film composition
DESCRIPTION
TRANSCRIPT
RECEPTORSX- ray film
Radiograph
DENTAL
Objectives for this Unit
• Discuss the composition of dental film• Describe latent image formation.• Differentiate between screen and nonscreen films• Identify the contents in dental film packets• Identify and compare the various intraoral films
according to size, customary usage and film speed.• Differentiate between intraoral and extraoral films• Discuss correct methods of film storage and
protection.
Dental X-Ray Film:
Picture or Likeness of an Object
Dental X-Ray Film: Components
Dental X-Ray Film: Composition
Film Base – a 0.2mm thick flexible piece of polyester plastic
- Transparent and slight blue tint - Emphasize Contrast - Enhances Image Quality - as a stable support for the emulsion
Dental X-Ray Film: Components
Film Emulsion • a homogenous mixture
• Gelatin • Halide Crystals
• Sensitive to X-ray
Dental X-Ray Film: Components
Gelatin •Suspension for the crystals•Evenly disperse the Silver Halide crystals
Silver Halide Crystals
•Sensitive to Radiation and light•Absorbs radiation & stores energy from the radiation•Has 80-99% AgBr and 1 – 10% AgI
Film Emulsion
Dental X-Ray Film: Components
Adhesive Layer- serves to attach the emulsion to
the baseProtective Layer
- thin transparent coating over the emulsion.- serves as protection from manipulation, chemical and processing damage
Dental X-Ray Film:
Latent Image• an Invisible image within the emulsion on the
exposed film • A pattern created by the stored energy with in
the Silver Halide Crystals
Films
• Non – Screen Film ( Intra-Oral Film)•Screen Film
2 Types
Extraoral Films
Screen Film• Main function – Reduce radiation to the patient • requires a screen for exposure
o Intensifying Screen – a device that transfers x-ray to visible light.
o Coated with Phosphors, Calcium Tungstate,Rare Earth
Types of Dental X-Ray Film
• Intraoral Films•Extra Oral Films
Extraoral FilmDental X-Ray Film:
• Are films placed/positioned outside the mouth during x-ray exposure.• are used to examine large areas of the skull and jaws
Extraoral FilmDental X-Ray Film:
• Panoramic Films•Cephalometric Films
Examples of Extra Oral Films
Intraoral Films
Size 022 x
35mm
Size 124 x 40mm
Size 2
31 x 41mm
“Pedo”“child” & some
AdultsAdult Film also Used
on young child for occlusal
Dental X-Ray Film:
Intraoral Film
Size 3
27 x 54mm
Size 4
57 x 76mm
Adult BWXonly
Occlusal Adult or child
Dental X-Ray Film:
Intraoral FilmDental X-Ray Film:
Packaging of Intraoral Film• water proof outer package
• Black Paper
• Film
• Lead Foil Backing
Refers to the amount of radiation required to
produce a Radiograph.
Intraoral Film Speed
Intraoral Film Speed
Factors Affecting Film Speed Size of Silver Halide Crystals Thickness of Emulsion presence of radiosensitive dyes
Intraoral Film Speed
Classification of Film Speed
A – F SpeedD- speed Film and E- Speed Film are used for intraoral radiography
FILM SPEEDFactors that determine film speed
Size of silver halide crystal. • The larger the crystal, the faster the film speed• The larger the crystal, the grainer the film
appearance.• The grainer the image, the greater the loss of
image sharpness.Thickness of emulsion
• The thicker the emulsion, the faster the film.Special radiosensitive dyes. Dyes are added to the emulsion to speed the film.
Film Storage and Protection
III. Dark room concerns
A.Old or contaminated solutionsB.Chemical fumes from the processorsC.PressureD.Faulty Safe lightsE.Unexposed film SHOULD NOT be stored
in the dark room
Film Storage and Protection
I . All film is extremely sensitive to light, heat, humidity and pressure
II. Any of these can cause film fogging or darkening of the finished
radiograph, on the film even prior to exposing or processing
Film Storage and Protection
IV. Heat and humidityA.Ideally should be stored at 50-70°B.30-50% relative humidity
V. Pressure—do not stack film to high or place
heavy objects on filmVI. Film should not be left in the x-ray roomVII. All film has a shelf life
Review:
• What are the composition of dental film?• Describe latent image formation.• Differentiate between screen and nonscreen films• What are the contents in dental film packets?• Identify and compare the various intraoral films
– according to size, – customary usage – film speed.
• Differentiate between intraoral and extraoral films• Discuss correct methods of film storage and protection.