This document provides information on the process of film development. It discusses the components of x-ray film, including the silver halide crystals and sensitivity specks that form the latent image. It describes the chemical and light-induced processes that create this invisible image. The stages of film processing are outlined, including development, rinsing, fixing, washing and drying. Details are given on the chemical constituents and functions of developers, stop baths, fixers and other processing solutions. Factors that influence development such as temperature, time and chemical concentrations are also summarized.

1. Dr Sujesh kumar N
1
FILM
PROCESSING

2. Film
Photochemistry and Latent
image
Basic principles of processing
Manual processing
Automatic processor
Abnormal densities & Processing
artefacts
2

3. FILM
X-ray film-
photographic
film with
radiosensitive
emulsion
coated on a
transparent
base. 3

4. 4
BASE
1.Cellulose nitrate
2.Triacetate
3.Polyester
EMULSION
1.Gelatin
2.Silver halide
3.Anti frothing
agents
4.Anti foggants
5.Wetting agents
6.Fungicides

5. SILVER HALIDES
Radiosensitive
Contains silver
and halide ions
arranged in a
crystal lattice.
Xray film*90-
99%AgBr,1-
10%AgI
5

6. SENSITIVITY SPECK
Chemical sensitisation-
sensitivity of Ag halide is
increased by addition of
allylthiourea which reacts
with it to form AgS.
AgS located on the surface
of the crystal –SENSITIVITY
SPECK
6

7.  When light falls
on xray film
photons are
absorbed by
the crystal.
 Release of an
electron from
Bromine ion
7

8.  This electron is captured and
fixed at the low energy electron
trap or Sensitivity speck.
 The now –ve spec attracts a +ve
Ag ion and forms a Ag atom.
 The process repeats forming a
clump of Ag atoms at the speck.
 No noticeable difference to the
appearance of the crystal
8

9.  This tiny collection of silver atoms has a
critical effect on the chemical behavior of the
silver halide crystal.
 It renders the crystal much more vulnerable
than unexposed crystals to attack by the
reducing agent in photographic developer.
 The sensitivity speck now acts as a
development centre in exposed crystals,
enabling them to be reduced completely to
silver during the development process.
9

10.  The existence on a film of numbers of silver
halide crystals possessing development
centres is said to constitute a latent image.
 Invisible image formed as a result of
exposure to radn,and which may later be
made visible by photographic devlpt.
10

11. The emulsion of X ray films must
be chemically processed to
render visible and permanent
the information recorded in the
latent image.
Complex chemical reaxns whose
activity and efficiency is
governed by factors like temp,
pH of the chemical environment.
11

12. Development
Rinsing
Fixing
Washing
Drying
12

13.  First stage in processing.
 Converts invisible latent
image to visible form.
 Amplifies L.I by millions.
 The basic reaxn is
REDUCTION ie addn of
electrons.
 Starts at the L.I centre.
13

14. PRINCIPLE
The chemical redn of Ag
halides in an exposed
sample is much more
faster than that of an
unexposed sample.
14

15. CHARGE BARRIERS
For development to be effective it’s
action should be selective on the
exposed Ag halides.
Both exposed and unexposed Ag
halides are surrounded by –ve
barrier of Br ions.
 Excess KBr added during
manufacture.
15

16. This charge
barrier
protects Ag
halides from
the attack of
electrons in
the developing
soln.
16

17.  Exposed Ag halide
crystals have a
weakness in this
charge barrier d/t
presence of neutral Ag
atoms collected at the
sensitivity speck.
 This allows the
developer electrons to
easily penetrate such
crystals.
17

18. Thus the Ag atoms in the
latent image acts as a
catalyst for the reduction
reaxn during developing.
18

19. CONSTITUENTS
 Reducing agents
 Solvent- Water Wetting agents
 Accelerators Antifoaming agents
 Restrainers Sequestrating agents
 Preservative Fungicides
 Hardners
 Buffers
19

20. A) DEVELOPER
 Reducing agents- supply electrons for
conversion of silver halides to metallic silver.
 Phenidone, Metol, Hydroquinone – used in
different combns.
 MOA: Developer + Ag ions  ox.developer +
Ag atoms + (H)ions
 Black metallic Ag thus formed is deposited at
the L.I centres.
 Microscopic L.I is enlarged to a visible pattern.
20

