CN110731774A - Medical multi-focus imaging system and method for imaging biological tissues by using same - Google Patents

Medical multi-focus imaging system and method for imaging biological tissues by using same Download PDF

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CN110731774A
CN110731774A CN201810799248.7A CN201810799248A CN110731774A CN 110731774 A CN110731774 A CN 110731774A CN 201810799248 A CN201810799248 A CN 201810799248A CN 110731774 A CN110731774 A CN 110731774A
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conductivity
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CN110731774B (en
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戴明
陈昕
陈思平
朱慧萍
孙通
于凌尧
陈冕
林浩铭
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Shenzhen University
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Abstract

The medical multi-focus imaging system comprises a conductivity front-end detection unit, a control unit, an excitation signal transmission unit and a voltage detection and processing unit, wherein the conductivity front-end detection unit comprises a detection water tank, a static magnetic field generation device and a probe, the control unit comprises a control module and a motion control platform, the voltage detection and processing unit respectively comprises a voltage detection module and a conductivity calculation module, and conductivity values measured by a focus point and an adjacent symmetrical point are adopted in the conductivity acquisition process, so that the vibration amplitude of particles at each focus point and the adjacent symmetrical point is ensured to be relatively , and the Lorentz force generated under the same static magnetic field is relatively , therefore, the method of multi-step sweep excitation by using a single focus probe overcomes the influence of the focus probe on the conductivity imaging resolution during single excitation of the focus probe in the Z-axis direction, solves the problem of uneven distribution of an ultrasonic excitation vibration source, and remarkably improves the conductivity resolution of magnetoacoustic electrographic imaging.

Description

Medical multi-focus imaging system and method for imaging biological tissues by using same
Technical Field
The invention relates to the field of medical imaging, in particular to a medical multi-focus imaging system and a method for imaging biological tissues by using the same.
Background
The existing conductivity detection method mainly comprises electrical impedance imaging (EIT), magnetic resonance electrical impedance imaging (MREIT), magnetoacoustic imaging (MAT), magnetoacoustic-electrical imaging (MAET), inductive magnetoacoustic imaging (MAT-MI) and difference frequency magnetoacoustic imaging (DF-MAET), but various imaging methods have limitations, for example, Electrical Impedance (EIT) imaging methods are not high in resolution and are not suitable for existing tissue conductivity imaging, inductive magnetoacoustic imaging (MAT-MI) uses coil excitation, and has the influence of an alternating magnetic field on tissue current, a voltage injection magnetoacoustic detection method injects current into an imaging body, and has the advantages of dispersed distribution and reduced spatial resolution, magnetoacoustic-electrical imaging (MAET) combines the advantages of magnetic, acoustic and electric fields, overcomes the limitation of the traditional single physical field, has the advantages of high ultrasonic imaging resolution and traditional electrical impedance imaging high contrast, has low requirements on the field intensity and uniformity of a magnet, and low cost, and can be detected by an electrode, the follow-up processing method is relatively simple, so that the magnetoacoustic-electrical impedance imaging method is applied to research, the research of the conventional electrical impedance imaging method is not easy to solve the problem of high-resolution, the existing scalar electrical conductivity imaging method of electromagnetic interference, and the problem of the existing scalar electrical signal interference of the high-electrical signal interference, the problem of the traditional electrical impedance imaging is solved by the traditional electromagnetic interference of the traditional electromagnetic interference, the traditional electromagnetic interference of the traditional electromagnetic interference, the traditional electromagnetic interference probe, and the traditional electromagnetic interference probe, the high-electrical interference probe is not easy-electrical interference probe, and the high-electrical-;
the magneto-acoustic conductivity imaging is a supplement of the existing medical imaging method, the imaging method is designed by fusing a magnetic field, an electric field, a sound field and three physical fields, utilizing the advantages of high resolution of ultrasonic imaging, high contrast of electrical impedance imaging and relatively simple subsequent processing of electric field detection signals, the magneto-acoustic conductivity imaging method is based on the theory of magneto-acoustic electrical imaging, and utilizes an ultrasonic focusing water immersion power probe to excite a measured sample, conductivity values of focus points and adjacent symmetrical points of each focus point are obtained by combining excitation signals and electrode detection voltage signals and moving a probe focus point, so that a conductivity distribution diagram of the focus probe in a biological tissue is obtained, the magneto-acoustic electrical imaging method for forming the conductivity of the biological tissue is expected to become a method for early diagnosis of the future cancer due to the fact that conductivity change is a mark of early symptoms of most of the cancer tissue, the method is expected to be designed into a portable noninvasive early diagnosis instrument for the cancer, the magneto-acoustic conductivity imaging mainly adopts an easy theorem to research and calculate, but has high complexity, long calculation time, boundary conditions, inverse problems such as unsuitability problems of high resolution and low cost of micro-MRI (magnetic resonance imaging) for high resolution imaging, high resolution MRI (magnetic resonance imaging) and high frequency signal processing) and high-frequency MRI (magnetic resonance imaging) is still difficult to be reflected by the problems of high-acoustic imaging method for the high-frequency MRI (magnetic resonance imaging) and high-MRI) and low-acoustic imaging method for the MRI (magnetic imaging method).
The method is characterized in that a traditional electrical impedance method is not suitable for biological tissue conductivity imaging, induction type magnetic acoustic electrical imaging uses coil excitation, an alternating magnetic field influences tissue current, a voltage injection magnetic acoustic detection method injects current into an imaging body, dispersive distribution of the current reduces spatial resolution, magnetic acoustic electrical imaging combines advantages of magnetic, acoustic and electric fields, the limitation of a traditional single physical field is overcome, the advantages of high ultrasonic imaging resolution and high traditional electrical impedance imaging contrast are achieved, requirements on magnetic field strength and uniformity are low, cost is low, detection can be performed through electrodes, a subsequent processing method is relatively simple, the existing magnetic acoustic electrical imaging is based on reciprocity theorem, a plane wave probe is adopted for excitation, a narrow pulse high-voltage signal is used as an excitation signal source signal, weak voltage signals are detected through an electrode pair, scanning excitation is performed through the circumference of the probe, a magnetoacoustic electrical algorithm based on reciprocity theorem is adopted for processing, a magnetoacoustic electrical inversion process is required, qualitative misappropriation exists in an inversion process, vectors are vector to scalar, information loss is caused in a process from scalar to vector, the vector is caused by the defect of information in the process, the defect of the probe, the defect of the information, the defect of the.
