Film%20Processing

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Film Processing

• Chapter 7

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Film Processing

• Proper film processing is vital to the production
  of a quality radiograph.
• Processing can be done manually or automatically.
  

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The Darkroom

• Three qualities of a good darkroom
• 1. Clean
• 2. Organized
• 3. Lightproof

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Darkroom continued

• Individual darkrooms may vary in design, but
  should all possess the same qualities.
• Should be separate from the radiographic suite
  and should be used for only one purpose,
  processing exposed radiographs.

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Darkrooms

• Most of work in darkrooms is with minimal light
  (hence the word Dark).
• Therefore layout should be such as to help reduce
  possibility of film damage.

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Darkroom cleanliness

• Should be clean as only room where intensifying
  screens and x-ray film is exposed to the air.
• Should have proper climate control. Dont want
  too humid.
• Why?

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Darkroom Organization

• Should be organized so that all equipment can be
  located quickly and easily.
• Should be two sides to the darkroom a dry side
  and a wet side.

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Dry Side of Darkroom

• Where cassettes are unloaded and reloaded.
• Should have countertop large enough to
  accommodate the largest cassette in an open
  position.
• Countertop should be easy to clean.
• Nothing wet should be brought to the dry side.

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Dry side of Darkroom continued

• Customary to store film under the dry table in a
  bin or cupboard.
• How should film be stored?
• Film hangers for each size film should be hung
  above the table on the dry side.

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Film Hangers

• Available in two designs
• Channel Hangers
• Tend to retain water and chemicals and need
  special cleaning and drying to prevent
  contaminations of the dry side.
• Film must be removed from the channel hangers in
  order to be dried.
• Clip Hangers
• More fragile than channel hangers.
• Clips can become weakened over time.
• Lose ability to stretch the film.
• Can puncture the corners of the film.
• Can scratch other films.

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Film Hangers
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Wet Side of Darkroom

• Where actual chemical processing occurs.
• Hand or manual processing consists of three
  tanks.
• Developer
• Water
• Fixer

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Manual processing tanks

• Can be individually free standing.
• Fixer and Developer can be placed in one large
  tank filled with thermostatically controlled
  water.
• One of most important pieces of equipment is
  thermometer when using manual processing.
• Processing chemicals must be certain temperature.

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Wet side/ Drying area

• Film drying area can consist of a film drying
  rack or a drying cabinet.
• Drying rack should be dust free.
• Drying cabinet is a heated forced-air unit that
  hastens the drying process.
• Viewing screen is recommended on wet side of
  darkroom.

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Darkroom Lightproofing

• Light leaks can cause film fog.

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Light leaks

• May be hard to perceive.
• Common sources of light leaks.
• Entrance to dark room
• Ceiling
• From adjacent rooms

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Lightproofing continued

• Entrance should have double door or revolving
  door preferred but not always practical.
• Make sure that door fits tightly into its frame.
• Use weather stripping if needed to ensure light
  proofing.
• Make sure that door LOCKS!

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Ceiling/walls/etc

• Suspended ceiling may have light leaks from
  adjacent rooms.
• Walls should be light color as gives more
  reflection from the safety light.

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Darkroom Safelight

• Appropriate lighting in darkroom is crucial to
  good film development.
• Safe light means light will not affect the
  film.
• Safelights use a small-wattage bulb and a special
  filter to eliminate the light from the blue and
  green spectrum.
• Bulb should be 15 watts or less.

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Safelights continued

• Should be positioned so that darkroom work can be
  performed without fumbling.
• Two types of safe-lighting
• Direct
• Diffused light that shines directly over a work
  area such as the dry or wet side of the darkroom.
• Indirect
• A filtered light directed toward the ceiling and
  reflected over the entire room.
• Two types of lighting may be combined.

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Safelights continued

• Safelight should never be closer than 4 feet to
  work area.
• If too close may cause some film fog.

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Film-Processing Solutions

• Film processing consists of five basic steps.
• 1. Developing
• 2. Rinsing or stop bath
• 3. Fixing
• 4. Washing
• 5. Drying

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Chemicals

• May be purchased in a variety of ways (liquids or
  powders).
• May be in concentrated form and need to be
  diluted or mixed.
• Preparing chemicals correctly is important or
  resulting solution may adversely affect the
  radiographic product.

