JP2001269336A - Ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously improve sensitivity and azimuth resolution even if an opening is variable, in the ultrasonograph allowing real-time three- dimensional scan in a sparse method. SOLUTION: This ultrasonograph comprises a plurality of oscillating elements arranged two dimensionally, a transmitting circuit 31 for transmitting ultrasonic wave to a subject through the oscillating elements, and a receiving circuit 32 for receiving echo from the subject through the oscillating elements. A plurality of first oscillating elements (C elements) of the plurality of oscillating elements are coupled to the transmitting circuit 31 and the receiving circuit 32, and a plurality of second oscillating elements (S elements) and a plurality of third oscillating elements (L elements) are selectively coupled to the transmitting circuit 31 and the receiving circuit 32 via a switch 13, respectively, and the opening is varied by selection of switch 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to a real-time ultrasonic diagnostic apparatus equipped with a matrix array probe in which a plurality of vibrating elements are two-dimensionally arranged.
The present invention relates to an ultrasonic diagnostic apparatus capable of obtaining a two-dimensional image.

[0002]

2. Description of the Related Art A conventional sector-scanning one-dimensional array probe for a circulatory organ is required to reduce a wide range of deflection such as an angle of view of 60.degree. To 90.degree. From the viewpoint of achieving a sufficiently small grating side lobe level, for example, in the case of a probe having a center frequency of about 2.5 MHz, 64 to 128 vibrating elements are one-dimensionally arrayed at a pitch of about 1/2 wavelength and less than 0.3 mm. In general, those having an opening of about 20 mm are used. In this case, the vibration element is not divided in the elevation direction (elevation angle direction), so that electronic scanning in this direction cannot be performed.

In recent years, a vibrating element has been divided in the elevation direction, and a living body has been scanned electronically by a matrix array probe capable of electronic deflection not only in the elevation direction but also in the elevation direction. A real-time three-dimensional ultrasonic diagnostic apparatus capable of performing high-speed scanning in three dimensions has been reported by Duke University and others. here,
Considering the number of vibrating elements required for a two-dimensional array, at least 4096 (= 64 ×
64), which is very large. Therefore, a method of reducing the number of necessary transmission / reception circuit channels by using only effective vibration elements appropriately thinned out of all the vibration elements arranged in a two-dimensional array (hereinafter referred to as a sparse method) is proposed. Have been.

[0004] The sparse method is considered to be an important technique in a real-time three-dimensional ultrasonic diagnostic apparatus in terms of minimizing the cost and power consumption of the system as much as possible. Since the beam width of the ultrasonic wave, that is, the azimuth resolution is inversely proportional to the size of the aperture, it is necessary to transmit and receive with a large aperture on a two-dimensional array in order to obtain high azimuth resolution. Two-dimensional scanning (for example, B
In the case of performing (mode), it is necessary to distribute the vibrating elements that can be used in the large opening, so that the arrangement density of the vibrating elements is reduced.

On the other hand, a real-time three-dimensional ultrasonic diagnostic apparatus generally requires multi-stage (M stages) parallel simultaneous reception in order to ensure real-time performance. This is due to the restriction that the speed of sound in a living body is about 1500 m / sec, and the repetition frequency of ultrasonic waves is limited to sound speed / depth of field / 2 [Hz] or less.
In order to obtain a visual field depth of about cm, the repetition frequency of the ultrasonic wave is limited to about 4.6 kHz. Here, in the case of a sector scan with a scan area of 60 ° × 60 ° and a scan interval of 1 ° × 1 °, to obtain a volume rate of about 20 Volume / sec, 20 [V / s] ≧ M × 4.6k. [1 / s]
/ (60 × 60 [V] / 1 ゜ × 1 ゜), M ≧ 16
And a large M is required. Therefore, 16 =
Since it is necessary to transmit the ultrasonic energy to a wide area of about 4 mm × 4 mm, the transmission aperture is limited to a certain extent in order to increase the transmission beam width.

This is because when real-time three-dimensional scanning is performed using a sparse array vibrating element arrangement arranged to obtain the same azimuth resolution as the conventional one, actual transmission is restricted due to the restriction of the transmission aperture. This means that the number of effective vibrating elements that can be used is reduced, so that the energy of ultrasonic waves that can be transmitted is reduced, causing a problem that sensitivity is deteriorated.

On the other hand, in a sparse array in which vibrating elements are arranged at high density in small apertures in order to secure sensitivity for real-time three-dimensional use, it is difficult to realize high azimuth resolution as in the related art.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic diagnostic apparatus that performs real-time three-dimensional scanning in a sparse system, and achieves both sensitivity and azimuth resolution even when the aperture is variable.

