The inverse problem of depth dose curve estimation.

The inverse problem of the depth dose curve is formulated and a proposition for its solution is presented. The solution is based on the approximation of the observation equation with a numerical quadrature operator and the regularization of this inverse problem with a smoothness side constraint. The problem formulation is applicable for both the electron and the photon depth dose curve estimation. Moreover, the method is equivalent for, for example, all energies, field sizes and source-to-phantom distances. Simulations show that the estimation error is smaller with the proposed method than with direct linear interpolation. The main result of the paper, however, is the formulation of the problem that allows feasible extensions and modifications for different measurement situations.