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Chemicals continued

• Chemicals should be kept at specified room
  temperature.
• Variances may adversely affect the radiographic
  product.
• Too low temps, some of the chemicals may become
  sluggish in action and produce an under-developed
  or under-fixed radiograph.
• Too high temps, may be too hot for manual
  control.

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Chemicals

• All chemicals should be kept at same temperature.
  
• Variances in temperature between the chemicals
  can result in film reticulation.
• Reticulation- a darkroom artifact produced by
  variable chemical temperatures that cause
  irregular expansion and contraction of the film
  emulsion, resulting in a mottled density
  appearance.

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Reticulation
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The Developer

• Developer-a chemical solution that converts the
  latent image to a visible image.
• Primary function is to convert the exposed silver
  halide crystals to black metallic silver.
• Developing time is specified by chemical
  manufacturer. Be sure to know this in your
  practice.

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The Developer Continued

• Developer temperatures affects the developing
  time.
• Time-temperature developing is preferred over
  visual inspection when using manual processing.
• Developer consists of developing agents,
  accelerators, preservatives, restrainers,
  hardeners, and a solvent.

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Developing Agents

• Composed of chemical compounds such as
  hydroquinone or phenidone that can convert
  exposed grains of silver halide to black metallic
  silver. The developing agent has little or no
  effect on the unexposed silver halide crystals.

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Accelerators

• Chemicals that increase the activity of the
  developer. Substances such as potassium
  carbonate or sodium carbonate are used to
  increase the pH to an alkaline range of 9.8 to
  11.4. This increase in pH causes the emulsion to
  swell and soften, allowing the developing agent
  to work more effectively.

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Preservatives

• Prevent the rapid oxidation that can occur with
  alkaline developing agents. They also help
  maintain a stable development rate and prevent
  straining of the emulsion layer.

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Restrainers

• Limit the action of the developing agent to the
  exposed silver bromide crystals in the film.

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Hardeners

• Often added to developers in automatic
  processors. They harden the film during
  processing and prevent excessive swelling of the
  emulsion. If the gelatin emulsion were to swell
  extensively, it could be damaged by the rollers
  in the automatic processor.

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Solvent

• Consists of water to dissolve the chemicals.

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The Rinse Bath

• After film is in Developer, retains a substantial
  amount of developer in the gelatin.
• If film went straight from developer to fixer,
  then alkaline developer would neutralize acid of
  the fixer.
• Rinse bath serves to stop the developing process,
  rinse the developer from film, and prevent
  carryover contamination to the fixer.

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The Fixer

• Serves two basic functions
• 1. Clears unexposed silver halide crystals from
  the film.
• 2. It hardens the gelatin coating so that it can
  be dried without damaging the film surface.
• General guideline is that film should be fixed
  for twice the development time.

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Fixer consists of

• Clearing or fixing agents
• Dissolve and remove unexposed silver halide
  crystals from the film emulsion.
• Preservatives
• Prevent decomposition of the fixing agent.
• Hardeners
• Prevent excessive swelling of gelatinous emulsion
  during fixation procedure and softening during
  the wash procedure. Shorten drying time.

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Fixers Composition Continued

• Acidifiers
• Compounds that accelerate action of other
  chemicals and neutralize any alkaline developer
  possibly carried over into the acidic fix
  solution.
• Buffers
• Chemical compounds added to the solution to
  maintain the desired pH. Help to stabilize the
  acidity against the addition of alkaline
  developer carryover. Without buffer, developer
  would neutralize fix solution. Can also prevent
  sludge formation in the fix bath.

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Fixer Composition continued

• Solvent
• Consists of water.
• Purpose is to dissolve other ingredients and
  assist in the fixing agent to diffuse into the
  emulsion layer of the film.
• Carried silver halide away from film.

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The Wash bath

• Wash portion is vital to a quality radiograph.
• If film is not washed properly for a long enough
  period of time, the image will eventually
  discolor and fade.
• Films should be washed in circulating water so
  both surfaces of film receive water continuously.
  
• Manual processing wash time is recommended 20-30
  mins.

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Wetting Agent

• Water spots and streaks is a problem with drip
  drying films in manual processing.
• A wetting agent bath can hasten drying process.
  Called Surface-tension reducing agent.

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Water spots/bubbles
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Solution Replenisher

• In manual processing, chemical depletion is a
  natural result of chemical carryover into
  adjacent tanks.
• Up to 60 mL of developer can be carried on a film
  into rinse bath.
• Developer and fixer need frequent replenishment.
• Replenishment is available in powder and liquid
  concentration form.
• Generally will have higher concentration than
  original solution in order to maintain chemical
  potency.

