JP2011130943A - Tissue hardness evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tissue hardness evaluation device capable of estimating a value regarding the hardness of tissue from the relation of the pressing force of a probe and the deformation of the tissue. <P>SOLUTION: The tissue hardness evaluation device includes: a measuring part comprising an ultrasonic probe and a pressing force measuring sensor; and an analysis part comprising an ultrasonic wave transmission/reception part, a pressing force reception part, a tissue deformation amount detection part, an elastic index calculation part, and a display part. The pressing force measuring sensor measures the pressing force of the ultrasonic probe to the tissue, and sends the measured result to the pressing force reception part. The ultrasonic wave transmission/reception part controls the transmission of the ultrasonic transmission signals of the ultrasonic probe, and outputs ultrasonic signals reflected from the tissue and converted by the ultrasonic probe to the tissue deformation amount detection part and the display part. The tissue deformation amount detection part detects the thickness of the tissue and outputs the detected result to the elastic index calculation part. The elastic index calculation part calculates the elastic indexes of the respective layers of the tissue on the basis of the signals from the pressing force reception part and the signals from the tissue deformation amount detection part, and outputs them to the display part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tissue hardness evaluation apparatus that can obtain information on the hardness (or softness) of a tissue from the deformation state of the living tissue by the pressing force, the pressing force and the tissue deformation rate.

A conventional ultrasonic echo device used in a medical field diagnoses the state of a tissue from the shape of an image displayed. At that time, the probe was empirically pressed against the body for reference of tissue identification.
An apparatus called elastography in which a function capable of measuring tissue elastic modulus is added to a conventional ultrasonic echo apparatus has been developed. This is a device that presses the probe against the body, reads the degree of tissue deformation from the image, and estimates the relative elastic modulus from the amount of strain. The configuration of the apparatus is the same as that of a normal ultrasonic echo apparatus. It is calculated by software built into the device from the ultrasonic signals before and after pressing. Since this device does not measure the pressing force, the resulting elastic modulus can only be obtained relative to the surrounding tissue.

  In existing patents, there is a technique for measuring a pressing force and a moving amount of a probe and calculating a value related to hardness. For example, there are the following.

  (1) The technique relating to the soft tissue viscoelasticity estimation apparatus and program using ultrasonic waves disclosed in Patent Document 1 can be applied to soft tissues having a hierarchical structure with skin, fat, muscle, bone, and the like, such as body tissues. It is possible to estimate elasticity, viscosity, and inertia every time, and to reduce damage to soft tissue by enabling estimation only with a short push-in operation, it is necessary to transmit and receive ultrasonic signals. An acoustic probe, an object deformation amount calculation unit for calculating the deformation amount of the object shape from the time change of the received data, a moving mechanism for moving the ultrasonic probe, and a probe control unit for controlling the same, Obtained from each of the position sensor for measuring the position of the probe, the force sensor for measuring the force applied to the probe section, the position sensor, the force sensor, and the object deformation amount calculation section. And the viscoelastic estimation unit that estimates a viscoelastic object on the basis of that value is a technique for constituting a viscoelastic display unit for presenting the estimated viscoelasticity to the user.

  (2) The technology relating to the ultrasonic diagnostic apparatus of Patent Document 2 is a magnetic sensor for the purpose of accurately grasping and rendering the positional relationship between a tomographic image and a strain elastic image in any strain elastic image rendering means. A position detecting means for detecting three-dimensional position information represented by the above is attached to an ultrasonic probe. This three-dimensional position detecting means is based on a base point fixed to a certain point and is spatially detected by a magnetic sensor. Can be grasped. By using this, the position information of the probe when obtaining a tomographic image is compared with the position information of the probe when obtaining a strain elastic image, and the probes that moved when acquiring each other's images are compared. It is possible to grasp the relative shift of the diagnostic image obtained from the movement distance of the child. In addition, by using three-dimensional position detection means, it is possible to keep the amount of pressure applied to the subject tissue constant regardless of the device handler, and to prepare a test environment that does not depend on the device handler. Technology.