[0009]

According to the present invention, there are provided a plurality of vibrating elements arranged two-dimensionally, a transmitting circuit for transmitting an ultrasonic wave to a subject via the vibrating elements, and a vibrating element via the vibrating elements. In an ultrasonic diagnostic apparatus having a receiving circuit that receives an echo from the subject, a plurality of first transducers among the plurality of transducers are connected to at least one of the transmitting circuit and the receiving circuit, A plurality of second vibrating elements of the plurality of vibrating elements are selectively connected to at least one of the transmitting circuit and the receiving circuit by a plurality of third vibrating elements of the plurality of vibrating elements and switches. The opening is changed by switching the switch.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) First, the principle of the present embodiment will be described. Here, the vibration element interval is 0.3 mm × 0.3 mm, and the number of matrices is 64 × 64.
= Consider a square matrix array with 4096 elements (maximum aperture 19.2 mm x 19.2 mm). In general, both transmission and reception are performed by a sparse method (in accordance with the limitation of the number of effective channels due to a transmission / reception circuit, a cable, or the like, driving more or less vibrating elements at random or regularly). Here, an example will be described in which the number of effective channels is 1024 and transmission and reception are performed by 1024 elements corresponding to １ ／ of the total number of elements of 4096.

In order to secure a high azimuth resolution in conventional two-dimensional scanning (for example, B mode), 1024 vibrating elements are arranged in a maximum aperture 64 × 64 area by a method called random sparse. Fig. 1 shows an example of vibration element arrangement
(A). The black part in the figure indicates the position of the effective vibration element (drive element). A Gaussian waveform having a center frequency of 2.5 MHz and a bandwidth of 1.4 MHz (80% bandwidth) is transmitted through the aperture, and the focal point is set to 60 mm (deflection angle is 0 mm).
[゜]), the result of simulating the one-dimensional sound pressure distribution in the azimuth direction by a computer when a depth of 60 mm is observed is shown by a solid line in FIG. 1 (b). In the drawing, the horizontal axis represents the angle [゜], and the vertical axis represents the RMS value of the sound pressure, which is expressed in [dB] units normalized by the maximum value. The beam width at −6 dB is 2.1 °, and the peak value at this time is 0 dB.

On the other hand, in the vibrating element arrangement shown in FIG. 1A, in order to obtain, for example, twice as large a transmission beam width for parallel simultaneous reception required for real-time three-dimensional scanning, the aperture must be reduced by half to 32 × 32. It is necessary to limit to the area of. Then, the small aperture area includes 32 × 32/4 = 256 vibrating elements as expected values. In other words, in the case of the small aperture drive, only 256 vibrating elements are used even though 1024 channels can be used from the transmitting / receiving circuit side. The opening under this condition is a small square area in the center of FIG. 1A, and its sound pressure distribution is shown by a broken line in FIG. 1B.
In order to make the difference in beam width easy to understand, this example is also normalized by the maximum value. Although the beam width at −6 dB is doubled to 4.0 °, the peak value in this case is −1.
It has decreased to 1.9 dB. This is because the sound pressure at the focal point is proportional to the number of vibrating elements (strictly speaking, the effective vibrating element area), and the transmission sensitivity is about 12 dB (≒ 20 × Log10
(256/1024))

Therefore, in the present invention, the number of effective channels is 10 even in the case of the small aperture drive as in the case of the large aperture drive.
The purpose of the present invention is to prevent the sensitivity from deteriorating by utilizing all of 24. The number of effective channels is determined by the smaller of the number of channels of the transmitting circuit and the number of channels of the receiving circuit. Generally, the number of channels of the transmitting circuit and the number of channels of the receiving circuit are set to be the same.

Therefore, as shown in FIG.
In the present embodiment, for example, 4
Of the 096 vibrating elements, 256 random vibrating elements in the inner area of 32 × 32 (1024 elements) having the same number of effective channels located in the approximate center of the entire area of the array (this vibrating element is , C elements) are connected to the transmission circuit and the reception circuit, and 768 random oscillation elements in the outer region including 3072 elements surrounding the outer periphery of the inner region (hereinafter, these oscillation elements are referred to as L elements) ) Are selectively connected to the transmitting circuit and the receiving circuit by the remaining 768 vibrating elements (hereinafter referred to as S elements) and 768 switches SW in the inner region. The remaining 2304 vibrating elements in the outer region (this vibrating element is hereinafter referred to as A element) are:
It is not electrically connected to either the transmission circuit or the reception circuit.

At the time of three-dimensional scanning, a large aperture drive is performed using a total of 1024 channels of the C element in the inner area and the L element in the outer area selected by the switch.
In two-dimensional scanning in the B mode or the like, small aperture driving is performed using a total of 1024 channels of the C element in the inner area and the S element in the inner area selected by the switch.

In this manner, transmission and reception can be performed using the maximum 1024 channels at all times during the large aperture drive and the small aperture drive. Therefore, the maximum sensitivity can be achieved in both the application where the azimuth resolution of the large aperture is emphasized and the real-time three-dimensional application where the small aperture is used.

In particular, in the case of the small aperture driving of the present embodiment, since all the vibration elements in the small aperture region can be used, not only the sensitivity is improved, but also the side factor which is a deterioration factor in the sparse array is used. The lobe level also decreases,
There is also an effect that artifact noise is reduced. This is due to the fact that the resolution (beam width) does not depend much on the number of vibrating elements, but is determined by the aperture, but the average sidelobe decreases depending on the number of vibrating elements. . According to the result of computer simulation of the sound pressure distribution at the time of small aperture driving using the 1024 elements shown in FIG. 2, when the 1024 elements are used in the figure, the solid line in the figure indicates a 32 × 32 small aperture area. Compared with the dashed line using only 256 elements as in the past,
The beam width does not change, but the side lobe is -2 to -3d
B has decreased. The peak value has been improved to 0 dB.

