A device that consists of a uniform density or a two or three-dimensional (3-D) pattern of objects, materials or openings of varying dimensions. It includes phantoms that come in both fixed and variable configurations. It is a quality assurance (QA) device used in both subjective and quantitative evaluations of various calibration and performance characteristics of dedicated digital or conventional diagnostic x-ray mammography systems or general-purpose x-ray systems adaptable for mammography applications. It is also used in performance evaluations of associated image acquisition, display, and analysis computer hardware and software.