Previous attempts at optimization of radiotherapy planning are described and criticized, and consideration of these attempts has resulted in the development of a new technique using quadratic programming. Uniformity of tumour dose is selected as the most important feature of any plan, and this is achieved by minimizing the variance of the dose to preselected points within the tumour. The dose to vulnerable regions can be constrained not to exceed a given percentage of the mean tumour dose. Optimization of field weight and field type is possible. The operation of the system is described and some typical results are given.

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