Abstract: A method and system for computed tomography were weighted data is used to reconstruct an image. The apparatus includes an x-ray source producing a cone-beam of x-rays, an x-ray detector disposed to receive x-rays from the x-ray source, a data collection unit, and a processing unit for processing the data using a weighting function using contributions from fan-beam and cone-beam weighting functions. The apparatus can produce images with reduced artifacts.

Abstract: A computed tomography apparatus and method where data is upsampled with shifting to produce upsampled data. The data is shifted up and down in the same amount in the z-direction, and then upsampled through interpolation. An image is reconstructed using the upsampled data. The process is preferably performed column-by-column. An upsampling shift and interpolation kernel size can be adaptive to the data z-gradient.

Abstract: A computed tomography apparatus and method using line data estimated from circle data and scanogram data. An image of a subject is reconstructed using the circle data and the estimated line data. The circle data and scanogram data may be weighted in estimating the line data. The apparatus and method are useful in diminishing or eliminating streak artifacts in reconstructed images such as images including the spine.

Abstract: A method of computed-tomography and a computed-tomography apparatus where a flying focal spot x-ray interpolation interlacing is used. Weighted or non-weighted interlacing of zero values is performed, or interpolation interlacing is performed. The interpolation interlacing may be implemented as part of backprojection and or may be a separate process prior to backprojection. In both cases interlacing is performed on post-logged convolved data. The interpolation interlacing may also be incorporated into different parts of the processing chain, such as before convolution.

Abstract: A method of computed-tomography and a computed-tomography apparatus where a interpolation kernel width is adaptively determined as a function of the distance from the x-ray source to the reconstruction pixel. The width of the kernel is the projection of the reconstruction pixel on the detector. The method can be implemented in the channel direction. The method can also be implemented in the segment direction, or in the channel and segment directions at the same time. Backprojection is performed using the adaptive kernel width and may by used with helical and circular scanning, and with cone-beam or fan beam x-ray CT.

Abstract: A computed tomography apparatus and method using line data estimated from circle data and scanogram data. An image of a subject is reconstructed using the circle data and the estimated line data. The circle data and scanogram data may be weighted in estimating the line data. The apparatus and method are useful in diminishing or eliminating streak artifacts in reconstructed images such as images including the spine.

Abstract: Three or more materials are advantageously separated from dual energy data by using a material separation technique. To effectively separate material clusters, a density plot is introduced to automatically render cluster separations. Initially, the projection data optionally undergo data-domain dual energy decomposition. Then, the image data is plotted in a vector plot whose axes are the low HU values and the high HU values. For a given data point in the vector plot, a number of data points is counted within in a region of interest surrounding the given data point to generate a density plot where each point now represents a density level surrounding the data point. Thus, clustering of a certain material is visualized by a predetermined color assignment scheme. Furthermore, special image processing methods such as Gaussian decomposition are used to improve the accuracy of material separation.

Abstract: An X-ray computed tomography apparatus includes an X-ray tube (101) which generates X-rays, a multi-channel X-ray detector (103) which detects X-rays transmitted through an object to be examined, a rotating frame (102) which is equipped with the X-ray tube and the X-ray detector, a reconstruction unit (114) which reconstructs an image on the basis of an output from the X-ray detector, and a control unit (121) which alternately shifts the X-ray focal spot of the X-ray tube along the rotating direction on the anode by a distance +? and a distance ?? for each view. The distance ? is set to ? = S ? ? O ? ? D · tan ( ? ? ? ? 2 ) where SOD is the distance between the X-ray tube and the rotation center, and ?? is the angle difference between adjacent views, such that X-ray focal spots in the adjacent views overlap each other at almost the same position.

Abstract: A method of computed-tomography and a computed-tomography apparatus where a interpolation kernel width is adaptively determined as a function of the distance from the x-ray source to the reconstruction pixel. The width of the kernel is the projection of the reconstruction pixel on the detector. The method can be implemented in the channel direction. The method can also be implemented in the segment direction, or in the channel and segment directions at the same time. Backprojection is performed using the adaptive kernel width and may by used with helical and circular scanning, and with cone-beam or fan beam x-ray CT.

Abstract: An X-ray computed tomography apparatus includes an X-ray tube (101) which generates X-rays, a multi-channel X-ray detector (103) which detects X-rays transmitted through an object to be examined, a rotating frame (102) which is equipped with the X-ray tube and the X-ray detector, a reconstruction unit (114) which reconstructs an image on the basis of an output from the X-ray detector, and a control unit (121) which alternately shifts the X-ray focal spot of the X-ray tube along the rotating direction on the anode by a distance +? and a distance ?? for each view. The distance ? is set to ? = S ? ? O ? ? D · tan ( ? ? ? ? 2 ) where SOD is the distance between the X-ray tube and the rotation center, and ?? is the angle difference between adjacent views, such that X-ray focal spots in the adjacent views overlap each other at almost the same position.

