有无均整器模式下脊柱转移瘤立体定向放疗计划的剂量学比较

Dosimetric comparison of stereotactic body radiation therapy plans for spine metastasis using flattening filter free and flattening filter modes

目的比较6MVX射线无均整器模式（FFF）和均整器模式（FF）下，脊柱转移瘤立体定向放疗（SBRT）计划的剂量学差异。方法选取9例入组患者共12处脊柱转移灶分别设计FFF—SBRT和FF—SBRT计划，比较两组计划的靶区、危及器官和正常组织剂量体积直方图（DVH）、靶区适形度（CI）、机器跳数和治疗时间的差别。结果两种模式下的计划均能满足临床治疗需要。靶区、危及器官、正常组织剂量分布相似。FFF—SBRT计划的机器跳数明显高于FF—SBRT计划（t=-5．20，P〈0．01），实际治疗时间相当于FF—SBRT计划的1／2（t=17．27，P〈0．01）。结论两种模式均能满足临床治疗需求，FFF-SBRT计划的治疗时间更短，效率更高。临床试验注册中国临床试验注册中心，ChiCTR-TRC-14004281。

Objective To compare the dosimetric difference of stereotactic body radiation therapy （SBRT） plans for spine metastasis using 6 MV X-ray flattening filter free （FFF） and flattening filter （FF） modes. Methods A total of nine previously treated patients with a total of twelve spine metastasis were retrospectively included and replanned using FFF-SBRT and FF-SBRT, respectively. The dose-volume histograms （ DVH ） , target conformity index （ CI ） , monitor unites （ MUs ） and treatment time of target volume, organs at risk and normal tissues were compared between the plans. Results Both FFF-SBRT and FF-SBRT met the clinical objectives. Dose distribution of target volume, organs at risk and normal tissues were similar. MUs of the FFF-SBRT were significantly higher than that of FF-SBRT （ t = - 5.20, P〈0. 01）, while the treatment time was almost half of the latter （t = 17.27, P 〈0. 01 ）. Conclusions Two plan modes are both clinically acceptable. FFF-SBRT plans are delivered in less time and with better efficiency. Trial registration Chinese clinical trial registry, ChiCTR-TRC-14004281.