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Chapter 23 Extraoral Imaging Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. Dental Radiography Questions What equipment is used in extraoral imaging? What is the purpose of each of the projections that is used for skull imaging? Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 2 Dental Radiography Chapter 23 Reading Iannucci & Howerton (pp. 274-289) Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 3 Dental Radiography Chapter 23 Outline Extraoral Imaging Basic concepts Step-by-step procedures Extraoral projection techniques Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 4 Introduction Iannucci & Howerton (p. 274) Purpose To present the basic concepts of extraoral imaging and describe the necessary patient and equipment preparations To introduce a number of extraoral projection techniques and describe the receptor placement, patient positioning, and beam alignment for such projections Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 5 Basic Concepts Iannucci & Howerton (pp. 274-275) Extraoral radiograph An image that is placed outside the mouth during x-ray exposure Used to image large areas of the skull or jaws Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 6 Purpose and Use Iannucci & Howerton (p. 275) To evaluate large areas of the skull or jaws To evaluate growth and development To evaluate impacted teeth To detect diseases, lesions, and conditions of the jaws To examine the extent of large lesions To evaluate trauma To evaluate the temporomandibular joint area Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 7 Equipment Iannucci & Howerton (p. 275) X-ray unit Film Intensifying screens Cassette Grid Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 8 X-ray Unit A standard intraoral x-ray machine may be used for a variety of extraoral projections. Iannucci & Howerton (p. 275) (Figs. 23-1, 23-2) Special head positioning and beam alignment devices can be added. Some panoramic x-ray units can be used for extraoral projections. The panoramic tubehead is used in conjunction with a special extension arm and a device known as a cephalostat or craniostat. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 9 Film Most extraoral exposures are made with screen film placed in a cassette with intensifying screens. Iannucci & Howerton (pp. 275-276) Screen film is sensitive to the light emitted from intensifying screens. An occlusal film is a nonscreen film that may be used for some extraoral radiographs. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 10 Intensifying Screens Iannucci & Howerton (p. 276) A device that converts x-ray energy into visible light; the light, in turn, exposes the screen film The screen film must be compatible with the light emitted from the screen. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 11 Cassette Iannucci & Howerton (p. 276) Purpose is to hold the receptor in tight contact with the intensifying screen and to protect the film from exposure to light. Must be labeled to orient the finished image. The front side is typically constructed of plastic, back side is made of metal. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 12 Grid A device used to reduce the amount of scatter radiation that reached an extraoral film during exposure Iannucci & Howerton (p. 276) (Fig. 23-3) A series of thin lead strips embedded in a material that permits passage of the x-ray beam The grid is placed between the patient’s head and the film. During exposure, the grid permits passage of the x-ray beam between the lead strips. Scatter radiation is absorbed by the lead strips and does not reach the surface of the film. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 13 Step-by-Step Procedures Equipment Preparation Patient Preparation Patient Positioning Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 14 Step-by-step Procedures Infection control procedures must be complete before exposing an extraoral receptor. If an extraoral unit with cephalostat is used, the ear rods must be wiped with disinfectant between patients. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 15 Equipment Preparation Iannucci & Howerton (p. 276) (Procedure 23-1) Load the extraoral cassette in the darkroom under safelight conditions. Set the exposure factors according to the manufacturer’s recommendations. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 16 Patient Preparation Iannucci & Howerton (pp. 276-277) (Procedure 23-2) Explain the radiographic procedure to the patient. Place a lead apron without a thyroid collar over the patient and secure it. Remove all objects from the head and neck region that may interfere with exposure. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 17 Patient Positioning Varies with each extraoral radiographic projection Discussed in section on specific extraoral projection techniques Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 18 Extraoral Projection Techniques Iannucci & Howerton (pp. 277-278) (Table 23-1) Lateral Jaw Imaging Skull Imaging Temporomandibular Joint Imaging Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 19 Lateral Jaw Radiography Iannucci & Howerton (pp. 277) Used to examine the posterior region of the mandible Includes • Body of the mandible projection • Ramus of the mandible projection Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 20 Body of the Mandible Purpose To evaluate impacted teeth, fractures, and lesions located in the body of the mandible Receptor placement Iannucci & Howerton (pp. 277, 279) (Fig. 23-4) Flat against cheek Centered over body