This document provides information on dark room and film processing techniques. It discusses the key components and functions of a dark room for handling radiographic films without light exposure. It also describes the various stages of film processing including development, fixing, washing and drying. Both manual and automatic processing techniques are covered, outlining the different steps, equipment, chemical solutions and factors involved in each method. Automatic processors provide controlled, consistent processing using chemical tanks and a transport system to move films through development, fixation, washing and drying cycles.

1. DARK ROOM
AND FILM
PROCESSING
TECHNIQUES
BY ROSHAN VALENTINE

2. Dark room
It is a facility where handling and processing of films can be carried out without
the hazard of producing fog by accidental exposure to light or x-rays.
It must exclude all outside light and provide “SAFE” artificial light

3. It should be in close proximity to the place where the work of radiographer is carried out.
It should serve as many imaging rooms as geographically possible.

4. Location
It should be centrally sited and served by
hatches(passboxes) from the adjacent imaging rooms.
Away from damp and hot areas
Power and water accessibility
Adjoining viewing area where processed films can be
checked or sorted out

5. Dark room
SIZE
Minimum floor area of 10m2
Ceiling height 2.5-3m
RADIATION PROTECTION
Coating the walls with barium plaster or increase the thickness
Lining the doors with LEAD ply-sheet
Shielding any gaps around the door

6. Dark Room
FLOORS
Durable and easy to maintain(Eg: Plastic tiles)
Non porous non slip flooring material
WALLS/CEILING
Light in color
Easy to wipe over and keep clean

7. Dark room
VENTILATION AND HEATING
Satisfactory working condition for staff
Good film handling and storage conditions
This can be ensured by
Relative humidity : 40-60%
Min of 10 air changes per hour
Room temperature 18-200C

8. DARKROOM ENTRANCE:
SINGLE DOOR

9. DARKROOM ENTRANCE:
DOUBLE DOOR

10. DARKROOM ENTRANCE:
MAZE

11. DARKROOM ENTRANCE: REVOLVING DOOR

12. DARK ROOM ILLUMINATION
2 modes of lighting :
Ordinary white lighting
Safe lighting

13. WHITE LIGHTING
It is necessary for
Inspection and maintenance of cassettes and screens
Cleaning of work surfaces and floors
Servicing of equipment
White light should be
Close to the ceiling to avoid shadows
Moderate in intensity (60W tungsten /30Wfluorescent)
Centrally placed

14. SAFELIGHTING
Need: Working in compete darkness all day long is not a pleasant condition to
work on.
White light cannot be used as it causes fogging of film.
Hence DIM COLORED LIGHTING sufficient enough to work at is used
BUT THERE IS NO TOTALLY SAFE “SAFE”LIGHTING

15. How does a safelight filter work
Its about choosing a filter which will transmit a color to which
the film is relatively unresponsive while stopping all light to
which the film is most sensitive.

16. WHY SAFELIGHTING IS NOT 100% SAFE
No Filter completely absorbs the undesirable wavelengths
All films have SOME sensitivity to all wavelengths
HOW TO MAKE IT MORE SAFER?
Reduce the film handling time and intensity of illumination
Recommended Standard : 25w lamp sited at a minimum of 1.2m from the film

17. CONSTRUCTION
Colored gelatin filter is sandwiched b/w plane glass
Fitted in a metal lantern box

18. SAFELIGHTING
Areas where safe light is required
Film loading / unloading areas.
Processor film feed-in points.
Path b/w above two.
At developer tank.

19. SAFELIGHTING
Type/prop
Direct
Indirect
Mixed
Construction
Filter forms the undersurface
Filter forms the upper surface
Filters on both its upper and lower surfaces
Working
Directs light towards the floor
Directs light towards the ceiling
Directs light towards both floor and ceiling
Function
For film loading and unloading areas
For general illumination of the darkroom
For both the purposes

20. SAFELIGHTING
Safelight handling time
Maximum time a film can be exposed to safelight during the procedure without
causing any appreciable degree of fogging.
Average time : 20-45secs
Faster films need shorter time

21. DARK ROOM
Equipment and arrangement
An automatic processor
Cassette hatches
Film storage hopper
Loading bench/cupboards

22. Film processing techniques

23. PROCESSING CYCLE
Washing

24. PROCESSING CYCLE
Stage 1: DEVELOPMENT
 The primary function of development is to convert the latent image into a
manifest or visible image
Secondary purposes of development.
 To amplify the amount of metallic silver
 To reduce the exposed silver halide crystal into metallic silver.

