Compensated photoacoustic receiver and method

Abstract

The application discloses a compensation type photoacoustic receiver and method. The receiver comprises a receiver shell, a hollow transducer, a compensation module and a planar transducer; the hollow transducer is arranged in the receiver shell, the hollow transducer comprises a hollow cylinder backing layer and a ring-shaped high-frequency piezoelectric element, the hollow cylinder backing layer is coaxially arranged with the receiver shell, and the ring-shaped high-frequency piezoelectric element is attached to the bottom concave surface of the hollow cylinder backing layer; the compensation module is sleeved in the hollow transducer, the compensation module comprises a prism group and a cylindrical transparent glass, the cylindrical transparent glass is coaxially arranged in the cavity of the hollow cylinder backing layer, and the prism group is fixed to the top of the cylindrical transparent glass; and the planar transducer is arranged on the top of the compensation module. The application can compensate for the lost sound signals, the superposition of the sound signals of two sound fields can make the collected sound signals more complete, and thus the detection sensitivity of the receiver and the quality of image reconstruction are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of photoacoustic imaging, and particularly relates to a compensating photoacoustic receiver and method. BACKGROUND

[0002] Photoacoustic imaging is a biomedical imaging technique that combines principles of optics and acoustics. It uses the photoacoustic effect, which is the generation of acoustic waves by the absorption of laser pulse energy in tissues or materials, to obtain structural and functional information of biological tissues. Photoacoustic imaging has high resolution and deep tissue penetration capability, so it has potential important applications in the field of medical imaging.

[0003] A key component of photoacoustic imaging is the photoacoustic receiver, which is used to receive acoustic signals generated by the photoacoustic effect and convert these acoustic signals into electrical signals for signal processing and image reconstruction. Patent application No. CN202110085865.2 discloses an ellipsoidal surface curvature-based photoacoustic / ultrasound dual-mode high-frequency probe. This technical solution expands the depth of field through the ellipsoidal surface shape, improving the imaging resolution. The middle part of the cylindrical structure of this invention is hollow, which facilitates the transmission of incident laser and the reception of return acoustic signals. However, the main drawback is that the cavity structure lacks piezoelectric material inside, which cannot receive acoustic signals, resulting in the loss of part of the acoustic signals, thereby affecting the receiver detection sensitivity and the imaging quality of the system. Patent application No. CN201810515835.9 discloses a transparent ultrasonic transducer. This invention can seamlessly integrate optical and ultrasonic components, and has ultra-high optical transparency, allowing more light to pass through, which is beneficial to improving imaging quality. However, there are technical challenges in manufacturing transparent ultrasonic transducers with high transparency and good acoustic performance, such as the development of new materials and designs, such as transparent piezoelectric units, transparent electrodes, and transparent backing layers. The preparation process is complex and costly.

[0004] In addition, the hollow transducer commonly used in current photoacoustic imaging technology has a cavity structure that makes it easier for light signals to propagate, but also has defects such as acoustic signal loss, which seriously affects the completeness of signal collection and the quality of image reconstruction. SUMMARY

[0005] In order to at least solve one of the deficiencies of the prior art, the present application provides a compensating photoacoustic receiver, which is simple in structure and reasonable in construction. The compensation module of the photoacoustic receiver can compensate for the lost acoustic signals, and the superposition of the two acoustic field acoustic signals can make the collected acoustic signals more complete, thereby improving the receiver detection sensitivity and the quality of image reconstruction.

[0006] In order to achieve the purpose of the present application, the present application provides a compensating photoacoustic receiver, which comprises a receiver shell, a hollow transducer, a compensation module and a planar transducer.

[0007] The hollow transducer is arranged in the receiver shell, the hollow transducer comprises a hollow cylindrical backing layer and a ring-shaped high-frequency piezoelectric element, the hollow cylindrical backing layer is arranged coaxially with the receiver shell, the cylindrical transparent glass is concave at the bottom for focusing sound signals, and the ring-shaped high-frequency piezoelectric element is arranged on the bottom concave surface of the hollow cylindrical backing layer.

