Thumb - PA

Radiographic Positioning

Adult

Other related pages of interest Applied Radiography Radiographic Anatomy Radiographic Protocols

Name of projection	Thumb - PA or AP
Area Covered	Distal and proximal phalanx, carpometacarpal joint, metacarpal, 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 thumbs metacarpophalngeal joint Perpendicular to the IR
Collimation	Centre: Metacarpophalngeal joint Shutter A: Distal phalanx to carpometacarpal joint Shutter B: To include soft tissues
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 For AP: Rotate arm and hand internally until thumb is AP Thumbnail and thumb flat against IR For PA: Raise thumb until in the PA position (may use sponge support) For both: Long axis of thumb in centre line of IR Metacarpophalangeal joint in centre of IR Other digits held back out of the way Support elbow if it is elevated
Critique PACEMAN	Positioning No rotation of the digit demonstrated by equal concavity of phalangeal and metacarpal shafts equal amount of soft tissue on both sides of phalanges Thumbnail, if visualised, will be centred Long axis of digit is aligned with long axis of IR AP position: Soft tissue overlap of palm over midshaft of first metacarpal and carpometacarpal joint Following joint spaces are open: metacarpophalangeal, interphalangeal, carpometacarpal PA position: Palm soft tissue does not overlap metacarpal and carpometacarpal joint Carpometacarpal joint is closed Area Covered Distal and proximal first phalanx, carpometacarpal joint, first metacarpal and trapezium Collimation Centred at metacarpophalangeal joint Opened to include distal phalanx to trapezium Opened to include soft tissue Exposure Bony trabecular patterns and cortical outlines are sharply defined Soft tissues are visualised
Special Notes