早期鼻咽癌三维适形和常规外照射计划的剂量学评价(英文)

目的利用二维治疗计划系统对早期鼻咽癌常规和三维适形放疗(3D CRT)计划作剂量学比较,评估不同照射方法剂量分布的差异,为今后指导临床治疗提供剂量学的依据。方法选择22例早期鼻咽癌患者,用三维治疗计划系统对每例患者分别作出常规和3D CRT 计划设计,然后根据靶区覆盖率(V_(95))、正常组织受量(D_(50),D_(33)和 D_5等)和正常组织并发症发生率(NTCP)比较这两种计划。结果剂量学比较表明,常规和3D CRT 的 PTV_(nx70)、PTV_(nd60)、PTV_(nx60)、PTV_(nx50)的 V_(95)分别为98.22%和99.98%(P=0.06)、98.41%和99.63%(P=1.00)、98.22%和99.98%(P=0.03)、98.85%和99.63%(P=0.02)。保护正常组织方面:在3D CRT 和常规计划中,单侧腮腺的 D_(50)分别为51.91Gy 和64.30Gy(P=0.00),单侧颞颌关节 D_(50),49.98Gy 和64.47Gy(P=0.00),脊髓 D1cc,44.98Gy和48.09Gy(P=0.00)。结论 3D CRT 在亚临床靶区比常规方法有稍好的靶区覆盖率,3D CRT 治疗早期鼻咽癌的优势在于给予靶区相似剂量分布的前提下,可以比常规方法减少某些正常组织器官如腮腺、颞颌关节等照射剂量,减少它们的 NTCP。

Dosimetric Evaluation of Three Dimensional Conformal and Conventional Treatment Plans of Early Untreated Carcinoma of Nasopharynx

Objective:Conventional external beam irradiation techniques for nasopharyngeal carcinoma have limitations,and improving external beam irradiation techniques is needed to enhance the curative rate.This study was designed to evaluate the difference in dose distribution of three dimensional confbrmal radiotherapy(3D CtRT)and conventional treatment plan in early untreated nasopharyngeal carcinoma us- ing a three dimensional treatment planning system.Methods:Twenty-two patients with early untreated nasopharyngeal carcinolna were selected.Conventionai and 3D CRT plans were made for each of them and compared with respect to target volume coverage(V_(95)),normaI tissue sparing(D)_(50),D_(33)and D_5,etc),nor- real tissue complication probability(NTCP).Results:The average vohnnetrie dose comparison indicated that the V_(95)of PTV_(nx)70 were 98.22% and 99.99%(P=0.06),and PTV_(nd60),98.41% and 99.63%(P=100), PTV_(nx60),98.44% and 99.98%(P=0.03),PTV_(nx50),98.85% and 99.63%(P=0.02)in conventional and 3DCRT txeatment plans respectively.With respect to normal tissue sparing,the average D_(50)of unilateral parotid glands were 51.91 Gy and 64.30 Gy(P=0.00)respectively,and the unilateral temporomandibular joints.19.98 Gy and 64.47 Gy(P=0.00),the Dice of spinal cords,44.98 Gy and 48.09 Gy(P=0.00)in 3D CRT and conventional plans.Conclusion:Though only a little bit better dose coverage of target volume in subclinical lesion region was reached in 3D CRT plans,it spared more normal tissues e.g.parotid glands and temporomandibnlar joints etc and decreased their NTCP while it got the similar dose distribution in target volumes as conventional plans did for these early nasopharyngeal carcinoma cases.