A practical approach to inverse planning for high-precision dose escalatedconformal prostate radiotherapy

The problem of choosing the best gantry angles and beam weights for dose-es calated conformal prostate treatment planning is formulated using a mixed-i nteger linear programming approach, to account for tumour dose homogeneity and dose-volume constraints. The formulation allows the number of beams to be restricted and for some of the beams to be compulsory. The present plann ing algorithm interfaces with and utilizes the three-dimensional planning c apabilities of a commercial treatment planning system. A case study is illu strated, which represents a particularly challenging planning problem due t o a large planning target volume and an unusually small bladder. Treatment plans with different numbers of beams are generated to compare with each ot her and with the standard six-field plan. Significant improvement is shown in the reduction of hot regions within the femoral heads and rectal wall, w hile not unduly compromising homogeneity constraints for the tumour.