Enhanced bremsstrahlung spectrum reconstruction from depth–dose gradients

Abstract

We present a technique to significantly improve the accuracy of bremsstrahlung spectra reconstructed from central-axis depth–dose data using inverse methods. While typical approaches directly use the measured depth–dose data, we show the advantage of using the gradient of these data for reconstruction. The inverse problem in terms of gradients is shown to be markedly less ill-conditioned than the usual inverse problem. In each case, a regularization is introduced to alleviate the effects of noise due to measurement and computation. The error in taking derivatives of depth–dose data is demonstrated to be sufficiently controllable as not to overtake the improvements in the conditioning of the inverse problem in a pair of simulated examples.