CN209899435U - Probe for elastography - Google Patents

Abstract

The present application relates to a probe for elastography, the probe comprising: the excitation generating device is provided with a hollow structure; the scanning device is arranged in the hollow structure of the excitation generating device and used for transmitting a scanning signal to the material to be detected and receiving a feedback signal reflected by the material to be detected; and the connecting piece is fixedly connected with the excitation generating device and the scanning device respectively. Above-mentioned a probe for elastography, scanning device can not take place the motion along with the vibration that the excitation produced the device, has realized avoiding scanning device vibration in the measurement process under the circumstances that excitation signal intensity does not basically lose to improve scanning signal acquisition's stability, reduced scanning signal post-processing's complexity, and effectively promoted instantaneous elastography's success rate and measurement accuracy.

Description

Probes for elastography

technical field

The present application relates to the technical field of elastography, and in particular, to a probe for elastography.

Background technique

Liver cirrhosis is a major threat to human health, and millions of people worldwide die of cirrhosis-related diseases every year. Localized fibrosis of the liver is often an early sign of cirrhosis. In the early stage of liver fibrosis, liver lesions can be controlled by various means, thereby preventing the development of liver cirrhosis. However, because hepatic fibrosis only occurs in a local area of the liver in the early stage, it will not show obvious signs under ultrasound, and it is difficult to diagnose the early stage of fibrosis. In recent years, studies have shown that liver fibrosis can cause significant changes in the mechanical properties of the liver near the lesions. As fibrosis develops, the liver gradually becomes hard. Therefore, non-invasive, non-destructive and rapid in vivo characterization of liver mechanical properties has become the goal of many researchers.

At present, in the in vivo non-invasive measurement of liver mechanical properties, traditional techniques usually use transient elastography, shear wave elastography, and nuclear magnetic resonance elastography for imaging. Taking transient elastography as an example, transient elastography is a method for non-invasive quantitative characterization of the mechanical properties of human tissue in vivo by monitoring the propagation of elastic waves caused by mechanical excitation in the human body through an ultrasonic probe (A-ultrasound). The basic process of transient elastography is as follows: observe the patient's intercostal region with ordinary B-ultrasound, and find an axis suitable for the measurement of mechanical properties. Once found, mark it on the body surface. Put the probe against the intercostal space of the subject, and manually apply a certain pressure to the tissue, so that the probe is in close contact with the skin surface. Manually keep the probe position stable. The probe generates a displacement excitation signal that induces the propagation of near-field mechanical waves within the tissue. The vibrating element inside the probe drives the probe tip to generate a full-cycle sinusoidal pulse with a duration of 20ms. This vibration causes near-field mechanical waves to propagate with the excitation point as the center of the sphere. The ultrasonic transducer at the end of the probe begins to image below the axis of the probe, collects echo signals at a frame rate of about 5000 Hz, and uses a related algorithm to capture the change of the axial displacement of the particle on the axis below the probe with time. Field mechanical wave velocity. The near-field mechanical wave velocity is substituted into the near-field elastic wave theory, and the mechanical parameters of the tissue are obtained.

However, the instantaneous elastography technology in the traditional technology is greatly affected by the operator's operation when obtaining the measurement parameters, and the effective depth of the measurement is also relatively limited. There are large areas of the liver outside the effective diagnostic area, and the traditional instantaneous elastography technology It is difficult to confirm the tissue condition under the probe in situ. In addition, the excitation system of traditional transient elastography technology interferes with the imaging system. In conclusion, the defects of these traditional transient elastography technologies lead to low measurement accuracy of transient elastography.

Utility model content

Based on this, it is necessary to provide a probe for elastography in order to solve the technical problem of the low measurement accuracy of the instantaneous elastography of the above-mentioned traditional elastography technology.

A probe for elastography, the probe comprising:

an excitation generating device, the excitation generating device is provided with a hollow structure for applying displacement excitation on the surface of the material to be measured, so that a near-field wave is generated inside the material to be measured;

a scanning device, arranged in the hollow structure of the excitation generating device, for transmitting a scanning signal to the material to be tested, and receiving a feedback signal reflected by the material to be tested;

A connecting piece is respectively connected to the excitation generating device and the scanning device.

