CN118806238A - A handheld photoacoustic imaging probe and a photoacoustic imaging system - Google Patents

Abstract

The present invention discloses a handheld photoacoustic imaging probe and a photoacoustic imaging system, which belong to the field of photoacoustic imaging technology and can solve the problems of the existing photoacoustic imaging system being relatively bulky, inconvenient to operate, and having a relatively complex screening process and high cost. The photoacoustic imaging probe comprises: a shell having an opening at one end; a first laser module arranged in the shell for emitting a first wavelength laser beam to the tissue to be tested through the opening; a second laser module arranged in the shell for emitting a second wavelength laser beam to the tissue to be tested through the opening; the wavelength of the second wavelength laser beam is greater than the wavelength of the first wavelength laser beam; an ultrasonic receiving module arranged in the shell and located between the first laser module and the second laser module for receiving an ultrasonic signal generated by the tissue to be tested through the opening and converting the ultrasonic signal into an electrical signal. The present invention is used for disease screening of human tissues.

Description

A handheld photoacoustic imaging probe and a photoacoustic imaging system

Technical Field

The invention relates to a handheld photoacoustic imaging probe and a photoacoustic imaging system, belonging to the technical field of photoacoustic imaging.

Background Art

Breast cancer is a malignant tumor that occurs in breast tissue and is one of the most common cancers in women worldwide. The incidence of breast cancer is on the rise worldwide, especially in my country. Due to changes in lifestyle and an aging population, the incidence and mortality of breast cancer are increasing year by year. In order to reduce the incidence and mortality of breast cancer and improve the quality of women's health, breast cancer screening is necessary.

Traditional breast cancer screening usually uses mammography and breast ultrasound as the main means. Mammography has problems with penetrating dense breast tissue and radiation risks in the early diagnosis of breast cancer, which will affect the accuracy of screening. Breast ultrasound is prone to miss small lesions, its spatial resolution and specificity are limited, and due to its high dependence on operator skills, the consistency of diagnostic results is difficult to ensure. These have limited the application of traditional screening strategies in the early detection of breast cancer and in high-risk groups.

In recent years, the clinical application of photoacoustic imaging technology in breast cancer has confirmed the potential of photoacoustic imaging systems in early screening, disease diagnosis, biopsy guidance, and treatment monitoring of breast cancer. As one of the methods to achieve photoacoustic imaging technology, photoacoustic tomography is widely used in current biomedical imaging, including tumor detection, vascular imaging, and neural activity monitoring. Photoacoustic tomography technology has great advantages in breast cancer monitoring. It can be used for early detection of breast cancer. Breast cancer cells usually absorb more light and therefore produce stronger photoacoustic signals.

However, existing photoacoustic tomography technology still has some limitations in breast cancer screening. For example, traditional photoacoustic imaging systems are usually bulky and not easy to move and position quickly in clinical settings. In addition, most systems require professional operators to perform complex equipment adjustments and data interpretation, which increases the complexity and cost of the screening process.

Summary of the invention

The present invention provides a handheld photoacoustic imaging probe and a photoacoustic imaging system, which can solve the problems of the existing photoacoustic imaging system being relatively bulky, inconvenient to operate, and having a relatively complex screening process and high cost.

In one aspect, the present invention provides a handheld photoacoustic imaging probe, the photoacoustic imaging probe comprising:

A housing having an opening at one end;

A first laser module, disposed in the housing, for emitting a laser beam of a first wavelength toward the tissue to be measured through the opening;

A second laser module is disposed in the housing and is used to emit a second wavelength laser beam to the tissue to be measured through the opening; the wavelength of the second wavelength laser beam is greater than the wavelength of the first wavelength laser beam;

The ultrasonic receiving module is arranged in the shell and located between the first laser module and the second laser module, and is used for receiving the ultrasonic signal generated by the tissue to be tested through the opening and converting the ultrasonic signal into an electrical signal.

Optionally, the first laser module and the second laser module emit laser beams alternately to the tissue to be tested;

The delay between the first laser module and the second laser module emitting laser beams is less than 10 ms.

