| The performance of a general x-ray photoconductor is analyzed by determining the charge collection enabled through the application of a constant applied field across a sandwiched x-ray photoconductor, considering the electron and hole trapping individually. In particular, employing the Hecht relation, an analytical expression for the collected charge is obtained. Then, the x-ray sensitivity of the x-ray photoconductor, defined as the collected charge obtained per unit area, per unit exposure of radiation, is determined. Using these basic performance metrics, namely the collected charge and the x-ray sensitivity, a performance comparison between a number of candidate x-ray photoconductors being considered for use in direct conversion flat panel digital x-ray image detectors, is presented. The candidate x-ray photoconductors considered in this analysis are amorphous selenium, mercuric iodide, lead iodide, cadmium zinc telluride, and thallium bromide. From this analysis, it was shown that while amorphous selenium is the most widely used x-ray photoconductor at present for applications in direct conversion flat panel digital x-ray image detectors, the other candidate x-ray photoconductors show considerable promise. |
