Vein blood oxygen saturation real-time measurement system and method based on LED light source

Abstract

The invention discloses a vein blood oxygen saturation real-time measurement system and method based on an LED light source. The method comprises the steps that 1, a pulse driving circuit outputs pulse voltage to drive LEDs with different wavelengths in a dual-wavelength LED light source to flicker alternately; collecting a photoacoustic signal by an ultrasonic transducer; 2, the ultrasonic signal processing platform receives the collected sound signals and carries out subsequent processing; 3, controlling the ultrasonic transducer to transmit an ultrasonic signal to the same measured part, and receiving an echo signal of the ultrasonic transducer; reconstructing an ultrasonic image of the measured part based on the echo signal; step 4, in the obtained ultrasonic image, positioning a vein to be analyzed and an adjacent artery thereof, and positioning the vein in the ultrasonic image; 5, the arterial oxygen saturation value of the whole body is measured through a finger clamping type pulse oximeter, and quantitative calculation of the venous oxygen saturation is achieved; and step 6, carrying out pixel-level fusion on the oxyhemoglobin saturation information and the ultrasonic image, and realizing visualization on the same frame of ultrasonic image.

Description

Technical Field

[0001] This invention relates to a method for measuring blood oxygen saturation, specifically to a real-time venous blood oxygen saturation measurement system and method based on an LED light source. Background Technology

[0002] Traditional pulse oximetry (POP) measurement utilizes photoplethysmography (PPG), which takes advantage of the difference in absorption between oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) as red and infrared light penetrate tissue. A photoelectric sensor receives the transmitted light and calculates the oxygen saturation (SO2). Based on this principle, pulse oximeters have become standard monitoring devices in clinical medical care and home health management due to their non-invasiveness and convenience. However, the absorption and scattering effects of light by biological tissues severely limit the penetration depth of light in human tissues; currently, the maximum effective measurement depth of clinically used pulse oximeters is approximately 3-5 mm. Therefore, imaging methods based on light transmission or reflection are difficult to detect oxygen saturation in some critical areas, such as intracranial vessels and neck vessels. Furthermore, POP only uses the AC component of the absorbed light signal to calculate oxygen saturation, and this AC signal is generated by violently pulsating arteries, making it difficult to obtain venous oxygen saturation information in the measured area. Venous oxygen saturation directly reflects the balance between tissue oxygen supply and demand, providing a key indicator for assessing tissue perfusion and metabolism in critically ill patients. It also provides timely warnings of symptoms such as shock and heart failure, making it an important indicator of concern in intensive care.

[0003] In recent years, photoacoustic oxygen saturation measurement technology has attracted widespread attention. Photoacoustic imaging combines the advantages of high contrast in optical imaging and high resolution in ultrasound imaging. The core principle of this technology is: irradiating biological tissue with a pulsed laser of a specific wavelength, hemoglobin molecules selectively absorb the light energy and undergo instantaneous thermal expansion, thereby exciting broadband ultrasound waves. Ultrasound waves have a much stronger penetrating power in human tissue than light signals. By detecting the ultrasound signals generated within the tissue and combining them with multi-wavelength processing algorithms, it is possible to measure the oxygen saturation of deep tissues.

[0004] In early photoacoustic pulse oximetry systems, pump lasers were the primary choice for light sources due to their ideal characteristics of high peak power and narrow linewidth. However, the low repetition rate of pump lasers made real-time monitoring difficult, and their large size and high cost limited their application in medicine. With advancements in semiconductor technology, modern high-power LED light sources can now provide multiple wavelengths covering the characteristic absorption band of hemoglobin, and their nanosecond-level pulse widths can effectively excite photoacoustic signals.

[0005] This invention proposes a real-time venous oxygen saturation measurement system and method based on an LED light source. The system possesses deep tissue detection capabilities and can perform convenient, stable, and relatively accurate quantitative calculations of venous oxygen saturation, providing an important imaging tool for clinical scenarios such as intensive care, real-time surgical monitoring, and cerebral oxygen metabolism assessment. Summary of the Invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a real-time measurement system and method for venous blood oxygen saturation based on LED light source, which addresses the shortcomings of the existing technology.

[0007] To address the aforementioned technical problems, this invention discloses a real-time venous blood oxygen saturation measurement system based on an LED light source. The system includes a pulse drive circuit, a dual-wavelength LED light source, a photoacoustic light source fixture, an ultrasonic transducer, an ultrasonic signal processing platform, and a finger-clip pulse oximeter.

