The advent of larger image-intensifying tubes with higher brightness gain has solved many of the problems of radiation dose and field size in cineradiography. Limited image detail remains as the most critical obstacle to be overcome if this method is to have a wider range of diagnostic usefulness. It is the purpose of this presentation to evaluate the relative merits of film size alone as a determining factor in the quality of a cine-image. Obviously, the film can record an image no better in detail than the quality and adjustment of the image intensifier and lens system will produce. It is obvious, furthermore, that the larger of two films with the same emulsion characteristics will present a greater number of photosensitive grains to accept the image; hence it can potentially yield more detail. Because of the very limited resolving power of present-day image tubes, the question of whether there is any critical gain in diagnostic yield through the use of 35-mm. film is pertinent. Factors Affecting the Ev...