Mandible - SMVThis is a featured page

Radiographic Positioning


Adult
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Name of projection Mandible - SMV
Area Covered Entire mandible, coronoid and condyloid process
Pathology shownFractures of mandible, neoplastic and inflammatory changes
Radiographic AnatomyMandible Radiographic Anatomy
IR Size & Orientation 18 x 24cm
landscape
Film / Screen Combination Regular
(CR and DR as recommended by manufacturer)
Bucky / Grid Moving or Stationary Grid
FilterNo
Exposure 70 kVp
18 mAs
FFD / SID 100cm
Central Ray CR perpendicular to infraorbitomeatal line (IOML)
Centre to a point midway between the angles of mandible, 4cm inferior to mandibular symphysis
Collimation Collimate to area of mandible
Markers Lateral
Marker orientation AP
Shielding Gonadal (check your department's policy guidelines)
RespirationSuspended
Positioning
  • The aim is to get the Infraorbitomeatal Line (IOML) parallel to the IR and bucky. The method used to achieve this will depend on the presentation of the patient.
  • The following description is for patients who are able to tip their head back, hyperextending their neck, and are able to sit.
    • The patient sits in an AP position in front of the upright bucky
    • The chin is raised and the head tipped back until the IOML is parallel to the bucky and the vertex of the skull is centred and resting against the bucky.
    • If the patient is able to achieve this position then the central ray is perpendicular to both the bucky and the IOML.
    • If the patient is unable to tip their head back far enough, then angle the central ray so that it is perpendicular to the IOML
    • Ensure the midsagittal plane is perpendicular to the bucky
    • Centre to a point midway between the angles of mandible, 4cm inferior to mandibular symphysis
Critique

Positioning
  • No rotation is evidenced by
    • Equal distance from mandible to lateral border of skull on both sides
    • Mandibular coronoid processes visualised projecting laterally from the rami area equally on each side of mandible
  • No tilt is evidenced by
    • The vomer and the bony nasal septum are aligned with the long axis of the film.
  • The central ray is at 90 degrees to the IOML, evidenced by
    • The mandibular mentum superimposes the outer border of the frontal bone.
Area Covered
  • Entire mandible, coronoid and condyloid process
Collimation
  • Centre: Centre to a point midway between the angles of mandible
  • Shutter A: Open to include the soft tissue and lateral borders of the mandible
  • Shutter B: Open to include the mandible superiorly and condyloid process of mandible inferiorly
Exposure
  • Assess for adequate penetration of the thickest part of the skull
  • Bony trabecular patterns and cortical outlines are sharply defined
  • Soft tissues are visualised
Special Notes



AndyC
AndyC 		Latest page update: made by AndyC , Jun 17 2011, 8:40 AM EDT (about this update About This Update AndyC Edited by AndyC


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