An Advance in X-ray Film Processing

The diagnostic value of any X-ray film is dependent on its quality and is critically so in cases where the progress of some clinical condition is assessed by comparison of films taken at different times. Exact repetition of the exposure and carefully controlled processing are essential if such films are to be comparable in density and contrast. Under optimum conditions the processing techniques used in conventional darkrooms can give results of a uniformly high quality. In a busy department it is difficult to maintain such a standard. An automatic processing unit (Hills, 1951) reduces human errors and ensures that all films are developed in accordance with time-temperature technique. The benefits deriving from the automatic action of such apparatus are impaired if the developing solution is subject to variation. A method of obtaining a sufficiently constant level of activity for an almost unlimited period of time has been devised and the details are described in this paper.The object is to ensure that films of the same patient taken under identical exposure conditions will show no diagnostically significant variations if they are processed at different times in the life of the developer. For this purpose developer activity can be assessed adequately in terms of the blackening of a sensitometric strip. It is assumed that developer activity defined in this way will remain constant provided that the developer constituents are kept within a suitable range of variation about their original concentrations.