Thumb (lateral view)

The thumb lateral view is an orthogonal projection to AP/PA view and helps in the localisation of a foreign body in the thenar eminence.

Patient position

• patient is seated alongside the table
• forearm is placed on table
• the wrist is kept in ulnar deviation and thumb abducted
• lateral aspect of thumb is brought in contact with the cassette by curling fingers (see Figure 1)

X-ray beam features

Collimation:

To include entire thumb and carpometacarpal joint, centring approximately over the metacarpophalangeal joint space.

Marker Placementplacement: AP, distal and anterior

Grid: Nono

SID: 100cm100 cm

Exposure Factorsfactors: 45 kV, 1.6 mAs

Please Notenote:These are average exposures using a Siemens DR system. Exposures may vary between different CR or DR systems and with different patient body habitus.

Image critique

(Figure 2)

Collimation

Appropriate collimation has been utilised with the entire first digit is visualised, including the carpometacarpal (CMC) joint.

Positioning

1st digit is positioned laterally, evidenced by open joint spaces and superimposition of the phalangeal and metacarpal heads. There is slight superimposition of the base of the 2nd metacarpal over the base of the 1st metacarpal, which is not ideal.

Exposure

Appropriate exposure evidenced by adequate bony detail visible in entire thumb, with soft tissue visualised clearly.