Patent Number: 
Section: claims

1. An x-ray reflector comprising:a substrate;a first layer formed on the substrate, the first layer including a relatively higher-Z material, where Z represents the atomic number; anda second layer formed on the first layer, the second layer including a relatively lower-Z material;both of the first layer and the second layer exhibiting a taper along an axis extending between a first end of the substrate and a second end of the substrate, at least one of the first layer and the second layer also substantially exhibiting arcuate uniformity along a ciiven arc defined by a radius extending from a reference point on the axis; andwherein, at any given axial position along the axial direction and treating the first and second layers as together representing a bi-layer structure, a thickness of the first layer represents about ⅖ of a total thickness of the bi-layer structure, and a thickness of the second layer represents about ⅗ of the total thickness of the bi-layer structure. 2. The x-ray reflector of claim 1, wherein the taper is non-linear. 3. The x-ray reflector of claim 2, wherein the taper is described by the following relation,            t              axp        ⁢                                  ⁢        1                    t              axp        ⁢                                  ⁢        2              ≈            sin      ⁢                          ⁢      α1              sin      ⁢                          ⁢      α2      where taxp1 represents a combined thickness of the first and second layers at a first axial position along the axial direction, α1 represents an incidence angle of x-rays from a source thereof that impinge upon the respective layer at the first axial taxp2 represents a combined thickness of the first and second layers at a second axial position along the axial direction farther from the source than the first axial position, and α2 represents an incidence angle of x-rays from the source that impinge upon the respective layer at the second axial position. 4. The x-ray reflector of claim 1, wherein:the first and second layers together represent a bi-layer structure; andthe x-ray reflector further includes a plurality of the bi-layer structures stacked successively upon each other. 5. A method of making a narrow band x-ray filter, the method comprising;providing a base;providing one or more x-ray reflectors, each reflector having at least one bi-layer structure that includes a relatively higher-Z material and a relatively lower-Z material, the bi-layer structure exhibiting a taper along an axis, the bi-layer structure also substantially exhibiting arcuate uniformity along a given arc defined by a radius extending from a reference point on the axis; andstacking the one or more reflectors upon the substrate;wherein the step of stacking, for each reflector, includes the following,disposing a set of one or more spacing bodies on a respective underlying structure, anddisposing the reflector on the set of one or more spacing bodies. 6. The method of claim 5, further comprising:mechanically connecting the one or more successively-stacked units to the substrate so as to form a sheaf of reflectors. 7. A filter of to produce one or more narrow band beams of x-rays, the filter comprising:a base;a sheaf of one or more x-ray reflectors stacked upon each other, the sheaf being disposed upon the base, each reflector having at least one bi-layer structure that includes a relatively higher-Z material and a relatively lower-Z material, the bi-layer structure exhibiting a taper along an axis, the bi-layer structure also substantially exhibiting arcuate uniformity along a given arc defined by a radius extending from a reference point on the axis; anda set of one or more spacing bodies to support each of the one or more x-ray reflectors, respectively;each set of one or more spacing bodies being interposed between a respective underlying structure and a respective reflector. 8. A filter to produce one or more narrow band beams of x-rays, the filter comprising:a base; anda sheaf of one or more x-ray reflectors stacked upon each other, the sheaf being disposed upon the base, each reflector having at least one bi-layer structure that includes a relatively higher-Z material and a relatively lower-Z material, the bi-layer structure exhibiting a taper along an axis, the bi-layer structure also substantially exhibiting arcuate uniformity along a given arc defined by a radius extending from a reference point on the axis;wherein the sheaf includes at least a first and a second one of the x-ray reflectors stacked upon each other; andwherein a taper of the at least one bi-layer structure in the first reflector differs from a taper of the at least one bi-layer structure in the second reflector such that the first reflector is configured to produce a different narrow band of x-rays than the second reflector. 9. An apparatus to produce one or more narrow band beams of x-rays, the apparatus comprising:a source of a first x-ray beam;a multispectral narrow bands x-ray filter having a first end, a second end and one or more focal points located nearer to the first end than to the second end,the filter including at least one reflector of x-rays, each reflector having at least one bi-layer structure that includes a relatively higher-Z material and a relatively lower-Z material, the bi-layer structure exhibiting a taper along an axis, the bi-layer structure also substantially exhibiting arcuate uniformity along a given arc defined by a radius extending from a reference point on the axis;the source being disposed substantially at an instance of the one or more focal points such that at least two narrow band beams of x-rays emanate from the second end of the filter;the filter including at least first and second reflectors; anda taper of the at least one bi-layer structure in the first reflector differing from a taper of the at least one bi-layer structure in the second reflector such that the first reflector is configured to produce a different narrow band of x-rays than the second reflector. 10. The apparatus of claim 9, wherein:at least one of the source and the filter is movable in at least one dimension; andthe apparatus further comprises a focal adjustment mechanism operable to move at least one of the source and filter in the at least one dimension and thus tune center wavelengths of the at least two narrow band beams of x-rays, respectively. 11. An x-ray imaging device comprising:the apparatus of claim 9,an arrangement of x-ray detectors; anda gantry to hold at least the source, filter and detectors;wherein the gantry is operable to move the source, filter and detectors in at least two dimensions with respect to a subject that is to be imaged. 12. The apparatus of claim 11, further comprising:a movable platform operable to move the subject relative to one of a position of and motion of the gantry. 13. The apparatus of claim 11, wherein the gantry is arranged to move at least the source, filter and detectors in a type of one of a circular, helical, linear and pendulum type of motion relative to one of a position of and motion of the subject. 