System and method for comminution of biomineralizations using microbubbles
A system and method for ultrasound treatment is presented. The system and method alternatingly provide microbubbles in a target region containing a biomineralization, then insonate the microbubbles using an external ultrasound source. The microbubbles cavitate in the target region, destructively affecting the biomineralization and potentially breaking it or reducing its mass over time as a result of the cavitation action. Spatial orientation or alignment of the external ultrasound source may be achieved for best results using acoustic signatures and spectral representations of the same.
1 . A method for causing comminution of a biomineralization, comprising:
determining a target region in an internal volume that includes a biomineralization having an initial size and mass;
placing an external ultrasound source on a skin of a subject;
in a plurality of macrocycles, each macrocycle including a bubble placement stage followed by an insonation stage, introducing a plurality of microbubbles into said target region only during the bubble placement stage, and insonating the plurality of microbubbles with a treatment beam from the external ultrasound source during the insonation stage, the treatment beam delivering energy to said target region to cause inertial cavitation (IC) of at least some of the microbubbles only during the insonation stage, wherein the bubble placement stage and the insonation stage are repeated in an alternating manner during the plurality of macrocycles;
dynamically changing a focal depth of an acoustic sensor to measure an IC amplitude with respect to the focal depth to determine a depth of the biomineralization with respect to said acoustic sensor;
dynamically changing a spatial alignment of the external ultrasound source with respect to said biomineralization, by translating or pivoting the external ultrasound source on the skin of the subject, based on the IC amplitude measured by said acoustic sensor;
dynamically adjusting the treatment beam, including the position and the spatial alignment of said beam, based on the depth and relative position of the biomineralization;
wherein:
the ultrasound source emits ultrasonic energy at selected times during the insonation stage,
the ultrasound source does not emit ultrasonic energy during the bubble placement stage, and
the microbubbles are not introduced into the target region during the insonation stage;
and
using said delivered energy and IC to break said biomineralization into pieces having less size and mass than the initial biomineralization size and mass.
2 . The method of claim 1 , wherein the external ultrasound source is programmably activated during the insonation stage in a sequence of microcycle ON-times when the external ultrasound source is activated and microcycle OFF-times when the external ultrasound source is deactivated.
3 . The method of claim 1 , further comprising detecting an acoustic emission of said at least some of the microbubbles undergoing said inertial cavitation so as to derive a quantifiable inertial cavitation (IC) signature.
4 . The method of claim 1 , wherein insonating the plurality of microbubbles with an external ultrasound source comprises delivering an ultrasound energy beam having a fundamental frequency and having an amplitude sufficient to cause said inertial cavitation of said at least some of the microbubbles.
5 . The method of claim 1 , wherein the microbubbles comprise engineered microbubbles having a chemical tag.
6 . The method of claim 1 , wherein said microbubbles comprise stone-surface accumulating (SSA) microbubbles that tend to aggregate at or near said biomineralization.
7 . The method of claim 1 , wherein said acoustic sensor is integrated into said external ultrasound source as a transducer element therein.
8 . The method of claim 1 , wherein said acoustic sensor comprises a stand-alone sensor not integrated into said external ultrasound source.