Ultrasound therapy device

Abstract

The objective of this invention is to appropriately display the focal point of therapeutic ultrasound. [Solution] The control unit 30 performs a first image generation process, an ultrasonic irradiation process, a second image generation process, a correlation calculation process, and a display process. The first image generation process is the process of causing the ultrasonic probe 16 to transmit imaging ultrasonic waves and generating a first ultrasonic image data based on the first reflected ultrasonic waves received by the ultrasonic probe 16. The ultrasonic irradiation process is the process of irradiating the ultrasonic transducer 28 with ultrasonic waves. The second image generation process is the process of causing the ultrasonic probe 16 to transmit imaging ultrasonic waves after the ultrasonic waves have been irradiated and generating a second ultrasonic image data based on the second reflected ultrasonic waves received by the ultrasonic probe 16. The correlation calculation process is the process of determining the degree of similarity distribution between the first ultrasonic image and the second ultrasonic image. The display process is the process of displaying the degree of similarity distribution.

Description

Technical Field

[0001] The present invention relates to an ultrasonic treatment apparatus, and particularly to a process for displaying the foci of ultrasonic waves emitted from a plurality of ultrasonic vibrators for treatment.

Background Art

[0002] Treatment apparatuses using High Intensity Focused Ultrasound (HIFU) are widely used. This treatment apparatus is called a HIFU irradiation apparatus or a HIFU irradiation system, and irradiates focused ultrasonic waves (sonicate) onto a treatment site to necrotize living tissue.

[0003] Generally, a HIFU irradiation apparatus includes a plurality of ultrasonic vibrators for treatment arranged along a concave surface. The plurality of ultrasonic vibrators are arranged such that ultrasonic waves emitted from each of them are irradiated at a single point to form a focus. During treatment, the position of the focus is adjusted to the treatment site and ultrasonic waves are irradiated. For confirmation of the irradiation position, an ultrasonic diagnostic apparatus that represents the focus on an ultrasonic image is used.

[0004] Patent Document 1 below describes an ultrasonic treatment apparatus that observes the position of a focus using an ultrasonic diagnostic apparatus that displays a B-mode image (a tomographic image based on ultrasonic echo intensity). In this apparatus, weak-level ultrasonic waves that do not affect the tissue are emitted from the ultrasonic vibrators for treatment, and a tomographic image is displayed by transmitting and receiving ultrasonic waves using an ultrasonic imaging probe. Since the acoustic characteristics of the patient's tissue change according to the temperature change of the tissue, the position of the focus is indicated by the intensity of the brightness in the tomographic image. Also, as shown in Non-Patent Document 1, since displacement occurs in the patient's tissue due to the irradiation of ultrasonic waves, the position of the focus is indicated by the change in brightness in the tomographic image.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] [Non-Patent Document 1] Tissue hardness measurement using ARFI (Internet)<https: / / www.innervision.co.jp / sp / ad / suite / siemens / technical_notes / 140368> [Overview of the project] [Problems that the invention aims to solve]

[0007] In treatment using powerful focused ultrasound, if there are areas in the patient's tissue with different acoustic properties than the surrounding area, the ultrasound emitted from the therapeutic ultrasound transducer will be refracted. This can cause the actual focal point to shift from the focal point expected under uniform acoustic conditions, making it difficult to align the therapeutic ultrasound focal point with the treatment site. Therefore, a technology that appropriately displays the focal point of the therapeutic ultrasound is desired.

[0008] The objective of this invention is to appropriately display the focal point of therapeutic ultrasound. [Means for solving the problem]

[0009] The HIFU irradiation device according to the present invention comprises a therapeutic ultrasonic transducer, an ultrasonic probe, and a control unit that controls the ultrasonic transducer and the ultrasonic probe, wherein the control unit transmits imaging ultrasound to the ultrasonic probe. The transmitted beam is scanned against biological tissue. Let, The aforementioned A first image generation process that generates first ultrasound image data based on first reflected ultrasound reflected by biological tissue and received by the ultrasound probe, After the first image generation process, An ultrasonic irradiation process in which ultrasonic waves are irradiated onto the ultrasonic transducer, and after the ultrasonic waves have been irradiated, imaging ultrasonic waves are directed onto the ultrasonic probe. The transmitted beam is scanned against the biological tissue.The process includes: a second image generation process that generates a second ultrasound image data based on the second reflected ultrasound reflected by the biological tissue and received by the ultrasound probe; a correlation calculation process that calculates the degree of similarity distribution between the image shown by the first ultrasound image data and the image shown by the second ultrasound image data based on a correlation calculation between the first ultrasound image data and the second ultrasound image data; and a display process that displays the degree of similarity distribution. The correlation calculation process includes a process for determining the degree of approximation distribution based on the correlation calculation performed for each direction of the transmission beam, wherein the correlation calculation is performed for each pixel in each direction of the transmission beam, and the degree of approximation distribution is the distribution of the absolute values ​​of the cross-correlation between the first ultrasonic image data and the second ultrasonic image data. It is characterized by the following:

[0010] In one embodiment, the correlation calculation process is performed as follows: The phase This process includes determining the displacement distribution of the biological tissue based on the calculations performed. The displacement distribution is the distribution of the phase angle of the cross-correlation value between the first ultrasonic image data and the second ultrasonic image data. The display process includes the process of displaying the displacement distribution.

