JP2004321274A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer ultrasonic diagnostic apparatus which can faithfully express the spatial organization of in-vivo tissue. <P>SOLUTION: In a scan layer 300, when two receiving beams are formed on either side of a transmitting beam, two transmission and reception synthesis beam central lines 306 are established on either side of a transmitting beam central line 304. Those transmission and reception synthesis beam central lines 306 have a profile which is especially curved with fluctuation in the depth orientation of a transmitting beam profile. In performing mapping of each data in DSC, the mapping is performed with being faithful to the profile of the transmission and reception synthesis beam central line 306. Thus, a configuration for calculating as a transmission and reception wave coordinate a coordinate of the transmission and reception synthesis beam center in each depth is prepared. Fairing treatment which changes the end side of an image into a straight line may be performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus in which a plurality of reception beams are simultaneously formed for one transmission beam.
[0002]
[Prior art]
In ultrasonic diagnosis, an ultrasonic beam is electronically scanned to form a scanning surface. The ultrasonic beam corresponds to a transmission / reception combined beam obtained by combining a transmission beam and a reception beam, and usually, the position of the transmission beam (the center line of the transmission beam) and the position of the reception beam (the center line of the reception beam) are the same. In this case, the center line of the ultrasonic beam is a straight line, and when forming an ultrasonic image, the scan converter linearly maps a data sequence corresponding to the ultrasonic beam in the display space. However, interpolation processing is generally performed at the time of coordinate conversion due to the difference between the transmission / reception wave coordinate system and the display coordinate system.
[0003]
In recent years, in order to increase the frame rate or the volume rate, a multi-directional simultaneous reception technique for simultaneously forming a plurality of reception beams per transmission beam has been used. In this case, for example, two reception beams are formed on both sides of one transmission beam. That is, the position of the transmission beam does not match the position of each reception beam. The transmit / receive combined beam depends on the transmit beam profile and the receive beam profile at each depth, and a transmit / receive combined beam is formed between the transmit beam and one receive beam and between the transmit beam and the other receive beam, respectively. Is done.
[0004]
Patent Literature 1 discloses a technique of forming a plurality of interpolated beams at equal intervals during simultaneous multidirectional reception. Patent Document 2 discloses a technique in which two transmission beams are formed simultaneously at the time of transmission, and two reception beams are formed simultaneously at the same position as the two transmission beams at the time of reception.
[0005]
[Patent Document 1]
U.S. Pat. No. 6,447,452
[Patent Document 2]
U.S. Pat. No. 6,282,963
[0006]
[Problems to be solved by the invention]
In the above case, even though the center of the combined transmitted / received beam does not coincide with the center of each received beam and is closer to the transmitted beam, simply mapping the data sequence linearly during the formation of the ultrasonic image, There is a problem that the image is distorted.
[0007]
Consider the above problem. Since the transmission beam profile fluctuates greatly depending on the depth, the center line of the transmission / reception combined beam is also affected by the influence and becomes not linear but non-linear. Normally, the transmitted / received combined beam centerline is distorted in the vicinity of the transmission focus point so as to be drawn closest to the transmission beam centerline (the phenomenon is also shown in FIG. 9 of Patent Document 2). In spite of such a distortion problem, each echo data is conventionally linearly mapped, but there is a demand to provide an image that accurately reflects the structure of a tissue in a living body.
[0008]
An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of faithfully representing the structure of a tissue in a living body.
[0009]
Another object of the present invention is to provide an ultrasonic diagnostic apparatus capable of solving the inherent problem of multi-directional simultaneous reception by post-processing.
[0010]
[Means for Solving the Problems]
(1) The present invention provides a transmission beamformer for forming a transmission beam, a reception beamformer for forming a reception beam at a position different from the transmission beam in a predetermined transmission / reception mode, and the transmission beam and the reception beam. Image forming means for mapping a data sequence obtained by forming the data sequence to a display space, wherein the data sequence is non-linearly mapped in the display space along the center line of the transmitted / received combined beam. I do.
[0011]
According to the above configuration, when the data string is mapped to the display space (corresponding to coordinate transformation), the data string is mapped along the center line of the transmitted / received combined beam, that is, faithfully conforms to the shape of the center line. The mapping eliminates or reduces image distortion that occurs during the image construction stage. Note that the center of the combined beam at each depth can be defined as the maximum sound pressure position, the center of gravity of the sound pressure distribution, the center position between both ends of the distribution, and the like.
