Presentation of constituents of Radiographic film and its processing. Also includes Automatic film processor

1. RADIOGRAPHIC FILM AND FILM PROCESSING
Dr.Tarique Ajij
Junior Resident,
Department of Radio-
Diagnosis,
Medical College,
Kolkata

2. X-RAY FILM
• Differential attenuation of X-ray within
the patient contains medical
information.
• This information captured and decoded
by photographic film.
• However to decode this information
film has to be processed and
developed.
• Main part of a X-ray film is a radiation-
sensitive, photographically active
material made in the form of emulsion
quoted on the supporting material
called base.

3. TYPES OF FILMS
• Basis of coating:
• Single Emulsion
• Double Emulsion
• Based on sensitivity
• Blue sensitive films
• Green sensitive films
• Panchromatic films
Based on use of screens
• Non Screen type
• Screen type
• Single screen
• Double Screen

4. RADIOGRAPHIC FILM
• Layers:
• Base
• Adhesive Layer
• Emulsion
• Supercoat

5. BASE
• Ideal Characters:
• Should not absorb light or produce
visible pattern during viewing
• Flexibility, thickness and strength will
be such to allow easy processing.
• Dimensional stability: shape and size
will not be changed during processing
and storage.
• Low flammability

6. TYPES OF BASES
• Glass Plates – Used in past, thin layer of
emulsion on one side.
• Cellulose Nitrate – Used in 1914,
inflammable – Caused fire accidents.
• Cellulose Tri acetate – Adopted in 1924, Non
inflammable.
• Polyester –
 Adopted in 1960.
 Better dimensional stability and colorless.
 Dimethyl terepthalate(DMT) and ethylene
glycol are brought together under low
pressure and high temperature to form molten
polymer, stretched into sheets.
• Eg. Cronex

7. TINTED BLUE FILM
• Triacetate and Polyester are clear and
colorless.
• Adopted in 1933, blue tint was added
to the x-ray film in an effort to produce
a film that was “easier” to look at.
• Causes less eye strain.
• Blue tint can be added to either to the
base or to the emulsion.
• All present x ray films are blue tinted.

8. EMULSION
• Photosensitive Layer of the film.
• Key ingredients:
• Gelatin
• Silver Halide
• Thickness not more than 0.5 mils ( 5-25
µm.)

9. EMULSION
GELATIN
• Produced from Cattle bones, later
synthesized.
• Advantages:
-Keeps ‘Silver Halide grains’
• Well dispersed
• Prevents Clumping of grains
-Developing solutions can penetrate
Gelatin rapidly without damaging the
structure and strength.
- Easily available in large and uniform
quality.

10. EMULSION
SILVER HALIDE
• Light sensitive material in emulsion.
• Composition:
• 90-99% Silver Bromide
• 1-10% Silver Iodide - it increases
sensitivity
• Silver Iodo-Bromide crystals are
precipitated and emulsified in Gelatin
• Precipitation reaction involves addition
of Silver Nitrate to Soluble Halide to
form soluble silver halide.
AgNO3 + KBr  AgBr + KnO3

11. CRYSTAL LATTICE
• The Silver Iodo-Bromide crystals in the
emulsion is in the form of crystals
suspended in gelatin.
• Crystals are formed by Ions of Ag+, Br-,
I- arranged in Cubic Lattice.
• Crystal size will vary from 1.0 to 1.5
microns in diameter.
• Each cubic centimeter of Emulsion
contains 6.3 x 109 crystals.
• 1 grain averages 1 - 10 million silver
ions

12. EMULSION
CRYSTAL DEFECTS
• An Imperfect Crystal (perfect crystal
has almost no photographic
sensitivity).
• Several types of crystal defects noted.
• A Point defect consists of a Silver Ion
that has moved out of its normal
position in crystal lattice (Interstitial
Ions).

13. EMULSION
CRYSTAL DEFECTS
• A dislocation is a line imperfection in
the crystal.
• Cause a strain in the wall structure.
• Iodine ion strains the crystal in this way

14. EMULSION
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.

15. • This Silver Sulphide is usually located on
surface of the crystals and is referred as
“sensitivity speck”.
• The sensitivity speck traps electron and
form latent image.

16. THE LATENT IMAGE
• Remnant radiation interacts with the silver
halide crystals
• Mainly by the photoelectric interaction
• The energy deposited into the film is in the
same pattern as the subject that was
exposed to radiation
• This invisible image is known as the latent
image
• A latent image on photographic
(radiographic) film is an invisible image
produced by the exposure of the film to
light (radiation).

