The document discusses procedures for a dark room used in medical radiography. It provides details on the layout, equipment, and setup of a dark room. Key points include: - A dark room must be lightproof and have adequate space for a dry bench, wet bench, and sink. Special lighting and filters are used to allow safe viewing of films. - Equipment includes cassettes, hangers, a film bin, and either a manual or automatic film processor. Chemicals are needed for developing, fixing, and washing films. - Proper development involves immersing films in tanks containing developer, fixer, and rinse solutions. Strict temperature control and timing is required to reveal the latent image on

1. DARK ROOM PROCEDURES
Presenter – Dr.Anuraj
Moderator – Dr. C.N. Pradeep Kumar

2. WHAT IS A DARKROOM ?
 Enclosed area or chamber dimly lit by
safelight (usually red) but otherwise
intentionally lightproof room where films are
handled and processed.

3. DARK ROOM LAYOUT
 A room should be set aside as a permanent dark room, ideally with a
floor area of not less than 10sq. m.
 The room must be capable of being made completely lightproof.
 It should not be damp or subjected to extremes of temperature.
 Water and electrical outlets should be provided.
 Sufficient space to accommodate a dry bench , a wet bench and a sink.
 Too large room is as undesirable as small room.
 Should be near the x-ray examination area.
 Should be well ventilated.
 The wall should be constructed of solid concrete (15 cm thick), have a
lead box inside to store boxes of unexposed films currently in use.
 The walls and roof should be painted by white or cream enamel as such
a paint acts as a good reflecting surface for safe light.
 X-ray rotating warning light in hallway switched "on" signaling that x-ray
machine is operating.

4. LOCATION
 Centrally located
 Serviced by hatches
from the adjacent
imaging room
 Away from damp or hot
areas
 Accessible in terms of
power and water supply
 Adjoining viewing room

5. SIZE
 Minimum floor area of 10 sq meter
 Ceiling height of 2.5 - 3 meter
 Size may be reduced depending upon the
department needs

6. LIGHT PROOF
 The first requisite of a processing room is the
exclusion of all external white light when
radiographs are processed.
 Photosensitive crystals in film emulsions are
extremely sensitive to visible light, and any light
leaking around a door or window may fog and ruin
the films.
 A door that can be locked to avoid accidental
exposure of film to white light.
 Alternatively a light outside the door indicating that
the darkroom is in use.When the white light in the
darkroom is switched off, the indicating light outside
automatically goes on

7. RADIATION PROTECTION
 Walls adjacent to the radiographic room
should be shielded with correct thickness of
the lead all the way to the ceiling
 In the interests of both darkroom staff and
film material alike
 1.6 mm lead is mostly used

8. FLOORS
 Non-porous flooring
 Non-slip flooring
 Chemical resistant
 Stain proof
 Durable & easy to
maintain
 Light coloured (low-
light working
conditions)
 Asphalt tiles
 Porcelain tiles
 Clay tiles
 Plastic tiles may be
used in the dry dark-
rooms

9. WALLS/CEILING
 Light in colour to reflect as much light as
possible onto the working surface
 Easy to wipe or clean
 Covered with chemical resistant materials
 Special paints, varnish, ceramic or plastic wall

10. VENTILATION AND HEATING
 Satisfactory working conditions for the staff
 Good film handling and storage conditions
 Efficient automatic processor performance
 Relative humidity is maintained at around 40-60 %
 Room temperature maintained between 18-20 degree
celsius
 A minimum of 10 air changes per hour
 All of these conditions can be achieved by using a good
air-conditioning system
 Alternatively, fairly satisfactory ventilation can be
achieved by using an extractor fan sited higher than and
diagonally opposite a second fan, the latter being so
placed as to obtain fresh and filtered air from outside.

