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Dosimetric analysis of beam number variations in IMRT for head-and-neck, breast, and pelvic cancers using Halcyon

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Radiation Physics and Chemistry 2025年 236卷

作者： Phat, Luong Tien Thao, Mai Thi Kien, Tran Trung Tai, Duong Thanh Sandwall, Peter Sulieman, Abdelmoneim Tamam, Nissren Yani, Sitti Chow, James C.L. Department of Radiation Oncology University Medical Shing Mark Hospital Viet Nam Department of Radiation Oncology Phuc Thinh General Hospital Viet Nam Department of Medical Physics Faculty of Medicine Nguyen Tat Thanh University Viet Nam Department of Radiation Oncology OhioHealth Mansfield OH United States Department of Radiological Sciences College of Applied Medical Sciences King Saud Bin Abdulaziz University for Health Sciences Al Ahsa Saudi Arabia Imaging Physics Section Research and Innovation Department King Faisal Specialist Hospital & Research Center Riyadh Saudi Arabia Department of Physics College of Science Princess Nourah bint Abdulrahman University P.O Box 84428 Riyadh11671 Saudi Arabia Department of Physics Faculty of Mathematics and Natural Sciences IPB University Jalan Meranti Kampus IPB Dramaga Bogor16680 Indonesia Department of Radiation Oncology University of Toronto Toronto Canada Radiation Medicine Program Princess Margaret Cancer Centre University Health Network Toronto Canada

This study investigated the dosimetric effects of varying beam numbers (9, 11, and 13) in intensity-modulated radiation therapy (IMRT) using the Halcyon linear accelerator at ShingMark University Hospital. IMRT plans for 27 patients with head-and-neck, breast, and pelvic cancers were evaluated according to the RTOG 0615 protocol, focusing on Planning Target Volume (PTV) dose coverage, uniformity, maximum and minimum doses, and Organ-at-Risk (OAR) dose constraints. For breast cancer, the 11-beam plan improved PTV coverage (V50Gy: 97.9 ± 0.5 %) and reduced maximum dose compared to 9- and 13-beam plans, while the 13-beam plan lowered heart mean dose by up to 10.5 % in left breast cases. In pelvic cases, the 13-beam plan enhanced OAR sparing, reducing bowel V35Gy by 10.5 % compared to the 9-beam plan, with minimal PTV coverage differences ( © 2025 The Authors

关键词： Diseases

Computational Design of Anisotropic Stealthy Hyperuniform Composites with Engineered Directional Scattering Properties

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arXiv 2023年

作者： Shi, Wenlong Keeney, David Chen, Duyu Jiao, Yang Torquato, Salvatore Materials Science and Engineering Arizona State University TempeAZ85287 United States Materials Research Laboratory University of California Santa BarbaraCA93106 United States Department of Physics Arizona State University TempeAZ85287 United States Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Physics Princeton University PrincetonNJ08544 United States Princeton Institute of Materials Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Disordered hyperuniform materials are an emerging class of exotic amorphous states of matter that endow them with singular physical properties, including large isotropic photonic band gaps, superior resistance to fracture, and nearly optimal electrical and thermal transport properties, to name but a few. Here, we generalize the Fourier-space based numerical construction procedure for designing and generating digital realizations of isotropic disordered hyperuniform two-phase heterogeneous materials (i.e., composites) developed by Chen and Torquato [Acta Mater. 142, 152 (2018)] to anisotropic microstructures with targeted spectral densities. Our generalized construction procedure explicitly incorporates the vector-dependent spectral density function χ˜V (k) of arbitrary form that is realizable. We demonstrate the utility of the procedure by generating a wide spectrum of anisotropic stealthy hyperuniform (SHU) microstructures with χ˜V (k) = 0 for k ∈ Ω, i.e., complete suppression of scattering in an "exclusion" region Ω around the origin in the Fourier space. We show how different exclusion-region shapes with various discrete symmetries, including circular-disk, elliptical-disk, square, rectangular, butterfly-shaped and lemniscate-shaped regions of varying size, affect the resulting statistically anisotropic microstructures as a function of the and phase volume fraction. The latter two cases of Ω lead to directionally hyperuniform composites, which are stealthy hyperuniform only along certain directions, and are non-hyperuniform along others. We find that, while the circular-disk exclusion regions give rise to isotropic hyperuniform composite microstructures, the directional hyperuniform behaviors imposed by the shape asymmetry (or anisotropy) of certain exclusion regions give rise to distinct anisotropic structures and degree of uniformity in the distribution of the phases on intermediate and large length scales along different directions. Moreover, while the anisotr

关键词： Volume fraction

Prediction and Prevention of Pandemics via Graphical Model Inference and Convexprogramming

