High energy X-rays reconstruction in the entire radiotherapy energy range

We have previously developed an original method of high energy X-ray spectral reconstruction from measured transmission data on a 12MV beam. This reconstruction is done by direct resolution of the matrix system A*F=T where T is the measured transmission vector, F is the fraction of the signal per unit energy produced by photons of a given energy in the unattenuated beam and A is the attenuation matrix. This technique is using spectral vectorial algebra. The resolution has been extended and tested in the entire radiotherapy energy range with photon beams from 4 to 25 MV nominal energies. Dosimetric quantities such as attenuation curves, mean energies and mean attenuation coefficients have been recalculated from our reconstructed spectra. These quantities have been computed for different materials