Imaging biological structures with a proton microprobe

Imaging the morphology of the tissue in vivo and producing the correspondent elemental maps, whether in major, minor, or trace concentrations in real-time can be done using a focused beam of accelerated particles. This can be accomplished using different ion beam techniques simultaneously such as Scanning transmission ion microscopy (STIM), secondary electron imaging (SEI), Rutherford backscattering spectrometry (RBS), and particle induced X-ray emission (PIXE). The results are fully quantitative. The experimental set-up including focusing, scanning and detection systems, is often called Nuclear Microprobe, or, if the projectiles are protons, Proton Microprobe. This paper deals with the basic principles of proton microprobe, including data processing and imaging. Considerations for specimen preparation requirements and for interpretation of results are focused. Examples of applications to biology and to human health problems are given.