JP2007044193A - Ultrasonic diagnosing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the picture quality of an ultrasonic image while aiming at the channel reduction in an ultrasonic diagnosing device which forms a three-dimensional image by using a 2D array oscillator. <P>SOLUTION: A plurality of subsidiary arrays 300A are set on the 2D array oscillator 300. A plurality of groups are set for each subsidiary array 300A. Each group is constituted of a plurality of vibration elements having a parallel connecting relationship. A subsidiary array shape regarding a plurality of the subsidiary arrays 300A is variably set depending on a beam orientation 304 and the depth of a focal point F1. Also, grouping patterns 310 to 320 are variably set for each subsidiary array 300A. Distances between respective vibration elements and the focal points can be adjusted as much as possible among a plurality of the vibration elements constituting each group, and a favorable beam profile can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus used in the medical field, and more particularly to setting a plurality of subarrays on an array transducer.

  The ultrasonic diagnostic apparatus is used for diagnosing a disease of a living body (patient) in the medical field. Specifically, the ultrasonic diagnostic apparatus transmits an ultrasonic pulse to a living body, receives a reflected wave from the living body, and forms an ultrasonic image based on a reception signal obtained by the reception.

  A two-dimensional (2D) array transducer is used to two-dimensionally scan the ultrasonic beam, thereby forming a three-dimensional echo data capture space in the living body. In general, a 2D array vibrator is formed by aligning a plurality of vibration elements in the X direction and the Y direction.

  In some cases, a plurality of subarrays are set on the 2D array transducer for channel reduction of the transmission / reception unit, simultaneous formation of a plurality of reception beams, or other purposes. Conventionally, a plurality of subarrays are fixedly set on the 2D array transducer. For example, a plurality of subarrays having a rectangular shape are set for the 2D array transducer. Patent Document 1 discloses grouping of a plurality of vibration elements, but the configuration of each group is fixed. Patent Document 2 discloses a configuration in which phasing addition is performed in two stages. In FIG. 6 of Patent Document 3, a plurality of groups are fixedly set in the 2D array transducer, a plurality of first beam formers are connected to the plurality of groups, and a plurality of first beams It is shown that a plurality of second beam formers are provided after the former. Patent Document 4 discloses setting a plurality of 2D subarrays on a 2D array transducer and setting a plurality of groups on each subarray.

  If the shape or grouping pattern of each subarray is set uniformly or fixedly, there is a problem that a good beam profile cannot be obtained depending on transmission / reception conditions. For example, side lobes are likely to appear in a specific beam scanning direction. Patent Documents 5 and 6 disclose setting a plurality of subarrays on an array transducer and setting a plurality of groups for each subarray. Each group is basically composed of a plurality of vibration elements, and a common transmission signal is distributed and supplied to them. A plurality of reception signals from a plurality of vibration elements constituting the group are added, and a delay process is performed on the reception signals after the addition. Patent Document 6 describes that the shape of each subarray is changed in accordance with the beam scanning direction.

JP 2001-276064 A JP 2001-104303 A JP-A-9-322896 US Pat. No. 5,832,923 JP 2005-34633 A JP 2005-34634 A

  By the way, in order to realize a good focus, between each vibration element and the focus point between a plurality of vibration elements in a parallel connection relationship (that is, the same delay processing relationship) constituting each group. It is desirable to determine the configuration of each group (grouping pattern in each subarray) so that the distances are as equal as possible. When the beam address or focus point (especially transmission focus point) depth changes, the acoustic distance from the focus point to each vibration element changes. Therefore, it is desirable to dynamically change the subarray shape and grouping pattern with such a change in beam scanning conditions.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of obtaining a good beam profile.

  Another object of the present invention is to make it possible to maintain or improve the image quality of an ultrasonic image when performing channel reduction of a transmission / reception unit.

(1) An ultrasonic diagnostic apparatus according to the present invention includes a plurality of vibration elements, an array transducer that forms a two-dimensionally scanned ultrasonic beam, and is connected to the array transducer, Switching means for setting a plurality of sub-arrays and setting a plurality of groups each composed of one or a plurality of vibration elements for each sub-array, and being connected to the array transducer via the switching means. Transmitting means for generating a group transmission signal for each group; receiving means connected to the array transducer via the switching means; and processing a group reception signal of each group output from the switching means; And the switching means includes grouping for each of the subarrays based on at least the depth of the focus point. The and sets individually Gupatan.

  According to the above configuration, the switching means has a sub-array setting function on the array transducer and a setting function for grouping patterns (arrangement forms of a plurality of groups) for each sub-array. A grouping pattern can be individually set for each sub-array and can be dynamically varied. Thereby, it is possible to adjust the distance from the focus point in the three-dimensional space to the respective vibration elements in the group as much as possible between a plurality of vibration elements constituting each group, and as a result, it is possible to realize a good focus. That is, if a grouping pattern is set in consideration of the depth of the focus point, a good beam profile can be obtained. Here, basically, the focus point is a transmission focus point, and the ultrasonic beam is a transmission beam. Each group is usually composed of a plurality of vibration elements, but there may be a group composed of one vibration element. As will be described later, it is desirable to change the subarray shape according to the beam scanning conditions (particularly the beam scanning direction), but the subarray shape may be fixed.

