Method and apparatus for acquiring a uniform distribution of radon data sufficiently dense to constitute a complete set for exact image reconstruction of an object irradiated by a cone beam source
First Claim
1. A method for acquiring discrete cone beam projection data along a three dimensional (3D) scanning trajectory in order to obtain a substantially uniform distribution of Radon data that is sufficiently dense to ensure the acquisition of a complete set of Radon data wherein said Radon data is organized onto a plurality of co-axial planes for exact image reconstruction of an object irradiated by a scanning cone beam source, said method comprising the steps:
- ensuring substantially equivalent signal-to-noise ratio among cone beam projection data;
providing a 3D scanning trajectory such that at least a composite of corresponding planar projections of said trajectory forms a continuous, convex, closed curve about a corresponding planar projection of the object being scanned, the step of providing a 3D scanning trajectory further comprising selecting respective portions from a plurality of 3D scanning trajectory projections onto respective planes of said plurality of co-axial planes to collectively form a continuous, convex, closed curve enclosing the respective projection of said object; and
discretely sampling at a corresponding plurality of cone beam source positions along said scanning trajectory in a manner providing uniformity in said distribution of Radon data.
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Abstract
A method and apparatus for acquiring scanning cone beam projection data along a three dimensional scanning trajectory is disclosed. The technique ensures acquisition of a substantially uniform distribution of Radon data that is sufficiently complete for exact image reconstruction of an object irradiated by a scanning cone beam source. By choosing a scanning trajectory whose planar projection onto a plurality of coaxial planes, when taken together, forms a continuous, convex, closed curve about a corresponding projection of the object being scanned; the Radon information obtained therefrom is complete and information coverage is uniform over the region of support of the object. Accordingly, this condition provides a practical, easy to implement, visual method for evaluating candidate three dimensional scanning trajectories.
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Citations
8 Claims
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1. A method for acquiring discrete cone beam projection data along a three dimensional (3D) scanning trajectory in order to obtain a substantially uniform distribution of Radon data that is sufficiently dense to ensure the acquisition of a complete set of Radon data wherein said Radon data is organized onto a plurality of co-axial planes for exact image reconstruction of an object irradiated by a scanning cone beam source, said method comprising the steps:
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ensuring substantially equivalent signal-to-noise ratio among cone beam projection data; providing a 3D scanning trajectory such that at least a composite of corresponding planar projections of said trajectory forms a continuous, convex, closed curve about a corresponding planar projection of the object being scanned, the step of providing a 3D scanning trajectory further comprising selecting respective portions from a plurality of 3D scanning trajectory projections onto respective planes of said plurality of co-axial planes to collectively form a continuous, convex, closed curve enclosing the respective projection of said object; and discretely sampling at a corresponding plurality of cone beam source positions along said scanning trajectory in a manner providing uniformity in said distribution of Radon data. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus for acquiring discrete cone beam projection data along a three dimensional (3D) scanning trajectory in order to obtain a substantially uniform distribution of Radon data on each of a plurality of co-axial planes that is sufficiently dense to ensure the acquisition of a complete set of Radon data for exact image reconstruction of an object irradiated by a scanning cone beam source, said apparatus comprising:
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cone beam source; planar array detector means fixed with respect to said cone beam source; means for scanning along said 3D scanning trajectory wherein said trajectory satisfies the condition that at least a composite of planar projections of said trajectory provides a continuous, convex, closed curve enclosing a corresponding planar projection of the object, said scanning means further including means for selecting respective portions from a plurality of 3D scanning trajectory projections onto respective planes of said plurality of co-axial planes to collectively form a continuous, convex, closed curve enclosing the respective projection of said object; means for discretely sampling cone beam projection data consistently at a select plurality of positions along said scanning trajectory; means for collecting said cone beam projection data for image processing; and means for processing collected cone beam projection data into a three dimensional image by Radon inversion.
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Specification