Inserm UA7, Rayonnement synchrotron pour la recherche médicale (STROBE), Université Grenoble Alpes, Grenoble, France.
Inserm UA7, Rayonnement synchrotron pour la recherche médicale (STROBE), Université Grenoble Alpes, Grenoble, France; Institute of Anatomy, Group Tomographic and Clinical Anatomy, University of Bern, Bern, Switzerland.
Int J Radiat Oncol Biol Phys. 2020 Jun 1;107(2):360-369. doi: 10.1016/j.ijrobp.2020.02.023. Epub 2020 Feb 21.
Synchrotron microbeam radiation therapy (MRT) is based on the spatial fractionation of the incident, highly collimated synchrotron beam into arrays of parallel microbeams depositing several hundred grays. It appears relevant to combine MRT with a conventional treatment course, preparing a treatment scheme for future patients in clinical trials. The efficiency of MRT delivered after several broad-beam (BB) fractions to palliate F98 brain tumors in rats in comparison with BB fractions alone was evaluated in this study.
Rats bearing 10 F98 cells implanted in the caudate nucleus were irradiated by 5 fractions in BB mode (3 × 6 Gy + 2 × 8 Gy BB) or by 2 boost fractions in MRT mode to a total of 5 fractions (3 × 6 Gy BB + MRT 2 × 8 Gy valley dose; peak dose 181 Gy [50/200 μm]). Tumor growth was evaluated in vivo by magnetic resonance imaging follow-up at T, T, T, T, T, and T days after radiation therapy and by histology and flow cytometry.
MRT-boosted tumors displayed lower cell density and cell proliferation compared with BB-irradiated tumors. The MRT boost completely stopped tumor growth during ∼4 weeks and led to a significant increase in median survival time, whereas tumors treated with BB alone recurred within a few days after the last radiation fraction.
The first evidence is presented that MRT, delivered as a boost of conventionally fractionated irradiation by orthovoltage broad x-ray beams, is feasible and more efficient than conventional radiation therapy alone.
同步辐射微束放射治疗（MRT）基于将入射的高准直同步加速器束空间分割成平行微束阵列，每个微束沉积几百个格雷。将 MRT 与常规治疗方案相结合，为临床试验中的未来患者制定治疗方案似乎是有意义的。本研究评估了与单独进行宽束（BB）分次相比，将 MRT 用于缓解大鼠 F98 脑肿瘤的疗效。
将 10 个 F98 细胞植入尾状核的大鼠接受 BB 模式下的 5 个分次照射（3×6 Gy+2×8 Gy BB）或 MRT 模式下的 2 个增量分次照射，总剂量为 5 个分次（3×6 Gy BB+MRT 2×8 Gy 低谷剂量；峰值剂量 181 Gy[50/200 μm]）。在放射治疗后 T、T、T、T、T 和 T 天通过磁共振成像（MRI）随访，以及通过组织学和流式细胞术，对体内肿瘤生长进行评估。
与 BB 照射的肿瘤相比，MRT 增强的肿瘤显示出较低的细胞密度和细胞增殖。MRT 增强完全阻止了肿瘤的生长约 4 周，并导致中位生存时间显著延长，而单独接受 BB 治疗的肿瘤在最后一次放疗后几天内复发。
首次提出证据表明，MRT 作为常规分次照射的增量照射，通过正交千伏宽束 X 射线实现，是可行的，比单独常规放射治疗更有效。
