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US5438602A
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Correction of CT attenuation data using fan beam reprojections
Assignee: General Electric Co
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Filing: 1993-12-23
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Granted: 1995-08-01
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Expires: 2013-12-23
Abstract
Abstract In an x-ray computed tomography system which acquire x-ray attenuation data using a fan beam of radiation, corrections for beam hardening are made by reprojecting the CT image data. The reprojection computations are reduced by rotating and warping the CT image data, and then performing a parallel reprojection along columns of data.
Inventors
- 👤 Carl R. Crawford
- 👤 Cameron J. Ritchie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:19
CPC Classifications
A; A61; A61B; A61B6/00; A61B6/02; A61B6/03; A61B6/032; G; G01; G01N; G01N23/00; G01N23/02; G01N23/04; G01N23/046; G06; G06T; G06T12/00; G06T12/10; G01N2223/00; G01N2223/40; G01N2223/419; Y; Y10; Y10S; Y10S378/00; Y10S378/901
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
105 words
In an imaging system which acquires a plurality of fan beam projections during a scan and which reconstructs the fan beam projections to produce image data, a method comprising: a) reprojecting the image data to produce a fan beam reprojection at an angle β by; i) warping the image data by translating image data along a set of lines emanating from the vertex of a fan beam to a corresponding set of parallel lines; and ii) reprojecting the warped image data along said set of parallel lines; and b) repeating step (a) at different angles β to produce a corresponding set of fan beam reproductions.
Claim 2
Dependent Claim
105 words
In an imaging system which acquires a plurality of fan beam projections during a scan and which reconstructs the fan beam projections to produce image data, a method comprising: a) reprojecting the image data to produce a fan beam reprojection at an angle β by; i) warping the image data by translating image data along a set of lines emanating from the vertex of a fan beam to a corresponding set of parallel lines; and ii) reprojecting the warped image data along said set of parallel lines; and b) repeating step (a) at different angles β to produce a corresponding set of fan beam reproductions.
Claim 3
Dependent Claim
53 words
The method as recited in claim 1 in which the image data is modified before being reprojected and the method includes: c) calculating corrections using the set of fan beam reproductions; d) applying the corrections to the plurality of fan beam projections; and e) reconstructing an image using the corrected fan beam projections.
Claim 4
Dependent Claim
17 words
The method as recited in claim 1 in which the imaging system is an x-ray CT system.
Claim 5
Dependent Claim
29 words
The method as recited in claim 2 in which the image system is an x-ray CT system and an imaging is reconstructed by backprojecting the corrected fan beam projections.
Claim 6
Dependent Claim
21 words
The method as recited in claim 2 in which the image data is modified to depict an image of bone tissue.
Claim 7
Dependent Claim
21 words
The method as recited in claim 5 in which the calculated corrections offset x-ray beam hardening effects due to bone tissue.
Claim 8
Dependent Claim
22 words
The method as recited in claim 2 in which steps a) through e) are repeated to further correct the CT image data.
Claim 9
Dependent Claim
23 words
The method as recited in claim 1 in which the image data is rotated by the angle β as part of the reprojection.
Claim 10
Dependent Claim
35 words
The method as recited in claim 1 in which the image data and the set of parallel lines to which the image data is translated during the warping step are rotated by an angle β.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-07-31 | 1999-01-30 | 1999-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-31 | 2003-01-30 | 2003-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-31 | 2007-01-30 | 2007-08-01 | $7700.00 | Window Closed / Lapsed |