Steering capabilities of an acoustic lens for transcranial therapy: numerical and experimental studies

Guillaume Maimbourg (1) , Alexandre Houdouin (1) , Thomas Deffieux (1) , Mickaël Tanter (1) , Jean-François Aubry (1)

1 Physique des ondes pour la médecine

Brain therapy by transcranial focused ultrasound needs to compensate for the delays locally induced by the skull. The patient-specific phase profile is currently generated by a multi-element array with a growing number of elements. We recently introduced a disruptive approach, consisting in using a single element transducer coupled to an acoustic lens of controlled thickness: by adjusting the local thickness of the lens, we were able to induce a phase difference which compensated that of the skull. Nevertheless, such an approach suffers from an apparent limitation: the lens is a priori designed for one specific target. In this paper, we demonstrate the possibility of taking advantage of the isoplanatic angle of the aberrating skull in order to steer the focus by mechanically moving the transducer/acoustic lens pair around its initial focusing position. This study, conducted on three human skull samples, confirms that tilting of the transducer with the lens restores a single focus at 914 kHz for a steering up to 11mm in the transverse direction, and 10mm in the longitudinal direction, around the initial focal region. Acoustic lens, transcranial ultrasound, therapeutic ultrasound

Domaines: Ingénierie biomédicale; Acoustique [physics.class-ph]

Guillaume Maimbourg, Alexandre Houdouin, Thomas Deffieux, Mickaël Tanter, Jean-François Aubry. Steering capabilities of an acoustic lens for transcranial therapy: numerical and experimental studies. IEEE Transactions on Biomedical Engineering, 2018, pp.1-1. ⟨10.1109/TBME.2019.2907556⟩. ⟨hal-02411218⟩