Ultrasound tomography of materials with high sound speed contrast

2017 ◽  
Vol 142 (4) ◽  
pp. 2537-2537
Author(s):  
Timothe Falardeau ◽  
Pierre Belanger
Keyword(s):  
Sound Speed ◽  
Ultrasound Tomography ◽  
High Sound

scholarly journals Using Whole Breast Ultrasound Tomography to Improve Breast Cancer Risk Assessment: A Novel Risk Factor Based on the Quantitative Tissue Property of Sound Speed

2020 ◽  
Vol 9 (2) ◽  
pp. 367 ◽  
Author(s):  
Neb Duric ◽  
Mark Sak ◽  
Shaoqi Fan ◽  
Ruth M. Pfeiffer ◽  
Peter J. Littrup ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Risk Factor ◽  
Breast Cancer Risk ◽  
Cancer Risk ◽  
Sound Speed ◽  
Menopausal Status ◽  
Surrogate Marker ◽  
Breast Ultrasound ◽  
Ultrasound Tomography ◽  
Breast Cancer Risk Assessment

Mammographic percent density (MPD) is an independent risk factor for developing breast cancer, but its inclusion in clinical risk models provides only modest improvements in individualized risk prediction, and MPD is not typically assessed in younger women because of ionizing radiation concerns. Previous studies have shown that tissue sound speed, derived from whole breast ultrasound tomography (UST), a non-ionizing modality, is a potential surrogate marker of breast density, but prior to this study, sound speed has not been directly linked to breast cancer risk. To that end, we explored the relation of sound speed and MPD with breast cancer risk in a case-control study, including 61 cases with recent breast cancer diagnoses and a comparison group of 165 women, frequency matched to cases on age, race, and menopausal status, and with a recent negative mammogram and no personal history of breast cancer. Multivariable odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for the relation of quartiles of MPD and sound speed with breast cancer risk adjusted for matching factors. Elevated MPD was associated with increased breast cancer risk, although the trend did not reach statistical significance (OR per quartile = 1.27, 95% CI: 0.95, 1.70; ptrend = 0.10). In contrast, elevated sound speed was significantly associated with breast cancer risk in a dose–response fashion (OR per quartile = 1.83, 95% CI: 1.32, 2.54; ptrend = 0.0003). The OR trend for sound speed was statistically significantly different from that observed for MPD (p = 0.005). These findings suggest that whole breast sound speed may be more strongly associated with breast cancer risk than MPD and offer future opportunities for refining the magnitude and precision of risk associations in larger, population-based studies, including women younger than usual screening ages.

scholarly journals Forbidden line diagnostics of photoevaporative disc winds

2020 ◽  
Vol 496 (3) ◽  
pp. 2932-2945 ◽  
Author(s):  
G Ballabio ◽  
R D Alexander ◽  
C J Clarke
Keyword(s):  
Sound Speed ◽  
Central Star ◽  
High Energy ◽  
Emission Lines ◽  
Limiting Factor ◽  
Line Profiles ◽  
Gas Temperature ◽  
Characteristic Emission ◽  
Extreme Uv ◽  
High Sound

ABSTRACT Photoevaporation driven by high-energy radiation from the central star plays an important role in the evolution of protoplanetary discs. Photoevaporative winds have been unambiguously detected through blue-shifted emission lines, but their detailed properties remain uncertain. Here we present a new empirical approach to make observational predictions of these thermal winds, seeking to fill the gap between theory and observations. We use a self-similar model of an isothermal wind to compute line profiles of several characteristic emission lines (in particular the [Ne ii] line at 12.81 μm, and optical forbidden lines such as [O i] 6300 Å and [S ii] 4068/4076 Å), studying how the lines are affected by parameters such as the gas temperature, disc inclinations, and density profile. Our model successfully reproduces blue-shifted lines with $v_{\rm peak} \lesssim 10$ km s−1, which decrease with increasing disc inclination. The line widths increase with increasing disc inclinations and range from $\Delta v\sim 15\text{ to }30$ km s−1. The predicted blue-shifts are mostly sensitive to the gas sound speed (and therefore the temperature). The observed [Ne ii] line profiles are consistent with a thermal wind and point towards a relatively high sound speed, as expected for extreme-UV photoevaporation. However, the observed [O i] line profiles require lower temperatures, as expected in X-ray photoevaporation, and show a wider scatter that is difficult to reconcile with a single wind model; it seems likely that these lines trace different components of a multiphase wind. We also note that the spectral resolution of current observations remains an important limiting factor in these studies, and that higher resolution spectra are required if emission lines are to further our understanding of protoplanetary disc winds.

