Faculty of radiography and medical imaging

Second year

course: Introduction to radiography 2

Lecture title: film processing

Uz. Maha Eltayeb

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Processing Area consideration

Processing Area should offer an environment in

which the necessary function can be carried out

safely.

Processing Area still commonly called 'the dark

room”.

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1- Location of the dark room

Center of x-ray room

the walls are likely to be provided with x-ray hatch

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Central core design

DARK ROOM

SORTING

X-R

X-R

X-R

X-R X-R

X-R

X-R

X-R

SUPPORT AREA

RECEPTION -WAITING

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2- Entrance

•Single door

Single door disadvantages

1.prevent other entrance during the work.

2.Emergency events for technologist

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Double door

2 1

the disadvantages the two door can be open at

the same time , and it need a large space.

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revolving door

Light trap

Permit entrance of number of workers at any

time, need large space also

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Room size

depend on:

Staff and type of processing

the size of room work 24hrs must be 100 foot

square

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Ceiling

Not more than 4m if we use indirect safe light.

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The Floor

not slippery

Chemical resistant

made of Asphalt or porcelain easy to clean

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Walls

90% of dark rooms paint by a black color

10% light in color

the best the creamy white color why?

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Dark room ventilation

3-10 times/ hour

Use of air condition or extra fan

Dark room temperature should be maintained

between 65º F - 68 º F

18.3 º C to 20 º C

The relative humidity 40 t0 60 %

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Radiation protection

Protect:

personal

films

The dark room should not resave primary radiation, walls of the dark room should be 2mm lead equivalent, this by:

One inch barium plaster

6 inch of cement

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Test for radiation leakage

Coin test

Dental film

the coin and the film adhesive at the wall facing

the x-ray room for week.

If the image of coin is appear the room is not safe.

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Illumination

Two types

1. General white light

2. Safe light

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Safe light

wet bench

Direct safe light

dry bench

2. Indirect safe light at the middle of the room

Safe light power 25 watt

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Film Processing

The latent image is invisible because only few silver ions have been

changed to metallic silver and deposited at sensitivity centre.

Processing the film magnifies thus action

many millions of time.

Thus latent image is converted to visible image.

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Radiography recorded by x-ray

Imaging = exposure + processing

Exposure latent image

Processing permanent image

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Production Permanent image

This involves the action of a chemical

agent to make the hidden image visible.

This stage is known as development, and

it is followed by further chemical

processes which fix the image and make it

into permanent record.

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The silver bromide crystals of photographic

emulsion consists of positive silver and negative

bromide ions arranged in a geometric pattern

known as a crystal.

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Latent image •The sequences repeats its and the

sensitivity speck has a number of atoms

of silver

( Latent image).

•This cycle of events takes place

extremely quickly (10 ms)

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When silver bromide grain is exposed

to light (or x-ray),

some of the bromine ions in the lattice

emit electrons

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These electrons are able to travel

through the crystal, and their rapid

movement carried them into what

are known as electron-traps existing

in the crystals.

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An electron-trap is a region in

the crystal of low energy

is sensitivity speckcalled a

produced during

manufacturing.

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Not all silver ions in the crystal

are held in the lattice (interstitial-

ions). Those that are able to

travel are attracted to the

negatively charged electrons in

sensitivity speck.

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The negative charged on

electrons neutralizes the positive

charge on the silver ions, and

when this happens silver atoms

are formed.

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Basic photographic action:

a) Conversion of silver bromide Metallic silver

Initiated by light or X-ray:

Silver bromine=Bromine ions (negative) and sliver ions (positive)

bromine ions + light = electrons emitted

electrons + silver ions = silver atoms

These silver atoms began to form the latent image

(bContinued by the action of the developer:

Developer gives electrons to silver ions

electrons + silver ions = silver atoms

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The production of latent

image and the conversion

of the latent image into

manifest image follow

several steps.

A, radiation interaction

releases electrons.

B, these electrons

migrate to sensitivity center.

C, at the sensitivity center,

atomic silver is formed

by attracting an

interstitial silver ion.

D, this process is repeated

many times, resulting in

buildup of silver atoms.

E, the remaining silver halide

is converted to silver during

processing.

F, the resulting silver grain.

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• Different between silver halide and metallic

silver

1. Silver halide can be converted into soluble compound by action of chemicals known as

fixing agent

Metallic silver Ag un affected and remains in soluble.

2. Metallic silver is opaque to light the black parts of radiographic image are formed from metallic

silver.

3. Silver halides are sensitive to light, metallic silver is not

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Schematic distribution of silver halide grains on

the film emulsion.

The gray areas indicate latent image produced by

exposure.

