Deep tissue oxygen partial pressure monitoring method and system

Abstract

The invention discloses a deep tissue oxygen partial pressure monitoring method and system, and relates to the technical field of oxygen partial pressure monitoring, and the method comprises the following steps: adding a coupling probe into a deep tissue; the method comprises the following steps: exciting a coupling probe in a deep tissue by using an X-ray source so that the coupling probe emits fluorescence in a specific spectrum band, collecting a fluorescence image of the fluorescence in the specific spectrum band, irradiating a deep tissue sample by using an external light source, and collecting a white light image of the deep tissue every certain angle; converting each white light image into a binary image; performing three-dimensional reconstruction on the converted binary image, and constructing a three-dimensional surface contour of the deep tissue; sampling points are uniformly selected from the three-dimensional surface contour, the fluorescence image is mapped to the three-dimensional surface contour of the deep tissue according to the structural relation between the fluorescence image and the three-dimensional surface contour, and three-dimensional light intensity distribution of the coupling probe is obtained; according to the three-dimensional light intensity distribution and the Stern-Volmer equation, the three-dimensional partial pressure of the deep tissue is obtained, and rapid and convenient monitoring of the oxygen partial pressure of the deep tissue is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of oxygen partial pressure monitoring, and in particular to a method and system for monitoring deep tissue oxygen partial pressure. Background Art

[0002] Deep tissue oxygen partial pressure is an important indicator for assessing whether tissue is hypoxic and further determining the state of the tissue.

[0003] At present, common oxygen partial pressure monitoring methods include oxygen electrode method, magnetic resonance imaging method, photoacoustic imaging method and optical imaging method. Among them, the oxygen electrode method is invasive, not suitable for real-time monitoring, and the detection depth is limited; magnetic resonance imaging takes a long time and is expensive; photoacoustic imaging indirectly evaluates the degree of tissue hypoxia by evaluating blood oxygen saturation, and cannot accurately and quickly visualize the oxygen partial pressure of the tissue. In the invention patent CN101788477B, oxygen partial pressure monitoring is achieved through an oxygen partial pressure monitor, which is invasive monitoring and will cause damage to the monitored object; in patent CN 116718574A, this method is applied to the oxygen partial pressure in the extracorporeal circulation circuit, and can only obtain a single value of the oxygen partial pressure in the circuit, and it is difficult to obtain the three-dimensional distribution data of the oxygen partial pressure.

[0004] In short, the currently used oxygen partial pressure monitoring method can only obtain a single value of oxygen partial pressure, and it is difficult to monitor the three-dimensional oxygen partial pressure in deep tissues. Summary of the invention

[0005] In view of the deficiency of the prior art that it is difficult to monitor the three-dimensional oxygen partial pressure in deep tissue, the present invention proposes a method and system for monitoring the oxygen partial pressure in deep tissue. Through the single-view fluorescence molecule reconstruction technology, the three-dimensional fluorescence intensity distribution inside the tissue is obtained, thereby realizing fast and convenient monitoring of the oxygen partial pressure in deep tissue, thereby solving the problems existing in the prior art.

[0006] A method for monitoring deep tissue oxygen partial pressure comprises the following steps:

[0007] Select an X-ray luminescent material and an oxygen sensitive material to synthesize a coupled probe, and place the coupled probe in a deep tissue sample; use an X-ray source to excite the coupled probe in the deep tissue sample to make it emit fluorescence in a specific spectrum, and collect fluorescence images of the fluorescence in the specific spectrum emitted from multiple angles of the deep tissue sample;

[0008] Turn off the X-ray source, use an external light source to illuminate the deep tissue sample, collect white light images of the deep tissue sample at multiple angles, and construct a three-dimensional surface contour of the deep tissue; uniformly select sampling points from the three-dimensional surface contour, and calculate the difference between the fluorescence value of the sampling point and the fluorescence image based on the structural relationship between the fluorescence image and the three-dimensional surface contour; map the fluorescence image to the three-dimensional surface contour of the deep tissue based on the difference, and obtain the three-dimensional light intensity distribution of the coupling probe;

[0009] The three-dimensional oxygen partial pressure in deep tissues is obtained based on the three-dimensional light intensity distribution of the coupled probe.

[0010] Furthermore, an electron multiplying charge coupled device (EMCCD) is used to collect fluorescence images of fluorescence in a specific spectral band.

