X-ray chopper wheel assembly and method

1. An x-ray chopper wheel assembly comprising:

a chopper wheel having a solid area configured to block x-ray radiation received at a source side of the chopper wheel from an x-ray source, the chopper wheel defining one or more openings configured to pass x-ray radiation from the source side of the chopper wheel to an output side of the chopper wheel; and

a source-side scatter plate arranged relative to the chopper wheel with a source-side gap in a range of approximately 0.2 mm to approximately 2.0 mm between the source-side scatter plate and the source side of the chopper wheel.

2. The x-ray chopper wheel assembly of claim 1 , wherein the source-side gap is in a range of approximately 0.5 mm to approximately 1.25 mm.

3. The x-ray chopper wheel assembly of claim 2 , wherein the source-side gap is in a range of approximately 0.5 mm to approximately 0.75 mm.

4. The x-ray chopper wheel assembly of claim 2 , wherein the source-side gap is in a range of approximately 0.02 mm to approximately 0.04 mm.

5. A method of limiting x-ray leakage from an x-ray chopper wheel assembly, the method comprising:

configuring a chopper wheel of an x-ray chopper wheel assembly to have a solid area configured to block x-ray radiation received at a source side of the chopper wheel from an x-ray source;

configuring the chopper wheel to define one or more openings to pass x-ray radiation from the source side of the chopper wheel to an output side of the chopper wheel; and

arranging a source-side scatter plate of the chopper wheel assembly relative to the chopper wheel with a source-side gap in a range of approximately 0.2 mm to approximately 2.0 mm between the source-side scatter plate and the source side of the chopper wheel to limit leakage of scattered x-rays from the x-ray chopper wheel assembly.

6. A method of limiting x-ray leakage from an x-ray chopper wheel assembly, the method comprising:

configuring a disk chopper wheel of an x-ray chopper wheel assembly to receive, at a source side of the disk chopper wheel, x-ray radiation from an x-ray source; and

arranging a source-side scatter plate of the x-ray chopper wheel assembly relative to the disk chopper wheel to cause a substantial confinement of x-rays that are scattered from the disk chopper wheel.

7. The method of claim 6 , wherein arranging a source-side scatter plate to cause the substantial confinement includes arranging the source-side scatter plate to limit leakage of scattered radiation to no more than 10% of scattered radiation or to a dose of no more than 0.5 milli-Rem per hour at a distance of 5 cm away from the outer surface of the assembly, whichever is greater.

8. The method of claim 6 , wherein:

configuring the disk chopper wheel includes configuring to rotate about a rotation axis thereof, the rotation axis perpendicular to a rotation plane of the disk chopper wheel, the disk chopper wheel having a solid cross-sectional area in the rotation plane,

the method further including configuring the source-side scatter plate to have a solid cross-sectional area in a plane substantially parallel to the rotation plane of the disk chopper wheel, with the solid cross-sectional area of the source-side scatter plate being less than 50% of the cross-sectional area of the disk chopper wheel.

9. The method of claim 8 , further including configuring the source-side scatter plate to have the solid cross-sectional area less than 25% of the cross-sectional area of the disk chopper wheel.

10. The method of claim 9 , further including configuring the source-side scatter plate to have the solid cross-sectional area less than 10% of the cross-sectional area of the disk chopper wheel.

11. The method of claim 6 , wherein arranging a source-side scatter plate of the x-ray chopper wheel assembly relative to the disk chopper wheel includes securing the source-side scatter plate in the plane substantially parallel to the rotation plane of the disk chopper wheel with a source-side gap between the source-side scatter plate and the source side of the disk chopper wheel, the source-side gap being in a range of a in a range of approximately 0.2 mm to approximately 2.0 mm.

12. The method of claim 6 , further including configuring the source-side scatter plate to be comprised of pure or alloyed lead, tin, iron, tungsten, or another high-Z material.

13. The method of claim 6 , further including configuring the source-side scatter plate to have a thickness on the order of 1.0 mm.

14. The method of claim 6 , further comprising:

configuring the disk chopper wheel to define one or more radial slit openings configured to pass x-ray radiation from the source side of the disk chopper wheel to an output side of the disk chopper wheel; and

configuring a cross-sectional area of the source-side scatter plate to be in a range of about 100% to about 5,000% larger than an open cross-sectional area of one of the one or more radial slit openings in a rotation plane of the disk chopper wheel.

15. The method of claim 6 , further comprising:

configuring the disk chopper wheel to define one or more radial slit openings configured to pass x-ray radiation from the source side of the disk chopper wheel to an output side of the disk chopper wheel; and

configuring the source-side scatter plate to have a plate width in a direction parallel to a radial direction of the disk chopper wheel, the plate width being in a range of about 10% to about 70% greater than a slit length of one of the one or more radial slit openings in the radial direction of the disk chopper wheel.

16. The method of claim 6 , further comprising:

configuring the disk chopper wheel to rotate about a rotation axis thereof, with the rotation axis perpendicular to a rotation plane of the disk chopper wheel, and to have a solid cross-sectional area in the rotation plane; and

configuring an output-side scatter plate, to define an open slot therein configured to pass x-ray radiation, to absorb x-ray radiation over a solid cross-sectional area in a plane parallel to the rotation plane of the disk chopper wheel, and to have the solid cross-sectional area of the output-side scatter plate substantially smaller than the solid cross-sectional area of the disk.

17. The method of claim 6 , further comprising:

configuring the source-side scatter plate to output a fan beam of x-rays through an open slot defined therein; and

configuring the disk chopper wheel with the arranged source-side scatter plate to output a pencil beam of x-rays.

18. A method of limiting x-ray leakage from an x-ray chopper wheel assembly, the method comprising:

receiving, at a source side of a disk chopper wheel of the x-ray chopper wheel assembly, x-ray radiation from an x-ray source; and

substantially confining x-rays that are scattered from the disk chopper wheel by using a source-side scatter plate arranged relative to the disk chopper wheel.

19. The method of claim 18 , wherein substantially confining x-rays includes using the source-side scatter plate arranged with a source-side gap in a range of approximately 0.2 mm to approximately 2.0 mm between the source-side scatter plate and the source side of the chopper wheel.