Low-frequency modulation type intraoperative parathyroid gland tissue identification method and system

Abstract

The invention discloses a low-frequency modulation type intraoperative parathyroid gland tissue recognition method and system. The method comprises the steps that the regional position of suspected parathyroid gland tissue is determined; exciting light emitted by the laser control unit is modulated, and then a secondary throwing probe is used for conducting fluorescence excitation on the area position of the suspected parathyroid gland tissue; the secondary throwing probe is used for receiving a fluorescence signal generated by the regional position, and the fluorescence signal is amplified after being converted through a photomultiplier; and the amplified fluorescence signal is analyzed by using a demodulation module, so that the parathyroid gland tissue is identified. The interference of the background light is effectively removed in a double-demodulation mode of phase-locked demodulation and Fourier transform demodulation, the adaptability of the system to complex background interference is further improved, the real-time performance and the complexity processing capacity are considered at the same time, and the flexibility and sensitivity of the system are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of medical detection and tissue identification, and in particular to a method and system for identifying parathyroid tissue during low-frequency modulation surgery. Background Art

[0002] The parathyroid glands are key organs regulating calcium metabolism in the human body. Their location is hidden and difficult to distinguish from surrounding tissue. During thyroid surgery, misdirected or missed parathyroidectomy is a major risk, often leading to postoperative hypocalcemia and calcium metabolism disorders, requiring lifelong calcium and vitamin D supplements. Furthermore, it can cause permanent hypoparathyroidism, leading to difficult recovery and decreased quality of life. Therefore, rapid and accurate identification of parathyroid tissue during surgery is crucial for reducing surgical risk and improving surgical quality.

[0003] In the existing technology, nanocarbon and methylene blue are often used for development, and the parathyroid glands are positively or negatively developed by injecting developer to achieve tissue identification. However, the above method is complicated and time-consuming to operate, and the injection of developer may cause chemical stimulation to the thyroid tissue, and it is impossible to monitor the functional status of the tissue in real time. Near-infrared technology can identify parathyroid tissue in real time during surgery, significantly improving the recognition rate of parathyroid tissue, especially in cases where it is difficult to detect with the naked eye. At present, the parathyroid tissue identification methods developed for this technology mainly include infrared fluorescence imaging and fluorescence spectroscopy detection. Among them, infrared fluorescence imaging is easily interfered by ambient light, so the operating room lights usually need to be turned off during surgery, making it difficult for the surgeon to accurately locate the position of the parathyroid gland based on the fluorescence image. In the process of fluorescence spectroscopy detection, the scattered signal generated by the excitation light during long-distance optical fiber transmission is consistent with the frequency of the target fluorescence signal and is difficult to remove.

[0004] Therefore, how to quickly and accurately achieve precise identification of parathyroid tissue is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In order to solve the above technical problems, this application proposes the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a method for identifying parathyroid tissue during low-frequency modulation surgery, comprising:

[0007] Locate the area of ​​suspected parathyroid tissue;

[0008] The excitation light emitted by the laser control unit is modulated and then used to excite fluorescence at the area suspected of parathyroid tissue through the sub-throw probe;

[0009] Utilizing the secondary probe to receive the fluorescent signal generated at the position of the region and converting and amplifying the fluorescent signal through a photomultiplier tube;

[0010] The demodulation module is used to analyze the amplified fluorescence signal to identify the parathyroid tissue.

[0011] In one possible implementation, the step of modulating the excitation light emitted by the laser control unit and then performing fluorescence excitation on the suspected parathyroid tissue region through the sub-throw probe includes:

[0012] The excitation light emitted by the laser control unit is input into the optical chopper for modulation;

[0013] The modulated excitation light is irradiated to the area suspected to be the parathyroid tissue through the sub-shot probe, inducing the suspected parathyroid tissue to generate autofluorescence signals.

[0014] In one possible implementation, the excitation light emitted by the laser control unit is input into the optical chopper for modulation using the following calculation formula:

[0015] I 激发 (t)=I0·sin(2πft)

[0016]

[0017] Among them, I 激发 (t) is the intensity of the modulated excitation light, I0 is the initial intensity of the excitation light, and f is the modulation frequency.