[0011] Furthermore, the method of irradiating the deep tissue sample with an external light source, collecting white light images of the deep tissue sample at multiple angles, and constructing a three-dimensional surface profile of the deep tissue specifically includes the following steps:

[0012] Using an external light source, a white light image of the deep tissue sample is collected at a certain angle until a 360-degree rotation is completed;

[0013] Each white light image is converted into a binary image using a threshold segmentation algorithm;

[0014] The converted binary image is input into the filtered back-projection algorithm for three-dimensional reconstruction to construct the three-dimensional surface contour of the deep tissue.

[0015] Furthermore, a method of fusing group sparse prior and depth compensation is used to obtain the three-dimensional light intensity distribution of the coupled probe, which specifically includes the following steps:

[0016]

[0017] Where Φ is the fluorescence value mapped to the surface, Y is the three-dimensional light intensity distribution, W is the system matrix, and W d and W m are depth compensation matrices, λ 1 and λ 2 is the regularization parameter, and the construction of R is expressed as:

[0018]

[0019] Among them, i and j represent the row and column numbers of the voxel respectively;

[0020] Depth compensation matrix W d and W m Respectively expressed as:

[0021]

[0022] in The matrix is ​​an initial distribution of probes, and q is the weight;

[0023]

[0024] Among them, W j represents the jth column of the W matrix, β j represents the weight of the j-th voxel, and n is the number of columns of W.

[0025] Furthermore, the three-dimensional oxygen partial pressure of the deep tissue is obtained according to the three-dimensional light intensity distribution of the coupling probe; specifically, the three-dimensional oxygen partial pressure of the deep tissue is obtained by inputting the three-dimensional light intensity distribution of the coupling probe into the Stern-Volmer equation after parameter calibration; the Stern-Volmer equation is expressed as:

[0026] Y 0 / Y=1+k q pO 2

[0027] Among them, Y 0 represents the three-dimensional light intensity distribution when the nitrogen-oxygen ratio is 1:0; pO 2 represents the oxygen partial pressure, k q is a constant, and Y is the three-dimensional light intensity distribution.

[0028] Furthermore, the parameter calibration process of the Stern-Volmer equation includes the following steps:

[0029] Oxygen and nitrogen are introduced into the solution containing the coupled probe, and the oxygen electrode is inserted into the solution to measure the oxygen partial pressure in the current solution;

[0030] Turn on the X-ray source, set the current and voltage parameters, and turn on the electron multiplying charge coupled device (EMCCD) to take a fluorescence image; the sum of the fluorescence values ​​of all pixels in the image is calculated as the three-dimensional light intensity distribution Y corresponding to the current oxygen partial pressure;

[0031] After changing the nitrogen and oxygen ratios for many times, the three-dimensional light intensity distribution after each change was obtained, and the Stern-Volmer equation was fitted to calculate the constant k q numerical value to complete the parameter calibration of the equation.

[0032] The present invention also includes a deep tissue oxygen partial pressure monitoring system, comprising:

[0033] A coupling probe is placed in the deep tissue sample; the coupling probe is a coupling body of an X-ray luminescent material and an oxygen sensitive probe;

[0034] An X-ray source is used to excite the coupled probe in the deep tissue sample to emit fluorescence in a specific spectral band;

[0035] Electron multiplying charge coupled device (EMCCD) is used to collect fluorescence images of specific spectral bands emitted from deep tissue samples at multiple angles;

[0036] The three-dimensional reconstruction module is used to turn off the X-ray source, use an external light source to illuminate the deep tissue sample, collect white light images of the deep tissue sample at multiple angles, and construct the three-dimensional surface contour of the deep tissue; uniformly select sampling points from the three-dimensional surface contour, and calculate the difference between the fluorescence value of the sampling point and the fluorescence image according to the structural relationship between the fluorescence image and the three-dimensional surface contour; map the fluorescence image to the three-dimensional surface contour of the deep tissue according to the difference, and obtain the three-dimensional light intensity distribution of the coupling probe;

[0037] The oxygen partial pressure acquisition module is used to obtain the three-dimensional oxygen partial pressure of deep tissue according to the three-dimensional light intensity distribution of the coupled probe.

[0038] Furthermore, it also includes a rotating table on which the bottom of the deep tissue is placed; the rotating table is used to drive the deep tissue to rotate at an angle.

