A5059879181- Ultrasound Imaging and Elastography
- Photoacoustic and Ultrasonic Imaging
- Ultrasound and Hyperthermia Applications
- Interconnection Networks and Systems
- Parallel Computing and Optimization Techniques
- Embedded Systems Design Techniques
- Distributed and Parallel Computing Systems
- Microwave Imaging and Scattering Analysis
- Evolutionary Algorithms and Applications
- Numerical methods for differential equations
- Education, Psychology, and Social Research
- Ultrasonics and Acoustic Wave Propagation
- Metaheuristic Optimization Algorithms Research
- Optical Imaging and Spectroscopy Techniques
- Differential Equations and Numerical Methods
- Advanced MRI Techniques and Applications
- Nonlinear Differential Equations Analysis
- Scientific Computing and Data Management
- Flow Measurement and Analysis
- Advanced X-ray and CT Imaging
- Thermography and Photoacoustic Techniques
- Advanced Radiotherapy Techniques
- Lattice Boltzmann Simulation Studies
- Electromagnetic Simulation and Numerical Methods
- Generative Adversarial Networks and Image Synthesis
Brno University of Technology
2015-2024
University College London
2016-2019
Comenius University Bratislava
2002-2016
Australian National University
2012
Tomas Bata University in Zlín
2012
University of Veterinary Science
1985
University of Arizona
1985
The simulation of nonlinear ultrasound propagation through tissue realistic media has a wide range practical applications. However, this is computationally difficult problem due to the large size computational domain compared acoustic wavelength. Here, k-space pseudospectral method used reduce number grid points required per wavelength for accurate simulations. model based on coupled first-order equations valid wave in heterogeneous with power law absorption. These are derived from fluid...
Non-invasive, focal neurostimulation with ultrasound is a potentially powerful neuroscientific tool that requires effective transcranial focusing of to develop. Time-reversal (TR) using numerical simulations propagation can correct for the effect skull, but relies on accurate simulations. Here, requirements ultrasonic are established through review previously employed parameters, and consideration deep brain targets. The specific limitations finite-difference time domain (FDTD) k-space...
A new model for simulating elastic wave propagation using the open-source k-Wave MATLAB Toolbox is described. The based on two coupled first-order equations describing stress and particle velocity within an isotropic medium. For absorbing media, Kelvin-Voigt of viscoelasticity used. are discretised in 2D 3D efficient time-stepping pseudospectral scheme. This uses Fourier collocation spectral method to compute spatial derivatives a leapfrog finite-difference scheme integrate forwards time....
Computational models of acoustic wave propagation are frequently used in transcranial ultrasound therapy, for example, to calculate the intracranial pressure field or phase delays correct skull distortions. To allow intercomparison between different modeling tools and techniques by community, an international working group was convened formulate a set numerical benchmarks. Here, these benchmarks presented, along with results. Nine increasing geometric complexity defined. These include...
Model-based treatment planning and exposimetry for high-intensity focused ultrasound requires the numerical simulation of nonlinear propagation through heterogeneous absorbing media. This is a computationally demanding problem due to large distances travelled by waves relative wavelength highest frequency harmonic. Here, k-space pseudospectral method used solve set coupled partial differential equations equivalent generalised Westervelt equation. The model implemented in C++ parallelised...
Models of ultrasound propagation in biologically relevant media have applications planning and verification therapies computational dosimetry. To be effective, the models must able to accurately predict both spatial distribution amplitude acoustic pressure. This requires that are validated absolute terms, which for arbitrarily heterogeneous should performed by comparison with measurements field. In this article, simulations using open-source k-Wave acoustics toolbox, a measurement-based...
A Green's function solution is derived for calculating the acoustic field generated by phased array transducers of arbitrary shape when driven a single frequency continuous wave excitation with spatially varying amplitude and phase. The based on homogeneous equation expressed in spatial domain or k-space. temporal convolution integral solved analytically, remaining integrals are form Fourier transform. This allows pressure all positions to be calculated step using two fast transforms. model...
Accurately representing acoustic source distributions is an important part of ultrasound simulation. This challenging for grid-based collocation methods when such do not coincide with the grid points, instance a curved, two-dimensional surface embedded in three-dimensional domain. Typically, points close to are defined as but this can result "staircasing" and substantial errors resulting fields. paper describes technique accurately arbitrary within Fourier methods. The method works by...
