Photoacoustic ultrasonic endoscopic tomography system and method based on sound film focusing

Abstract

The invention discloses a photoacoustic ultrasonic endoscopic tomography system and method based on sound piece focusing. The system comprises a photoacoustic ultrasonic endoscopic tomography probe based on sound piece focusing, a data acquisition card, a computer, a signal control circuit, a pulse laser and a drive control circuit. An excitation ultrasonic array of the probe is composed of a plurality of coaxial annular transducers, two adjacent half-aperture annular transducers emit ultrasonic waves in cross propagation at a set angle at the same time through a cross amplitude modulation sequence, and when two beams of annular sound waves meet in space, interference is performed to form a new sound field. The sound field has enhanced sound pressure on an annular plane, and an annular sound sheet layer is formed. According to the invention, the annular sound sheet transducer array is used as a row-column addressing transducer array, so that high-speed high-acoustic-resolution imaging is realized.

Description

Technical Field

[0001] The present invention relates to the research field of photoacoustic endoscopy, and particularly to a photoacoustic ultrasound endoscopy tomography system and an imaging method based on acoustic lens focusing. Background Art

[0002] Photoacoustic imaging technology is a biomedical imaging technology that combines the advantages of optical imaging and ultrasonic imaging. When a pulsed laser irradiates biological tissue, ultrasonic signals will be generated in the light absorption regions of the tissue. We call the ultrasonic signals generated by light excitation photoacoustic signals. The photoacoustic signals generated by the rapid heating and expansion of the light absorption medium in biological tissue carry the light absorption characteristic information of the tissue. By detecting the photoacoustic signals, an image of the light absorption distribution in the tissue can be reconstructed. Photoacoustic imaging has both the high selectivity characteristics of pure optical tissue imaging and the deep penetration characteristics of pure ultrasonic tissue imaging. High-resolution and high-contrast tissue images can be obtained through photoacoustic imaging. Currently, photoacoustic imaging technology has been applied to the field of endoscopic imaging.

[0003] Traditional photoacoustic imaging devices usually include a rotating motor to achieve full-round imaging of biological tissue. However, this rotating mechanism not only increases the complexity of the system, but also introduces additional noise signals, such as the vibration and noise generated by the rotation of the motor. These noise signals will interfere with the imaging quality and limit the accuracy and reliability of imaging. Summary of the Invention

[0004] The main object of the present invention is to overcome the deficiencies of the prior art, and provide a photoacoustic ultrasound endoscopy tomography system and an imaging method based on acoustic lens focusing. This system uses a stationary light source and an annularly arranged acoustic lens transducer array. By focusing this array on a specific annular acoustic lens layer, tomographic images of biological tissue can be obtained, thus eliminating the need for the traditional 360-degree scanning of the endoscopic probe driven by a rotating motor. Since there is no longer a need for a rotating scanning mechanism, such as complex components like smooth rings and electrical slip rings, the present invention not only enhances the overall stability of the system, but also simplifies the maintenance process and reduces the maintenance difficulty.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a photoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing, including a base, the base includes a first cylinder and a second cylinder arranged coaxially, and the diameter of the first cylinder is greater than the diameter of the second cylinder;

[0007] The interior of the second cylinder is a hollow structure, in which a Green lens is provided. The bottom of the second cylinder is provided with a transparent cylinder, and the top of the transparent cylinder is provided with a conical reflecting surface. An annular acoustic chip transducer array is sleeved outside the second cylinder. The annular acoustic chip transducer array includes a receiving ultrasonic array and an exciting ultrasonic array. The exciting ultrasonic array is composed of a plurality of coaxial annular transducers. By means of a cross amplitude modulation sequence, two adjacent half-aperture annular transducers simultaneously emit cross-propagating annular ultrasonic waves at a set angle. When two beams of annular acoustic waves meet in space, they interfere to form a new acoustic field. The acoustic field has enhanced sound pressure on the annular plane, forming an annular acoustic chip layer. The receiving ultrasonic array has a plurality of strip transducers bonded to the inner side of the receiving transducer, and is used for receiving ultrasonic and photoacoustic signals generated at the position of the annular acoustic chip layer.

[0008] The first cylinder is provided with a through hole for a single-mode optical fiber to pass through. After passing through the through hole of the first cylinder, the single-mode optical fiber is connected to the Green lens.

