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