CN104865195B - The detection method of optical projection fault imaging - Google Patents

Abstract

The detection method of optical projection tomography provided by the present invention includes collecting first image data through an optical projection tomography system, and the first image data includes first polarization condition image data, second polarization condition image data and first sample Transmission image data; processing the first sample transmission image data to obtain transmission three-dimensional data; processing the first polarization condition image data and the second polarization condition image data to obtain polarization condition three-dimensional pre-data and birefringent tissue area Figure; the birefringent tissue area map back-projects the polarization condition three-dimensional pre-data to obtain the polarization condition three-dimensional data; the transmission three-dimensional data, the birefringence tissue area map and the polarization condition three-dimensional data are analyzed . The present invention can effectively detect birefringent tissue in an optical projection tomography system.

Description

Detection method of optical projection tomography

technical field

The invention relates to optical projection tomography technology, in particular to a detection method of optical projection tomography.

Background technique

Optical projection tomography can be divided into transmission optical projection tomography and excitation optical projection tomography, both of which take advantage of the characteristic that light propagates approximately along a straight line in a transparentized subcentimeter-sized biological sample. Among them, the transmission optical projection tomography technology uses a light source to emit visible light to penetrate the sample, and then uses a camera to collect projection views of the sample from multiple angles for three-dimensional imaging; while the excitation optical projection tomography technology uses laser light to irradiate fluorescent substances in the sample , the fluorescent substance emits emission light after receiving the excitation light, and a camera is used to collect fluorescence emission images from multiple angles for three-dimensional imaging.

Specifically, when performing optical projection tomography, it is necessary to scan the sample from multiple angles. Generally, an electronically controlled turntable is used to rotate the sample in steps, and one or more projection images are collected for each rotation to an angle. During the scanning process, the sample There is no vertical or horizontal movement, only rotation. The final data collected by the optical projection tomography system is a series of two-dimensional image data at different angles. If a certain row of all two-dimensional images is extracted and superimposed into an image by row in sequence according to the scanning sequence, we can get A sinusoidal diagram similar to a sinusoidal curve, each sinusoidal diagram corresponds to a horizontal reconstruction slice of the sample, and all sinusoidal diagrams correspond to the three-dimensional tomographic reconstruction volume of the sample, the process from projection data to the three-dimensional tomographic structure of the sample is called optical projection Tomographic 3D reconstruction.

Optical projection tomography technology can realize structural (transmission) and molecular-specific functional (excitation) imaging of biological samples at the scale of 1-10 mm. depiction needs. But at the same time, there are many deficiencies in the transmission optical projection tomography imaging of the sample structure, one of which is that it can only examine the light absorption properties of the tested sample, and after the sample is made transparent by light, the internal tissues Sometimes there is no obvious difference in light absorption properties, which leads to the three-dimensional reconstruction results of the sample by transmission optical projection tomography, which is often not used to effectively identify various tissues, and it is difficult to determine its structure. The distribution relationship among them provides further help.

At present, in the field of optical projection tomography, the method for identifying various tissues in a sample and delineating the outline of a specific tissue is usually to use excitation optical projection tomography to detect samples, that is, through transgenic or sample The fluorescent labeling method stains the tissue of interest in the sample, and then indirectly investigates the distribution of the tissue of interest by detecting the specific emission light emitted from the sample after being irradiated with excitation light. At the same time, the process of adding fluorescent labels to samples will increase the complexity of experiments, and how to make fluorescent substances fully and specifically bind to specific tissues of large-volume samples has not been studied enough so far.

Contents of the invention

The detection method of the optical projection tomography provided by the invention can effectively detect the birefringence tissue in the optical projection tomography system.

According to an aspect of the present invention, a detection method of optical projection tomography is provided, comprising:

collecting first image data by an optical projection tomography system, the first image data including first polarization condition image data, second polarization condition image data and first sample transmission image data;

processing the transmission image data of the first sample to obtain transmission three-dimensional data;

Processing the first polarization-condition image data and the second polarization-condition image data to obtain polarization-condition three-dimensional pre-data and a birefringent tissue region map;

The birefringence tissue region map back-projects the polarization condition three-dimensional pre-data to obtain the polarization condition three-dimensional data;

The transmission three-dimensional data, the birefringent tissue area map and the polarization condition three-dimensional data are analyzed.