[0009] As a preferred technical solution, the outer wall of the transparent cylinder is transparent, the top is a conical reflecting surface at an angle of 60° with the central axis, and the bottom is provided with a cylindrical protrusion, and the cylindrical protrusion matches the hollow structure of the second cylinder.

[0010] As a preferred technical solution, the annular acoustic chip transducer array is a row-column addressed transducer array, and a cross amplitude modulation sequence is adopted to make the exciting ultrasonic array focus to generate an annular acoustic chip layer.

[0011] As a preferred technical solution, the single-mode optical fiber, the Green lens, and the transparent cylinder are coaxially fixed to the base in sequence.

[0012] As a preferred technical solution, the annular acoustic chip transducer array is fixed to the outer wall of the base by resin glue.

[0013] In a second aspect, the present invention provides a photoacoustic ultrasonic endoscopy tomography imaging system based on acoustic chip focusing, including the photoacoustic ultrasonic endoscopy tomography imaging probe based on acoustic chip focusing, and further including a data acquisition card, a computer, a signal control circuit, a pulsed laser, and a drive control circuit.

[0014] The data acquisition card is respectively connected to the computer and the signal control circuit. The computer is further connected to the pulsed laser and the drive control circuit. The signal control circuit is used to control two adjacent half-aperture annular transducers to simultaneously emit cross-propagating annular ultrasonic waves at a set angle.

[0015] The pulsed laser outputs a parallel beam after being connected to a collimating lens through a single-mode optical fiber. After being reflected by the conical reflecting surface, the beam passes through the outer wall of the transparent cylinder and the transparent sleeve, and hits the surrounding biological tissues to excite photoacoustic signals.

[0016] The driving control circuit is used to control the movement of the photoacoustic ultrasound endoscopy tomography probe based on acoustic sheet focusing;

[0017] The computer is used to store and process the collected data to complete the reconstruction of photoacoustic images and ultrasonic images.

[0018] As a preferred technical solution, the single-mode optical fiber is connected to the coupler of the pulsed laser through a standard optical fiber connector. The single-mode optical fiber and the Green lens are fixed inside the transparent sleeve through a base. The pulsed laser is connected to the Green lens through the single-mode optical fiber and then outputs a parallel light beam.

[0019] As a preferred technical solution, the annular acoustic sheet transducer array is led out along the inner groove of the transparent sleeve through a signal control and acquisition transmission line and connected to the signal control circuit. The signal control circuit controls the transducer array to simultaneously emit cross-propagating annular ultrasonic waves at a set angle through two adjacent semi-aperture annular transducers through the signal control and acquisition transmission line. When the two annular acoustic waves meet in space, an annular acoustic sheet layer is formed by interference. After the signal generated by the annular acoustic sheet transducer array is sent to the signal control circuit through the signal control and acquisition transmission line, it is sampled by a data acquisition card and sent to the computer for image reconstruction.

[0020] As a preferred technical solution, the driving control circuit is provided with a stepping motor. The stepping motor is connected to the driving control circuit through a control signal line, and the stepping motor is connected to the transparent sleeve through a torque wire.

[0021] In a third aspect, the present invention provides an imaging method for a photoacoustic ultrasound endoscopy tomography system based on acoustic sheet focusing, including the following steps:

[0022] (1) Excitation: After receiving the pulse signal generated by the computer, the signal control circuit controls the annular acoustic sheet transducer array to generate an annular acoustic sheet layer. After a period of delay, the pulse signal generated by the computer excites the pulsed laser to emit pulsed laser light. The pulsed laser light is incident on the single-mode optical fiber through the fiber optic coupler, and after passing through the Green lens, parallel outgoing laser light is generated. The parallel laser beam is incident on the conical reflecting surface to achieve a set angle of reflection, and the beam passes through the outer wall of the transparent cylinder and hits the surrounding biological tissue to excite photoacoustic signals;

[0023] (2) Data acquisition: The annular acoustic sheet transducer first receives the ultrasonic signal of the annular acoustic sheet layer. After a period of delay, the photoacoustic signal generated by the biological tissue at the annular acoustic sheet layer is detected again by the annular acoustic sheet transducer array. The two signals are successively transmitted to the AC / DC conversion module on the digital acquisition card through the signal control and acquisition transmission line for signal conversion, and finally the photoacoustic signal is transmitted and stored in the computer;

