Hifu irradiation device and method for evaluating state thereof

Abstract

To evaluate an influence that an ultrasonic imaging probe receives from an ultrasonic wave transmitted by an ultrasonic vibrator for treatment.SOLUTION: A control unit 22 executes ultrasonic transmission processing, ultrasonic reception processing, and distribution measurement processing. The ultrasonic transmission processing is processing for causing an ultrasonic vibrator 14 for treatment to transmit an ultrasonic wave for evaluation whose strength is smaller than that of the ultrasonic wave for treatment. The ultrasonic reception processing is processing for acquiring a reception signal based on the ultrasonic wave received by each vibrator 28 from each vibrator 28. The distribution measurement processing is processing for measuring strength distribution of the ultrasonic wave reaching a plurality of the vibrators 28 on the basis of the reception signal acquired from each vibrator 28.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a HIFU irradiation device equipped with an ultrasonic imaging probe, and in particular to evaluation of the state of the HIFU irradiation device. [Background technology]

[0002] A treatment device using high intensity focused ultrasound is widely used. This treatment device is called a HIFU irradiation device or HIFU irradiation system, and necrotizes biological tissue by irradiating a treatment site with focused ultrasound.

[0003] In general, a HIFU irradiation device is equipped with a plurality of ultrasonic transducers for treatment arranged on a concave surface. The plurality of ultrasonic transducers are arranged so that ultrasonic waves emitted from each of them are irradiated to one point to form a focal point. During treatment, the position of the focal point is adjusted to the treatment area and ultrasonic waves are irradiated. To confirm the irradiation position, an ultrasonic diagnostic device that shows the focal point on an ultrasonic image is used.

[0004] The following Patent Document 1 describes an ultrasonic treatment device that observes the position of the focal point using an ultrasonic diagnostic device that displays a B-mode image (tomographic image). In this device, ultrasonic waves at a low level that do not affect tissue are emitted from a therapeutic ultrasonic transducer, and a tomographic image is displayed by transmitting and receiving ultrasonic waves using an ultrasonic imaging probe. Since the acoustic properties of the patient's tissue change according to changes in the tissue temperature, the position of the focal point is indicated in the tomographic image by the intensity of brightness. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-71069 [Patent Document 2] JP 2014-30509 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a HIFU irradiation device, therapeutic ultrasound is reflected from inside or on the surface of a patient's body, and the reflected waves are concentrated near the ultrasound imaging probe, which may cause thermal stress on the ultrasound imaging probe. As described in Patent Document 2, a technology is described for an ultrasound diagnostic device equipped with a therapeutic probe and an imaging probe (ultrasonic imaging probe) that calculates the effect of the reflected waves of therapeutic ultrasound irradiated from the therapeutic probe on the ultrasound receiving surface of the diagnostic probe.

[0007] In the conventional technology described in Patent Document 2, when evaluating the effect of therapeutic ultrasound on an ultrasound imaging probe, an ultrasound transducer for treatment transmits ultrasound with the same intensity as that during treatment. With this technology, the ultrasound imaging probe is subjected to thermal stress by the ultrasound even during evaluation, which may shorten the life of the ultrasound imaging probe.

[0008] An object of the present invention is to evaluate the effect of ultrasound transmitted from a therapeutic ultrasound transducer on an ultrasound imaging probe. [Means for solving the problem]

[0009] The present invention comprises a therapeutic ultrasound transducer that transmits therapeutic ultrasound, an ultrasound probe having a plurality of transducers, and a control unit that controls the therapeutic ultrasound transducer and the ultrasound probe, and the control unit executes an ultrasound transmission process that causes the therapeutic ultrasound transducer to transmit evaluation ultrasound having a lower intensity than the therapeutic ultrasound, an ultrasound reception process that acquires from each transducer a reception signal based on the ultrasound received by each transducer, and a distribution measurement process that measures the intensity distribution of ultrasound arriving at the plurality of transducers based on the reception signal acquired from each transducer.

[0010] Preferably, the control unit executes a process of determining a concentration degree of ultrasonic waves received by each of the transducers based on the intensity distribution in the arrangement direction of the plurality of transducers.

[0011] Desirably, the intensity distribution is represented by a distribution function having one peak at a vertical axis value against a horizontal axis extending in the arrangement direction of the multiple transducers, and the control unit executes an evaluation process to evaluate the effect of the therapeutic ultrasound on each transducer using approximation parameters that define the distribution function.

