Dental X-Ray Film Flashcards
What is the purpose of dental x-ray film?
Serves as a recording medium or image receptor
What is an image?
A picture or likeness of an object
What is a receptor?
Something that responds to a stimulus
What is the film composition?
- film base
- adhesive layer
- film emulsion
- protective layer
What is the film base?
A 0.2 mm thick piece of polyester plastic that provides strength and support for the delicate emulsion
What is the adhesive layer?
Attaches the emulsion to the base
What is the film emulsion?
A homogenous coating with a mixture of gelatin and silver halide crystals attached to both sides of the film base. Gelatin is used to suspend and disperse millions of microscopic silver halide crystals over the film base. Silver halide crystals absorb radiation during exposure and store energy
What is the protective layer?
A protective layer is a thin coating over the emulsion to protect the emulsion from damage
What is latent image formation?
Silver halide crystals contain various levels of stored energy, depending on the density of the objects in the area exposed. The stored energy forms a pattern known as the latent image. The latent image cannot be seen until chemical processing to produce a visible image.
What happens when the photons strike the emulsion?
Some of the silver bromide/halide crystals are exposed but other are not.
What happens to crystals that are exposed when photons strike the emulsion?
They ionize, and the silver and bromine atoms are separated. Irregularities in the lattice structure of the exposed crystal, sensitivity specks, attract the silver atoms. These aggregates of neutral silver atoms are known as latent image centres
Types of dental x-ray film
- Intraoral film
- Extraoral film
- Duplicating film
What is intraoral film?
Placed inside the mouth and used to examine the teeth and supporting structures
What is the intraoral film packaging like?
Used to protect the film from light and moisture. It is usually available in plastic trays or cardboard boxes containing 25, 100 or 150 films
What are intraoral film boxes labeled with?
- type of film (Kodak, brand name)
- film speed
- film size
- number of films per packate
- total number of films enclosed
- expiration date
What are the components of intraoral film packaging?
Film packets have 4 components:
- x ray film
- paper film wrapper
- lead foil sheet
- outer package wrapping
What is the emulsion like on the intraoral film? How does this help?
Double emulsion film (emulsion on both sides). Requires less radiation to produce a latent image than a single emulsion. Double film packets are used when duplicates are needed, produce identical radiographs with the same amount of exposure
How do we identify the orientation of intraoral films?
Identification dots (small raised dot) in one corner that is used to distinguish the left and right sides of the patient. Important for film mounting and interpretation of radiographs. DOT IN THE SLOT
What is the paper film wrapper used for?
A black protective sheet to cover the film and protect is from light
What is the lead foil sheet used for?
Located behind the film wrapped in black protective paper, the lead foil sheet is used to shield the film from back scatter (secondary) radiation that creates film fog. Has a pattern that is visible on a reversed film when film is misplaced in the mouth (herringbone pattern)
What is the outer package wrapping and what is it used for?
Soft vinyl or paper wrapper to seal the contents and protect them from light or moisture. Tube side (solid white with a raised bump corresponding to the identification for on x-ray film). Tube side should face the teeth and tubehead during an exposure
What is the label side of the outer package wrapping?
Colour coded to identify between one and two film packs and according to film speed. (mint colour = one film packet, gray colour = 2 film packet). Has a flap used to open the film packet prior to processing
What are the 3 types of intraoral film?
- Periapical film
- Bite-wing film
- Occlusal film
What is perioapical film used for?
Used to examine the entire tooth, the crown and the root and the supporting bone. Evaluate height of the alveolar crest, evaluate modification of the lamina dura. Is more utilized to evaluate periodontal disease and periapical lesion. Dot in the slot
What is bite-wing film used for?
Used to examine the crowns of both maxillary and mandibular teeth on one film. Used for examining interproximal surfaces and cavity detection. Can use stick-on tabs or bite-wing loops
What is occlusal film used for?
A larger film used for examination of large areas of the maxillary or mandible. Detect cysts, impacted teeth, obstruction in the salivary glands
What are the 5 sizes of intraoral films? What can they be used for?
0, 1, 2, 3, 4, 5. Can be used for periapical film, bite-wing film, or occlusal film
In periapical films, what sizes would be used for small children? For anterior teeth in adults? For standard film on anterior and posterior teeth in adults?
