Patent US5412703A successfully refreshed from Google Patents.
US5412703A
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Reduced partial volume artifacts in image reconstruction, with application to X-ray computed tomography
Assignee: Sentinel Scanning Corp
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Filing: 1993-02-04
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Granted: 1995-05-02
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Expires: 2013-02-04
Abstract
Abstract An apparatus for correcting an X-ray tomographic image is presented, where the tomographic image is created by measuring an X-ray transmission coefficient at each of a plurality of X-ray beam paths through an object to enable reconstructing a tomographic image of the object. There is a device for selecting a plurality of volume averaged voxels along at least one of the X-ray beam ray paths, and for placing contiguous volume averaged voxels in a run length of volume averaged voxels, to make a plurality of run lengths of volume averaged voxels. There is a device for dividing the plurality of run lengths of volume averaged voxels into a plurality of subslices. There is a device, responsive to the plurality of subslices and responsive to the plurality of run lengths of volume averaged voxels, for computing a corrected value of X-ray attenuation coefficient for the X-ray beam ray path. There is a device for reconstructing a correction image using the corrected X-ray attenuation coefficient for each X-ray beam ray path. Finally, there is a device for obtaining an improved image by combining the tomographic image with the correction image.
Inventors
- 👤 Davil J. Goodenough
- 👤 Warren S. Edwards
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:58
CPC Classifications
G; G06; G06T; G06T12/00; G06T12/10; G01; G01N; G01N23/00; G01N23/02; G01N23/04; G01N23/046; G01N2223/00; G01N2223/40; G01N2223/419; G01N2223/60; G01N2223/612; Y; Y10; Y10S; Y10S378/00; Y10S378/901
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
171 words
An apparatus for correcting an X-ray tomographic image, where the tomographic image is created by measuring an X-ray transmission coefficient at each of a plurality of X-ray beam ray paths through an object to enable reconstructing a tomographic image of said object, comprising: means for selecting a plurality of volume averaged voxels along at least one said X-ray beam ray path, and for placing contiguous volume averaged voxels in a runlength of volume averaged voxels, to make a plurality of run lengths of volume averaged voxels; means for dividing said plurality of run lengths of volume averaged voxels into a plurality of subslices; means, responsive to said plurality of subslices and responsive to said plurality of run lengths of volume averaged voxels, for computing a corrected value of X-ray attenuation coefficient for said X-ray beam ray path; means for reconstructing a correction image using said corrected X-ray attenuation coefficient for each said X-ray beam ray path; means for obtaining an improved image by combining said tomographic image with said correction image.
Claim 2
Independent Claim
171 words
An apparatus for correcting an X-ray tomographic image, where the tomographic image is created by measuring an X-ray transmission coefficient at each of a plurality of X-ray beam ray paths through an object to enable reconstructing a tomographic image of said object, comprising: means for selecting a plurality of volume averaged voxels along at least one said X-ray beam ray path, and for placing contiguous volume averaged voxels in a runlength of volume averaged voxels, to make a plurality of run lengths of volume averaged voxels; means for dividing said plurality of run lengths of volume averaged voxels into a plurality of subslices; means, responsive to said plurality of subslices and responsive to said plurality of run lengths of volume averaged voxels, for computing a corrected value of X-ray attenuation coefficient for said X-ray beam ray path; means for reconstructing a correction image using said corrected X-ray attenuation coefficient for each said X-ray beam ray path; means for obtaining an improved image by combining said tomographic image with said correction image.
Claim 3
Independent Claim
177 words
An apparatus for correcting an X-ray tomographic image, comprising: means for measuring an X-ray transmission coefficient at each of a plurality of X-ray beam ray paths through an object to enable reconstructing a tomographic image of said object; means for reconstructing a tomographic image from said transmission data; means for selecting a plurality of volume averaged voxels along at least one said X-ray beam ray path, and for placing contiguous volume averaged voxels in a run length of volume averaged voxels, to make a plurality of run lengths of volume averaged voxels; means for dividing said plurality of run lengths of volume averaged voxels into a plurality of subslices; means, responsive to said plurality of subslices and responsive to said plurality of run lengths of volume averaged voxels, for computing a corrected value of X-ray attenuation coefficient for said X-ray beam ray path; means for reconstructing a correction image using said corrected X-ray attenuation coefficient for each said X-ray beam ray path; means for obtaining an improved image by combining said tomographic image with said correction image.
Claim 4
Independent Claim
177 words
An apparatus for correcting an X-ray tomographic image, comprising: means for measuring an X-ray transmission coefficient at each of a plurality of X-ray beam ray paths through an object to enable reconstructing a tomographic image of said object; means for reconstructing a tomographic image from said transmission data; means for selecting a plurality of volume averaged voxels along at least one said X-ray beam ray path, and for placing contiguous volume averaged voxels in a run length of volume averaged voxels, to make a plurality of run lengths of volume averaged voxels; means for dividing said plurality of run lengths of volume averaged voxels into a plurality of subslices; means, responsive to said plurality of subslices and responsive to said plurality of run lengths of volume averaged voxels, for computing a corrected value of X-ray attenuation coefficient for said X-ray beam ray path; means for reconstructing a correction image using said corrected X-ray attenuation coefficient for each said X-ray beam ray path; means for obtaining an improved image by combining said tomographic image with said correction image.