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Partial development begins to produce metallic

silver (black) in exposed grains.

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Development completed.

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Unexposed silver halide grains have been removed

by fixing.

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Processing Cycle The complete processing cycle comprises:

Manual Processing

Development

Rinse

Fixing

Washing &

Drying

Automatic Processing

Development

Fixing

Washing &

Drying

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Development

• Development is the first stage.

•The stage covert invisible latent image into visible image

• Development is a process of chemical reduction oxidized.

•A good developer is highly selectivity act on exposed grains

•A poor developer is low selectivity act on exposed grains

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A developer is chemical solution that

converts the invisible (latent) image on

the a film into a visible one composed of

minute masses of metallic silver.

An alkali chemical solution

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Converts exposed silver bromide crystals (latent

image) to black metallic silver (visible image).

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Constitution of Developing Solutions;

• Developer agents - Reducing agent

(Metol, hydroquinone MQ. Phenidone,Hydroquinone PQ

Hydroquinone slowly action

Metol & Phenidone quickly action

Manual Processing \ MQ

Automatic Processing \PQ

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•Accelerators an alkali, activator PH

sodium carbonate NaCo3& NaoH

soften and swells film emulsion

• Restrainer

(potassium bromide KBr , potassium iodide).

Reduce the action of the reducing agents

•Preservative

•(antioxidant; sodium sulphite)

Slow oxidation of the reducing agent by room air

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•Solvent (water)

Medium in which chemicals are dissolved

•Buffers

(maintaining the pH;carbonates .

•Hardener Glutaraldehyde)

prevent swelling

•Sequestering agents (prevent precipitation of insoluble mineral salts EDTA

(Ethylene-diamine-tetra-acetic –acid}).

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MQ

Manual Processing

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Automatic Processing

PQ

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Manual processing

Before the introduction of automatic film processing films were processed manually.

The film was first immersed in tank containing developer

Immersed in a stop bath.

Fixer solution.

Water for washing.

Hung to drip dry.

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PQ compared with MQ

.1High contrast than MQ

.2High speed than MQ

.3Low auto oxidation than MQ

.4The activity not dependent on Br- concentration

.5Temperature dependent

.6Less likely to cause dermatitis

7. Long shelf life time

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Development time

•The time for reducing all exposed Ag Br only

,do not cause changes in unexposed one

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Control of developing

.1Time temperature control

.2Agitation film moving to

•To move air babbles and reach film by

chemical

•Move to refresh chemical concentration

3. Inspection

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Factors control development time

.1Solution concentration

reduce development time by increase solution

concentration

•For this we use PQ in automatic processor

because less amount of PQ give high

concentration.

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2. Type of the developing agent

MQ or PQ

3.developer temperature

15º C 7 min

16º C 6 min

18º C 5 min

20º C 4 min

22º C 3 min

24º C 2 min

26º C 1 min

28º C 30 sec

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3. Agitation

4. Degree of solution expansion

can be a voided in manual processing by

Cover the developer

Reduce carry over rate

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Rinsing : Stop bath or water rinse

Between developing and fixing stages to avoid

carry of the developer to fixer and this cause:

.1Dichotic fog ( Pink green color)

.2Increase fixer alkalinity require about 30 sec

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Rinsing stage

•Manually by

.1Static water

.2Continually renewed water

More effect water + acid to stop developer

action.

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Fixation

•Fixer agent

.1Sodium thiosulphate Na2 S2 O3- manual

.1Ammonium thiosulphate Nh4)2 S2 O3

clears and removes unexposed silver

bromide crystals

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Acidifier

Acetic acid provides acid medium in which fixing

agent operates

stop the action of the alkaline developer solution

on contact

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•Hardener

Aluminum chloride Shrink and hardens

emulsion

•Preservative

Sodium sulfite slows oxidation of both fixer

& developer solution

•Solvent water

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Factors control fixation rate

.1Agitation

.2 fixer Agent type

.3Temperature

.4Solution expansion

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Fixation

Fixation time + cleaning time

Fixation time:

2 X cleaning time = 5-4 min

cleaning time:

the cleaning time is defined as the

time taken for the milky appearance.

1.3 X Fixation time

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Washing factors

•Temperature

•Concentration of sodiumthiosulphate in water

•Water exchange rate

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Washing solution

•Water

•Removes chemicals remaining on film

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Film hanger

.1 Channel hangers

.2Tension hangers

.3Dental hanger

.4Hanger bar sand clips

Made from steel resistant to solutions reaction

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Processing tank

Two types of tanks

1) Vertically (deep tank)

2) Horizontally (shallow tank)

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Horizontally (shallow tank)

Can not develop number of films

Can not control processing

Can not control temperature

Cause air oxidization