  Preferably, the switching means dynamically switches a grouping pattern set for each of the subarrays when scanning the ultrasonic beam. A uniform grouping pattern is not set for a plurality of subarrays as a whole, but a plurality of types of grouping patterns are set simultaneously.

  Preferably, the switching means further sets a grouping pattern for each of the sub-arrays according to the position based on the beam address. The beam address specifies the beam direction. The beam direction is generally determined by the position of the beam passing through a horizontal plane orthogonal to the vertical center axis of the array transducer or the beam deflection angle with respect to the vertical center axis of the array transducer and the rotation angle. In order to specify the position of each subaddress, the subarray address may be referred to. In controlling the switching means, information representing beam addresses or the like may be referred to rather than information representing beam addresses or the like. For this control, it is desirable to use a table that inputs a beam address and a depth of a focus point and generates a grouping pattern set including grouping patterns for each subarray. Further, a subarray address may be given as an input of the table.

  Preferably, the switching unit adds a function of distributing and outputting the group transmission signal to a plurality of vibration elements constituting the corresponding group, and a plurality of reception signals from the plurality of vibration elements in units of groups. And generating a group reception signal.

  The plurality of subarrays are desirably closely connected to each other on the array transducer from the viewpoint of acoustic power or sensitivity. In other words, it is desirable that all the effective all vibration elements constituting the array vibrator belong to one of the subarrays. However, a gap may exist between the subarrays. That is, there may be a vibration element that does not belong to any subarray and does not function for transmission / reception. In addition, there may be an ineffective vibration element that does not function in transmission / reception in the subarray.

  For example, if n (where 1 <n <m) groups are set for m vibration elements constituting a certain subarray, the channel reduction rate is n / m. If such channel reduction processing is performed in the probe head, there is an advantage that the number of signal lines through which the probe cable is inserted can be reduced. That is, by grouping, a plurality of received signals can be added and aggregated into one received signal (group received signal). In addition, one transmission signal (group transmission signal) can be supplied in parallel to a plurality of vibration elements constituting one group.

  Each group is basically composed of a plurality of vibration elements, but a group of one vibration element may exist. Desirably, the number of vibrating elements constituting each group in the sub-array is not uniform and can be dynamically varied. Desirably, a pattern variation area is defined for each subarray, whereby a plurality of pattern variation areas are defined on the array transducer, and the pattern variation area for each subarray is an area where a plurality of subarray shape patterns are combined. Correspondingly, the plurality of pattern variation regions have portions that partially overlap each other. Desirably, each pattern variation region covers a plurality of vibration elements unique to each sub-array and a plurality of vibration elements present in overlapping portions.

(2) An ultrasonic diagnostic apparatus according to the present invention is composed of a plurality of vibration elements, and forms an ultrasonic beam to be two-dimensionally scanned, and is connected to the array vibrator, and includes a beam address and a focus point. Switching means for setting a plurality of subarrays for the array transducer and setting a plurality of groups each composed of one or a plurality of vibration elements for each of the subarrays based on the depth and the subarray address And transmitting means for generating a group transmission signal for each group, connected to the array transducer via the switching means, and connected to the array transducer via the switching means, and output from the switching means Receiving means for processing the group received signal of each group.

  According to the above configuration, a good ultrasonic beam can be formed and the image quality of the ultrasonic image can be improved by setting the subarray shape for a plurality of subarrays and setting the grouping pattern for each subarray. In particular, since the subarray shape can be changed to an appropriate one, side lobes can be reduced.

  Preferably, the switching means dynamically switches a subarray shape set for each subarray during scanning of the ultrasonic beam, and dynamically changes a grouping pattern set for each subarray. Switch. Preferably, the switching means switches a subarray shape set for each of the subarrays according to a beam scanning direction on a horizontal plane orthogonal to the vertical center axis of the array transducer.

  Preferably, the main phasing addition processing is applied to the plurality of sub phasing addition signals after the sub phasing addition processing is performed for each group. A plurality of main phasing and adding circuits may be arranged in parallel, and a plurality of reception beams may be simultaneously formed by one reception. In the probe cable, the transmission signal may be transmitted as a voltage signal, and the reception signal may be transmitted as a current signal. The transmission signal may be a voltage signal of about 100 V, or may be a low voltage signal of about several volts to several tens of volts. In the latter case, for example, it is desirable to laminate each vibration element, thereby reducing the electrical impedance of each vibration element.

  Desirably, at least the array transducer and the switching means are provided in the probe head. Further, a plurality of sub phase adjusting and summing circuits may be provided in the probe head (in this case, the number of signal lines can be further reduced), or a plurality of sub phase adjusting and summing circuits may be provided in the probe connector or the apparatus main body. You may make it provide in. The transmission unit can be provided in the probe head, the cable connector, or the apparatus main body.

