Patents Examined by David Vernon Bruce
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Patent number: 6014419Abstract: A method is provided for reconstructing an image of an object, for use in an imaging system wherein a detector is mounted for measuring radiation emanating in a cone beam of rays which converge at a focal point. The method includes the step of establishing relative movement between the cone beam focal point and the object along a composite scan path, comprising primary and supplementary scan path components, the supplementary path usefully comprising a linear or helical path. The method further includes acquiring a set of cone beam data of the object with the detector during movement along the supplementary scan path component, computing a set of values of an intermediate function from the cone beam data, each of said computed values having an associated location defined by a prespecified point grid lying on the detector plane, and employing each of the computed values in a back-projection operation to determine the value of a reconstruction function, for use in forming an image of the object.Type: GrantFiled: November 7, 1997Date of Patent: January 11, 2000Inventor: Hui Hu
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Patent number: 6014420Abstract: An X-ray CT apparatus is disclosed which has a simple construction and yet is capable of correcting the sensitivity of each X-ray detecting element in response to a focal shift of an X-ray tube. A monitoring detector is formed of eight channels at an end of an X-ray detector for receiving X-rays not penetrating a patient. The eight channels are divided into two regions F and R each having four channels. Each of the regions F and R is divided into two parts along the direction of a body axis. Shielding plates such as of lead (Pb) not penetrable by X rays are applied to the detecting elements in one of the two parts of region F and to those in the other of the two parts of region R. When no focal shift occurs with the X-ray tube, an output difference S0 is zero between a total output F0 of the X-ray detecting elements in the region F and a total output R0 of the X-ray detecting elements in the region R.Type: GrantFiled: February 6, 1998Date of Patent: January 11, 2000Assignee: Shimadzu CorporationInventor: Junichi Ooi
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Patent number: 6009142Abstract: A method and apparatus of operating a CT imaging apparatus having a cone beam radiation source and a 2D detector arrangement, for exactly reconstructing an image of a 3D region of interest (ROI) in an object. Measurement data acquired by the 2D detector is processed to develop sub-sets of Radon data. Each of the sub-sets of Radon data is targeted for reconstructing a corresponding local 2D ROI in a 2D parallel projection of the object. Accordingly, after a sub-set of Radon data is completely developed, it is subjected to a first inversion processing step for developing the corresponding local 2D ROI. Multiple ones of the local ROIs are then grouped together and subjected to a second inversion processing step to develop an image reconstruction of a part of the 3D ROI in the object.Type: GrantFiled: March 31, 1998Date of Patent: December 28, 1999Assignee: Siemens Corporate Research, Inc.Inventors: Frank Sauer, Supun Samarasekera, Kwok Tam
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Patent number: 6009140Abstract: A correction algorithm for substantially eliminating "stair case" type artifacts in dental scans is described. In one specific embodiment, all high density object boundaries in the reformatted images are identified. To identify high density object boundaries, structures in the reformatted image are separated into two classes, namely, structure containing teeth and structure not containing teeth. Then, within each class, fuzzy logic is used to define the membership grade of each pixel. Particularly, linear interpolation is utilized to determine the boundary, and to reduce the probability that spike noise will be erroneously considered as high density objects, the N by N neighbors of the boundary candidate are searched to ensure that the number of pixels that belong to the high density object exceeds a certain predefined threshold. Such searching can be performed by summing the N by N neighbors of the membership function, .xi., and comparing the summation against a pre-defined threshold.Type: GrantFiled: November 7, 1997Date of Patent: December 28, 1999Assignee: General Electric CompanyInventor: Jiang Hsieh