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Research Square

Research Square 2021年

作者： Krechetov, Mikhail Sikaroudi, Amir Mohammad Esmaieeli Efrat, Alon Polishchuk, Valentin Chertkov, Michael Skolkovo Institute of Science and Technology Center for Energy Science and Technology Moscow121205 Russia University of Arizona Department of Computer Science TucsonAZ85721 United States University of Arizona Program in Applied Mathematics TucsonAZ85721 United States Linkoping Univeristy Communications and Transport Systems Norrkoping60174 Sweden University of Arizona Department of Mathematics TucsonAZ85721 United States

Hard-to-predict bursts of COVID-19 pandemic revealed significance of statistical modeling which would resolve spatio-temporal correlations over geographical areas, for example spread of the infection over a city with census tract granularity. In this manuscript, we provide algorithmic answers to the following two inter-related public health challenges of immense social impact which have not been adequately addressed (1) Inference Challenge: assuming that there are N census blocks (nodes) in the city, and given an initial infection at any set of nodes, e.g. any N of possible single node infections, any N(N−1)/2 of possible two node infections, etc, what is the probability for a subset of census blocks to become infected by the time the spread of the infection burst is stabilized? (2) Prevention Challenge: What is the minimal control action one can take to minimize the infected part of the stabilized state footprint? To answer the challenges, we build a Graphical Model of pandemic of the attractive Ising (pair-wise, binary) type, where each node represents a census track and each edge factor represents the strength of the pairwise interaction between a pair of nodes, e.g. representing the inter-node travel, road closure and related, and each local bias/field represents the community level of immunization, acceptance of the social distance and mask wearing practice, etc. Resolving the Inference Challenge requires finding the Maximum-A-Posteriory (MAP), i.e. most probable, state of the Ising Model constrained to the set of initially infected nodes. (An infected node is in the +1 state and a node which remained safe is in the −1 state.) We show that almost all attractive Ising Models on dense graphs result in either of the two possibilities (modes) for the MAP state: either all nodes which were not infected initially became infected, or all the initially uninfected nodes remain uninfected (susceptible). This bi-modal solution of the Inference Challenge allows us to re-st

关键词： Ising model

Fault Diagnosis of Wind Energy Conversion Systems Using Gaussian Process Regression-based Multi-Class Random Forest

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IFAC-PapersOnLine 2022年第6期55卷 127-132页

作者： Majdi Mansouri Radhia Fezai Mohamed Trabelsi Hajji Mansour Hazem Nounou Mohamed Nounou Electrical and Computer Engineering Program Texas A&M University at Qatar Doha Qatar Department of Mathematics and Sciences Prince Sultan University Riyadh 11586 Saudi Arabia Research Laboratory of Automation Signal Processing and Image National Engineering School of Monastir 5019 Tunisia Electronic and Communications Engineering Department Kuwait College of Science and Technology P. O. Box 27235 Kuwait Higher Institute of Applied Science and Technology of Kasserine University of Kairouan PO Box 471 1200 Kasserine Tunisia Chemical Engineering Program Texas A&M University at Qatar Doha Qatar

This work proposes a new fault diagnosis approach for a wind energy conversion (WEC) system. The proposed technique merges the benefits of feature extraction based on Gaussian Process Regression (GPR) and Multi-Class Random Forest (MCRF)-based fault classification where instances are classified into one or more classes. In the developed GPR-MCRF approach, the nonlinear statistical features including the mean vector M GPR and the variance matrix C GPR are computed using the GPR model with aim of extracting the most relevant features from the WEC system. Then, these features are introduced to the RF classifier for classification and diagnosis purposes. Therefore, the application of the GPR-MCRF technique for WEC systems aims to enhance the use of the classical raw data-based MCRF and diagnosis accuracy. Three kinds of faults (wear-out, open-circuit, and short-circuit faults) are considered in this work. Different case studies are investigated in order to illustrate the effectiveness and robustness of the developed technique compared to the state-of-the-art methods. The obtained results show that the the developed GPR-MCRF technique is an effective feature extraction and fault diagnosis technique for WEC systems.

关键词： Random Forest (RF) Multi-Class Gaussian Process Regression (GPR) Fault Diagnosis Wind Energy Conversion Systems

Superconductivity with High Upper Critical Field in the Cubic Centrosymmetric η-Carbide

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arXiv 2021年

作者： Ma, KeYuan Gornicka, Karolina Lefèvre, Robin Yang, Yikai Rønnow, Henrik M. Jeschke, Harald O. Klimczuk, Tomasz von Rohr, Fabian O. Department of Chemistry University of Zurich ZürichCH-8057 Switzerland Faculty of Applied Physics and Mathematics Gdansk University of Technology Gdansk80-233 Poland LausanneCH-1015 Switzerland Research Institute for Interdisciplinary Science Okayama University Okayama700-8530 Japan