[0008] The pulse driving circuit is connected to the dual-wavelength LED light source via a low-impedance transmission line.

[0009] The photoacoustic light source fixture fixes the dual-wavelength LED light source to both ends of the ultrasonic transducer, together forming a handheld photoacoustic signal probe; the operator can adjust the photoacoustic light source fixture according to the contour of the part being measured to change the illumination angle and distance of the dual-wavelength LED light source.

[0010] The ultrasonic transducer is connected to the ultrasonic signal processing platform;

[0011] The measurement values ​​from the finger-clip pulse oximeter are transmitted to the ultrasound signal processing platform.

[0012] This method is implemented using a real-time venous oxygen saturation measurement system based on an LED light source, and includes the following steps:

[0013] Step 1: The pulse drive circuit outputs a high-frequency, narrow-pulse-width pulse voltage to drive the LEDs of different wavelengths in the dual-wavelength LED light source to flash alternately; the handheld photoacoustic signal probe is placed close to the part to be tested and coupled to the part to be tested, and the photoacoustic signal is collected by the ultrasonic transducer.

[0014] Step 2: The ultrasonic signal processing platform receives the photoacoustic signal collected by the ultrasonic transducer and performs subsequent amplification, filtering, digitization and analysis processing. In the ultrasonic signal processing platform, the photoacoustic signals excited by different wavelengths are separated, and the moving window averaging algorithm is used to perform noise reduction processing on the signals corresponding to the two wavelengths respectively.

[0015] Step 3: Control the ultrasonic transducer to emit ultrasonic signals to the same test site and receive its echo signals; then, reconstruct the ultrasonic image of the test site based on the echo signals in the ultrasonic signal processing platform.

[0016] Step 4: In the obtained ultrasound image, locate the vein to be analyzed and its adjacent artery. By locating the vein in the ultrasound image, obtain the photoacoustic signal intensity of the vein at the corresponding position of the photoacoustic signal. Similarly, by locating the artery in the ultrasound image, obtain the photoacoustic signal intensity of the artery at the corresponding position of the photoacoustic signal.

[0017] Because the ultrasonic transducer collects photoacoustic and ultrasonic signals at the same location in a very short time interval, the two signals are spatially aligned. The amplitude of the photoacoustic signal at the (x,y) position can be found by using the (x,y) horizontal and vertical coordinates of the vein in the ultrasound image.

[0018] Step 5: Based on the prior knowledge that the whole body arterial blood oxygen saturation is highly consistent, the whole body arterial blood oxygen saturation value is measured using a finger-clip pulse oximeter. Combined with the measured photoacoustic signal intensity of arteries and veins, the venous blood oxygen saturation is quantitatively calculated.

[0019] Step 6: By color-coding the calculated blood oxygen saturation data, the calculated blood oxygen saturation information is fused with the ultrasound image at the pixel level and presented intuitively on the same frame of ultrasound image, realizing the visualization of structural and functional imaging.

[0020] Photoacoustic imaging involves emitting infrared light to irradiate tissue. Certain substances within the tissue (such as melanin in the skin and hemoglobin in blood vessels) absorb the infrared light and generate ultrasound waves due to thermal expansion. If the photoacoustic image is reconstructed, you will see thin lines in the skin, followed by very bright spots a few millimeters below – these are blood vessels. The tissues between the blood vessels and the epidermis cannot be seen through photoacoustic imaging, but they weaken the energy of the infrared light reaching the blood vessels, thus affecting the calculation of blood oxygen saturation. Therefore, step four involves emitting ultrasound waves from the ultrasound transducer to explore these unknown tissues; this is the origin of the "ultrasound image" and is part of the process of reconstructing the "photoacoustic image." The "ultrasound image" cannot be used to calculate blood oxygen saturation.

[0021] Step 1 is as follows:

[0022] The pulse driving circuit drives one of the wavelengths of the dual-wavelength LED light source to emit light for a duration of 100ns, and the ultrasonic transducer synchronously collects photoacoustic signals of a fixed duration. After one cycle interval, the circuit switches to the other wavelength LED and emits pulse light again, while the ultrasonic transducer performs the same signal acquisition process.

