Patents by Inventor Koichi Hirokawa

Koichi Hirokawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 10410343
    Abstract: A reconstruction image is generated with a small number of updates, with the use of an iterative approximation method. A specified tomographic image of a subject is received, and a process is performed two or more times, where an update process is performed according to the iterative approximation method, using the tomographic image as an initial image and an update image is obtained. Then, an update vector corresponding to a difference between thus generated update images of the update process performed twice is multiplied by predetermined coefficients, so as to generate an estimated update vector. Using this vector, an update image is generated. Then, this update image is used as a new initial image, and a process is repeated where the update process is performed according to the iterative approximation method and an update image is obtained, thereby generating a tomographic image of the subject.
    Type: Grant
    Filed: June 22, 2016
    Date of Patent: September 10, 2019
    Assignee: HITACHI, LTD.
    Inventors: Hisashi Takahashi, Taiga Goto, Koichi Hirokawa
  • Patent number: 10398404
    Abstract: In order to provide a data processing device and the like, capable of performing highly accurate reference correction even in a case where an object protrudes in reference channels in most of the measurement views, an image processing device (data processing device) of an X-ray CT apparatus calculates a unit air calibration reference value which is a value per unit tube current of an air calibration reference value which is reference data measured during air calibration, calculates a reference value (estimated reference value) corresponding to an X-ray condition in the main scanning on the basis of an output tube current value in the main scanning and a unit air calibration reference value, and corrects normalized reference data obtained by normalizing a measured reference value in the main scanning with the estimated reference value, to be included in an allowable error range, so as to remove the influence of protrusion.
    Type: Grant
    Filed: October 7, 2015
    Date of Patent: September 3, 2019
    Assignee: HITACHI, LTD.
    Inventors: Taiga Goto, Hisashi Takahashi, Koichi Hirokawa
  • Publication number: 20190180482
    Abstract: In order to determine noise intensity more accurately by a projection data division method using data after fan-parallel conversion, a plurality of projection data obtained by irradiating a scan object with radiations are received and subjected to prescribed data conversion; data after the conversion is divided into two or more sets; a reconstructed image is generated for each set of data; and the generated reconstructed image for each of the sets is subtracted to generate a difference image. An index indicating pixel value variation for at least one prescribed region on the difference image is calculated, the value of the index is corrected by a previously calculated correction value, and the corrected index value is regarded as noise intensity of the region.
    Type: Application
    Filed: June 16, 2017
    Publication date: June 13, 2019
    Applicant: Hitachi, Ltd.
    Inventors: Hisashi TAKAHASHI, Taiga GOTO, Koichi HIROKAWA
  • Patent number: 10238357
    Abstract: In order to provide an X-ray CT apparatus and the like capable of obtaining an optimal X-ray dose for a dynamically changing X-ray irradiation region and reliably irradiating the X-ray irradiation region in a case where X-rays are applied with a spreading angle in a body axis direction, an X-ray CT apparatus 1 dynamically changes an X-ray irradiation region 201 for each view angle during scanning, and a system control device 124 changes a position of an analysis line 300 used to calculate an optimal tube current during scanning according to a position of the X-ray irradiation region 201 at each view angle, so as to obtain an optimal irradiation X-ray dose.
    Type: Grant
    Filed: March 25, 2015
    Date of Patent: March 26, 2019
    Assignee: Hitachi, Ltd.
    Inventors: Kana Tanaka, Koichi Hirokawa, Yukio Kumagai
  • Patent number: 10213177
    Abstract: An X-ray CT apparatus includes an extraction unit that acquires air data measured using the X-ray CT apparatus and the measurement data obtained by scanning the object, that extracts sensitivity variation data which is a sensitivity variation component of a detection element from the air data, and that extracts blank data from which the sensitivity variation component is removed, and a projection data generation unit that removes the sensitivity variation component and noise which are included in the measurement data, based on the sensitivity variation data, and that uses the blank data so as to perform a correction process of the measurement data from which the sensitivity variation component and the noise are removed.
    Type: Grant
    Filed: July 23, 2015
    Date of Patent: February 26, 2019
    Assignee: HITACHI, LTD.
