Cast collimators for CT detectors and methods of making same

Abstract

Cast collimators for use in CT imaging systems are described, as are methods of making them. Such collimators may comprise pre-patient collimators, pre-patient filter/collimator assemblies, and/or post-patient collimators. The filters and/or collimators may be made of any suitable high-density, high atomic number material such as lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, tungsten suspended in a slurry, or the like. Embodiments of these collimators comprise specially-designed channels and vanes that allow them to be precision cast to the necessary degree of accuracy. These channels and vanes are preferably tapered. These collimators and filter/collimator assemblies help minimize the x-ray dose to the patient by minimizing the scattered radiation creation mechanism and by collimating out much of the scattered radiation that would otherwise be subjected to the patient. These collimators may be cast as either single piece structures, or multiple pieces that can be operatively connected together.

What is claimed is:  
     
         1 . A collimator for a CT imaging system, the collimator comprising: 
 a two-dimensional honeycomb structure,    wherein the two-dimensional honeycomb structure is made via a casting process, the two-dimensional honeycomb structure comprises channels of a predetermined shape running between channel walls of a predetermined thickness, and the two-dimensional honeycomb structure is capable of meeting predetermined precision requirements.    
     
     
         2 . The collimator of  claim 1 , wherein the collimator is utilized as a pre-patient collimator and further comprises a filter operatively coupled thereto.  
     
     
         3 . The collimator of  claim 2 , wherein the filter comprises a suitable high-density, high atomic number material.  
     
     
         4 . The collimator of  claim 3 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.  
     
     
         5 . The collimator of  claim 2 , wherein the filter comprises a three-dimensional insert that is operatively positioned within the channels of the two-dimensional honeycomb structure.  
     
     
         6 . The collimator of  claim 5 , wherein the filter comprises a suitable high-density, high atomic number material.  
     
     
         7 . The collimator of  claim 6 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.  
     
     
         8 . The collimator of  claim 1 , wherein the two-dimensional honeycomb structure comprises a suitable high-density, high atomic number material.  
     
     
         9 . The collimator of  claim 8 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.  
     
     
         10 . The collimator of  claim 1 , wherein the collimator is utilized as a post-patient collimator.  
     
     
         11 . The collimator of  claim 10 , wherein the predetermined shape of the channels comprises at least one of: rectangular, circular, ovular, trapezoidal, hexagonal, and square.  
     
     
         12 . The collimator of  claim 10 , wherein the channels are tapered to create a first aperture proximate an x-ray entry surface of the collimator that is larger than a second aperture proximate an x-ray exit surface of the collimator.  
     
     
         13 . The collimator of  claim 10 , wherein the two-dimensional honeycomb structure comprises a suitable high-density, high atomic number material.  
     
     
         14 . The collimator of  claim 13 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.  
     
     
         15 . A filter for use in pre-patient filter/collimator assemblies in CT imaging systems, the filter comprising a suitable high-density, high atomic number material that is capable of absorbing x-ray radiation.  
     
     
         16 . The filter of  claim 15 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.  
     
     
         17 . A pre-patient filter and collimator assembly for use in CT imaging systems, the assembly comprising: 
 a filter component; and    a collimator component,    wherein the filter component is operatively coupled to the collimator component and the collimator component comprises a two-dimensional honeycomb structure comprising channels of a predetermined shape running between channel walls of a predetermined thickness.    
     
     
         18 . The pre-patient filter and collimator assembly of  claim 17 , wherein the filter component comprises a suitable high-density, high atomic number material.  
     
     
         19 . The pre-patient filter and collimator assembly of  claim 18 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.  
     
     
         20 . The pre-patient filter and collimator assembly of  claim 17 , wherein the collimator component comprises a suitable high-density, high atomic number material.  
     
     
         21 . The pre-patient filter and collimator assembly of  claim 18 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.  
     
     
         22 . The pre-patient filter and collimator assembly of  claim 17 , wherein the filter component comprises a three-dimensional insert that is operatively positioned within the channels of the two-dimensional honeycomb structure.  
     
     
         23 . A post-patient collimator for use in CT imaging systems, the collimator comprising: 
 a two-dimensional honeycomb structure comprising channels of a predetermined shape running between channel walls of a predetermined thickness,    wherein the two-dimensional honeycomb structure is capable of meeting predetermined precision requirements.    
     
     
         24 . The post-patient collimator of  claim 23 , made via a casting process.  
     
     
         25 . The post-patient collimator of  claim 23 , wherein the predetermined shape of the channels comprises at least one of: rectangular, circular, ovular, trapezoidal, hexagonal, and square.  
     
     
         26 . The post-patient collimator of  claim 23 , wherein the channels are tapered to create a first aperture proximate an x-ray entry surface of the collimator that is larger than a second aperture proximate an x-ray exit surface of the collimator.  
     
     
         27 . The post-patient collimator of  claim 23 , wherein the two-dimensional honeycomb structure comprises a suitable high-density, high atomic number material.  
     
     
         28 . The post-patient collimator of  claim 27 , wherein the suitable high-density, high atomic number material comprises at least one of: lead, a lead alloy, tantalum, tungsten, tungsten suspended in an epoxy matrix, and tungsten suspended in a slurry.