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Solution Replacement

• Used/old chemicals are primary cause of
  poor-quality radiographs.
• Check chemicals every time PRIOR to development
  of film.
• Developer may turn from green to brown.
• In general, chemicals should be changed every 4-6
  weeks.
• Depends on frequency of use.

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Biologic Growth

• In manual processing may have bacterial growth.
• Need to be controlled.
• When changing chemicals, clean tanks as well.
• Wash tank of automatic processor should be
  drained at end of day to prevent growth.

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Film-processing Techniques

• Two types of processing
• Manual
• May take up to an hour to develop
• Automatic
• Generally can be processed in 90 seconds
• Both types of processing can produce a quality
  radiograph, it is a matter of preference.

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Manual-Processing Procedure

• Step 1.
• Preparation
• Make sure that chemicals should be at proper
  temperature and should be stirred.
• Step 2.
• Unloading the cassette
• Take care when unloading cassette. Careful with
  fingernails! (Why?)
• X-ray film should be handled by corners and edges
  only.

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Manual Processing Procedure cont.

• Step 3.
• Loading the film on a hanger
• Clip hanger load the bottom first
• Stretch to bounce a coin on it
• Will prevent the film from touching other films
  or walls while developing
• Channel hanger
• Held in one hand while sliding the film into the
  channels with the other
• All sides and corners should be checked for
  proper placement
• Once in place, the top can be closed

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Manual Processing Continued

• Step 4.
• Developing the film
• Immersed in developing tank and agitated two or
  three times.
• Step 5.
• Rinsing the film
• Remove film from developer.
• Immerse in rinse bath and agitated for 30
  seconds.

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Over-rinsed film
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Manual Processing Cont.

• Step 6.
• Fixing the Film
• Removed from rinse tank and immersed in the fix
  tank.
• Step 7.
• Washing the Film
• Removed from Fixer and washed 20-30 mins.

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Left in Fixer
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Under washed film
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Manual Processing cont.

• Step 8.
• Optional Final Rinse
• Application of a wetting agent.
• Step 9.
• Drying the film
• Film is dried in dust-free environment to prevent
  artifacts.
• Make sure well seperated.

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No Final Wash Applied
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Automatic Processing

• Advantages over the manual method.
• 1. highly standardized procedure with consistent
  quality.
• 2. can produce a dry radiograph in a short amount
  of time.
• 3. reduces labor time of employees.
• 4. smaller darkroom space required.

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Automatic Processors

• Roughly same procedure as manual processing.
• Operate at higher temps and have specifically
  formulated chemicals to speed development.
• Film is transported through processor by a series
  of rollers.

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Automatic Processor continued

• Chemicals still need to be checked and processor
  warmed up.
• Make sure that films are fed one at a time to
  prevent sticking together.
• Will be signaled by the processor when can feed
  next film.

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Stuck in processor
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Films stuck together
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Folded Film
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Processing Chemicals

• In automatic processing, chemicals are
  replenished as they are used.
• Temperature is also constantly monitored.
• Chemicals are re-circulated.

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Processor Maintenance

• Can be serviced by a professional
• Quick tech checks
• Check solution levels
• Check replenishment rate
• Check temperature
• Check roller operation
• Rinse and wipe rollers racks
• Clean tanks

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Silver Recovery

• Recycle to obtain silver from development
  process.
• 3 methods of silver recovery
• 1. Metallic replacement
• 2. Electrolyte recovery
• 3. Chemical precipitation

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Film Identification

• Proper Labeling and identification of x-ray films
  is VITAL!!!!!
• All labeling systems should include.
• 1. name and address of hospital practice or
  veterinarian.
• 2. date the radiograph was take.
• 3. patient identification including name of the
  owner and patient name, age, sex, and breed.

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Lead Blockers

• Identification can be done via lead lettering,
  lead impregnated tape, or photoimprinting labels.
  

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Other markers

• Right (R) and Left (L) markers are essential to
  identify size and position of image on
  radiograph.
• May need to label front and rear as well
  especially in large animals.
• If label not a part of film itself,then can add
  later with marker, or scratching into film while
  still wet.

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See markers
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Film Filing

• Organized film filing system is needed in
  veterinary practice.
• Must be placed in suitable holder and filed
  appropriately.
• Should be labeled, numbered if necessary and
  filed correctly for easy future reference.
• X-ray logs also help with film identification.