[Multileaf Collimator Position Accuracy of Respiratory Gated VMAT].

Respiratory gated VMAT (volumetric modulated arc therapy) repeats rapid stop and go operations of a MLC (multileaf collimator) by turning the beam on and off by respiratory gating. The rapid stop and go operations of the MLC during respiratory gated irradiation may induce position error of the MLC and may affect output error and dose distribution. The purpose of this study was to clarify the relationship between the MLC position accuracy of the respiratory gated VMAT and the VMAT parameters.