Interobserver variations in the delineation of target volumes and organs at risk and their impact on dose distribution in intensity-modulated radiation therapy for nasopharyngeal carcinoma. (July 2018)

• Record Type: Journal Article
• Authors: Peng, Ying-lin; Chen, Li; Shen, Guan-zhu; Li, Ya-ning; Yao, Ji-jin; Xiao, Wei-wei; Yang, Lin; Zhou, Shu; Li, Jia-xin; Cheng, Wan-qin; Guan, Ying; Xia, Hai-qun; Liu, Shuai; Zhao, Chong; Deng, Xiao-wu
• Is Part Of: Oral oncology. Volume 82(2018)
• Page Start: 1
• Page End: 7
• Publication Date: 2018-07
• Subjects: Interobserver variations in delineation -- Planning target volume -- Organs at risk -- Nasopharyngeal carcinoma -- Intensity-modulated radiation therapy; ABAS atlas-based automatic segmentation -- CV coefficient of variation -- MMR maximum/minimum ratio -- PDC prescription dose coverage -- STAPLE simultaneous truth and performance level estimation -- NPC nasopharyngeal carcinoma -- TPS treatment planning system; Mouth -- Cancer -- Periodicals; Mouth -- Tumors -- Periodicals; Mouth Diseases -- Periodicals; Mouth Neoplasms -- Periodicals; Bouche -- Cancer -- Périodiques; Bouche -- Tumeurs -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9943105
• DOI: 10.1016/j.oraloncology.2018.04.025
• Languages: English
• ISSNs: 1368-8375

Abstract

Highlights: Variations exist in the delineation of tumor volumes by different physicians. Delineations of small organs by different physicians were significantly different. Whereas delineations of larger organs were not significantly different. Significant dosimetry deviation may be caused by interobserver variation in delineation. Abstract: Objective: This study aimed to (a) assess the differences in the delineation of target volumes and organs-at-risk (OARs) by different physicians designing an intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and (b) analyze the impact of these differences on the treatment plan optimization. Materials and methods: The planning target volumes (PTVs) and OARs for radiotherapy were manually delineated from computed tomography images of a patient with NPC, and a standard delineation was determined using the STAPLE algorithm of ABAS software. IMRT was designed using one standard plan and 10 individual plans based on the same constraints and field conditions. The maximum/minimum ratio (MMR) of the PTV and OAR volumes and the coefficient of variation (CV) for the different groups were evaluated and compared to the volume of the standard contour. Results: Significant differences were seen in the PTVs of the nasopharynx (PTVnx ), neck lymph node (PTVnd ) and the OARs manually delineated by different physicians. Compared to the standard plan, the mean dose-related parameters of various OARs in different individual plans were not significantly different, while that of most organs in different individual plans were reduced. However, a significant difference in the dose at each organ was noted in different individual plans. Conclusion: Significant differences were noted in the PTV and OAR delineations by different physicians in radiotherapy of NPC, and their dosimetric parameters were significantly different from the standard planned parameters. Therefore, multicenter trials should pay attention to the impact of these differences on the clinical evaluation.