CN209899435U - Probe for elastography - Google Patents
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- CN209899435U CN209899435U CN201920166336.3U CN201920166336U CN209899435U CN 209899435 U CN209899435 U CN 209899435U CN 201920166336 U CN201920166336 U CN 201920166336U CN 209899435 U CN209899435 U CN 209899435U
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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
Technical Field
The application relates to the technical field of elastography, in particular to a probe for elastography.
Background
Cirrhosis is a major threat to human health, with millions of people dying from cirrhosis-related disease worldwide each year. Localized liver fibrosis is often an early sign of cirrhosis. In the early stage of hepatic fibrosis, liver lesions can be controlled by various means, so that the progress of the liver lesions to cirrhosis can be restrained. However, since the initial stage of hepatic fibrosis occurs only in a localized area of the liver, no significant signs are shown under ultrasound, and the initial stage of fibrosis is difficult to be diagnosed. In recent years, research has shown that liver fibrosis can cause significant changes in the mechanical properties of the liver near the lesion. With the development of liver fibrosis, the liver becomes gradually hard. Therefore, noninvasive, non-destructive, and rapid in-vivo characterization of liver mechanical properties is a goal of many researchers' efforts.
At present, in the aspect of in vivo noninvasive measurement of liver mechanical properties, the conventional technology generally adopts means such as an instantaneous elastography technology, a shear wave elastography technology, a nuclear magnetic resonance elastography technology and the like for imaging. Taking the instantaneous elastography technology as an example, the instantaneous elastography technology is a method for monitoring the propagation of elastic waves caused by mechanical excitation in a human body through an ultrasonic probe (ultrasonic A) and carrying out in-vivo noninvasive quantitative characterization on the mechanical properties of human tissues. The basic flow of transient elastography is as follows: the intercostal region of the patient is observed by using the common B-ultrasonic to find an axis suitable for measuring the mechanical property. After finding, marking on the body surface. The probe is pressed between the ribs of a person to be measured, and certain pressure is manually applied to the tissue, so that the probe is in close contact with the surface of the skin. The probe position was manually held steady. The probe generates a displacement excitation signal that induces propagation of near-field mechanical waves in the tissue. The vibration element in the probe drives the probe end to generate a sine pulse with a complete cycle, and the duration time is 20 ms. This vibration causes near-field mechanical waves to propagate centered on the excitation point. An ultrasonic transducer at the end part of the probe starts imaging below the axis of the probe, echo signals are collected at a frame frequency of about 5000Hz, the change of axial displacement of mass points on the axis below the probe along with time is captured by adopting a correlation algorithm, and the wave velocity of the near-field mechanical wave is calculated by a space-time displacement field. And substituting the wave velocity of the near-field mechanical wave into a near-field elastic wave theory to obtain the mechanical parameters of the tissue.
However, the transient elastography in the conventional techniques is greatly influenced by the operation of an operator when obtaining measurement parameters, the effective depth of measurement is limited, a large area of liver is outside the effective diagnosis area, and the conventional transient elastography techniques are difficult to confirm the tissue condition below the probe in situ.
SUMMERY OF THE UTILITY MODEL
Based on this, it is necessary to provide a probe for elastography, which is directed to the technical problem of low measurement accuracy of the transient elastography of the above-mentioned conventional technique.
A probe for elastography, the probe comprising:
the excitation generating device is provided with a hollow structure and is used for applying displacement excitation on the surface of the material to be detected so as to generate near field waves inside the material to be detected;
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 respectively connected with the excitation generating device and the scanning device.
In one embodiment, the scanning device comprises an ultrasound 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 configured to transmit an ultrasonic signal to the material to be tested and receive an ultrasonic echo signal reflected by the material to be tested.
In one embodiment, the excitation generating device is a ring structure.
In one embodiment, the gap between the excitation generating means and the scanning means is 0.001mm-100 mm.
In one embodiment, the probe further comprises:
a filler disposed within a gap between the scanning device and the excitation generating device.
In one embodiment, the probe further comprises:
an actuating element connected to the stimulus generating means for outputting a displacement waveform to the stimulus generating means such that the stimulus generating means moves.
In one embodiment, the probe further comprises:
a probe housing having an inner wall connected to the connector for receiving the excitation generating device, the scanning device, the connector, the filler, and the actuating element.
