Abstract: Various methods and systems are provided for multi-material decomposition for computed tomography. In one embodiment, a method comprises acquiring, via an imaging system, projection data for a plurality of x-ray spectra, estimating path lengths for a plurality of materials based on the projection data and calibration data for the imaging system, iteratively refining the estimated path lengths based on a linearized model derived from the calibration data, and reconstructing material-density images for each material of the plurality of materials from the iteratively-refined estimated path lengths. By determining path-length estimates in this way without modeling the physics of the imaging system, accurate material decomposition may be performed more quickly and with less sensitivity to changes in physics of the system, and furthermore may be extended to more than two materials.

Abstract: Various methods and systems are provided for spectral computed tomography (CT) imaging. In one embodiment, a method comprises performing a scan of a subject to acquire, with a detector array comprising a plurality of detector elements, projection data of the subject, generating corrected path-length estimates based on the projection data and one or more selected correction functions, and reconstructing at least one material density image based on the corrected path-length estimates. In this way, the fidelity of spectral information is improved, thereby increasing image quality for spectral computed tomography (CT) imaging systems, especially those configured with photon-counting detectors.

Abstract: Various methods and systems are provided for multi-material decomposition for computed tomography. In one embodiment, a method comprises acquiring, via an imaging system, projection data for a plurality of x-ray spectra, estimating path lengths for a plurality of materials based on the projection data and calibration data for the imaging system, iteratively refining the estimated path lengths based on a linearized model derived from the calibration data, and reconstructing material-density images for each material of the plurality of materials from the iteratively-refined estimated path lengths. By determining path-length estimates in this way without modeling the physics of the imaging system, accurate material decomposition may be performed more quickly and with less sensitivity to changes in physics of the system, and furthermore may be extended to more than two materials.

Abstract: Various methods and systems are provided for spectral computed tomography (CT) imaging. In one embodiment, a method comprises performing a scan of a subject to acquire, with a detector array comprising a plurality of detector elements, projection data of the subject, generating corrected path-length estimates based on the projection data and one or more selected correction functions, and reconstructing at least one material density image based on the corrected path-length estimates. In this way, the fidelity of spectral information is improved, thereby increasing image quality for spectral computed tomography (CT) imaging systems, especially those configured with photon-counting detectors.

Abstract: Methods and systems are provided for coherent scattered imaging using a computed tomography system with segmented detector arrays. In one embodiment, a method includes imaging a region of interest with an x-ray source and a segmented photon-counting detector array, detecting a position of an object of interest in the region of interest, selectively scanning, via the x-ray source and the segmented photon-counting detector array, the object of interest, detecting a coherent scatter signal from the object of interest with the segmented photon-counting detector array, and determining a material of the object of interest based on the detected coherent scatter signal. In this way, the coherent scatter signal may be used to identify and investigate lesions or other objects of interest within an imaged volume.

Abstract: Methods and systems are provided for coherent scattered imaging using a computed tomography system with segmented detector arrays. In one embodiment, a method includes imaging a region of interest with an x-ray source and a segmented photon-counting detector array, detecting a position of an object of interest in the region of interest, selectively scanning, via the x-ray source and the segmented photon-counting detector array, the object of interest, detecting a coherent scatter signal from the object of interest with the segmented photon-counting detector array, and determining a material of the object of interest based on the detected coherent scatter signal. In this way, the coherent scatter signal may be used to identify and investigate lesions or other objects of interest within an imaged volume.

Abstract: A plurality of projection images are acquired over an angular range during the slow rotation of a C-arm gantry having a source and detector. Phase-specific reconstructions are generated from the plurality of projections, wherein each phase-specific reconstruction is generated generally from projections acquired at or near the respective phase. In one embodiment, a plurality of motion estimates are generated based upon the phase-specific reconstructions. One or more motion-corrected reconstructions may be generated using the respective motion estimates and projections. The motion-corrected reconstructions may be associated to form motion-corrected volume renderings.

Abstract: A CT scanner acquires CT images at different energy levels and registers those images to provide a composite image that is substantially free of beam hardening artifacts and conspicuously provides atomic information of that imaged.

Abstract: One or more techniques are provided for adapting a reconstruction process to account for the motion of an imaged object or organ, such as the heart. In particular, projection data of the moving object or organ is acquired using a slowly rotating CT gantry. Motion data may be determined from the projection data or from images reconstructed from the projection data. The motion data may be used to reconstruct motion-corrected images from the projection data. The motion-corrected images may be associated to form motion-corrected volume renderings.

Abstract: A system is presented. The system includes a plurality of energy integrating detector elements configured to acquire energy integrating data. Further, the system includes a plurality of energy discriminating detector elements configured to acquire energy discriminating data, where the plurality of energy integrating detector elements and the plurality of energy discriminating detector elements are arranged in a spatial relationship to form a hybrid detector, and where the plurality of energy integrating detector elements and the plurality of energy discriminating detector elements are configured to obtain respective sets of energy integrating data and energy discriminating data for use in generating an image.

