Development of intensity-modulated radiation therapy treatment planning by actively utilizing nonlinear dynamics

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04169
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21030:Measurement engineering-related
• Research Institution: The University of Tokushima
• Principal Investigator: YOSHINAGA Tetsuya 徳島大学, 大学院医歯薬学研究部(医学域), 教授 (40220694)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 強度変調放射線治療計画 / 最適化問題 / 微分方程式 / 非線形問題

Outline of Final Research Achievements

We give a novel approach for obtaining an intensity-modulated radiation therapy (IMRT) optimization solution. The proposed method can handle not only dose-volume but also mean-dose constraints directly in IMRT treatment planning. A theoretical proof for the convergence to an equilibrium corresponding to the desired IMRT planning is given. By introducing the concept of acceptable and by using the proposed method for an acceptable IMRT planning, one can resolve the issue that the objective and evaluation are different in the conventional planning process. Moreover, in the case where the target planning is totally unacceptable and partly acceptable except for one group of dose constraints, we give a procedure that enables us to obtain a nearly optimal solution close to the desired solution for unacceptable planning. The performance of the proposed approach for an acceptable or unacceptable planning is confirmed through numerical experiments simulating a clinical setup.

Free Research Field

医用工学

Academic Significance and Societal Importance of the Research Achievements

強度変調放射線治療は，少ない副作用で高い効果が得られる がん治療法として高精度化が期待されている．本研究において，腫瘍組織には高い線量を正確に照射し，正常組織にはより少ない線量に抑えることが可能となる新しい演算法を考案した．従来法の課題であった線量制約条件を再設定して演算を繰り返す試行錯誤の手続きが無くなり，線量体積制約を直接の評価関数とした逆問題に基づく高精度な治療計画法が開発できた．