[0018] In a possible implementation, the fluorescent signal generated by the sub-throw probe at the position of the region is received, and the fluorescent signal is converted and amplified by a photomultiplier tube, including:

[0019] receiving a fluorescent signal generated at the position of the region by a secondary probe, wherein the fluorescent signal includes a parathyroid tissue fluorescent signal and a background light signal;

[0020] The fluorescent signal is converted into an electrical signal using a photomultiplier tube and then the electrical signal is amplified.

[0021] In a possible implementation, analyzing the amplified fluorescence signal using a demodulation module to identify parathyroid tissue includes:

[0022] Determining a demodulation mode according to background interference, wherein the demodulation mode includes phase-locked demodulation and Fourier transform demodulation;

[0023] Phase-locked demodulation or Fourier transform demodulation is used to demodulate the amplified fluorescence signal to achieve identification of parathyroid tissue.

[0024] In one possible implementation, a phase-locked demodulation method is used to demodulate the amplified fluorescence signal to identify the parathyroid tissue, including:

[0025] Obtain a reference signal with the same frequency as the parathyroid tissue fluorescence signal. The expression of the reference signal is:

[0026] S ― Ref(t) = A0·sin(2π·flt+φ3);

[0027] The fluorescence signal is multiplied by the reference signal to perform mixing processing to obtain a mixed signal, and the expression of the mixed signal is:

[0028] I ― Mixing(t) = (A1 sin(2π f1 t + φ1) + A2 sin(2π f2 t + φ2)) A0 sin(2π f1 t + φ3), where A1, f1, and φ1 are the amplitude, frequency, and phase of the parathyroid tissue fluorescence signal, respectively; A2, f2, and φ2 are the amplitude, frequency, and phase of the background light signal, respectively; and A0 and φ3 are the amplitude and phase of the reference signal, respectively.

[0029] removing the frequency-doubled signal and the high-frequency signal from the mixed signal by low-pass filtering to extract the parathyroid tissue fluorescence signal;

[0030] The parathyroid tissue is identified and located based on the extracted fluorescence signal of the parathyroid tissue combined with a demodulation algorithm.

[0031] In one possible implementation, Fourier transform demodulation is used to demodulate the amplified fluorescence signal to identify parathyroid tissue, including:

[0032] The amplified fluorescence signal is subjected to Fourier transform, and the calculation formula is:

[0033]

[0034] Spectral analysis was used to identify specific frequency components associated with parathyroid tissue;

[0035] Based on the identified specific frequency components and combined with the demodulation algorithm, the parathyroid tissue can be identified and located.

[0036] In a second aspect, an embodiment of the present application provides a low-frequency modulation intraoperative parathyroid tissue identification system, comprising: an embedded mainboard and a laser control unit, a motor control unit, a demodulation module, a detection handle, and a display and alarm module electrically connected to the embedded mainboard, wherein the output end of the laser control unit is electrically connected to an optical chopper, and a sub-throw probe is provided at the detection handle;

[0037] The laser control unit is used to adjust the characteristics of the laser according to different diagnostic requirements;

[0038] The motor control unit is used to adjust the position of the laser source or the sub-throw probe to ensure that the excitation light can accurately irradiate the suspected parathyroid tissue area;

[0039] The demodulation module is used to demodulate the fluorescent signal reflected from the suspected parathyroid tissue area to extract the unique fluorescent signal of the parathyroid tissue;

[0040] The optical chopper is used to periodically modulate the excitation light;

[0041] The sub-throw probe is used to contact the surgical area to receive the reflection or fluorescence signal, and transmit it back to the photomultiplier tube through the optical fiber transmission line;

[0042] The photomultiplier tube is used to convert and amplify the reflected fluorescent signal;

[0043] The display and alarm module is used to display the fluorescence signal intensity in real time and trigger an audible and visual alarm when the signal is abnormal.

[0044] In one possible implementation, the display and alarm module includes: an LCD screen and an audible and visual alarm unit, wherein the LCD screen is used to dynamically display the fluorescence signal intensity curve and real-time numerical value; the audible and visual alarm unit is used to trigger an alarm when the signal intensity is lower than a preset threshold or exceeds a safe range.

[0045] In a possible implementation, an optical component is integrated in the detection handle, and the optical component includes a collimating lens group, a filter, a dichroic mirror, and a detector interface.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] This application uses a pre-optical path design to embed the optical elements for laser modulation and fluorescence signal collection into the detection handle, reducing the Raman scattering background caused by long-distance transmission of the excitation light, improving the purity of the fluorescence signal, and effectively reducing the interference of ambient light and background light on the target signal.