[0011] Furthermore, the present invention comprises a therapeutic ultrasonic transducer, an ultrasonic probe, and a control unit that controls the ultrasonic transducer and the ultrasonic probe, wherein the control unit performs a first image generation process in which the ultrasonic probe scans a transmission beam of imaging ultrasound against biological tissue, reflects the ultrasound off the biological tissue, and generates first ultrasonic image data based on first reflected ultrasound received by the ultrasonic probe; an ultrasonic irradiation process in which the ultrasonic transducer is irradiated with ultrasound after the first image generation process; and after the ultrasound is irradiated, the ultrasonic probe scans a transmission beam of imaging ultrasound against the biological tissue, reflects the ultrasound off the biological tissue, and generates first ultrasonic image data based on first reflected ultrasound. The system performs a second image generation process that generates a second ultrasound image data based on a second reflected ultrasound received by an ultrasound probe, a correlation calculation process that determines the displacement distribution of the biological tissue based on a correlation calculation between the first ultrasound image data and the second ultrasound image data, and a display process that displays the displacement distribution. The correlation calculation process includes a process to determine the displacement distribution based on a correlation calculation performed for each direction of the transmission beam, and in the correlation calculation, the calculation is performed sequentially for each pixel in each direction of the transmission beam, and the displacement distribution is a distribution of the phase angle of the cross-correlation values ​​between the first ultrasound image data and the second ultrasound image data. .

[0012] In one embodiment, when the control unit scans the transmitting beam of the imaging ultrasound onto the biological tissue after the ultrasound has been irradiated and generates the second ultrasound image data, the ultrasound The position was determined theoretically. The transmit beam is scanned with respect to the focal point and its vicinity before other regions.

[0014] In one embodiment, the control unit causes the ultrasound probe to transmit imaging ultrasound, which is reflected by the biological tissue and received by the ultrasound probe, and performs a B-mode image generation process to generate B-mode image data based on the third reflected ultrasound. The display process includes the process of displaying the image shown by the B-mode image data.

[0015] In one embodiment, the control unit performs a pixel value difference image generation process to generate pixel value difference image data that shows the difference between the image shown by the first ultrasonic image data and the image shown by the second ultrasonic image data, and the display process includes a process to display the image shown by the pixel value difference image data. [Effects of the Invention]

[0016] According to the present invention, the position of the focus of therapeutic ultrasound can be appropriately displayed.

Brief Description of the Drawings

[0017] [Figure 1] It is a diagram showing the configuration of a HIFU irradiation device. [Figure 2] It is a diagram showing an image ultrasonic pulse and a test ultrasonic wave. [Figure 3] It is a diagram schematically showing the scanning range of an ultrasonic beam. [Figure 4] It is a diagram showing an example of a focus confirmation image. [Figure 5] It is a diagram showing an example of a focus confirmation image.

Embodiments for Carrying Out the Invention

[0018] Embodiments of the present invention will be described with reference to the respective drawings. The same reference numerals are given to the same components shown in the plurality of drawings to simplify the description. In FIG. 1, the configuration of a HIFU irradiation device 100 (ultrasonic treatment device) according to an embodiment of the present invention is shown. The HIFU irradiation device 100 includes a HIFU vibrator unit 10, a HIFU drive circuit 14, an ultrasonic probe 16, a transmission / reception circuit 18, an imaging calculation unit 20, a controller 22, a display device 24, and a drive device 26.

[0019] The controller 22 may be a personal computer, a tablet computer, or the like. An operation device (not shown) for a user to operate the HIFU irradiation device 100 is connected to the controller 22. The operation device may include a mouse, a touch panel integrated with the display device 24, a switch, a keyboard, and the like.

[0020] The HIFU transducer unit 10 comprises a transducer housing 12 having a concave surface 4 with an opening facing downward, and a plurality of ultrasonic transducers 28 arranged along the concave surface 4 in the transducer housing 12 and fixed to the transducer housing 12. The HIFU transducer unit 10 does not necessarily have a physical concave surface 4. In this case, the plurality of ultrasonic transducers 28 may be fixed to the transducer housing 12 so as to be arranged along a virtual concave surface 4.

[0021] The concave surface 4 of the transducer housing 12 may have a shape similar to the side surface of a cone. Here, a cone is a three-dimensional shape formed by a set of straight lines extending from a point in space to its base. The concave surface 4 of the transducer housing 12 may also have a dome-shaped bulge on the upper side. Each ultrasonic transducer 28 is fixed to the transducer housing 12 such that when each ultrasonic transducer 28 emits ultrasonic waves, the intensity of the ultrasonic waves is amplified at the focal point F below the transducer housing 12.

