全脑及局部转移灶同步推量螺旋断层调强放射治疗与静态调强放射治疗的剂量学比较

摘要

目的:比较不同放射治疗技术实施全脑放射治疗及局部转移灶同步推量放射治疗(WBRT+SIB)中的剂量学差异,为临床脑转移瘤患者提供最合适的放射治疗方案.方法:选取8例接受WBRT+SIB的患者CT图像,分别完成7野静态调强放射治疗(IMRT)及螺旋断层调强放射治疗(TOMO)系统的WBRT+SIB计划,比较两计划间处方剂量覆盖度(V30)、靶区适形指数(CI)、剂量均匀性指数(HI)、重要器官的最高剂量(Dmax)及平均剂量(Dmean)间的差异.结果:TOMO在剂量覆盖度、靶区的适形度以及剂量均匀性方面均优于IMRT,差异有统计学意义(t=-8.74,t=2.88,t=-3.25;P<0.05),且能更好的保护正常组织,减少眼球及晶体的照射剂量;两种放射治疗技术CI的差值与转移瘤的个数呈明显的线性相关.结论:在全脑及局部转移瘤的放射治疗中,TOMO在靶区的处方剂量覆盖度、适形指数及均匀性指数上均优于IMRT,正常组织受量低于IMRT.随着转移瘤数目的增加,TOMO在靶区适形度上的优势更加明显,因此TOMO可成为脑转移瘤患者更好的选择.%Objective:To compare the dosimetric difference between intensity modulated radiation therapy (IMRT) and tomotherapy (TOMO) for whole-brain radiotherapy (WBRT) combined with simultaneous integrated boost (SIB) of local brain metastases, and provide a best choice for patient with brain metastasis.Methods: The CT images of 8 patients with brain metastases were applied WBRT+SIB plan in IMRT and TOMO, respectively. A series of indicators, such as conformity index(CI), homogeneity index(HI), coverage of prescribed dose (V30), the maximum dose (Dmax) and mean dose(Dmean) of important organs were compared. Results: TOMO appeared more effect than IMRT in V30, HI and CI (t=-8.74,t=2.88,t=-3.25;P<0.05); and it also could protect normal organic, reduce radiation dose for eye and lens in more degree than IMRT; besides, with the increase of the number of brain metastasis, the CI difference between TOMO and IMRT also was increase, therefore, there was a obvious positive linear correlation between them.Conclusion: In WBRT+SIB,TOMO has obviously advantages than IMRT such as 30Gy(V30), HI, CI and the protection for organs. With the increase of the number of metastasis, TOMO appears more preponderance than IMRT; therefore, TOMO might be a good clinical choice for WBRT+SIB treatment.