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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
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3. 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 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 www.indiandentalacademy.com
5. 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
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6. Iodide ion
Bromide ion
Silver ion
Interstitial Ag ion
Sensitivity site
Silver bromide crystal in the emulsion of X-ray film contains mostly Ag+
and Br
-
ions with traces of I-
ions in a cubical crystal lattice. Free interstitial Ag+
ions and
areas of trace chemicals (Allyl thiocarbamide) serves as sensitivity sites before
exposure.
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7. During film processing, Selective
reduction of the exposed silver halide
crystals occurs
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8. Iodide ion
Bromide ion
Silver ion
Interstitial Ag ion
Bromine atom
Sensitivity site
Exposure of the crystal to an X-ray beam results in the release of electrons (e-
)
by interaction with Br ions. Br -
Br + e-
. Recoil electrons have
sufficient kinetic energy to move in crystal. Gets entrapped in sensitivity sites
and impart negative charge to this site
e-
Photon
Gelatin
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9. _
Iodide ion
Bromide ion
Silver ion
Interstitial Ag ion
Bromine atom
Sensitivity site
Free interstitial Ag+
ions are attracted towards the negatively charged
sensitivity site
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10. Iodide ion
Bromide ion
Silver ion
Interstitial Ag ion
Bromine atom
Silver atom
Sensitivity site
When interstitial Ag+
ions reach the sensitivity site, they acquire an
electron and become Ag atom (Ag+
+ e-
Ag). This Ag atoms
constitute the sensitivity.
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11. 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
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12. 2. WASHING
The film is washed in water to
remove residual developer
solution
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13. 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
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14. 4. WASHING
The film is washed through in
running water to remove residual
fixer solution
5. DRYING AND MOUNTING FOR VIEW
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15. Made up of black, white and grey areas
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17. 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
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18. 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
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19. 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
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20. 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 emulsionwww.indiandentalacademy.com
21. 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
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22. 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
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23. 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)
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24. 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
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25. ACETIC ACID OR SULPHURIC ACID
The purpose is to neutralizes the alkaline developers
Also produces necessary acidic environment for fixing
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26. SODIUM SULPHITE
To prevent chemical deterioration of the fixing
agent
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27. 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
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28. 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
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29. Primary function is to provide a completely darkened
environments, where x-ray film can handled and processed
to produces diagnostic radiograph
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30. Conveniently located
Of adequate size (16-20 sq feet)
Equipped with correct lighting arranged with ample
work space and storage
Temperature and humidity controlled
Room should be well ventilated
Light proof
Door should have locks to prevent accidental
opening
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31. 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
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32. 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
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33. 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
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34. 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
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35. 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)
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36. 1. MANUAL OR WET PROCESSING
2. AUTOMATIC PROCESSING
3. USING SELF DEVELOPING A FILM
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37. 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
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38. PROCESSING EQUIPMENTS
› Tanks containing various solutions
› Thermometers
› Immersion heater
› Accurate timer
› Film hangers
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40. 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
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41. 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.
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43. 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
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44. DISADVANTAGES
Strict maintenance and regular cleaning is
must
Equipment is expensive
Smalls machines cannot process large
extraoral film
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45. 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
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47. ADVANTAGES
No dark room or processing facilities are
needed
Time saving –the final radiograph is ready
in about 2-3 mints
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48. DISADVANTAGES
› Poor overall image quantity
› Image deteriorates rapidly with time
› No lead foil inside the film packet
› Film packet is very flexible 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
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Editor's Notes
AgBr crystal lattice contains Ag ion & Br ion arranged in cubical str. This type of perfect crys. is of no use radiographically and photo graphically.
Usually two effects are observed Photoelectric or Compton effect