[0022] The HIFU drive circuit 14 generates ultrasonic waves in each ultrasonic transducer 28 of the HIFU transducer unit 10 in accordance with the control of the controller 22. The HIFU drive circuit 14 also adjusts the intensity of the ultrasonic waves generated by each ultrasonic transducer 28 in accordance with the control of the controller 22.

[0023] The ultrasonic probe 16 is positioned in the transducer housing 12 such that ultrasonic waves are transmitted and received below the transducer housing 12 and above the focal point F. In this embodiment, the ultrasonic probe 16 penetrates the top of the transducer housing 12 in the vertical direction, and the transmitting and receiving unit 2 that transmits and receives ultrasonic waves is oriented downwards.

[0024] A general ultrasonic imaging device may be used for the transmitting / receiving circuit 18 and the imaging calculation unit 20. The imaging calculation unit 20 may consist of a processor that executes a program to control the transmitting / receiving circuit 18. The transmitting / receiving circuit 18 performs the following processing in response to the control of the imaging calculation unit 20. That is, the transmitting / receiving circuit 18 causes the ultrasonic probe 16 to transmit ultrasonic waves and scans the transmitted beam (ultrasonic beam) made of the transmitted ultrasonic waves. The ultrasonic beam is scanned in an observation plane that includes the central axis 3 extending vertically from the apex of the transducer housing 12. The transmitting / receiving circuit 18 causes the ultrasonic probe 16 to receive reflected ultrasonic waves arriving from the direction to which the ultrasonic beam is directed, and acquires received signals from the ultrasonic probe 16 based on the reflected ultrasonic waves received from each direction to which the ultrasonic beam is directed. The transmitting / receiving circuit 18 performs a Hilbert transform on each received signal by quadrature detection and outputs it to the imaging calculation unit 20. The Hilbert-transformed received signal is represented by a complex number with the common-mode component signal as the real part and the quadrature component signal as the imaginary part.

[0025] The imaging calculation unit 20 generates ultrasound data based on each received signal output from the transmitting and receiving circuit 18. The ultrasound data may be B-mode image data showing a B-mode image (tomographic image) acquired for the patient's biological tissue.

[0026] The drive unit 26 moves the HIFU transducer unit 10 and the ultrasonic probe 16 in accordance with the control of the controller 22, and adjusts their positions. The drive unit 26 may also rotate the ultrasonic probe 16 around the central axis 3 and rotate the observation surface of the ultrasonic probe 16 around the central axis 3 in accordance with the control of the controller 22.

[0027] Before therapeutic ultrasound is emitted from the HIFU transducer unit 10 to the patient, the following positioning process is performed: The HIFU drive circuit 14 irradiates each ultrasound transducer 28 with test ultrasound at a lower intensity than that used for treatment (sonicate). The drive device 26 sets the rotational angle position of the ultrasound probe 16 so that the ultrasound probe 16 scans the ultrasound beam on the observation plane at a predetermined rotational angle position.

[0028] The imaging calculation unit 20 scans the ultrasound probe 16 with an ultrasound beam on the observation surface, acquires B-mode image data as ultrasound data, and outputs it to the controller 22. The controller 22 displays the B-mode image on the display device 24. The user, as the practitioner, may refer to the B-mode image displayed on the display device 24 to confirm the difference between the position (focal point) where the test ultrasound emitted from the HIFU transducer unit 10 is intensified and the position of the affected area.

[0029] The user changes the position or orientation of the ultrasound probe 16 and HIFU transducer unit 10 if the difference between the position of the focal point F and the position of the affected area is outside the acceptable range. After confirming that the position of the focal point F and the position of the affected area coincide, or that the difference between the position of the focal point F and the position of the affected area is within the acceptable range, the user performs a treatment operation on the controller 22. The controller 22 controls the HIFU drive circuit 14 in response to the user's operation. The HIFU drive circuit 14 irradiates each ultrasound transducer 28 with therapeutic ultrasound of the necessary intensity for treatment in response to the control by the controller 22. As a result, biological tissue is ablated at the focal point F, and treatment is performed.

[0030] In the HIFU irradiation device 100 according to this embodiment, positioning processing may be performed by displaying a displacement distribution image or an approximateness distribution image in addition to the B-mode image. Here, the displacement distribution image is an image that shows the distribution of displacement of biological tissue by color, intensity of color, etc., when biological tissue is displaced by irradiation with test ultrasound. The approximateness distribution image is an image that represents the distribution of the degree of similarity between the B-mode image obtained by imaging ultrasound transmitted before irradiation with test ultrasound and the B-mode image obtained by imaging ultrasound transmitted after irradiation with test ultrasound.

[0031] This section describes a focus confirmation image display process that displays a displacement distribution image or an approximateness distribution image. In this embodiment, the focus confirmation image display process may be executed in a time-division manner together with a process that sequentially generates B-mode image data over time.

[0032] The upper part of Figure 2 shows the first ultrasound pulse 40 and the second ultrasound pulse 44 transmitted from the ultrasound probe 16 when the focus confirmation image display processing is performed. The first ultrasound pulse 40 and the second ultrasound pulse 44 are imaging ultrasounds. The lower part of Figure 2 shows the test ultrasound 42 irradiated from the HIFU transducer unit 10 when the focus confirmation image display processing is performed. The horizontal axis represents time, and the vertical axis represents amplitude.

