JP4688893B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a reception beam forming technique.

  In ultrasonic diagnosis, an ultrasonic beam is electronically scanned, thereby forming a scanning surface. The ultrasonic beam corresponds to a transmission / reception combined beam obtained by combining a transmission beam and a reception beam. Usually, the center line of the transmit beam and the center line of the receive beam are both straight lines, and they coincide completely at the same position. Therefore, the center line of the transmission / reception combined beam is also a straight line.

  In recent years, in order to increase the frame rate or volume rate, multi-directional simultaneous reception technology for simultaneously forming a plurality of reception beams per transmission beam has been utilized. In this case, for example, two reception beams are formed on both sides of one transmission beam. That is, the positions of the center line of the transmission beam and the center line of each reception beam are inconsistent. Since the transmit / receive combined beam is defined by the product of the transmit beam profile and the receive beam profile at each depth position, a pair of transmit / receive combined beams is formed on both sides of the transmit beam. Specifically, the center line of each transmission / reception combined beam is set between the center line of the transmission beam and the center line of each reception beam.

  The reception beam is formed by reception dynamic focus that continuously moves the reception focus point in the depth direction. That is, the beam width is reduced at each depth position on the reception beam. On the other hand, for the transmission beam, the beam width is narrowed in the vicinity of the fixedly set transmission focus point, but the beam width increases before and after that. Therefore, under the influence, the center line of the transmission / reception combined beam does not become a straight line, but has a non-linear shape, particularly depending on the characteristics (profile) of the transmission beam at each depth position. For example, the shape is curved near the transmission focus point.

  If mapping of each echo data is performed without dealing with the distortion generated in such a transmission / reception combined beam, the image quality of the tomographic image formed thereby is lowered. That is, the organ image in the tomographic image is distorted.

  By the way, in ultrasonic diagnosis, real-time property and image quality are emphasized. However, for example, when the number of ultrasonic beams constituting one frame is reduced, the image quality (particularly resolution) is lowered, and when the number of ultrasonic beams constituting one frame is increased, the frame rate (including a three-dimensional volume rate is included). The same). Therefore, it is desired to improve both the frame rate and the image quality. In particular, when electronic sector scanning is performed, the beam interval increases as the depth increases, and the data sampling interval becomes coarse in the azimuth direction (beam scanning direction). Of course, in forming an image, an interpolation technique is applied and data is supplemented between the beams. However, with such an interpolation technique, it is difficult to sufficiently improve the image quality even if the apparent resolution can be improved.

  Patent Document 1 discloses a technique for forming a plurality of interpolated beams at equal intervals during simultaneous multi-directional reception. Patent Document 2 discloses a technique in which two transmission beams are simultaneously formed at the time of transmission and two reception beams are simultaneously formed at the same position as the two transmission beams at the time of reception. Patent Document 3 discloses a technique for linearizing a transmission / reception integrated beam.

US Pat. No. 6,447,452 US Pat. No. 6,282,963 JP-A-2-206451

  An object of the present invention is to provide a new receive beamforming technique or a new receive dynamic focus technique.

  Another object of the present invention is to improve the quality of an ultrasonic image without sacrificing the volume rate.

  Another object of the present invention is to enable more significant data to be collected by one transmission / reception of ultrasonic waves.

(1) The present invention provides an array transducer having a plurality of transducer elements, a transmission beam former that supplies a plurality of transmission signals subjected to delay processing to the array transducer, thereby forming a transmission beam, A reception beamformer for performing delay addition processing on a plurality of reception signals from the array transducer, and forming a reception beam by executing reception dynamic focus for continuously moving a reception focus point in a depth direction And a control means for controlling the shape of the movement locus of the reception focus point in the reception dynamic focus.

