Hifu irradiation device

Abstract

An objective of the present invention is to facilitate an operation for aligning the position of the focal point of therapeutic ultrasonic waves with a treatment site. A controller (22) executes: a transmission process for transmitting push waves from a plurality of ultrasonic transducers (32) to biological tissue; and a search process for determining focus information, about the focal point (F) of ultrasonic waves generated by the plurality of ultrasonic transducers (32), on the basis of B-mode image data acquired by a data acquisition unit (16). The focus information is information indicating at least one of the region in which the focal point (F) is present or the position of the focal point (F). The search process includes a process for measuring the movement of shear waves generated in the biological tissue by the push waves and determining the focus information on the basis of the movement of the shear waves. The controller (22) causes a display unit (20) to display a positioning image in which a figure indicating at least one of the region in which the focal point (F) is present or the position of the focal point (F) is superimposed on a B-mode image.

Description

HIFU irradiation device

[0001] The present invention relates to a HIFU irradiation device, and more particularly to a process for searching for the focus of ultrasound waves emitted from multiple ultrasound transducers for treatment.

[0002] A treatment device using high intensity focused ultrasound (HIFU) is widely used. This treatment device is called a HIFU irradiation device or a HIFU irradiation system, and irradiates a treatment site with focused ultrasound to cause necrosis of biological tissue.

[0003] Generally, a HIFU irradiation device includes a plurality of ultrasonic transducers for treatment arranged along a concave surface. The plurality of ultrasonic transducers are arranged so that ultrasonic waves emitted from each of the transducers are irradiated at a single point to form a focal point. During treatment, the focal point is aligned with the treatment area and ultrasonic waves are irradiated. To confirm the irradiation position, an ultrasonic diagnostic device that displays the focal point on an ultrasound image is used.

[0004] The following Patent Document 1 describes an ultrasound treatment device that observes the position of a focal point using an ultrasound diagnostic device that displays B-mode images (tomographic images based on ultrasound echo intensity). In this device, a therapeutic ultrasound transducer emits ultrasound at a low level that does not affect tissue, and an ultrasound imaging probe transmits and receives ultrasound to display a tomographic image. Because the acoustic properties of the patient's tissue change depending on changes in tissue temperature, the tomographic image shows the position of the focal point by varying brightness. Furthermore, as shown in Non-Patent Document 1, because the irradiation of the patient's tissue with ultrasound causes displacement, the tomographic image shows the position of the focal point by varying brightness.

[0005] Japanese Patent Application Publication No. 8-71069

[0006] Tissue hardness measurement using ARFI via the Internet<https: / / www.innervision.co.jp / sp / ad / suite / siemens / technical_notes / 140368>

[0007] In treatment using high-intensity focused ultrasound, if there is an area in the patient's tissue with acoustic properties different from the surrounding area, the ultrasound emitted from the therapeutic ultrasound transducer will be refracted. This can cause the actual focal position to deviate from the expected focal position if the acoustic properties were uniform. This can make it difficult to align the focal position of the therapeutic ultrasound to the treatment area.

[0008] An object of the present invention is to facilitate the operation of adjusting the position of the focal point of therapeutic ultrasound to the treatment site.

[0009] The HIFU irradiation device according to the present invention comprises a plurality of ultrasonic transducers for treatment, an ultrasonic probe for acquiring B-mode image data, a transducer control unit for controlling the plurality of ultrasonic transducers, a data acquisition unit for acquiring the B-mode image data by the ultrasonic probe, and a controller for controlling the transducer control unit and the data acquisition unit, wherein the controller executes a transmission process for transmitting push waves from the plurality of ultrasonic transducers to biological tissue, and a search process for obtaining focus information related to the focus of the ultrasonic waves emitted from the plurality of ultrasonic transducers based on the B-mode image data, wherein the focus information represents at least one of an area where the focus exists and a position of the focus, and the search process includes a process for measuring the movement of shear waves generated in the biological tissue by the push waves and obtaining the focus information based on the movement of the shear waves.

[0010] In one embodiment, the search process includes a process of determining changes in the positions of multiple maximum points of the shear wave, the multiple maximum points traveling in different directions, and a process of determining at least one of a generation region and a generation point where the shear wave is generated based on the changes in the positions of each of the maximum points, and determining the focus information based on at least one of the generation region and the generation point.