[0033] This section describes the case where the ultrasonic beam is sector-scanned in the ultrasonic probe 16. Here, sector scanning refers to scanning in which the ultrasonic beam extending from a certain virtual reference point is oscillated around the reference point. The direction of the ultrasonic beam is expressed as the azimuth angle as viewed from the reference point.

[0034] The ultrasound probe 16 transmits a first ultrasound pulse 40 in each direction of the ultrasound beam scanning the biological tissue. That is, the first ultrasound pulse 40 is transmitted in each of the multiple directions to which the ultrasound beam is directed. For each direction, after the first ultrasound pulse 40 is transmitted, the first reflected ultrasound generated by the reflection of the first ultrasound pulse 40 within the biological tissue is received by the ultrasound probe 16. A predetermined time T1 has elapsed since the last transmission of the first ultrasound pulse 40, and the HIFU transducer unit 10 emits a test ultrasound 42. Time T1 is determined so that it is sufficient for the last first reflected ultrasound to be received by the ultrasound probe 16. The test ultrasound 42 is an ultrasound with a lower intensity than the therapeutic ultrasound. Here, lower intensity means that the amplitude is small under the condition that the number of oscillations on the time axis is the same. Also, under the condition that the amplitude is the same, it means that the number of oscillations on the time axis is small.

[0035] When a predetermined reverberation waiting period T2 has elapsed since the test ultrasound 42 was irradiated, the ultrasound probe 16 transmits a second ultrasound pulse 44 in each of the multiple directions from which the first ultrasound pulse 40 was transmitted. However, as will be described later, the order in which the second ultrasound pulse 44 is transmitted may differ from the order in which the first ultrasound pulse 40 is transmitted. Here, the reverberation waiting period T2 refers to the time required for the test ultrasound 42 to undergo multiple reflections within the biological tissue and be sufficiently attenuated after it has been irradiated onto the biological tissue. For each direction, after the second ultrasound pulse 44 is transmitted, the second reflected ultrasound generated by the reflection of the second ultrasound pulse 44 within the biological tissue is received by the ultrasound probe 16.

[0036] As shown in Figure 2, the ultrasonic transmission and reception sequence involves the transmission of a first ultrasonic pulse 40 and the reception of a first reflected ultrasonic pulse in each direction of the ultrasonic beam, followed by the irradiation of a test ultrasonic pulse 42. After the irradiation of the test ultrasonic pulse 42, the transmission of a second ultrasonic pulse 44 and the reception of a second reflected ultrasonic pulse are performed in each direction of the ultrasonic beam.

[0037] The processing performed by the HIFU irradiation device 100 in the ultrasonic transmission and reception sequence will be described in detail. The transmission and reception circuit 18 outputs a first received signal based on the first reflected ultrasonic wave for each direction of the scanned ultrasonic beam to the imaging calculation unit 20. The imaging calculation unit 20 generates first ultrasonic image data based on the first received signal obtained for each direction of the scanned ultrasonic beam. The transmission and reception circuit 18 also outputs a second received signal based on the second reflected ultrasonic wave for each direction of the scanned ultrasonic beam to the imaging calculation unit 20. The imaging calculation unit 20 generates second ultrasonic image data based on the second received signal obtained for each direction of the scanned ultrasonic beam.

[0038] In the ultrasound images shown in the first and second ultrasound image data, multiple pixels are arranged in a single row in the depth direction for a given azimuth angle φj of an ultrasound beam. Here, the azimuth angle φj is expressed as an angle with the depth direction set to 0°, for example, and ultrasound is transmitted and received for n ultrasound beams j=1 to n within the scanning range of the ultrasound beam. In this case, the ultrasound image has multiple pixels arranged in a single row for each azimuth angle φ1 to φn, and the ultrasound image is such that each pixel is arranged in polar coordinates. For display on the display device 24, the ultrasound image may be converted so that each pixel is arranged in orthogonal coordinates. Each pixel is represented by a complex number pixel value. The real part of the pixel value is the value of the in-phase component signal included in the received signal, and the imaginary part of the pixel value is the value of the orthogonal component signal included in the received signal.

[0039] The sequence for changing the direction of the ultrasonic beam of the second ultrasonic pulse 44 may be determined as follows. Figure 3 schematically shows the scanning range of the ultrasonic beam. Ultrasonic beam scanning ends A and B indicate the ends of the B-mode scanning range in which the ultrasonic beam is scanned when generating B-mode image data. In the focus confirmation image display process, the ultrasonic beam may be scanned in a range narrower than the B-mode scanning range.

[0040] The azimuth angle of the ultrasonic beam of the first ultrasonic pulse 40 changes in the order of φ1, φ2...φ5, and the ultrasonic beam is scanned from left to right in Figure 3. In this case, the ultrasonic beam with an azimuth angle of φ3 passes through the focal point F. The position of this focal point F can be theoretically determined by the positions where the multiple ultrasonic transducers 28 are arranged, the delay time of the ultrasonic waves emitted from each ultrasonic transducer 28, etc.

