film under step number six. Therefore, upon development, the quantity of silver
deposited in area number six is less than that under number one. A deposit of silver
that is proportional to the exposure represents each step.
b. Upon development (D), the latent image silver bromide is reduced to metallic
silver and the unexposed silver bromide (thin diagonal lines) is not affected. (Mixed with
the metallic silver deposits are some unexposed and undeveloped silver bromide
c. After the film has been fixed (E), all the unexposed and undeveloped silver
bromide is dissolved from the emulsion and the metallic silver remaining on the film
constitutes the radiographic image of the step wedge shown in (A).
d. When the radiograph (F) is later viewed on an x-ray illuminator, all the various
deposits representing the steps of the wedge are seen in their proper concentrations
and various degrees of translucency. To obtain an optimum density, full development is
Figure 3-1. Stages of exposure and development of x-ray film.