Tissue-mimicking phantoms with high scatterer concentrations were examined using quantitative ultrasound techniques based on four scattering models: The Gaussian model (GM), the Faran (FM), structure factor (SFM), and particle (PM). Experiments conducted 10- 17.5-MHz focused transducers tissue-mimicking ranging from 1% to 25%. Theoretical backscatter coefficients (BSCs) first compared experimentally measured BSCs in forward problem framework. BSC versus concentration relationship was...

Ultrasonic backscatter coefficient (BSC) measurements were performed on K562 cell pellet biophantoms with concentrations ranging from 0.006 to 0.30 in the 10–42 MHz frequency bandwidth. Three scattering models, namely, fluid-filled sphere model (FFSM), particle (PM), and structure factor (SFM), compared for modeling an ensemble of concentrated cells. A parameter estimation procedure was developed order estimate scatterer size relative impedance contrast that could explain measured BSCs all...

Three scattering models were examined for characterizing ex vivo canine livers and HT29 mouse tumors in the 10-38- 15-42-MHz frequency bandwidth, respectively. The spherical Gaussian model (SGM) fluid sphere (FSM) that are suitable dealing with sparse media, whereas structure factor (SFM) is adapted concentrated media. For livers, scatterer radius acoustic concentration estimated three similar matched well nuclear structures obtained from histological analysis (with relative errors less than...

Acoustic signals generated in water by terawatt (TW) laser pulses undergoing filamentation are studied. The acoustic signal has a very broad spectrum, spanning from 0.1 to 10 MHz and is confined the plane perpendicular direction. Such source appears be promising for development of remote based applications.

The authors study acoustic signals generated by filamentation of ultrashort terawatt laser pulses in water. They investigate experimentally and numerically the strong dependence shape intensity waves on input pulse duration. demonstrate that sound from an extended source produced picosecond have directivity, a finding relevant for underwater detection communications.

Experiments and simulations are performed to study filamentation generation of acoustic waves in water by loosely focused multi-millijoules laser pulses. When the pulse duration is increased from femtosecond nanosecond duration, a transition observed filamentary propagation with extended low energy density deposition localized breakdown, related high deposition. The suggests that Kerr self-focusing plays major role beam dynamics. As result, shape, amplitude spectrum resulting pressure wave...

The scattering of acoustic waves by an elastic sphere embedded in isotropic medium is investigated. Expressions for the scattered are given terms monostatic and bistatic cross sections. resonances solid were determined numerically individual normal mode amplitudes; dispersion curves phase velocities circumferential also obtained. Computations experimental results aluminum Plexiglas good agreement.

This study deals with the reconstruction, from ultrasonic measured data, of sound speed profile a penetrable two-dimensional target arbitrary cross-section embedded in an infinite medium. Green's theorem is used to obtain domain integral representation acoustical scattered field, and discrete formulation inverse problem obtained using moment method. An iterative non-linear algorithm minimizing discrepancy between computed fields reconstruct region interest. The minimization process performed...

The measurement of the pressure field radiated by a sound source has many applications in fields noise control and loudspeaker system design. In this paper, radiation mode method is used to measure complex acoustic whose surface impedance arbitrary does not correspond Neumann boundary condition for calculation modes. most effective modes are as test functions calculate expansion around under test, an that matches measured at limited number points close source. This then greater distance...

This paper presents an active noise control experiment designed to validate a real-time strategy for reduction of the scattered from three-dimensional body. The algorithm relies on estimating by linear filtering total measured around body; suitable filters are identified off-line measurements. A modified Filtered-Error Least-Mean-Squares then leads adaptive which drive secondary sources. provides numerical simulations using Boundary Element Method helped in designing feasible anechoic...

Sound propagation in water-saturated glass beads was studied under controlled laboratory conditions over a frequency range from 200 to 900 kHz for sound-speed measurements and 800 attenuation measurements. The influence of the grain size on both p-wave speed using three kinds beads. A strong negative dispersion sound whole observed with different populations used this experiment (mean size: 272 μm, 520 1.33 mm). In addition, it found that not only does increase nonlinearly frequency, but...

Quantitative ultrasound techniques have been previously used to evaluate biological hard tissues, characterized by a large acoustic impedance contrast. Here, we are interested in the imaging of experimental data from different test-targets with high contrast, using Full Waveform Inversion (FWI) method solve inverse problem. This is based on high-resolution numerical modeling forward problem interaction between waves and medium, considering full time series. To reduce complexity...

This study focuses on the application of ultrasonic diffraction tomography to noncircular 2D-cylindrical objects immersed in an infinite fluid. The distorted Born iterative method used solve inverse scattering problem belongs class algebraic reconstruction algorithms. was developed increase order approximation (in case weakly-contrasted media) higher orders. yields quantitative information about scatterer, such as speed sound and attenuation. Quantitative imaging techniques this kind are...

Sound reflection by water-saturated sands and glass beads with a flattened surface was studied under controlled laboratory conditions in wide frequency range, from 200 kHz to 7 MHz. In the ¿low-frequency¿ domain case of medium sand, reflected sound level found be good agreement both classical sonar measurements theories developed for fluid porous media (this is practically independent frequency); as increases, large decrease occurs, possibly due incoherent scattering. very high-frequency...

A model of the time domain scattering from small discrete volume particles is presented here with an experimental validation. The was implemented on backbone BORIS-3D which originally included only surface and perturbation density sound speed. proposed adds simulates both monostatic bistatic configurations. validation performed in a tank CMRS/LMA Laboratory (Laboratoire de Mécanique et d'Acoustique) using in-house produced silicon plate (with flat upper interface) 10% embeds spherical glass...

Ultrasound Computed Tomography (USCT) of soft biological tissues today provides images with a high-level resolution. The signal acquisition system using multichannel and/or multifrequency arrays performs in circular mode and the main (linear) inversion algorithms are based on compression wave propagation modeling. limits these methods for bone imaging due to large impedance contrast between tissues, propagative phenomena generated through periosteal interfaces (mode conversion, attenuation)....

This paper is concerned with the reconstruction, from measured (synthetic and experimental) data, of a 2D penetrable fluid-like cylindrical object arbitrary cross-section imbedded in (sediment) half-space separated by plane interface another fluid (deep water) wherein propagates acoustic interrogating wave. The Green theorem used to provide (1) domain integral representation (DIR) scattered field (2) equation (DIE) for pressure test region containing object. Both DIE DIR are discretized...

This study deals with the 2-D ultrasonic qualitative and quantitative imaging of child bone. The inverse problem is linearly non-linearly solved via a Born-based procedure involving minimization discrepancies between measurements modeling data. Inversions experimental data are presented.

In the field of quantitative ultrasound (QUS), several studies have been conducted to parameterize tissue anisotropy by measuring angular dependence backscatter coefficient (BSC). Early foundational utilized a single-element transducer, and more recent ones using linear array probes. However, probe features such as directivity crosstalk can strongly affect both, transmission an beam measurements backscattered signals, independently imaging strategy used, either focused steering or plane wave...