In one of the embodiments, the scanning device comprises an ultrasonic transducer or a photoacoustic scanner.

In one embodiment, at least one of the ultrasonic transducers is disposed in the hollow structure of the excitation generating device, and is used to transmit ultrasonic signals to the material to be tested and receive ultrasonic echoes reflected by the material to be tested. wave signal.

In one of the embodiments, the excitation generating device is a ring-shaped structure.

In one of the embodiments, the gap between the excitation generating device and the scanning device is 0.001mm-100mm.

In one embodiment, the probe further includes:

A filler, the filler is arranged in the gap between the scanning device and the excitation generating device.

In one embodiment, the probe further includes:

An actuating element, which is connected to the excitation generating device, is used for outputting a displacement waveform to the excitation generating device, so that the excitation generating device moves.

In one embodiment, the probe further includes:

a probe housing, the inner wall of the probe housing is connected with the connecting piece for accommodating the excitation generating device, the scanning device, the connecting piece, the filler and the actuating element.

In one embodiment, the probe further includes:

A buffer device, one end of the buffer device is connected to the connecting piece, and the other end of the buffer device is connected to the actuating element, and is used to cancel or weaken the force generated by the movement of the excitation generating device on the probe housing.

In one embodiment, the probe further includes:

a pressure sensor, which is connected to the connecting piece and the scanning device respectively, and is used for detecting the pressure between the scanning device and the material to be tested.

In one embodiment, the cross-sectional shape of the hollow structure is a circle, an ellipse, a rectangle, a star, a triangle or a distributed scattered point shape.

In one of the embodiments, the displacement waveform includes a single sine wave pulse, harmonic wave, triangular wave or broadband wave.

The above-mentioned probe for elastography includes an excitation generating device, a scanning device and a connector respectively connecting the excitation generating device and the scanning device, the excitation generating device is provided with a hollow structure, and the scanning device is arranged in the hollow structure of the excitation generating device It can be understood that the excitation generating device and the scanning device are arranged at intervals, so that the excitation generating device and the scanning device are spatially separated, that is, the working modes of the scanning device and the excitation generating device are not closely coupled, so that the scanning device will not follow the excitation The vibration of the device is generated and the movement occurs, so as to avoid the vibration of the scanning device during the measurement process without losing the strength of the excitation signal, thereby improving the stability of the scanning signal acquisition and reducing the complexity of the post-processing of the scanning signal. And effectively improve the success rate and measurement accuracy of transient elastography.

Description of drawings

FIG. 1 is a schematic structural diagram of a probe used for elastography in one embodiment;

Fig. 2 is the schematic diagram of scheme A (a) and scheme B (b) in one embodiment, the simplified models of both are axisymmetric models, and the dotted line is the symmetry axis of the model; the circle diagram is the front view of the probe, reflecting the probe Geometry;

Fig. 3 is a simulation result of near-field waves excited by probes of different shapes on bulk materials with different hardness (Young's modulus) in one embodiment. Changes in motivation time;

4 is a comparison of the amplitudes of signals generated by circular excitation and annular excitation in one embodiment, the horizontal axis is the depth, and the vertical axis is the extreme value of the displacement signal at the depth (using a logarithmic scale);

Figure 5 shows the extreme values of axial displacement signals at various depths when solid excitation (scheme A) and annular excitation (scheme B) are used to characterize materials with three moduli in one embodiment. (a) ^E =2KPa, (b) ^E=4KPa , (c) ^E=27KPa .

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

In one embodiment, referring to FIG. 1 , a probe for elastography is provided. The probe includes an excitation generating device 102 , a scanning device 104 , and a connector that is fixedly connected to the excitation generating device 102 and the scanning device 104 respectively. 106 , the scanning device 104 is spaced apart from the excitation generating device 102 . Further, the excitation generating device 102 is provided with a hollow structure, and the scanning device 104 is disposed in the hollow structure of the excitation generating device 102 . Wherein, the excitation generating device 102 is used to apply displacement excitation on the surface of the material to be measured, so that a near-field wave is generated inside the material to be measured. The scanning device 104 is used for transmitting a scanning signal to the material to be tested, and receiving a feedback signal reflected by the material to be tested, the feedback signal carrying the propagation information of the near-field wave inside the material to be tested. Alternatively, the material to be tested may be biological tissue.

