JPH11221217A - Ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve real-time performance of an ultrasonograph by forming an ultrasonic diagnostic image from received signals obtained by setting a receiving directivity almost same as that of the transmitted ultrasonic beam in a period the reflected wave reaches the ultrasonic vibrator. SOLUTION: The state in which an ultrasonic beam is transmitted/received between costae and the mitral valve on the border between the atrium sinistrum and the ventriculus sinister is observed is shown by (a) in the Fig.1. In order to obtain the images of a mitral valve and its periphery out of 4 regions from the region a to the region d in the depth direction, ultrasonic signals from a region c can be obtained (b). For transmission/reception direction of the ultrasonic wave, when the image angle is set θx deg., the ultrasonic wave is transmitted in the direction of angle -θx/2 in the first scanning and -θx/4 next. After transmission/reception is carried out toward directions of 0 deg. and +θx/4, the transmission/reception direction is further controlled in -θx/2+Δθ, -θx/4+Δθ, Δθin that order. However, Δθ is the minimum pitch in scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to transmitting an ultrasonic wave to a subject, receiving a reflected wave thereof, and obtaining an ultrasonic diagnostic image.
The present invention relates to a so-called ultrasonic diagnostic apparatus, and more particularly, to an ultrasonic diagnostic apparatus that achieves a substantial improvement in real-time performance and blood flow detection ability by increasing the number of scans per unit time.

[0002]

2. Description of the Related Art Ultrasound diagnostic methods for emitting ultrasonic pulses into a subject and obtaining biological information from reflected waves from various tissues have recently become rapid due to the development of two technologies, ultrasonic tomography and ultrasonic Doppler. Made progress. The most widely used electronic scanning type ultrasonic diagnostic apparatus today uses an array type ultrasonic transducer, and electronically controls and scans the ultrasonic transducer at high speed to perform real-time display.

FIG. 2 is a block diagram showing a schematic configuration of a sector electronic scanning type ultrasonic diagnostic apparatus according to a conventional example. Let M be the number of elements of the transducers 4 arranged in the ultrasonic probe. When transmitting an ultrasonic wave to a living body (or a medium), a transmission rate signal generator 1 first outputs a rate pulse for determining a repetition period of the ultrasonic pulse. This pulse is sent to a transmission delay circuit 2 composed of M channels, and is used to deflect the ultrasonic beam in a predetermined direction (θ0) with a delay time τf for determining the convergence distance (F0) of the ultrasonic beam during transmission. After the delay time τs is given, the M-channel oscillator driving circuit (pulsar) 3
Supplied to The delay time τ (m) set in the m-th delay circuit is τf (m) + τs (m), and τf and τs are set as shown in the following equation (1).

Τf (m) = d ² ｛(M−1) ² − (2m−M−1) ² ｝ / 8 VF0 τs (m) = (m−1) dsin θ0 / V (1) where d Is a transducer array interval, V is a sound speed in a living body, F0 is a focal length, and θ0 is a deflection angle.

In the pulsar 3, a driving pulse for driving the ultrasonic vibrator 4 to generate ultrasonic waves is formed. The timing of the drive pulse is determined according to the output of the transmission delay circuit 2. The output of the drive circuit 3 is supplied to an ultrasonic vibrator 4, whereby the vibrator 4 is driven to generate ultrasonic waves.

[0006] A part of the ultrasonic wave radiated into the living body from the ultrasonic transducer 4 is reflected by the boundary surface of the organ or the acoustic scatterer of the living tissue. This reflected wave is again transmitted to the ultrasonic vibrator 4
And converted into an electrical signal. After the reception signal passes through the preamplifier 5, similarly to the transmission, the delay time for determining the convergence distance of the ultrasonic beam at the time of reception and the delay time for determining the deflection angle (reception directivity) of the ultrasonic beam are determined. The signal is sent to the adder 7 through the receiving delay circuit 6 of the given M channel. Output signals from the M-channel reception delay circuit 6 are added and synthesized by an adder 7, and a logarithmic amplifier 8,
After being logarithmically compressed and detected by the envelope detection circuit 9, A / D converted, and temporarily stored in the image memory 11. Further, the stored signal is converted into a television format and displayed on the television monitor 13 as an ultrasonic tomographic image.

