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UBC Theses and Dissertations

A performance analysis of a direct-conversion digital X-ray imager Salhotra, Amith Kumar


In this thesis, the performance of direct-conversion digital X-ray imagers is evaluated using an elementary model that draws upon the material properties and the dimensions of the X-ray photoconductor employed within such imagers. Five possible X-ray photoconductors are considered in this analysis, namely amorphous selenium, cadmium zinc telluride, mercury iodide, lead iodide, and thallium bromide. The collected charge per unit area is the performance metric considered in this analysis. The collected charge per unit area related to the motion of the electrons and holes individually, and due the motion of both types of charge carriers, is evaluated. The fractional contributions to the collected charge per unit area is also evaluated. The application of both positive and negative biases to the radiation receiving terminals is considered. It is found that the collected charge per unit area, for the case of both positive and negative biases, is higher for the case of cadmium zinc telluride when compared with the other X-ray photoconductors considered in this analysis. This suggests that cadmium zinc telluride may be a better material to employ as the X-ray photoconductor within direct-conversion digital X-ray imagers.

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