摆位误差对VMAT计划剂量学验证的影响  

Effect of the setup error on the dosimetric verification for the volumetric modulated arc therapy

作　　者：孙晓欢[1] 谭丽娜[1] 马奎[1] 肖锋[1] 

机构地区：[1]第四军医大学西京医院放疗科,西安710032

出　　处：《中华放射肿瘤学杂志》2014年第6期513-515,共3页Chinese Journal of Radiation Oncology

摘　　要：目的 探讨鼻咽癌患者及宫颈癌患者VMAT中摆位误差对剂量学验证的影响.方法 分别为10例鼻咽癌、宫颈癌患者设计VMAT计划,并将计划移植到Delta4模体中进行计算,在瓦里安iX加速器上实施照射,通过移动治疗床模拟左、右、头、脚、腹、背方向上3、5、7 mm摆位误差,从而验证摆位误差对剂量验证通过率的影响.结果 γ分析结果显示鼻咽癌患者摆位误差＞3mm时,3％/3 mm标准下的通过率均＜90％,摆位误差达到5 mm时,头方向低至（64.7±8.2）％;宫颈癌患者摆位误差＞5mm时3％/3 mm标准下的通过率均＜90％,摆位误差达到7 mm时,头方向低至（63.3±3.6）％.结论 摆位误差对鼻咽癌患者和宫颈癌患者的VMAT计划的剂量学验证有较大影响,误差越大通过率越低,尤其是头方向误差对剂量分布影响更为显著.Objective To evaluate the effect of the setup error on the dosimetric verification for the nasopharyngeal carcinoma patients and cervical carcinoma patients treated with volumetric modulated are therapy （VMAT）.Methods VMAT plans for 10 cervical cancer patients and 10 nasopharyngeal carcinoma patients were transplanted into the Delta4 phantom and calculate the dose,next,implement the treatment on the Varian iX linear accelerator.on the Varian iX linear accelerator.To simulate the setup error by moving the treatment couch in,out,up,down,left,right by 3 mm,5 mm,7 mm.Thereby study the effect of the setup error on the pass rate of the dose verification.Results The results for the dose distribution using the gamma evaluation method showed that the pass rate （3％/3 mm） was less than 90％ when the setup error were greater than 3 mm and 5 mm for the nasopharyngeal carcinoma patients and the cervical carcinoma patients.The pass rate of head direction were （64.7 ± 8.2） ％ and （63.3 ± 3.6） ％ on setup error of 5 mm and 7 mm for nasopharyngeal carcinoma patients and cervical carcinoma patients,respectively.Conclusions Setup error has great effect on the dose verification of the VMAT plans,the greater of the setup error,the lower of the pass rate.The setup error of head direction is more sensitive than other directions especially.

关 键 词：容积调强弧形疗法 摆位误差 剂量学验证 

分 类 号：R739.63[医药卫生—肿瘤] R730.55[医药卫生—临床医学]