Neuroradiology Unit and CERMAC, Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, Milan, Italy; Department of Medical Physics, IRCCS San Raffaele Scientific Institute, Milan, Italy.
Department of Medical Physics, IRCCS San Raffaele Scientific Institute, Milan, Italy.
Phys Med. 2018 Nov;55:127-134. doi: 10.1016/j.ejmp.2018.10.004. Epub 2018 Oct 9.
Fractionated radiotherapy in brain tumors is commonly associated with several detrimental effects, largely related to the higher radiosensitivity of the white matter (WM) with respect to gray matter. However, no dose constraints are applied to preserve WM structures at present. Magnetic Resonance (MR) Tractography is the only technique that allows to visualize in vivo the course of WM eloquent tracts in the brain. In this study, the feasibility of integrating MR Tractography in tomotherapy treatment planning has been investigated, with the aim to spare eloquent WM regions from the dose delivered during treatment.
Nineteen high grade glioma patients treated with fractionated radiotherapy were enrolled. All the patients underwent pre-treatment MR imaging protocol including Diffusion Tensor Imaging (DTI) acquisitions for MR Tractography analysis. Bilateral tracts involved in several motor, language, cognitive functions were reconstructed and these fiber bundles were integrated into the Tomotherapy Treatment planning system. The original plans without tracts were compared with the optimized plans incorporating the fibers, to evaluate doses to WM structures in the two differently optimized plans.
No significant differences were found between plans in terms of planning target volume (PTV) coverage between the original plans and the optimized plans incorporating fiber tracts. Comparing the mean as well as the maximal dose (Dmean and Dmax), a significant dose reduction was found for most of the tracts. The dose sparing was more relevant for contralateral tracts (P < 0.0001).
The integration of MR Tractography into radiotherapy planning is feasible and beneficial to preserve important WM structures without reducing the clinical goal of radiation treatment.
脑肿瘤的分割放疗通常与多种有害作用相关，这些作用主要与白质（WM）相对于灰质的更高放射敏感性有关。然而，目前没有剂量限制来保护 WM 结构。磁共振（MR）纤维束追踪技术是唯一允许在活体中可视化脑内 WM 结构的技术。在这项研究中，探讨了将 MR 纤维束追踪技术集成到调强放疗计划中的可行性，旨在在治疗过程中避免 WM 区域受到剂量照射。
纳入 19 名接受分割放疗的高级别胶质瘤患者。所有患者均接受包括弥散张量成像（DTI）采集的治疗前磁共振成像（MRI）检查，以进行 MR 纤维束追踪分析。重建涉及多个运动、语言、认知功能的双侧纤维束，并将这些纤维束整合到调强放疗计划系统中。比较未纳入纤维束的原始计划和纳入纤维束的优化计划，以评估两种不同优化计划中 WM 结构的剂量。
在原始计划和纳入纤维束的优化计划之间，计划靶区（PTV）覆盖率方面没有差异。比较平均剂量和最大剂量（Dmean 和 Dmax），大多数纤维束的剂量降低明显。对侧纤维束的剂量节省更为显著（P < 0.0001）。
将 MR 纤维束追踪技术整合到放疗计划中是可行的，可以在不降低放射治疗临床目标的情况下，有助于保护重要的 WM 结构。
