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Within a relatively short time photofluorography has been transformed from a crude experiment to an efficient diagnostic aid. It may be estimated that within the last six years some 20 million Americans have had x-ray examinations of the chest. The vast majority of these would not have had this service if they had had to depend on the conventional 14 by 17 inch celluloid film. The outlook for the future is that mass radiography will further expand and that a majority of the adult population will receive this service. The radiographic technics and sizes most commonly used are 35 mm. photofluorography, 4 by 10 inch stereophotofluorography, roentgenography on 14 by 17 inch paper and film negatives and, in recent months, 70 mm. photofluorography. Individual preferences for one or the other of these technics are based, as far as can be determined, on considerations of economy, ease of operation, individual likes
C. C. Birkelo (Sat,) studied this question.