Patent Number: 
Section: claims

1. An X-ray apparatus comprising:an X-ray source for emitting X-ray radiation; anda beam chopping apparatus coupled to said X-ray source, wherein said beam chopping apparatus is adapted to rotate, receive said X-ray radiation and form a moving beam spot having a variance in frequency, wherein said variance in frequency decreases as said beam chopping apparatus is rotated faster. 2. The X-ray apparatus of claim 1 wherein said beam chopping apparatus comprises a hollow cylinder having at least one helical aperture. 3. The X-ray apparatus of claim 1 wherein said beam chopping apparatus comprises a hollow cylinder having at least two helical apertures. 4. The X-ray apparatus of claim 3 wherein said beam has a linear scan velocity and wherein said linear scan velocity is varied by modifying a pitch and roll of at least one of said helical apertures. 5. The X-ray apparatus of claim 3 wherein said beam has a linear scan velocity and wherein said linear scan velocity is kept constant by modifying a pitch and roll of at least one of said helical apertures. 6. The X-ray apparatus of claim 3 wherein said beam has a spot size and wherein said spot size is varied by modifying an aperture width of at least one of said helical apertures. 7. The X-ray apparatus of claim 3 wherein said beam has a spot size and wherein said spot size is kept constant by modifying an aperture width of at least one of said helical apertures. 8. The X-ray apparatus of claim 2 further comprising a motor for rotating said cylinder. 9. The X-ray apparatus of claim 8 further comprising a controller for dynamically modifying a rotation speed of said cylinder to achieve a predetermined scan velocity. 10. The X-ray apparatus of claim 9 wherein said rotation speed is equal to or less than 80,000 rpm. 11. The X-ray apparatus of claim 8 wherein said beam has a scan velocity and a spot size and wherein scan velocity and spot size can be modified without varying a speed of said motor. 12. The X-ray apparatus of claim 1 wherein said beam chopping apparatus comprises a hollow cylinder having at least two helical apertures, each having a length and an aperture width along said length and wherein said aperture width narrows along length. 13. The X-ray apparatus of claim 1 wherein said beam chopping apparatus comprises a hollow cylinder having at least two helical apertures, each having a length and an aperture width along said length and wherein said aperture width increases along length. 14. An X-ray apparatus comprising:an X-ray source for emitting X-ray radiation; anda beam chopping apparatus coupled to said X-ray source, wherein said beam chopping apparatus rotates and comprises a hollow cylinder with a first end and a second end defining a length of said cylinder and at least one helical aperture extending substantially along said length, wherein said cylinder is adapted to receive said X-ray radiation and emit said X-ray radiation, having a variance in frequency, through said helical aperture and wherein said variance in frequency decreases as said beam chopping apparatus is rotated faster. 15. The X-ray apparatus of claim 14 wherein said X-ray radiation passes through the helical aperture to produce a beam spot projection pattern, wherein said beam spot projection pattern comprises a beam spot moving vertically with a substantially constant velocity in a plane perpendicular to a plane of the X-ray source. 16. The X-ray apparatus of claim 15 wherein said beam spot projection pattern comprises a beam spot moving vertically with a substantially constant velocity in a plane parallel to a plane of the beam chopping apparatus. 17. The X-ray apparatus of claim 16 wherein said beam spot provides substantially equal illumination of a target object. 18. The X-ray apparatus of claim 14 wherein said beam spot is trapezoidal. 19. The X-ray apparatus of claim 14 wherein said helical aperture has a width that is more narrow at the second end relative to said first end.