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1. DARK ROOM PROCEDURES
COMPOSITION OF DEVELOPER & FIXER,MANNUAL &
AUTOMATIC PROCESSING,SAFELIGHTING AND
STORAGE OF FILMS
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2. Film processing
Composition of developer solution
Composition of fixer solution
Dark room equipments
Safe lighting
Practical processing methods
Manual
Automatic
Self Developing Film
Storage of films

3. FILM PROCESSING
The sequence of events required to convert the
invisible latent image, contained in the sensitized film
emulsion, into the visible, permanent radiographic
image
The purpose of film processing is two fold
To convert the latent a visible image (invisible)
image on the film into a visible image
To preserve the visible image that it is permanent
and dose not disappear from the dental radiograph

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5. Film Processing Fundamentals
Silver halide crystals in the emulsion absorb
x-radiation during x-ray exposure and store
the energy from the radiation, which forms a
pattern and creates an invisible image within
emulsion on the exposed film. This is called
as Latent Image

6. From Latent To Visible Image
During film processing, Selective reduction
of the exposed silver halide crystals occurs
SELECTIVE REDUCTION
Is the reduction of the energized, exposed
silver halide crystals into black metallic
silver, while the unenergized unexposed
silver halide crystals are removed from the
film
The latent image is made visible image
through processing procedure

7. STEPS
1.IMMERSION OF EXPOSED FILM IN DEVELOPER
Developer distinguishes between exposed
and unexposed silver halide crystals
Initiates chemical reaction that reduces the
exposed silver halide crystals into the black
metallic silver and creates dark or black
areas on the film.
At the same time, the unexposed silver
halide crystals remain virtually unaffected by
the developer solution

8. 2. WASHING
The film is washed in water to
remove residual developer
solution

9. 3. IMMERSION IN FIXING SOLUTION
Fixer removes the unexposed silver
halide crystals and creates white or
clear areas on the radiograph
meanwhile the black metallic silver
are not removed and remains on the
film

10. 4. WASHING
The film is washed through in
running water to remove residual
fixer solution
5. DRYING AND MOUNTING FOR VIEW

11. THE VISIBLE IMAGE
Made up of black, white and grey areas
RADIOLUCENT
Radiolucent structure is one that readily
permits the passage of the x-ray beam and
allows more x-rays to reach the film
If more x-ray reach the film , more silver
halide crystals in the film emulsions are
exposed and energized, resulting in
increased deposit of black metallic silver,
through appear more black or radiolucent

12. RADIOOPAQUE
Radioopaque structure is the one that
resists the passage of the x-ray beam and
restricts or limits the amount of x-rays
that reach the film
If no x-ray reach the film, no silver halide
crystals are exposed, and no deposits of
black metallic silver ions are seen
The unexposed silver halides crystals are
removed during processing, therefore
structure are white or radioopaque

13. PROCEDURE

14. DEVELOPING SOLUTION
Developer – reducing agent
- purpose is to convert exposed silver
halide crystals in to metallic silver grains
HYDROQUINONE – PARAHYDROXY
BENZENE
Generates the black tones and
Sharp contrast of radiographic image
Temperature sensitive
Inactive below 60o
F
Very active above 80o
F
Optimal temperature is 68o
F

15. ELON- MONOMETHYL PARA AMINOPHENOL
SULPHATE
Generates many shades of grey
Not temperature sensitive
Widely used in combination
If used individually
ELON - produce a film that appeared gray
with indistinct contrast
HYDROQUINONE – produce a film that
appeared black and white

16. PRESERVATIVE
SODIUM SULPHITE
antioxidant
Has greater affinity for oxygen and
Protect the developer from being oxidized
by atmospheric oxygen
Also combines with the brown oxidized
developer to produces a colors
Helps extend the useful life of
hydroquinone and elon

17. ACCELERATOR / ACTIVATOR
The developer agent are active only in alkaline –
high pH – medium (pH - 11)
To maintain this condition, they contain alkali
which serves as an activator (accelerator)
SODIUM CARBONATE, SODIUM HYDROXIDE
AND SOMETIMES SODIUM METABORATE,
SODIUM TETRABORATE
When developing agents reduces silver halide
granules H+ produced which causes fall in pH
and depress the reduction of silver that is slow
developing process, therefore activator is used to
fasten the process
Also serve to soften the gelatin so that developer
agent can diffuse more rapidly into this emulsion

18. RESTRAINER
POTASSIUM BROMIDE
Added because bromide is a product of
reduction of silver halide crystals and added
bromide serves to depress the reduction by
common ion effect
Although it dose depress the reduction of
both the exposed and unexposed crystals, it
is much more effective in depressing the
reduction of unexposed crystals, so as a
consequence acts as an ANTIFOG AGENT

19. RINSING
After developing film is to be rinsed in water
for 15-20 seconds before they are placed in
the fixer
This rinse will dilute the development
process
Also removes alkali activator thus preventing
neutralization of acid fixer

20. FIXING SOLUTION
Function is to remove the unexposed silver
halide crystals from the emulsion
Presence of unexposed crystal cause the film
to be opaque if not removed will cause the
film to be obscured and non diagnostic
The other function of fixer is to hardened the
emulsion (on the film)

21. CLEARING AGENT
Fixing agent
Aqueous solution of SODIUM THIOSULPHATE
or AMMONIUM THIO SULPHATE
Function is to remove the unexposed and
underdeveloped silver halide crystals from
the film emulsion
The chemicals clears the film so that the
black image produced by the developer
become readily distinguished

22. ACIDIFIER
ACETIC ACID OR SULPHURIC ACID
The purpose is to neutralizes the alkaline
developers
Also produces necessary acidic
environment for fixing