Specifically, the excitation generating device 102 may be an excitation head. The scanning device 104 and the excitation generating device 102 are spaced apart means that there is a gap between the scanning device 104 and the excitation generating device 102, or it can be understood that there is no contact between them. In this way, the working mode of the scanning device 104 and the excitation generating device 102 There is no coupling relationship. For example, when the operator contacts the probe with the surface of the material to be tested, the excitation generating device 102 will vibrate relative to the surface of the material to be tested. At this time, the scanning device 104 is not affected by the vibration of the excitation generating device 102. Movement occurs, ie the scanning device 104 is always in contact with the surface of the material to be tested. It should be clear that the size of the gap is not limited in this embodiment, as long as the movement of the excitation generating device 102 does not affect the operation of the scanning device 104 . The separate design makes the probe more flexible, for example, the probe can also be used for the characterization of non-biological tissue soft materials.

Optionally, the gap between the scanning device 104 and the excitation generating device 102 is 0.001mm-100mm. In one embodiment, the gap between the scanning device 104 and the excitation generating device 102 is 0.001 mm. In another embodiment, the gap between the scanning device 104 and the excitation generating device 102 is 100 mm. In yet another embodiment, the gap between the scanning device 104 and the excitation generating device 102 is 0.01 mm. Optionally, a filler can be placed in the gap between the scanning device 104 and the excitation generating device 102, the filler can effectively block the movement of the scanning device 104 caused by the vibration of the excitation generating device 102, and ensure the scanning signal of the probe. Collection stability.

The above-mentioned probe for elastography includes an excitation generating device, a scanning device and a connector respectively connecting the excitation generating device and the scanning device, the excitation generating device is provided with a hollow structure, and the scanning device is arranged in the hollow structure of the excitation generating device It can be understood that the excitation generating device and the scanning device are arranged at intervals, so that the excitation generating device and the scanning device are spatially separated, that is, the working modes of the scanning device and the excitation generating device are not closely coupled, so that the scanning device will not follow the excitation The vibration of the device is generated and the movement occurs, so as to avoid the vibration of the scanning device during the measurement process without losing the strength of the excitation signal, thereby improving the stability of the scanning signal acquisition and reducing the complexity of the post-processing of the scanning signal. It is expected to improve the characterization accuracy and characterization success rate of materials, thereby effectively improving the success rate and measurement accuracy of transient elastography, which is beneficial to the early screening of liver fibrosis.

In addition, the separate design of the excitation generating device 102 and the scanning device 104 gives the probe a greater degree of freedom, which enables the probe to be used for macroscopic characterization of soft materials, and the depth of signal focus can be controlled by controlling the shape of the excitation head, thereby It helps to solve the problem of strong attenuation of near-field signals encountered by traditional techniques for material characterization.

Further, the probe further includes an actuating element 108 connected to the excitation generating device 102 for outputting a displacement waveform to the excitation generating device 102 so that the excitation generating device 102 moves. The actuating element 108 and the excitation generating device 102 constitute the excitation system of the probe. Optionally, the actuating element 108 may be an electric actuating element 108 or an actuating element 108 driven by other energy sources, which is not limited in this embodiment. Taking the electric actuating element 108 as an example, after detecting the electric signal, the electric actuating element 108 outputs a set displacement waveform, thereby causing the excitation generating device 102 to vibrate. Optionally, the set displacement waveform can be divided into multiple gears, such as single sine wave pulses of different frequencies (30-200Hz), harmonic waves, triangular waves, and even broadband arbitrary waves. And the frequency is not limited and can be selected according to actual needs. In this embodiment, since the excitation generating device 102 and the scanning device 104 do not interfere with each other, the output waveform of the excitation system can be more free, which is helpful for the characterization of the viscoelasticity of the material to be measured and the characterization of complex mechanical properties.

