Abstract
X-ray microbeam radiotherapy can potentially widen the therapeutic window due to a geometrical redistribution of the dose. However, high requirements on photon flux, beam collimation, and system stability restrict its application mainly to large-scale, cost-intensive synchrotron facilities. With a unique laser-based Compact Light Source using inverse Compton scattering, we investigated the translation of this promising radiotherapy technique to a machine of future clinical relevance. We performed in vitro colony-forming assays and chromosome aberration tests in normal tissue cells after microbeam irradiation compared to homogeneous irradiation at the same mean dose using 25 keV X-rays. The microplanar pattern was achieved with a tungsten slit array of 50 μm slit size and a spacing of 350 μm. Applying microbeams significantly increased cell survival for a mean dose above 2 Gy, which indicates fewer normal tissue complications. The observation of significantly less chromosome aberrations suggests a lower risk of second cancer development. Our findings provide valuable insight into the mechanisms of microbeam radiotherapy and prove its applicability at a compact synchrotron, which contributes to its future clinical translation.
Highlights
Using the first commercially sold compact synchrotron X-ray source based on inverse Compton scattering, the Munich Compact Light Source (MuCLS), we investigate the translation of microbeam radiation therapy (MRT) to a laboratory-sized and more cost-efficient system that bridges the gap between conventional X-ray tubes and high-performance synchrotron facilities [13,14,15]
Due to flux variations over time, transmitted photons were monitored with a photon counting detector and the photon number was corrected for all absorbing elements along the beam path
The results shown for microbeam and homogeneous irradiations strongly suggest that their radiobiological effect differs at a quasi-monochromatic energy of 25 keV produced by a compact synchrotron source
Summary
X-ray microbeam radiation therapy (MRT) has shown high potential in terms of increased normal tissue tolerance and improved tumour control when compared to conventional. X-ray microbeam irradiation at a compact synchrotron programme Open Access Publishing received by KB, the Centre for Advanced Laser Applications http://www.cala-laser.de with respect to resources necessary for and at the MuCLS, the European Research Council (ERC, H2020, AdG 695045) https://erc.europa.eu/ received by FP, the DFG Cluster of Excellence Munich-Centre for Advanced Photonics https://www.munich-photonics.de/en/ received by TES, SEC, FP, and JJW, the DFG Gottfried Wilhelm Leibniz program http://www.dfg. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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