  According to the above configuration, when the reception dynamic focus is performed to form the reception beam, the shape of the movement locus of the reception focus point can be a desired shape other than a straight line. Such movement trajectory control can be used for various purposes, for example, correction of distortion generated in a transmission / reception synthetic beam (improvement of distortion of an image in an ultrasonic image), the number of acquired data per unit area or unit volume. It can be used for purposes such as increasing, improving the frame rate or volume rate. The present invention can be applied to the case where the ultrasonic beam is deflected and scanned, and the case where the ultrasonic beam is linearly scanned, and can also be applied to two-dimensional and three-dimensional measurements. The above control means may exist inside the reception beamformer or may exist outside the reception beamformer.

  Preferably, the control means makes at least a part of the shape in the movement locus non-linear. Desirably, the said control means sets the shape of the said movement locus | trajectory according to the change to the depth direction of a transmission beam profile.

  Preferably, the reception beam is formed in a relation adjacent to the transmission beam, and a movement locus for the reception beam is curved in a direction away from the center line of the transmission beam in the vicinity of the transmission focus point on the transmission beam. Has a shape. Preferably, the shape of the movement locus is set according to a condition in which a center line of a transmission / reception combined beam obtained by combining the transmission beam and the reception beam forms a substantially straight line. According to this configuration, it is possible to improve the distortion problem occurring in the transmission / reception combined beam.

  Desirably, the said control means changes the shape of the said movement locus | trajectory according to transmission / reception conditions. Preferably, the transmission / reception condition includes a beam deflection angle. In addition, the transmission / reception conditions include an operation mode, a diagnostic distance, a reception beam characteristic, a transmission beam characteristic, and the like.

  Preferably, the control means has a table in which delay data for each depth for the delay addition process is stored in advance. Preferably, the control means includes a coordinate calculation unit that calculates coordinates of a reception focus point in accordance with transmission / reception conditions, and a delay data calculation unit that calculates delay data for the delay addition processing based on the coordinates of the reception focus point. ,including. The delay data is data representing a delay time given to each received signal. Based on the result obtained by dividing the distance from the reception focus point to each vibration element by the sound velocity of the ultrasonic wave, the delay time for each reception signal is calculated.

(2) The present invention has a plurality of vibration elements in an ultrasonic diagnostic apparatus in which a reception beam set composed of a plurality of reception beams having a predetermined positional relationship with each transmission beam is formed. An array transducer, a plurality of transmission signals subjected to delay processing to the array transducer, and a transmission beam former that forms the transmission beam, and a plurality of reception signals from the array transducer are delayed A means for performing addition processing, including a reception beam former that performs reception dynamic focus for continuously moving the reception focus point in the depth direction for each reception beam forming the reception beam set. And a control means for controlling the shape of the movement locus of the reception focus point for each reception beam constituting the reception beam set. An ultrasonic diagnostic apparatus characterized.

  According to the above configuration, when performing multi-directional simultaneous reception, it is possible to improve the problem of distortion generated in each transmission / reception combined beam depending on the characteristics of the transmission beam. Note that the number of reception beams formed simultaneously is, for example, 2 to 16, and they are linearly arranged or constitute a two-dimensional array. Normally, the phasing addition processing is performed independently for each reception beam, and a number of reception processing systems corresponding to the number of reception beams operate in parallel.

  Desirably, the said control means determines the shape of the said movement locus so that the centerline of a transmission / reception synthetic beam may become a straight line for every receiving beam which comprises the said receiving beam set.

(3) Preferably, in the ultrasonic diagnostic apparatus in which the ultrasonic diagnostic apparatus forms a scanning surface as a two-dimensional space by scanning the transmission beam and the reception beam, an array transducer having a plurality of vibration elements; A transmission beam former that supplies a plurality of transmission signals subjected to delay processing to the array transducer, thereby forming a transmission beam, and a means for performing delay addition processing on the plurality of reception signals from the array transducer. A reception beamformer that forms a reception beam by executing a reception dynamic focus that continuously moves the reception focus point in the depth direction, and further scans the shape of the movement locus of the reception focus point. Control means for changing two-dimensionally in the plane is included.

  According to the above configuration, it is possible to give a two-dimensional change to the movement locus of the reception focus. Therefore, it is desirable to determine the shape of the movement locus according to the purpose.

  Preferably, all or a part of the movement trajectory has a zigzag shape. Desirably, the greater the reception focus point, the larger the zigzag swing width.

