Sesamoids - AxialThis is a featured page

Radiographic Positioning


Adult
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Name of projection Foot - Axial - Sesamoids
Area Covered Head of the first metatarsal, sesamoid bones
Pathology shownExtent of injury to sesamoid bones
Radiographic AnatomyFoot Radiographic Anatomy
IR Size & Orientation 18cm x 24 cm
Landscape
Film / Screen Combination Detail
(CR and DR as recommended by manufacturer)
Bucky / Grid No
FilterNo
Exposure 50 kVp
2 mAs
FFD / SID 100cm
Central Ray Directed to the first metatarsophalangeal joint
Perpendicular to the IR
Collimation To include the distal 1st, 2nd and 3rd metatarsals
Markers Distal and lateral
Marker orientation AP
Shielding Gonadal (check your department's policy guidelines)
RespirationNot applicable
PositioningLewis Method
  • Patient is prone on the table
  • Make the patient comfortable - pillow for their head, sponges under their knee and ankle
  • Ensure the long axis of the foot is not rotated
  • Place the big toe on the IR in a dorsiflexed position
  • Place the ball of the foot so that it is perpendicular to the IR
  • The plantar surface should be about 20° from the vertical
Holly Method
  • Patient is seated on the table, legs extended
  • Position foot so that the plantar surface is about 20° from the vertical (that is, the foot is slightly extended)
  • The toes are held in a flexed position by the patient (using a strip of bandage to assist them)
    Critique

    Positioning
    • Sesamoids are in profile
    • sesamoids are not superimposed by the metatarsals
    • Correct dorsiflexion of the foot shown by the distal ends of the 1st, 2nd and 3rd metatarsals seen in profile
    Area Covered
    • Distal 1st, 2nd and 3rd metatarsals, MTP joint, sesamoids
    Collimation
    • Centre: The first metatarsophalageal (MTP) joint
    • Shutter A: Open to include the 1st to 3rd distal metatarsals
    • Shutter B: Open to include the soft tissue of the ball of the foot and the distal metatarsals
    Exposure
    • bony trabecular patterns and cortical outlines are sharply defined
    • soft tissues are visualised
      Special NotesAlthough the Holly Method is usually more comfortable for the patient, the increased object to image receptor distance (OID) is greater, so the sesamoids will appear more magnified, with some accompanying loss of definition.



      AndyC
      AndyC
      Latest page update: made by AndyC , Jun 17 2011, 11:17 AM EDT (about this update About This Update AndyC Edited by AndyC

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