6MV与15MVX线在肺癌调强放疗中的剂量学比较

Dosimetric Comparison of 6MV and 15MV Photons for IMRT Treatment of Lung Cancer

目的:分析、比较用于治疗非小细胞肺癌(NSCLC)的6 MV和15 MV X线调强放疗(IMRT)计划。方法:随机选择10例NSCLC患者,采用6 MV和15 MV X射线对每例NSCLC进行IMRT的计划设计,并用ADAC Pinnacle3计划系统提供的卷积/迭加(convolution/superposition)算法对两种能量条件下相同布野方案的IMRT计划进行剂量计算,比较靶区及危及器官的剂量分布、DVH等指标。结果:6 MV与15 MV放疗计划的等剂量线和DVH相近,6 MV计划的靶区剂量均匀性优于15 MV计划,而15 MV计划高剂量覆盖靶区的程度略优于6 MV计划,食管、心脏、脊髓等危及器官的受量基本相同。结论:对于NSCLC,剂量计算应采用能够精确修正组织不均匀性影响的卷积/迭加等算法,调强放疗时应首选6 MV X射线。

Objective： To compare 6 MV and 15 MV photons intensity modulated radiotherapy （IMRT） for non-small cell tung cancer. Materials and methods： For a cohort of 10 patients, 6 and 15 MV IMRT planning was performed using identical planning objective and dose constraint. Doses were computed with a commercially available TPS by using convolution/superposition （CS） algorithm. Plans were compared according to dose-volume histogram （DVH） analysis in terms of PTV homogeneity and conformity indices （HI and CI） as well as OARs dose and volume parameters. Results： On average no statistically significant differences between 6 and 15MV plans were observed except HI. Conclusions： For NSCLC, highly accurate dose computation algorithms such as CS should be utilized to account for heterogeneities. 6MV photons may be the prudent choice of IMRT for NSCLC.