1. Film processing 2

2. Processing cycle
Dev.
Rinse
Fix
Wash
Dryer

3. Developing
Dev

4. Rinsing (stop bath)
Rinse

5. Rinsing in manual processing
Immediately after development the film is dipped in the water in order to:
Stop development
To wash the developer from the surface of the film – (reduces developer carry over to fixer)

6. Rinsing in Automatic processing?
No rinsing stage
The developer is removed from the film surface by passing it through the special type of rollers called “squeegee rollers”
Alkaline Developer is neutralized by the acid in the fixer

7. Fixing
Film
Film
Fixer

8. Functions of fixing To stop any further development
Clears the image (making the background transparent to light)
Makes the image permanent (fixed)
(no more sensitive to light)
by Removing the undeveloped silver bromide crystals from the emulsion
Hardens the emulsion

9. Fixer constituents Solvent Fixing agent Acid Hardener Buffer
Preservative
Anti-sludging agent

10. Functions of fixer constituents
Solvent
(water)
Carrying medium for the active ingredients
Controls the acidity by diluting
Fixing agent
(Sodium Thiosulphate /Ammonium Thiosulphate
Combines with insoluble AgBr to form soluble compounds (Ammonium Argento-Thiosulphate & NH4Br

11. Acid
(Acetic acid – pH 4.0 – 4.5)
To stop development
To provide suitable working environment for hardening agents
Hardener
(Aluminium chloride & aluminium sulphate)
Hardens the emulsion to limit water absorption, to reduce drying time, to minimize physical damage

12. Buffer
(Sodium acetate & acetic acid)
Controls the pH in a precise range in order to:
i. Prevent sulphurization
ii. Neutralize the developer
iii. Optimum hardening
Preservative
(Sodium sulphite)
Retards the decomposition of thiosulphate and delays the onset of sulphurization
Anti-sludging agent (Boric acid)
Reduces the formation of sludge of insoluble aluminium compounds by the aluminium salts used as the hardner

13. Factors affecting Fixation
The quality and quantity of fixation depends on the:
Constitution and activity of fixing solution
Fixer temperature
Fixing time

14. Constitution & activity of fixing solution
At a given temperature the activity of fixer solution depends on:
Fixing agent
Concentration of fixing agent
Amount of hardener present
The amount of soluble silver compounds and soluble halides present pH
pH does not affect clearing action directly, but reduces the function of hardeners if becomes high

15. Fixer temperature
The activity of fixing agents increases with temperature.
But high temperatures cause emulsion swelling and becomes susceptible to damage.
However precise control of temperature is not necessary

16. Fixing time
The fixing time should be long enough to complete the fixing process.
The required time for complete fixation depends on the
i. activity
i. type of film emulsion
iii. Agitation of fixer solution
Manual processing may be as long as 5 minutes
Automatic processing :- 15 sec in a 90 sec cycle.

17. Replenishment of Fixer
Replenishment of fixer is necessary to
Maintain the activity
Maintain the volume
The rate of replenishment depends on
Area/number of films processed
Type of emulsion/film
Type of image

18. Replenishment of chemicals
Automatic processing
Added automatically
by the replenishment
pumps at a given
rate for each film
processed
Manual processing
Suitable quantity is
added manually at
regular intervals

19. Washing
Removes the fixing solution contaminated with silver complexes and ammonium halides from the film surface and from film emulsion
Running water is used to maintain a concentration gradient and to improve the diffusion rate of chemicals from the emulsion to water
If not washed properly the emulsion will gradually acquire a yellow-brown sulphur stain during storage

20. Factors affecting washing efficiency
Type of film emulsion
Condition of fixing solution
Condition of water
Agitation of water
Temperature of water
Washing time
Thiosulphate level of < 3 microgram/square cm is recomended
100% efficiency is not practicable. The washing time is selected so that the film will not be stained within 10 years of storage

21. Drying
Removes all of the surface water and most of the water retained in the emulsion
Manual processing:- Keep the film in a drying cabinet in which hot air is circulated. Takes about minutes
Automatic Processing:- Surface water is removed by squeegee rollers ; evaporation removes the emulsion water.
25 sec in a 90 sec cycle

22. Factors affecting drying time & efficiency
The wetness of the emulsion; governed by:
i. hardness of the emulsion
ii. emulsion thickness
The drying conditions; governed by:
i. Air humidity
ii. Air Temperature
iii. Air circulation – rate of change

23. Summary
If a film is not processed properly the whole effort made in the x-ray room or in the ward to obtain a good radiograph will be lost
It is essential to pay similar attention to film processing as you pay at the x-ray room or in the ward when taking the x-ray