基于 MRI 的 LINAC 调强放疗、基于 MRI 的三钴 60 源调强放疗和 VMAT 治疗脊柱 SABR 的治疗计划质量比较。
Comparison of treatment plan quality among MRI-based IMRT with a linac, MRI-based IMRT with tri-Co-60 sources, and VMAT for spine SABR.
机构信息
Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.
Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.
出版信息
PLoS One. 2019 Jul 22;14(7):e0220039. doi: 10.1371/journal.pone.0220039. eCollection 2019.
PURPOSE
This study compares the plan quality of magnetic-resonance image (MRI)-based intensity modulated radiation therapy (IMRT) using a linac (MR-linac-IMRT), MRI-based IMRT using tri-Co-60 sources (MR-Co-60-IMRT), and volumetric modulated arc therapy (VMAT) for spine stereotactic ablative radiotherapy (SABR).
METHODS
Twenty patients with thoracic spine metastasis were retrospectively selected for this study. For each patient, the MR-linac-IMRT, MR-Co-60-IMRT, and VMAT plans were generated using an identical CT image set and structures, except for the spinal cord and spinal cord planning organ-at-risk volume (PRV). Those two structures were contoured based on CT image sets for VMAT planning while those were contoured based on MR image sets for MR-linac-IMRT and MR-Co-60-IMRT planning. The initial prescription doses were 18 Gy in a single fraction for every plan in this study. If the tolerance level of the spinal cord was not met, the prescription doses were reduced to meet the tolerance level of the spinal cord. Dose-volumetric parameters of each plan were analyzed.
RESULTS
The average spinal cord volumes contoured based on the CT and MR images were 3.8±1.6 cm3 and 1.1±1.0 cm3, respectively (p<0.001). For four patients, the prescription doses of VMAT plans were reduced to 16 Gy to satisfy the spinal cord tolerance level. For thirteen patients, the prescription doses of MR-Co-60-IMRT plans were reduced to be less than 16 Gy to meet the spinal cord tolerance level. However, for every MR-linac-IMRT plan, the initial prescription doses of 18 Gy could be delivered to the target volume while satisfying the spinal cord tolerance. The average values of D10%, V10Gy, and V14Gy of the spinal cord PRV consistently indicated that the doses to the spinal cord PRV in the MR-linac-IMRT plans were the lowest among three types of plans in this study (all with p≤0.003).
CONCLUSION
MR-linac-IMRT appears promising for spine SABR.
目的
本研究比较了基于磁共振成像（MRI）的直线加速器调强放疗（MR-linac-IMRT）、基于三钴源的调强放疗（MR-Co-60-IMRT）和容积调强弧形治疗（VMAT）在脊柱立体定向消融放疗（SABR）中的计划质量。
方法
本研究回顾性选择了 20 例胸腰椎转移患者。对于每位患者，使用相同的 CT 图像集和结构生成了 MR-linac-IMRT、MR-Co-60-IMRT 和 VMAT 计划，除了脊髓和脊髓计划器官危及体积（PRV）。这两个结构是基于 VMAT 计划的 CT 图像集进行描绘的，而 MR-linac-IMRT 和 MR-Co-60-IMRT 计划是基于 MR 图像集进行描绘的。本研究中每个计划的初始处方剂量为 18 Gy 单次分割。如果脊髓的耐受水平不满足，处方剂量将降低以满足脊髓的耐受水平。分析了每个计划的剂量-体积参数。
结果
基于 CT 和 MR 图像描绘的脊髓平均体积分别为 3.8±1.6 cm3 和 1.1±1.0 cm3（p<0.001）。对于 4 名患者，为了满足脊髓耐受水平，将 VMAT 计划的处方剂量降低至 16 Gy。对于 13 名患者，为了满足脊髓耐受水平，将 MR-Co-60-IMRT 计划的处方剂量降低至 16 Gy 以下。然而，对于每个 MR-linac-IMRT 计划，初始的 18 Gy 处方剂量可以传递到靶区，同时满足脊髓耐受。脊髓 PRV 的 D10%、V10Gy 和 V14Gy 的平均值始终表明，本研究中三种类型的计划中，MR-linac-IMRT 计划的脊髓 PRV 剂量最低（均 p≤0.003）。
结论
MR-linac-IMRT 似乎是一种有前途的脊柱 SABR 治疗方法。
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