Explicit optimization of plan quality measures in intensity-modulated radiation therapy treatment planning

摘要

Conventional planning objectives in optimization of intensity-modulatedradiotherapy treatment (IMRT) plans are designed to minimize the violation ofdose-volume histogram (DVH) thresholds using penalty functions. Althoughsuccessful in guiding the DVH curve towards these thresholds, conventionalplanning objectives offer limited control of the individual points on the DVHcurve (doses-at-volume) used to evaluate plan quality. In this study, weabandon the usual penalty-function framework and propose planning objectivesthat more explicitly relate to DVH statistics. The proposed planning objectivesare based on mean-tail-dose, resulting in convex optimization. We alsodemonstrate how to adapt a standard optimization method to the proposedformulation in order to obtain a substantial reduction in computational cost. We investigate the potential of the proposed planning objectives as tools foroptimizing DVH statistics through juxtaposition with the conventional planningobjectives on two patient cases. Sets of treatment plans with differentlybalanced planning objectives are generated using either the proposed or theconventional approach. Dominance in the sense of better distributeddoses-at-volume is observed in plans optimized within the proposed framework,indicating that the DVH statistics are better optimized and more efficientlybalanced using the proposed planning objectives.