[0012] Preferably, the distribution function includes a Gaussian function or a Lorentzian function.

[0013] The present invention is also a method for evaluating a state of a HIFU irradiation device including a therapeutic ultrasound transducer for transmitting therapeutic ultrasound and an ultrasound probe including a plurality of transducers, the method including the steps of: transmitting evaluation ultrasound having an intensity smaller than that of the therapeutic ultrasound to the therapeutic ultrasound transducer; acquiring, from each of the transducers, a reception signal based on the ultrasound received by each of the transducers; and measuring an intensity distribution of ultrasound arriving at the plurality of transducers based on the reception signal acquired from each of the transducers.

[0014] Preferably, the method includes a step of determining a concentration degree of ultrasonic waves received by each of the transducers based on the intensity distribution in the arrangement direction of the plurality of transducers. Effect of the Invention

[0015] According to the present invention, it is possible to evaluate the influence of ultrasonic waves transmitted from a therapeutic ultrasonic transducer on an ultrasonic imaging probe. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing the configuration of a HIFU irradiation device. [Diagram 2]FIG. 2 is a diagram illustrating n transducers provided in an ultrasonic imaging probe. [Diagram 3] 1A and 1B are diagrams illustrating an example of a phenomenon occurring near an ultrasonic imaging probe. [Figure 4] FIG. 13 is a diagram showing an example in which a distribution function I(x) is fitted to a plurality of measurement values ​​measured for a plurality of transducers. [Diagram 5] FIG. 13 is a diagram showing an example in which a distribution function I(x) is fitted to a plurality of measurement values ​​measured for a plurality of transducers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1 shows the configuration of a HIFU irradiation device 100 according to an embodiment of the present invention. The HIFU irradiation device 100 includes a HIFU transducer unit 10, an ultrasonic imaging probe 16, a coupling bag 18, an ultrasonic transmission / reception section 20, a control section 22, a HIFU driving section 24, and a display device 26. In the following description, for the sake of simplicity, the "ultrasonic imaging probe 16" will be simply expressed as the "ultrasonic probe 16."

[0018] The HIFU transducer unit 10 includes a container-shaped housing 12 with an opening facing downward, and a plurality of therapeutic ultrasound transducers 14 fixed to the housing 12. The plurality of therapeutic ultrasound transducers 14 are arranged, for example, in the shape of an imaginary curved surface that is convex upward, and are fixed to the housing 12 so that when each therapeutic ultrasound transducer 14 emits ultrasound, the intensity of the ultrasound is intensified at a therapeutic reference point Q below the housing 12. That is, each therapeutic ultrasound transducer 14 is fixed to the housing 12 so as to form a focal point F at the therapeutic reference point Q.

[0019] The ultrasonic probe 16 is attached to the housing 12 so that ultrasonic waves are transmitted and received at a position below the housing 12 and above the treatment reference point Q. In this embodiment, the ultrasonic probe 16 passes through the apex of the housing 12 in the vertical direction, and the tip that transmits and receives ultrasonic waves is directed downward. A plurality of imaging ultrasonic transducers 28 are disposed at the tip of the ultrasonic probe 16. The ultrasonic probe 16 may be movable in the vertical direction. The ultrasonic probe 16 may also be rotatable about its longitudinal axis. In the following description, the "imaging ultrasonic transducer 28" will be simply referred to as the "transducer 28" for the sake of simplicity.

[0020] A coupling bag 18 for matching acoustic impedance between each therapeutic ultrasonic transducer 14 and the patient, and between the ultrasonic probe 16 and the patient, is provided below the HIFU transducer unit 10. The coupling bag 18 may be a bag filled with a liquid such as water.

[0021] The control unit 22 may be configured by a computing device such as a personal computer, a tablet computer, etc. One or more computing devices may configure the control unit 22. An operation device (not shown) for a user to operate the HIFU irradiation device 100 is connected to the multiple control units 22. The operation device may include a mouse, a touch panel integrated with the display device 26, a switch, a keyboard, etc.

[0022] The HIFU driver 24 may include an electric circuit that drives each therapeutic ultrasonic transducer 14 to generate ultrasonic waves. The HIFU driver 24 causes each therapeutic ultrasonic transducer 14 to generate ultrasonic waves in response to the control of the control unit 22. The HIFU driver 24 also adjusts the intensity of the ultrasonic waves generated by each therapeutic ultrasonic transducer 14 in response to the control of the control unit 22.