In one embodiment, the probe further comprises:
and one end of the buffer device is connected with the connecting piece, and the other end of the buffer device is connected with the actuating element, and the buffer device is used for offsetting or weakening acting force generated by the motion of the excitation generating device on the probe shell.
In one embodiment, the probe further comprises:
and the pressure sensor is respectively connected with the connecting piece and the scanning device and used for detecting the pressure between the scanning device and the material to be detected.
In one embodiment, the cross-sectional shape of the hollow structure is circular, elliptical, rectangular, star-shaped, triangular, or distributed scatter-point shape.
In one embodiment, the displacement waveform comprises a single sine wave pulse, a harmonic, a triangular wave, or a broadband wave.
The probe for the elastography comprises an excitation generating device, a scanning device and a connecting piece respectively connected with the excitation generating device and the scanning device, 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 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 separated in space, that is, the working modes of the scanning device and the excitation generating device are not in close coupling relation, so that the scanning device can not move along with the vibration of the excitation generating device, the vibration of the scanning device in the measuring process can be avoided under the condition that the intensity of the excitation signal is not basically lost, therefore, the stability of scanning signal acquisition is improved, the complexity of scanning signal post-processing is reduced, and the success rate and the measurement precision of instantaneous elastography are effectively improved.
Drawings
FIG. 1 is a schematic diagram of a probe for elastography in one embodiment;
FIG. 2 is a schematic diagram of an embodiment of scheme A (a) and scheme B (b), both simplified models being axisymmetric models, with the dashed lines representing the symmetry axes of the models; the circle is the front view of the probe, reflecting the geometry of the probe;
FIG. 3 is a simulation of the near field wave induced by different shaped probes on bulk materials of different stiffness (Young's modulus) in one embodiment, the two-dimensional graph shows the axial displacement of the node on the central axis of the excitation as a function of the excitation time;
FIG. 4 is a comparison of signal amplitudes generated using circular excitation and circular excitation in one embodiment, with depth on the horizontal axis and displacement signal extrema (on a logarithmic scale) at that depth on the vertical axis;
FIG. 5 shows the extreme values of the axial displacement signal at each depth for one embodiment when a solid excitation (case A) and a ring excitation (case B) are used to characterize three modulus materials. (a)E＝2KPa，(b)E＝4KPa，(c)E＝27KPa。
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In one embodiment, referring to fig. 1, a probe for elastography is provided, the probe comprising an excitation generating device 102, a scanning device 104, and a connecting member 106 fixedly connecting the excitation generating device 102 and the scanning device 104, respectively, the scanning device 104 being spaced apart from the excitation generating device 102. Further, the excitation generating device 102 is opened with a hollow structure, and the scanning device 104 is disposed in the hollow structure of the excitation generating device 102. The excitation generating device 102 is configured to apply displacement excitation to 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 configured to transmit a scanning signal to the material to be measured and receive a feedback signal reflected by the material to be measured, where the feedback signal carries propagation information of the near-field wave in the material to be measured. Alternatively, the material to be tested may be a biological tissue.
Specifically, the excitation generating device 102 may be an excitation head. The spacing of the scanning device 104 from the stimulus generating device 102 means that there is a gap between the scanning device 104 and the stimulus generating device 102, or it can be understood that there is no contact between them, such that the scanning device 104 and the stimulus generating device 102 are not operatively coupled. For example, when the operator brings the probe into contact with the surface of the material to be measured, the excitation generating device 102 vibrates with respect to the surface of the material to be measured, and the scanning device 104 does not move due to the vibration of the excitation generating device 102, that is, the scanning device 104 is always in contact with the surface of the material to be measured. It should be clear that the present embodiment does not limit the size of the gap, as long as the motion of the excitation generating device 102 does not affect the operation of the scanning device 104. The split design allows greater flexibility of the probe, for example, the probe may also be used for characterization of soft materials of non-biological tissues, and the like.
Optionally, the gap between the scanning device 104 and the excitation generating device 102 is 0.001mm-100 mm. 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 may be placed in the gap between the scanning device 104 and the excitation generating device 102, and the filler may effectively block the motion of the scanning device 104 caused by the vibration of the excitation generating device 102, so as to ensure the stability of the scanning signal acquisition of the probe.
