Ablation Effect of High Intensity Focal Ultrasound with Bubbles
Date Issued
2009
Date
2009
Author(s)
Fan, Wen-Feng
Abstract
A current topic of interest for high intensity focused ultrasound (HIFU) treatments involves the role of bubbles as a heating mechanism. At high amplitudes, nonlinear propagation leads to the generation of boiling bubbles within milliseconds; at lower amplitudes, cavitation bubbles can enhance heating through viscous dissipation, acoustic radiation, and heat conduction.n this study, ablation effects of phantom with and without bubbles were studied. The fast multipole method (FMM) was used to calculate the pressure field. The temperature field was calculated using a bio-heat transfer equation (BHTE) that took the pressure field as the input source. The BHTE was solved using ANSYS. In addition, an experimental platform was set up where critical experiments were conducted to study the ablation effects. Frequency of transducer and output electric power were varied to study the bubble effects. or the cased without bubbles, a cigar-shaped was observed in experiments and predicted in simulation. For the case with a single bubble, lesion was accumulated before the bubble and formed a tadpole-shape. The tiny cavitation bubbles occurred at low frequency could be reasonably simplified as a single bubble in simulation. We found that a larger radius of a single bubble would produce a larger lesion size. We concluded that cavitation bubbles and boiling bubbles share important characteristics and both enhance the lesion size and shape for HIFU.
Subjects
bubbles
HIFU
FMM
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-98-R95521610-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):7d2fe1e6d999878af7f4291f07e2fdcf