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目的:比较鼻咽癌不同调强放射治疗(IMRT)计划的剂量学差异。方法:对16例鼻咽癌患者分别设计5、7、9野均分的IMRT计划,3种计划方式采用同步推量技术,比较3种计划中靶区与危及器官的剂量学差异。结果:靶区剂量覆盖率V95%,5野计划明显劣于7野和9野(P<0.05),7野与9野靶区的最大剂量Dmax、平均剂量Dmean、最小剂量Dmin接近(P>0.05),而在5计划中明显偏小,且与7野与9野之间的差异有统计学意义,P<0.05。另外对靶区适合度指数和均匀性指数而言7野与9野区别不大(P>0.05),均优于5野,P<0.05。各危及器官指标间比较5野的值最小(P<0.05),7野与9野相近(P>0.05),所有指标均低于耐受剂量的限值。BODY:5野与7野、9野比较,V10～V20差异均有统计学意义(P<0.05),而V25和V30相当,P>0.05;7野与9野比较V10～V30差异无统计学意义,P>0.05。结论:无论从临床剂量学要求还是设野原则来看,7野IMRT计划可以作为鼻咽癌IMRT的首选。
Objective: To compare the dosimetry differences of different intensity modulated radiotherapy (IMRT) plans for nasopharyngeal carcinoma. Methods: IMRT plans of 5, 7, 9 field were designed respectively for 16 cases of nasopharyngeal carcinoma patients. Three kinds of planning methods were used to compare the dosimetry of the target area and the organs at risk. Results: The coverage of target dose of V95% and 5-field was significantly lower than that of 7-and 9-field (P <0.05). The maximal dose Dmax, mean dose Dmean and minimum dose Dmin of 7-field and 9- 0.05), but it was obviously smaller in the 5-plan, and there was a significant difference with 7-field and 9-field (P <0.05). In addition, for the target fitness index and uniformity index, the difference between 7-field and 9-field was not significant (P> 0.05), which were all better than 5-field, P <0.05. The values of the five endangered organs were the lowest (P <0.05), and those of the seven fields were similar to those of the nine fields (P> 0.05). All the indexes were below the limit of tolerated dose. There were significant differences in V10 ~ V20 between 5 wild and 7 wild and 9 wild (P <0.05), while V25 and V30 were the same, P> 0.05; there was no significant difference in V10 ~ V30 between 7 and 9 wild Significance, P> 0.05. CONCLUSION: The 7-field IMRT plan can be the first choice for IMRT of nasopharyngeal carcinoma both in terms of clinical dosimetry requirements and orbital principle.