High-Intensity Focused Ultrasound: Heating and Destruction of Biological Tissue

The results of a numerical study of heating and destruction of a biological tissue under the action of a series of focused ultrasound pulses generated by a multielement array (tumor treatment programs) are presented. Irradiation programs are considered that differ in the locations of focal points within a tissue (the Archimedean and “square” spirals), the number of pulses in the series, and the time delay between pulses. A significant influence of the parameters of the pulse series and perfusion process on the size of the thermal lesion area in a tissue was established in a considered range of moderate intensities of radiation. It was shown that the heat propagation process in the tissue turns with time to a quasi-spherical pattern and is weakly dependent on the irradiation program type. This characteristic of the process is discussed in terms of its possible use to optimize protocols of medical procedures utilizing focused ultrasound.