Ultra-wideband terahertz imaging system and imaging method

Abstract

The application discloses an ultra-wideband terahertz imaging system and an imaging method, which comprises a terahertz wave generator for generating continuous ultra-wideband terahertz signals; a terahertz biological signal receiver, a receiving antenna of which can be adjusted in vertical height, for detecting an electromagnetic field around a tissue organ to obtain a scattered field; a terahertz biological signal processor for carrying out multi-dimensional image reconstruction on the detected scattered field to obtain a multi-dimensional image of the tissue organ; and an image display for displaying the multi-dimensional image of the tissue organ. The three-dimensional holographic terahertz imaging system can reconstruct a two-dimensional or three-dimensional image of the tissue organ, and is non-contact and non-invasive, and does not need to paste any detector on the tissue organ. According to the imaging method, corresponding medical instruments can be developed, and corresponding curves, images and numerical values can be displayed, so that a plurality of diseases such as breast cancer and skin cancer can be continuously monitored.

Description

Technical Field

[0001] This invention relates to the field of terahertz imaging, and in particular to an ultra-wideband terahertz imaging system and imaging method. Background Technology

[0002] Breast cancer is the leading cause of cancer death among women worldwide. Early detection and treatment can effectively reduce breast cancer mortality, but its incidence has increased over the past 30 years. Early diagnosis is key to improving five-year survival rates. Mammography is considered the gold standard for routine breast cancer detection, but it involves ionizing radiation, posing a potential risk to patients and is unsuitable for women with dense breasts or pregnant women. Ultrasound image quality is relatively low, and distinguishing early malignant tissue from normal tissue is challenging. MRI is the most sensitive method for detecting breast cancer, but it is expensive, cannot accurately locate the breast, and may lead to misdiagnosis. Traditional imaging methods often result in errors and limitations in cancer detection, prompting researchers to develop new cancer diagnostic methods.

[0003] Compared to conventional breast cancer detection techniques, terahertz breast imaging, with its advantages of being non-invasive, non-contact, non-ionizing radiation-free, high-contrast, and easy to screen, holds promise as a safe and effective routine or adjunctive method for breast tumor detection, attracting widespread attention from scholars both domestically and internationally. However, current terahertz imaging technology faces challenges such as long scanning times and poor image quality, hindering its widespread adoption. Summary of the Invention

[0004] In order to solve the technical problems of terahertz imaging technology in the prior art, the present invention proposes an ultra-wideband terahertz imaging system and imaging method.

[0005] The technical solution adopted in this invention is:

[0006] This invention proposes an ultra-wideband terahertz imaging system, comprising:

[0007] Terahertz wave generator, used to generate continuous ultra-wideband terahertz signals;

[0008] A terahertz signal transmitter, used to transmit ultra-wideband terahertz signals generated by the terahertz wave generator to tissues and organs;

[0009] Terahertz biosignal receivers have adjustable vertical antennas for detecting electromagnetic fields around tissues and organs and acquiring scattered electric fields.

[0010] The terahertz biosignal processor reconstructs the detected scattered electric field to obtain multidimensional images of tissues and organs.

[0011] Image display for showing multidimensional images of tissues and organs;

[0012] The intelligent scanning controller connects to and controls the terahertz wave generator, terahertz signal transmitter, terahertz biosignal receiver, image display, and terahertz biosignal processor.

[0013] Specifically, the terahertz signal transmitter includes at least one transmitting antenna, and the terahertz biosignal receiver includes at least one receiving antenna.

[0014] Specifically, the intelligent scanning controller controls the receiving antenna of the terahertz biosignal receiver to move around the tissue or organ for rotational scanning, or controls the receiving antenna of the terahertz biosignal receiver to move up and down for vertical scanning, or controls the receiving antenna of the terahertz biosignal receiver to move horizontally for horizontal scanning.

[0015] This invention also proposes a terahertz imaging method using the aforementioned ultra-wideband terahertz imaging system, comprising the following steps:

[0016] S1, control the terahertz wave generator to generate a continuous ultra-wideband terahertz signal;

[0017] S2, control the terahertz signal transmitter to continuously transmit ultra-wideband terahertz signals to tissues and organs;

[0018] S3, control the terahertz biosignal receiver to detect electromagnetic fields from tissues and organs and obtain scattered electric fields;

[0019] S4, control the terahertz biosignal processor to perform multi-dimensional image reconstruction on the scattered electric field detected by the terahertz biosignal receiver to obtain multi-dimensional images of tissues and organs;

[0020] S5 transmits multidimensional images of tissues and organs to an image display for image display of the detected tissues and organs.