25. CONSTITUENTS OF
DEVELOPING
SOLUTION
Developing Agent
Accelerator
Restrainers
Preservative
Hardener
Solvent

26. DEVELOPING SOLUTION
DEVELOPING AGENT
Principal component is hydroquinone (produces black tones slowly).
Secondary constituent is phenidone or metol (produces shades of grey rapidly).
Advantage of PQ developer:
 adequate activity
 high selectivity
 super-additivity (oxidised phenidone is reduced by hydroquinone)

27. DEVELOPING SOLUTION
ACCELERATOR/ACTIVATOR/BUFFERING AGENT
Alkaline medium for the action of PQ-accelerates the developing process
KCO3 or KOH
Ideal range of pH: 9.8-11.4
RESTRAINER/Anti-foggant
It reduces converting unexposed AgX to Ag and thus prevent chemical fogging.
KBr, benzotriazole(used with PQ developer)

28. DEVELOPING SOLUTION
PRESERVATIVE
It reduces the oxidation of developing agents.
Eg: Potassium sulphite
HARDENER
It controls gelatin swelling to minimize risk of physical damage.
Eg:Glutaraldehyde

29. DEVELOPING SOLUTION
SEQUESTERING AGENT
Prevents the precipitation of insoluble mineral salts which occur in hard water
areas
EDTA containing compounds are used
SOLVENT
Carrying medium for dissolving the developer constituents
Softens the film emulsion gelatin
MC used : Tap water

30. FACTORS AFFECTING DEVELOPMENT
Temperature of the developing solution
Total time of the development
An adequate combination of both is important for complete development

31. TEMPERATURE FOR DEVELOPMENT
Optimum temperature is 20-22oC
Below 16oC, action of hydroquinone ceases
◦ Radiograph lacks contrast and density
◦ Can be compensated by increasing the developing time.
Above 24oC (too warm) emulsion softens.
◦ Chemical fog results

32. DEVELOPMENT TIME
Time interval which elapses between the entry of a specified part of a film into
the developing solution and its exit.
Short processing times reduce waiting times.

33. FACTORS DETERMINING DEVELOPMENT
TIME
Developer activity- Active developer achieves given image density more
rapidly.
Type of film emulsion- Thick emulsion film > thinner ones(non screen
type>screen type film)
Agitation- Proper agitation fasten the development process.

34. STAGE 2:FIXING
During development not all the silver halides are reduced. Only 40% get
reduced
The remaining silver halides greatly impairs the
usefulness and permanence of the developed
radiograph and hence have to be removed.

35. FIXATION
It has four major functions
Stop any further development
Makes the solution more acidic
Remove the unexposed AgX from the emulsion
Convert it to soluble compounds and remove it
Makes the image chemically stable and no longer photosensitive
Completes the process of hardening of emulsion
Minimizes water absorption and reduces drying time

36. FIXER SOLUTION
FIXING AGENT
The fixing agents by forming water soluble complexes
tightly binds the silver ions and removes them from
the solution.Eg: sodium thiosulphate(HYPO)
Silver bromide +sodium thiosulphate
Silver thiosulphate complex +Sodium bromide

37. FIXER SOULTION
ACIDIFIER
To stop the development process. Create an acidic pH environment for fixing
agent.
Eg-Acetic acid
PRESERVATIVE
 To protect the fixing agent from oxidation and to maintain its activity, - Sodium
Sulfite

38. HARDENER
To further harden the emulsion to make the resultant image permanent. Al salt
such as Al sulphate, Al chloride.
SOLVENT
The purpose is to dilute the chemicals in the fixer solution – so that the
chemicals can function at their desired level of activity. Water

39. STAGE 3 : WASHING
Purpose of washing is to remove fixing solution from the surface of the film.
If the film is not properly washed, it will show a brown staining caused by
thiosulfate (fixing agent that remains in the emulsions).
The process by which washing works is diffusion.
Tap Water is mainly used

40. STAGE 4 : DRYING
Purpose is to remove 85-90% of the moisture from the film.
 If film is dried excessively, emulsion can crack which decrease the diagnostic
quality.

41. TYPES OF FILM PROCESSING
AUTOMATIC
1- Unloading the film
2- Inserting into processor
MANUAL
1-Unloading the film
2-Loading the film onto a hanger
3-Development
4-Rinsing or stop bath
5-Fixing
6-Washing
7-Immersion in a wetting agent
8-Drying

42. AUTOMATIC PROCESSOR

43. AUTOMATIC PROCESSOR
Consists of chemical tanks, a roller transport system and a dryer system for the
processing of radiographic film.
Processing time -amount of time taken to process a single piece of film-90-115s.
Processor capacity – No.of film that can be processed per hour based on which
its divided into high and low.