Disclosure of Invention
The invention provides a medical multi-focus imaging system and a method for imaging biological tissues by using the same, which aim to solve the problems of high computational complexity and low accuracy of an imaging system in the prior art and solve the technical problems of low signal-to-noise ratio and low resolution of an obtained conductivity distribution map in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the medical multi-focus imaging system comprises a conductivity front-end detection unit, a control unit, an excitation signal transmission unit and a voltage detection and processing unit:
the conductivity front end detecting unit includes a conductivity detecting unit,
the detection water tank is used for containing a sample to be detected, a silver-plated copper electrode is arranged inside the detection water tank, and the silver-plated copper electrode is arranged perpendicular to the bottom of the detection water tank;
the static magnetic field generating device comprises two static Ru-Fe-B magnets and a C-shaped bracket which are oppositely arranged on two sides of the detection water tank;
the probe is an ultrasonic water immersion focusing power probe, extends to the surface of the measured sample and is used for providing ultrasonic vibration required by high-power ultrasonic excitation on the measured sample;
the control unit comprises a control unit and a control unit,
the control module is used for controlling the probe to perform stepping excitation motion through the motion control platform, triggering the excitation signal transmission unit to generate a linear sweep frequency Chirp signal, and triggering the voltage detection and processing unit to perform conductivity calculation processing;
the motion control platform is used for controlling the probe to perform scanning motion at a specified focusing point and feeding back the current position information of the probe in the motion process to the control module;
the excitation signal transmission unit is respectively connected with the control module and the probe, the excitation signal transmission unit generates a linear sweep frequency Chirp signal through excitation of the control module, the linear sweep frequency Chirp signal is transmitted to the probe to excite the probe to generate ultrasonic waves, and the linear sweep frequency Chirp signal of the excitation signal transmission unit is also transmitted to the voltage detection and processing unit;
the voltage detection and processing units respectively comprise a voltage detection unit,
the voltage detection module is simultaneously connected with the excitation signal transmission unit and the detection water tank and is used for processing a linear frequency sweep Chirp signal from the power distributor of the excitation signal transmission unit and an electrode voltage signal from the detection conductivity front-end detection unit;
and the conductivity calculation module is used for receiving the electrode voltage signal and the linear frequency sweep Chirp signal which are processed by the voltage detection module, triggering the electrode voltage signal and the linear frequency sweep Chirp signal to perform conductivity calculation processing by using a trigger signal transmitted by the control module, obtaining a conductivity curve of an excitation point of a single detected sample after processing the signals, and drawing an internal conductivity distribution diagram of the detected sample according to the conductivity curve of series of excitation points.
, preferably, the excitation signal delivery unit includes,
the signal generation module is used for triggering the triggering signal transmitted by the control module to generate a linear frequency sweep Chirp signal;
the power distribution module is used for respectively distributing the linear frequency sweep Chirp signals generated by the signal generation module to the power amplification module and the voltage detection module;
and the power amplification module is used for transmitting the linear frequency sweep Chirp signal from the power distribution module to the probe after power amplification so as to excite the probe to generate ultrasonic waves.
, the conductivity calculation module further includes,
the impedance matching module is connected with the voltage detection module and is used for performing impedance matching on the electrode voltage signal and the linear sweep frequency Chirp signal from the voltage detection module;
an ADC acquisition module: the impedance matching module is connected with the input end of the analog-to-digital converter and is used for converting the two paths of signals processed by the impedance matching module into corresponding digital signals through the analog-to-digital converter;
a pre-amplification module: the ADC acquisition module is connected with the digital signal processing module and is used for amplifying the digital signals obtained by processing the two paths of signals by the ADC acquisition module;
the mean value processing module: the pre-amplification module is connected with the digital signal processing module and is used for carrying out mean value processing on the amplified digital signal;
a band-pass filtering module: the digital signal processing module is connected with the mean value processing module and is used for carrying out band-pass filtering processing on the digital signal after the mean value processing;
a digital dot multiplication module: the band-pass filter module is connected with the digital signal processing module and is used for carrying out digital point multiplication processing on the digital signal after the band-pass filtering processing;
a low-pass filtering module: the digital dot multiplication module is connected with the digital signal processing module and is used for performing low-pass filtering processing on the digital signal after the digital dot multiplication processing;
an FFT transform module: the low-pass filtering module is connected with the digital signal processing module and is used for converting the digital signal processed by the low-pass filtering module into an intermediate frequency signal;
scale conversion and peak detection module: the FFT conversion module is connected with the sample to be measured and used for obtaining a conductivity curve of a single excitation point of the sample to be measured through the intermediate frequency signal;
an imaging processing module: and the conductivity curve of the required excitation point obtained by the scale conversion and peak detection module is collected, and a conductivity distribution diagram is drawn according to the conductivity curve of the required excitation point.
, the voltage detection module further includes a impedance matching module, a ADC acquisition module and a preamplifier module connected in sequence, the impedance matching module, the ADC acquisition module and the preamplifier module respectively perform signal processing on the electrode voltage signal and the linear frequency sweep Chirp signal, wherein the impedance matching module is electrically connected with the silver-plated copper electrode and the power distribution module, and the preamplifier module is connected with the impedance matching module.
, the imaging process module is connected with the display module, the two-dimensional conductivity distribution map drawn by the imaging process module is displayed on the display module, and the display module is also used for displaying the state information of the voltage detection module.
, the conductivity calculating module is also connected to the input module, the input module is used to input the conductivity calculating command and the required display mode of the display module.
In addition, the control module is also connected with a second display module, and the second display module is an 8-inch Divingdus screen with a touch function.
More preferably, the control module is further connected to a second input module, and the second input module is configured to input a control command and a preset scanning plan.
The method for imaging the biological tissue by using the conductivity imaging system is characterized in that the probe performs uniform step scanning in the Z-axis direction and the X-axis direction to obtain a two-dimensional conductivity distribution map of a tested sample, wherein the Z-axis direction is the direction from the probe to the bottom of a water tank, the X-axis direction is the horizontal direction, and the step position point in the Z-axis direction is Z1，z2……zmStepping position in X-axis direction by X1，x2……xnThe method specifically comprises the following steps:
firstly, after receiving an input instruction of an th input module through a conductivity calculation platform, obtaining a constant k calculated by the conductivity calculation module at an excitation point, wherein k is constants calculated by the calculation platform and is determined by a step length in the Z-axis direction, a frequency m of sweep excitation in the Z-axis direction, an acquisition frequency of an ADC (analog to digital converter) acquisition module, an acoustic velocity c and a linear sweep time width T factor, and when a control probe is focused on (x)1，z1) At the site, imaging is performed at the site by a conductivity imaging system, obtaining a signal at (x)1，z1) The conductivity curve at excitation and extracting z on the curve1Moving the probe in the Z-axis direction with the focus of the probe at (x) and k magneto-acoustic conductivity values at the focus and adjacent to the symmetry point1，z2) Position, then through a conductivity imaging system in (x)1，z2) Is imaged to obtain z2Treating the electrical conductivity curve at excitation, and extracting the curveOn-line z2K magneto-acoustic conductivity values of the focus point and the adjacent symmetrical point, repeating the above steps to obtain the value in z3， z4……zmThe focus and the magnetic acoustic conductivity values adjacent to the symmetric point, at this time, k × m focus and conductivity values adjacent to the symmetric point are extracted, synthesized conductivity curves along Z axis are obtained according to the position information of each focus, and the conductivity curves are obtained according to the above-mentioned conductivity curves at x axis1A step of acquiring magneto-acoustic conductivity values in the Z-axis direction of the site, controlling the probe in the x-axis direction2，x3……xnAnd moving the sites in the Z-axis direction to obtain conductivity values of the sites in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k m n conductivity values, and combining the positions of probe excitation points and corresponding algorithms to obtain a two-dimensional conductivity distribution map on an XZ plane.