[0021] Furthermore, S2 specifically includes:

[0022] S21, Establish a rectangular coordinate system for the region to be imaged where the tissue or organ is located;

[0023] S22, an ultra-wideband terahertz wave signal is continuously applied to the tissue / organ by a transmitting antenna of a terahertz signal transmitter. The transmitting antenna is surrounded by the tissue / organ or located on one or both sides of the tissue / organ, and the number of transmitting antennas is N. T 1, N T ≥1.

[0024] Specifically, when the number of transmitting antennas N T >1, and when the transmitting antennas are uniformly distributed in a circular shape, the incident electric field is sequentially excited for each transmitting antenna, and the total incident electric field is N.T The sum of the incident electric fields excited by each transmitting antenna.

[0025] In the first embodiment, when performing two-dimensional image processing, step S3 specifically includes:

[0026] S31, control one receiving antenna of the terahertz biosignal receiver to detect the scattered electric field at at least three receiving positions at the same vertical height from the tissue or organ; or control at least three receiving antennas at the same vertical height from the tissue or organ to detect the scattered electric field at their receiving positions;

[0027] S32, Remove the tissue or organ from the test area and obtain the incident electric field of the transmitting antenna;

[0028] S33, the scattered electric field echo is calculated based on the incident electric field of the transmitting antenna and the scattered electric field detected by the receiving antenna.

[0029] In the second embodiment, when performing three-dimensional image processing, step S3 further includes:

[0030] S34, adjust the vertical height of the receiving antenna, and repeat steps S31 to S33.

[0031] In the first embodiment, S4 specifically includes:

[0032] S41, establish a nonlinear mathematical model between the electromagnetic properties of tissues and organs, such as dielectric constant, conductivity, and magnetic permeability, and the echo of the scattered electric field; establish a characterization mathematical model describing the internal structure of tissues and organs based on the distribution of receiving antenna positions.

[0033] S42, compare the scattered electric field echoes obtained from any two receiving positions at the same vertical height of the receiving antenna in sequence to obtain information on the amplitude and phase reflecting the electromagnetic property distribution of tissues and organs;

[0034] S43, based on the continuously detected electromagnetic property distribution information, extract the corresponding change values ​​and curves from the established nonlinear mathematical model and the characterization mathematical model describing the internal structure of tissues and organs, and reconstruct two-dimensional images of tissues and organs based on the change values.

[0035] In the second embodiment, S4 specifically includes:

[0036] S41. The scattered electric field echo is calculated based on the incident electric field of the transmitting antenna and the scattered electric field detected by the receiving antenna. A nonlinear mathematical model is established between the electromagnetic properties of tissues and organs, such as dielectric constant, conductivity, and magnetic permeability, and the scattered electric field echo. A characterization mathematical model describing the internal structure of tissues and organs is established based on the distribution of the receiving positions of the receiving antenna.

[0037] S42, compare the scattered electric field echoes obtained from any two receiving positions among all receiving positions of the receiving antenna at the same vertical height in turn to obtain information on the amplitude and phase reflecting the electromagnetic property distribution of tissues and organs;

[0038] S43, after adjusting the height of the receiving antenna, the scattered electric field echoes obtained from any two receiving positions at the same vertical height are compared in turn to obtain information on the amplitude and phase of the electromagnetic property distribution of tissues and organs.

[0039] S44. Based on the continuously detected electromagnetic property distribution information, the corresponding change values ​​and curves are extracted from the established nonlinear mathematical model and the characterization mathematical model describing the internal structure of tissues and organs, and the three-dimensional image of the tissues and organs is reconstructed based on the change values.

[0040] Compared with existing technologies, the three-dimensional holographic terahertz imaging system proposed in this invention can reconstruct two-dimensional or three-dimensional images of tissues and organs. Moreover, it is non-contact and non-invasive, requiring no detectors to be attached to tissues and organs. Based on the imaging method of this invention, corresponding medical instruments can be developed, which can display corresponding curves, images, and values, and can continuously monitor various diseases such as breast cancer and skin cancer. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a block diagram of the imaging system in an embodiment of the present invention;

[0043] Figure 2 This is a system concept diagram of the imaging system in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the transmitting antenna and the position of the antenna in the imaging system of this invention embodiment;

[0045] Figure 4 This is a schematic diagram of the geometric arrangement of a pair of terahertz biosignal receivers in the imaging system of an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the receiving antenna height adjustment in the imaging system according to an embodiment of the present invention;

[0047] Figure 6In this embodiment of the invention, the image is a two-dimensional image (real part) of a three-dimensional breast model.

