Method and system of x-ray data calibration

Abstract

A process of data calibration and correction is disclosed that utilizes feedback from a temperature sensor of an x-ray detector to isolate or otherwise select an appropriate calibration or correction map that is specific to the temperature of the x-ray detector during data acquisition. The method is also designed to take into account changes in power transients of an x-ray detector between the acquisition of imaging data and the acquisition of offset data. The method is particularly applicable in optimally selecting and applying gain correction, conversion factor, bad pixel, and offset calibrations.

1 - 19 . (canceled) 
     
     
         20 . An x-ray detector comprising:
 a scintillator configured to emit light in response to reception of radiation;   a detector element array configured to output radiographic data and having a plurality of detector elements, each detector element configured to detect light from the scintillator and provide an electrical signal that may be processed for image reconstruction;   a temperature sensor to provide feedback as to temperature of the detector element array;   a processor programmed to apply a bad pixel correction to at least one presumed bad pixel and a conversion factor correction to the radiographic data output by the detector element array, specific to the temperature of the detector element array during radiographic data acquisition.   
     
     
         21 . The x-ray detector of  claim 20  wherein the processor is further programmed to compare the temperature of the x-ray detector to a database of gain correction maps and select a gain correction map to be applied to the radiographic data output of the detector element array based on the comparison. 
     
     
         22 . The x-ray detector of  claim 21  wherein the processor is further programmed to select a gain correction map specific to the temperature of the detector and if the database of gain correction maps does not contain a gain correction map specific to the temperature of the x-ray detector then determine an appropriate gain correction map by interpolating between two gain correction maps stored in the database of gain correction maps. 
     
     
         23 . The x-ray detector of  claim 20  wherein the processor is further programmed to compare the temperature of the x-ray detector to a database of bad pixel correction maps and identify those elements of the detector element array presumed to be bad based on the temperature of the x-ray detector. 
     
     
         24 . The x-ray detector of  claim 23  wherein the processor is further programmed to ignore the electrical signals of those elements of the detector element array presumed to be bad during image reconstruction. 
     
     
         25 . The x-ray detector of  claim 20  wherein the processor is further programmed to compare the temperature of the x-ray detector to a conversion factor curve and determine a conversion factor to be applied to the radiographic data output based on the temperature of the x-ray detector. 
     
     
         26 . The x-ray detector of  claim 20  wherein the processor is further programmed to compare the temperature of the x-ray detector to a default temperature range and if the temperature falls within the default temperature range then apply a default calibration to the radiographic imaging data. 
     
     
         27 . A method of x-ray detector calibration comprising the steps of:
 determining a temperature of an x-ray detector during data acquisition from a subject to be imaged;   selecting a bad pixel map, specific to the temperature of the x-ray detector, from a number of stored bad pixel maps;   generating a conversion factor curve that is a function of temperature of the x-ray detector;   applying the selected bad pixel map and a conversion factor to data acquired by the x-ray detector to reduce artifacts in an image reconstructed from the data acquired by the x-ray detector; and   displaying the image to a user.   
     
     
         28 . The method of  claim 27  wherein the bad pixel map includes the location of pixels that are presumed to be corrupted. 
     
     
         29 . The method of  claim 27  further comprising the step of selecting a conversion factor from the conversion factor curve. 
     
     
         30 . The method of  claim 27  further comprising the step of selecting a gain correction map specific to a temperature not equal to the temperature of the x-ray detector from a number of stored gain correction maps and applying the gain correction map to the data acquired by the x-ray detector. 
     
     
         31 . The method of  claim 27  wherein the step of generating a conversion factor curve is further defined as generating a conversion factor map. 
     
     
         32 . The method of  claim 27  further comprising the step of selecting a gain correction map specific to the temperature of the x-ray detector from a number of stored gain correction maps and applying the gain correction map to the data acquired by the x-ray detector. 
     
     
         33 . The method of  claim 32  wherein the step of selecting the gain correction map further comprises interpolating between two gain correction maps if the temperature of the x-ray detector does not directly correspond to a stored gain correction map. 
     
     
         34 . The method of  claim 33  wherein the interpolating comprises carrying out a bicubic interpolation. 
     
     
         35 . A method of x-ray data correction comprising the steps of:
 acquiring radiographic data from a subject to be imaged;   determining a temperature of an x-ray detector used to acquire the radiographic data;   comparing the temperature of the x-ray detector to a series of temperature-dependent calibration maps;   identifying those detector elements of the x-ray detector that are presumed corrupted at the temperature of the x-ray detector during data acquisition;   ignoring data acquired by those detector elements presumed corrupted during image reconstruction; and   at least temporarily storing in memory data acquired by those detector elements not presumed corrupted during image reconstruction.   
     
     
         36 . The method of  claim 35  wherein the series of temperature-dependant calibration maps are a series of gain calibration maps. 
     
     
         37 . The method of  claim 36  further comprising the step of selecting a gain calibration map specific to the temperature of the x-ray detector from the series of gain calibration maps. 
     
     
         38 . A method of x-ray data correction comprising the steps of:
 acquiring radiographic data from a subject to be imaged;   determining a temperature of an x-ray detector used to acquire the radiographic data;   comparing the temperature of the x-ray detector to a database of temperature-dependent gain maps;   selecting at least two temperature-dependent gain maps from the comparison, wherein the at least two temperature-dependent gain maps correspond to two temperatures of the database closest to the temperature of the x-ray detector;   interpolating between the at least two temperature-dependent gain maps to obtain an interpolated temperature-dependent gain map at the temperature of the x-ray detector;   applying the interpolated temperature-dependent gain map to the radiographic data acquired to reduce artifacts in a reconstructed image of the subject; and   displaying the image to a user.   
     
     
         39 . The method of  claim 38  further comprising the step of accessing a bad pixel map from a series of bad pixel map, wherein the bad pixel map contains the location of pixels that are presumed to be corrupt and is specific to the temperature of the x-ray detector.