of the object sections.

Computer tomography method for determining an object region with the aid of projection images

The invention relates to a method for reducing image noise in the context of capturing at least one radiation-based image of a region of interest using two different radiation spectra, in particular two different x-ray radiation spectra, comprising the following steps: capturing raw images of the region of interest using the two different radiation spectra with in each case mutually paired measured values; and to separate different materials in the region of interest, applying to the captured raw images at least one inversion operator with integrated noise filtering, said operator describing a transition from a measured value pair to an assigned reconstruction value pair.

Method for reducing image noise in the context of capturing an image using two different radiation spectra

A method for creating material-selective volume images of various material components of an object to be examined is proposed. The method is based on multi-spectral projected images captured from various directions of projection, the images being captured using an X-ray machine, and makes it possible to quantitively exactly determine the material-selective volume images by way of iteration.

Method for creating material-selective volume images

The invention relates to a method for creating scatter-corrected mass density image in dual energy X-ray absorptiometry. The mass density image is created using additional information provided by attenuation images at different energy levels in an inhomogeneous correction image area. A multi-dimensional mass density is found that is consistent for a plurality of the attenuation images by inverting a primary radiation function. A scatter fraction is determined on the basis of the multi-dimensional mass density.

Method for creating mass density images on the basis of attenuation images captured at different energy levels

The invention relates to a computed tomography method. The airgap associated with a projection direction is determined by determining, in the projection images, edge pixels which map object edges on a detector. By back-projecting the edge pixels in an object image space it is possible to determine an envelope polygon for an outline contour of the examination object. The width of the airgap associated with a specific projection direction can then be determined on the basis of the envelope polygon. Exact knowledge of the current airgap serves to improve the scattered radiation correction.

Computed tomography method

A method for generating image data relating to a virtually prescribable X-ray tube voltage Ufrom first and second dual energy CT image data is disclosed. In at least one embodiment, the method includes providing the first and second CT image data; prescribing the virtual X-ray tube voltage Uwith U&#x2260;Uand U&#x2260;U, on the basis of the first and second CT image data for two prescribable base materials A, B; determining in each case a spatial density distribution &#x3c1;(x), &#x3c1;(x), assigned to the base materials A, B, in the reconstructed object volume, &#x3c1;(x)=&#x3c1;(x)+&#x3c1;(x) holds true for a density &#x3c1;(x) of a voxel x in the reconstructed object volume; providing an effective mass attenuation coefficient &#x3c;&#x3b1;&#x3e;for the base material A, and an effective mass attenuation coefficient &#x3c;&#x3b1;&#x3e;for the base material B, the effective mass attenuation coefficients &#x3c;&#x3b1;&#x3e;and &#x3c;&#x3b1;&#x3e;respectively being valid for an X-ray spectrum S(E, U) assigned to the virtual X-ray tube voltage U; and determining the image data as a third distribution of linear attenuation coefficients &#x3bc;(x) in the reconstructed object volume on the basis of the following relationship: &#x3bc;(x)=&#x3c;&#x3b1;&#x3e;&#xb7;&#x3c1;(x)+&#x3c;&#x3b1;&#x3e;&#xb7;&#x3c1;(x).

Method for generating image data relating to a virtually prescribable X-ray tube voltage from first and second CT image data

The invention relates to a method for beam hardening correction in medical image. Beam hardening within the context of medical imaging projection image profiles are split up into a basic profile which is assigned to a homogeneous object area and into a detailed profile which is assigned to an inhomogeneous object area. On the basis of the basic profile and of the difference profile the mass occupancy of the different components in the object to be examined can be approximately determined. On the basis of the approximately determined mass occupancy the correction of the beam hardening can then be performed directly on the projection data.

Method for hardening correction in medical imaging

The invention relates to a method for speeding up the scattered radiation correction in a computed tomography system with a radiation source and a detector constructed in large-area format with a number of rows of detectors, by which an object is scanned from numerous projection angles, uses the measured values for the attenuation of the radiation in generating projection data which is postprocessed for the purpose of reconstructing tomographic views, in doing which a beam hardening correction is applied directly to the projection data, whereby according to the invention the scattered radiation correction is also applied directly to the projection data.

Method for speeding up the scattered radiation correction in a computed tomography system

The invention relates to a method for combined bone hardening and scattered radiation correction in X-ray computed tomography of a heterogeneous object with a CT system comprising an X-ray source moved around an object, a flat detector with a large number of distributed detector elements which detect measuring beams from a focal point of the X-ray tube, and a control and arithmetic-logic unit&#x2014;by iterative reconstruction and segmented vectorial reprojection calculation, wherein a scattered radiation correction and a radiation hardening correction are carried out in each iteration cycle for at least two different material components of the object being examined. The invention also relates to an X-ray CT system for carrying out this method.

Method for combined bone hardening and scattered radiation correction in X-ray computed tomography

For scattered radiation correction in dual X-ray absorptiometry it is proposed to use the additional information supplied by the attenuation images in different energy ranges in a correction image area with homogeneous attenuation coefficients in order to determine the respective scattered radiation fraction. Toward that end, the inverse of the primary radiation function is considered and a search conducted for that scatter-to-primary ratio which leads to consistent mass per unit areas for the attenuation images recorded in different energy ranges.

Method for scattered radiation correction

The invention relates to a method for correcting x-ray scatter in projection radiography or in x-ray computer tomography, in which, for different observed objects, different scatter-correction convolution cores G are determined and in the examination of the respective objects object-specific scatter-correction convolution cores are applied to detector data which is created during the x-raying of these objects. The invention also relates to a projection radiography or x-ray computer tomography system which features programs in a processing system which executes the method described above when the system is operating.

Method for correcting x-ray scatter in projection radiography and computer tomography

The invention relates to an angiographic x-ray diagnostic device for rotation angiography with an x-ray emitter which can be moved on a circular path about a patient located on a patient support table, with an image detector unit which can moved on the circular path facing the x-ray emitter, with a digital image system for recording a plurality of projection images by means of rotation angiography, with a device for image processing, by means of which the projection images are reconstructed into a 3D volume image, and with a device for correcting physical effects and/or inadequacies in the recording system such as truncation correction, scatter correction, ring artifact correction, correction of the beam hardening and/or of the low frequency drop for the soft tissue display of projection images and the 3D volume images resulting therefrom.

Angiographic x-ray diagnostic device for rotation angiography

To enable an artifact free reconstruction even in the case of large regions of interest and with scanning paths of below 360&#xb0;, 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.

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Erlangen, Germany

Ernst-Peter Rührnschopf