[0024] (3) Endoscopic scanning: After exciting the annular acoustic sheet layer and the laser and completing one two-dimensional ultrasound and photoacoustic scan, the computer controls the drive control circuit to make the photoacoustic ultrasound endoscopic tomography probe based on acoustic sheet focusing move forward or backward one step and then stop. Repeat the endoscopic scanning step to finally complete three-dimensional endoscopic scanning;

[0025] (4) Image reconstruction and display: The computer stores and processes the collected data to complete the reconstruction of photoacoustic images and ultrasound images.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The present invention first applies an annular acoustic sheet transducer array to photoacoustic endoscopy. This transducer array is made of flexible material, customized into a ring shape and fixed on the outer wall of the probe. Through signal control circuit regulation, two cross-propagating acoustic beams are emitted to generate an annular acoustic sheet layer around the endoscopic probe for 360 degrees and focus on the annular acoustic sheet layer. Therefore, this system can achieve endoscopic tomographic images with high acoustic resolution without a rotating motor; at the same time, it improves the detection sensitivity and the overall system and reduces the maintenance cost of the system.

[0028] (2) The present invention uses an annular acoustic sheet transducer array and leads out the signal control and acquisition transmission lines along the inner groove of the transparent sleeve to be connected to the signal control circuit, successfully avoiding the use of an optoelectronic slip ring, which not only improves the overall stability of the system but also reduces the maintenance problems and costs that may be brought by the optoelectronic slip ring.

[0029] (3) The present invention adopts a method of focusing on the annular acoustic sheet layer to receive photoacoustic signals by combining a row-column addressed transducer array with a cross-amplitude modulation sequence, achieving fast and high-acoustic-resolution imaging. By simultaneously emitting cross-propagating annular ultrasonic waves at a set angle through two adjacent half-aperture annular transducers, when the two annular acoustic waves meet in space, interference forms an annular acoustic sheet layer. This design ensures image quality while improving imaging speed, especially suitable for application scenarios that require high-precision positioning.

[0030] (4) The present invention only needs to respectively excite ultrasound and photoacoustic once to complete a complete ring-scan imaging process, greatly shortening the detection time required, making real-time scanning imaging possible. The formation of the annular acoustic sheet layer allows for more precise imaging of the target area, further enhancing the detection efficiency and accuracy.

[0031] (5) The photoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing of the present invention abandons the traditional motor rotation and its related control circuits, thus simplifying the structure of the entire device, making it smaller in size and more flexible in operation. In addition, this design can provide a faster response speed during the imaging process, further shortening the imaging time, supporting high-speed and high-acoustic-resolution imaging. The introduction of the annular acoustic lens layer also enables the imaging system to adjust the focal position without moving mechanical components, increasing the flexibility and adaptability of the system. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is the front view of the photoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing according to the embodiment of the present invention;

[0034] Figure 2 It is the sectional view of the photoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing according to the embodiment of the present invention;

[0035] Figure 3 Parts (a) and (b) in it are respectively the structure of the annular acoustic lens transducer array and the generation schematic diagram of the annular acoustic lens layer according to the embodiment of the present invention;

[0036] Figure 4 It is the block diagram of the photoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing according to the embodiment of the present invention.

[0037] Explanation of the Reference Numerals in the Drawings:

[0038] 1 - Data acquisition card, 2 - Computer, 3 - Signal control circuit, 4 - Pulse laser, 5 - Drive control circuit, 6 - Transparent sleeve, 7 - Signal control and acquisition transmission line, 8 - Single-mode optical fiber, 9 - Torque guide wire, 10 - Base, 11 - Annular acoustic lens transducer array, 12 - Green lens, 13 - Transparent cylinder, 14 - Conical reflecting surface, 15 - Annular acoustic lens layer, 16 - Sound field, 17 - Received ultrasound array, 18 - Excited ultrasound array, 19 - Semi-aperture. Detailed Embodiments

[0039] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of this application.

[0040] In this application, the mention of "embodiment" means that the specific features, structures or characteristics described in combination with the embodiment may be included in at least one embodiment of this application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art understand explicitly and implicitly that the embodiments described in this application can be combined with other embodiments.