11. TYPE OF ENTRANCE
 SINGLE DOOR SYSTEM
 DOUBLE DOOR SYSTEM
 MAZETYPE ENTRANCE
 LABYRINTH
 ROTATING DOOR SYSTEM

12. DARK ROOM ENTRANCE
REVOLVING DOOR SINGLE DOOR

13. DOUBLE DOOR MAZE

14. MAZE TYPE ENTRANCE

15. ROTATING DOOR ENTRANCE

16. DARK ROOM ILLUMINATION
 WHITE LIGHTING
 SAFELIGHTING

17. WHITE LIGHTING
 For inspection & maintenance of cassettes &
screens
 Cleaning of work surfaces
 Servicing of equipment
 Sited close to the ceiling
 Moderate in intensity
 (60w tungsten, 30w fluorescent )
 Preferably centrally placed

18. SAFE LIGHTING
 DIRECT SAFE
LIGHTING:
 Light from safe lamp
directly falls onto the
work surface
 Eg. Beehive safelamp
 Minimum distance of
1.2 m/ 4 feet from the
working surface
 Best for loading &
unloading areas

19. INDIRECT SAFE LIGHTING
 Directs the light towards the ceiling which
reflects light back into the room
 Is intended to provide general illumination of
the dark room
 Suspended atleast 2.1 m above floor level

20. SAFE LIGHT FILTERS
 Sheet of gelatin dyed to
the appropriate colour
and sandwiched
between two sheets of
glass for protection
 Used in conjunction with
a 15W lamp
 Extremes of heat and
temperature
deteriorates the filter
gelatin
 Should be cleaned
periodically

21. How Does A Safelight Work?
 When white light is passed
through coloured filters,
certain wavelengths (or
colours) are absorbed by
the filters, whilst those
wavelengths, which
correspond to the colour of
the filters will be
transmitted.
 Making the correct
selection of safelight filter
(matching the filter to the
film), means choosing a
filter, which will transmit a
colour to which the film is
relatively unresponsive,
whilst stopping all light to
which the film is most
sensitive.

22. WHICH COLOUR FILTER TO USE?
 X-ray films have the highest sensitivity to the
blue-green part of the light spectrum .The X-
ray film is less sensitive to light in the
opposite region of the spectrum - i.e. the
yellow and red region. It is obvious that the
blue filter cannot be used, neither a green
color filter as it is so close to the blue.
Therefore safelights are safest when made
with amber or red filters.

23. How Safe Is Safe Lighting?
 No safe lighting is completely safe; all films will
become significantly fogged if exposed to
safelights for long enough.
 This is because safelight filters are not perfect
absorbers of the undesirable wavelengths and, in
truth, all films have some sensitivity to all
wavelengths.
 Thus, the intensity of illumination and the film-
handling time must be kept to a minimum if
significant fogging is not to occur.

24. Safelight illumination test
 Place a coin on a small piece of photo paper.
Let it sit for 20 min. and develop the paper. If
you see the outline of the coin, your safelight
isn't safe
If the safelight is not safe, you should do one of
the following to correct the problem:
1. Replace the bulb with one of lower wattage
2. Raise the safelight lamp higher from working
surface
3. Check the filter - may be cracked or broken

25. DARK ROOM EQUIPMENTS
 Automatic processor
 Manual process unit
 Processing chemicals
 Hangers for suspending film
 Cassette
 Film storage hopper
 Loading bench
 Cupboards

26. DARK ROOM EQUIPMENTS
Film cassettes:
 A cassette is designed to hold the x-ray film and intensifying screens in close
contact.
 The front face which is of aluminum or plastic, faces the tube while the other
side have a sheet of lead to absorbed back-scatter screens and cassettes are of
course made in various sizes to correspond with standard film sizes.
Mounting intensifying screens in the cassette
 Intensifying screens should be never be loose but must be properly mounted into
the cassette.
 Because certain adhesives interact with the screens it is advisable to use only the
double-sided tape provided by the manufacturers.
The care of cassettes
 Do not drop them on a hard floor
 Do not trap the edges of the screens when the cassette is closed
 Cassettes should be kept clean and there is always the danger of blood or urine
leaking to the inside of the cassette. When a cassette must be placed in a dirty
situation put it in a plastic bag.