    Inventors: Hisashi Takahashi, Taiga Goto, Koichi Hirokawa
  • Publication number: 20180165807
    Abstract: A reconstruction image is generated with a small number of updates, with the use of an iterative approximation method. A specified tomographic image of a subject is received, and a process is performed two or more times, where an update process is performed according to the iterative approximation method, using the tomographic image as an initial image and an update image is obtained. Then, an update vector corresponding to a difference between thus generated update images of the update process performed twice is multiplied by predetermined coefficients, so as to generate an estimated update vector. Using this vector, an update image is generated. Then, this update image is used as a new initial image, and a process is repeated where the update process is performed according to the iterative approximation method and an update image is obtained, thereby generating a tomographic image of the subject.
    Type: Application
    Filed: June 22, 2016
    Publication date: June 14, 2018
    Applicant: HITACHI, LTD.
    Inventors: Hisashi TAKAHASHI, Taiga GOTO, Koichi HIROKAWA
  • Patent number: 9980694
    Abstract: In order to provide a technique capable of restoring measured data from projection data with high accuracy and removing system noise included in the measured data, a signal processing device obtains measured data x including signal values of 0 or less by processing an output signal from a data acquisition system, and performs a conversion process on the measured data x by using a predefined function including a logarithmic function so as to generate projection data (logarithmically converted data z), in which the predefined function is a function of which an inverse function is present for values of a predetermined negative number s or more, and the measured data x including signal values of 0 or less within a predetermined range is restored from the projection data by applying the inverse function to the projection data.
    Type: Grant
    Filed: January 23, 2015
    Date of Patent: May 29, 2018
    Assignee: HITACHI, LTD.
    Inventors: Hisashi Takahashi, Taiga Goto, Koichi Hirokawa
  • Patent number: 9895128
    Abstract: In order to provide a technique for reducing system noise from an output signal value (measurement data), an X-ray CT apparatus includes an X-ray generation unit that irradiates X-rays to an object, an X-ray detector that detects the X-rays transmitted through the object, a correction processing unit that corrects an output signal from the X-ray detector, and a reconstruction calculating unit that reconstructs an image on the basis of an output from the correction processing unit, in which the X-ray detector includes arranged detection elements, and in which the correction processing unit maintains an average value of output signal values of a plurality of predetermined detection elements centering on a focused detection element among the detection elements, and also reduces a variance of the output signal values of the plurality of predetermined detection elements centering on the focused detection element.
    Type: Grant
    Filed: August 6, 2014
    Date of Patent: February 20, 2018
    Assignee: HITACHI, LTD.
    Inventors: Hisashi Takahashi, Taiga Goto, Koichi Hirokawa
  • Publication number: 20170273657
    Abstract: In order to provide a data processing device and the like, capable of performing highly accurate reference correction even in a case where an object protrudes in reference channels in most of the measurement views, an image processing device (data processing device) of an X-ray CT apparatus calculates a unit air calibration reference value which is a value per unit tube current of an air calibration reference value which is reference data measured during air calibration, calculates a reference value (estimated reference value) corresponding to an X-ray condition in the main scanning on the basis of an output tube current value in the main scanning and a unit air calibration reference value, and corrects normalized reference data obtained by normalizing a measured reference value in the main scanning with the estimated reference value, to be included in an allowable error range, so as to remove the influence of protrusion.
    Type: Application
    Filed: October 7, 2015
    Publication date: September 28, 2017
    Inventors: Taiga GOTO, Hisashi TAKAHASHI, Koichi HIROKAWA
  • Publication number: 20170202532
    Abstract: In order to provide a data processing method and the like capable of suppressing high-frequency errors such as moiré using data uniformly by presuming that adjacent pixels and beams overlap and performing calculation in a back projection process or a forward projection process for reconstructing images, the image processing device 122 sets a pixel size wider than a pixel interval, performs the back projection process or the forward projection process for calculating an interpolation value to be assigned to the pixels or the beams using a size-dependent weight (pixel window) according to an overlap amount of the adjacent pixels, sets a beam size wider than a beam interval, and then performs the back projection process or the forward projection process for calculating an interpolation value to be assigned to the pixels or the beams using a size-dependent weight (beam window) according to an overlap amount of the adjacent beams.
    Type: Application
    Filed: July 10, 2015
    Publication date: July 20, 2017
    Applicant: HITACHI, LTD.
