Category AP Caudal angulation Bilateral AP comparative Horizontal-beam lateral

Purpose Projects clavicle above scapula and ribs when cephalic angulation isn’t possible (e.g., kyphotic or supine patients) Compares both clavicles for asymmetry or bilateral injury, useful in trauma or congenital anomaly assessment Demonstrates lateral clavicle profile in acute trauma when rotation is limited, free of superimposition

Patient Position Upright or supine; arms at sides; midclavicle centered; midcoronal plane parallel to IR Upright; arms at sides; IR cross-wise at manubrium; shoulders level Supine; arm neutral; IR placed cross-wise against superior shoulder surface

Central Ray & Angulation CR 15° caudad to midclavicle, perpendicular to IR CR perpendicular to midclavicles, enters at manubrium level CR horizontal, perpendicular to midclavicle, enters at clavicular midpoint

Exposure Factors & Justification 70 kVp; 10 mAs; 100 cm SID; grid — bone contrast optimized, scatter reduced 65 kVp; 12 mAs; 100 cm SID; grid — even density across wide field 70 kVp; 16 mAs; 100 cm SID; grid — higher mAs offsets increased OID and scatter

Breathing Instructions Suspend at end expiration Suspend at end expiration Suspend at end expiration

Common Errors & Corrections Underangulation → increase CR angle; rotation → level shoulders Rotation → adjust patient rotation; decentered CR → recenter at manubrium IR too low → raise IR; scapular overlap → rotate body; IR tilt → position IR vertically