film composition

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.