In the optical projection tomography detection method provided by the embodiment of the present invention, the first polarization condition image data, the second polarization condition image data and the first sample transmission image data are collected by the optical projection tomography system, and the first polarization condition image data , the image data of the second polarization condition and the transmission image data of the first sample are processed to obtain the three-dimensional pre-data of the polarization condition, the birefringent tissue area map and the three-dimensional transmission data respectively, and the birefringent tissue area map reverses the three-dimensional pre-data of the polarization condition The three-dimensional data of the polarization condition is obtained by projection, and the analysis of the transmission three-dimensional data, the three-dimensional pre-data of the polarization condition, the birefringent tissue area map and the three-dimensional data of the polarization condition can effectively detect the birefringent tissue in the optical projection tomography system.

Description of drawings

FIG. 1 is a flowchart of a detection method for optical projection tomography provided by an embodiment of the present invention;

Fig. 2 is a schematic diagram of an optical projection tomography system provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of image data collected by an optical projection tomography system under polarization conditions provided by an embodiment of the present invention;

Fig. 4 is a composite diagram of polarization conditions of image data collected under polarization conditions provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of two results of three-dimensional data visualization for polarization condition three-dimensional data provided by an embodiment of the present invention;

Fig. 6 is a schematic diagram of the fusion of the rendering results of the polarization condition three-dimensional data and the transmission three-dimensional data provided by the embodiment of the present invention.

Detailed ways

The detection method of the optical projection tomography provided by the embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a flowchart of a detection method for optical projection tomography provided by an embodiment of the present invention.

Referring to FIG. 1 , in step S101 , first image data is collected by an optical projection tomography system, and the first image data includes first polarization condition image data, second polarization condition image data and first sample transmission image data.

Here, the optical projection tomography system includes a light source module and a signal acquisition module. The light source module includes a light source, frosted glass, and an adjustable polarizer; the signal acquisition module includes a microscope group, a camera, and an adjustable polarizer. For details, refer to the schematic diagram of the optical projection tomography system shown in Figure 2, where L is the light source; P1 is an adjustable polarizer; S is a sample; P2 is an adjustable analyzer; MS is a microscope; CIC is a camera imaging chip.

The light source can be a diffused white light source with broadband output, its wavelength can cover the entire visible light range, and it has high wavelength stability in the visible light range.

The frosted glass is placed in front of the light source, so that the light beam of the diffused light source is irradiated on the surface to form a spot with a large enough diameter, and the surface of the ground glass makes the light intensity distribution in the spot more uniform, so that when the sample is not placed, the image collected by the signal acquisition module The difference in intensity of each pixel point is less than 10% as the standard. The ground glass surface should be as perpendicular as possible to the axial direction of the signal acquisition module, and the included angle can be 90±1°.

The adjustable polarizer is a device composed of a circular polarizing plate and an adjusting frame. The large aperture on the polarizing plate can filter the entire light spot on the ground glass. When natural light passes through the polarizer, the ratio of the intensity of one of its orthogonally polarized components to the intensity of the other component should be greater than 100:1. After being combined with the adjustment frame, the polarizer can freely rotate around the center of the circle, and can be freely separated from the optical system. When reset, its polarization direction and its relative position with the optical path remain unchanged. During free rotation, the surface of the polarizer should be as vertical as possible to the axis of the microscope group in the signal acquisition module, and the included angle can be between 90±0.5°.

The camera in the signal acquisition module can be an EMCCD camera with a wide wavelength acquisition range, which can collect incident light with a wavelength within the visible wavelength range. Its combination with the microscope group should have a depth of field range, and the depth of field can be greater than 5mm.

The adjustable analyzer is a combination of a circular polarizer and an adjustment frame. The polarizer has a large aperture and can completely cover the field of view of the camera. When natural light passes through the polarizer, the ratio of the intensity of one of its orthogonally polarized components to the intensity of the other component should be greater than 100:1. After being combined with the adjustment frame, the polarizer can freely rotate around the center of the circle, and can be freely separated from the optical system. When reset, its polarization direction and its relative position with the optical path remain unchanged. During free rotation, the surface of the polarizer should be as perpendicular as possible to the axis of the microscope group in the signal acquisition module, preferably, the included angle is between 90±0.5°.

In step S102, the first sample transmission image data is processed to obtain transmission three-dimensional data.

In step S103, the first polarization-condition image data and the second polarization-condition image data are processed to obtain polarization-condition three-dimensional pre-data and a birefringent tissue region map.

In step S104, the birefringence tissue area map back-projects the polarization-condition three-dimensional pre-data to obtain polarization-condition three-dimensional data.