The probe for elastic imaging comprises an excitation generating device, a scanning device and a connecting piece respectively connected with the excitation generating device and the scanning device, wherein 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 the excitation generating device and the scanning device are arranged at intervals to ensure that the excitation generating device and the scanning device are separated in space, namely the working modes of the scanning device and the excitation generating device are not in close coupling relation, so that the scanning device can not move along with the vibration of the excitation generating device, the vibration of the scanning device in the measuring process is avoided under the condition of basically no loss of the intensity of an excitation signal, the collection stability of the scanning signal is improved, the complexity of post-processing of the scanning signal is reduced, and the characterization accuracy and the characterization success rate of the material are expected to be improved, thereby effectively improving the success rate and the measurement precision of instantaneous elastography and being beneficial to the early screening of hepatic fibrosis.
In addition, the separated design of the excitation generating device 102 and the scanning device 104 gives the probe a larger degree of freedom, the probe can be used for the macro characterization of soft materials, and the signal focusing depth can be controlled by controlling the shape of the excitation head, thereby being helpful for solving the problem of strong attenuation of near-field signals when the conventional technology is used for material characterization.
Further, the probe further comprises an actuating element 108, wherein the actuating element 108 is connected to the excitation generating means 102 for outputting a displacement waveform to the excitation generating means 102 to cause the excitation generating means 102 to move. Wherein the actuating element 108 and the excitation generating means 102 constitute the excitation system of the probe. Optionally, the actuating element 108 may be an electric actuating element 108, or may be an actuating element 108 driven by other energy sources, and the embodiment is not limited. Taking the electric actuator 108 as an example, the electric actuator 108 outputs a set displacement waveform after detecting the electric signal, so that the excitation generator 102 vibrates. Optionally, the set displacement waveform may be divided into a plurality of steps, such as single sine wave pulses with different frequencies (30-200Hz), harmonic waves, triangular waves, and even broadband arbitrary waves, and the type and frequency of the displacement waveform are not limited in this embodiment, and may be selected according to actual requirements. 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 characterizing the viscoelasticity and the complex mechanical properties of the material to be measured.
Optionally, in one embodiment, the excitation head generates one or more near-field waves propagating in the material under test by direct or indirect contact with the material under test. The shape of the near field wave over time may be arbitrary, but more generally is of the impulse type, transition type or periodic (continuous, monochromatic) type. The vibration is usually obtained mechanically, but can also be obtained by radiation pressure, by ultrasound hyperthermia or by vibration in the body (heartbeat, pulse, etc.). Similarly, vibrations can also be obtained by means of excitation heads arranged outside the body.
Alternatively, in one embodiment, the excitation head may be a low frequency oscillator or a motor. In order to make the material to be measured generate micro deformation under the action of external force or internal force, the excitation head generates low-frequency low-amplitude vibration to cause shear waves which are transmitted to biological tissues and induce the biological tissues to generate micro deformation.
In one embodiment, the excitation 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 detrimental 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 is limited, and if the amplitude of the shear wave is too large, the human body may feel uncomfortable, so in a preferred embodiment, the frequency of the vibration generated by the low frequency oscillator is 10 Hz to 1000 Hz, and the amplitude is 0.2mm to 2 mm.
Optionally, in an embodiment, the scanning device 104 includes an ultrasound transducer or a photoacoustic scanner. The number of the ultrasonic transducers may be one or more, and a plurality of the ultrasonic transducers constitute an ultrasonic transducer array. Alternatively, the ultrasound transducer array may be any one of a linear array ultrasound transducer, a convex array ultrasound transducer, or a phased array ultrasound transducer. The number of photoacoustic scanners may be one or more, and a plurality of photoacoustic scanners constitutes a photoacoustic scanner array. Optionally, in one embodiment, the probe further comprises a scanning device mount 105, the scanning device mount 105 being adapted to mount the scanning device 104. Correspondingly, the fixture for fixing the ultrasound transducer is referred to as an ultrasound transducer fixture, and the fixture for fixing the photoacoustic scanner is referred to as a photoacoustic scanner fixture 105. The fixing manner of fixing 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 adhered to the scanning device fixing member 105.
In one embodiment, the ultrasonic transducers may be a crown, ring, 2D matrix, linear or rib transducers, single element transducers, three element transducers, or star transducers, among others.
