Table 2.

Planning parameters used for optimization. The IMRT beam arrangement is currently employed clinically in our center for nasopharynx plans

IMRT	VMAT
7 co‐planar beams (gantry angles 205°, 255°, 305°, 0°, 50°, 105°, 155°)	2 arcs (clockwise and anticlockwise, 182° to 178°)
Minimum segment area 4 cm2	4° control point spacing
Minimum MU per segment 2	Maximum delivery time 300 s
Maximum number of segments 100	Leaf motion unconstrained between control points
Final dose calculation: Adaptive collapsed cone convolution	Final dose calculation: Adaptive collapsed cone convolution