Department of Radiotherapy, Military Institute of Medicine, Warsaw, Poland; Department of Radiotherapy, Regional Oncology Centre, Czestochowa, Poland.
Department of Radiotherapy, Medical Physics Unit, Military Institute of Medicine, Warsaw, Poland.
Radiother Oncol. 2022 Feb;167:261-268. doi: 10.1016/j.radonc.2021.12.041. Epub 2022 Jan 3.
A detailed contouring atlas of the heart valves is lacking. Existing heart contouring atlases have not been evaluated on average intensity projection four-dimensional non-contrast computed tomography (AVE-4D-CT) scans, routinely used for organ-at-risk delineation in lung cancer radiotherapy. We aimed to develop the heart valve contouring atlas and to assess inter-observer variation in delineation of the heart, its substructures, and coronary arteries on AVE-4D-CT scans, along with its impact on radiotherapy doses.
A heart valve contouring atlas was developed. Five radiation oncologists and four cardiologists delineated the valves according to this atlas, and the remaining heart substructures according to the existing atlases, on AVE-4D-CT scans of ten patients who underwent radio(chemo)therapy for NSCLC. The observer contours were then compared to the collectively defined "reference" contours. Spatial variation was assessed using the Sørensen-Dice similarity coefficient (DSC), directed average Hausdorff distance (DAH), directed Hausdorff distance (HD), and the mean distance to agreement (MDA). The effect of spatial variation on radiotherapy doses was assessed using the patients' treatment plans.
Inter-observer contour overlap (mean DSC) was 0.68, 0.49, 0.45 and 0.45, and inter-observer contour separation (mean DAH) was 2.1, 3.4, 2.6 and 2.9 mm for the pulmonic (PV), aortic (AV), mitral (MV) and tricuspid valve (TV), respectively. Mean HD was higher for TV and MV (13.3 and 11.7 mm) than for AV and PV (7.8 and 7 mm). The highest mean MDA of 3.1 mm was found for AV, and the lowest (1.9 mm) for PV. Inter-observer agreement was the lowest for the coronary arteries, but statistically significant dose variation was found mainly in the left ventricular septal and anterior segments.
Our atlas enables reproducible delineation of the heart valves. Delineation of the heart and its substructures on AVE-4D-CT scans is feasible, with inter-observer variability similar to that reported on conventional non-contrast CT scans.
目前尚缺乏详细的心脏瓣膜轮廓图谱。现有的心脏轮廓图谱尚未在平均强度投影四维非对比 CT（AVE-4D-CT）扫描上进行评估，而 AVE-4D-CT 扫描通常用于肺癌放射治疗中的危及器官勾画。我们旨在开发心脏瓣膜轮廓图谱，并评估在 AVE-4D-CT 扫描上勾画心脏、其亚结构和冠状动脉的观察者间变异性，以及其对放射治疗剂量的影响。
开发了心脏瓣膜轮廓图谱。五位放射肿瘤学家和四位心脏病专家根据该图谱以及现有的图谱在十位接受 NSCLC 放化疗的患者的 AVE-4D-CT 扫描上勾画了瓣膜和其他心脏亚结构。然后将观察者轮廓与集体定义的“参考”轮廓进行比较。使用 Sørensen-Dice 相似系数（DSC）、有向平均 Hausdorff 距离（DAH）、有向 Hausdorff 距离（HD）和平均一致性距离（MDA）评估空间变异性。使用患者的治疗计划评估空间变异性对放射治疗剂量的影响。
观察者间轮廓重叠（平均 DSC）分别为 0.68、0.49、0.45 和 0.45，观察者间轮廓分离（平均 DAH）分别为 2.1、3.4、2.6 和 2.9 毫米，用于肺动脉瓣（PV）、主动脉瓣（AV）、二尖瓣（MV）和三尖瓣（TV）。TV 和 MV 的平均 HD 较高（分别为 13.3 和 11.7 毫米），而 AV 和 PV 的平均 HD 较低（分别为 7.8 和 7 毫米）。AV 的平均 MDA 最高（3.1 毫米），而 PV 的平均 MDA 最低（1.9 毫米）。观察者间一致性最低的是冠状动脉，但主要在左心室间隔和前节段发现了有统计学意义的剂量变化。
我们的图谱能够实现心脏瓣膜的可重复性勾画。在 AVE-4D-CT 扫描上勾画心脏及其亚结构是可行的，观察者间变异性与传统非对比 CT 扫描报道的相似。