[0011] In one embodiment, the search process includes a process of estimating the position of each of the maximum points at the time when the shear wave occurs based on changes in the position of each of the maximum points, and determining the focus information based on the estimated position of each of the maximum points.

[0012] In one embodiment, the search process includes a process of determining the focus information based on the coordinates of the intersection of a straight line or curve represented by the approximation function for one of the two maximum points of the shear wave moving in different directions and a straight line or curve represented by the approximation function for the other of the two maximum points moving in different directions, when the relationship between position and time is represented by an approximation function.

[0013] In one embodiment, the controller determines the focus information for a depth in the biological tissue at which the maximum value of the shear wave exceeds a predetermined threshold when a predetermined time has elapsed since the push wave was transmitted.

[0014] In one embodiment, the controller obtains the focus information for a depth in the biological tissue at which the maximum value of the shear wave is greatest when a predetermined time has elapsed since the push wave was transmitted, and obtains the position of the focus at the depth at which the maximum value of the shear wave is greatest.

[0015] In one embodiment, the plurality of ultrasonic transducers are arranged along a concave surface, and the ultrasonic probe is arranged on a central axis of the concave surface.

[0016] According to the present invention, the operation of adjusting the focal position of therapeutic ultrasound to the treatment site can be facilitated.

[0017] 1 is a diagram showing the configuration of a HIFU irradiation device. FIG. 1 is a diagram schematically showing how shear waves are generated from the focus of a push wave. FIG. 2 is an enlarged view of the amplitude intensity distribution of shear waves. FIG. 3 is a diagram showing a cross section of the amplitude intensity distribution of shear waves. FIG. 4 is a diagram showing an example of a B-mode image acquired with the long axis of the ultrasound probe aligned with the y-axis direction and the observation plane aligned with the yz plane. FIG. 5 is a diagram showing an example of a B-mode image acquired with the long axis of the ultrasound probe aligned with the y-axis direction and the observation plane aligned with the yz plane. FIG. 6 is a diagram showing an example of a B-mode image acquired with the long axis of the ultrasound probe aligned with the y-axis direction and the observation plane aligned with the yz plane. FIG. 7 is a diagram showing an example of the amplitude of shear waves at a certain depth z=D in biological tissue and at times t=t1, t2, and t3. FIG. 8 is a diagram showing examples of a first approximation line and a second approximation line on a ty-plane. FIG. 9 is a diagram showing an example of a positioning image.

[0018] An embodiment of the present invention will be described with reference to the drawings. Identical components shown in multiple drawings are designated by the same reference numerals to simplify the description. Fig. 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 probe 12, a coupling bag 24, a probe driver 14, a data acquisition unit 16, a transducer controller 18, a display unit 20, and a controller 22.

[0019] 1 shows a cross section of a HIFU transducer unit 10. The HIFU transducer unit 10 includes a transducer housing 26 having a concave surface 30 with an opening facing downward, and a plurality of ultrasound transducers 32 arranged along the concave surface 30 of the transducer housing 26 and fixed to the transducer housing 26. The HIFU transducer unit 10 does not necessarily have to have an actual concave surface 30. In this case, the plurality of ultrasound transducers 32 may be fixed to the transducer housing 26 so as to be arranged along a virtual concave surface.

[0020] The concave surface 30 of the transducer housing 26 may have a shape similar to the side surface of a pyramid. Here, a pyramid refers to a three-dimensional shape formed by a collection of straight lines extending from a point in space to the bottom surface. The concave surface 30 of the transducer housing 26 may also have a dome-like bulge on the upper side. Each ultrasonic transducer 32 is fixed to the transducer housing 26 so that when each ultrasonic transducer 32 emits ultrasound, the intensity of the ultrasound is increased at a treatment reference point P below the transducer housing 26. Here, the treatment reference point P is a point within the treatment area or included in the treatment area.

[0021] The controller 22 may be a personal computer, a tablet computer, or the like. The controller 22 may realize each function by executing a program. An operating device (not shown) for a user to operate the HIFU irradiation device 100 is connected to the controller 22. The operating device may include a mouse, a touch panel integrated with the display unit 20, a switch, a keyboard, or the like.