  (3) The technique related to the ultrasonic probe and the ultrasonic diagnostic apparatus of Patent Document 3 is a means capable of detecting the contact pressure of the ultrasonic probe on the contact surface where the ultrasonic probe is pressed against the subject. When the contact pressure is equal to or higher than a predetermined pressure, an abutment surface that abuts the subject of the ultrasound probe for the purpose of providing an ultrasound diagnostic device that issues an alarm sound or the like A tube 50 filled with a pressure transmission medium is provided around the vibrator provided in the tube 50, and a pressure sensor 52 for detecting the pressure of the pressure transmission medium in the tube 50 is provided. The contact pressure at which the contact surface of the ultrasonic probe is pressed against the subject is measured. For this reason, if a circuit that issues a warning to the examiner when a pressure higher than the reference value is detected in the main body of the ultrasonic probe, the examiner can detect the ultrasonic probe at a pressure higher than a certain pressure. It is a technique that can prevent the patient from being pressed against the subject and remove the pain of the subject.

  (4) The technique relating to the elastography measurement and imaging method of Patent Document 4 and the apparatus for performing this method is an improved ultrasonic pulse / applied to accurate compression measurement in any backscattered material, particularly organic tissue. In order to provide an echo method and an apparatus for performing the method, a standard transducer or an axially translated transducer device is used to compress or move the proximal end area of the target body by a known small increment. At each increment, a pulse is emitted and an echo sequence (A-line) is detected from the sound travel path in the target or the area along the transducer beam. The time shift in the echo segment corresponding to the feature in the target is corrected for each zone of varying sound speed along the sound path to provide relative quantitative information about the distortion caused by the compression. Also, the stress applied by the transducer and transducer device is determined and modified corresponding to the depth along the sound path. A technique that divides the appropriate stress values by their respective strain values along each passage to produce a target elastogram or sequence of compressibility values.

  (5) The technology relating to the ultrasonic diagnostic apparatus of Patent Document 5 is based on two time-series techniques obtained by tomographic scanning means for the purpose of displaying an elastic image representing the hardness or softness of a living tissue in the ultrasonic diagnostic apparatus. Displacement measuring means 8 for calculating the amount of movement or displacement of each point on the tomographic image by calculating between the tomographic images, pressure measuring means 9 for measuring or estimating the body cavity pressure at the diagnostic site of the subject, The elastic modulus calculation means 10 for calculating the elastic modulus of each point on the tomographic image from the displacement and pressure obtained by the measuring means to generate elastic image data, and the elasticity image data from the elastic modulus calculation means 10 are input. Hue information conversion means 11 for providing hue information, and switching addition means 12 for adding or switching black and white tomographic image data from the tomographic scanning means and color elastic image data from the hue information conversion means 11. Cut off The image data from the substitution adding means 12 is displayed on the image display means 7. This is a technique for displaying an elastic image representing the hardness or softness of a living tissue.

  (6) The technique relating to the soft tissue softness detection method and the detection apparatus used therefor in Patent Document 6 are based on a change in frequency when a miniaturized sensor element touches soft tissue, cancer, tumor, etc. in the living body. A sensor comprising an objective contact vibrator 11 and a vibration detection unit 12 for the purpose of detecting a difference in hardness and measuring a hardness from a hard object such as a bone or a tooth to a soft soft tissue such as a bone with a single sensor. Unit 1, an output signal from the sensor unit 1 is amplified by an amplifier 21, and this is forcibly fed back to the objective contact vibrator 11 through a band-pass filter 22 or a peaking amplifier 23. This is a technique comprising a measuring unit 3 that measures the amount of frequency change of the self-excited oscillation circuit 2.

Japanese Patent No. 4189840 Japanese Patent No. 4179596 Japanese Patent Laid-Open No. 08-033623 JP-T-2001-519664 Japanese Patent No. 3268396 JP-A-8-29312

In the technique described in Patent Document 1, in addition to the mechanism for measuring the pressing force, it is necessary to measure the amount of movement of the probe in some form in order to calculate the amount of deformation of the tissue. Therefore, there is a mechanism for measuring the amount of movement. It becomes necessary and the device mechanism becomes large, and it is difficult to use it at the actual measurement site. Further, there is a problem that handling around the probe becomes difficult during use, and it is difficult to ensure portability.
The technique described in Patent Document 2 requires a mechanism for detecting the three-dimensional position information of the probe. Also, the pressing force is not measured.
The technique described in Patent Document 3 is a technique that measures the pressing force and issues a warning by an alarm sound or the like when the contact pressure between the probe and the living body exceeds a predetermined pressure, and cannot perform accurate measurement.
Since the technique described in Patent Document 4 moves the ultrasonic probe with a motor to deform the tissue, it requires a separate control device around the motor and does not measure the pressing force.
The technique described in Patent Document 5 is an invasive method for measuring internal stress by inserting a pressure sensor into a living body and is not helpful.
The technique described in Patent Document 6 is a technique for measuring the elastic modulus by changing the frequency of the ultrasonic wave, and the calibration process for removing the influence of the frequency from the measurement result is difficult, and is not practical.

