Medical image quality is ultimately gauged by the image’s contribution to an accurate diagnosis. Meaningful comparison of the key elements of diagnostic image quality requires that consistent methods be used to measure them. A NEMA subcommittee is drafting standards to evaluate an x-ray image intensifier (XRII) system—the XRII; lenses linking the XRII output to a camera; video, photofluorographic, and cine cameras; and a video monitor. Image quality parameters include contrast ratio, detective quantum efficiency (DQE), fixed pattern noise, gain, image signal uniformity, limiting spatial resolution, modulation transfer function (MTF), noise power spectrum, radial distortion, signal-to-noise ratio, and visible entrance field size. An IEC Working Group is dealing with the XRII itself and first addressed MTF and DQE. This paper reviews the work of these two groups developing standards for measuring the image quality parameters of medical XRIIs and systems.