[0048] This application effectively removes the interference of background light through dual demodulation of phase-locked demodulation and Fourier transform demodulation, further improving the system's adaptability to complex background interference, while taking into account real-time and complexity processing capabilities, and enhancing the flexibility and sensitivity of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic flow chart of a low-frequency modulation intraoperative parathyroid tissue identification method provided in an embodiment of the present application;

[0050] Figure 2 Schematic diagram of fluorescence extraction based on phase-locked demodulation method to filter out environmental interference provided in an embodiment of the present application;

[0051] Figure 3 Schematic diagram of fluorescence extraction based on Fourier transform demodulation method to filter out environmental interference provided in an embodiment of the present application;

[0052] Figure 4 This is a schematic diagram of a low-frequency modulation intraoperative parathyroid tissue identification system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] The present invention will be described below with reference to the accompanying drawings and specific implementation methods.

[0054] Figure 1 This is a flow chart of a low-frequency modulation intraoperative parathyroid tissue identification method provided in an embodiment of the present application, see Figure 1 In this embodiment, a low-frequency modulation method for identifying parathyroid tissue during surgery includes:

[0055] S101, determining the location of the suspected parathyroid tissue region.

[0056] In this embodiment, since the location of parathyroid tissue is hidden and difficult to distinguish from surrounding tissues, in order to avoid mis-resection or omission of the parathyroid gland, the locations of multiple areas of suspected parathyroid tissue are determined based on the doctor's own experience and professional knowledge before surgical resection.

[0057] S102, modulating the excitation light emitted by the laser control unit and then performing fluorescence excitation on the area suspected to be the parathyroid tissue through the sub-throw probe.

[0058] In this embodiment, the laser control unit emits 785nm wavelength excitation light, which is passed through the sub-throw probe to stimulate fluorescence in the area of ​​suspected parathyroid tissue, inducing the suspected parathyroid tissue to produce an autofluorescence signal. During this process, an optical chopper is used to modulate the excitation light, giving the fluorescence signal a modulation frequency characteristic. After the original excitation light passes through the optical chopper, it is cut into a sinusoidal signal of a specific frequency. The modulation frequency is determined by the optical chopper rotation speed and the number of holes, and is calculated as follows:

[0059]

[0060] The modulated excitation light intensity can be expressed as:

[0061] I 激发 (t)=I0·sin(2πft)

[0062] Among them, I 激发 (t) is the intensity of the modulated excitation light, I0 is the initial intensity of the excitation light, and f is the modulation frequency.

[0063] S103: Receive the fluorescence signal generated by the secondary probe at the position of the region and convert and amplify the fluorescence signal through a photomultiplier tube.

[0064] In this embodiment, a single-shot probe receives a fluorescent signal generated by a suspected parathyroid tissue area, and preliminary signal processing is performed within the detection handle. The fluorescent signal is a superposition of the parathyroid tissue fluorescence signal and the background light signal. A photomultiplier tube converts the reflected weak fluorescent signal into an electrical signal, which is then amplified.

[0065] S104: Analyze the amplified fluorescence signal using a demodulation module to identify the parathyroid tissue.

[0066] In this embodiment, the demodulation method is determined based on the background interference, and the demodulation methods include phase-locked demodulation and Fourier transform demodulation. Among them, phase-locked demodulation is used to demodulate the amplified fluorescence signal to achieve the identification of parathyroid tissue, including:

[0067] A reference signal with the same frequency as the parathyroid tissue fluorescence signal is obtained, and the modulation frequency signal is quickly extracted in real time by multiplying the reference signal and the target signal and low-pass filtering.