[0041] As Figure 1 、 Figure 2 shown, a photoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing in this embodiment includes a base 10. The base includes a first cylinder and a second cylinder arranged coaxially, and the diameter of the first cylinder is greater than that of the second cylinder; the first cylinder and the second cylinder are integrally formed by casting, jointly constituting the base of the imaging probe.

[0042] Further, the inside of the second cylinder is a hollow structure. A GRIN lens 12 is arranged in the hollow structure. A transparent cylinder 13 is provided at the bottom of the second cylinder, and a conical reflecting surface 14 is provided at the top of the transparent cylinder 13; an annular acoustic transducer array 11 is sleeved outside the second cylinder. The annular acoustic transducer array 11 includes a receiving ultrasound array 17 and an exciting ultrasound array 18. The exciting ultrasound array is composed of a plurality of coaxial annular transducers. Cross-propagating annular ultrasonic waves are simultaneously emitted at a set angle by two adjacent annular transducers with a semi-aperture 19. When the two annular acoustic waves meet in space, interference forms a new acoustic field 16. The acoustic field has an enhanced acoustic pressure on a specific plane, forming an annular acoustic lens layer 15; the receiving ultrasound array 17 has a plurality of strip transducers bonded to the inner side of the receiving transducer, and can receive the ultrasonic and photoacoustic signals generated at the location of the annular acoustic lens layer.

[0043] Further, the first cylinder is provided with a through hole for a single-mode optical fiber 8 to pass through. After passing through the through hole of the first cylinder, the single-mode optical fiber is connected to the GRIN lens 12.

[0044] In a specific embodiment, the outer wall of the transparent cylinder 13 is transparent, the top is a conical reflecting surface 14 at an angle of 60° with the central axis, and the bottom is provided with a cylindrical protrusion which matches the hollow structure of the second cylinder. This unique geometric structure ensures that the incident light can be reflected at a specific angle, thus achieving a specific optical effect. At the bottom of the transparent cylinder, there is a specially designed cylindrical protrusion, which not only coordinates in shape with the transparent cylinder itself to achieve seamless docking with the hollow part of another component, that is, the second cylinder. This matching design ensures that the two components can be tightly connected while maintaining the connectivity of the internal space, making the overall device have both a stable mechanical connection and excellent optical performance.

[0045] In a specific example, as Figure 3 shown in parts (a) and (b) of

[0046] The annular acoustic chip transducer array 11 is a specially designed row-column addressed transducer array, which is composed of multiple independent transducer units arranged in an annular layout. Each transducer unit can be individually controlled and addressed, and specific units or a group of units are activated through the combination of rows and columns to achieve precise control of the entire array. The array adopts an advanced Interleaved Amplitude Modulation (IAM) sequence technology. During operation, the IAM sequence can dynamically adjust the voltage amplitude and phase applied to each transducer unit to generate a complex sound field distribution. This modulation method not only improves the resolution and contrast of the signal, but also allows the system to flexibly change the position and shape of the focus according to needs, making the focusing more accurate and efficient.

[0047] When used to receive photoacoustic signals, the annular acoustic chip transducer array 11 can concentrate on high-sensitivity detection at the annular acoustic chip layer. After the ultrasonic signals generated by the photoacoustic effect are captured by the transducers and processed by the IAM sequence, the clarity of shallow tissue imaging can be effectively enhanced without sacrificing image quality, and good penetration and spatial resolution can be maintained in deep tissues. Therefore, this design has important application value in the fields of biomedical imaging, non-destructive testing, etc.

[0048] Specifically, as a medium for optical signal transmission, a single-mode optical fiber is first installed at one end of the base. Its core diameter is extremely small, allowing only one mode of light to propagate, which ensures the high purity and low loss characteristics of the transmitted optical signal. To ensure efficient coupling between the optical fiber and subsequent components, the output end face of the optical fiber is usually polished finely and may be firmly fixed at a designated position on the base using optical glue or other means.

[0049] Next is the Grin Lens, which is a gradient-index lens that can convert the divergent light beam from the single-mode optical fiber into a parallel light beam or vice versa. The Grin Lens achieves the bending of the light path through the characteristic that its internal refractive index gradually changes from the center to the edge, without relying on the surface curvature. The lens is precisely positioned and fixed directly in front of the single-mode optical fiber to ensure the best optical coupling effect between the two. To maintain this high-precision alignment, a specially designed mechanical structure or adjustment device is usually employed to assist in the installation of the Grin Lens.

