IMRT 2018

Gap between closed leaves

• Opposing MLCs may not be fully closed • Important to measure gap between leaves • Deviation results large errors

Dynamic MLC

Clinical prostate plan with simulated error in leaf gap ( ± 2%)

LoSasso, MedPhys 25, 1998. Physical and dosimetric aspects of a multileaf collimation system used in the dynamic mode for implementing intensity modulated radiotherapy. Zwan, J Appl Clin Med Phys 17,2016. An EPID-based system for gantry-resolved MLC quality assurance for VMAT