Selective brain tumor cell death caused by synchrotron microbeam X-ray radiation

采用宽峰宽（100 μm）共面或交叉共面微束辐射（MRT）治疗人脑胶质瘤U251细胞，并与窄峰宽（20 μm）MRT进行比较。X射线产生在SPring-8，一个大规模的shynchrotron辐射装置，和新设计的可调准直器使用。宽、窄宽度微梁的梁中心间距分别为500 μm和100 μm，与梁宽之比均为5。窄宽度MRT在130戈伊的峰值剂量下提供足够的抗肿瘤效应。宽MRT的影响较小，但在跨平面方式或重复两次，宽MRT显示出与窄MRT相当的效果。凋亡细胞死亡在宽MRT和窄MRT中均未增加，表明直接细胞死亡不能解释肿瘤生长抑制。细胞和组织生物学中的功能机制对于MRT的临床目的是必不可少的。

Microbeam radiation therapy (MRT) with wide (100 μm) peak width in co-planar or cross planar manner was applied on human U251 glioma cells and compared with narrow (20 μm) MRT. X-ray was generated at SPring-8, a large scale shynchrotron radiation facility, and newly designed adjustable collimeter was used. Spacing distances on center of beams in wide and narrow width microbeam were 500 μm and 100 μm, setting the same ratio to beam width of five. Narrow width MRT provide sufficient antitumoral effect at the peak dose of 130 Gy. Wide MRT has less effect, but in cross-planar manner or by repeating twice, wide MRT showed comparative effect to narrow MRT. Apoptotic cell death did not increased in neither wide nor narrow MRT, indicating direct cell death did not account for tumor growth suppression. Functional mechanisms in cell and tissue biology is essential for clinical purpose of MRT.