  As described above, according to the present invention, it is possible to provide an ultrasonic diagnostic apparatus capable of realizing a good focus and obtaining a good beam profile. Alternatively, according to the present invention, it is possible to maintain or improve the image quality of an ultrasonic image when performing channel reduction of a transmission / reception unit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the basic configuration of the ultrasonic diagnostic apparatus according to the present embodiment will be described with reference to FIG. The ultrasonic diagnostic apparatus includes a probe (probe unit) 240 and an apparatus main body 242. The probe 240 has a probe head 244, a probe cable 246, and a cable connector 247. The apparatus main body 242 includes a transmission / reception control unit 248, a reception unit 250, a signal processing module 252, an image forming unit 254, and a display unit 256. The cable connector 247 is detachably connected to a connector (not shown) of the apparatus main body 242. An electronic circuit 249 is built in the cable connector 247 in this embodiment. The electronic circuit 249 executes a sub-phasing addition process and a transmission signal generation process as will be described in detail later. The receiving unit 250 executes main phasing addition processing. The probe head 244 transmits and receives ultrasonic waves. The received signal thus obtained is input to the image forming unit 254 via the electronic circuit 249, the receiving unit 250 and the signal processing module 252. In this image forming unit 254, an ultrasonic image is formed based on the received signal. The ultrasonic image is displayed on the screen of the display 256. As the ultrasonic image, a two-dimensional tomographic image, a two-dimensional blood flow image, a three-dimensional image, and the like are known. In the present embodiment, a volume rendering process is performed on volume data acquired from a 3D space in a living body to form a 3D image. Various other methods for forming a three-dimensional image are known.

  FIG. 2 is a block diagram illustrating a configuration of a transmission / reception unit in the ultrasonic diagnostic apparatus according to the embodiment. The illustrated ultrasound diagnostic apparatus includes a probe unit and an apparatus main body 12, and the probe unit includes a probe head 10, a probe cable 14A, and a cable connector 14B.

  In the present embodiment, a plurality of transmission / reception modules 24 (that is, equivalent to the electronic circuit 249 described later) are accommodated in the cable connector 14B. However, a plurality of transmission / reception modules 24 can be provided in the probe head 10 or in the apparatus main body 12.

  The probe head 10 is, for example, a transducer that is used in contact with the body surface and transmits and receives ultrasonic waves. The probe head 10 has a 2D array transducer 16. An ultrasonic beam is formed by the 2D array transducer 16. The ultrasonic beam is electronically scanned two-dimensionally. As a result, a three-dimensional echo data capturing space (three-dimensional space) is formed. Examples of the ultrasonic beam electronic scanning method include an electronic sector scanning method. In addition, an electronic convex scanning method can be used.

  In the present embodiment, the array transducer 16 is configured by a large number (for example, 3000 or 4000) of vibration elements 16a. These vibration elements 16a are two-dimensionally arranged (see FIG. 4 described later). The switching circuit 20 is configured as a multiplexer or a switching matrix. In the present embodiment, the switching circuit 20 has a function of setting a plurality of subarrays on the 2D array transducer 16 and a function of setting a plurality of groups for each subarray (grouping function). The switching circuit 20 has a function of changing the shape of each subarray (subarray pattern on the array transducer 16) and a function of changing the arrangement and shape of each group (grouping pattern on each subarray). Yes.

  In particular, in this embodiment, as will be described in detail later with reference to FIGS. 13 to 15, the shape of each subarray is selected according to the beam forming conditions in order to reduce the side lobes and improve the beam profile. At the same time, grouping patterns are individually set for each subarray. In other words, the acoustic distances between the vibrating elements and the focus point are aligned as much as possible between the plurality of vibrating elements in the parallel connection relationship (same delay processing relationship) constituting the group, and the phase between them is adjusted. The deviation is made as small as possible. Also, the subarray shape is changed so that it can be realized more appropriately. In the present embodiment, the same subarray shape is set for a plurality of subarrays, but a plurality of different subarray shapes may be set for the plurality of subarrays. Note that the switching circuit 20 may be configured by a single circuit as illustrated in FIG. 2 or may be configured by a plurality of circuits.

  In FIG. 2, a plurality of subarrays S set by the switching circuit 20 are conceptually shown. On the 2D array transducer 16, the plurality of subarrays S are closely connected to each other, and the plurality of subarrays S are basically configured using all the vibration elements 16a. As described above, in the present embodiment, the subarray shape of each subarray can be changed, and the pattern variation region for each subarray is conceptually indicated by the symbol R in FIG. The change of the subarray shape will be described in detail later. A plurality of groups are set for each subarray, and the grouping pattern can be freely changed. In the present embodiment, as will be described later, the number of vibration elements constituting each group is dynamically varied according to transmission / reception conditions.

  In this embodiment, in any subarray shape, each subarray is composed of 5 × 5 = 25 vibration elements. The 25 vibration elements are divided into five groups. That is, each group is composed of five vibration elements. As a result, a channel reduction rate of 1/5 is realized in the probe head 10.

