Abstract: A system and method for acquiring an image of a region of interest (ROI) of subject using a computed tomography (CT) system includes a) performing a scout scan of the subject using the CT system to yield scout data related to the ROI and b) determining an initial contrast volume form at least the scout data. The method also includes c) prescribing a scanning protocol to be implemented using the computed tomography system to image the ROI and d) determining a size of the subject about the ROI. The method further includes e) determining a computed tomography dose related to volume (CTDIvol) based on at least the size determined at step d) and f) adjusting the scanning protocol prescribed in step b) to match at least one of a desired radiation dose and a relative intravenous (IV) contrast dose to a reference CTDIvol. The method includes g) acquiring imaging data from the ROI using the CT system by using the adjusted scanning protocol.

Abstract: A system and method for decomposing more than two materials in an imaging object includes performing a CT imaging acquisition of a portion of an imaging object using at least two energy levels to acquire imaging data associated with each of the at least two energy levels. A total mass attenuation of the imaging data is expressed as a weighted sum of constituent element mass attenuation coefficients and an effective atomic number and density of the constituent elements in the portion of the imaging object is determined by one of a number of methods. Accordingly, concentration of the constituent elements in imaged object is determined by solve the expression using known material attenuation coefficients and the measured CT data.

Abstract: The present invention is a method for reducing artifacts caused by highly attenuating materials in x-ray computed tomography (“CT”) images. The method includes combining projection views acquired at equivalent view angles to generate a projection plane data set, from which a reformatted projection is produced. The reformatted projection is then processed to detect and segment regions corresponding to objects composed of metals, metal alloys, or other highly attenuating materials. These segmented regions are then removed from the reformatted projection and the removed portions replaced by attenuation information interpolated from portions of the reformatted projection adjacent the removed portions. The interpolated reformatted projection is then mapped back to a projection plane data set, and an image of the subject is reconstructed from the projection views contained in that data set.

Abstract: A method and apparatus for reconstruction of a region of interest for an object is provided. The reconstruction of the object may be based on chords which may fill a part, all, or more than all of the region of interest. Using chords for reconstruction may allow for reducing data acquired and/or processing for reconstructing a substantially exact image of the ROI. Moreover, various methodologies may be used in reconstructing the image, such as backprojection-filtration, and modified filtration backprojection.

Abstract: A method for CT imaging that utilizes an automatic tube potential selection for individual subjects and diagnostic tasks. The method quantifies the relative radiation dose of different tube potentials for achieving a specific image quality. This allows the selection of a tube potential that provides a reduced radiation dose while still providing CT images of a sufficient quality.

Abstract: A method and apparatus for reconstruction of a region of interest for an object is provided. The reconstruction of the object may be based on chords which may fill a part, all, or more than all of the region of interest. Using chords for reconstruction may allow for reducing data acquired and/or processing for reconstructing a substantially exact image of the ROI. Moreover, various methodologies may be used in reconstructing the image, such as backprojection-filtration, and modified filtration backprojection.

Abstract: Projection data acquired with an x-ray CT system is filtered using a bilateral filter to reduce image noise and enable the acquisition at lower x-ray dose without the loss of image diagnostic quality. The bilateral filtering is performed before image reconstruction by producing a noise equivalent data set from the acquired projection data and then converting the bilateral filtered values back to a projection data set suitable for image reconstruction.

Abstract: A system and method for the accurate quantitative evaluation of dual-energy computed tomography (CT) projection data that is acquired in a dual-source helical scan includes employing a dual-source z-axis helical interpolation method. The method includes transforming the two helical projection data sets, where corresponding projections of high- and low-energy data sets are shifted with respect to one another by 90 degrees or another angle, into corresponding non-helical projection data sets. A dual-source helical interpolation algorithm allows for projection space dual-energy processing by realigning the high- and low-energy datasets based on the z-axis interpolation. This algorithm may be implemented using a variety of interpolation schemes and can be extended from single slice to multi-slice data acquisitions.

Abstract: A method and apparatus for reconstruction of a region of interest for an object is provided. The reconstruction of the object may be based on chords which may fill a part, all, or more than all of the region of interest. Using chords for reconstruction may allow for reducing data acquired and/or processing for reconstructing a substantially exact image of the ROI. Moreover, various methodologies may be used in reconstructing the image, such as backprojection-filtration, and modified filtration backprojection.

Abstract: The present invention provides a material decomposition method capable of determining the distribution of density and constituent material concentration throughout an imaged object. The concentration, in the form of a mass fraction, mass percent, weight fraction, or weight percent, is determined from CT images acquired at different energy levels. The ratio of attenuation coefficients associated with one energy level to attenuation coefficients associated with another energy level is determined and used as an index in a lookup table to determine the concentration of a given material throughout the imaged object.

