Film cessing Chemical and Their Properties

8/6/2019 Film cessing Chemical and Their Properties

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FILM PR0CESSING, CHEMICAL

& THEIR PROPERTIES

MODERATORMODERATOR::

Mr. SCMr. SC BansalBansal (Lecturer)(Lecturer)Deptt. of RadioDeptt. of Radio--Diagnosis & ImagingDiagnosis & ImagingPGIMER ChandigarhPGIMER Chandigarh

PRESENTER:PRESENTER:VarinderVarinder singhsinghB.Sc. M.T.(XB.Sc. M.T.(X--Ray)Ray) --2nd Year2nd YearDepttDeptt. Of Radio. Of Radio--Diagnosis &Diagnosis &

Imaging.Imaging.PGIMER, ChandigarhPGIMER, Chandigarh

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INTRODUCTION:

In the Radiology deptt. X ray films are used torecord the radiographic image. X ray films havephotosensitive material (AgBr) which records the

information. When the x ray film is exposed with the light or x

ray radiation, during this process of radiography thelatent image is formed.

The emulsion of x ray film must be chemicallyprocessed to bring out the latent image into thevisible & permanent form.

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DARKROOM

The darkroom is a very important place in the

radiology deptt. of a hospital, nursing home or a

private x ray clinic for the processing of x ray

films. The term darkroom overstates the case,

since complete darkness is unnessary. In fact, a

great deal of safe illumination is provided to

facilitate darkroom procedures.

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LOCATION: The darkroom should be

1. Centrally sited & serviced by hatches from the

adjacent imaging rooms.2. Sited away from the damp & hot areas.

3. Accessible in terms of power & water supply.

SIZE: A dark room must be of minimum areaof 10 m square & a ceiling height of around

2.5 -3 m.

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FLOOR: The floor should be durable, easilycleaned, not sleeppery & resistant to staining &corrosive substance. A light coloured material will be

an advantage to migrate against the low-light workingconditions.

WALLS/ CEILING: The walls & ceilingshould be

1.Light in colour so as to reflect much light aspossible on to working surfaces. A high level ofreflected light means that it may be possible to work

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With fewer safe lights, & should be easy to wipe

over & keep clean.

H

UMIDITY: Relative humidity is maintained ataround 40-60 %

TEMP. : Room temp. is maintained b/w 18-20 *c.

RADIATION PROTECTION: The walls of dark

room can be protected by coating Ba. plaster,

using lead shielding or building them with greater

thikness. Doors can be lined with Pb. ply sheet.

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ENTRANCE:

1. Single door system

2. Double door system3. Revolving type

DARK ROOM ILLUMINATION:

1. White lighting: is necessary for following tasks Inspection & maintainance of cassettes &

screens.

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Cleaning of working surfaces.

Servicing of equipment.

SAFE LIGHT: The darkroom should have a lightsource which will not fog films & provide adequateillumination. Safe lamps serve this purpose , theyshould have filter of the proper colour . The working

distance from the safe light to the film should not beless than 1.2 meter & bulb wattage should be less than15 watts.

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Processing

Manual

InspectionTime-Temp.

Method

Automatic

TYPES OF PROCESSING


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MANUAL PROCESSING

This is the process which make a latent image

into a visible image.

It has 5 distinct steps

y Development

y Intermediate rinsing / Stop bath

y Fixing

y Washing

y Drying

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Processing is a series of actions by which exposed Xray film yields an image. In processing a film, thesequence of actions should be as follows:

Mark the patients name on the film.

Develop the film. Rinse out developer from the film or stop the

development.

Fix the image.

Wash the fixer from the film. Dry the film.

Check the name, date & patient X ray number on thefilm.

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During the marking, development, rinsing of

developer from the film & fixing, there should

be no white light in the darkroom. But this

process can be done under the safe lighting.

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IDENTIFICATION OF THE FILM:

A film printer is used to mark the

identification of the patient on film.

The patients name should be written on the

film when it is taken out of the cassette.