17. THE MANIFEST IMAGE
• By chemically processing the latent
image it is made visible
• Certain chemicals permanently fixate
the image onto the film

19. FORMATION OF LATENT IMAGE
• Metallic silver is black, so it is this
metallic silver that produces black areas
on a developed films.
• Exposure of silver-iodo-bromide grains
to light photons emitted by screen /
direct x-ray exposure initiates the
formation of atomic silver to form a
visible pattern.

20. FORMATION OF LATENT IMAGE
GURNEY MOTT HYPOTHESIS
• The energy absorbed from light photon gives an electron in
the bromine Ions enough energy to escape, which can move
in the crystal till it reaches sensitive speck, which acts as
Electron trap, and temporarily fixed.
Br- + light photon  Br + electron
• This Sensitive Speck is negatively charged and attracts the
mobile Interstitial Silver Ion and neutralizes to form Silver
Atoms.
Ag+ + e-  Ag
• This Silver atom traps next electron, attracts second Silver Ion
to form two Silver atoms.
• Negative Bromine Ions lose electron to form bromine Atoms
leaves the crystal and diffuses into Gelatin.
• If >6-10 Ag0 accumulate at speck, it becomes a latent
image center: ie, it is developable

21. DIRECT X-RAY EXPOSURE OF FILM
• Photoelectric & Compton interactions
in film (silver halide in the emulsion)
• Liberated electrons have long ranges
• These electrons strip other electrons
from Bromide ion
• Bromine atoms & free electrons
produced
• Electrons captured at sensitivity speck
as before
Efficiency
• most photon energy lost
• much energy lost in gelatin
• only 3 - 10% of photon energy
produces silver
• sensitivity varies with
• kVp (energy)
• processing

22. ADHESIVE LAYER
• Firm attachment between emulsion
layer and film base is achieved .
• Guards integrity during processing and
fixing.

23. SUPER COATING
• Thin layer of Gelatin
• Protects the emulsion from mechanical
damage
• Prevents scratches and pressure marks.
• Makes the film smooth and slick

24. FILM PROCESSING
• Series of events after the film is exposed to
X-rays

25. 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

26. DEVELOPMENT
• Development is a process of chemical
reduction.
• The reduction is achieved by the developer
donating electrons to silver ions in the
exposed silver bromide and iodide grains
converting them to atoms of metallic silver.
Ag+ + electron  Ag
• The mode of action of developer is not fully
understood but the existence of electric
charge barriers around the halide grains is
thought to be involved.

27. CHARGE BARRIERS
• Both exposed and unexposed silver
bromide grains are surrounded by a
negative charge barrier of bromide
ions created by the excess of
potassium bromide employed in the
synthesis of silver bromide during the
manufacture of emulsion.
• The charge barrier protects the silver
bromide from attack by electrons in the
developer solution.
UNEXPOSED GRAIN

28. CHARGE BARRIERS
• Exposed silver bromide grains possess
a weakness in the charge barrier
caused by the presence of neutral silver
atoms, which have collected at the
sensitivity speck.
• This development center enables
electrons from the developer to
penetrate the grain and reduce all its
silver ions to metallic silver.
• EXPOSED GRAIN

29. • Silver atoms at latent image center act
as catalyst
• Grain either develops entirely or not at
all

30. CONSTITUENTS OF THE DEVELOPER
• Solvent
• Developing agents
• Accelerator
• Buffers
• Restrainer
• Preservative
• Hardener
• Sequestering agents

31. DEVELOPER
1. SOLVENT
Water is the solvent commonly
used in replenisher solution.
• This also controls developer activity
by diluting its effects.
• It has a softening effect on the
gelatin, thus allowing the
developing chemicals to penetrate
the emulsion and act on the silver
halides.
• The presence of calcium salts in the
water (hard water) may form a
chalky deposit or scum on the
surface of the film.
• More serious would be
contamination of the solvent with
dissolved metals like copper and
iron. The presence of only a fewer
parts per million of copper could
cause chemical fogging.
• In practice, such effects are
extremely rare.

32. DEVELOPER
2. DEVELOPING AGENTS
• 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: Selectivity and activity
tend to be antagonistic properties.
An agent with high activity generally has
low selectivity and vice versa.
3. Should be resistant to bromide ions in
the solution.