[0041] The ultrasonic beam of the second ultrasonic pulse 44 may be scanned such that its azimuth angle changes in the order of φ3, φ4, φ2, φ5, φ1. More generally, when the azimuth angle of the ultrasonic beam of the first ultrasonic pulse 40 changes in the order of φ1, φ2, φ3, etc., and the ultrasonic beam with an azimuth angle of φm is closest to or passing through the focal point F, the ultrasonic beam of the second ultrasonic pulse 44 may be scanned such that its azimuth angle becomes φm, φm+1, φm-1, φm+2, φm-2, etc. Alternatively, the ultrasonic beam of the second ultrasonic pulse 44 may be scanned such that its azimuth angle becomes φm, φm-1, φm+1, φm-2, φm+2, etc. That is, the ultrasonic beam of the second ultrasonic pulse 44 may be scanned so that the scanning range is sequentially expanded to the left and right, centering on the azimuth angle φm of the ultrasonic beam that is closest to or passing through the focal point F. Thus, with respect to the ultrasound beam of the second ultrasound pulse 44, by scanning the focal point F and its vicinity before other regions, the changes in biological tissue caused by the test ultrasound are reflected in the second reflected ultrasound before the changes in biological tissue caused by the test ultrasound disappear. Furthermore, even when the intensity of the test ultrasound is relatively weak, the changes in biological tissue caused by the test ultrasound are reflected in the second reflected ultrasound.

[0042] The imaging calculation unit 20 performs correlation calculation processing on the first ultrasound image data and the second ultrasound image data to obtain cross-correlation values ​​at each position (z, φj) in the biological tissue. Here, j is an integer from 1 to n, and z represents the depth in the direction of the ultrasound beam with an azimuth angle of φj.

[0043] For a given azimuth angle φj within the scanning range of the ultrasound beam, let T(i,j) be the pixel value of each pixel arranged in a single row in the first ultrasound image, and let I(i,j) be the pixel value of each pixel arranged in a single row in the second ultrasound image. The cross-correlation value θc(z,φj) at depth z and azimuth angle φj is expressed as shown in (Equation 1). Here, the pixel value T(i,j) is the pixel value of the first ultrasound image at the depth z+i·Δ position in the direction of azimuth angle φj. The pixel value I(i,j) is the pixel value of the second ultrasound image at the depth z+i·Δ position in the direction of azimuth angle φj. Δ is the interval at which pixel values ​​are acquired in the depth direction.

[0044]

number

[0045] The asterisk (*) above the pixel value T(i,j) indicates that it is the complex conjugate of the pixel value T(i,j). M represents the depth range over which the correlation operation is performed.

[0046] The phase angle (complex angle) of the cross-correlation value θc(z,φj) represents the displacement in the depth direction at position (z,φj). However, the displacement is a value normalized by the wavelength of the ultrasonic pulse transmitted from the ultrasonic probe 16. The absolute value of the cross-correlation value θc(z,φj) indicates the degree of approximation of the image at position (z,φj) and its vicinity. Therefore, the absolute value of the cross-correlation value θc(z,φj) is hereinafter referred to as the degree of approximation. The degree of approximation is normalized to a value between 0 and 1.

[0047] The imaging calculation unit 20 generates displacement distribution image data in the region of interest by determining the phase angle θc(z,φj) for each pixel included in the region of interest set in the biological tissue, based on (Equation 1). The displacement distribution image data shows the displacement distribution image in the region of interest.

[0048] The imaging calculation unit 20 generates approximate degree distribution image data in the region of interest by determining the absolute value of θc(z,φj) as the degree of approximation for each pixel included in the region of interest set in the biological tissue, based on (Equation 1). The approximate degree distribution image data shows the approximate degree distribution image in the region of interest.

[0049] The imaging calculation unit 20 may generate approximate distribution image data by performing pattern matching on the first ultrasound image data and the second ultrasound image data. Here, pattern matching is a process that determines the degree of similarity between the first ultrasound image data and the second ultrasound image data, and the positional difference of each image represented by the first ultrasound image data and the second ultrasound image data. An example of pattern matching is shown in the above-mentioned Patent Document 2.

[0050] The above example shows an ultrasonic beam being sector-scanned. The ultrasonic beam may be scanned in other ways, such as convex scanning or linear scanning. Convex scanning refers to scanning in which an ultrasonic beam, which is almost perpendicular to the curved transmitting and receiving surface of the transmitting and receiving unit 2 of the ultrasonic probe 16, is moved along the transmitting and receiving surface. Linear scanning refers to scanning in which the ultrasonic beam is moved parallel to each other in the same direction.

[0051] When scanning an ultrasonic beam in a manner other than sector scanning, another variable is used to specify the position or direction of each of the n ultrasonic beams within the scanning range, instead of the azimuth angle φj described above. For example, when linear scanning is performed along the x-axis direction corresponding to the lateral direction of the ultrasonic image, the x-axis coordinate value xj is used instead of φj.

