Abstract：
A kV imager coupled to a novel, ring-gantry radiotherapy system offers improved on-board kV-cone-beam computed tomography (CBCT) acquisition time (17-40 seconds) and image quality, which may improve CT radiotherapy image-guidance and enable online adaptive radiotherapy. We evaluated whether inter-observer contour variability over various anatomic structures was non-inferior using a novel ring gantry kV-CBCT (RG-CBCT) imager as compared to diagnostic-quality simulation CT (simCT).
Seven patients undergoing radiotherapy were imaged with the RG-CBCT system at breath hold (BH) and/or free breathing (FB) for various disease sites on a prospective imaging study. Anatomy was independently contoured by seven radiation oncologists on: 1. SimCT 2. Standard C-arm kV-CBCT (CA-CBCT), and 3. Novel RG-CBCT at FB and BH. Inter-observer contour variability was evaluated by computing simultaneous truth and performance level estimation (STAPLE) consensus contours, then computing average symmetric surface distance (ASSD) and Dice similarity coefficient (DSC) between individual raters and consensus contours for comparison across image types.
Across 7 patients, 18 organs-at-risk (OARs) were evaluated on 27 image sets. Both BH and FB RG-CBCT were non-inferior to simCT for inter-observer delineation variability across all OARs and patients by ASSD analysis (p < 0.001), whereas CA-CBCT was not (p = 0.923). RG-CBCT (FB and BH) also remained non-inferior for abdomen and breast subsites compared to simCT on ASSD analysis (p < 0.025). On DSC comparison, neither RG-CBCT nor CA-CBCT were non-inferior to simCT for all sites (p > 0.025).
Inter-observer ability to delineate OARs using novel RG-CBCT images was non-inferior to simCT by the ASSD criterion but not DSC criterion.
Seven patients undergoing radiotherapy were imaged with the RG-CBCT system at breath hold (BH) and/or free breathing (FB) for various disease sites on a prospective imaging study. Anatomy was independently contoured by seven radiation oncologists on: 1. SimCT 2. Standard C-arm kV-CBCT (CA-CBCT), and 3. Novel RG-CBCT at FB and BH. Inter-observer contour variability was evaluated by computing simultaneous truth and performance level estimation (STAPLE) consensus contours, then computing average symmetric surface distance (ASSD) and Dice similarity coefficient (DSC) between individual raters and consensus contours for comparison across image types.
Across 7 patients, 18 organs-at-risk (OARs) were evaluated on 27 image sets. Both BH and FB RG-CBCT were non-inferior to simCT for inter-observer delineation variability across all OARs and patients by ASSD analysis (p < 0.001), whereas CA-CBCT was not (p = 0.923). RG-CBCT (FB and BH) also remained non-inferior for abdomen and breast subsites compared to simCT on ASSD analysis (p < 0.025). On DSC comparison, neither RG-CBCT nor CA-CBCT were non-inferior to simCT for all sites (p > 0.025).
Inter-observer ability to delineate OARs using novel RG-CBCT images was non-inferior to simCT by the ASSD criterion but not DSC criterion.
摘要：
背景：耦合到新颖的kV成像仪，环形龙门放射治疗系统提供改进的机载kV锥形束计算机断层扫描（CBCT）采集时间（17-40秒）和图像质量，这可以改善CT放射治疗的图像指导，并使在线自适应放射治疗。与诊断质量模拟CT（simCT）相比，我们使用新型环形机架kV-CBCT（RG-CBCT）成像仪评估了各种解剖结构的观察者间轮廓变异性是否不差。
方法：在一项前瞻性影像学研究中，对7例接受放疗的患者在屏气（BH）和/或自由呼吸（FB）下进行RG-CBCT成像。七位放射肿瘤学家对解剖学进行了独立的轮廓分析：1。SimCT2。标准C型臂kV-CBCT(CA-CBCT),and3.在FB和BH的新型RG-CBCT。通过计算同时的真值和性能水平估计（STAPLE）共识轮廓来评估观察者之间的轮廓变异性，然后计算各个评估者和共识轮廓之间的平均对称表面距离（ASSD）和Dice相似性系数（DSC），以便在图像类型之间进行比较。
结果：在7名患者中，在27个图像集上评估了18个危险器官（OAR）。通过ASSD分析，BH和FBRG-CBCT在所有OAR和患者的观察者间描绘变异性方面均不劣于simCT（p<0.001），而CA-CBCT没有（p=0.923）。与ASSD分析中的simCT相比，RG-CBCT（FB和BH）在腹部和乳房亚部位也保持不下方（p<0.025）。在DSC比较中，所有部位的RG-CBCT和CA-CBCT均不劣于simCT(p>0.025)。
结论：根据ASSD标准而不是DSC标准，观察者间使用新型RG-CBCT图像描绘OAR的能力不劣于simCT。
方法：在一项前瞻性影像学研究中，对7例接受放疗的患者在屏气（BH）和/或自由呼吸（FB）下进行RG-CBCT成像。七位放射肿瘤学家对解剖学进行了独立的轮廓分析：1。SimCT2。标准C型臂kV-CBCT(CA-CBCT),and3.在FB和BH的新型RG-CBCT。通过计算同时的真值和性能水平估计（STAPLE）共识轮廓来评估观察者之间的轮廓变异性，然后计算各个评估者和共识轮廓之间的平均对称表面距离（ASSD）和Dice相似性系数（DSC），以便在图像类型之间进行比较。
结果：在7名患者中，在27个图像集上评估了18个危险器官（OAR）。通过ASSD分析，BH和FBRG-CBCT在所有OAR和患者的观察者间描绘变异性方面均不劣于simCT（p<0.001），而CA-CBCT没有（p=0.923）。与ASSD分析中的simCT相比，RG-CBCT（FB和BH）在腹部和乳房亚部位也保持不下方（p<0.025）。在DSC比较中，所有部位的RG-CBCT和CA-CBCT均不劣于simCT(p>0.025)。
结论：根据ASSD标准而不是DSC标准，观察者间使用新型RG-CBCT图像描绘OAR的能力不劣于simCT。
