Interobserver variations in the delineation of planning target volume and with orgagans at risk different contouring methods in intensity-modulated radiation therapy for nasopharyngeal carcinoma
Peng Yinglin1, Sun Wenzhao1, Cheng Wanqin2, Xia Haiqun3, Yao Jijin4, Xiao Weiwei1, Shen Guanzhu5, Yang Lin1, Zhou Shu1, Li Jiaxin6, Guan Ying7, Liu Shuai8, Deng Xiaowu1
1Department of Radiation Oncology,Sun Yat-sen University Cancer Center,State Key Laboratory of Oncology in South China,Collaborative Innovation Center for Cancer Medicine,Guangzhou 510060,China; 2Department of Oncology,The Shunde Hospital of Southern Medical University,Shunde 528300,China; 3Department of Radiation Oncology,Tungwah Hospital of Sun Yat-sen University,Dongguan 523110,China; 4Department of Radiation Oncology,The Fifth Affiliated Hospital of Sun Yat-sen University,Zhuhai 519000,China; 5Department of Radiation Oncology,Affiliated Cancer Hospital of Guangzhou Medical University,Guangzhou 510095,China; 6Department of Radiation Oncology,The First Affiliated Hospital of Sun Yat-sen University,Guangzhou 510080,China; 7Department of Radiation Oncology,Affiliated Cancer Hospital of Guangxi Medical University,Nanning 530021,China; 8Department of Radiation Oncology,The Sixth Affiliated Hospital of Sun Yat-sen University,Guangzhou 510655,China
Objective To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), aiming to provide references for the quality control of multi-center clinical trials. Methods The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the "manual contour group", and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the "auto+manual contour group". The maximum/minimum ratio (MMR) of the PTV and OAR volumes, and the coefficient of variation (CV) for different delineated contours were comparatively evaluated. Results Large variation was observed in the PTV and OAR volumes in the manual contour group. The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39, with the most significant variation in the PTVnd (MMR=3.41 and CV=0.39 for the PTVnd-L). The MMRand CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67. The MMR of the temporal lobe, spinal cord, temporomandibular joint, optic nerve and pituitary gland exceeded 2.0. Compared with the manual contour group, the average contouring time in the auto+ manual group was shortened by 68% and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37. Conclusions Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers. Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation, whereas the variation in the delineation of small organs remains above 1.5 times. The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.
Peng Yinglin,Sun Wenzhao,Cheng Wanqin et al. Interobserver variations in the delineation of planning target volume and with orgagans at risk different contouring methods in intensity-modulated radiation therapy for nasopharyngeal carcinoma[J]. Chinese Journal of Radiation Oncology, 2019, 28(10): 762-766.
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