[0012]
Preferably, the image forming means transmits and receives the transmission / reception coordinates of the data at each depth constituting the data sequence to a transmission beam profile at each depth and a transmission / reception combined beam at each depth based on the reception beam profile at each depth. Transmitting and receiving wave coordinate specifying means for specifying as center coordinates, and for each data of each depth constituting the data sequence, by performing coordinate conversion from the transmitting and receiving wave coordinates to the display coordinates, the data of each depth is displayed in the display space. And coordinate conversion means for mapping to
[0013]
According to the above configuration, by considering the transmission beam profile and the reception beam profile at each depth position, that is, the transmission beam characteristics and the reception beam characteristics, the center position of the transmission / reception combined beam at each depth position can be recognized with high accuracy or It is possible to estimate and, thereby, to assign correct transmission / reception wave coordinates to each data.
[0014]
Preferably, the transmit / receive wave coordinate specifying unit calculates a transmit beam profile at each depth based on transmit delay data, and a receive beam profile at each depth based on receive delay data. Receiving beam profile calculating means to be sought, and beam profile product calculating means for calculating the transmit / receive combined beam center coordinates at each depth based on the transmitting beam profile at each depth and the receiving beam profile at each depth. Including.
[0015]
The transmission delay data corresponds to a transmission delay amount given to a plurality of vibrating elements forming the transmission aperture, and the transmission delay data determines a beam pattern, a transmission focus, and the like in addition to the transmission aperture. Similarly, the reception delay data corresponds to a reception delay amount given to a plurality of vibrating elements forming the reception aperture, and the reception delay data determines a reception beam pattern, a reception focus, and the like in addition to the reception aperture. Since reception dynamic focus is generally applied at the time of reception, reception delay data is dynamically changed according to scanning in the depth direction of the reception point. In the above configuration, each calculation means may be configured by a calculator that actually performs the calculation, or may be configured by a storage unit that configures a table.
[0016]
In any case, if the center coordinates of the actual transmitted / received combined beam are specified on the basis of the transmission / reception conditions, it becomes possible to give accurate transmission / reception wave coordinates for each data.
[0017]
Incidentally, when calculating the product of the beam profiles, it is desirable to limit the calculation range between the center of the transmission beam profile and the center of the reception beam profile. According to this configuration, it is possible to perform an efficient search by reducing the amount of calculation, that is, to quickly obtain the center of the transmitted and received combined beam profile.
[0018]
Preferably, the transmit / receive wave coordinate specifying means is configured by a storage unit that stores the transmit / receive combined beam center coordinates at each depth based on the transmit beam profile at each depth and the receive beam profile at each depth. . According to this configuration, if the address is specified in the storage unit based on the transmission / reception conditions, the transmitted / received combined beam center coordinates as the transmitted / received wave coordinates can be quickly specified.
[0019]
Preferably, the predetermined transmission / reception mode is a mode in which a plurality of reception beams are formed per transmission beam. Of course, a plurality of transmission beams may be simultaneously formed under the conditions.
[0020]
Preferably, the image composing means includes interpolation processing means for generating interpolation data by interpolation processing when mapping data of each depth constituting the data sequence.
[0021]
Preferably, the image forming means includes an image shaping means for shaping an edge of the ultrasonic image into a straight line. Preferably, the image shaping unit shapes an edge of the ultrasonic image into a straight line by a clipping process. Preferably, the image shaping unit shapes an edge of the ultrasonic image into a straight line by an extrapolation process.
[0022]
In the case where the center of the transmitted / received combined beam is curved and each data string is drawn in accordance with the shape thereof, the outer shape of the ultrasonic image may be distorted unless appropriate edge processing is performed. Therefore, it is desirable to shape the outer shape of the ultrasonic image by the image shaping means. As a result, a fan-shaped image can be formed correctly in the case of electronic sector scanning, and a rectangular image can be formed correctly in the case of electronic linear scanning. The same applies to the case where another scanning method is applied.
[0023]
(2) The present invention provides a transmission beamformer that repeatedly forms a transmission beam, a reception beamformer that repeatedly forms a reception beam at a position different from the transmission beam in a predetermined transmission / reception mode, A scan converter that performs coordinate transformation on a data group obtained by repeatedly forming the reception beam to form an ultrasonic image, and the scan converter is based on the coordinates of the center line of the combined transmission and reception beams. The present invention is characterized in that coordinate transformation faithful to distortion generated on the center line of the transmitted / received combined beam is executed.
[0024]
Preferably, a center line of the transmitted / received combined beam is specified based on transmission / reception conditions.
[0025]
Preferably, means for calculating a transmission beam profile at each depth based on transmission delay data, means for calculating a reception beam profile at each depth based on reception delay data, and a transmission beam profile at each depth. Means for calculating a center line of the combined transmission and reception beam based on the reception beam profile at each of the depths.
