8 Flashcards
helps bring out the image
Phenidone
DEVELOPER
builds contrast
Hydroquinone
DEVELOPER
preservative; reduces oxidation
Sodium sulphite
DEVELOPER
activator; governs the activity of the developing agents
Potassium carbonate
DEVELOPER
restrainer; prevents fog and controls the activity of the developing agents
Benzotriazole
DEVELOPER
hardens the emulsion
Glutaraldehyde
DEVELOPER
prevents fungal growth
Fungicide
DEVELOPER
maintains pH (7+)
Buffer
DEVELOPER
solvent
Water
FIXER, DEVELOPER
removes unsensitized silver halide crystals
Ammonium thiosulphate
FIXER
preservative; prevents deterioration of the fixing agent
Sodium sulphite
FIXER
hardener
Aluminum chloride
FIXER
acidifier; maintains pH
Acetic acid
FIXER
→ has no need for a dark room
→ used in most dental clinics
→ contains the needed elements: developer, fixer and water for
rinsing
DEVELOPING BOX
→ a safe light is needed and positioned four feet from the solution
→ there should be absolute light tightness, an adequate working space, ventilation, washing facilities and adequate film storage
facilities
DARK ROOM
→ have a daylight loading facility
→ process is same as with manual processing except for the rinsing
between the developer and fixer due to rollers in the machine
AUTOMATIC PROCESSING
AUTOMATIC PROCESSING advantages & disadvantages
→ advantages:
o time-saving
o no dark room needed
o controlled standardized processing conditions are easy to maintain
o chemicals can be replenished automatically by some
machines
→ disadvantages
+ strict maintenance and regular cleaning of rollers which could leave a mark on films
+ plumbing in of some models
A n alternative to manual processing
already contains the developer and fixer in a special sachet
SELF-DEVELOPING FILMS
SELF-DEVELOPING FILMS advantages & disadvantages
advantages:
o no dark room needed
o time-saving
disadvantages:
o poor overall image quality
o image deteriorates rapidly with time
o no net foil inside the film packet
o film packet is very flexible and easily bent
o difficult to use in positioning folders
o relatively expensive
the digital image is captured in pixels (tiny squares), by two different types of sensor–solid-state or photostimulable phosphor plates
COMPUTER DIGITAL PROCESSING
the digital image is similar to a film-captured image, in that both are 2-dimensional representations of a 3-dimensional object
in digital imaging, each 2D pixel represents a 3D cuboid or voxel of the patient
COMPUTER DIGITAL PROCESSING
the depth of the cuboid is dependent on the thickness of the part of the body being x-rayed
each pixel measures the total x-ray absorption throughout the whole of each voxel
this 2D limitation has been overcome with the development of cone beam computed tomography (CBCT)
COMPUTER DIGITAL PROCESSING
COMMON CAUSES OF FAULTY RADIOGRAPHS
→ film processing results in a radiographic image
→ not paying attention to detail may lead to many problems
result in poor diagnostic film
→ poor films result in loss of diagnostic information
underdevelopment wherein the temperature in the developer is
too low or was dipped for a short time only
Light Radiographs
o depleted developer solution
o diluted or contaminated developer
o excessive fixation
Light Radiographs
underexposure:
o insufficient milliamperage
o insufficient peak kilovoltage
o insufficient time
o film source distance is too great o film package reversed in mouth
Light Radiographs
overdevelopment wherein the temperature of the developer is
too high or was dipped for too long
Dark Radiographs
o developer concentration is too high o inadequate fixation
o accidental exposure to light
o improper safelight
Dark Radiographs
→ overexposure:
o excessive milliamperage
o excessive peak kilovoltage
o excessive time
o film-source distance is too short
Dark Radiographs
→ improper safelight
→ light leak
Film Fogs
→ fingerprint contamination or black paper wrapping sticking to film surface
→ film in contact with other film during fixation
→ film contamination with developer before processing
Dark Spots or Lines
→ cause of excessive pending of films
→ static discharge of film before processing
→ excessive roller pressure during processing
→ dirty rollers in automatic processing
Dark Spots or Lines
→ cause of excessive pending of films
→ static discharge of film before processing
→ excessive roller pressure during processing
→ dirty rollers in automatic processing
Dark Spots or Lines
→ film contaminated with fixer before processing
→ film is in contact with another film during development
→ excessive bending of film
Light Spots
→ depleted developer or fixer
→ insufficient washing
→ contaminated solutions
Yellow and Brown Stains
→ movement of patient’s head or x-ray tube
→ double exposure; the film has been exposed already and used
again
Blurring of Films
→ top of the film is not immersed in developing solution
→ misalignment of x-ray tube which we commonly call as the “Cone
Cut”
Partial Images
→ abrasion of image during processing
→ excessive time in wash water
Emulsion Peel
→ abrasion of image during processing
→ excessive time in wash water
Emulsion Peel
