High energy, real time capable, direct radiation conversion X-ray imaging system for Cd-Te and Cd-Zn-Te based cameras

Abstract

A calibrated real-time, high energy X-ray imaging system is disclosed which incorporates a direct radiation conversion, X-ray imaging camera and a high speed image processing module. The high energy imaging camera utilizes a Cd—Te or a Cd—Zn—Te direct conversion detector substrate. The image processor includes a software driven calibration module that uses an algorithm to analyze time dependent raw digital pixel data to provide a time related series of correction factors for each pixel in an image frame. Additionally, the image processor includes a high speed image frame processing module capable of generating image frames at frame readout rates of greater than ten frames per second to over 100 frames per second. The image processor can provide normalized image frames in real-time or can accumulate static frame data for substantially very long periods of time without the typical concomitant degradation of the signal-to-noise ratio.

1 . A high energy, direct radiation conversion X-ray imaging system comprising: 
 a high energy x-ray imaging camera, the camera having a high pixel density, direct conversion radiation detector substrate, with pixels of detector substrate, an electrical connection to a corresponding pixel circuit on an ASIC readout substrate, the detector substrate providing for directly converting impinging high energy x-ray gamma ray radiation to an electrical charge and communicating the electrical charge via the electrical connection between the pixel to its corresponding pixel circuit on the ASIC readout substrate as an electric charge signal, and the pixel circuit providing for processing the electric charge signal from each pixel;    a high speed image frame processing module in electronic communication with the ASIC readout substrate of the imaging camera, the frame processing module capable of receiving digitized pixel signals derived from an output from each pixel circuit of the readout substrate and using the pixel signals to generate an image frame at a frame readout rate of greater than ten image frames per second;    a calibration module selectably in digital communication with the frame processor module, the module when selected being driven by a software process including a calibration routine which calibration routine writes pixel correction data specific to each pixel in an image frame to a lookup table;    a lookup table, the lookup table writeable by the calibration module with pixel specific correction data, and readable by a normalization module; and    a normalization module selectably in communication with the frame processor module and with the lookup table, the normalization module receiving real time image frame data/record from the frame processor module and pixel specific correction data from the lookup table, and providing normalized image data via a display image output for use in a display module to present an X-ray image of the high energy, direct detection X-ray imaging system.    
     
     
         2 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the normalization module provides normalized image data via a display image output for use in a display module to present a dynamic X-ray image from the high energy, real time, direct detection X-ray imaging system.  
     
     
         3 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the normalization module provides normalized image data via a display image output for use in a display module to present a static X-ray image from the high energy, real time, direct detection X-ray imaging system.  
     
     
         4 . The high energy, direct radiation conversion X-ray imaging system of  claim 3 , wherein the normalization module accumulates normalized image data over a period of time to provide a high precision display image output for use in a display module to present a static X-ray image.  
     
     
         5 . The high energy, direct radiation conversion X-ray imaging system of  claim 2 , wherein the normalization module accumulates normalized image data over a period of time of at least one hundredth of a second to ten seconds for providing a high precision display image output for each of the accumulation periods, for use in a display module to present a dynamic X-ray image.  
     
     
         6 . The high energy, direct radiation conversion X-ray imaging system of  claim 4 , wherein the normalization module accumulates normalized image data over a period of time of at least one hundredth of a second to 300 seconds.  
     
     
         7 . The high energy, direct radiation conversion X-ray imaging system of  claim 4 , wherein the normalization module accumulates normalized image data over a period of time of at least five minutes.  
     
     
         8 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the camera module comprises an imaging device having a Cadmium Telluride composition based radiation detector substrate in communication with an ASIC readout substrate.  
     
     
         9 . The high energy, direct radiation conversion X-ray imaging system of  claim 8 , wherein the camera module comprises an imaging device having a radiation detector substrate consisting of a composition selected from the group consisting of: Cadmium-Telluride and Cadmium-Zinc-Telluride.  
     
     
         10 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the camera module includes a detector substrate bias switch circuit.  
     
     
         11 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the high speed image frame processing module is capable of receiving digitized pixel signals derived from the output from each pixel circuit of the readout substrate and using the digitized pixel signals to generate an image frame at a frame readout rate of greater than 25 image frames per second.  
     
     
         12 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the high speed image frame processing module is capable of receiving digitized pixel signals derived from the output from each pixel circuit of the readout substrate and using the digitized pixel signals to generate an image frame at a frame readout rate of greater than 50 image frames per second.  
     
     
         13 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the software process includes a calibration routine which analyzes each digitized pixel value over at least some of the collected calibration frames being analyzed in accordance with a pixel value correction algorithm to provide and write pixel value correction data specific to each pixel in an image frame to the lookup table  
     
     
         14 . The high energy, direct radiation conversion X-ray imaging system of  claim 1 , wherein the software driving the calibration module includes a pixel non-linear performance compensation routine providing error correction for each pixel as a function of time.  
     
     
         15 . The software driving the calibration module of  claim 14 , wherein the pixel non-linear performance compensation routine includes an asymmetric linear polynomic calculation to determine correction coefficients to provide error correction for each pixel as a function of time.