Application of a proton microprobe to biomedical research : Limits and potentialities.

The capability of PIXE analysis to simultaneously detect trace elements with Z≥14, with a high power of detection, can be exploited in biomedical research if the diameter of the proton beam is reduced to micrometer dimensions. In this case, trace analyses of small particles or small parts of a larger specimen are rendered possible without deteriorating the detection limits of PIXE. The measurements yield a completely new type of information on the biological microstructure. In order to fully utilize the abilities of the combined method, however, sample preparation techniques, and irradiation procedures have to be adapted to each analysis problem. Examples of application of the Bochum Proton Microprobe will be used to demonstrate how and to what extent this can be achieved for different types of biomedical problems.