Imaging of Sound Speed Using Reflection Ultrasound Tomography

2012 ◽  
Vol 31 (9) ◽  
pp. 1389-1404 ◽  
Author(s):  
Jakob Nebeker ◽  
Thomas R. Nelson
Keyword(s):  
Sound Speed ◽  
Ultrasound Tomography

Characterization of the Content of the Cavity Behind a High-Speed Supercavitating Body

2006 ◽  
Vol 129 (2) ◽  
pp. 136-145 ◽  
Author(s):  
Xiongjun Wu ◽  
Georges L. Chahine
Keyword(s):  
Sound Speed ◽  
High Speed ◽  
Test Facility ◽  
Direct Visualization ◽  
Acoustic Measurements ◽  
Supercavitating Flow ◽  
Flow Test ◽  
High Sound ◽  
Very High

A high speed/high flow test facility was designed and implemented to study experimentally the supercavitating flow behind a projectile nose in a controlled laboratory setting. The simulated projectile nose was held in position in the flow and the cavity interior was made visible by having the walls of the visualization facility “cut through” the supercavity. Direct visualization of the cavity interior and measurements of the properties of the cavity contents were made. Transducers were positioned in the test section within the supercavitation volume to enable measurement of the sound speed and attenuation as a function of the flow and geometry parameters. These characterized indirectly the content of the cavity. Photography, high speed videos, and acoustic measurements were used to investigate the contents of the cavity. A side sampling cell was also used to sample in real time the contents of the cavity and measure the properties. Calibration tests conducted in parallel in a vapor cell enabled confirmation that, in absence of air injection, the properties of the supercavity medium match those of a mixture of water vapor and water droplets. Such a mixture has a very high sound speed with strong sound attenuation. Injection of air was also found to significantly decrease sound speed and to increase transmission.

scholarly journals Comparison of sound speed measurements on two different ultrasound tomography devices

2014 ◽  
Author(s):  
Mark Sak ◽  
Neb Duric ◽  
Peter Littrup ◽  
Lisa Bey-Knight ◽  
Mark Sherman ◽  
...  
Keyword(s):  
Sound Speed ◽  
Ultrasound Tomography

scholarly journals Sound speed estimation using wave-based ultrasound tomography: theory and GPU implementation

2010 ◽  
Author(s):  
O. Roy ◽  
I. Jovanović ◽  
A. Hormati ◽  
R. Parhizkar ◽  
M. Vetterli
Keyword(s):  
Sound Speed ◽  
Speed Estimation ◽  
Ultrasound Tomography ◽  
Gpu Implementation

scholarly journals Determinants of the reliability of ultrasound tomography sound speed estimates as a surrogate for volumetric breast density

2015 ◽  
Vol 42 (10) ◽  
pp. 5671-5678 ◽  
Author(s):  
Zeina G. Khodr ◽  
Mark A. Sak ◽  
Ruth M. Pfeiffer ◽  
Nebojsa Duric ◽  
Peter Littrup ◽  
...  
Keyword(s):  
Breast Density ◽  
Sound Speed ◽  
Ultrasound Tomography

scholarly journals Acoustic Characterization of Fluorinert FC-43 Liquid with Helium Gas Bubbles: Numerical Experiments

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Christian Vanhille ◽  
Cristian Pantea ◽  
Dipen N. Sinha
Keyword(s):  
Sound Speed ◽  
Numerical Experiments ◽  
Underwater Acoustics ◽  
Gas Bubbles ◽  
Acoustic Characteristics ◽  
Parametric Generation ◽  
Acoustic Characterization ◽  
Helium Gas ◽  
High Sound

In this work, we define the acoustic characteristics of a biphasic fluid consisting of static helium gas bubbles in liquid Fluorinert FC-43 and study the propagation of ultrasound of finite amplitudes in this medium. Very low sound speed and high sound attenuation are found, in addition to a particularly high acoustic nonlinear parameter. This result suggests the possibility of using this medium as a nonlinear enhancer in various applications. In particular, parametric generation of low ultrasonic frequencies is studied in a resonator cavity as a function of driving pressure showing high conversion efficiency. This work suggests that this medium could be used for applications such as parametric arrays, nondestructive testing, diagnostic medicine, sonochemistry, underwater acoustics, and ultrasonic imaging and to boost the shock formation in fluids.

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