A multicriteria framework with voxel‐dependent parameters for radiotherapy treatment plan optimization. Issue 4 (19th March 2014)

• Record Type: Journal Article
• Authors: Zarepisheh, Masoud; Uribe‐Sanchez, Andres F.; Li, Nan; Jia, Xun; Jiang, Steve B.
• Is Part Of: Medical physics. Volume 41:Issue 4(2014)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2014-03-19
• Subjects: Optimization -- Dose‐volume analysis -- Quality assurance in radiotherapy -- Numerical optimization; biological organs -- dosimetry -- mathematical analysis -- medical computing -- Pareto optimisation -- physiological models -- radiation therapy; treatment planning -- intensity modulation -- optimization -- Pareto surface -- voxel‐dependent parameters; Radiation therapy -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Scintigraphy; Dosimetry -- Anatomy -- Signal generators -- Medical treatment planning -- Surface treatments -- Radiation therapy -- Optimization -- Cancer -- Intensity modulated radiation therapy -- Radiation treatment; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4866886
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: : To establish a new mathematical framework for radiotherapy treatment optimization with voxel‐dependent optimization parameters. Methods: : In the treatment plan optimization problem for radiotherapy, a clinically acceptable plan is usually generated by an optimization process with weighting factors or reference doses adjusted for a set of the objective functions associated to the organs. Recent discoveries indicate that adjusting parameters associated with each voxel may lead to better plan quality. However, it is still unclear regarding the mathematical reasons behind it. Furthermore, questions about the objective function selection and parameter adjustment to assure Pareto optimality as well as the relationship between the optimal solutions obtained from the organ‐based and voxel‐based models remain unanswered. To answer these questions, the authors establish in this work a new mathematical framework equipped with two theorems. Results: : The new framework clarifies the different consequences of adjusting organ‐dependent and voxel‐dependent parameters for the treatment plan optimization of radiation therapy, as well as the impact of using different objective functions on plan qualities and Pareto surfaces. The main discoveries are threefold: (1) While in the organ‐based model the selection of the objective function has an impact on the quality of the optimized plans, this is no longer an issue for the voxel‐based model since the Pareto surface is independent of the objective function selection and the entire Pareto surface could be generated as long as the objective function satisfies certain mathematical conditions; (2) All Pareto solutions generated by the organ‐based model with different objective functions are parts of a unique Pareto surface generated by the voxel‐based model with any appropriate objective function; (3) A much larger Pareto surface is explored by adjusting voxel‐dependent parameters than by adjusting organ‐dependent parameters, possibly allowing for the generation of plans with better trade‐offs among different clinical objectives. Conclusions: : The authors have developed a mathematical framework for radiotherapy treatment optimization using voxel‐based parameters. The authors can improve the plan quality by adjusting voxel‐based weighting factors and exploring the unique and large Pareto surface which include all the Pareto surfaces that can be generated by organ‐based model using different objective functions.