[0039] Furthermore, it also includes a filter placed at the EMCCD receiving end; the filter is used to filter out fluorescence of a specific wavelength.

[0040] The present invention provides a method and system for monitoring deep tissue oxygen partial pressure, which has the following beneficial effects:

[0041] The present invention selects an X-ray luminescent material and an oxygen sensitive material to synthesize a coupled probe, adds the coupled probe to a deep tissue sample, converts the X-rays reaching the deep tissue into fluorescence, and then reacts with the oxygen sensitive material coupled thereto to produce a fluorescence quenching effect, thereby facilitating the generation of a fluorescence image; a three-dimensional surface contour of the deep tissue is constructed by collecting white light images of the deep tissue sample at each angle using an external light source, and according to the structural relationship between the fluorescence image and the three-dimensional surface contour, the fluorescence image is mapped to the three-dimensional surface contour of the deep tissue, thereby more conveniently obtaining the three-dimensional fluorescence intensity distribution inside the tissue, thereby realizing rapid monitoring of the oxygen partial pressure of the deep tissue sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 4 is a framework diagram of a deep tissue oxygen partial pressure monitoring system in an embodiment of the present invention.

[0043] Figure 2 4 is a flow chart of a method for monitoring deep tissue oxygen partial pressure in an embodiment of the present invention.

[0044] In the figure, 1-X-ray source; 2-monitoring object; 3-rotating table; 4-coupled probe; 5-EMCCD; 6-filter; 7-computer. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0046] The present invention provides a deep tissue oxygen partial pressure monitoring system, such as Figure 1 As shown, it specifically includes: an X-ray source 1, a monitored object 2, a rotating table 3, a coupling probe 4, an EMCCD 5 (electron multiplying charge coupled device), a filter 6 and a computer 7.

[0047] The X-ray source 1 is used to excite the coupling probe in the monitored object; the monitored object 2 is an in vitro deep tissue sample; the rotating table 3 is used to support the monitored object and realize angular rotation; the coupling probe 4 is a coupling body of an X-ray luminescent material and an oxygen sensitive probe, which is used to emit fluorescence under X-ray excitation, and the fluorescence undergoes a fluorescence quenching reaction under the action of the oxygen sensitive probe; the EMCCD 5 is used to obtain the fluorescence emitted by the coupling probe and used for optical three-dimensional reconstruction; the filter 6 is used to filter out light of a specific wavelength; the computer 7 is used to control other equipment, complete fluorescence three-dimensional reconstruction, and finally calculate and display the tissue oxygen partial pressure.

[0048] Based on the above monitoring system, the present invention also proposes a method for monitoring deep tissue oxygen partial pressure, such as Figure 2 As shown, the specific steps include:

[0049] S1. Coupled probe synthesis: Select appropriate X-ray luminescent materials and oxygen-sensitive materials, and synthesize coupled probes by coprecipitation. The coupled probe synthesis converts X-rays reaching deep tissues into fluorescence, which then reacts with the oxygen-sensitive material coupled thereto to produce a fluorescence quenching effect.

[0050] S2. Preparation of monitoring object: Place the monitoring object on a rotating table and add a coupling probe into it; receive the fluorescence emitted by the probe for fluorescence image acquisition.

[0051] S3. Fluorescence data acquisition: Turn on the X-ray source, set the current, voltage and other parameters, use the excitation source to excite the coupled probe in the monitored object to emit fluorescence in a specific spectral band (such as 460nm), and the oxygen-sensitive probe interacts with the fluorescence in the specific spectral band (such as 460nm) to produce a quenching effect. Load a filter that can pass the above-mentioned specific wavelength light (such as 460nm) in front of the lens, turn on the EMCCD, set the relevant parameters, collect a pair of fluorescence images and save them. Collect the fluorescence after X-ray emission and quenching for subsequent three-dimensional reconstruction, parameter calibration and oxygen partial pressure calculation.

[0052] S4. Construction of the three-dimensional contour of the monitored object: turn off the X-ray source, turn on the external light source, remove the filter, collect a white light image of the monitored object at a certain angle and save it until a 360-degree rotation is completed. For each white light image, use threshold segmentation and other algorithms to convert it into a binary image. The converted binary image is reconstructed in three dimensions using the filtered back projection algorithm to construct the three-dimensional surface contour of the monitored object. The collected fluorescence image is three-dimensionally mapped, that is, the two-dimensional fluorescence value is converted to the corresponding point on the three-dimensional surface, in preparation for the subsequent fluorescence three-dimensional reconstruction.

