Patent application number | Description | Published |
20090175562 | Imaging system - 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. | 07-09-2009 |
20090213985 | SYSTEM AND METHOD FOR TOMOGRAPHIC RECONSTRUCTION UTILIZING CIRCULAR TRAJECTORY AND SCANOGRAM TO REDUCE ARTIFACTS - 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. | 08-27-2009 |
20090262997 | METHOD, APPARATUS, AND COMPUTER-READABLE MEDIUM FOR PRE-RECONSTRUCTION DECOMPOSITION AND CALIBRATION IN DUAL ENERGY COMPUTED TOMOGRAPHY - A method of obtaining a computed tomography image of an object includes determining linear terms and non-linear beam hardening terms in a pair of line integral equations for dual-energy projection data from inserting average and difference from average attenuation terms, obtaining an initial solution of the line integral equation by setting the non-linear beam hardening terms to zero, and iteratively solving the line integral equations to obtain one line integral equations for each basis material. Attenuation by the first basis material corresponds to a photoelectric attenuation process, and attenuation by the second basis material corresponds to a Compton attenuation process. The line integral equations can be inverted by an inverse Radon procedure such as filtered backprojection to give images of each basis material. The images of each basis material can then be optionally combined to give monochromatic images, density and effective atomic number images, or photoelectric and Compton processes images. | 10-22-2009 |
20100189212 | METHOD OF PRE-RECONSTRUCTION DECOMPOSITION FOR FAST kV-SWITCHING ACQUISITION IN DUAL ENERGY COMPUTED TOMOGRAPHY (CT) - Fast kV-switching is a dual energy acquisition technique in computed tomography (CT) in which alternating views correspond to the low and high tube voltages. Its high temporal resolution and its suitability to a variety of source trajectories make it an attractive option for dual energy data acquisition. Its disadvantages include a one-view misregistration between the data for high and low voltages, the potentially poor spectrum separation due to the more-like a sine wave rather than the desired square wave in fast kV-switching, and the higher noise in the low voltage data because of the technical difficulty in swinging the tube current to counter the loss of x-ray production efficiency and loss of penetration at lower tube voltages. Despite the disadvantages, symmetric view matching according to the current invention substantially improves streaks and other artifacts due to the view misregistration, sufficient spectrum separation even in a sinusoidal waveform swinging between 80 kV and 135 kV, and contrast-to-noise for the simulated imaging task maximized at monochromatic energy of 75 keV. | 07-29-2010 |
20100208870 | SCATTERED RADIATION CORRECTION METHOD AND SCATTERED RADIATION CORRECTION APPARATUS - Scattered radiation is estimated by using a reduced image generated from a projection image, and the scattered radiation image of the projection image is acquired by enlargement processing. The scattered radiation correction of the projection image is executed by subtracting the obtained scattered radiation image from the projection image. In addition, when a primary X-ray image and a scattered radiation image in each projection direction are to be obtained by sequential approximation calculation, a primary X-ray image which has already been identified in an adjacent projection direction is used as a first estimated value (initially set value) in next sequential calculation. | 08-19-2010 |
20100303196 | VOLTAGE MODULATION IN DUAL ENERGY COMPUTED TOMOGRAPHY - To prevent patients from being overexposed or underexposed, it has been attempted to modulate either voltage or current in conventional single energy CT systems. The voltage modulation causes incompatibility in projection data among the views while the current modulation reduces only noise. To solve these and other problems, dual energy CT is combined with voltage modulation techniques to improve the dosage efficiency. Furthermore, dual energy CT has been combined with both voltage modulation and current modulation to optimize the dosage efficiency in order to minimize radiation to a patient without sacrificing the reconstructed image quality. | 12-02-2010 |
20100328313 | ADVANCED CLUSTERING METHOD FOR MATERIAL SEPARATION IN DUAL ENERGY CT - 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. In addition, the HSL color model may be used for better visualization and to bring a new dimension in material separation display. | 12-30-2010 |
20110103662 | METHOD FOR CIRCULAR SCAN RECONSTRUCTION IN COMPUTED TOMOGRAPHY AND COMPUTED TOMOGRAPHIC DEVICE - A method of computed-tomography and a computed-tomography apparatus where the portion of the field of view of a subject were full scan data is available is reconstructed using a full-scan algorithm. In the areas where full scan data is not available, half-scanning is used. Data is also extrapolated from the full scan data. The extrapolated data overlaps a portion of the half-scanning data. The extrapolated data and the overlapped portion of the half-scanning data are feathered. The image is reconstructed using the full-scan, half-scan and feathered data. Corner regions in an image are exposed and reconstructed to produce more uniform z-coverage of the reconstruction field of view. | 05-05-2011 |
