Method and apparatus for adaptive x-ray equalization

Abstract

The present invention pertains to an apparatus and method for adaptive exposure in imaging systems. An x-ray source for producing x-ray radiation and an x-ray detector for measuring amount of x-ray radiation passing through the human patient and striking the detector can be used. A tomographic image of the human patient or a tomosynthetic image of the human patient can be generated. Region of interest filtering and equalization filtering can be utilized. Filtering can be accomplished with a mechanical shield or shutter or with electronic control of the x-ray source.

What is claimed is: 
     
         1 . An x-ray imaging system for imaging a human patient comprising:
 an x-ray source for producing x-ray radiation;   an x-ray detector for measuring amount of said x-ray radiation passing through said human patient and striking said detector; and   a dwell controller coupled to said x-ray source configured to control total dwell time of said x-radiation for a focal spot.   
     
     
         2 . The x-ray imaging system of  claim 1  wherein said dwell controller adjusts a number of non-zero duration dwells. 
     
     
         3 . The x-ray imaging system of  claim 1  wherein said dwell controller adjusts a number of repetitions of fixed-length exposures. 
     
     
         4 . The x-ray imaging system of  claim 1  wherein said dwell controller adjusts a dwell exposure time of each exposure. 
     
     
         5 . The x-ray imaging system of  claim 1  further comprising:
 an x-ray tube controller configured to adjust a tube voltage of said x-ray source. 
 
     
     
         6 . The x-ray imaging system of  claim 1  further comprising:
 an x-ray tube controller configured to adjust a beam current of said x-ray source. 
 
     
     
         7 . The x-ray imaging system of  claim 1  further comprising:
 a dwell change limiter configured to limit changes in number of dwells between subsequent focal spots. 
 
     
     
         8 . The x-ray imaging system of  claim 1  further comprising:
 an image equalization filter configured to utilize a preliminary image reconstruction during a subset of said total dwell time for said focal spot. 
 
     
     
         9 . The x-ray imaging system of  claim 1  further comprising:
 a dynamic range limiter configured to compress dynamic range of said x-ray radiation striking said detector. 
 
     
     
         10 . A method for producing an x-ray image of a human patient comprising:
 producing a beam of x-ray radiation from an x-ray source;   controlling total dwell time of said beam of x-ray radiation for a focal spot of said x-ray source;   measuring amount of said x-ray radiation passing through said human patient and striking a detector.   
     
     
         11 . The method of  claim 10  further comprising:
 performing image equalization from a preliminary interim reconstruction during a subset of said total dwell time for said focal spot. 
 
     
     
         12 . The method of  claim 10  further comprising:
 limiting change in number of dwells between a plurality of subsequent focal spots. 
 
     
     
         13 . The method of  claim 10  further comprising:
 performing image equalization from a previously acquired image frame. 
 
     
     
         14 . The method of  claim 10  further comprising:
 adjusting number of non-zero duration dwells. 
 
     
     
         15 . The method of  claim 10  further comprising:
 modifying an x-ray photon threshold to reduce change in a number of dwells between a plurality of subsequent focal spots. 
 
     
     
         16 . The method of  claim 10  further comprising:
 adjusting a tube voltage of said x-ray source. 
 
     
     
         17 . The method of  claim 10  further comprising:
 adjusting a beam current of said x-ray source. 
 
     
     
         18 . The method of  claim 10  further comprising:
 adjusting a dwell exposure time of each exposure. 
 
     
     
         19 . The method of  claim 10  further comprising:
 compressing dynamic range by limiting x-ray exposure in a partial image. 
 
     
     
         20 . The method of  claim 10  further comprising:
 limiting exposure in a partial image to a desired exposure threshold.