Before it is put into the developer.

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INSPECTION METHOD:

In this method we just check the proper

development of visible image.

TIME TEMP. METHOD:

In this method the time and temp. of the

solution is fixed.


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BASIC MANUAL PROCESSING SYSTEM

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DEVELOPING:

The film is now ready to be developed.

The film should be mounted in a hanger

& put into a tank of developer andmoved up and down once or twice in

the tank. The film should then be left to

develop. The time taken for the film todevelop depends on the temperature &

concentration of dev. solution.

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The temperature of the developer should be

measured in the morning and afternoon with the

thermometer provided. When the film is placed

in the developer, set the timer to the number ofminutes required for that temperature. The film

should only be removed when the clock has

stopped timing. The developing solution shouldbe covered to prevent oxidation of dev. from air

& light, when not in use.

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The temperature time table below gives the

time, in minutes, that the film must stay in

the developer at the given temperature.

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TEMPERATURE-TIME TABLE:

TEMP. OF DEV.

*C *F

DEVELOPING TIME

15 59 7

16 61 6

17 62.5 6

18 64.5 5

19 66 5

20 68 4

21 70 4

22 71.5 3

23 73.5 3

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CONTENT OF MANUAL DEVELOPER

SOLUTION

1. Developing Agents 2. Accelerator

3. Preservative

4. Restrainer 5. Solvent

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PHENIDON

1-phenyl-3pyrazolidone,introduced by Ilford Ltdin 1940

y Properties very similar to those of Metoly Rapidly acting

y Produce low contrast

y Unselective between exposed and unexposed grains

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HYDRQUINONE

y 1,4-Benzenediol [C6H4(OH)2], also calledQuinol.

yWhite crystalline substance.yDiscovered in 1880 .yNeeds strong alkaline medium to reacty Produce high contrast.y Selective between exposed and unexposed

grains.

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ACCELERATOR

Developing agents function in high alkaline

medium (pH 10-11.5) Generally Potassium

Carbonate and Potassium Hydroxide are used.

Sodium Carbonate and sodium Hydroxide are

often used in combination.

Potassium compounds are preferred because of

their higher solubility but at the same time theyare costlier.

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PRESERVATIVE

Developing agents are reducers, hence they tendto get oxidized by the action of the chemicalsand aerial oxidation

y First step of oxidation produces sulphonatesy These sulphonates further accelerate the rate of

oxidation

y Sod . Sulphite( Na2SO3) / Pot . Sulphite(K2SO3) are

used as preservative to check the action of thesesulphonates to slow down the final stage of oxidation

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RESTRAINER

It increases the selectivity of the developingagents between the exposed and unexposedgrains by forming a negative barrier around the

grains. Restrainer is used to check the over-action of

the developing agents.

Potassium bromide (KBr) is used in MQDeveloper.

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SOLVENT

Wateris used as universal solvent.

Functions:

y It acts as a carrying medium in which the developer

constituents are dissolved.

y It has softening effect on the film emulsion, thus

allowing the developing chemicals to penetrate the

emulsion and act on the silver halides.

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RINSING / STOPBATH:

After development, the film should be rinsed

for about 30 seconds in clear water. During

this time the film should be lifted up and downseveral times in the water tank.

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FIXING:

After the film has been rinsed, it should be put

in the fixing tank. The film should stay in thistank for longer than 5 minutes.(there must be no

white light in the darkroom for the first 3

minutes of fixing time).

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CONTENTS OF FIXING CH

EMICAL

1. Fixing agent

2. Accelerator

3. Preservative

4. Hardner

5. Solvent

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Fixing agent

A fixing agent acts as a chemical whichcombines with the largely insoluble silverhalides (bromide or iodide) in the film

emulsion to form the soluble compoundswhich can diffuse and be washed out of theemulsion.

Sodium thiosulphate is used as fixingagent.

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ACCELERATOR

Fixing bath is acidic in nature (pH 4.0-5.0)

because

y Fixing agents act only in acidic

environment.

y This much low pH stops the action of

developer completely.

y Acetic acid (CH3COOH) is the acid ofchoice.

