The document provides information on processing x-ray film, including the steps to convert the latent image to a visible image. It discusses the chemical reactions that occur during development and fixing, as well as the components and purposes of developer and fixer solutions. The key steps in manual film processing are described as developing the film in developer solution for a specified time based on the temperature, rinsing, fixing, washing, and drying the film. Various equipment used in darkroom processing like tanks, timers, racks and hangers are also outlined.

1. Processing of x-ray film
Presented by: Shila Kandel
BDS 4th year
Presented to : Dr. Deepanshu Garg
Department of Oral medicine and
Radiology
College of Medical Sciences - TH

2. Contents
Introduction
Terminologies used in radiography
Types of image
Formation of latent image
Processing the exposed film
• Developing
• Rinsing
• Fixing
• Washing

3. Darkroom equipments
• Darkroom
• Safe-lighting
• Manual processing tanks
• Thermometer
• Timer
• Drying racks
• Film hangers
Manual processing method
Changing solutions
Automatic film processing
Management of radiographic wastes
Conclusion

4. Introduction
.
Film processing refers to the series of steps that converts the
latent image into the visible radiographic image.
A radiographic image is produced by the interaction of x-rays
with photographic emulsion on a film after passing through an
object.
The most frequently used image receptor used in dental
radiography is radiographic film.

5. Terminologies used in radiography
Radiopaque
These are the object when exposed to x-ray beam
,completely stop/absorb the x-rays and prevent them from
reaching the film ,as a result silver halide crystals do not get
exposed and hence conversion into metallic silver do not
occur.
The resultant image formed is radiopaque.

6. Radiolucent
It represents those structures through which all the x-ray
beam can pass and can reach the film to react with the silver
halide crystals converting them to metallic silver .
The resultant image formed is radiolucent

7. Types of image
Latent image
Latent image is defined as an invisible image that is produced
in film emulsion by light or x-ray.
Final image
A final image or visible image can be described as a two-
dimensional picture which is made up of a variety of black ,
white , and gray superimposed shadow.
A latent image is converted into a visible record by series of
chemical reactions which is known as processing.

8. Formation of latent image
• When a beam of photons exits an object and exposes an x-
ray film , it chemically changes the photosensitive silver
halide crystals in the film emulsion.
• These chemically altered silver bromide crystals constitute
the latent (invisible) image on the film.

9. • Before exposure ,film emulsion consists of photosensitive
crystals containing primarily silver bromide suspended in a
vehicle and layered on a thin sheet of transparent plastic
base.
• These silver halide crystals also contain a few free silver
ions (interstitial silver ions ) and trace amounts of sulfur
compounds bound to the surface of the crystals. The sulfur
compounds play a crucial role in image formation.

10. • Along with physical irregularities in the crystal produced by
iodide ions, sulfur compounds create sensitivity sites, the
sites in the crystal that are sensitive to radiation.
• Each crystal has many sensitive sites, which begin the
process of image formation by trapping the electrons
generated when the emulsion is irradiated.

11. • When the silver halide crystals are irradiated , x-ray
photons release electrons from the bromide ions.
• The free electron move through the crystal until they reach
a sensitivity site, where they become trapped and impart a
negative charge to the site.
• The negatively charged sensitivity site attracts positively
charged free interstitial silver ions.

12. • When a silver ion reaches the negatively charged sensitivity
site, it is reduced and forms a neutral atom of metallic
silver.
• The sites containing these neutral silver atoms are now
called latent image sites.
• This process occurs numerous times within a crystal ,
• The overall distribution of crystals with latent image sites in
a film after exposure constitutes the latent image.

13. (A) Sensitivity site (B) Interaction of photon with silver halide crystal (C) Formation of
negatively charged photoelectron trapped at sensitivity site (D) Attraction of positively charged
silver ion towards the negatively charged sensitivity site with formation of metallic silver
resulting in formation of latent image

14. • Processing the exposed film in developer and fixer
converts the latent image into visible radiographic image.

15. Processing the exposed film
•Processing
It is the term used to describe the sequence of events
required to convert the invisible latent image contained in
the sensitized film emulsion into the visible permanent
radiographic image.