The other output from the adder 7 is sent to two quadrature phase detection circuits. That is, first, the mixer 1
4-1 and 14-2. On the other hand, the reference signal generator 2
From 0, a continuous wave having a predetermined frequency (generally, a frequency substantially equal to the ultrasonic frequency fo is used) is output, and the phase thereof is shifted by 90 degrees by the π / 2 transfer unit 15, and the mixer 14-1 Is input to Also, the mixer 14-2
, The output of the reference signal generator 20 is directly input. The outputs of the mixers 14-1 and 14-2 are the low-pass filter 1
At 6-1 and 16-2, the sum frequency component is removed, and only the difference frequency component is extracted. A signal having the frequency of the difference is converted into a digital signal by A / D converters 17-1 and 17-2, and then temporarily stored in a memory (not shown).

In order to calculate a Doppler signal, it is necessary to continuously scan the same part and use a plurality of (N) signals at that time. In this case, a signal obtained by a plurality of scans is temporarily stored in a memory, and when a predetermined number of data is collected, the signal changes with time in the same portion.
A series of signals are extracted, and the MTI filter 22-
Unnecessary signals are removed by 1,2-2-2. Further, the output is supplied to the FFT circuit 18 for frequency analysis of the Doppler signal.

The physical quantities displayed in the ultrasonic blood flow imaging method are the center of the spectrum (ie, the average value of the flow velocity), the variance of the spectrum (ie, the state of disturbance of the flow velocity), and the power value (ie, the Doppler signal intensity). is there. These calculations are performed by the calculator 19. The values calculated by the calculator 19 are temporarily stored in the image memory 11 and displayed on the television monitor 13. The output of the arithmetic unit 19 is generally displayed in color on a tomographic image.

The received signal input to the mixer 14 constituting the quadrature phase detection circuit first has a frequency (fo) substantially equal to the center frequency of the ultrasonic wave and two reference signals having phases different from each other by 90 degrees. The multiplication is performed by the multiplication. In addition to the Doppler frequency (fd) component, f
A frequency component of d + 2fo is obtained, the latter component being removed by a low-pass (low-pass) filter 16. The Doppler signal (fd) is once converted into a digital signal by the A / D converter 17 and then stored in a memory (not shown). Received signals obtained by scanning a plurality of times in the same direction are once stored in a memory in the same manner, then extracted as a series of signals that change with time at the same site, and reflected from blood cells by the MTI filter 22. Wave (Doppler signal)
And unnecessary signals (clutter signals) from fixed reflectors such as blood vessel walls and organs.

The Doppler signal and the clutter signal are line spectra having an interval of a pulse repetition frequency (fr), and the MTI filter is a "comb-type" filter for removing a clutter signal located at an integer multiple of fr. MTI (Mo
The ving Target Indicator) filter is a filter technique that has been used in the radar field to extract and display only moving objects such as aircraft. In this way, N complex signals at a predetermined depth are extracted and input to the MTI filter and the FFT circuit 18,
The clutter signal is removed and the spectrum is calculated. Such arithmetic processing is performed two-dimensionally, and the result is DS
The signal is synthesized with a tomographic image signal by a C (digital scan converter), converted into a television format output, and displayed on a color monitor.

Next, a conventional ultrasonic probe will be described. FIG. 3 is a perspective sectional view showing the structure of a linear array ultrasonic probe when the transducers are arranged one-dimensionally. In this probe, a plurality of transducers are one-dimensionally arranged along the scanning direction. As shown in the figure, electrodes 31 are attached to the medium (living body) for transmitting and receiving ultrasonic waves and the opposite side to each transducer 30, and an acoustic matching layer (impedance) is provided on the electrode 31 on the living body side. A matching layer 32 is provided.