[0050] Finally, a transparent cylinder is installed after the Grin Lens. This cylinder has a transparent outer wall, with a conical reflecting surface at the top that forms a 60° angle with its central axis, and a cylindrical protrusion at the bottom that matches the hollow structure of the second cylinder. The transparent cylinder not only needs to be coaxial with the Grin Lens but also ensure that the special designs of its conical reflecting surface and bottom protrusion can fully play their roles. For this purpose, the transparent cylinder may be fixed to the base through a customized fixture or bracket system, while ensuring its position relative to the Grin Lens and the single-mode optical fiber is accurate, thus achieving an ideal optical path design and functional performance in the entire optical system.

[0051] As Figure 4 shown, in another embodiment of the present application, an optoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing technology is provided. The system mainly includes the following components: an ultrasound signal trigger and acquisition module, an image reconstruction and display module, an optoacoustic excitation module, a scan control module, and a transparent sleeve 6. The optoacoustic excitation module and the ultrasound signal trigger and acquisition module are integrated inside the transparent sleeve 6 and are connected to the image reconstruction and display module and the scan control module respectively through connecting wires.

[0052] Specifically, the optoacoustic excitation module (see Figure 4)It consists of a pulsed laser 4, a single-mode optical fiber 8, a GRIN lens 12, and a conical reflector 14. The single-mode optical fiber 8 is connected to the coupler of the pulsed laser through a standard fiber connector, ensuring efficient and stable optical transmission. The single-mode optical fiber 8 and the GRIN lens 12 are fixed on the base 10 and are located inside the transparent sleeve 6. The beam emitted by the pulsed laser is conducted through the single-mode optical fiber to the GRIN lens and then forms a parallel beam, which is reflected by the conical reflector and finally irradiates the biological tissues such as the intestinal wall or bronchus through the outer wall of the transparent cylinder, exciting photoacoustic signals.

[0053] The ultrasonic signal triggering and acquisition module includes an annular phased array transducer 11, a signal control and acquisition transmission line 7, a signal control circuit 3, and a data acquisition card 1. The annular phased array transducer adopts a row-column addressing structure and is fixed on the outer wall of the base by resin glue. The array is led out along the inner groove of the transparent sleeve through the signal control and acquisition transmission line and is connected to the signal control circuit. The signal control circuit controls two adjacent half-aperture 19 annular transducers in the transducer array to simultaneously emit cross-propagating annular ultrasonic waves 16 through the transmission line. When these ultrasonic waves meet in space, they will interfere to form an annular phased layer 15. The signals generated by the annular phased array transducer are transmitted to the signal control circuit through the signal control and acquisition transmission line, and then sampled by the data acquisition card and sent to the image reconstruction and display module for processing.

[0054] The scan control module includes a drive control circuit 5, a torque wire 9, and a stepping motor. The stepping motor is connected to the drive control circuit through a control signal line and is connected to the transparent sleeve through the torque wire to achieve precise adjustment of the position of the transparent sleeve. The drive control circuit is built with a stepping motor driver, receives pulse signals from the computer, and controls the stepping motor to act through the stepping motor driver, thereby driving the entire system to move axially to complete a tomographic scan.

[0055] The image reconstruction and display module is mainly composed of a computer 2, which is responsible for the overall coordination of the system. The computer is respectively connected to the drive control circuit, the pulsed laser, and the data acquisition circuit, used to send control instructions, receive data, and execute image reconstruction algorithms, and finally display the processed image information for users to view.

[0056] In summary, the imaging system of this embodiment integrates advanced optical and acoustic technologies, aiming to provide high-resolution in-vivo tissue images for medical diagnosis, and is particularly suitable for the examination of narrow cavities such as the digestive tract.

[0057] In another embodiment of the present application, an imaging method for a photoacoustic ultrasonic endoscopy tomography system based on phased focusing is provided, and the specific steps are as follows:

[0058] (1) System initialization and laser emission:

[0059] Start the photoacoustic ultrasound endoscopy imaging system. The computer generates a pulse signal and sends it to the signal control circuit. Through the signal control and acquisition transmission line, the signal control circuit instructs the annular acoustic lens transducer array to generate a specific annular acoustic lens layer.