[0068] See also Figure 2In this embodiment, it is assumed that the parathyroid tissue fluorescence signal is: A1sin(2π·f1·t+φ1), with a frequency of f1, an amplitude of A1, and a phase of φ1; the background interference signal is: A2·sin(2π·f2t+φ2), with a frequency of f2, an amplitude of A2, and a phase of φ2; and the reference signal is: A0sin(2π·fl·t+φ3), with a frequency of f1, an amplitude of A0, and a phase of φ3 (which is consistent with the frequency of the parathyroid tissue fluorescence signal);

[0069] The received fluorescence signal is composed of the superposition of the parathyroid tissue fluorescence signal and the background signal:

[0070] I ― Fluorescence (t)=A1·sin(2π·flt+φ1)+A2·sin(2π·f2·t+φ2)

[0071] The form of the reference signal is consistent with the modulation frequency f1 of the parathyroid tissue fluorescence signal, expressed as:

[0072] S ― Reference(t) = A0·sin(2π·flt+φ3)

[0073] The received fluorescence signal I ― Fluorescence (t) and reference signal S ― The mixing operation is performed by multiplying the reference (t) and the resulting mixed signal is:

[0074] I ― Mixing(t) = I ― Fluorescence (t)·S ― Refer to (t). Substitute the specific signal expression:

[0075] I ― Mixing (t)=(A1·sin(2π·f1·t+φ1)+A2·sin(2π·f2·t+φ2))·A0·sin(2π·f1·t+φ3)

[0076] After simplification, we get:

[0077] A1sin(2πflt+φ1)sin(2πflt+φ3)=(1 / 2)A1[cos(φ1―φ3)―cos(4πflt+φ1+φ3)]

[0078] After the background signal A2 is removed by mixing and then passes through a low-pass filter, only the DC part of the target signal remains.

[0079] A _甲状旁腺组织荧光 =(1 / 2)A0A1cos(φ1―φ3)

[0080] The parathyroid tissue is identified and located based on the extracted fluorescence signal of the parathyroid tissue combined with a demodulation algorithm.

[0081] See also Figure 3 In this embodiment, the amplified fluorescence signal is demodulated by Fourier transform demodulation to realize the identification of parathyroid tissue, including:

[0082] The fluorescence signal usually includes a fluorescence signal specific to the parathyroid tissue, a background signal (fluorescence signal from other tissues or background), and possible noise. The amplified fluorescence signal is used as the original signal, and the collected time domain signal can be converted into a frequency domain signal through Fourier transform. Since the fluorescence signal of the parathyroid tissue has a specific frequency characteristic (frequency f1), while the signals of other tissues or background have different frequency components. After using Fourier transform, specific frequency components related to the parathyroid gland can be identified in the spectrum. In this embodiment, by finding the frequency peak corresponding to the frequency of the parathyroid fluorescence signal, the parathyroid gland signal can be separated from the overall signal, while the background signal (for example, frequency f2) can be suppressed. The above method helps doctors monitor the position of the parathyroid gland in real time during surgery, thereby avoiding damage.

[0083] Corresponding to the low-frequency modulation intraoperative parathyroid tissue identification method provided in the above embodiment, the present application also provides an embodiment of a low-frequency modulation intraoperative parathyroid tissue identification system.

[0084] See also Figure 4The embodiment of the present application provides a low-frequency modulation type intraoperative parathyroid tissue identification system, comprising: an embedded mainboard and a laser control unit, a motor control unit, a demodulation module, a detection handle and a display and alarm module electrically connected to the embedded mainboard, wherein the output end of the laser control unit is electrically connected to the optical chopper, and a sub-throw probe is provided at the detection handle. The laser control unit is used to manage the switching, power adjustment and wavelength control of the laser. It ensures that the excitation light signal has an appropriate output intensity and wavelength to meet the needs of parathyroid identification. The laser control unit can adjust the characteristics of the laser according to different diagnostic requirements. The motor control unit is responsible for frequency calculation to provide a reference signal such as a phase-locked demodulation method, and controls the modulation module for accurate excitation and collection of tissue fluorescence. The modulation module is used to adjust the frequency, intensity or other characteristics of the laser signal. An optical component is integrated in the detection handle, and the optical component includes a collimating lens group, a filter, a dichroic mirror and a detector interface. The single-shot probe contacts the surgical area to receive fluorescence signals, which are then transmitted back to a photomultiplier tube (PMT) via a fiber optic transmission line. The PMT converts and amplifies the reflected fluorescence signals. The display and alarm module displays the fluorescence signal intensity in real time and triggers an audible and visual alarm if the signal is abnormal. The display and alarm module includes an LCD screen that dynamically displays the fluorescence signal intensity curve and real-time values, and an audible and visual alarm unit that triggers an alarm if the signal intensity falls below a preset threshold or exceeds a safe range.