  The switching circuit 20 has the same number of terminals as the number of vibration elements constituting the 2D array vibrator 16 on the 2D array vibrator 16 side, and the same number of terminal arrays as the number of subarrays on the apparatus body 12 side. Have. In the example shown in FIG. 2, each terminal row on the apparatus body 12 side includes five terminals (the same number of terminals as the number of groups set on one subarray). Specifically, the switching circuit 20 selectively connects the element signal line array and the group signal line array. Here, the group signal line array is constituted by a plurality of group signal line sets 22, and each group signal line set 22 is constituted by five group signal lines in the example shown in FIG. The switching circuit 20 has a plurality of switches (not shown) provided at the intersections between the element signal line array and the group signal line array. The on / off operation of each switch selects one or a plurality of vibration elements connected to each group signal line. The switching circuit 20 can vary the number of vibrating elements constituting each group according to the beam forming conditions. Also, according to the beam forming conditions, the switching circuit 20 includes one or a plurality of ineffective vibrating elements ( It is also possible to set a vibration element that is not connected to any group signal line and does not transmit or receive ultrasonic waves. Incidentally, it is possible to configure each subarray by, for example, 4 × 4 = 16 vibration elements, and group the 16 vibration elements into, for example, four groups, and also configure subarrays and groups under other conditions. You may do it.

  As can be understood from the above description, the switching circuit 20 outputs five group received signals for each subarray. The group reception signal is a signal obtained by adding, for example, five reception signals output from five vibration elements that form one group. In the present embodiment, the addition is realized by a simple addition method using connection. That is, a plurality of received signals are added by interconnection of a plurality of signal lines. However, a weighted addition method or the like may be employed. The number of additions depends on the number of vibration elements constituting the group. On the other hand, as will be described later, in the cable connector 14B, five transmission signals are generated for each sub-array, and these five transmission signals are divided into five groups constituting the corresponding sub-array. Supplied against. That is, one transmission signal is distributed (supplied in parallel) to, for example, five vibration elements constituting one group. That is, one transmission signal is branched into, for example, five in the switching circuit 20. The number of branches depends on the number of vibration elements constituting the group.

  As described above, reference numeral 22 denotes a signal line set provided for each subarray. Each signal line set 22 includes five signal lines (five group signal lines). The above transmission signal and reception signal are transmitted to each signal line. Incidentally, the reception signal may be transmitted as a current signal and the transmission signal may be transmitted as a voltage signal. In this case, the transmission signal may be a voltage signal of about 100V, for example, or a low voltage signal of about several volts. The probe cable 14A has a plurality of signal line sets 22, and also has one or more control lines for transmitting control signals and the like. In FIG. 2, the illustration of a power line inserted through the probe cable 14 </ b> A is omitted.

  The cable connector 14B has, for example, a box shape, and a plurality of transmission / reception modules 24 are accommodated therein as described above. Each transmission / reception module 24 includes a transmission unit and a sub phase adjusting and adding circuit 26, as will be described later. The transmitter has five transmitters, which generate five transmission signals for each subarray. The sub phasing / adding circuit 26 is a circuit that performs sub phasing / adding processing on the five received group signals. As a result, a sub-phasing addition signal 27 is generated for each sub-array.

  In the apparatus main body 12, in this embodiment, a main phasing and adding circuit 30 and a transmission / reception control unit 32 are provided. The main phasing and adding circuit 30 receives a plurality of sub phasing and adding signals 27 and executes main phasing and adding processing, thereby generating a main phasing and adding signal (received beam signal) 31. In the phasing addition process, a known reception dynamic focus technique can be applied. Each sub phase adjusting and adding circuit 26 and the main phase adjusting and adding circuit 30 are configured as analog phase adjusting and adding circuits or as digital phase adjusting and adding circuits.

  The transmission / reception control unit 32 controls the operation of each component shown in FIG. 2, and in particular, sets the phasing addition conditions in the plurality of sub phasing addition circuits 26 and the phasing in the main phasing addition circuit 30. Addition conditions are set. The transmission / reception control unit 32 outputs a control signal to the switching circuit 20 provided in the probe head 10, and a plurality of sub-arrays and a plurality of groups are set by the control signal. Is called. The transmission / reception control unit 32 includes a switching circuit control table (not shown). In this embodiment, according to the table, according to the beam address and the depth of the focus point, the connection pattern in the switching circuit 20, that is, a plurality of vibration elements constituting the array transducer 16 and a plurality of group signal lines are connected. ON / OFF operation of the switch group to be determined is determined. In this way, when the beam address and the depth of the focus point are specified, a grouping pattern set (a plurality of subarray patterns and a grouping pattern for each subarray) over the entire array transducer 16 is uniquely identified using a table. Can be determined. However, a table for generating a connection pattern for each subarray or other tables may be used according to the beam address, the depth of the focus point, and the subarray address.

  FIG. 3 shows a specific configuration example of the transmission / reception module 24 shown in FIG. As described above, the transmission / reception module 24 includes the transmission unit 36, the sub phase adjusting and adding circuit 26, and the plurality of transmission circuits 34. Here, each transmission circuit 34 functions as a transmission pulser and a reception head amplifier circuit. Each transmission circuit 34 outputs a transmission signal to the signal line at the time of transmission, and transmits a reception signal input from the signal line to the sub phasing addition circuit 26 at the time of reception. The transmission unit 36 includes five transmitters 38. Each transmitter 38 outputs a transmission signal to which a predetermined delay time is given.