14. A method of using x-rays to produce an image of a subject, the method comprising:providing an x-ray filter including one or more x-ray reflectors, each reflector having at least one bi-layer structure that includes a relatively higher-Z material and a relatively lower-Z material, the bi-layer structure exhibiting a taper in an axial direction along an axis;producing at least two narrow band beams of x-rays using the x-ray filter;disposing a subject in the at least two narrow band beams; anddisposing at least one array of x-ray detectors in the at least two narrow band beams downstream from the subject;wherein the step of producing includes the following,providing a narrow band x-ray filter,configuring a source of a broad band beam of x-rays at a first focal length of the filter so as to achieve a first central wavelength of a resulting narrow band of x-rays,reconfiguring, after initial occurrences of the steps of disposing the subject and disposing the at least one array of x-ray detectors, a source of a broad band beam of x-rays at a second focal length of the filter so as to achieve a second central wavelength different than the first central wavelength, andrepeating the steps of disposing the subject and disposing the at least one array of x-ray detectors. 15. The method of claim 14, wherein the step of producing generates the at least two narrow band beams of x-rays substantially concurrently. 16. An apparatus to produce at least two narrow band beams of x-rays having different center wavelengths, respectively, the apparatus comprising:a source of a relatively broad band beam of x-rays; andan x-ray filter operable to produce one or more narrow band beams of x-rays, the filter having a first end, a second end and one or more focal points located nearer to the first end than to the second end;the source being disposed substantially at an instance of the one or more focal points such that one or more narrow band beams of x-rays emanate from the second end of the filter;at least one of the following being true,the filter being arranged with respect to the source to produce susbstantially concurrently according to a single arrangement at least two narrow band beams of x-rays having different center wavelengths, respectively, andthe filter and the source being adaptively arrangible into at least two arrangements with respect to the source to produce the at least two narrow band beams of x-rays. 17. The apparatus of claim 16, wherein:the filter is a multispectral narrow bands type of x-ray filter that includes at least first and second reflectors, each reflector having at least one bi-layer structure that includes a relatively higher-Z material and a relatively lower-Z material, the bi-layer structure exhibiting a taper in an axial direction; anda taper of the at least one bi-layer structure in the first reflector differs from a taper of the at least one bi-layer structure in the second reflector such that the first reflector is configured to produce a different narrow band of x-rays than the second reflector. 18. The apparatus of claim 17, wherein:at least one of the source and the filter is movable in at least one dimension; andthe apparatus further comprises a focal adjustment mechanism operable to move at least one of the source and filter in the at least one dimension and thus tune center wavelengths of the at least two narrow band beams of x-rays, respectively. 19. The apparatus of claim 16, wherein:the filter is a unispectral type of x-ray filter operable to produce one narrow band beam of x-rays;at least one of the source and the filter is movable in at least one dimension such that the adaptive arrangibility of the filter and the source includes the following,a first arrangement in which the source is disposed at a first focal length of the filter so as to achieve a first central wavelength of a resulting narrow band of x-rays, anda second arrangement in which the source is disposed at a second focal length of the filter so as to achieve a second central wavelength of a resulting narrow band of x-rays; andthe apparatus further comprises a focal adjustment mechanism operable to move at least one of the source and filter in the at least one dimension so as to selectively adopt one of the first arrangement and the second arrangement and thus tune a center wavelength of the one narrow band beam of x-rays. 20. An x-ray imaging device comprising:the apparatus of claim 16;an arrangement of x-ray detectors; anda gantry to hold at least the source, filter and detectors;wherein the gantry is operable to move the source, filter and detectors in at least two dimensions with respect to a subject that is to be imaged. 21. A method of producing at least two narrow band beams of x-rays, the method comprising:providing a source of a relatively broad band beam of x-rays;providing an x-ray filter operable to produce one narrow band beam of x-rays, the filter having a first end, a second end and one or more focal points located nearer to the first end than to the second end;disposing the source substantially at a first instance of the one or more focal points of the filter so as to achieve a first central wavelength of a resulting first narrow band beam of x-rays; anddisposing the source substantially at a second instance of the one or more focal points of the filter so as to achieve a second central wavelength of a resulting second narrow band beam of x-rays. 22. The method of claim 21, wherein the step of disposing the source at the second instance of the one or more focal points includes:moving at least one of the source and filter in at least one dimension to change an output of the filter from exhibiting the first central wavelength to exhibiting the second central wavelength. 23. A method of using x-rays to produce an image of a subject, the method comprising:producing at least two narrow band beams of x-rays according to the method of claim 21;disposing a subject in the at least two narrow band beams; anddisposing at least one array of x-ray detectors in the at least two narrow band beams downstream from the subject. 24. The method of claim 14, wherein the bi-layer structure also substantially exhibits arcuate uniformity along a given arc defined by a radius extending from a reference point on the axis. 25. The x-ray reflector of claim 1, wherein an interface between the first layer and the second layer is substantially planar. 26. The method of claim 5, wherein, for each of the at least one bi-layer structure, an interface between the relatively higher-Z material and the relatively lower-Z material is substantially planar. 27. The filter of claim 7, wherein, for each of the at least one bi-layer structure, an interface between the relatively higher-Z material and the relatively lower-Z material is substantially planar. 28. The apparatus of claim 9, wherein, for each of the at least one bi-layer structure, an interface between the relatively higher-Z material and the relatively lower-Z material is substantially planar. 29. The filter of claim 8, wherein, for each of the at least one bi-layer structure, an interface between the relatively higher-Z material and the relatively lower-Z material is substantially planar.