Optionally, the wavelength of the first wavelength laser beam is 755±20 nm; the wavelength of the second wavelength laser beam is 1064±20 nm.

Optionally, the first laser module and the second laser module both include:

An optical fiber bundle, which is composed of a plurality of single-mode optical fibers bundled together and used to transmit the laser beam;

The optical diffuser is arranged at the light-emitting end of the optical fiber bundle and is used to diffuse the laser beam emitted by the optical fiber bundle so that the diffused laser beam irradiates the tissue to be measured.

Optionally, the ultrasound receiving module includes:

An acoustic lens, disposed on the opening, for focusing the ultrasonic signal generated by the tissue to be tested;

A matching layer, arranged on the exit side of the acoustic lens;

The piezoelectric array is arranged on a side of the matching layer away from the acoustic lens, and is used to receive the focused ultrasonic signal and convert the ultrasonic signal into an electrical signal; the matching layer is used to match the acoustic impedance between the tissue to be tested and the piezoelectric array.

Optionally, the acoustic impedance of the matching layer is 4-4.5 MRayls; and the thickness of the matching layer is 30-50 μm.

Optionally, the piezoelectric array includes a chip, and electrodes located on opposite sides of the chip;

The thickness of the wafer is 130-220 μm.

Optionally, the chip is formed by a plurality of piezoelectric array elements arranged in a horizontal direction, the piezoelectric array elements are in the shape of long beams, and the interval between two adjacent piezoelectric array elements is 60±10 μm.

Optionally, the photoacoustic imaging probe further includes:

An insulating layer is arranged on the inner wall of the shell; the first laser module, the second laser module and the ultrasonic receiving module are all arranged on the inner side of the insulating layer.

In another aspect, the present invention provides a photoacoustic imaging system, the system comprising:

A photoacoustic imaging probe as described in any one of the above;

A first laser, used to provide a laser beam of a first wavelength to the first laser module;

A second laser, used to provide a laser beam of a second wavelength to the second laser module;

The processor is connected to the ultrasonic receiving module through an electrical lead and is used to perform imaging processing on the electrical signal converted by the ultrasonic receiving module to obtain the detection result of the tissue to be detected.

The beneficial effects that the present invention can produce include:

The handheld photoacoustic imaging probe and photoacoustic imaging system provided by the present invention, by setting a dual-wavelength laser module as an ultrasonic excitation signal source, and integrating an ultrasonic receiving module, realizes the saturation analysis of oxygenated hemoglobin and deoxygenated hemoglobin in the blood, thereby improving the screening accuracy. The present invention has a simple structure and is easy to operate, solving the problems of the existing photoacoustic imaging system being relatively bulky, inconvenient to operate, and the screening process being relatively complicated and costly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a handheld photoacoustic imaging probe provided in an embodiment of the present invention.

Reference numerals:

1. Electrical lead; 2. Insulation layer; 3. Shell; 4. Electrode; 5. Diffused laser beam; 6. Tissue to be measured; 7. Tumor; 8. Fiber optic bundle; 9. Laser beam; 10. Backing material; 11. Piezoelectric array; 12. Optical diffuser; 13. Acoustic lens; 14. Ultrasonic signal; 15. Matching layer.

DETAILED DESCRIPTION

The present invention is described in detail below with reference to embodiments, but the present invention is not limited to these embodiments.

An embodiment of the present invention provides a handheld photoacoustic imaging probe, as shown in FIG1 , the photoacoustic imaging probe comprises:

The housing 3 has an opening at one end.

In practical applications, the housing 3 can be configured as a cylindrical housing.

Furthermore, a layer of insulating material is coated on the inner wall of the shell 3 as the insulating layer 2 .

The first laser module is disposed in the housing 3 and is used for emitting a laser beam of a first wavelength to the tissue to be measured 6 through the opening.

The second laser module is disposed in the housing 3 and is used to emit a second wavelength laser beam to the tissue to be measured 6 through the opening; the wavelength of the second wavelength laser beam is greater than the wavelength of the first wavelength laser beam.

