Abstract: Disclosed are embodiments of methods for reconstructing x-ray projection data (e.g., one or more sinograms) acquired using a multi-source, inverse-geometry computed tomography (“IGCT”) scanner. One embodiment of a first method processes an IGCT sinogram by rebinning first in “z” and then in “xy,” with feathering applied during the “xy” rebinning. This produces an equivalent of a multi-axial 3rd generation sinogram, which may be further processed using a parallel derivative and/or Hilbert transform. A TOM-window (with feathering) technique and a combines backprojection technique may also be applied to produce a reconstructed volume. An embodiment of a second method processes an IGCT sinogram using a parallel derivative and/or redundancy weighting. The second method may also use signum weighting, TOM-windowing (with feathering), backprojection, and a Hilbert Inversion to produce another reconstructed volume.

Abstract: The invention provides in one aspect methods and apparatus for use with C-arm and other CT systems, e.g., with non-rigid geometries. In such systems, by way of example, calibration can be performed to determine the exact position of the x-ray source and the exact orientation of the detector where each projection measurement is made. Next, a weighting coefficient can be determined for the voxels in each plane of a reconstruction volume at every possible projection. Finally, the order in which to process the voxels during image reconstruction can be determined. Following an actual CT scan procedure in which scans are obtained of a volume to be constructed, a system according to these and related aspects of the invention can use an optimal, pre-calculated processing method, while utilizing offsets and weighting coefficients determined during calibration, for performing backprojection image reconstruction.

Abstract: A tomosynthesis method for creating a three-dimensional reconstruction of a target element volume acquires radiation absorbance images of the target element volume through a limited plurality of positions. The target element volume is divided into a plurality of volume segments and a reconstruction algorithm is applied to each segment to generate a three-dimensional reconstruction of each volume segment. The three-dimensional reconstruction of each volume segment is then merged to create a three-dimensional reconstruction of the target volume. A tomosynthesis system and a computer program product for carrying out tomosynthesis are also provided.

Abstract: It is an object of the present invention to eliminate windmill artifacts that inevitably occurs when a helical scan is performed with an X-ray CT system. To this end, the present invention is equipped with an X-ray source, and an X-ray detector having a plurality of detector elements arranged two-dimensionally, and disposed opposite to the X-ray source with a predetermined rotation center axis therebetween. The invention further includes reconstruction means for performing an arithmetic operation, in which two-dimensional projection data obtained based on X-ray detection data detected by the detector elements while rotating the X-ray source around the rotation center axis are back projected along a path different in a Z-axis direction extending along the rotation center axis from the X-ray path of the projection data, to reconstruct an image.

Abstract: A method for generating a multi-spectral image of an object is provided. The method comprises acquiring measurement data at a plurality of X-ray energy levels and defining a plurality of image voxels in one or more regions comprising the object. The method then comprises obtaining prior information associated with a plurality of image voxels comprising the object. The prior information is defined by a joint probability density function (PDF) between a plurality of basis components. The method further comprises reconstructing the measurement data to generate a multi-spectral reconstructed image of the object based on the prior information.

Abstract: A method of and a system for variable pitch CT scanning for baggage screening and variable pitch image reconstruction are disclosed.

Abstract: 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?. Finally, a back projection to reconstruct sectional images or volume data is respectively carried out from the convoluted datasets B+? and A?. The dataset B is supplemented with data of the dataset A and supplementary data are removed from the dataset B+? after the convolution but before the back projection.

Abstract: A system for determining a position of an object includes an imaging system having a x-ray source and an imager, and a processor configured to obtain a tomosynthesis image of an object using the imaging system, and determine a position of the object using the tomosynthesis image. A method of determining a position of an object includes obtaining a tomosynthesis image of an object, and determining a coordinate of the object relative to a radiation machine using the tomosynthesis image. A device for determining a position of an object includes a processor for determining a coordinate of the object relative to a radiation machine using a tomosynthesis image. A method of determining a position of an object includes obtaining an image of an object, obtaining a reference image of the object, comparing the reference image with the image, and determining a coordinate of the object based at least in part on a result of the comparing, wherein the reference image has a plane that is parallel with a plane of the image.

Abstract: An x-ray diffraction measurement apparatus for measuring a sample, having an x-ray source and detector coupled together in a combination for coordinated rotation around the sample, such that x-ray diffraction data can be taken at multiple phi angles. The apparatus may provide a pole figure representation of crystal orientation of the sample, wherein the pole figure represents the crystal alignment, and a full width half maximum value is calculated from the pole figure for crystal alignment quantification. Data may be taken at discrete positions along a length of the sample, and the sample is in a fixed position during measuring; or data may be taken continuously along a length of the article, as the sample continuously moves along its length in a movement path between the source and detector. The sample may be in the form of a tape, linearly passing through a measurement zone.

Abstract: An X-ray generation unit and an X-ray detection unit are controlled by an imaging control unit when two-dimensional images of a sample without a contrast and two-dimensional images of a sample with a contrast are imaged, so as to set imaging angles of these two-dimensional images to be different from each other, and a three-dimensional image of the sample is acquired by an image calculation unit on the basis a plurality of two-dimensional images without a contrast and a plurality of two-dimensional images with a contrast which are acquired under the control of the X-ray generation unit and the X-ray detection unit.