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PRESERVATIVE

The preservative in fixer retards the

decomposition of thiosulphate and thus delays

the onset of sulphurization. Its presence isparticularly in liquid concentrates.

Sodium sulphite is commonly used.

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HARDNER

Potassium alum orchrome alum is used as a

hardner.

It hardens the gelatine in the film emulsion,

thereby protecting it against scratches.

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SOLVENT

Wateris used as a solvent.

It acts as a carrying medium in which

fixing contents are dissolved.

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WASHING

After it has been fixed, the film should be

washed in the large washing tank.(this tank

usually has clean running water). The filmshould stay in the water tank for at least 10

minutes. At this time the white light may be

on provided if no other films are beingprocessed.

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DRYING

The film is now ready to be dried. The drying

temperature must not exceed 35*c, and the

film must be hung in a dust-free area. Finally the dry developed film should be

checked to ensure that the name of the patient,

x ray number, the date & the L or R marker

can all be read easily. After checking, the film

can be put in a completed envelope & filed.

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DEV. TIME 3 min.STOP BATH 30 sec.

FIXING 5-7 min.

WASHING 10min.

DRYING 30min.

MANUAL PROCESSING

TEMP.

20*c20*C

20*C

20*C

35*C


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Each day, before any films are processed, thedeveloper & the fixer should be stirred usingonly the special rods provided for each

solution. The slightest mixer of these twochemicals upsets the processing so never mixthe tanks or the stirring rods used for the twochemical solutions. The developing rod should

only be used for the developer and the fixingrod only for the fixer. The developing tankshould contain.

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Only developer, and the fixing tank only fixer.

The developing and fixing tank should full ofdeveloper and fixer, respectively, at all times extradeveloper and fixer should be kept in separate bottlesin darkroom for topping up the tanks.

Both the developer and fixer solutions in theirrespective tanks must be completely changed aftertwo weeks.

The water rinse off developer from the film should becompletely changed everyday and the tank should bekept full.

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Running water should preferably be used to washoff fixer from the films . If this is not possible, thewater tank must be large, and the water must be

changed everyday ( dirty water contains chemicalswhich will spoil the film a waste of money andtime).

The chemical solutions ( developer and fixer) and

rinsing and washing water should be kept at aboutthe same temperature.

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Check that the water running into tank is not

too hot. If the water is hot, it will be better to

change the water in the tank. The water coming into the tank should be as

clean as possible. If the water is muddy or

dirty ask for a filter. The filter should becleaned every week.

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PREPARING THE DEVELOPING

SOLUTION

In 12 Ltrs. of water, add with stirring, content of

part A (5 Ltrs.) with stirring then add content of

part B (500 ml.) with stirring. Next, add thecontent of part C (500 ml.)with stirring. Make the

final solution 20 Ltrs. With water.

Same solution is used as replenisher solution.

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PREPARING THE FIXING

SOLUTION

In 18 Ltrs. Of water, add with stirring content of

part A (5 Ltrs.) and wait till solution is clear. Add

the content of part B (1 Ltr.) and make volume of25 Ltrs.

Same solution is used as replenisher solution.

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AUTOMATIC FILM PROCESSING

The processing of the x ray film is entirely

done nowadays by machine, with the filmbeing fed in at one end and received,

processed & dried at the other.

Film is transported through various chambers

of automatic processor by roller system.

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TRANSPORT SYSTEM COMPONENT

Feed Tray

Rollers (Different Assemblies):

1. Entrance

2. Deep Racks3. Turnaround

4. Crossover

5. Squeegee

6. Dryer

Receiving Bin

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TRANSPORT SYSTEM(ROLLERS)

Turnarou

nd

Entrance

DeepRacks

Crossover

Squeegee

Dryer

Feed

Tray

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PROCESSOR (TOP VIEW)

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CONSTITUENTS OF DEVELOPING

SOLUTION

The developing solution used in automaticprocessor are different in several important

respect for those used for manualprocessing.