[0023] The pulse drive circuit outputs a 400V drive voltage, providing sufficient energy for the normal operation of the LED light source; the repetition frequency reaches 4kHz, ensuring real-time imaging; it has a precise pulse width adjustment function, which can accurately set the LED light emission time to tens to hundreds of nanoseconds, realizing efficient photoacoustic signal excitation.

[0024] The dual-wavelength LED light source uses LEDs with high rated power and fast response speed. The operating wavelength of the LED is between 600nm and 950nm, which is the spectrum with high absorption of hemoglobin and low background interference, which helps to improve the imaging signal-to-noise ratio and contrast.

[0025] The center frequency of the ultrasonic transducer is preferably between 1MHz and 5MHz, which is a frequency band with high photoacoustic signal amplitude. It has the characteristics of high bandwidth and high sensitivity, and can effectively capture photoacoustic signals in a wide frequency band, significantly improving the signal-to-noise ratio and imaging resolution of the system.

[0026] In the actual detection process, the probe described in step 1 is closely attached to the part to be measured and coupled with the part to be measured, which is specifically achieved by using a medical coupling agent.

[0027] When selecting the artery adjacent to the target vein in step 4, the two vessels should be located in tissues with similar tissue depth and similar optical properties to ensure consistency of illumination conditions.

[0028] The calculation process for venous oxygen saturation in step 5 is as follows:

[0029] Under pulsed light irradiation with wavelength λ, the photoacoustic signal intensity A at a depth d below the skin surface is expressed as:

[0030] A(λ)=KΦ(λ)μ(λ)

[0031] Where K is a proportionality coefficient, which is related to transducer sensitivity, ultrasound attenuation, and Grünesen coefficient. The influence of its variation on the photoacoustic signal intensity of adjacent arteries and veins is ignored. Φ(λ) is the light intensity reaching depth d. As mentioned above, in the selected vein and adjacent artery, the light intensity Φ(λ) is the same. μ(λ) represents the absorption coefficient of hemoglobin in the blood vessel for light with wavelength λ. The absorption coefficient μ(λ) of the vein is related to its blood oxygen saturation SvO2 as follows:

[0032]

[0033] in, With ε HbR (λ) represents the molar absorptivity of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) at wavelength λ, respectively, and the specific values ​​can be obtained by consulting the literature; With cHbR Let be the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) in the target blood vessel, respectively. Substituting the above formula into the expression for photoacoustic signal intensity, the photoacoustic signal intensity A of the target vein measured under LED irradiation at different wavelengths λ1 and λ2 is calculated. v (λ1) and A v Taking the ratio (λ2), we can obtain:

[0034]

[0035] In the above equation for the ratio, Φ(λ) is the light intensity reaching the target vein under pulsed light with wavelength λ. By solving the above equation, the value of the blood oxygen saturation SvO2 of the vein can be obtained.

[0036] In the calculation process of venous oxygen saturation, in order to solve the value of SvO2, it is necessary to calculate the ratio of Φ(λ1) to Φ(λ2);

[0037] The photoacoustic signal intensity A of the adjacent artery was measured under LED illumination of different wavelengths. a (λ1) and A a (λ2) By taking the ratio and simplifying it, we can obtain the ratio of light intensity of adjacent arteries at different wavelengths:

[0038]

[0039] Among them, A a (λ) The intensity of the photoacoustic signal received from a neighboring artery under pulsed light excitation at wavelength λ. A is obtained by locating the neighboring artery in the ultrasound image and finding the corresponding position of the photoacoustic signal. a The value of (λ); SaO2 is the oxygen saturation of the adjacent artery. As described in step 5, the systemic arterial oxygen saturation value measured by the finger-clip pulse oximeter is used as the estimated value of the oxygen saturation of the artery.

[0040] Beneficial effects:

[0041] This invention proposes a real-time venous oxygen saturation measurement system and method based on an LED light source. The system employs a nanosecond-level pulse drive circuit to control a high-power LED light source to emit periodic short pulses of light, providing extremely high instantaneous power to the LED light source and achieving stable photoacoustic signal excitation and non-invasive measurement of deep tissue venous oxygenation. By locating the target vein and adjacent arteries using ultrasound images and using the oxygenation value of the adjacent arteries as a reference, convenient, stable, and relatively accurate quantitative calculation of venous oxygen saturation is achieved. The system's sampling rate is at the kHz level, maintaining a high frame rate after moving average, meeting clinical real-time dynamic detection standards. The use of high-power, multi-wavelength LEDs instead of expensive and bulky pump lasers significantly reduces cost and system size while ensuring photoacoustic excitation efficiency, making it more suitable for clinical application and bedside monitoring. Attached Figure Description

[0042] Figure 1 This is a structural block diagram of the photoacoustic real-time blood oxygen saturation measurement system in an embodiment of the present invention.