[0053] S5, fluorescence three-dimensional reconstruction, reconstruction of the three-dimensional fluorescence intensity distribution inside the tissue, is the basis for calculating the oxygen partial pressure distribution; sampling points are uniformly selected from the three-dimensional contour, and the three-dimensional light intensity distribution of the coupled probe is obtained by using the fusion group sparse prior and depth compensation method. Specifically, it is achieved through the following optimization process:

[0054]

[0055] Where W is the system matrix, which establishes the relationship between the three-dimensional light intensity distribution and the photon distribution on the surface, Φ is the fluorescence value mapped to the surface, Y is the three-dimensional light intensity distribution, and W d and W m are depth compensation matrices, λ 1 and λ 2 is the regularization parameter, and R is constructed as follows:

[0056]

[0057] Where i and j represent the row and column numbers of the voxel respectively; the depth compensation matrix W d and W m is constructed as follows:

[0058]

[0059] in The matrix is ​​an initial distribution of probes, and q is the weight. d Used to weight the data, it provides constraints for the above optimization problem.

[0060]

[0061] Among them, W j represents the jth column of the W matrix, β j represents the weight of the jth voxel, and n is the number of columns in W. m It is used to balance the differences in the contribution of each voxel point of the imaged object to the surface photon intensity.

[0062] S6. Parameter calibration: The physical properties of the coupled probe are measured experimentally, and the constant parameters in the formula are determined to provide a formula basis for the final oxygen partial pressure calculation: oxygen and nitrogen are introduced into the solution containing the coupled probe, and the oxygen electrode is inserted into the solution to measure the oxygen partial pressure in the current solution. Turn on the X-ray source, set the current and voltage parameters, turn on the EMCCD to take a fluorescence image, and the sum of the fluorescence values ​​of all pixels in the image is calculated as the fluorescence intensity corresponding to the current oxygen partial pressure (i.e., the Stern-Volmer equation Y 0 / Y=1+k q pO 2 Change the ratio of nitrogen to oxygen (such as 1:0, 1:0.25, 1:0.75, 1:2, 0:1) to obtain a series of fluorescence intensities (the fluorescence intensity when the nitrogen to oxygen ratio is 1:0 is Y 0 ), fit the Stern-Volmer equation, and calculate the constant k q numerical value, complete the equation calibration.

[0063] S7. Calculation of three-dimensional oxygen partial pressure: Calculate the three-dimensional oxygen partial pressure based on the three-dimensional light intensity distribution of the coupled probe calculated in step 5 and the calibrated equation in step S4.

[0064] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for monitoring deep tissue oxygen partial pressure, characterized in that: The following steps are involved: Select an X-ray luminescent material and an oxygen sensitive material to synthesize a coupled probe, and place the coupled probe in a deep tissue sample; use an X-ray source to excite the coupled probe in the deep tissue sample to make it emit fluorescence in a specific spectrum, and collect fluorescence images of the fluorescence in the specific spectrum emitted from multiple angles of the deep tissue sample; Turn off the X-ray source, use an external light source to illuminate the deep tissue sample, collect white light images of the deep tissue sample at multiple angles, and construct a three-dimensional surface contour of the deep tissue; uniformly select sampling points from the three-dimensional surface contour, and calculate the difference between the fluorescence value of the sampling point and the fluorescence image based on the structural relationship between the fluorescence image and the three-dimensional surface contour; map the fluorescence image to the three-dimensional surface contour of the deep tissue based on the difference, and obtain the three-dimensional light intensity distribution of the coupling probe; The three-dimensional oxygen partial pressure in deep tissues is obtained based on the three-dimensional light intensity distribution of the coupled probe.

2. A method for monitoring deep tissue oxygen partial pressure according to claim 1, characterized in that: An electron multiplying charge coupled device (EMCCD) is used to collect fluorescence images of specific spectral bands.

