Method and apparatus for performing multi-energy (including dual energy) computed tomography (ct) imaging

Abstract

An improved dual energy CT imaging system for providing improved imaging and improved material identification.

1 .- 21 . (canceled) 
     
     
         22 . A system for providing a first energy measurement associated with a first X-ray energy range produced by a polychromatic X-ray tube, and a second energy measurement associated with a second X-ray energy range produced by the same polychromatic X-ray tube, wherein the second X-ray energy range is different from the first X-ray energy range, the system comprising:
 a filtered detector for detecting X-rays produced by the polychromatic X-ray tube across the first X-ray energy range and providing an output, wherein the output of the filtered detector comprises the first energy measurement;   an unfiltered detector for detecting X-rays produced by the polychromatic X-ray tube across the full X-ray energy range of the polychromatic X-ray tube and providing an output; and   a processor for determining the second energy measurement, wherein the second energy measurement is the difference between the output of the unfiltered detector and the output of the filtered detector.   
     
     
         23 . A system according to  claim 22  wherein the first X-ray energy range comprises higher energy photons and the second X-ray energy range comprises lower energy photons. 
     
     
         24 . A system according to  claim 23  wherein the filtered detector comprises a detector and a filter interposed between the polychromatic X-ray tube and the detector, and further wherein the filter is configured to block lower energy photons. 
     
     
         25 . A system according to  claim 22  further comprising a polychromatic X-ray tube. 
     
     
         26 . A system according to  claim 22  wherein an object is disposed between (i) the polychromatic X-ray tube, and (ii) the filtered detector and the unfiltered detector. 
     
     
         27 . A method for providing a first energy measurement associated with a first X-ray energy range produced by a polychromatic X-ray tube, and a second energy measurement associated with a second X-ray energy range produced by the same polychromatic X-ray tube, wherein the second X-ray energy range is different from the first X-ray energy range, the method comprising:
 providing a system for providing a first energy measurement associated with a first X-ray energy range produced by a polychromatic X-ray tube, and a second energy measurement associated with a second X-ray energy range produced by the same polychromatic X-ray tube, wherein the second X-ray energy range is different from the first X-ray energy range:
 a filtered detector for detecting X-rays produced by the polychromatic X-ray tube across the first X-ray energy range and providing an output, wherein the output of the filtered detector comprises the first energy measurement; 
 an unfiltered detector for detecting X-rays produced by the polychromatic X-ray tube across the full X-ray energy range of the polychromatic X-ray tube and providing an output; and 
 a processor for determining the second energy measurement, wherein the second energy measurement is the difference between the output of the unfiltered detector and the output of the filtered detector; 
   using the polychromatic X-ray tube to cause the full X-ray energy range of the polychromatic X-ray tube to be received by the filtered detector and the unfiltered detector; and   using the filtered detector to determine the first energy measurement, and using the processor to determine the second energy measurement.   
     
     
         28 . A method according to  claim 27  wherein the first X-ray energy range comprises higher energy photons and the second X-ray energy range comprises lower energy photons. 
     
     
         29 . A method according to  claim 28  wherein the filtered detector comprises a detector and a filter interposed between the polychromatic X-ray tube and the detector, and further wherein the filter is configured to block lower energy photons. 
     
     
         30 . A method according to  claim 27  wherein the system further comprises a polychromatic X-ray tube. 
     
     
         31 . A method according to  claim 27  wherein an object is disposed between (i) the polychromatic X-ray tube, and (ii) the filtered detector and the unfiltered detector.