CN-122028860-A - Imaging and treatment device for mechanical linear ablation

Abstract

An ultrasound-based surgical system is provided for image guidance and mechanical ablation for performing minimally invasive procedures, particularly procedures requiring removal of tissue. The system includes a device having an elongated body portion supporting a therapeutic ultrasound transducer assembly comprising a piezoelectric composite and an annular electrode array. The electrodes may be driven to generate focused ultrasound pulses for ablating tissue via cavitation. The device may be controlled to scan a focused ultrasound pulse within the elongate axial region for performing a linear ablation. An electrical isolation layer is formed over the annular electrode array to prevent arcing within the backing when high voltage electrical pulses are delivered to the annular electrode array to generate ultrasonic pulses for cavitation. The elongate body may support the imaging transducer assembly within the central aperture of the therapeutic ultrasound transducer assembly to facilitate image guidance during an ablation procedure.

Inventors

• M. G. Marley
• J.A. Brown

Assignees

• 达克索尼克超声公司

Dates

Publication Date

20260512

Application Date

20240913

Priority Date

20230913

Claims (20)

1. 1. A therapeutic ultrasound system for performing tissue ablation via cavitation, the therapeutic ultrasound system comprising: A therapeutic ultrasound transducer assembly, the therapeutic ultrasound transducer assembly comprising: a piezoelectric composite layer having a proximal surface and a distal surface; An annular electrode array disposed on the proximal surface of the piezoelectric composite layer; a common electrode disposed on the distal surface of the piezoelectric composite layer; an electrical isolation layer disposed on the annular electrode array on the proximal surface of the piezoelectric composite layer; An elongate body, wherein the therapeutic ultrasound transducer assembly is supported at a location remote from a proximal end of the elongate body; An electrical signal transmission assembly disposed along at least a portion of the elongate body, wherein the electrical signal transmission assembly is operatively connected to the therapeutic ultrasound transducer assembly such that electrodes of the annular electrode array are in electrical communication with respective electrical channels of the electrical signal transmission assembly and such that the common electrode is in electrical communication with a common electrical channel of the electrical signal transmission assembly, and A control and processing circuit operatively coupled to the therapeutic ultrasound transducer assembly through the electrical signal delivery assembly, the control and processing circuit configured to generate electrical pulses that are delivered through the electrical signal delivery assembly to the annular electrode array for generating focused ultrasound pulses suitable for generating cavitation in water, and Wherein the thickness of the electrically isolating layer is less than the wavelength of the focused ultrasound pulse within the electrically isolating layer, and Wherein the thickness of the electrical isolation layer and the dielectric breakdown strength of the electrical isolation layer are sufficiently high to prevent arcing between adjacent electrodes of the annular electrode array within the backing of the therapeutic ultrasound transducer assembly during generation of the focused ultrasound pulses for cavitation.
2. 2. The therapeutic ultrasound system of claim 1, wherein the piezoelectric composite layer is configured such that between at least one pair of adjacent electrodes of the annular electrode array, an annular kerf extends into the piezoelectric composite layer from the proximal surface, and wherein an electrically insulating material forming the electrically isolating layer is located within each annular kerf.
3. 3. The therapeutic ultrasound system of claim 2, wherein at least one annular slit extends from the proximal surface to the distal surface.
4. 4. The therapeutic ultrasound system of claim 2, wherein each annular slit extends from the proximal surface to the distal surface.
5. 5. The therapeutic ultrasound system of claim 2, wherein at least one annular slit is a partial slit extending from the proximal surface into the piezo-composite but not extending to the distal surface.
6. 6. The therapeutic ultrasound system of claim 2, wherein each annular slit is a partial slit extending from the proximal surface into the piezo-composite but not extending to the distal surface.
7. 7. The therapeutic ultrasound system of claim 5 or 6, wherein the partial kerfs have a depth of between 5% and 95% of a thickness of the piezo-composite.
8. 8. The therapeutic ultrasound system of claim 5 or 6, wherein the partial kerfs have a depth of between 5% and 90% of a thickness of the piezo-composite.
9. 9. The therapeutic ultrasound system of claim 5 or 6, wherein the partial kerfs have a depth of between 5% and 75% of a thickness of the piezo-composite.
10. 10. The therapeutic ultrasound system of claim 5 or 6, wherein the partial kerfs have a depth of between 50% and 95% of a thickness of the piezo-composite.
11. 11. The therapeutic ultrasound system of claim 5 or 6, wherein the partial kerfs have a depth of between 50% and 90% of a thickness of the piezo-composite.
12. 12. The therapeutic ultrasound system of claim 5 or 6, wherein the partial kerfs have a depth of between 50% and 75% of a thickness of the piezo-composite.
13. 13. The therapeutic ultrasound system of any one of claims 2-12, wherein a thickness of the electrical isolation layer on each electrode of the annular electrode array exceeds a width of the annular kerf.
14. 14. The therapeutic ultrasound system according to any one of claims 2 to 13, wherein the piezocomposite layer comprises an array of piezoelectric pillars embedded in a matrix, the piezoelectric pillars extending from the proximal surface to the distal surface, and wherein the piezoelectric pillars are arranged in a segmented annular array comprising a plurality of concentric arrays of piezoelectric pillars such that each electrode of the annular electrode array is capable of electrically actuating one or more radially continuous arrays of piezoelectric pillars, and such that each annular kerf is aligned with and extends into an annular matrix region located between a respective pair of radially adjacent concentric arrays of piezoelectric pillars.
15. 15. The therapeutic ultrasound system of any one of claims 1-14, wherein the electrically isolating layer has a dielectric breakdown strength of between 10 kV/mm and 280 kV/mm.
16. 16. The therapeutic ultrasound system according to any one of claims 1-15, wherein the therapeutic ultrasound transducer assembly is air-backed.
17. 17. The therapeutic ultrasound system according to any one of claims 1-15, wherein the therapeutic ultrasound transducer assembly comprises a backing layer embedded with micro-balloons.
18. 18. The therapeutic ultrasound system of any one of claims 1-17, wherein the annular electrode array is defined such that a lateral electrode spacing is between 20 microns and 80 microns.
19. 19. The therapeutic ultrasound system of any one of claims 1-17, wherein the annular electrode array has an outer diameter of between 10 mm and 25mm, and wherein the number of electrodes forming the annular electrode array is between 8 and 64.
20. 20. The therapeutic ultrasound system according to claim 1, wherein the piezoelectric composite layer comprises an array of piezoelectric pillars embedded in a matrix, the piezoelectric pillars extending from the proximal surface to the distal surface, and wherein the piezoelectric pillars are arranged in a segmented annular array comprising a plurality of concentric arrays of piezoelectric pillars such that each electrode of the annular electrode array is capable of electrically actuating one or more radially-continuing arrays of piezoelectric pillars, and such that each annular electrode gap is aligned with an annular matrix region located between a respective pair of radially-adjacent concentric arrays of piezoelectric pillars.

