GOOD MORNING
GOOD MORNI
NG
SEMINAR
PROCESSING
YASMIN MOIDIN
2008 BATCH
AL AZHAR DENTAL COLLEGE
THODUPUZHA
DEFINITION
Processing is a collective title given to a series
of operations carried out in the dark room, which
effect chemical changes in the exposed
radiographic film, making the invisible latent
image, contained in the sensitized film emulsion
into a visible, permanent radiographic image
LATENT IMAGE
A radiographic film is a recording medium used
in dental radiography. When this film is exposed
to the information carrying beam of photons
exiting an object, the photosensitive silver halide
crystals in the film emulsion interact with these
photons and are chemically changed. These
chemically altered crystals are said to constitute
the latent (invisible) image of the film
These chemical changes in the crystals increase
the liability of crystals to chemical action of the
developing process that converts the latent
image into manifest (visible) image
FORMATION OF THE LATENT IMAGE
The film emulsion is made of silver bromide
crystals and silver iodide crystals that is
precipitated in gelatin and layered on a thin
sheet of transparent base
The silver halide crystals are chemically
sensitized by the presence of sulphur compounds
which cause physical irregularities in the crystal
produced by iodide ions , and these are called
latent image sites
The function of latent image site is to begin the
process of image formation by trapping the
electrons generated when the emulsion is
irradiated
When the silver halide crystals are irradiated ,
the electron released changes bromide ion into
bromine atom. This will produce kinetic energy
with which it moves in the crystal and strikes the
image site imparting a negative charge to that
region
Free positively charged interstitial silver ions are
attached to the negative latent image site and
neutralize the image site with the result that an
atom of metallic silver is deposited at the site.
After exposure e of a film to radiation, the
aggregate of silver atoms at the latent image
sites, comprises the latent image. It is the
metallic silver at each latent image site that
catalyses the development of the halide crystal
in which it formed and renders the crystal
sensitive to development and image formation
FILM PROCESSING
The primary action of processing solution is to
convert the crystals with latent image into black
metallic silver grains that can be visualized and
to remove the unexposed silver bromide crystals
Latent image is made visible through the
following processing procedures
The film is placed in a chemical known as the
developing solution for a specific amount of time
and at a specific temperature
Developer distinguishes between unexposed
and exposed silver halide crystals
Reduces exposed silver halide crystals into
metallic silver and creates black areas in the
radiograph
Unexposed remains unaffected
Rinsed in water to remove remaining
developer solution
Next , the film is placed in a special chemical
known as fixer solution
Fixer solution removes the unexposed silver
halide crystals and creates white or clear areas
on dental radiograph
Following the fixing process , the film is washed
in water to remove any remaining traces of
chemical solution
Drying : after rinsing the film , it is dried. The
film is placed in a drying cabinet or hung up in
a well ventilated dust free room
FILM PROCESSING SOLUTIONS
These may be obtained in the following forms :
Powder
Ready to use liquid
Liquid concentrate
The special chemical solutions are :
Developer solution
Fixing solution
DEVELOPER SOLUTION
REDUCING AGENTS
Hydroquinone : - It is concerned with the production
of high contrast in the radiograph
Metol or Elon :- It helps develop the shades of gray
on the film and brings out the details
When used together hydroquinone and metol produce
an adequate contrast and detail, at 20 degree C
Metol phenidone :- this serves as the first electron
donor that converts silver ions to metallic silver at the
latent image site
PRESERVATIVE
Sodium sulphite :- this inhibits the
tendency of the developing agent to combine
with the oxygen dissolved in water or in the
air. Therefore acts as a preservative and
keeps the solution in an usable condition for
several weeks
Oxidation of the developing agents forms
colored substances which would stain the film
and add to the film fog
ACTIVATOR
Potassium carbonate or sodium carbonate :- provide and maintain the degree of alkalinity in which the developing agent can function. Also known as accelerator
RESTRAINER
Potassium bromide :- it slows down the reduction action of the developing agents
HARDENER
Glutaraldehyde :- to prevent the emulsion
from softening and sticking to the rollers
FUNGICIDE :- to prevent bacterial growth
BUFFER :- to maintain p H
SOLVENT :- water
FIXING SOLUTION
CLEARING AGENT
Ammonium thiosulphate :- removes silver bromide
PRESERVATIVE
Sodium sulphite :- prevents oxidation of clearing agent
ACIDIFIER
