Ultrasound diagnostic equipment

Abstract

To simultaneously obtain good time responsiveness and a good space compound effect.SOLUTION: A first beam scanning plane FA and a second beam scanning plane FB are formed alternately. For formation of the first beam scanning plane FA, transmission / reception control is performed so that the beam deflection angle increases continuously toward the negative side from a first end to a second end in the electronic scanning direction. For formation of the second beam scanning plane FB, transmission / reception control is performed so that the beam deflection angle increases continuously toward the positive side from the second end to the first end in the electronic scanning direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to ultrasound diagnostic devices, and more particularly to spatial compounding techniques. [Background technology]

[0002] An ultrasound diagnostic device is a device that forms and displays ultrasound images by transmitting ultrasound waves into a subject and receiving reflected waves from the subject. Ultrasound images contain random acoustic noise (also called speckle). Spatial compounding is known as a technique for reducing such noise.

[0003] In the spatial compounding method, for example, a first beam scan is performed while maintaining a beam deflection angle of -φ degrees to acquire a first frame of data (hereinafter, "frame data" will be simply referred to as a "frame"). Next, a second beam scan is performed while maintaining a beam deflection angle of 0 degrees to acquire a second frame. Next, a third beam scan is performed while maintaining a beam deflection angle of +φ degrees to acquire a third frame. This sequence is performed cyclically, thereby acquiring a frame sequence. The frame sequence consists of a first frame, a second frame, a third frame, a first frame, a second frame, a third frame, ... arranged in chronological order. At each synthesis timing, three consecutive frames on the time axis are synthesized, thereby generating a synthesized frame.

[0004] The composite frame includes multiple parts, namely, a triple overlap part, a double overlap part, and a non-overlap part. Generally, the triple overlap part and the double overlap part are the display targets. In the spatial compounding method, it is known that the larger the maximum beam deflection angle difference (2φ in the above example), the greater the compounding effect. In the above double overlap part, the beam deflection angle difference is small, so the spatial compounding effect cannot be fully obtained.

[0005] In conventional spatial compounding, the number of composite frames (or the number of beam deflection angles) is an odd number, such as 3, 5, or 7. Although the spatial compounding does not appear to cause a decrease in frame rate, the temporal responsiveness decreases as the number of composite frames increases.

[0006] Patent Documents 1 and 2 disclose conventional spatial compounding methods. Patent Document 3 discloses a 1.25D probe. None of these documents discloses continuously changing the beam deflection angle during beam scanning from one end to the other in the electronic scanning direction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4860945 [Patent Document 2] U.S. Patent No. 6,416,477 [Patent Document 3] Patent No. 5921133 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present disclosure is to realize a spatial compounding method that can expand the polymerization region even with a small number of synthesis frames, or to simultaneously obtain good temporal response and good spatial compounding effects. [Means for solving the problem]

[0009] An ultrasonic diagnostic apparatus according to the present disclosure includes a transducer element array having a plurality of transducer elements aligned in an electronic scanning direction, a control unit that controls an operation of the transducer element array so that a plurality of beam scanning planes including a first beam scanning plane and a second beam scanning plane are sequentially formed, and a synthesis unit that synthesizes a plurality of frame data obtained by forming the plurality of beam scanning planes, wherein the first beam scanning plane is constituted by a plurality of first beams aligned in the electronic scanning direction, and the beam deflection angles of the plurality of first beams increase continuously toward the negative side from one end to the other end in the electronic scanning direction, and the second beam scanning plane is constituted by a plurality of second beams aligned in the electronic scanning direction, and the beam deflection angles of the plurality of second beams increase continuously toward the positive side from the other end to the one end. fart Continuous to Increased Crate , the vibration element array has a plurality of vibration element rows lined up in a minor axis direction perpendicular to the major axis direction which is the electronic scanning direction, and each of the vibration element rows is composed of a plurality of vibration elements lined up in the electronic scanning direction, the plurality of beam scanning planes include the first beam scanning plane, the second beam scanning plane, the third beam scanning plane, and a fourth beam scanning plane, the third beam scanning plane is composed of a plurality of third beams lined up in the electronic scanning direction, and a beam deflection angle of the plurality of third beams increases continuously to the negative side from the one end to the other end, the fourth beam scanning plane is composed of a plurality of fourth beams lined up in the electronic scanning direction, and a beam deflection angle of the plurality of fourth beams increases continuously to the positive side from the other end to the one end, when forming the first beam scanning plane and the second beam scanning plane, a first aperture size is set in the minor axis direction in the vibration element array, and when forming the third beam scanning plane and the fourth beam scanning plane, a second aperture size is set in the minor axis direction in the vibration element array, and the first aperture size and the second aperture size are different from each other. It is characterized by: [Effects of the Invention]

