Dental X-Ray Films-1.pdf

Dental X-Ray Films Prepared by : Dr. Rowa’a Yasin o Definition of Dental X-ray Films o Types of X-ray Films o Intraoral / Extraoral Films o Film sizes o Intraoral Film Packet Contents o Film processing Dr. Rowa'a Yasin  Dental X-Ray Films A recording media o...

Dental X-Ray Films Prepared by : Dr. Rowa’a Yasin o Definition of Dental X-ray Films o Types of X-ray Films o Intraoral / Extraoral Films o Film sizes o Intraoral Film Packet Contents o Film processing Dr. Rowa'a Yasin  Dental X-Ray Films A recording media on which image of the object was made by exposing this film to X-ray Dr. Rowa'a Yasin  Types of X- Ray Films Films are classified according to their 1) Uses Intraoral or Extraoral films / Direct or Indirect films 2) Speed Slow films are A, B , C and Fast films are D , E , F 3) Emulsion layer Single or Double 4) Packaging Single or Double 5) Size Dr. Rowa'a Yasin 1. According to their Uses Intraoral Films ( Direct Exposure ) Periapical views Bitewing views Occlusal views Extraoral films ( Indirect Exposure ) Panorama , Cephalometry and other Skull views Dr. Rowa'a Yasin  INTRAORAL FILMS They are placed inside patient’s mouth during exposure to x-rays All intraoral dental films are Direct exposure films Film intended to be exposed by X-rays Direct exposure film is used for intraoral examinations because it provides higher resolution images than screen-film combinations Dr. Rowa'a Yasin Types 1- Periapical 2- Bitewing 3- Occlusal Dr. Rowa'a Yasin  Periapical views Record the entire length of teeth (crowns, roots ) and surrounding bone Bitewing views Record the coronal portions of the maxillary and mandibular teeth in one image Used to detect interproximal caries and evaluate the height of alveolar bone Occlusal views Used to show larger areas of the maxilla or mandible than may be seen on a periapical film Dr. Rowa'a Yasin Dr. Rowa'a Yasin  EXTRAORAL FILMS They are placed outside patient’s mouth during X-ray exposure Located in cassette e.g. Panoramic film, Cephalometric and other skull views Types 1. Non screen films ( Direct ) 2. Screen films ( Indirect ) Dr. Rowa'a Yasin Dr. Rowa'a Yasin Screen Film The majority of extraoral films are screen films Screen film is a film that requires the use of a screen for exposure A screen film is placed between two special intensifying fluorescent screen in a cassette Dr. Rowa'a Yasin  Film emulsion is more sensitive to fluorescent light and more specifically to blue light These screen made from tiny calcium tungstate or Rare earth elements When these crystals are exposed to X-ray the result of exposure is creation of blue light this in turn exposes the film to produce image So the screen film is sensitive to fluorescent light rather than to direct exposure to x-ray Dr. Rowa'a Yasin  Cephalometric Dr. Rowa'a Yasin Non Screen Film It doesn’t require the use of screen for exposure A non screen film is exposed directly to X-ray Film emulsion is more sensitive to X-ray than to light The film has double emulsion like intra-oral films But the emulsion is thicker A non screen film requires more exposure time than does a screen film and is not recommended for use in dental radiography Dr. Rowa'a Yasin  2. According to the Speed SPEED means - The sensitivity of X-ray film silver bromide crystals to X-ray radiation - The amount of radiation required to produce a radiograph of standard density Factors that determine film speed are 1. Size of silver halide crystals 2. Thickness of the emulsion 3. Presence of special radiosensitive dyes Dr. Rowa'a Yasin Dr. Rowa'a Yasin  We have direct relation between the speed and the size of crystals and thickness of the emulsion - The larger the size the faster the film speed ✓ Film speed A is the Slowest ✓ Film speed F is the Fastest - The thicker the emulsion the faster the film - The faster film responds more quickly so it requires less amount of radiation to produce photographic image Dr. Rowa'a Yasin Dr. Rowa'a Yasin 5. According to the Size Size 4 Dr. Rowa'a Yasin Intraoral Films Sizes Various sizes of films are available 0 , 1 , 2 , 3, 4 Size 0 for small children Size 1 - May be also used for children - Used for anterior teeth in adults Size 2 standard film