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Patent number: 6005917Abstract: A method of imaging a blood vessel in a body using X-rays and an injectable contrast medium is described. The contrast medium is injected into the body, and signals constituted by an X-ray image sequence depicting X-ray attenuation values is recorded. The X-ray attenuated values in each spaced-time neighborhood are combined in a way that is dependent on the processed image sequence and separately established for each neighborhood, and separating, from background and vessel signals, flow signals having energy contributions mainly in an area of frequency domain bounded by surfaces corresponding to threshold velocities separately established for each neighborhood, which surfaces are shifted a specified amount along a temporal frequency axis.Type: GrantFiled: October 6, 1997Date of Patent: December 21, 1999Inventors: Mats Andersson, Hans Knutsson, Torbjorn Kronander
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Patent number: 6005916Abstract: An apparatus and method for rapid real time imaging with wavefield energy using a C.P.U. programmed to process data derived from wavefield energy that has been transmitted and scattered by an object so as to reconstruct a wavefield image of the object. Electronic signals are propagated and are transduced into wavefield energy waves which in turn are propagated toward the object. Detectors detect the wavefield energy waves scattered by the object. The detected wavefield energy waves are then electronically processed and input into a high-speed digital computer which may comprise a C.P.U. and/or a C.P.U. in combination with an array or parallel processor. Data is also prepared and input to the computer representing the incident field and the computer then reconstructs a high-quality image of the object having high spacial resolution and including actual properties of the object.Type: GrantFiled: November 17, 1997Date of Patent: December 21, 1999Assignee: Techniscan, Inc.Inventors: Steven A. Johnson, David T. Borup, James W. Wiskin, Frank Natterer, F. Wubeling, Yongzhi Zhang, Scott Charles Olsen
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Patent number: 6002738Abstract: Volume rendering and tomographic reconstruction center around solving two related integral equations: a volume rendering integral (a generalized Radon transform) and a filtered backprojection integral (the inverse Radon transform). Both of these equations are of the same mathematical form and can be dimensionally decomposed and approximated using Riemann sums over a series of resampled images. When viewed as a form of texture mapping and frame buffer accumulation, enormous hardware enabled performance acceleration is possible.Type: GrantFiled: July 7, 1995Date of Patent: December 14, 1999Assignee: Silicon Graphics, Inc.Inventors: Brian K. Cabral, James Foran
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Patent number: 6002739Abstract: A cone-beam tomographic system in which computation speed is improved by reducing the reconstructed images to thin planes. Reducing the images to thin planes reduces the number of picture elements to be computed, and reduces basis functions to a simple function of the angle of a ray relative to a plane. In a variation, computation speed is further improved by making pixel size inversely proportional to the distance of a plane from an emissions source. As a result of the variable pixel size, for each projection, a ray intersecting the center of a sensor element intersects the center of exactly one pixel in each object plane.Type: GrantFiled: April 28, 1998Date of Patent: December 14, 1999Assignee: Hewlett Packard CompanyInventor: John M. Heumann
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Patent number: 6000847Abstract: In a method and apparatus for scatter-glare correction in x-ray diagnostic images from a patient, a densitometric calibration phantom that reduces x-ray beam hardening effects. The calibration phantom is constructed from x-ray absorbing specks narrower than the x-ray aperture but thicker in the x-ray direction than the half-value thickness for diagnostic energy photons, the specks being aligned with the fan beams of x-rays from the x-ray source.Type: GrantFiled: April 7, 1998Date of Patent: December 14, 1999Assignee: Cedars-Sinai Medical CenterInventors: Robert Alan Close, James Stuart Whiting
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Patent number: 6002741Abstract: A method and apparatus for obtaining the planar location with sub-pixel resolution and corrected energy of a gamma or X-ray photon interacting with a room temperature solid state detector of given thickness. The detector comprises two electrodes of negative and positive polarities. One of the electrodes is common, and the other is segmented being formed with segmented readout elements. Each of the readout elements defines a pixel size. Depending on that the negative or positive electrode is segmented, respectively, negative-induces charge signals are induced on the readout elements or both a positive-induced charge signal is induced on a central readout element and negative-induced charge signals are induced on adjacent readout elements.Type: GrantFiled: December 17, 1997Date of Patent: December 14, 1999Assignee: The State of Israel, Atomic Energy Commission Soreq Nuclear Research CenterInventors: Yosef Eisen, Asher Shor
