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US6173032B1
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Methods and apparatus for image reconstruction
Assignee: General Electric Co
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Filing: 1998-09-29
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Granted: 2001-01-09
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Expires: 2018-09-29
Abstract
Abstract The present invention, in one form, is a method for improving image reconstruction in computed tomography systems by using a reconstruction algorithm and a detector cell algorithm. In accordance with one embodiment of the present invention, the reconstruction algorithm generates fan-parallel data directly from projection data which is processed to generate image data. In particular and in one embodiment, after view to view rebinning of the projection data, the data is pre- and post-convolution weighted, filtered and backprojected to generate image data. In another embodiment, the detector cell algorithm is utilized to determine the shape of the detector to include an arc sin dependency to eliminate axial interpolation of the projection data.
Inventors
- 👤 Guy M. Besson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:19
CPC Classifications
G; G06; G06T; G06T12/00; G06T12/10; Y; Y10; Y10S; Y10S378/00; Y10S378/901
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
51 words
A detector for use in a computed tomography system, said detector comprising a plurality of detector cells and a housing, each of said detector cells comprising a cell length and secured to said housing to form a gap therebetween, said detector configured to be positioned to directly generate fan parallel data.
Claim 2
Dependent Claim
51 words
A detector for use in a computed tomography system, said detector comprising a plurality of detector cells and a housing, each of said detector cells comprising a cell length and secured to said housing to form a gap therebetween, said detector configured to be positioned to directly generate fan parallel data.
Claim 3
Dependent Claim
19 words
A detector in accordance with claim 1 wherein said each of said detector cells comprise a variable cell length.
Claim 4
Dependent Claim
49 words
A detector in accordance with claim 2 wherein said cells are located at locus points x(v), y(v) in accordance with: ( x (ν), y (ν))=(S+D)([1 −a 2 ×ν 2 ] ½ ,a ×ν), where S=a detector vertex to a detector isocenter distance D=detector isocenter to a detector cell distance.
Claim 5
Dependent Claim
33 words
A detector in accordance with claim 3 wherein said detector cells each comprise a fixed length, and wherein said detector cell gaps are adjusted to position said detector cells at said locus points.
Claim 6
Dependent Claim
31 words
A detector in accordance with claim 3 wherein said detector cells each comprise an adjustable length, and wherein detector is configured so that each detector cell is adjacent another detector cell.
Claim 7
Independent Claim
48 words
A method for producing a tomographic image of an object from projection data acquired in a tomographic scan, said method comprising the steps of: utilizing view-to-view rebinning of the projection data to generate fan parallel data from the projection data; and generating image data from fan parallel data.
Claim 8
Independent Claim
48 words
A method for producing a tomographic image of an object from projection data acquired in a tomographic scan, said method comprising the steps of: utilizing view-to-view rebinning of the projection data to generate fan parallel data from the projection data; and generating image data from fan parallel data.
Claim 9
Independent Claim
46 words
A system for producing a tomographic image of an object from projection data acquired in a tomographic scan, said system configured to: utilize view-to-view rebinning of the projection data to generate fan parallel data from the projection data; and generate image data from fan parallel data.
Claim 10
Independent Claim
46 words
A system for producing a tomographic image of an object from projection data acquired in a tomographic scan, said system configured to: utilize view-to-view rebinning of the projection data to generate fan parallel data from the projection data; and generate image data from fan parallel data.
Claim 11
Independent Claim
71 words
A method of generating parallel data directly from a detector in a computed tomography system, the detector including a plurality of detector cells and a housing, each of said detector cells including a cell length therebetween, said method comprising the steps of: determining the position of each detector cell so that fan parallel data is directly generated; and securing each of the detector cells to the housing at the determined positions.
Claim 12
Independent Claim
71 words
A method of generating parallel data directly from a detector in a computed tomography system, the detector including a plurality of detector cells and a housing, each of said detector cells including a cell length therebetween, said method comprising the steps of: determining the position of each detector cell so that fan parallel data is directly generated; and securing each of the detector cells to the housing at the determined positions.
Claim 13
Dependent Claim
61 words
A method in accordance with claim 8 wherein determining the position of each detector cell comprises the step of determining a center point x(v), y(v) of each detector cell in accordance with: ( x (ν), y (ν))=(S+D)([1 −a 2 ×ν 2 ] ½ ,a ×ν), where S=a detector vertex to a detector isocenter distance D=detector isocenter to a detector cell distance.