    Inventors: Taiga GOTO, Hisashi TAKAHASHI, Koichi HIROKAWA
  • Publication number: 20170135664
    Abstract: An X-ray CT apparatus includes an extraction unit that acquires air data measured using the X-ray CT apparatus and the measurement data obtained by scanning the object, that extracts sensitivity variation data which is a sensitivity variation component of a detection element from the air data, and that extracts blank data from which the sensitivity variation component is removed, and a projection data generation unit that removes the sensitivity variation component and noise which are included in the measurement data, based on the sensitivity variation data, and that uses the blank data so as to perform a correction process of the measurement data from which the sensitivity variation component and the noise are removed.
    Type: Application
    Filed: July 23, 2015
    Publication date: May 18, 2017
    Applicant: HITACHI, LTD.
    Inventors: Hisashi TAKAHASHI, Taiga GOTO, Koichi HIROKAWA
  • Patent number: 9592023
    Abstract: In an X-ray CT apparatus, a tube current value calculation unit calculates a tube current value of an X-ray tube based on a successive approximation process condition and based on an input scanning condition and/or a reconstruction condition. A scanning control unit performs scanning based on the calculated tube current value of the X-ray tub, and an image reconstruction unit reconstructs a tomographic image of an object, in accordance with the selected successive approximation process condition and the reconstruction condition. The tomographic image is reconstructed from an amount of transmitted X-rays detected by an X-ray detector after being emitted from an X-ray source to the object, in accordance with the calculated tube current value of the X-ray tube, and being transmitted through the object.
    Type: Grant
    Filed: November 28, 2013
    Date of Patent: March 14, 2017
    Assignee: HITACHI, LTD
    Inventors: Kana Tanaka, Koichi Hirokawa, Yukio Kumagai, Ryo Yoshida
  • Publication number: 20170020478
    Abstract: In order to provide an X-ray CT apparatus and the like capable of obtaining an optimal X-ray dose for a dynamically changing X-ray irradiation region and reliably irradiating the X-ray irradiation region in a case where X-rays are applied with a spreading angle in a body axis direction, an X-ray CT apparatus 1 dynamically changes an X-ray irradiation region 201 for each view angle during scanning, and a system control device 124 changes a position of an analysis line 300 used to calculate an optimal tube current during scanning according to a position of the X-ray irradiation region 201 at each view angle, so as to obtain an optimal irradiation X-ray dose.
    Type: Application
    Filed: March 25, 2015
    Publication date: January 26, 2017
    Applicant: Hitachi, Ltd.
    Inventors: Kana TANAKA, Koichi HIROKAWA, Yukio KUMAGAI
  • Publication number: 20170000442
    Abstract: In order to provide a technique capable of restoring measured data from projection data with high accuracy and removing system noise included in the measured data, a signal processing device obtains measured data x including signal values of 0 or less by processing an output signal from a data acquisition system, and performs a conversion process on the measured data x by using a predefined function including a logarithmic function so as to generate projection data (logarithmically converted data z), in which the predefined function is a function of which an inverse function is present for values of a predetermined negative number s or more, and the measured data x including signal values of 0 or less within a predetermined range is restored from the projection data by applying the inverse function to the projection data.
    Type: Application
    Filed: January 23, 2015
    Publication date: January 5, 2017
    Inventors: Hisashi TAKAHASHI, Taiga GOTO, Koichi HIROKAWA
  • Patent number: 9454804
    Abstract: In order to provide an image processing device and the like making it possible to generate a target image in which edges of a structure are upheld and from which streaking artifacts are removed, a computation device determines a shape of a non-linear function on the basis of feature amounts of an original image and a smoothed image (S101). Next, the computation device calculates a condition coefficient of the original image and the smoothed image by using the non-linear function for which the shape was determined in S101 (S102). Next, the computation device uses the condition coefficients calculated in S102 to calculate a weighting coefficient for each of the pixels of the original image and the smoothed image (S103). Next, the computation device adds weighting to the original image and the smoothed image to generate the target image (S104).
    Type: Grant
    Filed: March 14, 2013
    Date of Patent: September 27, 2016
    Assignee: HITACHI MEDICAL CORPORATION
    Inventors: Hisashi Takahashi, Koichi Hirokawa, Taiga Goto
  • Patent number: 9406121
    Abstract: To generate a reconstructed image suitable to characteristics of a bilaterally symmetric site and possible to an appropriate image diagnosis, a computation device: computes a back projection phase width at a rotational center and distance between the rotational center location which is a reference location and a pixel to be reconstructed; according to the distance between the rotational center location and the pixel to be reconstructed, sets a function (f1) changing the back projection phase width; computes a back projection phase width in the pixel to be reconstructed, substituting a value of the distance between the rotational center location and a pixel to be reconstructed in the function (f1); computes a view weighting, on the basis of the back projection phase width in the post-correction pixel to be reconstructed and a slope width of a view weighting function; and reconstructs a CT image, using the view weighting.
