Research on robust optimization method of intensity-modulated proton therapy
Han Rongcheng1,2, Pu Yuehu3,4, Kong Haiyun1, Li Xiufang3, Wu Chao1,2
1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; 2University of Chinese Academy of Sciences, Beijing 100049, China; 3Shanghai APACTRON Particle Equipment Co., Ltd, Shanghai 201800, China; 4Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
Abstract：Objective To propose a new robust optimization method, known as modified worst case method, was proposed, which can enable users to control the trade-off between nominal plan quality and plan robustness. Methods In each iteration of the plan optimization process, the dose value of each voxel in nine scenarios, which corresponded to a nominal scenario and eight perturbed scenarios with range or set-up uncertainties, were calculated and the maximum of deviations of each scenario voxel dose from that of the nominal scenario was included as an additive robust optimization term in the Objective function. A weighting factor probust was used to this robust optimization term to balance the nominal plan quality and plan robustness. Results The robust optimization methods were implemented and compared in an in-house developed robust optimization module. When probust=0.8, compared with conventional optimization, the ΔD95% of CTV was reduced from 9.8 Gy to 7.6 Gy. When probust was reduced from 1 to 0, ΔD95% was increased from 7.0 Gy to 9.8 Gy, whereas the D95% and Dmax of CTV, and the D5% and Dmax of organs at risk (OAR) in the nominal scenario were reduced. Conclusions The proposed modified worst case method can effectively improve the robustness of the plan to the range and set-up uncertainties. Besides, the weighting factor probust in this method can be adopted to control the trade-off between nominal plan quality and plan robustness.
Han Rongcheng,Pu Yuehu,Kong Haiyun et al. Research on robust optimization method of intensity-modulated proton therapy[J]. Chinese Journal of Radiation Oncology, 2020, 29(10): 888-893.
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2020, Vol. 29 
