Fig. 2 :

Numerical simulations of ultrasound propagation with different single-element transducers (top to bottom: 1, 2, 3) emitting pulses of variable length (left to right: 1, 5, 25, 2,500 cycles). Transducer 3 was the only configuration that was able to treat deep structures without presenting multiple sidelobes within the human skull. Color bar: normalized focal pressure. Each pressure profile was self-normalized to the maximum acoustic pressure within the skull to illustrate the −3dB focal volume. Pressure values refer to the maximum instantaneous pressure at each location.