This paper is concerned with the oscillatory behavior of first-order delay differential equations form (1) x′(t) + p(t)x(τ(t)) = 0, t ≥ T, where p, τ ∈ C([T,∞),R+), R+ [0,∞), τ(t) nondecreasing, < for T and limt→∞ ∞. Let numbers k L be defined by
High-intensity focused ultrasound (HIFU) therapy can be used for noninvasive treatment of kidney (renal) cancer, but the clinical outcomes have been variable. In this study, efficacy renal HIFU was studied using nonlinear acoustic and thermal simulations in three patients.The were conducted with without refraction order to investigate its effect on shape, size, pressure distribution at focus. The values attenuation, sound speed, perfusion, conductivity varied over reported ranges determine...
A full-wave model for nonlinear ultrasound propagation through a heterogeneous and absorbing medium in an axisymmetric coordinate system is developed. The equations are solved using nonstandard or k-space pseudospectral time domain method. Spatial gradients the axial direction calculated Fourier collocation spectral method, spatial radial discrete trigonometric transforms. Time integration performed corrected finite difference scheme. This scheme exact plane waves propagating linearly...
This paper introduces a novel implementation of the genetic algorithm exploiting multi-GPU cluster. The proposed employs an island-based where every GPU evolves single island. individuals are processed by CUDA warps, which enables solution large knapsack instances and eliminates undesirable thread divergence. MPI interface is used to exchange material among isolated islands collect statistical data. characteristics GAs investigated on two-node cluster composed 14 Fermi GPUs 4 six-core Intel...
The simulation of nonlinear ultrasound waves in biological tissue has a number important applications. However, this is computationally intensive task due to the large domain sizes required for many problems practical interest. Recently, an efficient full-wave model was developed and released as part open source k-Wave Toolbox. Here, validated using series experimental measurements made with linear diagnostic probe membrane hydrophone. Measurements were performed both deionised water olive...
A broadband all-optical plane-wave ultrasound imaging system for high-resolution 3-D of biological tissues is presented. The based on a planar Fabry-Perot (FP) scanner detection and the photoacoustic generation in carbon-nanotube-polydimethylsiloxane (CNT-PDMS) composite film. FP sensor head was coated with CNT-PDMS film which acts as an transmitting layer pulse-echo imaging. Exciting coating nanosecond laser pulses generated monopolar MPa-range peak pressures -6-dB bandwidth 22 MHz, were...
In this work, the use of binary amplitude holography is investigated as a mechanism to focus broadband acoustic pulses generated by high peak-power pulsed lasers. Two algorithms are described for calculation holograms; one using ray-tracing, and an optimization based on direct search. It shown numerical simulations that when hologram excited train laser at its design frequency, field can be focused pre-determined distribution points, including single multiple focal line square foci. The...
Reconstructing images from measured time domain signals is an essential step in tomography-mode photoacoustic imaging. However, practice, there are many complicating factors that make it difficult to obtain high-resolution images. These include incomplete or undersampled data, filtering effects, acoustic and optical attenuation, uncertainties the material parameters. Here, processing image reconstruction steps routinely used by Photoacoustic Imaging Group at University College London...
Objective: High-intensity focused ultrasound (HIFU) therapy can be used for noninvasive treatment of kidney (renal) cancer, but the clinical outcomes have been variable. In this study, efficacy renal HIFU was studied using a nonlinear acoustic and thermal simulations in three patients. Methods: The were conducted with without refraction order to investigate its effect on shape, size, pressure distribution at focus. values attenuation, sound speed, perfusion, conductivity varied over reported...
Kidney cancer is a severe disease which can be treated non-invasively using high-intensity focused ultrasound (HIFU) therapy. However, tissue in front of the transducer and deep location kidney cause significant losses to efficiency treatment. The effect attenuation, refraction reflection due different types on HIFU therapy was studied nonlinear simulation model. geometry derived from computed tomography (CT) dataset patient had been segmented for water, bone, soft tissue, fat kidney....
The simulation of ultrasound wave propagation through biological tissue has a wide range practical applications. However, large grid sizes are generally needed to capture the phenomena interest. Here, novel approach reduce computational complexity is presented. model uses an accelerated k-space pseudospectral method which enables more than one hundred GPUs be exploited solve problems with 3*10^9 points. classic communication bottleneck Fourier spectral methods, all-to-all global data...