The method for imaging the biological tissue by using the conductivity imaging system is characterized in that the probe performs uniform step scanning in the Z-axis direction, the Y-axis direction and the X-axis direction to obtain a three-dimensional conductivity distribution map of a detected sample, wherein the Z-axis direction is the direction from the probe to the bottom of a detection water tank, the X-axis direction is the horizontal direction, the Y-axis direction is the longitudinal direction vertical to the X-axis, and the step position point in the Z-axis direction is the Z-axis1，z2…… zmStepping position in X-axis direction by X1，x2……xnY is the stepping position in the Y-axis direction1，y2……ypThe method specifically comprises the following steps:
first, the probe is controlled to be at x1Site, x2，x3……xnMoving the sites in the Z-axis direction to obtain the conductivity values of the sites in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k m n conductivity values, and combining the probe excitation point position and corresponding algorithm to obtain the X plane passing through y1And then controlling the probe focus point (x)n，y1， zm) Return motion first starts with excitation point (x)1，y1，z1) Then controlling the focusing point of the probe to step in the Y-axis directionGo steps to (x)1，y2，z1) And then repeating the process of obtaining the two-dimensional conductivity histogram, i.e. while the probe is at x1，x2，x3……xnMoving the sites in the Z-axis direction to obtain the conductivity values of the sites in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k m n conductivity values, and combining the probe excitation point position and corresponding algorithm to obtain the X-Z plane passing through y2A two-dimensional conductivity profile of. And by analogy, when the probe is step-scanned in the Y-axis direction for p times, the probe moves to (x)m，yp，zn) And then obtaining two-dimensional conductivity distribution maps of p XZ planes, and combining Y-axis excitation position information, namely reconstructing a three-dimensional conductivity distribution map on an XYZ space through k m n p conductivity values.
The implementation of the invention can achieve the following beneficial effects:
in two different focus points and adjacent symmetrical points, as the focus point of the same probe is used for excitation, the vibration amplitudes of particles generated by the focus point and the adjacent symmetrical points in an imaging body are fixed (close), therefore, the focus point position is changed by moving the focus probe in the depth direction according to the principle that the conductivity amplitudes of the two focus points and the adjacent symmetrical points with the same conductivity change are close, so that the conductivity amplitude of each focus point and the adjacent symmetrical points are obtained in the Z-axis direction, m conductivity curves along the Z-axis direction are sequentially obtained by combining m-1 step excitations in the Z-axis direction, the position of the probe in the X-axis direction is changed, so that m conductivity curves along the Z-axis direction of a lower batch are obtained, the conductivity values of each focus point and the adjacent symmetrical points are extracted from the m conductivity curves, further the conductivity curves along the Z-axis direction are synthesized conductivity curves along the Z-axis direction, n synthesized conductivity curves are obtained by n-1 step motions in the X-axis direction, further, the adjacent conductivity curves along the Z-axis direction are obtained, the adjacent conductivity curves are obtained, the adjacent conductivity curves are subjected to the high-axis vibration-frequency ultrasonic imaging, the high-frequency ultrasonic imaging acoustic imaging effect is overcome, the high-noise-caused by the high-noise-caused by-caused high-caused by-caused high-noise-induced vibration-induced high-induced vibration-induced vibration.
The conductivity values measured by the focus points and the adjacent symmetrical points are adopted in the conductivity acquisition process, so that the particle vibration amplitude of each focus point and the adjacent symmetrical point is ensured to be , and the Lorentz force generated under the action of the same static magnetic field is also , therefore, the method for multi-time frequency sweep stepping excitation by using the single focus probe overcomes the influence of the focus probe on the conductivity imaging resolution when the focus probe is excited in a single time in the Z-axis direction, solves the problem of uneven distribution of the ultrasonic excitation vibration source, and obviously improves the magnetoacoustic-electrical conductivity imaging resolution.
Drawings
FIG. 1 is a schematic diagram of a medical multi-focus imaging system according to the present invention;
FIG. 2 is a schematic diagram of a conductivity calculation module according to the present invention;
FIG. 3 is a conductivity magnitude image after 30 conductivity curves along the Z-axis are arranged in order of depth of excitation;
FIG. 4 is a schematic diagram of a structure of the change of the focal point position of the probe at the interface of the two-layer conductivity change;
FIG. 5 is a graph of the conductivity of a measured sample obtained with a two-layer conductivity change interface;
FIG. 6 is a schematic diagram of a structure of the position change of the focus point of the probe at the four-layer conductivity change interface;
FIG. 7 is a graph of the conductivity of the measured sample obtained with a four layer conductivity change interface;
FIG. 8 is 10 conductivity curves obtained at 10 different focus excitation point locations;
FIG. 9 is a flow chart illustration of a method of two-dimensional imaging using a conductivity imaging system;
fig. 10 is a step diagram of a probe for two-dimensional imaging using a conductivity imaging system.
The reference numbers of the device comprise 1-a detection water tank, 2-a sample to be detected, 3-a probe, 4-a control module, 5-a motion control platform, 6-a hole, 7-a voltage detection module, 71-a -th impedance matching module, 72-a -th ADC acquisition module, 73-a -th preamplifier module, 8-a conductivity calculation module, 81-an impedance matching module, 82-an ADC acquisition module, 83-a preamplifier module, 84-a mean value processing module, 85-a band-pass filtering module, 86-a digital dot multiplication module, 87-a low-pass filtering module, 88-an FFT conversion module, 89-a scale conversion and peak detection module, 90-an imaging processing module, 9-a signal generation module, 10-a power distribution module, 11-a power amplification module, 12-a 34-a display module, 13-a input module, 14-a second display module, 15-a second input module, 16-a static silver-plated electrode, 17-a magnetic field generation device, a-a fourth interface, b-a third interface, c-a third interface, a fourth interface, a third interface, a lower interface, a third interface, a fourth interface, a lower interface, a focus point, a.
Detailed Description
The detailed description of the embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to more clearly understand the technical features, objects, and effects of the present invention, it is obvious that the described embodiments are only a part of the embodiments , not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention are within the scope of the present invention without any inventive work.