  The zigzag shape includes a snake shape and a sine wave shape in addition to the left and right folded shape. In any case, it is possible to capture data from a large number of points spread in the horizontal direction rather than on one line (however, the depth of each point is different from each other) in one reception. The advantage of improved image quality or improved frame rate can be obtained. When electronic sector scanning is performed, it is possible to improve the image quality particularly in a deep part.

(4) According to the present invention, in an ultrasonic diagnostic apparatus in which a three-dimensional space is formed by scanning a transmission beam and a reception beam, an array transducer having a plurality of transducer elements and a delay process for the array transducer A transmission beam former for supplying a plurality of transmitted signals and thereby forming a transmission beam, and means for delay-adding a plurality of reception signals from the array transducer, wherein the reception focus point is in the depth direction A receive beamformer that forms a receive beam by executing a receive dynamic focus that continuously moves to a three-dimensional space in the three-dimensional space. It is characterized by including the control means to change.

  According to the above configuration, it is possible to give a three-dimensional change to the movement locus of the reception focus. Therefore, it is desirable to determine the shape of the movement locus according to the purpose.

  Preferably, all or a part of the movement locus has a spiral shape. Desirably, the deeper the reception focus point, the larger the diameter of the spiral shape.

  The spiral shape includes a polygon such as a quadrangle as well as a circular cross section. Even in the case of performing three-dimensional measurement, the movement trajectory can be the above zigzag shape.

(5) The present invention realizes non-linear type or arbitrary path type reception dynamic focus. In this regard, various applications are possible and combinations with various other techniques are possible. With respect to the data sampling rate, it is desirable to increase the speed as required, or the data sampling rate may be varied continuously or stepwise in the depth direction. Data mapping or coordinate transformation for image construction is performed based on the spatial coordinates of each data, and at that time, it is desirable to perform interpolation processing as in the prior art. When inter-frame correlation processing is performed, the pattern of the movement trajectory array may be alternately switched between frames. Further, not only the luminance image but also the Doppler information may be imaged.

  As described above, according to the present invention, various advantages as described above can be obtained by the new reception dynamic focus technique.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a typical reception dynamic focus performed conventionally. FIG. 2 shows a new reception dynamic focus according to the present embodiment.

  1 and 2, the array transducer 10 is composed of a plurality of vibration elements. As is well known, a transmission beam is formed by supplying a plurality of transmission signals to a plurality of vibration elements with a predetermined delay relationship, while a predetermined delay is applied to a plurality of reception signals from the plurality of vibration elements. Delay processing is performed with relation, and a plurality of reception signals after the delay are added to form a reception beam. When a transmission beam is formed, basically one transmission focus point is formed per transmission. On the other hand, according to the reception dynamic focus, the reception focus point can be continuously moved in the deep direction from the vicinity of the array transducer 10 according to the sound velocity. That is, the reception focus point can be scanned in the depth direction by matching the focus point with the reception point in accordance with the scanning of the reception point in the depth direction. Incidentally, with such reception dynamic focus, normally, variable aperture control is performed to widen the reception aperture continuously or stepwise.

  In FIG. 1, reference numeral 100 represents a center line of a reception beam formed by reception dynamic focus, and the center line 100 corresponds to a movement locus of the reception focus point. In the figure, an arrow is drawn in the direction in which the reflected wave returns, but the reception focus point moves in the deep direction, that is, the z direction from the vicinity of the array transducer.

  In FIG. 1, reference numeral 102 indicates a shallow reception focus point, reference numeral 104 indicates an intermediate reception focus point, and reference numeral 106 indicates a deep reception focus point. When each reception focus point is formed, the received signals from a plurality of vibration elements existing in the reception aperture are phased and added.

  In the typical example shown in FIG. 1, the center line 100 of the reception beam forms a straight line, and this is the same even in the case of electronic sector scanning, electronic linear scanning, or other electronic scanning. That is, the conventional apparatus does not have a function of freely deforming the center line of the received beam in the horizontal direction (direction perpendicular to the depth direction).

