WHAT CAN PHYSICS AND MODELLING DO FOR NEUROSURGEONS AND NEUROLOGISTS? J.-F. Aubry1 1Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, Paris, France e-mail: jean-francois.aubry@espci.fr OBJECTIVES This talk will give an overview of the underlying physics and modelling for transcranial brain therapy. METHODS Due to the increased defocusing effect of the human skull with increasing frequency, transcranial focusing techniques divide into two groups: (i) the use of very low frequencies (ii) the use of adaptive techniques based on Computed Tomography (CT) or Magnetic Resonance (MR) Imaging of the patient head. These approaches will be explained and reviewed RESULTS Beyond current techniques under clinical use, novel developments are on their way to meet the clinician’s needs for safer, more precise, and faster treatments. They will be reviewed in this talk. CONCLUSIONS Physics and modelling already plays a crucial role in MR guided transcranial ultrasonic brain therapy by estimating the phase delays used during treatments. But it will expend soon to patient selection guidance, automatic power adjustment and faster treatment time. ACKNOWLEDGEMENTS Supported by the Bettencourt Schueller Foundation and the "Agence Nationale de la Recherche" under the program ‘‘Future Investments’’ with the reference ANR-10-EQPX-15.