An object of the present invention is to provide a tissue hardness evaluation apparatus capable of calculating a value related to tissue hardness from the relationship between the pressing force of a probe and the deformation of a tissue in view of the problems of the conventional example.
Another object of the present invention is to allow calculation for each layer even for soft tissues having a hierarchical structure with skin, fat, muscle, bone, etc., such as body tissues.

(1) A tissue hardness evaluation apparatus according to the present invention includes a measurement unit including an ultrasonic probe and a pressing force measurement sensor, an ultrasonic transmission / reception unit, a pressing force reception unit, a tissue deformation amount detection unit, an elastic index calculation unit, and a display unit. The analysis part
The pressing force measurement sensor measures the pressing force of the ultrasonic probe to the tissue and sends the measurement result to the pressing force receiving unit, and the ultrasonic transmitting / receiving unit controls the transmission of the ultrasonic transmission signal of the ultrasonic probe, and from the tissue The ultrasonic signal reflected and converted by the ultrasonic probe is output to the tissue deformation amount detection unit and the display unit, and the tissue deformation amount detection unit detects the thickness of the tissue and outputs the detection result to the elasticity index calculation unit. The elasticity index calculation unit calculates the elasticity index of each tissue layer based on the signal from the pressing force receiving unit and the signal from the tissue deformation amount detection unit, and outputs the elasticity index to the display unit.
(2) The analysis unit is configured by a computer.
(3) The tissue deformation amount detection unit has a certain width with respect to the ultrasonic signal (echo signal) change b (x) obtained from the tissue, where x is a position in the depth direction from the surface of the tissue. A window is set, and the maximum value of the ultrasonic signal is found in the window width W. The windows are sequentially arranged at intervals sufficiently smaller than the window width, for example, about 1/10 of the window width in the x-axis direction. The maximum curve p (x) is obtained by the following formula 1 while shifting to
This maximum value is not changed more than a predetermined allowable variation value A _t portion of the center position of the part are continuous over the window width W and the position of the tissue, a value thickness is minimum of the tissue window width Thus, the position of the tissue is appropriately identified. However, max is a function for obtaining the maximum value.
(4) The elasticity index calculation unit takes in the movement amount Δx in the tissue from the tissue deformation amount detection unit and the pressing force value F which is a measurement value of the pressing force measurement sensor from the pressing force receiving unit, To obtain a value k related to hardness.

(Evaluation principle)
A value related to the hardness (softness) of the tissue is obtained by pressing the probe and deforming the tissue. When the tissue is simplified with a one-dimensional spring and Hook's law is applied, the following Equation 3 is obtained.
However, F is a pressing force, k is a value relating to hardness, and Δx is a movement amount of tissue.
In other words, in order to obtain a value k related to hardness by pressing the structure,
Should be calculated. F is measured by a sensor such as a load cell incorporated in the probe in the present invention, and Δx is measured from an ultrasonic image.

The present invention can measure not only information related to the volume related to the volume of tissue, particularly the shape of body tissue, but also information related to quality called hardness (softness).
In addition, by integrating the sensor that measures the pressing force into the ultrasonic probe, the sensor and probe can be operated freely and easily when collecting necessary data, and the portability is sacrificed. Therefore, it is possible to realize a device capable of obtaining a value relating to tissue hardness (or softness) appropriately and accurately.
Also, by integrating the sensor into the ultrasonic probe, it is possible to simultaneously measure the ultrasonic image and the pressing force.
Since the present invention obtains a value related to tissue hardness by calculation from the measured value of the pressing force against the tissue and the ultrasonic echo image of the tissue corresponding to the deformation rate of the tissue at the time of pressing, the amount of movement of the probe It is possible to eliminate the need for a mechanism for measuring.
In addition, it is possible to perform calculation for each layer even for soft tissues having a hierarchical structure with skin, fat, muscle, bone, and the like, such as body tissues.