#0 for small children #1 for anterior teeth in adults #2 in standard film on anterior and posterior teeth in adults
What size film would we use for bite wings for posterior teeth in small children? For horizontal or vertical examination of posterior teeth in adults? To see all posterior teeth on one side of the arch?
#0 used for posterior teeth in small children. #2 used horizontally or vertically to examine posterior teeth in adults #3 used to see all posterior teeth on one side of the arch (although currently not recommended because all contacts cannot be opened on one film because #3 is larger and narrower than standard #2)
What size film is used for occlusal films?
4 as it is almost 4x the size of the standard #2 film. Used to examine large areas of maxilla or mandible
What is film speed? What determines it?
Film speed is the amount of radiation required to produce a radiograph of standard density. It is determined by:
- the size of silver halide crystals
- the thickness of the emulsion
- the presence of special radiosensitive dyes
A fast film exposure requires less radiation exposure
What are extraoral films?
Placed outside the mouth during exposure, used to examine large areas of teeth and jaws.
What are extraoral films used for?
- Panoramic film
- Cephalometric film
What are panoramic films used for?
- wide view of upper and lower jaws
- identify oral pathologies
- edentulous patient before denture confection
- orthodontic treatment (evaluate growth/treatment plan)
- usually for all new patients
What are cephalometric films used for?
- bony and soft tissue areas of the facial profile (from the side)
- orthodontic treatment
- maxillo-facial surgery
What is extraoral film packaging like?
- boxed in quantities or 50 or 100 films (not enclosed in moisture proof packs)
- 5x7 inch or 8x10 inch sizes
- 5x12 inch or 6x12 inch sizes for panoramic films
- careful not to expose entire box
What are the 2 types of extraoral film?
- screen film
- nonscreen film
What is screen film?
- requires the use of a screen (intensifying) in a cassette with phosphors for exposure. the film is sensitive to fluorescent light, rather than direct exposure to x-radiation
- some screen films are sensitive to blue light and some are sensitive to green light
- the film-screen combinations must match
What is nonscreen film?
Does not require the use of a screen; is exposed directly to x-rays. Not recommended for dental use as it needs too much radiation.
What is extraoral film equipment?
Screen films are used with intensifying screens and cassettes
What are intensifying screens?
A device that transfers x-ray energy into visible light; the visible light then exposes the screen film (these screens intensify effects of x-rays on the film). This lowers radiation dose to the patient
How is the screen film secured?
Into a cassette between 2 intensifying screens of matching size. The intensifying screen is a smooth plastic sheet coated with minute fluorescent crystals known as phosphors (when exposed, the phosphors fluoresce and emit visible light in the blue or green spectrum). The emitted light then exposed the film
What are the 2 types of intensifying screens?
- calcium tungstate screens (have phosphors that emit blue light)
- rare earth screens (have phosphors that emit green light, these require less radiation than calcium tungstate screens)
What is a cassette?
Used to hold the film and the intensifying screens. May be flexible or right (most are rigid, except the panoramic cassette, which may be flexible). Must be light tight and hold the intensifying screen in contact with film; otherwise, the lack of contact between him and cassette will result in a lack or sharpness of the image in that area
What does a rigid cassette allow for passage of?
Has a plastic front cover to allow the photons to pass through
What does the back cover of a rigid cassette do?
Is metal to reduce scatter radiation
How do we ensure proper orientation of a cassette?
The cassette is marked with an L and an R for orientation
What is duplicating film?
A different type of film than radiographic film. Is used to make copies (the longer it is exposed, the lighter the film will be).
What is the use or duplicating film?
Good for referrals and for the submission of insurance claims
Is duplicating film one sided or two? Why?
One sided. It is not exposed to x-rays; it must be used with a film duplicator
What is the duplicating film packaging like?
Available in pariapical sizes and 5x12 inch and 8x10 inch sheets. Boxes of 50, 100 or 150 sheets available
How should film be stored?
Film is negatively affected by heat, humidity and radiation
What are the 7 rules for storing film?
- film should be kept in a cool, dry place
- 50-70 F
- 30-50% humidity
- to prevent film fog, we should store films in a lead lined or radiation-resistant storage boxes
- film has an expiration date
- we should always look at the expiration date before opening a new box
- first in, first out