In step S105, the transmission three-dimensional data, the birefringent tissue area map and the polarization condition three-dimensional data are analyzed.

Further, the optical projection tomography system includes an adjustable polarizer and an adjustable analyzer, and the collecting the first image data through the optical projection tomography system includes:

When the polarization directions of the adjustable polarizer and the adjustable analyzer are perpendicular, acquiring the first polarization condition image data of the sample in the polarization direction;

When the polarization directions of the adjustable polarizer and the adjustable polarizer are perpendicular and rotated by a first angle, image data of the second polarization condition of the sample in the polarization direction is acquired, the second The polarization condition image data includes third polarization condition image data and fourth polarization condition image data.

Here, when the polarization directions of the adjustable polarizer and the adjustable analyzer are perpendicular, the vertical state is maintained throughout the acquisition process, specifically, the sample is rotated 360° around the sample axis and an image is acquired every 1° , a total of 360 images are collected, and first polarization condition image data P _1-i (i=1, 2, . . . , 360) of each sample rotation angle in this polarization direction are obtained.

When the polarization directions of the adjustable polarizer and the adjustable analyzer are vertical and rotated by a first angle, wherein the first angle may be 30°, and the vertical state is maintained throughout the acquisition process, the sample Rotate 360° around the sample axis, and collect an image every 1°, collect 360 images in total, and obtain the third polarization condition image data P _2-i (i=1) of each sample rotation angle in this polarization direction ,2,...,360).

When the polarization directions of the adjustable polarizer and the adjustable polarizer are vertical and rotated by a first angle, and the vertical state is maintained throughout the acquisition process, the sample is rotated 360° around the sample axis, and every Collect an image at an interval of 1°, collect 360 images in total, and obtain the fourth polarization condition image data P _3-i (i=1,2,...,360) of each sample rotation angle in this polarization direction .

Further, the collecting the first image data through the optical projection tomography system further includes:

Rotating the sample at intervals of a second angle around the sample axis, and acquiring transmission image data of the first sample corresponding to the second angle.

The adjustable polarizer and the adjustable analyzer are removed, the sample is rotated 360° around the sample axis, and an image is collected every second angle, which can be 1°, and a total of 360 images are collected, and each The first sample transmission image data I _Ti (i=1, 2, . . . , 360) of sample rotation angles.

Further, said processing said first sample transmission image data to obtain transmission three-dimensional data includes:

Composing the first sample transmission image data into a first sample transmission two-dimensional data set;

performing a logarithmic operation on the first sample transmission two-dimensional data set to obtain a second sample transmission two-dimensional data set;

The three-dimensional transmission data is obtained by performing three-dimensional reconstruction of filtered reflection shadows on the second sample transmission two-dimensional data set.

Here, the collected 360 pieces of first sample transmission image data I _Ti (i=1, 2, . . . , 360) are composed into the first sample transmission two-dimensional data set I _T . Logarithmic operation is performed on the first sample transmission two-dimensional data set to obtain the second sample transmission two-dimensional data set I _T ', and I _T ' is subjected to filtered back-projection three-dimensional reconstruction to obtain three-dimensional transmission data D _T .

Further, the processing of the first polarization-condition image data and the second polarization-condition image data to obtain polarization-condition three-dimensional pre-data and birefringent tissue region map includes:

acquiring a plurality of first polarization condition combined image data from the first polarization condition image data, the third polarization condition data and the fourth polarization condition data;

combining the plurality of first polarization condition combined image data into a second polarization condition two-dimensional data set;

Performing the filtered back projection three-dimensional reconstruction on the second polarization condition two-dimensional data set to obtain the polarization condition three-dimensional pre-data.

Here, a plurality of first polarization condition combination image data I _Pi is obtained from the first polarization condition image data P _1-i , the third polarization condition data P _2-i and the fourth polarization condition data P _3-i , and the A plurality of first polarization condition combined image data I _Pi is combined into a second polarization condition two-dimensional data set I _P , and the second polarization condition two-dimensional data set I _P is subjected to the filter back projection three-dimensional reconstruction to obtain the polarization condition three-dimensional pre-data D _P ^* .

Further, the acquiring a plurality of first polarization condition combined image data from the first polarization condition image data, the third polarization condition data and the fourth polarization condition data includes repeatedly executing the following processing until all The first polarization-conditioned image data, the third polarization-conditioned image data and the fourth polarization-conditioned image data have all been selected:

Select polarization condition image data respectively from the first polarization condition image data, the third polarization condition image data and the fourth polarization condition image data, and obtain the maximum gray value of the selected polarization condition image data at the same position pixel degree value;

Combining image data for a first polarization condition according to the maximum gray value combination.