33. • No single agent satisfies all these requirements Modern
X-ray developers use a combination of 2 developing
agents phenidone and hydroquinone known as PQ
developer.
• Phenidone is a quick acting reducing agent capable of
developing all exposed silver halide grains. However, its
selectivity is low and if used alone would result in high fog
levels.
• Hydroquinone requires a strong alkaline medium for its
action. This is more selective than phenidone but slower
in onset of action. Once its action has begun the
development proceeds vigorously although lightly
exposed grains are not affected by hydroquinone.
• Hydroquinone and Phenidone – High Contrast
• Metol – High Speed/Low Contrast/Fine grain
DEVELOPER
2. DEVELOPING AGENTS

34. DEVELOPER
2. DEVELOPING AGENTS
REACTION
• Involves donation of Electron by
developing agent to form metallic
Silver by Silver Ion (with inactivation of
developing agent and liberation of
hydrogen ions )
Alkaline
Medium

35. DEVELOPER
2. DEVELOPING AGENTS
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

36. DEVELOPER
3. ACCELERATORS
• PQ developers need alkaline medium
for their action (10 - 11.5 pH). Includes
Sodium Hydroxide, Sodium Carbonate
and Borates.
• This alkali is known as accelerator since
its effect is to accelerate the developing
process.

37. DEVELOPER
4. BUFFERS
• It has the effect of maintaining the pH
of a solution within close limits.
• Normally adequate buffering action is
provided by the carbonates used as
accelerators and sulphides used as
preservatives. Thus no additional
buffers are necessary.

38. DEVELOPER
5. ANTI-FOGGANTS/RESTRAINERS
• Decrease the formation of Fog (fog is the
development of the unexposed silver halide
grains that do not contain a latent image ).
• It also decrease the development of the latent
image.
• Anti-foggants permit rapid development of
exposed grains at higher temp with minimized
fog development.
• The development process itself produces as a
byproduct potassium bromide which is a very
effective restrainer.
• So the developer replenisher need not include
potassium bromide among its constituents.
However it is usual to provide a powerful
restrainer / antifoggant such as benzotriazole.

39. DEVELOPER
6. PRESERVATIVES
• Sodium sulphite
• Oxidized products of developing
agents form colored material that can
stain the emulsion, sodium sulphite
forms colorless soluble products after
combining with colored oxidized
products of developing agents
(sulfonates).
• It acts as a preservative by preventing
oxidation of hydroquinone by
removing dissolved oxygen in the
solution and at the interface.
Sodium Sulphite
Coloured product
(stain the emulsion)

40. DEVELOPER
7. HARDENERS
• Powerful organic hardeners such as
gluteraldehyde which prevent the
excessive swelling of gelatin in the
emulsion when it absorbs water during
development.
• If the emulsion is over hardened the
speed with which the developing
agents penetrate the silver halide
grains is reduced.

41. DEVELOPER
OTHERS
8. Sequestering agents: Prevent
precipitation of insoluble mineral salts,
which tend to occur in hard water areas.
Compounds based on EDTA are used for
this purpose
9. Others: Bactericides and fungicides.

42. RINSING
• Rinsed for about 30sec in running
water.
• Will remove the developer diffused
into gelatin.
• Reduces the speed of development.

43. REPLENISHMENT
• During development, Bromide Ions are
released by the reduction of silver ions to
atoms and they pass into solution to
increase Br concentration, which limits the
life of the developing solution.
• The purpose is to maintain:
• developing agent conc.
• preservative conc.
• Bromide conc. and
• pH at constant level
(during the process of development the
developing agents, preservatives are
consumed and H+, Br- are increased )

44. DEVELOPMENT REACTION (HIGH VOLUME)
• Bromide and acid are formed (pH is
lowered)
• Developer is consumed
• Replenisher formulas have a higher pH
,contains no bromide.
• Rate of replenishment — 60ml of the
developer is replaced with replenisher
for each 14 x 17 inch film.
2AgBr + H2Q + Na2SO3

2Ag + HBr + HQSO3Na + NaBr

45. OXIDATION REACTION (LOW VOLUME)
• pH is raised
• No bromide is produced.
• Replenisher formulas have a lower pH
,contains bromide and high sulfite conc.
to retard oxidation.
• Rate of replenishment — 90ml of the
developer is replaced with replenisher
for each14 x 17 inch film (rate is higher
to increase the developer turn over
rate).
H2Q + Na2SO3 + O2

HQSO3Na + NaOH + Na2SO4

46. FACTORS AFFECTING DEVELOPMENT
1. Constitution of developing solution
2. Developer temperature
3. Development time

47. 1. Constitution of developing
solution: For a particular level of
exposure image density depends
both on the emulsion characteristics
and on the developer activity. The
developer activity is influenced by
i. Choice of developing agents and
their relative proportions.
ii. Concentration of developing agents
in solution.
iii. pH of the developer solution.
iv. Concentration of restrainer and
antifoggant.
FACTORS AFFECTING DEVELOPMENT

48. FACTORS AFFECTING DEVELOPMENT
2. Developer Temperature: Developer activity
increases with temperature as many other chemical
reactions.
High temperature development: A range of 38-
420C is used which enables 90 seconds or even faster
cycle times to be operated.
Low temperature development: Operated at
around 300C and can still produce very rapid results.
Some developers are extremely versatile and can be
used over a range of temperature requiring different
processor cycle times (ex. a 7 minutes cycle at 200C, a
90 seconds cycle at 300C).
Medium temperature development:
Between 33-370C.

