Film processing 2

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

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

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

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

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

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

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 10-15 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