[0008] The compensation module is sleeved in the hollow transducer, the compensation module comprises a prism group and a cylindrical transparent glass, the cylindrical transparent glass is coaxially arranged in the cavity of the hollow cylindrical backing layer, and the prism group is fixed on the top of the cylindrical transparent glass.

[0009] The planar transducer is arranged on the top of the compensation module.

[0010] The hollow transducer is a hollow structure, which can be sleeved and fixed with the compensation module.

[0011] Preferably, the ring-shaped high-frequency piezoelectric element is attached to the concave surface at the bottom of the hollow cylindrical backing layer, and the two are coaxial.

[0012] The prism group is bonded with the transparent cylindrical glass, the transparent cylindrical glass is sleeved in the hollow cylindrical backing layer, and the planar transducer is attached to the top of the compensation module.

[0013] The hollow cylindrical backing layer is coaxially sleeved with the compensation module and the receiver shell.

[0014] Preferably, the receiver shell is made of aluminum.

[0015] Preferably, the hollow transducer is arranged inside the receiver shell, and the gap between the receiver shell and the hollow transducer is filled with a glue layer.

[0016] Preferably, the glue layer uses ultraviolet curing glue and resin waterproof glue; first, the receiver shell and the hollow cylindrical backing layer are placed in the coaxial position, and the ultraviolet curing glue is used for filling and fixing; then the resin waterproof glue is used to fill the bottom, so that the glue layer not only realizes the connection of the two, but also has the function of waterproof.

[0017] Preferably, the ring-shaped high-frequency piezoelectric element is attached to the concave surface at the bottom of the hollow cylindrical backing layer by epoxy resin, which is flat and wrinkle-free, and the two are coaxial. The bottom of the hollow cylindrical backing layer is concave, and the ring-shaped high-frequency piezoelectric element has a convex surface, which is attached to the concave surface of the hollow cylindrical backing layer.

[0018] Preferably, the hollow cylindrical backing layer is made of an epoxy resin-tungsten powder material. The preparation process includes: adding an epoxy resin curing agent to epoxy resin at a ratio of 1:0.35, pouring in 66% to 71% tungsten powder and 6% boron nitride powder, and stirring until the mixture reaches a gray liquid state. The sample is then placed in a vacuum chamber to remove bubbles and air. Finally, the sample is poured into a mold and heated in a constant temperature oven for curing. The tungsten powder has a mass fraction of approximately 66% to 71%, and has high acoustic attenuation coefficient and acoustic impedance values, with acoustic impedance values ​​ranging from 5.5 MRayls to 6.6 MRayls and acoustic attenuation coefficients ranging from 15.7 dB / cm to 16.3 dB / cm. The acoustic signal emitted by biological tissue is partially received by the high-frequency piezoelectric element, while a small portion passes through the high-frequency piezoelectric element and is then reflected by the hollow cylindrical backing layer to the high-frequency piezoelectric element. This improves the efficiency of acoustic signal reception, thereby enhancing the detection sensitivity of the receiver. It also serves to support, isolate, and protect the high-frequency piezoelectric element.

[0019] Preferably, the annular high-frequency piezoelectric element adopts a wide-band PVDF material and is formed by making the PVDF piezoelectric film into a ring shape. The annular high-frequency piezoelectric element is used to focus and receive sound signals; the PVDF piezoelectric film has a small acoustic impedance value, which is between 1.5MRayls and 3.0MRayls, and can achieve good acoustic impedance matching with water and human tissue without the need for a matching layer.

[0020] Preferably, the cylindrical transparent glass of the compensation module is fitted into the hollow transducer and bonded to the hollow cylindrical backing layer by epoxy resin; the curvature radius of the concave surface of the bottom of the cylindrical transparent glass is R=f(1-1 / n), where n is the ratio of the propagation speed of the acoustic signal in the glass and in the water, and f is the focusing focal length.

[0021] Preferably, the bottom of the prism group of the compensation module and the top of the cylindrical transparent glass are bonded together by ultrasonic glue, and the centers of the prism group and the cylindrical transparent glass are aligned.

[0022] Preferably, the prism group is used for reflecting light and transmitting sound, and includes two metal-coated prisms, and the two prisms are fixed to each other.