  The sub phase adjusting and adding circuit 26 can be configured as an analog phase adjusting and adding circuit having a delay line (delay line), for example, or can be configured as a digital phase adjusting and adding circuit as a digital beam former. . Further, it can be configured as a phasing addition circuit using a CCD device. Incidentally, various embodiments can be adopted for the configuration that is closer to the apparatus body than the switching circuit 20. The configuration shown in FIG. 3 is an example.

  Next, the basic function of the switching circuit 20 will be described with reference to FIGS.

  FIG. 4 conceptually shows a part of the 2D array transducer 16. Each cell corresponds to one vibration element. In this example, a plurality of subarrays are set on the 2D array transducer 16 each having a square subarray shape. In FIG. 4, in particular, subarrays S1 to S9 are shown. The subarrays S1 to S9 are closely connected to each other without a gap. In FIG. 4, an example of a group setting method is shown as a reference regarding the subarray S5. In the example shown in FIG. 4, five groups are set in the X direction. Each group is composed of five vibration elements arranged in the Y direction. Here, A, B, C, D, and E indicate identifiers of groups to which each vibration element belongs. The same applies to each figure described below. When the vertical center axis of the array transducer is the Z direction, the illustrated X direction and Y direction are orthogonal to the Z direction and correspond to two axes that define a horizontal plane.

  The subarray shape shown in FIG. 4 is the most common, i.e. square. The grouping pattern of each group shown in FIG. 4 is also a general one, and a linear shape extending in the Y direction is adopted for each group. Such a grouping pattern (arrangement of a plurality of groups in the sub-array) is employed, for example, when an ultrasonic beam is scanned in the X direction as shown in FIG.

  FIG. 5 shows another example of the subarray shape. Each of the sub-arrays S1 to S9 has a parallelogram shape as a whole inclined in a stepwise manner in an oblique direction. For example, when attention is paid to the sub-array S5, the grouping is performed as shown in the figure, and the group A is composed of five vibrating elements linearly aligned in the oblique direction, and this is the same for the other groups. However, in each stage in the Y direction, the X direction position of each group is shifted in parallel by one step. Incidentally, the same grouping pattern as that of the sub-array S5 is adopted for the other sub-arrays.

  By adopting the subarray shape and grouping pattern as shown in FIG. 5, for example, in the case of a certain focus point depth, the ultrasonic beam is scanned in a direction inclined by 45 degrees with respect to both the X direction and the Y direction. In some cases, the thickness of each group in that direction can be only 1 / √2 vibration elements. That is, it is possible to prevent the problem that the width of the vibrating portion is apparently increased in the beam scanning direction. This will be described in detail. In the present embodiment, the same delay time is given for each group. That is, the plurality of vibration elements constituting each group are connected in parallel at the time of transmission and at the time of reception, and constitute a single vibration part as a whole. If the width of such a vibrating portion is expanded in the beam scanning direction, side lobes are likely to occur as a result. On the other hand, as shown in FIG. 5, by appropriately setting the subarray pattern and the grouping pattern, it is possible to prevent the width of the vibrating portion from being apparently increased. That is, the above problem can be solved or reduced.

  FIG. 6 shows various subarray shapes. At the same time, a grouping pattern is also shown. The sub-array shape shown in (a) is the same as that shown in FIG. 4, and is adopted when the ultrasonic beam is scanned in the X direction. The subarray shape shown in (b) is the same as the subarray shape shown in (a) in its outer shape, but the grouping pattern in the inside is different. That is, five groups are arranged in the Y direction, and each group includes five vibration elements arranged in the X direction. This is employed when the ultrasonic beam is scanned in the Y direction. The subarray shape shown in (c) is the same as that shown in FIG. The subarray shape shown in (d) is obtained by shifting the subarray shape shown in (b) above by one step stepwise in the X direction for each stage in the Y direction. Such a subarray shape shown in (d) is suitable for scanning an ultrasonic beam in a right upward (downward left) direction toward the paper surface, similarly to the subarray shape shown in (c). The subarray shape shown in (e) has a form deformed in an oblique direction opposite to the subarray shape shown in (c). Such a subarray shape is suitable when an ultrasonic beam is scanned in the upward (leftward) direction toward the paper surface. The subarray shape shown in (f) has a form deformed in an oblique direction opposite to the subarray shape shown in (d). Similar to the subarray shape shown in (e), such a subarray shape is suitable when an ultrasonic beam is scanned in the upward (leftward) direction toward the paper surface.

  Of course, some of the subarray shapes shown in FIG. 6 are examples, and various other subarray shapes can be employed. That is, the subarray shape (and grouping pattern) is set so that side lobes are not generated as much as possible according to the beam forming conditions, particularly the beam scanning direction and focus depth, that is, the beam profile is improved. Is desirable. Note that, in order to simplify the configuration of the switching circuit 20 and simplify the control, the number of selectable subarray shapes may be limited to, for example, about four. In that case, subarray shapes such as (a), (b), (c) (or (d)), and (e) (or (f)) shown in FIG. 6 can be adopted.