Abstract: A computed tomography apparatus and method using line data estimated from circle data and scanogram data. An image of a subject is reconstructed using the circle data and the estimated line data. The circle data and scanogram data may be weighted in estimating the line data. The apparatus and method are useful in diminishing or eliminating streak artifacts in reconstructed images such as images including the spine.

Abstract: A method and system for computed tomography were weighted data is used to reconstruct an image. The apparatus includes an x-ray source producing a cone-beam of x-rays, an x-ray detector disposed to receive x-rays from the x-ray source, a data collection unit, and a processing unit for processing the data using a weighting function using contributions from fan-beam and cone-beam weighting functions. The apparatus can produce images with reduced artifacts.

Abstract: A computed tomography apparatus and method where data is upsampled with shifting to produce upsampled data. The data is shifted up and down in the same amount in the z-direction, and then upsampled through interpolation. An image is reconstructed using the upsampled data. The process is preferably performed column-by-column. An upsampling shift and interpolation kernel size can be adaptive to the data z-gradient.

Abstract: A method of computed-tomography and a computed-tomography apparatus where a flying focal spot x-ray interpolation interlacing is used. Weighted or non-weighted interlacing of zero values is performed, or interpolation interlacing is performed. The interpolation interlacing may be implemented as part of backprojection and or may be a separate process prior to backprojection. In both cases interlacing is performed on post-logged convolved data. The interpolation interlacing may also be incorporated into different parts of the processing chain, such as before convolution.

Abstract: A method for estimating projection data outside a field of view of a scanning device, including: obtaining measured projection data by scanning an object using the scanning device; selecting a projection angle and a fan angle outside a field of view of the scanning device; determining, based on the selected projection angle and fan angle, a plurality of sinogram curves, each sinogram curve corresponding to a different image point in the object; determining a contribution value for each of the sinogram curves based on the measured projection data; and calculating estimated expanded projection data for the selected projection angle and fan angle based on the determined contribution values.

Abstract: A method of determining an image data value at a point of reconstruction in a computed tomography (CT) image of a scanned object, including obtaining projection data of the scanned object, filtering the obtained projection data with a one-dimensional ramp filter to generate ramp-filtered data, and applying a backprojection operator with inverse distance weighting to the ramp-filtered data to generate the image data value at the point of reconstruction in the CT image.

Abstract: A method, system, and computer program product for compensating for the unavailability of projection data of a scanned object at a selected point, the selected point located outside a detection range of a detector. The method include the steps of obtaining projection data of the scanned object, and compensating for the unavailability of the projection data at the selected point based on the obtained projection data and coordinates of the selected point relative to the detector. The compensating step includes determining at least one complementary projection angle and coordinates of at least one complementary point based on a source projection angle and the coordinates of the selected point relative to the detector, and estimating the projection data value at the selected point based on the acquired projection data, the at least one complementary projection angle, and the coordinates of the at least one complementary point.

Abstract: A method for estimating projection data outside a field of view of a scanning device, including: obtaining measured projection data by scanning an object using the scanning device; selecting a projection angle and a fan angle outside a field of view of the scanning device; determining, based on the selected projection angle and fan angle, a plurality of sinogram curves, each sinogram curve corresponding to a different image point in the object; determining a contribution value for each of the sinogram curves based on the measured projection data; and calculating estimated expanded projection data for the selected projection angle and fan angle based on the determined contribution values.

Abstract: A method, system, and computer program product for compensating for the unavailability of projection data of a scanned object at a selected point, the selected point located outside a detection range of a detector. The method include the steps of obtaining projection data of the scanned object, and compensating for the unavailability of the projection data at the selected point based on the obtained projection data and coordinates of the selected point relative to the detector. The compensating step includes determining at least one complementary projection angle and coordinates of at least one complementary point based on a source projection angle and the coordinates of the selected point relative to the detector, and estimating the projection data value at the selected point based on the acquired projection data, the at least one complementary projection angle, and the coordinates of the at least one complementary point.

Abstract: A method of determining an image data value at a point of reconstruction in a computed tomography (CT) image of a scanned object, including obtaining projection data of the scanned object, filtering the obtained projection data with a one-dimensional ramp filter to generate ramp-filtered data, and applying a backprojection operator with inverse distance weighting to the ramp-filtered data to generate the image data value at the point of reconstruction in the CT image.