[0023] Further preferably, the prism group is composed of two aluminum-coated prisms bonded together by UV-curing glue. The acoustic impedance of aluminum is approximately 17.1 MRalys, and the acoustic impedance of glass is approximately 18.9 MRayls. Aluminum and glass have good acoustic impedance matching, and the attenuation of ultrasonic waves inside this material is small, which is conducive to the transmission of ultrasonic waves.

[0024] Preferably, the planar transducer is attached to the top of the cylindrical transparent glass to receive the acoustic signal focused by the cylindrical transparent glass. The planar transducer is made of piezoelectric ceramic material, which has a high electromechanical coupling coefficient, high sensitivity and high stability.

[0025] Preferably, the planar transducer and the prism assembly are bonded together by ultrasonic glue.

[0026] The present invention also provides a signal receiving method using the aforementioned photoacoustic receiver, the method comprising: placing the photoacoustic receiver on biological tissue, irradiating a laser pulse beam toward a prism group, the beam being reflected by the prism group, then passing through a transparent cylindrical glass, and irradiating the biological tissue, where the biological tissue absorbs the laser pulse energy to generate an acoustic signal;

[0027] Part of the generated acoustic signal is focused and received by the annular high-frequency piezoelectric element, forming the first part of the focused acoustic field; the other part of the acoustic signal is focused by the compensation module, passes through the prism group, and is then received by the planar transducer, forming the second part of the focused acoustic field;

[0028] The first part of the focused sound field is converted into an electrical signal output by the annular high-frequency piezoelectric element, and the second part of the focused sound field is converted into an electrical signal output by the planar transducer.

[0029] Compared with the prior art, the present invention has at least the following advantages and effects:

[0030] (1) Only part of the acoustic signal is received by a single hollow transducer, and the rest of the acoustic signal is lost from the middle cavity; the present invention adds a compensation module in the cavity of the hollow transducer, which can focus the lost acoustic signal to the planar transducer, thereby realizing compensated reception of the acoustic signal.

[0031] (2) In the present invention, a part of the generated acoustic signal is received by the annular high-frequency piezoelectric element of the receiver, forming a first part of the focused acoustic field; the other part passes through the compensation module and is received by the planar transducer, forming a second part of the focused acoustic field; the acoustic signals of the two different sound fields work together to help compensate for the lost acoustic signal, making the acquired acoustic signal information more complete, thereby improving the detection sensitivity of the receiver and the quality of image reconstruction.

[0032] (3) The present invention provides a photoacoustic signal compensation receiver with a simple structure that can be well matched with a photoacoustic imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the structure of a compensated photoacoustic receiver provided by an embodiment of the present invention;

[0034] Figure 2 A schematic cross-sectional view of a compensated photoacoustic receiver provided by an embodiment of the present invention;

[0035] Figure 3 An explosion structure diagram of a compensation type photoacoustic receiver is provided for the embodiment of the present application;

[0036] The figure serial number is explained: 1 is a plane transducer; 2 is a prism group; 3 is a cylindrical transparent glass; 4 is a receiver shell; 5 is a hollow cylindrical backing layer; 6 is a ring-shaped high-frequency piezoelectric element; wherein the prism group 2 and the cylindrical transparent glass 3 form a compensation module; wherein the hollow cylindrical backing layer 5 and the ring-shaped high-frequency piezoelectric element 6 form a hollow transducer. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiment of the present application more clear, the technical scheme in the embodiment of the present application will be described clearly and completely below in combination with the drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0038] As shown in the figure, Figure 1 The present application provides a photoacoustic signal compensation receiver, which comprises a receiver shell 4, a hollow transducer, a compensation module and a plane transducer 1. The compensation module comprises a prism group 2 and a cylindrical transparent glass 3. The transparent glass has good light transmission, which is convenient for focusing and transmitting light signals, and the glass material has good mechanical stability and chemical stability. The hollow transducer comprises a hollow cylindrical backing layer 5 and a ring-shaped high-frequency piezoelectric element 6. The compensation module is sleeved in the hollow transducer.