Abstract: A system and method for creating a combined or mixed-energy image using both low- and high-energy CT data sets acquired using a dual-energy CT system. The low- and high-energy datasets are mixed using desired weighting factors to mimic a “single-energy” image. The low-energy dataset provides data with improved contrast enhancement, but with increased noise level. The high-energy dataset provides data with lower contrast enhancement, but with better noise properties. By combining the low- and high-energy datasets in accordance with the present method, the resulting mixed-energy images utilize the information of full dose of radiation used in the dual-energy scan. A plurality of weighting metrics can be selected, including patient size, dose partitioning, or image quality, to determine the desired weighting factors based on the weighting metrics. By selecting the proper weight factors, image noise can be reduced and/or the contrast to noise ratio can be increased in the mixed-energy image.

Abstract: The present invention is a method for reducing artifacts caused by highly attenuating materials in x-ray computed tomography (“CT”) images. The method includes combining projection views acquired at equivalent view angles to generate a projection plane data set, from which a reformatted projection is produced. The reformatted projection is then processed to detect and segment regions corresponding to objects composed of metals, metal alloys, or other highly attenuating materials. These segmented regions are then removed from the reformatted projection and the removed portions replaced by attenuation information interpolated from portions of the reformatted projection adjacent the removed portions. The interpolated reformatted projection is then mapped back to a projection plane data set, and an image of the subject is reconstructed from the projection views contained in that data set.

Abstract: The present invention provides a material decomposition method capable of determining the distribution of density and constituent material concentration throughout an imaged object. The concentration, in the form of a mass fraction, mass percent, weight fraction, or weight percent, is determined from CT images acquired at different energy levels. The ratio of attenuation coefficients associated with one energy level to attenuation coefficients associated with another energy level is determined and used as an index in a lookup table to determine the concentration of a given material throughout the imaged object.

Abstract: A system and method for decomposing more than two materials in an imaging object includes performing a CT imaging acquisition of a portion of an imaging object using at least two energy levels to acquire imaging data associated with each of the at least two energy levels. A total mass attenuation of the imaging data is expressed as a weighted sum of constituent element mass attenuation coefficients and an effective atomic number and density of the constituent elements in the portion of the imaging object is determined by one of a number of methods. Accordingly, concentration of the constituent elements in imaged object is determined by solve the expression using known material attenuation coefficients and the measured CT data.

Abstract: A method and apparatus for reconstruction of a region of interest for an object is provided. The reconstruction of the object may be based on chords which may fill a part, all, or more than all of the region of interest. Using chords for reconstruction may allow for reducing data acquired and/or processing for reconstructing a substantially exact image of the ROI. Moreover, various methodologies may be used in reconstructing the image, such as backprojection-filtration, and modified filtration backprojection.

Abstract: A system and method for creating a combined or mixed-energy image using both low- and high-energy CT data sets acquired using a dual-energy CT system. The low- and high-energy datasets are mixed using desired weighting factors to mimic a “single-energy” image. The low-energy dataset provides data with improved contrast enhancement, but with increased noise level. The high-energy dataset provides data with lower contrast enhancement, but with better noise properties. By combining the low- and high-energy datasets in accordance with the present method, the resulting mixed-energy images utilize the information of full dose of radiation used in the dual-energy scan. A plurality of weighting metrics can be selected, including patient size, dose partitioning, or image quality, to determine the desired weighting factors based on the weighting metrics. By selecting the proper weight factors, image noise can be reduced and/or the contrast to noise ratio can be increased in the mixed-energy image.

Abstract: A method and apparatus for reconstruction of a region of interest (ROI) for an object using an imaging system is provided. The imaging system may substantially exactly reconstruct the ROI with a straight line trajectory. In the straight line trajectory, the ROI is not bounded or encircled by the actual trajectory of the source (e.g., no chords that are composed from two points on the source trajectory intersect or fill the ROI to be imaged). However, the ROI may be substantially reconstructed by using “virtual” chords to reconstruct the ROI. The virtual chords are such that no point on the trajectory is included in the virtual chord (such as one that is parallel to the straight line trajectory). These virtual chords may intersect and fill the ROI, thus enabling substantially exact reconstruction. Further, in reconstructing the image, the straight line trajectory may be assumed to be infinite in length.

Abstract: A method and apparatus are provided for reconstructing a tomographic image from fan-beam or cone-beam data. The method includes the steps of collecting fan-beam or cone-beam data over an image space, converting the fan-beam or cone-beam data to parallel-beam data with respect to a rotation angle within the image space, performing a shift variant filtration of the parallel-beam data within the image space and converting the processed data to images through backprojection or other means.

Abstract: A method and apparatus for reconstruction of a region of interest for an object is provided. The reconstruction of the object may be based on chords which may fill a part, all, or more than all of the region of interest. Using chords for reconstruction may allow for reducing data acquired and/or processing for reconstructing a substantially exact image of the ROI. Moreover, various methodologies may be used in reconstructing the image, such as backprojection-filtration, and modified filtration backprojection.