This slide is prepared by Dr Parikha Rampal, Senior Resident, Department of Radiodiagnosis, ABVIMS & Dr RML Hospital, New Delhi

1. FILM PROCESSING
AND
AUTOMATED PROCESSORS
PRESENTER : Dr. Parikha Rampal
MODERATOR : Dr. Shahina Bano

2. FILM PROCESSING
Processing of an X ray film refers to the series of events that occur after a film
is exposed to x rays.
It involves the following steps-
• Development
• Fixing
• Washing
• Drying

3. DEVELOPMENT
Development is a chemical process that amplifies the latent image by a factor of millions to form a visible
silver pattern.
The basic reaction that occurs is the reduction of a silver ion into black metallic silver.
𝐴𝑔+
+ 𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛 → Ag
The process is initiated at the site of a latent image speck(commonly the surface of the silver bromide or
iodide crystal).
The developer acts as the reducing agent.
The silver atoms formed in the latent image catalyse the reduction of other silver ions in the grain by the
developing chemicals.
The silver thus formed is deposited at the latent image site gradually enlarging the initially microscopic black
spot into a visible black speck of silver in the emulsion.

4. CONSTITUENTS OF THE
DEVELOPING SOLUTION
Developing agents
Solvent
Accelerator
Buffer
Restainer or anti foggants
Preservative (sodium sulphite)
Sequestering agents

5. Developing agents
Usually a combination of hydroquinone and phenidone or metol is used
These agents are used together because they exhibit synergism as hydroquinone provides
high contrast and metol provides high speed.
The mixture results in a development rate greater than the sum of the developing rate of
each developing agent.
Hydroquinone + 𝐴𝑔+ → Ag + Quinone

6. Accelerators and Buffers
• Alkali: e.g sodium hydroxide, sodium carbonate &
borates.
• Adjusts the pH as required by the developer (10 to 11.5)
thereby accelearating the developing power of the
developing agent.
• Acts as buffer to control hydrogen ions liberated during
development reactions
• Preservatives
• Preservatives e.g. sodium sulphite act by decreasing
the rate of oxidation, especially of hydroquinone.
• Oxidation products of the developing agents
decompose in alkaline solutions to form colored
material that can stain the emulsions. These products
react rapidly with sodium sulphite to form colorless

7. Antifoggants
• Soluble bromides (KBr)
• Decrease the rate of formation of fog ( fog is the development of
unexposed silver halide grains that do not contain a latent image).
• They permit rapid development of the exposed grains at high
temperatures with minimized fog development.
• The development process itself produces potassium bromide which a
very effective restrainer but additional antifoggants are required in
modern machineries to permit very rapid development of the
exposed grains but minimize fog development.

8. Factors affecting development
Constituents of the developing solution
• Right concentration of agents
• Optimum pH of 9.5-10.7
• Proper concentration of restrainer or anti foggant
Developer Temperature - 22C (2-3C) above or below is acceptable
• Developing Time
It is the interval between the entry of specified part of film in the developer and exit
of the same specified part from the developer.

9. Factors affecting developing time
• Developer activity
• Type of film – Developing solution takes a longer time to enter a thick
emulsion than a thin one.
• Agitation - Gentle agitation of the developer is to be done when the film is
immersed in it, to prevent streaking.
But this is not a problem in automated processors because of constant
motion of the solution caused by the roller mechanism.

10. REPLENISHMENT
• The increase in bromide ion concentration due to reduction of silver ions is
mainly responsible for limiting the life of the developing solution.
• Thus replenishment is needed to maintain the bromide ion concentration,
developing agent concentration, preservative concentration and pH at a
constant level for the lifetime of the developer solution.
• Replenishment process depends on the number of films produced each
day.

11. Types of replenishment
• High volume systems - for busy departments where many films are being
produced in a day. Here replenishment is required due to weakening of
solution caused by excessive use.
• It is developing reaction dependent.
• Development reaction os as follows-
AgBr + 𝐻2O + 𝑁𝑎2S𝑂3 → 2Ag + HBr + HQS𝑂3Na + NaBr
Replenishment process here must compensate for the increase in bromide
and acid concentration by using alkaline agents and buffers.
A typical replenishment rate is to replace 60ml of developer with
replenisher for each 14x 17 inch film processed.

12. • Low volume systems where only few films are being processed. Here,
replenishment is required due to oxidation caused by air.
• It is oxidation reaction dependent
𝐻2𝑂 + 𝑁𝑎2𝑆𝑂3 + 𝑂2 → 𝐻𝑄𝑆𝑂3𝑁𝑎 + 𝑁𝑎𝑂𝐻 + 𝑁𝑎2𝑆𝑂4
• This oxidation reaction raises the pH of the developer by forming sodium
hydroxide and there is no production of bromide.