  According to the present embodiment, as shown in FIG. 2, the center line (that is, the movement locus of the reception focus point) 110 can be formed into a non-linear shape, in other words, the reception focus point at each depth position. It is possible to individually and arbitrarily determine the horizontal coordinates. Even when the horizontal position of the reception focus point at each depth is set randomly for each reception beam, the movement locus of the reception focus point exists.

  In FIG. 2, reference numeral 112 denotes a shallow reception focus point, reference numeral 114 denotes an intermediate reception focus point, and reference numeral 116 denotes a deep reception focus point. However, they are not aligned on a straight line, and their horizontal coordinates are dynamically changed. Of course, in order to obtain a certain degree of reception sensitivity, it is necessary to set each reception focus point (each reception point) within the range of the spread of the transmission beam. Accordingly, it is possible to set the reception focus point within the beam width of such a transmission beam, and conversely, the spread (beam pattern) of the transmission beam is determined so as to cover the reception focus point of each depth. You can also

  As described above, according to the new reception dynamic focus technology according to the present embodiment, the movement locus of the reception focus point can be formed into a desired shape, and thus the movement locus is a straight line uniformly. Can solve the problem that occurs. Further, when the number of beams is maintained, the advantage of improving the resolution can be obtained, and when the resolution is maintained, the advantage of improving the frame rate by reducing the number of beams can be obtained.

  Incidentally, on the center lines 100 and 110 shown in FIGS. 1 and 2, sampling points (reception points) are set at certain depth intervals, and data is sampled at each sampling point. The sampling interval may be fixed along the depth direction, or may be varied continuously or stepwise.

  Next, an application example of the new reception dynamic focus technique will be described.

  FIG. 3 shows a beam profile at a certain depth position. The horizontal axis represents the beam orientation θ, and the vertical axis represents power.

  In this example, the transmission beam profile 122 has a characteristic of spreading symmetrically about the center 120 of the transmission beam. On the other hand, the center 124 of the received beam is set at a position displaced from the center 120 by a certain distance, and a received beam profile 126 that spreads left and right around the center 124 is formed. When such a transmission beam profile 122 and a reception beam profile 126 exist, a transmission / reception synthesis profile as indicated by reference numeral 130 is constructed. The center of the transmission / reception synthesis profile 130 is indicated by reference numeral 128. As is clear from the above description, when the center 124 of the reception beam is set at a position shifted from the center 120 of the transmission beam, the center 128 of the transmission and reception combined beam is the center of the transmission beam 120 and the center 124 of the reception beam. They do not match any of them and are formed between them. Of course, the form and placement of the transmit / receive combined beam depend on the form and position of the transmit beam profile and the receive beam profile.

  The phenomenon described with reference to FIG. 3 causes a problem in the case of multidirectional simultaneous reception. This is illustrated in FIG.

  In FIG. 4, reference numeral 132 denotes the center line of the transmission beam. On the center line 132, the transmission focus point 134 is set to a certain depth. In general, the transmission beam is most focused in the vicinity of the transmission focus point 134 and has a form spreading before and after the transmission focus point 134. A pair of receive beams are formed on both sides of the center line 132 of the transmit beam. Center lines 136 and 138 of each reception beam are straight lines. However, as described above, since the beam width of the transmission beam varies for each depth, the center line of the transmission / reception combined beam draws a curve as indicated by reference numerals 140 and 142. That is, as indicated by reference numerals 141 and 143, in the vicinity of the transmission focus point 134, the center lines 140 and 142 of each transmission / reception combined beam are drawn toward the center line 132 side of the transmission beam, and the portion is curved.

  The above phenomenon will be further examined with reference to FIG. In FIG. 5, (A) shows each beam profile at a shallow depth position, (B) shows each beam profile at an intermediate depth position near the transmission focus point, and (C). Each beam profile at a deep position is shown in FIG.

  The beam profiles 144A, 144B, and 144C of the transmission beam vary depending on the depth direction. In particular, as shown in (B), the profile is considerably converged in the vicinity of the transmission focus point.