[0010] The ultrasound diagnostic device according to the present disclosure can expand the overlap region even with a small number of synthesis frames when implementing spatial compounding, or can simultaneously achieve good temporal response and good spatial compounding effects. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an example of the configuration of an ultrasound diagnostic apparatus according to an embodiment. [Figure 2] FIG. 3 is a diagram showing beam scanning according to the first embodiment. [Figure 3] FIG. 1 is a diagram illustrating a spatial compounding technique according to a first embodiment. [Figure 4] FIG. 4 is a diagram showing a beam deflection angle function according to the first embodiment. [Figure 5] FIG. 4 is a diagram showing a beam deflection angle difference function according to the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating the characteristics of a band-pass filter. [Figure 7]FIG. 10 is a diagram showing a change in cutoff frequency according to a change in beam deflection angle. [Figure 8] FIG. 1 is a diagram illustrating a first comparative example. [Figure 9] FIG. 10 is a diagram illustrating a second comparative example. [Figure 10] FIG. 10 is a diagram illustrating a first modified example of the first embodiment. [Figure 11] FIG. 10 is a diagram illustrating a second modified example of the first embodiment. [Figure 12] FIG. 10 is a diagram illustrating a spatial compounding technique according to a second embodiment. [Figure 13] FIG. 10 is a diagram showing a beam deflection angle function according to the second embodiment. [Figure 14] FIG. 10 is a diagram showing a beam deflection angle difference function according to the second embodiment. [Figure 15] FIG. 10 is a diagram illustrating a modified example of the second embodiment. [Figure 16] FIG. 10 is a diagram showing a 1.25D probe according to a third embodiment. [Figure 17] FIG. 10 is a diagram illustrating a spatial compounding technique according to a third embodiment. [Figure 18] FIG. 10 is a diagram illustrating a weighting function. [Figure 19] FIG. 10 is a diagram illustrating a modified example of the third embodiment. [Figure 20] FIG. 10 is a diagram illustrating convex scanning. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment will be described with reference to the drawings.

[0013] (1) Overview of the embodiment An ultrasound diagnostic apparatus according to an embodiment includes a transducer array, a controller, and a combiner. The transducer array includes a plurality of transducer elements aligned in an electronic scanning direction. The controller controls the operation of the transducer array so that a plurality of beam scanning planes, including a first beam scanning plane and a second beam scanning plane, are sequentially formed. The combiner combines a plurality of frame data obtained by forming the plurality of beam scanning planes. The first beam scanning plane is composed of a plurality of first beams aligned in the electronic scanning direction. From one end to the other end in the electronic scanning direction, the beam deflection angles of the plurality of first beams continuously increase toward the negative side. The second beam scanning plane is composed of a plurality of second beams aligned in the electronic scanning direction. From the other end to the one end, the beam deflection angles of the plurality of second beams continuously increase to the positive side.

[0014] The first beam scanning surface has a first divergent shape with a deep portion that widens in the negative electronic scanning direction, and the second beam scanning surface has a second divergent shape with a deep portion that widens in the positive electronic scanning direction. Therefore, even with a small number of synthesis frames, the overlapping area (overlap area) between the first beam scanning surface and the second beam scanning surface can be expanded in the electronic scanning direction. Therefore, good temporal response and good spatial compounding effect can be obtained at the same time.

[0015] In an embodiment, the first flared shape is trapezoidal, with a bottom edge extending in the negative electronic scan direction. The second flared shape is also trapezoidal, with a bottom edge extending in the positive electronic scan direction. The bottom edges of the first flared shape and the second flared shape are each straight or curved (arc). Similarly, the top edges of the first flared shape and No. 2 The top sides of the flared shapes are also straight lines or curves (arcs). In real space, the two bottom sides do not coincide, but the two top sides do. When the first flared shape is mirror-flipped, the mirror-flipped first flared shape coincides with the second flared shape. In other words, the first flared shape and the second flared shape have an inversion-symmetric relationship.

[0016] The continuous increase in the beam deflection angle includes a stepwise increase in the beam deflection angle. In the first beam scanning plane, the difference in beam deflection angle between adjacent beams gradually increases from one end to the other end in the electronic scanning direction. In the second beam scanning plane, the difference in beam deflection angle between adjacent beams gradually increases from the other end to one end in the electronic scanning direction.

[0017] The control unit indirectly controls the operation of the transducer array by controlling the operation of the transmitter and receiver. Each of the beams is an acoustic line or a scanning line. More specifically, each of the beams is a transmitting / receiving beam when parallel reception is not performed, and is a transmitting beam when parallel reception is performed. When parallel reception is performed, multiple receiving beams that spread radially according to a beam deflection angle function may be simultaneously formed.

[0018] In an embodiment, the control unit sets deflection angles of a plurality of first beams according to a first beam deflection angle function, and sets deflection angles of a plurality of second beams according to a second beam deflection angle function. In a coordinate system defined by a first axis indicating a position in the electronic scanning direction and a second axis indicating the beam deflection angle, the first beam deflection angle function is represented by a first line, and the second beam deflection angle function is represented by a second line. In the coordinate system, the first line and the second line are each a straight line or a curved line. In the coordinate system, the first line and the second line are parallel to each other.

[0019] In the first beam scanning plane, the deflection angle of the first beam corresponding to one end is 0 degrees or +ζ degrees, and the deflection angle of the first beam corresponding to the other end is -α degrees (where |α|>0 or |α|>|ζ|>0). In the second beam scanning plane, the deflection angle of the second beam corresponding to the other end is 0 degrees or -ζ degrees, and the deflection angle of the second beam corresponding to one end is +α degrees.

[0020] +ζ and -ζ each function as a negative offset. By adding +ζ and -ζ, it is possible to expand the overlap area in the electronic scanning direction. If you do not require such expansion, simply use 0 instead of +ζ and -ζ.

