29: The quantitative evaluation of alternative treatment plans

A number of quantitative techniques have been investigated to objectively compare alternative treatment plans. Images of regret combine the dosimetric data represented by an isodose plot with the dose levels prescribed for each organ, and display in appropriate colours any regions which have unacceptably large deviations. Score functions are calculated for dose gradient across the target, 'hot' and 'cold' target areas, and for each sensitive organ, and are presented on a uniform scale from 10 (ideal) to zero (limit of acceptability). Prediction of risk is based on dose-volume histograms for each organ, combined with a partial-volume dose relationship to estimate equivalent whole-organ doses. 2 figs.; 2 tabs