In one embodiment, the excitation generating device 102 is provided with a hollow structure; at least one ultrasonic transducer is disposed in the hollow structure of the excitation generating device 102, and is configured to transmit an ultrasonic signal to the material to be measured and receive an ultrasonic echo signal reflected by the material to be measured, where the ultrasonic echo signal carries propagation information of the near-field wave in the material to be measured.
Specifically, the cross-sectional shape of the hollow structure may be a circle, an ellipse, a rectangle, a star, a triangle, or a distributed scatter point shape, and may also be other irregular shapes, and the shapes are within the scope of protection of the present application as long as the hollow structure can be formed. Distributed scatter shapes refer to shapes consisting of one and a separate spot area in which a scanning device 104, such as an ultrasound transducer, may be disposed. The ultrasound transducer is arranged in the hollow structure of the excitation generating means 102 such that the ultrasound transducer is not in a coupling relationship with the operation of the excitation generating means 102. Preferably, the excitation generating means 102 is a ring structure. Here, the simple and easy-to-understand excitation generating device 102 with a ring structure is taken as an example, when an operator opens a switch of the probe and applies a certain pressure to contact the probe with the surface of the material to be measured, at this time, the ring excitation generating device 102 also contacts with the surface of the material to be measured, and it applies displacement excitation on the surface of the material to be measured, i.e., generates vibration, so as to excite a near field wave similar to that excited by a transient elastography system in the interior of the material to be measured. Furthermore, the ultrasonic transducer transmits ultrasonic signals to the material to be measured and receives ultrasonic echo signals reflected by the material to be measured, and the ultrasonic echo signals carry propagation information of near-field waves in the material to be measured, including information such as wave velocity and frequency dispersion of the near-field shear waves.
Alternatively, the ultrasonic transducer may be placed at the center of the hollow structure of the excitation generating device 102, or may be placed at other positions of the hollow structure of the excitation generating device 102, which may be placed according to actual requirements, and the application is not limited thereto.
It is clear that, taking a human or animal as an example, the ultrasound transducer is in contact with the surface of the human or animal body, so as to acquire a two-dimensional ultrasound image of the biological tissue. The two-dimensional ultrasonic image obtained by the ultrasonic transducer in real time is accurately positioned, the probe is assisted and guided to accurately position according to actual needs, specifically, the position corresponding to the scanning line of the middle position of the two-dimensional ultrasonic image is the area to be detected, and accurate positioning is provided for the actual clinical instantaneous elastography process.
In the embodiment, the excitation head is provided with the hollow structure, the space released by the hollow structure allows the scanning device 104 or the miniature B-ultrasonic imaging component and the like to be placed, and when the probe is actually used, the probe can be directly used for probing the liver below the probe to a uniform degree, so that non-uniform tissues such as large blood vessels and the like are avoided; meanwhile, the purpose of axis alignment of the probe in use is achieved, the axis direction of the probe can be detected in real time, and the obtained data are more accurate and effective. Moreover, the present embodiment uses the excitation generating device 102 with a hollow structure, such as the ring-shaped excitation generating device 102, and places the scanning device 104, such as a plurality of sets of ultrasonic transducers, at the center of the ring, so that the excitation and the imaging are separated from each other, which has the advantages of being non-invasive, fast, simple to operate and low in cost.
In one embodiment, the scanning device 104 may be disposed around an outer surface of the excitation generating device 102. 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. Alternatively, the excitation generating means 102 is a solid structure. The scanning device 104 is disposed about an outer surface of the excitation generating device 102, and the scanning device 104 is not operatively coupled to the excitation generating device 102. Thus, when the excitation generating device 102 applies displacement excitation on the surface of the material to be measured, vibration is generated, so that near-field waves similar to those excited by a transient elastography system are excited in the interior of the material to be measured. Furthermore, the scanning device 104 may be, for example, an ultrasonic transducer, which transmits an ultrasonic signal to the material to be measured in the axial direction of the probe by using a focusing manner, and receives ultrasonic echo signals reflected by the material to be measured, where the ultrasonic echo signals carry propagation information of the near-field wave in the material to be measured, including information such as the wave velocity and the frequency dispersion of the near-field shear wave.
