Thumb - Lateral

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Radiographic Positioning

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Name of projection Thumb - Lateral
Area Covered Distal and proximal first phalanx, metacapal, carpometacarpal joint, 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: From distal phalanx to trapezium
Shutter B: To include soft tissues
Markers Distal and Lateral
Marker orientation AP
Shielding Gonadal (check your department's policy guidelines)
Respiration Not applicable
  • Seated at end of table
  • Palmar surface of hand down
  • Flex hand slightly until thumb is in lateral position
  • Thumb against IR
  • Long axis of thumb in line with axis of IR
  • Centre to metacarpophalangeal joint

  • First digit in true lateral position is demonstrated by
    • anterior surface of proximal phalanx is concave
    • posterior surface of proximal phalanx and metacarpal will be slightly convex
    • Thumbnail, if visualised, will be in profile
    • Proximal first metacapal slightly super-imposed by proximal second metacarpal
  • The following joint spaces are open: metacarpophalangeal, interphalangeal, carpometacarpal
  • Long axis of digit is aligned with long axis of IR
  • Centred to metacarpophalangeal joint
Area Covered
  • Distal and proximal first phalanx, metacapal, carpometacarpal joint, trapezium
  • Centred to first metacarpophalangeal joint
  • Opened to include distal phalanx to trapezium and soft tissues
  • Bony trabecular patterns and cortical outlines are sharply defined
  • Soft tissues are visualised
Special Notes