[0026]
Preferably, the scan converter includes a frame memory having an address space corresponding to a transmission / reception space, and means for executing coordinate conversion and interpolation processing when reading data from the frame memory.
[0027]
According to this configuration, a so-called read coordinate conversion process is performed. In this case, generally, display coordinates are sequentially generated in accordance with the raster scan, and transmission / reception wave coordinates corresponding to each display coordinate are sequentially generated, and are used as read addresses of the frame memory. In general, a plurality of (for example, four or eight) transmission / reception coordinates existing in the vicinity of the display coordinates are designated, and an interpolation process is applied between the plurality of data read out to thereby correspond to the display coordinates. Data (interpolated data) is generated.
[0028]
Preferably, the scan converter includes a frame memory having an address space corresponding to a display space, and means for executing coordinate conversion and interpolation processing when writing data to the frame memory.
[0029]
According to this configuration, a so-called write coordinate conversion process is performed. In this case, each time each data is input, the transmission / reception wave coordinates are converted into display coordinates, and the display coordinates are used as a write address of the frame memory. In general, when writing data to a certain display coordinate, a plurality of transmission and reception coordinates near the periphery are specified, and interpolation processing is performed on a plurality of data corresponding to the transmission and reception coordinates to generate interpolation data. Data is written to the display coordinates.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the present embodiment, the problem of the conventional method will be described first, and then the method of the present embodiment will be described in comparison with the conventional method.
[0031]
FIG. 1 shows a beam profile at a certain depth position when the position of the transmission beam and the position of the reception beam are different. The horizontal axis indicates the beam direction θ, and the vertical axis indicates power.
[0032]
In this example, the transmission beam profile 122 has a characteristic that spreads symmetrically about the center 120 of the transmission beam. On the other hand, a center 124 of the reception beam is set at a position displaced by a certain distance from the center 120, and a reception beam profile 126 extending right and left around the center 124 is formed. When such a transmission beam profile 122 and a reception beam profile 126 exist, a transmission / reception combined 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 apparent 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 / reception combined beam is equal to the center 128 of the transmission beam 120 and the center 124 of the reception beam. It does not match any of them and is formed between them. Of course, the form and position of the combined transmit / receive beam depend on the form and position of the transmit and receive beam profiles.
[0033]
Next, the problem of the distortion of the center line of the combined beam transmitted and received will be described with reference to FIG.
[0034]
In FIG. 2, reference numeral 10 indicates an array vibrator including a plurality of vibrating elements. As is well known, a transmission beam is formed by supplying a plurality of transmission signals with a predetermined delay relationship to a plurality of vibration elements, while a predetermined delay is applied to a plurality of reception signals from the plurality of vibration elements. Delay processing is performed with the relationship, 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 for one transmission. On the other hand, according to the reception dynamic focus, the reception focus point can be continuously moved from the vicinity of the array transducer 10 to the deep direction. That is, the reception focus point can be made to coincide with the reception point, and the reception focus point can be scanned in the depth direction in accordance with the scanning of the reception point in the depth direction. By the way, with such a reception dynamic focus, usually, an aperture variable control for continuously or stepwise expanding the reception aperture is executed.
[0035]
In FIG. 2, reference numeral 132 indicates the center line of the transmission beam. A transmission focus point 134 is set at a certain depth on the center line 132. The transmit beam generally has the form of being most focused near the transmit focus point 134 and expanding before and after it. A pair of reception beams is formed on both sides of the center line 132 of the transmission beam. The center lines 136, 138 of each receive beam are straight lines. However, as described above, since the beam width of the transmission beam changes at each depth, the center line of the transmission / reception combined beam draws a curve as shown by reference numerals 140 and 142. That is, as indicated by reference numerals 141 and 143, near the transmission focus point 134, the center lines 140 and 142 of the combined transmission and reception beams are drawn toward the center line 132 of the transmission beam, and the portions are curved (reference numerals). 141, 142).
[0036]
The above phenomenon will be further studied with reference to FIG. 3A shows each beam profile at a shallow depth position, FIG. 3B shows each beam profile at an intermediate depth position near the transmission focus point, and FIG. 2 shows each beam profile at a deep position.
[0037]
The beam profiles 144A, 144B, 144C of the transmission beam fluctuate depending on the depth direction. In particular, as shown in (B), the profile becomes considerably focused near the transmission focus point.
[0038]
Reference numeral 146 indicates the center of the transmission beam, and a pair of reception beams is formed on both sides of the center 146. The centers of the pair of receiving beams are indicated by reference numerals 150 and 152. The reception beam basically has a similar profile over the depth direction as shown by reference numerals 148A, 148B, and 148C. The center of the profile always coincides with the position indicated by reference numerals 150 and 152. This means that the movement trajectory of the reception focus point for each reception beam is a straight line.
