摘要目的 对容积调强弧形技术(VMAT)优化模型进行改良,在仿真环境下结合全自动逆向优化技术,制定综合IMRT与VMAT优点的放疗计划优化新策略,并对优化结果进行剂量学评估验证.方法 在仿真环境下,模拟临床相对复杂的鼻咽癌病例,分别制作9野IMRT计划和单弧VMAT计划.使用全自动逆向优化技术,自主研发基于VMAT模型的优化程序AOP.根据不同阈值将初始VMAT优化模型产生的子野进行均匀合并,阈值范围为[10,20,30,40,50].AOP软件根据约束条件给出不同阈值下优化难易值w,并选取最优方案生成AOP计划.将AOP计划与常规IMRT/VMAT计划做剂量学比较,评估优化结果,验证计划质量.结果 与常规IMRT及VMAT优化方案相比,AOP软件给出的最优方案(m=2时)靶区适形度较好,同时更好地保护视交叉、晶状体、视神经等正常组织,且在腮腺及口咽的平均剂量上较IMRT和VMAT计划要低.结论 基于VMAT模型的全自动逆向优化技术产生的方案与临床现有技术具有可比性,甚至在保护某些正常组织上更有优势,同时耗费子野总数更少.

abstractsObjective To investigate a new automatic inverse optimal solution based on VMAT optimization model and verify its result.Methods A variant of the new automatic inverse optimal solution was proposed in this study,which provided a solution to calculate treatment plan with the minimized number of beams and the minimized levels of their intensities on the basis of VMAT optimization model by customized software tools.The verifications were evaluated on the simulated head-neck phantom by dosimetric parameters.Results Compared with conventional IMRT/VMAT treatment plans,the adaptive optimization program(AOP)plan showed that plan20/40(20 fields with totally 40 sub-fields,m=2)made the best achievement and it was clinicable.Conclusions The proposed new optimization technique provides an effective way to reach an inverse treatment plan with the best compromise and less sub-fields compared with IMRT/VMAT plans.