基于Auto-planning技术的早期鼻咽癌容积旋转调强放射治疗计划评估

Evaluation of Auto-planning technique-based volumetric modulated arc therapy plan for early nasopharyngeal carcinoma

目的:比较基于Auto-planning技术的早期鼻咽癌容积旋转调强放射治疗(VMAT)计划和常规VMAT计划之间的剂量学差异以及计划质量。方法:回顾性分析20例早期鼻咽癌患者的临床资料,采用Pinnacle3计划系统的Auto-planning自动计划模块行VMAT自动计划设计,相应的常规VMAT计划由经验丰富的物理师完成设计,分别为aVMAT和mVMAT。对两组计划的肿瘤靶区剂量分布、危及器官剂量学、机器跳数和计划设计时间进行比较和评估。结果:两组计划靶区的剂量覆盖和适形度均满足处方要求。aVMAT组的PGTV、PTV2的剂量均匀性指数明显优于mVMAT组,但两者的适形度指数无显著差异性。此外,aVMAT计划比mVMAT计划可以更好地保护脊髓,而且在降低脑干的受照剂量亦具有优势。与mVMAT组相比,aVMAT组的平均机器跳数MU减少6.83%,平均计划设计时间减少14.50%。结论:对于早期鼻咽癌,基于Auto-planning技术所产生的自动VMAT计划,比常规VMAT计划具有更佳的靶区剂量分布,且更好地降低正常组织的剂量,同时具有更高的优化效率和计划执行效率。

Objective To compare the dosimetric differences and planning qualities between conventional volumetric modulated arc therapy(m VMAT) plan and Auto-planning technique-based VMAT plan(a VMAT) for early nasopharyngeal carcinoma(NPC).Methods The clinical data of 20 patients with early NPC were analyzed retrospectively. Two kinds of VMAT plans, namely m VMAT plan and aVMAT plan, were designed for each patient. mVMAT plans were manually generated by experienced physicists, and a VMAT plans were automatically generated by Auto-Planning module in Pinnacle3 system. The dose distributions, organs-at-risk sparing, monitor units and planning time were evaluated and compared. Results The dose coverage and conformity index of the target areas in two groups met the prescription requirements. The homogeneity indexes of PGTV and PTV2 in a VMAT group were significantly better than those in m VMAT group, but there was no significant difference in conformity index between two groups.a VMAT plan was advantages over m VMAT plan in protecting spine cord and reducing the dose to the brain stem. Compared with those in mVMAT group, the average monitor units in aVMAT group was reduced by 6.83%, and the average planning time was reduced by 14.50%. Conclusion Compared with mVMAT plan, aVMAT plan for early NPC has better target dose distribution and reduces the dose to normal tissues. Additionally, a VMAT plan has higher optimization efficiency and plan execution efficiency.