Ding Shouliang, Liu Biaoshui, Zheng Shiyang, Wang Daquan, Liu Mingzhi, Liu Hongdong, Zhang Pengxin, Peng Kangqiang, He Haoqiang, Zhou Rui, Guo Jinyu, Qiu Bo, Huang Xiaoyan, Liu Hui
Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Sun Yat‑sen University Cancer Center, Guangzhou, China.
Department of Radiology, State Key Laboratory of Oncology in South China, Sun Yat‑sen University Cancer Center, Guangzhou, China.
Clin Transl Radiat Oncol. 2023 Feb 23;40:100602. doi: 10.1016/j.ctro.2023.100602. eCollection 2023 May.
To assess the feasibility and potential benefits of online adaptive MR-guided fractionated stereotatic radiotherapy (FSRT) in patients with brain metastases (BMs).
Twenty-eight consecutive patients with BMs were treated with FSRT of 30 Gy in 5 fractions on the 1.5 T MR-Linac. The FSRT fractions employed daily MR scans and the contours were utilized to create each adapted plan. The brain lesions and perilesional edema were delineated on MR images of pre-treatment simulation (Fx0) and all fractions (Fx1, Fx2, Fx3, Fx4 and Fx5) to evaluate the inter-fractional changes. These changes were quantified using absolute/relative volume, Dice similarity coefficient (DSC) and Hausdorff distance (HD) metrics. Planning target volume (PTV) coverage and organ at risk (OAR) constraints were used to compare non-adaptive and adaptive plans.
A total of 28 patients with 88 lesions were evaluated, and 23 patients (23/28, 82.1%) had primary lung adenocarcinoma. Significant tumor volume reduction had been found during FSRT compared to Fx0 for all 88 lesions (median -0.75%, -5.33%, -9.32%, -17.96% and -27.73% at Fx1, Fx2, Fx3, Fx4 and Fx5, < 0.05). There were 47 (47/88, 53.4%) lesions being accompanied by perilesional edema and the inter-fractional changes were significantly different compared to those without perilesional edema ( < 0.001). Patients with multiple lesions (13/28, 46.4%) had more significant inter-fractional tumor changes than those with single lesion (15/28, 53.6%), including tumor volume reduction and anatomical shift ( < 0.001). PTV coverage of non-adaptive plans was below the prescribed coverage in 26/140 fractions (19%), with 12 (9%) failing by more than 10%. All 140 adaptive fractions met prescribed target coverage. The adaptive plans also had lower dose to whole brain than non-adaptive plans ( < 0.001).
Significant inter-fractional tumor changes could be found during FSRT in patients with BMs treated on the 1.5 T MR-Linac. Daily MR-guided re-optimization of treatment plans showed dosimetric benefit in patients with perilesional edema or multiple lesions.
评估在线自适应磁共振引导的分次立体定向放射治疗（FSRT）在脑转移瘤（BMs）患者中的可行性和潜在益处。
28例连续的脑转移瘤患者在1.5T磁共振直线加速器上接受了5次分割、总剂量30Gy的FSRT治疗。FSRT各分次采用每日磁共振扫描，并利用轮廓创建每个适应性计划。在治疗前模拟（Fx0）及所有分次（Fx1、Fx2、Fx3、Fx4和Fx5）的磁共振图像上勾勒脑病变和病变周围水肿，以评估分次间变化。使用绝对/相对体积、骰子相似系数（DSC）和豪斯多夫距离（HD）指标对这些变化进行量化。使用计划靶体积（PTV）覆盖情况和危及器官（OAR）限制来比较非适应性计划和适应性计划。
共评估了28例患者的88个病变，其中23例（23/28，82.1%）为原发性肺腺癌。与Fx0相比，所有88个病变在FSRT期间均出现显著的肿瘤体积缩小（Fx1、Fx2、Fx3、Fx4和Fx5时的中位数分别为-0.75%、-5.33%、-9.32%、-17.96%和-27.73%，P<0.05）。有47个（47/88，53.4%）病变伴有病变周围水肿，与无病变周围水肿的病变相比，分次间变化有显著差异（P<0.001）。有多个病变的患者（13/28，46.4%）比分次间肿瘤变化比单个病变的患者（15/28，53.6%）更显著，包括肿瘤体积缩小和解剖移位（P<0.001）。非适应性计划的PTV覆盖在26/140个分次（19%）低于规定覆盖范围，其中12个（9%）低于规定超过10%。所有140个适应性分次均达到规定的靶区覆盖。适应性计划全脑接受的剂量也低于非适应性计划（P<0.001）。
在1.5T磁共振直线加速器上接受治疗的脑转移瘤患者的FSRT期间可发现显著的分次间肿瘤变化。每日磁共振引导的治疗计划重新优化对伴有病变周围水肿或多个病变的患者显示出剂量学益处。
