Department of Radiation Oncology, The Netherlands Cancer Institute/Antoni van Leeuwenhoekhuis, Amsterdam, The Netherlands.
Radiat Oncol. 2010 Mar 15;5:21. doi: 10.1186/1748-717X-5-21.
To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation.
For ten nasopharyngeal cancer patients, ten observers each delineated the Clinical Target Volume (CTV) and the CTV elective. After 3D analysis of the delineated volumes, a second delineation was performed. This implied improved delineation instructions, a combined delineation on CT and co-registered MRI, forced use of sagittal reconstructions, and an on-line anatomical atlas.
Both for the CTV and the CTV elective delineations, the 3D SD decreased from Phase 1 to Phase 2, from 4.4 to 3.3 mm for the CTV and from 5.9 to 4.9 mm for the elective. There was an increase agreement, where the observers intended to delineate the same structure, from 36 to 64 surface % (p = 0.003) for the CTV and from 17 to 59% (p = 0.004) for the elective. The largest variations were at the caudal border of the delineations but these were smaller when an observer utilized the sagittal window. Hence, the use of sagittal side windows was enforced in the second phase and resulted in a decreased standard deviation for this area from 7.7 to 3.3 mm (p = 0.001) for the CTV and 7.9 to 5.6 mm (p = 0.03) for the CTV elective.
Attempts to decrease the variation need to be tailored to the specific causes of the variation. Use of delineation instructions multimodality imaging, the use of sagittal windows and an on-line atlas result in a higher agreement on the intended target.
确定鼻咽癌靶区勾画的变化，并探讨减少这种变化的措施。
对 10 例鼻咽癌患者，10 名观察者分别对临床靶区（CTV）和CTV 选择性勾画。在对勾画体积进行 3D 分析后，进行第二次勾画。这意味着改进了勾画指导，在 CT 和配准的 MRI 上联合勾画，强制使用矢状位重建，并使用在线解剖图谱。
无论是 CTV 还是 CTV 选择性勾画，3D 标准差都从第 1 阶段到第 2 阶段降低，CTV 从 4.4 降至 3.3mm，CTV 选择性从 5.9 降至 4.9mm。观察者对同一结构的勾画意向一致性增加，CTV 从 36%增加到 64%（p=0.003），CTV 选择性从 17%增加到 59%（p=0.004）。勾画的最下部边界变化最大，但当观察者使用矢状位窗时，这些变化较小。因此，在第 2 阶段强制使用矢状位侧窗，使 CTV 和 CTV 选择性的该区域标准差从 7.7 降至 3.3mm（p=0.001）和 7.9 降至 5.6mm（p=0.03）。
减少变化的尝试需要针对变化的具体原因进行定制。使用勾画指导、多模态成像、矢状位窗和在线图谱可以提高目标勾画的一致性。
