This document provides information on the processing of dental radiographs, including definitions of key terms, the formation of latent images, film processing solutions and procedures, darkroom requirements, and various processing methods. It describes how exposure to radiation results in chemical changes in the film's silver halide crystals to form a latent image, which is then made visible through development and fixing solutions. The roles of developer solutions, fixing solutions, and processing equipment are summarized.

1. GOOD
MORNING

2. SEMINAR

3. PROCESSING
YASMIN MOIDIN
2008 BATCH
AL AZHAR DENTAL COLLEGE
THODUPUZHA

4. 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

5. 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

6. 
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

7. 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

8. 
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

9. 
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

10. 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

11. 
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

12. 
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

13. 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

14. 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

15. 
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

16. 
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

17. 
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

18. 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

19. 
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

20. 
CHEMICAL INTENSIFICATION OF
RADIOGRAPHS

In – 4 chromium intensifier

In -5 silver intensifier

Copper iodide intensifying solution

XR -10 intensifying solution

Line toner solution

21. 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

22.  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

23. 
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

24.  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

25.  SAFE

LIGHT ILLUMINATION
Should be of low intensity
3 zones :i.
dimmest zone
ii.
medium zone
iii.
bright zone


Excessive exposure of film to safe light illumination
will result in fog, 3 factors :-

26. 
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

27.  TESTS
FOR CHECKING UNSAFE
ILLUMINATION

Coin test / penny test :- evaluate fogging caused by
inappropriate safe light conditions

Check for light leak

28.  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

29.  OTHER
REQUIREMENTS INCLUDE :

Thermometer

Timer

Drying racks

Stirring rod or stirring paddle

Plastic apron

30. 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

31.  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 6870degree F and timer is fixed

Dry the film

32.  VISUAL

METHOD
Advantage :- film can be developed to the contrast
and detail desired for the particular subject

Disadvantage
:-
film
has
to
be
individually and is very time consuming
processed

33. 
RAPID PROCESSING METHOD

Film can develop in 15minutes at room temperature

Applied in endodontics and emergency situations

34. 

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

35. 
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





36. 
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

37. 
DAY LIGHT METHOD

No need of darkroom

Emulsion consists of yellow dye and the film
appears yellow and black

38. 
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

39. 
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