US5708690A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods and apparatus for helical image reconstruction in a computed tomography fluoro system
Assignee: General Electric Co
•
Filing: 1996-10-11
•
Granted: 1998-01-13
•
Expires: 2016-10-11
Abstract
Abstract The present invention, in one form, is a system for performing image reconstruction from projection data acquired in a helical scan. More specifically, the system implements an incremental reconstruction algorithm for helical scan projection data which does not require filtering, weighting and backprojecting such projection data for generating each image. Particularly, an overscan weighting algorithm generates weighting factors to be applied to projection data to generate base image projection data. An update weighting algorithm generates update weighting factors to be applied to the base image projection data to generate subsequent image projection data.
Inventors
- 👤 Jiang Hsieh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 23:24
CPC Classifications
A; A61; A61B; A61B6/00; A61B6/02; A61B6/03; A61B6/032; G; G06; G06T; G06T12/00; G06T12/20; A61B6/027; Y; Y10; Y10S; Y10S378/00; Y10S378/901
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
91 words
A system for producing a base tomographic image and a subsequent tomographic image of an object using projection data acquired in a scan, said system comprising an x-ray source and a detector array, said detector array comprising a plurality of detectors, said system configured to: apply an overscan weighting algorithm to the projection data to generate base image projection data; determine a subsequent image view angle; and apply an update weighting algorithm to the base image projection data, using the determined subsequent image view angle, to generate subsequent image projection data.
Claim 2
Independent Claim
91 words
A system for producing a base tomographic image and a subsequent tomographic image of an object using projection data acquired in a scan, said system comprising an x-ray source and a detector array, said detector array comprising a plurality of detectors, said system configured to: apply an overscan weighting algorithm to the projection data to generate base image projection data; determine a subsequent image view angle; and apply an update weighting algorithm to the base image projection data, using the determined subsequent image view angle, to generate subsequent image projection data.
Claim 3
Dependent Claim
56 words
A system in accordance with claim 1 wherein the overscan weighing algorithm is: w(β)=3x.sup.2 (β)-2x.sup.3 (β), where: ##EQU4## β is a view angle; β 0 is an angle of gantry rotation in excess of 360° during a helical scan; x(β) is a weighting function; and w(β) is an overscan weighting factor corresponding to view angle β.
Claim 4
Dependent Claim
73 words
A system in accordance with claim 1 wherein the update weighting algorithm F(β) is: ##EQU5## where ξ≧β 0 , and ##EQU6## where ξ<β 0 ; and where: β is a view angle; β 0 is an angle of gantry rotation in excess of 360° during a scan; k is a numbered image to be generated; f(β) indicates overscan weights for a region (0,β 0 ); and ξ is the subsequent image view angle.
Claim 5
Dependent Claim
9 words
A system in accordance with claim 3 wherein ξ=π/4.
Claim 6
Dependent Claim
11 words
A system in accordance with claim 3 wherein β 0 =π/4.
Claim 7
Dependent Claim
27 words
A system in accordance with claim 3 further comprising a computer having a memory, and wherein values for ξ and β 0 are stored in said memory.
Claim 8
Dependent Claim
19 words
A system in accordance with claim 1 further configured to combine projection data that is one gantry revolution apart.
Claim 9
Independent Claim
81 words
A method for reconstructing an image of an object in a CT system using projection data acquired in a scan, the CT system having an x-ray source for projecting x-rays and a detector array, said detector array comprising a plurality of detectors, said method comprising the steps of: applying an overscan weighting algorithm to the projection data to generate base image projection data; and applying an update weighting algorithm to the base image projection data to generate subsequent image projection data.
Claim 10
Independent Claim
81 words
A method for reconstructing an image of an object in a CT system using projection data acquired in a scan, the CT system having an x-ray source for projecting x-rays and a detector array, said detector array comprising a plurality of detectors, said method comprising the steps of: applying an overscan weighting algorithm to the projection data to generate base image projection data; and applying an update weighting algorithm to the base image projection data to generate subsequent image projection data.
Claim 11
Dependent Claim
56 words
A method in accordance with claim 8 wherein the overscan weighing algorithm is: w(β)=3x.sup.2 (β)-2x.sup.3 (β), where: ##EQU7## β is a view angle; β 0 is an angle of gantry rotation in excess of 360° during a helical scan; x(β) is a weighting function; and w(β) is an overscan weighting factor corresponding to view angle β.
Claim 12
Dependent Claim
74 words
A method in accordance with claim 8 wherein the update weighting algorithm F(β) is: ##EQU8## where ξ≧β 0 , and ##EQU9## where ξ<β 0 ; and where: β is a view angle; β 0 is an angle of gantry rotation in excess of 360° during a helical scan; k is a numbered image to be generated; f(β) indicates overscan weights for a region (0,β 0 ); and ξ is the subsequent image view angle.
Claim 13
Dependent Claim
9 words
A method in accordance with claim 10 wherein ξ=π/4.
Claim 14
Dependent Claim
11 words
A method in accordance with claim 10 wherein β 0 =π/4.
Claim 15
Dependent Claim
48 words
A method in accordance with claim 10 wherein the system further includes a computer having a memory, and wherein said method further comprises the steps of selecting values for ξ and β 0 , and storing the selected values for ξ and β 0 in the computer memory.
Claim 16
Dependent Claim
21 words
A method in accordance with claim 8 further comprising the step of combining projection data that is one gantry revolution apart.
References Cited (Backward Citations)
US4275444A
Cited
US4590582A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-01-12 | 2001-07-14 | 2002-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-01-12 | 2005-07-14 | 2006-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-01-12 | 2009-07-14 | 2010-01-13 | $7700.00 | Window Closed / Lapsed |