Quantitative Detection Device and Method for Spatial Distribution of Blood Oxygen Saturation in Photodynamic Therapy

Abstract

The present invention discloses a quantitative detection device and method for the spatial distribution of blood oxygen saturation in photodynamic therapy. White light emitted by a white light LED generates a fringe image with a specific spatial frequency after passing through a digital micromirror device. The fringe image is projected onto a biological tissue to be measured through a projection lens and a first polarizer. The biological tissue generates a diffuse reflection light signal under this illumination. The diffuse reflection light signal passes through a second polarizer and a liquid crystal tunable filter. The liquid crystal tunable filter only allows the diffuse reflection light signal with a specific wavelength to pass through under computer control. The diffuse reflection light signal passing through the liquid crystal tunable filter is incident on the target surface of a CMOS camera after passing through an imaging lens. The CMOS camera transmits the collected image information into a computer to complete the acquisition of image information. The present invention can obtain the spatial distribution and its changes of tissue oxygen content during the photodynamic reaction, providing a reference basis for evaluating the degree of photodynamic reaction and further optimizing and regulating photodynamic therapy parameters to improve the efficacy of PDT.

Description

Technical Field

[0001] The present invention relates to the technical field of photodynamic therapy, and particularly to a quantitative detection device and method for the spatial distribution of blood oxygen saturation in photodynamic therapy. Background Art

[0002] Photodynamic therapy (PDT) is a targeted therapy technology in which photosensitizers and molecular oxygen in target tissues undergo a series of photophysical and photochemical reactions under illumination of a specific wavelength to generate reactive oxygen species (ROS), thereby selectively damaging the target tissues. Due to its advantages such as precise action, low toxicity and side effects, and repeatable treatment, PDT has broad application prospects in the treatment of malignant tumors, skin diseases, and infectious diseases. The photodynamic reaction is an oxygen-consuming process, and sufficient tissue oxygen content is a prerequisite for ensuring a sufficient photodynamic reaction and obtaining the expected therapeutic effect. While consuming the oxygen content in the target tissue, the photodynamic reaction may also block the microvessels supplying oxygen in the tissue, further causing local hypoxia and anoxia in the tissue body, and then reducing the production of reactive oxygen species, especially singlet oxygen, during the photodynamic reaction process and lowering the efficacy of PDT. Therefore, real-time monitoring of the tissue oxygen content during PDT is of great significance for optimizing the PDT treatment plan and evaluating its efficacy.

[0003] Research shows that techniques such as polarographic oxygen microelectrode technology, fluorescence quenching technology, phosphorescence spectroscopy technology, electron paramagnetic resonance imaging technology, and delayed fluorescence quenching technology can directly measure the absolute value of oxygen partial pressure (pO2); while techniques such as nuclear magnetic resonance technology, reflectance spectroscopy technology, frequency-domain photon migration spectroscopy technology, and Fourier transform spectroscopic imaging technology can calculate the blood oxygen saturation based on measuring the concentrations of oxyhemoglobin and deoxyhemoglobin in the blood, and indirectly obtain the oxygen content in the tissue. However, due to the non-uniformity of the oxygen content in the lesion tissue, existing measurement techniques are difficult to monitor tissue oxygen in the spatio-temporal dimension, unable to comprehensively reflect the change of tissue oxygen content during the photodynamic reaction process, not conducive to establishing a quantitative relationship between tissue oxygen content and PDT efficacy, and hindering the application and popularization of PDT. Summary of the Invention

[0004] The purpose of the present invention is to provide a quantitative detection device and method for the spatial distribution of blood oxygen saturation in photodynamic therapy, which uses wide-field imaging technology to quantitatively detect the concentrations of oxyhemoglobin and deoxyhemoglobin in the target tissue during photodynamic therapy, calculate the blood oxygen saturation, and reflect the change of tissue oxygen content during the photodynamic reaction process.

