Control of Medical X-Ray Film Processing by Light Sensitometry: the Influence of Reciprocity Law Failure and Intermittency Effect

Abstract

In medical X-ray imaging, film processing is one of the main parameters determining image quality, An important method for controlling film processing is sensitometry. Light sensitometers in which electroluminescent foils serve as light sources are widely used for this purpose. These sensitometers emit light pulse trains of different pulse repetition frequency and different total length, which may cause intermittency effects or give rise to reciprocity law failure. These effects may increase the uncertainty of this sensitometric method to an extent which is no longer tolerable for the intended purpose. The effects were measured for a great number of films of five leading film manufacturers. The results are presented and steps proposed which should be taken to make this kind of sensitometry more reliable.