Alternatively, in one embodiment, the scanning device 104 may be disposed on both sides of the excitation head, for example, for the rib region imaging operation, since the ribs have an elongated arch shape, the probe may be designed to have a structure similar to the shape of the ribs, so that the rib region can be more effectively and conveniently imaged by disposing the scanning device 104 on both sides of the excitation head along the extending direction of the ribs. In one embodiment, multiple scanning devices 104 may be positioned on either side of the excitation head by two positioning posts.
In one embodiment, the probe further includes a probe housing 110 for housing the internal structure of the probe, including the excitation generating device 102, the scanning device 104, the coupling 106, and the like, as described above. The probe housing 110 may also serve the purpose of protecting the internal structure of the probe and facilitating operation by an operator. Further, in one embodiment, the connector 106 is fixedly connected to the probe housing 110, such that the position of the excitation generating device 102 and the scanning device 104 connected to the connector 106 is fixed to the probe housing 110, thereby preventing the probe housing from falling off. Alternatively, the probe housing 110 may be made of plastic, metal, or quartz.
Further, in one embodiment, the probe further includes a damping device 112, the damping device 112 being connected to the actuating element 108 and the connecting member 106, respectively, for counteracting or damping forces generated by the motion of the excitation generating device 102 on the probe housing 110. Specifically, the damping device 112 is responsible for damping and reducing the force applied to the probe housing 110 by the motion of the excitation generating device 102, so that the probe housing 110 is substantially stationary during the motion of the excitation generating device 102. Alternatively, the damping device 112 may be an extension spring, a damping rod or a rubber strip, and it should be clear that any device capable of performing a damping function is within the scope of the present application. The damping device 112 is housed in the probe housing 110.
Optionally, in an embodiment, the probe further includes a pressure sensor 114, and the pressure sensor 114 is connected to the connecting member 106 and the scanning device 104, respectively, and is configured to detect a pressure between the scanning device 104 and the material to be measured, so that the probe and the surface of the material to be measured are kept in a certain compression, thereby ensuring that the probe and the surface of the material to be measured 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 measured. The pressure sensor 114 is housed in the probe housing 110.
Optionally, in one embodiment, the probe further comprises a protective membrane (not shown) covering the excitation generating means 102 and the scanning means 104. The protective film can not only protect the probe from damage, but also prevent the material to be measured from any contamination by using a new protective film for each new operation of the material to be measured. Preferably a cell, which comprises an echogenic gel to ensure proper ultrasound coupling. In addition, the protective film is preferably disposable in order to prevent the transfer of contaminants from one material to be tested to another.
The following will illustrate the advantages of the solution described in the present application by comparing the results of the solution described in the present application with those of Fibrosan (conventional technology) through finite element simulation results in combination with practical cases.
From the mechanical point of view, the mechanically simplified models corresponding to the fiber scan scheme (hereinafter referred to as scheme a) and the scheme described in the present application (hereinafter referred to as scheme B) are shown in fig. 2(a) and fig. 2(B), respectively. Modeling the two materials by adopting a finite element method, wherein the block material to be characterized is a semi-space infinite uniform block material, the material constitutive relation is a linear elastic material, the Poisson ratio v is 0.499977, and the material density rho is 1000kg/m3(ii) a The section of the excitation head in the A case is in a solid circle shape with the diameter d of 9 mm; the section of the excitation head in the case B is in a ring shape with the outer diameter d being 9 mm; the motion of the exciting head is a sine wave, the frequency of the sine wave is 50Hz, and the peak value of vibration is 0.2 mm; the observation area is a cylinder with a radius L of 100mm and a height H of 100 mm.
Adopting commercial finite element software Abaqus to carry out numerical simulation on the propagation process of the near field wave under two conditions, and extracting an axial displacement component U on the symmetry axis of the modely. Make axis nodal displacement UyThe time-space diagram over time is shown in fig. 3. The course of the wave front movement in the depth direction of the near-field wave is clearly visible in fig. 3. Fitting the displacement minimum value point on each depth on the two-dimensional space-time diagram by using a straight line to obtain the phase velocity of near-field wave propagation, and substituting the phase velocity into a theoretical formula E of 3 rho c2The elastic modulus of the material can be inverted. The numerical simulations gave the results shown in table 1. It can be seen that the inversion process of the tissue elasticity properties is not affected by the B scheme.
