Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing, 100021, China.
Radiat Oncol. 2022 Feb 3;17(1):22. doi: 10.1186/s13014-022-01996-6.
Respiratory motion may introduce errors during radiotherapy. This study aims to assess and validate internal gross tumour volume (IGTV) margins in proximal and distal borders of gastroesophageal junction (GEJ) tumours during simultaneous integrated boost radiotherapy.
We enrolled 10 patients in group A and 9 patients in group B. For all patients, two markers were placed at the upper and lower borders of the tumour before treatment. In group A, within the simulation and every 5 fractions of radiotherapy, we used 4-dimensional computed tomography (4DCT) to record the intrafractional displacement of the proximal and distal markers. By fusing the average image of each repeated 4DCT with the simulation image based on the lumbar vertebra, the interfractional displacement could be obtained. We calculated the IGTV margin in the proximal and distal borders of the GEJ tumour. In group B, by referring to the simulation images and cone-beam computed tomography (CBCT) images, the range of tumour displacement in proximal and distal borders of GEJ tumour was estimated. We calculated the proportion of marker displacement range in group B lay within the IGTV margin calculated based on the data obtained in group A to estimate the accuracy of the IGTV margin.
The intrafractional displacement in the cranial-caudal (CC) direction was significantly larger than that in the anterior-posterior (AP) and left-right (LR) directions for both the proximal and distal markers of the tumour. The interfractional displacement in the AP and LR directions was larger than that in the CC direction (p = 0.001, p = 0.017) based on the distal marker. The IGTV margins in the LR, AP and CC directions were 9 mm, 8.5 mm and 12.1 mm for the proximal marker and 15.8 mm, 12.7 mm and 11.5 mm for the distal marker, respectively. In group B, the proportions of markers that located within the IGTV margin in the LR, AP and CC directions were 96.5%, 91.3% and 96.5% for the proximal marker and 100%, 96.5%, 93.1% for the distal marker, respectively.
Our study proposed individualized IGTV margins for proximal and distal borders of GEJ tumours during neoadjuvant radiotherapy. The IGTV margin determined in this study was acceptable. This margin could be a reference in clinical practice.
放疗过程中的呼吸运动会引入误差。本研究旨在评估并验证胃食管结合部（GEJ）肿瘤同步整合推量放疗中近端和远端边界的内部大体肿瘤体积（IGTV）边界。
我们纳入了 A 组的 10 例患者和 B 组的 9 例患者。所有患者在治疗前于肿瘤的上下边界放置两个标记物。在 A 组中，在模拟和每次 5 个分次放疗期间，我们使用 4 维 CT（4DCT）记录近端和远端标记物的分次内位移。通过将每个重复的 4DCT 的平均图像与基于腰椎的模拟图像融合，我们可以获得分次间的位移。我们计算了 GEJ 肿瘤近端和远端边界的 IGTV 边界。在 B 组中，我们参考模拟图像和锥形束 CT（CBCT）图像，估计 GEJ 肿瘤近端和远端边界的肿瘤位移范围。我们计算 B 组中标记物位移范围在基于 A 组数据计算的 IGTV 边界内的比例，以估计 IGTV 边界的准确性。
肿瘤近端和远端标记物的头脚（CC）方向的分次内位移明显大于前后（AP）和左右（LR）方向。基于远端标记物，AP 和 LR 方向的分次间位移大于 CC 方向（p=0.001，p=0.017）。近端标记物在 LR、AP 和 CC 方向的 IGTV 边界分别为 9mm、8.5mm 和 12.1mm，远端标记物分别为 15.8mm、12.7mm 和 11.5mm。在 B 组中，近端标记物在 LR、AP 和 CC 方向位于 IGTV 边界内的标记物比例分别为 96.5%、91.3%和 96.5%，远端标记物分别为 100%、96.5%和 93.1%。
我们的研究为新辅助放疗中胃食管结合部肿瘤的近端和远端边界提出了个体化的 IGTV 边界。本研究确定的 IGTV 边界是可接受的。这一边界可以作为临床实践的参考。
