非共面容积旋转调强技术在左侧乳腺癌保乳术后全乳加锁骨区放疗中的剂量学研究

目的:分析非共面容积旋转调强(nVMAT)技术与容积旋转调强(VMAT)技术在左侧乳腺癌保乳术后全乳加锁骨区放疗中的剂量学差异。方法:选取10例临床上接受VMAT的左侧乳腺癌保乳术后患者,采用n VMAT技术重新计划,比较靶区剂量学参数,危及器官心脏、全肺、对侧乳腺的Dmean,脊髓、冠状动脉Dmax,心脏V20、V30,左肺V5、V20以及气管V30、V40。结果:n VMAT计划在临床靶区(P-CTV)均匀性、心脏Dmean、全肺Dmean、对侧乳腺Dmean、冠状动脉Dmax方面优于VMAT计划,差异具有统计学意义(P<0.05);靶区(P-CTV、P-GTV)适形度及心脏V30,左肺V20,气管V30、V40方面略优,但无统计学差异(P>0.05);机器跳数明显增加(P<0.05);脊髓Dmax略有增加,但差异不显著(P>0.05)。结论:n VMAT技术可使靶区剂量更均匀,并改善危及器官的剂量,其中心脏Dmean及冠状动脉Dmax显著降低。

Dosimetric study on non-coplanar volumetric modulated arc therapy technique in breast and clavicular radiotherapy following breast-conserving surgery for left-sided breast cancer

Abstract: Objective To investigate the dosimetric differences between non-coplanar volumetric modulated arc therapy (nVMAT) and VMAT in breast and clavicular radiotherapy following breast-conserving surgery for left-sided breast cancer. Methods The clinical VMAT plans of 10 patients undergoing breast-conserving surgery for left-sided breast cancer were re-planned using non-coplanar VMAT technique. The dosimetric parameters of target areas and organs-at-risk were compared. The comparison indicators of organs-at-risk included the Dmean of heart, lungs and contralateral breast, the Dmax of spinal cord and coronary artery, the V20, V30 of heart, the V5, V20 of the left lung and the V30, V40 of trachea. Results nVMAT plan was superior to VMAT plan in the homogeneity index of P-CTV, the Dmean of heart, lungs and contralateral breast, and the Dmax of coronary artery, with statistical differences (P<0.05). Compared with those in VMAT plan, the conformity indexes of P-CTV and P-GTV, and the V30 of heart, the V30 of left lung, the V30, V40 of trachea in nVMAT plan were slightly better, but there was no statistical difference (P>0.05). Moreover, the number of motion units in nVMAT plan was significantly increased (P<0.05). Although the Dmax of the spinal cord was increased in nVMAT plan, the difference between two plans was trivial (P>0.05). Conclusion nVMAT technique can increase the homogeneity index of target volumes and improve organs-at-risk sparing, especially reducing the Dmean of heart and the Dmax of coronary artery.