A problem in rotation therapy with X-rays: dose distributions with an axis of symmetry

We give the equations which need to be solved to extend the work of Brahme, Roos, and Lax to dose distributions which are not circularly symmetrical. These equations do not contain the linear absorption coefficient, mu, explicitly so they are valid in principle for any mu. The general solution of these equations has not been found, but the solution given by Brahme, Roos, and Lax is used to extend their work to simple dose distributions with an axis of symmetry. Some examples are given and discussed.