Abstract: The invention relates to a method for evaluating projection datasets of an object undergoing examination. Each projection dataset is assigned a swiveling angle and a recording instant. Each data element of each projection dataset defines a projection line along which an X-ray beam has traveled from an X-ray source to an X-ray detector. The projection datasets form recording groups each of which corresponds with the projection datasets that were recorded during a single swiveling action. A computer determines reconstruction datasets using the projection datasets. Each reconstruction dataset contains at least one reconstruction data value assigned to a reconstruction line. Using a temporal interpolation, the computer determines the reconstruction datasets in such a way that they refer to a uniform reconstruction time. The computer determines a reconstruction of the object undergoing examination using the reconstruction datasets.

Abstract: A computer receives a number of groups of projection images of a reference object already known to the computer. Each projection image was captured via a recording arrangement with corresponding positioning of the recording arrangement. The computer uses one projection image for the respective position of the recording arrangement to determine an interim projection matrix, which describes a mapping of the three-dimensional space to a projection image captured with the respective positioning of the recording arrangement. The interim projection matrices relate to coordinate systems that are specifically assigned to each group. The computer uses interim projection matrices of different groups determined for the same position of the recording arrangement to determine locations of the other coordinate systems related to one of the coordinate systems.

Abstract: A precise and comparatively simple method for generating a three-dimensional image data record of a moving object using X-ray tomography and a device that is particularly suitable for implementing the method with an X-ray emitter/detector unit supported such that it can be rotated and with an evaluation unit are specified.

Abstract: Automatic measurement of morphometric and motion parameters of a coronary target includes extracting reference frames from input data of a coronary target at different phases of a cardiac cycle, extracting a three-dimensional centerline model for each phase of the cardiac cycle based on the references frames and projection matrices of the coronary target, tracking a motion of the coronary target through the phases based on the three-dimensional centerline models, and determining a measurement of morphologic and motion parameters of the coronary target based on the motion.

Abstract: The invention relates to a method for determining gray-scale values for volume elements of bodies to be mapped using an x-ray image recording system. When a body to be mapped is not mapped in full on a single projection image for a rotational position, a second projection image must be made and a virtual projection image derived from the two projection images, this being back-projected onto the volume elements. For calibration the present invention proposes making the same two projection images in each case at a calibration phantom and additionally a further projection image, corresponding to the position and orientation of the virtual projection image. As a result the mathematical relationships between the projection images and the virtual projection image and for the back-projection can be derived.

Abstract: A control device pivots an X-ray arrangement repeatedly between two final angular positions about a pivot axis. Projections of an object arranged in the region of the pivot axis and moving iteratively are detected at a plurality of angular positions and supplied to the control device. The control device also receives a phase position referring to the object and assigns the phase position to each projection. A computer selects one or more projections whose phase position corresponds at least approximately to a reconstruction phase position. If the computer has selected one projection for an angular position, it determines this projection as a reconstruction projection. If the computer has selected a plurality of projections for an angular position, it detects the reconstruction projection using these projections. The computer then detects a three-dimensional reconstruction of the object based on the reconstruction projection.

Abstract: A method is disclosed for generating computer tomography images using a 3D image reconstruction method. According to the method, to scan an object to be examined using a cone-shaped bundle of rays originating from a focal point and a planar, preferably multi-line detector for detecting the bundle of rays, the focal point is displaced along a spiral trajectory around the object to be examined. The detector delivers output data corresponding to the detected radiation and image voxels from the scanned examined object are reconstructed from the optionally pre-processed output data, the image voxels reflecting the attenuation coefficients of the respective voxel. Each image voxel is reconstructed separately from projection data, which covers a projection angular range of at least 108° and an approximate weighting is carried out for each voxel considered in order to standardize the projection data using the voxel.

Abstract: In dynamic computed tomography a contrast agent is injected into a patient, and a region of interest where the contrast agent is flowing is then scanned with a computed tomography machine having a ray source and a ray detector. The ray source rotates. At a first rotational position of the ray source for a first rotation at a first time point a first image is obtained, and at the first rotational position for at least another rotation at a second time point a second image is obtained. For at least another rotational position of the ray source for the first rotation at a third time point a third image is obtained, and at the another rotational position for the another rotation at a fourth time point a fourth image is obtained. Time interpolations are performed and a reconstructed image is created.