[0022] The transducer control unit 18 may be configured by a processor that executes a program to control each ultrasonic transducer 32. The transducer control unit 18 causes each ultrasonic transducer 32 to generate ultrasonic waves in accordance with the control of the controller 22. Furthermore, the transducer control unit 18 adjusts at least one of the intensity and delay time of the ultrasonic waves generated by each ultrasonic transducer 32 in accordance with the control of the controller 22.

[0023] The ultrasonic probe 12, which extends in the vertical direction, is attached to the transducer housing 26 so that ultrasonic waves are transmitted and received at a position below the transducer housing 26 and above the treatment reference point P. In this embodiment, the ultrasonic probe 12 passes through the apex of the concave surface 30 of the transducer housing 26 in the vertical direction, and the transmitting and receiving unit 28 that transmits and receives ultrasonic waves faces downward.

[0024] A coupling bag 24 is provided below the HIFU transducer unit 10 to match acoustic impedance between each ultrasonic transducer 32 and the patient, and between the ultrasonic probe 12 and the patient. The coupling bag 24 may be a bag filled with a liquid such as water. The ultrasonic probe 12 passes through the coupling bag 24 from above to inside, and a transmitting / receiving unit 28 is located inside the coupling bag 24.

[0025] The movable body including the HIFU transducer unit 10, the probe driver 14, and the coupling bag 24 may be attached to a transport mechanism such as a robot arm. The transport mechanism may be controlled by a controller 22. The controller 22 controls the transport mechanism according to, for example, a user's operation. The transport mechanism may transport the movable body and adjust the position of the movable body according to the control of the controller 22.

[0026] An ultrasound diagnostic device may be used as the data acquisition unit 16. The data acquisition unit 16 performs the following processing in accordance with the control of the controller 22. That is, the data acquisition unit 16 causes the ultrasound probe 12 to transmit ultrasound waves and causes scanning with a beam of the transmitted ultrasound waves (ultrasonic beam).

[0027] The transmitting / receiving unit 28 of the ultrasonic probe 12 has defined major and minor axis directions, and an ultrasonic beam is scanned across an observation surface 44 that extends in the major axis direction and in a direction away from the transmitting / receiving unit 28. The ultrasonic probe 12 is attached to the HIFU transducer unit 10 along a central axis 40 that passes vertically through the apex of the concave surface 30 of the transducer housing 26.

[0028] The data acquisition unit 16 causes the ultrasonic probe 12 to receive reflected ultrasonic waves arriving from the direction in which the ultrasonic beam is directed, and acquires reception signals based on the reflected ultrasonic waves received from each direction in which the ultrasonic beam is directed. The data acquisition unit 16 generates ultrasound data based on the reception signals obtained at the observation plane 44, and outputs the ultrasound data to the controller 22. The ultrasound data may be, for example, data indicating a B-mode image (tomographic image) acquired for the observation plane 44 (hereinafter referred to as B-mode image data).

[0029] The ultrasonic probe 12 is rotatable around a central axis 40 by a probe driver 14. The probe driver 14 rotates the ultrasonic probe 12 around the central axis 40 relative to the HIFU transducer unit 10. That is, the probe driver 14 rotates the ultrasonic probe 12 around the central axis 40 and rotates an observation surface 44 of the ultrasonic probe 12 around the central axis 40 in accordance with the control of the controller 22.

[0030] During treatment, the coupling bag 24, the ultrasonic probe 12, and the HIFU transducer unit 10 are positioned so that the lower part of the coupling bag 24 is in close contact with the patient. Before the therapeutic ultrasonic waves are irradiated from the HIFU transducer unit 10 to the patient, the following positioning process is performed.

[0031] In the positioning process, the controller 22 executes a transmission process in which push waves are transmitted to biological tissue from the multiple ultrasound transducers 32 included in the HIFU transducer unit 10, and a search process in which focus information regarding the focus F of the ultrasound waves emitted from the multiple ultrasound transducers 32 is obtained based on the B-mode image data acquired by the data acquisition unit 16. Here, the focus information is information that indicates at least one of the region in which the focus F exists and the position of the focus F.

[0032] Furthermore, a push wave refers to an ultrasonic pulse that forms a focal point within biological tissue and excites shear waves in the biological tissue from that focal point. The push wave may be an ultrasonic wave whose main component is a compressional wave. A shear wave refers to a wave whose main component is a wave that displaces in a specific direction relative to the propagation direction. The search process includes a process of measuring the movement of the shear wave generated in the biological tissue by the push wave and determining focal point information based on the movement of the shear wave. Note that there are no limitations on the characteristics of the push wave, such as its intensity or wave train length, as long as it generates shear waves in the target biological tissue.