21. METOL
Quick onset of action.
Once initiated process
continues more slowly.
Poor selectivity (fogging).
Becomes weak soon- highly
susceptible to Br ion
concentration.
21

22. PHENIDONE
Quick acting.
Poor selectivity.
Produce chemical fog if used
alone.
Less susceptible to Br ion
concentration.
22

23. HYDROQUINONE
 Slow onset of action.
More selective to exposed Ag
halides.
Gives good contrast.
23

24. M-Q COMBINATION
Metol & Hydroquinone produce a
photographic density which is
greater than the sum of the effects
they produce when used separately -
Superadditivity.
HQ reacts with some of the oxidized
metol and regenerates it thus
prolonging its action.
24

25. P-Q developer
 Commonly used combn.
 High selectivity and therefore low chemical fog.
 Adequate activity,adequate contrast
characteristics and also fast acting.
 Synergestic or Super additive effect.
 10-15 times more effective than M-Q developer.
 HQ regenerates some of the oxidised phenidone-
prolongs working life of the soln.
 Cheaper.
 Available as liquid concentrate.
 Less incidence of contact dermatitis &
staining of body parts. 25

26. CHEMICAL FOG
The developer is also capable of
reducing the unexposed Ag halides if
the film spends too much time in it.
Fog is the development of unexposed
Ag halides that donot contain the
latent image.
Thus time is the most important factor in
this process.
26

27. Development should be
DISCONTINUED when the
differential between
EXPOSED DEVELOPED
GRAINS and UNEXPOSED
UNDEVELOPED GRAINS is
MAXIMUM.
27

28.  Optimal pH range of developers- 9.8-11.4
 Alkalinity established by addn of strong
alkalis like K carbonate, KOH,NaOH, Na
carbonate.
 This alkali is known as an accelerator, since its
effect is to accelerate the developing process.
 Too high pH- Over active.
 Too low pH- Sluggish reaxn.
28
B) ACCELERATORS

29. C) RESTRAINERS
Increase selectivity of
developers.
By increasing the charge barriers
around the unexposed grains.
Minimize formation of fog- also
known as ANTI FOGGANTS.
KBr, Benzotriazole.
29

30. D) PRESERVATIVES
Pottassium sulphite.
To decrease atmospheric
oxdn of developer.
To increase regeneration of
phenidone by HQ.
30

31. E) HARDNERS
Mainly in automatic processors.
Prevent mechanical damage from
rollers.
Decrease the amount of water
absorbed by gelatin- easy drying.
Allows use of higher temperatures
during processing.
Glutaraldehyde
31

32. F) WETTING AGENTS
 These are detergent based compounds that
decrease the surface tension of b/w the developer
& the emulsion.
 Allows easy penetration of the chemicals
G) SEQUESTRATING AGENTS
These are chemicals which prevent
the precipitation of insoluble
mineral salts,which tend to occur in
‘hard water’ areas - EDTA
32

33. Developer replenisher- With continuous use
developer becomes weak and it has to be
replenished with replenisher.
Starter solution
33
 Initially when the tank is filled with new
developer, it will be over active d/t high pH and low
KBr.
 First few films will be over developed-FOG
 Prevented by starter solution- ACID RESTRAINER
 When added to developer it decreases pH to
working value and provides KBr restrainer
 Mostly used in automatic processor.

34. FACTORS AFFECTING DEVELOPMENT
1. Constitution of the developing
soln.
2. Developer temperature.
3. Development time.
34

35.  Constitution of the developing solution like the
choice and concentration of the developing agent,
also pH of the developer solution.
 Developer activity increases with temperature
 Manufactureres of developers for manual
processing recommend a temp. of about 20 degree
C for optimum results.
 Development time again depends on the
constitution of the developer solution and
developer temp. Also the type of film emulsion
and the agitation of developer solution.
35

36. 2. RINSING
Stage between Developing and
Fixing.
This stage is not present in
automatic processor.
Objective- Prevent film materials
from carrying active developer
chemicals into the fixer.
36

37. TYPES
1. Plain water rinse- dilutes
developer.
2. Acid stop bath- inhibits further
development.
 PLAIN RINSE
1. Static bath/Dip rinse
2. Spray rinse
3. Running rinse
37

38. 3. FIXING
A film thus taken out of the developer
contains the complete radiological
image.
The unexposed, undeveloped Ag halide
remains in the film as a light sensitive
material.
This if left there will have an obscuring
effect, impending the transmission of
light giving the image an opalescent,
milky appearance.
38

