射野角度优化方法在全段食管癌IMRT计划设计中的应用

目的:分析射野角度优化（BAO）布野、均分布野和人工布野3种5野全段食管癌IMRT计划设计方法的剂量学差异,为全段食管癌IMRT计划设计提供临床参考。方法:选取15例行IMRT治疗的全段食管癌患者,分别设计3种5野IMRT（5f-IMRT）计划:基于BAO方法布野计划组（A组）、均分布野计划组（B组）以及人工布野计划组（C组）。用靶区覆盖率、适形度指数（CI）和均匀性指数（HI）以及各危及器官的剂量学参数来比较3组计划方法的剂量学差异,统计分析用配对t检验方法。结果:3组计划的靶区剂量覆盖均能满足临床要求。对于危及器官,A组计划的双肺Dmean和心脏平均值明显低于其他两组计划,差异有统计学意义（P<0.05）。相对于C组计划,A组和B组计划中双肺的V20 Gy和心脏V30 Gy均明显降低（P<0.05）,其中A vs C、B vs C的双肺V20 Gy和心脏V30 Gy分别为［（29.15±2.75）% vs （30.03±2.55）%, P=0.005］、［（29.08±2.40）% vs （30.03±2.55）%, P=0.005］和［（45.37±4.59）% vs （48.24±6.45）%, P=0.010］、［（45.79±4.60）% vs （48.24±6.45）%, P=0.040］。最后,对3组计划的剂量学参数进行综合评分,其中A组计划中的靶区PTVx综合评分、危及器官综合评分和计划综合评分得分均为最高,其中计划综合评分CSFTotal为7。C组计划综合评分最差,CSFTotal为-4。结论:相比于人工布野方法与均分布野方法设计的全段食管癌5f-IMRT计划,BAO计划具有明显的剂量学优势,建议在全段食管癌的计划设计中推广应用。

Application of beam angle optimization in intensity-modulated radiotherapy planning for esophageal cancer

Objective To study the dosimetric differences among 5-field intensity-modulated radiotherapy(5f-IMRT)plans designed by beam angle optimization(BAO),uniform field distribution or artificial field distribution for providing clinical reference for the IMRT planning for esophageal cancer.Methods Fifteen patients with esophageal cancer treated with IMRT were selected,and 3 kinds of 5f-IMRT plans were designed for each patient,namely BAO group(group A),uniform field distribution group(group B)and artificial field distribution group(group C).The target coverage,conformity index,homogeneity index of target areas and the dosimetric parameters of organs-at-risk were used to compare the dosimetric differences among 3 groups.Paired-t test was used for statistical analysis.Results The target coverage of all 3 groups met the clinical requirements.The mean doses of the lung and the heart in groupAwere significantly lower than those in the other two groups,with statistical significance(P<0.05).Compared with those in group C,the lung V20 Gy and heart V30 Gy in group A and group B were significantly lower(P<0.05).The lung V20 Gy of A vs C and B vs C were[(29.15±2.75)%vs(30.03±2.55)%,P=0.005]and[(29.08±2.40)%vs(30.03±2.55)%,P=0.005)],respectively,and the heart V30 Gy were[(45.37±4.59)%vs(48.24±6.45)%,P=0.010)]and[(45.79±4.60)%vs(48.24±6.45)%,P=0.040)],respectively.Finally,the dosimetric parameters of 3 groups were evaluated to obtain comprehensive scoring factorbased scores(CSF).The CSFPTVx,CSFOAR and CSFTotal in groupAwere the highest,and CSFTotal reached 7;and group C had the worst CSFTotal which was-4.Conclusion BAO plan for esophageal cancer has obvious dosimetric advantages over the 5f-IMRT plans designed by uniform field distribution and artificial field distribution,which suggests that BAO plan should be popularized and applied in the treatment planning for esophageal cancer.