[0005] The technical solution adopted by the present invention is:

[0006] Quantitative detection device for spatial distribution of blood oxygen saturation in photodynamic therapy, which consists of a white light LED, a digital micromirror device, a projection lens, a first polarizer, a sample to be measured, a second polarizer, a liquid crystal tunable filter, an imaging lens, a CMOS camera and a computer. The white light emitted by the white light LED generates a sinusoidal gray-scale image with a specific spatial frequency through the digital micromirror device. This sinusoidal gray-scale image is projected onto the biological tissue to be measured through the projection lens and the first polarizer. The biological tissue generates a diffuse reflection light signal under this illumination. The diffuse reflection light signal enters the liquid crystal tunable filter after passing through the second polarizer. The liquid crystal tunable filter only allows the diffuse reflection light signal with a specific wavelength to pass through under the computer control instruction. The diffuse reflection light signal passing through the liquid crystal tunable filter is then incident on the target surface of the CMOS camera after passing through the imaging lens. The CMOS camera transmits the collected image information into the computer to complete the acquisition of the image information. By controlling the computer instruction to change the light transmission wavelength of the liquid crystal tunable filter, the above operations are repeated to obtain multiple spectral image information. The collected images are demodulated by the three-phase shift method, and the optical characteristic parameters of the biological tissue at different wavelengths are obtained by the look-up table method or the inverse Monte Carlo simulation method.

[0007] Further, the wavelength of the white light LED is 400nm - 720nm.

[0008] Further, under the action of the electronic switch, the micromirrors on the digital micromirror device can load the images with specific spatial frequencies generated by computer processing.

[0009] Further, the white light LED, the digital micromirror device and the projection lens are fixedly installed directly above the sample to be measured using a mounting bracket.

[0010] Further, the first polarizer is installed at the front end of the projection lens through a bracket; the second polarizer is threadedly installed at its front end through the liquid crystal tunable filter. The polarization directions of the first polarizer and the second polarizer are perpendicular to each other.

[0011] Further, the light transmission range of the liquid crystal tunable filter is 400 - 720nm, and the light transmission wavelength can be quickly switched.

[0012] Further, the liquid crystal tunable filter, the imaging lens and the CMOS camera are connected by the threads of each component. They are fixedly installed directly above the sample to be measured using a mounting bracket.

[0013] Further, the projection lens and the imaging lens are parallel to each other, and the distance between the projection system and the liquid crystal tunable filter is less than 5mm.

[0014] Quantitative detection method for spatial distribution of blood oxygen saturation in photodynamic therapy, which includes the following steps;

[0015] Step 1: Place the system in a dark room, turn on the CMOS camera, and collect dark-field image information;

[0016] Step 2: Turn on the white light LED, place the checkerboard (0.5 mm × 0.5 mm) at the position of the sample to be measured, project a uniform white light image onto the checkerboard through the digital micromirror device, the CMOS camera collects the checkerboard image, and obtain the number of pixels corresponding to a pair of black and white squares on the checkerboard image from the checkerboard image;

[0017] Step 3: Remove the checkerboard, place the diffuse reflection plate at the position of the sample to be measured, adjust the height of the diffuse reflection plate so that the surface of the diffuse reflection plate is at the same height as the surface of the checkerboard in Step 2, use MATLAB programming software to generate a square wave fringe image, and the spatial period of the square wave image is consistent with the linear dimension corresponding to a pair of black and white squares on the checkerboard. Control the digital micromirror device through computer instructions to generate a square wave structured light and project it onto the diffuse reflection plate, the CMOS camera collects the fringe image reflected by the diffuse reflection plate, obtain the number of pixels corresponding to one fringe period from the fringe image, perform ratio calculation with the number of pixels corresponding to a pair of black and white squares on the checkerboard image obtained in Step 2 to obtain the correction coefficient of the spatial frequency, and generate three-phase sine images with different spatial frequencies according to the correction coefficient through MATLAB programming software;

[0018] Step 4: Use a standard sample with known optical characteristic parameters, and calculate through the Monte Carlo simulation method to obtain the zero-frequency (f i = 0 mm x ) diffuse reflectance R -1 and high-frequency (f Dc，ref = 0.1 mm x ) diffuse reflectance R -1 of the standard sample at each wavelength λ1, λ2,... λ AC，ref ;

[0019] Step 5: Place the standard sample at the position of the sample to be measured, adjust the height of the standard sample so that the surface of the standard sample is at the same height as the surface of the checkerboard in Step 2, generate an image with three phases (0, 2π / 3, 4π / 3) of zero frequency (f x = 0 mm -1 ) and project it onto the surface of the standard sample in sequence through the digital micromirror device, the computer controls the liquid crystal tunable filter to select the passing optical wavelength λ1, and the CMOS camera synchronously collects the three-phase sine diagrams I 10 , I 20 and I 30 at zero frequency under the wavelength λ1, and calculate the DC amplitude M DC，ref of the standard sample at the wavelength λ1 according to formula (1):

[0020]

[0021] Among them, I 10 is the diffuse reflection light intensity value at zero frequency and 0 phase, and I 20 is the diffuse reflection light intensity value at zero frequency and 2π / 3 phase, and I 30 is the diffuse reflection light intensity value at zero frequency and 4π / 3 phase.

