  We propose a new objective numerical figure of merit to aid in the evaluation
and comparison of tissue-selective images generated from dual-energy
radiography systems. A metric is developed through identification of the
requirements of a successful objective metric and analyzed in a variety of
scenarios. The proposed Dual-Energy Subtraction Efficiency (DSE) metric
adequately describes a multitude of image properties for all simulated image
scenarios, indicating its ability to accurately and objectively describe image
quality. The DSE and its measurement method described can become a tool to
characterize dual-energy radiographic image quality objectively and
quantitatively, allowing for improved system comparison, development, and
optimization.
