Fig. 3.

Normalised simulated 2D spatial distribution of acoustic pressure fields without (a, b) and with (c, d) the presence of a bubble at the HIFU focus under linear propagation conditions. (a) and (c) are the simulated positive pressure fields p₊ whereas (b) and (d) are the magnitude of the computed negative pressure fields |p_-|. A bubble with a radius of 386 μm is indicated by an arrow in (c) and (d). The 1.0 MHz HIFU beam propagates from left to right. The simulations were performed over t = 60 μs. A bubble was modelled as a stationary 2D infinite cylinder.