FPM model calculation for micro X-ray fluorescence confocal imaging using synchrotron radiation

A novel quantitative reconstruction model for synchrotron-based confocal X-ray fluorescence imaging has been developed and validated. The theoretical approach uses a new generalized system of equations of the Fundamental Parameter Method (FPM) to calculate the 2D distribution of the concentration values of the trace, minor, and major elements. For the reconstruction procedure of the 2D quantitative mXRF calculations, a serial-type specialised iterative algorithm was developed based on successive approximation of the elementary composition of each individual voxel in the sample. This procedure is capable of neglecting serious numerical difficulty arising at the simultaneous-approaching solution of the huge number of variables involved in the non-linear FPM equations. The model describes the absorption of the primary and secondary X-ray beams in the sample volume and the photoelectric excitation process of characteristic X-ray emission in each sample voxel. For validation of this new evaluation method, standard samples were measured using monoenergetic synchrotron radiation at beamline L in HASYLAB.