Image Processing Flashcards
If film is exposed to white light or ionizing radiation, what 2 options can be used to prevent that?
- Daylight system – consists of an automatic film unloader that takes the sheet of film out of the cassette and moves it directly into a film processor.
- Darkroom - functions to protect the film from white light and ionizing radiation during handling and processing
Darkroom function
Protect film from:
Visible light
• Ionizing radiation
• Excess heat and humidity • Static electricity
• Pressure
• Chemical fumes
Film processing functions
Converts latent image to manifest image
• Preserve image for permanent storage
What are the 2 basic methods used for film processing?
Manual – film is transported through each step by hand.
• Automatic – electro-mechanical device that transports film through various solutions
Processing chemistry developer
Most important processing step
Converts latent image to manifest image
Uses oxidation/reduction reaction
Development
First stage in processing of the radiograph
Amplifies latent image by 100,000,000
Converts invisible latent image into visible form
Latent image
Bromide ions react with silver ions to form metallic silver ions, and eventually get a cluster of them
Developer or Reducing agents
Phenidone - Fast acting producing optical densities under 1.2
Hydroquinone - slow acting, producing optical densities above 1.2
Uses Synergism or Superadditivity
Most hazardous processing solution, very high pH
Accelerator, Activator, or Buffering Agents
Maintain alkaline medium
Soften and swell film emulsion - gives more area for develop solution to do its activity
PH scale
Developer should have a pH of 10-11.5
Restrained, regulator, anti-foggant, or starter
Restrains the action of developing agents to help prevent chemical fog
Preservative
Helps prevent premature oxidation
Premature oxidation can be caused by:
Aerial- contact with air
Internal - contact with other ingredients in developer
Photo - exposure to light
Hardener
Keeps film emulsion from sticking to rollers in processor
Weaker hardener than in fixer solution
Glutaralehyde is used
Solvent
Other components mixed with solvent, creates developer solution
Water is used
Sequestering agent
Used for developer solutions mixed from concentrate
Keeps impurities in tap water from oxidizing reducing agents