非均整器模式下早期非小细胞肺癌 3 种放疗技术剂量学研究

Dosimetric evaluation of three radiotherapy techniques for early stage NSCLC with flattening filter-free beams

摘要:

目的 从剂量学角度比较非均整器（FFF）模式下早期非小细胞肺癌（NSCLC）立体定向放射治 疗的不同放疗技术。方法 选取15 例NSCLC 作为研究对象，分别设计FFF 模式下适形拉弧（CAT）、三维适 形技术（3D-CRT）及容积弧形动态旋转调强（VMAT）计划。比较3 种计划95%、105% 的处方剂量覆盖 靶区体积百分数（V95%、V105%）、靶区均匀度（HI）、适形度（CI）、最大剂量（Dmax）和平均剂量（Dmean）、 危及器官（OAR）剂量、机器跳数（MU）及治疗时间（TT）。结果 CAT 和3D-CRT 计划中的计划靶区（PTV） V95%、CI 低于VMAT 计划（P <0.05），而V105%、HI、Dmax、Dmean 高于VMAT 计划（P <0.05）；在患侧肺 V5、V20、V30、V40、Dmean 方面，CAT 和3D-CRT 计划高于VMAT 计划（P <0.05）；在患侧肺V20、V30 方面， 3D-CRT 计划高于CAT 计划（P <0.05）；在脊髓Dmax，3D-CRT 计划低于CAT 与VMAT 计划（P <0.05）； CAT、3D-CRT 计划的MU 低于VMAT 计划（P <0.05）。在治疗时间上CAT 低于3D-CRT，且两者均少于 VMAT（P <0.05）。结论 FFF 模式下3 种计划均能满足临床要求，靶区CI、HI 及患侧肺保护的VMAT 计划 优于CAT 和3D-CRT 计划，但在执行效率，CAT 和3D-CRT 更具有优势。

Abstract:

Objective To investigate the dosimetric difference between different radiotherapy techniques in treatment of early stage non small cell lung cancer (NSCLC) using stereotactic body radiotherapy (SBRT) in flattening filter free (FFF) beams. Methods A total of 15 early stage NSCLC patients were recruited in this study; flattening free filter CAT, 3D-CRT and VMAT plans were generated with the same prescription dose and objective conditions for each patient. Target volume receiving 95% and 105% prescription dose (V95%, V105%), conformity index (CI), homogeneity index (HI), maximum dose (Dmax), mean dose (Dmean) of target, the radiation dose of organs at risk (OARs), the monitor units and the treatment time were analyzed among the three types of plan. Results As for PTV, V95%, CI in CAT and 3D-CRT plans were lower than those in VMAT plan (P < 0.05), while the V105%, HI, Dmax, Dmean were higher than those in VMAT plan (P < 0.05). As for OARS, V5, V20, V30, V40, Dmean of the ipsilateral lung in CAT and 3D-CRT plans were higher than those in VMAT plan (P < 0.05). V20 and V30 of the ipsilateral lung in 3D-CRT plan were higher than those in CAT, (P < 0.05). The Dmax of spinal cord in 3D-CRT was lower than that in CAT and VMAT plans (P < 0.05). MUs of CAT and 3D-CRT were obviously less than those of VMAT plan (P < 0.05). For the time of treatment, CAT was less than 3D-CRT, and both of them were less than VMAT (P < 0.05). Conclusion All the three plans with FFF beams meet the clinical requirements, but VMAT performs the best on CI, HI and the protection of ipsilateral lung. But CAT and 3D-CRT have more advantages as regarding plan execution efficiency.