[0021] In the embodiment, the transducer element array has a plurality of transducer element rows aligned in a minor axis direction perpendicular to the major axis direction, which is the electronic scanning direction. Each transducer element row is composed of a plurality of transducer elements aligned in the electronic scanning direction. The plurality of beam scanning planes include a first beam scanning plane, a second beam scanning plane, a third beam scanning plane, and a fourth beam scanning plane. The third beam scanning plane is composed of a plurality of third beams aligned in the electronic scanning direction. From one end to the other end in the electronic scanning direction, the beam deflection angles of the plurality of third beams continuously increase toward the negative side. The fourth beam scanning plane is composed of a plurality of fourth beams aligned in the electronic scanning direction. From the other end to the one end in the electronic scanning direction, the beam deflection angles of the plurality of fourth beams continuously increase toward the positive side. When forming the first beam scanning plane and the second beam scanning plane, a first acoustic aperture size is set in the minor axis direction in the transducer element array. When forming the third beam scanning plane and the fourth beam scanning plane, a second acoustic aperture size is set in the minor axis direction in the transducer element array. The first acoustic aperture size and the second acoustic aperture size are different from each other.

[0022] The above configuration utilizes a combination of beam deflection angle changes and switching of aperture size in the minor axis direction. For example, a 1.25D probe, a 1.5D probe, a 1.75D probe, or a 2D probe is used to implement the above configuration. The order of forming the beam scan planes can be determined arbitrarily. For example, the first beam scan plane, the second beam scan plane, the third beam scan plane, and the fourth beam scan plane are formed. Scanning plane Alternatively, a series of beam scanning planes may be formed in the order of the first beam scanning plane, the third beam scanning plane, the second beam scanning plane, and the fourth beam scanning plane. Scanning plane A series of beam scan planes may be formed in the order:

[0023] An ultrasonic diagnostic apparatus according to an embodiment includes a filter that acts on a plurality of first received signals corresponding to a plurality of first beams and a plurality of second received signals corresponding to a plurality of second beams. A control unit changes the characteristics of the filter according to the deflection angles of the plurality of first beams and the plurality of second beams. The ultrasonic propagation distance changes according to the beam deflection angle. In other words, the characteristics of the received signal change according to the beam deflection angle. Therefore, the above configuration changes the characteristics of the filter according to the change in the characteristics of the received signal.

[0024] In the embodiment, the number of the beam scan planes is an even number. For example, the number is 2 or 4. A beam scan plane set consisting of an even number of beam scan planes is formed cyclically. In the embodiment, a scan performed with the beam deflection angle fixed at 0 degrees (a conventional intermediate scan) is not required.

[0025] (2) Details of the embodiment An ultrasound diagnostic apparatus according to an embodiment is shown in Fig. 1. This ultrasound diagnostic apparatus is a medical apparatus installed in a medical institution or the like and used for ultrasound examinations of subjects. Control and processing according to each embodiment described below are performed using the configuration shown in Fig. 1.

[0026] The ultrasonic probe 10 has a transducer element array consisting of a plurality of transducer elements arranged in a line. The transducer element array forms an ultrasonic beam 12. By repeating electronic scanning of the ultrasonic beam 12, beam scan planes (two-dimensional data acquisition areas) are formed sequentially. In the embodiment, a plurality of types of beam scan planes are formed cyclically according to a spatial compounding method. In some examples described later, a first beam scan plane 16 and a second beam scan plane 18 are formed alternately. In such cases, the number of synthesis frames is two.

[0027] The transmitter 22 is an electronic circuit that functions as a transmit beam former. During transmission, the transmitter 22 supplies multiple transmit signals in parallel to the transducer array. This causes ultrasound waves to be emitted into the living body. In other words, a transmit beam is formed.

[0028] The receiver 20 is an electronic circuit that functions as a receive beamformer. During reception, when reflected waves from within the living body are received by the transducer element array, multiple receive signals are output in parallel from the transducer element array to the receiver 20. The receiver 20 applies phasing addition to the multiple receive signals, thereby generating receive beam data.

[0029] One electronic scan forms one receive frame (receive frame data). One receive frame is made up of multiple receive beam data aligned in the electronic scan direction. Each beam data is made up of multiple echo data aligned in the depth direction. In the illustrated configuration example, a first receive frame corresponding to a first beam scanning plane and a second receive frame corresponding to a second beam scanning plane are obtained alternately.

[0030] The beam data processing unit 24 includes an envelope detection circuit, a filter, a logarithmic compression circuit, etc. The filter is, for example, a band-pass filter (BPF). The characteristics of the band-pass filter are dynamically changed according to the depth of the receiving point. In the embodiment, the characteristics of the band-pass filter are also changed according to the beam deflection angle. This will be described in detail later.

[0031] The image forming unit 26 is a circuit that generates multiple display frames from multiple received frames. Specifically, the image forming unit 26 is configured with a digital scan converter (DSC) that has functions such as coordinate conversion, pixel interpolation, and frame rate change. Each display frame corresponds to a tomographic image as a still image. Images other than tomographic images may also be formed as ultrasound images. When spatial compounding is performed, the multiple display frames that have been formed are sent to a synthesis unit 28.

[0032] The synthesis unit 28 sequentially extracts display frame pairs, each consisting of two temporally adjacent display frames, from the input display frame sequence, and synthesizes each display frame pair to generate a synthesized frame. The synthesis unit 28 outputs a synthesized frame sequence. When synthesizing the display frame pairs, for example, a rectangular overlapping portion is cut out, and two non-overlapping portions (two end portions) are discarded.

[0033] The composite frame sequence may be generated by combining frame sequences before coordinate transformation, or by combining RF frame sequences before envelope detection.

[0034] The display processing unit 30 has a graphic synthesis function, a color calculation function, etc. The synthesized frame sequence is sent from the display processing unit 30 to a display 32. The synthesized frame sequence is displayed on the display 32 as a tomographic image (moving image). The display 32 is configured with an organic EL display device, an LCD, etc. The synthesis unit 28 and the display processing unit 30 are each configured with a processor. The control unit 34 described below may function as the synthesis unit 28 and the display processing unit 30.