Optionally, in one embodiment, the excitation head generates one or more near-field waves propagating in the material to be measured through direct or indirect contact with the material to be measured. The shape of the near field wave over time can be arbitrary, but is more generally of the impulse, transitional or periodic (continuous, monochromatic) type. This vibration is usually obtained mechanically, but can also be obtained by radiation pressure, by ultrasonic hyperthermia, or by vibration in the body (heartbeat, pulse, etc.). Similarly, vibrations can also be obtained by means of an exciter head arranged outside the body.

Optionally, in one embodiment, the exciter head may be a low frequency oscillator or a motor. In order to make the material to be tested micro-deformed by external force or internal force, low-frequency low-amplitude vibration occurs through the exciter head, causing shear waves propagating into biological tissue and inducing micro-deformation.

In one embodiment, the exciter head is a low frequency oscillator. Specifically, in a low frequency oscillator, if the frequency of the shear wave is too high, the shear wave attenuation is too low, and if the frequency is too low, the diffraction effect is too strong, all of which are not conducive to the propagation of the shear wave. If the amplitude of the shear wave in the low frequency oscillator is too small, the propagation depth will be limited, and if the amplitude of the shear wave is too large, the human body will feel uncomfortable. Therefore, in a preferred embodiment, the vibration frequency generated by the low frequency oscillator is 10 Hz to 1000 Hz with an amplitude of 0.2 mm to 2 mm.

Optionally, in one embodiment, the above-mentioned scanning device 104 includes an ultrasonic transducer or a photoacoustic scanner. The number of ultrasonic transducers may be one or more, and a plurality of ultrasonic transducers constitute an ultrasonic transducer array. Optionally, the ultrasonic transducer array may be any one of linear array ultrasonic transducers, convex array ultrasonic transducers or phased array ultrasonic transducers. The number of photoacoustic scanners may be one or more, and a plurality of photoacoustic scanners constitute an array of photoacoustic scanners. Optionally, in one embodiment, the probe further includes a scanning device fixing member 105 , and the scanning device fixing member 105 is used to fix the scanning device 104 . Correspondingly, the fixing member for fixing the ultrasonic transducer is referred to as the ultrasonic transducer fixing member, and the fixing member for fixing the photoacoustic scanner is called the photoacoustic scanner fixing member 105 . The fixing method of the scanning device 104 to the scanning device fixing member 105 is not limited, and the scanning device 104 may be embedded in the scanning device fixing member 105 , or the scanning device 104 may be pasted on the scanning device fixing member 105 .

In one embodiment, the above-mentioned ultrasonic transducers may be coronal, annular, 2D matrix, linear or rib transducers, single-element transducers, three-element transducers, or star transducers, and the like.

In one embodiment, the above-mentioned excitation generating device 102 is provided with a hollow structure; at least one ultrasonic transducer is arranged in the hollow structure of the excitation generating device 102 for transmitting ultrasonic signals to the material to be tested and receiving reflections from the material to be tested The ultrasonic echo signal, wherein the ultrasonic echo signal carries the propagation information of the near-field wave inside the material to be tested.

Specifically, the cross-sectional shape of the hollow structure can be a circle, an ellipse, a rectangle, a star, a triangle or a distributed scattered point shape, and can also be other irregular shapes. As long as the shape can constitute a hollow structure, it belongs to the present application scope of protection. Wherein, the distributed scattered point shape refers to a shape formed by one after another of discrete point regions, and the scanning device 104 such as an ultrasonic transducer can be arranged in the point regions. The ultrasonic transducer is arranged in the hollow structure of the excitation generating device 102 , so that there is no coupling relationship between the ultrasonic transducer and the working mode of the excitation generating device 102 . Preferably, the excitation generating device 102 is an annular structure. Here, the simple and easy-to-understand ring-shaped excitation generating device 102 is used as an example for description. When the operator turns on the switch of the probe and applies a certain pressure to contact the probe with the surface of the material to be tested, at this time, the ring The excitation generating device 102 is also in contact with the surface of the material to be measured, and it will apply displacement excitation on the surface of the material to be measured, that is, to generate vibration, so as to excite a near field within the material to be measured similar to that excited by the transient elastography system. Wave. Furthermore, the ultrasonic transducer transmits ultrasonic signals to the material to be tested, and receives ultrasonic echo signals reflected by the material to be tested. These ultrasonic echo signals carry the propagation information of near-field waves inside the material to be tested, including near-field shearing The wave velocity, dispersion and other information of the shear wave.

