CBCT在纠正摆位误差导致鼻咽癌PTV剂量不足的应用研究  

Research on Application of CBCT to set-up Error Correcting and Bettering PTV Dose Distribution in Nasopharyngeal Carcinoma Treatment

作　　者：詹蔚[1] 徐晓婷[1] 郭建[1] 陈龙[1] 周菊英[1] 

机构地区：[1]苏州大学附属第一医院,江苏苏州215006

出　　处：《药物生物技术》2012年第6期527-529,共3页Pharmaceutical Biotechnology

基　　金：江苏省预防科学研究课题(No.YZ201024)

摘　　要：前鼻咽癌治疗普遍应用调强放疗,与传统三维适形放疗相比,调强放疗对摆位精确度要求更高,剂量更加准确。由于摆位误差需要对靶区进行外扩,本研究旨在探索与确定合适的外扩边界,在保护正常组织的前提下保证靶区剂量的均匀性。应用IGRT图像引导获取12例患者的摆位误差,在治疗计划系统中相应移动等中心,在不改变射野分布和权重的情况下,重新计算剂量分布。分析移动等中心后计划与原计划中各靶区与正常组织的剂量变化,确定适当的靶区外扩边界,以保证靶区剂量的均匀以及正常组织受量。当摆位误差为5 mm时,8.3%的GTV D99及16.7%的CTVD95剂量减少大于6%,当摆位误差为2 mm时,GTV D99、CTV D95剂量减少均小于3%。误差越大对剂量分布的影响越明显。靶区CTV较GTV对于摆位误差更为敏感,按照Stroom等推荐的公式2.0Σ+0.7σ计算GTV外扩边界PGTV:x=4.33 mm;y=2.80 mm;z=4.18 mm,据此生成的计划可有效避免由摆位误差导致的靶区剂量不足。Aim： Nowadays IMRT is widely used as a treatment for nasopharyngeal carcinoma, which requires more in accuracy of set-up and dose. This study is intended to find the proper external of the Target and to ensure dose homogeneity on the basis of protecting healthy tissues. Method： Offerring 12 set-up error cases through the image guide of IGRT,changing the location of ISO in TPS, and redesigning dose distribution without changing field distribution and weight. Analyzing the difference of dose change in Target and normal tissues between the original plan and the plan after moving ISO ratio of dose evaluation and original plan to make sure of the enlarge of the target and ensure well-distributed dose and the dose obtained by the normal tissues. When the set-up error is 5 mm,8.3% GTV D99 and 16. 7% CTVD95＇s dose decrease is more than 6% ,When the set-up error is 2 mm,the dose decrease in GTVD99 and CTVD95 is less than 3% . The huger the error is, the more effective on dose distribution. Target CTV is more sensitive to set-up error,which means set-up error has more effects on target CTV than target GTV. Figuring out the enlarge of the GTV based on the formula 2. 0∑＋0.7σ by Stroom. PGTV ：x =4. 33 mm;y =2. 80 mm;z =4. 18 mm. The plan produced based on this is an effective way to avoid the lack in dose caused by position error.

关 键 词：CBCT 调强放疗 摆位误差 

分 类 号：R730.55[医药卫生—肿瘤]