[0043] Figure 2 This is a schematic diagram of the structure of the handheld photoacoustic probe in an embodiment of the present invention.

[0044] Figure 3 This is a dual-modal image of wrist venous oxygen saturation measured in an embodiment of the present invention.

[0045] Figure 2 It includes 21. Dual-wavelength LED light source, 22. Photoacoustic light source fixture, and 23. Ultrasonic transducer. Detailed Implementation

[0046] A real-time venous blood oxygen saturation measurement system based on an LED light source, such as Figure 1 As shown, the system includes a pulse drive circuit, a dual-wavelength LED light source, a photoacoustic light source fixture, an ultrasonic transducer, an ultrasonic signal processing platform, and a finger-clip pulse oximeter.

[0047] The pulse driving circuit is connected to the dual-wavelength LED light source via a low-impedance transmission line.

[0048] The photoacoustic light source fixture fixes the dual-wavelength LED light source to both ends of the ultrasonic transducer, together forming a handheld photoacoustic signal probe; the operator can adjust the photoacoustic light source fixture 3 according to the contour of the part being measured to change the illumination angle and distance of the dual-wavelength LED light source 2.

[0049] The ultrasonic transducer is connected to the ultrasonic signal processing platform;

[0050] The measurement values ​​from the finger-clip pulse oximeter are transmitted to the ultrasound signal processing platform.

[0051] In this embodiment:

[0052] The dual-wavelength LED light source has two groups of LEDs in the circuit, with wavelengths of 850nm and 940nm respectively. The LEDs are arranged in a 14×4 array, with LEDs in the same group connected in series, and the two groups of LEDs are arranged alternately in the array. The typical radiant intensity of LED 21 in group A is 710mW / sr, the maximum instantaneous forward current reaches 2A, the forward voltage drop is 3.25V, the size of the light-emitting area is 0.73mm×0.73mm, the rise time is 9ns, the fall time is 16ns, and the package size is 1.5mm×1.5mm. The typical radiant intensity of LED 22 in group B is 765mW / sr, the maximum instantaneous forward current reaches 2A, the forward voltage drop is 2.8V, the size of the light-emitting area is 0.73mm×0.73mm, the rise time is 12ns, the fall time is 11.5ns, and the package size is 1.5mm×1.5mm. The dual-wavelength LED light source is a rectangular rigid circuit board, 45mm long and 9.4mm wide.

[0053] The number and arrangement of LEDs in the dual-wavelength LED light source circuit can be adjusted according to the light intensity requirements. Similarly, the circuit board shape parameters and the physical parameters of the photoacoustic light source fixture 3 of the dual-wavelength LED light source circuit can also be flexibly adjusted.

[0054] In this embodiment:

[0055] The ultrasonic transducer 4 used is a linear array ultrasonic transducer with a center frequency of 3.5MHz and a bandwidth of 3MHz.

[0056] The structure of the handheld photoacoustic signal probe is described in [reference]. Figure 2 The photoacoustic light source fixture 22 fixes the dual-wavelength LED light source 21 on both sides of the ultrasonic transducer 23. The operator can adjust the photoacoustic light source fixture 22 according to the contour of the part being measured to change the illumination angle and distance of the dual-wavelength LED light source 21.

[0057] This method is implemented using a real-time venous oxygen saturation measurement system based on an LED light source, and includes the following steps:

[0058] Step 1: The pulse drive circuit 1 outputs a high-frequency, narrow-pulse-width pulse voltage to drive the LEDs of different wavelengths in the dual-wavelength LED light source 2 to flash alternately; the handheld photoacoustic signal probe is placed close to the part to be tested and coupled to the part to be tested, and the photoacoustic signal is collected by the ultrasonic transducer.

[0059] Step 2: The ultrasonic signal processing platform receives the photoacoustic signal collected by the ultrasonic transducer and performs subsequent amplification, filtering, digitization and analysis.