Abstract: A system and method for tomographic image reconstruction using truncated limited-angle projection data that allows exact interior reconstruction (interior tomography) of a region of interest (ROI) based on the linear attenuation coefficient distribution of a subregion within the ROI, thereby improving image quality while reducing radiation dosage. In addition, the method includes parallel interior tomography using multiple sources beamed at multiple angles through an ROI and that enables higher temporal resolution.

Abstract: A tomograph which determines projection data phase range capable of back projection for each reconfigured voxel with an arbitrary value larger than ? so that the absolute values of cone angles at the ends of this phase range is minimized, calculates an approximate straight line for a curve indicating the position of a radiation source with respect to the channel direction position of parallel beam projection data obtained by a parallel beam of a parallel shape viewed from the go-around axis direction generated from the radiation source, and based on the determined projection data range capable of back projection, three-dimension back projects the parallel beam projection data subjected to filter processing created through a filter correction to the back projection region corresponding to the region in concern along the approximate irradiation trace of the radiation beam calculated using the calculated approximate straight line, thereby suppressing generation of the distortion attributed to data discontinuity,

Abstract: The present invention attempts to reduce an amount of a contrast medium or a patient dose and improve diagnostic efficiency. The conditions for a main scan are designated so that a first scan of scanning a subject with a tube current of a first tube current value fed to an X-ray tube will be performed in order to examine the blood flow in a subject's blood vessel into which a contrast medium is injected. Moreover, the conditions for a main scan are designated so that a second scan of scanning the subject with a tube current of a second tube current value fed to the X-ray tube will be performed in order to image the subject's blood vessel into which the contrast medium is injected. Images of the subject are constructed based on projection data items produced by scanning the subject under the sets of conditions for a main scan.

Abstract: A method and computed tomography unit are disclosed for producing computed tomograms of a patient's beating heart by voxelwise reconstruction of volume data records from prescribed cardiac cycle phases. Firstly, a multiplicity of voxelwise partial reconstructions are calculated from projection segments substantially smaller than 180° in accordance with small cardiac phase segments. The complete voxel data that cover overall at least 180° and originate from a preselected cardiac phase are subsequently summed up per cardiac phase to be considered from the pool of the incomplete reconstructed voxel data.

Abstract: The invention relates to a method for correcting truncation artifacts in reconstructing computer tomography recordings. The projection images of the computer tomography recordings are extended by extrapolation. An equivalent body is determined which in the peripheral region of the projection image attenuates the radiation emanating from a radiation source of the computer tomography according to the object to be examined, and the attenuation is determined outside the projection image for extrapolated image points. A smoothing of the signal of a projection data line is effected with a digital polynomial filter to reduce the noise portion of the signal. The truncated portion of the projection data line is computed from the smoothed signal of the projection data line by an extrapolation method.

Abstract: There is described a method for correction of truncation artifacts in reconstructed tomographic images in a reconstruction method for tomographic images with truncated projection image data in the reconstructed tomographic images, in which divergent radiation is emitted from a radiographic source, an object to be examined is x-rayed with the divergent radiation in different projection directions, the radiation penetrating through the object to be examined is detected by a detector as projection images, with the data of the signal being arranged in a number of projection data rows and projection images detected by the detector being expanded line-by-line through extrapolation of the projection data rows.

Abstract: A cone-beam scanning system scans along a half circle. The reconstruction uses a weighting function which decreases for rows farther from the scan plane to take the redundancy of the projection data into account. Another embodiment uses a circle plus sparse helical scan geometry. Image data can be taken in real time.

Abstract: A method is disclosed for generating cardiac CT representations of a beating heart of a patient with the aid of a multi-tube CT system with application of a contrast medium. In at least one embodiment, the method includes carrying out a first CT scan with the multi-tube CT system, wherein at least one tube generates an X-ray spectrum, and reconstructing at least one CT representation of the same cardiac phase with a first temporal resolution; subsequently carrying out a second CT scan with the multi-tube CT system, wherein at least two angularly offset tubes generate different X-ray spectra; reconstructing at least one CT representation of the same cardiac phase per X-ray spectrum with a second temporal resolution; and generating a combined CT representation from results of the first and of the second scan.

Abstract: A method is disclosed for scattered radiation detection and/or for scattered radiation correction. In at least one embodiment, each radiation produced is provided with an individual temporal marker/variation of known magnitude, the change in the measured radiation being investigated for these typical temporal variations, and the fraction of the scattered radiation is inferred from the temporal variation found and, if appropriate, a corresponding correction is carried out. Furthermore, a CT system is disclosed, including a computer program that carries out at least one embodiment of the method.

Abstract: The invention relates to a method for producing computer tomography images from limited data of a region of interest of an image object which can be subject to changes, comprising the steps of a) producing a first computer tomography image of the region of interest (source image) by acquiring a sufficient set of projection data and using a standard CT-image reconstruction technique, b) selecting at least one transformation function depending on expected changes of the image object, c) acquiring CT-data of the image object from a limited number of projections under a limited range of observation angles, d) reconstructing a new image of the region of interest (target image) by an iterative procedure starting from the source image of the region of interest, deforming the source image by using the transformation function and optimizing the target image in view of the acquired CT-data from the limited number of projections.