Description

Imaging and treatment device for mechanical linear ablation Cross Reference to Related Applications The present application claims priority from U.S. provisional patent application No. 63/538,163, entitled "IMAGING AND THERAPY DEVICE FOR MECHANICAL LINE ABLATION (imaging and therapy device FOR mechanical linear ablation)" filed on 9/13 of 2023, the entire contents of which are incorporated herein by reference. Background The present disclosure relates to therapeutic ultrasound. More particularly, the present disclosure relates to devices for performing tissue ablation via tissue fragmentation (histotripsy). Numerous tools are specifically designed for minimally invasive surgery, which exhibit varying sizes and mechanisms of tissue removal. These tools include more traditional ablation tools such as micro-cutters, micro-forceps and micro-graspers, which may be employed using endoscopic or laparoscopic form factors. There are also many endoscopic thermal ablation-based instruments that use various techniques to remove tumor tissue through high temperature lesions, including RF ablation, microwave ablation, focused ultrasound ablation, or laser ablation, and cryoablation that uses liquefied gas to enhance the efficacy of RF ablation. Almost all current endoscopic ablation tools are thermal ablation tools, which suffer from the disadvantage of substantially damaging adjacent tissue outside the treatment area and leaving scar tissue in situ within the ablation area. One of the few examples of non-thermal endoscopic ablation tools is an ultrasonic surgical aspirator, which acts as a miniature vibrating saw. Although these instruments effectively ablate tissue without heating, there is a lack of precision at the target ablation site. However, the most significant shortcoming of these conventional endoscopic ablation tools is that the ablation zone is in contact with the tip of the endoscope. This means that when ablating a superficial lesion directly beneath the skin (or tongue) surface, an open wound must be created to gain access to the lesion, causing complications such as bleeding and infection. While cavitation is known to be useful for tissue ablation, the latest technology of ablation based on ultrasonic cavitation (tissue fragmentation) involves very large transducers designed to ablate tissue from a distance. This means that the transducer is required to be large in size and operate at low frequencies. Recently, there have been some efforts to develop smaller, higher frequency endoscopic tissue fragmentation transducers with greater accuracy. These were developed for minimally invasive surgery and small access surgery. However, these devices are based on the use of single element piezoelectric transducers, with passive fixed focus acoustic lenses applied to the front to passively focus the ultrasound beam (e.g., J.K. Woodacre and J. Brown, "TRANSDUCER ASSEMBLY FOR GENERATING FOCUSED ULTRASOUND (transducer assembly for producing focused ultrasound)", US 2020/0346044 A1,2020;T.G. Landry et al, "Endoscopic Coregistered Ultrasound IMAGING AND Precision Histotripsy: INITIAL IN Vivo Evaluation (endoscopic co-registered ultrasound imaging and accurate tissue fragmentation: preliminary in Vivo Evaluation)", BME front, 2022, doi:10.34133/2022/9794321; and Maxwell, R. Hsi, T. Lendvay, P. Casale and M. Bailey, "FOCUSED ULTRASOUND APPARATUS AND METHODS OF USE (focused ultrasound device and method of use)", US/0287909A 1, 2016). A disadvantage of such lens-based designs is that due to the strong curvature of the fixed focus lens, acoustic coupling to the tissue may be difficult because the area between the curved lens surface and the tissue to be ablated needs to be entirely filled with coupling material. Another disadvantage of such lens-based tissue fragmentation endoscopes is that the ablation zone is limited by the fixed focus of the lens. This may limit the ablation rate, as increasing the ablation zone requires a relatively slow mechanical translation of the transducer. Disclosure of Invention An ultrasound-based surgical system is provided for image guidance and mechanical ablation for performing minimally invasive surgery, particularly surgery requiring removal of tissue. The system includes a device having an elongated body portion supporting a therapeutic ultrasound transducer assembly comprising a piezoelectric composite and an annular electrode array. The electrodes may be driven to generate focused ultrasound pulses for ablating tissue via cavitation. The device may be controlled to scan a focused ultrasound pulse within the elongate axial region for performing a linear ablation. An electrical isolation layer is formed over the annular electrode array to prevent arcing within the backing when high voltage electrical pulses are delivered to the annular electrode array to generate ultrasonic pulses for cavitation. The elongate body may support the imaging transducer assembly within the central aperture of t