[0048] Figure 7 In this embodiment of the invention, the image is a two-dimensional (imaginary) image of a three-dimensional breast model.

[0049] Figure 8 In this embodiment of the invention, the image is a two-dimensional reconstructed image (real part) of a three-dimensional breast model.

[0050] Figure 9 In this embodiment of the invention, the image is a two-dimensional reconstructed image (imaginary part) of a three-dimensional breast model. Detailed Implementation

[0051] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0052] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0053] The electromagnetic properties of tissues and organs are closely related to the health of physiological systems. When disease occurs, the dielectric properties (commonly expressed as dielectric constant) and conductivity of biological tissues change significantly. Different types of biological tissues exhibit significant differences in dielectric properties and conductivity, providing a feasible physical basis for terahertz imaging to detect the physiological and pathological states of tissues and organs. Terahertz breast imaging reconstructs images of the internal tissue structure of organs by detecting the distribution of scattered electric fields inside and around the organs under the influence of a terahertz electric field, obtaining important characteristics such as the distribution of dielectric constant and conductivity. Over the past two decades, much work has focused on the application of terahertz imaging technology in in vitro biological imaging and tumor detection, such as breast imaging for detecting breast tumors. In this regard, this invention proposes an ultra-wideband terahertz imaging system and method. The imaging system employs a non-contact, non-invasive application method, eliminating the need to attach any detectors to tissues and organs. Based on the imaging method and system of this invention, corresponding medical instruments can be developed to display corresponding curves, images, and numerical values, enabling continuous monitoring of various diseases such as breast cancer and skin cancer.

[0054] like Figure 1 As shown, this invention proposes an ultra-wideband terahertz imaging system, specifically comprising:

[0055] The system comprises a terahertz wave generator, a terahertz signal transmitter, a terahertz biosignal receiver, a terahertz biosignal processor, an image display, and an intelligent scanning controller. The terahertz wave generator, controlled by the intelligent scanning controller, generates a continuous ultra-wideband terahertz signal. This ultra-wideband terahertz signal is continuously applied to the terahertz signal transmitter, which transmits it uninterruptedly to the tissues and organs via its transmitting antenna. The ultra-wideband terahertz signal generates an electromagnetic field around the tissues and organs, inducing an electromagnetic field within them and / or a scattered magnetic field. The receiving antenna of the terahertz biosignal receiver can... The detected stray electric field from the tissues and organs is transmitted to the terahertz biosignal receiver. The terahertz biosignal receiver can reconstruct two-dimensional images of the tissues and organs from the stray electric fields detected by the receiving antenna at different receiving positions at the same vertical height, or it can reconstruct three-dimensional images of the tissues and organs from the stray electric fields detected by the receiving antenna at different receiving positions at multiple vertical heights. This is used to display multi-dimensional images of the tissues and organs. The intelligent scanning controller connects to the terahertz wave generator, terahertz signal transmitter, terahertz biosignal receiver, image display, and terahertz biosignal processor for control.

[0056] In a specific embodiment, the terahertz wave generator uses a vector network analyzer, which can generate terahertz wave signals with a frequency range of 0.1THz-0.17THz.

[0057] In a specific embodiment, the imaging system proposed in this invention operates at an ultra-wideband frequency, with an optimal operating frequency range of 0.1THz-0.17THz.

[0058] Specifically, the terahertz signal transmitter includes at least one transmitting antenna, and the terahertz biosignal receiver includes at least one receiving antenna. Both the transmitting and receiving antennas are terahertz antennas, and they can be the same type of terahertz antenna or different types of terahertz antennas. If they are the same type of antenna, the transmitting antenna transmits terahertz wave information, and the receiving antenna detects changes in the electromagnetic field inside and around tissues and organs, as well as the distribution of dielectric properties and conductivity.

[0059] like Figure 2 As shown, the multiple transmitting antennas of the terahertz signal transmitter are arranged in a uniform ring, which can surround the tissues and organs within the ring, and the height of each transmitting antenna from the tissues and organs is the same (i.e., all transmitting antennas are on the same plane and at the same height).

