CN-121971031-A - PS-OCT-based detection method for physiological and functional characteristics of dental hard tissue

CN121971031ACN 121971031 ACN121971031 ACN 121971031ACN-121971031-A

Abstract

The invention provides a method for detecting physiological and functional characteristics of dental hard tissue based on PS-OCT. The method comprises the steps of collecting interference signals of dental hard tissues by using a PS-OCT system, calculating complex amplitude of the PS-OCT interference signals, further calculating to obtain PS-OCT intensity images and various polarization images, calculating and outputting compactness parameters of the dental hard tissues based on PS-OCT phase delay images, calculating and outputting structure confusion parameters of the dental hard tissues based on PS-OCT optical axis images, and calculating and outputting depolarization parameters of the dental hard tissues based on PS-OCT polarization uniformity images. Compared with the prior art, the method has the advantages that the PS-OCT technology can be used for carrying out high-resolution and large-view-field imaging on the tooth tissue in real time without damage, and can obtain an intensity image and various polarization images simultaneously, and the physiological and functional characteristics of the tooth hard tissue are represented by various parameters.

Inventors

LIANG YANMEI
XU SONGWEN
YANG DI

Assignees

南开大学

Dates

Publication Date: 20260505
Application Date: 20241030

Claims (5)

1. The method for detecting the physiological and functional characteristics of the dental hard tissue based on the PS-OCT is characterized by utilizing the scattering and polarization state modulation results of the biological tissue on light to detect the physiological and functional characteristics of the dental hard tissue, and specifically comprises the following steps: Step 1, detecting dental hard tissue by using a polarization sensitive optical coherence tomography (PS-OCT) system to obtain two paths of PS-OCT interference signals I H and I V with mutually perpendicular polarization directions, wherein subscripts H and V respectively indicate that the polarization directions are in a horizontal direction and a vertical direction; Step 2, respectively calculating and outputting intensity images of the dental hard tissue corresponding to the two paths of dental hard tissue PS-OCT interference signals and a plurality of polarization images based on the two paths of dental hard tissue PS-OCT interference signals, wherein the plurality of polarization images comprise, but are not limited to, a phase delay image, an optical axis image and a polarization uniformity image; step 3, calculating and outputting density parameters of the dental hard tissue based on the PS-OCT phase delay image obtained in the step 2, wherein the density parameters are used for reflecting hardness characteristics of the dental hard tissue; Step 4, calculating and outputting a structural confusion parameter of the dental hard tissue based on the PS-OCT optical axis image obtained in the step 2, wherein the structural confusion parameter is used for reflecting the consistency of the dental hard tissue crystal structure; and 5, calculating and outputting depolarization parameters of the hard dental tissue based on the PS-OCT polarization uniformity image obtained in the step 2, wherein the depolarization parameters are used for reflecting the multiple scattering degree of the hard dental tissue.
2. The PS-OCT-based dental hard tissue physiological and functional feature detection method according to claim 1, wherein the specific calculation method of the intensity image and the multiple polarization images in step 2 is as follows: Step 2.1, sequentially performing background spectrum reduction, zero padding and inverse Fourier transformation on the two paths of PS-OCT interference signals I H and I V obtained in the step 1 to respectively obtain complex amplitudes corresponding to the PS-OCT interference signals And Expressed as: Wherein A and Representing the amplitude and phase of the complex amplitude, respectively; step 2.2, calculating a PS-OCT intensity image, a phase delay image, an optical axis image and a polarization uniformity image based on the complex amplitude, wherein the steps are respectively as follows: Wherein I is intensity, delta is phase delay, theta is optical axis, DOPU is polarization uniformity (Degree of Polarization Uniformity, DOPU), I is used for describing structural characteristics of dental hard tissue, delta is used for describing cumulative phase delay change from surface to detection depth of the dental hard tissue and reflecting double refraction size of the dental hard tissue, theta is used for describing cumulative optical axis change from surface to detection depth of the dental hard tissue and reflecting arrangement direction of crystal structure in the dental hard tissue, DOPU is used for describing overall polarization degree of the dental hard tissue in a selected window and reflecting depolarization characteristic of the dental hard tissue.
3. The PS-OCT-based dental hard tissue physiological and functional characteristic detection method according to claim 1, wherein the dental hard tissue density parameter in step 3 is specifically calculated by: step 3.1, dividing different areas of dental hard tissue in the PS-OCT phase delay image, extracting the numerical value of the phase delay image of each area, and obtaining a phase delay parameter; based on the phase delay parameters of the dental hard tissue, local density parameters of individual regions of the dental hard tissue are calculated, including but not limited to, the phase delayed region mean parameters The specific calculation steps are as follows: Wherein the method comprises the steps of The regional mean value parameter representing the phase delay reflects the local hardness characteristics of dental hard tissue in each region, m represents the mth pixel point of the region, delta m represents the phase delay value of the mth pixel point in the region, and n represents the total number of pixels dividing the region; Step 3.2, based on the PS-OCT phase delay parameters obtained in step 3.1, dividing the image into a high hardness region and a low hardness region using a selected threshold, and calculating overall density parameters of the dental hard tissue, including but not limited to, width parameters of the high hardness region and normalized area parameters of the high hardness region, specifically including the following steps: h=P t -P e Wherein h is a width parameter of a high-hardness region, P t is a boundary position of the high-hardness region and the low-hardness region which are distinguished by using a threshold value, P e is an edge position of a dental hard tissue, T is a normalized area parameter of the high-hardness region, S H is an area of the high-hardness region, S L is an area of the low-hardness region, h represents a distance from the edge of the high-hardness region to the edge of the dental hard tissue, which is determined according to the threshold value, in the dental hard tissue, T represents a proportion of the area of the high-hardness region to the total area of the dental hard tissue, and the two jointly reflect the overall hardness characteristics of the dental hard tissue.
4. The PS-OCT-based dental hard tissue physiological and functional feature detection method according to claim 1, wherein the dental hard tissue structure disorder parameter in step 4 is specifically calculated by: dividing different areas of dental hard tissue in the PS-OCT optical axis image, extracting the numerical value of the optical axis image of each area, and obtaining the optical axis parameter; Based on the optical axis parameters of the dental hard tissue, local structure confusion parameters of each area of the dental hard tissue are calculated, including but not limited to an area standard deviation parameter sigma θ of the optical axis, and the specific calculation steps are as follows: Wherein sigma θ represents the regional standard deviation parameter of the optical axis, reflects the consistency characteristic of the crystal structure of the dental hard tissue in each region, The average value of the area representing the optical axis parameter, θ m represents the optical axis value of the mth pixel point in the area, n represents the total number of pixels dividing the area, and m represents the mth pixel point of the area.
5. The method for detecting physiological and functional characteristics of dental hard tissue based on PS-OCT according to claim 1, wherein the depolarization parameters of the dental hard tissue in step 5 are specifically calculated by: Dividing different areas of dental hard tissue in the PS-OCT polarization uniformity image, extracting the numerical value of the polarization uniformity image of each area, and obtaining the polarization uniformity parameter; Calculating local depolarization parameters for various regions of the dental hard tissue based on polarization uniformity parameters of the dental hard tissue, including but not limited to, region mean parameters of polarization uniformity The specific calculation steps are as follows: Wherein the method comprises the steps of The region mean value parameter representing the polarization uniformity reflects the multiple scattering degree of dental hard tissue in each region, x DOPUm represents the polarization uniformity value of the mth pixel point in the region, n represents the total number of pixels dividing the region, and m represents the mth pixel point in the region.

