局限期小细胞肺癌两种放射治疗技术的剂量学比较

Dosimetric comparison of conventional and three-dimensional radiotherapy techniques for limited-stage small cell lung cancer

目的探讨2种不同的放射治疗技术治疗局限期小细胞肺癌时，对靶区和危及器官物理剂量学的影响。方法回顾性分析10例局限期小细胞肺癌患者。每例患者在总疗程中需重新定位1次，2个阶段中每阶段均制定常规放疗和三维适形放疗计划（均采用CadplanR3．1．2治疗系统）。总剂量为50Gy。用剂量体积直方图评价2个阶段靶区和危及器官的剂量参数。结果第1阶段治疗适形放疗在计划靶体积1（PTV1）的均匀指数（HI）值、PTV2的适形指数（CI）值、健肺的V30和健肺的平均剂量上优于常规放疗。第2阶段治疗适形放疗在PTV1的CI值、平均剂量、HI值优于常规放疗，FTV2的CI值、平均剂量上也优于常规放疗。结论三维适形放射治疗的优势在于更好的满足CI和HI，但对于危及器官的保护上与常规放疗无明显区别。

Objective To compare the dosimetric difference in planning target volume （FIT） and organ at risk （OAR） with conventional and the three-dimensional treatment planning for limited-stage small cell lung cancer. Methods Ten patients with limited-stage small cell lung cancer were chosen in the present study. Two treatment planning were designed twice respectively with the Cadplan R 3.1.2 treatment planning system for each patient in two-course. The total radiation dose was 50 Gy. The dosimetric parameters were assessed with dose volume histograms in PTV and OAR. Results For the first course, the dose homogeneity indices（HI）of PTV1, conformal indices（CI） of PTV2 , contralateral lung V30 and contralateral mean lung dose in the three-dimensional treatment planning were better than that in the conventional treatment planning. For the second course, the HI, CI and mean dose of PTV1 , CI and mean dose of PTV2 in the three-dimensional treatment planning were better than that in the conventional treatment planning. Conclusions By comparison with conventional treatment planning, the three-dimensional conformal treatment planning could meet the demands of dosimetric requirements well for limited-stage small cell lung cancer with three-dimensional conformal radiotherapy, but with no significant dosimetric differences in the OAR.