Alfred Health Radiation Oncology, The Alfred, 55 Commercial Road, Melbourne, VIC, 3004, Australia.
Department of Surgery, Central Clinical School, Monash University, Melbourne, VIC, Australia.
Radiat Oncol. 2021 Nov 14;16(1):218. doi: 10.1186/s13014-021-01946-8.
To determine the optimal volume of barium for oesophageal localisation on cone-beam CT (CBCT) for locally-advanced non-small cell lung cancers (NSCLC) and quantify the interfraction oesophageal movement relative to tumour.
Twenty NSCLC patients with mediastinal and/or hilar disease receiving radical radiotherapy were recruited. The first five patients received 25 ml of barium prior to their planning CT and alternate CBCTs during treatment. Subsequent five patient cohorts, received 15 ml, 10 ml and 5 ml. Six observers contoured the oesophagus on each of the 107 datasets and consensus contours were created. Overall 642 observer contours were generated and interobserver contouring reproducibility was assessed. The kappa statistic, dice coefficient and Hausdorff Distance (HD) were used to compare barium-enhanced CBCTs and non-enhanced CBCTs. Oesophageal displacement was assessed using the HD between consensus contours of barium-enhanced CBCTs and planning CTs.
Interobserver contouring reproducibility was significantly improved in barium-enhanced CBCTs compared to non-contrast CBCTs with minimal difference between barium dose levels. Only 10 mL produced a significantly higher kappa (0.814, p = 0.008) and dice (0.895, p = 0.001). The poorer the reproducibility without barium, the greater the improvement barium provided. The median interfraction HD between consensus contours was 4 mm, with 95% of the oesophageal displacement within 15 mm.
10 mL of barium significantly improves oesophageal localisation on CBCT with minimal image artifact. The oesophagus moves substantially and unpredictably over a course of treatment, requiring close daily monitoring in the context of hypofractionation.
为了确定在锥形束 CT（CBCT）上对局部晚期非小细胞肺癌（NSCLC）进行食管定位的最佳钡剂体积，并定量测量肿瘤相对的食管分次运动。
共招募了 20 名纵隔和/或肺门疾病接受根治性放疗的 NSCLC 患者。前 5 名患者在其计划 CT 前和治疗过程中的交替 CBCT 中接受了 25ml 钡剂。随后的 5 名患者分别接受了 15ml、10ml 和 5ml 钡剂。6 位观察者在 107 组数据集中的每一组中勾画食管，并创建了共识轮廓。共生成了 642 个观察者轮廓，并评估了观察者间轮廓的可重复性。使用 Kappa 统计、骰子系数和 Hausdorff 距离（HD）比较钡增强 CBCT 和非增强 CBCT。使用 HD 评估钡增强 CBCT 与计划 CT 之间的食管位移。
与非对比 CBCT 相比，钡增强 CBCT 的观察者间轮廓可重复性显著提高，而钡剂量水平之间的差异最小。只有 10ml 产生了更高的 Kappa（0.814，p=0.008）和骰子系数（0.895，p=0.001）。没有钡剂时的可重复性越差，钡剂提供的改善就越大。共识轮廓之间的中位数分次 HD 为 4mm，95%的食管位移在 15mm 以内。
10ml 钡剂可显著提高 CBCT 上的食管定位，且图像伪影最小。食管在治疗过程中会发生大量且不可预测的移动，在分次治疗的情况下需要密切的每日监测。