[0052] When test ultrasound is irradiated onto biological tissue, displacement occurs in the tissue at the focus of the test ultrasound. As a result, pixels with different pixel values ​​from the surrounding areas appear in the displacement distribution image. These pixels with different pixel values ​​represent the focus. Therefore, in the HIFU irradiation device 100 according to this embodiment, the displacement distribution image is displayed on the display device 24 along with the B-mode image during the positioning process. The user may perform an operation to align the position of the focus with the position of the affected area while referring to the B-mode image and the displacement distribution image.

[0053] Furthermore, when test ultrasound is irradiated onto biological tissue, the reflection characteristics of the ultrasound change at and near the focus of the test ultrasound. As a result, differences occur between the first ultrasound image and the second ultrasound image at and near the focus. Consequently, pixels with different pixel values ​​from the surrounding pixels appear in the approximateness distribution image. Pixels with different pixel values ​​from the surrounding pixels represent the focus. Therefore, in the HIFU irradiation device 100 according to this embodiment, the approximateness distribution image is displayed on the display device 24 along with the B-mode image during the positioning process. In this case, the user may perform an operation to align the position of the focus with the position of the affected area while referring to the B-mode image and the approximateness distribution image.

[0054] The image display in the positioning process will be explained in detail. The imaging calculation unit 20 outputs displacement distribution image data and approximateness distribution image data to the controller 22. The controller 22 displays a focus confirmation image on the display device 24, which is a composite of a real-time B-mode image based on B-mode image data generated sequentially over time, a displacement distribution image, and an approximateness distribution image. The user refers to the focus confirmation image displayed on the display device 24 to confirm the difference between the focus of the test ultrasound emitted from the HIFU transducer unit 10 and the position of the affected area.

[0055] Figure 4 shows an example of a focus confirmation image 50. The focus confirmation image 50 consists of a displacement distribution / B-mode image 52, a motion-removed displacement distribution / B-mode image 54, a pixel value difference image 56, and an approximateness distribution image 58. Each image was obtained by convex scanning of the ultrasonic beam.

[0056] The displacement distribution / B-mode image 52 shown in the upper left of Figure 4 is displayed based on the displacement distribution image data and the B-mode image data. The displacement distribution / B-mode image 52 is an image created by overlaying the displacement distribution image 52-2 onto the B-mode image 52-1.

[0057] The imaging calculation unit 20 generates displacement distribution / B-mode image data sequentially over time based on the B-mode image data and displacement distribution image data that are generated sequentially over time, and outputs it to the controller 22. The controller 22 displays the displacement distribution / B-mode image 52, which is obtained by superimposing the displacement distribution image 52-2 onto the real-time B-mode image 52-1, on the display device 24.

[0058] In the example shown in Figure 4, the region of interest for which displacement distribution image data is required is set to be narrower than the region for which B-mode image data is required. In this embodiment, the displacement distribution image is colored more intensely as the displacement in the depth direction increases. As a result, the location where the focus occurs is colored more intensely.

[0059] The motion-removed displacement distribution / B-mode image 54 shown in the upper right of Figure 4 is obtained by subtracting the motion component based on the movement of biological tissue from the displacement distribution shown in the displacement distribution / B-mode image. The motion component may be obtained from B-mode image data generated in real time. The imaging calculation unit 20 determines the positional difference between the B-mode image shown by the B-mode image data generated earlier and the B-mode image data shown later as the motion component for each pixel. The imaging calculation unit 20 generates motion-removed displacement image data by subtracting the motion component from each pixel value included in the displacement distribution image data.

[0060] The imaging calculation unit 20 generates motion-removed displacement distribution / B-mode image data sequentially over time based on the B-mode image data and motion-removed displacement distribution image data that are generated sequentially over time, and outputs it to the controller 22. The controller 22 displays the motion-removed displacement distribution / B-mode image 52, which is created by superimposing the motion-removed displacement distribution image 54-2 onto the real-time B-mode image 54-1, on the display device 24.

[0061] The pixel value difference image 56 shown in the lower left of Figure 4 is an image in which each pixel value is the absolute value obtained by subtracting the absolute value of each pixel value shown in the first ultrasound image data from the absolute value of each pixel value shown in the second ultrasound image data. The absolute value of each pixel value is the absolute value of a complex number. For example, the imaging calculation unit 20 generates pixel value difference image data based on the first ultrasound image data and the second ultrasound image data and outputs it to the controller 22. The controller 22 displays the pixel value difference image 56 on the display device 24.

[0062] The approximateness distribution image 58 shown in the lower right of Figure 4 is displayed based on the approximateness distribution image data. The imaging calculation unit 20 outputs the approximateness distribution image data to the controller 22. The controller 22 displays the approximateness distribution image 58 on the display device 24. The approximateness distribution image 58 is an image in which pixels with a smaller degree of approximateness are given darker colors. Pixels with an approximateness of 1 (maximum value) are given white, and pixels with a smaller degree of approximateness are given darker colors.

