III期非小细胞肺癌碳离子放疗与光子容积旋转调强放疗的剂量学对比研究

目的:比较碳离子二维放射治疗(two-dimensional carbon-ion radiotherapy,2D-CIRT)计划与光子容积调强放射治疗(volume modulated arc therapy,VMAT)计划在III期非小细胞肺癌中剂量学优劣，为临床碳离子治疗提供依据。方法:选取我中心13例III期非小细胞肺癌患者，使用相同的处方剂量及危及器官约束条件，分别在Ciplan计划系统上设计2D-CIRT计划和Eclipse计划系统上设计VMAT计划，比较剂量-体积直方图，评价靶区剂量分布及危及器官受量。采用SPSS 22.0软件进行数据分析。结果:CIRT和VMAT计划肿瘤覆盖率均较好，PTV1的D98、D95、D50差异无统计学意义，两种计划的均匀性指数（homogeneity index,HI）相似（CIRT与VMAT:0.39 Gy与0.38 Gy，P＞0.05）。PTV2两种方案在D95、D98、D50、D2均有显著性差异，PTV2采用CIRT的HI也明显优于VMAT(CIRT vs VMAT:0.08 Gy vs 0.16 Gy,P=0.003)。与光子VMAT相比，CIRT计划中健侧肺的V5、V10、V20、V30、V40和Dmean明显降低。患侧肺中CIRT的V5低于VMAT（CIRT vs VMAT:53.00 Gy vs 64.41 Gy，P=0.003），V10、V20、V30、V40、Dmean两种计划均无统计学差异；CIRT有较低的脊髓Dmax（CIRT vs VMAT:18.61 Gy vs 43.03 Gy，P=0.000）、食管Dmean（CIRT vs VMAT:16.25 Gy vs 20.38 Gy，P=0.031）和V50（CIRT vs VMAT:4.49 Gy vs 11.43 Gy，P=0.005）、骨V10和V30，以及气管和支气管树的V50。结论:与光子VMAT相比，2D-CIRT被动束流扫描技术在III期非小细胞肺癌治疗中显著降低了对危及器官的辐射剂量，对正常组织有更好的保护作用。

A dosimetric comparative study of carbon-ion radiotherapy versus x-rayvolumetric modulated arc therapy for stage III non-small cell lung cancer

Objective:To examine whether two-dimensional carbon-ion radiotherapy(2D-CIRT)is dosimetrically superior to photon beam volume modulated arc therapy(VMAT)in the treatment of stage III non-small cell lung cancer(NSCLC),and provide basis for clinical carbon ion therapy.Methods:To select 13 patients in our center with stage III NSCLC whom were calculated 2D-CIRT by Ciplan planning system and VMAT by Eclipse planning system.The optimization constraints of the two designs were basically the same.Target dose distribution and organs at risk(OARs)doses were evaluated by dose-volume histograms(DVH).SPSS 22.0 software was used for data analysis.Results:Both CIRT and VMAT plans had good tumor coverage with no significant differences in D98,D95,and D50 of PTV1 between the two plans.The homogeneity index(HI)between the two plans were similar(CIRT vs VMAT:0.39 vs 0.38,P＞0.05).There were significant differences in D98,D95,and D50 of PTV2 between the two plans.The HI of PTV2 was significantly superior in the CIRT plan(CIRT vs VMAT:0.08 vs 0.16,P＜0.05).The V5,V10,V20,V30,V40,and Dmean of the contralateral lung in the CIRT plan were significantly reduced compared with the photon VMAT.The V5 of the ipsilateral lung was slightly lower in the CIRT plan(CIRT vs VMAT:53.0% vs 64.4%,P＜0.05).There were no differences between the two groups of the V10,V20,V30,V40,and Dmean.The CIRT had a lower spinal cord Dmax(CIRT vs VMAT:18.61 Gy vs 43.03 Gy,P＜0.000 1),esophageal Dmean（CIRT vs VMAT:16.25 Gy vs 20.38 Gy,P=0.031）and V50（CIRT vs VMAT:4.49% vs 11.43%,P=0.005）,V10 and V30 of bone,and the V50 of the trachea and bronchial tree.Conclusion:As compared with photon VMAT,2D-CIRT using passive beam scanning technology significantly reduces radiation dose to the OARs in the treatment of stage III NSCLC,suggesting a better protection of the normal tissues.