[0060] In the ultrasonic signal processing platform 5, photoacoustic signals excited by different wavelengths are separated, and a moving window averaging algorithm is used to perform noise reduction processing on the signals corresponding to the two wavelengths respectively;

[0061] Step 3: Control the ultrasonic transducer 4 to emit ultrasonic signals to the same test site and receive its echo signals; then, reconstruct the ultrasonic image of the test site based on the echo signals in the ultrasonic signal processing platform 5.

[0062] In this embodiment, the area being measured is the wrist. For example... Figure 3 As shown, we selected veins (left) and arteries (right) at similar tissue depths as target and reference vessels, respectively.

[0063] Step 4: In the obtained ultrasound image, locate the target vein to be analyzed and its adjacent artery. By locating the target vein in the ultrasound image, obtain the photoacoustic signal intensity of the artery and vein at the corresponding position of the photoacoustic signal. Locate the adjacent artery in the ultrasound image, and obtain the photoacoustic signal intensity of the artery at the corresponding position of the photoacoustic signal.

[0064] Step 5: Based on the prior knowledge that the whole body arterial blood oxygen saturation is highly consistent, the whole body arterial blood oxygen saturation value is measured using a finger-clip pulse oximeter 6. Combined with the measured photoacoustic signal intensity of arteries and veins, the oxygen saturation of the target vein is quantitatively calculated.

[0065] Step 6: By color-coding the calculated blood oxygen saturation data, the calculated blood oxygen saturation information is fused with the ultrasound image at the pixel level and presented intuitively on the same frame of ultrasound image, realizing the visualization of structural and functional imaging.

[0066] According to claim 2, the method for real-time measurement of venous blood oxygen saturation based on LED light source is characterized in that, in the actual detection process, the probe in step 1 is closely attached to the measured part and coupled with the measured part, specifically by using a medical coupling agent to achieve coupling.

[0067] When selecting the artery adjacent to the target vein in step 4, it is required that the two vessels are in tissues with similar tissue depth and similar optical properties.

[0068] The calculation process for venous oxygen saturation in step 5 is as follows:

[0069] Under pulsed light irradiation with wavelength λ, the photoacoustic signal intensity A at a depth d below the skin surface is expressed as:

[0070] A(λ)=KΦ(λ)μ(λ)

[0071] Where K is a proportionality coefficient, which is related to transducer sensitivity, ultrasound attenuation, and Grünesen coefficient. The influence of its variation on the photoacoustic signal intensity of adjacent arteries and veins is ignored. Φ(λ) is the light intensity reaching depth d. As mentioned above, in the selected vein and adjacent artery, the light intensity Φ(λ) is the same. μ(λ) represents the absorption coefficient of hemoglobin in the blood vessel for light with wavelength λ. The absorption coefficient μ(λ) of the vein is related to its blood oxygen saturation SvO2 as follows:

[0072]

[0073] in, With ε HbR (λ) represents the molar absorptivity of oxyhemoglobin HbO2 and deoxyhemoglobin HbR at wavelength λ, and the specific values ​​can be obtained by consulting the literature. With c HbR Let be the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) in the target blood vessel, respectively. Substituting the above formula into the expression for photoacoustic signal intensity, the photoacoustic signal intensity A of the target vein measured under LED irradiation at different wavelengths λ1 and λ2 is calculated. v (λ1) and A v Taking the ratio (λ2), we can obtain:

[0074]

[0075] In the above equation for the ratio, Φ(λ) is the light intensity reaching the target vein under pulsed light with wavelength λ. By solving the above equation, the value of the blood oxygen saturation SvO2 of the vein can be obtained.

[0076] In the calculation process of venous oxygen saturation, in order to solve the value of SvO2, it is necessary to calculate the ratio of Φ(λ1) to Φ(λ2);

[0077] The photoacoustic signal intensity A of the adjacent artery was measured under LED illumination of different wavelengths. a (λ1) and A a (λ2) By taking the ratio and simplifying it, we can obtain the ratio of light intensity of adjacent arteries at different wavelengths:

[0078]

[0079] Among them, A a (λ) The intensity of the photoacoustic signal received from a neighboring artery under pulsed light excitation at wavelength λ. A is obtained by locating the neighboring artery in the ultrasound image and finding the corresponding position of the photoacoustic signal. aThe value of (λ); SaO2 is the oxygen saturation of the adjacent artery. As described in step 5, the systemic arterial oxygen saturation value measured by the finger-clip pulse oximeter is used as the estimated value of the oxygen saturation of the artery.