for Periapical and Bitewing radiography Size 3 it is a long Bitewing film Size 4 is the largest film , used for occlusal radiography Dr. Rowa'a Yasin Dr. Rowa'a Yasin Dr. Rowa'a Yasin Occlusal View Film Size 57 x 76 mm To show larger area than periapical views Dr. Rowa'a Yasin STANDARD INTRAORAL FILM SIZES : SIZE 4 ( 57 x 76 mm ) For Occlusal radiograph SIZE 2 ( 31 x 41 mm ) For Periapical and Bitewings radiographs Dr. Rowa'a Yasin Extra-oral Films Sizes NON SCREEN FILMS Size include 5 x 7 and 8 x 10 inches SCREEN FILMS - Size 5 x 7 inches used mainly for lateral view of the jaw or TMJ - Size 8 x 10 inches used for cephalometry and P/A view of the skull - Size 10 x 12 inches used for panoramic radiographs Dr. Rowa'a Yasin Intraoral Film Packet Contents Outer packet or wrapper Radiographic film Sheet of lead foil Black paper Dr. Rowa'a Yasin  Black Paper Black Paper Dr. Rowa'a Yasin Dr. Rowa'a Yasin  OUTER PACKET OR WRAPPER Is made of nonabsorbent paper or plastic and is sealed to prevent the ingress of saliva Each film packet has two sides The front side or tube side of the packet Faces towards the x-ray beam usually White in color Dr. Rowa'a Yasin  The back or label side Faces away from the source of radiation Usually of two colors so there is little chance of the film being placed the wrong way in patient’s mouth Different colors represent different film speeds Dr. Rowa'a Yasin  BLACK PAPER The black paper on either side of the film To protect the film from Light Damage by fingers while being unwrapped Saliva which may leak into the film packet Dr. Rowa'a Yasin  SHEET LEAD FOIL A thin sheet of lead foil is placed behind the film To prevent : Scattered secondary radiation from x-ray photon interactions within the tissues Some of the residual radiation that has passed through the film continuing on into the patients tissue Dr. Rowa'a Yasin  RADIOGRAPHIC FILM ❖ COMPOSED OF : Plastic Base A thin layer of adhesive Emulsion A protective layer of clear gelatin Dr. Rowa'a Yasin THE RADIOGRAPHIC FILM Dr. Rowa'a Yasin  Plastic Base : Made of clear transparent cellulose acetate Which acts as a support for the emulsion but doesn’t contribute to the final image Adhesive layer : A thin layer that fixes the emulsion to the base Dr. Rowa'a Yasin  Emulsion : On both sides of the base Consists of silver halide crystals embedded in a gelatin matrix Sensitive to both x-ray photons and light A protective layer of clear gelatin : To shield the emulsion from mechanical damage Dr. Rowa'a Yasin Dr. Rowa'a Yasin What will happen during exposure of film to radiation ? X-Ray photons interact with electrons of atoms of chemical emulsion in dental film So the result is analogue image (identical to the original ) Dr. Rowa'a Yasin  FILM STORAGE AND PROTECTION All radiographic film is extremely sensitive to Radiation , light , heat , humidity , chemical fumes and physical pressure Additionally film is sensitive to aging having a shelf life determined by manufacture Film fogging is the darkening of the finished radiograph caused by one or more of these factors Dr. Rowa'a Yasin  Film Processing A series of steps that convert the invisible latent image on dental X-ray film into visible permanent radiographic image It can be done into ways : - Chemical Processing - Computer Digital Processing Dr. Rowa'a Yasin A) A silver bromide crystal in the emulsion of an x-ray film contains mostly silver and bromide ions in a crystal lattice also free interstitial silver ions and areas of trace chemicals that form sensitivity sites B) Exposure of the crystal to photons in an x-ray beam results in the release of electrons, usually by interaction of the photon with a bromide ion the recoil electrons have sufficient kinetic energy to move about in the crystal , When electrons reach a sensitivity site they impart a negative charge to this region C) Free interstitial silver ions with a positive charge are attracted to the negatively charged sensitivity site D) When the silver ions reach the sensitivity site they acquire an electron and become neutral silver atoms These silver atoms now constitute a latent image site The collection of latent image sites over the entire film constitutes the latent image  Practical