[0022] Step 6: Keep the light transmission wavelength λ1 of the liquid crystal tunable filter controlled, and project the three-phase (0, 2π / 3, 4π / 3) sine images with high frequency (f x = 0.1 mm -1 ) onto the surface of the standard sample in sequence through the digital micromirror device. The CMOS camera synchronously collects the three-phase sine graphs I1, I2, and I3 at high frequency under the wavelength λ1, and calculates and obtains the AC modulation depth M of the standard sample at the wavelength λ1 according to formula (2) AC，ref :

[0023]

[0024] Among them, I1 is the diffuse reflection light intensity value at high frequency and 0 phase, I2 is the diffuse reflection light intensity value at high frequency and 2π / 3 phase, and I3 is the diffuse reflection light intensity value at high frequency and 4π / 3 phase.

[0025] Step 7: Remove the standard sample, place the biological tissue to be measured at the sample to be measured, and repeat Step 5 and Step 6 to obtain M of the biological tissue at the wavelength λ1 DC，sample and M AC，sample ;

[0026] Step 8: Obtain the calibrated true reflectance R DC，sample and R AC，sample of the biological tissue to be measured according to formula (3) and formula (4), and then perform inversion of optical characteristic parameters through the inverse Monte Carlo simulation method or the look-up table method to obtain the absorption coefficient of the biological tissue at the wavelength λ1;

[0027]

[0028]

[0029] Step 9: Control the liquid crystal tunable filter to sequentially switch its light transmission wavelength to λ2,... λ i and then repeat Step 5, Step 6, Step 7, and Step 8 to respectively obtain the absorption coefficients of the biological tissue at the wavelengths λ2,... λ i ;

[0030] Step 10: According to the molar extinction coefficients ε i (λ i) The least squares fitting of formula (5) is performed to obtain the concentrations C of chromophores such as oxyhemoglobin and deoxyhemoglobin. i :

[0031]

[0032] Among them, μ a (λ i ) is the absorption coefficient of the biological tissue to be measured at wavelength λ i , ε i (λ i ) is the molar extinction coefficient of the i-th chromophore at wavelength λ i , and C i is the concentration of the i-th chromophore.

[0033] Then, the blood oxygen saturation of the biological tissue to be measured is calculated according to formula (6):

[0034]

[0035] Among them, StO2 is the blood oxygen saturation of the biological tissue to be measured, C(HbO2) represents the concentration of oxyhemoglobin, and C(Hb) represents the concentration of deoxyhemoglobin.

[0036] The present invention adopts the above technical solutions and has the following beneficial effects compared with the prior art: During the process of treating diseases by photodynamic therapy, spatial frequency domain diffuse reflection images are sequentially captured. On the basis of quantitatively obtaining tissue optical characteristic parameters, according to the relationship between the optical characteristic parameters and the concentrations of oxyhemoglobin and deoxyhemoglobin, the spatial distributions of the concentrations of oxyhemoglobin and deoxyhemoglobin in the tissue are obtained in a wide-field and quantitative manner, providing a reference basis for further evaluating the degree of photodynamic reaction and then optimizing and regulating photodynamic therapy parameters to improve the efficacy of PDT. The present invention has high cost performance, is easy to use, and is expected to be popularized and applied in the field of clinical photodynamic therapy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The following further describes the present invention in detail with reference to the drawings and specific embodiments;

[0038] Figure 1 is a schematic structural diagram of a device for quantitatively detecting the spatial distribution of tissue oxygen content during photodynamic therapy;

[0039] Figure 2 is a flow chart of a method for quantitatively detecting the spatial distribution of blood oxygen saturation in a photodynamic therapy.

[0040] In the figure: 1 - white light LED, 2 - digital micromirror device, 3 - projection lens, 4 - first polarizer, 5 - sample to be measured, 6 - second polarizer, 7 - liquid crystal tunable filter, 8 - imaging lens, 9 - CMOS camera, 10 - computer. Detailed implementation mode

[0041] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.

