左侧乳腺癌保乳术后深吸气屏气模式下Hybrid-IMRT和Hybrid-VMAT的剂量学比较

目的:在深吸气屏气（DIBH）模式下比较适形混合调强（Hybrid-IMRT）和适形混合旋转容积调强（Hybrid-VMAT）对左侧乳腺癌保乳术后的剂量学差异，为治疗计划选择提供参考。方法:选取26名左侧乳腺癌保乳术后的患者分别设计Hybrid-IMRT和Hybrid-VMAT计划，通过体积剂量直方图比较两种计划的靶区和危及器官的剂量。结果:Hybrid-VMAT计划PTV的D90、D98及HI优于Hybrid-IMRT计划（P<0.05）。Hybrid-IMRT计划GI优于Hybrid-VMAT计划（P<0.05），但对于PTV的D2、Dmean及CI，两种计划没有明显差异（P>0.05）。Hybrid-IMRT计划患侧肺V5、V20、V30及Dmean优于Hybrid-VMAT计划（P<0.05）； Hybrid-IMRT计划心脏的V10、Dmean优于Hybrid-VMAT计划（P<0.05），但V30、V40比较，差异无统计学意义（P>0.05）；Hybrid-IMRT计划对侧乳腺Dmean、V5优于Hybrid-VMAT计划（P<0.05），但Dmax比较，差异无统计学意义（P>0.05）；两种计划的脊髓剂量均满足临床剂量要求，但Hybrid-IMRT计划的脊髓Dmax低于Hybrid-VMAT计划（P<0.05）。结论:两种混合计划均能满足临床剂量要求，但Hybrid-IMRT计划可以明显降低危及器官的受照剂量。

Dosimetric comparison between Hybrid-IMRT and Hybrid-VMAT using deep inspiration breath-hold technique for left-sided breast cancer after breast-conserving surgery

Abstract: Objective To compare the dosimetric differences between hybrid intensity-modulated radiotherapy (Hybrid-IMRT) and hybrid volumetric modulated arc therapy (Hybrid-VMAT) using deep inspiration breath-hold (DIBH) technique for left-sided breast cancer after breast-conserving surgery, thereby providing reference for treatment plan selection. Methods Two kinds of treatment plans, namely Hybrid-IMRT plan and Hybrid-VMAT plan, were designed for 26 patients with left-sided breast cancer after breast-conserving surgery. The dose-volume histogram was used to compare the doses to target areas and organs-at-risk between Hybrid-IMRT plan and Hybrid-VMAT plan. Results Compared with Hybrid-IMRT plan, Hybrid-VMAT plan was superior in D90, D98 and homogeneity index of planning target area (P<0.05), but inferior in GI (P<0.05), and there was no significant difference in D2, CI and Dmean between two plans (P>0.05). Hybrid-IMRT plan was advantageous over Hybrid-VMAT plan in terms of the V5, V20, V30 and Dmean of the ipsilateral lung (P<0.05), and the V10, Dmean of the heart (P<0.05). However, there was no significant difference between two plans in the V40 and V30 of the heart (P>0.05). Hybrid-IMRT plan was superior to Hybrid-VMAT plan in the Dmean and V5 of contralateral breast (P<0.05), but the difference in Dmax was trivial (P>0.05). The spinal dose of the two plans met the clinical dose requirements, while the spinal Dmax of Hybrid-IMRT plan was much less than that of Hybrid-VMAT plan (P<0.05). Conclusion Both of the two hybrid plans meet the clinical dose requirements, but Hybrid-IMRT plan can significantly reduce the radiation dose to organs-at-risk.