27. Dry Bench
 The dry bench is where the cassettes are unloaded and
recharged with fresh film. It must be impossible for splashes
of developer to reach the dry bench surface.
 The top of the dry bench must be large enough to
accommodate the largest cassette in use when opened out.
 The top surface should be either of wood or linoleum. Plastic
laminates are not recommended because they hold static
charges of electricity which can cause marks on films.
 It is usual to store film boxes, especially those in current use ,
beneath the dry bench , either in a cupboard ( protected if
near an X-ray set ) or in a film hopper.
Wet Bench
 The wet bench is where the processing of the films is carried
out.
 The usual method is to use a set of tanks holding developer
,rinse water and fixer , and a larger tank for washing the films.

28. DARK ROOM DRY BENCH SYSTEM

29. PROCESSINGTANKS
1. MASTERTANK
 This tank serves as a water jacket to hold the
insert tanks and is usually large enough to
provide space between insert tanks for
rinsing and washing of films.The water
assists in maintaining the same / constant
temperature in the insert tanks.
2. INSERTTANKS
 These are removable containers for the
individual processing solutions - (developer
and fixer), and are spaced in the master tank

30. MANUAL PROCESS UNIT IN PKTB HOSPITAL

31. AN AUTOMATIC PROCESSOR

33. AUTOMATIC PROCESSOR

34. PROCESSINGCHEMICALS

35. Hangers used for suspending films during processing

36. CASSETTES

37. FILM BIN
FILMS
8 X 10
10 X 12
11 X 14
14 X 17
TYPICAL DARK ROOM FILM BIN
SLOTS OF DIFFERENT SIZES

39.  14 X 17
 11 X 14
 10 X 12
 8 X 10
 7 X 17
 6 X 12
 14 X 36
 35 X 43
 28 X 35
 25 X 30
 20 X 25
 18 X 43
 15 X 30
 35 X 91
RADIOGRAPHIC FILM SIZES

40. Film Processing

41. RADIOGRAPHIC FILM

42. Gurney Mott hypothesis
This process repeats.

43. Chemical sensitization
 Chemical sensitization of the crystals are
produced by adding allylthiourea, a sulfur
containing compound to the emulsion , which
reacts with silver halide to form silver sulfide.

44. Sensitivity Speck
• This Silver Sulphide
is usually located
on surface of the
crystals and is
referred as
“sensitivity speck”.

45. Point defect in
cubic lattice.
Sensitivity
speck by Silver
sulfide
The sensitivity speck traps electron and form latent image.

46. The film is then passes through the following four
steps
Developing
Fixing
Washing
Drying

47. DevelopingAgent
Accelerator
Restrainers
Preservative
Hardener
Solvent
CONSTITUENTSOF
DEVELOPING
SOLUTION

48. Development
 It is the first stage in
processing of the
radiograph.
 Amplifies latent image
by 100,000,000!
 The primary purpose:
convert the invisible
latent image into
visible form.
 Processing initiated at
latent image speck

49.  These are the reducing agents, which carry out
the primary function of supplying the electrons
that convert the exposed silver halide grains to
silver.
 Characteristics:
1. Selectivity
2. High activity
3. Should be resistant to bromide ions in the solution.
Developing Agents

50. 1.DEVELOPINGAGENTS
Hydroquinone + phenidone/metol
 Hydoquinone(developer) +silver ions
quinone(oxidised develper) + silver atoms +
hydrogen ions
 Phenidone(developer)+silver ions oxidised
developer+silver atoms+hydrogen atoms

51.  Advantages of PQ developers
1. Tolerant of increase in bromine ion concentration.
2. High selectivity and low chemical fog.
3. Adequate activity even in low concentrations.
4. Available in liquid concentrate form.
5. Fast acting
6. Adequate contrast
7. Super additive effect

