A Gradient Method of Optimizing External-Beam Radiotherapy Treatment Plans

Although a number of methods of treatment optimization by computer have ben proposed, they have received little support. In this paper, an alternative approach is proposed based on the differentials of a treatment evaluation function with respect to wedge angle, incidence angle, entry point, and field weighting. The technique may be used in a batch-oriented computer system, or, by means of a conversational terminal, the therapist can plan a treatment with guidance from the program. Although it can be used to find global optima by a search process, it operates best as a method of improving partially-satisfactory treatments.