[0039]
Therefore, as indicated by reference numerals 150A, 150B, and 150C, the position in the azimuth direction of the center in the transmission / reception combined beam profile at each depth varies depending on the depth direction. This is the phenomenon as shown in FIG.
[0040]
Despite the above-mentioned phenomenon, if the echo data sequence corresponding to the reception beam is linearly mapped in the digital scan converter, for example, when a tomographic image is formed, the organ image is distorted.
[0041]
Although the above description has been made on the assumption that the ultrasonic beam is not deflected, the same problem occurs when the ultrasonic beam is deflected at the angle θ. This will be described with reference to FIG.
[0042]
FIG. 8 shows a conventional problem when an ultrasonic beam is deflected. Basically, a problem similar to the problem described with reference to FIG. 4 has occurred. More specifically, when the transmission focus point 162 is set on the center line 160 of the transmission beam, the center lines 164 and 166 of the pair of reception beams formed on both sides of the transmission beam are straight lines. Also, the center lines 168 and 170 of the combined transmitted and received beams are distorted as shown. Reference numerals 165 and 166 indicate distortion amounts near 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 about its center.
[0043]
FIG. 5 schematically shows a scan plane formed by scanning two electronic beams while forming two receive beams for one transmit beam. For each transmission / reception, a pair of reception beam center lines is formed on both sides of the transmission beam center line 304, thereby forming a pair of transmission / reception combined beams on both sides of the transmission beam center line. In this case, as shown in FIGS. 2 and 4, each transmitted / received combined beam center line 306 has a non-linear shape as shown. In particular, the distortion of each reception beam center line 306 near the transmission focus point 302 is large. Θ indicates the azimuth direction, and r indicates the depth direction. The vertex of the fan-shaped scanning plane 300 is the transmission / reception wave origin.
[0044]
In the conventional apparatus, the data string corresponding to the reception beam is linearly mapped in the display space without particularly considering the curvature of the transmission / reception combined beam center line 306 as described above. In this case, as conceptually shown in FIG. 6, the image sequence of the organ existing in the fan-shaped tomographic image 310 is distorted in each direction. In particular, a discontinuous portion appears between sound rays, and a stripe pattern occurs. Here, for the sake of explanation, the organ is drawn as a rectangle extending in the horizontal direction. This is the same in FIG. 7 described below.
[0045]
Therefore, in the present embodiment, the actual shape of the transmitted / received combined beam center line (that is, the center coordinates of the transmitted / received combined beam profile at each depth) is determined in advance, and the data train is arranged on the transmitted / received combined beam center line along the shape. The above problem is addressed by faithfully mapping That is, as shown in FIG. 5, the data arrangement is faithfully performed according to the distortion of the transmission / reception combined beam center line to avoid the problem that the image of the organ is distorted at the time of coordinate transformation. From another point of view, this is also to provide more accurate transmission and reception coordinates for each data. FIG. 7 schematically shows a tomographic image 315 formed by the method according to the present embodiment, in which the image 313 of the organ is not distorted and accurately reflects the tissue shape. Imaging has been achieved.
[0046]
FIG. 8 shows a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention, and FIG. 8 is a block diagram showing the overall configuration.
[0047]
The probe 410 is an ultrasonic probe that is brought into contact with the surface of a living body or inserted into a body cavity. The probe 410 has an array transducer composed of a plurality of transducers. As described above, an ultrasonic beam (transmitting beam, receiving beam) is formed by the array transducer, and the ultrasonic beam is electronically scanned. As a result, a scanning plane, which is a two-dimensional data capturing area, is formed. Of course, the present invention can be applied to a case where a three-dimensional data capturing area is formed.
[0048]
The transmission unit 412 functions as a transmission beamformer. That is, a transmission beam is formed by supplying a plurality of transmission signals with a predetermined delay relationship to a plurality of vibration elements. The transmission unit 412 has a plurality of transmission circuits, and each transmission circuit includes a waveform generator, a D / A converter, a linear amplifier, and the like. The receiving unit 414 functions as a receiving beamformer. That is, by performing phasing addition processing on a plurality of reception signals output from a plurality of vibration elements with a predetermined delay relationship, a reception beam is formed electronically. The receiving unit 414 has a plurality of receiving circuits corresponding to the plurality of vibration elements. Each receiving circuit has an amplifier, a D / A converter, a delay circuit, and the like. The plurality of received signals after the delay processing are added by the adder, whereby the phasing addition processing is achieved. The reception signal after the phasing addition is output to signal processing section 418.
