Temperature rise vs. time. Temperature rise as a function of time for (a) the phantom study and (b) the lamb study. Curves for both the hottest voxel in the focal spot (solid lines) and the mean of the ten hottest near-field voxels (dashed lines) are shown, both when focusing in the plane most distal to the transducer (red lines) and when focusing in a plane more proximal to the transducer (blue lines). For the phantom, the focal spot can be seen to heat more than the near field, whereas in the lamb study, the near field experiences greater temperature rises than at the focal spot. In both cases, the near field reaches the peak temperature after the US is turned off and cools slower than the focal spot. Green arrows indicate when the US was applied.