早期周围型肺腺癌不同弧度容积旋转调强与动态调强的剂量学比较

Dosimetric Comparison Between VMAT with Different Arc and dIMRT for Early-stage Peripheral Lung Adenocarcinoma

目的比较单弧弧形容积旋转调强放射治疗(VMAT)与5野动态调强放射治疗(dIMRT)在具有球形或类球形肿瘤病灶的早期周围型肺腺癌中的剂量学特点,并探索单弧VMAT在该类患者中的适宜弧度。方法收集具有球形或类球形肿瘤病灶的早期周围型肺腺癌患者32例,对所选病例行单弧180°和单弧360°VMAT以及5野dIMRT三种放疗计划设计,比较各参数值。结果三组计划均能满足临床靶区剂量学要求。三组计划PTV的最大剂量(Dmax)、最小剂量(Dmin)、平均剂量(Dmean)、剂量均匀性指数(HI)及靶区适形度指数(CI)差异均无统计学意义(均P>0.05)。在双肺及患侧肺的平均剂量(MLD)、V5、V10、V20上,5野dIMRT组均低于其他两组单弧VMAT,单弧360°VMAT计划稍高于单弧180°VMAT组(均P<0.05)。三组计划之间比较脊髓Dmax差异均无统计学意义(均P>0.05),5野dIMRT组的脊髓Dmean最小,单弧360°VMAT组最大(P<0.05)。三组放疗计划在心脏V30、D1/3上差异均无统计学意义(均P>0.05)。5野dIMRT组食管Dmean低于单弧VMAT组(P<0.05),单弧180°VMAT组与单弧360°VMAT组之间差异无统计学意义(P>0.05)。5野dIMRT组MU最小,单弧360°VMAT组最大(P<0.05)。结论对于具有球形或类球形肿瘤病灶的早期周围型肺腺癌患者,首选5野dIMRT;就单弧VMAT计划而言,首先考虑弧度为180°。

Objective To compare the dosimetric characteristics of single-arc volumetric modulated arc therapy(VMAT)and 5-field dynamic intensity-modulated radiotherapy(dIMRT)for early-stage peripheral lung adenocarcinoma patients with spherical or spheroidal tumor lesions,and explore the appropriate curvature of single-arc VMAT.Methods We collected 32 early-stage peripheral lung adenocarcinoma patients with spherical or spheroidal tumor lesions and designed three treatment plans for selected cases:single-arc 180°and single-arc 360°VMAT and 5-field dIMRT.The volume of each parameter was compared.Results The three types of plans could meet all the dosimetric requirements of the clinical target area.There was no significant statistical difference in maximum dose(Dmax),minimum dose(Dmin),mean dose(Dmean),homogeneity index(HI)and conformity index(CI)of PTV among three groups(P>0.05).The mean lung dose(MLD),V5,V10 and V20 of the bilateral-lungs and affected-lung in the dIMRT plan group were lower than those of the other two single-arc VMAT plans,and those of single-arc 360°VMAT plan were slightly higher than those of the single-arc 180°VMAT plan(P<0.05).Dmean of spinal cord was the lowest in dIMRT group and the highest in single-arc 360°VMAT group(P<0.05).Dmean of esophagus in dIMRT group was less than those in the single-arc VMAT groups(P<0.05).MUs was the lowest in dIMRT group and the highest in single-arc 360°VMAT group(P<0.05).Conclusion For early-stage peripheral lung adenocarcinoma patients with spherical or spheroidal tumor lesions,5-field dIMRT is preferred;for single-arc VMAT,180°single-arc is better.