[0033] The controller 22 causes the display unit 20 to display a positioning image in which a graphic indicating at least one of the region where the focus F exists and the position of the focus F is superimposed on the B-mode image. The display unit 20 may be a liquid crystal display, an organic EL display, or an information processing device such as a computer or smartphone using such a display.

[0034] The user refers to the positioning image and confirms the difference between the position of the focal point F and the position of the treatment reference point P. If the difference between the position of the focal point F and the position of the treatment reference point P is not within the allowable range, the user changes the positions or postures of the coupling bag 24, the ultrasound probe 12, and the HIFU transducer unit 10. Alternatively, the user changes the contact state between the coupling bag 24 and the patient. After confirming that the position of the focal point F matches the position of the treatment reference point P or that the difference between the position of the focal point F and the position of the treatment reference point P is within the allowable range, the user performs an operation for treatment on the controller 22.

[0035] The controller 22 controls the transducer control unit 18 in response to a user's operation. The transducer control unit 18 causes each ultrasound transducer 32 to transmit therapeutic ultrasound waves having an intensity required for treatment in response to control by the controller 22. This cauterizes the living tissue at the focus F, thereby providing treatment.

[0036] The transmission process and search process executed in the positioning process will now be described. In response to a user's operation, the controller 22 controls the transducer control unit 18 so that each ultrasonic transducer 32 transmits a push wave that converges on the focal point F. In response to the control of the controller 22, the transducer control unit 18 causes each ultrasonic transducer 32 to transmit a push wave.

[0037] 2(a) to 2(d) schematically show how shear waves 50 are generated from the focal points F of push waves 48 emitted from each ultrasound transducer 32 in the HIFU transducer unit 10. In Fig. 2, the direction downward from the HIFU transducer unit 10 is the positive z-axis direction, and an xy plane perpendicular to the positive z-axis direction is defined.

[0038] FIG. 2( a ) shows a propagation region 46 through which a push wave 48 propagates and a focal point F. FIG. 2( a ) shows the state in which the push wave 48 converges at the focal point F and a shear wave is generated from this. FIGS. 2( b ) to 2 ( d ) show the state in which a shear wave 50 propagates in a direction away from the focal point over time. In FIGS. 2( b ) to 2 ( d ), the shear wave 50 is represented by its amplitude intensity distribution. Here, the amplitude intensity distribution of the shear wave 50 is represented by the amplitude component in the z-axis direction using shades of black and white. Regions with larger amplitude components in the z-axis direction are given darker colors.

[0039] Fig. 3A shows an enlarged view of the amplitude intensity distribution of the shear wave 50, and Fig. 3B shows a cross section of the amplitude intensity distribution of the shear wave 50. As shown in Figs. 2(b) to 2(d) and 3, the amplitude intensity distribution (energy distribution) of the shear wave 50 spreads in a donut shape along the xy plane with the focal point as time elapses.

[0040] 1 , the controller 22 controls the transducer control unit 18 so that each ultrasound transducer 32 transmits a push wave that converges at a focal point F, and also controls the data acquisition unit 16 so that B-mode image data is acquired. That is, the data acquisition unit 16 causes the ultrasound probe 12 to transmit ultrasound waves and scan the observation plane 44 with an ultrasound beam.

[0041] The data acquisition unit 16 causes the ultrasonic probe 12 to receive reflected ultrasonic waves arriving from the direction in which the ultrasonic beam is directed, and acquires reception signals based on the reflected ultrasonic waves received from each direction in which the ultrasonic beam is directed. The data acquisition unit 16 generates B-mode image data based on the reception signals obtained at the observation plane 44, and outputs the data to the controller 22.

[0042] The data acquisition unit 16 repeatedly scans with the ultrasonic beam, generates B-mode image data sequentially over time, and outputs the data to the controller 22. The controller 22 sequentially displays B-mode images based on the B-mode image data output from the data acquisition unit 16 on the display unit 20 sequentially over time.

