A comparison of dose and set-up accuracy between flexed and extended neck positions in Helical Tomotherapy of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) patients treated with Helical Tomotherapy (HT) are commonly set up in an extended neck (EN) or a flexed neck (FN) position. This study investigated the dosimetric and set-up accuracy differences between these 2 set-up positions. Twenty NPC patients treated with HT from each set-up position were retrospectively recruited.