Octavius4D验证系统用于VMAT剂量验证的研究

摘要

Objective To study the feasibility of dose verification with Octavius 4D system in volumetric modulated arc therapy (VMAT).Methods Twenty patients were treated with the VMAT.Their treatment plans were performes and then acquired the measured data with the Octavius 4D system.In addition,the treatment plans are used in the CT phantom for Octavius 4D system,and acquire the simulated data.We use the γ pass rate to analysis the measured and simulated results for the conditions:the dose deviations are 2％3％5％,the displacement deviations are 2 mm/3 mm/5 mm and the thresholds are 5％ 10％,and got the Gamma pass rate and fitness of profile curve.Results The distributions of measured and simulated dose are matched well,and the fitness of profile curve are also matched well.The averaged Gamma pass rate is 97.78％ in the case 3 mm 3％ 10％.Conclusions Octavius 4D system can meet the dose verification for VMAT treatment.The measured plane is always following the rotating frame and perpendicular to the beam.%目的 研究Octavius4D验证系统在VMAT剂量验证中的可行性.方法 在满足临床剂量要求的VMAT计划中选取20例患者计划,传输至MOSAIQ网络系统上执行验证治疗,使用Octavius 4D验证系统采集实时数据.同时把治疗计划移植至Octavius 4D验证系统的CT模体中进行剂量计算.在剂量偏差2％、3％、5％,位移偏差2 mm、3 mm、5 mm,阈值偏差5％、10％条件下,采用γ通过率法分析模体中计划计算结果与Octavius 4D验证系统实际测量的剂量结果,得出相应验证通过率及Profile等曲线吻合度.结果 实测的剂量信息与计划计算的剂量信息在对应几何平面分布较为一致,Profile等曲线吻合度都较好,在3％剂量偏差、3 mm位移偏差和10％阈值偏差条件下的γ平均通过率为97.78％.结论 Octavius4D验证系统能满足临床VMAT计划剂量验证要求,且测量平面始终随机架旋转与射线束相垂直,无角度依赖性,可行性值得认可.