ABSTRACT
Humans are continually exposed to ionizing radiation from a range of sources including environmentalandoccupationalsources.Thedosesfromthesevarioussourcesareverylowandgenerally oflowdoserates.Atthelevelofindividualcellswithinthehumanbody,thiscanequatetoonly
21.1 Introduction .......................................................................................................................... 575 21.2Low Dose Radiation Effects and Radiation Risk ................................................................. 576 21.3Introduction to Microbeams ................................................................................................. 576 21.4History, Rationale, and Key Aspects .................................................................................... 577 21.5Charged-Particle Microbeams .............................................................................................. 580
21.5.1 Microbeam Production ............................................................................................. 580 21.5.2Beam Detection ........................................................................................................ 581 21.5.3Beam Orientation and Sample Holder ...................................................................... 582 21.5.4Optics and Sample Preparation ................................................................................ 583 21.5.5Positioning Stage ...................................................................................................... 584
21.6 X-Ray Microbeams ............................................................................................................... 584 21.6.1X-Ray Source ............................................................................................................ 585 21.6.2X-Ray Optics ............................................................................................................ 587 21.6.3X-Ray Detection and Dosimetry .............................................................................. 588
21.7Electron Microbeams ........................................................................................................... 588 21.8 Future Developments ............................................................................................................ 589
21.8.1Beam Spot Scanning ................................................................................................ 589 21.8.2Non-Staining Imaging .............................................................................................. 590 21.8.3Hard X-Ray Optics ................................................................................................... 590 21.8.4Biological Advances ................................................................................................. 591
21.9 Summary .............................................................................................................................. 591 Acknowledgments .......................................................................................................................... 592 References ...................................................................................................................................... 592
single tracks of radiation crossing a cell over periods of weeks or years. Our understanding of theeffectsoftheselowdosesrequirestechnologicalapproachesthatcandeliverhighlylocalized radiation beams into biological models. This chapter reviews the use of novel microbeam technologies that allow relevant doses to be tested in biological systems. We outline some of the key technologicalapproachesusedtoproducemicrobeamsusingdifferenttypesofionizingradiationsandgive examples of some of the biological results that have been obtained with them.