[0049]
The signal processing unit 418 has signal processing modules corresponding to a plurality of operation modes. For example, in a module corresponding to the B mode, circuits such as a detection circuit and a logarithmic compression circuit are provided. Of course, when a two-dimensional blood flow image or the like is formed, a quadrature detection circuit, an autocorrelation circuit, and the like are provided. Further, a signal processing circuit necessary for another mode is provided.
[0050]
A data sequence (echo data sequence or Doppler data sequence) is input to a DSC (Digital Scan Converter) 420 for each reception beam. The DSC 420 performs coordinate conversion, interpolation processing, and the like on the data sequence. That is, for each data, a coordinate conversion from transmission / reception wave coordinates to display coordinates, a process of generating interpolation data, and the like are executed. In the present embodiment, the coordinates on the transmission / reception combined beam center line are used as the transmission / reception wave coordinates of each data, that is, coordinate conversion faithful to the shape of the transmission / reception combined beam center line is achieved. This will be described in detail later.
[0051]
In the DSC 420, in addition to the coordinate conversion as described above, interpolation data necessary for forming an ultrasonic image to be displayed is also generated. For example, a plurality of data such as four or eight data near the interpolation point is referred to, and interpolation data is generated by performing a predetermined interpolation operation on the data. An ultrasonic image constituted by the DSC 420, for example, the B mode is displayed on the display unit 464.
[0052]
The control unit 416 includes an operation program, a CPU, and the like, and controls the operation of each component in the apparatus. In the present embodiment, the operation of the transmission delay data and the reception delay data is performed by the control unit 416, and the data is supplied to the transmission unit 412 and the reception unit 414, and is also supplied to the DSC 420. ing. This is for calculating the transmission / reception combined beam center line. Of course, the control unit 416 may calculate the transmission / reception combined beam center line, that is, the actual transmission / reception wave coordinates of each data, by software processing, for example.
[0053]
Next, the configuration of the DSC 420 shown in FIG. 8 will be described in detail. Incidentally, the coordinate conversion methods are roughly classified into write coordinate conversion and read coordinate conversion, and FIG. 8 shows a read coordinate conversion method. FIG. 14, which will be described later, shows an example of a writing coordinate conversion method.
[0054]
In FIG. 8, input data is stored on a frame memory 454 in accordance with a transmission / reception wave coordinate system. Specifically, each data is stored in a memory address corresponding to a write address specified by r and θ. In this case, the write address has been generated by the write controller 452.
[0055]
In the present embodiment, the writing controller 452 specifies the transmission and reception coordinates of the data at each depth forming the data string as the coordinates of the center line of the transmission and reception combined beam described above. In other words, even if there is distortion in the center line of the transmitted and received combined beams, data mapping is faithfully performed on such distortion, thereby avoiding problems such as distortion of the image of an organ when a tomographic image is formed as a result. Is what you do.
[0056]
In order to accurately specify the transmission / reception wave coordinates, the writing controller 452 refers to the transmission beam profile and the reception beam profile at each depth, as described later with reference to FIG. That is, as shown in FIG. 1 and the like, the transmission / reception combined beam profile can be specified as a combination or product of the transmission beam profile and the reception beam profile, and the profile center can be calculated as the maximum sound pressure on the transmission / reception combined beam profile. Therefore, information necessary for such calculation is supplied from the control unit 416 to the write controller 452.
[0057]
Therefore, the write controller 452 gives the most suitable transmission / reception wave coordinates for each data. Specifically, such transmission / reception wave coordinates are provided to the frame memory 454 as write addresses. As a result, each data is stored on the frame memory 454 at a memory address corresponding to the coordinates of each sampling point in the actual transmission / reception wave space. That is, at this stage, it is possible to solve the problem of image distortion as seen in the conventional device.
[0058]
An interpolation processing unit 456 is provided downstream of the frame memory 454. The interpolation processing unit 456 includes a conversion and interpolation controller 458 and an interpolator 462 in the example shown in FIG. The conversion and interpolation controller 458 performs coordinate conversion from the transmission / reception wave coordinates to the display coordinates, and controls reading of a plurality of data necessary for the interpolation processing. Specifically, for example, when determining a pixel value for a certain display coordinate, four or eight data corresponding to the vicinity of the display coordinate are read from the frame memory 454, and the plurality of data are For example, interpolation data is obtained by applying a linear interpolation process or the like, and the interpolation data is output to the display unit 464 as a pixel value.
[0059]
In the above-described interpolation processing, normally, each display coordinate is sequentially generated according to the raster scan, and the interpolation processing is performed for each of the sequentially generated display coordinates. In each interpolation process, the conversion and interpolation controller 458 supplies the frame memory 454 with a plurality of transmission / reception wave coordinates corresponding to the display coordinates as read addresses. Of course, such a plurality of read addresses correspond to a plurality of data used in the interpolation processing.