The upper critical field is a fundamental measure of the strength of superconductivity in a material. It is also a cornerstone for the realization of superconducting magnet applications. The critical field arises because of the Copper pair breaking at a limiting field, which is due to the Pauli paramagnetism of the electrons. The maximal possible magnetic field strength for this effect is commonly known as the Pauli paramagnetic limit given as µ0HPauli ≈ 1.86[T/K]·Tc for a weak-coupling BCS superconductor. The violation of this limit is only rarely observed. Exceptions include some low-temperature heavy fermion and some strongly anisotropic superconductors. Here, we report on the superconductivity at 9.75 K in the centrosymmetric, cubic η-carbide-type compound Nb4Rh2C1-δ, with a normalized specific heat jump of ∆C/γTc = 1.64. We find that this material has a remarkably high upper critical field of µ0Hc2(0) = 28.5 T, which is exceeding by far its weak-coupling BCS Pauli paramagnetic limit of µ0HPauli = 18.1 T. Determination of the origin and consequences of this effect will represent a significant new direction in the study of critical fields in superconductors. Copyright © 2021, The Authors. All rights reserved.

关键词： Carbides

Overlapping Schwarz methods with GenEO coarse spaces for indefinite and non-self-adjoint problems

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arXiv 2021年

作者： Bootland, Niall Dolean, Victorita Graham, Ivan G. Ma, Chupeng Scheichl, Robert Department of Mathematics and Statistics University of Strathclyde GlasgowG1 1XH United Kingdom Laboratoire J.A. Dieudonné CNRS University Côte d’Azur Nice06108 France Department of Mathematical Sciences University of Bath BathBA2 7AY United Kingdom Institute for Applied Mathematics Interdisciplinary Center for Scientific Computing Heidelberg University Heidelberg69120 Germany

GenEO (‘Generalised Eigenvalue problems on the Overlap’) is a method for computing an operator-dependent spectral coarse space to be combined with local solves on subdomains to form a robust parallel domain decomposition preconditioner for elliptic PDEs. It has previously been proved, in the self-adjoint and positive-definite case, that this method, when used as a preconditioner for conjugate gradients, yields iteration numbers which are completely independent of the heterogeneity of the coefficient field of the partial differential operator. We extend this theory to the case of convection–diffusion–reaction problems, which may be non-self-adjoint and indefinite, and whose discretisations are solved with preconditioned GMRES. The GenEO coarse space is defined here using a generalised eigenvalue problem based on a self-adjoint and positive-definite subproblem. We prove estimates on GMRES iteration counts which are independent of the variation of the coefficient of the diffusion term in the operator and depend only very mildly on variations of the other coefficients. These are proved under the assumption that the subdomain diameter is sufficiently small and the eigenvalue tolerance for building the coarse space is sufficiently large. While the iteration number estimates do grow as the non-self-adjointness and indefiniteness of the operator increases, practical tests indicate the deterioration is much milder. Thus we obtain an iterative solver which is efficient in parallel and very effective for a wide range of convection–diffusion–reaction *** Codes 65N22, 65N55, 65F10 Copyright © 2021, The Authors. All rights reserved.

关键词： Finite element method

Local number fluctuations in ordered and disordered phases of water across temperatures: Higher-order moments and degrees of tetrahedrality

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arXiv 2024年

作者： Klatt, Michael A. Kim, Jaeuk Gartner, Thomas E. Torquato, Salvatore Institute for AI Safety and Security Wilhelm-Runge-Str. 10 Ulm89081 Germany Institute for Material Physics in Space Köln51170 Germany Department of Physics Ludwig-Maximilians-Universität München Schellingstr. 4 Munich80799 Germany Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Physics Princeton University PrincetonNJ08544 United States Princeton Materials Institute Princeton University PrincetonNJ08544 United States Department of Chemical & Biomolecular Engineering Lehigh University BethlehemPA18015 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

The isothermal compressibility (i.e., the asymptotic number variance) of equilibrium liquid water as a function of temperature is minimal near ambient conditions. This anomalous non-monotonic temperature dependence is due to a balance between thermal fluctuations and the formation of tetrahedral hydrogen-bond networks. Since tetrahedrality is a many-body property, it will also influence the higher-order moments of density fluctuations, including the skewness and kurtosis. To gain a more complete picture, we examine these higher-order moments that encapsulate many-body correlations using a recently developed, advanced platform for local density fluctuations. We study an extensive set of simulated phases of water across a range of temperatures (80 K to 1600 K) with various degrees of tetrahedrality, including ice phases, equilibrium liquid water, supercritical water, and disordered nonequilibrium quenches. We find clear signatures of tetrahedrality in the higher-order moments, including the skewness and excess kurtosis, that scale for all cases with the degree of tetrahedrality. More importantly, this scaling behavior leads to non-monotonic temperature dependencies in the higher-order moments for both equilibrium and non-equilibrium phases. Specifically, at near-ambient conditions, the higher-order moments vanish most rapidly for large length scales, and the distribution quickly converges to a Gaussian in our metric. However, at non-ambient conditions, higher-order moments vanish more slowly and hence become more relevant especially for improving information-theoretic approximations of hydrophobic solubility. The temperature non-monotonicity that we observe in the full distribution across length-scales could shed light on water's nested anomalies, i.e., reveal new links between structural, dynamic, and thermodynamic anomalies. © 2024, CC BY-NC-ND.