It is a figure explaining the process in the structure | tissue hardness evaluation part 8 of this invention. It is a figure which shows the echo image of this invention, and the layer position of a structure | tissue, a right figure is a thigh front part, and a left figure is an upper arm front part. FIG. 3 is an echo image showing a change state of a certain tissue site in FIG. 3B when the pressing force in FIG. 3A is continuously changed, and an interval table of each layer in FIG. The characteristic table of the rate of change from the initial pressing force in FIG. FIG. 3 is a graph showing the characteristic table of the rate of change from the initial pressing force in FIG. The expansion-contraction aspect of each structure | tissue layer when pressing force is applied to a structure | tissue is illustrated. It is a characteristic view of the elasticity parameter | index with respect to the pressing force of the BC layer and CD layer of a structure | tissue. It is a block block diagram of the structure | tissue hardness evaluation apparatus of this invention. Some examples of how to incorporate a sensor to measure the pressing force on a probe are shown. Examples of the A mode and B mode of the present invention are shown. The method of calculating | requiring each tissue position of this invention is shown. It is a flowchart of the process in the analysis part 3 of this invention.

  Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 7 is a block diagram of the structure hardness evaluation apparatus of the present invention.
The tissue hardness evaluation apparatus 1 includes a measurement unit 2 and an analysis unit 3. The measurement unit 2 includes an ultrasonic probe 4 and a pressing force measurement sensor 5. The analysis unit 3 includes an ultrasonic transmission / reception unit 6, a pressing force reception unit 7, a tissue deformation amount detection unit 8, an elasticity index calculation unit 9, and a display unit 10. The ultrasonic probe 4 converts the voltage into an ultrasonic signal and transmits it to the tissue 11, and converts the reflected ultrasonic signal into a voltage and sends it to the ultrasonic transmission / reception unit 6.
The analysis unit 3 is constituted by a computer, for example. The analysis unit 3 controls the structure hardness evaluation apparatus using an input / output function by an i / o interface of a computer, a storage / read function by a memory, and a calculation function by a CPU.
The tissue hardness evaluation apparatus 1 is provided with a moving mechanism such as a linear slider (not shown) for manually moving the ultrasonic probe 4 provided with the pressing force measurement sensor 5 to an arbitrary position with respect to the tissue. You can also. In addition, since the acquisition time of tissue ultrasonic signals (echo image signals) is extremely short, the time interval that satisfies the constant pressing force is also shortened, and the constant pressing force is satisfied even in manual pressing operations. It is like that.
The pressing force measurement sensor 5 measures the pressing force of the ultrasonic probe 4 against the tissue 11 and sends the measurement result to the pressing force receiver 7. The ultrasonic transmission / reception unit 6 controls the ultrasonic transmission signal of the ultrasonic probe 4 by the voltage, and the ultrasonic signal reflected from the tissue 11 and converted into the voltage by the ultrasonic probe 4 with the tissue deformation amount detection unit 8. This is sent to the display unit 10. The tissue deformation amount detection unit 8 detects the thickness of the tissue 11 and sends the detection result to the elasticity index calculation unit 9. The elasticity index calculation unit 9 calculates the elasticity index of each layer of the tissue 11 based on the signal from the pressing force receiving unit 7 and the signal from the tissue deformation amount detection unit 8 and sends it to the display unit 10.

(Tissue thickness deformation detection method)
Measurements using ultrasonic waves include a method of converting the amplitude of an ultrasonic signal called B mode into luminance and displaying it as a two-dimensional image, and a method of drawing the amplitude of ultrasonic wave called A mode as a curve.
FIG. 9 shows an example of the A mode and B mode of the present invention.
FIG. 9A is a two-dimensional image in the B mode (luminance mode), where the wavy direction (the direction from the top to the bottom of the paper) is the depth direction from the surface of the tissue, and the white portion in the image is a portion where the luminance is high. A black part represents a portion having a low luminance.
FIG. 9B is a characteristic diagram of the A mode (luminance amplitude mode), which represents the luminance change characteristic of the wavy line portion (one-dimensional image) in the two-dimensional image of the B mode, and the vertical axis represents the tissue depth direction. The distance is represented, and the horizontal axis represents the luminance value.
A graph in which the luminance of the wavy line in the B-mode image is extracted and displayed as a change in the ultrasonic signal corresponds to the A mode.
The amount of deformation of each tissue is obtained from this A-mode ultrasonic signal change.

