Answers to revision questions
Chapter 11: Processing the Radiographic Film
1. Give the four main stages of processing in order
Developer
Fixer
Wash
Dry
2. Describe what happens to the exposed silver halide crystals during
development.
During development the exposed silver halide grains are reduced to metallic
silver while the grains in the emulsion unaffected by the exposure do not
change.
Fixer will clear the image by removing silver halide crystals from the emulsion.
The exposed crystals of silver halide have been converted to metallic silver
but the unexposed crystals remain.
3. What factors will affect the efficiency of the washing process?
The efficiency of the washing process will be affected by the amount of
contaminant in the emulsion, the condition of the fixer, the flow and amount of
water movement, the temperature of the water and the time taken to wash the
film.
4. Name the two compounds in developing solution
Developing Agents
Preservative
Accelerator
Restrainer
Sequestering Agents
Solvent
Other Additions
5. Why is water used as the solvent in fixer solution?
Water has a neutral pH and is cheap as well as readily available. This will
dissolve into the emulsion carrying with it the dissolved fixer chemicals.
6. How does the film transport system of an automatic processor work?
The film is initially taken into the processor through a film feed system.. The
film is carried through the tanks through a series of rollers. These will press
the solution onto the surface of the film and will also squeegee excess
chemistry off the surface of the film as it leaves the tanks. To alter the
amount of time the film spends in each tank the depth of the tank is altered,
rather than having a complicated gear system. The transportation may either
be vertically through a series of deep tanks or horizontally through a series of
shallow trays.
7. Give two uses for water in an automatic processor
Water bath to help maintain temperature of developer and fixer
Solvent in developer and fixer
Wash water for the final stage of fixing process
8. Describe the daily care needed to maintain an automatic processor
The tanks and rollers must be cleaned regularly (once a week) to stop build of
the residual chemicals that may impair the function of the processor. The build
up of residual chemicals will speed up the deterioration of the remaining
chemicals, may cause scratches to the film and may cause the film to override
the rollers.
The temperature needs checking daily, as do the position of the rollers and
lid. The water needs to be emptied daily and benefits from an anti-fungal
treatment overnight.
9. How does replenishment in an automatic processor work?
Each time a film is taken into a processor a small amount of chemical is
automatically removed and replaced with fresh chemicals. This extends the
life of the chemicals and the effectiveness of the chemicals
10. How does a safelight work?
A safelight is essential to prevent light affecting the film and causing fogging.
All radiographic film is sensitive to white light and so the light must be filtered.
Most radiographic film is sensitive to green or blue light and so selecting a
filter that will remove this light will result in reduced fogging of the film.