-
Darkroom Temperature
- 60-70deg F
- 40-60% Humidity
-
Latent Image
Invisible image after exposure to radiation beam
-
Manifest Image
Visible image after processed
-
Film
- 2 Parts
- Base and Emulsion
- Surrounded by protective covering of gelatin called Supercoating
- 95% Silver Halide
- 5% Silver Iodide
- Double Emulsion (on both sides)
-
-
Photoelectric Interaction
Transfer of info from radiation to emulsion
-
Ionized Silver Halide Crystals
Change to black grains during developing
-
Screen-Type Film
- Less rads exposure to patient
- Sensitive to light
-
Screen-Type Film
3 Characteristics
- Contrast (High = B&W, Low = gray shaded)
- Speed (sensitivity)
- Light absorption (high speed = thick emulsion, lg crystals, decreased visibility)
-
Spectral Absorption or
Spectral Matching
Use of film whos sensitivity matches light spectrum of screen
-
Blue Sensitive Film
Amber safe light
-
Green Sensitive Film
Red-brown filter safe light
-
Film Fog
Undesirable increase of density of emulsion
-
Intensifying Screen
- 4 Layers
- Protective coating, Phosphor, Reflective layer, Base
- Higher speed of screen = more density less detail
- Must contact entire film
-
Resolution
- Ability to consistantly produce image of an object
- High speed = low resolution
-
Chemical Processing
- Change Latent Image (non-visible) held in film emulsion
- Into Manifest Image we can see
-
-
Film Processing
Developer
Convert exposed silver halide into metallic silver
-
Film Processing
Fixer
- Removes unexposed silver halide from emulsion
- Hardens gelatin to make permanent record
-
Film Processing
Wash
Removes fixer
-
Film Processing
Dry
Prepares for viewing
-
Developer Agents
- Phenidone
- Elon
- Hydroquinone
-
Silver Halide
Electrical Charges
- Unexposed = positive
- Exposed = negative
- Developer = negative
-
Auto Processor
- Transport
- Water
- Recirculation
- Replenishment
- Dryer
-
Film Artifacts
- Physical, Mechanical, Chemical
- Brown stain = old developer
- Multicolor = poor rinsing
- Yellow = exhausted fixer
- Reticulation = web-like = extreme diference in solutions
-
Sensitometry
- Study of how film responds to rads exposure and processing conditions
- 3 Methods:
- Step-wedge pentrometer and medium exposure
- Sensitometer exposure
- Pre-exposed strips
-
|
|
