Thumb - ObliqueThis is a featured page

Radiographic Positioning


Adult
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Name of projection Thumb - Oblique
Area Covered Distal and proximal first phalanx, carpometacarpal joint, first metacarpal and trapezium
Pathology shown Fracture, dislocation, foreign body, infection, tumour, arthritis
Radiographic Anatomy Hand Radiographic Anatomy
IR Size & Orientation 18 x 24cm
Landscape, divided for multiple thumb images, use lead masking for unused area
Film / Screen Combination Detail
(CR and DR as recommended by manufacturer)
Bucky / Grid No
Filter No
Exposure 50 kVp
2.5 mAs
FFD / SID 100cm
Central Ray Directed to first metacarpophalangeal joint
Perpendicular to IR
Collimation Centre: First metacarpophalangeal joint
Shutter A: Distal phalanx to trapezium
Shutter B: Skin line
Markers Distal and Lateral
Marker orientation AP
Shielding Gonadal (check your department's policy guidelines)
Respiration Not applicable
Positioning
  • Patient seated at end of table
  • Palm down - thumb is at 45°
  • Abduct thumb
  • Thumb flat against IR
  • Ulna deviate hand slightly
  • Long axis of thumb in line with IR and light field
  • Centred to metacarpophalangeal joint
Critique

 Positioning
  • Correct rotation of thumb is demonstrated by:
    • twice as much soft tissue and more phalangeal and metacarpal midshaft concavity on the raised side of the thumb (next to the fingers)
  • Metacarpophalangeal, interphalangeal and carpometacarpal joints spaces are open
  • Long axis of digit aligned with long axis of IR
  • Phalanges are not foreshortened
Area Covered
  • Distal and proximal first phalanx, carpometacarpal joint, first metacarpal and trapezium
Collimation
  • Centred to first metacarpophalangeal joint
  • Opened to include distal phalanx to trapezium and the soft tissue
Exposure
  • Bony trabecular patterns and cortical margins are sharply defined
  • Soft tissues are visualised
Special Notes



AndyC
AndyC 		Latest page update: made by AndyC , Jun 17 2011, 2:25 PM EDT (about this update About This Update AndyC Edited by AndyC

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Keyword tags: oblique thumb phalange phalynx thumb thumb oblique thumb positioning
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