The invention relates to a magnetoacoustic imaging method and a system innovatively provides new imaging methods, which can not only carry out stepping scanning in the X-axis direction, but also carry out stepping sweep excitation in the depth direction and the longitudinal depth of the probe, and can clearly obtain a two-dimensional conductivity distribution map or a three-dimensional conductivity distribution map which is close to the conductivity of the biological tissue, therefore, the invention is expected to obtain high-resolution biological tissue conductivity imaging on the prior magnetoacoustic technology, thereby realizing the diagnosis and treatment of the biological tissue such as tumor, cancer and the like.
The medical multi-focus imaging system comprises a conductivity front-end detection unit, a control unit, an excitation signal transmission unit and a voltage detection and processing unit;
the conductivity front end detecting unit includes:
the detection water tank 1 is used for containing a sample 2 to be detected, a silver-plated copper electrode 16 is arranged inside the detection water tank 1, and the silver-plated copper electrode 16 is arranged vertical to the bottom of the detection water tank 1;
the static magnetic field generating device 17 comprises two static Ru-Fe-B magnets and a C-shaped bracket which are oppositely arranged at two sides of the detection water tank;
the probe 3 is an ultrasonic water immersion focusing power probe, extends to the surface of the sample 2 to be measured, and is used for providing ultrasonic vibration excitation required for carrying out high-power ultrasonic excitation on the sample 2 to be measured;
the control unit includes:
the control module 4 is used for controlling the probe 3 to move through the motion control platform 5, triggering the excitation signal transmission unit to generate a linear sweep frequency Chirp signal, and triggering the voltage detection and processing unit to perform conductivity calculation processing;
the motion control platform 5 is used for controlling the probe 3 to perform scanning motion at a specified focusing point and feeding back the current position information of the probe 3 in the motion process to the control module 4;
the control module 4 is also connected to a second display module 14, the second display module 14 being an 8 inch divin DGUS screen with touch functionality. The control module 4 is further connected to a second input module 15, and the second input module 15 is used for inputting a control command and a preset scanning plan.
The excitation signal transmission unit is respectively connected with the control module 4 and the probe 3, the excitation signal transmission unit generates a linear sweep frequency Chirp signal through excitation of the control module 4, the linear sweep frequency Chirp signal is transmitted to the probe 3 to excite the probe to generate ultrasonic waves, and the linear sweep frequency Chirp signal of the excitation signal transmission unit is also transmitted to the voltage detection and processing unit;
the voltage detection and processing unit respectively comprises:
the voltage detection module 7 is connected with the excitation signal transmission unit and the silver-plated copper electrode in the detection water tank 1 simultaneously and used for receiving a linear sweep Chirp signal from the excitation signal transmission unit and an electrode voltage signal from the conductivity front-end detection unit, the voltage detection module 7 further comprises an -th impedance matching module 71, a -th ADC acquisition module 72 and a -th preamplifier module 73 which are sequentially connected, the -th impedance matching module 71, the -th ADC acquisition module 72 and the -th preamplifier module 73 respectively carry out signal processing on the electrode voltage signal and the linear sweep Chirp signal, wherein the -th impedance matching module 71 is electrically connected with the detection water tank 1 and the power distribution module 10, and the -th preamplifier module 73 is connected with the impedance matching module 81.
The conductivity calculation module 8 is configured to receive the electrode voltage signal and the linear frequency sweep Chirp signal that are processed by the voltage detection module 7, trigger the trigger signal transmitted by the control module 4 to perform conductivity calculation processing on the electrode voltage signal and the linear frequency sweep Chirp signal, obtain a conductivity curve of an excitation point of a single sample 2 to be measured after processing the signals, and draw a conductivity distribution diagram of the interior of the sample 2 to be measured according to the conductivity curve of series of excitation points, where the conductivity calculation module 8 specifically includes:
the impedance matching module 81 is connected with the voltage detection module 7 and is used for performing impedance matching on the electrode voltage signal and the linear sweep frequency Chirp signal from the voltage detection module 7;
the ADC acquisition module 82 is connected to the impedance matching module 81, and is configured to convert the two paths of signals processed by the impedance matching module 81 into corresponding digital signals through an analog-to-digital converter;
the pre-amplification module 83 is connected with the ADC acquisition module 82 and is configured to amplify digital signals obtained by processing the two paths of signals by the ADC acquisition module 82;
a mean value processing module 84 connected to the pre-amplification module 83 for performing mean value processing on the amplified digital signal;
the band-pass filtering module 85 is connected with the mean value processing module 84 and is used for performing band-pass filtering processing on the digital signals after mean value processing;
a digital dot multiplication module 86 connected to the band-pass frequency wave module 85 for performing digital dot multiplication on the digital signal after the band-pass filtering;
a low-pass filtering module 87 connected to the digital dot product module 86 for performing low-pass filtering processing on the digital signal after the digital dot product processing;
the FFT conversion module 88 is connected with the low-pass filtering module 87 and used for converting the digital signals processed by the low-pass filtering module 87 into intermediate frequency signals;
the scale conversion and peak detection module 89 is connected with the FFT conversion module 88 and is used for obtaining the conductivity curve of a single excitation point of the sample 2 to be measured through the intermediate frequency signal;
the imaging processing module 90 is connected with the th display module 12, the two-dimensional conductivity distribution graph drawn by the imaging processing module 90 is displayed on the th display module 12, the th display module 12 is also used for displaying the state information of the voltage detection module 7, the conductivity calculation module 8 is also connected with the th input module 13, and the th input module 13 is used for inputting conductivity calculation instructions and modes required to be displayed by the th display module 12.
The excitation signal delivery unit includes:
the signal generation module 9 is used for generating a linear frequency sweep Chirp signal by triggering the trigger signal transmitted by the control module 4;
the power distribution module 10 is used for respectively distributing the linear frequency sweep Chirp signals generated by the signal generation module 9 to the power amplification module 11 and the voltage detection module 7;
and the power amplification module 11 is used for performing power amplification on the linear frequency sweep Chirp signal from the power distribution module 10 and then transmitting the linear frequency sweep Chirp signal to the probe 3 so as to excite the probe 3 to generate ultrasonic waves and further generate local particle vibration in the measured sample.