FIG. 4 shows the configuration of the ultrasonic diagnostic apparatus according to the present embodiment. This ultrasonic diagnostic apparatus generally includes a matrix array probe head 1, a probe cable 2, an apparatus main body 3, and a display 4 for mainly displaying an image. The apparatus body 2 includes a transmitting circuit 31 having 1024 channels, a receiving circuit 32 having the same number of channels (1024 channels) as the transmitting circuit, and a transmitting circuit for transmitting / receiving elements (C element and S element). An electronic switch circuit 3 for switching the connection to a receiving circuit 31 and a receiving circuit 32 at the time of receiving.
5 and a two-dimensional image such as B mode based on the received signal and 3
An image generation circuit 33 capable of generating both a two-dimensional image and a three-dimensional image is provided, and a control circuit 34 that controls switching between large-aperture driving and small-aperture driving is provided as a characteristic component.

The matrix array probe head 1 includes:
The element array 11 in which the vibrating elements are arranged in a matrix of, for example, 64 × 64, and a 3D (three-dimensional) /
Control circuit 34 associated with 2D (two-dimensional) user selection
And a switch circuit 12 mounted with, for example, 768 switches 13 for selectively connecting two types of vibrating elements (L element and S element) to the transmission circuit 31 and the reception circuit 32 in accordance with the control. I have.

The switch circuit 12 is not limited to being mounted on the matrix array probe head 1 as shown in FIG. 4, but may be mounted on the connector 21 of the probe cable 2 as shown in FIG. Good, and Figure 6
As shown in FIG.

Here, a control signal line may be individually provided from the control circuit 34 to the 768 switches 13,
1 from the control circuit 34 for the 768 switches 13
The number of control lines can be reduced by sharing one control signal line with one or more switches 13. This has the advantage that the cable 2 can be made thinner in the case of FIG. However, when used for transmission, a switch 13 with a high withstand voltage is required on a certain scale in order to drive the vibrating element at a high voltage, so that the head 1 is made smaller to improve operability and not to generate heat. In view of the above, it is desirable to equip the connector 21 of FIG. 5 or the apparatus main body 3 of FIG.

The number of switches 13 is desirably kept to a minimum in the sense that the circuit configuration is not unnecessarily large. In the above-described example, since the switch 13 is basically unnecessary for the 256-channel vibrating element (C element) which is always used in the small aperture region, the number of the channels is smaller than the number of channels of the transmitting circuit 31 and the receiving circuit 32. There is an advantage that the configuration is possible. However, it is a condition that the difference in signal characteristics between the channel with the SW interposed and the channel without the SW is sufficiently small. If this condition is not satisfied, or if all the channels are It goes without saying that a SW may be interposed in the above.

Next, a description will be given of an application example of the present embodiment which produces a yield improvement effect. Originally a switch circuit 35
In contrast to the 256 vibrating elements (C elements) in the inner region that should be connected via the oscillating element, the 2304 vibrating elements (A elements) in the outer region that are not normally connected can be changed to 256 arbitrary vibrating elements (A elements).
256 pairs are selected and connected to the transmission circuit 31 and the reception circuit 32 via a switch for each pair, and a control line from the control circuit 34 is separately provided in the switch. Normally, the switch is connected to the C element side, and unfortunately, there are cases in which the characteristics of the 256 C elements are deteriorated due to manufacturing defects or aging. Then, the switch corresponding thereto is controlled so as to select the A element instead of the C element in which the problem has occurred.

Similarly, regarding the 768 vibrating elements (L elements) in the outer area, the 2
Any 768 from the rest of the 304 vibrating elements (A elements)
768 pairs are selected, and each pair is connected to the transmission circuit 31 and the reception circuit 32 via a switch, and a control line from the control circuit 34 is individually provided in the switch. Normally, the switch is connected to the L element side, and unfortunately, among 768 L elements, there are cases in which characteristics are deteriorated due to manufacturing defects or aging. Then, the switch corresponding thereto is controlled so as to select the A element instead of the L element in which the problem has occurred. Alternatively, 76 in the outer region
7 in the inner region paired with eight vibrating elements (L elements)
When any of the 68 elements (S) becomes defective, the other normal element may be selected irrespective of the aperture change.

In this way, the vibrating element having the maximum number of channels can always be used effectively, which is preferable from the viewpoint of ensuring sensitivity. Here, in the case of random sparse, since the arrangement of the vibration elements is determined at random, even if a vibration element other than the original candidate is selected,
If the number is sufficiently smaller than the total number of vibration elements used, there is a characteristic that the average beam characteristic is hard to change, so that the degree of deterioration of the beam characteristic is considered to be small.

In the conventional apparatus, in order to avoid the influence of a faulty channel, the channel is usually invalidated (the drive is not performed for transmission, the weight is set to zero for reception, etc.) in many cases. It must be disabled especially in serious cases that can cause noise.)
Although the vibrating element causing such a problem is suppressed sufficiently small in the conventional one-dimensional array, it is considered that the two-dimensional array which is difficult to manufacture is not always sufficient. Also, the two-dimensional array has the aspect of being very expensive. Since the number of vibrating elements is thinned in the sparse array in the first place, it is disadvantageous in terms of sensitivity, and such a device for maximizing the effective vibrating element area is as follows.
It is also expected to improve the reliability of the dimensional array and the stability of the sensitivity performance, and in some cases, to improve the yield.

