First clinical experiences with a high field 1.5 T MR linac
First clinical experiences with a high field 1.5 T MR linac
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DOI：
10.1080/0284186x.2019.1627417
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发表时间：
2019-06-15
期刊：
影响因子：
3.1
通讯作者：
Bernchou, Uffe
中科院分区：
文献类型：
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作者：
Bertelsen, Anders S.;Schytte, Tine;Bernchou, Uffe
目的：一台1.5T磁共振直线加速器(MRL)最近问世。MRL治疗工作流程(WF)包括基于每日磁共振图像(MRI)的在线计划调整。这项研究报告了使用五个月后在患者依从性、病例、WF计时和剂量准确性方面的初步临床经验。方法和材料：根据当天的临床情况使用两种不同的WF；适应位置WF(ATP)，其中参考平面位置被严格调整以匹配靶点和桨的位置；以及适应形状WF(ATS)，其中使用变形图像配准创建新的计划以匹配当天的解剖结构。这两个WFS都包括三次3D MRI扫描，用于计划调整、射束前验证和调强放疗期间的验证。记录患者的依从性和WF时间。使用圆柱形二极管体模评估剂量传递的准确性。结果：19例患者已完成治疗，共接受176次治疗。病例从前列腺治疗(60Gy20F)到淋巴结SBRT(45Gy3F)和卵巢照射去势(15Gy3F)不等。127例患者的中位会话时间(患者从入院到出院)为26(21-78)分钟，由于额外的计划适应，其中4个部分持续时间超过45min。对于49个ATS，轮廓绘制使用的中位数时间为12(1-24)分钟，总的中位数会话时间为42(29-91)分钟。三次SBRT分批持续了一个多小时。患者对坐在MRL沙发上的时间耐受性良好。调整后的计划伽玛通过率(2 mm，全球最大值2%)的中位数为99.2(93.4-100)%，表明计划剂量与交付剂量之间有很好的一致性。结论：MRL治疗，包括每日核磁共振成像、计划调整和准确的剂量传递，在临床可接受的时间范围内是可能的，患者对其耐受性良好。
Purpose: A 1.5 T MR Linac (MRL) has recently become available. MRL treatment workflows (WF) include online plan adaptation based on daily MR images (MRI). This study reports initial clinical experiences after five months of use in terms of patient compliance, cases, WF timings, and dosimetric accuracy. Method and materials: Two different WF were used dependent on the clinical situation of the day; Adapt To Position WF (ATP) where the reference plan position is adjusted rigidly to match the position of the targets and the OARs, and Adapt To Shape WF (ATS), where a new plan is created to match the anatomy of the day, using deformable image registration. Both WFs included three 3D MRI scans for plan adaptation, verification before beam on, and validation during IMRT delivery. Patient compliance and WF timings were recorded. Accuracy in dose delivery was assessed using a cylindrical diode phantom. Results: Nineteen patients have completed their treatment receiving a total of 176 fractions. Cases vary from prostate treatments (60Gy/20F) to SBRT treatments of lymph nodes (45 Gy/3F) and castration by ovarian irradiation (15 Gy/3F). The median session time (patient in to patient out) for 127 ATPs was 26 (21-78) min, four fractions lasted more than 45 min due to additional plan adaptation. For the 49 ATSs a median time of 12 (1-24) min was used for contouring resulting in a total median session time of 42 (29-91) min. Three SBRT fractions lasted more than an hour. The time on the MRL couch was well tolerated by the patients. The median gamma pass rate (2 mm,2% global max) for the adapted plans was 99.2 (93.4-100)%, showing good agreement between planned and delivered dose. Conclusion: MRL treatments, including daily MRIs, plan adaptation, and accurate dose delivery, are possible within a clinically acceptable timeframe and well tolerated by the patients.