PIXE TOMOGRAPHIC RECONSTRUCTION OF ELEMENTAL DISTRIBUTIONS USING AN ITERATIVE MAXIMUM-LIKELIHOOD METHOD

We have developed a computer program for PIXE tomographic reconstructi on of trace elemental distributions using the maximum-likelihood expec tation-maximization (MLEM) algorithm. This algorithm is based on the e xact stochastic model of X-ray yield measurements. Energy loss of the incident particles and attenuation of the X-ray photons are incorporat ed into the reconstruction algorithm so quantitatively accurate trace elemental concentrations can be obtained. The reconstruction algorithm has been tested using calculated X-ray yields generated from a micro- PIXE line scan simulation program. This algorithm is capable of recons tructing elemental distributions using only four angular views of the sample.