关键词： Higher order statistics

A METRIC ON DIRECTED GRAPHS AND MARKOV CHAINS BASED ON HITTING PROBABILITIES

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arXiv 2020年

作者： Boyd, Zachary M. Fraiman, Nicolas Marzuola, Jeremy L. Mucha, Peter J. Osting, Braxton Weare, Jonathan Department of Mathematics Univ. North Carolina at Chapel Hill United States Department of Statistics and Operations Research Univ. North Carolina at Chapel Hill United States Carolina Center for Interdisciplinary Applied Mathematics Department of Mathematics Department of Applied Physical Sciences Univ. North Carolina at Chapel Hill United States Department of Mathematics University of Utah United States Courant Institute of Mathematical Sciences New York University United States

The shortest-path, commute time, and diffusion distances on undirected graphs have been widely employed in applications such as dimensionality reduction, link prediction, and trip planning. Increasingly, there is interest in using asymmetric structure of data derived from Markov chains and directed graphs, but few metrics are specifically adapted to this task. We introduce a metric on the state space of any ergodic, finite-state, time-homogeneous Markov chain and, in particular, on any Markov chain derived from a directed graph. Our construction is based on hitting probabilities, with nearness in the metric space related to the transfer of random walkers from one node to another at stationarity. Notably, our metric is insensitive to shortest and average walk distances, thus giving new information compared to existing metrics. We use possible degeneracies in the metric to develop an interesting structural theory of directed graphs and explore a related quotienting procedure. Our metric can be computed in O(n3) time, where n is the number of states, and in examples we scale up to n = 10, 000 nodes and ≈ 38M edges on a desktop computer. In several examples, we explore the nature of the metric, compare it to alternative methods, and demonstrate its utility for weak recovery of community structure in dense graphs, visualization, structure recovering, dynamics exploration, and multiscale cluster detection. Copyright © 2020, The Authors. All rights reserved.

关键词： Directed graphs

Stealthy and hyperuniform isotropic photonic bandgap structure in 3D

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arXiv 2024年

作者： Siedentop, Lukas Lui, Gianluc Maret, Georg Chaikin, Paul M. Steinhardt, Paul J. Torquato, Salvatore Keim, Peter Florescu, Marian Department of Physics University of Konstanz Konstanz78457 Germany Advanced Technology Institute Department of Physics University of Surrey Surrey GuildfordGU2 7XH United Kingdom Department of Physics New York University New YorkNY20012 United States Department of Physics Princeton University PrincetonNJ08544 United States Department of Chemistry Princeton University PrincetonNJ08544 United States Princeton Materials Institute Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Max-Planck-Institute for Dynamics and Self-Organization Göttingen37077 Germany Institute for the Dynamics of Complex Systems University of Göttingen Göttingen37077 Germany

In photonic crystals the propagation of light is governed by their photonic band structure, an ensemble of propagating states grouped into bands, separated by photonic band gaps. Due to discrete symmetries in spatially strictly periodic dielectric structures their photonic band structure is intrinsically anisotropic. However, for many applications, such as manufacturing artificial structural color materials or developing photonic computing devices, but also for the fundamental understanding of light-matter interactions, it is of major interest to seek materials with long range non-periodic dielectric structures which allow the formation of isotropic photonic band gaps. Here, we report the first ever 3D isotropic photonic band gap for an optimized disordered stealthy hyperuniform structure for microwaves. The transmission spectra are directly compared to a diamond pattern and an amorphous structure with similar node density. The band structure is measured experimentally for all three microwave structures, manufactured by 3D-Laser-printing for meta-materials with refractive index up to n = 2.1. Results agree well with finite-difference-time-domain numerical investigations and a priori calculations of the band-gap for the hyperuniform structure: the diamond structure shows gaps but being anisotropic as expected, the stealthy hyperuniform pattern shows an isotropic gap of very similar magnitude, while the amorphous structure does not show a gap at all. The centimeter scaled microwave structures may serve as prototypes for micrometer scaled structures with bandgaps in the technologically very interesting region of infrared (IR). Copyright © 2024, The Authors. All rights reserved.

关键词： Anisotropy