Podcast
Questions and Answers
What is the recommended central ray (CR) angle for an AP projection of the thumb, using the Lewis method?
What is the recommended central ray (CR) angle for an AP projection of the thumb, using the Lewis method?
- $0^\circ$
- Perpendicular to the image receptor
- 15-20 angled toward the elbow
- 10-15 angled toward the wrist (correct)
During a PA oblique projection of the thumb, what specific hand positioning is required to ensure accurate imaging?
During a PA oblique projection of the thumb, what specific hand positioning is required to ensure accurate imaging?
- Hand in a natural arched position with the palmar surface down.
- Hand in extreme internal rotation.
- Hand in slight ulnar deviation with the thumb abducted. (correct)
- Hand in lateral position with the dorsal surface parallel to the image receptor.
How should the hand be positioned for a lateral projection of the thumb?
How should the hand be positioned for a lateral projection of the thumb?
- In slight ulnar deviation.
- In a natural, arched position with the palmar surface down. (correct)
- Dorsal surface parallel to the image receptor.
- In extreme internal rotation.
Which projection of the thumb is best for demonstrating superimposition of the trapezium?
Which projection of the thumb is best for demonstrating superimposition of the trapezium?
Which projection of the digits (2nd to 5th) requires the patient to rotate their hand 45 laterally?
Which projection of the digits (2nd to 5th) requires the patient to rotate their hand 45 laterally?
When performing a lateral projection of the 2nd or 3rd digit, which describes the direction of the X-ray beam?
When performing a lateral projection of the 2nd or 3rd digit, which describes the direction of the X-ray beam?
In imaging the digits (2nd to 5th), what is an alternative to the standard PA projection if the patient cannot extend their digits?
In imaging the digits (2nd to 5th), what is an alternative to the standard PA projection if the patient cannot extend their digits?
For which scenario involving the digits (2nd to 5th) might an AP projection be specifically indicated as an alternative to the PA?
For which scenario involving the digits (2nd to 5th) might an AP projection be specifically indicated as an alternative to the PA?
Why might a PA oblique projection of the digits (2nd to 5th) be preferred over a standard PA projection?
Why might a PA oblique projection of the digits (2nd to 5th) be preferred over a standard PA projection?
What is the primary purpose of using the PA oblique projection of the digits, with either lateral or medial rotation?
What is the primary purpose of using the PA oblique projection of the digits, with either lateral or medial rotation?
Flashcards
AP Projection (Thumb)
AP Projection (Thumb)
Hand in extreme internal rotation. 10-15° cephalad CR toward the wrist, thumb free of soft tissue of palm.
PA Projection (Thumb)
PA Projection (Thumb)
Hand in lateral position; Dorsal surface of thumb parallel to IR
PA Oblique Projection (Thumb)
PA Oblique Projection (Thumb)
Hand in slight Ulnar deviation; thumb abducted.
Lateral Projection (Thumb)
Lateral Projection (Thumb)
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PA Oblique (Lateral Rotation)
PA Oblique (Lateral Rotation)
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PA Oblique (Medial Rotation)
PA Oblique (Medial Rotation)
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Lateral (Lateromedial)
Lateral (Lateromedial)
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Lateral (Mediolateral)
Lateral (Mediolateral)
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Alternative of PA projection
Alternative of PA projection
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Study Notes
Thumb (1st Digit) & Digits (2nd to 5th) Projections
Thumb 1st MCP Jt (APPL)
- AP projection involves hand in extreme internal rotation
- The central ray (CR) goes to the 1st MCP joint
- Lewis method: angle CR 10-15° toward the wrist, thumb free of soft tissue
- PA projection involves hand in lateral position, the dorsal surface of thumb is parallel to image receptor (IR)
- The CR goes to the 1st metacarpophalangeal joint resulting in a magnified thumb
- PA oblique projection involves the hand in slight ulnar deviation and thumb abducted
- The CR goes to the 1st MCP joint resulting in a PA oblique projection of the thumb
- Lateral Projection: place hand in arched position with palmer side down, CR @ 1st MCP Jt to get a lateral projection of thumb w superimposition of trapezium
Digits (2nd to 5th) Projection
- PA projection; CR goes to the proximal interphalangeal joint PIP.
- PA Oblique (Lateral Rotation) rotates 45° laterally and Medial Rotation rotates 45° medially
- PA Oblique Rotations increases recorded detail and detects other fractures
- Lateral projections can be lateromedial for the 4th and 5th digits or mediolateral for the 2nd and 3rd digits to look for foreign bodies
- AP projection is an alternative to PA projection if the patient can't extend digits, use a small dental film for suspected joint injury
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