Figures & data
Figure 3. (a) Measured temperature rise (labeled ‘Thermocouple’) and PCD output (labeled ‘PCD’) as a function of time for a 1-s 1.1-MHz HIFU insonation of an agar-graphite tissue phantom at three different pressure amplitudes. No inertial cavitation occurs in (iii), whilst cavitation onsets halfway through the exposure in (ii) and at the start of exposure in (i). In (ii) and (iii), there is a dramatic increase in the observed rate of heating that is coincident with the onset of inertial cavitation activity. (b) Peak temperature rise with respect to ambient conditions vs. peak-positive acoustic pressure for the agar/graphite phantom subjected to 700-ms bursts of HIFU. The thermocouple is positioned in the HIFU focal plane 0.5 mm off axis. The ‘Linear Theory’ curve is computed from the bioheat transfer equation (BHTE) using the known pressure field characteristics. This phantom was only slightly degassed [81, 99, 137].
![Figure 3. (a) Measured temperature rise (labeled ‘Thermocouple’) and PCD output (labeled ‘PCD’) as a function of time for a 1-s 1.1-MHz HIFU insonation of an agar-graphite tissue phantom at three different pressure amplitudes. No inertial cavitation occurs in (iii), whilst cavitation onsets halfway through the exposure in (ii) and at the start of exposure in (i). In (ii) and (iii), there is a dramatic increase in the observed rate of heating that is coincident with the onset of inertial cavitation activity. (b) Peak temperature rise with respect to ambient conditions vs. peak-positive acoustic pressure for the agar/graphite phantom subjected to 700-ms bursts of HIFU. The thermocouple is positioned in the HIFU focal plane 0.5 mm off axis. The ‘Linear Theory’ curve is computed from the bioheat transfer equation (BHTE) using the known pressure field characteristics. This phantom was only slightly degassed [81, 99, 137].](/cms/asset/b5b18543-3565-4774-a0e4-529cf8857772/ihyt_a_235260_f0001_b.gif)