Film processing 2 Film processing 2. Dev.RinseFixWash Dryer Processing cycle.

Film processing 2Film processing 2

Dev. Rinse Fix Wash

Dryer

Processing cycle

Dev

Developing

Rinse

Rinsing (stop bath)

Rinsing in manual Rinsing in manual processingprocessing

Immediately after development Immediately after development the film is dipped in the water in the film is dipped in the water in order to:order to:

i.i. Stop developmentStop development

ii.ii. To wash the developer from the To wash the developer from the surface of the film – (reduces surface of the film – (reduces developer carry over to fixer)developer carry over to fixer)

Rinsing in Automatic Rinsing in Automatic processing?processing? No rinsing stageNo rinsing stage The developer is removed from The developer is removed from

the film surface by passing it the film surface by passing it through the special type of rollers through the special type of rollers called “squeegee rollers”called “squeegee rollers”

Alkaline Developer is neutralized Alkaline Developer is neutralized by the acid in the fixerby the acid in the fixer

FixingFixing

Fixer

Film

Film

Functions of fixingFunctions of fixing To stop any further developmentTo stop any further development Clears the image (making the Clears the image (making the

background transparent to light)background transparent to light) Makes the image permanent (fixed)Makes the image permanent (fixed) (no more sensitive to light) (no more sensitive to light) by Removing the undeveloped silver by Removing the undeveloped silver

bromide crystals from the emulsionbromide crystals from the emulsion Hardens the emulsionHardens the emulsion

Fixer constituentsFixer constituents SolventSolvent Fixing agentFixing agent AcidAcid HardenerHardener BufferBuffer PreservativePreservative Anti-sludging agentAnti-sludging agent

Functions of fixer Functions of fixer constituentsconstituents

ConstituentConstituent FunctionFunction

SolventSolvent

(water)(water)Carrying medium for the Carrying medium for the active ingredientsactive ingredients

Controls the acidity by Controls the acidity by diluting diluting

Fixing agentFixing agent

(Sodium (Sodium Thiosulphate Thiosulphate /Ammonium /Ammonium ThiosulphateThiosulphate

Combines with insoluble Combines with insoluble AgBr to form soluble AgBr to form soluble compounds (Ammonium compounds (Ammonium Argento-Thiosulphate & Argento-Thiosulphate & NHNH44BrBr

AcidAcid

(Acetic acid – pH 4.0 (Acetic acid – pH 4.0 – 4.5)– 4.5)

To stop developmentTo stop development

To provide suitable To provide suitable working environment working environment for hardening agentsfor hardening agents

HardenerHardener

(Aluminium chloride (Aluminium chloride & aluminium & aluminium sulphate)sulphate)

Hardens the Hardens the emulsion to limit emulsion to limit water absorption, to water absorption, to reduce drying time, reduce drying time, to minimize physical to minimize physical damagedamage

BufferBuffer

(Sodium (Sodium acetate & acetate & acetic acid)acetic acid)

Controls the pH in a precise Controls the pH in a precise range in order to:range in order to:

i. Prevent sulphurizationi. Prevent sulphurization

ii. Neutralize the developer ii. Neutralize the developer

iii. Optimum hardening iii. Optimum hardening

PreservativePreservative

(Sodium (Sodium sulphite)sulphite)

Retards the decomposition of Retards the decomposition of thiosulphate and delays the thiosulphate and delays the onset of sulphurizationonset of sulphurization

Anti-Anti-sludging sludging agent (Boric agent (Boric acid)acid)

Reduces the formation of Reduces the formation of sludge of insoluble aluminium sludge of insoluble aluminium compounds by the aluminium compounds by the aluminium salts used as the hardnersalts used as the hardner

Factors affecting Factors affecting FixationFixationThe quality and quantity of fixation The quality and quantity of fixation

depends on the:depends on the: Constitution and activity of fixing Constitution and activity of fixing

solutionsolution Fixer temperatureFixer temperature Fixing timeFixing time

Constitution & activity Constitution & activity of fixing solutionof fixing solutionAt a given temperature the activity of At a given temperature the activity of

fixer solution depends on:fixer solution depends on: Fixing agentFixing agent Concentration of fixing agentConcentration of fixing agent Amount of hardener presentAmount of hardener present The amount of soluble silver compounds The amount of soluble silver compounds

and soluble halides presentand soluble halides present pH pH

Fixer temperatureFixer temperature The activity of fixing agents The activity of fixing agents

increases with temperature. increases with temperature. But high temperatures cause But high temperatures cause

emulsion swelling and becomes emulsion swelling and becomes susceptible to damage.susceptible to damage.

