Indications for imaging
Trauma, rheumatology, congenital,
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Anatomy Demonstrated
Distal and proximal phalanges, first metacarpal and associated
joints.
Rt Thumb Lat Anatomy
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Basic Patient Position
The patient sits alongside the end of the table elbow flexed
palm downwards, or at the end of the table with he elbow flexed
at 90 degrees, hand and wrist flat on the cassette the elbow may
need a small pad to promote contact of the hand with the cassette. The
fingers can be spread slightly.
the thumb is abducted and the hand internally rotated and
supported in position such that the thumb is lateral and in
contact with the cassette.
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Radiation protection
Direct lead rubber gonad protection using a "half
apron".
Ensure the lower limbs and torso are not below the table top in
the primary beam.
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Central Ray
The vertical central ray is centered to the center of the first
metacarpophalangeal joint.
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Exposure Factors
| Kv |
mAS |
FFD (cm) |
Grid |
Focus |
AEC |
Cassette |
| 60 |
4 |
100 |
No |
Fine |
No |
18 x 24 cm |
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Evaluation of the Image
ID and markers must be present and correct in the appropriate
area of the film
Evidence of collimation on four sides equally around the
centering point.
Limits of the examination, distally the tip of the distal
phalanx, proximally the trapezium, the skin surface externally
and the 2nd metacarpal medially.
The thumb should be true lateral with the dorsal surface
of the 1st metacarpal almost flat.
The joint spaces should be open.
Exposure, adequate penetration to visualise all bone detail and
low enough contrast to visualise the soft tissues.
Rt Thumb Lat Radiograph
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Related Projections
Thumb AP.
Wrist for Scaphoid and Trapezium
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Additional modalities
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