Computed tomography system for imaging of human and small animal

Abstract

Computed tomography device comprising an x-ray source and an x-ray detecting unit. The x-ray source comprises a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, and a collimator. Each electron emitting unit includes an electron field emitting material. The electron field emitting material includes a nanostructured material or a plurality of nanotubes or a plurality of nanowires. Computed tomography methods are also provided.

1 . A computed tomography device, comprising: 
 an x-ray source, the x-ray source comprising a cathode with a plurality of individually programmable electron emitting units that each emit an electron beam upon an application of an electric field, an anode target that emits an x-ray beam upon impact by the emitted electron beam, and    a collimator; and an x-ray detecting unit.    
     
     
         2 . The device of  claim 1 , wherein each electron emitting unit includes an electron field emitting material.  
     
     
         3 . The device of  claim 2 , wherein the electron field emitting material includes a nanostructured material.  
     
     
         4 . The device of  claim 2 , wherein the electron field emitting material includes a plurality of nanotubes or a plurality of nanowires.  
     
     
         5 . The device of  claim 4 , wherein the nanotubes includes at least one field emitting material selected from the group consisting of carbon, boron, and nitrogen.  
     
     
         6 . The device of  claim 4 , wherein the nanowires included at least one field emitting material selected from the group consisting of silicon, germanium, carbon, oxygen, oxide, and nitrides.  
     
     
         7 . The device of  claim 2 , wherein the electron field emitting material includes a plurality of single-wall carbon nanotubes, a plurality of multi-wall carbon nanotubes or a mixture thereof.  
     
     
         8 . The device of  claim 1 , wherein the x-ray source further comprises a gate electrode to extract the emitted electron from one or more of the plurality of individually programmable electron emitting units when the electrical field is applied between the gate electrode and the one or more individually programmable electron emitting units.  
     
     
         9 . The device of  claim 8 , wherein the gate electrode is located between the cathode and the anode target.  
     
     
         10 . The device of  claim 8 , wherein the electrical field is applied such that the gate electrode is at a positive potential with respect to the one or more of the plurality of individually programmable electron emitting units, and a field strength of the electrical field is from 0.1 Volt/micron to 100 Volt/micron.  
     
     
         11 . The device of  claim 1   0 , wherein the field strength is from 0.5 Volt/micron to 20 Volt/micron.  
     
     
         12 . The device of  claim 8 , wherein the electrical field applied to the gate electrode is controlled by a feedback mechanism from the x-ray detecting unit.  
     
     
         13 . The device of  claim 1 , further comprising a control system for data collection and reconstruction.  
     
     
         14 . The device of  claim 1 , further comprising a vacuum container housing the cathode and the anode target.  
     
     
         15 . The device of  claim 1 , wherein at least one of the plurality of individually programmable electron emitting units has an emission threshold of less than 3 Volt/micron for a current density of greater than 0.01 mA/cm 2  and emits 0.1-100 mA total current.  
     
     
         16 . The device of  claim 15 , wherein the current density is greater than 0.1 mA/cm 2 .  
     
     
         17 . The device of  claim 1 , wherein the plurality of individually programmable electron emitting units are arranged linearly on an axis in a plane and each individually programmable electron emitting unit is focused at one of a plurality of focal spots on the anode target.  
     
     
         18 . The device of  claim 17 , wherein the collimator generates a fan beam geometry of x-ray radiation.  
     
     
         19 . The device of  claim 1 , wherein the plurality of individually programmable electron emitting units are arranged over an area of a plane and each individually programmable electron emitting unit is focused at one of a plurality of focal spots on the anode target.  
     
     
         20 . The device of  claim 19 , wherein the collimator generates a fan beam geometry of x-ray radiation.  
     
     
         21 . The device of  claim 1 , wherein the device is portable.  
     
     
         22 . A method to operate a computed tomography device, the computed tomography device including an x-ray source, the x-ray source comprising a cathode with a plurality of individually programmable electron emitting units that each emit an electron beam upon an application of an electric field, an anode target that emits an x-ray beam upon impact by the emitted electron beam, a collimator, and an x-ray detecting unit, the method comprising: 
 applying the electric field to at least a first of the plurality of individually programmable electron emitting units to cause the emission of an electron beam;    focusing the emitted electron beam at one of a plurality of focal points on the anode target;    impacting the anode target with the emitted electron beam to form an emitted x-ray radiation beam;    collimating the emitted x-ray radiation beam;    passing the collimated x-ray radiation beam through an object;    detecting the x-ray radiation beam -with the x-ray detecting unit; and    processing the detected x-ray radiation image into a tomographic image.    
     
     
         23 . The method of  claim 22  further comprising repeating the steps of applying, focusing, impacting, collimating, passing, detecting, and processing to produce multiple x-ray radiation images without rotating the object positioned on the object stage, wherein the electric field is applied to at least a second individually programmable electron emitting unit during the repeated step of applying.  
     
     
         24 . The method of  claim 22  further comprising repeating the steps of applying, focusing, impacting, collimating, passing, detecting, and processing to produce multiple x-ray radiation images without rotating the object positioned on the object stage, wherein the emitted electron beam is focused on a second of the plurality of focal points on the anode target when the step of focusing is repeated.  
     
     
         25 . The method of  claim 22 , wherein the x-ray source further includes a gate electrode located between the cathode and the anode target and the electrical field is applied such that the gate electrode is at a positive potential with respect to the individually programmable electron emitting unit and a field strength of the electrical field is from 0.1 Volt/micron to 100 volt/micron.  
     
     
         26 . The method of  claim 25 , wherein the field strength is from 0.5 Volt/micron to 20 Volt/micron.  
     
     
         27 . The method of  claim 22 , wherein the electron beam emitted from each electron emitting unit is focused at a different one of the plurality of focal spots within a line on the anode target.  
     
     
         28 . The method of  claim 27 , wherein the collimator generates a fan beam geometry of x-ray radiation.  
     
     
         29 . The method of  claim 22 , wherein the step of collimating produces a fan beam geometry.  
     
     
         30 . A computed tomography device for small animal imaging, comprising: 
 a field emission x-ray source, wherein the x-ray source can generate a plurality of x-ray beams from a plurality of focal spots which are arranged in a two-dimensional matrix on a surface of an x-ray anode, an area multi-pixel digital x-ray detector, and an object stage placed between the x-ray source and the detector.    
     
     
         31 . The device of  claim 30 , wherein the x-ray source comprises: a cathode with a plurality of individually programmable electron emitting units that each emit an electron beam upon an application of an electric field, wherein the emitting units are positioned in a two-dimensional matrix on the cathode; an electron focusing device; and an anode target that emits an x-ray beam from a focal spot upon impact by an emitted electron beam.