ABSTRACT
PURPOSE: The aim of this prospective study was to evaluate daily set-up by a radiation oncologist and by radiation therapists using on-board imaging of patients with head and neck cancer in order to calculate margin to PTV (planning target volume) and intent partial delegation of positioning images control. PATIENTS AND METHODS: The files of 11 patients with head and neck cancer treated on a Synergy™ (Elekta™) accelerator with on-board imaging system were evaluated. Daily kV-kV images were double-blind reviewed by radiation therapists (7 participants) and by one radiation oncologist. The radiation oncologist's measures were used for margin calculation from CTV to PTV. The difference of measures and the concordance of decisions between radiation therapists and the radiation oncologist were calculated. RESULTS: The 325 measures made by the radiation oncologist resulted in a margin of 5mm to be applied to the CTV in each direction. Nine hundred seventy-seven measures were made by the radiation oncologist and radiation therapists with a difference of 3mm or less in 98.46%. The concordance of decision for a 4mm difference or less to the isocenter was 96.7%. CONCLUSION: This study confirms the 5mm PTV margin mostly used in ORL. The small gap between the radiation oncologist's and therapists' measures allows a partial delegation of positioning images control.
