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Dental Radiology 6
Radiographic Film
| Question | Answer |
|---|---|
| Conventional film composition, 4 components | Film Base, Film Emulsion, Film Adhesive layer, Protective layer |
| Film Base of Conventional Film | Film base flexible, clear cellulose acetate withstands heat, moisture, chemical exposure provides support for emulsion |
| Film Emulsion of Conventional Film | Film emulsion coating consisting of gelatin and silver halide crystals silver halide crystals made mostly of silver bromide silver halide crystals absorb radiation during x-ray exposure halide is sensitive to radiation and light |
| Adhesive Layer of Conventional Film | Adhesive layer Covers both sides of the film base Attaches emulsion to the base |
| Protective Layer of Conventional Film | Protective layer Transparent coating placed over the emulsion to protect it from handling, processing and mechanical damage |
| Latent Image Formation, Dental Radiographic Film | Dental radgrphc film is image recptr Silver halide crystals absorb x-radtn & store the energy from the raditn. Stored energy within the crystals forms a pattern &creates an invisible image wthn theemulsion this pattern of stored energy is latent image |
| The latent image becomes visible on film once... | Once the film undergoes chemical processing, the latent image becomes visible on the film. |
| The process of latent image formation (in sequence): | *X-ray photons hitfilm emulsion *Silver bromide crystals thatare exposd tox-rays become ionized (silver& bromine atoms seprte) Irrglrtes inthelattice structure ofthe crystalsattract thesilver atoms *The crystals w/clusters ofsilver form latentimage onfil |
| Intraoral Film, characteristics | Intraoral film *Protected from light and moisture *Double emulsion *Film packet contents: black paper, lead foil, outer covering (identification dot), film(s) |
| Extraoral film; placed...; examines...; includes... | Extraoral film Placed outside the mouth; *Examines large areas of the maxilla and mandible or skull *Includes panoramic films, cephalometric films |
| What film utilizes intensifying screens | extraoral |
| Extraoral film and intensifying screens; What happens when intensifying screens are exposed to x-rays? benefits for pt? | *When exposed to x-rays, the screens convert x-ray energy into light Screen film is sensitive to fluorescent light instead of direct exposure to x-radiation Reduce radiation exposure to the patient |
| Calcium tungstate intensifying screens emit | blue light |
| Rare earth intensifying screens emit | green light |
| Intensifying screens are... When exposed to x-rays... Types of intensifying screens | Screens -smooth plastic sheets coated w/fluorescent crystals calld phosphors When exposed to x-rays, phosphors emit visible light this light then exposes thefilm Some are calcium tungstate screens-emit blue light, or rare earth screens-emit green ligh |
| Non-screen film, describe | Non-screen film *Does not use intensifying screens for exposure (film emulsion is directly exposed to x-radiation) Requires more exposure time than a screen film *non-screen film use is not recommended in dental radiography |
| Non-screen film and exposure time | Non-screen film requires more exposure time than a screen film |
| Duplicating film | Photographic film that is used to make an identical copy of an intraoral or extraoral conventional radiograph |
| Photographic film that is used to make an identical copy of an intraoral or extraoral conventional radiograph | duplicating film |
| Duplicating film is used only.. | in the darkroom, not exposed to radiation |
| Duplicating film, emulsion characteristics; placement of film during duplicating | *Emulsion on one side only emulsion side appears dull (matte finish) *side without emulsion is shiny& darker in appearance *emulsion side is in contact w/the radiograph during the duplictng process *notch on upper right side of film when correctly pla |
| When duplicating film what position of notch will indicate that film is correctly placed | notch on the upper right side of film when correctly placed; |
| (Intraoral) Film Speed | Film speed refers to the amount of radiation required to produce a radiograph of standard density; Film speed = film sensitivity |
| Film Speed= | Film Sensitivity |
| Film Sensitivity= | Film Speed |
| Determining factors of intraoral film speed | Determining factors *Size of silver halide crystals larger crystals = faster speed film *Thickness of emulsion *Presence of radiosensitive dyes |
| Film speed determines ... | Film speed determines the amount of radiation and exposure time necessary to produce an image on the film |
| Faster speed film and exposure time | faster speed film requires less exposure time to produce an image on the film since the film is more sensitive to x-radiation the larger the silver halide crystals, the faster the film speed |
| Film speed is classified by... and designated by... | Film speed is classified by alphabetical letter (A-E) and designated by the American National Standards Institute (ANSI) |
| Types of Film | A-C speed film are the slowest and least sensitive “D” : “Ultraspeed” “E” : “Ektaspeed” or “Ektaspeed Plus” discontinued by Kodak “F” : “Insight” Only D-speed and F-speed film are used for intraoral radiography |
| F-speed film characteristics | F-speed film requires about 60% of the exposure time of D-speed film Safest speed film for the patient Larger crystals Increased amount of silver bromide in the emulsion thicker emulsion Speed of film indicated on the film packet |
| Film Sizes | 5 sizes (children – adult) Size 0 small children (bitewings) Size 1 anterior PA films-adults Size 2 posterior PA films, posterior BW films Size 3 BWs only “long bitewing” not recommended- difficult to open all contact areas Size 4 adult occlus |
| Film storage. Film is affected by | Film is adversely affected by heat, humidity and radiation |
| Film storage, characterize | *Must be kept in a cool, dry environment (50-70 degrees F) *Area free of radiation to avoid film fogging do not store film in the dental operatory unless it is in a lead-lined box *Film has a limited shelf life check the expiration date on the box |
| Film fogging, define | All or part of the conventional radiograph appears gray due to sources other than the primary beam radiation. |
| All or part of the conventional radiograph appears gray due to sources other than the primary beam radiation. | Film fogging |
| Causes of film fogging | *Light leaks/inadequate safelighting in darkroom *Contmntd procssng solutions *Unintntnl exposure to light before/during processing *Scatter radiation striking the film (scatter may come from the pt or from storing the film in operatory) Outdated film |
| Daylight loaders for conventional film | Daylight loaders for conventional film Light tight cover for an automatic film processor that allows you to develop films without using a darkroom An infection control problem! |
| Problem with daylight loaders for conventional film | An infection control problem |
| Light tight cover for an automatic film processor that allows you to develop films without using a darkroom | Daylight loaders for conventional film |
Created by:
EdmondDantes