FIG. 10 shows a method for obtaining each tissue position of the present invention. The vertical axis in FIG. 10 is the luminance value, and the horizontal axis is the distance in the depth direction.
The ultrasonic signal (echo signal) is output from the ultrasonic transmission / reception unit 6 in advance as an ultrasonic signal reflected from the tissue 11 and converted into a voltage by the ultrasonic probe 4.
Therefore, if x in FIG. 10 is a position in the depth direction from the surface of the tissue, the tissue deformation amount detection unit 8 uses the ultrasonic signal (echo signal) change b (x) obtained via the ultrasonic transmission / reception unit 6. A window having a certain width with respect to is set, and the maximum value of the ultrasonic signal is found within the window width W. The maximum curve p (x) is obtained by sequentially shifting this window in the x-axis direction at an interval sufficiently smaller than the width of the window, for example, about 1/10 of the width of the window. This can be expressed by the following mathematical formula 5. max is a function for obtaining the maximum value.
The center position of the portion where the portion where the maximum value does not change more than a certain value (allowable variation value A _t ) continues for the window width W or more is defined as the tissue position (tissue position). By setting the window width to a value that minimizes the tissue thickness, the tissue position can be appropriately identified. The change in the thickness of the tissue that changes due to the pressing force can be calculated by comparing the thicknesses of the tissues due to the two types of pressing forces. In the living tissue, in the upper arm and thigh, the subcutaneous fat portion has the minimum tissue thickness, and therefore it is appropriate to set the window width to 10 mm.

(Calculation formula of elasticity index)
The elasticity index calculation unit 9 takes in the movement amount Δx in the tissue 11 from the tissue deformation amount detection unit 8 and the pressing force value F which is a measurement value of the pressing force measurement sensor 5 from the pressing force reception unit 7, and Perform the operation.
If we simplify the tissue with a one-dimensional spring and apply Hook's law,
F = −kΔx
However, F is a pressing force, k is a value relating to hardness, and Δx is a movement amount of tissue.
In other words, k = −F / Δx in order to press the tissue 11 and obtain the value k related to hardness.
Should be calculated.

(Processing mode)
FIG. 1 is a diagram for explaining processing in the tissue hardness evaluation unit 8 of the present invention.
The characteristic diagram of the pressing force in the upper part of FIG. 1 shows how the pressing force increases and decreases.
The image in the middle of FIG. 1 is an echo image (B mode), and the adjacent characteristic diagram (line diagram: A mode) represents the characteristic of the center dotted line in the echo image. Image 1 is an image acquired at a load of 150 gf at the 20 / 100th frame, and image 2 is an image acquired at a load of 4500 gf at the 90 / 100th frame. Symbols A, B, C, and D in the image image indicate vertex positions in the adjacent diagram. Symbols A, B, C, and D indicate A-mode characteristic positions where the luminance on the image changes.
The lower characteristic table shows the distance from the end points to the positions A to D in the images 1 and 2, the difference between the values of the images 1 and 2 (measurement value difference), and the rate of change (force per unit area). Means value, dimension is (N / m) or (m ³ / kg)).
FIG. 2 is a diagram showing an echo image of the present invention and the layer position of the tissue, the right diagram is the front thigh, and the left diagram is the upper arm.
FIG. 3 is an echo image showing a change state of a certain tissue site in FIG. 3B when the pressing force in FIG. 3A is continuously changed, and an interval table of each layer in FIG. The characteristic table of the rate of change from the initial pressing force in FIG.
FIG. 4 is a graph showing the characteristic table of the rate of change from the initial pressing force in FIG.
FIG. 5 illustrates the expansion / contraction mode of each tissue layer when a pressing force is applied to the tissue. The expansion / contraction mode of each tissue layer indicates an overall expansion / contraction mode.
FIG. 6 is a characteristic diagram of the elasticity index with respect to the pressing force of the BC layer and the CD layer of the tissue.
Generally, as shown in FIG. 4, the change in the thickness of the tissue is not linear with respect to the pressing force. This is a phenomenon called strain hardening in which the hardness of the tissue increases with the pressing force. Therefore, in order to obtain a constant (independent of the pressing force) index for the pressing force necessary for the evaluation of the structure, it is necessary to convert the pressing force with a certain function and perform linear approximation. When a function to be used is a natural logarithm (ln), F is a pressing force, k ′ is an elastic index, and Δx is a movement amount of tissue,
k ′ = − ln (F) / Δx
Will be expressed. In FIG. 6, the elasticity index k ′ with respect to the pressing force F is calculated and graphed.

