Image reconstructing method and X-ray CT apparatus
First Claim
1. An image reconstructing method comprising the steps of, upon reconstructing an image using a multi-row detector having a plurality of detector sequences and on the basis of projection data D0 collected by a helical scan with a scan surface being tilted:
- effecting, on the projection data D0, a tilt correcting process for correcting variations every views, in positions of respective channels of the detector sequences with respect to a linear travel axis due to the inclination of the scan surface;
then projecting respective pixels in an X-ray penetration direction along lines parallel to an X axis or a Y axis on a reconstruction plane (XY plane) to determine the corresponding projection data D0 and defining the same as backprojected pixel data D2 of respective pixels constituting the reconstruction plane; and
adding the backprojected pixel data D2 of all views used in image reconstruction in association with the pixels to determine backprojected data D3.
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Accused Products
Abstract
An image reconstructing method includes upon reconstructing an image using a multi-row detector having a plurality of detector sequences and on the basis of projection data D0 collected by a helical scan with a scan surface being tilted effecting, on the projection data, a tilt correcting process for correcting variations on every view, in positions of respective channels of the detector sequences with respect to a linear travel axis due to the inclination of the scan surface, projecting respective pixels in an X-ray penetration direction along lines parallel to an X axis or a Y axis on a reconstruction plane to determine the corresponding projection data and defining the same as backprojected pixel data of respective pixels constituting the reconstruction plane, and adding the backprojected pixel data of all views used in image reconstruction in association with the pixels to determine backprojected data.
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Citations
20 Claims
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1. An image reconstructing method comprising the steps of, upon reconstructing an image using a multi-row detector having a plurality of detector sequences and on the basis of projection data D0 collected by a helical scan with a scan surface being tilted:
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effecting, on the projection data D0, a tilt correcting process for correcting variations every views, in positions of respective channels of the detector sequences with respect to a linear travel axis due to the inclination of the scan surface;
then projecting respective pixels in an X-ray penetration direction along lines parallel to an X axis or a Y axis on a reconstruction plane (XY plane) to determine the corresponding projection data D0 and defining the same as backprojected pixel data D2 of respective pixels constituting the reconstruction plane; and
adding the backprojected pixel data D2 of all views used in image reconstruction in association with the pixels to determine backprojected data D3.
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2. An image reconstructing method comprising the steps of, upon reconstructing an image using a multi-row detector having a plurality of detector sequences and on the basis of projection data D0 collected by a helical scan with a scan surface being tilted:
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effecting, on the projection data D0, a tilt correcting process for correcting variations every views, in positions of respective channels of the detector sequences with respect to a linear travel axis due to the inclination of the scan surface;
determining data D1 plane-projected onto the plane of projection on the basis of the tilt-corrected projection data D0;
then projecting, in an X-ray penetration direction, the data D1 plane-projected on respective pixels constituting a plurality of lines which are parallel to an X axis or a Y axis on a reconstruction plane (XY plane) with plural pixel intervals defined thereamong and extend in the direction parallel to the projection plane to thereby determine backprojected pixel data D2 of the respective pixels constituting the lines on a reconstruction area; and
interpolating among the plurality of lines to determine backprojected pixel data D2 of respective pixels among the lines on the reconstruction area; and
adding the backprojected pixel data D2 of all views employed in image reconstruction in association with the pixels to determine backprojected data D3.
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3. An image reconstructing method comprising the steps of, upon reconstructing an image using a multi-row detector having a plurality of detector sequences and on the basis of projection data D0 collected by a helical scan with a scan surface being tilted:
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effecting, on the projection data D0, a tilt correcting process for correcting variations every views, in positions of respective channels of the detector sequences with respect to a linear travel axis due to the inclination of the scan surface;
determining data D1 plane-projected onto lines on a projection plane, corresponding to a plurality of lines which are placed on a reconstruction area with plural pixel intervals defined thereamong and extend in the direction parallel to the projection plane, on the basis of the tilt-corrected projection data D0;
determining backprojected pixel data D2 of respective pixels on the reconstruction area on the basis of the plane-projected data D1 located on the lines on the projection plane; and
adding the backprojected pixel data D2 of all views used in image reconstruction in association with the pixels to determine backprojected data D3.