  In FIG. 7, the fluctuation region R for a certain sub-array is indicated by a thick line. This variation region is defined by the largest outer edge of the region that the subarray can take when the shape of the subarray varies. That is, the fluctuation region R corresponds to a shape obtained by superimposing the shapes (a) to (f) shown in FIG. Here, reference numeral 100 denotes the most basic square subarray shape. For reference, the grouping pattern shown in FIG. 6C is shown. As can be understood from the form of the fluctuation region R shown in FIG. 7, a plurality of adjacent fluctuation regions R partially overlap each other. However, at the time of each transmission / reception, adjacent subarrays are closely connected to each other, and there is no overlap between them. The overlap will be described with reference to FIG.

  In FIG. 8, R1 to R4 represent four variable regions for four subarrays arranged vertically and horizontally. Incidentally, the fluctuation region R1 is represented by a solid line, the fluctuation region R2 is represented by a one-dot chain line, the fluctuation region R3 is represented by a two-dot chain line, and the fluctuation region R4 is represented by a broken line. Consider the vibration elements a to l in which the respective fluctuation regions partially overlap. The vibration elements a, b, and c belong to the fluctuation regions R1, R2, and R3, the vibration elements d, e, and f belong to the fluctuation regions R1, R2, and R4, and the vibration elements g, h, and i belong to the fluctuation regions R2, R3, and R3, respectively. The vibration elements j, k, and l belong to the fluctuation regions R1, R3, and R4. When attention is paid to the fluctuation region R1, the vibration elements a to f and j to l belong to the fluctuation region R1 (the vibration elements g to i do not belong), and the fluctuation region R1 further has its own characteristic. A plurality of vibration elements belong. Such a specific vibration element is composed of thirteen vibration elements, and they are densely packed in a rhombus centered on the central portion of the fluctuation region R1.

  FIG. 9 shows a comparative example. Here, the subarray shape is square, and the shape is unchanged. When scanning an ultrasonic beam in an oblique direction, for example, a grouping pattern as shown in FIG. 9 is set. This pattern is also unchanged. In this case, a plurality of vibration elements belonging to the group C exist in a multiple manner in the beam scanning direction (that is, the thickness of the vibration part C increases in the direction), and as a result, the profile of the ultrasonic beam Collapses and side lobes are likely to appear. In addition, it is difficult to make the distance between each vibration element constituting the group and the focus point uniform. On the other hand, according to the present embodiment, as will be described later, it is possible to eliminate or reduce the problem that occurs in the case shown in FIG. 9 by dynamically setting the subarray shape and the grouping pattern.

  FIG. 10 shows another example of the sub-array shape, in which one sub-array is constituted by 4 × 4 = 16 vibration elements. Sixteen vibration elements constituting each subarray are grouped into four groups. In FIG. 10, each group is given a different hatching to identify each group. The numerical values shown in FIG. 10 indicate the angle indicating the beam scanning direction (corresponding to the beam rotation angle around the vertical axis). Each grouping pattern shown in FIG. 10 is an exemplification, and in practice, various grouping patterns can be switched and set for each subarray shape according to transmission / reception conditions.

  As shown in FIG. 10, the beam profile can be improved in any beam scanning direction by adaptively changing each sub-array (simultaneously grouping pattern) according to the scanning direction of the ultrasonic beam. Even when any of the subarray shapes shown in FIG. 10 is employed, the plurality of subarrays can be closely connected to each other. For example, when the scanning direction is 45 degrees, as shown in FIG. 5, a plurality of subarrays are closely connected to each other without a gap. The same applies to other scanning angles.

  However, one or a plurality of vibrating elements that do not substantially function may exist at the end of the 2D array transducer. In the above embodiment, no gap is generated between the plurality of subarrays, but one or a plurality of substantially non-functional vibrating elements may exist between the subarrays. The sub-array variable setting method described above can be applied to, for example, a 1.5D array transducer in which a plurality of vibration elements are two-dimensionally arranged in addition to the 2D array transducer.

  With reference to FIG. 11 and FIG. 12, some other variations of the variable subarray shape and grouping pattern will be described. In FIG. 11, the subarray is composed of 4 × 4 vibrating elements.

  (A) shows the sub-array shape when the beam scanning direction is 45 degrees. Each group is composed of four vibration elements orthogonal to the beam scanning direction (thick arrow). Each group has the same shape. (B) shows the subarray shape when the beam scanning direction is an angle smaller than 45 degrees. The subarray shown in (B) has the same subarray shape (outer shape) as the subarray shown in (A), but the number of vibrating elements constituting the group is not the same among the plurality of groups, and is non-linear. Groups A, B, and C are included. (C) shows a subarray shape when the beam scanning direction is an angle larger than 45 degrees. The subarray shown in (C) has the same subarray shape as the subarray shown in (A), but the number of vibrating elements constituting the group is not the same among the plurality of groups, and the non-linear group B , C, D are included. (D) shows another subarray shape when the beam scanning direction is an angle smaller than 45 degrees. The subarray shown in (D) has a different shape from the subarray shown in (A). In (D), the group shape is the same among a plurality of groups. (E) shows the sub-array shape when the beam scanning direction is at a considerably small angle. The subarray shown in (E) has the same shape as the subarray shown in (D), but the number of vibration elements constituting the group is non-identical among a plurality of groups. Regardless of which subarray shape is employed, a plurality of subarrays can be closely connected to each other.

