FDTD simulation of finite-amplitude pressure and temperature fields for biomedical ultrasound

作者：Ibrahim M. Hallaj, Robin O. Cleveland · 发表于：The Journal of the Acoustical Society of America · 年份：1999 · DOI：10.1121/1.426776 · 被引用次数：167 · 研究领域：Ultrasound Imaging and Elastography、Ultrasound and Hyperthermia Applications、Photoacoustic and Ultrasonic Imaging

Full wave simulations provide a valuable tool for studying the spatial and temporal nature of an acoustic field. One method for producing such simulations is the finite-difference time-domain (FDTD) method. This method uses discrete differences to approximate derivatives in the governing partial differential equations. We used the FDTD method to model the propagation of finite-amplitude sound in a homogeneous thermoviscous fluid. The calculated acoustic pressure field was then used to compute the transient temperature rise in the fluid; the heating results from absorption of acoustic energy by the fluid. As an example, the transient temperature field was calculated in biological tissue in response to a pulse of focused ultrasound. Enhanced heating of the tissue from finite-amplitude effects was observed. The excess heating was attributed to the nonlinear generation of higher-frequency harmonics which are absorbed more readily than the fundamental. The effect of nonlinear distortion on temperature rise in tissue was observed to range from negligible at 1 MPa source pressure to an 80% increase in temperature elevation at 10 MPa source pressure.