Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Neuenheimer Feld 280, 69120, Heidelberg, Germany.
Department of Radiation Oncology, University Hospital of Heidelberg, Neuenheimer Feld 400, 69120, Heidelberg, Germany.
Strahlenther Onkol. 2018 May;194(5):425-434. doi: 10.1007/s00066-017-1258-y. Epub 2018 Jan 18.
The present work aimed to analyze the feasibility of a shuttle-based MRI-guided radiation therapy (MRgRT) in the treatment of pelvic malignancies.
20 patients with pelvic malignancies were included in this prospective feasibility analysis. Patients underwent daily MRI in treatment position prior to radiotherapy at the German Cancer Research Center. Positional inaccuracies, time and patient compliance were assessed for the application of off-line MRgRT.
In 78% of applied radiation fractions, MR imaging for position verification could be performed without problems. Additionally, treatment-related side effects and reduced patient compliance were only responsible for omission of MRI in 9% of radiation fractions. The study workflow took a median time of 61 min (range 47-99 min); duration for radiotherapy alone was 13 min (range 7-26 min). Patient positioning, MR imaging and CT imaging including patient repositioning and the shuttle transfer required median times of 10 min (range 7-14 min), 26 min (range 15-60 min), 5 min (range 3-8 min) and 8 min (range 2-36 min), respectively. To assess feasibility of shuttle-based MRgRT, the reference point coordinates for the x, y and z axis were determined for the MR images and CT obtained prior to the first treatment fraction and correlated with the coordinates of the planning CT. In our dataset, the median positional difference between MR imaging and CT-based imaging based on fiducial matching between MR and CT imaging was equal to or less than 2 mm in all spatial directions. The limited space in the MR scanner influenced patient selection, as the bore of the scanner had to accommodate the immobilization device and the constructed stereotactic frame. Therefore, obese, extremely muscular or very tall patients could not be included in this trial in addition to patients for whom exposure to MRI was generally judged inappropriate.
This trial demonstrated for the first time the feasibility and patient compliance of a shuttle-based off-line approach to MRgRT of pelvic malignancies.
本研究旨在分析基于穿梭机的磁共振引导放射治疗（MRgRT）在治疗盆腔恶性肿瘤中的可行性。
本前瞻性可行性分析纳入 20 例盆腔恶性肿瘤患者。在德国癌症研究中心进行放射治疗前，患者每天在治疗位置进行 MRI。评估离线 MRgRT 应用中的位置不准确性、时间和患者依从性。
在 78%的应用放射剂量中，可以顺利进行用于验证位置的 MRI 成像。此外，治疗相关的副作用和降低的患者依从性仅导致 9%的放射剂量未能进行 MRI 成像。研究工作流程平均需要 61 分钟（范围 47-99 分钟）；单独进行放射治疗需要 13 分钟（范围 7-26 分钟）。患者定位、MR 成像和包括患者重新定位和穿梭机转移的 CT 成像分别需要平均 10 分钟（范围 7-14 分钟）、26 分钟（范围 15-60 分钟）、5 分钟（范围 3-8 分钟）和 8 分钟（范围 2-36 分钟）。为了评估基于穿梭机的 MRgRT 的可行性，我们确定了第一剂量治疗前的 MR 图像和 CT 图像中 x、y 和 z 轴的参考点坐标，并将其与计划 CT 的坐标进行了比较。在我们的数据集，基于 MR 和 CT 图像之间的基准点匹配，MR 成像和 CT 成像的坐标之间的位置差异中位数在所有空间方向上均等于或小于 2 毫米。MR 扫描仪的有限空间影响了患者选择，因为扫描仪的孔径必须容纳固定装置和构建的立体定向框架。因此，除了那些通常被认为不适合接受 MRI 的患者外，肥胖、肌肉非常发达或非常高的患者也不能被纳入该试验。
本试验首次证明了基于穿梭机的离线方法进行盆腔恶性肿瘤的 MRgRT 的可行性和患者依从性。
