Top Banner
GOOD MORNING
40
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: PROCESSING

GOOD MORNI

NG

Page 2: PROCESSING

SEMINAR

Page 3: PROCESSING

PROCESSING

YASMIN MOIDIN

2008 BATCH

AL AZHAR DENTAL COLLEGE

THODUPUZHA

Page 4: PROCESSING

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

Page 5: PROCESSING

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

Page 6: PROCESSING

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

Page 7: PROCESSING

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

Page 8: PROCESSING

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

Page 9: PROCESSING

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

Page 10: PROCESSING

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

Page 11: PROCESSING

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

Page 12: PROCESSING

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

Page 13: PROCESSING

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

Page 14: PROCESSING

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

Page 15: PROCESSING

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

Page 16: PROCESSING

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

Page 17: PROCESSING

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

Page 18: PROCESSING

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

Page 19: PROCESSING

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

Page 20: PROCESSING

CHEMICAL INTENSIFICATION OF

RADIOGRAPHS

In – 4 chromium intensifier

In -5 silver intensifier

Copper iodide intensifying solution

XR -10 intensifying solution

Line toner solution

Page 21: PROCESSING

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

Page 22: PROCESSING

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

Page 23: PROCESSING

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

Page 24: PROCESSING

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

Page 25: PROCESSING

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 :-

Page 26: PROCESSING

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

Page 27: PROCESSING

TESTS FOR CHECKING UNSAFE

ILLUMINATION

Coin test / penny test :- evaluate fogging

caused by inappropriate safe light conditions

Check for light leak

Page 28: PROCESSING

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

Page 29: PROCESSING

OTHER REQUIREMENTS INCLUDE :

Thermometer

Timer

Drying racks

Stirring rod or stirring paddle

Plastic apron

Page 30: PROCESSING

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

Page 31: PROCESSING

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

Page 32: PROCESSING

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

Page 33: PROCESSING

RAPID PROCESSING METHOD

Film can develop in 15minutes at room

temperature

Applied in endodontics and emergency

situations

Page 34: PROCESSING

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

Page 35: PROCESSING

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

Page 36: PROCESSING

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

Page 37: PROCESSING

DAY LIGHT METHOD

No need of darkroom

Emulsion consists of yellow dye and the film

appears yellow and black

Page 38: PROCESSING

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

Page 39: PROCESSING

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

Page 40: PROCESSING