20110170757 | Imaging System - 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. | 07-14-2011 |
20110317805 | SYSTEM AND METHOD FOR TOMOGRAPHIC RECONSTRUCTION UTILIZING CIRCULAR TRAJECTORY AND SCANOGRAM TO REDUCE ARTIFACTS - 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. | 12-29-2011 |
20120213414 | MOTION INDEX FOR MEDICAL IMAGING DATA BASED UPON GRANGEAT'S FORMULA - Embodiments and processes of computer tomography perform tasks associated with selecting a portion of projection or emission data that contain the least amount of motion based upon a predetermined motion index, a derivative of plane integral (DPI). Other embodiments and processes of computer tomography perform tasks associated with determining an amount of direction-dependent motion in an object based upon a comparison of the DPIs in predetermined directions. | 08-23-2012 |
20120215090 | IMAGING SYSTEM - 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. | 08-23-2012 |
20120308104 | METHOD AND SYSTEM UTILIZING PARAMETER-LESS FILTER FOR SUBSTANTIALLY REDUCING STREAK AND OR NOISE IN COMPUTER TOMOGRAPHY (CT) IMAGES - Photon starvation causes streaks and noise and seriously impairs the diagnostic value of the CT imaging. To reduce streaks and noise, a new scheme of adaptive Gaussian filtering relies on the diffusion-derived scale-space concept in one embodiment of the current invention. In scale-space view, filtering by Gaussians of different sizes is similar to decompose the data into a sequence of scales. As the scale measure, the variance of the filter linearly relates to the noise standard deviation of a predetermined noise model in the new filtering method. The new filter has only one optional parameter that remains stable once tuned. Although single-pass processing using the new filter generally achieves desired results, iterations are optionally performed. | 12-06-2012 |
20130101190 | COMBINATION WEIGHT APPLIED TO ITERATIVE RECONSTRUCTION IN IMAGE RECONSTRUCTION - The image generation method and system generates an image using a predetermined iterative reconstruction technique, and an instance of the iteration process is weighted according to a predetermined combination of weights during the reconstruction. The predetermined combination of the weights includes weights based upon a predetermined noise model and a predetermined window function to improve image quality. | 04-25-2013 |
20130188847 | METHOD AND SYSTEM FOR IMAGE DENOISING USING DISCRETE TOTAL VARIATION (TV) MINIMIZATION WITH ONE-DIRECTION CONDITION - In the CT imaging system, a one-direction condition improves noise uniformity in the denoised images and avoids over smoothing in the low noise regions in an image, assuming that the image originally has an unequal noise distribution. On the other hand, the discrete gradients of total variation (DTV) minimization results in an improved edge preserving effects in comparison to the conventional total variation (TV) minimization. Using DTV, the pixel values on an edge will not be substantially affected after a certain denoising treatment. The difference between the DTV minimization and the conventional TV minimization is substantially negligible for strong edges while the DTV minimization substantially improves in preserving the weak edges. DTV keeps the original values while TV slightly smoothes the values for the pixel near the bottom and top of edges. | 07-25-2013 |
20130243349 | METHOD AND SYSTEM UTILIZING PARAMETER-LESS FILTER FOR SUBSTANTIALLY REDUCING STREAK AND OR NOISE IN COMPUTER TOMOGRAPHY (CT) IMAGES - Photon starvation causes streaks and noise and seriously impairs the diagnostic value of the CT imaging. To reduce streaks and noise, a new scheme of adaptive Gaussian filtering relies on the diffusion-derived scale-space concept in one embodiment of the current invention. In scale-space view, filtering by Gaussians of different sizes is similar to decompose the data into a sequence of scales. As the scale measure, the variance of the filter linearly relates to the noise standard deviation of a predetermined noise model in the new filtering method. The new filter has only one optional parameter that remains stable once tuned. Although single-pass processing using the new filter generally achieves desired results, iterations are optionally performed. | 09-19-2013 |
20130251097 | METHOD AND SYSTEM FOR SPECTRAL COMPUTED TOMOGRAPHY (CT) WITH SPARSE PHOTON COUNTING DETECTORS - Photon counting detectors are sparsely placed at predetermined positions in the fourth-generation geometry around an object to be scanned in spectral Computer Tomography (CT). Optionally, integrating detectors are placed between the two adjacent ones of the sparsely placed photon counting detectors in the fourth-generation geometry. Furthermore, the integrating detectors are placed in the third-generation in combination to the sparsely placed photon counting detectors at predetermined positions in the fourth-generation geometry. | 09-26-2013 |
