IMRT Article 2 Humans 2 Radiotherapy, Intensity-Modulated 2 VMAT 2 cancer radiotherapy 2 human 2 intensity modulated radiation therapy 2 radiation dose distribution 2 3D dose distribution 1 Back-projection 1 Calibration 1 Dose constraints 1 Dose distributions 1 Dose objectives 1 Dose verification 1 Dose-Response Relationship, Radiation 1 EPID dosimetry 1 Head 1 Head and Neck Neoplasms 1 Head and neck 1 Incidence 1 Independent analysis 1 Intensity-modulated radiation therapy 1 Irradiation fields 1 Light distribution 1 Medline 1 Monte Carlo dose inhomogeneity conversion 1 NTCP 1 Neck 1