多发脑转移瘤铅门跟随VMAT-SRS计划与固定技术剂量学对比分析  

Dosimetric influence of jaw tracking and static jaw in volumetric modulated arc therapy plans for multiple brain metastases stereotactic radiosurgery

作　　者：刘乐乐[1] 胡金炎[1] 王芳娜[1] 孔凡洋 马阳光[1] 郭跃信[1] LIU Le-le;HU Jin-yan;WANG Fang-na;KONG Fan-yang;MA Yang-guang;GUO Yue-xin(Department of Radiation Oncology,First Affiliated Hospital of Zhengzhou University,Zhengzhou 450052,P.R.China)

机构地区：[1]郑州大学第一附属医院放射治疗部

出　　处：《中华肿瘤防治杂志》2019年第20期1542-1546,共5页Chinese Journal of Cancer Prevention and Treatment

基　　金：河南省高等学校重点科研项目计划（19B416005）;河南省科技厅科技攻关计划（182102310369）

摘　　要：目的随着容积旋转调强(volumetric modulated arc therapy,VMAT)技术的出现,基于直线加速器的立体定向放射外科(stereotatic radiosurgery,SRS)技术可以实现更好的计划质量和更高治疗效率。本研究分析铅门跟随(Jaw tracking,JT)技术和铅门固定(static jaw,SJ)技术在多发脑转移瘤VMAT-SRS计划中的剂量学差异。方法选取2015-01-01-2017-06-30郑州大学第一附属医院放疗科收治的15例多发脑转移瘤患者,首先在定位CT图像上设计具JT技术的VMAT计划(VMAT-JT),随后复制计划,取消JT权限,保持所有参数不变,重新优化计划得到SJ的VMAT计划(VMAT-SJ),比较两组计划的靶区、危及器官和正常脑组织的剂量学参数。分别将两组计划用瓦里安Portal dosimetry系统进行剂量验证。结果两组靶区剂量分布均达到临床处方剂量要求。VMAT-JT计划在低剂量区的剂量跌落GIlow好于VMAT-SJ计划,t=-3.339,P=0.009。与VMAT-SJ计划相比,VMAT-JT计划全脑的Dmean、V10%、V20%、V30%分别降低了1.92%(t=-6.111,P<0.001)、3.64%(t=-5.062,P<0.001)、2.22%(t=-3.490,P=0.004)和1.26%(t=-3.868,P=0.002),脑干和左、右眼球的Dmean分别降低了3.10%(t=-2.574,P=0.026)、7.06%(t=-3.068,P=0.008)和7.06%(t=-2.441,P=0.033),此外,VMAT-JT计划左晶体和右视神经的Dmax分别降低了9.52%(t=-2.868,P=0.012)和5.88%(t=-2.637,P=0.020),其余靶区、危及器官和正常脑组织的剂量学参数差异均无统计学意义。两组计划验证的γ通过率均在95%以上,且差异无统计学意义。结论在多发脑转移瘤VMAT-SRS计划中,铅门跟随的VMAT-JT计划与铅门固定的VMAT-SJ计划相比,能实现相当的靶区剂量分布,而且能更好的降低正常组织和危及器官的低剂量照射。OBJECTIVE With the advent of volumetric modulated arc therapy(VMAT),using linac-based stereotactic radiosurgery(SRS)can achieve improved plan quality and high delivery efficiency.The purpose of this study was to study the dosimetric difference between jaw tracking technique and static jaw technique in VMAT plans for multiple brain metastases SRS.METHODS Fifteen patients with multiple brain metastases who received VMAT-SRS in the Department of Radiation Oncology at the First Affiliated Hospital of Zhengzhou University from January 1,2015 to June 30,2017 were enrolled in the study.A VMAT plan with jaw tracking technique(VMAT-JT)was designed on computed tomography(CT)images.Thereafter,a similar plan(VMAT-SJ)except without jaw tracking was generated with re-optimization.The dose distribution in the target,organs at risk and normal brain tissues in two groups were compared to explore the dosimetric differences.RESULTS The plans of two groups can achieve comparable target dose coverage and were clinically acceptable.VMAT-JT had a significantly better dose distribution than VMAT-JT regarding the low dose volume(t=-3.339,P=0.009).In comparison to VMAT-SJ,VMAT-JT reduced the Dmean,V10%,V20% and V30% of normal brain by an average of 1.92%(t=-6.111,P<0.001),3.64%(t=-5.062,P<0.001),2.22%(t=-3.490,P=0.004)and1.26%(t=-3.868,P=0.002),the Dmeanof the brain stem and eyes were reduced by an average of 3.10%(t=-2.574,P=0.026),7.06%(t=-3.068,P=0.008)and 7.06%(t=-2.441,P=0.033),the Dmaxof the left lens and right optic nerve by an average of 9.52%(t=-2.868,P=0.012)and 5.88%(t=-2.637,P=0.020),respectively.No statistical differences were observed on other parameters.With portal dosimetric verification,the passing rates for two groups of plans were over 95%,and the results showed no statistical difference.CONCLUSION In VMAT plans for multiple brain metastases SRS,using jaw tracking technique can significantly reduce the low dose irradiation volume for organs at risk with similar target dose performance comparing to static jaw technique.

关 键 词：铅门跟随 多发脑转移瘤 容积调强放疗 立体定向放射外科 

分 类 号：R739.41[医药卫生—肿瘤]