[0080] The dual-modal imaging results of this embodiment can be found in [reference needed]. Figure 3 The oxygen saturation of the adjacent artery was 98%, and the calculated oxygen saturation of the target venous blood was 72%. The image clearly shows the difference in oxygen saturation between arteries and veins, facilitating a direct visual assessment of oxygen perfusion information in this area.

[0081] The application value of this invention is not limited to peripheral blood vessels. For deeper, more critical physiological monitoring scenarios, the method of this invention demonstrates unique advantages, such as in monitoring jugular venous oxygen saturation, a key indicator for brain metabolism assessment. The jugular vein directly reflects the brain's oxygen supply and demand relationship and is a crucial blood vessel for assessing whole-brain metabolism, but it is located approximately 1-2 cm deep subcutaneously. While laser-based imaging technology can detect to this depth, its high single-pulse energy does not support prolonged exposure, posing a risk of thermal damage, and the light can also harm the eyes. On the other hand, while LED light sources offer high safety, their divergent characteristics make it difficult to calibrate the light source flux, thus hindering accurate calculation of blood oxygen saturation.

[0082] To address this challenge in clinical monitoring, the method for calculating venous oxygenation based on arterial standards proposed in this invention effectively overcomes the aforementioned limitations. As verified in this embodiment, this method significantly improves the accuracy of depth vascular oxygenation measurement while ensuring the safety of the light source, making it possible to non-invasively, safely, and continuously monitor jugular venous oxygen saturation and assess brain metabolism over a long period. This provides a potentially important tool for brain oxygenation management in neurocritical care (such as for patients with traumatic brain injury or stroke).

[0083] This invention provides a real-time venous blood oxygen saturation measurement system and method based on an LED light source. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A LED light source based real-time measurement system for venous blood oxygen saturation, characterized in that, The system comprises a pulse driving circuit, a dual-wavelength LED light source, a photoacoustic light source clamp, an ultrasonic transducer, an ultrasonic signal processing platform and a finger clip pulse oximeter. The pulse driving circuit is connected with the dual-wavelength LED light source through a low-impedance transmission line. The photoacoustic light source clamp fixes the dual-wavelength LED light source at both ends of the ultrasonic transducer, and together forms a handheld photoacoustic signal probe. The ultrasonic transducer is connected with the ultrasonic signal processing platform. The measurement value of the finger clip pulse oximeter is transmitted to the ultrasonic signal processing platform.

2. A method for real-time measurement of venous oxygen saturation based on LED light source, characterized in that, The method is realized based on a real-time measurement system of venous blood oxygen saturation of an LED light source, and comprises the following steps: Step 1: The pulse driving circuit outputs a high-frequency and narrow-pulse-width pulse voltage to drive the LEDs of different wavelengths in the dual-wavelength LED light source to flash alternately; the handheld photoacoustic signal probe is tightly attached to and coupled with the measured part, and the ultrasonic transducer collects photoacoustic signals; Step 2: The ultrasonic signal processing platform receives the photoacoustic signals collected by the ultrasonic transducer and performs subsequent amplification, filtering, digitization and analysis processing; in the ultrasonic signal processing platform, the photoacoustic signals excited by different wavelengths are separated, and the moving window average algorithm is used to perform noise reduction processing on the signals corresponding to the two wavelengths respectively; Step 3: The ultrasonic transducer emits ultrasonic signals to the same measured part and receives the echo signals; then, the ultrasonic signal processing platform reconstructs the ultrasonic image of the measured part based on the echo signals; Step 4: In the obtained ultrasonic image, the vein to be analyzed and the adjacent artery are located, the vein photoacoustic signal intensity is obtained at the corresponding position of the photoacoustic signal by locating the vein in the ultrasonic image, and the artery photoacoustic signal intensity is obtained at the corresponding position of the photoacoustic signal by locating the artery in the ultrasonic image; Step 5: Based on the prior knowledge that the arterial blood oxygen saturation of the whole body is highly consistent, the arterial blood oxygen saturation value of the whole body is measured by the finger clip pulse oximeter, and the venous blood oxygen saturation is quantitatively calculated by combining the measured photoacoustic signal intensities of the artery and the vein; Step 6: The blood oxygen saturation data obtained by calculation are color-coded, the calculated blood oxygen saturation information is pixel-level fused with the ultrasonic image, and the fusion result is intuitively presented on the same frame of ultrasonic image, so that the visualization of structure and function imaging is realized.