16. • Film processing involves the following procedures :
Immerse exposed film in developer
Rinse developer off the film in water bath
Immerse film in fixer
Wash film in water bath to remove fixer
Dry film and mount for viewing

17. Sequence of steps in processing
Steps Time(approximate) Purpose
Development 4.5-5 minutes Convert latent image to visible image
Rinsing 30 seconds Removal of excess chemical
Fixation 10 minutes Removal of unexposed Ag halide from
emulsion and hardening
Washing 15 minutes Removal of excess chemicals
Drying 30 minutes Removal of water and preparation of
radiograph for viewing

18. Development
• A chemical solution developer is used in the development
process.
• Developer chemically reduces the exposed silver halide
crystals into metallic silver grains.
• To produce a diagnostic image, this reduction process must
be restricted to crystals containing latent image sites.
• To accomplish this, reducing agents used as developers are
catalyzed by neutral silver atom at the latent image sites.

19. • Individual crystals are developed completely or not at all
during the recommended developing times.
• Areas with many exposed crystals are darker because of
their higher concentration of black metallic silver grains
after development

20. • When an exposed film is developed, developer initially has
no visible effect. After this initial phase, density increases,
rapidly at first and then more slowly.
• Eventually, all exposed crystals develop and developing
agents starts to reduce the unexposed crystals.
• The development of unexposed crystals result in chemical
fog on the film.

21. fig

22. • The developing solution contains four components all
dissolved in water:
Developer
Activator
Preservative
Restrainer

23.  Developer
• Reducing agent
Composition:
• Pyarazolidine-type compound, usually Phenidone (1-phenyl-
3-pyrazolidine)
• Hydroquinone (paradihydroxy benzene)

24. Function
• Phenidone serves as the first electron donor that converts
silver ions to metallic silver at the latent image site. This
electron transfer generates the oxidized form of
Phenidone.
• Hydroquinone provides an electron to reduce the oxidized
Phenidone back to its original active state so that it can
continue to reduce silver halide grains to metallic silver.

25.  Activator
• Soapy in touch
Composition
• Sodium or potassium hydroxide
• Sodium bicarbonate

26. Function
• The developers are active only at alkaline pH values.It
maintains alkalinity (pH above 11).
• Sodium bicarbonate acts as buffer.
• Activator also causes gelatin to swell for rapid diffusion of
developer into emulsion.

27.  Preservative
Composition
• Sodium sulfite
Function
• Antioxidant- protects the developers from oxidation by
atmospheric oxygen and thus increasing the shelf life.
• Combines with the brown oxidized developer to produce a
colorless soluble compound.

28.  Restrainer
Composition
• Bromide, usually potassium bromide
• Benzotriazole
Function
• Depress reduction of both exposed and unexposed crystals
but more effective in depressing the reduction of
unexposed crystals – Antifog agent.
• Improves contrast.

29. Developer replenisher
In the normal course of film processing,
Phenidone and hydroquinone are consumed from the
solution.
Bromide ions and other by-products are released into
solution.
Developer solution gets inactivated by exposure to
oxygen.
.

30. • These actions produces a seasoned solution.
• Hence the developing solution of both manual and
automatic developers should be replenished with fresh
solution daily to prolong the life of seasoned solution.
• The recommended amount to be added daily is 8 ounces of
fresh developer per gallon of developing solution. This
assumes the development of an average of 30 periapical or
5 panoramic films per day

31. Rinsing
• A continuous, gentle rinsing for 30 seconds in water is
necessary after developing.
• This rinsing process is typical for manual processing but is
not used with automatic processing.
Purpose :
• To dilute the developer and slow down the development
process.
• To remove alkali activator thus preventing neutralization of
acid fixer.

32. Fixing
• A chemical solution fixer is used in the fixing process.
Purpose
• To dissolve and remove the undeveloped silver halide
crystals from the emulsion as the presence of undeveloped
crystals causes the film to be dark and non diagnostic.
• To harden and shrink film emulsion during the process.

33. Fixing solution also contains four components, all dissolved
in water.
Clearing agent
Acidifier
Preservative
Hardener

34.  Clearing agent
• After development the film emulsion must be cleared by
dissolving and removing the unexposed silver halide.
Composition
• Aqueous solution of ammonium thiosulfate (hypo).
Function
• Dissolves and removes the unexposed silver halide grains.
• Forms a stable, water soluble complexes with silver ions
(silver thiosulfate complex), which can be subsequently
washed out of the film.