The description which follows is based on

the solutions used in automatic processingare :

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DEVELOPERREPLENISHER

SOLUTION

A typical Developer usually contains followingconstituents :

1. Developing agent

2. Accelerator3. Restrainer

4. Preservatives

5. Hardener

6. Buffer

7. Sequesting agent

8. Solvent

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DEVELOPING AGENT

Modern x ray developers use a

combinations of two developing agents:

Hydroquinone and phenidone / metol.

A combinations of phenidone

hydroquinone(PQ) is used.

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HYDRQUINONE

y 1,4-Benzenediol [C6H4(OH)2], also calledQuinol.

y White crystalline substance.yDiscovered in 1880 .yNeeds strong alkaline medium to reacty Produce high contrast.

y Selective between exposed and unexposedgrains.

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METOL

P-methyl aminophenol (CH3NH.C6H4OH )

y White crystalline substance

y Discovered in 1891

y Rapidly actingy Produce low contrast


y Restrained by increased presence of Br-

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PHENIDON

1-phenyl-3pyrazolidone,introduced by Ilford Ltdin 1940

y Properties very similar to those of Metol

yRapidly acting

y Produce low contrast


ADVANTAGE OVER METOL

y Activity does not diminish in presence of increasedconcentration of Br

y 10 15 times more effective than Metol

y Long working life.

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SUPERADDITIVITY

If only Metol/Phenidone(M orP) orHydroquinone(Q) is used alone, result will either bevery fast development with high density & contrastor exactly its opposite.Hence M and Q are usedtogether to produce adequate result. This phenomenais called Superadditivity or synergism.

When Metol and Hydroquinone are used incombination, it is called MQ Developer and when

Phenidone is used withHydroquinone, it is calledPQ Developer

Presently PQ is the combination of choice

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ADVANTAGES OF SUPERADDITIVITY

Q produces very high contrast ,but M or P producesvery low contrast, but PQ or MQ produces adequatecontrast

P or M start action readily but their activity dropsdown pretty quickly, whereas Q starts slow and cantproduce very good density alone unless kept in thesoln for very long. But MQ and PQ produceadequate contrast and density

Unless used in combination, these chemicals cantproduce required grey scale details

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ACCELERATOR

Developing agents function in high alkaline

medium (pH 10-11.5) Generally Potassium

Carbonate and Potassium Hydroxide are used.

Sodium Carbonate and sodium Hydroxide areoften used in combination.

Potassium compounds are preferred because of

their higher solubility but at the same time theyare costlier

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RESTRAINER

Restrainer is used to check the over-action of thedeveloping agents.

It increases the selectivity of the developing agents

between the exposed and unexposed grains byforming a negative barrier around the grains.

As Phenidone is not so much affected by Br ion

concentration,Benzotriazole is used as an organicantifoggant in PQ Combination.

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PRESERVATIVE

Developing agents are reducers, hence they tendto get oxidized by the action of the chemicalsand aerial oxidation.

y First step of oxidation produces sulphonates.y These sulphonates further accelerate the rate of

oxidation.

y Sod . Sulphite( Na2SO3) / Pot . Sulphite(K2SO3) areused as preservative to check the action of thesesulphonates to slow down the final stage of oxidation.

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the inclusion of a hardener in the developer . A

powerful organic hardener, such as

glutaraldehyde is used.

Developers formulated for manual processingmay not include a hardening agent.

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BUFFER

Buffers are used to maintain the pH.

These are pairs of strong and weak alkali. The

presence of buffering agents in developing

solution prevents the undesirable effects of

changes in pH due to aerial oxidation of

developer and acidic by-products of

development process. Normally adequate

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buffering action is provided by carbonates

used as accelerator and the sulphites acting as

preservatives.

Thus, no additional buffering chemicals are

necessary in most developing solutions.

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SEQUESTING AGENT

Sequesting agents are chemicals which prevent

the precipitation of insoluble mineral salts.

