Ultrasonically induced gas bubble production in agar based gels: Part I, experimental investigation

Daniels, Stephen R.; Blondel, D.; Crum, Lawrence A.; Haar, Gail ter; Dyson, Mary

doi:10.1016/0301-5629(87)90179-7

Cited by 38 publications

(9 citation statements)

References 8 publications

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“…Agar hydrogels are commonly used as phantoms to mimic tissue (Daniels et al, 1987; Dunmire et al, 2013; Vlaisavljevich et al, 2014). Ours were prepared with agar concentrations from 1.5% to 3.0% w/v and with a water:dimethyl sulfoxide (DMSO; 99% purity, FWI, Tulsa, OK) ratio of 30:20, to improve optical clarity following established protocols (Hall et al, 1997; Hyon et al, 1989; Dunmire et al, 2013).…”

Section: Methodsmentioning

confidence: 99%

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Ultrasound-Induced Bubble Clusters in Tissue-Mimicking Agar Phantoms

Movahed

Kreider

Maxwell

et al. 2017

Ultrasound in Medicine & Biology

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Therapeutic ultrasound can in cases drive bubble activity that damages soft tissues. To study potential mechanisms of such injury, transparent agar tissue-mimicking phantoms were subjected to multiple pressure wave bursts of the kind being considered specifically for burst wave lithotripsy (BWL). A highspeed camera recorded bubble activity during each pulse. Different agar concentrations were used to alter the phantom’s mechanical properties, especially its stiffness, which was varied by a factor of 3.5. However, the maximum observed bubble radius was insensitive to stiffness. Bubbles appeared continuously during the 1000 wave bursts of a candidate BWL treatment over a region that expands slowly, primarily toward the transducer. Denser bubble clouds are formed at higher pulse repetition frequency. The specific observations are used to inform the incorporation of damage mechanisms into cavitation models for soft materials.

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Section: Methodsmentioning

confidence: 99%

“…To facilitate observations, transparent agar hydrogels are used (Daniels et al, 1987). Gel stiffness depends on the agar concentration, which is adjusted.…”

Section: Introductionmentioning

confidence: 99%

Ultrasound-Induced Bubble Clusters in Tissue-Mimicking Agar Phantoms

Movahed

Kreider

Maxwell

et al. 2017

Ultrasound in Medicine & Biology

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“…The existence of a threshold at this intensity tends to point toward a strong role of cavitation, particularly inertial or collapse cavitation, in this release phenomenon. Several groups have reported the existence of a threshold for the onset of inertial cavitation 90–94. Daniels et al90 reported an inertial cavitation threshold between 0.036 and 0.141 W/cm 2 at 750 kHz insonation, while Hill showed the thresholds to occur below 1 W/cm 2 for frequencies ranging between 0.25 and 4 MHz 91.…”

Section: Mechanismsmentioning

confidence: 99%

“…Several groups have reported the existence of a threshold for the onset of inertial cavitation 90–94. Daniels et al90 reported an inertial cavitation threshold between 0.036 and 0.141 W/cm 2 at 750 kHz insonation, while Hill showed the thresholds to occur below 1 W/cm 2 for frequencies ranging between 0.25 and 4 MHz 91. Obviously there is a wide range of intensities reported for the onset of inertial cavitation.…”

Section: Mechanismsmentioning

confidence: 99%

Ultrasonic-Activated Micellar Drug Delivery for Cancer Treatment

Husseini

Pitt

2009

Journal of Pharmaceutical Sciences

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The use of nanoparticles and ultrasound in medicine continues to evolve. Great strides have been made in the areas of producing micelles, nanoemulsions and solid nanoparticles that can be used in drug delivery. An effective nanocarrier allows for the delivery of a high concentration of potent medications to targeted tissue while minimizing the side effect of the agent to the rest of the body. Polymeric micelles have been shown to encapsulate therapeutic agents and maintain their structural integrity at lower concentrations. Ultrasound is currently being used in drug delivery as well as diagnostics, and has many advantages that elevate its importance in drug delivery. The technique is non-invasive, thus no surgery is needed; the ultrasonic waves can be easily controlled by advanced electronic technology so that they can be focused on the desired target volume. Additionally, the physics of ultrasound are widely used and well understood; thus ultrasonic application can be tailored towards a particular drug delivery system. In this article, we review the recent progress made in research that utilizes both polymeric micelles and ultrasonic power in drug delivery.

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“…They are all driven by a fully programmable emission channel, 54 of them also being able to receive. Cavitation events occur in a 1.75%w/v agar gel, phantom for in vivo bubble formation [6]. A needle hydrophone with a 3D positioning system is used to map the focal spots at 1MHz and low amplitude levels.…”

Section: Iiexperimental Set Upmentioning

confidence: 99%

Reaching the optimal focusing and steering capabilities of transcranial HIFU arrays based on time reversal of acoustically induced cavitation bubble signature

Gâteau

Pernot

Aubry

et al. 2008

2008 IEEE Ultrasonics Symposium

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Brain treatment with High Intensity Focused Ultrasound (HIFU) can be achieved by multichannel arrays through the skull using timereversal focusing. Such a method requires a reference signal either sent by a real source embedded in brain tissues or computed from a virtual source, using the acoustic properties of the skull deduced from CT images. This noninvasive computational method allows precise focusing, but is time consuming and suffers from unavoidable modeling and repositioning errors which reduce the accessible acoustic pressure at the focus in comparison with real experimental time reversal using an implanted hydrophone. Ex vivo simulations with a half skull immersed in a water tank allow us to reach at low amplitude levels a pressure ratio of 83% of the reference pressure (real timereversal) at 1MHz. Using this method to transcranially focus a pulse signal in an agar gel (model for in vivo bubble formation), we induced a cavitation bubble that generated an ultrasonic wave received by the array. Selecting the 1MHz component, the signal was time reversed and reemitted, allowing 97%±1.1% of pressure ratio to be restored. To target points in the vicinity of the geometrical focus, conventional electronic steering from the reference signal has been achieved. Skull aberrations severely degrade the accessible pressure while moving away from the focus ( ~90% at 11mm in the focal plane). Nevertheless, inducing cavitation bubbles close to the limit of the primary accessible zone allowed us to acquire multiple references signal to increase the electronic steering area by 50%.Adaptive focusing, noninvasive method, microcavitation, bubble, transcranial brain therapy, ultrasonic array

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Ultrasonically induced gas bubble production in agar based gels: Part I, experimental investigation

Cited by 38 publications

References 8 publications

Ultrasound-Induced Bubble Clusters in Tissue-Mimicking Agar Phantoms

Ultrasound-Induced Bubble Clusters in Tissue-Mimicking Agar Phantoms

Ultrasonic-Activated Micellar Drug Delivery for Cancer Treatment

Reaching the optimal focusing and steering capabilities of transcranial HIFU arrays based on time reversal of acoustically induced cavitation bubble signature

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