A computer-aided treatment planning technique for universal wedges.

Some modern accelerators provide only one wedge built into the head of the treatment machine. A continuous range of wedge angles can be generated using wedged and unwedged beams in different proportions. However, this may pose difficulty in treatment planning since the planners will have to work with twice as many beams to achieve a desirable dose distribution. We have developed a simple algorithm to solve the treatment planning problem involving wedged and open beam combinations. The algorithm is based on the assumption that the user has some knowledge of the dose distribution to be optimized. Some properties of the distributions are then used to set up the system of equations for optimization. Unlike other optimization techniques, it does not require specification of dose value to every interest point selected, and it allows each specified dose value to vary within a clinically acceptable range. Examples are given to illustrate the application of the algorithm for some standard treatment plans.