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, finding the time corresponding to the displacement extreme value under each depth on the velocity space-time diagram shown in figure 3, and making a time-depth scatter diagram; (2) fitting the time-depth scatter diagram by using a straight line, wherein the fitting slope is the near field wave propagation speed V; (3) by classical formula E ═ 3 ρ c2The young's modulus of the material is inverted.
Hollowing out the center results in less energy being input into the tissue by the exciter, potentially reducing the signal-to-noise ratio. Since the near-field wave is strongly attenuated in the depth direction itself (fig. 4), this energy loss needs to be strictly controlled. For this purpose, it is necessary to determine the attenuation level of the signal in relation to the proportion of hollowing. Still extracting the U at each depth during wave propagationyAnd making an extremum value and making a relation between the extremum value and the depth. It can be seen that the B scheme can be adopted to provide sufficient space for the ultrasonic transducer group with almost no loss of signal strength.
The above results have demonstrated that ring excitation transient elastography can avoid the movement of the ultrasonic probe in the imaging process under the condition that the signal is hardly lost compared with the Fibroscan, thereby reducing the complexity of signal processing and improving the stability and success rate of the method applied to early screening of hepatic fibrosis. The method can be used for characterization of soft materials besides hepatic fibrosis materials. When the annular probe is used for characterization of soft materials, the annular probe is not limited by a complex structure of a human body, so that a larger space is designed. The following is also described in terms of a finite element algorithm.
The material to be measured is an infinite uniform block, and the scheme (a) and (b) in fig. 2 is adopted to characterize the material. (a) The vibration exciter parameters of the scheme are as follows: d is 9 mm; (b) parameter d of annular vibration exciter of schemeIn25mm and d 25.4mm (this parameter is chosen to ensure consistent contact area size in both cases). 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 was taken to be 2KPa, 4KPa and 27KPa, respectively, and the Poisson's ratio was still 0.499977. Extracting U on central axis of finite element calculation resultyAnd compared, the results are shown in fig. 5. Therefore, under the condition that the contact areas are the same, the scheme B can be adopted to obtain a strong signal at a deeper position of the area to be detected, and meanwhile, the movement of the ultrasonic probe A in the characterization process can be avoided, so that the precision and the stability of material characterization are improved.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the utility model. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (12)
1. A probe for elastography, the probe comprising:
the excitation generating device is provided with a hollow structure and is used for applying displacement excitation on the surface of the material to be detected so as to generate near field waves inside the material to be detected;
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 respectively connected with the excitation generating device and the scanning device.
2. The probe of claim 1, wherein the scanning device comprises an ultrasound transducer or a photoacoustic scanner.
3. The probe of claim 2, wherein at least one of the ultrasonic transducers is disposed in the hollow structure of the excitation generating device for transmitting an ultrasonic signal to the material to be measured and receiving an ultrasonic echo signal reflected by the material to be measured.
4. The probe of claim 1, wherein the excitation generating means is a ring structure.
5. The probe of claim 1, wherein a gap between the excitation generating means and the scanning means is 0.001mm-100 mm.
6. The probe of claim 5, further comprising:
a filler disposed within a gap between the excitation generating device and the scanning device.
7. The probe of any one of claims 1 to 6, further comprising:
an actuating element connected to the stimulus generating means for outputting a displacement waveform to the stimulus generating means such that the stimulus generating means moves.
8. The probe of claim 7, further comprising:
a probe housing having an inner wall connected to the connector for receiving the excitation generating means, the scanning means, the connector, the filler and the actuating element.
9. The probe of claim 8, further comprising:
and one end of the buffer device is connected with the connecting piece, and the other end of the buffer device is connected with the actuating element, and the buffer device is used for offsetting or weakening acting force generated by the motion of the excitation generating device on the probe shell.
10. The probe of any one of claims 1 to 6, further comprising:
and the pressure sensor is respectively connected with the connecting piece and the scanning device and used for detecting the pressure between the scanning device and the material to be detected.
11. The probe of claim 1, wherein the cross-sectional shape of the hollow structure is circular, elliptical, rectangular, star-shaped, triangular, or a distributed scatter point shape.
12. The probe of claim 7, wherein the displacement waveform comprises a single sine wave pulse, a harmonic, a triangular wave, or a broad frequency wave.
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