Abstract: The invention relates to a method for recording x-ray images with a C-arm system, which comprises an image recording system rotatable about a center of rotation in a recording plane, a number of x-ray fluoroscopic images of an area of interest of an object lying on an object supporting device are recorded at a plurality of angles of rotations by the image recording system, from which one or more cross-sectional images or a three dimensional can be reconstructed. The method is characterized in that the object supporting device is guided synchronously and in a non-colliding manner with the rotation of the image recording system, such that at every angle of rotation at which the recording of an image takes place, the area of interest of the object lies within a beam cone of the x-ray radiation beam of the image recording system.

Abstract: A system and method of obtaining perfusion data for cerebral tissue is described. The system includes a C-arm X-ray device and a computing system configured to obtain sets of rotational projection X-ray data suitable for reconstructing 3D voxel data sets. A first data set is obtained of the patient, and then contrast material is injected into the vascular system to obtain a second 1 data set. A first voxel data set is subtracted from the second voxel data set, and the resultant data set is processed so as to segment the contrast-enhanced vasculature from the remaining data. The segmented voxels are subtracted from the resultant voxel data set, so as to yield a functional data set representing the difference between the attenuation of the tissues after administering contrast agent and the tissues prior to administering the contrast agent, without the contrast enhanced vasculature. The attenuation of the functional data set represents the perfusion or cerebral blood volume (CBV).

Abstract: The invention relates to a device for making visible a pathological change in a part of a patient's body labeled with a fluorescent dye, the device having: a first selectable light source (11, 17), which emits light in the excitation wavelength range of the fluorescent dye, in order to trigger the emission of light in the emission wavelength range of the fluorescent dye, a second selectable light source, which emits visible light outside the emission wavelength of the fluorescent dye, and a means for selectively switching the first and the second light source on and off.

Abstract: In a method for reconstructing a CT image from data acquired from an examination subject, a reconstruction algorithm is employed that is based on an ideal short-scan circle-and-line trajectory. To adapt the reconstruction algorithm to a “real world” scan trajectory, data are acquired with a C-arm CT apparatus wherein the focus is moved through an actual short-scan circle-and-line trajectory. For each position of the focus in the actual trajectory, a projection matrix is electronically generated and the reconstruction algorithm with the ideal trajectory is adapted to the actual trajectory using the projection matrices.

Abstract: The invention relates to a method and device for reconstructing a 3D image data set of a moving object from a set of projection images, which were recorded at least partially one after the other from different projection directions. The projection images are hereby assigned by ECG gating to a motion phase of the object in each instance and an incomplete 3D image of the object is computed in this motion phase from these few projection images using local tomography. Motion fields are determined from these 3D images and are used during the final 3D image reconstruction for motion correction.

Abstract: An imaging method is disclosed for a multi-slice spiral CT scan. A CT unit is disclosed for carrying out this method. In the method, the filtering may be formed by use of multiple applications of a ramp filter and a masking operation to a projection image in a different sequence. The CT unit may include, for filtering purposes, multiple applications of a ramp filter and a masking operation to a projection image in a different sequence.

Abstract: An imaging method is for a multi-slice spiral CT scan. An object to be examined is scanned with reference to its absorption behavior by a rotating ray bundle moving in the direction of the axis of rotation, and the measured absorption data are collected. In order to reconstruct volumetric images from the measured data, the latter are filtered and the filtered data are subsequently back-projected in three dimensions in order to generate at least one volumetric image of the object to be examined. The volumetric image represent absorption values, obtained from the data, of the voxels, belonging to the layer of the object to be examined, for the radiation of the ray bundle. A CT unit is for carrying out this method. In the method, the filtering is formed by use of multiple application of a ramp filter R{right arrow over (t)} and a masking operation M to a projection image in a different sequence.

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: In a method for reconstruction of a three-dimensional image of an object scanned in linear or circular fashion in the context of a tomosynthesis. The object is transirradiated with X-rays from various projection angles &phgr; for the recording of the projection images, and the radiation exiting from the object is recorded by a detector that supplies digital output image signals. The output image signals representing the projection image data are supplied to a computer for image reconstruction. In the context of the reconstruction a filter is first produced, on the basis of the following steps: A 3D transmission function Hproj(&ohgr;x,&ohgr;y,&ohgr;z) is calculated from the recording geometry for the individual projection image recording and the back-projection of the individual projection images into the 3D reconstruction image volume. By approximation, the 3D transmission function Hproj(&ohgr;x,&ohgr;y,&ohgr;z) is inverted for the determination of an inversion function Hinv(&ohgr;x,&ohgr;y,&ohgr;z).