  Reference numeral 146 indicates the center of the transmission beam, and a pair of reception beams are formed on both sides of the center 146. The centers of the pair of reception beams are denoted by reference numerals 150 and 152. As indicated by reference numerals 148A, 148B, and 148C, the reception beam basically has a similar profile over the depth direction. The center of the profile always coincides with the position indicated by reference numerals 150 and 152. This means that the movement locus of the reception focus point for each reception beam is a straight line.

  Therefore, as indicated by reference numerals 150A, 150B, and 150C, the position of the reception focus point at each depth in the azimuth direction varies depending on the depth direction. This is a phenomenon as shown in FIG.

  In spite of the above phenomenon, if the echo data string corresponding to the received beam is linearly mapped in the digital scan converter, for example, when a tomographic image is formed, the organ image is distorted.

  Therefore, in the present embodiment, as shown in FIGS. 6 and 7, the new reception dynamic focus technique described above is applied to directly correct the distortion generated in the center line of the transmission / reception combined beam, thereby correcting the image. Eliminate distortion.

  In FIG. 6, the center lines 152 and 154 of the two received beams are curved in whole or in part so as to cancel the distortion generated in the center lines of the transmitted and received combined beams. Specifically, the center lines 152 and 154 bulge and curve in a direction away from the center line 132 of the transmission beam in the vicinity of the transmission focus point 134. As a result, when transmission / reception combined beams are formed for the respective reception beams, the center lines 156 and 158 have a straight line or a shape close to a straight line. In short, considering the depth dependency of the transmit beam profile (and if necessary, the depth dependency of the receive beam profile) The movement trajectory is set. If the distortion problem is dealt with under the transmission / reception conditions, it is possible to simply perform coordinate conversion or echo data mapping on the assumption that echo data sequences corresponding to reception beams are linearly aligned in real space. Reference numerals 153 and 155 represent distortion correcting actions.

  FIG. 7 shows a beam profile at each depth under the transmission / reception conditions shown in FIG. (A) shows a beam profile at a shallow position, (B) shows each beam profile at an intermediate depth position near the transmission focus point, and (C) shows each beam profile at a deep position. Has been.

  The beam profiles 144A, 144B, and 144C of the transmission beam vary depending on the depth direction. Reference numeral 146 indicates the center of the transmission beam, and a pair of reception beams are formed on both sides of the center 146. However, at each depth position, the center of the received beam varies in the azimuth direction, which is the horizontal axis. Specifically, as understood from the comparison of (A), (B), and (C), the center 184A of the received beam profile 182A at the shallow position, the center 184B of the received beam profile 182B at the intermediate position, the deep position The center 184C of the received beam profile 182C is not the same in the azimuth direction, which is the horizontal axis, and is set individually for each depth. In particular, in the middle position, the center 184B is more than the center 146 of the transmitted beam. Shifting away. As described above, such a sound field formation cancels the positional variation in the azimuth direction that occurs at the centers 186A, 186B, and 186C of the transmitted and received combined beams, and as a result, it is possible to improve image distortion. .

  Although the above description is based on the assumption that the ultrasonic beam is not deflected, the same control as described above can be performed when the ultrasonic beam is deflected at an angle θ. This will be described with reference to FIGS.

  FIG. 8 shows a conventional problem when the ultrasonic beam is deflected. Basically, a problem similar to the problem described with reference to FIG. 4 occurs. More specifically, when the transmission focus point 162 is set on the transmission beam center line 160, the pair of reception beam center lines 164 and 166 formed on both sides of the transmission beam are simply straight lines. Then, the center lines 168 and 170 of the transmission / reception combined beams are distorted as shown in the figure. Reference numerals 165 and 166 denote distortion amounts in the vicinity of the transmission focus point 162, and the distortion amount is larger on the left side than on the right side. This is due to the beam profile being asymmetric with respect to its center.

  On the other hand, as shown in FIG. 9, by applying the new reception dynamic focus technology according to the present embodiment and optimizing the movement locus of the reception focus point, that is, the shapes of the center lines 172 and 174 of the reception beam, The shape of the center lines 178 and 180 of the combined beam is substantially a straight line. As indicated by reference numerals 173 and 175, the amount of swelling of the decimal beam center lines 172 and 174 near the transmission focus point 162 is larger on the left side than on the right side.

