Method for tuning lithotripsy frequency to target size

Patent metadata

Field	Value
Publication number	US-12364497-B2
Application number	US-202217937294-A
Country	US
Kind code	B2
Filing date	Sep 30, 2022
Priority date	Oct 1, 2021
Publication date	Jul 22, 2025
Grant date	Jul 22, 2025

Abstract

Methods and systems for tuning lithotripsy frequency to target size are disclosed. In one embodiment, a lithotripsy system for comminuting a stone in a body includes: a burst wave lithotripsy (BWL) therapy transducer configured to transmit smooth ultrasound waves within a burst of ultrasound waves toward the stone; and a controller configured to determine operating frequency of the ultrasound waves of the therapy transducer. The operating frequency of the ultrasound waves is determined as:

f
=

Const
.

c
d

where:
d is a diameter of the stone,
f is the frequency of the ultrasound waves,
c is a wave speed in the stone, and
Const. is a predetermined constant.

First claim

What is claimed is:

1. A lithotripsy system for comminuting a stone in a body, comprising:
a burst wave lithotripsy (BWL) therapy transducer configured to transmit smooth ultrasound waves within a burst of ultrasound waves toward the stone; and
a controller configured to determine an operating frequency of the ultrasound waves of the therapy transducer;
wherein the operating frequency of the ultrasound waves is determined as:

f
=

Const
.

c
d

where:
d is a diameter of the stone,
f is the frequency of the ultrasound waves,
c is a wave speed in the stone, and
Const. is a predetermined constant.

2. The lithotripsy system of claim 1 , wherein the wave speed c is a shear wave speed, and wherein Const. corresponds to ¾.

3. The lithotripsy system of claim 1 , wherein the operating frequency is a first operating frequency, wherein the first operating frequency operates to break the stone into fragments of a given size range, wherein the controller is configured to determine a second operating frequency such that the second operating frequency (f2) is determined as:

f
2

=

Const
.

c

d
2

where:
d 2 is a diameter of the fragments, and
f 2 is the frequency of the ultrasound waves.

4. The lithotripsy system of claim 3 , wherein the therapy transducer is a first therapy transducer capable of generating the first operating frequency, the system comprising a second therapy transducer capable of generating the second operating frequency.

5. The lithotripsy system of claim 3 , wherein the second operating frequency is determined based on a target size of the fragments as:

f
2

≥

Const
.

c

d
final

where:
d final is a final target diameter of the fragments.

6. The lithotripsy system of claim 1 , wherein the burst of ultrasound waves of the BWL therapy transducer comprises at least 5 cycles of the ultrasound waves.

7. The lithotripsy system of claim 1 , wherein the burst of ultrasound waves of the BWL therapy transducer comprises at least 8 cycles of the ultrasound waves.

8. The lithotripsy system of claim 1 , wherein the ultrasound waves of the BWL therapy transducer are transmitted as the bursts of ultrasound waves, wherein the bursts of ultrasound waves are repeated in a frequency of 10 Hz.

9. The lithotripsy system of claim 1 , wherein the waves of the BWL therapy transducer are transmitted as bursts of ultrasound waves, wherein the bursts are repeated in a frequency of 20 Hz.

10. The lithotripsy system of claim 1 , wherein the burst wave lithotripsy (BWL) therapy transducer generates an acoustic pressure p 0 in a focal plane and a principal stress T zz in the stone, and wherein a ratio of T zz /p 0 is higher than 2.

11. The lithotripsy system of claim 10 , wherein the burst wave lithotripsy (BWL) therapy transducer causes an acoustic pressure p 0 in a focal plane and a principal stress T zz in the stone, and wherein a ratio of T zz /p 0 is higher than 4.

12. The lithotripsy system of claim 1 , wherein the ultrasound waves are sinusoidal waves.

13. A method for comminuting a stone in a body using an ultrasound, comprising:
determining an operating frequency of smooth ultrasound waves of a burst wave lithotripsy (BWL) therapy transducer, wherein the therapy transducer is configured to transmit the ultrasound waves within bursts of ultrasound waves at the operating frequency toward the stone; wherein the operating frequency is determined as:

f
=

Const
.

c
d

where:
d is a diameter of the stone,
f is the frequency of the ultrasound waves,
c is a wave speed in the stone, and
Const. is a predetermined constant; and
transmitting the ultrasound waves at the operating frequency toward the stone.

14. The method of claim 13 , wherein the wave speed c is a shear wave speed, and wherein Const. corresponds to ¾.

15. The method of claim 13 , wherein the operating frequency is a first operating frequency, wherein the first operating frequency operates to break the stone into fragments of a given size range, wherein a second operating frequency (f2) is determined as:

f
2

=

Const
.

c

d
2

where:
d 2 is a diameter of the fragments, and
f 2 is the frequency of the ultrasound waves.

16. The method of claim 15 , wherein the therapy transducer is a first therapy transducer capable of generating the first operating frequency, the method comprising generating the second operating frequency by a second therapy transducer.

17. The method of claim 13 , wherein the operating frequency of the ultrasound waves (f final ) is determined based on a target size of stone fragments as:

f
final

≥

Const
.

c

d
final

where:
d final is a final target diameter of the fragments.

18. The method of claim 17 , wherein entire treatment is executed with the therapy transducer operating at the operating frequency of the ultrasound waves f final .

19. The method of claim 13 , wherein the therapy transducer generates an acoustic pressure p 0 in a focal plane and a principal stress T zz in the stone, and wherein a ratio of T zz /p 0 is higher than 2.

20. The method of claim 19 , wherein the therapy transducer generates an acoustic pressure p 0 in a focal plane and a principal stress T zz in the stone, and wherein a ratio of T zz /p 0 is higher than 4.

21. The method of claim 13 , wherein the ultrasound waves are sinusoidal waves.

Assignees

• Univ Washington

Inventors

• Bailey Michael R
• Maxwell Adam D
• Sapozhnikov Oleg A

Classifications

• A61B2017/00141

  continuous, e.g. wave · CPC title

• A61B2017/00146

  with multiple frequencies · CPC title

• A61B2017/00402

  Piezo electric actuators · CPC title

• A61N2007/0056

  Beam shaping elements · CPC title

• A61N2007/006

  Lenses · CPC title