Microbeam radiation therapy is an innovative treatment approach in radiation therapy that\nuses arrays of a few tens of micrometer wide and a few hundreds of micrometer spaced planar\nx-ray beams as treatment fields. In preclinical studies these fields efficiently eradicated tumors\nwhile normal tissue could effectively be spared. However, development and clinical application of\nmicrobeam radiation therapy is impeded by a lack of suitable small scale sources. Until now, only\nlarge synchrotrons provide appropriate beam properties for the production of microbeams.\nMethods: In this work, a conventional x-ray tube with a small focal spot and a specially designed\ncollimator are used to produce microbeams for preclinical research. The applicability of the developed\nsource is demonstrated in a pilot in vitro experiment. The properties of the produced radiation field\nare characterized by radiochromic film dosimetry.\nResults: 50 Ã?¼m wide and 400 Ã?¼m spaced microbeams were produced in a 20Ã?â??20 mm2 sized\nmicrobeam field. The peak to valley dose ratio ranged from 15.5 to 30, which is comparable to\nvalues obtained at synchrotrons. A dose rate of up to 300 mGy/s was achieved in the microbeam\npeaks. Analysis of DNA double strand repair and cell cycle distribution after in vitro exposures of\npancreatic cancer cells (Panc1) at the x-ray tube and the European Synchrotron leads to similar results.\nIn particular, a reduced G2 cell cycle arrest is observed in cells in the microbeam peak region.\nConclusions: At its current stage, the source is restricted to in vitro applications. However, moderate\nmodifications of the setup may soon allow in vivo research in mice and rats.
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