They act by combining with the minerals to form

soluble compounds which do not react with the

developing chemicals .

EDTA ( ethylene diamine tetra-acetic acid) are

commonly included in developer for thispurpose.

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SOLVENT

Water is used as universal solvent.

y In some areas, extra hard watermay be boiledbefore using

yItis always wise to use in-line filtration

Functions:

y Itacts as a carryingmediumin which the developerconstituents are dissolved

yIt has softening effect onthe film emulsion, thusallowing the developing chemicals to penetrate theemulsionand act onthe silverhalides.

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Other constituents of developer

solution

In addition to the eight constituents

replenisher also contain Bactericides &

fungicides to inhibit the growth of organismin solution. Such organisms can lead to

unpleasant effect such as formation of slimy

coating on the walls of developer tank.

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STARTER SOLUTION

Starter solution is basically an acidic restrainer

when added to developer replenisher , it reduces

the pH to its normal working value and it

provides a supply of potassium bromiderestrainer

Dev. replenisher +Dev. starter=Working dev.

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REPLENISHMENT

This soln is used to top-up and rejuvenate

exhausted Dev.Soln

yConstituents are the same only restrainer

is lacking.

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ACTION OF SQUEEGING ROLLER

Rinsing or stop bath process is not used in

automatic processing bcz with the help of

squeeging rollers remaining dev. Solution isremoved.

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FIXING

When a film is exposed and developed, some ofthe Silver halide converted to metallic silver butrest remain there to give the film an opaque look.

These remaining Silver halide has to be removedto give the film a clear appearance.

In the fixing stage remaining Silver halide areremoved.

The image becomes permanent by chemicaltreatment.

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COSTITUENTS OF FIXING SOLUTION

Fixing agent

Acid

Buffer

Hardener

Preservative

Anti sludging agent

Solvent

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FIXING AGENT

A fixing agent as a chemical which combineswith the largely insoluble silver halides (bromideor iodide) in the film emulsion to form thesoluble compounds which can diffuse and be

washed out of the emulsion. Fixing agent used in radiography processing is

ammonium thiosulphate & sodium thiosulphate.

Ammonium thiosulphate is used in automatic

processing. Sodium thiosulphate is used in manual

processing.

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Advantage of ammonium thiosulphate over

alternative fixing agents:

1. High solubility.

2. High activity, thus fixing can be accomplished

rapidly eg. 15 s in a 90 s processing cycle.

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ACID

Fixing bath is acidic in nature (pH 4.0-5.0)

because

y Fixing agents act only in acidic environment.

y This much low pH stops the action of developer

completely.

y Acetic acid (CH3COOH) is the acid of choice.

*A strong acidll decompose thiosulphate andinsoluble sulphur depositll appear.

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BUFFER

pH of fixer is important in order to:

1.Prevent sulphurization.

2. Ensure nutralization.

3. Maintain optimum hardener activity.

Sodium acetate is used as buffer inconjuction with the acetic acid.

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PRESERVATIVE

The preservative in fixer retards the

decomposition of thiosulphate and thus delays

the onset of sulphurization. Its presence isparticularly in liquid concentrates.

Sodium sulphite is commonly used.

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ANTI SLUDGE

Sludge is a complex precipitation which appear

when the pH is too high.

y Boric acid (H3BO3) is used as antisludging agent.

y It reduces the formation of sludge which adhere to

the film & to the walls of fixing tank.

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SOLVENT

Wateris the solvent and diluent used in fixing

solution it acts as a carrying medium in which

the fixer constituents are dissolved

It has a softening effect on the film emulsiongelatin , thus allowing the fixing chemicals to

penetrate the emulsion and act on the silver

halides .

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Contd....

The water used for developer solution must be

clean and free from insoluble deposits, such asgrit or rust particles, which could scratch the

delicate film emulsion or damage the

processing equipment

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WASHING

When film leaves the fixing tank its emulsion issaturated with fixing solution contaminatedwith silver complexes and ammonium halides.