[0043] 4A to 4C show examples of B-mode images acquired with the long axis of the ultrasound probe 12 aligned with the y-axis direction and the observation plane 44 aligned with the yz plane. The B-mode image in FIG. 4B is an image based on B-mode image data acquired later than the time at which the B-mode image data representing the B-mode image in FIG. 4A was acquired. The B-mode image in FIG. 4C is an image based on B-mode image data acquired later than the time at which the B-mode image data representing the B-mode image in FIG. 4B was acquired. That is, FIGS. 4A, 4B, and 4C are B-mode images based on B-mode image data acquired at times t=t1, t2, and t3, respectively, where time t=t2 is later than time t=t1 and time t=t3 is later than time t=t2.

[0044] In the example shown in Figures 4A to 4C, the geometric focus is located at a position (z, y) = (8 mm, 0 mm). Here, the geometric focus is a focal position determined by a theory based on physics and geometry, based on the position of each ultrasonic transducer 32 and the intensity and delay time of the ultrasonic waves generated by each ultrasonic transducer 32. The horizontal axis in Figures 4A to 4C indicates the distance y from the geometric focus. In the following description, the distance y from the geometric focus may be referred to as the y coordinate value.

[0045] In the B-mode images shown in Figures 4A to 4C, areas with larger shear wave amplitudes are colored closer to white, and areas with smaller shear wave amplitudes are colored closer to black. An indicator that associates pixel shading (lightness / darkness) with pixel values ​​is shown on the right side of each image. As shown in Figures 4A to 4C, the shear waves shown in lighter colors move away from the geometric focus over time.

[0046] 5 shows an example of the amplitude of a shear wave at a depth z = D in biological tissue and at times t = t1, t2, and t3. The horizontal axis represents the y-coordinate value [mm], and the vertical axis represents the amplitude of the shear wave. The units [a.u.] on the vertical axis indicate arbitrary units. The amplitude of the shear wave may be, for example, a value normalized by the average value of the amplitude intensity distribution of the shear wave in the yz plane, or a value normalized by the square root of the energy of the shear wave on the yz plane.

[0047] In the example shown in Figure 5, the time when each ultrasonic transducer 32 transmits a push wave is defined as t = 0, and t1 = 2.0 [msec], t2 = 2.5 [msec], and t3 = 3.0 [msec]. The maximum point of the amplitude of the shear wave moves away from the geometric focus over time. The amplitude value at the maximum point of the amplitude of the shear wave, i.e., the maximum value, decreases with increasing distance from the geometric focus. In Figure 5, the maximum point moving in the positive y-axis direction (rightward) over time is indicated by a black circle. The maximum point moving in the negative y-axis direction (leftward) over time is indicated by a black rectangle.

[0048] When the controller 22 determines a first approximate function that indicates the relationship between the y-coordinate value of a maximum point moving in the positive direction of the y-axis and time t, and a second approximate function that indicates the relationship between the y-coordinate value of a maximum point moving in the negative direction of the y-axis and time, the controller 22 determines the time t = t0 at the intersection of the curve or straight line indicated by the first approximate function on the ty-plane and the curve or straight line indicated by the second approximate function on the ty-plane.

[0049] For example, for the local maximum points moving in the positive direction of the y-axis, the controller 22 determines a first approximation function that indicates a straight line or a curve that approximates and represents the y-coordinate values ​​at all times t, not just at times t=t1, t2, and t3, by regression analysis using least squares approximation, etc. Furthermore, for the local maximum points moving in the negative direction of the y-axis, the controller 22 determines a second approximation function that indicates a straight line or a curve that approximates and represents the y-coordinate values ​​at all times t, not just at times t=t1, t2, and t3, by regression analysis using least squares approximation, etc.

[0050] The first approximation function is a function that represents the movement of the shear wave in terms of the movement of the local maximum point moving in the positive direction of the y-axis. The slope of the linear function indicates the velocity of the local maximum point moving in the positive direction of the y-axis. The second approximation function is a function that represents the movement of the shear wave in terms of the movement of the local maximum point moving in the negative direction of the y-axis. The slope of the quadratic function indicates the velocity of the local maximum point moving in the negative direction of the y-axis.

[0051] 6 shows an example of a first approximate line 60-1 indicated by the first approximate function and a second approximate line 60-2 indicated by the second approximate function on the ty-y plane. In the example shown in FIG. 6, the first approximate function and the second approximate function are linear functions, and the first approximate line 60-1 and the second approximate line 60-2 are straight lines.