[0035] The control unit 34 is configured by a CPU that executes a program. The control unit 34 controls the operation of each component shown in FIG. 1 and also executes various information processing. Specifically, the control unit 34 functions as a transmission / reception control unit 38. The control unit 34 also functions as a spatial compound control unit 36. The transmission / reception control unit 38 and a synthesis control unit 40 function during spatial compound control. The specific content of spatial compound control will be explained later. The operation panel 42 connected to the control unit 34 is an input device having multiple switches, multiple knobs, a keyboard, a trackball, etc.

[0036] FIG. 2 shows beam scanning according to the first embodiment. The horizontal x-axis indicates the position in the electronic scanning direction. The positive electronic scanning direction is represented by +x, and the negative electronic scanning direction is represented by -x. The transducer element array 46 is composed of multiple transducer elements aligned along the x-axis. The z-axis, which is orthogonal to the x-axis, is the depth axis. A transmitting and receiving aperture is set for the transducer element array 46, and the transmitting and receiving aperture is electronically scanned.

[0037] In FIG. 2, reference numeral 48 denotes a center line that crosses the center of the transducer array 46. The beam deflection angle is indicated by θ. With respect to the beam deflection angle θ, the counterclockwise direction is the positive side (+θ side), and the clockwise direction is the negative side (-θ side). R denotes one end of the electronic scanning direction, and L denotes the other end of the electronic scanning direction. The transmitting and receiving aperture 50R is an aperture corresponding to the one end R. The transmitting and receiving aperture 50L is an aperture corresponding to the other end L. In the illustrated example, the center position of the transmitting and receiving aperture 50R coincides with the position of the one end R, and the center position of the transmitting and receiving aperture 50L coincides with the position of the other end L. Note that the transmitting and receiving apertures may be set so as to partially extend beyond the transducer array 46 or to straddle the actual ends of the transducer array 46. In this case, the transmitting and receiving apertures are composed of a real aperture portion and a virtual aperture portion.

[0038] The direction of electronic scanning of the ultrasonic beam is either the +x direction or the -x direction. That is, the transmit / receive aperture is electronically scanned in the +x direction or the -x direction. The ultrasonic beam is, for example, a transmit beam and a receive beam. The ultrasonic beam may be understood as a combined transmit / receive beam. When parallel reception is performed, multiple receive beams are formed simultaneously for one transmission. In this case, the arrangement of multiple receive beams may be determined according to a beam deflection angle function described below. Hereinafter, the ultrasonic beam will be simply referred to as a beam. Note that z1 indicates the maximum depth (depth range) for imaging.

[0039] In the first embodiment, first beam scanning planes 16 and second beam scanning planes 18 are formed alternately. To explain in more detail, the first beam scanning plane 16 is made up of a plurality of first beams aligned in the electronic scanning direction. Specifically, it is made up of n beams from a first beam 54R corresponding to one end R to a first beam 54L corresponding to the other end L. The beam deflection angle θ of the plurality of first beams is 54R First beam from 54L The value increases continuously toward the negative side (-θ side) from

[0040] In the first embodiment, the beam deflection angle θ of the first beam 54R is 0 degrees, and the beam deflection angle of the first beam 54L is −α. Focusing on the deep part of the first beam scanning surface 16, the inter-beam pitch increases continuously from the first beam 54R to the first beam 54L.

[0041] The second beam scan plane 18 is composed of multiple second beams aligned in the electronic scan direction. Specifically, it is composed of n beams from the second beam 56L corresponding to the other end L to the second beam 56R corresponding to the one end R. The beam deflection angle θ of the multiple second beams continuously increases toward the positive side (+θ side) from the second beam 56L to the second beam 56R.

[0042] In the first embodiment, the beam deflection angle θ of the second beam 56L is 0 degrees, and the beam deflection angle of the second beam 56R is +α. Focusing on the deep part of the second beam scanning surface 18, the inter-beam pitch increases continuously from the second beam 56L to the second beam 56R.

[0043] When forming the first beam scan plane 16, a non-parallel scan stretched in the -x direction is performed, and when forming the second beam scan plane 18, a non-parallel scan stretched in the +x direction is performed.

[0044] The first beam scan surface 16 has a first diverging shape. The second beam scan surface 18 has a second diverging shape. The first diverging shape is a trapezoid with a right angle, only the bottom side of which extends in the negative electronic scan direction. The second diverging shape is also a trapezoid with a right angle, only the bottom side of which extends in the positive electronic scan direction.

[0045] Reference numeral 44 indicates an overlapping region between the first beam scanning plane 16 and the second beam scanning plane 18. The overlapping region 44 is rectangular. The overlapping region 44 constitutes a display region. On the negative side (-x side) of the overlapping region 44, there is a triangular end region 16a that belongs only to the first beam scanning plane 16. On the positive side (+x side) of the overlapping region 44, there is a triangular end region 18a that belongs only to the second beam scanning plane 18. The two end regions 16a, 18a are not imaged.

[0046] In the first embodiment, |α| is set, for example, within the range of 10 to 20 degrees. It may be set within the range of 20 to 30 degrees, or within the range of 5 to 10 degrees. Note that Z1 indicates the ultrasonic propagation distance corresponding to depth z1 when the beam deflection angle θ is −α. When dynamically varying the filter characteristics, the ultrasonic propagation distance is taken into account for each receiving point on each beam. In this case, the round-trip propagation distance may also be taken into account.

