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US 6,445,761 B1Granted
X-ray computerized tomograph including collimator that restricts irradiation range of X-ray fan beam
AssigneeHitachi Medical Corporation
InventorsOsamu Miyazaki, Tetsuo Nakazawa, Yoshihiro Goto
Life of this patent
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Abstract
An X-ray CT apparatus including a collimator that restricts an irradiation range of an X-ray fan beam, in which first projection data is obtained with no restriction placed onto the X-ray irradiation range through the collimator, then, second projection data is obtained with the X-ray irradiation range restricted in accordance with a concerned region set on a tomographic image, and when reconstructing an image with the use of the second projection data, the image is reconstructed using, as data outside of the concerned region, data of a corresponding portion of the first projection data.
Claims27
An X-ray CT apparatus, comprising:
- a display apparatus displaying a tomographic image;
- means for setting a concerned region on the tomographic image displayed by said display apparatus;
- X-ray shielding means for restricting an irradiation range of an X-ray fan beam in relation to said concerned region;
- means for controlling said X-ray shielding means so that said irradiation range of said X-ray fan beam through said X-ray shielding means and restriction positions of said X-ray shielding means are controlled in response to a rotation angle of an X-ray irradiator;
- means for, through said X-ray shielding means, irradiating with X-rays from said X-ray irradiator a range including said concerned region in a subject to be inspected and executing an X-ray CT measurement;
- and
- means for obtaining outside of concerned region data by means of calculation and reconstructing an image with the use of said outside of concerned region data and data of the irradiation range restricted by said X-ray shielding means, said outside of concerned region data being data of a range that is not restricted by said X-ray shielding means.
4 more elements
An X-ray CT apparatus, comprising:
- a display apparatus displaying a tomographic image;
- means for setting a concerned region on the tomographic image displayed by said display apparatus;
- X-ray shielding means for restricting an irradiation range of an X-ray fan beam in relation to said concerned region;
- means for controlling said X-ray shielding means;
- means for, through said X-ray shielding means, irradiating with X-rays a range including said concerned region in a subject to be inspected and executing an X-ray CT measurement;
- and
- means for obtaining outside of concerned region data by means of calculation and reconstructing an image with the use of said outside of concerned region data and data of the irradiation range restricted by said X-ray shielding means, said outside of concerned region data being data of a range that is not restricted by said X-ray shielding means;
- wherein said means for controlling a position of said X-ray shielding means comprises means for controlling the position of said X-ray shielding means so that, when a plurality of continuous measurements are executed, a region outside of said concerned region is also irradiated with X-rays at least one time;
- and
- wherein said means for controlling a position of said X-ray shielding means comprises means for setting the position of said X-ray shielding means so that, for each scanning, the X-ray irradiation range is gradually reduced or expanded between said concerned region and a global measurement scanning range.
7 more elements
An X-ray CT apparatus, comprising:
- an X-ray tube;
- a high voltage generator for supplying a high voltage to said X-ray tube;
- an X-ray detector opposed to and at a predetermined distance from said X-ray tube;
- a scanner mechanism unit for rotating said X-ray tube and said X-ray detector around a subject to be inspected;
- an image processor for processing measurement data and reconstructing an image;
- a display apparatus for displaying an image reconstructed;
- a slice collimator provided in an X-ray irradiation portion of said X-ray tube for restricting an X-ray irradiation range to a slice width;
- X-ray shielding means provided in said X-ray irradiation portion of said X-ray tube for restricting an X-ray irradiation range in an X-ray fan beam direction;
- a computer for controlling operations of an entire apparatus, wherein said image processor obtains outside of concerned region data by means of calculation and reconstructs said image with the use of said outside of concerned region data and data of the irradiation range restricted by said X-ray shielding means, said outside of concerned region data being data of a range that is not restricted by said X-ray shielding means;
- and
- means for controlling said X-ray shielding means so that said irradiation range of said X-ray fan beam through said X-ray shielding means and restriction positions of said X-ray shielding means are controlled in response to a rotation angle of an X-ray irradiation means.
8 more elements
A method of reconstructing an image in an X-ray CT apparatus, comprising the steps of:
- obtaining projection data by executing X-ray irradiation with an X-ray fan beam converged onto a predetermined range by moving X-ray shielding means to predetermined positions in response to a rotation angle of an X-ray irradiation means;
- and
- reconstructing an image by using said projection data and correction data corresponding to a region outside of said predetermined range.
An X-ray CT apparatus, comprising:
- a display apparatus for displaying a tomographic image,
- means for setting a concerned region on the tomographic image displayed by said display apparatus;
- X-ray shielding means for restricting an irradiation range of an X-ray fan beam in relation to said concerned region;
- means for controlling said X-ray shielding means so that said irradiation range of said X-ray fan beam through said X-ray shielding means is controlled in response to a rotation angle of an X-ray irradiator;
- means for, through said X-ray shielding means, irradiating with X-rays from said X-ray irradiator a range including said concerned region in a subject to be inspected and executing an X-ray CT measurement;
- and
- means for reconstructing an image from data obtained by said measurement,
- wherein said means for reconstructing an image comprises means for reconstructing said image with the use of data obtained by calculation from data obtained by said measurement in the X-ray irradiation range in addition to said data obtained by said measurement.