39. DURING FIXING THE
UNEXPOSED INSOLUBLE Ag
halides ARE CONVERTED TO
SOLUBLE COMPOUNDS
AND REMOVED.
39

40. FUNCTIONS OF FIXER
To stop further development.
To clear the image by removing
undeveloped Ag halides.
To fix the image, ie to make it
chemically and radiologicaly
stable and storable.
To harden the emulsion.
40

41. CONSTITUENTS
Solvent
Fixing agent
Acid
Hardner
Buffer
Preservative/Stabilizer
Anti-sludging agents
41

42. A. SOLVENT
Water
Carrying medium for active
constituents.
Hard water is undesirable.
42

43. B. FIXING AGENTS
A chemical which combines with
insoluble Ag halides in the emulsion to
form soluble compounds which can
diffuse out and be washed off.
MUST NOT affect the developed
metallic Ag.
Na thiosulphate, Ammonium
thiosulphate.
43

44. Na THIOSULPHATE
Commonly known as hypo
Reaction with Ag halide gives
Argentothiosulphate and Na halide.
These are soluble and
diffuses out into the fixing
bath.
44

45. AMMONIUM thiosulphate
More rapid action.
Forms highly soluble
compounds.
Washed off very quickly.
Used mainly in automatic
processors.
45

46. Disadvantage
Compounds formed are less
stable.
Improper washing after fixing
leads to quicker staining and
deterioration of the image.
46

47. C. ACID
 Acidic pH to stop developer action and to provide
suitable environment for hardner.
 Ideal pH = 4-4.5
 Weak acids like acetic acid is used.
 Insufficient acidity – inadequate hardening.
 Too acidic – thiosulphate breaks down and ppt
insoluble sulphur – Sulphurisation.
47

48. D. HARDNERS
Limits water uptake by the
emulsion.
Essential in automatic processors.
Decrease drying time and prevents
physical damage by rollers.
Allows use of higher temperatures.
Al chloride, Al sulphate,
Chrome alum, Potash alum.
48

49. E. BUFFER
 For precise control of pH, to
prevent sulphurisation , to
ensure neutralization of
developer, to provide optimal
hardening.
 Sodium acetate
49

50. F. PRESERVATIVE
Retards decomposition of
thiosulphate.
Delays onset of sulphurisation.
Eg: Na sulphite, Na acetate
Na and K metabisulphates- acts
as acid stabilizers with some
buffering action.
50

51. G. Anti-sludging agents
Aluminium salts used as hardners
have a tendency to produce
insoluble Al compounds which
may ppt out of the solution to form
a sludge.
This adheres to the film and sides
of the fixing tank.
BORIC ACID
51

52. FACTORS AFFECTING FIXING RATE
1. CONSTITUTION OF FIXING
SOLUTION
2. FIXER TEMPERATURE
3. FIXING TIME
52

53. 1. FIXER CONSTITUTION
Fixer type- Ammonium thiosulphate-
rapid
Concentration of fixing agent
Hardners- slows fixing
Increasing Ag thiosulphates- retards
fixing
Soluble halides- slows down
pH of fixer
53

54. 2. FIXER TEMPERATURE
Fixing is faster at higher
temperatures as the emulsion
softens.
A big difference in the
temperatures of fixer and
developer results in emulsion
damage, d/t rapid swelling of
gelatin- RETICULATION
54

55. 3. FIXING TIME
 Higher the fixer activity, the shorter is the
required fixing time.
 Type of emulsion- AgBr faster
 Emulsion thickness- thin- rapid
 Direct exposure films-thick-more processing time
 Agitation accelerates fixing by speeding up the
removal of byproducts from the film surface and
replacement with fresh fixer.
55

56. Fixer replenisher– With continuous
use fixer becomes weak and needs
to be replenished with the
replenisher. Available as liquid
concentrates.
56

57. 4. WASHING
 When the film leaves the fixing
tank it carries in its emulsion a
layer comprising of
1. Argento-thiosulphates
2. Residual fixers
3. Remaining salts- NaBr, NH4Br
57

58. These compounds if left on the film will
destroy the image.
Ag thioSO4- decompose to AgS-
Yellow brown discoloration.
Residual fixers + Ag in the image –
AgS- Yellow brown discoloration.
Residual salts crystallize on the
surface making it difficult to view.
58