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Patent number: 5999587Abstract: A method of and system for the 3-D reconstruction of an image from 2-D cone-beam tomography projections is disclosed in which a circle-plus-arc data acquisition geometry is utilized to provide a complete set of data so that an exact 3-D reconstruction is obtained. A volume CT scanner which uses a cone-beam x-ray source and a 2-D detector is utilized in which one set of cone-beam projections is acquired while rotating the x-ray tube and detector on the CT gantry and then another set of projections is acquired while tilting the gantry by a small angle. The projection data is preweighted and the partial derivatives of the preweighted projection data are calculated. Those calculated partial derivatives are rebinned to the first derivative of the Radon transform, for both the circular orbit data and the arc orbit data. The second partial derivative of the Radon transform is then calculated and then the reconstructed 3-D images are obtained by backprojecting using the inverse Radon transform.Type: GrantFiled: July 3, 1997Date of Patent: December 7, 1999Assignee: University of RochesterInventors: Ruola Ning, Xiaohui Wang
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Patent number: 5999591Abstract: To provide a method and an instrument capable of easily and accurately measuring a size of an affected part present in a body of a patient, there is provided a measuring instrument 1 including at least four sheets of acrylic plates having indices of a substance of X-ray image forming performance of metal balls 2 and 3, metal wires and the like in which sets of two sheets of the acrylic plates are arranged in parallel to each other and a space defined by the sets of acrylic plates arranged in parallel, is provided with an interval capable of receiving a part of a patient to be measured, such as the head or the like.Type: GrantFiled: October 29, 1997Date of Patent: December 7, 1999Assignee: Terumo Kabushiki KaishaInventors: Shigeki Kobayashi, Kazuhito Ishihara
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Patent number: 5995580Abstract: An exact image reconstruction method for computed tomography allows the reconstruction of a sub-volume of interest in a long subject from cone beam or pyramid beam CT data using a spiral focus path. A two-stage reconstruction process is utilized that, by line integration over the detector, first calculates 3D radon values of a sub-volume of interest defined only for the respective .phi.-plane for each .phi.-plane of a 3D spherical coordinate system. For each .phi.-plane, the sub-volume of interest is limited toward the exterior by the radius of the measurement field and is upwardly and downwardly limited by curved surfaces that arise by the locus of a straight line perpendicular to the .phi.-plane under consideration proceeding to each focus point of a spiral segment.Type: GrantFiled: May 28, 1998Date of Patent: November 30, 1999Assignee: Siemens AktiengesellschaftInventor: Stefan Schaller
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Patent number: 5991356Abstract: In order to obtain a tomographic image close to a stationary image using opposite view data, a radiation tomography method and apparatus are provided for measuring projection data representing a subject by radiation beams in a plurality of view directions around the subject; calculating estimated projection data for each of the plurality of view directions by performing a weighting calculation on data elements of the projection data generated by radiations which transmit through the same path in opposite directions so that a desired time phase for the subject is centrally weighted; and producing a tomographic image of the subject based on the estimated projection data.Type: GrantFiled: May 26, 1998Date of Patent: November 23, 1999Assignee: GE Yokogawa Medical Systems, LimitedInventors: Tetsuya Horiuchi, Makoto Gono
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Patent number: 5991358Abstract: A data acquisition system for use in a CT scanner comprises an analog-to-digital converter for generating digital signals in response to analog signals representative of projection data taken at a relatively constant sampling rate; and an interpolation filter for generating projection data for a plurality of predetermined projection angles as a function of the digital signals irrespective of the sampling rate.Type: GrantFiled: December 31, 1997Date of Patent: November 23, 1999Assignee: Analogic CorporationInventors: Enrico Dolazza, Hans J. Weedon, Douglas Q. Abraham