In the above description, the aperture at the time of two-dimensional scanning does not change at the same large aperture at the time of transmission and at the time of reception. Similarly, at the time of three-dimensional scanning, the aperture at the time of transmission and reception also differs. At the same small aperture. But 3
At the time of dimensional scanning, as shown in FIG. 7, the switch 13 is switched for transmission and reception. At the time of transmission, the S element in the inner area is selected and small aperture driving is performed. At the time of reception, the L element in the outer area is selected. Then, reception may be performed using a large aperture.

(Second Embodiment) FIG. 8 shows a configuration of an ultrasonic diagnostic apparatus according to a second embodiment. The first mentioned above
In the embodiment, the transmitting aperture is changed between the two-dimensional scanning and the three-dimensional scanning, and the receiving aperture is changed between the two-dimensional scanning and the three-dimensional scanning accordingly. In the embodiment, as shown in FIG. 8, the L element in the outer region is not connected to the receiving circuit 32 via the switch 13. Then, 768 V elements in the outer region are connected to the receiving circuit 32. That is, the C element in the inner region and the V element in the outer region are connected to the receiving circuit 32 as in the first embodiment. Therefore, the receiving aperture does not change between two-dimensional scanning and three-dimensional scanning, and is always fixed at a large aperture.

In the beam forming performed by the receiving circuit 32, each ultrasonic beam is formed by multi-stage focusing, but its aperture is substantially changed according to the depth of focus, that is, the depth of focus is shallow. As the depth increases, the substantial aperture is changed so as to greatly expand, and the change in the aperture employs weighted addition when adding signals of each element in beam forming, and becomes invalid with the change in aperture. This is preferably realized by setting the weight coefficient for the signal of the element to be set to a value extremely lower than that of the effective element, such as zero or one.

(Third Embodiment) As shown in FIG. 9, when the number of channels of a circuit to be used is relatively small, a transmission / reception element is eliminated and a transmission-only element (C element, S element, L element) is used. ) And the reception-only elements (M element, N element), the reception aperture may always be fixed at a large aperture. Here, assuming that the number of effective channels of the transmission circuit 31 and the reception circuit 32 is 512,
For example, 128 C elements dedicated to transmission in the inner area, 384 S elements dedicated to transmission in the inner area, and 384 S elements dedicated to transmission in the inner area and the S element in the outer area selectively connected to the transmission circuit 31 via the switch 13. The number of transmission-only L elements is designed to be 384. Further, as reception only, 128 M elements in the inner area and 384 N elements in the outer area are designed. When the transmission and reception are completely separated in this manner, an effect is obtained that the electronic switch circuit 35 for switching between transmission and reception becomes unnecessary.

(Fourth Embodiment) In the third embodiment, the element 11 is separated for transmission and reception, and the reception aperture is fixed at a large diameter. However, it may be variable. As shown in FIG. 10, the transmission is the same as in the example of FIG. On the other hand, for reception, 128 E
The elements are fixedly connected to the receiving circuit 32, and the 384 G elements in the inner area are selectively connected to the 384 H elements in the outer area via the switch 14 to the receiving circuit 32. Has become. By switching the switch 14, the receiving aperture can be switched between the large aperture and the small aperture. By enabling the reception aperture to be switched in this way, for example, when the probe 1 is applied between the ribs and scanning is performed so as to look into the heart or the like from between the ribs, the reception aperture is reduced to reduce the barrier effect by the ribs. Can be reduced.

(Fifth Embodiment) In the ultrasonic diagnostic apparatus, the aperture and the focal length are kept constant so as to keep the F number (aperture size / focal length) constant in order to make the beam connection in the distance direction uniform. It is common to perform control between and. That is, the aperture is controlled to be larger as the focal length increases. In order for such an application to function effectively, it is preferable that the switching of the opening is not sufficient at the stages described above, but is possible at three or more stages. In the present embodiment, the openings can be switched in three or more stages. Here, for convenience of explanation, a case will be described where the opening can be switched in three stages.

FIG. 11 shows the connection between the element array 14 in the probe head and the switches 15 and 16 for realizing this. The configuration of the other parts is the same as that of the first embodiment, so that illustration and description are omitted. For simplicity of explanation and understanding, it is assumed that the element array 14 is 8 × 8 elements (= 64) and the number of effective channels of the transmission circuit and the reception circuit is 16. The aperture has the same small aperture drive in the inner region containing the same 4 × 4 elements as the number of effective channels,
The driving is changed in three stages: the same middle opening driving in the middle region including 20 elements surrounding the outer periphery of the inner region, and the same large opening driving in the outer region including 28 elements surrounding the outer periphery of the middle region.

