Physics Bucharest 2017

VMAT

1. The MLC leaf trajectories as a function of time 2. The gantry angle as a function of time 3. The dose rate as a function of time

Beam fluence:

Gantry speed (mechanical limitations) Dose rate variations

Aperture weights (MU) variation:

Transition between adjacent apertures: MLC motion trajectories

→ as the gantry rotates the beam is on → the subfields of adjacent beam angles should not require the MLC leaves to travel long distances (ensuring smooth leaf motion in the leaf-sequencing algorithm)