(Flowchart of analysis unit 3)
FIG. 11 is a flowchart of processing in the analysis unit 3 of the present invention.
The processing flow of the analysis unit 3 composed of a computer is roughly expressed as follows.
(S0: Step 0)
A sample of the pressing force, the window width w, and the movement interval are stored in advance in the memory.
start:
(S1: Step 1)
An ultrasonic wave corresponding to the tissue depth is transmitted from the ultrasonic transmission / reception unit 6 to the ultrasonic probe 4, an echo signal from the tissue 11 is received via the ultrasonic probe 4, and a depth-luminance characteristic (one-dimensional, 2D), and the depth-luminance characteristic (1D, 2D) signal is output.
(S2: Step 2)
The maximum value curve is obtained by sequentially shifting the window width w read from the memory in the depth-luminance characteristics (1D and 2D) in the depth direction, and the portion where the maximum value does not change beyond a certain value is the window width. The center position of the continuous part is obtained as the tissue position.
(S3: Step 3)
The tissue position from the tissue deformation amount detection unit 8 is converted into a tissue movement amount Δx, and a value k = −F / Δx related to the tissue hardness is obtained from the movement amount Δx and the pressing force F from the pressing force receiving unit 7. Ask.
(S4: Step 4)
A measured value from the pressing force measuring sensor 5 is received by the pressing force receiving unit 7.
(S5: Step 5)
A combination of the depth-luminance characteristics (one-dimensional and two-dimensional) of the echo signal from the ultrasonic transmission / reception unit 6 and the tissue movement amount Δx, the pressing force F, and the tissue hardness k from the elasticity index calculation unit 9 is displayed. .
End:

  It can be used in fields that require non-invasive measurement of tissue shape, hardness, softness, and other qualities such as health care, agriculture (evaluation of meat quality), and fishery (evaluation of meat quality). Further, since a large-scale device such as a moving mechanism is not necessary for the probe portion, it can be carried not only indoors but also outdoors and used portablely.

DESCRIPTION OF SYMBOLS 1 Tissue hardness evaluation apparatus 2 Assumption part 3 Analysis part 4 Ultrasonic probe 5 Pushing force measurement sensor 6 Ultrasonic transmission / reception part 7 Pushing force receiving part 8 Tissue deformation amount detection part 9 Elasticity index calculation part 10 Display part 11 Tissue

Claims (5)

A measurement unit comprising an ultrasonic probe and a pressing force measurement sensor;
An ultrasonic transmitter / receiver unit, a pressing force receiver unit, a tissue deformation amount detection unit, an elasticity index calculation unit, and an analysis unit consisting of a display unit,
The pressing force measuring sensor measures the pressing force of the ultrasonic probe on the tissue and sends the measurement result to the pressing force receiving unit, and the ultrasonic transmitting / receiving unit transmits an ultrasonic transmission signal of the ultrasonic probe. Controlling, outputting the ultrasonic signal reflected from the tissue and converted by the ultrasonic probe to the tissue deformation amount detection unit and the display unit, the tissue deformation amount detection unit detects the thickness of the tissue, The detection result is output to the elasticity index calculator, and the elasticity index calculator calculates the elasticity index of each tissue layer based on the signal from the pressing force receiver and the signal from the tissue deformation detector, and displays the display The structure hardness evaluation apparatus characterized by outputting to a part. The tissue hardness evaluation apparatus according to claim 1, wherein the analysis unit is configured by a computer. The tissue deformation amount detection unit is a window having a certain width with respect to an ultrasonic signal (echo signal) change b (x) obtained from the tissue, where x is a position in the depth direction from the surface of the tissue. In the window width W, the maximum value of the ultrasonic signal is found, and the maximum value curve p (x) is expressed as follows while the windows are sequentially shifted in the x-axis direction at intervals sufficiently smaller than the window width. Obtained by Equation 6,
This maximum value is not changed more than a predetermined allowable variation value A _t portion of the center position of the part are continuous over the window width W and the position of the tissue, and a value of the window width is the thickness of the tissue is minimized The tissue hardness evaluation apparatus according to claim 1, wherein the position of the tissue is appropriately identified.
However, max is a function for obtaining the maximum value.
The elasticity index calculation unit takes in a movement amount Δx in the tissue from the tissue deformation amount detection unit and a pressing force value F which is a measurement value of the pressing force measurement sensor from the pressing force receiving unit, and The structure hardness evaluation apparatus according to claim 1, wherein a value k related to hardness is obtained by performing the following calculation.
The elasticity index calculation unit takes in a movement amount Δx in the tissue from the tissue deformation amount detection unit and a pressing force value F which is a measurement value of the pressing force measurement sensor from the pressing force receiving unit, and The structure hardness evaluation apparatus according to claim 1, wherein the value k ′ relating to the hardness is obtained by performing the calculation.