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4. An X-ray CT apparatus comprising:
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an X-ray tube;
a multi-row detector opposite to the X-ray tube and having a plurality of detector sequences;
a linear movement control device for relatively moving the X-ray tube and the multi-row detector linearly with a subject along a linear travel axis;
a rotation control device for rotating at least one of the X-ray tube and the multi-row detector about a rotational axis;
a tilt control device for tilting an angle of a scan surface formed by the rotation with respect to the linear travel axis to an angular slope other than 90°
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a scan control device for collecting projection data D0, using the multi-row detector and by a helical scan with a scan surface being tilted; and
an image reconstructing device for reconstructing an image, based on the projection data D0, wherein the image reconstructing device includes, a tilt correcting device for effecting a tilt correcting process for correcting variations every views, in positions of respective channels of the detector sequences with respect to the linear travel axis due to the inclination of the scan surface, on the projection data D0, a backprojected pixel data calculating device for then projecting respective pixels in an X-ray penetration direction along lines parallel to an X axis or a Y axis on a reconstruction plane (XY plane) to determine the corresponding projection data D0 and thereby determining backprojected pixel data D2 of respective pixels constituting the reconstruction plane; and
a backprojected data calculating device for adding the backprojected pixel data D2 of all views used in image reconstruction in association with the pixels to determine backprojected data D3. - View Dependent Claims (5, 9, 12, 14, 15, 16, 17, 18, 19, 20)
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6. An X-ray CT apparatus comprising:
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an X-ray tube;
a multi-row detector opposite to the X-ray tube and having a plurality of detector sequences;
a linear movement control device for relatively moving the X-ray tube and the multi-row detector linearly with a subject along a linear travel axis;
a rotation control device for rotating at least one of the X-ray tube and the multi-row detector about a rotational axis;
a tilt control device for tilting an angle of a scan surface formed by the rotation with respect to the linear travel axis to an angular slope other than 90°
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a scan control device for collecting projection data D0, using the multi-row detector and by a helical scan with a scan surface being tilted; and
an image reconstructing device for reconstructing an image, based on the projection data D0, wherein the image reconstructing device includes, a tilt correcting device for effecting a tilt correcting process for correcting variations every views, in positions of respective channels of the detector sequences with respect to the linear travel axis due to the inclination of the scan surface, on the projection data D0, a plane-projected data calculating device for determining data D1 plane-projected onto the plane of projection on the basis of the tilt-corrected projection data D0, a backprojected pixel data calculating device for projecting, in an X-ray penetration direction, the plane-projected data D1 onto respective pixels constituting a plurality of lines which are parallel to an X axis or a Y axis on a reconstruction plane (XY plane) with plural pixel intervals defined thereamong and extend in the direction parallel to the projection plane to thereby determine backprojected pixel data D2 of the respective pixels constituting the lines on a reconstruction area, and interpolating among the plurality of lines to determine backprojected pixel data D2 of respective pixels among the lines on the reconstruction area, and a backprojected data calculating device for adding the backprojected pixel data D2 of all views employed in image reconstruction in association with the pixels to determine backprojected data D3. - View Dependent Claims (8, 10, 11, 13)
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7. An X-ray CT apparatus comprising:
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an X-ray tube;
a multi-row detector opposite to the X-ray tube and having a plurality of detector sequences;
a linear movement control device for relatively moving the X-ray tube and the multi-row detector linearly with a subject along a linear travel axis;
a rotation control device for rotating at least one of the X-ray tube and the multi-row detector about a rotational axis;
a tilt control device for tilting an angle of a scan surface formed by the rotation with respect to the linear travel axis to an angular slope other than 90°
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a scan control device for collecting projection data D0, using the multi-row detector and by a helical scan with a scan surface being tilted; and
an image reconstructing device for reconstructing an image, based on the projection data D0, wherein the image reconstructing device includes, a tilt correcting device for effecting a tilt correcting process for correcting variations every views, in positions of respective channels of the detector sequences with respect to the linear travel axis due to the inclination of the scan surface, on the projection data D0, a plane-projected data calculating device for determining data D1 plane-projected onto lines on a projection plane, corresponding to a plurality of lines which are placed on a reconstruction area with plural pixel intervals defined thereamong and extend in the direction parallel to the projection plane, on the basis of the tilt-corrected projection data D0, a backprojected pixel data calculating device for determining backprojected pixel data D2 of respective pixels on the reconstruction area on the basis of the plane-projected data D1, and a backprojected data calculating device for adding the backprojected pixel data D2 of all views used in image reconstruction in association with the pixels to determine backprojected data D3.
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Specification