23. PRESERVATIVE
SODIUM SULPHITE
To prevent chemical deterioration of the
fixing agent

24. HARDENING AGENT
POTASSIUM ALUM
To harden and shrink the gelatin in the
film emulsion after it has been softened by
the accelerator in developer solution
Shortens the drying time

25. WASHING
Should be washed in a sufficient flow of
water for an adequate time to assure
removed of all processing solution
Washing efficiency is influenced by water
temperature and decreases rapidly below 60o
F

26. DARK ROOM EQUIPMENTS
Primary function is to provide a completely
darkened environments, where x-ray film can
handled and processed to produces
diagnostic radiograph

27. REQUIREMENTS
Conveniently located
Of adequate size (16-20 sq feet)
Equipped with correct lighting arranged with
ample work apace and storage
Temperature and humidity controlled
Room should be well ventilated
Light proof
Door should have locks to prevent accidental
opening

28. LOCATION SIZE
Location must be convenient and near to the
area where x-ray units are installed
Large enough to accommodate film
processing equipments and to allow ample
working space
Measured at least 16-20 square feet

29. LIGHTING
Room must be completely dark and must
exclude all visible white light
LIGHT TIGHT – completely dark room
LIGHT LEAKS –light leaks into dark room
- May cause film fog
Tow types of lighting
Room lighting
Safe lighting

30. ROOM LIGHTING
Incandescent room lighting is required for
procedure not associated with the act of
processing film.
Required for other tasks like cleaning,
stocking materials mixing chemicals

31. SAFELIGHTING
Special type of light that is used to provide
illumination in the dark room during
processing
Low intensity light composed of long wave
lengths in the red –orange portion of visible
light spectrum
Dose not rapidly affect on open film ,but
permits one to see well enough to work
Typically consist of a lamp equipped with a
low wattage (71
/2 or 16w) and a safe light
fitters

32. Safe light filter removes short wavelength in
blue green portion of visible light spectrum
that are responsible for exposure or
damaging the film
Safe light filter permits passage of light in the
red orange range
Most films hare reduced sensitivity to this
red orange range and are not affected by
minimal exposure
It is necessary to maintain an adeqquate
safelight film handling time to a
Minimum Distance – 4 feet / 1.2 meters
Time 2-3 minutes (Handling)

33. PRACTICAL PROCESSING METHODS
1. MANUAL OR WET PROCESSING
2. AUTOMATIC PROCESSING
3. USING SELF DEVELOPING A FILM

34. 1. MANUAL OR WET PROCESSING
Carried out in dark rooms
General requirements are
Absolute light tightness
Adequate working space
Adequate ventilation
Adequate washing facilities
Adequate film storage facilities
Safe light - 1.2 m from work
25 w bulbs / filters

35. PROCESSING EQUIPMENTS
Tanks containing various solutions
Thermometers
Immersion heater
Accurate timer
Film hangers

36. PROCESSING TANK

37. PROCESSING CYCLE
The exposed film packet is unwrapped
and film clipped on to a hanger
The film is immersed in developer and
agitated several times in the solution to
remove air bubbles and left for 5 min
at 20o
C.
The residual developer is rinsed off in
water for 10 seconds
The films is immersed in fixer for
about 8-10 min
The film is allowed to dry in a just free
atmosphere

38. 2. AUTOMATIC PROCESSING
Processing is carried out automatically by a
machine
Several automatic processors are available
which are designed to carryout the film
through the complete cycle usually by a
system of rollers
The cycle same as for manual processing
except that the rollers squeeze off any
excess developing solution before passing
the film onto the fixer, eliminating the
need for the water wash between these two
solutions.

39. AUTOMATIC PROCESSING
DIAGRAMMATIC REPRESENTATION

40. ADVANTAGES
Time saving –Dry films are produced in
5 min
Need of dark room is eliminated
Controlled standardized processing
conditions are easy to maintain
Chemicals can be replenished automatically
by some mechanics

41. DISADVANTAGES
Strict maintenance and regular cleaning
is must
Equipment is expensive
Smalls machines cannot process large
extraoral film

42. SELF DEVELOPING FILMS
An alternative to manual processing
X-ray film is presented in a special sachet
containing developer and fixer
Following exposure, developer tab is pulled,
releasing developer solution which milked down
towards the film and messaged around it
After 15 seconds the fixer tab is pulled , to
release fixer which is also milked down
After fixing the used chemical are discharged ,
them film is rinsed in water for 10 min and
dried

43. SELF DEVELOPING FILM

44. ADVANTAGES
No dark room or processing facilities are
needed
Time saving –the final radiograph is ready
in about 2-3 mints

45. DISADVANTAGES
Poor overall image quantity
Image deteriorates rapidly with time
No lead foil inside the film packet
Film packet is very flexiblee and easily bent
Difficult to use in positioning holder
Relatively expensive
A rigid, radiographs plastic backing support
tray can be made, which helps to reduce the
problems of flexibility and lack of lead hold

46. STORAGE OF FILMS
Film is adversely affected by heat humidity
and radiation.
Following precaution must be taken to
protect the films
1.To prevent fog, unexposed, unprocessed
film must be kept in a cool, dry place
2.The optimum relative temperature for
storage ranges from 50-70o
F

47. 3.The optimum relative humidity level ranges
from 30-50 %
4.Storage areas should be adequately sheilded
from source of radiations
5.Lead lined or radiation resistant film
dispensers and storage boxes are ideal
6.Each box or container of film is clearly
labelled with an expiration date
7.The “FIRST IN, FIRST-OUT” rule of
thumb should be applied to film use
- The oldest film in stock should always be
used before any new film