Evaluation of temperature rise in a tissue mimicking material during HIFU exposure

High‐Intensity Focused Ultrasound‐Induced Thermal Effect for Solid Polymer Materials

“…However, even though some investigations of ultrasound‐induced thermal effect on polymer have been conducted, there are few reports on the HIFU‐induced thermal effect on a solid polymer matrix. For the determination of the ultrasound‐induced temperature rise of the polymer materials, the thermocouple method is normally used; however, it may produce thermocouple artifacts, which arise from the conduction of heat along the thermocouple wire, or from differences in the heat capacity or absorption between the thermocouple and the surrounding medium . Infrared thermal imaging is an effective way to investigate the HIFU‐induced phantom thermal effect, and this non‐invasive temperature record method will not interrupt the HIFU process…”

In VitroDemonstration of Focused Ultrasound Thrombolysis Using Bifrequency Excitation

“…Heating induced by ultrasound wave for a given intensity appeared to be the same for both types of excitation: spatial temperature profiles and temperature maxima measured using MR thermometry in muscle samples were basically identical at a given applied P ac value. In fact, the use of bifrequency HIFU to enlarge heating lesions in tissue is valid only for amplitudes higher than the cavitation threshold [ 35 ], while the constant slopes observed on curves from Figure 8 suggest that no increase of absorption due to the presence of cavitation bubbles occurred during experiments. As for aspects related to the nonlinear propagation of the wave, it was explained in [ 25 ] that even for high peak-to-peak amplitude the waveforms should not be shocked because the distance of shock formation is several times higher than the axial length of the −3 dB focal volume (20 mm).…”