  As described above, a good ultrasonic beam can be formed by changing both the subarray pattern and the grouping according to the beam scanning direction and the like. In particular, the side lobes can be reduced more effectively by changing the number of vibrating elements constituting each group in accordance with the beam scanning direction.

  In the above embodiment, all of the plurality of vibration elements constituting each sub-array function as effective vibration elements (vibration elements that transmit and receive ultrasonic waves), but the beam scanning direction is a predetermined angle. In this case, one or a plurality of reactive vibration elements (vibration elements that do not transmit and receive ultrasonic waves) may be set in each subarray. This will be described with reference to FIG.

  In FIG. 12, the subarray is composed of 5 × 5 vibration elements. (A) shows the sub-array shape when the beam scanning direction is 45 degrees (the same as the patterns shown in FIGS. 5, 6B, and 7). Each group is constituted by a vibrating element row orthogonal to the beam scanning direction, and each vibrating element row is constituted by five vibrating elements. (B) shows the sub-array shape when the beam scanning direction is 30 degrees. (C) shows the sub-array shape when the beam scanning direction is 60 degrees. The subarrays shown in (B) and (C) have the same shape as the subarray shown in (A), but the subarrays shown in (B) and (C) have a plurality of non-linear groups. Have. (D) shows the sub-array shape when the beam scanning direction is 25 degrees. Here, the number of vibration elements constituting the group is the same and the shape is the same among the plurality of groups. On the other hand, (E) shows the subarray shape when the beam scanning direction is 15 degrees. The subarray shown in (E) has the same shape as the subarray shown in (D), but the grouping pattern is different between the two. (F) shows a sub-array shape pattern when the beam scanning direction is 20 degrees. The subarray shown in (F) has the same shape as the subarray shown in (D), but includes one reactive vibration element 102 in the subarray. (G) shows the sub-array shape when the beam scanning direction is 10 degrees. The subarray shown in (G) has the same shape as the subarray shown in (E), but includes four reactive vibration elements 102 in the subarray. As described above, the position and the number of the invalid vibration elements are variably set according to the beam scanning direction. Even when any of the subarray shape patterns shown in FIGS. 11 and 12 is employed, a plurality of subarrays can be closely connected to each other.

  Next, with reference to FIGS. 13 to 15, the control in consideration of the depth of the focus point will be described in detail.

  In this embodiment, the subarray shape is changed according to the beam address (particularly the beam scanning direction), and the grouping pattern is individually set for each subarray according to the beam address, the focus point depth, and the subarray position. I have to. That is, the subarray shape and the grouping pattern are optimized so that the distances between the respective vibration elements and the focus points are as uniform as possible for a plurality of vibration elements constituting each group.

  In FIG. 13, (A) shows a plane perpendicular to the array transducer surface (XZ plane), and (B) shows a horizontal plane (XY plane) parallel to the array transducer surface. The same applies to FIGS. 14 and 15. The X direction and the Y direction are arrangement directions of the vibration elements, the Z direction is a vertical direction, and is orthogonal to the X direction and the Y direction. Reference numeral 302 denotes a vertical axis that passes through the focus point F1 and is parallel to the Z axis. Reference numeral 304 indicates a transmission beam expressed with the center 308 of the array transducer 300 as the origin (starting point). The transmission beam 304 is directed to the focus point F1. Reference numeral 306 indicates an equidistant surface (wavefront as a spherical surface) viewed from the focus point F1. Ideally, a plurality of vibrators constituting each group are arranged on the equidistant surface. In (B), each cell in the array transducer 300 represents a sub-array 300A. Here, each subarray is composed of 4 × 4 vibrating elements (see reference numerals 310 to 320 described later).

  For example, as shown in FIG. 13, when the angle between the beam direction and the horizontal axis (here, the X axis) is small and the focus point F1 is set at a relatively shallow position, (B ), Different grouping patterns 310 to 320 are set for each subarray on the array transducer 300 according to the position of the subarray. Although the shape of each subarray is the same, a more appropriate grouping pattern is set for each subarray from the viewpoint of matching the phase in units of groups. That is, the form of each group and the number of constituent elements are optimized. From the above state, for example, as shown in FIG. 14, when the angle between the beam scanning direction and the horizontal axis slightly increases and the depth of the focus point F2 increases, as shown in FIG. In addition, grouping patterns 324 to 336 are set for each subarray according to the position. However, each subarray shape remains rectangular. Further, as shown in FIG. 15, from the above state, the depth of the focus point F3 is substantially maintained, while the angle in the beam scanning direction is increased so that it is approximately 45 with respect to the two horizontal axes perpendicular to each other. As shown in (B), the shape of each sub-array is changed from a rectangle to a parallelogram, and grouping patterns 342 to 354 are set for each sub-array according to the position at the same time. Is done. The switching of the subarray shape is performed according to the conditions shown in FIG. 10 or simplified conditions. For example, in FIG. 10, only the sub-array shapes indicated by 0 degree, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees may be used.

