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This paper introduces Inverse Distributionally Robust Optimization (I-DRO) as a method to infer the conservativeness level of a decision-maker, represented by the size of a Wasserstein metric-based ambiguity set, from the optimal decisions…

Optimization and Control · Mathematics 2024-05-07 Qi Li , Zhirui Liang , Andrey Bernstein , Yury Dvorkin

Purpose: To develop a DL-based PBSPT dose prediction workflow with high accuracy and balanced complexity to support on-line adaptive proton therapy clinical decision and subsequent replanning. Methods: PBSPT plans of 103 prostate cancer…

Direct Preference Optimization (DPO) has become a popular method for fine-tuning large language models (LLMs) due to its stability and simplicity. However, it is also known to be sensitive to noise in the data and prone to overfitting.…

Machine Learning · Computer Science 2025-10-28 Cheol Woo Kim , Shresth Verma , Mauricio Tec , Milind Tambe

Anatomical changes during intensity-modulated proton therapy (IMPT) for head-and-neck cancer (HNC) can shift Bragg peaks, risking tumor underdosing and organ-at-risk overdosing. Treatment replanning is often required to maintain clinically…

Medical Physics · Physics 2025-08-13 Malvern Madondo , Yuan Shao , Yingzi Liu , Jun Zhou , Xiaofeng Yang , Zhen Tian

Conventional beam orientation optimization (BOO) algorithms for IMRT assume that the same set of beam angles is used for all treatment fractions. In this paper we present a BOO formulation based on group sparsity that simultaneously…

Medical Physics · Physics 2018-03-14 Daniel O'Connor , Dan Nguyen , Dan Ruan , Victoria Yu , Ke Sheng

This work presents a novel algorithm for impulsive optimal control of linear time-varying systems with the inclusion of input magnitude constraints. Impulsive optimal control problems, where the optimal input solution is a sum of delta…

Optimization and Control · Mathematics 2026-03-17 Ethan Foss , Simone D'Amico

Deep learning (DL) 3D dose prediction has recently gained a lot of attention. However, the variability of plan quality in the training dataset, generated manually by planners with wide range of expertise, can dramatically effect the quality…

Computer Vision and Pattern Recognition · Computer Science 2021-06-08 Navdeep Dahiya , Gourav Jhanwar , Anthony Yezzi , Masoud Zarepisheh , Saad Nadeem

Geometric uncertainty can degrade treatment quality in radiation therapy. While margins and robust optimization mitigate these effects, they provide only implicit control over clinical goal fulfillment probability. We therefore develop a…

Medical Physics · Physics 2026-01-14 Albin Fredriksson , Erik Engwall , Jenneke de Jong , Johan Sundström

Non-coplanar Intensity-Modulated Radiation Therapy (IMRT) goes a step further by orienting the gantry carrying the radiation beam and the patient couch in a non-coplanar manner to accurately target the cancer region and better avoid…

Medical Physics · Physics 2023-05-16 Fang Guo , Franklin Okoli , Ulrike Schick , Dimitris Visvikis , Antoine Valeri , Julien Bert

Distributionally robust optimization (DRO) studies decision problems under uncertainty where the probability distribution governing the uncertain problem parameters is itself uncertain. A key component of any DRO model is its ambiguity set,…

Optimization and Control · Mathematics 2025-05-28 Daniel Kuhn , Soroosh Shafiee , Wolfram Wiesemann

Background: Multi-collimator proton minibeam radiation therapy (MC-pMBRT) has recently emerged as a versatile technique for dose shaping, enabling peak-valley dose patterns in organs-at-risk (OAR) while maintaining a uniform dose…

Medical Physics · Physics 2025-02-25 Nimita Shinde , Weijie Zhang , Yuting Lin , Hao Gao

Instability and slowness are two main problems in deep reinforcement learning. Even if proximal policy optimization (PPO) is the state of the art, it still suffers from these two problems. We introduce an improved algorithm based on…

Machine Learning · Computer Science 2019-10-01 Zhenyu Zhang , Xiangfeng Luo , Tong Liu , Shaorong Xie , Jianshu Wang , Wei Wang , Yang Li , Yan Peng

Traditionally, optimization of radiation therapy (RT) treatment plans has been done before the initiation of RT course, using population-wide estimates for patients' response to therapy. However, recent technological advancements have…

Medical Physics · Physics 2021-02-15 Stefan C. M. ten Eikelder , Ali Ajdari , Thomas Bortfeld , Dick den Hertog

In SLAM (Simultaneous localization and mapping) problems, Pose Graph Optimization (PGO) is a technique to refine an initial estimate of a set of poses (positions and orientations) from a set of pairwise relative measurements. The…

Robotics · Computer Science 2024-08-19 Emilio Olivastri , Alberto Pretto

Dynamic real-time optimization (DRTO) is a challenging task due to the fact that optimal operating conditions must be computed in real time. The main bottleneck in the industrial application of DRTO is the presence of uncertainty. Many…

Predictive models for clinical outcomes that are accurate on average in a patient population may underperform drastically for some subpopulations, potentially introducing or reinforcing inequities in care access and quality. Model training…

Machine Learning · Statistics 2022-02-03 Stephen R. Pfohl , Haoran Zhang , Yizhe Xu , Agata Foryciarz , Marzyeh Ghassemi , Nigam H. Shah

We consider a real-world chemotherapy scheduling template design problem, where we cluster patient types into groups and find a representative time-slot duration for each group to accommodate all patient types assigned to that group, aiming…

Optimization and Control · Mathematics 2025-10-14 Qing Zhu , Xian Yu , Yu-Li Huang

The purpose of this study is to determine whether organ sparing and target coverage can be simultaneously maintained for pencil beam scanning (PBS) proton therapy treatment of thoracic tumors in the presence of motion, stopping power…

Reaching tasks with random targets and obstacles is a challenging task for robotic manipulators. In this study, we propose a novel model-free reinforcement learning approach based on proximal policy optimization (PPO) for training a deep…

Robotics · Computer Science 2023-02-10 Yongliang Wang , Hamidreza Kasaei

Metallic coatings are used to enhance the durability of metal surfaces by protecting them from corrosion. These protective layers are typically deposited in a fluid state via a liquid film. Controlling instabilities in the liquid film is…

Fluid Dynamics · Physics 2026-04-29 Fabio Pino , Edoardo Fracchia , Benoit Scheid , Miguel A. Mendez