Inertial cavitation activity, quantified by the standard deviation of the signal received by a 15 MHz passive cavitation detection transducer confocally aligned with the ultrasound source, for a 2 s 0.5 MHz continuous-wave HIFU exposure in degassed liver, starting at t = 2 s and ending at t = 4 s. At low peak rarefactional pressures, there is little cavitation activity; however, at an acoustic pressure of 2.14 MPa, cavitation activity to rapidly increase approximately 0.5 s into the exposure period (Ref. 3).
The effect of transients of the Keller-Miksis equation on the rectified diffusion process for a 2 μm bubble: (a) Radius-time profile; the square marks the “zero point” of steady state oscillation. (b) Bubble growth rate with and without Keller–Miksis transients.
The effect of initial concentration profile on the rectified diffusion process for a 2 μm bubble: (a) Changes in the nondimensional mass increase and (b) changes in the nondimensional concentration profile after 100 μs of insonation.
Variation in radius-time profiles at 1 MHz for equilibrium bubble sizes of (a) μm, driven at 500 kPa, and (b) μm, driven at 1 MPa.
The effect of the individual temperature dependences on growth rates for a 2 μm bubble. Traces at 20 and 60 °C are provided for comparison.
(a) Variation in the rectified diffusion threshold at elevated temperatures. (b) Variation relative to the threshold at 20 °C.
Comparison of rectified diffusion and inertial cavitation thresholds at (a) 20 °C and (b) 60 °C.
Effect of temperature dependences on parameter values.
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