射野准直器跟随功能在胸上段食管癌容积旋转调强计划中的应用

目的：探讨射野准直器跟随功能在胸上段食管癌容积旋转调强计划中的剂量学影响。方法选取11例胸上段食管癌放疗患者，在瓦里安Eclipse治疗计划系统上分别设计两种计划：RapidArc和JT‐RapidArc。比较靶区和危及器官的剂量体积参数、适形度指数（CI）、剂量均匀性指数（HI）、正常组织低剂量体积（B‐P）及机器跳数（MU）。结果与RapidArc计划比较， JT‐RapidArc计划降低了PTV1（64）、PTV2（54）的平均剂量和高剂量（D2）受照体积，提高了PTV1（64）的低剂量区域（D98）和 HI （P＜0．05），但PTV1（64）的CI二者差异无统计学意义（P＞0．05）。JT‐RapidArc计划肺的（V5、V10、V13、V20、V30、Dmean ）、心脏的（V20、Dmean ）、B‐P的（V5、V10、V15、V20、V30）明显低于RapidArc计划（P＜0．05），脊髓计划区和脊髓的差异二者间差异无统计学意义（P＞0．05）。JT‐RapidArc计划的MU（349±29）比RapidArc计划的MU（345±16）略微增加1％（P＞0．05）。结论两种计划均能满足临床治疗需求，JT‐RapidArc计划在提供了更优的部分靶区剂量分布情况下，能更好地有效保护肺、心脏和正常组织低剂量区域，MU仅略微增加。

Application of Jaw-tracking function in VMAT for upper thoracic esophageal cancer

Objective To explore the effect of the Jaw‐tracking with RapidArc(JT‐RapidArc) plans for upper thoracic e‐sophageal cancer .Methods Treatment planning was designed by using RapidArc and JT‐RapidArc techniques for 11 consecutive patients .The dose‐volume histogram parameters of PTV and the organs at risk ,conformity index(CI) ,heterogeneity index(HI) , low dose volume of normal tissue (B‐P ) and monitor units (MU ) were compared between the different techniques . Results Compared with the RapidArc plan ,JT‐RapidArc had increased coverage of PTV1(64) D98 and HI(P<0 .05) ,lower Dmean , D2 of PTV1(64) and PTV2(54) ,but no statistically difference in CI(P>0 .05) .Plans with JT‐RapidArc had lower Lung(V5 ,V10 , V13 ,V20 ,V30 ,Dmean ,P<0 .05) ,heart(V20 ,Dmean ,P<0 .05) ,and B‐P(V5 ,V10 ,V15 ,V20 ,V30 ,P<0 .05) ,but no significantly different in spinal cord and SC‐PRV as compared with RapidArc plans(P>0 .05) .JT‐RapidArc plans increaseed the MU by 1% (349 ± 29 vs .345 ± 16 ,P>0 .05) as compared with RapidArc plans .Conclusion All of the plans had met the requirements of clinical dosime‐try .JT‐RapidArc plans as compared with RapidArc plans ,showing better part of target coverage ,part of lung and heart and B‐P sparing ,which MU was slightly increased .