[0063] In the example shown in the lower right of Figure 4, the focal point and its vicinity are highlighted with darker colors. This is because the degree of similarity between the first ultrasound image before the test ultrasound is applied and the second ultrasound image after the test ultrasound is applied decreases at and near the focal point.

[0064] Figure 5 shows a focus confirmation image 50Z, which is an enlarged view of the area around the focal point of the focus confirmation image 50 shown in Figure 4. During the positioning process, the focus confirmation image 50Z shown in Figure 5 may be displayed on the display device 24 instead of the focus confirmation image 50 shown in Figure 4.

[0065] The controller 22 may determine the focal point information of the ultrasound emitted from the HIFU transducer unit 10 based on displacement distribution image data or approximation distribution image data, and display it on the display device 24. The focal point information may be the position coordinates of the focal point or information that identifies the range in which the focal point exists on a coordinate plane.

[0066] The above shows a focus confirmation image 50 composed of a displacement distribution / B-mode image 52, a motion-removed displacement distribution / B-mode image 54, a pixel value difference image 56, and an approximateness distribution image 58. The focus confirmation image 50 does not have to include all of the displacement distribution / B-mode image 52, the motion-removed displacement distribution / B-mode image 54, the pixel value difference image 56, and the approximateness distribution image 58; it may include any one of these images.

[0067] Alternatively, an approximateness distribution / B-mode image may be displayed in which the approximateness distribution image 58 is superimposed on the B-mode image. In this case, the imaging calculation unit 20 generates approximateness distribution / B-mode image data sequentially over time based on the B-mode image data and approximateness distribution image data that are generated sequentially over time, and outputs it to the controller 22. The controller 22 causes the display device 24 to display the approximateness distribution / B-mode image, which is a real-time B-mode image with the approximateness distribution image 58 superimposed on it.

[0068] The above describes an embodiment in which displacement distribution image data and approximateness distribution data are generated based on first and second ultrasound image data acquired before and after irradiation with test ultrasound, and a focus confirmation image (50, 50Z) is displayed based on the displacement distribution image data and approximateness distribution data. The focus confirmation image may be displayed after treatment. In this case, the test ultrasound may be replaced with therapeutic ultrasound. That is, first and second ultrasound image data may be acquired before and after irradiation with therapeutic ultrasound, and a process may be performed to generate displacement distribution image data and approximateness distribution data based on the first and second ultrasound image data. A focus confirmation image (50, 50Z) may be displayed based on the displacement distribution image data and approximateness distribution data acquired in this manner.

[0069] As described above, the HIFU irradiation device 100 is an ultrasonic treatment device comprising a HIFU transducer unit 10 including a therapeutic ultrasonic transducer 28, an ultrasonic probe 16, and a control unit 30 that controls the ultrasonic transducer 28 and the ultrasonic probe 16. The control unit 30 consists of a HIFU drive circuit 14, a transmit / receive circuit 18, an imaging calculation unit 20, and a controller 22.

[0070] The control unit 30 performs a first image generation process, an ultrasound irradiation process, a second image generation process, a correlation calculation process, and a display process. The first image generation process involves causing the ultrasound probe 16 to transmit imaging ultrasound, which is reflected by biological tissue, and generating a first ultrasound image data based on the first reflected ultrasound received by the ultrasound probe 16. The ultrasound irradiation process involves irradiating the ultrasound transducer 28 with ultrasound. This ultrasound is either test ultrasound or therapeutic ultrasound.

[0071] The second image generation process involves, after ultrasound irradiation, causing the ultrasound probe 16 to transmit imaging ultrasound, which is reflected by biological tissue and received by the ultrasound probe 16, to generate a second ultrasound image data based on the second reflected ultrasound. The correlation calculation process involves calculating the degree of similarity between the image shown by the first ultrasound image data and the image shown by the second ultrasound image data based on the correlation calculation between the first ultrasound image data and the second ultrasound image data. The display process involves displaying the degree of similarity distribution.

[0072] The correlation calculation process may include a process for determining the displacement distribution of biological tissue based on a correlation calculation between the first ultrasound image data and the second ultrasound image data. In this case, the display process may include a process for displaying the displacement distribution. The correlation calculation process may include a process for determining the displacement distribution based on correlation calculations performed for each direction of the transmitted beam. Furthermore, the correlation calculation process may include a process for determining the degree of approximation based on correlation calculations performed for each direction of the transmitted beam.

[0073] When the control unit 30 scans the transmitted beam of imaging ultrasound onto biological tissue after ultrasound irradiation to generate a second ultrasound image data, it may scan the ultrasound focal point and the region near the focal point before other regions.

[0074] The control unit 30 may perform a B-mode image generation process that causes the ultrasound probe 16 to transmit imaging ultrasound, which is reflected by biological tissue and received by the ultrasound probe 16, generating B-mode image data based on the third reflected ultrasound. In this case, the display process may include a process for displaying the B-mode image.

