Film processing Flashcards
The darkroom
Where film processing occurs
Should be:
Clean
Organized
Light-proof
Need appropriate safe lights
Film processing solutions
Both manual and automatic processing have five basic steps
Developing
Rinsing
Fixing
Washing
Drying
Important to follow manufacturer’s instructions when preparing chemicals
Try to keep solutions at constant temperature
Low temperature = sluggish chemicals = under developed or under fixed radiograph
If too hot the opposite effect happens
All chemicals should be kept at the same temperature
If not – Reticulation can occur
Mottled density due to irregular expansion and contraction of film emulsion
Developer purpose
Converts latent image to visible image
Does this by converting silver halide crystals within film to black metallic silver
Rinse bath
Purpose:
Stop the developing process
Rinses off developer so prevents carryover contamination of fixer by developer solution
Consists of circulating water
Film is rinsed for 30 seconds
Automatic processors omit this step
Excess developer removed through squeegee rollers prior to entering fixer
The fixative
Purpose:
Remove unexposed silver holiday crystals from film
Hardens the gelatin coating so can be dried without damage to film surface
If unexposed crystals are not removed they would discolor and darken with exposure to light
Water bath
Purpose:
To remove processing chemicals from film surface
If not washed properly for a long enough time the image will eventually discolor and fade
Films should be washed in circulating water so both surfaces receive fresh water continuously
Automatic processors keep a constant flow of temperate water through and around the wash rack and film
Solution replacement
Exhausted chemicals are a primary cause of poor quality radiographs
Chemicals that have lost potency will produce radiographs that have increased film fog and decreased contrast and density
Biological growth in film processing
Manual processing tanks can be a breeding ground for bacteria, algae, and fungi
Originate from air, personnel or incoming water supply
Can cause corrosion of metal tanks and artifacts on films
Inhibited by good housekeeping
When changing chemicals, tanks should be scrubbed with 1% bleach
Waterlines should have a filter added to remove unwanted organisms
Film processing techniques
Manual or Automatic
Manual takes approximately 1 hour to produce a finished product
Automatic can take as little as 90 seconds
Both can produce a quality radiograph
Manual processing
You may read up on on your own
Automatic film processors
Involve same routine as manual processing except operate at higher temperatures and rinse step is omitted
Carry over chemicals are removed by compression of film by squeegee rollers
Film is transported through processor by a series of rollers
Rollers move at a constant speed to ensure proper processing
Silver recovery
Silver is a valuable natural resource and should be recycled
Environmentally wise
Economically prudent
During processing silver is either:
Contained in emulsion of x-ray film as black metallic silver
Removed by the fix solutions
Both can be recovered
Film identification
Must be properly labeled so can be identified at later date
Additional radiographs need to be taken to evaluate healing or advancement of disease
Without proper labeling, progressive evaluation is difficult
Legal considerations
If medico-legal problem were to arise, a radiograph improperly labeled is of no value in a court of law
Legally accepted radiographs must have the label imprinted within the film emulsion
Minimum legal info required
1.Name of hospital/practice or veterinarian
2. Date radiograph was taken
3. Complete patient identification
* Usually a hospital case or medical record file number
4. A Left or Right marker
Lead markers
- Simplest method
- Uses lead letters and numbers
- Placed in holder or taped directly to cassette
- Lead absorbs the primary radiation so film directly under is
unexposed and transparent - Disadvantages
- Loss of lead letters
- Limits tight collimation
- Easy to forget
Radiographic markers
Right and left markers are essential
Identify right and left limb
Right and left side of central body
Front and hind limb markers also essential for large animal
Distal limb below carpus/tarsus are identical and can only be differentiated by label
Time sequence labels
For special procedures to indicate time lapse
Following administration of contrast media
Mitchell markers
Identify direction of x-ray beam
Has bead in central ball
