Po‐Poster ‐ 09: Depth dose gradients: A new approach to bremsstrahlung spectrum reconstruction

Abstract

A new approach to significantly improve the accuracy of bremsstrahlung spectra reconstructed from central axis depth dose data is introduced. While typical methods directly use the measured depth dose data, we show the advantages of using the gradient of this data for reconstruction. The inverse problem in terms of gradients is shown to be markedly less ill‐conditioned than the depth dose based inverse problem. We regularize the ill‐conditioning by truncating a diagonalization of the inverse problem to alleviate the effects of noise due to measurement and computational errors. The error in taking derivatives of depth dose data is demonstrated to be sufficiently controllable in an explicit Monte Carlo generated 15 MV spectrum example as not to overtake the improvements in the conditioning of the inverse problem.