Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment Planning

The conventional approach to intensity-modulated radiation therapy treatment planning involves two distinct strategies: optimizing an evaluation function while accounting for dose constraints, and solving feasibility problems using feasibility-seeking projection methods that incorporate inequality c...

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Main Authors: Norihisa Obata, Omar M. Abou Al-Ola, Ryosei Nakada, Takeshi Kojima, Tetsuya Yoshinaga
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Mathematics
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Online Access:https://www.mdpi.com/2227-7390/12/23/3826
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author Norihisa Obata
Omar M. Abou Al-Ola
Ryosei Nakada
Takeshi Kojima
Tetsuya Yoshinaga
author_facet Norihisa Obata
Omar M. Abou Al-Ola
Ryosei Nakada
Takeshi Kojima
Tetsuya Yoshinaga
author_sort Norihisa Obata
collection DOAJ
description The conventional approach to intensity-modulated radiation therapy treatment planning involves two distinct strategies: optimizing an evaluation function while accounting for dose constraints, and solving feasibility problems using feasibility-seeking projection methods that incorporate inequality constraints. This paper introduces a novel iterative scheme within the framework of continuous dynamical systems, wherein constraint conditions dynamically evolve to enhance the optimization process. The validity of dynamically varying dose constraints is theoretically established through the foundation of continuous-time dynamical systems theory. In particular, we formalize a system of differential equations, with both beam coefficients and dose constraints modeled as state variables. The asymptotic stability of the system’s equilibrium is rigorously proven, ensuring convergence to a solution. In practical terms, we leverage a discretized iteration formula derived from the continuous-time system to achieve rapid computational speed. The mathematical structure of the proposed approach, which directly incorporates dose-volume constraints into the objective function, facilitates significant computational efficiency and solution refinement. The proposed method has an inherent dynamics that approaches more desirable solutions within the set of solutions when the solution to the optimization problem is not an isolated point. This property guarantees the identification of optimal solutions that respect the prescribed dose-volume constraints while enhancing accuracy when such constraints are feasible. By treating dose constraints as variables and concurrently solving the optimization problem with beam coefficients, we can achieve more accurate results when compared with using fixed values for prescribed dose conditions.
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spelling doaj-art-d69b3f37e00b49ffa34f1e719a5ec6ad2024-12-13T16:27:53ZengMDPI AGMathematics2227-73902024-12-011223382610.3390/math12233826Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment PlanningNorihisa Obata0Omar M. Abou Al-Ola1Ryosei Nakada2Takeshi Kojima3Tetsuya Yoshinaga4Graduate School of Health Sciences, Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8509, JapanFaculty of Science, Tanta University, El-Giesh St., Tanta 31527, EgyptRadiation & Proton Therapy Office, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi 411-8777, JapanInstitute of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8509, JapanInstitute of Biomedical Sciences, Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8509, JapanThe conventional approach to intensity-modulated radiation therapy treatment planning involves two distinct strategies: optimizing an evaluation function while accounting for dose constraints, and solving feasibility problems using feasibility-seeking projection methods that incorporate inequality constraints. This paper introduces a novel iterative scheme within the framework of continuous dynamical systems, wherein constraint conditions dynamically evolve to enhance the optimization process. The validity of dynamically varying dose constraints is theoretically established through the foundation of continuous-time dynamical systems theory. In particular, we formalize a system of differential equations, with both beam coefficients and dose constraints modeled as state variables. The asymptotic stability of the system’s equilibrium is rigorously proven, ensuring convergence to a solution. In practical terms, we leverage a discretized iteration formula derived from the continuous-time system to achieve rapid computational speed. The mathematical structure of the proposed approach, which directly incorporates dose-volume constraints into the objective function, facilitates significant computational efficiency and solution refinement. The proposed method has an inherent dynamics that approaches more desirable solutions within the set of solutions when the solution to the optimization problem is not an isolated point. This property guarantees the identification of optimal solutions that respect the prescribed dose-volume constraints while enhancing accuracy when such constraints are feasible. By treating dose constraints as variables and concurrently solving the optimization problem with beam coefficients, we can achieve more accurate results when compared with using fixed values for prescribed dose conditions.https://www.mdpi.com/2227-7390/12/23/3826dynamical systempiecewise-smooth systemoptimizationintensity-modulated radiation therapystability of equilibrium
spellingShingle Norihisa Obata
Omar M. Abou Al-Ola
Ryosei Nakada
Takeshi Kojima
Tetsuya Yoshinaga
Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment Planning
Mathematics
dynamical system
piecewise-smooth system
optimization
intensity-modulated radiation therapy
stability of equilibrium
title Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment Planning
title_full Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment Planning
title_fullStr Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment Planning
title_full_unstemmed Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment Planning
title_short Variable Dose-Constraints Method for Enhancing Intensity-Modulated Radiation Therapy Treatment Planning
title_sort variable dose constraints method for enhancing intensity modulated radiation therapy treatment planning
topic dynamical system
piecewise-smooth system
optimization
intensity-modulated radiation therapy
stability of equilibrium
url https://www.mdpi.com/2227-7390/12/23/3826
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AT omarmaboualola variabledoseconstraintsmethodforenhancingintensitymodulatedradiationtherapytreatmentplanning
AT ryoseinakada variabledoseconstraintsmethodforenhancingintensitymodulatedradiationtherapytreatmentplanning
AT takeshikojima variabledoseconstraintsmethodforenhancingintensitymodulatedradiationtherapytreatmentplanning
AT tetsuyayoshinaga variabledoseconstraintsmethodforenhancingintensitymodulatedradiationtherapytreatmentplanning