[0042] As Figure 1 shown in Fig. 1 or 2, the present invention discloses a quantitative detection device for the spatial distribution of blood oxygen saturation in photodynamic therapy, which includes a white light LED 1, a digital micromirror device 2, a projection lens 3, a first polarizer 4, a sample to be measured 5, a second polarizer 6, a liquid crystal tunable filter 7, an imaging lens 8, a CMOS camera 9, and an imaging computer 10. The white light LED 1 emits light and projects it onto the digital micromirror device 2. The computer 10 controls the digital micromirror device 2 through instructions to generate a three-phase sinusoidal grayscale image with a specific spatial frequency. The generated sinusoidal fringe image with a specific spatial frequency is projected onto the sample to be measured 5 through the projection lens 3 and the first polarizer 4. The diffuse reflected light generated by the sample to be measured 5 enters the liquid crystal tunable filter 7 through the second polarizer 6. The diffuse reflected light image of the biological tissue is collected by the imaging lens 8 and the CMOS camera 9. By changing the light passing wavelength of the liquid crystal tunable filter 7 and repeating the collection of the diffuse reflected light image, multiple spectral image information can be obtained. The collected image information is transmitted to the computer 10, and the three-phase shift method is used for image demodulation, and the optical characteristic parameters of the biological tissue are obtained by the look-up table method or the inverse Monte Carlo simulation method.

[0043] Refer to Figure 1 and Figure 2 , the specific steps of the quantitative detection device and method for the spatial distribution of tissue oxygen content during the photodynamic therapy in this embodiment are as follows:

[0044] Step 1: Place the system in a dark room, turn on the CMOS camera (MV-CA013-AOUM, Hikvision, China), and collect dark field image information.

[0045] Step 2: Turn on the white light LED (MCWHL8-C1, Thorlabs, USA), place the checkerboard (0.5 mm × 0.5 mm) at the sample to be measured, project a uniform white light image onto the checkerboard through the digital micromirror device (LC4500-NIR-EKT, Keynote Photonics, USA), and the CMOS camera collects the checkerboard image. Obtain the number of pixels corresponding to a pair of black and white squares in the checkerboard image from the checkerboard image.

[0046] Step 3: Remove the checkerboard and place the diffuse reflectance plate at the position of the sample to be measured. Adjust the height of the sample to be measured so that the surface of the diffuse reflectance plate is at the same height as the surface of the checkerboard in Step 2. Use MATLAB programming software to generate a square wave fringe image. The spatial period of this square wave image is consistent with the linear dimension corresponding to a pair of black and white squares on the checkerboard. Control the digital micromirror device through computer instructions to generate a square wave structured light and project it onto the diffuse reflectance plate. The CMOS camera collects the fringe image reflected by the diffuse reflectance plate, obtains the number of pixels corresponding to one fringe period from the fringe image, and performs a ratio calculation with the number of pixels corresponding to one square on the checkerboard image obtained in Step 2 to obtain the calibration coefficient of the spatial frequency. According to the calibration coefficient, use MATLAB programming software to generate three-phase sinusoidal images with different spatial frequencies;

[0047] Step 4: Use a standard sample with known optical characteristic parameters to calculate the diffuse reflectance R i and R DC，ref at each wavelength λ1, λ2,... λ AC，ref through Monte Carlo simulation or diffuse approximation model;

[0048] Step 5: Place the standard sample at the position of the sample to be measured and adjust it so that the surface of the standard sample is at the same height as the surface of the checkerboard in Step 2. Generate an image of three-phase (0, 2π / 3, 4π / 3) with zero frequency (f x = 0 mm -1 ) on the surface of the standard sample in sequence through the digital micromirror device. Use a computer to control the liquid crystal tunable filter (VariSpec VIS, PerkinElmer, USA) to select the passing wavelength λ1, and the CMOS camera synchronously collects the three-phase sinusoidal images I 10 , I 20 and I 30 at wavelength λ1 under zero frequency. Calculate and obtain the DC amplitude M DC，ref of the standard sample at each wavelength according to the formula:

[0049]

[0050] Step 6: Project the sinusoidal image structured light of three-phase (0, 2π / 3, 4π / 3) with high frequency (f x ) onto the surface of the standard sample in sequence through the digital micromirror device. Use a computer to control the liquid crystal tunable filter to select the passing wavelength λ1 in sequence, and the CMOS camera synchronously collects the three-phase sinusoidal images I1, I2 and I3 at wavelength λ1 under high frequency. Calculate and obtain the AC amplitude M AC，ref of the standard sample at each wavelength according to the formula:

