Department of Oncology, Laboratory of Radiation Physics, Odense University Hospital, Odense C, Denmark.
Department of Clinical Research, University of Southern Denmark, Odense, Denmark.
Acta Oncol. 2021 Nov;60(11):1407-1412. doi: 10.1080/0284186X.2021.1949036. Epub 2021 Jul 10.
The aim is to quantify and analyse tumour motion during a course of treatment for lung SBRT patients.
Peak-to-peak motion of 483 tumours in 441 patients treated with peripheral lung SBRT at a single institution over a two year period was measured on planning CT and at all treatment fractions. Planning 4D-CT scans were analysed using our clinical workflow involving deformable propagation of the delineated target to all phases. Similarly, acquisition of the 4D-CBCT data followed the clinical workflow based on XVI 5.0 available on Elekta linacs. Differences and correlations of the peak-to-peak motion on the planning CT and at treatment were analysed.
On the planning CT, a total of 81.4% of the tumours had a peak-to-peak motion <10 mm, and 96.1% had <20 mm. The largest motion was observed in the CC direction, with largest amplitude for tumours located in the caudal posterior part of the lung. The difference in amplitude in CC between planning CT and first fraction had a mean and standard deviation of 0.3 mm and 3.5 mm, respectively, and the largest differences were observed in the caudal posterior part of the lung. Patients with a difference in tumour motion amplitude exceeding two standard deviations (>7 mm) at the first fraction were evaluated individually, and they all had poor 4DCT image quality. The difference between the first and second/third fractions had a mean and standard deviation of 0.4 mm/0.5 mm and 2.0 mm/1.9 mm.
Tumour motion at first treatment was similar to motion at planning, and motion at subsequent treatments was very similar to motion at first treatment. Large tumour motions are located towards the caudal posterior tumour locations. Patients with poor 4D-CT image quality should be closely followed at the first treatment to verify the motion.
本研究旨在定量分析肺部 SBRT 患者在整个疗程中的肿瘤运动情况。
在一家机构对两年间接受肺部 SBRT 治疗的 441 例 483 个肿瘤患者的计划 CT 及各分次治疗时的肿瘤运动幅度进行测量。使用勾画靶区的形变传播，分析纳入了本临床工作流程的计划 4D-CT 扫描。同样，根据 Elekta 直线加速器上的 XVI 5.0 临床工作流程采集 4D-CBCT 数据。分析计划 CT 与治疗时肿瘤的峰峰值运动的差异和相关性。
在计划 CT 上，81.4%的肿瘤峰峰值运动<10mm，96.1%的肿瘤峰峰值运动<20mm。肿瘤运动幅度最大的方向是 CC 方向，且位于肺后下部的肿瘤运动幅度最大。计划 CT 与首次分次治疗之间 CC 方向的肿瘤运动幅度差异平均值和标准差分别为 0.3mm 和 3.5mm，最大差异见于肺后下部。首次分次治疗的肿瘤运动幅度差值超过两个标准差（>7mm）的患者需要单独评估，他们的 4DCT 图像质量均较差。首次分次与第二次/第三次分次之间的差异平均值和标准差分别为 0.4mm/0.5mm 和 2.0mm/1.9mm。
首次治疗时的肿瘤运动与计划时相似，后续治疗时的肿瘤运动与首次治疗时相似。较大的肿瘤运动主要位于肺后下部。4DCT 图像质量较差的患者应在首次治疗时密切关注，以验证肿瘤运动情况。