[0052] The controller 22 determines the coordinates (y, t) = (A0(D), t0) of the intersection of the first approximation line 60-1 and the second approximation line 60-2, where A0(D) is the value determined for the depth z = D.

[0053] The controller 22 determines the position on the yz plane expressed as (y, z) = (A0(D), D) as the estimated position of the focal point. Here, the estimated position of the focal point is the position of the focal point searched under the limited condition that the depth in the biological tissue is z = D.

[0054] As one processing example, the controller 22 determines, as the focal depth, the depth z = Df at which the amplitude value of the maximum point proceeding in the positive y-axis direction or the negative y-axis direction is maximized when viewed in the z-axis direction at a predetermined time, for example, time t = t1, t2, or t3. The controller 22 may determine the coordinates (y, t) = (A0(Df), t0) of the intersection of the first approximation line 60-1 and the second approximation line 60-2 for the focal depth z = Df, and determine the position (y, z) = (A0(Df), Df) in the yz plane as the position of the focal point. The controller 22 may cause the display unit 20 to display a positioning image in which a focal point figure representing the focal point whose position has been determined in this manner is superimposed on a B-mode image.

[0055] As another processing example, the controller 22 may determine, as the focal depth range, a range in the z-axis direction in which the magnitude of the shear wave at a predetermined time, for example, t=t1, t2, or t3, satisfies a predetermined z-direction condition. This z-direction condition may be a range in which the amplitude value of the local maximum point moving in the positive y-axis direction exceeds a predetermined threshold, and the amplitude value of the local maximum point moving in the negative y-axis direction also exceeds a predetermined threshold.

[0056] In this case, the controller 22 determines the range in the z-axis direction in which the amplitude value of the local maximum point moving in the positive y-axis direction exceeds a predetermined threshold and the amplitude value of the local maximum point moving in the negative y-axis direction exceeds a predetermined threshold as the focal depth range. The controller 22 may determine, at the position y = A0(Df), a straight line extending across the focal depth range in the z-axis direction as the focal line (one form of a focal region described later). The controller 22 may cause the display unit 20 to display a positioning image in which a focal line figure representing the focal line is superimposed on the B-mode image.

[0057] As yet another processing example, the controller 22 determines the value y=D1 of the first approximation function at time t=0 and the value y=D2 of the second approximation function at time t=0. The controller 22 determines the range in the y-axis direction determined by D2≦y≦D1 as the focal lateral range. The controller 22 determines the rectangular region determined by the focal lateral range and the above-mentioned focal depth range as the focal region. The focal region is an area estimated as an area where shear waves are generated, and is an area where the focus F of the therapeutic ultrasound exists.

[0058] The controller 22 may cause the display unit 20 to display a positioning image in which a focal region graphic, such as a rectangle representing a focal region, is superimposed on a B-mode image. Fig. 7 shows a positioning image in which a rectangular focal region graphic 70 is superimposed on a B-mode image. In the example shown in Fig. 7, the focal region is indicated by the focal region graphic 70 drawn in a rectangular frame on the B-mode image at time t = t1.

[0059] The above describes a process for determining a focus, a focal line, or a focal region based on the positions of two local maxima moving in different directions determined for three times t = t1, t2, and t3. The focus, a focal line, or a focal region may also be determined based on the positions of two local maxima moving in different directions determined for two or four or more times.

[0060] Alternatively, the positioning process may be performed for each of a plurality of rotational angle positions around the central axis 40 of the ultrasonic probe 12. In this case, the controller 22 controls the probe driver 14 in response to a user operation so as to adjust the rotational angle position of the ultrasonic probe 12. The probe driver 14 rotates the ultrasonic probe 12 around the central axis 40 and rotates the observation surface 44 of the ultrasonic probe 12 around the central axis 40 in response to the control of the controller 22. By performing the positioning process for each of a plurality of rotational angle positions of the observation surface 44 around the central axis 40, the position of the focal point F can be more accurately brought closer to or aligned with the treatment reference point P.

