The EM simulation starts when the pulse starts. Because the EM fields in the whole computational region die out promptly after the pulse excitation,the EM simulation is ceased as the pulse ends. The acoustic wave evolution during the 1-μs pulse cannot be ignored because it can travel as much as 1.5 mm that is comparable to the target size (1-mm radius). In other words, the stress confinement condition [27] is not satisfied. Therefore, it is imperative to take into account the acoustic wave generation and radiation during the microwave pulse to guarantee accuracy.In the acoustic FDTD simulations, SAR used in (4) is calculated from (2) at every discretized time points within the 1-μs pulse duration and is zero after that.Termination of the acoustic simulation depends on the distance between the thermoacoustic source and the transducers. The simulated acoustic pressures at the transducers are recorded during the entire acoustic FDTD computational time period and utilized for the beam forming and image formation.