[0023] The ultrasonic transmission / reception unit 20 includes an electric circuit that outputs electric signals to a plurality of transducers 28 included in the ultrasonic probe 16 and acquires the electric signals output from the transducers 28. The ultrasonic transmission / reception unit 20 executes the following process according to the control of the control unit 22. That is, the ultrasonic transmission / reception unit 20 causes the ultrasonic probe 16 to transmit imaging ultrasonic waves and scans with a beam (ultrasonic beam) of the transmitted imaging ultrasonic waves. The ultrasonic beam scans an observation plane including a central axis A extending vertically from the top of the housing 12. The ultrasonic transmission / reception unit 20 causes the ultrasonic probe 16 to receive reflected ultrasonic waves arriving from the direction in which the ultrasonic beam is directed, acquires reception signals based on the reflected ultrasonic waves received from each direction in which the ultrasonic beam is directed, and outputs the reception signals to the control unit 22.

[0024] The control unit 22 generates ultrasound data based on the received signal obtained at the observation surface. The ultrasound data may be irradiation area data indicating an area (cavitation area) where harmonic components are generated in the patient's biological tissue, or B-mode image data indicating a B-mode image (tomographic image) acquired for the patient's biological tissue.

[0025] Before the therapeutic ultrasound is irradiated from the HIFU transducer unit 10 to the patient, for example, the following positioning process is performed. The HIFU driver 24 causes each therapeutic ultrasound transducer 14 to transmit ultrasound with a lower intensity than that during treatment. The ultrasound transmission / reception unit 20, under the control of the controller 22, causes the ultrasound probe 16 to scan the observation surface with an ultrasound beam, obtains B-mode image data as ultrasound data, and outputs it to the controller 22. The controller 22 causes the display device 26 to display the B-mode image. The user as the practitioner refers to the B-mode image displayed on the display device 26 to confirm the difference between the focus F of the ultrasound transmitted from the HIFU transducer unit 10 and the position of the affected area.

[0026] When the difference between the position of the focal point F and the position of the affected area is not within an allowable range, the user changes the position or posture of the ultrasonic probe 16 and the HIFU transducer unit 10. After confirming that the position of the focal point F coincides with the position of the affected area, the user performs an operation for treatment on the control unit 22. The control unit 22 controls the HIFU driving unit 24 in response to the operation by the user. The HIFU driving unit 24 transmits therapeutic ultrasonic waves having an intensity required for treatment to each therapeutic ultrasonic transducer 14 in response to the control by the control unit 22. As a result, the living tissue is cauterized at the focal point F, and treatment is performed.

[0027] The HIFU irradiation device 100 performs a process of superimposing an image showing an irradiation area irradiated with the therapeutic ultrasonic wave on a B-mode image and displaying the image on the display device 26 while irradiating the patient with the therapeutic ultrasonic wave. Here, the process of superimposing and displaying two images may be a process of generating new image data by synthesizing image data so that one image can be seen through the other image, and displaying an image based on the new image data.

[0028] 2 shows n transducers 28-1 to 28-n provided in the ultrasonic probe 16. The transducers 28-1 to 28-n are linearly arranged in the long axis direction (x-axis direction) on the transmitting / receiving surface 38 of the ultrasonic probe 16 in the order of transducers 28-1, 28-2, 28-3, . . . 28-n. The positions on the x-axis of the transducers 28-1, 28-2, 28-3, . . . 28-n are x=x1, x2, x3, . . . , xn, respectively. Each transducer 28-1 to 28-n transmits ultrasonic waves from the transmitting / receiving surface 38 and receives ultrasonic waves arriving at the transmitting / receiving surface 38.

[0029] FIG. 3 is a diagram conceptually explaining an example of a phenomenon occurring near the ultrasonic probe 16 on a B-mode image 50. Between the ultrasonic probe 16 and the focal point F (treatment reference point Q) of the therapeutic ultrasonic wave, there is a reflective tissue 44 that reflects ultrasonic waves. In the example shown in FIG. 3, the reflective tissue 44 forms a reflective surface that spreads laterally. The therapeutic ultrasonic wave mainly propagates through an area sandwiched between two imaginary straight lines 40 that intersect at the focal point F. The ultrasonic wave (reflected wave) reflected by the reflective tissue 44 propagates upward and heads toward the reflected wave focal point RF near the transmitting / receiving surface 38 of the ultrasonic probe 16. The reflected wave mainly propagates through an area sandwiched between two imaginary straight lines 42. The left straight line 42 extends to the upper right from the intersection of the reflective surface of the reflective tissue 44 and the left straight line 40 at the same angle as the angle between the straight line 40 and the reflective surface. The right line 42 extends upward and to the left from the intersection of the reflecting surface of the reflecting tissue 44 and the right line 40 at the same angle as the angle between the line 40 and the reflecting surface. The left and right lines 42 intersect at the reflected wave focus RF at the end of their extension from the reflecting surface.

