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目的比较脑恶性胶质瘤术后同期加量调强放疗与序贯加量适形放疗计划中不同参数的剂量学。方法选择10例脑恶性胶质瘤术后患者(WHO分级3级5例,4级5例),采用颅脑CT和MRI双定位,在Pinnacle3治疗计划系统中将CT和MRI图像融合后,在MRI图像上勾画和定义靶区。将瘤床(包括术腔和术后残留病灶)定义为肿瘤靶区(GTV),GTV外放10mm定义为临床靶区1(CTV1),GTV外放25mm定义为临床靶区2(CTV2),CTV1和CTV2各外放5mm分别定义为PTV1和PTV2。基于每例患者勾画和定义所得靶区,分别制定同期加量调强放疗(SIB-IMRT)计划和序贯加量适形放疗(SB-CRT)计划。SIB-IMRT计划处方剂量:PTV2为50.0Gy/25次,PTV1同步加量至62.5Gy/25次,;SB-CRT计划处方剂量:PTV2为50.0Gy/25次,PTV1序贯加量至66.0Gy/33次。采用配对t检验比较两种计划不同参数的剂量学。结果两种计划中,PTV1的最大剂量、PTV1的平均剂量、PTV2的平均剂量差异均有统计学意义(P﹤0.05),SIB-IMRT计划的适形指数(CI)及异质性指数(HI)均优于SB-CRT计划(P﹤0.05);两种计划中,脑干的最大受剂量及平均剂量差异均有统计学意义(P﹤0.05),全脑的平均剂量差异也有统计学意义(P﹤0.05),而两个计划中双侧晶体及双侧视神经的最大剂量差异则均无统计学意义(P﹥0.05)。结论脑恶性胶质瘤术后同期加量调强放疗计划优于序贯加量适形放疗计划,在优化计划靶区剂量适形性和均匀性的同时,显著降低了脑干和全脑受照剂量,而且缩短了总治疗时间。
Objective To compare the dosimetry of different parameters of intensity-modulated radiotherapy and sequential plus conformal radiotherapy in the same period after surgery of brain glioblastoma. Methods Ten patients with malignant gliomas were enrolled in the study (WHO grade 5, grade 5, grade 4, grade 5). CT and MRI were combined by brain CT and MRI. After fusion of CT and MRI images in Pinnacle3 treatment planning system, The target area is sketched and defined on the MRI image. The tumor bed (including the surgical cavity and postoperative residual lesions) was defined as the tumor target (GTV). GTV was defined as clinical target 1 (CTV1) 10mm, GTV was defined as clinical target 2 (CTV2) 5mm each of CTV1 and CTV2 are defined as PTV1 and PTV2. The SIB-IMRT and SB-CRT plans were developed based on the delineation and definition of target areas for each patient. SIB-IMRT planned prescription dose: PTV2 50.0Gy / 25 times, PTV1 synchronous dose to 62.5Gy / 25 times; SB-CRT planned prescription dose: PTV2 50.0Gy / 25 times, PTV1 sequential dose to 66.0Gy / 33 times. The paired t test was used to compare the dosimetry of two different plan parameters. Results The maximum dose of PTV1, the average dose of PTV1 and the average dose of PTV2 were significantly different between the two plans (P <0.05). The CI and HIFI of SIB-IMRT ) Were superior to those of SB-CRT (P <0.05). In both plans, the maximum dose and average dose of brain stem had statistical significance (P <0.05), and the average dose of whole brain also had statistical significance (P <0.05). However, the maximum dose differences between bilateral and bilateral optic nerves in the two plans were not statistically significant (P> 0.05). Conclusions Compared with the sequential dosage of conformal radiotherapy, the intensity-modulated radiotherapy schedule of brain glioblastoma at the same period after surgery is significantly lower than that of the control group According to the dose, but also shortens the total treatment time.