[0075] The control unit 30 may perform a pixel value difference image generation process to generate pixel value difference image data that shows the difference between the first ultrasound image and the second ultrasound image. In this case, the display process may include a process to display the pixel value difference image. [Explanation of Symbols]

[0076] 2 Transceiver unit, 3 Central axis, 4 Concave surface, 10 HIFU transducer unit, 14 HIFU drive circuit, 16 Ultrasonic probe, 18 Transceiver circuit, 20 Imaging calculation unit, 22 Controller, 24 Display device, 26 Drive device, 28 Ultrasonic transducer, 30 Control unit, 40 Imaging ultrasonic pulse, 42 Test ultrasound, 50, 50Z focus confirmation image, 52 Displacement distribution / B-mode image, 52-1 B-mode image, 52-2 Displacement distribution image, 54 Motion-removed displacement distribution / B-mode image, 54-1 B-mode image, 54-2 Motion-removed displacement distribution, 56 Pixel value difference image, 58 Approximation distribution image.

Claims

1. A therapeutic ultrasonic transducer, Ultrasound probe and The system comprises a control unit for controlling the ultrasonic transducer and the ultrasonic probe, The control unit, A first image generation process involves scanning a transmission beam using imaging ultrasound with the ultrasound probe over biological tissue, generating a first ultrasound image data based on the first reflected ultrasound reflected by the biological tissue and received by the ultrasound probe; After the first image generation process, an ultrasonic irradiation process is performed in which ultrasonic waves are irradiated onto the ultrasonic transducer, After the ultrasound is irradiated, the ultrasound probe is made to scan the biological tissue with a transmission beam of imaging ultrasound, and a second image generation process is performed to generate a second ultrasound image data based on the second reflected ultrasound that is reflected by the biological tissue and received by the ultrasound probe. A correlation calculation process to determine the degree of similarity distribution between the image shown by the first ultrasound image data and the image shown by the second ultrasound image data, based on the correlation calculation between the first ultrasound image data and the second ultrasound image data, The display process for displaying the aforementioned approximation distribution is executed, The correlation calculation process is performed as follows: The process includes determining the degree of approximation distribution based on correlation calculations performed for each direction of the transmission beam, wherein the correlation calculation is performed pixel by pixel for each direction of the transmission beam. The ultrasound treatment device is characterized in that the degree of approximation distribution is the distribution of the absolute values ​​of the cross-correlation between the first ultrasound image data and the second ultrasound image data.

2. An ultrasonic therapy device according to claim 1, The correlation calculation process is performed as follows: The process includes determining the displacement distribution of the biological tissue based on the correlation calculation, The displacement distribution is the distribution of the phase angle of the cross-correlation value between the first ultrasonic image data and the second ultrasonic image data. The aforementioned display process is: An ultrasonic treatment device characterized by including a process for displaying the aforementioned displacement distribution.

3. A therapeutic ultrasonic transducer, Ultrasound probe and The system comprises a control unit for controlling the ultrasonic transducer and the ultrasonic probe, The control unit, A first image generation process involves scanning a transmission beam using imaging ultrasound with the ultrasound probe over biological tissue, generating a first ultrasound image data based on the first reflected ultrasound reflected by the biological tissue and received by the ultrasound probe; After the first image generation process, an ultrasonic irradiation process is performed in which ultrasonic waves are irradiated onto the ultrasonic transducer, After the ultrasound is irradiated, the ultrasound probe is made to scan the biological tissue with a transmission beam of imaging ultrasound, and a second image generation process is performed to generate a second ultrasound image data based on the second reflected ultrasound that is reflected by the biological tissue and received by the ultrasound probe. A correlation calculation process is performed to determine the displacement distribution of the biological tissue based on the correlation calculation between the first ultrasound image data and the second ultrasound image data. The following is performed: a display process that shows the displacement distribution, The correlation calculation process is performed as follows: The process includes determining the displacement distribution based on correlation calculations performed for each direction of the transmission beam, wherein the correlation calculations are performed sequentially for each pixel in each direction of the transmission beam. The ultrasonic therapy device is characterized in that the displacement distribution is the distribution of the phase angle of the cross-correlation value between the first ultrasonic image data and the second ultrasonic image data.

4. An ultrasonic therapy device according to any one of claims 1 to 3, The control unit, An ultrasound therapy device characterized in that, when scanning the transmitting beam of the imaging ultrasound onto the biological tissue after the ultrasound has been irradiated, the transmitting beam is scanned over the theoretically determined focal point and the vicinity of the focal point before other regions.

5. An ultrasonic therapy device according to any one of claims 1 to 3, The control unit, The ultrasound probe is made to transmit imaging ultrasound, and a B-mode image generation process is performed to generate B-mode image data based on the third reflected ultrasound that is reflected by the biological tissue and received by the ultrasound probe. The aforementioned display process is: An ultrasonic treatment device characterized by including a process for displaying the image shown in the B-mode image data.

6. An ultrasonic therapy device according to any one of claims 1 to 3, The control unit, A pixel value difference image generation process is performed to generate pixel value difference image data that shows the difference between the image shown by the first ultrasound image data and the image shown by the second ultrasound image data. The aforementioned display process is: An ultrasonic treatment device characterized by including a process for displaying the image shown by the aforementioned pixel value difference image data.

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