scholarly journals Effects of acoustic nonlinearity on pulse-echo attenuation coefficient estimation from tissue-mimicking phantoms

2020 ◽  
Vol 148 (2) ◽  
pp. 805-814 ◽  
Author(s):  
Andres Coila ◽  
Michael L. Oelze
Keyword(s):  
Attenuation Coefficient ◽  
Acoustic Nonlinearity ◽  
Coefficient Estimation ◽  
Pulse Echo

Differentiation between normal and tumor mammary glands with depth-resolved attenuation coefficient from optical coherence tomography

2021 ◽  
Author(s):  
Marino de Jesus Maciel ◽  
Hugo M Pereira ◽  
Sara Pimenta ◽  
Alice Miranda ◽  
Eduardo Jorge Nunes-Pereira ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Attenuation Coefficient ◽  
Light Attenuation ◽  
Biological Tissues ◽  
Mammary Glands ◽  
Optical Coherence ◽  
Cross Sectional ◽  
Subjective Analysis ◽  
Coefficient Estimation ◽  
Cross Sectional Imaging

Abstract Optical coherence tomography (OCT) is a well-established imaging technology for high-resolution, cross-sectional imaging of biological tissues. Imaging processing and light attenuation coefficient estimation allows to further improve the OCT diagnostic capability. In this paper we use a commercial OCT system, Telesto II-1325LR from Thorlabs, and demonstrate its ability to differentiate normal and tumor mammary mouse glands with the OCT attenuation coefficient. Using several OCT images of normal and tumor mammary mouse glands (n=26), a statistical analysis was performed. The attenuation coefficient was calculated in depth, considering a slope of 0.5 mm. The normal glands present a median attenuation coefficient of 0.403 mm-1, comparatively to 0.561 mm-1 obtained for tumor mammary glands. This translates in an attenuation coefficient approximately 39 % higher for tumor mammary glands when compared to normal mammary glands. The OCT attenuation coefficient estimation eliminates the subjective analysis provided by direct visualization of the OCT images.

Ultrasonic Characterization of EB-PVD Thermal Barrier Coatings Irradiated by HIPIB

2008 ◽  
Vol 373-374 ◽  
pp. 358-362 ◽  
Author(s):  
Li Lin ◽  
Y. Zhao ◽  
J. Chen ◽  
X.M. Li ◽  
M.K. Lei
Keyword(s):  
Reflection Coefficient ◽  
Attenuation Coefficient ◽  
Physical Vapor Deposition ◽  
Ion Beam ◽  
Phase Spectrum ◽  
Transmission Model ◽  
Compact Structure ◽  
Shot Number ◽  
Ultrasonic Reflection Coefficient ◽  
Pulse Echo

High-intensity pulsed ion beam (HIPIB) irradiation at 300 A/cm2 with a shot number of 1, and 5 was performed on the coatings and caused the modification of properties. Porosity and rough surface of EB-PVD (Electron Beam-Physical Vapor Deposition) deposited ZrO2-7%Y2O3 coatings with the thickness of 150 μm on heat-resistant steel have been characterized using the ultrasonic reflection coefficient phase spectrum. With increasing the shot number, the surface remelting and ablating filled gaps and caves between columns, and induced more uniform and compact structure. The ultrasonic measurement was investigated using immersion focusing pulse echo method with a 10 MHz transducer. The ultrasonic reflection coefficient related to frequency, velocity and attenuation coefficient were analyzed based on the acoustic transmission model in a multi-layered structure. For the as-deposited coating and coatings irradiated by HIPIB with the shot number of 1 and 5, the ultrasonic velocity changed from 2950 to 3170, and 3255 m/s respectively. The relationship between the attenuation coefficient and the frequency has been deduced based on the numerical fitting of the phase spectrum. The corresponded expressions are 1.35 α = 0.105 f , 1.2 α = 0.045 f and 1.14 α = 0.035 f , which displays that the attenuation coefficient decreases with the increasing of shot number. The ultrasonic results are in agreement with SEM observations, which have indicated that the coatings became denser and uniform with increasing the shot number. From the velocity and attenuation coefficient, the density, porosity, and microcracks of the coatings can be nondestructively evaluated utilizing the method of this paper.

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