In this embodiment, of the 64 vibrating elements of the matrix array probe, four random vibrating elements in the inner region (hereinafter, referred to as Q elements) are referred to as a transmitting circuit. Connect to the receiving circuit. Of the remaining twelve vibrating elements in the inner area, six random vibrating elements (this vibrating element is hereinafter referred to as P element) are replaced with six random vibrating elements (this A vibration element is hereinafter referred to as an O element) and a switch 15 is selectively connected to a transmission circuit and a reception circuit. Further, the remaining six vibrating elements in the inner area (hereinafter, this vibrating element is hereinafter referred to as Y element) are replaced with six random vibrating elements in the outer area (this vibrating element is hereinafter referred to as X element). ) And the switch 16 selectively connects to the transmission circuit and the reception circuit. The remaining fourteen vibrating elements in the intermediate region (this vibrating element is hereinafter referred to as a Z element)
Is not electrically connected to any of the transmitting circuit and the receiving circuit, and the remaining 22 vibrating elements (hereinafter referred to as R elements) in the outer region are connected to the transmitting circuit and the receiving circuit. It is not electrically connected to any of the circuits.

In driving the large aperture, a total of 16 channels of the Q element in the connected inner area, the O element in the intermediate area selected by the switch 15 and the X element in the outer area selected by the switch 16 are used. In driving the middle aperture, a total of 16 channels including the Q element in the inner area, the Y element in the inner area selected by the switch 16, and the O element in the intermediate area selected by the switch 15 are used.
Further, in the small aperture drive, the Q element in the inner area, the P element in the inner area selected by the switch 15, and the switch 16
, Respectively, using the Y elements in the inner region selected using the total of 16 channels.

In this manner, transmission / reception can be performed using the maximum 16 channels at all times during the large aperture drive, the middle aperture drive, and the small aperture drive. The sensitivity does not decrease due to the aperture change.

Further, as shown in FIG.
In order to minimize the total length of the wiring (OP connection path) with respect to the pairing of the P element and the O element that form a pair through the element 5, each of the O elements in the intermediate area is located within the inner area. Other than the Q element and the Y element, P elements in the inner region are selected and combined so that the total sum of the distances to the O element is the shortest. Similarly, regarding the pairing of the X element and the Y element that form a pair via the switch 16, in order to minimize the total length of the wiring (XY connection path), for each X element in the outer region, Other than the Q element and the P element in the inner area, the Y elements in the inner area are selected and combined so that the sum of the distances to the X elements becomes the shortest.

When the pairing is performed in this manner, the pair is determined according to the distance from the vibration element in the outer area farthest from the inner area, so that the total length of all connection paths is minimized. This is a desirable connection from the viewpoint of minimizing the variation in the characteristics of electric signals from each vibrating element to the circuit channel. However, in this example, as the aperture is increased, the vibrating elements are gradually buried from the outside to the inside, so that it is considered that an unfavorable situation may occur from the viewpoint of beam shape formation.

In the case of the sparse array, the spatial distribution of the vibrating elements has an effect similar to that of weighting in the amplitude direction, and the fact that the density of the outer vibrating elements is high is This is because the contribution of the vibrating element on the outside becomes relatively large, so that a donut-shaped opening having a small weight tends to be set outside the center. In this case, although the main beam formed as is well known is slightly narrowed, the primary side lobe may be unduly maximized, which is considered to be undesirable for increasing the contrast resolution. Conversely, if the inner vibrating element
If the vibrating element for W connection is buried, an aperture having a large weight is set at the central portion, and the primary side lobe tends to decrease. Therefore, it is considered to be more preferable in terms of beam formation.

As an example to show such a tendency,
FIG. 13 and FIG. 1 show the results of computer simulation of the sound pressure distribution when the distribution weight of the sparse arrangement is intentionally changed.
It is shown in FIG. Based on the same conditions (32 × 32 aperture, 256 vibrating elements) as those for obtaining the characteristics indicated by the broken line in FIG. 1B, the case where the density (weight) of the inner region is increased and the case where the density of the outer region is The case of making it larger was compared. FIG. 13 shows the arrangement of these sparse vibrating elements.
(A) is a uniform density (equivalent to the small aperture in FIG. 1 (a)), FIG.
3B shows an example in which the center is dense, and FIG. 13C shows an example in which the center is coarse. Comparing the other examples on the basis of the case of uniform density, it can be seen that the side lobe is large when the center is coarse, but decreases when the center is dense.

Therefore, as an example of a connection for increasing the density at the center, "when the size of the opening is larger than the minimum one, the smallest opening sequentially increases as the size of the opening selected by the switch increases. FIG. 15 shows a connection method in which the vibrating elements are selected from the inside to the outside of the region and the sum of the distances between the vibrating elements connected to the switches in all the switches is as small as possible. It will be described based on the following. In this case as well, for the same reason as above, it is considered preferable that the total of the connection paths be as small as possible, and the conditions for the combined use are considered.

First, as in the example of FIG. 12, four Q elements are randomly selected from the inner area, six O elements are selected from the intermediate area, and six X elements are selected from the outer area. Next, with respect to the six X elements in the outer region, the six vibrating elements closer to the center and shorter in distance from each of the X elements X among the 28 vibrating elements available in the inner region are replaced with Y elements. And connected to the switch 16 via the XY connection path. Then, with respect to the O elements included in the intermediate area, six P elements P which are closer to the center and have a short distance from each O element are selected from among the remaining 22 vibration elements in the inner area. Connect with an O-P connection path.

