Numerical Study of Bubble Area Evolution During Acoustic Droplet Vaporization-Enhanced HIFU Treatment

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Ying Xin ◽  
Aili Zhang ◽  
Lisa X. Xu ◽  
J. Brian Fowlkes
Keyword(s):  
Treatment Time ◽  
Numerical Study ◽  
Dynamic Change ◽  
High Intensity Focused Ultrasound ◽  
Propagation Path ◽  
Experimental Result ◽  
Bubble Wall ◽  
Acoustic Droplet Vaporization ◽  
Treatment Protocols ◽  
Droplet Vaporization

Acoustic droplet vaporization has the potential to shorten treatment time of high-intensity focused ultrasound (HIFU) while minimizing the possible effects of microbubbles along the propagation path. Distribution of the bubbles formed from the droplets during the treatment is the major factor shaping the therapeutic region. A numerical model was proposed to simulate the bubble area evolution during this treatment. Using a linear acoustic equation to describe the ultrasound field, a threshold range was defined that determines the amount of bubbles vaporized in the treated area. Acoustic parameters, such as sound speed, acoustic attenuation coefficient, and density, were treated as a function of the bubble size distribution and the gas void fraction, which were related to the vaporized bubbles in the medium. An effective pressure factor was proposed to account for the influence of the existing bubbles on the vaporization of the nearby droplets. The factor was obtained by fitting one experimental result and was then used to calculate bubble clouds in other experimental cases. Comparing the simulation results to these other experiments validated the model. The dynamic change of the pressure and the bubble distribution after exposure to over 20 pulses of HIFU are obtained. It is found that the bubble area grows from a grainlike shape to a “tadpole,” with comparable dimensions and shape to those observed in experiments. The process was highly dynamic with the shape of the bubble area changing with successive HIFU pulses and the focal pressure. The model was further used to predict the shape of the bubble region triggered by HIFU when a bubble wall pre-exists. The results showed that the bubble wall helps prevent droplet vaporization on the distal side of the wall and forms a particularly shaped region with bubbles. This simulation model has predictive potential that could be beneficial in applications, such as cancer treatment, by parametrically studying conditions associated with these treatments and designing treatment protocols.

Numerical Study of Bubble Cloud and Thermal Lesion Evolution During Acoustic Droplet Vaporization Enhanced Hifu Treatment

2021 ◽  
Author(s):  
Ying Xin ◽  
Aili Zhang ◽  
Lisa X. Xu ◽  
J. Brian Fowlkes
Keyword(s):  
Focused Ultrasound ◽  
Continuous Wave ◽  
Numerical Study ◽  
Wave Exposure ◽  
High Intensity Focused Ultrasound ◽  
Hifu Treatment ◽  
Thermal Lesion ◽  
Acoustic Droplet Vaporization ◽  
Droplet Vaporization ◽  
Bubble Cloud

Abstract Acoustic droplet vaporization (ADV) has proven to enhance high intensity focused ultrasound (HIFU) thermal ablation of tumor. It has also been demonstrated that triggering droplets before HIFU exposure could be a potential way to control both the size and the shape of the thermal lesion. In this paper, a numerical model is proposed to predict the thermal lesion created in ADV enhanced HIFU treatment. Bubble oscillation was coupled into a viscoelastic medium in the model to more closely represent real applications in tissues. Several physical processes caused by continuous wave ultrasound and elevated temperature during the HIFU exposure were considered, including rectified diffusion, gas solubility variation with temperature in the medium, boiling, etc. Four droplet concentrations spanning two orders of magnitude were calculated. The bubble cloud formed from triggering of the droplets by the pulse wave ultrasound, along with the evolution of the shape and location of the bubble cloud and thermal lesion during the following continuous wave exposure were obtained. The increase of bubble void fraction caused by continuous wave exposure were found to be consistent with the experimental observation. With the increase of droplet concentration, the predicted bubble cloud shapes vary from tadpole to triangular and double triangular, while the thermal lesions move toward the transducer. The results show that the assumptions used in this model increased the accuracy of the results. This model may be used for parametrical study of ADV enhanced HIFU treatment and be further used for treatment planning and optimization in the future.

WE-E-304A-05: Acoustic Droplet Vaporization for Enhancement of High Intensity Focused Ultrasound Thermal Ablation

2009 ◽  
Vol 36 (6Part26) ◽  
pp. 2786-2787
Author(s):  
M Zhang ◽  
KJ Haworth ◽  
SD Swanson ◽  
ML Fabiilli ◽  
OD Kripfgans ◽  
...  
Keyword(s):  
High Intensity ◽  
Thermal Ablation ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Acoustic Droplet Vaporization ◽  
Droplet Vaporization

scholarly journals Acoustic Droplet Vaporization in Biology and Medicine

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Chung-Yin Lin ◽  
William G. Pitt
Keyword(s):  
Drug Delivery ◽  
Contrast Agent ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Superheated Liquid ◽  
Clinical Use ◽  
Vessel Occlusion ◽  
Acoustic Droplet Vaporization ◽  
Droplet Vaporization ◽  
Preclinical Trials

This paper reviews the literature regarding the use of acoustic droplet vaporization (ADV) in clinical applications of imaging, embolic therapy, and therapeutic delivery. ADV is a physical process in which the pressure waves of ultrasound induce a phase transition that causes superheated liquid nanodroplets to form gas bubbles. The bubbles provide ultrasonic imaging contrast and other functions. ADV of perfluoropentane was used extensively in imaging for preclinical trials in the 1990s, but its use declined rapidly with the advent of other imaging agents. In the last decade, ADV was proposed and explored for embolic occlusion therapy, drug delivery, aberration correction, and high intensity focused ultrasound (HIFU) sensitization. Vessel occlusion via ADV has been explored in rodents and dogs and may be approaching clinical use. ADV for drug delivery is still in preclinical stages with initial applications to treat tumors in mice. Other techniques are still in preclinical studies but have potential for clinical use in specialty applications. Overall, ADV has a bright future in clinical application because the small size of nanodroplets greatly reduces the rate of clearance compared to larger contrast agent bubbles and yet provides the advantages of ultrasonographic contrast, acoustic cavitation, and nontoxicity of conventional perfluorocarbon contrast agent bubbles.

scholarly journals Acoustic Droplet Vaporization for Enhancement of Thermal Ablation by High Intensity Focused Ultrasound

2011 ◽  
Vol 18 (9) ◽  
pp. 1123-1132 ◽  
Author(s):  
Man Zhang ◽  
Mario L. Fabiilli ◽  
Kevin J. Haworth ◽  
Frederic Padilla ◽  
Scott D. Swanson ◽  
...  
Keyword(s):  
High Intensity ◽  
Thermal Ablation ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Acoustic Droplet Vaporization ◽  
Droplet Vaporization

Treatment of murine tumors using acoustic droplet vaporization-enhanced high intensity focused ultrasound

2013 ◽  
Vol 58 (17) ◽  
pp. 6179-6191 ◽  
Author(s):  
Meili Zhu ◽  
Lixing Jiang ◽  
Mario L Fabiilli ◽  
Aili Zhang ◽  
J Brian Fowlkes ◽  
...  
Keyword(s):  
High Intensity ◽  
Focused Ultrasound ◽  
High Intensity Focused Ultrasound ◽  
Acoustic Droplet Vaporization ◽  
Droplet Vaporization ◽  
Murine Tumors
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