Claim 14
Dependent Claim
50 words
A method in accordance with claim 9 wherein each detector cell has a fixed length, and wherein securing each of the detector cells to the housing at the determined positions comprises the step of altering the distance between the detector cells to position the detector cells at the locus points.
Claim 15
Dependent Claim
16 words
A method in accordance with claim 9 wherein each detector cell has a variable cell length.
Claim 16
Dependent Claim
41 words
A method in accordance with claim 11 wherein securing each of the detector cells to the housing at the determined positions comprises the step of altering the length of each detector cell to position each detector cell adjacent another detector cell.
Claim 17
Dependent Claim
28 words
A method in accordance with claim 8 wherein each detector cell includes an output signal and wherein said method further comprises the step of generating parallel projection rays.
Claim 18
Dependent Claim
23 words
A method in accordance with claim 8 wherein generating parallel projection rays comprises the step of view-to-view interpolation of the detector output signals.
Claim 19
Dependent Claim
48 words
A method in accordance with claim 13 wherein the computed tomography system further includes a multiple channel data acquisition system coupled to the detector and wherein generating parallel rays comprises the step delaying the output signals of each detector cell utilizing a data acquisition system channel dependent delay.
Claim 20
Independent Claim
66 words
A method for producing a tomographic image of an object from projection data acquired in a tomographic scan, said method comprising the steps of: generating fan parallel data from the projection data; applying pre-convolution weights to the projection data; filtering the weighted projection data to generate filtered data; applying post convolution weights to the filtered data; and backprojecting the weighted filtered data to generate image data.
Claim 21
Independent Claim
66 words
A method for producing a tomographic image of an object from projection data acquired in a tomographic scan, said method comprising the steps of: generating fan parallel data from the projection data; applying pre-convolution weights to the projection data; filtering the weighted projection data to generate filtered data; applying post convolution weights to the filtered data; and backprojecting the weighted filtered data to generate image data.
Claim 22
Dependent Claim
22 words
A method in accordance with claim 16 wherein applying the pre-convolution weights comprises the step of multiplying the projection data by one.
Claim 23
Dependent Claim
76 words
A system in accordance with claim 16 wherein filtering the weighted projection data comprises the step of applying a filter in accordance with: F ɛ ( v - v _ ) × { v - v _ 2 sin [ a × ( v - v _ ) 2 ] } 2 × { 1 - tan 2 [ a × ( v - v _ 2 ) ] } .
Claim 24
Dependent Claim
26 words
A method in accordance with claim 16 wherein the post convolution weights are in accordance with: 1 cos ( a × v _ ) .
Claim 25
Independent Claim
64 words
A system for producing a tomographic image of an object from projection data acquired in a tomographic scan, said system configured to: generate fan parallel data from the projection data; apply pre-convolution weights to the projection data; filter the weighted projection data to generate filtered data; apply post convolution weights to the filtered data; and backprojecting the weighted filtered data to generate image data.
Claim 26
Independent Claim
64 words
A system for producing a tomographic image of an object from projection data acquired in a tomographic scan, said system configured to: generate fan parallel data from the projection data; apply pre-convolution weights to the projection data; filter the weighted projection data to generate filtered data; apply post convolution weights to the filtered data; and backprojecting the weighted filtered data to generate image data.
Claim 27
Dependent Claim
68 words
A system in accordance with claim 20 wherein said reconstructor filter is in accordance with: F ɛ ( v - v _ ) × { v - v _ 2 sin [ a × ( v - v _ ) 2 ] } 2 × { 1 - tan 2 [ a × ( v - v _ 2 ) ] } .
Claim 28
Dependent Claim
26 words
A system in accordance with claim 20 wherein said post convolution weights are in accordance with: 1 cos ( a × v _ ) .
Claim 29
Dependent Claim
13 words
A system in accordance with claim 19 wherein said pre-convolution weights equal one.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-01-09 | 2004-07-10 | 2005-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-01-09 | 2008-07-10 | 2009-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-01-09 | 2012-07-10 | 2013-01-09 | $7700.00 | Window Closed / Lapsed |