title: Use of charged particle beams for analysis of biological tissues and fluids.
abstract: PIXE has passed through its demonstration stage and matured into a viable tool supported by a reliable physics data base; the main problem to be solved at the outset of any new project is the preparation of a representative specimen of uniform thickness (or thinness) rather than any aspect of X-ray or accelerator physics or technology.  We repeat the caution that minimum detection limits are strongly influenced by the nuclear reaction gamma-ray background from trace elements in the specimen.  Thus experiment on a new target type is preferable to use of MDL calculations based on the background due to atomic processes (bremsstrahlung) in the known matrix. One hopes to see a more adventurous mood eg a move from routine blood serum analysis towards analyses of different blood fractions that concentrate specific trace elements. PIGE, while promising, must be regarded as developmental until the data-base of elemental gamma-ray yields is extended and made more accurate; work on fluorine in teeth clearly stands to profit from this technique. Finally, RBS, although scarcely used to date in any biological context, is clearly a powerful way of measuring major elemental ratios in mineralised tissues; however, RBS lacks the resolving power of PIXE and so is not a candidate for multi-trace element analysis.
mesh_terms: D001826:Body Fluids / Q000032:analysis; D004602:Elements / Q000032:analysis*; D005720:Gamma Rays; D006801:Humans; D011522:Protons; D012542:Scattering, Radiation; D013052:Spectrometry, X-Ray Emission
chemical_list: D004602:Elements; D011522:Protons