Optionally, the above-mentioned ultrasonic transducer can be placed at the center of the hollow structure of the excitation generating device 102, or can be placed at other positions of the hollow structure of the excitation generating device 102, which can be placed according to actual needs. Do limit.

It should be clear that, taking a human or an animal as an example, the ultrasonic transducer is in contact with the body surface of the human or animal, thereby acquiring a two-dimensional ultrasonic image of the biological tissue. Accurate positioning is carried out through the two-dimensional ultrasound image obtained in real time by the ultrasonic transducer, and the probe is assisted and guided for precise positioning according to actual needs. Specifically, the position corresponding to the scan line at the middle position of the two-dimensional ultrasound image is the area to be detected. Provides precise localization for practical clinical transient elastography procedures.

In this embodiment, a hollow structure is formed on the excitation head, and the space released by the hollow structure allows the placement of imaging components such as the scanning device 104 or micro B-ultrasound. Exploration to the highest degree, avoiding non-uniform tissues such as large blood vessels; at the same time, the purpose of the axis alignment of the probe during use is achieved, and then the axis direction of the probe can be detected in real time to ensure that the obtained data is more accurate and effective. In addition, in this embodiment, the excitation generating device 102 with a hollow structure, such as a ring-shaped excitation generating device 102, is used, and the scanning device 104, such as a plurality of sets of ultrasonic transducers, is placed in the center of the ring, so as to separate the excitation and imaging from each other, and has the advantages of non-invasive, The advantages of fast, simple operation and low cost.

In one embodiment, the scanning device 104 may be disposed around the outer surface of the excitation generating device 102 . Wherein, the outer surface enclosed between the two end faces of the excitation generating device 102 is the outer surface of the excitation generating device 102 . Optionally, the excitation generating device 102 is a solid structure. The scanning device 104 is arranged around the outer surface of the excitation generating device 102 , and the scanning device 104 is not coupled to the working mode of the excitation generating device 102 . In this way, when the excitation generating device 102 applies displacement excitation on the surface of the material to be measured, vibration is generated, so that a near-field wave similar to that excited by a transient elastography system is excited inside the material to be measured. Furthermore, the scanning device 104 can be, for example, an ultrasonic transducer, which transmits ultrasonic signals to the material to be measured in the axial direction of the probe in a focusing manner, and receives ultrasonic echo signals reflected by the material to be measured. These ultrasonic echo signals carry The propagation information of the near-field wave inside the material to be measured, including the wave velocity and dispersion of the near-field shear wave.

Optionally, in one embodiment, the above-mentioned scanning device 104 can be arranged on both sides of the excitation head, for example, for the imaging operation of the rib area, since the rib has an elongated arcuate shape, the probe can be designed to match the shape of the rib. Similar structure, in this way, the scanning device 104 is arranged on both sides of the excitation head along the extending direction of the rib, so that the rib area can be imaged more effectively and conveniently. In one embodiment, the plurality of scanning devices 104 may be positioned on both sides of the exciter head by two positioning posts.

In one embodiment, the probe further includes a probe housing 110 for accommodating the internal structure of the probe, including the excitation generating device 102 , the scanning device 104 , the connecting member 106 and the like. The probe housing 110 can also protect the internal structure of the probe and facilitate the operation of the operator. Further, in one embodiment, the connector 106 is fixedly connected to the probe housing 110, so that the excitation generating device 102 and the scanning device 104 connected to the connector 106 are fixed to the probe housing 110 to avoid falling off. Optionally, the probe housing 110 may be made of materials such as plastic, metal or quartz.