[0060] After a preset delay, the computer sends another pulse signal to trigger the pulsed laser, which emits short-pulse laser with a wavelength of 532 nm. This laser enters a single-mode optical fiber with a diameter of 9 μm through an optical fiber coupler and is converted into a parallel beam by a connected GRIN lens. This parallel Gaussian beam then impinges on the inclined surface of the mirror, and after being reflected by the inclined surface, it passes through the outer wall of the transparent cylinder and the transparent sleeve, and uniformly irradiates biological tissues such as the intestinal wall or bronchus, covering a 360° range.

[0061] (2) Ultrasound and photoacoustic signal reception:

[0062] The annular acoustic lens transducer first captures the ultrasound signal generated by the annular acoustic lens layer. After a set delay, when the laser irradiates biological tissues such as the intestinal wall or bronchus, the photoacoustic signal excited at the position of the annular acoustic lens layer is detected by the annular acoustic lens transducer array.

[0063] The detected signal is transmitted through the signal control and acquisition transmission line to the AC / DC conversion module on the digital acquisition card for processing. After the signal conversion is completed, the data is transmitted and stored in the computer for subsequent analysis.

[0064] (3) Tomographic scanning and image reconstruction:

[0065] After completing one tomographic scan, the computer sends a pulse signal to the drive control circuit, and drives the transparent sleeve and its internal components to move forward axially through the stepper motor to prepare for the next scan.

[0066] The data acquired during the scanning process is transmitted to the computer in real time through the signal acquisition circuit. The computer processes the collected data using programming algorithms to reconstruct photoacoustic and ultrasound images.

[0067] (4) Acquisition of multiple images and three-dimensional reconstruction:

[0068] Quickly repeat the above tomographic scanning steps to continuously acquire multi-frame circumferential scan image data.

[0069] Superimpose these image data respectively to form three-dimensional images in two modalities of photoacoustic and ultrasound, providing more comprehensive organizational structure information and helping for more accurate medical diagnosis.

[0070] The method of this embodiment combines advanced optical and acoustic technologies to achieve high-resolution in-vivo tissue imaging, which is particularly suitable for the examination of narrow cavities such as the digestive tract and can provide detailed anatomical and functional information for clinical applications.

[0071] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0072] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. An optoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing, characterized in that, It includes a base, and the base includes a first cylinder and a second cylinder which are coaxially arranged. The diameter of the first cylinder is larger than that of the second cylinder. The inside of the second cylinder is a hollow structure, and a Green lens is arranged in the hollow structure. A transparent cylinder is provided at the bottom of the second cylinder, and a conical reflecting surface is provided at the top of the transparent cylinder. An annular acoustic chip transducer array is sleeved outside the second cylinder. The annular acoustic chip transducer array includes a receiving ultrasonic array and an exciting ultrasonic array. The exciting ultrasonic array is composed of a plurality of coaxial annular transducers. By means of a cross amplitude modulation sequence, two adjacent semi-aperture annular transducers simultaneously emit cross-propagating annular ultrasonic waves at a set angle. When the two annular acoustic waves meet in space, interference forms a new acoustic field. The acoustic field has an enhanced sound pressure on the annular plane, forming an annular acoustic chip layer. The receiving ultrasonic array has a plurality of strip transducers bonded to the inner side of the receiving transducer, and is used for receiving ultrasonic and photoacoustic signals generated at the position of the annular acoustic chip layer. The first cylinder is provided with a through hole for a single-mode optical fiber to pass through, and the single-mode optical fiber is connected to the Green lens after passing through the through hole of the first cylinder.

2. The photoacoustic ultrasound endoscopy tomography probe based on acoustic sheet focusing according to claim 1, wherein The outer wall of the transparent cylinder is transparent, the top is a conical reflecting surface at an angle of 60° with the central axis, and the bottom is provided with a cylindrical protrusion, and the cylindrical protrusion matches the hollow structure of the second cylinder.

3. The photoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing according to claim 1, wherein The annular acoustic chip transducer array is a row-column addressed transducer array, and a cross amplitude modulation sequence is adopted to enable the exciting ultrasonic array to focus and generate an annular acoustic chip layer.

