Evaluation of heating patterns generated by therapeutic ultrasound insonation in muscle phantoms

The present work aims at studying the effect of heating patterns generated by therapeutic ultrasound (US) insonation on tissue mimicking device called Phantom. With this purpose, it was constructed a cylindrical calorimeter (80 mm height and 42 mm diameter) which was filled with muscle mimic phantom, for acquisition of temperature an array of thermocouples was placed at 2 and 6 cm depth. Ultrasound physiotherapy equipment was used at two therapeutic frequency (1 and 3 MHz), three intensities, and continuous irradiation mode and applied for 300s static mode. The experimental temperatures elevation profiles in Phantom were compared to a 2D bio-heat equation model, permitting a critical evaluation of such experimental data. The acoustic heating model was based on the US absorption equation, assuming linear propagation and neglecting stationary wave and multiplies reverberation effects. The comparison between experimental and mathematical simulation for the central thermocouple showed that, for far field the correlation between the experimental and simulated values are higher than for the near field.