Thumb - Oblique

Radiographic Positioning

Adult

Other related pages of interest Applied Radiography Radiographic Anatomy Radiographic Protocols

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 PACEMAN	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