Further, in one embodiment, the probe further includes a buffering device 112, the buffering device 112 is connected to the actuating element 108 and the connecting piece 106, respectively, for offsetting or weakening the force generated by the movement of the excitation generating device 102 on the probe housing 110 . Specifically, the buffering device 112 is responsible for buffering and reducing the force on the probe housing 110 caused by the movement of the excitation generating device 102 , so that the probe housing 110 is substantially stationary during the movement of the excitation generating device 102 . Optionally, the buffering device 112 may be a tension spring, a damping rod or a rubber strip. It should be clear that any device that can play a buffering role falls within the protection scope of the present application. The buffer device 112 is accommodated in the probe housing 110 .

Optionally, in one embodiment, the probe further includes a pressure sensor 114, and the pressure sensor 114 is respectively connected to the above-mentioned connector 106 and the scanning device 104, and is used to detect the pressure between the scanning device 104 and the material to be measured, so that the probe A certain pressure is maintained with the surface of the material to be tested, so as to ensure that the two are in close contact, so that the scanning signal generated by the scanning device 104 can effectively pass through the surface of the material to be tested. The pressure sensor 114 is accommodated in the probe housing 110 .

Optionally, in one embodiment, the probe further includes a protective film (not shown) covering the excitation generating device 102 and the scanning device 104 . This protective film not only protects the probe from damage, but also protects the material to be tested from any contamination by using a new protective film for each new operation of the material to be tested. Preferably, the protective film includes echo gel to ensure proper ultrasound coupling. Furthermore, in order to prevent the transfer of contaminants from one material under test to another material under test, the protective film is preferably disposable.

The following will combine actual cases and compare the results of the solution described in this application with the results of Fibrosan (traditional technology) through finite element simulation results, so as to illustrate the advantages of the solution described in this application.

From a mechanical point of view, the simplified mechanical models corresponding to the Fibroscan scheme (hereinafter referred to as scheme A) and the scheme described in this application (hereinafter referred to as scheme B) are shown in Figure 2(a) and Figure 2(b), respectively. The finite element method is used to model the two. The bulk material to be characterized is a half-space infinite homogeneous bulk material, the material constitutive relation is a linear elastic material, the Poisson's ratio ν=0.499977, and the material density ρ=1000kg/m ³ ; The cross-sectional shape of the exciter head in case A is a solid circle with a diameter of d=9mm; the cross-sectional shape of the exciter head in case B is a circular ring with an outer diameter of d=9mm; the motion of the exciter head is a sine wave, a sine wave The frequency is 50 Hz, and the peak-to-peak value of the vibration is 0.2 mm; the observation area is a cylinder with a radius of L=100 mm and a height of H=100 mm.

Abaqus, a commercial finite element software, was used to numerically simulate the propagation process of near-field waves in both cases, and the axial displacement component U _y on the model's symmetry axis was extracted. The time-space diagram of the axis node displacement U _y changing with time is shown in Figure 3. The motion process of the near-field wave in the depth direction of the wave front can be clearly seen from Fig. 3 . Fitting the displacement minimum point at each depth on the two-dimensional space-time map with a straight line can obtain the phase velocity of the near-field wave propagation, which can be substituted into the theoretical formula E=3ρc ² to invert the elastic modulus of the material. The results given by the numerical simulation are shown in Table 1. It can be seen that adopting the B scheme will not affect the inversion process of tissue elastic properties.

Table 1 Inversion results of Young's modulus of materials under two schemes (unit: KPa)

Note: The inversion process of Young's modulus is as follows: (1) In the depth range of 25-65mm, find the time corresponding to the displacement extreme value at each depth on the velocity space-time diagram shown in Figure 3, and calculate the time-depth scatter plot; (2) Fit the time-depth scatter plot with a straight line, and the fitting slope is the near-field wave propagation velocity V; (3) Invert the Young's mode of the material by the classical formula E=3ρc ² quantity.

The hollowing out of the center will reduce the energy input by the exciter into the tissue, which may reduce the signal-to-noise ratio. Since the near-field wave itself is strongly attenuated along the depth direction (Fig. 4), this energy loss needs to be tightly controlled. To do this, it is necessary to determine the relationship between the attenuation level of the signal and the knockout ratio. The extreme value of U _y at each depth in the wave propagation process is still extracted, and the relationship between the extreme value and the depth is made. It can be seen that adopting the B scheme can provide enough space for the ultrasonic transducer group with almost no loss of signal strength.