[0047] Figure 3 shows the spatial compounding technique according to the first embodiment. T is the time axis, and T1, T2, T3, and T4 indicate frame processing timings, respectively. (A) shows the beam scan plane sequence, (B) shows the frame sequence, and (C) shows the composite frame sequence.

[0048] The beam scanning plane sequence is composed of a first beam scanning plane FA, a second beam scanning plane FB, a first beam scanning plane FA, a second beam scanning plane FB, ... The maximum beam deflection angle θ at each first beam scanning plane FA is -α, and the maximum beam deflection angle θ at each second beam scanning plane FB is +α. A frame sequence is generated as the beam scanning plane sequence is formed. The frame sequence is composed of a first frame GA, a second frame GB, a first frame GA, a second frame GB, ...

[0049] A synthesis process is applied to each frame pair in the frame sequence to generate a synthesis frame H. Each synthesis frame H consists of an overlapping portion Ha and non-overlapping portions Hb and Hc. The non-overlapping portions Hb and Hc are usually discarded. The overlapping portion Ha is the target of imaging.

[0050] 4 shows a first beam deflection angle function 58 and a second beam deflection angle function 60 according to the first embodiment. The horizontal axis represents the x-axis, and the vertical axis represents the beam deflection angle θ. When forming the first beam scanning plane, the beam deflection angle of each first beam is set according to the first beam deflection angle function 58. When forming the first beam scanning plane, the minimum beam deflection angle θ is 0 degrees, and the maximum beam deflection angle θ is -α degrees.

[0051] When forming the second beam scanning plane, the beam deflection angle of each second beam is set according to the second beam deflection angle function 60. When forming the second beam scanning plane, the minimum beam deflection angle θ is 0 degrees, and the maximum beam deflection angle θ is +α degrees. The first beam deflection angle function 58 and the second beam deflection angle function 60 are each straight lines that are parallel to each other. The interval between them is α.

[0052] 5 shows a beam deflection angle difference function 62 according to the first embodiment. The horizontal axis represents the x-axis, and the vertical axis represents the beam deflection angle difference Δθ. The beam deflection angle difference Δθ is always a constant value α, regardless of the position in the x-axis direction.

[0053] FIG. 6 shows the operation of the BPF included in the beam data processing unit. The horizontal axis indicates the ultrasonic propagation distance, and the vertical axis indicates the cutoff frequency. The BPF is composed of an LPF and an HPF. Reference numeral 80 indicates the cutoff frequency characteristic of the LPF, and reference numeral 82 indicates the cutoff frequency characteristic of the HPF. The area 83 between the two cutoff frequency characteristics 80 and 82 corresponds to the passband. In the cutoff frequency characteristics 80 and 82, the cutoff frequencies of the LPF and HPF are lowered as the ultrasonic propagation distance increases. The ultrasonic propagation distance increases with the depth of the receiving point and with an increase in the beam deflection angle (increase in |θ|).

[0054] 7 shows the control of the BPF according to the embodiment. During electronic scanning of the first beam, the beam deflection angle is changed according to a beam deflection angle function 84. Even if the reception point depth remains the same, the ultrasonic propagation distance increases as the beam deflection angle increases. Focusing on a reception point at a certain depth, as the beam deflection angle increases, the cutoff frequencies of the LPF and HPF are lowered, as shown by function 88.

[0055] When the second beam is electronically scanned, the beam deflection angle is changed according to a beam deflection angle function 86. Even if the reception point depth is the same, the ultrasonic propagation distance increases as the beam deflection angle increases. When focusing on a reception point at a certain depth, the cutoff frequencies of the LPF and HPF are lowered as the beam deflection angle increases, as shown by function 90. Note that in FIG. 7, both function 88 and function 90 are expressed schematically. They may also be curved lines.

[0056] FIG. 8 shows a first comparative example. (A) shows a beam scanning plane sequence. (B) shows a frame sequence. (C) shows a composite frame sequence. The beam scanning plane sequence includes a first beam scanning plane FA, a second beam scanning plane FB, and a third beam scanning plane FC. The first beam scanning plane FA is composed of a plurality of first beams, and the beam deflection angle thereof is constant (-φ degrees). The second beam scanning plane FB is composed of a plurality of second beams, and the beam deflection angle thereof is constant (0 degrees). The third beam scanning plane FC is composed of a plurality of third beams, and the beam deflection angle thereof is constant (+φ degrees). A composite frame H is generated by combining three frames that are consecutive on the time axis.

[0057] The composite frame H consists of a triplet portion Ha, doublet portions Hb and Hc, and non-combined portions Hd and He. The hatched imaging area HA is a rectangular area that includes the triplet portion Ha and doublet portions Hb and Hc. In the imaging area HA, the doublet portions Hb and Hc have a smaller beam deflection angle difference (and fewer overlaps) than the triplet portion Ha, resulting in a reduced spatial compounding effect. Furthermore, because the composite frame is generated from three frames, temporal response can be an issue in some cases.

[0058] FIG. 9 shows a second comparative example. (A) shows a beam scanning plane sequence. (B) shows a frame sequence. (C) shows a composite frame sequence. The beam scanning plane sequence includes a first beam scanning plane FA and a second beam scanning plane FB. Each composite frame consists of an overlapping portion Ha and non-overlapping portions Hb, Hc. The imaging area HA, represented by a dashed line, is a rectangular area and includes the overlapping portion Ha and non-overlapping portions Hb1, Hc1. The second comparative example provides better temporal response than the first comparative example, but the entire imaging area HA cannot be made into an overlapping area.