[0060]
As is clear from the above description, the conversion and interpolation controller 458 performs a conversion from the display coordinates to the transmission and reception coordinates inside for convenience, but as a result, the data input to the DSC 420 The transmission / reception wave coordinates are converted to the display coordinates, and the DSC 420 has the essential function of the coordinate conversion from the transmission / reception wave coordinates to the display coordinates as in the case of the write conversion method described later with reference to FIG. It is.
[0061]
Therefore, as described above with reference to FIG. 7, each data is accurately mapped to the display space in accordance with the accurate transmission / reception wave coordinates. Problems such as steps and stripes can be effectively eliminated or reduced.
[0062]
FIG. 9 shows a specific configuration example of the write controller 452 shown in FIG. In the example illustrated in FIG. 9, the writing controller 452 includes a transmission beam profile calculation unit 428, a reception beam profile calculation unit 430, and a beam profile product calculation unit 431. The transmission beam profile calculation unit 428 is a module that calculates a transmission beam profile at each depth position based on transmission delay data supplied from the control unit 416.
[0063]
Similarly, the reception beam profile calculation unit 430 is a module that calculates the reception beam profile at each depth based on the reception delay data for each depth position of the reception point supplied from the control unit 416. Then, the beam profile product calculation unit 431 obtains the transmission and reception combined beam profile by calculating the product of the transmission beam profile and the reception beam profile. Specifically, in order to perform the calculation quickly, such calculation of the product of the beam profiles is performed only between the center of the transmission beam profile and the center of the reception beam profile, and the maximum sound pressure point therebetween, That is, the center of the transmission / reception combined beam profile is specified as the peak point.
[0064]
Since only one (one set) of transmission delay data is supplied per transmission, reception delay data is generated for each depth position according to the reception dynamic focus at the time of one reception. The product calculation unit 431 performs calculation of the product of the beam profiles for each depth position. Thereby, the transmission / reception wave coordinates are obtained from the beam profile product calculation unit 431 as the center of the transmission / reception combined beam profile for each data at each depth. The transmission / reception coordinates are specified by the r address and the θ address. The transmission / reception wave coordinates are output to the frame memory 454 as a write address as described above.
[0065]
FIG. 10 shows another embodiment of the write controller 452 shown in FIG. In this embodiment, the coordinate memory 432 stores the transmission / reception wave coordinates corresponding to the center of the transmission / reception combined beam calculated in advance. That is, the control unit 416 generates a memory address based on the transmission delay data and the reception delay data, and reads out the transmission / reception wave coordinates specified by the memory address from the coordinate memory 432. Incidentally, when the transmission / reception conditions are changed, it is preferable that the control unit 416 newly calculates the transmission / reception wave coordinates corresponding to each reception point and downloads the calculation results to the coordinate memory 432. Then, when actual transmission / reception is started, it is desirable that the control unit 416 sequentially generates memory addresses, and thereby sequentially generates transmission / reception wave coordinates from the coordinate memory 432.
[0066]
FIG. 11 conceptually shows a result of mapping each data on the display space. Here, the example shown in FIG. 11 is a case in which electronic sector scanning is performed. Reference numeral 434 denotes a center line of a combined transmitted / received beam, and reference numeral 438 denotes real data (real pixel) obtained by transmission / reception of ultrasonic waves. Reference numeral 440 denotes interpolation data (interpolated pixels) generated by interpolation processing on a plurality of pieces of real data. Further, reference numeral 436 indicates other background data (background pixels). As shown in FIG. 11, the center line 434 of the combined beam transmitted and received has a curved shape with the above-described fluctuation of the beam profile in the depth direction. The actual data 438 is mapped, and as a result, problems such as distortion of the image of the organ can be effectively solved. Further, since the interpolation data 440 is generated between the plurality of actual data, the apparent resolution of the ultrasonic image can be improved.
[0067]
The conversion and interpolation controller 458 illustrated in FIG. 8 includes a shaping unit 460 in the present embodiment. The shaping processing unit 460 is a processing unit that corrects distortion generated at an edge of the scanning surface and performs linear processing. In this case, as a method of the shaping process, a clipping process and an extrapolation process can be given. As shown in FIG. 12, in the case where a pair of center lines 434A and 434B are present at the end of the image 444, the clipping processing is performed by cutting off a half area 442 between them. Is to process the edge 444A of the image 444 into a straight line. Here, reference numeral 440 indicates an interpolation pixel, and reference numeral 438 indicates an actual pixel.
