Evaluation of MLC performance in VMAT and dynamic IMRT by log file analysis.

Purpose: This multi-institution study assessed the positioning accuracy of multileaf collimators (MLC) by analyzing log files. It determined the main machine parameters that affect MLC positioning errors for pre-TrueBeam (Clinac) and TrueBeam linacs.

Methods: Around 30,000 dIMRT and VMAT log files belonging to 6 linacs from 4 different centers were analyzed.