@article{Kishimoto2017, title = "A successive {LP} approach with {C}-{V}a{R} type constraints for {IMRT} optimization ", journal = "Operations Research for Health Care ", volume = "", number = "", pages = " - ", year = "2017", note = "", issn = "2211-6923", doi = "https://doi.org/10.1016/j.orhc.2017.09.007", url = "https://www.sciencedirect.com/science/article/pii/S2211692316301631", author = "Shogo Kishimoto and Makoto Yamashita", keywords = "Intensity-modulated radiotherapy treatment", keywords = "Fluence map optimization", keywords = "Linear programming", keywords = "Conditional value-at-risk ", abstract = "Abstract In this paper, we propose a successive linear programming (LP) approach for an intensity-modulated radiotherapy treatment (IMRT) optimization. The use of \{IMRT\} enables to control the beam intensities accurately and gives more flexibility for cancer treatment plans, but finding a feasible plan that satisfies all dose-volume constraints (DVCs) requires expensive computation cost. Romeijn et al. (2003) replaced the \{DVCs\} with C-VaR (conditional Value-at-Risk) type constraints, and successfully reduced this computation cost. However, the feasible region of the \{LP\} problem was small compared to the original DVCs, therefore, their approach often failed to find a feasible plan even when the \{DVCs\} were not so stringent. In the proposed method, we integrate the C-VaR type constraints with a successive \{LP\} approach. Exploiting the solution of \{LP\} problems, we automatically detect outliers and remove them from the domain of the C-VaR type constraints. This reduces the sensitivity of the C-VaR type constraints to outliers, therefore, we can search feasible plans in a wider region than the C-VaR type constraints. We give a mathematical proof that if the optimal value of an \{LP\} problem in the proposed method is non-positive, the corresponding optimal solution satisfies all the DVCs. From a numerical experiment on test data sets, we observed that the proposed method found feasible solutions more appropriately than existing successive \{LP\} approaches. Moreover, the proposed method required fewer \{LP\} problems, and this was reflected in a short computation time. " } @article{yang2017arc, title={An arc-search $\mathcal{O}(n{L})$ infeasible-interior-point algorithm for linear programming}, author={Yang, Yaguang and Yamashita, Makoto}, journal={Optimization Letters}, pages={1--18}, year={2017}, publisher={Springer} } @article{safarina2017conic, title={Conic relaxation approaches for equal deployment problems}, author={Safarina, Sena and Moriguchi, Satoko and Mullin, Tim J and Yamashita, Makoto}, journal={arXiv preprint arXiv:1703.03155}, year={2017} }