  In the above description, two reception beams are formed per one transmission beam. Of course, the above principle is applied even when a larger number of reception beams are formed per one transmission beam. Is possible.

  The method of using the reception dynamic focus technology described above is, of course, an example, and in various situations where it is desired to freely set the shape of the center line of the reception beam, that is, the shape of the movement locus of the reception focus point. Technology can be used.

  FIG. 10 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to this embodiment. The array transducer 10 is provided in an ultrasonic probe (not shown). The ultrasonic probe is used in contact with the body surface or inserted into a body cavity. The array transducer 10 includes a plurality of vibration elements 12. These vibration elements 12 are arranged on a straight line or in an arc shape, for example. Of course, the array transducer 10 may be a 2D array transducer instead of a 1D array transducer. An ultrasonic beam is formed by the array transducer 10, and the ultrasonic beam is electronically scanned. In this case, examples of the electronic scanning method include electronic linear scanning and electronic sector scanning.

  The transmission beamformer includes a transmission unit 14 and a transmission control unit 18. The transmission unit 14 includes a transmission circuit 30 for each vibration element 12, that is, for each channel. The transmission circuit 30 includes, for example, a waveform generator, a D / A converter, an amplifier, and the like. The transmission control unit 18 controls the operation of each transmission circuit 30. Specifically, the delay amount for each transmission signal is set according to the delay data output from the transmission focus controller 32. Generally, the delay amount of the transmission signal is set by adjusting the output start timing of the read signal for the waveform generator included in the transmission circuit 30. A phase shifter or the like may be provided at the subsequent stage of such a waveform generator to adjust the delay amount more finely. The transmission control unit 18 is controlled by the main control unit 22.

  The reception beamformer includes a reception unit 16 and a reception control unit 20. The receiving unit 16 has a plurality of receiving circuits 34 provided for each vibration element 12, that is, for each channel. Each receiving circuit 34 has a preamplifier, an A / D converter, a delay circuit, and the like. Then, the delayed received signals output from the receiving circuits 34 are added by the adder 40. That is, a delay addition process is performed on a plurality of received signals.

  The reception control unit 20 includes a reception dynamic focus controller 36. The reception dynamic focus controller 36 has a function of freely setting the shape of the movement locus of the reception focus point as shown in FIG. Specifically, individual delay data (delay amount) given to each receiving circuit 34 is manipulated so that such a movement trajectory is realized. Specific contents of the reception dynamic focus controller will be described later with reference to FIGS. The reception control unit 20 is controlled by the main control unit 22.

  The signal processing unit 26 receives the reception signal after the phasing addition processing output from the reception unit 16. The signal processing unit 26 performs necessary signal processing on the received signal. For example, when forming a B-mode image, noise removal, logarithmic conversion processing, and the like are executed. Of course, the signal processing unit 26 may include an orthogonal detection circuit for processing Doppler information, an autocorrelation calculator, and the like. Further, signal processing for forming a three-dimensional image may be performed.

  The DSC (digital scan converter) 28 performs coordinate conversion from the transmission / reception coordinate system to the display coordinate system for each data. In the coordinate conversion, an interpolation process is also executed as in the prior art. Further, the DSC 28 performs inter-line correlation processing, inter-frame correlation processing, and the like.

  In the coordinate conversion processing of the DSC 28, when each echo data is sequentially mapped on the frame memory, the spatial coordinates of each echo data are required. Information indicating the spatial coordinates is received by the reception dynamic focus controller 36 or the main control unit 22. To DSC28.

  When a certain deflection angle θ is set for the received beam, one echo data string corresponding to the deflection angle θ is acquired by one transmission / reception wave. Then, the spatial coordinates of each echo data constituting it are generally described by a deflection angle θ and a depth r. That is, the same θ is given to each echo data constituting the echo data string. In the present embodiment, even when the same deflection angle is uniformly given to each echo data constituting the echo data string, the center line of the transmission / reception combined beam substantially draws a straight line. The problem of distortion is improved.