of mandible Head position Tipped 15 degrees toward side being imaged Chin extended and elevated Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 21 Body of the Mandible Beam alignment Below inferior border of mandible, vertical angulation -15 to -20 degrees Perpendicular to horizontal plane of cassette Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 22 Ramus of the Mandible Purpose To evaluate impacted third molars, large lesions, and fractures that extend into the ramus of the mandible Receptor placement Iannucci & Howerton (pp. 277, 280) (Fig. 23-5) Flat against cheek, centered over ramus of mandible Head position Tipped 15 degrees toward side being imaged Chin extended and elevated Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 23 Ramus of the Mandible Beam alignment Posterior to third molar area Vertical angulation -15 to -20 degrees Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 24 Skull Imaging Iannucci & Howerton (pp. 277-278) Used to examine the bones of the face and skull Used most often in oral surgery and orthodontics Includes: • Lateral cephalometric projection • Posteroanterior projection • Waters projection • Submentovertex projection • Reverse Towne projection Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 25 Lateral Cephalometric Projection Purpose Iannucci & Howerton (pp. 278, 281) (Fig. 23-6) To evaluate facial growth and development, trauma, and disease and developmental abnormalities Receptor placement Cassette perpendicular to the floor Long axis of cassette horizontal Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 26 Lateral Cephalometric Projection Head position Beam alignment Left side of patient’s head near cassette Midsagittal plane perpendicular to the floor Frankfort plane parallel to the floor Central ray perpendicular to the cassette Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 27 Posteroanterior Projection Purpose Iannucci & Howerton (pp. 282-283) (Fig. 23-7) To evaluate facial growth and development, trauma, and disease and developmental abnormalities Receptor placement Cassette perpendicular to the floor Long axis of cassette horizontal Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 28 Posteroanterior Projection Head position Beam alignment Forehead and nose touch cassette Midsagittal plane perpendicular to the floor Frankfort plane parallel to the floor Central ray perpendicular to the cassette Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 29 Waters Projection Purpose To evaluate the maxillary sinus area Receptor placement Iannucci & Howerton (pp. 282,284) (Fig. 23-8) Cassette perpendicular to the floor Long axis of the cassette is vertical Head position Chin touches cassette Tip of nose ½ -1 inch from cassette Midsagittal plane perpendicular to the floor Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 30 Waters Projection Beam alignment Central ray through center of the head and perpendicular to the cassette Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 31 Submentovertex Projection Purpose Iannucci & Howerton (pp. 282, 285) (Fig. 23-9) To identify the position of the condyles, demonstrate the base of the skull, and evaluate fractures of the zygomatic arch Receptor placement Cassette perpendicular to the floor Long axis of the cassette is vertical Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 32 Submentovertex Projection Head position Beam alignment Head tipped back Top of head touches cassette Midsagittal plane and Frankfort plane perpendicular to the floor Central ray through center of the head and perpendicular to the cassette Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 33 Reverse Towne Projection Purpose Iannucci & Howerton (pp. 282, 286) (Fig. 23-10) To identify fractures of the condylar neck and ramus area Receptor placement Cassette perpendicular to the floor Long axis of the cassette is vertical Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 34 Reverse Towne Projection Head position Beam alignment Head tipped down Mouth open wide as possible Top of forehead touches cassette Midsagittal plane perpendicular to the floor Central ray through center of the head and perpendicular to the cassette Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 35 Temporomandibular Joint Imaging Iannucci & Howerton (p. 282) The joint includes the temporal bone and the mandible. The glenoid fossa and articular eminence of the temporal bone, the condyle of the mandible, and the articular disk between the bones comprise the TMJ. Includes • Transcranial projection • Temporomandibular joint tomography Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 36 Transcranial Projection (Lindblom Technique) Purpose Iannucci & Howerton (pp. 282, 287) (Fig. 23-11) To evaluate the superior surface of the condyle and the articular eminence Receptor placement Flat against patient’s ear Centered over TMJ Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 37 Transcranial Projection Head position Beam alignment Midsagittal plane perpendicular to the floor and parallel with the cassette 2 inches above and 0.5 inch behind the ear canal opening Vertical angulation +25 degrees, horizontal angulation forward 20 degrees Exposure factors Vary with the receptor, intensifying screens, and equipment used Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 38 Temporomandibular Joint Tomography Iannucci & Howerton (pp. 287-288) (Fig. 23-12) Used to examine the temporomandibular joint The location of the rotational point determines what plane of the head of the TM joint will be imaged. Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 39