III期非小细胞肺癌三维适形与调强技术的剂量学比较

Dosimetric comparison of three- dimensional conformal radiotherapy and intensity modulated radiotherapy for III-stage non-small cell lung cancer

目的:比较III期非小细胞肺癌三维适形放疗(Three Dimensional Conformal Radiotherapy,3D-CRT)和调强放疗计划(Intensity Modulated Radiotherapy,IMRT)在靶区和危及器官上的剂量差异,为临床医生选择合适的放射治疗技术提供可靠的治疗依据。方法:选择16例III期非小细胞肺癌患者,采用Pinnacle V9.2治疗计划系统分别为每例患者设计3DCRT和IMRT两组放疗计划,分析比较两组计划的靶区适形度指标(Conformity Index,CI)和均匀性指数(Homogeneity Index,HI)以及正常组织的剂量分布。结果:IMRT和3D-CRT的靶区CI分别为0.97±0.02和0.91±0.04;HI分别为0.16±0.06和0.20±0.14,且差异具有统计学意义(P<0.05)。其余危及器官剂量参数,除肺组织V_5、V_(10)外,IMRT技术较3D-CRT技术均有不同程度的降低。结论:对于III期非小细胞肺癌的放射治疗,IMRT技术能够在提高靶区剂量的均匀性和适形度的同时,有效降低正常组织的受照剂量,从而降低患者放疗后并发症发生的可能性。

Objective To provide a reliable treatment basis for selecting the appropriate radiotherapy by comparing the dose differences of target volumes and organs at risk between three-dimensional conformal radiotherapy （3D-CRT） and intensity modulated radiotherapy （IMRT） for Ⅲ-stage non-small cell lung cancer （NSCLC）. Methods Sixteen patients with Ⅲ-stage NSCLC were selected, and Pinnacle V9.2 treatment planning system was applied to design 3D-CRT and IMRT plans for each patient. The conformity index and homogeneity index of target volumes, and dose distribution of normal tissue were compared. Results The conformity indexes of IMRT and 3D-CRT plans were respectively 0.97±0.02 and 0.91±0.04; the homogeneity indexes of IMRT and 3D-CRT plans were respectively 0.16±0.06 and 0.20±0.14, with statistically significant differences （P〈0.05）. The dose parameters of organs at risk of IMRT plan were all lower than those of 3D-CRT plan in different degrees, except V5 and V10 of lung tissue. Conclusion Compared with 3D-CRT, IMRT for Ⅲ-stage NSCLC provides significant improvement in conformity and homogeneity, effectively lowers the radiation dose of normal tissue, and lowers the possibility of complication after the radiotherapy.