鼻咽癌放射治疗IMRT与Arc调强计划的剂量学比较

目的分析鼻咽癌放射治疗IMRT与Rapid Arc调强放疗计划方案,为临床提供参考。方法 10例鼻咽癌CT增强扫描模拟定位后勾画CTV,按统一标准外扩PTV;实施均分9野IMRT计划和单弧、双弧、3弧Arc调强计划;以PTV处方剂量70Gy,分析各治疗计划靶区剂量分布和危及器官受限剂量,进行剂量学对比研究并比较治疗时间的长短。结果 IMRT调强计划适形指数及不均匀指数明显优于单弧,与双弧和3弧没有明显区别;各计划之间危及器官受量均低于参考受限剂量;照射体积(irradiation volume,IV)未见明显区别;机器跳数(monitor unit,MU),Arc调强计划明显低于IMRT调强计划;治疗时间上Arc调强计划更短。结论目前虽IMRT计划更符合鼻咽癌的治疗剂量要求,但Arc计划在缩短治疗时间、降低治疗时的机器跳数上有明显优势。

A dosimetric comparison between IMRT and Arc treatment plan for nasopharyngeal carcinoma

Objective To examine intensity modulated radiation therapy （IMRT） and Rapid Arc treatment plan for nasopharyngeal carcinoma,and to provide a reference fl~r clinical selection of radiotherapy plans. Methods Ten patients with nasophalTngeal carci- noma（NPC ） were enrolled and underwent CT simulation.The clinical target volume（CTV） was contoured on the CT image,and the planning target volume（PTV ） was defined according to the same criteria.Nine-field IMRT（IMRT9）, single arc（Arcl ）,double arc （Arc2） and triple arc （Arc 3） Rapid Arc plans were generated for each patient.All plans were prescribed 70 Gy.The dosimetric pa- rameters of target volume and organ at risk （OAR）,the monitor units （MU） and treatment time were compared between IMRT and arc treatment plan. Results The conformity index （CI） and HI of PTV for IMRT were superior to those for Arcl ,and were similar to those for Arc2 and Arc3,and all the OAR for various plans were lower than the reference limited dose.MU of Arc was significantly lower than that of IMRT plan,and treatment time of Arc was shorter than that of IMRT. Conclusions Although the IMRT plan is recom- mended for dosimetry, the Arc plan shows a distinct advantage for its short treatment time and small MU number.