In the method for performing two-dimensional imaging by using the conductivity imaging system, as shown in fig. 9, the probe performs uniform step scanning in the X-axis direction to obtain a two-dimensional conductivity distribution map of the sample 2, wherein the Z-axis direction is a direction from the surface of the sample 2 to the bottom of the detection water tank 1, the X-axis direction is a horizontal direction, and a step position in the Z-axis direction is Z1，z2……zmStepping position in X-axis direction by X1，x2……xnExciting a sample to be measured at a focusing point by a focusing probe 3 to generate particle vibration at the focusing point, separating positive and negative charges by a magnetostatic field action, that is, a Lorentz force, by vibrating particles under the action of a magnetostatic body, detecting magnetoacoustic voltage signals generated at both sides of the sample by pairs of electrodes closely attached to both sides of the sample and orthogonal to both the magnetostatic field direction and the probe excitation direction, combining an ultrasonic excitation source signal and the detected magnetoacoustic voltage signalsThe voltage signal is used for obtaining the conductivity amplitude at the focus point, and the method specifically comprises the following steps:
as shown in fig. 10, firstly, the number of conductivity amplitudes that need to be extracted at the focus point and the adjacent symmetric point at each excitation points is obtained through calculation of the conductivity calculation module, i.e. a constant K, where K is a constant calculated by calculation platforms, and is determined by factors such as the step length in the Z-axis direction, the number m of times of sweep excitation in the Z-axis direction, the ADC of the system is determined by using the frequency, the sound velocity c, and the width T during linear sweep, and the constant K calculated at the excitation point by the conductivity calculation module is obtained after the input instruction of the input module is received by the conductivity calculation platform, and is determined after the system setting parameters are determined, and K is a constant value during each steps of motion excitation, and then the probe 3 is controlled to be focused (x is a1，z1) At the position point, the circle in the figure is an excitation position point q, the distance between the probe 3 and the focus point is constant and 5cm (the probe is focused by 5cm, and other values can be also used), the position point is imaged through a conductivity imaging system, and the position is obtained as (x)1，z1) The conductivity curve at excitation and extracting z on the curve1The magnetic acoustic conductivity values of the focus point and the adjacent symmetrical points (1 focus point + k-1 adjacent symmetrical points) move the probe in the Z-axis direction and make the focus of the probe located at (x)1，z2) Position, then through a conductivity imaging system in (x)1，z2) Is imaged to obtain z2The conductivity curve at excitation and extracting z on the curve2K magneto-acoustic conductivity values of the focus point and the adjacent symmetrical point, repeating the above steps to obtain the value in z3，z4……znThe magneto-acoustic conductivity values of the focus point and the adjacent symmetrical point are extracted, the conductivity values of k × m focus points and the adjacent symmetrical point are extracted, the th conductivity curve is obtained, and the conductivity curve is obtained according to the above-mentioned value in x1A step of acquiring magneto-acoustic conductivity values in the Z-axis direction of the site, controlling the probe 3 in the x-direction2，x3……xnMoving the sites in the Z-axis direction to obtain the conductivity values of the sites in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k m n conductivity values, and combining the positions of the excitation points of the probes and corresponding calculationAnd (4) obtaining a two-dimensional conductivity distribution map on the XZ plane.
The following formula is used for a single excitation site:
1. sending linear excitation linear frequency sweep Chirp signals to two ends of an ultrasonic probe:
Figure BDA0001736714500000161
2. the received voltage signal detected by for a silver-plated copper electrode against the surface of the sample being measured can be expressed as:
Figure BDA0001736714500000162
3. through carrying out digital coherent demodulation on a transmitting signal and a receiving signal, namely at every excitation point positions, transmitting 10 Chirp excitation signals through a signal generator module, simultaneously receiving 10 linear sweep frequency Chirp signals through a verasonics system, (in the process of acquiring the transmitting signal and the receiving signal, a digital band-pass filter is passed through by the verasonics), respectively carrying out 2-3Mhz band-pass filtering and ten times mean processing on the transmitting signal and the receiving signal, then carrying out digital dot multiplication, and then passing through a 0.6MHz low-pass filter, obtaining a difference frequency signal of the transmitting signal and the receiving signal, namely an intermediate frequency, wherein the intermediate frequency change generated in a conductivity discontinuous area is related to the depth of the excitation position, and the expression of dot multiplication of the transmitting signal and the receiving signal is as follows:
Figure BDA0001736714500000163
the low-pass filtered intermediate frequency signal is proportional to:
4. intermediate frequency signal (difference frequency (difference in frequency) of transmission and excitation signals):
5. theoretical axial resolution (axial resolution Δ R obtained by the device of the invention)
Figure BDA0001736714500000172
In the above formula: starting frequency: f. of02MHz, probe center frequency 2.5MHz, bandwidth: Δ f 1MHz, chirp continuous wave duration: t1000 μ s, the farthest distance of the probe to the boundary of the biological tissue (or phantom): r ═ 15cm, speed of propagation of acoustic waves in biological tissues (or mimetics): and c 1540 m/s.
The specific functions of the modules involved in the present invention are explained below:
a control module: the device is used for controlling the movement of the focus position of the probe, so that the focus is scanned in an XZ direction in a stepping mode, and meanwhile, the device is also used for generating two trigger signals, wherein the trigger signal 1 is used for triggering the signal generation module to generate a linear sweep frequency signal, and the trigger signal 2 is used for triggering the conductivity calculation module to perform conductivity calculation processing. The control module presets parameter information required by the excitation source such as pulse width time, sweep frequency start, termination frequency, center frequency, delay time, repetition period and the like required by the signal generator, and can also modify parameters required by the signal generation module through the control module, send the parameters to the signal generation module for signal generation, and start and close the signal generation module through the trigger signal 1. The present invention uses the MC600 as a control module. But is not limited to the control module.
A second input module: the input module is used for inputting control instructions and preset scanning plans and is carried out by touching, a mouse, keys and the like.
A second display module: the system is used for displaying position data, a scanning plan and a scanning progress of the motion control platform, the control module receives information such as an instruction, a trigger signal state and a control module state, and the received control module state information is fed back through the module. Preferably, an 8-inch Divingdus screen with touch function is used for display.
A signal generation module: after receiving information required by the excitation source, such as pulse width time, sweep frequency start, termination frequency, center frequency, delay time, repetition period and the like sent by the control module, the signal generation module generates a linear sweep frequency continuous wave excitation signal, namely a linear sweep frequency Chirp signal, and starts or cuts off a signal output port signal by receiving a trigger signal 1, so as to start or close the excitation signal source. For generating the chirp continuous wave signal required for detection. In this embodiment, the signal generator is generated by a Direct Digital Synthesizer (DDS), which has the advantages of low cost and power consumption, high resolution, and fast conversion time. In practical application, preferably, the method is realized by adopting an AD9952DDS chip with modulation functions of amplitude modulation, frequency modulation, phase modulation and the like and an on-chip D/A converter, and can also adopt an internal program of a Verasonics system to synthesize a chirp excitation signal with 2-3MHz, a bandwidth of 1Mhz, an adjustable sweep frequency time of 100 and 2000us and an amplitude of 200 mv.
And an th input module for inputting conductivity calculation command and required display mode of th display module and feeding back the received control module state information through the module.
display module for displaying conductivity calculation result, voltage detection module status and other information, which can be input module such as keyboard, mouse, touch screen and so on.
The power distribution module is used for distributing the linear sweep frequency excitation signals generated by the signal generation module, paths of the distributed signals are sent to the power amplification module and then sent to the ultrasonic power probe, and the other paths of the distributed signals are sent to the voltage detection module for ADC acquisition and subsequent signal processing.
The power amplification module is used for carrying out power amplification on the excitation signal after passing through the power distribution module and then sending the excitation signal to the ultrasonic excitation probe, the power amplification module is adjustable by adopting 0-60DB, and is fixed to carry out power amplification on the ultrasonic excitation signal by using 53 DB.