[0059] In contrast, according to the first embodiment, a composite frame can be generated from two frames, and the entire rectangular imaging area in the composite frame can be made into an overlapping area. Moreover, a relatively large beam deflection angle difference can be ensured over the entire imaging area, thereby achieving a good spatial compounding effect over the entire imaging area.

[0060] FIG. 10 shows a first modified example of the first embodiment. The array of beam scan planes includes four beam scan planes FA1, FB1, FA2, and FB2. When forming the beam scan plane FA1, the beam deflection angle is continuously increased on the negative side from 0 to -α1 from one end to the other in the electronic scanning direction. When forming the beam scan plane FB1, the beam deflection angle is continuously increased from 0 to +α1 from the other end to the one end in the electronic scanning direction. When forming the beam scan plane FA2, the beam deflection angle is continuously increased from 0 to -α2 from one end to the other in the electronic scanning direction. When forming the beam scan plane FB2, the beam deflection angle is continuously increased from 0 to +α2 from the other end to the one end in the electronic scanning direction. Here, |α1|<|α2|.

[0061] The frame sequence includes four frames GA1, GB1, GA2, and GB2 corresponding to four beam scan planes FA1, FB1, FA2, and FB2. When generating a composite frame, four frames that are consecutive in time are synthesized. For example, frames GA1, GB1, GA2, and GB2 are synthesized. The order in which the four beam scan planes FA1, FB1, FA2, and FB2 are formed can be determined arbitrarily.

[0062] According to the first modification, a high spatial compounding effect can be obtained across the entire display area, thereby further improving image quality. When priority is given to time response, the number of composites can be set to 2, i.e., the sequence shown in Figure 3 can be adopted. On the other hand, when priority is given to image quality, the number of composites can be set to 4, i.e., the sequence shown in Figure 10 can be adopted.

[0063] 11 shows a second modified example of the first embodiment. (A) shows a beam scanning plane sequence. (B) shows a frame sequence. (C) shows an intermediate composite frame sequence. (D) shows a composite frame sequence.

[0064] The intermediate composite frame sequence is composed of multiple intermediate composite frames GC generated based on the frame sequence. Each intermediate composite frame GC is generated for each frame pair (GA-GB pair or GB-GA pair) in the frame sequence by applying nonlinear processing to the frame pair. For example, the intermediate composite frame GC may be generated by Lagrangian interpolation processing, spline interpolation processing, etc. The intermediate composite frame GC may also be generated by a neural network (machine-learned image generation model).

[0065] The composite frame H is generated by combining three frames: the two frames that make up the frame pair and an intermediate composite frame generated from the frame pair. For example, the composite frame H is generated by adding together the frame GA, the frame GB, and the intermediate composite frame GC. According to the second modification, a higher spatial compounding effect can be obtained.

[0066] Next, a second embodiment will be described with reference to FIGS.

[0067] In FIG. 12, (A) shows a beam scan plane array, (B) shows a frame array, and (C) shows a composite frame array. The beam scan plane array consists of a plurality of first beam scan planes FA and a plurality of second beam scan planes FB that are formed alternately. In each first beam scan plane FA, the deflection angle of the beam 66R corresponding to one end of the electronic scan direction is +ζ, and the deflection angle of the beam 66L corresponding to the other end of the electronic scan direction is -α. From one end to the other end in the electronic scan direction, the beam deflection angle increases toward the negative side (-θ side).

[0068] On each second beam scan plane FB, the deflection angle of the beam 68L corresponding to the other end of the electronic scanning direction is -ζ, and the deflection angle of the beam 68R corresponding to one end of the electronic scanning direction is +α. From the other end to the one end of the electronic scanning direction, the beam deflection angle increases toward the positive side (+θ). Each composite frame H is composed of an overlapping portion Ha and non-overlapping portions Hb and Hc. The overlapping portion Ha has a symmetrical, diverging shape. The relationship |α|>|ζ|>0 holds. Note that α in the second embodiment corresponds to the angle obtained by adding ζ to α in the first embodiment (see FIG. 2).

[0069] 13 shows a first beam deflection angle function 70 and a second beam deflection angle function 72 according to the second embodiment. When forming the first beam scanning plane, the beam deflection angle of each first beam is set according to the first beam deflection angle function 70. When forming the first beam scanning plane, the beam deflection angle θ at one end is +ζ, and the beam deflection angle θ at the other end is -α.

[0070] When forming the second beam scanning plane, the beam deflection angle of each second beam is set according to the second beam deflection angle function 72. When forming the second beam scanning plane, the beam deflection angle θ at the other end is -ζ degrees, and the beam deflection angle θ at one end is +α degrees. The first beam deflection angle function 70 and the second beam deflection angle function 72 are each straight lines that are parallel to each other. The interval between them is (α-ζ).

[0071] 14 shows a beam deflection angle difference function 74 according to the second embodiment. The beam deflection angle difference is always (α-ζ) regardless of the position in the x-axis direction.

[0072] According to the second embodiment, similar to the first embodiment, good temporal response and good spatial compounding effect can be obtained, and the overlapping region, that is, the imaging region, can be further enlarged.

[0073] 15 shows a modified example of the second embodiment. When forming the first beam scan plane, the beam deflection angle of each first beam is set according to a first beam deflection angle function 76. When forming the first beam scan plane, the beam deflection angle θ at one end is +ζ, and the beam deflection angle θ at the other end is -α. The first beam deflection angle function 76 is a curve, and specifically has a shape similar to a logistic curve.

