Image positioning method and system for tomosynthesis in a digital X-ray radiography system
First Claim
1. A method for aligning an image of a target object for tomosynthesis in a x-ray radiography system of the type including an x-ray source, and an x-ray detector system for detecting x-rays emitted from the x-ray source and transmitted through said object, comprising:
- a. positioning at least one marker between said x-ray source and said detector system;
b. moving said x-ray source after step a; and
c. measuring a shift in the image of the at least one marker caused by said motion of said x-ray source;
d. correlating the shift measured in step c with a corresponding shift in the image of a point of interest in the target object, thereby determining a shift in the image of the point of interest in the target object caused by said motion of said x-ray source.
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Accused Products
Abstract
The present invention provides a method and system for determining the position of the image of a target object or the position of the x-ray source in digital tomosynthesis, as the x-ray source is moved relative to the object so as to obtain multiple two-dimensional images of the object from multiple angles. At least one marker, characterized by a simple and known image pattern, is disposed between an x-ray source and a detector system. The shift in the image of the object, resulting from the movement of the x-ray source during tomosynthesis, is calculated to a desired resolution using the readily observable shift in the image of the marker. The x-ray source may be translated along a plane parallel to the plane of the detector system, or may be rotated about a fixed center.
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Citations
19 Claims
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1. A method for aligning an image of a target object for tomosynthesis in a x-ray radiography system of the type including an x-ray source, and an x-ray detector system for detecting x-rays emitted from the x-ray source and transmitted through said object, comprising:
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a. positioning at least one marker between said x-ray source and said detector system; b. moving said x-ray source after step a; and c. measuring a shift in the image of the at least one marker caused by said motion of said x-ray source; d. correlating the shift measured in step c with a corresponding shift in the image of a point of interest in the target object, thereby determining a shift in the image of the point of interest in the target object caused by said motion of said x-ray source. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for obtaining tomosynthesis data of an object, the apparatus comprising:
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a. an x-ray source for generating radiation directed toward said object; b. an x-ray detector system disposed in a detector plane for detecting radiation transmitted through said object and for generating object image data representative of an image of said object on said detector plane; and c. at least one marker disposed between said x-ray source and said detector so that the detector system can receive x-rays transmitted through the marker to generate marker image data representative of an image of the marker on the detector plane; wherein the x-ray source is disposed at a distance Zs from said detector plane, as measured along a longitudinal direction orthogonal to said detector plane; wherein the marker is disposed at a distance Zm from said detector plane as measured along said longitudinal direction; wherein Zs and Zm are selected so as to avoid overlap between the image of the object and the image of the marker, and so that when the x-ray source is moved after the marker is disposed between the x-ray source and the detector system, a shift Δ
Xp in the image of a point of interest P in the object on said detector plane, resulting from the motion of said x-ray source, is correlated to a corresponding shift Δ
Xm in the image of said marker on said detector plane by a relationship given by;
Δ
XpΔ
Xm*(Zp/Zm)*(Zs−
Zm)/(Zs−
Zp),where Zp is the distance of the point of interest P from said detector plane along said longitudinal direction, and wherein the marker comprises a plurality of linear parallel stripes disposed along a direction parallel to said detector plane. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for obtaining tomosynthesis data of an object, the apparatus comprising:
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A. an x-ray source for generating radiation directed toward said object; B. an x-ray detector disposed in a detector plane, the detector being adapted to detect x-rays transmitted through said object and to generate object image data for an image of said object on said detector plane; and C. at least one marker disposed between said x-ray source and said detector at a fixed location with respect to said detector so that the detector is responsive to x-rays transmitted through said marker to generate marker image data representative of an image of the marker on said detector plane; wherein a displacement of said x-ray source within a lateral plane parallel to said detector plane produces a corresponding lateral shift in said image of the marker; and wherein a shift in the image of a point of interest within the object, resulting from said displacement of said x-ray source, is correlated by a known relationship to said shift in said image of the marker, and to the distance of said point of interest from said detector plane along a longitudinal direction orthogonal to said detector plane; and wherein said lateral plane is defined by mutually perpendicular x- and y-coordinate axes; wherein said at least one marker comprises; a) at least a first marker that includes a plurality of linear and parallel stripes disposed along an x-direction parallel to said x-coordinate axis; and b) at least a second marker that includes a plurality of linear and parallel stripes disposed along a y-direction parallel to said y-coordinate axis; wherein a displacement of said radiation source along the x- and y-directions, respectively, produces corresponding shifts in the image of said first and said second markers along the x- and the y-directions, respectively; wherein the shift along the x-direction in the image of a point of interest within the object, resulting from a displacement of said radiation source along the x-direction, is correlated by a known relationship to the shift in the image of said first marker along the x-direction; and wherein the shift along the y-direction in the image of a point of interest within the object, resulting from a displacement of said radiation source along the y-direction, is correlated by a known relationship to the shift in the image of said second marker along the y-direction.
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Specification