[0060] The receiving antenna of the terahertz biosignal receiver also uses terahertz antenna 2, and the number of terahertz antennas used as receiving antennas is N. R N Rare natural numbers and N R ≥1. The terahertz antennas, which serve as receiving antennas, are uniformly arranged around the tissue organ 1, forming a circular and uniform arrangement. The distance or height of each receiving antenna from the tissue organ 1 is the same, and the position of the receiving antennas can be adjusted.

[0061] In one embodiment, only one terahertz antenna can be set up, rotating uniformly around the tissue or organ at a rotation angle of 22.5°. That is, the terahertz antenna can collect 16 pieces of information in one rotation around the tissue or organ. Each terahertz antenna serves both as a transmitting antenna to transmit terahertz waves to the tissue or organ and as a receiving antenna to detect changes in the electric field and the distribution of conductivity inside and around the tissue or organ.

[0062] Meanwhile, to reduce the cost of the imaging system and improve its applicability, no additional medium is used between the tissues and organs and the terahertz antennas, i.e., the filling material is air.

[0063] The working principle of the holographic terahertz breast imaging system of this invention is as follows: A continuous ultra-wideband terahertz wave is applied to a terahertz transmitting antenna, and this ultra-wideband terahertz wave signal propagates through space to all other receiving antennas. The propagation of the electric field is affected by the complex conductivity and complex permittivity of the space it passes through. By comparing the amplitude and phase differences of the scattered electric field from different receiving antennas pairwise, information on the spatial complex conductivity, complex permittivity, or permeability can be obtained. By sequentially changing the transmitting antenna and using the remaining terahertz antennas for detection, a complete set of measurement data can be obtained. This measurement data is transmitted to a terahertz biosignal processor, which performs image reconstruction on the detected measurement data, thereby reconstructing a distribution image of conductivity or its variation within a two-dimensional or three-dimensional tomographic section. During the measurement process, the terahertz antenna needs to be rotated uniformly to change the detection position.

[0064] In specific embodiments, terahertz antennas can be waveguide antennas, terahertz patch antennas, horn antennas, metasurface terahertz patch antennas, etc. The size of terahertz antennas is limited by the operating frequency, operating environment, and materials.

[0065] In specific embodiments, the positional relationship between the terahertz transmitting antenna as a transmitting antenna and the terahertz receiving antenna as a receiving antenna specifically includes: both the terahertz transmitting antenna and the terahertz receiving antenna are located on the same side and / or on both sides of the tissue or organ, at the same height or different heights; or the terahertz transmitting antenna and the terahertz receiving antenna are parallel to each other; or the terahertz transmitting antenna and the terahertz receiving antenna coincide (e.g., ...). Figure 3(as shown); or both the terahertz transmitting antenna, which serves as the transmitting antenna, and the terahertz receiving antenna, which serves as the receiving antenna, are at a certain angle to the tissue or organ.

[0066] This invention also proposes a terahertz imaging method using the aforementioned ultra-wideband terahertz imaging system, specifically including the following steps:

[0067] S1, control the terahertz wave generator to generate a continuous ultra-wideband terahertz signal;

[0068] S2, control the terahertz signal transmitter to continuously transmit ultra-wideband terahertz signals to tissues and organs;

[0069] S3, control the terahertz biosignal receiver to detect electromagnetic fields from tissues and organs and acquire electromagnetic field signals;

[0070] S4, control the terahertz biosignal processor to perform multi-dimensional image reconstruction on the electromagnetic field signal detected by the terahertz biosignal receiver to obtain multi-dimensional images of tissues and organs;

[0071] S5, transmit the multidimensional image of the tissue or organ to the image display for image display of the detected tissue or organ.

[0072] Specifically, step S2 above involves the intelligent scanning controller controlling at least one transmitting antenna in the terahertz signal transmitter to apply an uninterrupted ultra-wideband terahertz wave to the tissue organ (which may be the breast); the ultra-wideband terahertz wave generates a scattered electric field around the tissue organ (which may be the breast), and under the action of the electromagnetic field, the excitation electric field generates a scattered electric field when it passes through the tissue organ.