[0061] In the HIFU irradiation device 100 according to this embodiment, push waves are transmitted to biological tissue from multiple ultrasound transducers 32 used in treatment, generating shear waves in the biological tissue. The HIFU irradiation device 100 transmits push waves from the multiple ultrasound transducers 32, acquires B-mode image data, and measures the movement of the maximum point of the shear wave based on the B-mode image data. The HIFU irradiation device 100 estimates the focus where the shear wave is generated based on the movement of the maximum point, and determines the focus, focal line, or focal region, and displays it on the display unit 20. Displaying the focus, focal line, or focal region on the display unit 20 facilitates the user's task of aligning the treatment reference point P with the focus.

[0062] The above describes a search process for determining a focal point, focal line, or focal region based on the change in the position of the local maximum of the shear wave moving in the positive and negative y-axis directions. The search process may also be generalized as follows:

[0063] That is, the search process may include a process of determining a change in the position of each of the multiple maximum points of the shear wave, a process of determining at least one of a generation region and a generation point where the shear wave occurs based on the change in the position of each maximum point, and a process of determining focus information based on at least one of the generation region and the generation point. However, the multiple maximum points of the shear wave are multiple maximum points moving in different directions. In the above embodiment, the generation region is determined as a focal line or a focal region.

[0064] The search process may also include estimating the position of each local maximum point at the time when the shear wave occurs based on the change in the position of each local maximum point, and determining focus information based on the estimated position of each local maximum point. In the above embodiment, the occurrence time corresponds to time t = t0.

[0065] 10 HIFU transducer unit, 12 ultrasonic probe, 14 probe driver, 16 data acquisition unit, 18 transducer control unit, 20 display unit, 22 controller, 24 coupling bag, 26 transducer housing, 28 transmitter / receiver unit, 30 concave surface, 32 ultrasonic transducer, 40 central axis, 44 observation surface, 46 propagation region, 48 push wave, 50 shear wave, 60-1 first approximation line, 60-2 second approximation line, 70 focal region figure, 100 HIFU irradiation device.

Claims

1. A HIFU irradiation device comprising: a plurality of ultrasonic transducers for treatment; an ultrasonic probe for acquiring B-mode image data; a transducer control unit for controlling the plurality of ultrasonic transducers; a data acquisition unit for acquiring the B-mode image data by the ultrasonic probe; and a controller for controlling the transducer control unit and the data acquisition unit, wherein the controller executes a transmission process for transmitting push waves from the plurality of ultrasonic transducers to biological tissue; and a search process for obtaining focus information regarding the focus of ultrasound emitted from the plurality of ultrasonic transducers based on the B-mode image data, wherein the focus information represents at least one of an area where the focus exists and a position of the focus, and the search process includes a process for measuring the movement of shear waves generated in the biological tissue by the push waves and obtaining the focus information based on the movement of the shear waves.

2. A HIFU irradiation device according to claim 1, wherein the search process includes: a process for determining a change in the position of each of a plurality of maximum points of the shear wave, the maximum points being those moving in different directions; and a process for determining at least one of a generation region and a generation point where the shear wave is generated based on the change in the position of each of the maximum points, and for determining the focus information based on at least one of the generation region and the generation point.

3. A HIFU irradiation device according to claim 2, wherein the search process includes a process of estimating the position of each of the maximum points at the time when the shear wave is generated based on a change in the position of each of the maximum points, and determining the focus information based on the estimated position of each of the maximum points.

4. A HIFU irradiation device according to claim 2, wherein the search process includes a process for determining the focus information based on the coordinates of the intersection of a straight line or curve expressed by the approximation function for one of the two maximum points of the shear wave moving in different directions with a straight line or curve expressed by the approximation function for the other of the two maximum points moving in different directions, when the relationship between position and time is expressed by an approximation function.

5. A HIFU irradiation device according to any one of claims 2 to 4, wherein the controller determines the focus information for a depth in the biological tissue at which the maximum value of the shear wave exceeds a predetermined threshold value when a predetermined time has elapsed since the push wave was transmitted.

6. A HIFU irradiation device according to any one of claims 2 to 4, wherein the controller determines the focus information for a depth in the biological tissue at which the maximum value of the shear wave is greatest when a predetermined time has elapsed since the push wave was transmitted, and determines the position of the focus at the depth at which the maximum value of the shear wave is greatest.

7. A HIFU irradiation device according to any one of claims 1 to 4, characterized in that the plurality of ultrasonic vibrators are arranged along a concave surface, and the ultrasonic probe is arranged on the central axis of the concave surface.

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