Further, the processing of the first polarization condition image data and the second polarization condition image data to obtain the polarization condition three-dimensional pre-data and the birefringence tissue area map further includes:

performing threshold segmentation processing on the first polarization condition combination image data to obtain second polarization condition combination image data;

The image data combined with the second polarization condition is subjected to octane-neighborhood expansion processing to obtain the birefringent tissue region map.

Here, the first polarization condition combination image data _IPi is subjected to threshold value segmentation processing to obtain the second polarization condition combination image data, the threshold can be set as one-twentieth of the maximum intensity of the pixel in each picture, and the second polarization condition Combining the image data with eight-neighborhood expansion processing to obtain the birefringence tissue area map I _i (i=1,2,...,360) at each sample rotation angle, and using the i-th (i=1,2,. .., 360) birefringent tissue region maps I _i back-project the polarization condition three-dimensional pre-data D _P ^* according to the sample rotation angle i to obtain the polarization condition three-dimensional data D _P .

Further, the analyzing the transmission three-dimensional data, the birefringent tissue area map and the polarization condition three-dimensional data includes:

Visualize the three-dimensional data of the polarization condition by using a three-dimensional visualization method of volume rendering, and analyze the peripheral contour and texture features of the birefringent tissue;

The rendering results of the polarization condition three-dimensional data and the transmission three-dimensional data are fused by a volume rendering three-dimensional visualization method, and the distribution of the birefringent tissue in the sample and the position and shape relationship with other tissues are analyzed.

Here, volume rendering describes a technique that supports the visualization of three-dimensional data, volume rendering is a sampling function of three-dimensional space, and a technique for calculating two-dimensional visualization of colored translucent objects.

Specifically, the analysis of the three-dimensional data D _P of the polarization condition may use an appropriate three-dimensional visualization method to visualize the three-dimensional data. Analyze the peripheral contour and textural features of birefringent tissue by using volume rendering methods.

By analyzing the transmission 3D data D _P and the polarization condition 3D data D _T , perform appropriate volume rendering 3D visualization on them respectively, fuse the volume rendering results, and analyze the distribution of birefringent tissue in the sample and the position with other tissues and shape relationship.

Collect images P _i (i=1,2,...,360) by analyzing the polarization conditions, and sequentially investigate the polarization condition collection image group P of the rotation angle of the i (i=1,2,...,360) sample _i , compare the intensity of each pixel in P _1-i , P _2-i , and P _3-i , and obtain the sequence number of the image where each pixel in the sample area has the strongest intensity at the rotation angle of the sample, then the sample The direction of the fibers in the birefringent tissue projected on the radial plane of the camera at the pixel points with the same image number where the strongest intensity is located in the region is the same, so that the information about the fiber arrangement inside the sample can be roughly obtained.

Fig. 3 is a schematic diagram of image data collected by an optical projection tomography system under polarization conditions according to an embodiment of the present invention.

Referring to Fig. 3, with the diaphragm of a healthy nude mouse as a sample, when the polarization directions of the adjustable polarizer and the adjustable analyzer are vertical, the first polarization condition image data of the sample in the polarization direction is obtained; when the adjustable polarizer When it is perpendicular to the polarization direction of the adjustable analyzer and rotated by the first angle, the second polarization condition image data of the sample in the polarization direction is acquired, the second polarization condition image data includes the third polarization condition image data and the fourth polarization condition image data image data. Among them, FIG. 3( a ) is the image data of the first polarization condition, FIG. 3( b ) is the image data of the third polarization condition, and FIG. 3( c ) is the image data of the fourth polarization condition.

Fig. 4 is a synthesis diagram of polarization conditions of image data collected under polarization conditions provided by an embodiment of the present invention.

Referring to Fig. 4, from the first polarization condition image data, the 3rd polarization condition image data and the 4th polarization condition image data, obtain a plurality of first polarization condition combination image data; Combine a plurality of first polarization condition combination image data into the first Two-dimensional dataset for two polarization conditions.

Fig. 5 is a schematic diagram of two results of three-dimensional data visualization for polarization condition three-dimensional data provided by an embodiment of the present invention.

Referring to Figure 5, the stomach wall section of a healthy rat was used as a sample, and the obtained three-dimensional data of the polarization condition was visualized by the volume rendering three-dimensional visualization method, and the peripheral contour and texture characteristics of the birefringent tissue were analyzed.

