The feasibility of prescription dose escalation for nasopharyngeal carcinoma cancer using helical tomotherapy / 中华放射医学与防护杂志

ABSTRACT

Objective To study the feasibility of helical tomoterapy (HT) at prescription dose escalation for nasopharyngeal carcinoma (NPC).Methods Static-IMRT (sIMRT) and HT plans were designed for 10 nasopharyngeal carcinoma patients which were treated by sIMRT and HT treatment plan.Prescription dose was escalated for each plan until any organs at risk (OARs) reached the quantitative analysis of normal tissue effects within the clinical threshold.Dosimetric factors of target and OARs were analyzed for both sIMRT and HT plans.Results Compared with sIMRT plan, prescribed dose of HT plans increased 42.6％ (t =6.373, P ＜ 0.01), and the homogeneity index was also improved (t =-2.288, P＜0.05);the conformity index decreased (P ＞ 0.05).The limits of HT prescribed dose escalation were spinal cord (2 cases), optic nerve (5 cases) and brainstem (3 cases).The limits of sIMRT prescribed dose escalation were lens (1 case), spinal cord (1 case) and parotid (8 cases).Conclusions HT could improve prescription dose of nasopharyngeal carcinoma while keeping the OARs safe.Compared with sIMRT, HT technology might be used at high dose NPC radiotherapy.