[0085] The A / D converter module is also included. It converts the analog signal received from the detector into a digital signal for further processing by the embedded motherboard and computer. This process ensures accurate signal transmission and avoids signal loss during transmission.

[0086] When the system is powered on, the embedded mainboard activates each submodule via the control panel. The operator sets laser parameters such as wavelength, power, and scanning frequency on the mainboard display. Based on the parathyroid gland characteristics to be detected, the operator also enters relevant parameters (such as laser power and frequency) through the system setup interface. These parameters are transmitted to the corresponding control module for adjustment of the laser and probe. Once the laser control unit is activated, the laser begins operating at the set wavelength and power, ensuring that the laser beam intensity and frequency meet the requirements for parathyroid gland identification. The laser control unit allows the system to adjust the laser output in real time. The laser signal is modulated by the modulation module, allowing the system to adjust the laser frequency and intensity based on different tissue response characteristics. The motor control unit controls the motor or servo within the system, ensuring a stable laser source flash frequency. When the laser signal strikes the target area (such as the parathyroid gland), it is reflected or scattered. The reflected light signal is received by a photomultiplier tube, which converts the weak optical signal into an electrical signal and amplifies it. After amplification by the photomultiplier tube, the demodulation module begins processing the received signal, removing background noise and extracting the useful signal. Through demodulation, the system extracts characteristic signals reflecting parathyroid tissue, effectively improving diagnostic accuracy. The demodulated analog signal is fed into the A / D conversion module, which converts it into a digital signal for further processing by the embedded motherboard and computer. This digital signal conversion ensures accurate signal transmission during subsequent processing and prevents signal loss. The embedded motherboard receives the A / D-converted digital signal and performs real-time analysis. By comparing it with known characteristics of parathyroid tissue, the system determines whether the area is a parathyroid gland and provides visual feedback to the operator. The analysis results are displayed in real time on a monitor connected to the embedded motherboard, allowing the operator to see the location of the parathyroid gland and related signal characteristics. The system also automatically generates a test report based on the analysis results, including the parathyroid gland diagnosis conclusion and relevant parameters. Throughout the process, the operator monitors the system's real-time operating status through the display interface, allowing real-time adjustments to the laser intensity, frequency, and probe position to ensure optimal system operation.

[0087] In the embodiments of this application, "multiple" refers to two or more. "And / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean that A exists alone, A and B exist simultaneously, or B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0088] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0089] The above description is merely a specific embodiment of the present application. Any person skilled in the art may easily conceive of variations or substitutions within the technical scope disclosed in this application, and such variations or substitutions shall be within the scope of protection of this application. The scope of protection of this application shall be subject to the scope of protection of the claims.

Claims

1. A method for identifying parathyroid tissue during low-frequency modulation surgery, characterized in that: include: Locate the area of ​​suspected parathyroid tissue; The excitation light emitted by the laser control unit is modulated and then used to excite fluorescence at the area suspected of parathyroid tissue through the sub-throw probe; Utilizing the secondary probe to receive the fluorescent signal generated at the position of the region and converting and amplifying the fluorescent signal through a photomultiplier tube; The demodulation module is used to analyze the amplified fluorescence signal to identify the parathyroid tissue.

2. The method for identifying parathyroid tissue during low-frequency modulation surgery according to claim 1, characterized in that: The method of modulating the excitation light emitted by the laser control unit and then performing fluorescence excitation on the area of ​​suspected parathyroid tissue through the sub-throw probe comprises: The excitation light emitted by the laser control unit is input into the optical chopper for modulation; The modulated excitation light is irradiated to the area suspected to be the parathyroid tissue through the sub-shot probe, inducing the suspected parathyroid tissue to generate autofluorescence signals.

3. The method for identifying parathyroid tissue during low-frequency modulation surgery according to claim 2, characterized in that: The calculation formula for inputting the excitation light emitted by the laser control unit into the optical chopper for modulation is: I 激发 (t)=I0·sin(2πft) Among them, I 激发 (t) is the intensity of the modulated excitation light, I0 is the initial intensity of the excitation light, and f is the modulation frequency.

