1Department of Medical Physics;
Graduate School of Medicine;
Sapporo Medical University;
Sapporo;
Japan 4Radiation Therapy Research Institute;
Social Medical Corporation Teishinkai;
Sapporo;
Japan;
Department of Medical Physics;
Graduate School of Medicine;
Sapporo Medical University;
Sapporo;
Japan;
Department of Medical Physics;
Graduate School of Medicine;
Sapporo Medical University;
Sapporo;
Japan Department of Radiology;
Sapporo Medical University;
Sapporo;
Japan;
Department of Medical Physics;
Graduate School of Medicine;
Sapporo Medical University;
Sapporo;
Japan Nikko Memorial Hospital;
Muroran;
Japan;
IMRT; IGRT; Radiation; Therapy; Immobilization; Head; and; Neck; Cancer;