Régnard Pierrick, Bräuer-Krisch Elke, Troprès Irène, Keyriläinen Jani, Bravin Alberto, Le Duc Géraldine
Biomedical Facility, 6, Rue Jules Horowitz, ESRF, BP220, F 38043 Grenoble, France.
Eur J Radiol. 2008 Dec;68(3 Suppl):S151-5. doi: 10.1016/j.ejrad.2008.04.049. Epub 2008 Jul 16.
Microbeam radiation therapy (MRT) is a form of radiosurgery first dedicated to the treatment of brain tumors. It uses arrays of synchrotron generated X-rays microbeams of very high doses (typically 625 Gy). Microbeams are typically few micrometers large (25 microm) and few hundred micrometers spaced (200 microm). Previous experiments have shown that despite a good tumor eradication rate (5/11), a 100-microm spacing unidirectional irradiation (skin dose 625 Gy, width 25 microm) was too invasive for normal tissue. On the contrary, a 200-microm spacing unidirectional irradiation preserved healthy tissue with a low tumor eradication rate (2/32). The purpose of this study was to enhance the potential of the 200 microm spacing irradiation protocol. After diagnosis of the tumor by MRI, 9L tumor-bearing rats were laterally irradiated with 51 microbeams (625 Gy, 25 microm, 200 microm) 14 days after implantation. Three drugs (Gd-DTPA, CisPt, temozolomide) were tested, after intratumoral injection at the theoretical center of the tumor. Control rats displayed a median survival time of 19 days. There was no significant difference between drug-treated rats and control group. Irradiated animals showed an increase in life span (ILS) of 60.5%. Interestingly, the ILS increased to 131.6% and 1/6 rat survived more than 1 year in case of MRT combined with gadolinium injection. These results showed that the synergy between gadolinium injection (acting as a dose enhancer) and MRT improved significantly the life span of tumor bearing rats (more than a factor 2).
微束放射治疗（MRT）是一种放射外科形式，最初专门用于治疗脑肿瘤。它使用同步加速器产生的具有非常高剂量（通常为625戈瑞）的X射线微束阵列。微束通常几微米宽（25微米），间隔几百微米（200微米）。先前的实验表明，尽管肿瘤根除率良好（5/11），但100微米间距的单向照射（皮肤剂量625戈瑞，宽度25微米）对正常组织的侵袭性过大。相反，200微米间距的单向照射能保留健康组织，但肿瘤根除率较低（2/32）。本研究的目的是提高200微米间距照射方案的潜力。通过MRI诊断肿瘤后，对荷9L肿瘤的大鼠在植入肿瘤14天后进行51束微束的侧向照射（625戈瑞，25微米，200微米）。在肿瘤理论中心进行瘤内注射后，测试了三种药物（钆喷酸葡胺、顺铂、替莫唑胺）。对照大鼠的中位生存时间为19天。药物治疗组大鼠与对照组之间无显著差异。接受照射的动物寿命延长（ILS）了60.5%。有趣的是，在MRT联合钆注射的情况下，ILS提高到了131.6%，并且1/6的大鼠存活超过了1年。这些结果表明，钆注射（作为剂量增强剂）与MRT之间的协同作用显著提高了荷瘤大鼠的寿命（超过2倍）。