[0073] Furthermore, the above S2 specifically includes the following steps:

[0074] S21, Establish a rectangular coordinate system for the region to be imaged where the tissue or organ is located; used to determine the distance between the tissue / organ and the transmitting and receiving antennas, the position coordinates of the transmitting antenna, the position coordinates of the receiving antenna, and the number of image points N;

[0075] S22, an ultra-wideband terahertz wave signal is continuously applied to the tissues and organs by at least one transmitting antenna of the terahertz signal transmitter. The signal generates an excitation electric field inside and around the tissues and organs. The excitation electric field can be regarded as a time harmonic electric field. When the transmitted electric field passes through the tissues and organs, an incident electric field is generated due to the electromagnetic field.

[0076]

[0077] From organ models to locations The distance vector of the launch day at that location. It is the amplitude of the TE10 mode, AN and B B These are the length and width dimensions of the antenna, respectively. It is a radiation pattern. Vector polarization;

[0078] The specific embodiment of S22 above is: it can be N surrounding the tissue or organ or located on one or both sides of the tissue or organ. T Each transmitting antenna sequentially transmits terahertz wave signals in a specific frequency band.

[0079] Specific scattered electric field echo The method for obtaining it is as follows:

[0080] One or more receiving antennas detect the scattered electric field Where r i Let r be the position coordinates of the transmitting antenna. r Let N be the position coordinates of the receiving antenna; when N T When the electric field is greater than 1 and the transmitting antennas are uniformly distributed in a circular shape, the incident electric field is excited sequentially for each transmitting antenna, and the total incident electric field is N. T The sum of the incident electric fields excited by each transmitting antenna;

[0081] The tissue or organ is removed from the test area, and the same incident electric field is detected while the emission source remains unchanged. That is, the detection is still performed using the same receiving antenna (or the same detection location);

[0082] The scattered electric field echo of tissues and organs can be obtained by subtracting the measurement data from the two steps above, that is:

[0083]

[0084] Specifically, when performing two-dimensional image processing, the above-mentioned S3 further includes the following steps:

[0085] S31, Obtain the scattered electric field of the receiving antenna of the terahertz signal transmitter at at least three receiving positions at the same vertical height from the tissue organ. That is, it can be that at least three receiving antennas are located at the same vertical height at three receiving positions, or one receiving antenna is moved to three different receiving positions at the same vertical height for detection.

[0086] S32, Remove the tissue or organ from the test area and obtain the incident electric field of the transmitting antenna;

[0087] S33, the scattered electric field echo is calculated based on the incident electric field of the transmitting antenna and the scattered electric field detected by the receiving antenna.

[0088] If only a two-dimensional image is needed, then step S33 ends; if a three-dimensional image is needed, then step S34 continues.

[0089] S34, adjust the vertical height of the receiving antenna (specifically, relative to the horizontal reference plane where the tissue or organ is located), obtain the scattered electric field of the receiving antenna at at least three receiving positions at that vertical height from the tissue or organ, and repeat steps S31 to S33 to obtain the scattered electric field echo at another height.

[0090] Specifically, when acquiring a two-dimensional image, S4 above further includes the following steps:

[0091] S41. The scattered electric field echo is calculated based on the incident electric field of the transmitting antenna and the scattered electric field detected by the receiving antenna. A nonlinear mathematical model is established between the electromagnetic properties of tissues and organs, such as dielectric constant, conductivity, and magnetic permeability, and the scattered electric field echo. A characterization mathematical model describing the internal structure of tissues and organs is established based on the distribution of the receiving positions of the receiving antenna.

[0092] S42, compare the scattered electric field echoes obtained from any two receiving positions at the same vertical height of the receiving antenna in sequence to obtain information on the amplitude and phase reflecting the electromagnetic property distribution of tissues and organs;

[0093] S43, based on the continuously detected electromagnetic property distribution information, extract the corresponding change values ​​and curves from the established nonlinear mathematical model and the characterization mathematical model describing the internal structure of tissues and organs, and reconstruct two-dimensional images of tissues and organs based on the change values.

[0094] Specifically, when acquiring a 3D image, S4 above further includes the following steps:

[0095] S41. The scattered electric field echo is calculated based on the incident electric field of the transmitting antenna and the scattered electric field detected by the receiving antenna. A nonlinear mathematical model is established between the electromagnetic properties of tissues and organs, such as dielectric constant, conductivity, and magnetic permeability, and the scattered electric field echo. A characterization mathematical model describing the internal structure of tissues and organs is established based on the distribution of the receiving positions of the receiving antenna.