[0030] In this way, when there is a reflecting tissue 44 between the ultrasonic probe 16 and the focal point F of the therapeutic ultrasonic waves, the therapeutic ultrasonic waves are reflected upward by the reflecting tissue 44 toward the reflected wave focal point RF, and the energy of the reflected waves may be concentrated at the reflected wave focal point RF. Among the multiple transducers 28 of the ultrasonic probe 16, those in the vicinity of the reflected wave focal point RF may be subjected to thermal stress by the reflected waves, shortening their lifespan or failing to perform as intended.

[0031] Therefore, in the HIFU irradiation device 100 according to this embodiment, an evaluation process described below may be executed after the positioning process is completed and before the therapeutic ultrasound is irradiated to the patient from the HIFU transducer unit 10. In the evaluation process, among the multiple transducers 28 included in the ultrasound probe 16, one in which the energy of the reflected wave is concentrated is specified.

[0032] In the evaluation process, similarly to the positioning process, the HIFU driver 24 causes each therapeutic ultrasound transducer 14 to transmit an evaluation ultrasound having a lower intensity than that during treatment. The evaluation ultrasound converges on the focal point F, while a part of the evaluation ultrasound is reflected inside the patient's body and travels toward each transducer 28.

[0033] 1 and 2, transducers 28-1 to 28-n each receive ultrasonic waves reflected from inside the patient's body, generate electrical signals RS1 to RSn corresponding to the received ultrasonic waves, and output these to ultrasonic transmission / reception unit 20. Ultrasonic transmission / reception unit 20 measures the magnitudes of electrical signals RS1 to RSn, and outputs measurement values ​​U1 to Un to control unit 22.

[0034] The control unit 22 fits a distribution function to n measurement points in the scatter plot where values ​​corresponding to positions x=x1 to xn on the horizontal axis are measurement values ​​U1 to Un, respectively. The distribution function may be, for example, a function obtained by adding an offset B to a Gaussian function. Specifically, the control unit 22 determines the coefficient P, center value μ, standard deviation σ, and offset B of the Gaussian function as approximation parameters by a nonlinear least squares regression method such as the Levenberg Marquardt method so that the curve of the function approaches the n measurement points in the scatter plot.

[0035] A distribution function indicating the intensity distribution of the ultrasonic waves (arriving ultrasonic waves) arriving at the transmitting / receiving surface 38 of the ultrasonic probe 16 is expressed as shown in (Equation 1).

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[0036] The control unit 22 calculates the concentration degree C of the incoming ultrasonic waves according to (Equation 2) to (Equation 5). The concentration degree C is the product of fa, fb, and fe calculated by (Equation 3), (Equation 5), and (Equation 6), respectively.

[0037]

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[0038]

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[0039]

number

[0040]

number

[0041]

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[0042] Equation 4 indicates the average value m of n values ​​obtained by substituting the x coordinates of n measurement points on the scatter plot into Equation 1. Equation 3 means that the greater the coefficient P of the Gaussian function is the greater the average value m, the closer the concentration degree element fa is to 1, and the arriving ultrasonic waves are concentrated at a specific position. Equation 5 means that the smaller the offset B is than the average value m, the closer the concentration degree element fb is to 1, and the arriving ultrasonic waves are concentrated at a specific position. Equation 6 means that the smaller the standard deviation σ is, the closer the concentration degree element fe is to 1, and the arriving ultrasonic waves are concentrated at a specific position. Here, the specific position refers to the vicinity of the position where x = μ.

[0043] The degree of concentration C approaches 1 as the coefficient P of the Gaussian function is larger than the average value m, the offset B is smaller than the average value m, and the standard deviation σ is smaller, meaning that the arriving ultrasonic waves are concentrated at a specific position.

[0044] The concentration degree C may be defined by only one of the concentration degree elements fa, fb, and fe. Also, the concentration degree C may be defined by the product of any two of the concentration degree elements fa, fb, and fe.

