调强放疗对保护鼻咽癌患者吞咽结构的剂量学研究

Dosimetric Study of Protection of Swallowing Structures in Nasopharyngeal Carcinoma Treated with Intensity-Modulated Radiotherapy

[目的]探讨调强放疗（intensity-modulated radiotherapy,IMRT）技术对鼻咽癌患者吞咽功能保护的剂量学优势。[方法]收集T1-4N2-3M0鼻咽癌患者90例,分成常规调强组（rIMRT）、保护吞咽结构的调强组（pIMRT）和二维常规放疗组（2D-RT）,每组30例。其中pIMRT在rIMRT的基础上增加对吞咽结构咽缩肌（PC）、声带和声门上喉（包括会厌）（GSL）、食管上端（Esoph）的勾画和剂量限定。比较吞咽结构在三组放疗计划中的剂量学差异及相应的功能损伤。[结果]pIMRT计划中吞咽结构PC的平均剂量Dmean、V40、V50、V60分别为4743.77±261.50cGy、10.05%±3.59%、4.05%±2.49%、1.60%±1.45%,明显好于rIMRT和2D-RT（P〈0.05）,同样GSL的平均剂量Dmean、V40、V50、V60分别3643.58±1822.48cGy、6.37%±5.35%、0.45%±0.77%、0.02%±0.07%,也优于rIMRT和2D-RT（P〈0.05）,但是对于食管上端的受照剂量,2DRT计划的各项参数占优势（P〈0.05）;对于功能损伤,pIMRT组中重度损伤较少,其次是rIMRT,2D-RT组多数出现中重度损伤。[结论 ]pIMRT对吞咽结构的保护有一定的剂量学优势,为进一步研究吞咽结构的受照剂量与吞咽困难发病率的相关性提供有力的研究基础。

[Purpose] To investigate the dosimetric advantages of protecting swallowing structures of nasopharyngeal carcinoma（NPC） in intensity-modulated radiotherapy（IMRT）. [Methods] A total of 90 diagnosed as T1-4N2-3M0 NPC patients were randomized devided into 3 groups,including regularIMRT（rIMRT）,swallow-protect IMRT（pIMRT） and 2D radiotherapy（2D-RT）,each had 30 cases patients treated with pIMRT were paid extra attention to swallowing structures,such as pharyngeal constrictors（PC）,glottic and supraglottic larynx（GSL） and esophagus（Esoph）,which were defined additionally and the dose were alsoto be considered during optimization. Differences of dose distribution and corresponding swallowing injury were compared. [Results] In comparison to2D-RT and rIMRT,pIMRT provided improvements in PC dosimetric parameters（P〈0.05）,whose Dmean、V40、V50、V60 in pIMRT were 4743.77 ±261.50 cGy,10.05% ±3.59%,4.05% ±2.49%,1.60% ±1.45%,respectively. Similarly,the Dmean、V40、V50、V60 of GSL in pIMRT were 3643.58±1822.48 cGy,6.37%±5.35%,0.45%±0.77%,0.02%±0.07%,respectively,which were better than 2D-RT and rIMRT（P〈0.05）. But in terms of Esoph sparing,no advantage was observed in IMRT（P〈0.05）. For the swallowing injury,there was least moderate and severe damage in pIMRT,the less was rIMRT,mostly 2D-IMRT group appeared moderate and severe damage. [Conclusion] pIMRT could achieve better swallowing structures protection,which will provide a strong research basis for the correlation between the dose of swallowing structures and the incidence of dysphagia.