The first laser module and the second laser module emit laser beams 9 to the tissue to be measured 6 alternately; and the delay between the first laser module and the second laser module in emitting the laser beams 9 is less than 10 ms.

In practical applications, the wavelength of the first wavelength laser beam can be 755±20nm; the wavelength of the second wavelength laser beam can be 1064±20nm. Considering the different sensitivities of lasers of different wavelengths to oxygenated hemoglobin and deoxygenated hemoglobin, preferably, the wavelength of the first wavelength laser beam is 755nm; the wavelength of the second wavelength laser beam is 1064nm; the laser pulse width of the first wavelength laser beam is 15~20ns, and the pulse energy is 140~160mJ; the laser pulse width of the second wavelength laser beam is 40~60ns, and the pulse energy is 130~140mJ.

In an embodiment of the present invention, the first laser module and the second laser module both include:

The optical fiber bundle 8 is composed of a plurality of single-mode optical fibers bundled together and is used to transmit the laser beam 9 .

The optical diffuser 12 is disposed at the light-emitting end of the optical fiber bundle 8 and is used to diffuse the laser beam 9 emitted from the optical fiber bundle 8 so that the diffused laser beam 5 irradiates the tissue 6 to be measured.

The diameter of the optical fiber bundle 8 can be set to 8-9 mm, and it is composed of a single-mode optical fiber with a diameter of 200-300 μm. The laser beam 9 transmitted in the optical fiber bundle 8 is evenly diffused by the optical diffuser 12 .

The optical diffuser 12 adopts a YAG laser high-performance beam expander with a beam expansion ratio of 3 to 5 times, a comprehensive transmittance of more than 95%, a light spot stability of less than 1 mrad, and is suitable for laser beams with wavelengths of 755nm and 1064nm.

The ultrasonic receiving module is arranged in the housing 3 and located between the first laser module and the second laser module, and is used for receiving the ultrasonic signal 14 generated by the tissue to be tested 6 through the opening and converting the ultrasonic signal 14 into an electrical signal.

Specifically, the ultrasonic receiving module includes:

The acoustic lens 13 is disposed on the opening and is used to focus the ultrasonic signal 14 generated by the tissue 6 to be tested.

The matching layer 15 is provided on the emission side of the acoustic lens 13 .

The piezoelectric array 11 is arranged on the side of the matching layer 15 away from the acoustic lens 13, and is used to receive the focused ultrasonic signal 14 and convert the ultrasonic signal 14 into an electrical signal; the matching layer 15 is used to match the acoustic impedance between the tissue to be tested 6 and the piezoelectric array 11.

The piezoelectric array 11 may include a chip and electrodes 4 located on two opposite sides of the chip; the thickness of the chip may be 130-220 μm.

In the embodiment of the present invention, the chip is formed by a plurality of piezoelectric array elements arranged in a horizontal direction, the piezoelectric array elements are in the shape of long beams, and the interval between two adjacent piezoelectric array elements is 60±10 μm.

In practical applications, the size of the piezoelectric array element may be 1.5 mm×130 μm×150 μm, the interval between two adjacent piezoelectric array elements may be 60 μm, and the operating frequency may be 15-25 MHz; specifically, the piezoelectric array element may be a piezoelectric single crystal lithium niobate.

The acoustic impedance of piezoelectric single crystal lithium niobate is 34 MRayls, and the acoustic impedance of the human tissue to be measured is 1.5 MRayls. Therefore, preferably, the acoustic impedance of the matching layer 15 is set to 4-4.5 MRayls; the thickness of the matching layer 15 is set to 30-50 μm, which can obtain a better acoustic impedance matching effect.

The acoustic lens 13 may be a silicon acoustic lens.

The above-mentioned tissue to be tested can be human tissue, such as breast, uterus, kidney and other tissues; taking breast tissue as an example, when the 755nm and 1064nm laser beams alternately irradiate the breast tissue, the hemoglobin in the blood vessels formed by the tumor 7 in the breast tissue will generate an ultrasonic signal 14, and the ultrasonic signal 14 is received by the ultrasonic receiving module and converted into an electrical signal for subsequent analysis and disease screening.

