Quantitative comparison of automatic and manual IMRT optimization for prostate cancer: the benefits of DVH prediction

摘要

A recent publication indicated that the patient anatomical feature (PAF) model was capable of predicting optimal objectives based on past experience. In this study, the benefits of IMRT optimization using PAF-predicted objectives as guidance for prostate were evaluated. Three different optimization methods were compared. 1) Expert Plan: Ten prostate cases (16 plans) were planned by an expert planner using conventional trial-and-error approach started with institutional modified OAR and PTV constraints. Optimization was stopped at 150 iterations and that plan was saved as Expert Plan. 2) Clinical Plan: The planner would keep working on the Expert Plan till he was satisfied with the dosimetric quality and the final plan was referred to as Clinical Plan. 3) PAF Plan: A third sets of plans for the same ten patients were generated fully automatically using predicted DVHs as guidance. The optimization was based on PAF-based predicted objectives, and was continued to 150 iterations without human interaction. D MAX and D 98 % for PTV, D MAX for femoral heads, D MAX , D_10cc, D 25 % / D 17 % , and D 40 % for bladder/rectum were compared. Clinical Plans are further optimized with more iterations and adjustments, but in general provided limited dosimetric benefits over Expert Plans. PTV D 98 % agreed within 2.31% among Expert, Clinical, and PAF plans. Between Clinical and PAF Plans, differences for D MAX of PTV, bladder, and rectum were within 2.65%, 2.46%, and 2.20%, respectively. Bladder D_10cc was higher for PAF but 1.54 % in general. Bladder D 25 % and D 40 % were lower for PAF, by up to 7.71% and 6.81%, respectively. Rectum D_10cc, D 17 % , and D 40 % were 2.11%, 2.72%, and 0.27% lower for PAF, respectively. D MAX for femoral heads were comparable ( 35 Gy on average). Compared to Clinical Plan ( Primary + Boost ), the average optimization time for PAF plan was reduced by 5.2 min on average, with a maximum reduction of 7.1 min. Total numbers of MUs per plan for PAF Plans were lower than Clinical Plans, indicating better delivery efficiency. The PAF-guided planning process is capable of generating clinical-quality prostate IMRT plans with no human intervention. Compared to manual optimization, this automatic optimization increases planning and delivery efficiency, while maintaining plan quality.PACS numbers: 87.55.D-, 87.55.de, 87.53.Jw