A computational investigation of cavitation-induced traumatic brain injury as a result high-powered microwave exposure

Prior work by Dagro et al. (2021) has shown that high-powered microwave exposure can lead to rapid thermal expansion of brain tissue and has a strain-focusing effect. The rapid increase in thermal strain causes pressure waves to form in the brain and reverberate as tensile waves. This study investigates the possibility of tissue damage from these tensile waves through the growth of intrinsic cavitation nuclei. Cavitation is modeled using the Keller–Miksis equation modified to incorporate viscoelastic effects. A fourth-order variable time step Runge-Kutta scheme calculates bubble radii and wall velocities from the pressure profile. Our simulations show that the maximum hoop stretch caused by high-powered microwave exposure considered in Dagro et al. (2021) is less than the threshold needed to cause morphological degeneration in neural cells, as given in Estrada etal. (2021). By performing a parameter sweep, we find that pressures 1000 times larger than those reported by Dagro et al. (2021) are needed to cause injury. These correlations can help provide safety limits against brain injury due to microwave energy.