After the tumor enters the vascular stage, the tumor cells obtain nutrients through the perfusion of the newly generated blood vessels, causing the tumor to grow and proliferate rapidly until it invades and metastasizes. The hemoglobin saturation of the tumor-associated blood vessels is lower than the normal value, and its vascular structure is abnormal. Therefore, by imaging the blood vessels with the probe of the present invention and analyzing the saturation of the two hemoglobins, the tumor can be accurately identified.

The present invention provides a handheld photoacoustic imaging probe composed of multiple micro-functional modules. The probe has a compact design, is easy to operate, has no electromagnetic radiation, can quickly scan human tissues such as breasts, and generate high-resolution photoacoustic images in real time. By detecting the saturation of oxygenated hemoglobin and deoxygenated hemoglobin in the blood, combined with the tissue photoacoustic imaging image of the probe, a preliminary diagnosis of breast cancer can be made quickly and accurately, greatly improving the feasibility and acceptability of screening.

Another embodiment of the present invention provides a method for manufacturing a photoacoustic imaging probe, the specific steps of which are as follows:

Step 1: Use lithium niobate single crystal as piezoelectric array element, pre-process the lithium niobate wafer, use ultrasonic cleaner to clean it for 5-10 minutes, then put it into drying oven at 40-60℃ for 5-10 minutes, then use plasma cleaner to clean it for 15-30 minutes, clean its surface and polish it with aluminum oxide powder, and use magnetron sputtering to plate chrome-gold lower electrode on the wafer.

Specifically, a lithium niobate single crystal cut at 36°Y was used as the piezoelectric array element, the lithium niobate wafer was pre-processed, adhered to a clean glass sheet with paraffin, wiped with trichloroethylene liquid and anhydrous ethanol and dried, then cleaned with an ultrasonic cleaner for 5 minutes, placed in a drying oven at 40°C for 10 minutes, and finally cleaned in a plasma cleaner for 15 minutes. After cleaning the surface, it was polished with aluminum oxide powder with a particle size of 1 μm, and a chrome-gold lower electrode was plated on the wafer using a magnetron sputtering device.

Step 2: Place the wafer plated with the lower electrode in a special mold and inject the matching layer material. After the matching layer material is solidified, take out the wafer and use a grinder to thin the wafer to 130~220μm, and then thin the matching layer 15 to 30~50μm.

Specifically, a wafer with a glass sheet and a plated lower electrode is placed in a special mold to inject the matching layer material. The matching layer material is composed of silver powder particles and epoxy resin in a mass ratio of 1:4. After the matching layer material is cured, the wafer is taken out of the mold, and the matching layer 15 is first ground flat using a grinder, and then the wafer is removed from the glass sheet. The same steps are used to adhere the wafer to another clean glass sheet (the matching layer 15 is close to the glass sheet), and the wafer is thinned to 130μm using a grinder. After cleaning the ground surface of the wafer, it is surface polished using aluminum oxide powder with a particle size of 1μm. Similarly, the matching layer 15 is thinned to 30μm.

Step 3: Use the same process as step 1 to plate the upper electrode of the wafer with chrome-gold, and use a cutting machine to cut the lithium niobate wafer into long beam-shaped blocks of the same size.

The size of the long beam-shaped block is 1.5 mm×130 μm×150 μm.

Step 4: Apply epoxy resin evenly on the piezoelectric array element, place it accurately on the flexible circuit board, fix it with a clamp so that the piezoelectric array element is in close contact with the flexible circuit board, and let it stand at room temperature until the epoxy resin solidifies, finally achieving electrical connection between the chip and the outside world.

The epoxy resin for coating can be prepared by mixing the AB components in a mass ratio of 8:100, stirring evenly, and then extracting the bubbles therein using a vacuum pump.

Step 5: fix the piezoelectric array 11 obtained in step 4 inside the housing 3, and connect the upper and lower electrodes of the piezoelectric array 11 to an electrical lead 1 respectively to access an external electrical signal processor.

Step 6: Prepare a silicon acoustic lens and fix it at the lower end of the matching layer 15. The focal length of the lens should be 5-10 cm.