49. FACTORS AFFECTING DEVELOPMENT
• Slightly raised temperature causes
• increased image density for the same
exposure (thus increased film speed).
• Slightly increased chemical fog.
• Increased image contrast.
• More severe raise in temperature leads
to
• gross increase in density.
• Un-acceptable increase in chemical fog.
• Reduction in contrast.
Effects on the image of increased
temperature:

50. FACTORS AFFECTING DEVELOPMENT
• Slightly lowered temperature causes
• low density and
• low contrast.
• A more severe fall in temperature leads
to
• gross overall reduction of density and
• loss of contrast.
Effects on the image of decreased
temperature:

51. FACTORS AFFECTING DEVELOPMENT
3. Development time:
• Defined as the time between the entry
of a specified part of the film into the
developing solution and exit from the
developing solution of the same part of
the film.
• Factors determining development time:
(a) Developer activity
(b) Type of emulsion: Developer solution
takes longer time to penetrate a thick
emulsion than a thin one. Non-
screen films require longer time.
(c) Agitation of the developer solution:
This is not a problem in automatic
processors because of constant
motion of the solution caused by the
roller mechanism

52. FIXING
• It has 4 major functions:
1. To stop further development
• Making it acidic
2. To clear the image
• by removing the remaining silver halide
from emulsion
3. To fix the image
• no longer sensitive to light
4. To complete the process of
hardening of the film emulsion

53. CONSTITUENTS OF THE FIXING
SOLUTION
1. Solvent
2. Fixing agent
3. Acid
4. Hardener
5. Buffer
6. Preservative
7. Anti-sludging agent

54. FIXING SOLUTION
1. SOLVENT
• Water

55. FIXING SOLUTION
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)

56. FIXING SOLUTION
3. Acid:
• Prevents dichroic 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.
3. 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
• Optimizes hardener activity
• Sodium acetate is commonly used in
conjunction with acetic acid

57. FIXING SOLUTION
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.

58. WASHING
 Film must be washed well with water
after developing and fixing.
 Removes all thiosulfite complexes.
 Tap water is a satisfactory washing
medium. In a 90 seconds cycle about
15 seconds is allowed for the washing
stage, while in manual processing a
minimum of 10 minutes is advised.
 Incomplete wash causes retained hypo
to react with silver to form silver sulfide
acquiring brown colour.
Hypo + Silver

Silver Sulfide(brown) + Sodium sulfite

59. DRYING
• All the surface water and most of that
retained in the emulsion should be
removed.
• The drying medium is dry air of low
humidity, which accelerates the
evaporation process and reduces drying
time.
• Heated air can retain more moisture than
cold air and is therefore a more effective
drying medium. However, the excessive
use of heat may damage the film emulsion.
• Air temperatures between 40-650C are
commonly used.

60. TOTAL PROCESS OF DEVELOPING IN
SCHEMATIC REPRESENTATION

61. THE AUTOMATIC FILM PROCESSOR

62. 4 STEPS OF PROCESSING
• 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

63. SYSTEMS OF THE AUTOMATIC
PROCESSOR
1. The Film Feed Section
2. Transport System
3. Temperature Control System
4. Recirculation System
5. Replenishment System
6. Dryer System
7. Electrical System

64. 1. THE FILM FEED SECTION
• As a film is fed to the processor, so the
cycle of events listed below is initiated:
1. Drive motor energized (to turn the
rollers).
2. Safelight above feed tray extinguished.
3. Developer and fixer replenisher
pumped into tanks.
4. Drier heater energized.
5. Wash water flow rate boosted.
6. Film signal delay timer activated
(audible signal which will sound 1-3s
after the trailing edge of the film has
passed the entry rollers, to let the
operator know that the next film can be
fed to the processor).

65. 2. THE FILM TRANSPORT SECTION
• A system of rollers that moves the
film through the developer, fixer,
washing and drying sections of the
processor.
• Also acts as a squeegee action to
remove excess chemicals from the
film.