4. The photoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing according to claim 1, wherein The single-mode optical fiber, the Green lens, and the transparent cylinder are coaxially fixed to the base in sequence.

5. The photoacoustic ultrasound endoscopy tomography probe based on acoustic lens focusing according to claim 1, characterized in that, The annular acoustic chip transducer array is fixed to the outer wall of the base by resin glue.

6. An optoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing, characterized in that, It includes the photoacoustic ultrasonic endoscopy tomography probe based on acoustic chip focusing according to any one of claims 1-5, and further includes a data acquisition card, a computer, a signal control circuit, a pulsed laser, and a drive control circuit. The data acquisition card is respectively connected to the computer and the signal control circuit. The computer is also connected to the pulsed laser and the drive control circuit. The signal control circuit is used to control two adjacent semi-aperture annular transducers to simultaneously emit cross-propagating annular ultrasonic waves at a set angle. The pulsed laser outputs a parallel beam after being connected to a collimating lens through a single-mode optical fiber. After being reflected by the conical reflecting surface, the beam passes through the outer wall of the transparent cylinder and a transparent sleeve, and hits the surrounding biological tissues to excite photoacoustic signals. The drive control circuit is used to control the movement of the photoacoustic ultrasonic endoscopy tomography probe based on acoustic chip focusing. The computer is used to store and process the collected data and complete the reconstruction of photoacoustic images and ultrasonic images.

7. The photoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing according to claim 6, characterized in that, The single-mode optical fiber is connected to the coupler of the pulsed laser through a standard fiber connector. The single-mode optical fiber and the Green lens are fixed inside the transparent sleeve through the base. The pulsed laser is connected to the Green lens through the single-mode optical fiber and then outputs a parallel beam.

8. The photoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing according to claim 6, wherein, The annular phased array transducer is led out along the inner groove of the transparent sleeve through a signal control and acquisition transmission line and is connected to a signal control circuit. The signal control circuit controls the transducer array to simultaneously emit cross-propagating annular ultrasonic waves at a set angle through two adjacent semi-aperture annular transducers via the signal control and acquisition transmission line. When the two annular acoustic waves meet in space, they interfere to form an annular acoustic sheet layer. After the signal generated by the annular phased array transducer is sent to the signal control circuit through the signal control and acquisition transmission line, it is sampled by a data acquisition card and then sent to a computer for image reconstruction.

9. The photoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing according to claim 6, wherein The drive control circuit is provided with a stepping motor. The stepping motor is connected to the drive control circuit through a control signal line, and the stepping motor is connected to the transparent sleeve through a torque wire.

10. The imaging method of the photoacoustic ultrasound endoscopy tomography system based on acoustic lens focusing according to any one of claims 6-9, characterized in that, It includes the following steps: (1) Excitation: After receiving the pulse signal generated by the computer, the signal control circuit controls the annular phased array transducer to generate an annular acoustic sheet layer. After a period of delay, the pulse signal generated by the computer excites a pulsed laser to emit pulsed laser light. The pulsed laser light is incident into a single-mode optical fiber through an optical fiber coupler, and after passing through a Grimm lens, parallel outgoing laser light is generated. The parallel laser beam is incident on a conical reflecting surface to achieve a beam reflected at a set angle passing through the outer wall of the transparent cylinder and hitting the surrounding biological tissue to excite photoacoustic signals. (2) Data acquisition: The annular phased array transducer first receives the ultrasonic signal of the annular acoustic sheet layer. After a period of delay, the photoacoustic signal generated by the biological tissue at the position of the annular acoustic sheet layer is detected again by the annular phased array transducer. The two signals are successively transmitted to the AC / DC conversion module on the digital acquisition card through the signal control and acquisition transmission line for signal conversion, and finally the photoacoustic signal is transmitted and stored in the computer. (3) Endoscopic scanning: After exciting the annular acoustic sheet layer and the laser and completing one two-dimensional ultrasonic and photoacoustic scan, the computer controls the drive control circuit to make the photoacoustic ultrasonic endoscopic tomography probe based on acoustic sheet focusing move forward or backward one step and then stop. Repeat the endoscopic scanning step to finally complete three-dimensional endoscopic scanning. (4) Image reconstruction and display: The computer stores and processes the collected data to complete the reconstruction of photoacoustic images and ultrasonic images.

Images