Specifically, the focal length of the silicon acoustic lens can be selected to be 8 cm.

Step 7: Use a single-mode optical fiber with a diameter of 200-300 μm and available for 755 nm to make a first optical fiber bundle with a diameter of 8-9 mm, and use a single-mode optical fiber with a diameter of 200-300 μm and available for 1064 nm to make a second optical fiber bundle with a diameter of 8-9 mm.

Specifically, a first optical fiber bundle with a diameter of 8 mm can be made using a single-mode optical fiber with a diameter of 200 μm and available for 755 nm, and a second optical fiber bundle with a diameter of 8 mm can be made using a single-mode optical fiber with a diameter of 200 μm and available for 1064 nm.

Step 8: fix the first optical fiber bundle and the second optical fiber bundle inside the probe, and set an optical diffuser 12 at the end thereof so that the laser beam 9 transmitted therein is evenly diffused and then irradiates the tissue to be measured 6.

Step 9: remove the matching layer material on the designed laser transmission path, and apply a layer of light absorbing material on the surface to prevent the matching layer material from affecting the transmission of the laser beam 9. The light absorbing material may be nano silicon oxide or nano aluminum oxide coating.

Step 10: Encapsulate the probe obtained through the above steps, and fill the probe with a backing material 10 composed of tungsten powder and epoxy resin. After drying in a drying oven at 40-60° C. for 24-48 hours, connect the electrical and optical interfaces, and seal the rear end of the probe.

Specifically, the probe prepared by the above steps is packaged, and the backing material 10 formed by mixing tungsten powder and epoxy resin in a mass ratio of 1:4 is filled into the probe. After drying in a drying oven at 60° C. for 48 hours, the electrical and optical interfaces are connected, and the rear end of the probe is sealed to obtain a miniature handheld photoacoustic imaging probe with a working center frequency of about 20 MHz, a focal length of 8 mm, and a longitudinal resolution of 50 μm.

The handheld photoacoustic imaging probe of the present invention adopts dual-wavelength laser ultrasonic imaging and integrates optical fiber with an ultrasonic receiving module, thereby solving the problems of low sensitivity, complex structure, poor portability and low screening efficiency of existing photoacoustic imaging devices. The photoacoustic imaging probe of the present invention has the functional photoacoustic imaging capability of oxygenated and deoxygenated hemoglobin.

The handheld photoacoustic imaging probe of the present invention uses a standardized single-mode optical fiber as a basis for preparing a laser module, has a simple structure and is conducive to the industrialized production of the handheld photoacoustic imaging probe.

The handheld photoacoustic imaging probe of the present invention adopts lasers with wavelengths of 755nm and 1064nm as ultrasonic excitation signal sources, so as to realize saturation analysis of oxygenated and deoxygenated hemoglobin in blood, thereby improving diagnostic accuracy.

The handheld photoacoustic imaging probe of the present invention can effectively realize photoacoustic imaging of breast tissue 5 to 10 cm deep under the skin by reasonably designing the distribution structure of the optical diffuser 12 and the acoustic lens 13.

Another embodiment of the present invention provides a photoacoustic imaging system, the system comprising:

A photoacoustic imaging probe as described in any one of the above.

The first laser is used to provide a laser beam with a first wavelength to the first laser module.

The second laser is used to provide a laser beam with a second wavelength to the second laser module.

The processor is connected to the ultrasonic receiving module via an electrical lead 1 and is used to perform imaging processing on the electrical signal converted by the ultrasonic receiving module to obtain the detection result of the tissue to be tested 6 .

The first laser mentioned above may be an Alexandrite laser, which operates at a "short" near-infrared wavelength of 755 nm, emits 50 ns long pulses, and has a pulse energy of 140 mJ.

The second laser may be a Nd:YAG laser, which operates at a "long" near-infrared wavelength of 1064 nm, emitting pulses of 15 ns in length with a pulse energy of 150 mJ.

The present invention adopts a dual-wavelength laser module to not only realize functional photoacoustic imaging of oxygenated hemoglobin and deoxygenated hemoglobin, but also synchronizes the laser pulses of the two wavelengths in time, so that the delay between the two wavelengths is reduced to about 5 ms, thereby minimizing the influence of tissue movement.

