This document describes the performance metrics associated with DUAL-ENERGY IMAGING capable DIGITAL X-RAY IMAGING DEVICES meant for medical applications and specifies the methods for their determination. These metrics can be used to analyze TISSUE-SUBTRACTED IMAGES and to evaluate dose performance, noise characteristics, and tissue-subtraction efficacy of DIGITAL X-RAY IMAGING DEVICES. The described methods indicate the procedures to obtain MULTI-SPECTRAL PRIMARY DATA and to compute their derived TISSUE-SUBTRACTED IMAGES. The intended users of this part of IEC 62220 are MANUFACTURERS and well-equipped test laboratories. This document is restricted to DIGITAL X-RAY IMAGING DEVICES that are used for single or multiple exposure dual-Energy radiographic imaging based on, for example, CR systems, direct and indirect flat panel-detector based systems. This document excludes and is not applicable to: DIGITAL X-RAY IMAGING DEVICES intended to be used in mammography or in dental RADIOGRAPHY; slot scanning DIGITAL X-RAY IMAGING DEVICES; COMPUTED TOMOGRAPHY or CONE-BEAM COMPUTED TOMOGRAPHY; photon-energy discriminating devices such as photon counting X-RAY IMAGING DEVICES; devices for dynamic imaging (where series of images are acquired, as in fluoroscopy or cardiac imaging). DIGITAL X-RAY IMAGING DEVICES intended to be used with RADIOTHERAPY beams