Acetic acid :- keep the fixer pH constant
HARDENER
Aluminum chloride :- form complex with gelatin
SOLVENT
Water
REDUCTION
A photographic reducer contains an oxidizing
agent, potassium ferricyanide which oxidizes
the silver to silver ferrocyanide , which in
turn is dissolved by the solution of sodium
thiosulphate. This is known as the farmer’s
reducer and consists of two solutions
Solution A : potassium ferricyanide 75 grams
Solution B : sodium thiosulphate crystals 240
grams
CHEMICAL INTENSIFICATION OF
RADIOGRAPHS
In – 4 chromium intensifier
In -5 silver intensifier
Copper iodide intensifying solution
XR -10 intensifying solution
Line toner solution
THE DARKROOM
Function :- provide a completely darkened
environment where the X-ray film can be
handled and processed to produce a
diagnostic image in an efficient, precise and
standardized procedure
GENERAL LAYOUT
Size of the darkroom :- 3 feet x 3 feet for an
individual dentist and 16 to 20 square feet
for a group
Size will vary depending on :-
Volume of radiographs processed
Number of persons using darkroom
Type of processing equipments
Space required for duplication of film and
storage
REQUIREMENTS OF DARK ROOM
Sufficient space
Should be 3 feet away from processing tank
Should be ventilated
Temperature of 70 degree and humidity of
50-70% is maintained
Should include hot and cold running water
ILLUMINATION
Complete darkness and must exclude all visible
light- light tight or light proof is accomplished
by :- exclusion of all external lights
use of light tight door
Use of both white light and safe light
White light illumination is required during
cleaning tanks and preparing the solutions
SAFE LIGHT ILLUMINATION
Should be of low intensity
3 zones :- i. dimmest zoneii. medium zoneiii. bright zone
Excessive exposure of film to safe light
illumination will result in fog, 3 factors :-
Type of filters:-
Moralite filter
Wratten series 6 B filters
Red GBX-2 safe light filter
Intensity of illumination :-
Wattage of bulb should be 7 ½ to 15 watts
The distance of the safe light above the work
area should be 4 feet
Time of exposure :- more the film is exposed
to safe light, more chance of film fogging
TESTS FOR CHECKING UNSAFE
ILLUMINATION
Coin test / penny test :- evaluate fogging
caused by inappropriate safe light conditions
Check for light leak
PROCESSING EQUIPMENT
MANUAL / HAND / TANK PROCESSING
Simplest and most efficient procedure for developing with
accurate control
Processing tank consists of :-
Master tank
Insert tank
Tanks are made of :-
Stainless steel ( ISI type 316 SS with 23 % Mo )
Enamel
Earthenware
Hard rubber
OTHER REQUIREMENTS INCLUDE :
Thermometer
Timer
Drying racks
Stirring rod or stirring paddle
Plastic apron
METHODS OF PROCESSING
Manual method
Time temperature method
Visual method
Rapid processing method
Automatic method
Monobath method
Day light method
Digitized processing method
Self developing method
TIME TEMPERATURE METHOD
Mass processing of radiographs
Method
Replenish solutions
Stir the solutions
Mount the film on hangers
Processing is carried out at a temperature of
68- 70degree F and timer is fixed
Dry the film
VISUAL METHOD
Advantage :- film can be developed to the
contrast and detail desired for the particular
subject
Disadvantage :- film has to be processed
individually and is very time consuming
RAPID PROCESSING METHOD
Film can develop in 15minutes at room
temperature
Applied in endodontics and emergency
situations
AUTOMATIC METHOD
Automatic dunking models : produces a washed
film that still has to be dried
Miniature roller type : produces a dried film
Advantages :-
Process takes less than 4- 7 minutes
Uniformity
Less floor space required
No wet films to be handled
Density and contrast are consistent
Disadvantages
Quality is not as high as manually developed radiograph
More grain is evident in the final image High cost of equipment and maintenance
Mechanism
An in line arrangement consisting of a transport system
Function of roller Move the film through developing solutions Motion keeps solutions agitated
MONOBATH METHOD
Developer and fixer are combined in one solution
Advantage :- It is ideal for root canal treatment or in cases
of quick spot diagnosis
Disadvantages :- Alkaline type of fixer very rapidly oxidizes
under atmospheric conditions Results are not satisfactory as in
conventional processing as the fixing starts while the developing process is in progress
DAY LIGHT METHOD
No need of darkroom
Emulsion consists of yellow dye and the film
appears yellow and black
DIGITIZED PROCESSING METHOD
CR system : IP cassette is used instead of
cassette with an X-ray film
DR system : cassette is replaced by a sensor
which is directly connected to the
workstation
SELF DEVELOPING FILMS
Advantages :- No dark room is required Time saving
Disadvantages :- Poor image quality Image deteriorates with time No lead foil inside the packet Film packet is flexible and easily blent Films are difficult to use in positioning
holders