The handheld photoacoustic imaging probe and the photoacoustic imaging system provided by the present invention use two lasers of different wavelengths to perform blood function imaging inside human tissues by tomographic imaging, and evaluate the saturation of oxyhemoglobin and deoxyhemoglobin in tissue blood. The handheld photoacoustic imaging probe of the present invention has the advantages of high resolution, good penetration, no need for external contrast agents, and no ionizing radiation. It can provide functional information about vascular structure and blood oxygen saturation, and obtain morphological and anatomical information at the same time, which is particularly beneficial for the rapid screening of diseases such as breast cancer.

The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims (10)

1. A hand-held photoacoustic imaging probe, the photoacoustic imaging probe comprising:

a housing having an opening at one end;

the first laser module is arranged in the shell and is used for emitting a first wavelength laser beam to the tissue to be detected through the opening;

the second laser module is arranged in the shell and is used for emitting a second wavelength laser beam to the tissue to be detected through the opening; the wavelength of the second wavelength laser beam is greater than the wavelength of the first wavelength laser beam;

the ultrasonic receiving module is arranged in the shell and between the first laser module and the second laser module, and is used for receiving ultrasonic signals generated by the tissue to be detected through the opening and converting the ultrasonic signals into electric signals.

2. The photoacoustic imaging probe of claim 1, wherein the first laser module and the second laser module alternately emit laser beams to the tissue under test;

the delay of the first laser module and the second laser module emitting laser beams is less than 10ms.

3. The photoacoustic imaging probe of claim 2 wherein the wavelength of the first wavelength laser beam is 755±20nm; the wavelength of the second wavelength laser beam is 1064+/-20 nm.

4. The photoacoustic imaging probe of claim 1, wherein the first laser module and the second laser module each comprise:

the optical fiber bundle consists of a plurality of single-mode optical fibers and is used for transmitting laser beams;

The optical diffusion sheet is arranged at the light emitting end of the optical fiber bundle and used for diffusing the laser beam emitted by the optical fiber bundle so that the diffused laser beam irradiates the tissue to be detected.

5. The photoacoustic imaging probe of claim 1, wherein the ultrasound receiving module comprises:

the acoustic lens is covered at the opening and is used for focusing ultrasonic signals generated by the tissue to be tested;

a matching layer disposed on an exit side of the acoustic lens;

the piezoelectric array is arranged on one side of the matching layer, which is far away from the acoustic lens, and is used for receiving the focused ultrasonic signals and converting the ultrasonic signals into electric signals; the matching layer is used for matching acoustic impedance between the tissue to be detected and the piezoelectric array.

6. The photoacoustic imaging probe of claim 5, wherein the acoustic impedance of the matching layer is 4-4.5 MRayls; the thickness of the matching layer is 30-50 mu m.

7. The photoacoustic imaging probe of claim 5 wherein the piezoelectric array comprises a wafer and electrodes on opposite sides of the wafer;

The thickness of the wafer is 130-220 mu m.

8. The photoacoustic imaging probe of claim 7 wherein the wafer is formed by arranging a plurality of piezoelectric array elements in a horizontal direction, the piezoelectric array elements being in a long beam shape, and a space between two adjacent piezoelectric array elements being 60±10 μm.

9. The photoacoustic imaging probe according to claim 1, the photoacoustic imaging probe is characterized by further comprising:

an insulating layer arranged on the inner wall of the shell; the first laser module, the second laser module and the ultrasonic receiving module are all arranged on the inner side of the insulating layer.

10. A photoacoustic imaging system, the system comprising:

a photoacoustic imaging probe according to any one of claims 1 to 9;

A first laser for providing a first wavelength laser beam to the first laser module;

A second laser for providing a second wavelength laser beam to the second laser module;

and the processor is connected with the ultrasonic receiving module through an electric lead and is used for carrying out imaging processing on the electric signals converted by the ultrasonic receiving module to obtain a detection result of the tissue to be detected.