20130251224 | METHOD AND SYSTEM FOR RECONSTRUCTION ALGORITHM IN CONE BEAM CT WITH DIFFERENTIATION IN ONE DIRECTION ON DETECTOR - The current invention is generally related to a data acquisition and or image processing method and system for acquiring and or processing sparse channel data. The sparse channel is implemented in a data acquisition system having a predetermined wider pitch between the adjacent detector cells than that in the currently available imaging systems at least in one predetermined direction. In one implementation, the sparse channel data is acquired by the sparse channel data acquisition system, and an image is reconstructed from the sparse channel data according to a predetermined chord based reconstruction method eliminating the differentiation along the channel direction and utilizing a pair of proper weights. | 09-26-2013 |
20130336443 | SPARSE AND ENERGY DISCRIMINATING COLLIMATED DETECTOR ELEMENTS TO ASSIST SCATTER EVALUATION IN CT IMAGING - A computed-tomography apparatus that includes a CT scanner including an X-ray source and a detector covering respective angle ranges in the axial and transaxial planes of the CT scanner. The CT detector includes first detector elements disposed on a first surface to capture incident X-ray photons emitted from the X-ray source, and second detector elements sparsely disposed on a second surface different from the first surface, the second surface being farther away from the scanner than the first surface, the second detector elements being smaller in number than the first detector elements. Each of the second detector elements is reachable only by X-ray photons originating in a small angle range around a line connecting the X-ray source and a center of the surface of the detector element, the small angle range being determined by the predetermined distance separating the first and second surfaces and a size of the detector element. | 12-19-2013 |
20140105354 | SPARSE AND ENERGY DISCRIMINATING COLLIMATED DETECTOR ELEMENTS TO ASSIST SCATTER EVALUATION IN CT IMAGING - A computed-tomography apparatus that includes a CT scanner including an X-ray source and a detector covering respective angle ranges in the axial and transaxial planes of the CT scanner. The CT detector includes first detector elements disposed on a first surface to capture incident X-ray photons emitted from the X-ray source, and second detector elements sparsely disposed on a second surface different from the first surface, the second surface being farther away from the scanner than the first surface, the second detector elements being smaller in number than the first detector elements. Each of the second detector elements is reachable only by X-ray photons originating in a small angle range around a line connecting the X-ray source and a center of the surface of the detector element, the small angle range being determined by the predetermined distance separating the first and second surfaces and a size of the detector element. | 04-17-2014 |
20140233693 | APPARATUS AND METHOD FOR COUNT LOSS CALIBRATION OF PHOTON-COUNTING DETECTORS IN SPECTRAL COMPUTED TOMOGRAPHY IMAGING - A method for photon count-loss calibration in a computed-tomography (CT) scanner, including capturing incident X-ray photons via a plurality of energy-discriminating detectors, determining photon counts of the captured incident X-ray photons in a plurality of energy windows at each energy-discriminating detector, and adjusting the determined photon counts in each energy window for each energy-discriminating detector based on a pre-determined photon count-loss look-up table and the determined photon counts. | 08-21-2014 |
20140233694 | APPARATUS AND METHOD FOR ANGULAR RESPONSE CALIBRATION OF PHOTON-COUNTING DETECTORS IN SPARSE SPECTRAL COMPUTED TOMOGRAPHY IMAGING - A method for detector angular response calibration in computed-tomography (CT) comprising capturing incident X-ray photons, emitted from an X-ray source, via a plurality of energy-discriminating detectors, determining photon counts of the captured incident X-ray photons in a plurality of energy windows at each energy-discriminating detector, and adjusting the photon counts based on a pre-determined detector angular response calibration look-up table for a given view for each energy-discriminating detector at each energy window. | 08-21-2014 |
20140241489 | METHOD FOR SCATTERING CORRECTION FOR SPARSELY DISTRIBUTED STATIONARY DETECTORS AND ROTATING X-RAY SOURCE - A spectral computed tomography scanner apparatus, including a rotating X-ray source, a plurality of fixed energy-discriminating detectors, a processor that generates a shadow map that indicates, for each detector/view angle, a shadow state of the detector, the shadow state indicating that one of X-rays are completely blocked by a second detector and do not reach the detector, the X-rays are partially blocked by the second detector and partially reach the detector, the X-rays are not blocked by any of the detectors and reach the detector, and the detector is not with the scan field of view at the view angle, and a controller configured to cause the scanner apparatus to perform a scan of an object over a first range of view angles to collect view data, wherein the processor is configured to perform scatter correction using the collected view data and the generated shadow map. | 08-28-2014 |
