早期非小细胞肺癌不同放疗技术的剂量学差异分析

Analysis of the dosimetry differences between peripheral early stage non-small cell lung cancer （NSCLC） treated with SBRT technique

目的 比较早期周围型NSCLC不同放疗技术的剂量学差异,探讨合适治疗手段。方法 对2014—2015年间收治的5例病理确诊的T1、T2期周围型NSCLC行4DCT定位,勾画靶区和OAR。靶区包括GTV、ITV和PTV,ITV在最大密度投影图像上勾画,PTV=ITV＋5 mm;OAR主要包括心脏、肺、食管、脊髓等。用Monaco 5.0 TPS进行计划设计,设计3种计划：（1）3DCRT：11个野,在患侧肺布野,射野形状与PTV适形,PTV外放0.2 cm边界;（2） SW-IMRT：9个野,布野方式同3DCRT;（3） VMAT：机架绕患侧肺旋转180°。计划评估标准参照RTOG0618。配对t检验差异。结果 3种计划PTV的D2%、D5%、D98%、D95%、D50%、HI、CI和机器跳数中,SW-IMRT计划HI较3DCRT好（1.03∶1.24,P=0.017）;3DCRT计划机器跳数平均值较VMAT减少24.5%（P=0.022）;OAR剂量学参数中3DCRT计划的V30、V40较SW-IMRT和VMAT的分别降低29.4%、28.4%和56.7%、59.7%（P=0.003、0.006和P=0.041、0.019）。结论 早期NSCLC的放疗技术中3DCRT可能是较为合适的技术。

Objective To explore the dosimetric difference between different radiotherapytechnologies in the treatment of early peripheral stage non-small-cell lung cancer （NSCLC）. Methods Four-dimensional computed tomography scans and delineation of target volumes and organs at risk （OARs） were performed in 5 patients pathologically diagnosed with stage T1/T2 peripheral NSCLC who were admitted from 2014 to 2015. Target volumes contained gross tumor volume （GTV）, internal target volume （ITV）, and planning target volume （PTV）. ITV was contoured on the maximum intensity projection images. PTV was defined as ITV plus a 5 mm margin. OARs contained the heart, lung, esophagus, and spinal cord. The Monaco 5.0 treatment planning system was used to design three plans. The three-dimensional conformal radiotherapy （3DCRT） plan had 11 fields in the diseased lung covering the PTV plus a 0.2 cm margin. The sliding window intensity-modulated radiotherapy （SW-IMRT） plan had 9 fields in the same areas as the 3DCRT plan. The volumetric modulated arc therapy （VMAT） plan had the gantry rotating 180° around the diseased lung. The evaluation criteria referred to the RTOG 0618 trial. Comparison was made by paired t test. Results The SW-IMRT plan had a significantly better homogeneity index than the 3DCRT plan （1.03 vs. 1.24,P=0.017）. Compared with the VMAT plan, the mean monitor units in the 3DCRT plan was significantly reduced by 24.5%（P=0.022）. The V30 and V40 of the 3DCRT plan were significantly reduced by 29.4% and 28.4%, respectively, compared with the SW-IMRT plan （P=0.003,0.006） and 56.7% and 59.7%, respectively, compared with the VMAT plan （P=0.041,0.019）. Conclusions 3DCRT may be an appropriate radiotherapy method for early stage NSCLC.