Microbeam radiation therapy at a laser-based compact synchrotron x-ray source

Summary form only given. X-ray microbeam radiation therapy (MRT) is a preclinical approach for tumor treatment based on spatial dose redistribution. In-vitro and in-vivo studies suggest higher tumor control and less normal tissue complications compared to conventional radiotherapy [1]. Due to high requirements on dose rate and x-ray beam collimation, most of the research on MRT has been performed at large-scale synchrotron facilities. We conducted first successful in-vitro experiments at a laser-based Compact Light Source (CLS). This unique system is based on inverse Compton scattering of infrared laser photons, enhanced with a high-finesse bowtie-cavity, with relativistic electrons of 20-45 MeV [2]. Here, the magnetic field created by undulators at standard synchrotrons is replaced by the electro-magnetic field of the laser photons. Due to the significantly lower period of the laser undulator, these low electron energies are sufficient to achieve quasi-monochromatic x-rays of 15-35 keV with a source size of about 45×45 μm
²
yielding a photon flux of 1×10
¹⁰
ph/s. As this x-ray source bridges the gap between laboratory x-ray sources and large-scale synchrotron facilities, it is well suited to deepen the knowledge about radiobiological effects of MRT in in-vitro studies using cells or tissue models or in-vivo using small animals.