ESTRO 2025 - Abstract Book

S1034

Clinical – Head & neck

ESTRO 2025

References:

1. NWO TRAIN . Available from: https://www.nwo.nl/en/projects/629002212. 2. Wilkinson, M.D., et al., The FAIR Guiding Principles for scientific data management and stewardship. Scientific Data 2016 3:1, 2016-03-15. 3 (1). 3. Personal Health Train . Available from: https://www.dtls.nl/fair-data/personal-health-train/. 4. vantage6 . Available from: https://distributedlearning.ai/.

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Digital Poster The morphological and dosimetric changes of target volumes and organs at risk during radiotherapy for nasopharyngeal carcinoma Xiao-li Yu 1,2 , Jiang Hu 1 , Yu-xian Yang 3 , Guang-yu Wang 1 , Xin Yang 1 , Wen-chao Diao 1 , Lu Liu 1 , Xiao-bo Jiang 1 , Chen-di Xu 1 , Liu-wen Lin 1 , Le-cheng Jia 4 , Hua Li 4 , Yan-fei Liu 4 , Ying Sun 1 , Guan-qun Zhou 1 1 Radiation Oncology, Sun Yat-Sen University Cancer Center and State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China. 2 Radiation Oncology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangzhou, China. 3 Radiation Oncology, un Yat-Sen University Cancer Center and State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China. 4 Research cooperation department, Shenzhen United Imaging Research Institute of Innovative Medical Equipment, Shenzhen, China Purpose/Objective: This study aims to retrospectively analyze the morphological and dosimetric changes of all target volumes and organs at risk (OARs) in nasopharyngeal carcinoma (NPC) radiotherapy, hoping to assist in the timing decision making of adaptive radiotherapy. Material/Methods: NPC patients treated at Sun Yat-sen Cancer Center between August 2022 and May 2024 were retrospectively collected. We included those performed fan beam CT (FBCT) scanning at least once a week, and the interval between two FBCT scannings should not exceed two radiotherapy fractions. We analyzed the weekly volume, dice similarity coefficient (DSC) and dosimetric parameters changes for the OARs and target volumes. Considering the inter-fractional delineation and positioning error, only when the percentage difference of volume or DSC for a structure in week 1-7 ≥ 2.5%, would we further analyzed its change trend.