[0074] When forming the second beam scanning plane, the beam deflection angle of each second beam is set according to the second beam deflection angle function 78. When forming the second beam scanning plane, the beam deflection angle θ at the other end is -ζ, and the beam deflection angle θ at the one end is +α. The second beam deflection angle function 78 is a curve, and specifically, like the first beam deflection angle function 76, it has a shape like a logistic curve. In the first embodiment, the two beam deflection angle functions shown in FIG. 4 may be curves.

[0075] Next, a third embodiment will be described with reference to Figures 16 to 18. In the third embodiment, a 1.25D probe is used as the ultrasonic probe. Alternatively, a 1.5D probe, a 1.75D probe, or a 2D probe may be used.

[0076] FIG. 16 shows a transducer array 92 arranged on a 1.25D probe. The x direction is the long axis direction, which is the electronic scanning direction, and the y direction is the short axis direction. The transducer array 92 is composed of three transducer element rows 94, 96, and 98 arranged in the y direction. The central transducer element row 94 is composed of a plurality of transducer elements arranged in the x direction. Similarly, the transducer element row 96 on one side of the y direction and the transducer element row on the other side of the y direction are each composed of a plurality of transducer elements arranged in the x direction. From another perspective, the transducer element array 92 is composed of a plurality of transducer element sets 100 arranged in the x direction. Each transducer element set 100 is composed of three transducer elements arranged in the y direction.

[0077] The signal line group 102 is composed of multiple signal lines connected to multiple transducer element sets 100. When the switches 104A and 104B are in the off state, the signal line group 102 is connected only to the transducer element array 96. In this case, a small aperture size D1 is set in the y direction. For example, a transmitting and receiving aperture 105A is set. On the other hand, when the switches 104A and 104B are in the on state, the signal line group 102 is connected to the three transducer element arrays 94, 96, and 98. In this case, a large aperture size D2 is set in the y direction. For example, a transmitting and receiving aperture 105B is set. The operation of the switches 104A and 104B is controlled by a control unit.

[0078] 17 shows a spatial compounding technique according to a third embodiment. (A) shows switching of the aperture size in the minor axis direction. Small aperture size D1 and large aperture size D2 are set alternately.

[0079] The beam scan plane array shown in (B) includes a first beam scan plane FA1, a second beam scan plane FA2, a third beam scan plane FB1, and a fourth beam scan plane FB2. The first beam scan plane FA1 is composed of multiple first beams formed under a small aperture size D1. The beam deflection angles of the multiple first beams continuously increase from 0 degrees to -α degrees on the negative side from one end to the other in the electronic scan direction.

[0080] The second beam scan plane FA2 is composed of multiple second beams formed under the large aperture size D2. The beam deflection angles of the multiple second beams continuously increase from 0 degrees to -α degrees on the negative side from one end to the other in the electronic scanning direction.

[0081] Third beam scanning plane FB1 is composed of multiple third beams formed under a small aperture size D1. The beam deflection angles of the multiple third beams continuously increase on the positive side from 0 degrees to +α degrees from one end to the other end in the electronic scanning direction.

[0082] 4th beam scanning plane FB2 is composed of multiple fourth beams formed under the large aperture size D2. The beam deflection angles of the multiple fourth beams increase continuously from 0 degrees to +α degrees on the positive side from one end to the other end in the electronic scanning direction.

[0083] The frame sequence shown in (C) includes a first frame GA1 obtained from the first beam scanning plane FA1, a first frame GA2 obtained from the second beam scanning plane FA2, a first frame GB1 obtained from the third beam scanning plane FB1, and a first frame GB2 obtained from the fourth beam scanning plane FB2. (D) shows weighted synthesis applied to four temporally consecutive frames.

[0084] For example, weighting functions 106 and 108 shown in Fig. 18 are used. The horizontal axis represents depth (or propagation distance), and the vertical axis represents weight. Weighting function 106 is applied when a small aperture size D1 is set, and weighting function 108 is applied when a large aperture size D2 is set.

[0085] A weighting function is applied to each frame, and the resulting four weighted frames are then synthesized. By performing weighting synthesis on four consecutive frames on the time axis, a sequence of synthesized frames shown in (E) is generated.

[0086] According to the fourth embodiment, a good spatial compounding effect can be obtained from shallow to deep depths. That is, the image quality of the ultrasound image can be improved. The order in which the first beam scan plane FA1, the second beam scan plane FA2, the third beam scan plane FB1, and the fourth beam scan plane FB2 are formed can be determined arbitrarily.

[0087] For example, as shown in FIG. 19, a plurality of beam scan planes may be formed cyclically in the order of the first beam scan plane FA1, the third beam scan plane FB1, the second beam scan plane FA2, and the fourth beam scan plane FB2.

[0088] As shown in Fig. 20, the spatial compounding technique according to the embodiment may be applied to a convex probe. In Fig. 20, a convex probe 110 has a transducer element array 112 consisting of a plurality of transducer elements arranged in an arc shape. The negative electronic scanning direction is indicated by -x, and the positive electronic scanning direction is indicated by +x. R indicates one end of the electronic scanning direction, and L indicates the other end of the electronic scanning direction. Symbols 113 indicates a transmitting and receiving aperture set around one end R, and reference numeral 114 indicates a transmitting and receiving aperture set around the other end L. z indicates the depth direction. As already explained, the transducer element array 112 or the vibrating element array 112 The transmit and receive apertures may be set across the actual edges of the

[0089] First beam scanning planes 120 and second beam scanning planes 122 are formed alternately. The first beam scanning plane 120 is composed of a plurality of first beams. The plurality of first beams is composed of n first beams from a first beam 118R corresponding to one end R to a first beam 118L corresponding to the other end L. The beam deflection angle θ of the first beam 118R is 0 degrees, and the beam deflection angle θ of the first beam 118L is -α. From one end R to the other end L in the electronic scanning direction, the beam deflection angle θ continuously increases to the negative side (-θ side).