If such chemicals are not removed, theemulsion will gradually develop a yellow brownsulphur stains.

To avoid such effects the film is passed through

a washing stage. Tap water is a satisfactory washing medium for

automatic processor.

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FIXER RETENSION (NOT WASHED OFF)

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DRYING

The final stage in the processing of radiograph

is to remove all of the surface water and most

of that retained in its emulsion.

Dust free hot air is blown on the surface offilm.

The temperature of this hot air is usually

around 55*c.

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DEVELOPMENTTIME

26 sec. Temp.32*C

FIXING TIME 15 sec. 32*c

WASHING 15 sec. 32*c

DRYING 24 sec. 57* c

AUTOMATIC PROCESSING

10 sec. film travelling time in various chambers ofprocessing tank. Total processing time is 90 sec.

MAINTAINACE OF AUTOMATIC


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MAINTAINACE OF AUTOMATIC

PROCESSOR

DAILY MAINTAINANCE:

1. Remove cross-over roller assemblies or guide

plates. Rinse under warm running water (38*c).

Wipe dry. Do not use the same cloth for developer& fixer.

2. Wipe down the entry rollers with a damp cloth.

Wipe dry. 3. Wipe off all chemical deposits in the processing

section.

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Contd

4. wipe all top rollers above solution level.

WEEKLY MAINTAINANCE:

1. Repeat the daily cleaning programme.

2. Put splashguard b/w the develper & fixer

tanks to prevent contamination. Rinse andwipe with cloth using a different cloth for

developer and fixer.

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Contd.

3. Operate each rack manually to check tension onchains/ gears, that they move freely, and that allrollers rotate correctly.

4. Re-install racks, being very careful. 5.Replace cross-over assemblies. Check each

component is correctly positioned.

6.Remove drier section air tubes and clean

vigorous agitation in warm water. 7.Clean drier rollers with a damp cloth.

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MONTHLY MAINTAINANCE:

1.Carry out weekly and daily maintainance.

2. Drain main tanks and clean with sponge and runningwater.

3. Close drain valves.

4. Fill both developer & fixer tanks with water, replaceprocessor cover & switch on mains power and

processor on switch. This activates the solutioncirculation pumps & flushes the system through withwater.

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Contd.

5. Turn off the processor & mains isolator.

Remove the processor lid.

6.Drain tanks & refill with fresh chemistry.

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Two types of daylight systems are :

1. Composite or Complete type

2. Modular or Integrated type

Composite type: The word compositmeans that all the systems components i.e.

film supply magazine or dispenser, film

unloading machinery and processor are placed

combined in one place.

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Contd.

In this system a cassette containing film forprocessing is inserted at front of the unit & doorof system is automatically closed. A bar code(attached to every cassette) is read by the loadermicroprocessor, in order to identify the size of thecassette.

Inside the unit cassette is automatically opened &

film is extracted by means of suction cups. Theidentity of the patient is photographed on film byprism or lens system.

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Contd.

Now film is transported through roller systeminto processor. Then, film loading carriage orsled moves into position beneath the appropriatefilm magazine dispenser, then film is released bydispenser into empty cassette.

After receiving film cassette closed, the frontdoor of the unit opens & processed film goes to

film bin. The entire unloading & reloading sequence

takes only 15 sec

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Contd.

Modular daylight system: In thistype of system the cassette loading

equipment i.e. film dispenser is separatedfrom the automatic processor.

The automatic processor may be centrally

located & film dispenser may be sited inor near the imaging room.

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Contd.

Film dispenser: A film dispenser consists of an

upper film storage & dispensing section & a

lower cassette loading section.

In this unit a cassette is placed in front of the unit

pushing forwards which activates the loading

cycle mechanism. The cassette is driven uptowards the film storage area. Then , two metal

pins enter the cassette frame on either side of the

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Contd.

Film aperture, causing a spring loaded flap

to open. Then, the film from dispenser is

released & received by cassette. Now, thecassette is lowered away so that metal pins

disingage & cassette flap springs shut,

safely protected the film from any light.

