Clinical analysis of IMRT-induced Temporomandibular Joint Lesion in Patients with Nasopharyngeal Carcinoma

Objective:To compare the Radiation-induced prismns in nasopharyngeal carcinoma patients treated with IMRT to that with conventional radiotherapy.Methods:Seventy four nasopharyngeal carcinoma patients were treated with conventional radiotherapy(41 cases) and IMRT(33 cases).Bilateral facial-neck fields were adopted as the main fields with conventional radiotherapy,the total dose ranged from 70 to 74 Gy.7 conformal fields were adopted with IMRT,the total dose ranged from 69.4 to 74.8 Gy.The distance between 2 dens incisivus medialis (DDIM) was measured before radiotherapy,and 1 year after radiotherapy.Results:The calculated DDIM was 4.03 ± 0.47 cm before RT,and 3.61 ± 0.81 cm 1 year post-RT with IMRT,which was better than that with conventional RT(P 0.01);The ratio of prismns with IMRT was 9.4%,which was much lower than that with conventional RT(P 0.01).Conclusion:IMRT can spare the temporomandibular joint from high dose irradiation.The risk of radiation-induced severe temporomandibular joint damage,namely prismns in NPC patients treated with IMRT is much lower than with conventional radiotherapy.