Open AccessAnalysis of RapidArc optimization strategies using objective function values and dose‐volume histograms
Author(s) -
Oliver Mike,
Gagne Isabelle,
Popescu Carmen,
Ansbacher Will,
Beckham Wayne A.
Publication year - 2009
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1120/jacmp.v11i1.3114
Subject(s) - volume (thermodynamics) , nuclear medicine , dose volume histogram , histogram , medical physics , medicine , mathematics , computer science , radiology , radiation therapy , physics , radiation treatment planning , artificial intelligence , quantum mechanics , image (mathematics)
RapidArc is a novel treatment planning and delivery system that has recently been made available for clinical use. Included within the Eclipse treatment planning system are a number of different optimization strategies that can be employed to improve the quality of the final treatment plan. The purpose of this study is to systematically assess three categories of strategies for four phantoms, and then apply proven strategies to clinical head and neck cases. Four phantoms were created within Eclipse with varying shapes and locations for the planning target volumes and organs at risk. A baseline optimization consisting of a single 359.8° arc with collimator at 45° was applied to all phantoms. Three categories of strategies were assessed and compared to the baseline strategy. They include changing the initialization parameters, increasing the total number of control points, and increasing the total optimization time. Optimization log files were extracted from the treatment planning system along with final dose‐volume histograms for plan assessment. Treatment plans were also generated for four head and neck patients to determine whether the results for phantom plans can be extended to clinical plans. The strategies that resulted in a significant difference from baseline were: changing the maximum leaf speed prior to optimization ( p < 0.05 ) , increasing the total number of segments by adding an arc ( p < 0.05 ) , and increasing the total optimization time by either continuing the optimization ( p < 0.01 ) or adding time to the optimization by pausing the optimization ( p < 0.01 ) . The reductions in objective function values correlated with improvements in the dose‐volume histogram (DVH). The addition of arcs and pausing strategies were applied to head and neck cancer cases, which demonstrated similar benefits with respect to the final objective function value and DVH. Analysis of the optimization log files is a useful way to intercompare treatment plans that have the same dose‐volume objectives and importance values. The results for clinical head and neck plans were consistent with phantom plans. PACS number: 87.55.x, 87.55.D, 87.55.de 87.55.dk