[0068]
On the other hand, FIG. 13 shows an extrapolation process. In this case, the interpolation data 440 is supplemented by interpolation to the missing area caused by the curvature of the outer center line 434B of the pair of center lines, thereby processing the edge 444A of the image 446 linearly. Things. Reference numeral 450 indicates an enlarged view of such a supplemented portion. For example, extrapolation processing can be achieved by copying the actual data or the interpolated data to the outside. In the example shown in FIG. 13, all the pixels 440A, 440B, and 440C have the same value.
[0069]
Of course, the above-described shaping process is an example, and various other processes can be applied. In addition, in the examples shown in FIGS. 12 and 13, a rectangular image corresponding to electronic linear scanning or the like is shown. Side straightening can be applied.
[0070]
FIG. 14 shows another embodiment of the electronic DSC 420 shown in FIG. The example shown in FIG. 14 is one mode of the write conversion method.
[0071]
The line memories 470 and 472 are connected in series, and a data string corresponding to one reception beam is stored in the line memories 470 and 472. That is, the two line memories 470 and 472 store two data strings corresponding to two adjacent reception beams.
[0072]
The interpolator 478 is a circuit that generates a plurality of necessary interpolation data between two transmission / reception combined beams. In order to perform such an interpolation process, a conversion and interpolation controller 474 is provided. The conversion and interpolation controller 474 designates, for example, four data on the two transmitting and receiving combined beams by their transmitting and receiving wave coordinates, and uses one of the four data thus specified, for example, to interpolate one or a plurality of necessary interpolation data. Is generated in the interpolator 478. Then, the interpolation data generated by the interpolation processing is stored in the frame memory 480. In this case, the interpolation data is stored in the memory address corresponding to the display coordinates specified by the conversion and interpolation controller 474. . That is, coordinate conversion is achieved by specifying an address corresponding to the display coordinates at the stage of writing each data to the frame memory 480.
[0073]
Therefore, data for each display coordinate is stored in the frame memory 480, and when each display coordinate is specified by the read controller 482 in accordance with the raster scan, the data is supplied to the frame memory 480 as a read address and read out. Each data specified by the address is read out in order.
[0074]
The conversion and interpolation controller 474 is supplied with transmission delay data and reception delay data from the control unit 416 in the same manner as the configuration shown in FIG. 9 in order to convert the transmission / reception wave coordinates to the display coordinates. Then, a transmission beam profile and a reception beam profile are calculated based on them, and a product of them is calculated to specify transmission / reception wave coordinates of each data. Further, when the transmission / reception wave coordinates are obtained, a display coordinate corresponding to the data is obtained by using a conversion table from polar coordinates to polar coordinates. Of course, a memory in which the calculation results are stored in advance as shown in FIG. 10 may be used without performing the coordinate calculation for each data.
[0075]
In the embodiment shown in FIG. 14 as well, the conversion and interpolation controller 474 has a shaping section 476, and the shaping section 476 attempts to linearize the edges of the image data. The principle is the same as that shown in FIGS.
[0076]
FIGS. 8 and 14 show two embodiments relating to the DSC. However, the present invention can be realized with various configurations as long as each data can be faithfully mapped on the center line of the transmission / reception combined beam. Since the transmission beam profile and the reception beam profile can be determined uniformly when certain transmission / reception conditions are determined, such profiles may be calculated in advance and stored in a storage unit existing in the apparatus, for example. Alternatively, the transmission / reception wave coordinates as the calculation result of the product of the beam profiles may be calculated in advance and managed in the storage unit in the apparatus. The azimuth of the reception beam and the depth of the reception point may be used as parameters to determine the corresponding transmission / reception wave coordinates by referring to the table.
[0077]
【The invention's effect】
As described above, according to the present invention, it is possible to construct an ultrasonic image that can faithfully represent the structure of a tissue in a living body.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a transmission beam profile and a reception beam profile.
FIG. 2 is a diagram for explaining distortion generated on a center line of a transmitted / received combined beam.
FIG. 3 is a diagram for explaining a relationship between a transmission beam profile and a reception beam profile at each depth position.
FIG. 4 is a diagram for explaining distortion generated on a center line of a transmitted / received combined beam in a state where an ultrasonic beam is polarized.
FIG. 5 is a diagram showing a pattern of a center line of a combined beam transmitted and received on a scanning surface.
FIG. 6 is a diagram for explaining image distortion according to a conventional method.
FIG. 7 is an explanatory diagram showing a state in which image distortion has been eliminated by the method according to the present embodiment.
FIG. 8 is a block diagram illustrating an overall configuration of an ultrasonic diagnostic apparatus according to the present embodiment.
FIG. 9 is a diagram illustrating an example of a write controller.
FIG. 10 is a diagram showing another example of the write controller.
