Technique of range modulation for a clinical pi‐meson beam

A simple, versatile technique of range modulation has been developed based on the mathematical technique of linear programming for linear addition of depth dose curves. This technique enables the use of discrete step range shifting, and hence results in substantial simplification in the design and operation of range modulators. A prototype using only eight steps has been constructed for the TRIUMF biomedical π− channel for cancer radiotherapy. This system has been shown to be capable of producing depth dose profiles of various characteristics required for biomedical experimentation. Its operation under computer control is also simple, accurate, and immune to large fluctuations in the output of the TRIUMF accelerator.