In this way, when a larger opening is selected from the viewpoint of the smallest opening, the tendency that many vibrating elements are distributed outside the smallest opening region is reduced. On the other hand, a relatively weighted arrangement is realized at the center. Therefore, this is a desirable connection from the viewpoint of preventing the side lobe from being unduly maximized.

In the above embodiment, the example in which the aperture is variable in three stages has been described. However, it can be easily analogized that the present invention can be applied to a case where the basic idea can be varied in more stages.

Further, it goes without saying that examples of the arrangement and switching of the vibrating element according to the present invention are not limited to the above-described embodiment, but can be variously modified.
For example, (a) the concept of the fifth embodiment can be applied to the transmission aperture, the reception aperture, or both apertures.
(B) It is desirable that the center of gravity of each opening serving as a selection candidate is located at the center of the array, but it may be shifted.
(C) Although the sparse arrangement is a random arrangement as an example, a periodic sparse arrangement reported in a paper or the like may be basically used.

Regarding the switching of the arrangement pattern or the opening shape, the opening shape is arbitrary such as a rectangle, a circle, or an ellipse. In some cases, the number of the vibrating elements is constant regardless of whether the shape is rectangular or circular. For this purpose, an embodiment in which the well-known difference between the characteristics of the rectangular opening and the characteristics of the circular opening are properly used depending on the application can be considered. Here, the sound pressure distribution created by the rectangular aperture is represented by the product of two-dimensional sinc functions (sinc in the azimuth direction x sinc in the elevation direction). Distribution. On the other hand, the sound pressure distribution created by the circular aperture is represented by a two-dimensional Bessel function, and “the main beam width is about 20% wider, but the primary side lobe is 4 dB, compared to a rectangular aperture having the same outer peripheral aperture. Weakly distributed uniformly. Therefore, in the case of a scanning mode in which one of the vibration element connection candidates is arranged in a sparse arrangement for a rectangular aperture and the other is arranged in a sparse arrangement for a circular aperture, and a B-mode tomographic image in which azimuth resolution is emphasized is obtained. When a C-mode tomographic image requiring a spatially uniform resolution is obtained using a rectangular aperture with SW (scanning equivalent to three dimensions), it is preferable to use a circular aperture with a switch. .

Of course, it is possible to obtain a circular opening without using the vibrating elements at the four corners by arranging the rectangular vibrating elements, but in this case, the effective area is reduced to π / 4, so that the sensitivity loss is reduced. Large (both transmissions are degraded by -2.1 dB). Therefore, there is a merit of switching by the SW for achieving both the rectangular opening and the circular opening with high sensitivity. In this embodiment, a sparse arrangement pattern for a rectangular opening and a sparse arrangement pattern for a circular opening are arranged independently of each other, and then a predetermined vibration element (vibration element that is basically not shared by both openings) is determined. Pairing of the vibration elements may be performed, or a rectangular opening may be considered as a large opening area in the first embodiment, and a circular opening may be considered as a small opening area. May go.

Further, the present invention can be applied to a change in the opening shape in consideration of the acoustic window of the living body. That is, the present invention can be applied to a case where the opening is not a fixed shape and is dynamically deformed. For example, assuming a cardiac examination, when a matrix array probe is placed on the chest wall, multiple reflections occur between the probe and ribs due to the presence of ribs whose acoustic impedance is significantly different from surrounding soft tissue. In some cases, the waveform of the received signal is greatly distorted. This situation is schematically shown in FIG.
6 (a), FIG. 16 (b), FIG. 16 (c), FIG. 16 (d)
It was shown to. A channel of a circuit connected to a vibrating element that gives a signal significantly different from such a predetermined characteristic (substantially the same as the “defective channel” described later in the first embodiment) is a noise source. In recent years, proposals have been made to attempt to reduce the effect on image quality by disabling the channel (do not drive for transmission, set the weight to zero for reception, etc.) No. 10-40828).

Here, since the defective channel is basically "not used", it is apparent that the sensitivity is deteriorated. Therefore, the idea of selecting a vibrating element for avoiding a defective channel described in the second half of the first embodiment is applied to an opening having a plurality of sizes as shown in the second embodiment of the present invention, Consider using the above proposals together. This is because, as shown in FIG. 16 (a), the position of the vibrating element which is considered to interfere with the ribs is at the position of the vibrating element for selecting a larger opening corresponding to the edge among the openings of the matrix array probe. Depending on what is considered easy. In other words, it is assumed that even if the edge of the large opening becomes defective, the small opening is unlikely to be defective. Therefore, when such a defective channel is detected in the case where the large aperture is selected,
Instead of "not using" the channel, the switch of the present invention is switched to the vibrating element in the small opening area to be used effectively.

In this way, in order to avoid a vibrating element which is an unnecessary noise source from the living body, even if the opening is not a fixed shape and is dynamically deformed, the sensitivity is less deteriorated. Images can be provided.

[0051]

According to the present invention, in an ultrasonic diagnostic apparatus that performs real-time three-dimensional scanning in a sparse system, it is possible to achieve both sensitivity and azimuth resolution even with variable aperture.

[Brief description of the drawings]

FIG. 1A is a diagram showing a conventional random sparse type opening (large opening, small opening), and FIG. 1B is a simulation of a one-dimensional sound pressure distribution in the azimuth direction corresponding to each opening in FIG. The figure which shows a result.

