To date, the lack of adequate electronic display devices has been the primary factor limiting the use of digital radiographic images. Flat panel display technology using field emissive cathodes in microvacuum cells has emerged as a potential solution. However, the performance characteristics of low-voltage cathodoluminescence in the range below 1 kV is not well understood. In this paper, we discuss issues concerning the prediction of phosphor efficiency, and describe the processes of light generation and transport which influence the performance of phosphor screens. ©2004 Copyright SPIE - The International Society for Optical Engineering.