Description

PS-OCT-based detection method for physiological and functional characteristics of dental hard tissue Technical Field The invention belongs to the technical field of polarization-sensitive optical coherence tomography, and particularly relates to a detection method of physiological and functional characteristics of dental hard tissue based on PS-OCT. Background Oral health problems have been a major concern for society. Oral tissue includes hard dental tissue, i.e., the development and health of teeth, which is directly related to the quality of life of people, and mucosal tissue such as lips, cheeks, palates, and the like. Common diseases include caries, periodontitis, pulpitis, and the like. These diseases severely affect the quality of life of people, for example caries often causes inflammation at the tip etc. of the tooth, and there is a local swelling and the possible cause of septicemia or bacteremia. Therefore, a solution for detecting physiological and functional characteristics of dental hard tissue is needed to achieve early diagnosis of diseases. The main detection means of dental diseases are currently visual detection, however, the detection is highly dependent on the experience of doctors, and lesions usually occur in the interior of teeth at early stages and cannot be identified from the tooth appearance, and the other method is to image hard tissues of the tooth body by using an X-ray technology, which can provide structural characteristics of the tooth body, but the low-resolution X-ray imaging technology cannot find early lesions. While high resolution X-ray micro-CT imaging techniques have a resolution on the order of microns, in-vivo dental detection is not possible due to the high radioactive contamination. As a non-invasive, high resolution, non-contact imaging technique, optical coherence tomography (Optical Coherence Tomography, OCT) has become a routine diagnostic technique for ophthalmology. The polarization technology can obtain more functional information in the tissue compared with the structural information by detecting the change of the polarization state of the light after being reflected or scattered by the biological tissue. On the basis of obtaining tissue structure information, polarization sensitive OCT (Polarization sensitive OCT, PS-OCT) combined with a polarization technology can obtain more information of dental hard tissue by analyzing the polarization characteristics of a sample. For example, tooth enamel is an anisotropic crystal material, and the crystal structure of the anisotropic crystal material enables light to pass through the anisotropic crystal material to generate a double refraction phenomenon, and the double refraction phenomenon not only can reveal the crystal arrangement mode and internal structural characteristics of the tooth enamel, but also provides a new visual angle for researching biological characteristics and pathological changes of the tooth. The crystal structure of the normal dental hard tissue is orderly arranged, and the birefringence property is obvious. When a hard dental tissue is diseased such as caries, the hydroxyapatite crystal structure in enamel is destroyed, and the internal air or liquid component is increased, resulting in a change in its birefringent form, i.e., a change in the density of the hard dental tissue, disorder of the internal crystal structure arrangement, and depolarization characteristics. Therefore, PS-OCT can be used as a polarization imaging mode, and the change of physiological and functional characteristics of the pathological change process of the dental hard tissue can be well observed. For example, the phase retardation (δ) describes the magnitude of birefringence of the hard dental tissue, characterizes the degree of densification of the internal crystal structure arrangement, reflects the hardness of the hard dental tissue, the optical axis (θ) describes the direction of the optical axis of the hard dental tissue, indicates the direction of the arrangement of the internal crystal structure, and the polarization uniformity (Degree ofPolarization Uniformity, DOPU) describes the depolarization characteristics of the hard dental tissue, characterizes the degree of multiple scattering of light within the tissue. It has been found that caries lesions cause a strong change of DOPU and caries lesions (Jonas Golde,Florian Tetschke,Julia Walther,Tobias Rosenauer D.D.S.,Franz Hempel,Christian Hannig D.D.S.,Edmund Koch,Lars Kirsten,"Detection of carious lesions utilizing depolarization imaging by polarization sensitive optical coherence tomography,"J.Biomed.Opt.23(7)071203(2018)), are detected using DOPU as a parameter, whereas this method detects caries lesions using only DOPU one parameter, making it difficult to describe the physiological and functional characteristics of hard dental tissue in more detail. At present, the information of PS-OCT images still needs to be fully mined, and the physiological and fun