The matching layer 32 adjusts the difference in acoustic impedance (product of density and sound speed) between the living body and the vibrator 30, and allows an ultrasonic pulse having a small wave number to be incident into the living body. Further, an acoustic lens 34 made of silicon rubber or the like is attached on the matching layer 32.
The acoustic lens 34 focuses the ultrasonic beam at a predetermined distance and narrows the beam width in the slice direction orthogonal to the scanning direction. The vibrator 30, the matching layer 32, the acoustic lens 34 and the like are fixed on a support (backing material) 35.

In the probe in which the transducers are arranged one-dimensionally, the ultrasonic beam is focused electronically, that is, by controlling the delay time, and the transducer is arranged in the transducer arrangement direction (scanning direction).
Beam width can be reduced. In the slice direction, a beam focusing method using an acoustic lens is adopted. In this case, since the radius of curvature of the acoustic lens is fixed, the focal point is also fixed at one point.

[0015]

By the way, the received signal spectrum before the filtering process has fd as shown in FIG.
In addition to the Doppler signal occurring at ± nfr (n is an integer), ±
A clutter signal component appears in nfr. The clutter signal is a signal from a blood vessel wall or an organ around the blood vessel (especially often an artifact component due to sidelobes or the like) mixed in a reflected wave from a blood cell, and its signal intensity is generally higher than that of a Doppler signal. About 40 dB larger. Therefore, a filtering technique for sufficiently removing this clutter signal is particularly important. Specifically, it is necessary to improve the frequency resolution of the filter, and for that purpose, it is necessary to increase the number of data, that is, the number of scans (N) of the same part.

However, increasing the number of data
Increasing the number of frames in an image is in a trade-off relationship. For this reason, it has not been possible with a conventional ultrasonic diagnostic apparatus to observe a low-flow-rate blood flow, such as a coronary artery, having a very low difference in clutter speed, especially in a fast-moving organ such as the heart.

Recently, attempts have been made to mechanically move a one-dimensional array or to perform a three-dimensional scan by using a two-dimensional array to create and display a three-dimensional image based on such scanning. Has been made.

Here, the former, that is, the conventional ultrasonic diagnostic apparatus which performs three-dimensional scanning by mechanically moving the one-dimensional array, can relatively easily make the structure of the apparatus. It takes a long time to obtain, and the operability is poor. On the other hand, the latter, that is, the conventional ultrasonic diagnostic apparatus that performs three-dimensional scanning using a two-dimensional array has the advantages that the probe can be configured as small as the conventional one and that the probe is excellent in operability. However, there is a drawback that the configuration inside the device and the probe is complicated and impractical. Furthermore, if a three-dimensional image is to be obtained in real time, a large-scale parallel simultaneous receiving circuit is required, and the circuit size increases and the apparatus becomes extremely expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to improve the real-time ultrasonic diagnosis without increasing the circuit scale and without reducing the operability. It is to provide a device. It is another object of the present invention to provide an ultrasonic diagnostic apparatus that reduces heat generation of a probe.

[0020]

In order to solve the above problems and achieve the object, an ultrasonic diagnostic apparatus according to the present invention is configured as follows.

(1) An ultrasonic diagnostic apparatus according to the present invention comprises an array of a plurality of ultrasonic transducers, and transmits an ultrasonic beam and receives a reflected wave thereof. Transmitting means for transmitting the ultrasonic beam while sequentially changing the direction at the direction interval, only during the period when the reflected wave from the specific depth region reaches the ultrasonic transducer,
A receiving unit that sets a reception directivity in substantially the same direction as the transmission ultrasonic beam that is the source of the reflected wave to obtain a reception signal,
The apparatus includes a generation unit that performs signal processing on a reception signal obtained from the reception unit to generate an ultrasonic diagnostic image, and a display unit that displays the ultrasonic diagnostic image.