Claim 5
Dependent Claim
92 words
The apparatus as in claim 1 further comprising: means for determining an X-ray attenuation coefficient in a voxel in an upper slice above said slice of interest, and for determining an X-ray attenuation coefficient in a voxel in a lower slice below said slice of interest; means, responsive to said determining said X-ray attenuation coefficient in said upper slice and responsive to said determining said X-ray attenuation coefficient in said lower slice, for ordering said subslices so that an upper subslice corresponds to a material in a voxel in said upper slice.
Claim 6
Dependent Claim
15 words
The apparatus as in claim 1 further comprising: each said subslice has the same thickness.
Claim 7
Dependent Claim
42 words
The apparatus as in claim 1 further comprising: a thickness of each said subslice is determined by a value of thickness of a first material, where said value of thickness of a first material is computed for said run length of voxels.
Claim 8
Dependent Claim
26 words
The apparatus as in claim 4 wherein said thickness of a first material is computed from Z/h values computed for each said run length of voxels.
Claim 9
Dependent Claim
39 words
The apparatus as in claim 1 wherein said means for computing a corrected X-ray attenuation coefficient for at least one selected subslice, further comprises; means for choosing a material of selected X-ray attenuation coefficient to occupy a selected subvoxel.
Claim 10
Dependent Claim
26 words
The apparatus as in claim 7 further comprising: means for computing a correction X-ray attenuation coefficient for a ray path along a subslice using equation 18.
Claim 11
Dependent Claim
71 words
The apparatus as in claim 7 further comprising: means for computing a correction X-ray attenuation coefficient for a ray path along a subsclice using the following equation, ##EQU27## where, T i is the subsclice thickness I i is the intensity exiting the subsclice I 0 is the original unit intensity μ eff is the effective X-ray attenuation coefficient R is the total run length, and N is the number of subslices.
Claim 12
Dependent Claim
25 words
The apparatus as in claim 1 further comprising: means for determining a shape of said object; means, responsive to said shape, for selecting said subslices.
Claim 13
Dependent Claim
30 words
The apparatus as in claim 1 further comprising: means for determining a shape of said object; means, responsive to said shape, for selecting a material to occupy a selected subvoxel.
Claim 14
Independent Claim
176 words
An apparatus for correcting an X-ray tomographic image, comprising: a. means for measuring an X-ray transmission coefficient at each of a plurality of X-ray beam ray paths through an object to enable reconstructing a tomographic image of said object; b. means for reconstructing a tomographic image from said transmission data; c. means for selecting at least one run length of volume averaged voxels along each said ray path; d. means for dividing said at least one run length of volume averaged voxels into a plurality of subslices; e. means, responsive to said plurality of subslices, for computing a corrected X-ray attenuation coefficient for each said ray path; f. means for repeatably computing a corrected X-ray attenuation coefficient for each said ray path by repeating step e, and for ending the repeated calculations when a convergence criteria is met; g. means for reconstructing a correction image using said corrected X-ray attenuation coefficient computed at step f for each said ray path; h. means for obtaining an improved image by combining said tomographic image and said correction image.
Claim 15
Independent Claim
176 words
An apparatus for correcting an X-ray tomographic image, comprising: a. means for measuring an X-ray transmission coefficient at each of a plurality of X-ray beam ray paths through an object to enable reconstructing a tomographic image of said object; b. means for reconstructing a tomographic image from said transmission data; c. means for selecting at least one run length of volume averaged voxels along each said ray path; d. means for dividing said at least one run length of volume averaged voxels into a plurality of subslices; e. means, responsive to said plurality of subslices, for computing a corrected X-ray attenuation coefficient for each said ray path; f. means for repeatably computing a corrected X-ray attenuation coefficient for each said ray path by repeating step e, and for ending the repeated calculations when a convergence criteria is met; g. means for reconstructing a correction image using said corrected X-ray attenuation coefficient computed at step f for each said ray path; h. means for obtaining an improved image by combining said tomographic image and said correction image.
Claim 16
Dependent Claim
34 words
The apparatus as in claim 12 wherein said convergence criteria is X as computed by the following equation, ##EQU28## where, Δμ is the change in X-ray attenuation coefficient, μ is the X-ray attenuation coefficient.
Claim 17
Dependent Claim
63 words
The apparatus as in claim 12 further comprising: means for selecting a new number of subslices; means for comparing a value of said convergence criteria as computed with a first number of subslices and as computed with a second number of subslices, and for selecting as an optimum number of subslices a number of subslices yielding a smaller value of said convergence criteria.
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) | 1998-05-01 | 1998-10-31 | 1999-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-01 | 2002-10-31 | 2003-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-01 | 2006-10-31 | 2007-05-02 | $7700.00 | Window Closed / Lapsed |