Can acoustic vortices fragment kidney stones?

Abstract

Burst wave lithotripsy (BWL) is an ultrasound-based technique used to fragment kidney stones. In this proof-of-concept, we test a novel approach based on acoustic vortices to improve the efficiency of stone fragmentation. Acoustic vortices are wavefronts containing phase dislocations which carry pseudo-orbital angular momentum. These beams can be synthesized and focused by spherical phased arrays which also enable beam steering and control the topological charge of vortices. Experiments were conducted using real and artificial kidney stones in water using a 128-channel therapeutic ultrasound phased-array transducer with 1.1-MHz central frequency. Sinusoidal-pulsed bursts of 20 cycles at 200-Hz pulse repetition frequency were generated. A confocal 128-element imaging probe monitored stones, while a camera recorded the fragmentation. Conventional BWL and single topological-charge vortices were compared using same rarefaction pressure and, additionally, same energy. Artificial stones (Bego-stone) and real stones (calciumoxalate-monohydrate and brushite) were tested. We observe that fragmentation speed is enhanced in a factor of two using vortices in artificial and real stones. Furthermore, vortices are a kind of defocused beams. Therefore, the mechanical index using vortices is lower than using BWL, resulting in a potentially less injurious therapy for surrounding tissues. These results demonstrate that acoustic vortices can enhance fragmentation using low-amplitude focused ultrasound.

@inproceedings{MaldonadoFA2025,
 author = {Sergio Maldonado-Ortega and Enrique González-Mateo and Alejandro Cebrecos and Cesar D. Vera-Donoso and Alicia Carrión and Francisco Camarena and Noé Jiménez},
 booktitle = {Forum Acusticum Euronoise 2025: 11th Convention of the European Acoustics Association. Málaga, Spain. 23-26 June},
 editor = {Conference proceedings},
 month = {09},
 organization = {European Acoustics Association, Sociedad Española de Acústica},
 pages = {1-1},
 series = {Oral},
 title = {Can acoustic vortices fragment kidney stones?},
 year = {2025}
}