Processing Flashcards
What are the 3 types of conventional processing methods?
- Manual/wet
- Automatic
- Direct
Describe the manual/wet (conventional) processing method
Break plastic cover, then drop film out of plastic, rub with alcohol rub
Hold film with forceps by dot in the corner
Hold in developer for 5 mins at 20C
Wash for 10 seconds
Fix for 10 mins
Running water for 10 mins
Dry to get off excess fixer (dust free environment)
Describe the automatic (conventional) processing method
Unwrap exposed film
Hold in developer for 5 mins at 20C
Fix for 10 mins
Running water for 10 mins
Dry to get off excess fixer
What is the purpose of stage 1, development, during processing?
Stage 1: Development
The sensitized silver halide crystals in the emulsion are converted to black metallic silver to produce the black/grey parts of the image.
What is the purpose of stage 2, washing, during processing?
The film is washed in water to remove residual developer solution.
What is the purpose of stage 3, fixation, during processing?
The unsensitized silver halide crystals in the emulsion are removed to reveal the transparent or white parts of the image and the emulsion is hardened.
What is the purpose of stage 4, Washing, during processing?
The film is washed thoroughly in running water to remove residual fixer solution.
What is the purpose of stage 5, Drying, during processing?
The resultant black/white/grey radiograph is dried.
Name some requirements for manual processing
Carried out in a dark room
Absolute light-tightness
Adequate working space
Adequate ventilation
Adequate washing facilities
Adequate film storage facilities
Safelights- positioned 1.2m away from work surfaces with 25W bulbs suitable for the type of film being used
Processing equipment
Tanks containing various solutions
Thermometer
Immersion heater
Accurate timer
Film hangers
Name some constituents of fixer solution and their functions
Advantages of automatic processing?
Time saving – dry films are produced in about five minutes
The need for a darkroom is often eliminated
Controlled, standardized processing conditions are easy to maintain
Chemicals can be replenished automatically by some machines.
Disadvantages of automatic processing?
Strict maintenance and regular cleaning are essential; dirty rollers produce marked films
Some models need to be plumbed in
Equipment is relatively expensive
Smaller machines cannot process large extraoral films.
Advantages of self developing films?
No darkroom/processing facilities needed
Time saving (ready in about minute)
Disadvantages of self developing films?
Poor overall image quality
The image deteriorates rapidly with time
There is no lead foil inside the film packet
The film packet is very flexible and easily bent
These films are difficult to use in positioning holders
Relatively expensive
Advantages of digital processing?
No need for chemical processing, thus avoiding all conventional processing faults and the hazards associated with handling chemical solutions.
Easy storage and archiving of patient information and incorporation into patient records.
Easy transfer of images electronically.
Image enhancement and manipulation.
Phosphor plates have a wide latitude producing an acceptable image whether underexposed or overexposed.
Disadvantages of digital processing?
Large pixels result in poor resolution and structures may not be represented accurately
Conventional screens/monitors reduce or limit image quality.
Diagnostic image quality screens/monitors are required for optimal viewing.
Images need to be backed up to a separate storage area remote from the image-capture computer in case this computer fails.
Over-exposure and overloading of CCD sensors creating the phenomenon of blooming
Loss of image quality and resolution on hard copy print-outs when using thermal, laser or ink-jet printers.
Image enhancement and manipulation:
–operators need to understand how the image is created and being altered to avoid being misled
–time-consuming
–magnification is achieved by enlarging the pixels, but resolution is lost.
While manufacturers provide safeguards to prevent any tampering with original images within their own software, it is relatively easy to access these images using inexpensive third party software and then to change them
How does manual processing work?
Silver halide + X-ray
X rays not absorbed by soft tissues/air spaces
o X rays sensitise the silver halides
o Dip film in developer black silver
o Fix to plastic base
o Wash off excess
X rays absorbed by bone/teeth/metal
o X rays do not sensitise the silver halides
o Remove halide from base using developer
o Film remains translucent here
How does digital processing work?
o Direct or Indirect
o X-ray photons - Scintillation layer - photons converted to light - light interacts with silicon - charge packet in each individual pixel - latent image
