To Compare The Differents Imageological In Nasopharyngeal Carcinoma Of IMRT And To Observe The Short-term Clinical

Objective:To evaluate the exact of target region by MRI and the IMRT clinical efficacy,acute toxicities of intensity modulated radiotherapy for nasopharyngeal cancer patients.Materials and Methods:From SEP.2006 to DEC.2008,107 naive patients with histologically diagnosed NPC,received both computed tomography(CT) and magnetic resonance imaging(MRI) scans of the nasopharynx and cervical part.Clinical stage was classified according to the Chinese'92 staging system and the 6th edition UICC/AJCC staging system respectively,based on both CT/MRI imaging data and clinical information.To compare the differents between the two methods.59 patients of IMRT were retrospectively reviewed.Of the 59 patients by Clinical stage was classified according to the Chinese'92 staging system,1 had stageⅠ,20 hadⅡ,24 hadⅢand 14had stageⅣa disease.17patients received curative radiotherapy alone, and 42patients received radiotherapy combined with chemotherapy.The prescription dose was engaged to the GTVnx of nasopharyngeal to DT70～74Gy/ 30～31f,GTVnd to DT 66～70Gy/30～31f,CTV1 to 64 Gy/30～31f,and CTV2 to 54 Gy/30～31f.The GTVnx,CTV1 and upper neck were irradiated by IMRT technique.The lower neck and the supraclavicular fossae were irradiated with the conventional technique usingan anterior field.Acute toxicities were evaluated according toRTOG/EORTC criteria. RESULTS:There was significant statistical difference between CT and MRI in detecting the invasion of NPC in retropharyngeal lymph nodes,base of skull,vagina carotica fasciae cervicalis.And in musculus longus capitis, retropharyngeal space,orbital apex,cavernous sinus.But compare to the CT,there was no statistical difference of MRI in detecting cervical lymph node metastasis.Compared with CT,MRI made changes in 43 of T stage(including35 up-staging and 8 downstaging),and 33 of clinical stage(28 up-staging and 5 down-staging) for the Chinese'92 staging system,while made changes in 35 of T stage(32 up-staging and 3 down-staging),34 of clinical stage(32 up-staging and 2 down-staging) for the 6th edition UICC/AJCC staging system.With a median followed-up of 2 months(range 2-26),two patients failed in the neck. No patients developed distant metastasis.The 1-year estimated local regional progression-free survival rates,distant metastases-free survival rates and overall survival rateswere 91.3%,100.0%and 100.0%.Most of the patients had grade 1 to 2 acute and Grade 0 to 1 late toxicities,without anyonehaving Grade 4 acute or late toxicities.Xerostomia decreased with time in 48 evaluable patients.CONCLUSIONS:MRI has a typical advantage in detecting the primary tumor extension of NPC,which will provide reliable evidences for radiotherapy target region.For treatment-naive nasopharyngeal cancer,IMRT yields good dose distribution and the surrounding normal tissues can be well protected.The acute toxicities are well tolerated and the early clinical efficacy is satisfying.