Ultrasonic temperature monitoring in tissue phantoms by locally resolved measurement of longitudinal and transverse wave speed

Wolf, Mario; Timmermann, L.; Juhrig, Andrè; Rath, Katharina; Leipner, Emanuel; Krujatz, Felix; Kühnicke, Elfgard

doi:10.1121/2.0001076

Cited by 3 publications

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“…Building on [34], [35], we report a novel wave-based approach that provides SoS measurements with high spatial and temporal resolution. In this paper we demonstrate the accuracy of this novel approach.…”

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confidence: 99%

Ultrasonic thermometry by a localized measurement of the longitudinal wave velocity using sound field information

Leipner¹,

Wolf²,

Kühnicke³

et al. 2021

Preprint

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Temperature monitoring during medical interventions such as hyperthermia or radio frequency ablation is a demanding task. An alternative to expensive MRI measurements are ultrasound measurements exploiting the dependence of sound velocity on temperature. In this paper, a new measurement technique is presented that determines the sound velocity spatially resolved in tissue phantoms with the aim of temperature monitoring. The measurements are performed with annular arrays operating element-wise in pulse-echo mode to allow synthetic focusing. Unlike speckle techniques, which also evaluate echoes from scatterers, this method allows to determine the true position of scatterers and absolute values of local sound velocity, rather than evaluating only relative changes. This is achieved by varying the set of delay times used for focusing and determining the set that gives the maximum amplitude of the focused echo. The measurement technique is described in detail and measurement results are shown. The achievable resolution (1mm axial and 0.4mm lateral) and accuracy of 98% are determined. Sound field simulations are used to model the measurement process and vary measurement parameters. Thus, the effect of parameter variations on the achievable accuracy can be evaluated very precisely.

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confidence: 99%

Ultrasonic thermometry by a localized measurement of the longitudinal wave velocity using sound field information

Leipner¹,

Wolf²,

Kühnicke³

et al. 2021

Preprint

Self Cite

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Transient approximated Green’s Function of a circular line source on a half space for fast simulation of axisymmetric problems

Wolf

Kühnicke

2019

2019 IEEE International Ultrasonics Symposium (IUS)

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Linear, spatio-temporally resolved ultrasound measurement of the liquid fraction distribution in froth

Emmerich

Schaller

Nauber

et al. 2021

Tm - Technisches Messen

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Froth flotation is an important process for separating metal particles from gangue. A single flotation circuit for copper uses approx. 44 billion litres water a year. In situ process monitoring of the foam’s parameters and closed-loop control can reduce the resource use. However, no measurement technique is broadly employed that yields the liquid fraction distribution in the froth. Optical measurements are prevented by the bulk foam’s opacity. Though, ultrasound in the low frequency range is able to penetrate froth. In this paper we investigate the application of ultrasound to measure the local liquid content of aqueous foam in the axis of the ultrasound beam. Assuming a dependency of the backscattering coefficient b on the foam’s liquid fraction ϕ, we developed a model to calculate b from the echo signal. Local backscattering coefficients b n {b_{n}} can be determined for time gated windows and show a trend in the dependency on the foam’s liquid fraction ϕ (for ϕ < 0.8 \phi <0.8 %). The absolute uncertainty of the liquid fraction determined by means of an electrical reference measurement is σ ϕ = 0.079 {\sigma _{\phi }}=0.079 %. We demonstrated the capability of spatio-temporally resolved measurements with a frame rate of 0.33 Hz and an axial resolution of 7.9 mm in an experiment with a time-varying, inhomogeneous liquid fraction. This research work is contributing to a determination of in situ information of the foam’s parameter in a flotation process.

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Ultrasonic temperature monitoring in tissue phantoms by locally resolved measurement of longitudinal and transverse wave speed

Cited by 3 publications

References 0 publications

Ultrasonic thermometry by a localized measurement of the longitudinal wave velocity using sound field information

Ultrasonic thermometry by a localized measurement of the longitudinal wave velocity using sound field information

Transient approximated Green’s Function of a circular line source on a half space for fast simulation of axisymmetric problems

Linear, spatio-temporally resolved ultrasound measurement of the liquid fraction distribution in froth

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