35.  Acidifier
Composition
• Acetic acid buffer system (pH 4 - 4.5).
Function
• It provides necessary acidic medium for diffusion of
thiosulfate into the emulsion and maintains adequate pH.
• Inactivates any residual developing agents in the film
emulsion, hence blocks the further development of any
unexposed crystals.

36.  Preservative
Composition
• Ammonium sulfite
Function
• Prevents oxidation of thiosulfate clearing agent, which is
unstable in the acidic environment of the fixing solution.
• Binds with any colored oxidized developer carried over into
the fixing solution and effectively removes it from the
solution, thus preventing oxidized developer from staining
the film.

37.  Hardener
Composition
• Aluminium sulfate
Function
• Complexes with gelatin during fixing and prevents damage to
the gelatin during subsequent handling.
• Reduces the swelling of emulsion.
• Lessens mechanical damage to the emulsion.
• Limits water absorption.
• Shortens drying time.

38. Washing
• After fixing, the processed film is washed in a sufficient
flow of water for an adequate time to ensure removal of all
thiosulfate ions and silver thiosulfate complexes.
• Washing efficiency declines rapidly when water
temperature decreases to less than 6o degree F.
• Any silver compound or thiosulfate that remains because
of improper washing discolours and causes stains, which
are most apparent in the radiopaque areas.

39. Drying
• Films are dried with the help of x-ray dryer in a dust free
area.
• While drying, films should not touch each other to avoid
sticking of the films.

40. Darkroom equipment requirements
Darkroom
Safe-lighting
Manual processing tanks
Thermometer
Timer
Drying racks
Film hangers

41. Darkroom
A well planned dark room makes the processing easier,
which should be of at least 4feet×5 feet (1.2m×1.5 m).
Characteristics of dark room:
Lightproof
The door should have a lock to prevent accidental
opening, which might allow an expected flood of light
that can ruin opened films.

42. • Well ventilated for the comfort of those working in the
area and to exhaust the heat from the dryer and moisture
from the drying films.
• Also, a comfortable room temperature helps maintain
optimal conditions for developing, fixing, and washing
solutions.

43. Controlled temperature and humidity to prevent film
damage.
Room temperature of 70 degree F is recommended ; if
exceeds 90 degree F, film fog results.
Humidity level of between 50 – 70% should be maintained;
when too high, film emulsion does not dry; when too low,
static electricity becomes a problem and causes film artifacts.

44. Fig : Darkroom

45. Safe lighting
• The processing room should have both white illumination
and safe lighting.
• Safe lighting is special kind of lighting of relatively low-
intensity illumination of long wavelength (red) that does
not rapidly affect open film but permits one to see well
enough to work in the area.
• To minimize the fogging effect of prolonged exposure, the
safelight should have a 15 watt bulb and should be
mounted at least 4 feet above the surface where opened
films are handled.

46. • The red GBX-2 filter is recommended as a safelight in the
darkroom because this filter transmits light only at the red
end of the spectrum .
• Film handling should be limited between 5-8 minutes
because film emulsion shows some sensitivity to light from
a safelight with prolonged exposure.

48. Manual processing tanks
• Practical size of about 20cm×25 cm (8×10 inches).
• The tank should have hot and cold running water and a
means of maintaining the temperature between 60 and 70
degree F.
• Consists of 1 master tank and 2 insert tank.
• Should be made of stainless steel which does not react
with the processing solutions and is easy to clean.

49. Fig: Processing tank

50. Master tank
Filled with circulating water.
Should have a cover to reduce oxidation of the processing
solutions, protect the developing film from accidental
exposure to light and minimize evaporation of the
processing solutions.

51. Insert tank
Two, removable tanks
Holds 3.8 L (1 gallon) of developer or fixer, placed within
the outer, larger master tank.
Developer solution is placed in the insert tank on the left
side and fixer solution in the insert tank on the right side of
the master tank.
Water in master tank separates the two insert tanks.