FIG. 2A is a diagram showing a vibrating element density in the case where all the vibrating elements in a small opening region are conventionally driven, and FIG.
FIG. 9 is a diagram showing a simulation result of a one-dimensional sound pressure distribution in the case of FIG.

FIG. 3 is a diagram illustrating the principle of the present invention.

FIG. 4 is a configuration diagram of an ultrasonic diagnostic apparatus according to the first embodiment.

FIG. 5 is a diagram showing a modification of FIG. 4;

FIG. 6 is a view showing another modification of FIG. 4;

FIG. 7 is a time chart showing a movement of changing an aperture between transmission and reception in the 3D scan of the first embodiment.

FIG. 8 is a configuration diagram of an ultrasonic diagnostic apparatus according to a second embodiment.

FIG. 9 is a configuration diagram of an ultrasonic diagnostic apparatus according to a third embodiment.

FIG. 10 is a configuration diagram of an ultrasonic diagnostic apparatus according to a fourth embodiment.

FIG. 11 is a configuration diagram of a main part of a fifth embodiment.

FIG. 12 is a view showing pairing of the vibration element shown in FIG. 11;

13A and 13B are diagrams showing a driving element density at the time of small aperture driving in the fifth embodiment, where FIG. 13A shows a case where the density is uniform, FIG. 13B shows a case where the center is dense, and FIG.

FIG. 14 is a view showing a simulation result of a one-dimensional sound pressure distribution corresponding to each density in FIG. 13;

FIG. 15 is a view showing another pairing of the vibration element of FIG. 11;

FIG. 16 is a diagram showing the effect of multiple reflection on a received signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Matrix ultrasonic probe, 2 ... Cable, 3 ... Device body, 4 ... Display, 11 ... Vibration element array, 12 ... Switch circuit, 13 ... Switch, 31 ... Transmission circuit, 32 ... Receiving circuit, 33 ... Image generation circuit , 34 ... Control circuit.

Claims (30)