A probe: the ultrasonic water immersion focusing power probe is used for carrying out high-power ultrasonic excitation on a test sample, so that the ultrasonic waves cause particle vibration in a tissue body, the sample in a static magnetic field generates charge separation under the action of Lorentz force, and finally the charge is accumulated on an electrode to form a weak voltage signal. The probe adopted by the invention is a high-power ultrasonic excitation probe with the bandwidth of 1.8-3.5MHz and the fixed focusing depth of 5cm, can be immersed in water, and has the excitation power of 2W, preferably, a CDC10963 probe of Imasonic corporation in France is adopted, and an immersion focusing high-power excitation probe of Blatek corporation in America can also be adopted. And the probe needs 50 ohm impedance matching and magnetic shielding treatment. The invention adopts the focus point of the focus probe to carry out point-by-point stepping sweep frequency excitation on the imitation body.
The motion control platform is used for controlling the ultrasonic probe to focus on a designated focus point to perform step scanning along a probe excitation direction (Z-axis direction), step length in the Z-axis direction is set to be 2 every time, the ultrasonic probe focus point is controlled to perform step scanning along an electrode pair direction (X-axis direction), movement step length in the direction is set to be l, in the probe point-by-point movement process, a probe focus is firstly set on a certain point A on the X-axis, then the probe focus point sequentially performs step scanning movement downwards along the Z-axis, after the probe finishes scanning on the Z-axis, the probe returns to the original A position of the Z-axis, the probe moves to a lower position B along the X-axis by controlling the step length l, and sequentially performs step scanning movement downwards along the Z-axis, step length d each time is until the probe focuses on the Z-axis direction, the probe focus point is controlled to move to the position of the initial B point, the probe horizontally moves to the step length l on the X-axis again, in the subsequent process, the scanning process is performed by controlling the step scanning movement step length d along the Z-axis, the Z-axis until the probe focus point is started, and the control module is triggered to generate a step movement control signal, and then the control module, and the control module is triggered to generate a step control module, and the step movement control module.
The conductivity calculation module is used for calculating the conductivity of a sample, the method comprises the steps of obtaining an excitation signal and an electrode voltage signal after a power distribution module through a voltage detection module, respectively carrying out impedance matching, ADC (analog to digital converter) acquisition, preamplification, mean value processing and band-pass filtering on the two paths of signals, then carrying out digital point multiplication and low-pass filtering, further carrying out FFT (fast Fourier transform) conversion to obtain an intermediate frequency signal, obtaining a conductivity curve of a phantom at a single excitation point in the Z axis direction through scale conversion and peak detection, obtaining m conductivity curves after m times of stepping excitation in the Z axis direction, then obtaining m conductivity curves through the conductivity calculation module, extracting k conductivity values of each focusing excitation point and adjacent symmetrical points through the conductivity calculation module, synthesizing conductivity curves in the Z axis direction by combining probe position information, then moving step lengths in the X axis, repeating the operation to obtain a second synthesized conductivity curve, sending a motion stop motion instruction to the motion control module until n conductivity curves are synthesized, simultaneously generating a trigger signal 2 through the control module, enabling the conductivity calculation module to calculate a linear conductivity curve according to the X axis stepping and the two-dimensional conductivity curve, and carrying out interpolation on the Verason the two-dimensional conductivity curve, and carrying out calculation on the linear interpolation calculation of the linear ason the Verason the ason the two.
In addition, the conductivity calculation module can also automatically adjust the ADC and the impedance adjustment module of the voltage detection module and detect the state of the ADC and the impedance adjustment module.
The voltage detection module: the voltage detection module is used for carrying out impedance matching, ADC acquisition, preamplification and other processing on the excitation signal, and simultaneously carrying out impedance matching, ADC acquisition and preamplification processing on the electrode voltage signal, and feeding back the state information of the voltage detection module to the control and calculation module.
In order to reduce the influence of random noise on the imaging resolution, as shown in fig. 8, at each focus excitation point, the transmission signal and the reception signal are acquired 10 times, and are averaged 10 times and then processed by a corresponding algorithm to obtain a conductivity curve, where g denotes a lower interface, i denotes a lower interface, k denotes a final focus position, o denotes an upper interface peak, p denotes a lower interface peak, and h denotes a thickness of the sample 2 to be measured.
Fig. 8 is a graph showing changes in the amplitude of two conductivity change interfaces of a uniform measured sample 2 after single focus excitation, 10 conductivity graphs are obtained at 10 different focus excitation points, and the two peak values on each conductivity graph represent the conductivity amplitude change conditions of the upper and lower interfaces of the measured sample 2 when the measured sample 2 is excited at different excitation points, and the average value of the 10-time amplitude values of the upper interface i is similar to the average value of the 10-time amplitude values of the lower interface g.
The two-dimensional conductivity distribution diagram obtained on the XZ plane is described below with 30 focusing points on the Z axis, namely, 30 conductivity curves are obtained by dynamic focusing step excitation 30 times in the Z axis direction, the conductivity curves are sequentially arranged on the horizontal axis, and four interfaces shown in fig. 3 are obtained by an image processing method, the horizontal data in fig. 3 is the frequency of step sweep in the Z axis direction, it can be seen that the phantom is represented by interface a, second interface b, third interface c and fourth interface d from top to bottom times, and the conductivity amplitudes on each interfaces are extracted and an average value is removed, the average value is used as the conductivity amplitude of the corresponding interface position, and the four conductivity curves are converted into position information in the Z axis direction according to the parallel line imaging principle, and then the initial position point is combined, so that a more accurate conductivity curve with the Z axis direction can be obtained, and similarly, the probe is moved in the X axis direction, the above operations can be repeated, so that another conductivity curve along the Z axis direction can be obtained, and the two-dimensional conductivity distribution diagram can be obtained by step sweep in the X axis n, and the conductivity curve can be combined with the conductivity curve, and the conductivity curve can be obtained.
The measured sample 2 is not dug, the motion mode of the probe is shown in fig. 4, fig. 4 is a structural diagram of position change of the probe moving from an th starting excitation position e to a final focusing excitation position f in the measured sample 2 in a stepping mode, fig. 5 is a synthesized conductivity curve graph obtained by controlling the probe to focus on a th starting excitation position e above the measured sample 2 and performing stepping sweep excitation to the final focusing excitation position f, wherein the X value represents an X-axis coordinate, the Y value represents a conductivity value of the point, the th peak value represents a th interface a, namely an upper interface, the second peak value represents a fourth interface d, namely a lower interface or a bottom interface, and the X-axis depth represents the distance between the th interface and the second interface.
