鼻咽癌部分危及器官勾画差异对剂量分布的影响

Dosimetric impact of organs at risk delineation variability of inter-observer on patients with nasopharyngeal carcinoma

目的探讨全盲下危及器官(OARs)勾画指南的统一学习对鼻咽癌放疗时OARs勾画的体积及受照剂量分布差异的影响。方法在全盲模式下,由4名医师对8例鼻咽癌患者在CT横断面上勾画双侧颞叶、内耳、中耳,后统一学习OARs勾画指南,比较学习前后上述OARs体积的差异及其受照射剂量的变化。结果学习前后内耳及中耳绝对体积没有明显差异(P>0.05);学习后,左右两侧的颞叶的体积均较学习前有所缩小(P<0.05);上述3种OARs的一致性指数(AI)在学习后明显提高(P<0.05)。从剂量学来看,与学习前相比,除了左侧内耳Dmean,右侧内耳的Dmean及两侧内耳的V50均有统计学差异(P<0.05);除了左侧中耳Dmean,右侧中耳的Dmean及两侧中耳的V50均无统计学差异(P>0.05);右侧颞叶的D2和左侧颞叶的Dmax、D1、D2在学习前后存在明显差异(P<0.05)。指南的统一学习使双侧内耳Dmean和V50、左侧中耳的V50、左侧颞叶D1和右侧颞叶D2的Kappa值均明显提高(P<0.05)。结论不同观察者勾画的OARs体积和剂量之间存在明显差异,统一学习明显提高了颞叶、中耳及内耳勾画的准确性及一致性,从而使放疗计划的评价更加客观。

Objective To investigate the extent of inter.observer variation in delineation of the organs at risk before and after studying the recommendation and its impact on estimating doses in blind mode. Methods Eight patients with nasopharyngeal carcino.ma were asked to contour bilateral inner ear, middle ear and temporal lobe on computed tomography transverse section in blind mode by four observers. Inter.observer variability were compared in the delineation of the above organs and estimated doses for these before and after studying the recommendation. Results No difference of absolute volumes of inner ear, middle ear were observed（ P＆gt;0.05） , that of bilateral temporal lobe decreased significantly（ P〈0.05）;The agreement index （ AI） of three organs at risk volume contoured by four observers increased significantly（ P〈0.05） . Based on analysis of dosage, there was significant difference for Dmean of right inner ear and V50 of bilateral inner ear except Dmean of left inner ear（ P〈0.05）;There was no significant difference for Dmean of right middle ear, V50 of left middle ear except Dmean of left middle ear（ P〉0.05）;Significant difference were observed for D2 of right temporal lobe and Dmax , D1 and D2 of left temporal lobe （ P〈0.05）;The recommendation significantly improved Kappa value of Dmean and V50 of bilateral inner ear, V50 of left middle ear, D1 of left temporal lobe and D2 of right temporal lobe（ P〈0.05） . Conclusion Different volumetric and do.simetric parameters may hinder the different researchers. The unified and standardized training can improve the accuracy and concord.ance of delineation, which caused evaluation of treatment plannings more objectively.