52. Thermometer
• Used to determine the temperature of developing, fixing
and washing solutions.
• It can be left in the water circulating through master tank
to monitor its temperature.
• Thermometer used may contain alcohol or metal but they
should not contain mercury because they could break and
contaminate the processor or solutions.

53. Timer
• The x-ray film must be exposed to the processing chemicals
for specific intervals.
• An interval timer is indispensable for controlling
development and fixation times.

54. Drying racks
• Two or three drying racks can be mounted on a convenient
wall for film hangers.
• Drip trays are placed underneath the racks to catch water
that may run off the wet films.
• An electric fan can be used to circulate the air and speed
drying the films but it should not be pointed directly at the
films.
• Also, cabinet dryers are available that circulate warm air
around the film and accelerate drying.

55. Film hangers
• Also known as processing hangers.
• Made up of stainless steel.
• Equipped with clips used to hold films during processing.
• Available in various sizes and can hold upto 20 intraoral
films.

56. Fig : Film hangers

57. Processing methods
1.Manual processing method
Time-temperature method
Visual method
Rapid processing method
2. Automatic method
Monobath method
Self developing films

58. Manual processing method:
Sequence of steps in manual processing:
Time-temperature method
Replenish solutions
Before processing check the solution level of developer and
fixer. If the solution level is low, add fresh solution.

59. Stir solutions
Use stirring rod or paddle
This mixes chemicals and regularizes the temperature of
the solution.
Check the temperature of the developer solution. The
optimal temperature for the developer is between 65°F to
70°F.

60. Mount films on hanger
Turn on the safe light
Remove the exposed film from its lightproof packet
Hold the film only from their edges
Clip the bare film to the hanger clip (1 film to a single clip)

61. Solution Temperature (in degree F) Developing time (in minute)
65°F 6 minute
68°F 5 minute
70°F 4.5 minute
72°F 4 minute
76°F 3 minute
80°F 2.5 minute
Set timer
Based on temperature of developer solution and the
instruction of manufacturer, set the timer. A time temperature
chart is used to determine the time

62. Develop
Immerse the film hangers with the films into developer
solution.
Film must not contact one another or the sides of the
processing tanks during development.
Activate the timer, agitate mildly for 5 seconds to sweep air
bubbles off the film to allow uniform contrast of developer.

63. Rinse
Rinse the film by placing in the circulating water for 30
seconds.
Fix
Immerse the film hanger with film in the fixer solution for 10
minutes. Gently agitate it for 5 seconds every 30 seconds.
This eliminates air bubbles and brings fresh fixer in touch
with emulsion.

64. Wash and dry
The films are then placed in running water for at least 10
minutes
Dry the film in circulating, moderately warm air.
If heated using drying cabinet, temperature should not
exceed 120°F.
Remove the dry radiograph from the film hanger and
radiograph is now ready for examining.

65. Visual method
• In this method the exposed X ray film is immersed in
developing solution for about 10 seconds and then
removed and observed in safe light.
• If adequate image have been obtained then it is put for
rinsing otherwise reinserted in developing solution till
adequate image is obtained.
•Disadvantage: Objective in nature and doesn’t give
consistent quality.

66. Rapid processing method
• Rapid processing solutions typically develop films in 15
seconds and fix them in 15 seconds at room temperature.
• They have the same general formulation as conventional
processing solutions but often contain a higher
concentration of hydroquinone.
• They also have a more alkaline pH than conventional
solutions, which causes the emulsion to swell more, thus
providing greater access to developer.

67. • Although the resultant images may be satisfactory, they
often do not achieve the same degree of contrast as films
processed conventionally, and they may discolor over time
if not fully washed.
• After viewing, rapidly processed films are placed in
conventional fixing solution for 4 minutes and washed for
10 minutes. This improves the contrast and helps keep
them stable in storage.

68. Changing solutions
• Under average conditions solutions may provide service of
3-4 weeks, as all processing solutions may deteriorate due
to:
i. Continuous use
ii. Exposure to air
iii.Eventual build up of reaction products
• Loss of image contrast and density indicates time to
change processing solutions.

69. Automatic film processing
• Step in automatic processing are more or less same like the
manual processing with exception of rinsing , between
developing and fixing.
• This stage is omitted because excess developer is either
drained or squeezed.

