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US5444792A
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Process and apparatus for the reconstruction of three-dimensional images of an object using two circular acquisition paths
Assignee: Commissariat à l'Énergie Atomique et Aux Énergies Alternatives
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Filing: 1994-06-13
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Granted: 1995-08-22
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Expires: 2014-06-13
Abstract
Abstract Process for the reconstruction of three-dimensional images of an object. Several measurements are performed by displacing a bidimensional array of sensors, sensitive to a radiation passing through the object or coming from the object in at least two circular paths. The digital method for making it possible to synthesize the informations measured and in particular convert the informations obtained into reference frames linked with the paths in a random reference frame is given. Application to medical imaging or to non-destructive inspection.
Inventors
- 👤 Pierre Grangeat
- 👤 Philippe Rizo
- 👤 Pascal Sire
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:04
CPC Classifications
G; G06; G06T; G06T12/00; G06T12/20; A; A61; A61B; A61B6/00; A61B6/02; A61B6/027; G06T17/00; G06T2211/00; G06T2211/40; G06T2211/421
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
302 words
A process for reconstructing a three-dimensional image of an object, comprising the steps of: using at least one two-dimensional array of sensors for acquiring at least two measurement sets of a function at selected points of the object defined by coordinates in an object reference frame, said function, which represents the image of the object, being a property of a radiation viewed by said sensors, wherein the at least one array travels along at least two circular trajectories around the object, the sensors of each of said at least one array of sensors being focused to a respective common focal point beyond the object and at a constant position with respect to said sensors so that each focal point travels along a respective circular focal trajectory and said sensors view a conical space and one trajectory reference frame and one of the measurement sets being associated with each of the focal trajectories; reconstructing the image of the object from the measurement sets of the image, said image reconstruction including the steps of: computing for each of the measurement sets, sums of the function over planes (P) of a respective plane set of a plane domain, wherein the planes of the respective plane set are defined by coordinates in the trajectory reference frame associated with the measurement step, the planes of the respective plane set crossing the focal trajectory to which the measurement set is associated and including at least one point of the object, so as to get as many sums as said planes; merging in an object reference frame the sums provided in the measurement sets in computing, for each of the planes of the plane domain, coordinates defining said plane; and inverting the merged sums in the object reference frame in order to get the reconstructed image of the object.
Claim 2
Dependent Claim
302 words
A process for reconstructing a three-dimensional image of an object, comprising the steps of: using at least one two-dimensional array of sensors for acquiring at least two measurement sets of a function at selected points of the object defined by coordinates in an object reference frame, said function, which represents the image of the object, being a property of a radiation viewed by said sensors, wherein the at least one array travels along at least two circular trajectories around the object, the sensors of each of said at least one array of sensors being focused to a respective common focal point beyond the object and at a constant position with respect to said sensors so that each focal point travels along a respective circular focal trajectory and said sensors view a conical space and one trajectory reference frame and one of the measurement sets being associated with each of the focal trajectories; reconstructing the image of the object from the measurement sets of the image, said image reconstruction including the steps of: computing for each of the measurement sets, sums of the function over planes (P) of a respective plane set of a plane domain, wherein the planes of the respective plane set are defined by coordinates in the trajectory reference frame associated with the measurement step, the planes of the respective plane set crossing the focal trajectory to which the measurement set is associated and including at least one point of the object, so as to get as many sums as said planes; merging in an object reference frame the sums provided in the measurement sets in computing, for each of the planes of the plane domain, coordinates defining said plane; and inverting the merged sums in the object reference frame in order to get the reconstructed image of the object.
Claim 3
Dependent Claim
25 words
Process for reconstructing three-dimensional images according to claim 1, wherein the trajectory reference frames and object reference frame have an axis with the same direction.
Claim 4
Dependent Claim
35 words
Process for reconstructing three-dimensional images according to claim 1, wherein each of the trajectory reference frames has an axis identical to a rotational axis of the trajectory to which the trajectory reference frame is associated.
Claim 5
Dependent Claim
22 words
Process for reconstructing three-dimensional images according to claim 1, wherein the object reference frame coincides with one of the trajectory reference frames.
Claim 6
Dependent Claim
14 words
Process for reconstructing three-dimensional images according to claim 1, wherein the trajectories are concentric.
Claim 7
Dependent Claim
52 words
Process for reconstructing three-dimensional images according to claim 1, wherein the coordinates that define the planes in the trajectory reference frames and the object reference frame are coordinates of characteristic points obtained by projecting respective origin points of said frames on said planes, the characteristic points being generally different for said frames.
Claim 8
Dependent Claim
51 words
Process for reconstructing three-dimensional images according to claim 1, further comprising in said gathering step, after the conversions, an averaging of sums associated with planes of the plane domain that have a same position in the object while being defined by different coordinates in different ones of said trajectory reference frames.
Claim 9
Dependent Claim
33 words
Process for reconstructing three-dimensional images according to claim 1, wherein the property is an absorption property of the radiation which is produced by a point source placed at each of the focal points.
Claim 10
Dependent Claim
53 words
Process for reconstructing three-dimensional images according to claim 1, wherein the property is an emission activity of the radiation which is produced by the object and wherein, for each of the trajectories, the focal point is defined by an intersection of measurement directions of the sensors of the array moving along said trajectory.
Claim 11
Dependent Claim
18 words
Process according to claim 1, wherein the coordinates defining the planes of the plane domain are spherical coordinates.
Claim 12
Dependent Claim
66 words
Process for reconstructing three-dimensional images according to claim 10, wherein the coordinates in the trajectory reference frames and the object reference frame are spherical coordinates and the gathering of the sums involves a temporary conversion of the spherical coordinates (ρ, Θ, φ) in the trajectory reference frames into cartesian coordinates (X,Y,Z), then a conversion of the cartesian coordinates into spherical coordinates in the object reference frame.
Claim 13
Dependent Claim
54 words
Process according to claim 1, wherein said at least one array of sensors is moved around the object either by rotating said at least one array of sensors around the object or by rotating the object with respect to said at least one array of sensors which is stationary during each of the trajectories.
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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) | 1998-08-21 | 1999-02-20 | 1999-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-21 | 2003-02-20 | 2003-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-21 | 2007-02-20 | 2007-08-22 | $7700.00 | Window Closed / Lapsed |