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Patent number: 5987094Abstract: A computer-assisted diagnostic (CAD) method and apparatus are described for the enhancement, detection, and classification of suspicious regions in digital x-ray images, with particular emphasis on lung nodule detection using chest x-ray images. An objective is to improve the sensitivity and specificity of detection of suspicious areas such as nodules, while maintaining a low false positive detection rate. A modular CAD technique has been developed to be potentially automatic and to be used as a second-opinion method for lung nodule detection. The method consists of using a plurality of CAD modules to preprocess and enhance image features, including image preprocessing, selective enhancement, segmentation, and feature extraction using a multiresolution/multiorientation wavelet transform and a computationally efficient filter, a 1.5 D circular pattern filter.Type: GrantFiled: October 30, 1997Date of Patent: November 16, 1999Assignee: University of South FloridaInventors: Laurence P. Clarke, Wei Qian, Fei Mao
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Patent number: 5987093Abstract: X-ray detectors of an X-ray CT apparatus provides photographing image data to a medical image forming apparatus. When data for setting a region-of-interest ("ROI") image and CT values of bones are provided through an input data entry unit of the medical image forming apparatus, a system control unit controls a tomographic image reconstruction unit in such a way that the latter eliminates pixels with the CT values from the ROI image. The reconstruction unit provides the same to a monitor unit through a display control unit. The ROI tomographic image is converted into a blood-vessel emphasized tomographic image. A clear ROI image can be obtained for portions even complicatedly tangled with bones and vessels, such as a human head or the like.Type: GrantFiled: October 24, 1997Date of Patent: November 16, 1999Assignee: Kabushiki Kaisha ToshibaInventor: Masahiro Ozaki
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Patent number: 5987091Abstract: Projection data having a phase difference of 180.degree. from each other, which are obtained through a 1/4 offset detector, are arranged alternately to obtain projection data of the high resolution, and a CT image is reconstructed on the basis of the projection data of the high resolution. Opposition difference data showing the difference between the projection data having the phase difference of 180.degree. from each other and having a phase difference of 180.degree. from each other are alternately arranged to obtain the opposition difference data of the high resolution, and an opposition difference image is reconstructed on the basis of the opposition difference data of the high resolution. Then, distortion components showing the high-frequency component are extracted from the aforesaid opposition difference image, and the aforesaid reconstructed CT image is corrected by the thus extracted distortion components, so that motion artifacts contained in the original CT image can be reduced.Type: GrantFiled: July 21, 1997Date of Patent: November 16, 1999Assignee: Hitachi Medical CorporationInventors: Osamu Miyazaki, Shinichi Migita, Tetsuo Nakazawa
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Patent number: 5982846Abstract: Methods and apparatus for dose reduction in a computed tomography (CT) system are described. In one embodiment, the CT system includes a configurable multislice detector array and an adjustable source collimator. The detector array includes a photodiode cell array optically coupled to a scintillator array. The photodiode array includes a plurality of photodiodes arranged in rows and columns that may be combined to collect slice data from a number of inner and outer slices. The CT system also includes an x-ray source and a collimator. The x-ray source generates an x-ray beam that is collimated by the collimator to define the thickness of each outer slice. In operation, an operator determines the quantity and thickness of inner slices and the thickness of each outer slice. After altering the detector and collimator configuration, as defined by an operator, slice data for each inner slice and each outer slice is gathered.Type: GrantFiled: April 13, 1998Date of Patent: November 9, 1999Assignee: General Electric CompanyInventors: Thomas L. Toth, Neil B. Bromberg
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Patent number: 5982845Abstract: A forward projector/backprojector (30) for a CT scanner (10) includes a VME interface (36) which loads data onto and off of the forward projector/backprojector (30), and a CPU (42) which controls data flow. An array of ASICs (60a-x) is included. Each ASIC has two pipelines along which data is subjected to pipeline operations including one of a forward projection algorithm and a backprojection algorithm. Double-buffered memories for storing data subject to the pipeline operations are arranged on each ASIC (60a-x) such that while data is loaded into one bank of the double-buffered memories data in its opposing bank is subject to pipeline operations. A dual in-line memory module (DIMM) daughtercard (120) holds an output memory (100) with two banks employed during pipeline operations.Type: GrantFiled: April 7, 1998Date of Patent: November 9, 1999Assignee: Picker International, Inc.Inventors: John Sidoti, Holly F. Heiple, Anthony F. Krecic, Robert J. Merat