基于RTOG 0813/0915剂量学指标比较不同技术对非小细胞肺癌立体定向放疗计划的影响

Effects of different techniques in stereotactic radiotherapy for non-small cell lung cancer based on RTOG 0813/0915 dosimetry index

目的系统评价适形治疗(CRT)、动态适形弧治疗(DCAT)、调强放疗(IMRT)和容积旋转调强治疗(VMAT)等不同非小细胞肺癌体部立体定向放疗(NSCLC-SBRT)技术在美国放射治疗肿瘤协作组(RTOG)0813/0915剂量学指标和其他全肺受量指标以及治疗效率等方面的差异,选择合适的NSCLC-SBRT技术。方法回顾分析2019年4月—2021年3月接受SBRT的17例非小细胞肺癌患者的临床资料,分别设计7野CRT、7野IMRT、双弧DCAT和双弧VMAT,比较其靶区RTOG 0813/0915剂量学指标中100%等剂量体积与计划靶体积之比(R_(100%))、50%等剂量体积与计划靶体积之比(R_(50%))、距计划靶区2 cm处的最大剂量(D_(2cm))和20 Gy剂量照射的体积占肺体积的百分比(V_(20)),以及其他全肺受量指标和治疗效率的差异。结果4种技术中,在靶区R_(100%)、R_(50%)和D_(2cm)方面,VMAT组最优(P<0.05),IMRT组次之(P<0.05),CRT和DCAT组较差,且2组间差异无统计学意义。VMAT与IMRT组全肺5 Gy剂量照射的体积占肺体积的百分比(V_(5))、V_(20)及平均剂量(D_(mean))均相近(P=0.082,P=0.082,P=0.652),其中VMAT组全肺V_(20)较CRT与DCAT组分别减少13.3%和9.3%(P<0.05)。与IMRT组相比,VMAT组全肺10 Gy剂量照射的体积占肺体积的百分比(V_(10))、机器跳数(MU)和治疗时间分别减少6.9%、53.1%和18.1%(P<0.05),DCAT组MU和治疗时间分别减少65.4%和36.4%(P<0.05)。与VMAT组相比,DCAT组MU和治疗时间分别减少26.1%和22.3%(P<0.05)。结论基于医用加速器的NSCLC-SBRT优先推荐VMAT技术,其既能保证RTOG协议的剂量限值要求,又能减少全肺剂量。

Objective To systematically evaluate the differences of non-small cell lung cancer-stereotactic body radiation therapy(NSCLC-SBRT)techniques such as conformal radiotherapy(CRT),dynamic conformal arc therapy(DCAT),intensity modulated radiotherapy(IMRT)and volumetric modulated arc therapy(VMAT)in The Radiation Therapy Oncology Group(RTOG)0813/0915 dosimetric index,other whole-lung dose index,and treatment efficacy,and to select appropriate NSCLC-SBRT technology.Methods A total of 17 NSCLC patients who underwent SBRT from April 2019 to March 2021 were enrolled and their clinical data were retrospectively analyzed.The plans included 7-beam CRT,7-beam IMRT,double arc DCAT and double arc VMAT.They were compared for conformity index(R_(100%)),ratio of 50%isodose volume to the PTV(R_(50%)),maximum dose 2 cm away from PTV in any direction(D_(2cm)),and percent of normal lung receiving 20 Gy(V_(20))and therapeutic efficacy.Results In terms of target volume R_(100%),R_(50%)and D_(2cm)in the four plans,the VMAT group was the best(P<0.05),followed by the IMRT group(P<0.05),the CRT and DCAT groups were worse and the difference between the two groups was without statistical difference.The VMAT and IMRT groups had similar percent of normal lung receiving 5 Gy(V_(5)),V_(20)and mean dose(D_(mean))(P=0.082,P=0.082,and P=0.652),where the total lung V_(20)of the VMAT group was 13.3%and 9.3%lower than that of the CRT and DCAT groups,respectively(P<0.05).Compared with the IMRT group,the total lung percent of normal lung receiving 10 Gy(V_(10)),monitor units(MUs)and treatment time of the VMAT group decreased by 6.9%,53.1%and 18.1%,respectively(P<0.05),and the V_(10),MUs and treatment time of the DCAT group decreased by 65.4%and 36.4%,respectively(P<0.05).Compared with the VMAT group,the number of MUs and treatment time in the DCAT group decreased by 26.1%and 22.3%,respectively(P<0.05).Conclusions For NSCLC-SBRT based on medical accelerators,VMAT is preferred,which can not only ensure the dose limit requirements of the RTOG protocol but also reduce the total lung dose.