Synchronous heating of two local regions of a biological tissue phantom using automated targeting of phase conjugate ultrasound beams

Synchronous heating of two local regions of an absorbing medium by phase conjugate ultrasound beams focused on them has been experimentally demonstrated. A polymeric biological tissue phantom with two small air cavities scattering sound has been used as the medium irradiated by a $5$-MHz “probe” ultrasound beam. The scattered field is incident on a parametric device for ultrasonic wave phase conjugation. The conjugate and amplified field is self-adaptive focused on scatterers and heats the medium owing to the absorption of the ultrasonic energy. In this case, these regions are heated by about $5$ $^\circ$C in $70$ s. Only an insignificant increase in the temperature owing to the heat conduction effect is observed in the remaining volume of the phantom. The implemented effect can be used in medical applications of phase conjugate ultrasound beams.