[Claims] 1. A plurality of vibrating elements arranged two-dimensionally, a transmitting circuit for transmitting ultrasonic waves to a subject via the vibrating elements, and receiving an echo from the subject via the vibrating elements. In an ultrasonic diagnostic apparatus having a receiving circuit, a plurality of first vibrating elements among the plurality of vibrating elements are connected to at least one of the transmitting circuit and the receiving circuit,
A plurality of second vibrating elements of the plurality of vibrating elements are selectively connected to at least one of the transmitting circuit and the receiving circuit by a plurality of third vibrating elements of the plurality of vibrating elements and switches. And an aperture is changed by switching the switch. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the first vibrating element is distributed in an inner area together with the second vibrating element, and the third vibrating element is distributed in an outer area. . 3. The ratio of the number of the first vibrating elements to the number of vibrating elements in the inner region is the same as the ratio of the number of the third vibrating elements to the number of vibrating elements in the outer region. The ultrasonic diagnostic apparatus according to claim 2, wherein: 4. The device according to claim 1, wherein the total number of said first and second vibrating elements is equal to the total number of said first and third vibrating elements. 2
An ultrasonic diagnostic apparatus as described in the above. 5. The total number of elements of the first vibrating element and the second vibrating element is equal to the number of vibrating elements in the inner region,
The ultrasonic diagnostic apparatus according to claim 2, wherein the number of the third vibration elements is smaller than the number of the vibration elements in the outer region. 6. The first vibration element and the second vibration element are relatively densely distributed in the inner area, and the third vibration element is relatively coarsely distributed in the outer area. The ultrasonic diagnostic apparatus according to claim 2. 7. The total number of elements of the first vibrating element and the second vibrating element and the total number of elements of the first vibrating element and the third vibrating element are each equal to the number of channels of the transmitting circuit. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the values coincide with each other. 8. The total number of the first and second vibrating elements and the total number of the first and third vibrating elements are each equal to the number of channels of the receiving circuit. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the values coincide with each other. 9. The ultrasonic diagnostic apparatus according to claim 1, wherein the number of said switches is smaller than the number of channels of said transmission circuit. 10. The ultrasonic diagnostic apparatus according to claim 1, wherein the number of said switches is smaller than the number of channels of said receiving circuit. 11. The second vibrating element and the third vibrating element are paired so as to minimize the total distance between the second vibrating element sharing the switch and the third vibrating element forming a pair with the second vibrating element. The ultrasonic diagnostic apparatus according to claim 1, wherein: 12. The ultrasonic diagnostic apparatus according to claim 1, wherein the switch is incorporated in a probe together with the vibration element. 13. The ultrasonic diagnostic apparatus according to claim 1, wherein said switch is incorporated in a probe connector. 14. The ultrasonic diagnostic apparatus according to claim 1, wherein the switch is incorporated in the ultrasonic diagnostic apparatus main body together with the transmission circuit and the reception circuit. 15. The ultrasonic diagnostic apparatus according to claim 1, further comprising a control circuit for integrally controlling said switch. 16. The ultrasonic diagnostic apparatus according to claim 1, further comprising a control circuit for individually controlling said switches. 17. A control circuit for controlling an arbitrary switch separately from another switch in order to use one of an arbitrary second vibrating element and a third vibrating element paired with the second vibrating element in a fixed manner. The ultrasonic diagnostic apparatus according to claim 1, wherein: 18. The first vibrating element is distributed in an inner area together with the second vibrating element, and the third vibrating element is distributed in an outer area. During two-dimensional scanning, both transmission and reception are performed in the inner area. Selecting a first vibrating element and the second vibrating element in an outer region;
2. The three-dimensional scanning device according to claim 1, further comprising a control circuit for controlling the switch to select the first vibrating element and the second vibrating element in an inner area for both transmission and reception. Ultrasound diagnostic device. 19. The first vibrating element is distributed in an inner area together with the second vibrating element, and the third vibrating element is distributed in an outer area. During two-dimensional scanning, both transmission and reception are performed in the inner area. Selecting a first vibrating element and the second vibrating element in an outer region;
When transmitting a three-dimensional scan, the first vibrating element and the second vibrating element in the inner area are selected, and when receiving the three-dimensional scanning, the first vibrating element in the inner area and the third vibrating element in the outer area are selected. The ultrasonic diagnostic apparatus according to claim 1, further comprising a control circuit that controls the switch to select a vibration element. 20. The first vibrating element is connected to the transmitting circuit and the receiving circuit, and the second vibrating element is selectively connected to the third vibrating element and the transmitting circuit. The ultrasonic diagnostic apparatus according to claim 1, wherein a vibration element is fixedly connected to the receiving circuit. 21. The first vibrating element is fixedly connected to the transmitting circuit, the second vibrating element is selectively connected to the third vibrating element and the transmitting circuit, and further includes a fourth vibrating element in an inner region. The ultrasonic diagnostic apparatus according to claim 1, wherein the element and a fifth vibration element in an outer region are fixedly connected to the receiving circuit. 22. The first vibrating element is fixedly connected to the transmitting circuit, the second vibrating element is selectively connected to the third vibrating element and the transmitting circuit, and further includes a fourth vibrating element in an inner region. The ultrasonic device according to claim 1, wherein an element is fixedly connected to the receiving circuit, and a fifth vibrating element in an inner region is selectively connected to a sixth vibrating element in an outer region and the receiving circuit. Diagnostic device. 23. A plurality of vibrating elements arranged two-dimensionally, a transmitting circuit for transmitting ultrasonic waves to the subject via the vibrating elements, and receiving an echo from the subject via the vibrating elements. In an ultrasonic diagnostic apparatus having a receiving circuit, the plurality of vibrating elements are configured such that at least one of a transmission aperture and a reception aperture changes by switching a switch,
An ultrasonic diagnostic apparatus connected to the transmission circuit and the reception circuit. 24. A plurality of vibrating elements arranged two-dimensionally, a transmitting circuit for transmitting ultrasonic waves to the subject via the vibrating elements, and receiving an echo from the subject via the vibrating elements. In an ultrasonic diagnostic apparatus having a receiving circuit, the plurality of vibrating elements include a plurality of pairs of vibrating elements that are selectively connected to at least one of the transmitting circuit and the receiving circuit by a switch. An ultrasonic diagnostic apparatus characterized in that the aperture is changed variously by switching control of a switch. 25. Pairing is performed so that the density of the inner region of the vibrating element connected to at least one of the transmitting circuit and the receiving circuit becomes higher than the density of the outer region as the opening increases. 25. The ultrasonic diagnostic apparatus according to claim 24, wherein the ultrasonic diagnostic apparatus is performed. 26. Pairing is performed such that the density in each opening of the vibrating element connected to at least one of the transmitting circuit and the receiving circuit is constant irrespective of the change in the opening. The ultrasonic diagnostic apparatus according to claim 24, wherein: 27. A plurality of vibrating elements arranged two-dimensionally, a transmitting circuit for transmitting ultrasonic waves to the subject via the vibrating elements, and receiving an echo from the subject via the vibrating elements. In an ultrasonic diagnostic apparatus having a receiving circuit, among the plurality of vibration elements, a plurality of first vibration elements;
A plurality of first vibrating elements and a plurality of second vibrating elements selectively connected to at least one of the transmitting circuit and the receiving circuit by a switch, wherein an aperture is changed by switching the switch; An ultrasonic diagnostic apparatus, comprising: 28. A plurality of ultrasonic vibrating elements arranged two-dimensionally, a first transmission mode for driving a first region at a first ultrasonic vibrating element density, Control means for switching between a second transmission mode in which a large second region is driven at a second ultrasonic vibration element density lower than the first ultrasonic vibration element density, and control of the ultrasonic vibration element according to the mode. Transmitting means for transmitting a driving signal for transmission to a part thereof; and receiving signal processing means for generating an ultrasonic image based on a signal received by the ultrasonic vibration element. Ultrasound diagnostic device. 29. The control means selects the first transmission mode when performing three-dimensional scanning, and selects the second transmission mode when performing two-dimensional scanning. 29. The ultrasonic diagnostic apparatus according to claim 28, wherein: 30. The control means switches at least the first transmission mode and the second transmission mode at the time of multi-stage focusing, and selects the first transmission mode when the focus position is a long distance. 29. The ultrasonic diagnostic apparatus according to claim 28, wherein the second transmission mode is selected when the focus position is a short distance.