3. The method of claim 2, wherein the LED light source is a white LED light source. Step 1 is specifically as follows: The pulse driving circuit drives the LED of one wavelength in the dual-wavelength LED light source to emit light, and the ultrasonic transducer synchronously collects photoacoustic signals of a fixed time length for 100 ns; after a period of interval, the LED of another wavelength is switched to and the pulse light is emitted again, and the ultrasonic transducer performs the same signal collection process.

4. The LED-based source real-time venous blood oxygen saturation measurement system according to claim 1, wherein, The pulse driving circuit outputs a driving voltage to provide energy for the operation of the LED light source; the pulse driving circuit has a pulse width adjustment function and can accurately set the light-emitting time of the LED to tens to hundreds of nanoseconds to realize the excitation of photoacoustic signals.

5. The LED-based source real-time venous blood oxygen saturation measurement system according to claim 1, wherein, The working wavelength of the LED is between 600 nm and 950 nm.

6. The LED-based source real-time venous blood oxygen saturation measurement system according to claim 1, wherein, The center frequency of the ultrasonic transducer is 1 MHz-5 MHz.

7. The LED light source based real time measurement of venous blood oxygen saturation method according to claim 2, wherein, In the actual detection process, the probe in step 1 is closely attached to and coupled with the measured part, specifically, coupling is achieved by using a medical coupling agent.

8. The LED light source based real time measurement of venous blood oxygen saturation method according to claim 2, wherein, In step 4, when the artery blood vessel adjacent to the target vein is selected, it is required that the two blood vessels are in similar tissue depths and similar optical properties of the tissue.

9. The LED light source based real time measurement of venous blood oxygen saturation method according to claim 2, wherein, In step 5, the calculation process of the venous oxygen saturation is as follows: Under the irradiation of pulsed light with a wavelength of λ, the photoacoustic signal intensity A at a depth d below the skin surface is represented as: A(λ)=KΦ(λ)μ(λ) Where K is a proportional coefficient, which is related to the transducer sensitivity, ultrasonic attenuation and Gruneisen coefficient, and the influence of the change thereof on the photoacoustic signal intensity of the adjacent artery and vein is ignored, Φ(λ) is the light intensity reaching the depth d, as described above, in the selected vein and adjacent artery, the light intensity Φ(λ) has the same value, μ(λ) represents the absorption coefficient of hemoglobin in the blood vessel to light with a wavelength of λ, and the absorption coefficient μ(λ) of the venous blood vessel has the following relationship with the venous oxygen saturation SvO2: μ(λ) = (ε HbO2 (λ) * SvO2 + ε HbR (λ) * (1 - SvO2) * (c HbO2 + c HbR ) wherein ε HbO2 (λ) and ε HbR (λ) are the molar absorption coefficients of oxyhemoglobin HbO2 and deoxyhemoglobin HbR at wavelength λ, respectively, and c HbO2 and c HbR are the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) in the target blood vessel, respectively. Substituting the above equation into the expression of the photoacoustic signal intensity, the ratio of the photoacoustic signal intensity A v (λ1) measured under LED irradiation at different wavelengths λ1 and λ2 and A v (λ2) can be obtained: In the above ratio equation, Φ(λ) is the light intensity reaching the target vein under the irradiation of pulsed light with a wavelength of λ, and the above equation is solved to obtain the value of the venous oxygen saturation SvO2 of the venous blood vessel.

10. The LED light source based real-time measurement of venous blood oxygen saturation method according to claim 9, wherein, In the calculation process of the venous oxygen saturation, to solve the value of SvO2, it is required to calculate the ratio of Φ(λ1) to Φ(λ2); The light acoustic signal intensity A of the adjacent artery measured under irradiation of different wavelength LEDs a (λ1) and A a (λ2) are taken in ratio and arranged, and the ratio of the light intensity of the adjacent artery blood vessel under different wavelengths can be obtained: where A a (λ) is the intensity of the photoacoustic signal received from the proximal artery under the excitation of the pulsed light at wavelength λ, which is obtained by locating the proximal artery in the ultrasound image and taking the value of A a (λ) at the corresponding position of the photoacoustic signal; and SaO2 is the blood oxygen saturation of the proximal artery, which is estimated by taking the value of the systemic arterial blood oxygen saturation measured by the finger clip pulse oximeter as the blood oxygen saturation of the proximal artery.

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