This paper presents a new adaptive beamforming method for focusing ultrasound through the human skull, enhancing 3D transcranial imaging with small-aperture planar phased arrays. Conventional methods struggle with skull-induced distortions due to its complex structure, causing beam deflection and image inaccuracies. The proposed method uses a 2 MHz, 256-element matrix array probe to measure the skull profile and apply adaptive time delay patterns, compensating for refraction and restoring beam focus. The method was theoretically and experimentally validated, showing significant improvements in targeting accuracy.