20140270056 | DYNAMIC ALIGNMENT OF SPARSE PHOTON COUNTING DETECTORS - An apparatus and method for controlling movement of a plurality of fixed detectors arranged in a computed tomography (CT) system that includes a rotating X-ray source. The method including obtaining a view angle of the X-ray source, determining a tilt angle for a detector of the plurality of detectors that is within a scan field-of-view of the X-ray source at the obtained view angle so that an outer face of the detector directly faces the X-ray source, and causing the detector to be moved to the determined tilt angle. | 09-18-2014 |
20140314196 | TILTED DETECTOR ARRAY FOR MEDICAL IMAGING SYSTEMS INCLUDING COMPUTED TOMOGRAPHY - A medical imaging system can include a frame that has a bore that has a central longitudinal axis that intersects a target area for imaging, and a radiation source to emit radiation in radial directions towards the target area to form a fan or cone of emitted radiation that irradiates a cross-section of the target area with respect to the longitudinal axis. The system can include one or more detector arrays including a plurality of detector segments that extend along a detector axis that extends in a direction that is effectively parallel to the longitudinal axis, such that radiation emitted from the radiation source passes through the target area and is incident on one or more of the detector segments. The detector segments can each include a detecting surface that is tilted such that the detecting surface has a tilt (e.g., a non-zero slope) with respect to the detector axis. | 10-23-2014 |
20140314211 | PILEUP CORRECTION METHOD FOR A PHOTON-COUNTING DETECTOR - A method and apparatus for determining a parameter vector that includes a plurality of parameters of a detector pileup model of a photon-counting detector, the detector pileup model being used for pileup correction for a spectral computed-tomography scanner. The method includes setting values of the parameters, the parameters including a dead time parameter and individual probabilities of different pileup events, the probabilities including a probability of single photon events, a probability of double quasi-coincident photon events, and a probability of at least three quasi-coincident photon events. The method include determining, using (1) a detector response model, (2) an incident spectrum, and (3) the set values of the parameter vector, a plurality of component spectra, each component spectrum corresponding to one of the individual probabilities of the different pileup events, and summing the plurality of component spectra to generate an output spectrum. | 10-23-2014 |
20140328451 | APPARATUS AND METHOD FOR DYNAMIC CALIBRATION OF SPECTRAL CT WITH ROTATING X-RAY SOURCE AND STATIONARY ENERGY DISCRIMINATING DETECTORS - An apparatus and method for dynamically calibrating a computed-tomography (CT) scanner that includes a rotating X-ray source and a plurality of stationary energy-discriminating detectors configured to capture incident X-ray photons emitted from the X-ray source. A bowtie filter with a unique geometry and material composition is used to generate reference beams of a desired intensity. The apparatus includes a processor that is configured to remove a scattering background based on data obtained from the reference beams and compute a change in a predetermined calibration function. | 11-06-2014 |
20140341333 | APPARATUS AND METHOD FOR COLLIMATING X-RAYS IN SPECTRAL COMPUTER TOMOGRAPHY IMAGING - A detector includes a photon-counting detector (PCD) layer and a cathode layer arranged adjacent to the PCD layer. The detector further includes a plurality of pixilated anodes arranged adjacent to the photon-counting detecting layer on a side opposite to the cathode layer. The detector also includes a plurality of collimator segments arranged above the cathode layer so as to block a portion of X-ray photons emitted from an X-ray source from reaching the anodes, where each collimator segment is arranged above a portion of at least one anode. | 11-20-2014 |
20140355853 | NOISE BALANCE PRE-RECONSTRUCTION DATA DECOMPOSITION IN SPECTRAL CT - More than two acquired energy or spectral M bins are used for photon counting detectors in a CT system. In the pre-reconstruction data decomposition, the measured photo counts in the M acquired spectral bines are combined into a predetermined fewer number of processed or weighted spectral bines N, which is at least two in number and represents a number of selected basic materials. Since the N basis materials are selected in the imaged subject where N12-04-2014 | |
20140376689 | APPARATUS AND METHOD FOR REDUCING X-RAY FLUX IN SPECTRAL CT - An apparatus and method for reducing the X-ray flux in a computed-tomography (CT) scanner that includes a rotating X-ray source and a plurality of stationary photon-counting detectors configured to capture incident X-ray photons emitted from the X-ray source. A bowtie filter equipped with an edge filter that can be positioned in a reconfigurable manner such that the high X-ray flux at the leading edge of an X-ray fan beam incident on the detector is reduced. The CT apparatus includes a processor that is configured to compute the displacement of the edge filter in either a static or dynamic manner such that that the intensity of X-ray flux at the detectors in within acceptable operating limits. | 12-25-2014 |