Estimated spectrum of a 4-MV therapeutic beam

We have made a comparative investigation of the estimated spectra obtained by the Laplace transform analysis of the transmitted exposure data measured in an absorption study of a 4-MV x-ray beam. Four transform pair models currently used with this method have been evaluated. It has been determined that the Archer-Wagner model provides a valid representation of the measured transmission data and yields an estimated spectrum which most closely resembles a Monte Carlo spectrum calculated for a 4-MV therapeutic x-ray beam available from a typical medical accelerator.