Ayyalusamy Anantharaman, Vellaiyan Subramani, Subramanian Shanmuga, Ilamurugu Arivarasan, Satpathy Shyama, Nauman Mohammed, Katta Gowtham, Madineni Aneesha
Department of Radiation Oncology, Yashoda Hospitals, Hyderabad, India.
All India Institute of Medical Sciences, New Delhi, India.
Radiat Oncol J. 2019 Jun;37(2):134-142. doi: 10.3857/roj.2019.00038. Epub 2019 Jun 30.
The aim is to study the dependence of deformable based auto-segmentation of head and neck organs-at-risks (OAR) on anatomy matching for a single atlas based system and generate an acceptable set of contours.
A sample of ten patients in neutral neck position and three atlas sets consisting of ten patients each in different head and neck positions were utilized to generate three scenarios representing poor, average and perfect anatomy matching respectively and auto-segmentation was carried out for each scenario. Brainstem, larynx, mandible, cervical oesophagus, oral cavity, pharyngeal muscles, parotids, spinal cord, and trachea were the structures selected for the study. Automatic and oncologist reference contours were compared using the dice similarity index (DSI), Hausdroff distance and variation in the centre of mass (COM).
The mean DSI scores for brainstem was good irrespective of the anatomy matching scenarios. The scores for mandible, oral cavity, larynx, parotids, spinal cord, and trachea were unacceptable with poor matching but improved with enhanced bony matching whereas cervical oesophagus and pharyngeal muscles had less than acceptable scores for even perfect matching scenario. HD value and variation in COM decreased with better matching for all the structures.
Improved anatomy matching resulted in better segmentation. At least a similar setup can help generate an acceptable set of automatic contours in systems employing single atlas method. Automatic contours from average matching scenario were acceptable for most structures. Importance should be given to head and neck position during atlas generation for a single atlas based system.
旨在研究基于可变形的头颈部危及器官（OAR）自动分割对单图谱系统中解剖匹配的依赖性，并生成一组可接受的轮廓。
使用10例处于颈部中立位的患者样本以及3组图谱集（每组由10例处于不同头颈部位置的患者组成），分别生成代表解剖匹配差、一般和完美的三种情况，并对每种情况进行自动分割。研究选取的结构包括脑干、喉、下颌骨、颈段食管、口腔、咽肌、腮腺、脊髓和气管。使用骰子相似性指数（DSI）、豪斯多夫距离和质心（COM）变化比较自动轮廓和肿瘤学家参考轮廓。
无论解剖匹配情况如何，脑干的平均DSI分数都较好。下颌骨、口腔、喉、腮腺、脊髓和气管的分数在匹配差时不可接受，但随着骨匹配的增强而改善，而即使在完美匹配情况下，颈段食管和咽肌的分数也低于可接受水平。所有结构的HD值和COM变化随着匹配度的提高而降低。
改善解剖匹配可实现更好的分割。至少类似的设置有助于在采用单图谱方法的系统中生成一组可接受的自动轮廓。大多数结构的平均匹配情况下的自动轮廓是可接受的。对于基于单图谱的系统，在生成图谱时应重视头颈部位置。
