![]() Long axes Apices location Beam alignment/angulation Vertical Horizontal Point of entry Centering exposure fieldģ2 Stabe Holder Design features Radiolucent Rigid back Disposableĭot in slot Center film in holder Anterior = vertical Posterior = horizontal Insert cotton roll under bite block Instruct client to close firmly Slide aiming ring along indicator rod until close to client’s skin Expose film!ģ0 Stabe Holder Film Placement Holder Oral Cavityģ1 Stabe Holder Anatomical considerations Beam alignment/angulation Need to remember which films have been exposed #1-32 Cross arch Anterior first Insert indicator rod into aiming ring slot Check for correct assemblyĬenter film & holder behind teeth to be radiographed Maintain film parallel to long axis of teeth & buccal surfaces of teeth Stabilized bite block against occlusal surfaces of teeth to be radiographedĢ6 Long Axes of the Teeth Mandibular ArchĢ7 Sequence of Films Several possibilities Maxillary occlusal plane parallel to floor for maxillary films Mandibular occlusal plane parallel to floor for mandibular filmsįilm holder Anterior: longest dimension of film placed vertically Posterior: widest dimension of film placed horizontally Dot in the slot XCP: flex backing plate to open film slotĢ2 XCP Holders Assembly Positioning Step-by-step proceduresĢ3 XCP Assembly Insert rod into openings in bite block Ring further aligns beam & prevents cone cutting Cotton rolls used for stabilization Rectangular PID or lead collimators availableĢ0 Client Positioning Midsaggital plane perpendicular to floor XCP Plastic bite block or styrofoam Metal arm supports plastic ring Arm used to align horizontal & vertical beam alignment What’s a “good” film? Area of interest clearly displayed Apical regions visible with 2-3 mm of surrounding bone Entire tooth/teeth length displayed No cone-cutting in region of interest ![]() Two-point contact Radiation beam Maxillary molarįilm position Horizontal dimension: position horizontal plane of film parallel to facial surfaces of teeth being radiographedīeam alignment Vertical: direct radiation beam perpendicular to film & long axes of teeth Horizontal: direct radiation beam through the contact areas of the teeth Technique of choice due to image accuracy Implication of name Developed 1920 Requires use of long target-film-distance 16” PID or recessed tubeheadĦ Principles of the Paralleling Techniqueįilm placed parallel to long axis of teeth Beam directed perpendicular to film & long axis of teeth Film holder used to keep film flat & unbent Long PID or TFD to offset increased magnification due to great OFDħ Principles of the Paralleling Techniqueįilm placement Film position Vertical dimension Parallel to long axis Two-point contact Horizontal dimension Beam alignment Vertical Horizontal Film exposureįilm placement: position film to cover prescribed area (teeth to be examined)įilm position Vertical dimension: position film parallel to long axes of teeth by placing far away from lingual surfaces of teethįilm position Vertical dimension: position film parallel to long axes of teeth by placing far away from lingual surfaces of teeth Two-point contact: maintain contact of top edge of film with palate & bite portion of holder with maxillary occlusal surfaces ![]() Smallest radiation source Target-film-distance long as practical Object-film-distance short as possible Parallel film to long axis of teeth Perpendicular alignment of beam to film & objects Ideal results: Sharp image Image of the true shape and size of the object being radiographedĤ Five Fundamental Principles of Shadow Casting Hock, RDH, MAdEd Dental Hygiene Department William Rainey Harper CollegeĪlso known as shadow casting Basic objective is to direct radiation toward client’s face so that radiation passes horizontally & vertically through the tissues to be examined & to the film at the most favorable angle with minimal distortion of the resulting image. Lesson 16: Periapical Radiographs & Intraoral Surveys Kathleen A.
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