食道癌心脏瓣膜勾画差异对剂量分布的影响

Dosimetric impact of heart valve delineation variability of inter-observer on radiotherapy of patients with esophagus carcinoma

目的：评价在全盲模式下,食道癌根治性放疗时,心脏勾画图谱统一学习前后不同研究者勾画心脏的差异,及其对全心和各瓣膜受照剂量分布的影响。方法：对10名未行手术的食道癌患者,在全盲模式下,由5名医生在统一学习心脏图谱前后行两次心脏靶区勾画,比较学习前后全心勾画的差异以及全心和各个瓣膜受照射剂量的变化。结果：与无指南相比,引入指南后,心脏勾画的体积明显增大从635.3 cm3增加到647.6 cm3,Soensen-Dice相似指数从0.84~0.87增加至0.92~0.94;Jaccard相似指数从0.91~0.93增加至0.96~0.97,I_Tot/U_Tot从0.75±0.02提高到0.84±0.03。除全心和肺动脉瓣外,主动脉瓣、二尖瓣和三尖瓣的平均照射剂量（Dmean）和最大照射剂量（Dmax）较引入指南前均明显提高,全心及所有瓣膜的Dmean和Dmax的变异系数均有明显提高。结论：心脏勾画指南的引入明显缩小了不同研究者对心脏勾画的差异,这种差异的改变对全心和肺动脉瓣膜受照剂量没有明显影响,导致了主动脉瓣、二尖瓣及三尖瓣Dmean和Dmax的不同,而心脏勾画指南的引入减小了上述所有结构的受照射剂量差异。

Objective：To determine the extent of inter-observer variation in delineation of heart after and before studying the heart atlas and its impact on dose distribution of the whole heart and every cardiac valve in radical radiotherapy of patients with esophagus cancer in blind modes. Methods：Ten patients with esophagus cancer and without operation were asked to contour the heart in computed tomography transverse section in blind modes by five observers. Inter-observer variability were compared in the delineation of the whole heart and estimated doses for heart and every cardiac valve before and after studying the heart atlas. Results：Compared with the mean heart volume without guidelines,the mean heart volume with guidelines was increased from 635.3 cm3to 647.6 cm3. Soensen-Dice similarity index（DSI）was increased from 0.84~0.87 to 0.92~0.94. Jaccard similarity index（JSI）was increased from 0.91~0.93 to 0.96~0.97. After learning guidelines,the volume of the heart was increased significantly,I_Tot / U_ Tot increased from 0.75 ± 0.02 to 0.84 ± 0.03. In addition to the heart and the pulmonary valve,Dmean and Dmax of aortic valve,mitral valve,tricuspid valve were increased significantly after learning guidelines. The coefficients of variation（CV）of Dmean and Dmax of hart and valves were increased significantly. Conclusion：There was a significant difference in the delineation of heart for different observers,which could be decreased by the introduction of heart atlas. The delineating inter-observer variability has no dosimetric effects on the whole heart and pulmonic valve,leads to the difference of Dmean and Dmax of the estimated dose on aortic valve,mitral valve,tricuspid valve. Furthermore,the introduction of heart atlas decreases the difference of radiation dose among the above structures.