[0090] The second beam scan plane 122 is composed of a plurality of second beams. The plurality of second beams is composed of n second beams from a second beam 119L corresponding to the other end L to a second beam 119R corresponding to one end R. The beam deflection angle θ of the second beam 119L is 0 degrees, and the beam deflection angle θ of the second beam 119R is +α. From the other end L to the one end R in the electronic scanning direction, the beam deflection angle θ continuously increases to the positive side (+θ side). As described above, the spatial compounding technique according to the embodiment can also be applied to a convex probe. [Explanation of symbols]

[0091] 10 ultrasound probe, 28 synthesis unit, 30 display processing unit, 36 spatial compound control unit, 38 transmission / reception control unit, 40 synthesis control unit.

Claims

1. a transducer element array having a plurality of transducer elements arranged in an electronic scanning direction; a control unit that controls an operation of the transducer array so that a plurality of beam scanning planes including a first beam scanning plane and a second beam scanning plane are sequentially formed; a synthesis unit that synthesizes a plurality of frame data obtained by forming the plurality of beam scanning planes; Including, the first beam scanning plane is configured by a plurality of first beams aligned in the electronic scanning direction, the beam deflection angles of the plurality of first beams continuously increase toward the negative side from one end to the other end in the electronic scanning direction, the second beam scanning plane is configured by a plurality of second beams aligned in the electronic scanning direction, the beam deflection angles of the second beams continuously increase toward a positive side from the other end to the one end, the transducer array has a plurality of transducer element rows arranged in a minor axis direction perpendicular to a major axis direction that is the electronic scanning direction, Each of the vibration element rows is composed of a plurality of vibration elements aligned in the electronic scanning direction, the plurality of beam scanning planes include the first beam scanning plane, the second beam scanning plane, a third beam scanning plane, and a fourth beam scanning plane; the third beam scanning plane is configured by a plurality of third beams aligned in the electronic scanning direction, the beam deflection angles of the third beams continuously increase toward the negative side from the one end to the other end, the fourth beam scanning plane is configured by a plurality of fourth beams aligned in the electronic scanning direction, the beam deflection angles of the plurality of fourth beams continuously increase toward a positive side from the other end to the one end, When the first beam scanning surface and the second beam scanning surface are formed, a first opening size is set in the vibration element array in the minor axis direction, When the third beam scanning plane and the fourth beam scanning plane are formed, a second opening size is set in the vibration element array in the minor axis direction, the first opening size and the second opening size are different from each other; An ultrasonic diagnostic device characterized by:

2. 2. The ultrasonic diagnostic apparatus according to claim 1, the control unit sets deflection angles of the plurality of first beams according to a first beam deflection angle function, and sets deflection angles of the plurality of second beams according to a second beam deflection angle function; in a coordinate system defined by a first axis indicating a position in the electronic scanning direction and a second axis indicating a beam deflection angle, the first beam deflection angle function is expressed by a first line, and the second beam deflection angle function is expressed by a second line; In the coordinate system, the first line and the second line are each a straight line or a curved line. An ultrasonic diagnostic device characterized by:

3. 3. The ultrasonic diagnostic apparatus according to claim 2, In the coordinate system, the first line and the second line are parallel. An ultrasonic diagnostic device characterized by:

4. 4. The ultrasonic diagnostic apparatus according to claim 3, In the coordinate system, the first line and the second line are each a straight line. An ultrasonic diagnostic device characterized by:

5. 2. The ultrasonic diagnostic apparatus according to claim 1, In the first beam scanning plane, the deflection angle of the first beam corresponding to the one end is 0 degrees or +ζ degrees, and the deflection angle of the first beam corresponding to the other end is −α degrees (where |α|>0 or |α|>|ζ|>0); In the second beam scanning plane, the deflection angle of the second beam corresponding to the other end is 0 degrees or −ζ degrees, and the deflection angle of the second beam corresponding to the one end is +α degrees. An ultrasonic diagnostic device characterized by:

6. 2. The ultrasonic diagnostic apparatus according to claim 1, the plurality of frame data include first frame data obtained by forming the first beam scanning plane, second frame data obtained by forming the second beam scanning plane, third frame data obtained by forming the third beam scanning plane, and fourth frame data obtained by forming the fourth beam scanning plane, the combining unit weights and combines the first frame data, the second frame data, the third frame data, and the fourth frame data. An ultrasonic diagnostic device characterized by:

7. 2. The ultrasonic diagnostic apparatus according to claim 1, a filter that operates on a plurality of first received signals corresponding to the plurality of first beams and a plurality of second received signals corresponding to the plurality of second beams; the control unit changes characteristics of the filter according to deflection angles of the plurality of first beams and deflection angles of the plurality of second beams. An ultrasonic diagnostic device characterized by:

8. 2. The ultrasonic diagnostic apparatus according to claim 1, the number of the plurality of beam scanning planes is an even number, The beam scanning surface set consisting of the even number of beam scanning surfaces is formed cyclically. An ultrasonic diagnostic device characterized by:

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