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

Claim 3

Method according to claim 1 wherein the step of ensuring substantially equivalent signal-to-noise ratio among data further comprises mathematically accommodating substantially uniform irradiation of the object.

Claim 4

Method according to claim 2 wherein the step of accommodating said substantially uniform irradiation of the object is accomplished by varying irradiation exposure time.

Claim 5

Method according to claim 2 wherein the step of accommodating substantially uniform irradiation of the object is accomplished by proportionately weighting each of a plurality of source scanning positions which contribute to the same Radon datum.

Claim 6

Method according to claim 1 wherein said distribution of Radon data at any point enclosed by said planar projected curve corresponds to the number of times a line at said point, being normal to a segment connecting said point to an object centered origin, intersects said planar projected curve.

Claim 7

Method according to claim 5 wherein said step of providing uniform distribution of Radon data is automatically ensured by geometrically restricting said curve to a continuous, convex, closed curve, such that any said line intersects said curve in two and only two points, thereby ensuring uniformity.

Claim 8

Method according to claim 1 wherein the step of discretely sampling further comprises preserving relative uniformity among a plurality of planar projections, a technique herein referred to as down-sampling.

Claim 9

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: 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.

Claim 10

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: 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.