Livingstone Jayde, Adam Jean François, Crosbie Jeffrey C, Hall Chris J, Lye Jessica E, McKinlay Jonathan, Pelliccia Daniele, Pouzoulet Frédéric, Prezado Yolanda, Stevenson Andrew W, Häusermann Daniel
Australian Synchrotron, Clayton, Victoria 3168, Australia.
Equipe d'accueil Rayonnement Synchrotron et Recherche Médicale, Université Grenoble-Alpes, Grenoble, France.
J Synchrotron Radiat. 2017 Jul 1;24(Pt 4):854-865. doi: 10.1107/S1600577517006233. Epub 2017 May 18.
Therapeutic applications of synchrotron X-rays such as microbeam (MRT) and minibeam (MBRT) radiation therapy promise significant advantages over conventional clinical techniques for some diseases if successfully transferred to clinical practice. Preclinical studies show clear evidence that a number of normal tissues in animal models display a tolerance to much higher doses from MRT compared with conventional radiotherapy. However, a wide spread in the parameters studied makes it difficult to make any conclusions about the associated tumour control or normal tissue complication probabilities. To facilitate more systematic and reproducible preclinical synchrotron radiotherapy studies, a dedicated preclinical station including small-animal irradiation stage was designed and installed at the Imaging and Medical Beamline (IMBL) at the Australian Synchrotron. The stage was characterized in terms of the accuracy and reliability of the vertical scanning speed, as this is the key variable in dose delivery. The measured speed was found to be within 1% of the nominal speed for the range of speeds measured by an interferometer. Furthermore, dose measurements confirm the expected relationship between speed and dose and show that the measured dose is independent of the scan direction. Important dosimetric parameters such as peak dose, valley dose, the collimator output factor and peak-to-valley dose ratio are presented for 5 mm × 5 mm, 10 mm × 10 mm and 20 mm × 20 mm field sizes. Finally, a feasibility study on three glioma-bearing rats was performed. MRT and MBRT doses were prescribed to achieve an average dose of 65 Gy in the target, and magnetic resonance imaging follow-up was performed at various time points after irradiation to follow the tumour volume. Although it is impossible to draw conclusions on the different treatments with such a small number of animals, the feasibility of end-to-end preclinical synchrotron radiotherapy studies using the IMBL preclinical stage is demonstrated.
同步加速器X射线的治疗应用，如微束（MRT）和迷你束（MBRT）放射治疗，如果能成功应用于临床实践，对于某些疾病而言有望比传统临床技术具有显著优势。临床前研究表明，有明确证据显示，与传统放射治疗相比，动物模型中的许多正常组织对MRT的更高剂量具有耐受性。然而，所研究参数的广泛差异使得难以就相关的肿瘤控制或正常组织并发症概率得出任何结论。为了促进更系统且可重复的临床前同步加速器放射治疗研究，在澳大利亚同步加速器的成像与医学束线（IMBL）设计并安装了一个包括小动物照射阶段的专用临床前工作站。该阶段根据垂直扫描速度的准确性和可靠性进行了表征，因为这是剂量输送中的关键变量。通过干涉仪测量发现，在测量的速度范围内，测量速度在标称速度的1%以内。此外，剂量测量证实了速度与剂量之间的预期关系，并表明测量剂量与扫描方向无关。给出了5 mm×5 mm、10 mm×10 mm和20 mm×20 mm照射野尺寸的重要剂量学参数，如峰值剂量、谷值剂量、准直器输出因子和峰谷剂量比。最后，对三只荷胶质瘤大鼠进行了可行性研究。规定MRT和MBRT剂量以在靶区实现平均剂量65 Gy，并在照射后的不同时间点进行磁共振成像随访以跟踪肿瘤体积。尽管用如此少量的动物无法对不同治疗得出结论，但证明了使用IMBL临床前阶段进行端到端临床前同步加速器放射治疗研究的可行性。
