title: Multi-subject atlas-based auto-segmentation reduces interobserver variation and improves dosimetric parameter consistency for organs at risk in nasopharyngeal carcinoma: A multi-institution clinical study.
abstract: OBJECTIVE
  To assess whether consensus guideline-based atlas-based auto-segmentation (ABAS) reduces interobserver variation and improves dosimetric parameter consistency for organs at risk (OARs) in nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Eight radiation oncologists from 8 institutes contoured 20 OARs on planning CT images of 16 patients via manual contouring and manually-edited ABAS contouring. Interobserver variation [volume coefficient of variation (CV), Dice similarity coefficient (DSC), three-dimensional isocenter difference (3D-ICD)] and dosimetric parameters were compared between the two methods of contouring for each OAR.
  
  
  RESULTS
  Interobserver variation was significant for all OARs in manual contouring, resulting in significant dosimetric parameter variation (P<0.05). Edited ABAS significantly improved multiple metrics and reduced dosimetric parameter variation for most OARs; brainstem, spinal cord, cochleae, temporomandibular joint (TMJ), larynx and pharyngeal constrictor muscle (PCM) obtained most benefit (range of mean DSC, volume CV and main ICD values was 0.36-0.83, 12.1-84.3%, 2.2-5.0mm for manual contouring and 0.42-0.86, 7.2-70.6%, 1.2-3.5mm for edited ABAS contouring, respectively; range of dose CV reduction: 1.0-3.0%).
  
  
  CONCLUSIONS
  Substantial objective interobserver differences occur during manual contouring, resulting in significant dosimetric parameter variation. Edited ABAS reduced interobserver variation and improved dosimetric parameter consistency, particularly for brainstem, spinal cord, cochleae, TMJ, larynx and PCM.
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Chang-Juan
authors.initials: CJ
authors.lastname: Tao
authors.affiliation: Department of Radiation Oncology, Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China.
authors.forename: Jun-Lin
authors.initials: JL
authors.lastname: Yi
authors.affiliation: Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Nian-Yong
authors.initials: NY
authors.lastname: Chen
authors.affiliation: Department of Radiation Oncology, National University Cancer Institute, National University Health System, National University of Singapore, Republic of Singapore.
authors.forename: Wei
authors.initials: W
authors.lastname: Ren
authors.affiliation: Department of Radiation Oncology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Jason
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Clinical Oncology, Tuen Mun Hospital, Hong Kong, China.
authors.forename: Stewart
authors.initials: S
authors.lastname: Tung
authors.affiliation: Department of Radiation Oncology, Fudan University, Shanghai Cancer Center, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Kong
authors.affiliation: Department of Radiation Oncology, Cancer Hospital of Fujian Medical University, Fuzhou, China.
authors.forename: Shao-Jun
authors.initials: SJ
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, Cancer Hospital of Fujian Medical University, Fuzhou, China.
authors.forename: Jian-Ji
authors.initials: JJ
authors.lastname: Pan
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Guang-Shun
authors.initials: GS
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Qi
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Radiation Oncology, National University Cancer Institute, National University Health System, National University of Singapore, Republic of Singapore.
authors.forename: Jia-De
authors.initials: JD
authors.lastname: Lu
authors.affiliation: Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, United States.
authors.forename: Di
authors.initials: D
authors.lastname: Yan
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China. Electronic address: sunying@sysucc.org.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
mesh_terms: D001933:Brain Stem / Q000000981:diagnostic imaging; D002277:Carcinoma; D001270:Cervical Atlas; D006801:Humans; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D009367:Neoplasm Staging; D015588:Observer Variation; D058958:Organs at Risk; D011859:Radiography; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D013116:Spinal Cord / Q000000981:diagnostic imaging
keywords: Atlas-based auto segmentation (ABAS); Contour variation; Dosimetric parameter; Nasopharyngeal carcinoma; Organs at risk