13. Fixing
• Fixing refers to stopping of the development and permanent fixation of
image on the film.
• The function of the fixing agent is to form water soluble complexes in
which silver ions are tightly bound. The soluble complex thus formed
effectively removes silver ions from the solution.
• 2 agents fulfil this requirement-
• Cyanides- poisonous hence not used
• Thiosulfates- used as sodium or ammonium salts called as “hypo”
• A typical reaction is –
Silver bromide + sodium thiosulphate → Silver thiosulphate complex +
Sodium bromide

14. • This way the excess silver halide is removed from the solution which if remained
would have impaired the immediate usefulness and permanence of the
developed radiograph.
Hardening agents
• For e.g. ; chromium or aluminium compounds are added to the fixing solution to
decrease the swelling of gelatin making it tough and more resistant to abrasion.
• The fixing solution also contains acid, stabilizers, and a buffer to maintain the
acidic pH level.
RINSING
• It is done before fixing the film by dipping the film in running water or 1% acetic
acid solution
• Done to remove developer from film so that acid in fixer is not degraded and
fixer can act uniformly.
• Rinsing is omitted in automatic processing

15. Washing
• The films must be washed with water to remove the fixing bath chemicals.
• If the retained chemicals remain they will react with the silver image to form
silver halide, thereby acquiring a brown tarnish.
• The general reaction is
Hypo + Silver → Silver sulphide(brown) + Sodium sulfite

16. Drying
• It is essential to dry the film before its removal for viewing in the view
box.
• The dryer consists of a blower, ventilation ducts, vented dryer tubes and
exhaust system.
• The blower draws in air from the room and passes it over the heating
coils.
• Heated air enters the ventilation ducts and dryer tubes and then blows
over the film.

17. Methods of processing
• Manual Processing
a) Time Temperature method
b) Modified time temperature method
c) Visual method
• Automated processors
• Day light processing
• Self developed films

18. Difference between manual and automated processors
Temperature
• Developing
• Fixing
• Washing
• Drying
Time
• Developing
• Fixing
• Washing
• Drying
Surface changes
Rinsing
Manual Processors
20C
20C
20C
43C
3-5min
2-10min
10-30min
10-20min
Manual agitation
Required
Automated Processor
35C
35C
37C
57C
25sec
21sec
9sec
20sec
Transport rollers
Not required

19. Automated processors
ADVANTAGES
• It shortens the total processing time to about 90 seconds.
• It improves the quality control by more precise temperature regulation and
replenishment in the automatic processor.
• Compact in size as smaller darkroom space is required.
• Density and contrast is constant
• Produces a dry radiograph immediately.
DISADVANTAGES
• Artefacts caused by rollers
• Expensive and requires maintenance
• Requires manual processing as a backup in case of a breakdown.

20. Structure and working of an automated processor
• The exposed film is loaded at one end and processed film is received at the
other.
• It consists of 4 chambers-
• Developer
• Fixer
• Washer
• Dryer
A series of rollers are
Present which transport the
Film from the loader to the
various sections.

21. Various systems of automated processors
• Film feed section
• Transport system
• Temperature control system
• Recirculation system
• Replenishment system
• Dryer system
• Electrical system

22. Film feed section
As the film is fed to the processor, a cycle of events begins-
• Drive motor is energized
• Safelight above the feed ray is extinguished
• Developer and fixer replenisher pumped into the tank.
• Drier heater energized
• Wash water flow rate is boosted.

23. Film transport section
• A system of rollers moves the film thorough the developer, fixer,
washing and drying sections of the processor.
• It also acts as a squeegee action to remove excess chemicals from the
film.
• The transport system consists of the following-
• Entrance roller – They grab the film and draw it into the developer.
When the film is completely into the developer tank, the bell rings or
the light flicks on.

24. • Transport rollers (vertical or deep racks) -move the film into and
through the solution and the dryer. They use a turn around assembly at
the bottom of the tank to turn the film direction upward.
• Crossover assembly - move the film from the developer from the fixer
tank and from the fixer to the wash tank and forces solution from the
film back into the tank it came from.
• Squegee assembly - moves the film from the wash tank to the dryer
and helps remove excess water from the film.

25. Factors affecting fixing solution

26. Water system
• It has 2 functions-
• Washing the film – removes the last traces of processing chemicals and
prevents fading or discoloration. This enables long term storage capability.
• Temperature control – maintains developer, fixer, washer and dryer
temperature. Process Temperature
Developing 35C
Fixing 35C
Washing 32-35C
Drying 57C

27. Circulation system
• It agitates the developer solution with the help of recirculation pumps.
Agitation helps keep the solution in contact with a heater element in the
bottom of the tank and prevents layering of chemicals.
• It removes the reaction particles by the use of a filtration system.
• It helps to stabilize the developer temperature.
• Rate of circulation of water required to wash the residual fixer is
12litres/minute.

28. Replenishment system
• The levels of fixing and developing solutions drop as the film is processed.
This system helps to replace the lost chemicals.
• The microswitch of entrance rollers starts the replenishment pump and
stops when the film exits the entrance rollers.
• Typical replenishment rate - 60-70ml of developer, 100-110ml of fixer for
every 14 inch of an x ray film.

29. Types of replenishment
• Volume replenishment – A specific volume of chemicals is relaced for each
film that is processed.
• Flood replenishment – Periodically replaces chemicals regardless of the
number of films processed.

30. Dryer system
• This system dries the film before its removal into the viewbox.
• It consists of a blower, ventilation ducts, vented dryer tubes and exhaust
system.
• Blower draws in air from the room and passes it over the heating coils.
• Heated air enters the ventilation ducts and dryer tubes and then blows
over the film.
• Moist warm air is vented out.

31. Thank You