Abstract: An X-ray imaging system is provided. The X-ray imaging system includes a distributed X-ray source and a detector. The distributed X-ray source is configured to emit X-rays from a plurality of emission points arranged as a substantially linear segment, a substantially arcuate segment, a curvilinear segment, or a substantially non-planar surface and the detector is configured to generate a plurality of signals in response to X-rays incident upon the detector.

Abstract: A method for Computed Tomography (CT) imaging is provided. The method comprises rotating a gantry at a substantially slow rotation speed about a volume of interest. The gantry comprises a combination of X-ray source points. The X-ray source points comprise one or more discrete emission points and an arc of discrete or continuous X-ray source points. The method then comprises obtaining projection data from the combination of X-ray source points and performing a suitable reconstruction based on the projection data obtained from the combination of X-ray source points, to generate one or more reconstructed images.

Abstract: A plurality of projection images are acquired over an angular range during the slow rotation of a C-arm gantry having a source and detector. Phase-specific reconstructions are generated from the plurality of projections, wherein each phase-specific reconstruction is generated generally from projections acquired at or near the respective phase. In one embodiment, a plurality of motion estimates are generated based upon the phase-specific reconstructions. One or more motion-corrected reconstructions may be generated using the respective motion estimates and projections. The motion-corrected reconstructions may be associated to form motion-corrected volume renderings.

Abstract: A method for extracting information of a cardiac cycle from projection data is presented. The method provides for acquiring one or more sets of computed tomography (CT) projection data. Further, the method includes analyzing the one or sets of CT projection data to obtain a center of cardiac mass. Also, the method provides for estimating raw motion data representative of the motion of the center of cardiac mass from the one or more sets of CT projection data. In addition, the method includes processing the center of mass through time to extract a motion signal from the raw projection data. Also, the method provides for extracting the periodicity information from the motion signal.

Abstract: Various configurations for scatter reduction and control are provided for CT imaging. These configurations include an imaging system having a stationary detector extending generally around a portion of an imaging volume and a distributed X-ray source placed proximal to the stationary detector for radiating an X-ray beam toward the stationary detector. A scatter control system is further provided that is configured to adaptively operate in cooperation with the stationary detector and the distributed X-ray source to focally align collimator septa contained therein to the X-ray beam at a given focal point and to provide X-ray beam scatter control.

Abstract: A system and method for forming x-rays. One exemplary system includes a target and electron emission subsystem with a plurality of electron sources. Each of the plurality of electron sources is configured to generate a plurality of discrete spots on the target from which x-rays are emitted. Another exemplary system includes a target, an electron emission subsystem with a plurality of electron sources, each of which generates at least one of the plurality of spots on the target, and a transient beam protection subsystem for protecting the electron emission subsystem from transient beam currents and material emissions from the target.

Abstract: A method for reconstructing image data acquired by a computed tomography system is provided. The method comprises selecting a portion of image data to be reconstructed and determining a corresponding portion of projection data. An adaptive filter is computed and applied to the portion of projection data to generate a portion of adaptively-filtered projection data. The adaptive filter is computed based upon desired quality properties of the portion of image data. Finally, the portion of image data is reconstructed based upon the portion of adaptively-filtered projection data. The step of selecting, computing and reconstructing is repeated for every pixel or group of pixels comprising the image data.

Abstract: A system and method for forming x-rays. One exemplary system includes a target and electron emission subsystem with a plurality of electron sources. Each of the plurality of electron sources is configured to generate a plurality of discrete spots on the target from which x-rays are emitted. Another exemplary system includes a target, an electron emission subsystem with a plurality of electron sources, each of which generates at least one of the plurality of spots on the target, and a transient beam protection subsystem for protecting the electron emission subsystem from transient beam currents, material emissions from the target, and electric field transients.

Abstract: Geometries and configurations are provided for CT systems in which rotational loading is reduced, permitting higher speeds and lighter structures to be implemented in the systems. In certain embodiments a distributed and addressable rotating radiation source is provided with a rotating detector. In other embodiments a distributed and addressable stationary radiation source is provided with a rotating detector. In yet other embodiments a distributed and addressable radiation source is provided that rotates with respect to a stationary detector. The sources may be ring-like, arcuate and/or lines extending at least in the Z-direction. Sources may include a large number of distributed emitters arranged in lines, arcs and one- or two-dimensional arrays.

Abstract: A technique is disclosed for generating variance data and a variance map from measured projection data acquired from a tomography system. The method comprises accessing the measured projection data from the tomography system. The method further comprises generating the variance map from the measured projection data and displaying, analyzing or processing the variance map. The variance data is determined based upon a statistical model from measured image data, and may be used for image analysis, data acquisition, in computer aided diagnosis routines, and so forth.