Empirical relationships between acoustic parameters in human soft tissues

Mast, T. Douglas

doi:10.1121/1.1336896

Cited by 333 publications

(235 citation statements)

References 25 publications

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“…The maximum temperature elevation is approximately 7.5˚C, which means that one could afford to slightly defocus the US beam to increase the insonified volume. Furthermore, [39] showed that the mean absorption coefficient of human soft tissues is approximately 0.54 dB/cm (or 6.2 Np/m) at 1 MHz, higher than that of glycerol (3.6 Np/(m•MHz)). This means that even if an in vivo evaluation will introduce thermal dissipation due to blood perfusion, we could still expect good performance on small animals, depending on the insonified tissue.…”

Section: Mild Hyperthemiamentioning

confidence: 99%

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Gross¹,

Legros

Vince³

et al. 2018

OJAppS

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Capacitive Micromachined Ultrasonic Transducer (CMUT) technology, which has been widely studied in the field of medical imaging, possesses strong design flexibility due to its manufacturing process. Many applications could benefit from this unique feature, especially those that require different operating ultrasonic frequencies. This article reports on the characterization of the therapeutic low-frequency field provided by an ultrasound-guided focused ultrasound CMUT probe that is connected to a custom ultrasonic scanner for hyperthermia applications. The study begins by mapping the focused ultrasonic beam in the vicinity of the focal spot and a parametric analysis providing the maximum peak-to-peak (PTP) pressure delivered by the probe under different acoustic conditions. The measured maximum PTP pressure at the targeted operating frequency of 1 MHz is 3 MPa, with a maximum of 3.6 MPa at 1.25 MHz. Based on an in vitro setup found in the literature, the temperature elevation at the focal point was measured, showing results in agreement with the targeted applications (max. ∆T = 7.5˚C). The article concludes with a reliability study considering the delivered pressure and the self-heating of the CMUT probe: the results show the good stability of the pressure amplitude over 1.8 × 10 9 cycles at a duty cycle of 40%, with a moderate internal heating of 3˚C.

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Section: Mild Hyperthemiamentioning

confidence: 99%

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Gross¹,

Legros

Vince³

et al. 2018

OJAppS

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show abstract

“…This works by simulating the propagation of ultrasound waves through a map of the individual patient's Figure 1: Relationship between the density of the skull bone, derived from CT, and the compressional sound speed. Values taken from Connor et al [19], Mast et al [20], Aubry et al [5], and Pichardo et al [21].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of simulated transcranial ultrasound fields to acoustic medium property maps

et al. 2017

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Abstract.High intensity transcranial focused ultrasound is an FDA approved treatment for essential tremor, while low-intensity applications such as neurostimulation and opening the blood brain barrier are under active research. Simulations of transcranial ultrasound propagation are used both for focusing through the skull, and predicting intracranial fields. Maps of the skull acoustic properties are necessary for accurate simulations, and can be derived from medical images using a variety of methods. The skull maps range from segmented, homogeneous models, to fully heterogeneous models derived from medical image intensity. In the present work, the impact of uncertainties in the skull properties is examined using a model of transcranial propagation from a single element focused transducer. The impact of changes in bone layer geometry and the sound speed, density, and acoustic absorption values is quantified through a numerical sensitivity analysis. Sound speed is shown to be the most influential acoustic property, and must be defined with less than 4% error to obtain acceptable accuracy in simulated focus pressure, position, and volume. Changes in the skull thickness of as little as 0.1 mm can cause an error in peak intracranial pressure of greater than 5%, while smoothing with a 1 mm 3 kernel to imitate the effect of obtaining skull maps from low resolution images causes an increase of over 50% in peak pressure. The numerical results are confirmed experimentally through comparison with sonications made through 3D printed and resin cast skull bone phantoms.

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“…5 shows the change in the density and acoustic impedance according to the olive-oil composition ratio. Table 2 compares the acoustic properties of the fabricated fat phantom in this study, subcutaneous fat tissue [12][13][14], and fat tissue of the breast area [10] as typical fat tissue. From a comparison of the subcutaneous fat tissue and the fat tissue of the breast area, the sound velocity of the subcutaneous fat tissue was 40 m/s higher than the fat tissue of the breast area.…”

Section: Resultsmentioning

confidence: 99%

A Fat-Tissue Mimic Phantom for Therapeutic Ultrasound

Kim¹,

Kim²,

Jung³

et al. 2014

IEIE Transactions on Smart Processing and Computing

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Abstract:As the number of treatments in the therapeutic ultrasound field targeted at fat tissue increase, the performance of the equipment should be evaluated for safety using a fat phantom. In this study, a fat phantom was fabricated using olive oil and a tissue-mimicking material (TMM) phantom. To evaluate the acoustic properties of the TMM phantom according to the changes in the olive oil, the composition ratio of a liquid mixture of olive oil with a surfactant was adjusted from 5-20% in 5% steps. The acoustic properties of the phantom were evaluated using the sound velocity, attenuation coefficient, density, and acoustic impedance. The experimental results showed that the sound velocity decreased with increasing amount of olive oil but the other acoustic properties did not change. In addition, the phantom using an olive-oil mixture with a 15% composition ratio was most similar to the acoustic characteristics of fat tissue with a sound velocity of 1477.35 m/s, an attenuation coefficient of 0.514 dB/MHz-cm, a density of 1.07 g/cm 3 , and an acoustic impedance of 1.575 MRayl. These experimental results are expected contribute to the accuracy of the results using a TMM phantom and will be useful for the therapeutic ultrasound field targeted at subcutaneous fat tissue.

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Empirical relationships between acoustic parameters in human soft tissues

Cited by 333 publications

References 25 publications

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Evaluation of an Ultrasound-Guided Focused Ultrasound CMUT Probe for Targeted Therapy Applications

Sensitivity of simulated transcranial ultrasound fields to acoustic medium property maps

A Fat-Tissue Mimic Phantom for Therapeutic Ultrasound

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