Microbeams

Microbeams are narrow beams of particles or photons with cross-sectional dimensions on the order of micrometres. They are produced by focusing or collimating a larger beam of electrons, ions, or photons to a small spot, enabling irradiation or interrogation of extremely small targets such as single cells, subcellular structures, or microfabricated features. Microbeams are used across several fields, with radiobiology, materials science, and medical research being the most prominent areas of application.

Production and techniques vary by particle type. X-ray microbeams are commonly generated at synchrotron facilities using specialized optics such as polycapillary lenses, Kirkpatrick–Baez mirrors, or Fresnel zone plates to achieve micrometre-scale focus. Proton and heavy-ion microbeams use magnetic and electric lenses in combination with precise collimation to produce micron-sized spots and often employ beam-scanning systems to interrogate larger areas. Electron microbeams are created with electron optics in electron microscopes or dedicated beamlines and are frequently used for microfabrication, imaging, and radiobiology experiments. In practice, microbeams may be used in fixed spots or scanned across a target to build up spatial maps of response or composition.

Applications include targeted irradiation of cells to study DNA damage, repair processes, and bystander effects, as well as preclinical work in microbeam radiation therapy, where arrays of micrometre-wide X-ray beams aim to spare normal tissue while delivering dose to tumors. In materials science and chemistry, microbeams enable high-resolution elemental mapping, microanalysis, and localized irradiation studies, supporting investigations of material properties and microstructure. The technique requires sophisticated instrumentation, precise alignment, and rigorous radiation safety controls.

See also: microbeam radiation therapy, x-ray microbeam, proton microbeam, focused ion beam.