Transcranial ultrasound focusing

A method for generating an ultrasound intensity-peak within a human subject brain around a target-peak-location, by delivering ultrasound through a skull of the human subject, the skull having an outer-facing surface, the method comprising:

• a. providing an array of ultrasound transducers (AUT);
• b. operating at least some transducers of the AUT to subject the skull to at least L ultrasound skull-probe (USP) events {USP-event1, USP-event2 . . . USP-eventL} (L is a positive integer;
• L≥5) such that:
• (i) during each USP-eventi, a respective ultrasound test signal UTSi emitted by one or more transducer(s) of the AUT probes the skull to produce a maximum intensity at a different respective event-specific skull-surface location max_intensity_SOS_LOC(USP-eventi) that is on the outer-facing surface of the skull, said respective event-specific skull-surface location max_intensity_SOS_LOC(USP-even) being specific for USP-eventi;
• (ii) each USP-eventi is defined by a different respective dominant emission-locale DEL(USP-eventi) such that during each USP-eventi at least 50% of power of the respective ultrasound test signal UTSi received at the respective skull-surface location max_intensity_SOS_LOC(USP-eventi) on the skull is supplied by transmitter(s) of the AUT whose center(s) is(are) disposed within the dominant emission-locale DEL(USP-eventi), the dominant emission-locale DEL(USP-eventi) being spherical in shape with a radius of at most 0.5 cm;
• (iii) the dominant emission locales are distributed in space so that no two dominant emission locales [(DEL(USP-eventj), DEL(USP-eventk)](j≠k) (both j and k are positive integers equal to at most L) are displaced from each other to have a center-center distance of less than 2 cm;
• c. for each USP-eventi having its respective ultrasound test signal UTSi and its respective dominant emission-locale DEL(USP-eventi), measuring a respective echo time-difference ETD(USP-eventi) between:
• (i) a first measured time T1(USP-eventi) at which the respective ultrasound test signal UTSi received into one of the transducers of the array;
• (ii) a second measured time T2(USP-eventi) at which the respective ultrasound test signal UTSi received into the same one or a different one of the transducers of the array;
• and
• d. operating at least some transducers of the AUT in focus-around-target-peak-location (FATPL) mode to simultaneously irradiate the skull, wherein step (d) is performed such that:
• A. the at least some transducers deliver ultrasound at relative phases computed from the echo time-differences measured in step (c);
• and
• B. the delivering of ultrasound from the at least some transducers generates the ultrasound intensity-peak within the human subject brain around the target-peak-location-9%.