Patent Number: 
Section: claims

1. An x-ray absorption grid system comprising:at least two individual grids each produced by a lithography technique, said at least two individual grids being arranged atop one another in a direction of radiation propagation therethrough to form a grid combination, and each individual grid comprising a substrate with no gaps therein and a grid area on said substrate exhibiting a grid structure formed on said substrate with said substrate remaining beneath said grid structure, said grid structure comprising a plurality of radiation-absorbing grid webs and grid gaps in alternation;the substrate of each individual grid also comprising an outer region that  extends outside of said grid area;the respective outer regions of the substrate of each of said at least two individual grids comprising toothed structures corresponding to one another at at least two points, said toothed structures being generated in the same lithography technique used to produce the grid structure;said toothed structures being located on the outer region of the substrate of each of said at least two individual grids at a defined position relative to the grid structure on that substrate, to produce a defined alignment of the respective individual grids relative to each other in said grid combination by engagement of the toothed structures of the respective individual grids atop one another; andthe respective grid structures of said at least two individual grids, and said defined position and said defined alignment being structured relative to each other to set an interaction of said respective grid structures with said radiation propagating through said respective grid structures that produces a radiation beam exiting said grid combination that has beam characteristics for phase-contrast CT. 2. An x-ray absorption grid system as claimed in claim 1 wherein at least one of said toothed structures is a positive-negative structure. 3. An x-ray absorption grid system as claimed in claim 1 wherein said outer region in each of said individual grids forms a border at least partially surrounding the grid area thereof. 4. An x-ray absorption grid system as claimed in claim 1 wherein said outer region of each of said individual grids completely surrounds the grid area thereof. 5. An x-ray absorption grid system as claimed in claim 1 wherein said outer region of each of said individual grids comprises multiple external tabs distributed around said grid area, at which said toothed structures are carried. 6. An x-ray absorption grid system as claimed in claim 1 comprising adhesive that adheres said individual grids with one another in said grid combination. 7. An x-ray absorption grid system as claimed in claim 1 comprising at least three of said individual grids arranged atop one another in said combination. 8. An x-ray absorption grid system as claimed in claim 1 wherein the respective toothed structures are positioned to cause all of the individual grids in said grid combination to be congruent with each other with regard to said grid webs and said grid gaps. 9. An x-ray absorption grid system as claimed in claim 1 wherein said toothed structures are positioned on respective individual grids to cause the respective individual grids atop one another in said grid combination to exhibit a defined offset relative to the grid webs and the grid gaps, said offset being perpendicular to a longitudinal direction of said grid webs. 10. An x-ray absorption grid system as claimed in claim 1 wherein said individual grids in said grid combination have respectively different grid periodicities. 11. An x-ray absorption grid system as claimed in claim 1 wherein said individual grids are produced with a LIGA method.