[0096] S42, compare the scattered electric field echoes obtained from any two receiving positions among all receiving positions of the receiving antenna at the same vertical height in turn to obtain information on the amplitude and phase reflecting the electromagnetic property distribution of tissues and organs;

[0097] S43, compare the scattered electric field echoes obtained from any two receiving positions at the same vertical height after the receiving antenna height is adjusted, and obtain the amplitude and phase information reflecting the electromagnetic property distribution of tissues and organs.

[0098] S44. Based on the continuously detected electromagnetic property distribution information, the corresponding change values ​​and curves are extracted from the established nonlinear mathematical model and the characterization mathematical model describing the internal structure of tissues and organs, and the three-dimensional image of the tissues and organs is reconstructed based on the change values.

[0099] In the two embodiments above, S41 specifically refers to:

[0100] Establish a nonlinear mathematical model between the electromagnetic properties of tissues and organs (such as the breast), such as dielectric constant, conductivity, and magnetic permeability, and the echo of the scattered electric field. Based on the distribution of the receiving positions of the receiving antennas, establish a characterization mathematical model describing the internal structure of tissues and organs.

[0101] Based on the mechanism by which terahertz waves induce multiple scattering between different tissues within an organ after penetrating its surface, an internal field effect model describing the nonlinear mathematical model and an external field effect model describing the organ are obtained.

[0102] The internal field effect model is described as follows:

[0103]

[0104] In equation (2), Let G be the incident electric field, and G be the Green's function. Let be the position vector from the source point to the scattered electric field. Let k be the position vector from the source point to any point within the tissue or organ, and k0 be the wavenumber in free space. It is the magnetic current density. j is the imaginary part of the complex number. μ r Let μ be the magnetic permeability of the tissue or organ, and μ0 be the magnetic permeability of free space. For the total electric field, = Incident electric field + Scattered electric field, where V is the volume of the target object.

[0105] The mathematical model for the total electric field is:

[0106]

[0107] In equation (3), For the incident electric field, To get from the target point to the location The vector distance of the terahertz antenna, Represents the divergence operator. For Green's function, Let be the position vector from the source point to any point within the tissue or organ.

[0108] The externally scattered electric field model (external electric field effect model) is as follows:

[0109]

[0110] In equation (4), For the scattered electric field (scattered electric field echo), For any target point within an organ, the distance to the location located The vector distance of the terahertz antenna, Represents the position vector. R represents the distance between the scattering source and the target point. Further, letting a≈1 and b≈-1, the scattering electric field model can be described as follows:

[0111]

[0112] A nonlinear mathematical model is obtained by combining the internal electric field effect model and the external electric field effect model.

[0113]

[0114] S42 specifically includes the following steps:

[0115] Calculate the positions of any two receiving antennas among all receiving positions at the same vertical height (i.e., on the same plane, with equidistant vertical distances from the tissue or organ). Visibility function: Calculates the visibility of any two receiver positions among all receiver antenna positions. Visible functions:

[0116]

[0117] In equation (7), * denotes complex conjugate, and <> denotes average time. It can be seen that the function... Includes any two receiving antenna positions Detected phase delay and / or amplitude difference.

[0118] Calculate the visibility function of the received signal at any two receiving antenna positions sequentially to obtain the total visibility function detected at all receiving positions. This is done when the receiving antenna positions are N. R At this time, N R are natural numbers and N R ≥3, total visible function is N R (N R -1) sum of visible functions detected at the locations of the receiving antennas.

[0119] Two-dimensional images of tissues and organs are obtained by performing an inverse Fourier transform on the total visible function detected at all receiving antenna locations.

[0120] The specific process of reconstructing two-dimensional images of tissues and organs is explained below with reference to the accompanying drawings.

[0121] like Figure 4 As shown, suppose a point Q(x,y,z) is located inside a tissue or organ. Any two points within the receiving area of ​​this point Q(x,y,z) relative to the receiving antenna are located... and The scattered electric field at the receiving position of the receiving antenna is represented by the visible function of equation (7), that is, a mathematical model is established to characterize it.

[0122] exist The scattering intensity of the tissue / organ (breast) at the location is:

[0123]

[0124] The visible volume of an organ (breast) is divided into:

[0125]

[0126] Substituting equation (9) into equation (7), we get:

[0127]

[0128] In equation (10), λ b For the operating wavelength, Unit vector in spherical coordinate system dV = s 2 sinθdθdφds.

