Factors involved in the high radiographic sensitivity of E-speed films.

A microscopic and densitometric analysis of the high speed and fog density of E-speed film was conducted. The grain sizes of silver bromide (AgBr) and developed silver metals were measured, and the optical densities of the film were compared by means of various development procedures. Silver bromide grains were found to be large and accounted for the high speed of the film. Development caused chains of silver metal clusters to form, which contributed to the larger fog density as well as the higher speed.