儿童全脑全脊髓容积调强弧形放疗的剂量学评估  

Evaluation of dosimetry of volumetric modulated arc therapy in pediatric craniospinal axis irradiation

作　　者：钱建军[1] 孙彦泽[1] 严利明 陆雪官[1] 田野[1] 

机构地区：[1]苏州大学附属第二医院放射治疗科,苏州大学放射肿瘤治疗学研究所,苏州市肿瘤放射治疗学重点实验室,江苏苏州215004

出　　处：《肿瘤》2016年第2期181-186,共6页Tumor

基　　金：国家自然科学基金资助项目(编号:81172128);江苏省“十二五”临床医学重点学科[苏卫科教(2011)12号]~~

摘　　要：目的 :评价容积调强弧形治疗(volumetric modulated arc therapy,VMAT)应用于儿童全脑全脊髓放疗的剂量学。方法 :对10例接受全脑全脊髓放疗的儿童分别设计传统放疗计划[X射线适形放疗(conformal radiotherapy,CRT)_X计划和电子线CRT_E计划]和VMAT计划,比较这3种放疗计划的靶区覆盖度、危及器官(organ at risk,OAR)受照剂量以及出束时间的差异。结果 :采用VMAT技术时的靶区覆盖度、靶区适形指数(conformality index,CI)和剂量均匀指数(homogeneity index,HI)分别为(95.77±0.72)%、1.01±0.03和1.08±0.01,均显著优于CRT_X技术和CRT_E技术[(90.87±1.24)%、1.09±0.08和1.14±0.02,P值均<0.01;(91.06±1.53)%、0.95±0.08和1.14±0.03,P值均<0.01]。采用VMAT技术时,OAR最大受照剂量显著低于CRT_X技术,但略高于CRT_E技术;肺、肾、脾和胃的平均受照剂量显著高于CRT_X和CRT_E技术(P<0.05或P<0.01),但心和肠的平均受照剂量较低。采用VMAT技术时,靶区外整体剂量为(7.57±0.89)Gy,显著高于CRT_X和CRT_E技术(P值均<0.01),但出束时间明显延长(P值均<0.01)。结论 :在儿童全脑全脊髓放疗中,传统的X射线和电子线放疗技术的治疗效率较高,大多数OAR均能得到较好的保护;而VMAT技术的靶区覆盖度和剂量均匀性相对较好,但会明显增加低剂量区体积并延长出束时间,须谨慎考虑可能引发的不良反应及安全性问题。Objective： To evaluate the dosimetry of volumetric modulated arc therapy（VMAT） in pediatric craniospinal axis irradiation（CSI）.Methods： Conventional radiation therapy planning [conformalradiotherapy_X ray（CRT_X） and CRT_electron beam（CRT_E） plannings] and VMAT planning were designed for CSI in ten pediatric patients. The dosimetric parameters including target dose coverage, organ at risk（OAR） dose-volume level and beam time were compared among three radiation therapy plannings.Results： The target dose coverage, conformality index（CI） and homogeneity index（HI） of VMAT planning were（95.77±0.72）%, 1.01±0.03 and 1.08±0.01, respectively, which were superior to those of CRT_X planning [（90.87±1.24）%, 1.09±0.08 and 1.14±0.02, respectively; all P 0.05] and CRT_E planning [（91.06±1.53）%, 0.95±0.08 and 1.14±0.03, respectively; all P 0.01]. The maximal irradiation dose of OAR in VMAT planning was obviously lower than that in CRT_X planning, but slightly higher than that in CRT_E planning. The mean irradiation doses of lung, kidney, spleen and stomach in VMAT planning were significantly higher than those of CRT_X and CRT_E plannings（P 0.05 or P 0.01）, but which of heart and bowel were lower. The non-target integral dose in VMAT planning was（7.57±0.89） Gy, which was higher than those of CRT_X and CRT_E plannings（both P 0.01）, but the beam time was significantly prolonged（both P 0.01）.Conclusion： In pediatric craniospinal axis irradiation, VMAT can significantly improve the dose conformality and homogeneity and eliminate field matching, but prolong the beam time and extend low dose volume. Hence, treatment toxicity and radiotherapy security should be considered carefully.

关 键 词：放射疗法 全脑全脊髓 容积调强弧形治疗 剂量学 儿童 

分 类 号：R730.55[医药卫生—肿瘤]