70. • Although automatic processing has numerous advantages,
the most important is the time saved.
• Depending on the equipment and the temperature of
operation, an automatic processor requires only 4-6
minutes to develop, fix, wash and dry.

71. • Many dental automatic processors have a light-shielded
(daylight loading) compartment in which the operator can
unwrap films and feed them into the machine, without
working in the darkroom.
• However , special care must be taken to maintain infection
control when using these daylight-loading compartments.

72. • Another attractive feature of the automatic system is that
the density and contrast of the radiographs tend to be
consistent.
• However, because of the higher temperature of the
developer and the artifacts caused by rollers, the quality of
films processed automatically often is not as high as that of
those carefully developed manually.

73. Mechanism
• Automatic processing cycle is same as manual processing
except that the rollers squeeze off any excessive
developing solution before passing the fill on the fixer ,thus
eliminating the need for the washing between these two
steps.

74. • Automatic processors have an in-line arrangement typically
consisting of a transport mechanism that picks up the
unwrapped film and passes it through the developing,
fixing, washing, and drying sections .

75. Fig : Components of the automatic
processor

76. • There are series of rollers which transport the films
through various sections for each step in the operation.
• These sections are designed and positioned so that the
film crosses over from one roller to the next, the operator
may remove them independently for soaking, cleaning, and
repairing.

77. Functions of rollers
• Moving the film through the developing solutions.
• Agitation of solution which contributes to the uniformity of
processing.
• In the developer, fixer, and water tanks the rollers press on
the film emulsion, forcing some solution out of the
emulsion. The emulsions rapidly fill again with solution,
thus promoting solution exchange.
• Minimizes carryover of developer into the fixer tank.

78. • The chemical compositions of the developer and fixer are
modified to operate at higher temperatures than those
used for manual processing and to meet the more rapid
development, fixing, washing, and drying requirements of
automatic processing.
• The fixer has an additional hardener that helps the
emulsion withstand the rigors of the transport system.
• Poor quality fixers containing no hardener produce more
film artifacts.

79. • Successful operation of an automatic processor requires
standardized procedures and regular maintainance.
• The processor and surrounding area should be kept clean
so that no chemicals contaminate hands or films.
• The solution level and temperature should be checked each
morning.
• Hands should be dry while handling films.

80. Self developing films
• Alternative to manual processing.
• The x ray film is present in sachet containing developer and
fixer .
• Following exposure the developer can be pulled, releasing
developer solution which is milked down toward the film
and flow around it.

81. • After 15 seconds fixer tab is pulled to release the fixer
solution which similarly baths down the film.
• After fixing the used chemicals are discarded and film is
rinsed thoroughly under running water for ten minutes.

83. Advantages
• No darkroom or processing equipments are required.
• Final radiograph is ready in about a minute and hence saves time.

84. Disadvantages
• Resultant image has poor quality.
• Image deteriorates rapidly with time as fixing is inadequate
• As there is no lead foil inside film packet patient receives
more radiation dose.
• As these film packets are very flexible and they bend easily,
these films are difficult to use with positioning holders.

85. Monobath method
• In this method developer and fixer are combined in one
solution .
• Fixer is alkaline and does not neutralize the developer.
• It is injected into special waterproof film packet and the
film is developed by rubbing film packet.
• There is no need of darkroom.
• It is advantageous for quick spot diagnosis and for root
canal treatment.

86. Management of radiographic wastes
• Although dental radiograph waste constitutes only a small
potential hazard it should be discarded properly.
• The primary ingredient of concern in processing solution is
the dissolved silver found in used fixer.
• Another material is lead foil found in film packets.
• Dental offices should consider using companies licenced to
pick up waste materials.

87. Conclusion
• Correct processing of radiographs is a key factor in good
radiography. Correct processing is not an expensive
procedure; however an understanding of basic
fundamentals is required to avoid unnecessary errors that
may destroy the detail of radiographs. So the proper
technique for film processing should be employed to
produce a good diagnostic radiograph.

88. References
• ORAL RADIOLOGY Principles and Interpretation, Staurt C.
White , Michael J. Pharoah
• Oral and Maxillofacial Radiology: A Diagnostic Approach
David MacDonald
• Fundamentals of oral and maxillofacial radiology, Hubar,
Jack Sean

89. Thank you