processing chemistry

• wetting: swells the emulsion to permit subsequent chemical penetration
• developing: produces a visible image from the latent image
• rinsing in stop bath: terminates development and removes excess chemical from emulsion
• fixing: removes remaining silver halide from emulsion and hardens gelatin
• washing: removes excess chemicals
• drying: removes water and prepares radiograph for viewing
• approx time for wetting in manual processing: 15 seconds
• approx time for developing in manual and automatic processing respectively: 5 minutes, 22 seconds
• approx time fro rinsing in stop bath for manual processing: 30 seconds
• approx time for fixing for manual and automatic processor respectively: 15 minutes, 22 seconds
• approx time for washing for manual and automatic processor respectively: 20 minutes, 20 seconds
• approx time for drying for manual and automatic processor respectively: 30 minutes, 26 seconds
• FILM PROCESSING: Refers to the series of steps that converts the latent image into the visible radiographic image
• In handing the different Processing Chemistry:

  1. Wear a proper mask that reduces inhalation of fumes.
  2. Wear nitrile gloves (do not use surgical gloves)
  3. Wear protective glasses (prevent chemical splashing into the eyes)
• pH level for all solutions: 0-14
• pH level for Developer: 10-10.5
• pH level for Fixer: 4-4.5
• Developer Temperature: 95-100F / 35- 38C
• Fixer Temperature: appx 94F
• Water Temperature: appx 94F
• Automatic processor; Dryer temperature: 120-150F (2.5kW)
• REPLENISHMENT RATE: amount of solution per tank
• DEVELOPER REPLENISHMENT RATE: 60-70 mL or cc / 14” film
• FIXER REPLENISHMENT RATE: 100-110 mL or cc / 14” film
• UNIVERSAL SOLVENT: WATER
• principal action of developing: to change the silver ions of exposed crystals into metallic silver which produces a visible image from the latent image
• REDUCTION: When an electron is given up by a chemical, in this case the developing agent, to neutralize a positive ion
• reducing agent: chemical responsible for reducing silver ion to metallic silver
• oxidation: reaction thaat produces an electron
• REDOX REACTIONS: Oxidation and reduction occur simultaneously
• developing agents: phenidone and hydroquinone
• Phenidone: Reducing agent; produces shades of gray rapidly
• Hydroquinone: Reducing agent; produces black tones only
• • principal component of developing agent: hydroquinone
• secondary constituents of developing agent: phenidone and metol
• SYNERGISM: occurs when the action of two agents working together is greater than the sum of the action of each agent working independently
• developing agents used in manual processing: metol and hydroquinone
• developing agents used in automatic processing: phenidone and hydroquinone
• Sodium Carbonate: helps swell gelatin; produces alkalinity; controls pH
• The developer contains alkali compounds, such as sodium carbonate and sodium hydroxide or potassium carbonate and potassium hydroxide