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ADVANTAGE OF DAYLIGHT SYSTEM


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ADVANTAGE OF DAYLIGHT SYSTEM

OVER CONVENTIONAL TYPE

Faster film handling.

Fewer film handling marks.

Less space requirement for processing

procedure.

More time can be spent with patient instead of

film handling activities.

Greater patient throughput bcz of faster filmhandling.

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ADVANCEMENTS IN FILM

PROCESSING

Introduction: Laser imagers also known as

laser cameras, Laser printers or hard copycameras, have become the state of art equipment

for recording images in digital radiography,

computed tomography(CT scan), Magnetic

resonance & imaging (MRI), Ultrasound(US).

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Contd.

There are two major types of Laser imagers used tocreate hard copy images from digital data onradiographic films: Wet Laser imagers and DryLaser imagers.

In wet Laser imagers, liquids are used to process thefilms through four steps: developing, fixing, washingand drying. The liquid chemicals are expensive,produce hazardous waste and require a water supply

and drainage facilities. The introduction of dry Laserimagers in 1996 eliminated the use of liquidchemical processing.

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Contd.

Modern dry Laser imagers can produce images

with an almost continuous gray scale, as do

conventional wet Laser imagers.

Because dry processor Laser imagers eliminate theneed for liquid chemicals, they are easy to set up

anywhere in the hospital and easy to connect to the

computer network. Moreover, dry Laser imager

have an automatic quality control program builtinto the system and thus eliminate the need to

perform daily sensitometry.

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FILM MATERIAL:

The films used in dry and wet Laser imagers areof blue base films respectively on which a silvergrain emulsion is coated to produce a visibleimage.

Whereas , the wet Laser films containconventional silver halide crystal so , they requirethe use of wet chemical processing, and the dry

Laser films are based on silver behenate, used inmicrofilms and are infrared sensitivephotothermography film.

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WORKING OF WETLASER IMAGER

The following sequence occurs each time when theoperator issues a print command:

1. In the wet Laser imager, the film is taken out ofthe supply cartridge.

2. Then film is exposed with Laser beam in a Zpattern.

3. After exposure, the film goes through aconventional development, fixation , washing &drying procedure.

4.After this film is delivered at the receiving tray.

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WET LASER IMAGER


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WET LASER IMAGER

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O AS AG


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WORKING OF DRY LASER IMAGER

The operator acquire the images from the imagesource device, which is stored on a hard disc in theimager for printing on the film. The followingsequence occurs each time when the operator issues

a print command: 1. Suction cups lit a single sheet of a film out of the

supply cartridge and route it into the film feedroller.

2. The film feed rollers move the film down to theplaten rollers, which drive the film into theexposure module platen.

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Contd.

3. A moving Laser beam writes the image on to thefilm, which is held stationary in the platen.

4. The platen rollers reverse the direction and movethe exposed film up through the vertical transport

area. 5. Transport rollers drive the film on to the processor

drum.

6. The heated processor drum develops the film(convert into visible image) as it passes over the drum.The film is developed by heating it to approximatelyat 120*c for 15 sec.

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Contd.

7. In this Laser imager, an infrared Laser diode

records an image on the film , then a heating unit

develops it and a densitometer scan, a self-generated test film to keep the density and

contrast at present values.

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DRY LASER IMAGER


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DRY LASER IMAGER

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ADVANTAGE


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ADVANTAGE

Dry view Laser imaging film delivers diagnostic

quality, continuous tone images along with sharp

alphanumeric and optimum contrast with no image

quality variability due to wet chemistry. The principle advantage of this latest technology lies

in the fact that no wet chemical processing is

required and is able to produce high quality film

images without the need of an associated automaticprocessor as well as darkroom procedures with

minimum impact on the enviornment.

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REFERANCE


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REFERANCE

Radiographic photography , Chesney

Journal on Manual of Darkroom

technique(World Health Organization)

Journal of IART sept. 2003

www.google.com

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Film cessing Chemical and Their Properties

Documents