Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea; Department of Radiation Oncology, Gil Medical Center, Gachon University College of Medicine, Incheon, South Korea.
Department of Radiation Oncology, Ajou University School of Medicine, Suwon, South Korea.
Pract Radiat Oncol. 2024 Sep-Oct;14(5):e324-e333. doi: 10.1016/j.prro.2024.04.012. Epub 2024 Apr 30.
We aimed to develop and investigate positional reproducibility using a fixation device (Unity Brain tumor Immobilization Device [UBID]) in patients with brain tumor undergoing magnetic resonance (MR)-guided radiation therapy (RT) with a 1.5 Tesla (T) MR-linear accelerator (MR-LINAC) to evaluate its feasibility in clinical practice and report representative cases of patients with central nervous system (CNS) tumor.
Quantitative analysis was performed by comparing images obtained by placing only the MR phantom on the couch with those obtained by placing UBID next to the MR phantom. Twenty patients who underwent RT for CNS tumors using 1.5T MR-LINAC between June and October 2022 were retrospectively analyzed. Among them, 5 did not use UBID, whereas 15 used UBID. The positional reproducibility of UBID was evaluated using the median interfractional and intrafractional errors in the first 10 fractions.
Each MR quality factor of the MR phantom with UBID satisfied the criteria presented by Elekta. Median values of median shifts in the mediolateral, anteroposterior, and craniocaudal axes for interfractional errors were 2.98, 2.35, and 1.40 mm, respectively. For intrafractional errors, the median values were 0.05, 0.03, and 0.06 mm, respectively. The median values of the median rotations in pitch, roll, and yaw for both interfractional and intrafractional rotations were 0.00°. One patient diagnosed with an optic nerve sheath meningioma received RT with motion monitoring during irradiation. In 2 patients, changes in the tumor cavity and residual lesions were observed in the MRI obtained using 1.5T MR-LINAC on the day of the first treatment and immediately before the 21 fraction, respectively; therefore, offline/online adaptation was performed.
The reproducible and immobile UBID is clinically feasible in patients with CNS tumors receiving RT with 1.5T MR-LINAC. Based on our initial experience, we developed a workflow for 1.5T MR-LINAC treatment of CNS tumors.
我们旨在开发并研究使用固定装置（Unity Brain tumor Immobilization Device [UBID]）在接受 1.5 特斯拉（T）MR-直线加速器（MR-LINAC）引导的磁共振（MR）引导放射治疗（RT）的脑肿瘤患者中的位置重现性，以评估其在临床实践中的可行性，并报告中枢神经系统（CNS）肿瘤患者的代表性病例。
通过仅将磁共振体模放置在治疗床上与将 UBID 放置在磁共振体模旁边两种情况下所获得的图像进行比较，进行定量分析。回顾性分析了 2022 年 6 月至 10 月间接受 1.5T MR-LINAC 治疗 CNS 肿瘤的 20 例患者。其中，5 例未使用 UBID，15 例使用 UBID。使用前 10 个分次的分次间和分次内误差的中位数评估 UBID 的位置重现性。
带有 UBID 的磁共振体模的每个磁共振质量系数均满足 Elekta 提出的标准。分次间误差中，中侧轴、前后轴和头侧轴的中位数偏移值分别为 2.98、2.35 和 1.40mm。对于分次内误差，中位数值分别为 0.05、0.03 和 0.06mm。分次间和分次内旋转的中 Pitch、Roll 和 Yaw 旋转的中位数值均为 0.00°。一位视神经鞘脑膜瘤患者在放疗过程中接受了运动监测。有 2 位患者在首次治疗当日和第 21 次治疗前的 MRI 中分别观察到肿瘤腔和残留病灶的变化，因此进行了离线/在线校正。
在接受 1.5T MR-LINAC 放射治疗的 CNS 肿瘤患者中，可重现且固定的 UBID 具有临床可行性。基于我们的初步经验，我们开发了一种用于 1.5T MR-LINAC 治疗 CNS 肿瘤的工作流程。
