Abstract: A short scan uses only data from about 180° gantry rotation instead of a full 360° turn. In the provided short scan cardiac CT, a periodical axial focal spot movement is performed during gantry rotation, wherein the acquired data used for image reconstruction results from a 180° rotation of the gantry. After the data acquisition, an approximate reconstruction is performed. In a preferred embodiment the focal spot moves on a short scan saddle trajectory.

Abstract: Computed tomography (CT) systems are provided that utilize x-ray tube spectra in connection with the generation and/or interpretation of CT data. The disclosed systems and methods use x-ray tube spectra associated with CT systems to enhance contrast and/or image quality, e.g., by making use of energy selective detection techniques. The x-ray spectra may be determined in a variety of ways, e.g., incorporation of a spectral x-ray tube model into the CT system, using the output of Monte-Carlo simulations, and/or processing measured experimental spectral tube data for the CT system. The x-ray tube spectra is generally generated by and/or stored in a computer system associated with the CT system and may be used in support of an energy selective detective method and/or generation of spectral CT images.

Abstract: The invention relates to an imaging method, especially a computerized tomography method, with which an object is penetrated by rays from different directions and measured values, which depend upon the intensity of the rays after penetrating the object, are acquired by a detector unit. From these measured values, an object image is reconstructed by means of back projection of measured-value-dependent back projection values. Therein, the object image is divided into overlapping, quasi-spherically symmetric image segments, each being defined by an image value and a quasi-spherically symmetric base function.

Abstract: The present invention relates to a CT imaging system for imaging a substance, such as a contrast agent, present an object of interest, such as a patient.

Abstract: The present invention relates to a CT system for determining the quantitative material concentrations of the components, such as bone, blood, contrast agent, in a region of interest of an object, such as a patient.

Abstract: Cone-beam CT scanners with large detector arrays suffer from increased scatter radiation. This radiation may cause severe image artefacts. An examination apparatus is provided which directly measures the scatter radiation and uses this measurement for a correction of the contaminated image data. The measurement is performed by utilizing a 1-dimensional anti-scatter-grid and an X-ray tube with an electronic focal spot movement. Image data is detected at a first position of a focal spot and scatter data is detected at a second position of the focal spot. The image data is corrected on the basis of the scatter data.

Abstract: The invention relates to a computer tomography method in which a periodically moving object, in particular an organ of the body, is irradiated by a cone-shaped beam cluster (4) along a trajectory which runs on a cylindrical surface. The radiation transmitted through the object is measured by means of a detector unit (16), and at the same time the periodic movement of the object is recorded. In order to reconstruct the absorption distribution of the object, the measured values or the corresponding beams are rebinned to form a number of parallel projections, where for each of these projections a measured value is determined whose beam irradiates the object. The point in time at which this measured value was acquired is allocated to the respective projection. For the reconstruction, which may for example be carried out using a filtered back-projection, only projections whose allocated points in time lie within a predefined, specific time range (H1) within a period of the object movement are used.

Abstract: The invention relates to a device and a method for the iterative reconstruction of the attenuation coefficients ?j in a tomographic image of an object (1) from projection measurements mi. In the update equation for ?jn during the n-th iteration the backprojected error (mi?mi?(?jn)) is weighted by a voxel dependent factor Formula (I). Such a voxel dependent update may particularly be included in the algorithms of ART or ML.

Abstract: Spectral CT systems require cheap detectors with high energy resolution. According to an aspect of the present invention, a computer tomography apparatus comprises a detector element which is segmented into a plurality of sub-pixels. Each sub-pixel has at least two thresholds and counting channels, wherein the second threshold for each sub-pixel varies over the nominal detector element. This may provide for an improved energy-resolved photon counting.

Abstract: The invention relates to an examination apparatus with an X-ray device (10) for circular or helical cone-beam CT acquisition of projections images (Pi(E1), Pi(E2)) of a patient (1) with different energy spectra (E1, E2) and/or with an energy-resolved detection. By a combination of the projections, images (Ibone,i, Itissue,i) can be calculated that show predominantly the bone structure and the soft tissue, respectively. Therefore, a 3D model (Mbone) of the bone structure and a 3D model (Mtissue) of the tissue can be reconstructed separately. After removal of artifacts from the bone-structure model (Mbone), both separate 3D models can be integrated to a combined model (M) of the body volume with a high image quality.

Abstract: An iterative method determines a spatial distribution of values of a property of an object, and particularly values of its absorption, in an examination region, on the basis of measured values that values are acquired with a measuring device, and particularly with a computer tomograph. The reliability of each measured value is taken into account when this is done. The measured values can each be represented as a sum of values of the property that have each been multiplied by a proportional factor, the proportional factor being a measure of the proportion that a value of the property forms of the measured value.