[0129] Define new parameters (l, m, n):

[0130]

[0131] dV can be obtained from the following formula:

[0132] dV = s 2 dldmds / n (12)

[0133] Substituting formula (12) into (10), we get:

[0134]

[0135] Components of the baseline vector in the Cartesian coordinate system for

[0136]

[0137]

[0138] Because the terahertz antennas (the receiving positions of the receiving antennas) are arranged at the same height, the visibility scattering function equation for the tissue (breast) becomes:

[0139]

[0140] The line integral along the radial coordinate n is:

[0141]

[0142] Using equation (16), the following two-dimensional integral visibility scattering function for the variable (l,m) is obtained:

[0143]

[0144] The visibility scattering function (17) is a two-dimensional Fourier transform; therefore, a two-dimensional breast image can be reconstructed through an inverse Fourier transform.

[0145]

[0146] Equation (18) shows that a two-dimensional image of a three-dimensional tissue model can be reconstructed by the inverse Fourier transform visibility scattering function.

[0147] In step S3 above, when the tissue or organ is non-magnetic and conductive, the scattered electric field received by the tissue or organ at any receiving position of the receiving antenna can be calculated by formula (6). This method can be used to monitor various physiological and pathological characteristics of organisms, such as breast tumors, strokes, and skin diseases.

[0148] In step S4 above, a time series of at least one electromagnetic property of the tissue / organ is formed based on the scattered electric field detected by two of the at least three receiving antenna positions, and the difference in electromagnetic properties detected by the at least two receiving antenna positions is calculated to construct a two-dimensional image of the tissue / organ. Following a method where the height of the at least three receiving positions is kept the same relative to the tissue / organ (i.e., the three receiving positions are at the same vertical height from the tissue / organ), while gradually changing the height (i.e., moving the receiving antennas vertically to change the receiving positions), the difference in electromagnetic properties detected by the at least two receiving positions (electromagnetic property distribution information, specifically the amplitude and phase information of the electromagnetic property distribution) is calculated to construct a three-dimensional image of the target organism. By calculating the distribution of visible intensity differences of the tissue / organ acquired by the receiving antennas at different heights, and comparing the visible intensity differences acquired by the receiving antennas at different heights pairwise, a complete set of data is formed, thereby achieving three-dimensional image reconstruction. The spatial resolution of the three-dimensional image is affected by the antenna type, antenna shape, scanning speed, scanning height, operating frequency, and antenna material.

[0149] To verify the holographic terahertz imaging method proposed in this invention, a three-dimensional simulation model was established using the MATLAB platform to simulate the effects of scattered electric fields on different tissues when breast tumors occur. Figure 6 It is a two-dimensional image (real part) of a three-dimensional breast model; Figure 7 It is a two-dimensional image (imaginary part) of a three-dimensional breast model; Figure 8 It is a two-dimensional reconstructed image (real part) of a three-dimensional breast model; Figure 9 This is a two-dimensional reconstructed image (imaginary part) of a three-dimensional breast model. The reconstructed image of the three-dimensional breast model can clearly show different breast tissues, including tumor cells.

[0150] It should be noted that the terminology used above is for describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0151] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ultra-wideband terahertz imaging system, characterized in that, include: Terahertz wave generator, used to generate continuous ultra-wideband terahertz signals; A terahertz signal transmitter, used to transmit ultra-wideband terahertz signals generated by the terahertz wave generator to tissues and organs; Terahertz biosignal receivers have adjustable vertical antennas for detecting electromagnetic fields around tissues and organs at different heights to obtain scattered electric fields. The terahertz biosignal processor is configured to: receive scattered electric field data detected by the terahertz biosignal receiver at different height planes; for each height plane, calculate the visibility function of the scattered electric field between any two locations based on the scattered electric field data at at least three detection locations within the plane; perform inverse Fourier transform on all visibility functions to reconstruct a two-dimensional image of the height plane; and combine the two-dimensional images of each height plane to obtain a three-dimensional image of the tissue or organ. Image display for showing multidimensional images of tissues and organs; The intelligent scanning controller connects to and controls the terahertz wave generator, terahertz signal transmitter, terahertz biosignal receiver, image display, and terahertz biosignal processor.

2. The ultra-wideband terahertz imaging system as described in claim 1, characterized in that, The terahertz signal transmitter includes at least one transmitting antenna, and the terahertz biosignal receiver includes at least one receiving antenna.

