非小细胞肺癌容积旋转调强与适形调强放疗的剂量学比较

目的:比较容积旋转调强放疗（VMAT）和适形调强放疗（IMRT）技术在非小细胞肺癌靶区和危及器官（OAR）的剂量学差异。 方法:选取首程接受放射治疗的20例非小细胞肺癌患者，分别设计5野IMRT（5F-IMRT）、7野IMRT（7F-IMRT）、双弧VMAT（D-VMAT）和部分弧VMAT（P-VMAT）计划，比较靶区剂量分布、OAR剂量体积参数。 结果:4种计划中计划靶区的Dmean比较差异无统计学意义（P>0.05）；两种VMAT计划中计划靶区的均匀性指数和适形度指数均优于两种IMRT（P<0.05）；4种计划中D-VMAT肺平均剂量高于其余3种计划（P<0.05）；P-VMAT的双肺V5、V10稍好于D-VMAT（P<0.05），但两种VMAT计划均高于两种IMRT计划（P<0.05）；4种计划中P-VMAT的双肺V20最优，且4种计划相互间比较差异有统计学意义（P<0.05）；D-VMAT与P-VMAT双肺的V30相当（P>0.05），但均优于两种IMRT计划（P<0.05）；4种计划双肺V40和心脏的V30、V40比较差异无统计学意义（P>0.05）。P-VMAT计划的脊髓Dmax最低，与其余计划相比差异均有统计学意义（P<0.05）。 结论:非小细胞肺癌靶区剂量分布D-VMAT和P-VMAT好于IMRT计划。P-VMAT在OAR的保护方面体现的优势更多。综合考虑，非小细胞肺癌的放疗优先推荐P-VMAT，但对于重点考虑肺低剂量区，而次要考虑靶区剂量分布的病例推荐7F-IMRT。

Dosimetric comparison of volumetric modulated arc therapy and intensity-modulated radiotherapy for non-small cell lung cancer

Objective To compare the dosimetric differences in target areas and organs-at-risk (OAR) between volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for non-small cell lung cancer (NSCLC). Methods Four different kinds of plans, namely 5-field IMRT (5F-IMRT), 7-field IMRT (7F-IMRT), double-arc VMAT (D-VMAT) and partial-arc VMAT (P-VMAT), were designed for 20 NSCLC patients receiving radiotherapy for the first course. The dose distribution in target areas and OAR dose-volume parameters were compared. Results No significant differences were found in the Dmean of planning target areas among the 4 plans (P>0.05). The homogeneity index and conformal index of two VMAT plans were better than those of two IMRT plans (P<0.05). Compared with the other 3 plans, D-VMAT plans had the highest mean lung dose (P<0.05). The V5 and V10 of lungs in P-VMAT plan were slightly better than those in D-VMAT plan (P<0.05), and both of them were higher than those in two IMRT plans (P<0.05). The V20 of lungs in P-VMAT was the optimal among the 4 plans, and the differences between the 4 plans were statistically significant (P<0.05). D-VMAT and P-VMAT plans had similar V30 of lungs (P>0.05), superior to two IMRT plans (P<0.05). The comparison of the V30 of lungs and the V30, V40 of heart between the 4 plans didn’t showed any statistical differences (P>0.05). The Dmax of spinal cord in P-VMAT was the lowest among the 4 plans, and the differences were statistically significant as compared with other plans (P<0.05). Conclusion The target dose distributions in D-VMAT and P-VMAT plans for NSCLC are better than those in IMRT plans, moreover, P-VMAT shows more advantages in OAR sparing. Therefore, P-VMAT is recommended preferentially in radiotherapy for NSCLC, but 7F-IMRT is recommended for cases in which the low dose areas of lung is the main focus, while the target dose distribution is secondarily considered.