Patent Number: 
Section: claims

1. An X-ray collimator comprising:three or more high attenuation layers, each comprising a high-Z material, wherein each high attenuation layer includes two or more through holes;wherein the high attenuation layers are arranged in a layer by layer stack to form a collimator having an input face and an output face;wherein the through holes of the high attenuation layers combine to form four or more channels extending through the collimator from the input face and to the output face;wherein at least two of the channels intersect within the collimator at a location other than at the input face or at the output face. 2. The X-ray collimator of claim 1, wherein said high-Z material is selected from the group consisting of brass, tungsten, lead, molybdenum, and mixtures or alloys thereof. 3. The X-ray collimator of claim 1, wherein at least one pair of adjacent said high attenuation layers are separated by an air gap. 4. The X-ray collimator of claim 1, wherein at least one pair of adjacent said high attenuation layers are separated by a transparent layer. 5. The X-ray collimator of claim 4, wherein said transparent layer comprises a material selected from the group consisting of low-Z materials, low density plastics, fiber material, carbon fiber, Al, and microspheres in an epoxy matrix. 6. The X-ray collimator of claim 1, wherein at least one of said channels intersects with two or more of said channels within the collimator at locations other than at said input face or at said output face. 7. The X-ray collimator of claim 1, wherein each of said channels is centered on a straight line. 8. The X-ray collimator of claim 1, wherein each of said channels is larger at said output face than at said input face. 9. The X-ray collimator of claim 1, further comprising a filter layer adjacent to said input face and covering one or more of said channels, wherein said filter layer provides independently predetermined levels of X-ray attenuation for each of the covered channels. 10. The X-ray collimator of claim 1, further comprising a filter layer adjacent to said output face and covering one or more of said channels, wherein said filter layer provides independently predetermined levels of X-ray attenuation for each of the covered channels. 11. The X-ray collimator of claim 1, further comprising a filter layer between said input face and said output face and interrupting one or more of said channels, wherein said filter layer provides independently predetermined levels of X-ray attenuation for each of the interrupted channels. 12. An X-ray imaging system comprising:one or more X-ray sources providing two or more X-ray source locations;two or more X-ray detectors;an X-ray collimator according to claim 1; andwherein each said channel of said X-ray collimator is aligned to permit X-rays to travel from one of the X-ray source locations to one of the X-ray detectors. 13. The imaging system of claim 12, wherein X-rays emitted from said source locations and directed away from any of said X-ray detectors are substantially absorbed in said X-ray collimator. 14. The imaging system of claim 12, wherein said channels permit X-rays to travel from each of said X-ray source locations to all of said X-ray detectors. 15. The imaging system of claim 12, wherein said channels permit X-rays to travel from each of said X-ray source locations to one or more of said X-ray detectors. 16. The imaging system of claim 12, wherein said imaging system is selected from the group consisting of computerized tomography systems, x-ray fluoroscopy systems, or tomosynthesis systems.