Podcast
Questions and Answers
What is the IR size for all projections of the digits, thumb, and hand?
What is the IR size for all projections of the digits, thumb, and hand?
18 x 24 cm
What is the typical range for mAs technical factor settings?
What is the typical range for mAs technical factor settings?
At what joint does the CR enter the patient for the PA projection of Digits 2 to 5?
At what joint does the CR enter the patient for the PA projection of Digits 2 to 5?
The part position for lateral projection of Digits 2 to 5 requires the phalanges to be rotated from true lateral.
The part position for lateral projection of Digits 2 to 5 requires the phalanges to be rotated from true lateral.
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What is a proper technical factor used for imaging the digits?
What is a proper technical factor used for imaging the digits?
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In the PA oblique projection, the digit of interest is extended with the palmar surface resting on a ______ degree wedge sponge.
In the PA oblique projection, the digit of interest is extended with the palmar surface resting on a ______ degree wedge sponge.
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What should be included in the evaluation criteria for the PA projection of Digits 2 to 5?
What should be included in the evaluation criteria for the PA projection of Digits 2 to 5?
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In the lateral projection of the thumb, where does the CR enter?
In the lateral projection of the thumb, where does the CR enter?
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Study Notes
Essential Projections of the Digits, Thumb, and Hand
- All images should be taken with an 18 x 24 cm image receptor (IR).
- Technical factors: mAs 1.6 – 2.5, kVp: 63 – 70.
- Central ray should be perpendicular to the IR for all images.
Digits 2 to 5
- Essential projections: PA, lateral, PA oblique.
- Collimation: 2.5 cm on all sides of the digit, including 2.5 cm proximal to the MCP joint.
PA Digits 2 to 5
-
Part position:
- Extend the digit with the palmar surface in the center of the IR.
- Center the requested digit in the middle of the IR.
- Separate the fingers slightly.
- Long axis of digit aligned parallel.
-
CR:
- Perpendicular to the IR.
- Enters patient at the PIP joint.
-
Evaluation criteria:
- Proper collimation.
- No rotation of the phalanges.
- All three phalanges (distal, middle, proximal) included.
- Distal end of the metacarpal included.
- Open IP and MCP joint spaces.
- No superimposition of digits.
- Proper technical factors (clear soft tissue and bony trabeculae).
- Right or left marker included.
Lateral Digits 2 to 5
-
Part position:
- Separate the digit of interest using cotton swab or tape, and fold other digits into a fist.
- The digit of interest should be centered on the IR.
- The long axis of the digit should be parallel with the IR.
-
Second and third digits positioning:
- Extended with the lateral surface in contact with the IR (mediolateral projection).
- Minimizes object image distance (OID).
-
Fourth and fifth digits positioning:
- Extended with the medial surface in contact with the IR (lateromedial projection).
- Minimizes OID.
-
CR:
- Directed perpendicular to the IR.
- Enters patient at the PIP joint.
-
Evaluation criteria:
- Proper collimation.
- No rotation of the phalanges from a true lateral position.
- All three phalanges (distal, middle, proximal) included.
- Distal end of the metacarpal included.
- Open IP joint spaces.
- No superimposition of digits from the other fingers.
- Proper technical factors (clear soft tissue and bony trabeculae).
- Right or left marker included.
PA Oblique Digits 2 to 5
-
Part position:
- Extend the digit with the palmar surface resting on a 45-degree wedge sponge.
- Separate the digit of interest to prevent soft tissue overlap.
-
CR:
- Perpendicular to the PIP joint of the affected digit.
- Collimation: 2.5 cm on all sides of the digit.
-
Evaluation criteria:
- Proper collimation.
- Phalanges should appear obliqued.
- All three phalanges (distal, middle, proximal) included.
- Distal end of the metacarpal included.
- Open IP and MCP joint spaces.
- No superimposition of digits from the other fingers.
- Proper technical factors (clear soft tissue and bony trabeculae).
- Right or left marker included.
Thumb
- Essential projections: Anteroposterior (AP), lateral, PA oblique.
- Collimation: 2.5 cm on all sides of the digit, including 2.5 cm proximal to the CMC joint.
AP Thumb
-
Part position:
- Place the hand in extreme internal rotation.
- The posterior surface of the thumb should be on the IR.
- Center the MCP joint to the IR.
- Align the long axis of the thumb parallel to the IR.
- Separate other digits from the thumb with tape or the opposite hand.
- Ensure a true AP projection by checking the thumb's position.
-
CR:
- Perpendicular to the MCP joint.
-
Evaluation criteria:
- Proper collimation.
- Entire thumb to the trapezium included.
- Concavity of the phalangeal bodies visible.
- Open IP and MCP joint spaces.
- Proper technical factors (clear soft tissue and bony trabeculae).
- Left or right marker included.
PA Thumb (Alternative)
- Center the thumb and CR appropriately to the IR.
- Evaluation criteria is the same as the AP thumb projection.
- Magnification occurs due to the large OID.
Lateral Thumb
-
Part position:
- Palmar surface on the IR.
- Align the long axis of the thumb parallel to the IR.
- Center the MCP joint to the unmasked portion of the IR.
- Rotate the thumb until the lateral surface is on the IR (mediolateral projection).
-
CR:
- Perpendicular to the MCP joint of the thumb.
-
Evaluation criteria:
- Proper collimation.
- Entire thumb to the trapezium included.
- No rotation of the phalanges.
- Open IP and MCP joint spaces.
- Proper technical factors (clear soft tissue and bony trabeculae).
- Left or right marker included.
PA Oblique Thumb
-
Part position:
- Palmar surface of the thumb on the IR.
- Align long axis of thumb parallel.
- Place a 45-degree wedge sponge under the thumb.
- Center the MCP joint to the IR.
- Rotate the thumb 45 degrees.
-
CR:
- Perpendicular to the IR and the MCP joint.
-
Evaluation criteria:
- Proper collimation.
- Phalanges should appear obliqued.
- Open IP and MCP joint spaces.
- Proper technical factors (clear soft tissue and bony trabeculae).
- Left or right marker included.
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Description
This quiz covers essential projections for digits 2 to 5, focusing on proper collimation, part positioning, and evaluation criteria. It emphasizes technical factors necessary for accurate imaging and the central ray alignment for hand and digit radiography.
