摘要
目的:通过对CT模拟(CT-Sim)定位阶段确定的治疗等中心与治疗计划系统(TPS)阶段确定的治疗等中心进行容积旋转调强放射治疗(VMAT)计划剂量学比较,探讨在CT-Sim阶段确定脑胶质瘤治疗等中心的可行性。方法:选取医院收治的17例脑胶质瘤术后患者,按治疗等中心选择位置的不同,将TPS自动放置等中心(TPS-AUTO)纳入TPS-AUTO组,将CT-Sim定位技术确定的术后靶区中心(Sim-AUTO)纳入Sim-AUTO组,将CT-Sim定位技术确定的听眉线上5 cm层面为全脑中心(Sim-RML)纳入Sim-RML组,将TPS放置的基于靶区几何中心的等中心(TPS-GEOM)纳入TPSGEOM组共计4组。放射治疗设计的等中心进行VMAT计划设计,以TPS自动放置等中心(TPS-AUTO)计划为基准,比较4组方案的靶区20%、50%、98%靶区体积的受照剂量(D_(2)、D_(50)、D_(98))、适形度指数(CI)和均匀性指数(HI)等剂量参数。结果:4组计划的靶区近似最大剂量(D2)、平均剂量(D_(50))、最小剂量(D_(98))、CI和HI剂量学参数均能满足临床要求。通过比较靶区计划肿瘤体积(PGTV)64靶区剂量学参数,以CT-Sim定位技术确定的治疗等中心在CI上优于TPS确定的治疗等中心,但差异无统计学意义,比较PGTV58靶区剂量学参数,D98在TPS确定的等中心计划中高于CT-Sim定位技术确定的全脑中心(t=2.128,P<0.05),但CI值低于CT-Sim定位技术确定的全脑中心,差异均有统计学意义(t=-3.498,P<0.05),TPS放置的基于几何中心的等中心的全脑低剂量区V10和总MU更小。Sim-AUTO组脑干外扩3 mm的1cc体积所受照剂量(D1cc)优于TPS-AUTO组,差异具有统计学意义(t=-5.337,P<0.05)。结论:通过CT-Sim定位技术确定的放射治疗等中心进行计划设计能够满足临床所需的靶区要求,并减少复位过程中误差的引入,避免潜在错误,提高工作效率。
Objective: To explore the feasibility of determining isocenter of treatment of glioma in computed tomography(CT) Sim stage through conducted dosimetry comparison for the volumetric modulated arc therapy(VMAT) plans which respectively obtained from the treatment isocenter that was determined at CT simulated location Sim stage and the treatment isocenter that was determined at treatment plan system(TPS) stage. Methods: A total of 17 postoperative patients with glioma who admitted to hospital were selected and they were divided into 4 groups according to the different position that was chosen by the treatment isocenter. The auto-placed isocenter by TPS(TPSAUTO) was included into TPS-AUTO group, and the center of postoperative target region that was determined by CT-Sim technique(Sim-AUTO) was included into Sim-AUTO group. The 5cm layer above glabellomeatal line(SimRML), which was judged as center of whole brain and was determined by CT-Sim technique, was included into SimRML group, and the isocenter based on geometric center(TPS-GEOM) of target region that was placed by TPS was included into TPS-GEOM group. The isocenter of the radiotherapy plan was designed by VMAT plan, the TPSAUTO plan was used as standard to compare the received doses of 20%, 50% and 98% volumes(D2, D50, D98) of target region, conformal index(CI) and homogeneity index(HI) among 4 groups. Results: The dosimetric parameters of the four groups, including approximate maximum dose(D2), approximate average dose(D50), approximate minimum dose(D98), CI and HI could meet the clinical requirement. By comparing the dosimetric parameters of PGTV64 target region, the treatment isocenter that was determined by CT-Sim technique were superior to the treatment isocenter that was determined by TPS, but the difference of that between them was not statistically significant. By comparing the dosimetric parameters of PGTV58 target region, D98 in the center plan that was determined by TPS was higher than the whole brain center that was determined by CT-Sim technique(t=2.128, P<0.05), but CI value of former was lower than the latter, the difference of that between them was statistically significant(t=-3.498, P<0.05). The V10 and total MU of the low-dose region of whole brain based on the isocentric of geometric center, which was placed by TPS, were smaller. The received exposure dose of 1cc volume at external expansion 3mm away brain stem in Sim-AUTO group was better than that in TPS-AUTO group, and the difference of that between two groups was significant(t=-5.337,P<0.05). Conclusion: The plan and design through the isocenter of radiotherapy is determined by CT-Sim can meet the demand of target region, which is the requirements of clinical practice, and reduce the introduction of errors in the restoration process, and avoid the potential errors, and improve the process efficiency.
作者
孙博
陈星宇
庞得全
SUN Bo;CHEN Xing-yu;PANG De-quan(Department of Radiotherapy,North China of Science and Technology Affiliated Hospital,Tangshan 063000,China.)
出处
《中国医学装备》
2023年第2期13-18,共6页
China Medical Equipment