Abstract: The invention relates to an imaging method, in which a projection data record of an examination area to be reconstructed is generated by acquiring projections from different projection directions, in particular with the aid of a computer tomograph. For each projection direction, a filter operator is determined that is optimally adapted to a projection geometry allocated to the respective projection direction. An image of the examination area is reconstructed from the projection data record by filtering the projections with the filter operators determined and by back projection of these filtered projections.

Abstract: The invention relates to a computer tomography method in which a radiation source moves relative to an examination region along, in particular, a helical or circular trajectory. Measured values are acquired by a detector unit and a CT image of the examination region is reconstructed from these measured values. In the reconstruction, a complementary measured value, whose ray is oriented parallel to the ray of the respective measured value that has been acquired but in the opposite direction thereto, is determined for each of at least some measured values that lie within a reconstruction window. Redundant measured values are used to calculate the complementary measured values, with the help in particular of John's equation.

Abstract: Motion is one of the most critical sources of artifacts in helical conebeam CT. By comparing opposite rays corresponding to projection data, the amount of motion may be estimated and, in the following suppression of corresponding motion artifacts may be performed according to an exemplary embodiment of the present invention. The method of motion artifact compensation may be implemented in both approximate reconstruction algorithms and exact reconstruction algorithms. Advantageously, motion during the data acquisition is detected automatically and related motion artifacts may be suppressed adaptively.

Abstract: The invention relates to a computed tomography method for forming images of an object to be examined which is arranged in an examination zone. The examination zone is scanned by means of a conical X-ray beam. In order to enable images having a high image quality to be formed from a selected imaging zone while making an as small as possible computational effort, the invention proposes the following steps: a) selecting an imaging zone of the object to be examined, b) determining the sub-regions of the X-ray detector on which the imaging zone of the object to be examined is projected during the acquisition of the projection data, c) forming sub-projection data by selecting the projection data associated with the sub-regions from the acquired projection data, and d) reconstructing the desired image from the sub-projection data by backprojection.

Abstract: In the CT imaging of non-homogeneously moving objects such as the heart or the coronary vessel tree, there is a problem that different parts of the objects are at rest at different points in time. Thus, a gated reconstruction with a globally selected time point does not yield a sharp image of such objects. According to the present invention, a motion of the objects is estimated, describing the motion of selected regions of these objects. Then, on the basis of the estimated motion, time points are determined, where these areas have minimal motion. Then, an image is reconstructed, wherein the data from which the respective regions are reconstructed, correspond to the respective time points, where the regions have minimal motion. Due to this, an improved image qualify maybe provided.

Abstract: The invention relates to an iterative method of determining a spatial distribution of values of a property of an object, and particularly values of its absorption, in an examination region, on the basis of measured values that values are acquired with a measuring device, and particularly with a computer tomograph. The reliability of each measured value is taken into account when this is done. The measured values can each be represented as a sum of values of the property that have each been multiplied by a proportional factor, the proportional factor being a measure of the proportion that a value of the property forms of the measured value.

Abstract: The invention relates to a computed tomography method in which a rebinning operation is carried out so as to form parallel fan beams whose rays traverse a plane, containing the axis of rotation, in equidistant puncture points. Reconstruction is performed for rays which extend perpendicularly to said planes. Such a transition from a cone beam geometry to a parallel beam geometry enables very fast reconstruction which can be carried out notably for CT fluoroscopy.

Abstract: The invention relates to a computer tomography method in which a periodically moving object, in particular an organ of the body, is irradiated by a cone-shaped beam cluster (4) along a trajectory which runs on a cylindrical surface. The radiation transmitted through the object is measured by means of a detector unit (16), and at the same time the periodic movement of the object is recorded. In order to reconstruct the absorption distribution of the object, the measured values or the corresponding beams are rebinned to form a number of parallel projections, where for each of these projections a measured value is determined whose beam irradiates the object. The point in time at which this measured value was acquired is allocated to the respective projection. For the reconstruction, which may for example be carried out using a filtered back-projection, only projections whose allocated points in time lie within a predefined, specific time range (H1) within a period of the object movement are used.

Abstract: The invention relates to a computer tomography method in which a radiation source moves relative to an examination region along, in particular, a helical or circular trajectory. Measured values are acquired by a detector unit and a CT image of the examination region is reconstructed from these measured values. In the reconstruction, a complementary measured value, whose ray is oriented parallel to the ray of the respective measured value that has been acquired but in the opposite direction thereto, is determined for each of at least some measured values that lie within a reconstruction window. Redundant measured values are used to calculate the complementary measured values, with the help in particular of John's equation.