66. 2. THE FILM TRANSPORT SECTION
MAKE UP OF THE TRANSPORT SYSTEM
1. Entrance roller or detector roller
2. Vertical or Deep racks (transport
racks)
3. Crossover assembly
4. Squeegee assembly

67. 2. THE FILM TRANSPORT SECTION
ENTRANCE ROLLER OR DETECTOR ROLLER
• Entrance rollers grab film and draw
it into developer
• Entrance rollers separate slightly,
film passes between rollers
activating microswitch controlling
replenishment of chemicals
• When film is completely in
developer tank, bell ring or light
flicks on – safe to turn on light

68. 2. THE FILM TRANSPORT SECTION
VERTICAL OR DEEP RACKS (TRANSPORT RACKS)
• Moves film into and through solutions
and dryer
• Uses a turn around assembly at the
bottom of the tank to turn film
direction upward.

69. 2. THE FILM TRANSPORT SECTION
CROSSOVER ASSEMBLY
• Moves film from developer to fixer tank
and from the fixer to the wash tank
• Forces solutions from film back into the
tank it is coming from.

70. 2. THE FILM TRANSPORT SECTION
SQUEEGEE ASSEMBLY
• Moves the film from the wash tank to
the dryer
• Squeegee action removes excess water
from the film.

71. 2. THE FILM TRANSPORT SECTION
TRANSPORT SYSTEM (ROLLERS)
Turnaround
Entrance
Deep
Racks
Crossover
Squeegee
Dryer

72. WATER SYSTEM
• 2 functions:
• Washing the film
• Temperature control

73. WASHING
• Removes the last traces of
processing chemicals and prevents
fading or discoloration.
• This enables long term storage
capability

74. 3. TEMPERATURE CONTROL SYSTEM
Processing Temperatures
Developer 35° C
Fixer 35 ° C
Wash 32-35 ° C
Dryer 57 ° C
• Maintains developer, fixer & dryer
temperature

75. 4. CIRCULATION OR RECIRCULATION OR
FILTRATION SYSTEM
• Agitates developer solution
• Removes reaction particles by the
use of a filtration system
• Helps stabilize developer
temperature.
• Agitation keeps solutions in contact
with a heater element in the bottom
of the tank and prevents layering of
chemicals
• Heating element is controlled by a
thermostat

76. RECIRCULATION SYSTEM
• Controlled by recirculation pumps that
agitate solutions to keep them mixed
to maintain constant temperature
• Circulation of water required to wash
residual fixer (12 litres per minute)

77. 5. REPLENISHMENT SYSTEM
• Fixer & developer levels drop as films
processed
• System replaces lost chemicals
• Microswitch of entrance rollers starts
replenishment pump – stops when film
exits entrance rollers

78. 5. REPLENISHMENT SYSTEM
• Typical replenishment rates: 60-70 mls
of developer, and 100-110 ml of fixer
for every 14 inches of x-ray film (per 35
x 43cm crosswise film)

79. TYPES OF REPLENISHMENT
• Volume Replenishment
• A volume of chemicals are replaced for
each film that is processed.
• Flood Replenishment
• Periodically replenishes chemicals
regardless of the number of films
processed.

80. 6. DRYER SYSTEM
• Dries the film before its removal for
viewing
• Consists of blower, ventilation ducts,
vented dryer tubes & exhaust system
• Blower draws in air from room and
passes it over heating coils
• Heated air enters ventilation ducts &
dryer tubes & then blows over film
• Moist warm air vented

81. PROCESSING RATESProcessing Times
Developer 20-25secs
Fixer 20
Wash 20
Dryer 25-30
Travel
Time
10
Total Time 90 sec
• Amount of time it takes a film to go
through processor – ranges from 45-
210 seconds
• Film manufacturers determine
temperatures and replenishment rates

82. DAYLIGHT AUTOMATIC
PROCESSORS
• Enable film to be processed without
need for darkroom
• Special cassettes
• Increase in department efficiency, no
need for special darkroom staff
• Disadvantages
• Cost
• Mechanical breakdowns

83. AUTOMATIC FILM PROCESSING:
BENEFITS
• Compact size
• Faster
• Density and contrast is constant
• Time and temperature controlled
• Produces dry radiograph immediately

84. AUTOMATIC FILM PROCESSING:
DISADVANTAGES
• Artifacts caused by rollers.
• Expensive and requires maintenance.
• Manual processing required as a back
up in case of break down

85. MAINTENANCE
To maintain quality, attention needed in
3 areas:
1. Quality control
2. Processor cleanliness
3. Basic operation