Patent Number: 
Section: claims

1. An x-ray chopper wheel assembly comprising:a disk chopper wheel configured 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 disk chopper wheel configured to absorb x-ray radiation received from an x-ray source at a source side of the disk chopper wheel, the disk chopper wheel defining one or more 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; andan output-side scatter plate arranged at the output side of the disk chopper wheel and configured to absorb x-rays scattered from the disk chopper wheel, the output-side scatter plate defining an open slot therein configured to pass x-ray radiation, the output-side scatter plate having a solid cross-sectional area in a plane substantially parallel to the rotation plane of the disk chopper wheel, wherein the solid cross-sectional area of the output-side scatter plate is substantially smaller than the solid cross-sectional area of the disk chopper wheel. 2. The assembly of claim 1, wherein the output-side scatter plate is secured relative to the disk chopper wheel with an output-side gap between the output-side scatter plate and the output side of the disk chopper wheel, the output-side gap in a range of approximately 0.5 mm to approximately 1.0 mm. 3. The assembly of claim 1, wherein the solid cross-sectional area of the output-side scatter plate is less than 50%, less than 25%, or less than 10% of the cross-sectional area of the disk chopper wheel. 4. The assembly of claim 1, wherein the output-side scatter plate comprises tungsten or another high-Z material and has a thickness on the order of 1.0 mm. 5. The assembly of claim 1, wherein the one or more openings are one or more radial slit openings having a slit length in a radial direction of the disk chopper wheel, and wherein the output-side scatter plate has a plate width in a direction parallel to the radial direction of the disk chopper wheel, the plate width being in a range of about 10% to about 70% greater than the slit length. 6. The assembly of claim 1, further comprising a source-side scatter plate having a solid cross-sectional area in a plane substantially parallel to the rotation plane of the disk chopper wheel, the source-side scatter plate configured to absorb x-ray radiation and defining an open slot therein configured to pass x-ray radiation, wherein the solid cross-sectional area of the source-side scatter plate is substantially smaller than the solid cross-sectional area of the disk chopper wheel. 7. The assembly of claim 6, wherein the disk chopper wheel and source-side scatter plate are arranged relative to each other to confine substantially x-ray radiation scattered from the disk chopper wheel. 8. The assembly of claim 7, wherein the solid cross-sectional area of the disk chopper wheel, the solid cross-sectional area of the source-side scatter plate, and a source-side gap between the disk chopper wheel and the source-side scatter plate limit leakage of scattered radiation to no more than 50% of scattered radiation or to a dose of no more than 5 milli-Rem per hour at a distance of 5 cm away from an outer surface of the assembly, whichever is greater. 9. The assembly of claim 8, wherein the solid cross-sectional area of the disk chopper wheel, the solid cross-sectional area of the source-side scatter plate, and a source-side gap between the disk chopper wheel and the source-side scatter plate 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. 10. The assembly of claim 8, wherein the solid cross-sectional area of the source-side scatter plate is less than 50%, less than 25%, or less than 10% of the cross-sectional area of the disk chopper wheel. 11. The assembly of claim 6, wherein a source-side gap between the source-side scatter plate and the source side of the disk chopper wheel is in a range of approximately 0.5 mm to approximately 1.0 mm. 12. The assembly of claim 6, wherein the source-side scatter plate comprises tungsten or another high-Z material and has a thickness on the order of 1.0 mm. 13. The assembly of claim 6, wherein the source-side scatter plate is configured to output a fan beam of x-rays through the open slot therein, which, in combination with the chopper wheel and output-side scatter plate, enables the assembly to output a pencil beam of x-rays. 14. The assembly of claim 1, wherein the x-ray chopper wheel assembly is configured to be mounted within a handheld x-ray scanner. 15. The assembly of claim 1, wherein the x-ray chopper wheel assembly is configured to be mounted within a fixed-mount or mobile x-ray scanning system. 16. 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; anda source-side scatter plate arranged relative to the chopper wheel with a source-side gap in a range of approximately 0.5 mm to approximately 1.0 mm between the source-side scatter plate and the source side of the chopper wheel, the source-side scatter plate being arranged to limit leakage, from the x-ray chopper wheel assembly, of x-rays scattered from the chopper wheel. 17. The assembly of claim 16, wherein the disk chopper wheel and source-side scatter plate are arranged relative to each other further to confine substantially the x-rays scattered from the disk chopper wheel. 18. The assembly of claim 16, further comprising an output-side scatter plate arranged at the output side of the chopper wheel and configured to absorb x-rays scattered from the chopper wheel, the output-side scatter plate defining an open slot therein configured to pass x-ray radiation, the output-side scatter plate having a solid area that is substantially smaller than the solid area of the chopper wheel. 19. 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 disk 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; andan output-side scatter plate arranged relative to the chopper wheel with an output-side gap in a range of approximately 0.5 mm to approximately 1.0 mm between the output-side scatter plate and the output side of the chopper wheel. 20. The assembly of claim 19, further comprising a source-side scatter plate arranged at the source side of the chopper wheel and configured to absorb x-rays scattered from the chopper wheel, the source-side scatter plate defining an open slot therein configured to pass x-ray radiation, the source-side scatter plate having a solid area that is substantially smaller than the solid area of the chopper wheel.