5 more elements
An X-ray CT apparatus, comprising:
- a display apparatus for displaying a tomographic image;
- means for setting a concerned region on the tomographic image displayed by said display apparatus;
- X-ray shielding means for restricting an irradiation range of an X-ray fan beam in relation to said concerned region;
- means for controlling a position of said X-ray shielding means;
- means for, through said X-ray shielding means, irradiating with X-rays a range including said concerned region in a subject to be inspected and executing an X-ray CT measurement;
- and
- means for reconstructing an image from data obtained by said measurement,
- wherein said means for controlling the position of said X-ray shielding means comprises means for controlling the position of said X-ray shielding means so that, when a plurality of continuous measurements are executed, a region outside said concerned region is also irradiated with X-rays at least one time, and further means for setting the position of said X-ray shielding means so that, for each scanning, the X-ray irradiation range is gradually reduced or expanded between said concerned region and a global measurement scanning range.
5 more elements
An X-ray CT apparatus, comprising:
- a display apparatus for displaying a tomographic image;
- means for setting a concerned region on the tomographic image displayed by said display apparatus;
- X-ray shielding means for restricting an irradiation range of an X-ray fan beam in relation to said concerned region;
- means for controlling said X-ray shielding means;
- means for, through said X-ray shielding means, irradiating with X-rays a range including said concerned region in a subject to be inspected and executing an X-ray CT measurement;
- and
- means for reconstructing an image from data obtained by said measurement,
- wherein said means for reconstructing an image comprises filtering means for executing a filtering processing to data in proximity to a boundary of said concerned region among said data obtained by said measurement.
5 more elements
An X-ray CT apparatus, comprising:
- a display apparatus for displaying a tomographic image;
- means for setting a concerned region on the tomographic image displayed by said display apparatus;
- X-ray shielding means for restricting an irradiation range of an X-ray fan beam in relation to said concerned region;
- means for controlling a position of said X-ray shielding means;
- means for, through said X-ray shielding means, irradiating with X-rays a range including said concerned region in a subject to be inspected and executing an X-ray CT measurement;
- and
- means for reconstructing an image from data obtained by said measurement,
- wherein said means for reconstructing an image comprises threshold value processing means for obtaining, by means of a threshold value processing, a boundary of said concerned region of said data obtained by said measurement.
5 more elements
An X-ray CT apparatus, comprising:
- a display apparatus displaying a tomographic image;
- means for setting a concerned region on the tomographic image displayed by said display apparatus;
- X-ray shielding means for restricting an irradiation range of an X-ray fan beam in relation to said concerned region;
- means for controlling said X-ray shielding means;
- means for, through said X-ray shielding means, irradiating with X-rays a range including said concerned region in a subject to be inspected and executing an X-ray CT measurement;
- and
- means for obtaining outside of concerned region data by means of calculation and reconstructing an image with the use of said outside of concerned region data and data of the irradiation range restricted by said X-ray shielding means, said outside of concerned region data being data of a range that is not restricted by said X-ray shielding means;
- wherein said means for reconstructing an image obtains said outside of concerned region data from data outside the irradiation range restricted by said X-ray shielding means and data of a region determined in view of an error of said X-ray shielding means.
5 more elements
An X-ray CT apparatus, comprising:
- an X-ray tube;
- a high voltage generator for supplying a high voltage to said X-ray tube;
- an X-ray detector opposed to and at a predetermined distance from said X-ray tube;
- a scanner mechanism unit for rotating said X-ray tube and said X-ray detector around a subject to be inspected;
- an image processor for processing measurement data and reconstructing an image;
- a display apparatus for displaying an image reconstructed;
- a slice collimator provided in an X-ray irradiation portion of said X-ray tube for restricting an X-ray irradiation range to a slice width;
- X-ray shielding means provided in said X-ray irradiation portion of said X-ray tube for restricting an X-ray irradiation range in an X-ray fan beam direction;
- and
- a computer for controlling operations of an entire apparatus, wherein said image processor obtains outside of concerned region data by means of calculation and reconstructs said image with the use of said outside of concerned region data and data of the irradiation range restricted by said X-ray shielding means, said outside of concerned region data being data of a range that is not restricted by said X-ray shielding means;
- wherein said means for reconstructing an image obtains said outside of concerned region data from data outside the irradiation range restricted by said X-ray shielding means and data of a region determined in view of an error of said X-ray shielding means.
8 more elements
Dependencies are inferred from the claim text.