Processing the Latent Image

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Processing the Latent Image

• Bushong Ch 12

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Purpose of Film Processing

• Change silver halide crystals from film emulsion
  (after exposure to x-ray or light photons) to
  black metallic silver.
• Latent image (invisible until processed) is
  developed into a Manifest image.
• Improper or careless processing can cause poor
  diagnostic quality.

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Processing Sequence

• Wetting
• Developing
• Rinsing in stop bath

• Fixing
• Washing
• Drying

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Manual Feed Processor
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Hand Processing in the Early years

• Strong smell of chemicals
• Messy
• Time comsuming

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1956 first roller transport6 minute processing
time
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Processing Time
3 minutes 90 seconds
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Processing FilmTable top Processors
Can process as fast as 60 seconds
TABLE TOP PROCESSOR
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Daylight Processor
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AUTOMATIC PROCESSING

• TRANSPORTATION SYSTEM
• DEVELOPER
• FIXER

• WASHER
• DRYER
• REPLENISHMENT SYSTEM

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PROCSSING CHEMICALS

• Solutions are PRE- MIXED
• Outside Company usually provides service-
• Weekly or monthly
• Solutions should be replenished as necessary
  changed regularly
• Solutions must be monitored (Daily QC strip).

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Automatic Processor
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Processor Chemistry Overview

• Developer converts latent image into manifest
  image
• Fixer clear the film of unexposed, undeveloped
  silver bromide crystals, promotes archival
  quality
• Wash rid the film of residual chemicals

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First Step

• Wetting the film to swell the emulsion

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Developer Solution(6 Ingredients)

• Reducing Agent reduce exposed silver halide to
  black metallic silver
• -Hydroquinone (Blacks)
• -Phenidone (Grays)
• 2. Activator softens gelatin, maintains
  alkaline pH (increase pH)
• -Sodium Carbonate

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Developer Solution

• 3. Hardener prevents damage to the film from
  over swelling of gelatin in automatic processors.
• -Gluteraldehyde
• 4. Preservative Antioxidant that prevents
  oxidation of developer
• -Sodium Sulfite

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Developer Solution

• 5. Restrainer prevents chemical fog protects
  crystals from chemicals
• -Potassium Bromide
• 6. Solvent dissolves ionizes the developer
  chemicals
• -Water

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Fixing

• Once development is complete, the film must be
  treated so that the image will not fade but will
  remain permanently.
• Fixing
• First step of fixing is the stop bath to stop
  the developer chemicals

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Fixer Solution(5 Ingredients)

• Clearing Agent dissolves undeveloped silver
  halide
• -Ammonium Thiosulfate
• 2. Tanning Agent shrinks, hardens, preserves
  emulsion
• -Aluminum Salt

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Fixer Solution

• 3. Activator neutralizes developer, maintains
  acidic pH (decrease pH)
• -Acetic Acid
• 4. Preservative prevents oxidation, prolongs
  solution life
• -Sodium Sulfite
• 5. Solvent dissolves other ingredients
• -Water

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Wash

• Rid the film of residual chemicals
• Residual chemicals on the film will discolor
  radiograph over time.
• Cold water processors are less efficient in
  removing chemicals Warm water processors much
  better.
• Agitation during wash process is essential

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Fixer or Hypo Retention(Not Washed Off)
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Wash Dryer Systems

• Wash Provide thorough removal of chemical
  solutions from the film.
• -Archival film quality
• Dryer Removes water from film by blowing warm,
  dry air
• -Between 120 degrees 130 degrees F.

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Transport System in Automatic Processors

• Conveys the film through different solutions
  (sections) by a series of rollers driven by
  gears, chains sprockets.
• Done at a prescribed speed determines length of
  time the film is in each solution

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Transport System Components

• Feed Tray
• Rollers (Different Assemblies)
• 1. Entrance
• 2. Deep Racks
• 3. Turnaround
• 4. Crossover
• 5. Squeegee
• 6. Dryer
• Receiving Bin

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Transport System (Rollers)
Entrance
Crossover
Feed Tray
Squeegee
Deep Racks
Dryer
Turnaround
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Feed Tray

• Engages a micro switch to start the replenishment
  system.
• Always feed the film evenly, using the side rails
  of the feed tray. Alternate sides from film to
  film.
• Short side of film against the side rail for
  proper replenishment.

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Replenishment System

• Main function Keep solution tanks full and
  assure proper solution concentration.
• As film is introduced into processor, sensor
  initiates solution replenishment
• Right wrong way to feed in film
• -Feed in along short edge

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Replenishment tanks
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Temperature Regulation

• Main function To control the temperature of each
  section of the processor.
• Developer most important solution to regulate
• Usually between 92 degrees and 95 degrees
• Thermostatically controlled

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Recirculation System

• Provides agitation necessary for uniform solution
  concentration

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Silver Recovery

• About ½ of the films silver remains in the
  emulsion after exposure processing.
• Other ½ (unexposed silver) is removed from the
  film during fixing process.
• Silver is toxic to public water supply must
  have proper disposal.

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Darkrooms Still Necessary?

• Darkrooms are necessary for manually fed
  processors and daylight processors.
• -Loading automatic film processor magazines.
• Necessary for conducting certain quality control
  tests (daily sensitometric strip).

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Film Storage

• Clean, dry location
• 40 60 Humidity 70 º Fahrenheit
• Away from chemical fumes
• Safe from radiation exposure
• Standing on edge
• Expiration date clearly visible

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WILL THIS WORK ????
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Safe Light

• 15 Watts
• Red filter
• Must be 3-6 feet from counter top or feed tray of
  processor
• Used to be amber or orange filter

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Film Identification

• Pt name
• Exam date time
• Pt x-ray number
• Pt Birthday/DOB
• Rt or Lt marker
• Optional
• Exam type
• Dr. Name

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FILM ID PRINTER
Name of patient place on top Cassette is
flashed with name can be done before or after
image is taken Must be done BEFORE PROCESSING FIL
M
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TABLE TOP FILM DUPLICATORto MAKE COPIES OF FILMS
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Digital Image Printing

• Dry processing no chemistry
• No darkroom
• Less environmental impact
• Reduce costs

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Dry Processing

• Uses a laser to form a latent image and heat to
  process the image
• Two types
• Photothermography (PTG) Uses a laser to record
  the image signal (latent image) then film is
  heated to produce the manifest image
• Thermography (TG) Uses modulated heat source to
  produce the image directly

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Questions?