[0039] The plane transducer 1 is adhered to the prism group 2 by ultrasonic glue. The cylindrical transparent glass 3 is inserted into the cavity of the hollow cylindrical backing layer 5, and the cylindrical transparent glass 3 and the hollow cylindrical backing layer 5 are adhered together by epoxy resin, and the bottoms of the two are aligned. The prism group 2 and the transparent cylindrical glass 3 are adhered together by ultrasonic glue. The prism group 2 is located at the top of the transparent cylindrical glass 3, and the centers of the two are aligned. The bottom of the hollow cylindrical backing layer 5 is provided as a concave surface. The ring-shaped high-frequency piezoelectric element 6 is adhered to the bottom concave surface of the hollow cylindrical backing layer 5 by epoxy resin, and the two have coaxial centers. The receiver shell 4 and the hollow cylindrical backing layer 5 are filled and fixed by a glue layer.

[0040] The prism assembly 2 includes two metal-coated prisms bonded together with UV-curable adhesive. In some embodiments of the present invention, the prism assembly 2 includes two aluminum-coated prisms, each of which is an isosceles right triangle (one angle is 90 degrees and the other two angles are 45 degrees). The inclined surfaces of the two prisms are bonded together to form a cube.

[0041] In some embodiments of the present invention, the receiver housing 4 is made of aluminum, which can effectively reduce the surrounding electromagnetic influence.

[0042] In some embodiments of the present invention, the glue layer filled between the receiver housing 4 and the hollow cylindrical backing layer 5 includes ultraviolet light curing glue and resin waterproof glue, wherein the receiver housing 4 and the hollow cylindrical backing layer 5 are first placed in a coaxial position and filled and fixed with ultraviolet light curing glue; then the bottom is filled with resin waterproof glue. The glue layer not only can achieve the connection between the two, but also has a waterproof effect.

[0043] In some embodiments of the present invention, the curvature radius of the concave bottom surface of the cylindrical transparent glass 3 is R=f(1-1 / n), where n is the ratio of the propagation speed of the acoustic signal in the glass and in the water, and f is the focal length.

[0044] In some embodiments of the present invention, the hollow cylindrical backing layer 5 is made of an epoxy resin-tungsten powder material. Further preferably, the steps of preparing the hollow cylindrical backing layer 5 include: adding an epoxy resin curing agent to an epoxy resin according to a predetermined ratio, adding 66% to 71% tungsten powder and 6% boron nitride powder, stirring and mixing until a gray liquid is obtained, then placing the sample in a vacuum chamber to remove bubbles and air, and finally pouring the sample into a mold and heating and curing it in a constant temperature oven.

[0045] In some embodiments of the present invention, the annular high-frequency piezoelectric element 6 is made of a broadband PVDF material and is formed by shaping a PVDF piezoelectric film into an annular shape. In one specific example, the annular high-frequency piezoelectric element 6 has an inner diameter of 4 mm, an outer diameter of 8 mm, and a center frequency of 50 MHz.

[0046] A signal receiving method comprises placing the compensated photoacoustic receiver of the present invention on top of biological tissue, and emitting a series of laser pulses from a laser light source to irradiate the prism group 2. The light beam is reflected by the prism group 2, then passes through the transparent cylindrical glass 3 and irradiates the biological tissue. The biological tissue absorbs the laser pulse energy and generates an acoustic signal.

[0047] Part of the generated acoustic signal is received by the ring-shaped high-frequency piezoelectric element 6 of the receiver, forming a first part of the focused acoustic field; another part of the acoustic signal is focused by the compensation module (transparent cylindrical glass 3), passes through the prism group 2, and is then received by the planar transducer 1, forming a second part of the focused acoustic field; the first part of the focused acoustic field is converted into an electrical signal output by the ring-shaped high-frequency piezoelectric element 6, and the second part of the focused acoustic field is converted into an electrical signal output by the planar transducer 1.

[0048] For the hollow transducer, the acoustic signal is only received by the ring-shaped high-frequency piezoelectric element 6 of the hollow transducer, and the remaining acoustic signal is lost from the middle cavity of the hollow cylindrical backing layer 5; the compensation module is added to the middle cavity of the hollow transducer, and the lost acoustic signal in the acoustic field can be received by the planar transducer 1 to compensate for the lost acoustic signal.