[0051]

[0052] Step 7: Remove the standard sample, place the biological tissue to be measured at the sample to be measured, and repeat Step 5 and Step 6 to obtain M of the biological tissue at wavelength λ1 DC，sample and M AC，sample :

[0053] Step 8: According to Formula (3) and Formula (4), perform inversion of optical characteristic parameters by the inverse Monte Carlo simulation method or the look-up table method to obtain the absorption coefficient of the biological tissue at wavelength λ1 DC，sample and R AC，sample :

[0054]

[0055]

[0056] Then, perform inversion of optical characteristic parameters by the inverse Monte Carlo simulation method or the look-up table method to obtain the absorption coefficient of the biological tissue at wavelength λ1

[0057] Step 9: Control the liquid crystal tunable filter to sequentially switch its passing wavelength to λ2,... λ i After that, repeat Step 5, Step 6, Step 7 and Step 8 to obtain the absorption coefficients of the biological tissue at wavelengths λ2,... λ i respectively

[0058] Step 10: According to the molar extinction coefficients ε i (λ i ) of chromophores such as oxyhemoglobin and deoxyhemoglobin, perform least squares fitting on the following formula to obtain the concentrations C i of chromophores such as oxyhemoglobin and deoxyhemoglobin:

[0059]

[0060] Then, calculate the blood oxygen saturation of the biological tissue according to the following formula:

[0061]

[0062] Through the above steps, the quantitative detection of the spatial distribution of tissue oxygen content during the photodynamic therapy can be completed.

[0063] The present invention adopts the above technical solutions and has the following beneficial effects compared with the prior art: During the process of treating diseases by photodynamic therapy, spatial frequency domain diffuse reflection images are sequentially captured. On the basis of quantitatively obtaining tissue optical characteristic parameters, according to the relationship between the optical characteristic parameters and the concentrations of oxyhemoglobin and deoxyhemoglobin, the spatial distributions of the concentrations of oxyhemoglobin and deoxyhemoglobin in the tissue are obtained in a wide-field and quantitative manner, providing a reference basis for further evaluating the degree of the photodynamic reaction and then optimizing and regulating the photodynamic therapy parameters to improve the efficacy of PDT. The present invention has high cost performance, is easy to use, and is expected to be popularized and applied in the field of clinical photodynamic therapy.

[0064] Obviously, the described embodiments are part of the embodiments of this application, rather than all of the embodiments. Without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Usually, the components of the embodiments of this application described and illustrated in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application is not intended to limit the scope of this application claimed, but merely represents the selected embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

