Millennium MLC (80 / 120 leaf)

Multi-leaf collimator. Shapes the beam for IMRT, VMAT, RapidArc. Individual leaf motors are the top MLC failure point.

Fits

• Varian Clinac iX
• Varian Trilogy, 21EX

Diagnosis

• Stuck leaf → plan execution fails
• Position drift → physicist-flag at monthly QA