  As described above, the subarray shape is dynamically variably set according to the beam scanning. The grouping pattern is also dynamically variably set for each subarray on the premise of the set subarray shape according to the beam scanning. In that case, it is desirable to calculate in advance the best grouping pattern set for the entire array transducer for each combination of beam address and focus depth, and store the switching pattern for realizing it in the table. In other words, it is desirable that the optimum switching pattern be obtained instantaneously by referring to the table from the beam address and the depth of the focus point. As a result of such switching, a plurality of subarrays are formed on the array transducer, and at the same time, a grouping pattern is formed for each subarray. The beam scanning path in the three-dimensional space can be set arbitrarily. In general, a scanning surface is formed by scanning a beam in a first direction, and the scanning surface is scanned in a second direction.

  According to the above configuration, since the best grouping pattern is set for each sub-array, focusing on the positional relationship between the focus point and the plurality of vibration elements constituting the group, while realizing channel reduction, It is possible to improve the image quality of the ultrasonic image by improving the beam profile. In other words, good image quality can be obtained while simplifying the device configuration.

1 is a block diagram showing an overall configuration of an embodiment of an ultrasonic diagnostic apparatus according to the present invention. It is a block diagram which shows the structure of the transmission / reception part in the ultrasonic diagnosing device which concerns on this invention. It is a block diagram which shows the specific structural example of the transmission / reception module shown in FIG. It is a figure which shows an example of a subarray shape. It is a figure which shows the other example of a subarray shape. It is a figure for comparing and explaining a plurality of subarray shapes. It is a figure which shows the fluctuation | variation area | region which exists for every subarray. It is a figure for demonstrating the overlap between several fluctuation | variation area | regions. It is a figure for demonstrating a comparative example. It is a figure which shows other various subarray shapes. It is a figure for demonstrating embodiment with which the number of the vibration elements which comprise each group changes. It is a figure for demonstrating other embodiment from which the number of the vibration elements which comprise each group changes. It is a figure which shows the example of a grouping pattern setting in case a short-distance focus and a beam scanning angle are small. It is a figure which shows the grouping pattern setting example in case a beam scanning angle is small by a long distance focus. It is a figure which shows the grouping pattern setting example in case a beam scanning angle is large by a long distance focus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Probe head, 12 Apparatus main body, 16 2D array vibrator | oscillator, 20 Switching circuit, 24 Transmission / reception module, 26 Sub phasing addition circuit, 30 Main phasing addition circuit, 32 Transmission / reception control part, S subarray, R Fluctuation range, 310 320, 324-336, 342-354 Grouping pattern, 304, 322, 340 Transmit beam.

Claims (7)

An array transducer formed of a plurality of vibrating elements and forming an ultrasonic beam to be two-dimensionally scanned;
Switching means connected to the array transducer for setting a plurality of subarrays for the array transducer and setting a plurality of groups each composed of one or a plurality of vibration elements for each of the subarrays;
Transmitting means connected to the array transducer via the switching means and generating a group transmission signal for each group;
Receiving means connected to the array transducer via the switching means and processing a group reception signal of each group output from the switching means;
Including
The ultrasonic diagnostic apparatus, wherein the switching unit individually sets a grouping pattern for each of the subarrays based on at least a depth of a focus point. The ultrasonic diagnostic apparatus according to claim 1,
The ultrasonic diagnostic apparatus, wherein the switching unit dynamically switches a grouping pattern set for each of the subarrays when scanning the ultrasonic beam. The ultrasonic diagnostic apparatus according to claim 1,
The ultrasonic diagnostic apparatus according to claim 1, wherein the switching unit further sets a grouping pattern corresponding to the position of each subarray based on a beam address. The apparatus of claim 1.
The switching means includes
A function of distributing and outputting the group transmission signal to a plurality of vibration elements constituting a corresponding group;
A function of generating a group reception signal by adding a plurality of reception signals from a plurality of vibration elements in units of groups;
An ultrasonic diagnostic apparatus comprising: An array transducer formed of a plurality of vibrating elements and forming an ultrasonic beam to be two-dimensionally scanned;
A plurality of sub-arrays are set for the array transducer according to the beam address and the depth of the focus point, and each of the sub-arrays is set to 1 or Switching means for setting a plurality of groups composed of a plurality of vibration elements;
Transmitting means connected to the array transducer via the switching means and generating a group transmission signal for each group;
Receiving means connected to the array transducer via the switching means and processing a group reception signal of each group output from the switching means;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 5.
The switching means dynamically switches a subarray shape set for each subarray and dynamically switches a grouping pattern set for each subarray when scanning the ultrasonic beam. A characteristic ultrasonic diagnostic apparatus. The apparatus of claim 6.
The ultrasonic diagnostic apparatus, wherein the switching means switches a subarray shape set for each subarray according to a beam scanning direction on a horizontal plane orthogonal to a vertical central axis of the array transducer.

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