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Designing RNA sequences that reliably adopt specified three-dimensional structures while maintaining thermodynamic stability remains challenging for synthetic biology and therapeutics. Current inverse folding approaches optimize for…

Trust Region Policy Optimization (TRPO) and Proximal Policy Optimization (PPO), as the widely employed policy based reinforcement learning (RL) methods, are prone to converge to a sub-optimal solution as they limit the policy representation…

Machine Learning · Computer Science 2020-06-16 Jun Song , Chaoyue Zhao

Despite Proximal Policy Optimization (PPO) dominating policy gradient methods -- from robotic control to game AI -- its static trust region forces a brittle trade-off: aggressive clipping stifles early exploration, while late-stage updates…

Machine Learning · Computer Science 2025-05-26 Ben Rahman

Multi-Agent Proximal Policy Optimization (MAPPO) is a variant of the Proximal Policy Optimization (PPO) algorithm, specifically tailored for multi-agent reinforcement learning (MARL). MAPPO optimizes cooperative multi-agent settings by…

Machine Learning · Computer Science 2026-05-14 Changha Lee , Gyusang Cho

Automating the radiotherapy treatment planning process is a technically challenging problem. The majority of automated approaches have focused on customizing and inferring dose volume objectives to used in plan optimization. In this work we…

Medical Physics · Physics 2017-01-04 Chris McIntosh , Thomas G. Purdie

Purpose: LATTICE, a form of spatially fractionated radiation therapy that delivers high-dose peaks and low-dose valleys within the target, has been clinically utilized for treating bulky tumors. However, its application to…

Medical Physics · Physics 2025-09-08 Nimita Shinde , Weijie Zhang , Yuting Lin , Hao Gao

Purpose: Accurate segmentation of clinical target volumes (CTV) and organs-at-risk is crucial for optimizing gynecologic brachytherapy (GYN-BT) treatment planning. However, anatomical variability, low soft-tissue contrast in CT imaging, and…

Computer Vision and Pattern Recognition · Computer Science 2025-06-03 Mingzhe Hu , Yuan Gao , Yuheng Li , Ricahrd LJ Qiu , Chih-Wei Chang , Keyur D. Shah , Priyanka Kapoor , Beth Bradshaw , Yuan Shao , Justin Roper , Jill Remick , Zhen Tian , Xiaofeng Yang

In this paper, we develop a high order residual distribution (RD) method for solving steady state conservation laws in a novel Hermite weighted essentially non-oscillatory (HWENO) framework recently developed in [24]. In particular, we…

Numerical Analysis · Mathematics 2022-03-14 Jianfang Lin , Yupeng Ren , Rémi Abgrall , Jianxian Qiu

We present a method of directly optimizing on deviations in clinical goal values in radiation therapy treatment planning. Using a new mathematical framework in which metrics derived from the dose-volume histogram are regarded as functionals…

Medical Physics · Physics 2021-09-07 Tianfang Zhang , Rasmus Bokrantz , Jimmy Olsson

Bayesian Optimization (BO) is a common solution to search optimal hyperparameters based on sample observations of a machine learning model. Existing BO algorithms could converge slowly even collapse when the potential observation noise…

Computer Vision and Pattern Recognition · Computer Science 2022-10-10 Lei Cui , Yangguang Li , Xin Lu , Dong An , Fenggang Liu

Medical steerable needles can follow 3D curvilinear trajectories inside body tissue, enabling them to move around critical anatomical structures and precisely reach clinically significant targets in a minimally invasive way. Automating…

Robotics · Computer Science 2022-03-01 Mengyu Fu , Kiril Solovey , Oren Salzman , Ron Alterovitz

Precise needle alignment is essential for percutaneous needle insertion in robotic ultrasound-guided procedures. However, inherent challenges such as speckle noise, needle-like artifacts, and low image resolution make robust needle…

Numerical modeling of localizations is a challenging task due to the evolving rough solution in which the localization paths are not predefined. Despite decades of efforts, there is a need for innovative discretization-independent…

Computational Engineering, Finance, and Science · Computer Science 2023-07-06 Jonghyuk Baek , Jiun-Shyan Chen

Deep reinforcement learning (DRL) is one of the promising approaches for introducing robots into complicated environments. The recent remarkable progress of DRL stands on regularization of policy, which allows the policy to improve stably…

Machine Learning · Computer Science 2023-07-04 Taisuke Kobayashi

Prostate brachytherapy involves implanting radioactive seeds (I125 for instance) permanently in the gland for the treatment of localized prostate cancers, e.g., cT1c-T2a N0 M0 with good prognostic factors. Treatment planning and seed…

Precise patient positioning is fundamental to successful removal of malignant tumors during treatment of head and neck cancers. Errors in patient positioning have been known to damage critical organs and cause complications. To better…

Robotics · Computer Science 2017-09-26 Olalekan Ogunmolu , Adwait Kulkarni , Yonas Tadesse , Xuejun Gu , Steve Jiang , Nicholas Gans

In the past decades mathematical optimization has found its way into radiation therapy and has made profound practice changing impact. Today, virtually all advanced treatment delivery methods, such as IMRT, VMAT, tomotherapy, LDR/HDR…

Medical Physics · Physics 2018-10-31 Bram L. Gorissen , Jan Unkelbach , Thomas R. Bortfeld

In many applied optimization settings, parameters that define the constraints may not guarantee the best possible solution, and superior solutions might exist that are infeasible for the given parameter values. Removing such constraints,…

Optimization and Control · Mathematics 2024-07-22 Farzin Ahmadi , Todd R. McNutt , Kimia Ghobadi

Beam angle optimization (BAO) largely determines the performance of fixed-field intensity modulated radiation therapy (IMRT), and it is usually considered as non-convex optimization and an NP hard problem. In this work, BAO is reformulated…

Medical Physics · Physics 2021-05-12 Junbo Peng , Ailin Wu , Lei Zhu

Stereotactic body radiation therapy (SBRT) refers to focusing high-energy rays in three-dimensional space on the tumor lesion area, reducing the dose received by surrounding normal tissues, which can effectively improve the local control…

Medical Physics · Physics 2024-02-27 Yanqi Zong , Zhengrong Cui , Luqi Lin , Sihao Wang , Yizhi Chen
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