The measured sample 2 is provided with a hole 6, four layers of conductivity change interfaces can be obtained, the motion mode of the probe is shown in fig. 6, fig. 6 is a synthetic conductivity graph obtained by controlling the probe to focus on the th starting excitation position above the measured sample to move to the final focusing excitation position in a stepping mode, and the position of the probe focus position is changed schematically, as shown in fig. 6, the probe is controlled to focus on the th starting excitation position e above the measured sample 2 to excite in a stepping mode to the final focusing excitation position f (the amplitude represents the interface position, the th peak represents the th interface a, the second peak represents the second interface b, wherein the X value represents the X-axis coordinate, the Y value represents the conductivity value of the site, the X-axis depth represents the distance between the th interface a and the second interface b, the third peak value of the third interface c can be obtained in turn, the fourth peak value of the fourth interface d can be obtained at the conductivity change interface, the peak value can be related to the conductivity change position, the th peak value is related to the size of the fourth peak value, the approximate to the third peak value is the , namely, the simulated thickness of the measured sample 852.
The method for carrying out three-dimensional imaging by using a conductivity imaging system comprises the steps of carrying out uniform stepping scanning on a probe 3 in the Z-axis direction, the Y-axis direction and the X-axis direction to obtain a two-dimensional conductivity distribution map of a detected sample 2, wherein the Z-axis direction is the direction from the surface of the probe to the bottom of a detection water tank 1, the X-axis direction is the horizontal direction, the Y-axis direction is the vertical direction vertical to the X-axis direction, and the stepping position point in the Z-axis direction is Z1，z2……zmStepping position in X-axis direction by X1，x2……xnY is the stepping position in the Y-axis direction1，y2……ypThe specific three-dimensional imaging process comprises the following steps:
first, the probe is controlled at the above-mentioned position x1, x2，x3……xnMoving the sites in the Z-axis direction to obtain the conductivity values of the sites in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k m n conductivity values, and combining the probe excitation point position and corresponding algorithm to obtain the X plane passing through y1And then controlling the probe focus point (x)n，y1， zm) Return motion first starts with excitation point (x)1，y1，z1) Then the focusing point of the probe is controlled to step steps in the Y-axis direction to (x)1，y2，z1) And then repeating the process of obtaining the two-dimensional conductivity histogram, i.e. while the probe is at x1，x2，x3……xnMoving the sites in the Z-axis direction to obtain the conductivity values of the sites in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k m n conductivity values, and combining the probe excitation point position and corresponding algorithm to obtain the X-Z plane passing through y2A two-dimensional conductivity profile of. And by analogy, when the probe is step-scanned in the Y-axis direction for p times, the probe moves to (x)m，yp，zn) And then obtaining two-dimensional conductivity distribution maps of p XZ planes, and combining Y-axis excitation position information, namely reconstructing a three-dimensional conductivity distribution map on an XYZ space through k m n p conductivity values.
The XYZ directions represent the directions of the magnetic field, the ultrasonic excitation direction and the electrode detection direction which are perpendicular to each other in pairs, and for convenience of description and understanding, X represents the horizontal direction, Z represents the vertical direction, and Y represents the direction perpendicular to the XZ plane, but are not limited to the above description.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. Medical multi-focus imaging system, characterized by: the device comprises a conductivity front end detection unit, a control unit, an excitation signal transmission unit and a voltage detection and processing unit:
the conductivity front end detecting unit includes a conductivity detecting unit,
the detection water tank (1) is used for containing a sample (2) to be detected, a silver-plated copper electrode (7) is arranged inside the detection water tank (1), and the silver-plated copper electrode (7) is arranged vertical to the bottom of the detection water tank (1);
the static magnetic field generating device (8) comprises two static Ru-Fe-B magnets and a C-shaped bracket, wherein the plate surfaces of the two static Ru-Fe-B magnets are oppositely arranged on the two sides of the detection water tank (1);
the probe (3) is an ultrasonic linear array probe, extends to the surface of the measured sample (2), and is used for providing ultrasonic waves required by high-power ultrasonic electronic focusing excitation on the measured sample (2);
the control unit comprises a control unit and a control unit,
the control module (4) is used for controlling the probe (3) to perform stepping excitation motion through the motion control platform (5), and the control module (4) is used for triggering the excitation signal transmission unit to generate a linear sweep frequency Chirp signal and triggering the voltage detection and processing unit to perform conductivity calculation processing;
the motion control platform (5) is used for controlling the probe (3) to perform scanning motion at a specified focus point and feeding back the current position information of the probe (3) in the motion process to the control module (4);
the excitation signal transmission unit is respectively connected with the control module (4) and the probe (3), the excitation signal transmission unit generates a linear sweep frequency Chirp signal through excitation of the control module (4), the linear sweep frequency Chirp signal is transmitted to the probe (3) to excite the probe to generate ultrasonic waves, and the linear sweep frequency Chirp signal of the excitation signal transmission unit is also transmitted to the voltage detection and processing unit;
the voltage detection and processing units respectively comprise a voltage detection unit,
the voltage detection module (7) is connected with the excitation signal transmission unit and the detection water tank (1) and is used for processing a linear sweep frequency Chirp signal from the power distributor of the excitation signal transmission unit and an electrode voltage signal from the detection conductivity front-end detection unit;
and the conductivity calculation module (8) is used for receiving the electrode voltage signal and the linear sweep frequency Chirp signal which are processed by the voltage detection module (7), triggering the electrode voltage signal and the linear sweep frequency Chirp signal to perform conductivity calculation processing by using a trigger signal transmitted by the control module (4), obtaining a conductivity curve of an excitation point of a single tested sample (2) after processing the signals, and drawing an internal conductivity distribution diagram of the tested sample (2) according to the conductivity curve of series of excitation points.
2. A medical multi-focus imaging system as claimed in claim 1, wherein: the excitation signal delivery unit includes:
the signal generation module (9) is used for triggering the triggering signal transmitted by the control module (4) to generate a linear frequency sweep Chirp signal;
the power distribution module (10) is used for distributing the linear frequency sweep Chirp signals generated by the signal generation module (9) to the power amplification module (11) and the voltage detection module (7) respectively;
and the power amplification module (11) is used for transmitting the linear sweep Chirp signal from the power distribution module (10) to the probe (3) after power amplification so as to excite the probe (3) to generate ultrasonic waves.
