While the question of standardization has been considered in X-ray therapy for a considerable time, in X-ray diagnosis it has, as yet, only been provisionally considered. It is questionable whether absolute standardization of physical, chemical and photographic conditions, relating to X-ray photographic images, is necessary or whether it is even possible. The necessity for specifying standards of ... [Show full abstract] production of films is obvious. The question of standardisation of the accessory apparatus, the record cards of patients, the clinical findings and the directions of projection by which the film is taken, has been dealt with by Holtzknecht. The standardisation of X-ray projectory symbols has also been dealt with by Robinson.
These aspects will not be considered in the present paper, which deals rather with the possibility of attempting to find units for X-ray exposure, so that the several aspects of the physical, chemical, and photo-chemical conditions can be represented graphically by a curve of density of the X-ray film or plate. For this purpose test objects are used which are photographed during the optimum exposures of the actual organ, or particular part of the body. It is to be noted that, by this means, we are guaranteed that in other X-ray laboratories the same results will be obtained, given the same physical and chemical conditions of photography.