Processing Methods There are three practical processing methods Manual or wet processing Automatic processing Using self-developing films Dr. Rowa'a Yasin MANUAL OR WET PROCESSING Dr. Rowa'a Yasin  It is carried out in a dark room General Requirements are Absolute light tightness Adequate working space Adequate ventilation Adequate washing facilities Adequate film storage facilities Dr. Rowa'a Yasin  Stages Of Processing Immerse exposed film in Developer Rinse developer off film in water bath Immerse film in Fixer Wash film in water bath to remove fixer Dry film and mount for viewing Dr. Rowa'a Yasin Emulsion Changes During Film Processing (A) Before exposure many silver bromide crystals (gray) are present in emulsion (B) After exposure the exposed crystals containing neutral silver atoms at latent image sites (orange dots within some crystals) constitute the latent image (C) The developer converts the exposed crystals containing neutral silver atoms at the latent image sites into solid grains of metallic silver (black) (D) The fixer dissolves the unexposed, undeveloped silver bromide crystals leaving only the solid silver grains that form the radiographic image Stage 1 : Development The exposed sensitized silver halide crystals in the emulsion are converted into black metallic silver to produce the black/ grey parts of the image Stage 2 : Rinsing The film is washed in water to remove residual developer solutions Dr. Rowa'a Yasin Stage 3 : Fixation The unexposed unsensitized silver halide crystals in the emulsion are removed to reveal the transparent or white parts of the image and the emulsion is hardened Stage 4 : Washing The film is washed thoroughly in running water to remove residual fixer solution Stage 5 : Drying The resultant Black / White Radiograph is dried Dr. Rowa'a Yasin Dr. Rowa'a Yasin  PROCESSING SOLUTIONS DEVELOPER It is an alkaline solution Its action on the sensitized ( exposed ) crystals Also the developer will soften the emulsion Produce the Black / Grey parts of the image When the developer solution is oxidized by air its effectiveness decreased Dr. Rowa'a Yasin  Solutions should be used for no more than 10-14 days irrespective of the number of films processed during that time Too long development, the radiograph will be too Dark Too short development, the radiograph will be too Light Development time is dependent on the temperature of solution If temperatures is too high development is rapid If the temperature is too low the development is slowed Dr. Rowa'a Yasin  It is an acid solution FIXER Action : Re harden the emulsion Removed the unexposed or undeveloped crystals Produce the White parts of the image Inadequately fixed films may appear greenish yellow or milky due to residual emulsion With time these films may discolor further becoming brown Dr. Rowa'a Yasin AUTOMATIC PROCESSING Dr. Rowa'a Yasin  It is carried out by a machine automatically The cycle is the same as for manual processing except that the rollers squeeze off any excess developing solution before passing the film into the fixer thus eliminating the need for the water wash between these two solutions Dr. Rowa'a Yasin Advantages Time saving No need for dark room Controlled, standardized processing conditions are easy to maintain Chemicals can be replenished automatically by some machines Disadvantages Strict maintenance and regular cleaning are essential Expensive equipment Smaller machines can not process large extra oral films Dr. Rowa'a Yasin  SELF DEVELOPING FILMS An alternative to manual processing The x-ray film is presented in a special sachet containing Developer and Fixer Following exposure milk down the developer and fixer towards the film when the chemicals reaches the film massaged it for 30-45 seconds Push the liquid back Pull up the flap to open and take the film out Wash the film thoroughly under running water Dr. Rowa'a Yasin Dr. Rowa'a Yasin Advantages No darkroom or processing facilities are needed Time saving Disadvantages Poor overall image quality The image break up rapidly with time There is no lead foil inside the film packet The film packet is very flexible and easily bent Difficult to be used in positioning holders Relatively expensive Dr. Rowa'a Yasin