44. AUTOMATIC PROCESSOR
Tanks
1. For Developer solution
2. Fixer solution
3. Wash tank for water
During a 90s processing cycle
Developer------ 26s
Fixer ----- 15s
Wash ----- 15s
Drier ------ 24s
Travel time----- 10s

45. SUBSYSTEMS OF AN AUTOMATIC
PROCESSOR
Transport
Temperature control
Replenishment
Recirculation
Wash
Drying

46. TRANSPORT SYSTEM
It ensures that the film moves through developer , fixer , wash and dryer at a
controlled and consistent speed without damage
Mainly 3 roller assemblies
1)Entrance roller
2)Transport roller
3)Turn around roller

47. CYCLE OF EVENTS
Drive motor energized(to turn the rollers)
Safelight above the feed tray extinguished
Developer and fixer replenisher pumped into tanks
Drier heater energized
Wash water flow rate boosted
Film signal delay time activated
But how does it get triggered ?

48. ENTRY ROLLER DETECTION SYSTEM

49. INFRARED DETECTOR

50. MOTOR DRIVE
 An electrical motor provides power for the roller
assemblies to transport the film through the processor.
REPLENISHMENT SYSTEM
Function of replenishment system is replacement of fresh
chemicals after the loss of chemicals during processing -
specifically developer and fixer solution.

51. OVER REPLENISHMENT
 Of developer solution causes an increase in radiographic density and decrease
in radiographic contrast.
Of fixer solution – no effect on radiographic quality.
UNDER REPLENISHMENT
 Of developer can cause decreased density.
 Of fixer – result in poor archival quality of finished radiograph

52. RECIRCULATION SYSTEM
To maintain solution activity and the required agitation. Also, to maintain proper
temperature of the developer solution.
Temperature control
If the temperature in developer tank
Raises increases the density.
DropDecreases the density.

53. WASHING
SPRAY WASH
 By the help of processors situated in between the transport roller.
 Water flow rate could be as high as 10 L/min
TANK IMMERSION
 Water fed in to the tank by developer/heat exchanger.
 Water flow rate is between 4-7L/min

54. DRYING SECTION
Initial drying happens when the film moves through the squeegee rollers
between the wash and drying section
While in drying section , it is commonly dried by
1 Hot air drying
2 Infrared drying.

57. Dichroic Fog

58. MANUAL PROCESSING
1-Unloading the film
2-Loading the film onto a hanger
3-Development
4-Rinsing or stop bath
5-Fixing
6-Washing
7-Immersion in a wetting agent
8-Drying
Four Compartment tank – Developing, rinsing, fixing, and washing.

59. MANUALPROCESSING

60. MANUAL PROCESSING TANKS
DARK ROOM

61. MANUAL PROCESSING
DEVELOPING
It is done by time – temperature technique
Here film is immersed in developer for 4 minutes
Temperature is maintained at 20 C
At intervals with in 4 minutes film is examined under safelights
If image seems to lack expected density at 4 minutes, development is
continued

62. MANUAL PROCESSING
RINSING
Purpose is to slow the action of developer and to remove it from the surfaces of
the film, done by a plain rinse bath.
To stop the action of developer, done by acid stop bath.
FIXING
After rinsing, the film is immersed in fixer solution
Fixing time can be up to 5 minutes

63. MANUAL PROCESSING
WASHING
Immerse the film in large tank or in a series of tanks through which water is kept
flowing.
Time duration:- 20 – 30 minutes
DRYING
Hot air drying cupboards or by rapid drier machines.
Temperature may vary from 40-50 C

64. COMPARISON
MANUAL
• DEVELOPING TEMP 200 c
• FIXING TEMP 200 C
• WASHING TEMP 200 C
• DRYING TEMP 430 C
• DEVELOPING TIME 3-5 MIN
• FIXING TIME 2-10MIN
• WASHING TIME 15-30MIN
• DRYING TIME 15-20MIN
• SURFACE CHANGE- MANUAL
• REPLENISHMENT - MANUAL
AUTOMATIC
• 350 C
• 350 C
• 350 C
• 570 C
• 25s
• 21s
• 9s
• 20s
• TRANSPORT ROLLER
• AUTOMATIC

65. THANK YOU