- This position is performed commonly to evaluate for early evidence of rheumatoid arthritis at the second through fifth proximal phalanges and MCP joints. It also may demonstrate fractures of the base of the fifth metacarpal.
- Both hands generally are taken with one exposure for bony structure comparison of both hands.
- IR size - 24 x 30cm (10 x 12 inches), crosswise
- Detail screen or digital IR tabletop
- 55 to 65 kV range
|Ball Chatchers Position|
- Place lead shield over patient's lap to shield gonads.
- Seat patient at end of table with both hands extended.
- Supinate hands and place medial aspect of both hands together at center of IR.
- From this position, internally rotate hands 45degrees and support posterior of hands on 45degrees radiolucent block (figure 5-83).
- Extent fingers and ensure that they are relaxed, slightly separated but parallel to IR.
- Abduct both thumbs to avoid superimposition.
- CR perpendicular, directed to midpoint between both hands at level of fifth MCP joints
- Minimum SID of 40 inches (100cm)
- Collimate on four sides to outer margins of hands and wrist.
- A modification of the Norgaard method is the ball catcher's position with the finger partially flexed; this distorts the interphalangeal joints but visualizes the MCP joints equally well.
|Ball Chatchers X - Ray|
- Both hands from the carpal area to the tips of digits in 45degrees oblique position are visible.
45degrees oblique as evidence by the following:
- Midshafts of second through fifth metacarpals and base of phalanges should not overlap
- MCP joint should be open
- No superimposition of the thumb and second digit should occur
Collimation and CR:
- Collimation should be visible on four sides to outer margins of hands and wrist.
- CR and center of collimation field to midway between both hands at level of MCP joints.
- Optimal density and contrast with no motion are demonstrated by clear, sharp bony trabecular markings and joint space margins of MCP joints.