Sensitivity variation of X-ray photographic films
WM. H. GEORGE · Proceedings of the Physical Society · 1937
An experimental study of the variation of sensitivity from place to place on an X-ray photographic film has been made, so that fluctuations of blackening, due to intensity-variation of the incident radiation, can be distinguished from those due to film sensitivity. Double-film exposures are made with the two sensitive surfaces in contact, and the processing is carried out in a simple mechanical apparatus so that the films move always with accelerated motion relative to the liquids. It is found that if X-ray photographic films are used with the technique described and are blackened until they transmit about half the incident light, then the variations of sensitivity are such as may lead to maximum deviations in the individual measurements of X-ray intensity of the order ±6 per cent in single-film exposures or of ±3 per cent in double-film exposures. The mean deviations are of the order ±2 per cent.