Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
10 Cards in this Set
- Front
- Back
Describe in detail film composition and latent image formation
|
Dental x-ray film serves as a recording medium or image receptor
-Image: a picture or likeness of an object -Receptor: something that responds to a stimulus Film composition (4 components) 1) Film base -flexible piece of polyester plastic 0.2mm -provide a stable support for the delicate emulsion 2) Adhesive layer -attach the emulsion to the base -allows emulsion to stick to the plastic 3) Film emulsion -A homogenous coating w/ a mixture of gelatine and silver halide crystals attached to both sides of the film base -halide: a chemical compound that is sensitive to radiation -Gelatin: used to suspend and disperse millions of microscopic silver halide crystals over the film base -Halide crystals: The silver halide crystals absorb radiation during exposure and store the energy 4) Protective layer -a thin coating over the emulsion to protect the emulsion from damage Latent image formation -Silver halide crystals (silver bromide and silver iodine) contain various levels of stored energy, depending on the density of the objects in the are exposed -the stored energy forms a pattern know as the latent image (a duplicate image of the teeth on film) -The latent image cannot be seen until chemical processing to produce a visible image -When photons (x-ray) strike the emulsion, some silver bromide crystals are exposed while others are not -crystals exposed are ionized, and the silver and the bromine atoms are separated -Irregularities in the structure of the exposed crystal (sensitivity specks) attract the silver atoms -Sensitivity speck attracts electrons (-) which then attract silver ions (+). The collection of neutral silver atoms (Ag) create latent image centers |
|
List and describe the different types of x-ray film used in dentistry
|
Intraoral film: in the mouth for exposure and need radiation
Extraoral film: outside of person Duplicating film: does not recieve x-ray |
|
Define intraoral film and describe intraoral film packaging
|
-Placed inside the mouth and used to examine the teeth and supporting structures
Packaging: -used to protect the film from light and moisture -boxes are labeled with the type of film, film speed, film size, number of films per packet, total number of films enclosed, and expiration date -4 components: x-ray film, paper film wrapper, lead foil sheet, outer package wrapping 1) X-ray film -1 or 2 film packet -id dot used to determined film orientation -id dot located in corner of film -id dot will be raised on one side and indented on other -critical to determine right and left sides of patients mouth -Double film packet used when duplicate radiographs are indicated 2) Paper film wrapper -A black protective sheet to cover the film and protect it from light -looks and feels like construction paper 2) Lead foil sheet -Located behind the film wrapped in black protective paper -shields the film from back scattered (secondary) radiation that creates film fog. -has a pattern that is visible on reversed film 4) Outer Package wrapping -soft vinyl or paper to seal the contents and protect them from light or moisture -tube side (front side of film) =solid white w/ a raised bump corresponding to the identification dot on x-ray film =solid white side should face the tubehead during the exposure Label side: -color coded to identify b/w 1 and 2 film packs and according to film speed -has a flap used to open the film packet prior to processing |
|
Identify the types and sizes of intraoral film available
|
3 types of intraoral film
1) Periapical film 2) Bitewing film 3) Occlusal film Periapical- used to examine the entire tooth and 2 mm of supporting bone. 2mm for posterior, 4mm for anterior Bitewing film: -used to examine the crowns of both maxillary and mandibular teeth on one film -used for examining interproximal surfaces -can use stick-on tabs of bitewing loops Occlusal film: -larger film used for examination of large areas of the maxilla or mandible Film sizes: Periapical film: -0: used for small children -1 used for anterior teeth for adults -2 standard film, used for anterior and posterior teeth in adults Bitewing film -0: used for posterior teeth in small children -1: positioned vertically to examine anterior teeth in adults -2: used horizontally/vertically to examine posterior teeth in adults -3: shows all posterior teeth on one side of the arch (not recommended, can't see all open contacts) Occlusal film: -4: used to examine large areas of the maxilla or mandible (almost 4x the size of standard #2 film) |
|
Discuss film speed
|
-The amount of radiation required to produce a radiograph of standard density
-Determined by: =the size of silver halide crystals =the thickness of the emulsion =the presence of special radiosensitive dyes -a fast film requires less radiation exposure =larger crystals with increase silver bromide in emulsion -the current speeds available are D and F =E speed is off the market =F speed film (insight film) requires 60% of the exposure time as D speed film |
|
Discuss the differences between intraoral film and extraoral film
|
Extraoral film:
-placed outside the mouth during an exposure -used to examine large areas of teeth and jaws -panoramic film =wide view of upper and lower jaws -cephalometric film =bony and soft tissue areas in profile (from the side) |
|
Describe the difference between screen and nonscreen films
|
Screen films:
-Requires the use of a screen 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 Nonscreen film: -Doesn't require the use of a screen; it is exposed directly to x-rays -not used in dentistry |
|
Describe the use of intensifying screens and cassettes
|
-screen films are used with intensifying screens and cassettes
Intensifying screens: -a device that transfers x-ray energy into visible light =visible light then exposes the screen film =this lowers the radiation dose to the patient -Screen film is secured in a cassette b/w 2 intensifying screens of matching size =intensifying screen is a smooth plastic sheet coated with fluorescent crystals called phosphors -2 types 1) Calcium tungstate screens-have phosphors that emit BLUE light 2) Rare earth screens (less radiation)-have phosphors that emit GREEN light. Cassettes: -Houses the film and the intensifying screens -flexible or rigid -light tight and hold the intensifying screen in contact with film -without contact of film and screen, image will lack sharpness of the image in that area -a rigid cassette has a plastic front cover to allow the photons to pass thru =the back cover is metal to reduce scatter radiation -the cassette is marked with an L and an R for orientation |
|
Describe duplicating film
|
-Different type of film than radiographic film
-used to make copies of original =the longer it is exposed, the lighter the film will be =used for referrals and for the submission of insurance claims -Duplicating film has emulsion on one side only =it is not exposed to x-rays =must use duplicator equipment and white light |
|
Discuss proper film storage and protection
|
-Film is affected by heat, humidity, and radiation
=film should be kept in a cool, dry place =film has an expiration date |