3. A medical multi-focus imaging system as claimed in claim 1, wherein: the conductivity calculation module (8) further comprises:
the impedance matching module (81) is connected with the voltage detection module (7) and is used for performing impedance matching on the electrode voltage signal and the linear sweep frequency Chirp signal from the voltage detection module (7);
the ADC acquisition module (82) is connected with the impedance matching module (81) and is used for converting the two paths of signals processed by the impedance matching module (81) into corresponding digital signals through an analog-to-digital converter;
the pre-amplification module (83) is connected with the ADC acquisition module (82) and is used for amplifying digital signals obtained by processing the two paths of signals through the ADC acquisition module (82);
the mean value processing module (84) is connected with the pre-amplification module (83) and is used for carrying out mean value processing on the amplified digital signals;
the band-pass filtering module (85) is connected with the mean value processing module (84) and is used for carrying out band-pass filtering processing on the digital signals after the mean value processing is finished;
the digital dot multiplication module (86) is connected with the band-pass frequency wave module (85) and is used for carrying out digital dot multiplication on the digital signals subjected to band-pass filtering;
the low-pass filtering module (87) is connected with the digital dot multiplication module (86) and is used for performing low-pass filtering processing on the digital signals subjected to the digital dot multiplication processing;
the FFT conversion module (88) is connected with the low-pass filtering module (87) and is used for converting the digital signals processed by the low-pass filtering module (87) into intermediate frequency signals;
the scale conversion and peak detection module (89) is connected with the FFT conversion module (88) and is used for obtaining the conductivity curve of a single excitation point of the tested sample (2) through the intermediate frequency signal;
and the imaging processing module (90) is connected with the scale conversion and peak detection module (89), acquires the conductivity curve of the required excitation point obtained by the scale conversion and peak detection module (89), and draws a conductivity distribution diagram according to the conductivity curve of the required excitation point.
4. The medical multi-focus imaging system of claim 2, wherein the voltage detection module (7) further comprises an th impedance matching module (71), a th ADC acquisition module (72) and a th preamplifier module (73) connected in sequence, the th impedance matching module (71), the th ADC acquisition module (72) and the th preamplifier module (73) respectively perform signal processing on the electrode voltage signal and the linear swept Chirp signal, wherein the th impedance matching module (71) is electrically connected with the silver-plated copper electrode and power distribution module (10), and the th preamplifier module (72) is connected with the impedance matching module (81).
5. The medical multi-focus imaging system as set forth in claim 3, wherein the imaging processing module (90) is connected to the th display module (12), the two-dimensional conductivity distribution map drawn by the imaging processing module (90) is displayed on the th display module (12), and the th display module (12) is further used for displaying the status information of the voltage detection module (7).
6. A medical multi-focus imaging system as claimed in claim 5, wherein the conductivity calculation module (8) is further connected to an th input module (13), and the th input module (13) is used to input conductivity calculation instructions and modes to be displayed by the th display module (12).
7. A medical multi-focus imaging system as claimed in claim 1, wherein: the control module (4) is also connected with a second display module (14), and the second display module (14) is an 8-inch DivingDGUS screen with a touch function.
8. A medical multi-focus imaging system as claimed in claim 1, wherein: the control module (4) is also connected with a second input module (15), and the second input module (15) is used for inputting a control instruction and a preset scanning plan.
9. The method for imaging biological tissues by using the medical multi-focus imaging system as claimed in claim 1, wherein the probe (3) performs uniform step scanning in the Z-axis direction and the X-axis direction to obtain the two-dimensional conductivity distribution map of the sample (2) to be measured, wherein the Z-axis direction is the direction from the probe (3) to the bottom of the water tank (1), the X-axis direction is the horizontal direction, and the step position in the Z-axis direction is Z1，z2……zmStepping position in X-axis direction by X1，x2……xnThe method specifically comprises the following steps:
firstly, after receiving an input instruction of an th input module (13) through a conductivity calculation platform, obtaining a constant k calculated by the conductivity calculation module at the excitation site, wherein k is constants calculated by the calculation platform and is determined by a step length in the Z-axis direction, a frequency m of sweep excitation in the Z-axis direction, an acquisition frequency of an ADC (analog to digital converter) acquisition module (82), an acoustic velocity c and a linear sweep time width T factor, and when a control probe (3) is focused on (x), the control probe is controlled to be in a state of focusing on (x)1，z1) At the site, imaging is performed at the site by a conductivity imaging system, obtaining a signal at (x)1，z1) The conductivity curve at excitation and extracting z on the curve1Moving the probe in the Z-axis direction with the focus of the probe at (x) and k magneto-acoustic conductivity values at the focus and adjacent to the symmetry point1，z2) Position, then through a conductivity imaging system in (x)1，z2) Is imaged to obtain z2The conductivity curve at excitation and extracting z on the curve2K magneto-acoustic conductivity values of the focus point and the adjacent symmetrical point, repeating the above steps to obtain the value in z3，z4……zmFocusing point and magnetic-acoustic conductivity values adjacent to the symmetrical point, extracting k × m focusing points and conductivity values adjacent to the symmetrical point, obtaining synthesized conductivity curve along Z axis according to the position information of each focusing point, and calculating the conductivity curve according to the above-mentioned conductivity curve1A step of acquiring magneto-acoustic conductivity values in the Z-axis direction of the site, controlling the probe (3) in the x-direction2，x3……xnAnd moving the sites in the Z-axis direction to obtain conductivity values of the sites in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k multiplied by m multiplied by n conductivity values, and combining the positions of probe excitation points and corresponding algorithms to obtain a two-dimensional conductivity distribution map on an XZ plane.
10. Method for imaging biological tissue using a medical multi-focus imaging system according to claim 1, wherein the probe (3) performs uniform step scanning in the Z-axis direction, the Y-axis direction and the X-axis direction to obtain three-dimensional samples (2) to be measuredThe conductivity distribution diagram is shown, wherein the Z-axis direction is the direction from the probe (3) to the bottom of the detection water tank (1), the X-axis direction is the horizontal direction, the Y-axis direction is the vertical direction vertical to the X-axis, and the stepping point in the Z-axis direction is Z1，z2……zmStepping position in X-axis direction by X1，x2……xnY is the stepping position in the Y-axis direction1，y2……ypThe method specifically comprises the following steps:
first, the probe is controlled to be at x1Site, x2，x3……xnMoving the position points in the Z-axis direction to obtain the conductivity values of the position points in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k multiplied by m multiplied by n conductivity values, and combining the position of the probe excitation point and a corresponding algorithm to obtain the y-passing conductivity curve on the XZ plane1And then controlling the probe focus point (x)n，y1，zm) Return motion first starts with excitation point (x)1，y1，z1) Then the focusing point of the probe is controlled to step steps in the Y-axis direction to (x)1，y2，z1) And then repeating the process of obtaining the two-dimensional conductivity histogram, i.e. while the probe is at x1，x2，x3……xnMoving the position points in the Z-axis direction to obtain the conductivity values of the position points in the Z-axis direction, obtaining n synthesized conductivity curves along the Z-axis direction, totaling k multiplied by m multiplied by n conductivity values, and combining the position of the probe excitation point and a corresponding algorithm to obtain the y-passing conductivity curve on the XZ plane2A two-dimensional conductivity profile of. And by analogy, when the probe is step-scanned in the Y-axis direction for p times, the probe moves to (x)m，yp，zn) And then, obtaining two-dimensional conductivity distribution maps of p XZ planes, and reconstructing a three-dimensional conductivity distribution map on an XYZ space by combining Y-axis excitation position information through k multiplied by m multiplied by n multiplied by p conductivity values.
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