Development of a bio-PIXE setup at the Debrecen scanning proton microprobe

Abstract

On the growing need of an accurate, quantitative method for the analysis of thin biological tissues down to the cell level, a measurement setup and data evaluating system has been developed at the Debrecen scanning proton microprobe facility, using its unique capability of the PIXE-PIXE technique. Quantitative elemental concentrations and true elemental maps from C to U can be produced in the case of thin (10–50μm), inhomogeneous samples of organic matrix with a 2μm lateral resolution.The method is based on the combined application of on-axis STIM and PIXE-PIXE ion beam analytical techniques. STIM spectra and maps are used to determine the morphology and the area density of the samples. PIXE spectra and maps of an ultra thin windowed and a conventional Be-windowed Si(Li) X-ray detectors are used to quantify concentrations and distributions of elements in the C to Fe (light and medium) and S to U (medium and heavy) atomic number regions, separately. For cross-checking the validation of the obtained data in a few cases RBS technique was used simultaneously.The application of the new bio-PIXE method is shown through an example, the study of the penetration and clearance of ultra-fine particles containing heavy metals (TiO2) of physical bodycare cosmetics in different layers of skin within the frame of the NANODERM EU5 project.