52. SUPER ADDITIVE EFFECT

53.  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)
DEVELOPINGSOLUTION

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

55. 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
DEVELOPINGSOLUTION

56.  Temperature of the developing solution
 Total time of the development
An adequate combination of both is important for complete
development
FACTORSAFFECTINGDEVELOPMENT

57.  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
TEMPERATUREFOR DEVELOPMENT

58.  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.
STAGE 2:FIXING

59. 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
FIXATION

60. 1. Solvent
2. Fixing agent
3. Acid
4. Hardener
5. Buffer
6. Preservative
7. Anti-sludging agent
Constituents of the fixing
solution:

61. 1.SOLVENT
Water
2. FIXING AGENT
2 agents:
 Cyanides
 Poisonous
 Not generally used.
 Thiosulfates - Sodium and Ammonium Salt (more active)
– called Hypo.
AgBr + sod.Thiosulfate

Ag thiosulfate complex + NaBr
(water soluble)

62. 3. Acid:
 Prevents dichoric fog by inhibiting developing agents.
 Provides a suitable environment for the hardening agents in
the fixer.
 Acetic acid is used usually at a pH of 4-4.5.
4. Hardener:
 Reduces drying time and prevents physical damage.
 Aluminium chloride and aluminium sulfate (or Chromium
compounds) are used commonly.
5. Buffer:
 Prevents sulphurization.
 Neutralizes the developer
 Sodium acetate is commonly used in conjunction with acetic
acid

63. 6. Preservative:
 Retards decomposition of thiosulphates
 Sodium sulphate is commonly used
7. Antisludging agent:
 Boric acid is commonly used and this prevents sludging
of insoluble aluminium compounds in the hardener.

64.  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
STAGE 3 : WASHING

65.  The drying medium is dry air of low humidity, which accelerates the
evaporation process and reduces drying time.
 Film drying box
Heating element with a circulating fan.
It can dry in 15 minutes.
 Film will dry properly if hung
in air for a longer period (1+ hours).
STAGE 4 : DRYING

66.  The longer the film spends in the fixer, the longer
the wash time needed
 This is a 1:2:3 ratio of developer to fixer to wash

67. TYPES OF FILM PROCESSING
AUTOMATIC MANUAL
• Unloading the film
• Inserting into
processor
Unloading the film
Loading the film
onto a hanger
Development
Fixing
Washing
Drying

68. 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

69. MANUAL PROCESSING

70. MANUALPROCESSING
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

71. 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

72. MANUALPROCESSING
 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

73.  Developing – formation of the image
 Fixing – stopping of development,
permanent fixing of image on film
 Washing – removal of residual fixer
 Drying – warm air blowing over film
4 Steps of Processing

74. COMPARISON
• DEVELOPING TEMP 200 c
• FIXINGTEMP 200 C
• WASHING TEMP 200 C
• DRYING TEMP 430 C
• DEVELOPING TIME 3-5 MIN
• FIXINGTIME 2-10MIN
• WASHING TIME 15-30MIN
• DRYINGTIME 15-20MIN
AUTOMATIC
• 350 C
• 350 C
• 350 C
• 570 C
• 25s
• 15s
• 15s
• 20s
MANUAL

77. CLEANING THE PROCESSING TANKS
 The action between the mineral salts in the
water and carbonate in the developing
solutions produces a deposit on the inside
wall of the processing tanks.
 A commercially prepared stainless steel tank
cleaner can be used to remove these
deposits.
 Or simply brush thoroughly with a brush and
water.

78.  The developing solution should be tightly
covered when not in use to reduce oxidation.
 The solution should be discarded and
replaced after three months of use because
oxidation and accumulation of gelatin sludge
and other impurities will cause poor
development.
 As the solution weakens it first turns yellow,
then brown.When it turns brown, indicating
exhaustion, it should be replaced.
Few important points to be kept
in mind

79.  Christensen’s physics of diagnostic radiology
REFERENCES