  In the case where a plurality of reception apertures are set on the array transducer 10 and a plurality of reception beams are simultaneously formed, the spatial coordinates of the echo data string for each reception beam depend on the center position of the corresponding reception aperture. . Even in such a case, as described above, it is possible to perform mapping of the echo data string on the assumption that the echo data string is linearly arranged. Therefore, coordinate conversion can be performed with the same amount of calculation as the conventional apparatus.

  The image data of the ultrasonic image formed by the DSC 28 is output to the display unit 29, and the ultrasonic image is displayed on the display screen of the display unit.

  The main control unit 22 is configured by a CPU, an operation program, and the like, and performs operation control of each component included in the ultrasonic diagnostic apparatus. In particular, when the reception dynamic focus controller 36 calculates the coordinates of the reception focus point at each depth position, information necessary for this is sent to the reception dynamic focus controller 36.

  The operation panel 24 is composed of a keyboard, a trackball, and the like. By using the operation panel 24, the user can input information and switch operations.

  FIG. 11 shows a configuration example of the reception dynamic focus controller 36 shown in FIG. In the example shown in FIG. 11, the spatial coordinates of each reception focus point are calculated by the main control unit 22, and the calculation result is stored in advance in a delay amount table 42 that constitutes the reception dynamic focus controller 36. Accordingly, the delay data is sequentially output to the receiving circuit 34 for each reception focus point, thereby performing reception dynamic focus.

  FIG. 12 shows another configuration example of the reception dynamic focus controller 36. In the example shown in FIG. 11, necessary delay data is calculated by the main control unit, but in the example shown in FIG. 12, delay data is calculated inside the reception dynamic focus controller 36.

  The focus coordinate calculation unit 44 receives information necessary for calculating the coordinates of the reception focus point from the main control unit 22. Examples of the information include probe type information, information on a transmission beam profile, information on a reception beam profile, and the like.

  The focus coordinate calculation unit 44 calculates the spatial coordinates for each reception focus point in each reception beam, and sends the calculation result to the delay amount calculation unit 46. When the spatial coordinates of the reception focus point are given, the delay amount calculation unit 46 calculates delay data for realizing the reception focus at the spatial coordinates. That is, the delay amount for each reception channel is calculated. The calculation result is registered in the memory 48. The delay data is sequentially output from the memory 48 to the receiving circuit.

  In the configuration shown in FIG. 10, when a plurality of reception beams are simultaneously formed for one transmission beam, it is desirable to provide phasing addition circuits corresponding to the number of reception beams.

  Next, another usage method of the above-described new reception dynamic focus technique will be exemplified.

  FIG. 13 shows a scanning plane 200 formed by scanning an ultrasonic beam with an electronic sector. A reception beam is formed for each direction, and the center line of each reception beam, that is, the movement locus of the reception focus point, has a zigzag shape as indicated by reference numeral 204. Incidentally, reference numeral 202 indicates the central axis of the received beam. Specifically, the movement trajectory 204 is expanded from the transmission / reception origin to the deepest position while being reversed left and right and increasing its amplitude, thereby forming a single received beam in a more horizontal direction. It is possible to set more sample points over a wide range. In the example shown in FIG. 13, the movement trajectories of adjacent reception beams mesh with each other, and formation of such an engagement pattern can form a uniform and high-density data array space. Of course, instead of a completely bent zigzag shape as shown in FIG. 13, a shape like a snake line or a shape like a sine wave may be adopted.

  FIG. 14 shows the movement locus 204 of one reception beam shown in FIG. Here, a black circle 206 indicates a sampling point. As shown in the figure, by setting each sample point 206 at a fixed interval or variable interval in the depth direction while performing a zigzag scan, more sample points can be arranged spatially, and as a result, There is an advantage that the spatial resolution can be improved.