3. A method for monitoring deep tissue oxygen partial pressure according to claim 1, characterized in that: The method of irradiating the deep tissue sample with an external light source, collecting white light images of the deep tissue sample at multiple angles, and constructing a three-dimensional surface profile of the deep tissue specifically includes the following steps: Using an external light source, a white light image of the deep tissue sample is collected at a certain angle until a 360-degree rotation is completed; Each white light image is converted into a binary image using a threshold segmentation algorithm; The converted binary image is input into the filtered back-projection algorithm for three-dimensional reconstruction to construct the three-dimensional surface contour of the deep tissue.

4. A method for monitoring deep tissue oxygen partial pressure according to claim 1, characterized in that: The three-dimensional light intensity distribution of the coupled probe is obtained by using a method of fusion group sparse prior and depth compensation, which specifically includes the following steps: Where Φ is the fluorescence value mapped to the surface, Y is the three-dimensional light intensity distribution, W is the system matrix, and W d and W m are depth compensation matrices, λ1 and λ2 are regularization parameters, and the construction of R is expressed as: Among them, i and j represent the row and column numbers of the voxel respectively; Depth compensation matrix W d and W m Respectively expressed as: in The matrix is ​​an initial distribution of probes, and q is the weight; Among them, W j represents the jth column of the W matrix, β j represents the weight of the j-th voxel, and n is the number of columns of W.

5. A method for monitoring deep tissue oxygen partial pressure according to claim 1, characterized in that: The three-dimensional oxygen partial pressure in the deep tissue is obtained according to the three-dimensional light intensity distribution of the coupling probe; specifically, the three-dimensional oxygen partial pressure in the deep tissue is obtained by inputting the three-dimensional light intensity distribution of the coupling probe into the Stern-Volmer equation after parameter calibration; the Stern-Volmer equation is expressed as: Y0 / Y=1+k q pO2 Among them, Y0 represents the three-dimensional light intensity distribution when the nitrogen-oxygen ratio is 1:0; pO2 represents the oxygen partial pressure, k q is a constant, and Y is the three-dimensional light intensity distribution.

6. A method for monitoring deep tissue oxygen partial pressure according to claim 5, characterized in that: The parameter calibration process of the Stern-Volmer equation includes the following steps: Oxygen and nitrogen are introduced into the solution containing the coupled probe, and the oxygen electrode is inserted into the solution to measure the oxygen partial pressure in the current solution; Turn on the X-ray source, set the current and voltage parameters, turn on the electron multiplying charge coupled device (EMCCD) to take a fluorescence image; the sum of the fluorescence values ​​of all pixels in the image is calculated as the three-dimensional light intensity distribution Y corresponding to the current oxygen partial pressure; After changing the nitrogen and oxygen ratios for many times, the three-dimensional light intensity distribution after each change was obtained, and the Stern-Volmer equation was fitted to calculate the constant k q numerical value to complete the parameter calibration of the equation.

7. A deep tissue oxygen partial pressure monitoring system, characterized in that: include: A coupling probe is placed in the deep tissue sample; the coupling probe is a coupling body of an X-ray luminescent material and an oxygen sensitive probe; An X-ray source is used to excite the coupled probe in the deep tissue sample to make it emit fluorescence in a specific spectral band; Electron multiplying charge coupled device (EMCCD) is used to collect fluorescence images of specific spectral bands emitted from deep tissue samples at multiple angles; The three-dimensional reconstruction module is used to turn off the X-ray source, use an external light source to illuminate the deep tissue sample, collect white light images of the deep tissue sample at multiple angles, and construct the three-dimensional surface contour of the deep tissue; uniformly select sampling points from the three-dimensional surface contour, and calculate the difference between the fluorescence value of the sampling point and the fluorescence image according to the structural relationship between the fluorescence image and the three-dimensional surface contour; map the fluorescence image to the three-dimensional surface contour of the deep tissue according to the difference, and obtain the three-dimensional light intensity distribution of the coupling probe; The oxygen partial pressure acquisition module is used to obtain the three-dimensional oxygen partial pressure of deep tissue according to the three-dimensional light intensity distribution of the coupled probe.

8. A deep tissue oxygen partial pressure monitoring system according to claim 7, characterized in that: It also includes a rotating platform on which the bottom of the deep tissue is placed; the rotating platform is used to drive the deep tissue to rotate at an angle.

9. A deep tissue oxygen partial pressure monitoring system according to claim 7, characterized in that: It also includes a filter placed at the EMCCD receiving end; the filter is used to filter out fluorescence with a specific wavelength.

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