59.  All these compounds being water
soluble can be removed by washing-
the process being simple diffusion.
 Washing time in manual processing
-a minimum of 10 min.
 The film surface is ideally exposed to
continuous flow of uncontaminated water,
either by spray mechanism or rapidly flowing
fresh water bath.
59

60. 5. DRYING
Final stage in processing.
To remove all the surface water and
most of the water retained in the
emulsion.
Some moisture must remain to prevent
it from becoming too brittle.
Ideally the film should retain 10-15% of
its own weight of water.
60

61. DRYING METHODS
The most common method of
drying employed in manual
processors is by air.
Hot air drying or infra red
drying are used in automatic
processors.
61

62. MANUAL PROCESSING UNIT
62
 The manual processor essentially
consists of a large master tank with
some smaller tanks & divisions.
1. A lidded tank for developer
2. A compartment for rinsing (tap
water)
3. A tank for fixer
4. A large compartment of water for
washing the fixed films.

63. 63
A MANUAL
PROCESSING
UNIT

64. MANUAL PROCESSING
PROCEDURE
64
After exposure the cassette
containing the film is taken to the
dark room.
The film is unloaded under safe
lighting.
The film is placed in the processing
hanger of appropriate size.
The loaded hanger is immersed in
the developer solution and lightly

65. 65
When adequate development has
occurred the hanger is transferred
into the rinse tank.
Next the film is suspended in the
fixer solution.
The last wet stage of processing is
washing.
The film is then dried in air & is
ready for viewing.

66. Duration of different stages in a manual
processor-
66
Development- 3-5min
Rinse- 10-20sec
Fixing- 5-10min
Washing- 10-15min
Drying- 20min
Total= 40-50min

67.  All automatic processors possess :-
 A system which mechanically transports
films through the processor.
 A system which provides for replenishment
& recirculation of the chemical solutions.
 A system concerned with water circulation.
 A system for temperature control.
 A system for drying films.
67

68. All factors which influence
the quality of the
radiograph can be kept with
in fine limits.
Processing time is much
less.
68

69.  A film which is introduced into the
automatic processor is moved
through the different chambers by
means of a system of rollers in 2
ways
1. Vertically
2. Horizontally
 Rollers are made of- Rubber/ Steel/
PVC
69

70. 70

71.  Developer - 26 sec
 Fixer - 15 sec
 Wash - 15 sec
 Dryer - 24 sec
 Travel time - 10 sec
Total – 90 sec
71

72. ABNORMAL DENSITIES
 Films without sufficient density:
1. Too short development time.
2. Exhausted developer.
3. Too low developer tank temperature.
4. Too low developer pH.
 Films with too high density:
1. Too high developer temperature.
2. Starter solution missed – High pH.
3. Too long development time.
72

73. PROCESSING ARTEFACTS
FINGER MARKS
 Handling the film surface with the
fingers before it has been
processed.
 Moisture transferred to the film
surface from the skin modifies the
action of the chemicals.
 Hands previously contaminated
with chemicals or metals more
likely to cause markings. 73

74. PRESSURE MARKS
 Application of undue pressure/stress to
the emulsion before/during devlpt.
 Crimp marks – Crescent shaped marks
occur during handling if a film becomes
kinked or creased when it droops under
its own weight.
74

75. CHEMICAL STAINING
Fixer artefacts – White marks d/t
fixer droplets falling on the
undeveloped film.
 Inadequate fixing results in a milky
white, opalescent appearance.
 Inadequate washing leads to
yellow-brown staining, d/t unstable
sulphur compds. Develops slowly
over time.
75

76. Black Splashes
 The film has been splashed with
developer before the development.
This area develops faster than the
rest of the film making it darker.
 Due to splashes of water falling on
the film before development.
Water softens the emulsion  faster
development.
76

77. SURFACE DAMAGE
 Film emulsion is delicate & prone to
damage during processing.
 A badly adjusted transport system may
cause abrasions on the film surface.
Pi marks – Regularly placed marks
across the film - damage produced by
the rollers in the processor.
Reticulation/ Frilling - Detachment of
the emulsion from the base d/t adverse
processing conditions.
77

78. STATIC MARKS
 These are d/t the
static electrical
charges that
accumulate as a
result of friction.
 Such electrical
discharges trigger
chemical changes
which mimic an
exposure & lead to
the black static
marks.
78

79. THANK YOU…
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