However precise control of However precise control of temperature is not necessarytemperature is not necessary

Fixing timeFixing time The fixing time should be long The fixing time should be long

enough to complete the fixing enough to complete the fixing process.process.

The required time for complete The required time for complete fixation depends on thefixation depends on the

i. activity i. activity i. type of film emulsion i. type of film emulsion iii. Agitation of fixer solutioniii. Agitation of fixer solution

Replenishment of FixerReplenishment of FixerReplenishment of fixer is necessary toReplenishment of fixer is necessary to

i.i. Maintain the activityMaintain the activity

ii.ii. Maintain the volumeMaintain the volume

The rate of replenishment depends onThe rate of replenishment depends on

i.i. Area/number of films processedArea/number of films processed

ii.ii. Type of emulsion/filmType of emulsion/film

iii.iii. Type of imageType of image

Replenishment of Replenishment of chemicalschemicalsManual processingManual processing

Suitable quantity is Suitable quantity is

added manually at added manually at

regular intervalsregular intervals

Automatic processingAutomatic processing

Added automaticallyAdded automatically

by the replenishmentby the replenishment

pumps at a given pumps at a given

rate for each film rate for each film

processedprocessed

WashingWashing Removes the fixing solution Removes the fixing solution

contaminated with silver complexes contaminated with silver complexes and ammonium halides from the film and ammonium halides from the film surface and from film emulsionsurface and from film emulsion

Running water is used to maintain a Running water is used to maintain a concentration gradient and to concentration gradient and to improve the diffusion rate of improve the diffusion rate of chemicals from the emulsion to chemicals from the emulsion to waterwater

Factors affecting Factors affecting washing efficiencywashing efficiency Type of film emulsionType of film emulsion Condition of fixing solutionCondition of fixing solution Condition of waterCondition of water Agitation of waterAgitation of water Temperature of waterTemperature of water Washing timeWashing time

Thiosulphate level of < 3 Thiosulphate level of < 3 microgram/square cm is recomendedmicrogram/square cm is recomended

DryingDrying Removes all of the Removes all of the surface watersurface water and and

most of the water retained in the most of the water retained in the emulsionemulsion

Manual processingManual processing:- Keep the film in a :- Keep the film in a drying cabinet in which hot air is drying cabinet in which hot air is circulated. Takes about 10-15 minutescirculated. Takes about 10-15 minutes

Automatic ProcessingAutomatic Processing:- Surface water is :- Surface water is removed by squeegee rollers ; removed by squeegee rollers ; evaporation removes the emulsion water.evaporation removes the emulsion water.

25 sec in a 90 sec cycle25 sec in a 90 sec cycle

Factors affecting Factors affecting drying time & drying time & efficiencyefficiency

The wetness of the emulsion; The wetness of the emulsion; governed by: governed by:

i. hardness of the emulsion i. hardness of the emulsion

ii. emulsion thicknessii. emulsion thickness The drying conditions; governed by:The drying conditions; governed by:

i. Air humidityi. Air humidity

ii. Air Temperatureii. Air Temperature

iii. Air circulation – rate of changeiii. Air circulation – rate of change

SummarySummary

If a film is not processed properly If a film is not processed properly the whole effort made in the x-ray the whole effort made in the x-ray room or in the ward to obtain a room or in the ward to obtain a good radiograph will be lostgood radiograph will be lost

It is essential to pay similar It is essential to pay similar attention to film processing as attention to film processing as you pay at the x-ray room or in you pay at the x-ray room or in the ward when taking the x-ray the ward when taking the x-ray