3. The ultra-wideband terahertz imaging system as described in claim 1, characterized in that, The intelligent scanning controller controls the receiving antenna of the terahertz biosignal receiver to move around the tissue or organ for rotational scanning, or controls the receiving antenna of the terahertz biosignal receiver to move up and down for vertical scanning, or controls the receiving antenna of the terahertz biosignal receiver to move horizontally for horizontal scanning.

4. A terahertz imaging method, characterized in that, Using the ultra-wideband terahertz imaging system according to any one of claims 1 to 3, the steps include: S1, control the terahertz wave generator to generate a continuous ultra-wideband terahertz signal; S2, control the terahertz signal transmitter to continuously transmit ultra-wideband terahertz signals to tissues and organs; S3, control the terahertz biosignal receiver to detect electromagnetic fields from tissues and organs and obtain scattered electric fields; S4, control the terahertz biosignal processor to perform multi-dimensional image reconstruction on the scattered electric field detected by the terahertz biosignal receiver to obtain multi-dimensional images of tissues and organs; S5 transmits multidimensional images of tissues and organs to an image display for image display of the detected tissues and organs.

5. The terahertz imaging method as described in claim 4, characterized in that, S2 specifically includes: S21, Establish a rectangular coordinate system for the region to be imaged where the tissue or organ is located; S22, an ultra-wideband terahertz wave signal is continuously applied to the tissue / organ by a transmitting antenna of a terahertz signal transmitter. The transmitting antenna is surrounded by the tissue / organ or located on one or both sides of the tissue / organ. The number of transmitting antennas is [number missing]. indivual, ≥1.

6. The terahertz imaging method as described in claim 5, characterized in that, When the number of transmitting antennas When the transmitting antennas are uniformly distributed in a circular shape, an incident electric field is sequentially excited for each transmitting antenna, and the total incident electric field is... The sum of the incident electric fields excited by each transmitting antenna.

7. The terahertz imaging method as described in claim 5, characterized in that, When performing two-dimensional image processing, S3 specifically includes: S31, control one receiving antenna of the terahertz biosignal receiver to detect the scattered electric field at at least three receiving positions at the same vertical height from the tissue or organ; or control at least three receiving antennas at the same vertical height from the tissue or organ to detect the scattered electric field at their receiving positions; S32, Remove the tissue or organ from the test area and obtain the incident electric field of the transmitting antenna; S33, the scattered electric field echo is calculated based on the incident electric field of the transmitting antenna and the scattered electric field detected by the receiving antenna.

8. The terahertz imaging method as described in claim 7, characterized in that, When performing three-dimensional image processing, S3 further includes: S34, adjust the vertical height of the receiving antenna, and repeat steps S31 to S33.

9. The terahertz imaging method as described in claim 7, characterized in that, S4 specifically includes: S41, establish a nonlinear mathematical model between the electromagnetic properties of tissues and organs, such as dielectric constant, conductivity, and magnetic permeability, and the echo of the scattered electric field; establish a characterization mathematical model describing the internal structure of tissues and organs based on the distribution of receiving antenna positions. S42, compare the scattered electric field echoes obtained from any two receiving positions at the same vertical height of the receiving antenna in sequence to obtain information on the amplitude and phase reflecting the electromagnetic property distribution of tissues and organs; S43, based on the continuously detected electromagnetic property distribution information, extract the corresponding change values ​​and curves from the established nonlinear mathematical model and the characterization mathematical model describing the internal structure of tissues and organs, and reconstruct two-dimensional images of tissues and organs based on the change values.

10. The terahertz imaging method as described in claim 8, characterized in that, S4 specifically includes: S41, establish a nonlinear mathematical model between the electromagnetic properties of tissues and organs, such as dielectric constant, conductivity, and magnetic permeability, and the echo of the scattered electric field; establish a characterization mathematical model describing the internal structure of tissues and organs based on the distribution of receiving antenna positions. S42, compare the scattered electric field echoes obtained from any two receiving positions among all receiving positions of the receiving antenna at the same vertical height in turn to obtain information on the amplitude and phase reflecting the electromagnetic property distribution of tissues and organs; S43, after adjusting the height of the receiving antenna, the scattered electric field echoes obtained from any two receiving positions at the same vertical height are compared in turn to obtain information on the amplitude and phase of the electromagnetic property distribution of tissues and organs. S44. Based on the continuously detected electromagnetic property distribution information, the corresponding change values ​​and curves are extracted from the established nonlinear mathematical model and the characterization mathematical model describing the internal structure of tissues and organs, and the three-dimensional image of the tissues and organs is reconstructed based on the change values.

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