4. The method for identifying parathyroid tissue during low-frequency modulation surgery according to claim 1, characterized in that: The fluorescent signal generated by the sub-throw probe at the position of the region is received, and the fluorescent signal is converted and amplified by a photomultiplier tube, including: receiving a fluorescent signal generated at the position of the region by a secondary probe, wherein the fluorescent signal includes a parathyroid tissue fluorescent signal and a background light signal; The fluorescent signal is converted into an electrical signal using a photomultiplier tube and then the electrical signal is amplified.

5. The method for identifying parathyroid tissue during low-frequency modulation surgery according to claim 1, characterized in that: The demodulation module is used to analyze the amplified fluorescence signal to identify the parathyroid tissue, including: Determining a demodulation mode according to background interference, wherein the demodulation mode includes phase-locked demodulation and Fourier transform demodulation; Phase-locked demodulation or Fourier transform demodulation is used to demodulate the amplified fluorescence signal to achieve identification of parathyroid tissue.

6. The method for identifying parathyroid tissue during low-frequency modulation surgery according to claim 5, characterized in that: Phase-locked demodulation is used to demodulate the amplified fluorescence signal to identify parathyroid tissue, including: Obtain a reference signal with the same frequency as the parathyroid tissue fluorescence signal. The expression of the reference signal is: S ― Ref(t) = A0·sin(2π·flt+φ3); The fluorescence signal is multiplied by the reference signal to perform mixing processing to obtain a mixed signal, and the expression of the mixed signal is: I ― Mixing(t) = (A1 sin(2π f1 t + φ1) + A2 sin(2π f2 t + φ2)) A0 sin(2π f1 t + φ3), where A1, f1, and φ1 are the amplitude, frequency, and phase of the parathyroid tissue fluorescence signal, respectively; A2, f2, and φ2 are the amplitude, frequency, and phase of the background light signal, respectively; and A0 and φ3 are the amplitude and phase of the reference signal, respectively. removing the frequency-doubled signal and the high-frequency signal from the mixed signal by low-pass filtering to extract the parathyroid tissue fluorescence signal; The parathyroid tissue is identified and located based on the extracted fluorescence signal of the parathyroid tissue combined with a demodulation algorithm.

7. The method for identifying parathyroid tissue during low-frequency modulation surgery according to claim 5, characterized in that: The amplified fluorescence signal is demodulated using Fourier transform demodulation to identify parathyroid tissue, including: The amplified fluorescence signal is subjected to Fourier transform, and the calculation formula is: Spectral analysis was used to identify specific frequency components associated with parathyroid tissue; Based on the identified specific frequency components and combined with the demodulation algorithm, the parathyroid tissue can be identified and located.

8. A low-frequency modulation intraoperative parathyroid tissue identification system, based on the low-frequency modulation intraoperative parathyroid tissue identification method according to any one of claims 1 to 7, characterized in that: include: An embedded mainboard and a laser control unit, a motor control unit, a demodulation module, a detection handle, and a display and alarm module electrically connected to the embedded mainboard, wherein the output end of the laser control unit is electrically connected to the optical chopper, and a secondary probe is provided at the detection handle; The laser control unit is used to adjust the characteristics of the laser according to different diagnostic requirements; The motor control unit is used to adjust the position of the laser source or the sub-throw probe to ensure that the excitation light can accurately irradiate the suspected parathyroid tissue area; The demodulation module is used to demodulate the fluorescent signal reflected from the suspected parathyroid tissue area to extract the unique fluorescent signal of the parathyroid tissue; The optical chopper is used to periodically modulate the excitation light; The sub-throw probe is used to contact the surgical area to receive the reflection or fluorescence signal, and transmit it back to the photomultiplier tube through the optical fiber transmission line; The photomultiplier tube is used to convert and amplify the reflected fluorescent signal; The display and alarm module is used to display the fluorescence signal intensity in real time and trigger an audible and visual alarm when the signal is abnormal.

9. The low-frequency modulation intraoperative parathyroid tissue identification system according to claim 8, characterized in that: The display and alarm module includes: an LCD screen and an audible and visual alarm unit. The LCD screen is used to dynamically display the fluorescence signal intensity curve and real-time numerical value; the audible and visual alarm unit is used to trigger an alarm when the signal intensity is lower than a preset threshold or exceeds a safe range.

10. The low-frequency modulation intraoperative parathyroid tissue identification system according to claim 8, characterized in that: An optical component is integrated in the detection handle, and the optical component includes a collimating lens group, a filter, a dichroic mirror and a detector interface.

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