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03 xray film etc
1. X-ray Equipment
The X-ray machine
Grids
Film and cassettes
Processing
2. X-ray Film
Types of film
Handling of film
Choosing film
Depends on size, subject, machine
3. X-ray Film
Purpose:
provides permanent record of x-ray image
Fluoroscopy/ultrasound traditionally transient
Newer technology allows video capture
4. X-ray Film
Composed of silver halide crystals on
plastic sheet
Crystals interact with:
Ionizing radiation (including x-rays)
Visible light
Pressure
Bending
Moisture
5. X-ray Film
Composition
Similar to photographic film
Silver halide emulsion on both sides of
polyester base
Most film bases are blue tinted
Pleasing to the eye
6. X-ray Film
Latent image
Formed by absorption of light photon by
silver halide crystal
Energy of photon dislodges an electron
The electron causes positively charges
silver ions to join into a silver atom
8. X-ray Film Characteristics
Film density
Measure of film blackening
Equals log of incident light intensity
divided by transmitted light intensity
21. X-ray Film Types
Non-screen film
More sensitive to ionizing radiation
Allows for finer detail
Requires more exposure
Requires thicker emulsion and thus manual
processing
Ex.: dental films
22. X-ray Film Types
Screen film
Crystals also sensitive to fluorescent light
from intensifying screens
Less sensitive to direct ionizing radiation
Benefits
Less exposure
Drawbacks
Loss of image definition
23. X-ray Film Types
Screen film
Blue sensitive film
Film responds to ultra-violet, violet and blue light
emitted from screen
Green sensitive film
Respond to screens that emit 60% green and 25%
blues
Relatively newer technology using rare earth
phosphors
24. X-ray Film Types
Blue and green screen can be used with
either blue or green sensitive film
But most efficient if film is sensitive to light
emitted by screen
25. X-ray Film Types
Screen film
Standard silver halide crystals absorb violet to
blue light
“Ortho” film
Thin layer of green absorbing dye transfers energy
to silver halide crystals
Therefore extends sensitivity of film into green
wavelengths
“Pan” film
Red absorbing dye
26. X-ray Film Types
Screen film
Crossover or punch-
through effect
Decreased detail of
radiograph due to
additional exposure to
light from screen on
opposite side
28. Intensifying screens
Thin cleanable sheet of phosphor crystals
which lies adjacent to the film within the
cassette
Purpose:
To decrease amount of radiation required for
a diagnostic radiograph
Able to use lower mAs (faster exposure)
29. Intensifying screens
4 layers of a screen
Base
Substrate for phosphor crystals
Reflecting layer
To reflect light back toward film
Phosphor layer
Must be uniform and flexible (to avoid cracking)
Protective coating
31. Intensifying screens
Intensification factor
Direct film requires roughly 34 times more
exposure than screen film
A 0.1 second exposure on screen film
would require 3.4 seconds on non-screen
film
33. Intensifying screens
Phosphor layer
Calcium tungstate and barium lead sulfate
emit blue light
Rare earth screens more green light
emitted
Extremely important to keep screens
clean and undamaged
34. Film holders
Cassettes
Must be rigid, durable, light-proof and
transparent to x-rays on at least one face
Provide housing for intensifying screens and
film
Must be maintained well
36. Film holders
Cardboard or light-proof paper
Use for non screen films
Light-weight
Low/no maintenance
37. Manual Film Processing
Dark room
Must be light-proof
Tight seal of door
Stray light may fog film
Must be not be exposed to radiation
Adjacent x-ray machine may cause fogging of film
38. Manual Film Processing
Dry area
Film storage
Use lightproof cabinet
Cassette loading
Safelight
Must be of visible spectrum that will not fog film
Red part of spectrum
42. Manual Film Processing
Developing
Chemical process dependant upon time and
temperature
Ideally 5 minutes in developer tank at 68 degrees
Fahrenheit
High temperature causes reticulation
Artifact caused by slipping of emulsion layer
44. Manual Film Processing
Fixer
Converts undeveloped silver bromide crystals
into a solution that is washed away
Black metallic silver left on film
Also hardens film
45. Manual Film Processing
Minimum fixing time
Determined by change in film appearance
from cloudy to clear (clearing time)
46. Manual Film Processing
After clearing, film should be left in for
twice that amount of time
Ex. 2 minutes to clear = keep film in 4
additional minutes
Clearing time should not exceed 2-3 minutes
49. Automatic Film Processing
Benefits
Compact size
Faster
More consistent
Time and temperature controlled
Produces dry radiograph immediately
50. Film Processing
Solutions need to be specially disposed
due to contents
Treated as hazardous waste in many
including California