Digits 2-5 PA is a radiography positioning projection of the Upper Extremity. Seated, hand pronated, palm down on IR. SID 40". The centering point is located PIP joint of the affected digit. The central ray is perpendicular to the PIP joint of the affected digit. Image-quality criteria include affected digit shown in true PA with no rotation, all three phalanges and the distal metacarpal included. A sample technique is 63 kVp with DR 0.6 or CR 1.6 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Distal, middle, and proximal phalanges of digits 2-5.
- Distal portion of the adjoining metacarpal.
- DIP, PIP, and MCP joint spaces.
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient; do not rotate a severely injured part or remove splints (Bontrager). Merrill's: do not attempt true AP or lateral positioning of a severely injured limb; take two projections 90 degrees apart, moving it as little as possible, and move the IR and tube if the patient cannot reach the position.
- Verify patient identity using two identifiers.
- Remove rings, bracelets, and radiopaque items from the hand.
- Seat the patient at the end of the table.
- Flex the elbow about 90 degrees with hand pronated (palm down on IR).
- Extend fingers and slightly separate digits on IR.
Position & centering point
PIP joint of the affected digit.
Central ray
Perpendicular to the PIP joint of the affected digit.
Exposure / technique
- kVp
- 63
- mAs
- DR 0.6 / CR 1.6
- SID
- 40" (102 cm)
- Notes
- Tabletop technique. Digits extended and slightly separated. Merrill's: digits that cannot be extended can be examined in small sections, and when joint injury is suspected an AP is recommended instead of a PA. Sample technique: DR 0.6 / CR 1.6 mAs at 63 kVp, 40 in SID, for a 1.5 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Affected digit shown in true PA with no rotation.
- All three phalanges and the distal metacarpal included.
- Joint spaces open and clearly visible.
- Soft tissue and bone trabeculae sharp, no motion blur.
- Collimation: 1 inch on all sides, 1 inch proximal to MCP joints.
Common errors
- 1 Hand not fully pronated for the PA: open IP joints show it was.
- 2 CR not at the PIP joint of the affected digit.
- 3 Uneven digit separation causes overlapping images.
Clinical indications
- Trauma evaluation for finger fracture or dislocation.
- Assessment of finger joint arthritis or degenerative changes.