基于逐次优化算法的自动双弧VMAT技术在颈胸段食管癌放疗中的应用

The Progressive Optimization Algorithm Based Automatic Double Arc Volumetric Modulated Arc Therapy Technology Used in Radiotherapy for Cervicothoracic Esophageal Cancer

目的首次利用基于逐次优化算法的自动双弧VMAT技术(Auto-VMAT)来加速和优化颈胸段食管癌的放疗计划,并综合比较Auto-VMAT、人工VMAT和IMRT在治疗CTEC的剂量学差异及正常组织并发症概率(NTCP)。方法采用基于逐次优化算法的Pinnacle39.10计划系统的自动双弧VMAT技术设计放疗计划,具体包括选取自动治疗技术、运行自动计划脚本和评估最终放疗方案;另外所有病例均人工设计7野IMRT(7f-IMRT)、单弧VMAT(Single-VMAT)和双弧VMAT(Double-VMAT)计划。最后用标准剂量体积直方图、靶区适形度指数(CI)、靶区均匀性指数(HI)和机器跳数(MUs)对四种计划方案进行定量评估。结果7f-IMRT计划的靶区剂量适形度低于所有计划,Double-VMAT计划略低于Auto-VMAT,但优于Single-VMAT。Auto-VMAT和7f-IMRT计划的HI值分别为最高和最低。对于NTCP结果,四种放疗计划有显著的统计学差异,与7f-IMRT计划相比,Auto-VMAT计划减少了约1%的肺部肺炎的并发症概率。所有VMAT计划平均MUs减少了42.1%,其中Single-VMAT传输60 Gy剂量所需的平均MUs最小,Auto-VMAT次之,VMAT计划的平均治疗时间从193.8 s减少到99.2 s,减少约48.8%。结论Auto-VMAT具有最大的靶区覆盖率和最优的危及器官保护,计划设计和治疗时间明显缩短,也避免了计划设计者在设计放疗计划时的人为失误与不同设计者计划设计的差异,是未来治疗CTEC的较好选择。

Objective The progressive optimization algorithm based automatic double arc volumetric modulated arc therapy(Auto-VMAT)technology was first used to accelerate and improve the radiotherapy plan of cervicothoracic esophageal cancer(CTEC),and the dosimetric difference and probability of normal tissue complications(NTCP)of Auto-VMAT,artificial VMAT and IMRT plans in the treatment of CTEC were compared comprehensively.Methods The radiotherapy plan was designed using the automatic dual-arc VMAT technology of Pinnacle39.10 planning system based on progressive optimization algorithm.Specially,it includes the selection of treatment techniques,the running of automated planning scripts,and the evaluation of the final radiotherapy regimen,and the manual 7field-IMRT(7f-IMRT),Single-arc-VMAT and Double-arc-VMAT(Single-Arc/Double-Arc)plans were generated in all cases.Finally,the standard dose volume histogram,target's conformal index(CI),target's homogeneity index(HI)and monitor units(MUs)were used to quantitatively evaluate the four plans.Results The CI of the 7f-IMRT plan was inferior to all plans,whereas the Double-Arc plan was slightly inferior to the Auto-VMAT but superior to the Single-Arc and 7f-IMRT plan.The HI was highest for the Auto-VMAT plan and lowest for the Single-Arc plan.For the NTCP results,there was significant statistical difference among the four plans;the Auto-VMAT reduced the complication rate of pulmonary pneumonia byapproximately 1%compared with the 7f-IMRT plan.The average MUs of all VMAT plans decreased by 42.1%,among which the average MUs required to transmit 60Gy of Single-VMAT was the smallest,followed by Auto-VMAT,and the average treatment time of VMAT plans decreased from 193.8 seconds to 99.2 seconds,a decrease of about 48.8%.Conclusion By comprehensive consideration,Auto-VMAT showed better target coverage and sparing of organ at risks,and achieve a significant reduction in planning and treatment time,it also avoids the human error of the plan designer in designing the radiotherapy plan and the difference between the plan design of different designers,which is a good option for treating CTEC in the future.