Fig. 3 :

Numerical simulations of ultrasound propagation with the clinical focused ultrasound (FUS) transducer targeting structures of variable depth within a human skull. Examples are shown for transducer axial offset of −30 mm to 20 mm (offset = 0mm when the focus in free field coincides with the midline). Center frequency: 0.25 MHz, pulse length: 2,500 cycles. 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.