[0049] The acoustic signals of the two different acoustic fields act together to compensate for the lost acoustic signal, so that the obtained acoustic signal information is more complete, thereby obtaining a more accurate and information-rich image, and improving the receiver detection sensitivity and image reconstruction quality.

[0050] The present application aims to solve the problem of acoustic signal loss caused by the hollow structure in the photoacoustic imaging technology based on the hollow transducer. The cavity structure of the existing hollow transducer allows light signals to pass through easily, but due to the lack of piezoelectric material in the cavity, it cannot receive the acoustic wave signals in the cavity, which leads to the loss of acoustic wave signals in the cavity. The compensation type photoacoustic receiver provided in the foregoing embodiments of the present application can realize the light transmission function through the hollow structure of the hollow transducer, and the compensation module can collect the lost acoustic signals through the light-reflecting and sound-transmitting prism group and the light-transmitting and sound-transmitting cylindrical glass, and finally received by the planar transducer. The combination of the hollow transducer and the compensation module can compensate for the lost acoustic signals, realize complete acoustic signal reception, improve the integrity of the acoustic signal, and thus improve the receiver detection sensitivity and image reconstruction quality.

[0051] Although the embodiments of the present application are as described above, the content described is only for the purpose of facilitating understanding of the embodiments of the present application, and is not intended to limit the present application. Any person skilled in the art of the present application can make any modification and change in the form and details without departing from the spirit and scope of the present application, but the patent protection scope of the present application shall be subject to the scope defined by the appended claims.

Claims

1. A compensated photoacoustic receiver, characterized in that: including a receiver housing, a hollow transducer, a compensation module, and a planar transducer; The hollow transducer is arranged in the receiver housing. The hollow transducer includes a hollow cylindrical backing layer and an annular high-frequency piezoelectric element. The hollow cylindrical backing layer is coaxially arranged with the receiver housing, and the annular high-frequency piezoelectric element is fitted on the bottom concave surface of the hollow cylindrical backing layer. The compensation module is mounted in the hollow transducer and includes a prism group and a cylindrical transparent glass. The cylindrical transparent glass is coaxially located in the cavity of the hollow cylindrical backing layer, and the prism group is fixed on the top of the cylindrical transparent glass. The planar transducer is arranged on the top of the compensation module; The prism assembly is used for reflecting light and transmitting sound, and includes two metal-coated prisms, which are fixed to each other; The hollow cylindrical backing layer is made of epoxy resin-tungsten powder material; The prism group is aligned with the center of the cylindrical transparent glass. The curvature radius of the concave bottom surface of the cylindrical transparent glass is: , where n is the ratio of the propagation speed of the acoustic signal in glass and water, is the focus focal length.

2. A compensated photoacoustic receiver according to claim 1, characterized in that: The annular high-frequency piezoelectric element is made of PVDF material.

3. The compensated photoacoustic receiver according to claim 1, characterized in that: The receiver housing is made of aluminum.

4. The compensated photoacoustic receiver according to claim 1, characterized in that: A glue layer is used to fill the space between the receiver shell and the hollow cylindrical backing layer.

5. The compensated photoacoustic receiver according to claim 4, characterized in that: The glue layer includes ultraviolet light curing glue and resin waterproof glue. The receiver shell and the hollow cylindrical backing layer are filled and fixed by ultraviolet light curing glue, and the bottom is filled by the resin waterproof glue.

6. A signal receiving method, characterized in that: The photoacoustic receiver according to any one of claims 1 to 4 is used, and the method comprises: placing the photoacoustic receiver on biological tissue, irradiating a laser pulse beam toward a prism assembly, the laser beam being reflected by the prism assembly, then passing through a transparent cylindrical glass, and irradiating the biological tissue, whereby the biological tissue absorbs the laser pulse energy and generates an acoustic signal; Part of the generated acoustic signal is focused and received by the annular high-frequency piezoelectric element, forming the first part of the focused acoustic field; the other part of the acoustic signal is focused by the compensation module, passes through the prism group, and is then received by the planar transducer, forming the second part of the focused acoustic field; The first part of the focused sound field is converted into an electrical signal output by the annular high-frequency piezoelectric element, and the second part of the focused sound field is converted into an electrical signal output by the planar transducer.

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