    Type: Grant
    Filed: March 18, 2013
    Date of Patent: August 2, 2016
    Assignee: HITACHI MEDICAL CORPORATION
    Inventors: Taiga Goto, Hisashi Takahashi, Koichi Hirokawa
  • Publication number: 20160157809
    Abstract: In order to provide a technique for reducing system noise from an output signal value (measurement data), an X-ray CT apparatus includes an X-ray generation unit that irradiates X-rays to an object, an X-ray detector that detects the X-rays transmitted through the object, a correction processing unit that corrects an output signal from the X-ray detector, and a reconstruction calculating unit that reconstructs an image on the basis of an output from the correction processing unit, in which the X-ray detector includes arranged detection elements, and in which the correction processing unit maintains an average value of output signal values of a plurality of predetermined detection elements centering on a focused detection element among the detection elements, and also reduces a variance of the output signal values of the plurality of predetermined detection elements centering on the focused detection element.
    Type: Application
    Filed: August 6, 2014
    Publication date: June 9, 2016
    Applicant: HITACHI MEDICAL CORPORATION
    Inventors: Hisashi TAKAHASHI, Taiga GOTO, Koichi HIROKAWA
  • Patent number: 9254107
    Abstract: In order to provide a technique of obtaining an image having high diagnosability without degrading the operability in an X-ray CT apparatus that suppresses the amount of exposure of an object by controlling the amount of radiation by setting a target image SD and determining the imaging conditions (tube current) satisfying the target image SD, there is provided an X-ray CT apparatus that controls the amount of radiation according to the size of an object in consideration of the contrast by simply inputting one image quality level as a reference of the image quality level that the operator desires. The input image quality level is set as a target image SD when scanning an object having a standard size with a standard tube voltage.
    Type: Grant
    Filed: September 4, 2011
    Date of Patent: February 9, 2016
    Assignee: HITACHI MEDICAL CORPORATION
    Inventors: Yoshiaki Sugaya, Taiga Goto, Koichi Hirokawa
  • Publication number: 20150297165
    Abstract: In order to provide an X-ray CT apparatus with little image quality degradation even though a tube current value of the X-ray tube is suppressed, an X-ray CT apparatus of the present invention includes: a system controller that calculates a tube current value of an X-ray tube based on a successive approximation process condition selected from a plurality of successive approximation process conditions and input a scanning condition and/or a reconstruction condition and that performs scanning based on the calculated tube current value of the X-ray tube; and an image reconstruction device that reconstructs a tomographic image of an object, based on the selected successive approximation process condition and the reconstruction condition, from an amount of transmitted X-rays detected by an X-ray detector after being emitted from an X-ray source to the object based on the calculated tube current value of the X-ray tube and being transmitted through the object.
    Type: Application
    Filed: November 28, 2013
    Publication date: October 22, 2015
    Inventors: Kana Tanaka, Koichi Hirokawa, Yukio Kumagai, Ryo Yoshida
  • Patent number: 9159146
    Abstract: To provide an image reconstruction device capable of creating an image with image quality matching the operator's request when a cross-sectional image is reconstructed through a repeated calculation, the image reconstruction device which performs a repeated calculation on the basis of a difference between calculated projection data and measured projection data, the calculated projection data being obtained by performing a forward projection calculation on a reconstructed image which is reconstructed based on the measured projection data, includes an input section to which an image quality parameter which is considered to be important by an operator is input, a weight calculation section that calculates a weighting coefficient on the basis of the image quality parameter, and a repeated calculation section that performs a repeated calculation on the basis of a value obtained by weighting and adding a pixel value obtained in the previous iteration to a pixel value obtained from now using the weighting coefficien
    Type: Grant
    Filed: July 5, 2012
    Date of Patent: October 13, 2015
    Assignee: HITACHI MEDICAL CORPORATION
    Inventors: Hisashi Takahashi, Taiga Goto, Koichi Hirokawa