The above results have demonstrated that the ring excitation transient elastography can avoid the movement of the ultrasound probe during the imaging process with almost no loss of signal compared with Fibroscan, thereby reducing the complexity of signal processing and improving the application of this method in the early screening of liver fibrosis. Check the stability and success rate. In addition to liver fibrosis materials, this method can also be used for the characterization of soft materials. When used for soft material characterization, the design of the ring probe has more space because it is not limited by the complex structure of the human body. The following is also described with a finite element calculation example.

The material to be tested is an infinite uniform block, which is characterized by the schemes (a) and (b) in Figure 2. (a) The exciter parameters of the scheme: d=9mm; (b) the parameters of the ring exciter of the scheme: d _In =25mm, d=25.4mm (this parameter is selected to ensure that the size of the contact area in the two cases is consistent ). The excitation signal is still a sinusoidal signal with a peak-to-peak value of 0.2 mm. The Young's modulus of the material to be characterized is taken as 2KPa, 4KPa and 27KPa respectively, and the Poisson's ratio is still 0.499977. Similarly, U _y on the axis of the finite element calculation results is extracted and compared, and the results are shown in Figure 5. It can be seen that when the contact area is the same, the B scheme can obtain a strong signal in the deeper part of the area to be measured, and at the same time can avoid the movement of the A ultrasound probe during the characterization process, thereby improving the accuracy and stability of material characterization.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features It is considered to be the range described in this specification.

The above-mentioned embodiments only represent several embodiments of the present application, and the descriptions thereof are relatively specific and detailed, but should not be construed as a limitation on the scope of the utility model patent. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the appended claims.

Claims (12)

1. A probe for elastography, wherein the probe comprises: an excitation generating device, the excitation generating device is provided with a hollow structure for applying displacement excitation on the surface of the material to be measured, so that a near-field wave is generated inside the material to be measured; a scanning device, arranged in the hollow structure of the excitation generating device, for transmitting a scanning signal to the material to be tested, and receiving a feedback signal reflected by the material to be tested; A connecting piece is respectively connected to the excitation generating device and the scanning device. 2. The probe according to claim 1, wherein the scanning device comprises an ultrasonic transducer or a photoacoustic scanner. 3 . The probe according to claim 2 , wherein at least one of the ultrasonic transducers is arranged in the hollow structure of the excitation generating device, and is used for transmitting ultrasonic signals to the material to be tested and receiving all the ultrasonic signals. 4 . The ultrasonic echo signal reflected by the material to be tested. 4. The probe according to claim 1, wherein the excitation generating device is an annular structure. 5 . The probe according to claim 1 , wherein the gap between the excitation generating device and the scanning device is 0.001 mm-100 mm. 6 . 6. The probe according to claim 5, wherein the probe further comprises: A filler, which is arranged in the gap between the excitation generating device and the scanning device. 7. The probe according to any one of claims 1 to 6, wherein the probe further comprises: An actuating element, which is connected to the excitation generating device, is used for outputting a displacement waveform to the excitation generating device, so that the excitation generating device moves. 8. The probe according to claim 7, wherein the probe further comprises: a probe housing, the inner wall of the probe housing is connected with the connecting piece for accommodating the excitation generating device, the scanning device, the connecting piece, the filler and the actuating element. 9. The probe according to claim 8, wherein the probe further comprises: A buffer device, one end of the buffer device is connected to the connecting piece, and the other end of the buffer device is connected to the actuating element, and is used to cancel or weaken the force generated by the movement of the excitation generating device on the probe housing. 10. The probe according to any one of claims 1 to 6, wherein the probe further comprises: a pressure sensor, which is connected to the connecting piece and the scanning device respectively, and is used for detecting the pressure between the scanning device and the material to be tested. 11 . The probe according to claim 1 , wherein the cross-sectional shape of the hollow structure is a circle, an ellipse, a rectangle, a star, a triangle or a distributed scattered point shape. 12 . 12. The probe according to claim 7, wherein the displacement waveform comprises a single sine wave pulse, harmonic wave, triangular wave or broadband wave.

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