[0045] When the concentration degree C exceeds the judgment value D, the control unit 22 causes the display device 26 to display warning information. The warning information indicates that there is a possibility that reflected waves will concentrate as incoming ultrasonic waves on a specific transducer 28 included in the ultrasonic probe 16. The user who has referred to the warning information may avoid the concentration of reflected waves on a specific position by, for example, adjusting the positional relationship between the patient and the HIFU transducer unit 10.

[0046] The control unit 22 may cause the display device 26 to display at least one of the n measurement points, the intensity distribution, the approximation parameters, and the concentration degree C in the scatter diagram.

[0047] 4 and 5 show an example in which a distribution function I(x) expressed by (Equation 1) is fitted to a plurality of measurement points obtained for a plurality of transducers 28 included in the ultrasonic probe 16. The intensity distribution 60 in each of Figs. 4 and 5 is obtained by connecting a plurality of measurement points, whose measured values ​​correspond to the x-coordinate values ​​of the plurality of transducers 28, with a curve. The intensity distribution 62 is obtained by fitting the distribution function I(x) to the intensity distribution 60.

[0048] In the example shown in FIG. 4, the fitting yields approximate parameters of coefficient P=784.526, center value μ=62.090, standard deviation σ=9.521, and offset B=87.189. Also, the average value m=232.322 is calculated. From these, the concentration degree elements are fa=0.996, fb=0.926, and fe=0.905, and the concentration degree C=0.834 is calculated. In the example shown in FIG. 4, the incoming ultrasonic waves are concentrated on the transducers 28 numbered 51 to 70. Therefore, by setting an appropriate judgment value D, warning information may be displayed on the display device 26 for the example shown in FIG. 4.

[0049] In the example shown in FIG. 5, the fitting yielded approximate parameters of coefficient P=1227.765, center value μ=139.820, standard deviation σ=8.555, and offset B=47.3. Also, the average value m=66.306 was calculated. From these, the concentration degree elements were fa=1.000, fb=0.490, and fe=0.015, and the concentration degree C=0.007 was calculated. In the example shown in FIG. 5, the ultrasonic intensity at both ends of the probe is high. This is because the transducer 28 is in contact with the patient's body surface via the coupling bag 18, and the ultrasonic waves are transmitted only to the transducers 28 at both ends that have a slight gap with the body surface. In general, this state is determined to be a state in which the incoming ultrasonic waves are not concentrated. Therefore, by setting an appropriate judgment value D, it is not necessary to display warning information on the display device 26 for the example shown in FIG. 5.

[0050] For example, by setting a judgment value D to a value between the concentration degree C in the example shown in FIG. 4 and the concentration degree C in the example shown in FIG. 5, warning information that can prevent thermal stress on the ultrasonic imaging probe is displayed on the display device 26.

[0051] In this manner, the control unit 22 included in the HIFU irradiation device 100 according to this embodiment executes an ultrasonic wave transmission process, an ultrasonic wave reception process, and a distribution measurement process. The ultrasonic wave transmission process is a process of causing the therapeutic ultrasonic transducer 14 to transmit an evaluation ultrasonic wave having a smaller intensity than the therapeutic ultrasonic wave. The ultrasonic wave reception process is a process of acquiring, from each transducer 28, a reception signal based on the ultrasonic wave received by each transducer 28. The distribution measurement process is a process of measuring the intensity distribution of the ultrasonic waves arriving at the plurality of transducers 28 based on the reception signal acquired from each transducer 28.

[0052] The control unit 22 calculates the concentration degree C of the ultrasound received by each transducer 28 based on the intensity distribution in the arrangement direction of the multiple transducers 28, and performs a process of evaluating the effect of the therapeutic ultrasound on each transducer 28 based on the concentration degree C.

[0053] The transducers 28 may be arranged in a straight line. The intensity distribution may be represented by a distribution function having one peak for a vertical axis value with respect to a horizontal axis extending in the arrangement direction of the transducers 28. The control unit 22 may also execute an evaluation process for evaluating the influence of the therapeutic ultrasound on each transducer 28 using approximation parameters that define the distribution function. The evaluation process is a process for evaluating the influence of the therapeutic ultrasound on each transducer 28 based on the intensity distribution. The influence of the therapeutic ultrasound on each transducer 28 includes an effect in which the therapeutic ultrasound is concentrated on a specific transducer 28, causing a change in the operating characteristics of the specific transducer 28, and the like.