Claims

1. A quantitative detection method for the spatial distribution of blood oxygen saturation in photodynamic therapy, characterized in that: It includes the following steps: Step 1: Place the quantitative detection device in a dark room, and turn on the CMOS camera to collect dark-field image information; The quantitative detection device includes an LED light engine, a first polarizer, a liquid crystal tunable filter, a second polarizer, an imaging lens, a CMOS camera, and a computer; Step 2: Turn on the white light LED, place the checkerboard at the position of the sample to be measured, project a uniform white light image onto the checkerboard through the digital micromirror device, the CMOS camera collects the checkerboard image, and obtain the number of pixels of a pair of black and white squares from the checkerboard image; Step 3: Remove the checkerboard, place the diffuse reflection plate at the position of the sample to be measured, make the surface of the diffuse reflection plate at the same height as the surface of the checkerboard in Step 2, use the MATLAB programming software to generate a square wave fringe image, and the spatial period of the square wave fringe image is consistent with the linear dimension of a pair of black and white squares of the checkerboard; control the digital micromirror device to generate a square wave structured light and project it onto the diffuse reflection plate, the CMOS camera collects the fringe image reflected by the diffuse reflection plate, obtain the number of pixels of a fringe period from the fringe image, perform a ratio calculation with the number of pixels of a square of the checkerboard image to obtain the correction coefficient of the spatial frequency, and generate three-phase sine images with different spatial frequencies through the MATLAB programming software according to the correction coefficient; Step 4: Use a standard sample with known optical characteristic parameters, and calculate the diffuse reflectance R i of the standard sample at each wavelength λ1, λ2, … λ DC,ref and R AC,ref ; Step 5: Place the standard sample at the position of the sample to be measured, making the surface of the standard sample at the same height as the surface of the checkerboard in Step 2. Generate images of zero-frequency three-phase and project them onto the surface of the standard sample in sequence. Control the passing light wavelength λ1 of the liquid crystal tunable filter, and the CMOS camera synchronously collects the three-phase sine graphs I 10 , I 20 and I 30 , and calculate the DC amplitude M DC,ref : Step 6: Control the light-transmitting wavelength λ1 of the liquid crystal tunable filter, and sequentially project the high-frequency three-phase sinusoidal images onto the surface of the standard sample through the digital micromirror device. The CMOS camera synchronously acquires the three-phase sinusoidal images I1, I2, and I3 at the high frequency of wavelength λ1, and calculates the AC amplitude M of the standard sample at wavelength λ1 AC,ref : Step 7: Remove the standard sample, place the biological tissue to be measured at the sample to be measured, and repeat Step 5 and Step 6 to obtain M of the biological tissue at the wavelength of λ1 DC,sample and M AC,sample ; Step 8: Obtain the calibrated true reflectance R of the biological tissue to be measured DC,sample and R AC,sample , perform optical property parameter inversion by the inverse Monte Carlo simulation method or the look-up table method, and obtain the absorption coefficient of the biological tissue at the wavelength of λ1. The formula is: Step 9: Control the liquid crystal tunable filter to sequentially switch the light transmission wavelengths to λ2, …, λ i After that, repeat Steps 5 to 8 to respectively obtain the absorption coefficients of the biological tissue at λ2, …, λ i wavelengths; Step 10: According to the molar extinction coefficients ε of the chromophores of oxyhemoglobin and deoxyhemoglobin i (λ i ), perform least-squares fitting to obtain the chromophore concentrations C of oxyhemoglobin and deoxyhemoglobin i : where μ a (λ i ) is the absorption coefficient of the biological tissue to be measured at wavelength λ i , ε i (λ i ) is the molar extinction coefficient of the i-th chromophore at wavelength λ i , and C i is the concentration of the i-th chromophore; Calculate the blood oxygen saturation of the biological tissue to be measured: Wherein, StO2 is the blood oxygen saturation of the biological tissue to be measured, C(HbO2) is the concentration of oxyhemoglobin, and C(Hb) is the concentration of deoxyhemoglobin.

2. The quantitative detection method for the spatial distribution of blood oxygen saturation in the photodynamic therapy according to claim 1, wherein: The LED light engine includes a white light LED, a digital micromirror device, and a projection lens arranged along the optical path, and the white light LED emits light with a wavelength of 400nm - 720nm.

3. The quantitative detection method for the spatial distribution of blood oxygen saturation in the photodynamic therapy according to claim 2, characterized in that: The white light LED, the digital micromirror device, and the projection lens are fixedly installed directly above the sample to be measured using a mounting bracket.

4. The quantitative detection method for the spatial distribution of blood oxygen saturation in the photodynamic therapy according to claim 2, wherein: The first polarizer is installed at the front end of the light exit surface of the projection lens through a bracket; the second polarizer is installed at the front end of the liquid crystal tunable filter through a thread on the liquid crystal tunable filter, and the polarization directions of the first polarizer and the second polarizer are perpendicular to each other.

5. The quantitative detection method for the spatial distribution of blood oxygen saturation in the photodynamic therapy according to claim 2, wherein: The projection lens and the imaging lens are parallel to each other, and the distance between the projection system and the liquid crystal tunable filter is less than 5mm.

6. The quantitative detection method for the spatial distribution of blood oxygen saturation in photodynamic therapy according to claim 1, characterized in that: The liquid crystal tunable filter, the imaging lens, and the CMOS camera are connected through the threads of each component, and are fixedly installed directly above the sample to be measured using a mounting bracket.

7. The quantitative detection method for the spatial distribution of blood oxygen saturation in the photodynamic therapy according to claim 1, characterized in that: The light transmission range of the liquid crystal tunable filter is 400 - 720nm.

8. The quantitative detection method for the spatial distribution of blood oxygen saturation in the photodynamic therapy according to claim 1, characterized in that: The three-phase bitmaps in Step 6 are the phase diagrams corresponding to 0, 2π / 3, and 4π / 3 respectively.

Images