Helical tomotherapy (HT) is conceptually regarded an image-guided IMRT. HT was designed and developed with advantages in sharper dose gradients and better normal tissue sparing. Our and the other clinical experience of using HT for locally advanced head and neck cancer had achieved encouraging results along with less toxicity, such lower percentage of dermatitis and xerostomia when compared with previous reports (16-18). HT provides better normal tissue sparing and sharper dose gradients than IMRT (19, 20).Chen et al. (19) compared HT and IMRT for nasopharyngeal carcinoma and noted that HT significantly reduced dose to the contralateral parotid gland and improved dose homogeneity to the PTVs. Additionally, HT reduced mean doses to brainstem (p = 0.02), larynx (p = 0.03), and oral cavity (p = 0.03). Similarly, for head-and-neck cancer, HT plans also provided favorably results compared with the step-and-shoot IMRT plans. They are expected to be able to reduce the parotid normal tissue (average 6.5 Gy) complication probability further, keeping similar target dose homogeneity (21). Furthermore, HT provided better mandible sparing than IMRT with mean dose decreased from 34.9 Gy (IMRT) to 30.7 Gy (HT) (20). However, can HT provide better normal tissue sparing to reduce the incidence of trismus? It's still an interesting issue to discuss.