Tao C.-J.Yi J.-L.Chen N.-Y.Ren W.CHIA-HSIEN CHENGTung S.Kong L.Lin S.-J.Pan J.-J.Zhang G.-S.Hu J.Qi Z.-Y.Ma J.Lu J.-D.Yan D.Sun Y.2020-04-272020-04-2720150167-8140https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946398054&doi=10.1016%2fj.radonc.2015.05.012&partnerID=40&md5=43c8decb0e6deb672a726d7d02b59d02https://scholars.lib.ntu.edu.tw/handle/123456789/485666Background and purpose 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). Materials and 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%, 2.2-5.0 mm for manual contouring and 0.42-0.86, 7.2-70.6%, 1.2-3.5 mm for edited ABAS contouring, respectively; range of dose CV reduction: 1.0-3.0%). Conclusion 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. ? 2015 Elsevier Ireland Ltd.Atlas-based auto segmentation (ABAS); Contour variation; Dosimetric parameter; Nasopharyngeal carcinoma; Organs at risk[SDGs]SDG3antineoplastic metal complex; Article; atlas based autosegmentation; brain stem; clinical article; cochlea; cone beam computed tomography; consensus; dosimetry; human; intensity modulated radiation therapy; larynx; mandible; multicenter study; nasopharynx carcinoma; nerve; optic chiasm; optic nerve; organs at risk; parotid gland; pharyngeal constrictor muscle; pharyngeal muscle; practice guideline; priority journal; radiation dose reduction; radiological procedures; radiotherapy planning system; spinal cord; temporal lobe; temporomandibular joint; three dimensional imaging; cancer staging; clinical trial; computer assisted radiotherapy; first cervical vertebra; Nasopharyngeal Neoplasms; observer variation; organs at risk; pathology; procedures; radiography; radiometry; Brain Stem; Cervical Atlas; Humans; Nasopharyngeal Neoplasms; Neoplasm Staging; Observer Variation; Organs at Risk; Radiometry; Radiotherapy Planning, Computer-Assisted; Spinal Cordjournal article10.1016/j.radonc.2015.05.012260255462-s2.0-84946398054