RapidArc和IMRT在脑胶质瘤术后放疗中保护海马的剂量学比较

目的:研究RapidArc和IMRT技术在脑胶质瘤术后放疗中保护海马的剂量学比较。 方法:选取22例脑胶质瘤术后行放疗患者，在其CT和MRI图像融合基础上勾画靶区和危及器官，分别设计IMRT和RapidArc计划，比较两种计划在计划靶区及危及器官的剂量学参数。 结果:两种计划均能满足处方剂量要求。与IMRT技术相比，RapidArc技术靶区适形度指数更接近于1（P<0.05）、靶区剂量均匀性指数无显著差异；在脑干和海马保护上，RapidArc技术比IMRT技术有明显优势，特别是海马的Dmax和Dmean值均显示在RapidArc技术中低于IMRT技术（P<0.05）。 结论:RapidArc计划可以达到或优于IMRT技术的靶区剂量分布，能更好地降低海马的受照射量，且相对MU和治疗时间均有很大的优势，是脑胶质瘤术后海马保护放射治疗计划较好的选择。

Dosimetric comparison of RapidArc and IMRT in hippocampus sparing during postoperative radiotherapy for glioma

Abstract: Objective To compare the dosimetric differences between volumetric modulated arc therapy with RapidArc (RapidArc) and intensity-modulated radiotherapy (IMRT) in hippocampus sparing during postoperative radiotherapy in patients with glioma. Methods Twenty-two postoperative patients with glioma were selected. Based on the fusion of CT images and MRI images, the target areas and organs-at-risk were delineated. Both IMRT and RapidArc plans were designed for each patient. The dosimetric parameters of target areas and organs-at-risk were compared between two plans. Results Both IMRT and RapidArc plans met the requirements of prescribed dose. Compared with that of IMRT, the conformity index of RapidArc was closer to 1 (P<0.05), but there was no significant difference in homogeneity index. In the protection of brainstem and hippocampus, RapidArc was superior to IMRT, especially in the Dmax and Dmean of hippocampus which were lower in RapidArc (P<0.05). Conclusion Compared with IMRT, RapidArc shows a similar or better target dose distribution and reduces the irradiation doses to organs-at-risk, with the advantages of less monitor units and shorter treatment time. RapidArc with hippocampus sparing can be considered as the preferred treatment option in postoperative radiotherapy for glioma.