3DVH系统在鼻咽癌容积旋转调强剂量验证中的应用研究

Dosimetric verification of Volumetric Modulated Arc Therapy(VMAT) in nasopharyngeal carcinoma using 3DVH patient anatomy based system

目的:研究3DVH系统在鼻咽癌容积旋转调强计划剂量验证中的应用。方法:选取18例鼻咽癌病例在Pinnacle计划系统(9.2版本)中进行容积旋转治疗计划设计,通过网络把治疗计划传输至MOSAIQ网络系统上,同时把治疗计划导入ARCCHECK模体重新进行剂量计算。然后把重新剂量计算得到的剂量和计划文件以DICOM的格式传输到3DVH软件系统中,比较靶区和危及器官的理论计算和实际测量之间的差异。其中比较的参数主要有:靶区的平均量(Dmean)、2%体积剂量(D2%)、98%体积剂量(D98%)以及Y通过率。危及器官如脊髓、脑干、视神经、眼晶体以及视交叉的平均剂量(Dmean)、1%体积剂量(D1%)。腮腺的平均剂量(Dmean)、30Gy的剂量体积(V30Gy)以及50%体积剂量(D50%)。结果:各个靶区的γ通过率均在95%以上,Dmean和D2%差异在1%以内,D98%差异在1.5%以内。危及器官的理论和实际测量的差异大都在1.5%以内。结论:3DVH系统是一种方便快捷的鼻咽癌容积旋转调强剂量工具,它可以更加直观的显示计划系统理论计算结果和实际测量结果之间的差异。

Objective： To investigate the dosimetric performance of 3DVH system,a novel 3D quality assurance system for the verification of nasopharyngeal carcinoma volumetric modulated therapy treatment plan. Methods： 18 nasopharyngeal carcinoma patient volumetric modulated arc therapy treatment plans were performed with Pinnacle treatment planning system（ 9. 2 version）,and the treatment plans were sent to ArcCHECK phantom and MOSAIQ RV system respectively,the recalculated plans in ArcCHECK phantom were transferred to 3DVH software in DICOM format,ArcCHECK reconstructed dose versus TPS dose were evaluated using the dose volume-based indices： dose received by target mean dose（ Dmean）,98% volume of target（ D98%） 、2% volume of target（ D2%） and γ pass rate. dose to the 1% of the spinal cord and brain stem volume（ D1%） 、mean dose of leaf and right parotid（ Dmean） 、the volume received 30 Gy for left and right parotid（ V30Gy）,and 50% volume dose of parotid.（ D50%）. Results：The average dose difference for the target volumes and D2% were within 1%,the difference for D98% were within 1. 5% for most treatment plans,and the γpass rate is more than 95% for all target volumes. The average difference for organ at risk were within 1. 5%. Conclusion： The 3DVH system is an ideal tool for the VMAT verification. It can check the dose difference between the real delivery and TPS calculation directly for each individual organ,either target volumes or critical organs.