[0054] The control unit 22 evaluates the state of the HIFU irradiation apparatus 100 by a method including the following steps (i) to (vi). Each step may be executed by a calculation device such as a computer provided outside the HIFU irradiation apparatus 100 and connected to the control unit 22 in accordance with a user's operation.

[0055] (i) A step of transmitting an evaluation ultrasound having an intensity lower than that of the therapeutic ultrasound to the therapeutic ultrasound transducer 14. (ii) acquiring, from each transducer 28, a reception signal based on the ultrasonic waves received by each transducer 28; (iii) measuring the intensity distribution of ultrasonic waves arriving at the plurality of transducers 28 based on the reception signals acquired from each transducer 28; (iv) determining the concentration of the ultrasonic waves received by each transducer 28 based on the intensity distribution in the arrangement direction of the plurality of transducers 28;

[0056] For the distribution function I(x), instead of the Gaussian function, a Lorentz function with an offset B added thereto, as shown in (Equation 7), may be used. The Lorentz function shown in (Equation 7) represents a distribution that is centered at the position of x=μ and approaches the offset B according to the inverse of a quadratic function as the x coordinate value moves away from the central value μ. The kurtosis k in (Equation 7) is a positive number that indicates the degree to which the distribution is upwardly convex as the value becomes smaller. The kurtosis k may be a value calculated based on a normal distribution.

[0057]

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[0058] When the Lorentz function expressed by (Equation 7) is used as the distribution function, the concentration degree C may be one of the concentration degree elements fa and fb, or the product of the concentration degree elements fa and fb. [Explanation of symbols]

[0059] 10 HIFU transducer unit, 12 housing, 14 therapeutic ultrasound transducer, 16 ultrasound imaging probe (ultrasound probe), 18 coupling bag, 20 ultrasound transmission / reception unit, 22 control unit, 24 HIFU drive unit, 26 display device, 28, 28-1 to 28-n imaging ultrasound transducer (transducer), 38 transmission / reception surface, 40, 42 straight line, 44 reflecting tissue, 50 B-mode image, 60, 62 intensity distribution.

Claims

1. A therapeutic ultrasound transducer for transmitting therapeutic ultrasound; An ultrasonic probe having a plurality of transducers; a control unit for controlling the therapeutic ultrasound transducer and the ultrasound probe, The control unit is an ultrasound transmission process for transmitting evaluation ultrasound having an intensity lower than that of the therapeutic ultrasound to the therapeutic ultrasound transducer; an ultrasonic reception process for acquiring, from each of the transducers, a reception signal based on the ultrasonic waves received by each of the transducers; A distribution measurement process for measuring an intensity distribution of ultrasonic waves arriving at the plurality of transducers based on the reception signals acquired from each of the transducers; A HIFU irradiation device that performs the above steps.

2. 2. The HIFU irradiation device according to claim 1, The control unit is A HIFU irradiation device, comprising: a process for determining a concentration degree of ultrasonic waves received by each of said transducers based on said intensity distribution in an arrangement direction of said plurality of transducers.

3. 3. The HIFU irradiation device according to claim 1 or 2, the intensity distribution is represented by a distribution function having one peak at a value on a vertical axis with respect to a horizontal axis extending in an arrangement direction of the plurality of transducers, The control unit is The HIFU irradiation device performs an evaluation process for evaluating the influence of the therapeutic ultrasound on each of the transducers using approximation parameters that define the distribution function.

4. 4. The HIFU irradiation device according to claim 3, The HIFU irradiation device, wherein the distribution function includes a Gaussian function or a Lorentz function.

5. A therapeutic ultrasound transducer for transmitting therapeutic ultrasound; A method for evaluating a state of a HIFU irradiation device comprising an ultrasound probe having a plurality of transducers, the method comprising: A step of transmitting an evaluation ultrasound having an intensity lower than that of the therapeutic ultrasound to the therapeutic ultrasound transducer; acquiring, from each of the transducers, a reception signal based on an ultrasonic wave received by each of the transducers; Measuring an intensity distribution of ultrasonic waves arriving at the plurality of transducers based on the reception signals acquired from each of the transducers; The method according to claim 1, further comprising:

6. 6. The method of claim 5, A method comprising the step of determining a concentration degree of ultrasound received by each of the transducers based on the intensity distribution in an arrangement direction of the plurality of transducers.

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