Fig. 6 is a schematic diagram of the fusion of the rendering results of the polarization condition three-dimensional data and the transmission three-dimensional data provided by the embodiment of the present invention.

Referring to Figure 6, the gastric wall section of a healthy rat is used as a sample, and the obtained polarization condition 3D data and transmission 3D data are visualized by the volume rendering 3D visualization method, and the rendering results are fused, and the described The distribution of birefringent tissue in the sample and its positional and morphological relationship to other tissues.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (7)

1. A detection method for optical projection tomography, characterized in that the method comprises: collecting first image data by an optical projection tomography system, the first image data including first polarization condition image data, second polarization condition image data and first sample transmission image data; processing the transmission image data of the first sample to obtain transmission three-dimensional data; Processing the first polarization-condition image data and the second polarization-condition image data to obtain polarization-condition three-dimensional pre-data and a birefringent tissue region map; The birefringence tissue region map back-projects the polarization condition three-dimensional pre-data to obtain the polarization condition three-dimensional data; analyzing the transmission three-dimensional data, the birefringent tissue region map and the polarization condition three-dimensional data; The optical projection tomography system includes an adjustable polarizer and an adjustable analyzer, and the acquisition of the first image data through the optical projection tomography system includes: When the polarization directions of the adjustable polarizer and the adjustable analyzer are perpendicular, acquiring the first polarization condition image data of the sample in the polarization direction; When the polarization directions of the adjustable polarizer and the adjustable polarizer are perpendicular and rotated by a first angle, image data of the second polarization condition of the sample in the polarization direction is acquired, the second The polarization condition image data includes third polarization condition image data and fourth polarization condition image data. 2. The method according to claim 1, wherein said collecting the first image data by an optical projection tomography system further comprises: Rotating the sample at intervals of a second angle around the sample axis, and acquiring transmission image data of the first sample corresponding to the second angle. 3. The method according to claim 1, wherein said processing said first sample transmission image data to obtain transmission three-dimensional data comprises: Composing the first sample transmission image data into a first sample transmission two-dimensional data set; performing a logarithmic operation on the first sample transmission two-dimensional data set to obtain a second sample transmission two-dimensional data set; performing filtered backprojection three-dimensional reconstruction on the second sample transmission two-dimensional data set to obtain the transmission three-dimensional data. 4. The method according to claim 1, wherein the processing of the first polarization condition image data and the second polarization condition image data to obtain the polarization condition three-dimensional pre-data and birefringent tissue area map comprises: acquiring a plurality of first polarization condition combined image data from the first polarization condition image data, the third polarization condition image data and the fourth polarization condition image data; combining the plurality of first polarization condition combined image data into a second polarization condition two-dimensional data set; The second polarization-condition two-dimensional data set is subjected to filtered back-projection three-dimensional reconstruction to obtain the polarization condition three-dimensional pre-data. 5. The method according to claim 4, wherein said acquiring a plurality of first polarization condition image data from said first polarization condition image data, said third polarization condition image data and said fourth polarization condition image data Combining the image data with polarization conditions includes repeatedly performing the following processing until all the image data with the first polarization condition, the image data with the third polarization condition and the image data with the fourth polarization condition have been selected: Select polarization condition image data respectively from the first polarization condition image data, the third polarization condition image data and the fourth polarization condition image data, and obtain the maximum gray value of the selected polarization condition image data at the same position pixel degree value; Combining image data for a first polarization condition according to the maximum gray value combination. 6. The method according to claim 1, wherein the processing of the first polarization condition image data and the second polarization condition image data to obtain the polarization condition three-dimensional pre-data and birefringent tissue area map further comprises: performing threshold segmentation processing on the first polarization condition combination image data to obtain second polarization condition combination image data; The image data combined with the second polarization condition is subjected to octane-neighborhood expansion processing to obtain the birefringent tissue region map. 7. The method according to claim 1, wherein said analyzing said transmission three-dimensional data, birefringent tissue area map and said polarization condition three-dimensional data comprises: Visualize the three-dimensional data of the polarization condition by using a three-dimensional visualization method of volume rendering, and analyze the peripheral contour and texture features of the birefringent tissue; The rendering results of the polarization condition three-dimensional data and the transmission three-dimensional data are fused by a volume rendering three-dimensional visualization method, and the distribution of the birefringent tissue in the sample and the position and shape relationship with other tissues are analyzed.