  Of course, when setting more sample points than in the past, it is desirable to increase the sampling rate of A / D conversion for the received signal, for example, by setting a sampling frequency of several tens to several hundreds of MHz. Also good. Further, the sampling frequency may be changed continuously or stepwise over the depth direction.

Further, when the ultrasonic beam is scanned two-dimensionally, that is, when three-dimensional measurement is performed, as shown in FIG. You may make it do. That is, a movement trajectory having a spiral shape is set. A plurality of sampling points 212 are set on such a movement trajectory 210. Since the movement trajectory 210 advances in the depth direction, the depths of the plurality of sampling points 212 are different from each other as shown in the figure. In this case, the turning size is gradually increased over the depth direction.

  Further, as shown in FIG. 16, when electronic linear scanning is performed, similarly to the above, zigzag scanning is performed so that a plurality of echo data sequences are substantially simultaneously formed by one reception beam. May be. Reference numeral 218 represents a sampling point, and reference numeral 214 represents the central axis of the received beam. Also in the example shown in FIG. 16, the movement trajectories are alternately meshed with adjacent reception beams, and this has the advantage that the spatial resolution can be greatly improved as described above.

  Various modifications can be considered for the various embodiments described above. For example, in the above-described embodiment, the tissue luminance image is configured. However, a two-dimensional or three-dimensional blood flow image may be constructed using the Doppler method. In the above-described embodiment, the transmission beam has one-stage focus, but multi-stage transmission focus may be applied. In this case, the movement locus control of the reception focus point is performed for each transmission beam. Also, when the above zigzag scan or the like is performed, there is a concern that the end of the scan space will have a jagged shape, but edge processing is applied to make it a smooth edge. May be. Further, the zigzag scan pattern as shown in FIG. 13 may be alternately switched between frames.

It is a figure which shows a linear receiving dynamic focus. It is a figure which shows the reception dynamic focus which concerns on this invention. It is a figure which shows each beam profile. It is a figure for demonstrating the problem of the distortion which arises in a transmission / reception synthetic beam. It is a figure for demonstrating each beam profile in each depth position conventionally. It is a figure for demonstrating the effect in case the receiving dynamic focus which concerns on this invention is applied. In this invention, it is a figure for demonstrating each beam profile in each depth position. It is a figure for demonstrating the problem of distortion of a transmission / reception synthetic | combination beam at the time of deflecting an ultrasonic beam. It is a figure for demonstrating improvement of the problem of said distortion in the case of deflecting an ultrasonic beam. 1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present embodiment. It is a figure for demonstrating the structural example of a reception dynamic focus controller. It is a figure for demonstrating the other structural example of a receiving dynamic focus controller. It is a figure for demonstrating a zigzag scan. It is an enlarged view of a zigzag scan. It is a figure for demonstrating a spiral scan. It is a figure for demonstrating other zigzag scanning.

Explanation of symbols

  10 array transducer, 14 transmission unit, 16 reception unit, 18 transmission control unit, 20 reception control unit, 32 transmission focus controller, 36 reception dynamic focus controller.

Claims (3)

In an ultrasonic diagnostic apparatus in which a three-dimensional space is formed by scanning a transmission beam and a reception beam,
An array vibrator having a plurality of vibration elements;
A transmission beam former that supplies a plurality of delayed transmission signals to the array transducer, thereby forming a transmission beam;
A reception beamformer for performing delay addition processing on a plurality of reception signals from the array transducer, and forming a reception beam by executing reception dynamic focus for continuously moving a reception focus point in a depth direction When,
Including
And a control means for three-dimensionally changing the shape of the movement locus of the reception focus point in the three-dimensional space in the reception dynamic focus ,
A plurality of sampling points are set at different depths on the movement locus,
An ultrasonic diagnostic apparatus, wherein all or a part of the movement locus has a spiral shape turning around a central axis of the transmission beam . The apparatus of claim 1 .
The ultrasonic diagnostic apparatus characterized in that the spiral shape diameter increases as the reception focus point becomes deeper. The apparatus of claim 1.
The ultrasonic diagnostic apparatus, wherein a sampling rate for the data after the delay addition process is varied continuously or stepwise in the depth direction.

Images