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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

Many high-dimensional optimisation problems exhibit rich geometric structures in their set of minimisers, often forming smooth manifolds due to over-parametrisation or symmetries. When this structure is known, at least locally, it can be…

Optimization and Control · Mathematics 2025-10-27 Evan Markou , Thalaiyasingam Ajanthan , Stephen Gould

Proper X-ray radiation design (via dynamic fluence field modulation, FFM) allows to reduce effective radiation dose in computed tomography without compromising image quality. It takes into account patient anatomy, radiation sensitivity of…

Medical Physics · Physics 2024-01-02 Anatoli Juditsky , Arkadi Nemirovski , Michael Zibulevsky

This paper presents a piecewise convexification method for solving non-convex multi-objective optimization problems with box constraints. Based on the ideas of the $\alpha$-based Branch and Bound (${\rm \alpha BB}$) method of global…

Optimization and Control · Mathematics 2022-06-28 Q. Zhu , L. P. Tang , X. M. Yang

Constrained convex optimization problems arise naturally in many real-world applications. One strategy to solve them in an approximate way is to translate them into a sequence of convex feasibility problems via the recently developed level…

Optimization and Control · Mathematics 2019-04-30 E. Bonacker , A. Gibali , K. -H. Küfer

In the treatment plan optimization for intensity modulated radiation therapy (IMRT), dose-deposition coefficient (DDC) matrix is often pre-computed to parameterize the dose contribution to each voxel in the volume of interest from each…

Medical Physics · Physics 2013-03-15 Zhen Tian , Masoud Zarepisheh , Xun Jia , Steve B. Jiang

Constrained quasiconvex optimization problems appear in many fields, such as economics, engineering, and management science. In particular, fractional programming, which models ratio indicators such as the profit/cost ratio as fractional…

Optimization and Control · Mathematics 2019-09-02 Kazuhiro Hishinuma , Hideaki Iiduka

Purpose: To develop a novel aperture-based algorithm for volumetric modulated arc therapy (VMAT) treatment plan optimization with high quality and high efficiency. Methods: The VMAT optimization problem is formulated as a large-scale convex…

Medical Physics · Physics 2015-05-19 Chunhua Men , H. Edwin Romeijn , Xun Jia , Steve B. Jiang

The pooling problem has applications, e.g., in petrochemical refining, water networks, and supply chains and is widely studied in global optimization. To date, it has largely been treated deterministically, neglecting the influence of…

Optimization and Control · Mathematics 2019-06-19 Johannes Wiebe , Inês Cecílio , Ruth Misener

This paper proposes novel algorithm for non-convex multimodal constrained optimisation problems. It is based on sequential solving restrictions of problem to sections of feasible set by random subspaces (in general, manifolds) of low…

Optimization and Control · Mathematics 2023-03-28 Dmitry A. Pasechnyuk , Alexander Gornov

We present a convex optimization framework for overcoming the limitations of Kubernetes Cluster Autoscaler by intelligently allocating diverse cloud resources while minimizing costs and fragmentation. Current Kubernetes scaling mechanisms…

Distributed, Parallel, and Cluster Computing · Computer Science 2025-03-28 Shayan Boghani , Emin Kirimlioglu , Amrita Moturi , Hao-Ting Tso

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

An adaptive regularization algorithm for unconstrained nonconvex optimization is proposed that is capable of handling inexact objective-function and derivative values, and also of providing approximate minimizer of arbitrary order. In…

Optimization and Control · Mathematics 2021-11-30 N. I. M. Gould , Ph. L. Toint

We introduce and study various algorithms for solving nonconvex minimization with inequality constraints, based on the construction of convex surrogate envelopes that majorize the objective and the constraints. In the case where the…

Optimization and Control · Mathematics 2025-06-11 Nuozhou Wang , Junyu Zhang , Shuzhong Zhang

Radiotherapy planning naturally leads to a multi-criteria optimization problem which is subject to different sources of uncertainty. In order to find the desired treatment plan, a decision maker must balance these objectives as well as the…

Optimization and Control · Mathematics 2026-01-27 Jan Schröeder , Yair Censor , Philipp Süss , Karl-Heinz Küfer

This paper presents a novel convex optimization-based method for finding the globally optimal solutions of a class of mixed-integer non-convex optimal control problems. We consider problems with non-convex constraints that restrict the…

Optimization and Control · Mathematics 2019-11-21 Danylo Malyuta , Behcet Acikmese

In this paper, we present a novel nonlinear programming-based approach to fine-tune pre-trained neural networks to improve robustness against adversarial attacks while maintaining high accuracy on clean data. Our method introduces…

Machine Learning · Computer Science 2024-10-28 Shudian Zhao , Jan Kronqvist

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

To accurately verify the dose of intensity-modulated radiation therapy (IMRT), we have used a global optimization method to investigate a new dose-verification algorithm. In practical application of this quality assurance (QA) procedure,…

Medical Physics · Physics 2007-05-23 Dong Hyun Park , Sung-Yong Park , Dahl Park , Tae-Hyun Kim , Kyung Hwan Shin , Dae Yong Kim , Kwan-Ho Cho

Spatiotemporal fractionation schemes, that is, treatments delivering different dose distributions in different fractions, may lower treatment side effects without compromising tumor control. This is achieved by hypofractionating parts of…

Medical Physics · Physics 2018-02-14 Melissa R. Gaddy , Sercan Yıldız , Jan Unkelbach , Dávid Papp