FIG. 11 is a schematic diagram for explaining an ultrasonic image formed by coordinate conversion and interpolation processing.
FIG. 12 is a diagram illustrating a cut-off process as an example of a shaping process.
FIG. 13 is a diagram illustrating extrapolation processing as an example of shaping processing.
FIG. 14 is a block diagram showing another configuration example of the DSC.
[Explanation of symbols]
410 probe, 412 transmission unit (transmission beamformer), 414 reception unit (reception beamformer), 420 DSC (digital scan converter), 452 writing controller, 454 frame memory, 456 interpolation processing unit, 458 conversion and interpolation controller, 464 shaping unit, 462 interpolator.

Claims (14)

A transmission beamformer for forming a transmission beam;
In a predetermined transmission / reception mode, a reception beam former that forms a reception beam at a position different from the transmission beam,
Image forming means for mapping a data sequence obtained by forming the transmission beam and the reception beam onto a display space,
Including
An ultrasonic diagnostic apparatus, wherein the data sequence is non-linearly mapped in the display space along the center line of the transmitted / received combined beam. The device of claim 1,
The image forming means,
Transmission / reception wave coordinates specification for specifying transmission / reception wave coordinates of data at each depth constituting the data sequence as transmission / reception combined beam center coordinates at each depth based on a transmission beam profile at each depth and a reception beam profile at each depth. Means,
Coordinate conversion means for mapping data of each depth to the display space, by performing coordinate conversion from transmission / reception wave coordinates to display coordinates for the data of each depth constituting the data sequence,
An ultrasonic diagnostic apparatus comprising: The device according to claim 2,
The transmitting and receiving wave coordinate specifying means,
Transmission beam profile calculation means for calculating a transmission beam profile at each depth based on transmission delay data,
Receiving beam profile calculating means for obtaining a receiving beam profile of each depth based on receiving delay data,
Based on the transmission beam profile at each of the depths and the reception beam profile at each of the depths, a beam profile product calculation unit that calculates the transmission and reception combined beam center coordinates at each of the depths,
An ultrasonic diagnostic apparatus comprising: The device according to claim 2,
The transmission / reception wave coordinate specifying means is configured by a storage unit that stores transmission / reception combined beam center coordinates at each depth based on the transmission beam profile at each depth and the reception beam profile at each depth. Ultrasound diagnostic device. The device of claim 1,
The ultrasonic diagnostic apparatus, wherein the predetermined transmission / reception mode is a mode in which a plurality of reception beams are formed for one transmission beam. The device of claim 1,
The ultrasonic diagnostic apparatus according to claim 1, wherein said image composing means includes interpolation processing means for generating interpolation data by interpolation processing at the time of mapping data of each depth constituting said data sequence. The device of claim 1,
The ultrasound diagnostic apparatus according to claim 1, wherein the image forming unit includes an image shaping unit that shapes an edge of the ultrasound image into a straight line. The device according to claim 7,
An ultrasonic diagnostic apparatus, wherein the image shaping unit shapes an edge of the ultrasonic image into a straight line by a clipping process. The device according to claim 7,
An ultrasonic diagnostic apparatus, wherein the image shaping unit shapes an edge of the ultrasonic image into a straight line by an extrapolation process. A transmission beamformer that repeatedly forms a transmission beam;
In a predetermined transmission / reception mode, a reception beam former that repeatedly forms a reception beam at a position different from the transmission beam,
A scan converter that configures an ultrasonic image by performing coordinate transformation on a data group obtained by repeatedly forming the transmission beam and the reception beam,
Including
An ultrasonic diagnostic apparatus, wherein the scan converter performs a coordinate conversion based on a center line of a combined transmitted / received beam and faithful to a distortion generated in a center line of the combined transmitted / received beam. The device according to claim 10,
An ultrasonic diagnostic apparatus, wherein a center line of the transmitted / received combined beam is specified based on a transmission / reception condition. The apparatus according to claim 11,
Means for calculating a transmission beam profile at each depth based on the transmission delay data;
Means for calculating a receive beam profile at each depth based on the receive delay data;
Means for calculating the center line of the combined transmit / receive beam based on the transmit beam profile at each depth and the receive beam profile at each depth,
An ultrasonic diagnostic apparatus comprising: The device according to claim 10,
The scan converter,
A frame memory having an address space corresponding to the transmitting and receiving wave space;
Means for performing coordinate conversion and interpolation processing when reading data from the frame memory;
An ultrasonic diagnostic apparatus comprising: The device according to claim 10,
The scan converter,
A frame memory having an address space corresponding to the display space;
Means for executing coordinate conversion and interpolation processing when writing data to the frame memory;
An ultrasonic diagnostic apparatus comprising:

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