According to this configuration, only during the period when the reflected wave from the specific depth region reaches the ultrasonic vibrator, the reception directivity is substantially the same as the direction of the transmitted ultrasonic beam that is the source of the reflected wave. Is set to obtain a reception signal, so that the number of scans per unit time can be greatly increased. Therefore, the color Doppler method and 3
A device that satisfies both the real-time property and the operability required for the three-dimensional display method and that is relatively inexpensive can be realized.

(2) An ultrasonic diagnostic apparatus according to the present invention is composed of a plurality of ultrasonic transducers arranged, and transmits an ultrasonic beam and receives a reflected wave thereof. Transmitting means for transmitting ultrasonic beams in at least two directions at substantially the same time while sequentially changing directions at the direction intervals of: and a reception signal based on a reflected wave of the ultrasonic beam received by the ultrasonic transducer. Receiving means to obtain;
The apparatus includes a generation unit that performs signal processing on a reception signal obtained from the reception unit to generate an ultrasonic diagnostic image, and a display unit that displays the ultrasonic diagnostic image.

According to this configuration, the transmission / reception sensitivity and the resolution between adjacent scans of the transmission ultrasonic beam can be improved.

(3) An ultrasonic diagnostic apparatus according to the present invention is composed of a plurality of ultrasonic transducers arranged, and transmits an ultrasonic beam and receives an ultrasonic wave reflected therefrom. Transmitting means for transmitting an ultrasonic beam while sequentially changing the direction at a direction interval of: a receiving means for obtaining a reception signal based on a reflected wave of the ultrasonic beam received by the ultrasonic transducer; and the receiving means Generating means for processing the received signal obtained from the above to generate an ultrasonic diagnostic image,
In the ultrasonic diagnostic apparatus including a display unit that displays the ultrasonic diagnostic image, the reflected wave is continuously generated in a specific period except for a certain period from the rising point of the rate pulse that drives the ultrasonic vibrator. A determination unit that determines whether the ultrasonic transducer is obtained; and a voltage control unit that controls a drive voltage of the ultrasonic transducer based on a determination result of the determination unit.

According to such a configuration, it can be determined by the above-mentioned determining means that the probe is in the state of air load or unused, and in this case, the transmission power generated by the probe is determined by the voltage control means. Can be reduced.

(4) An ultrasonic diagnostic apparatus according to the present invention is composed of a plurality of ultrasonic transducers arranged two-dimensionally, and transmits an ultrasonic beam and receives a reflected wave thereof. Transmitting means for transmitting an ultrasonic beam while sequentially changing the direction at predetermined direction intervals, and receiving means for obtaining a reception signal based on a reflected wave of the ultrasonic beam received by the ultrasonic transducer, In an ultrasonic diagnostic apparatus including: a generating unit that performs signal processing on a received signal obtained from the receiving unit to generate an ultrasonic diagnostic image, and a display unit that displays the ultrasonic diagnostic image, the transmitting unit includes: Ultrasonic beams in at least a plurality of directions are transmitted at substantially the same time, and the receiving means transmits the reflected waves of the ultrasonic beams in a plurality of directions transmitted at substantially the same time by the transmitting means to these ultrasonic beams. Which receives beam with directivity substantially simultaneously we need to set the same, characterized in that to obtain only reception signals based on the reflected wave from the 3-dimensional region of a specific depth.

According to such a configuration, real-time three-dimensional scanning, which has been impossible in the past, can be realized without complicating the circuit scale. Therefore, in the diagnosis of congenital heart disease, not only the shape and function (exercise state) of the heart can be observed in real time, but also a three-dimensional image of an organ in the abdomen or the like or a blood vessel based on a Doppler signal can be easily obtained. It becomes possible.

Also, in the color Doppler display or the power Doppler display of the coronary artery of the heart, which was not possible in the prior art, the present invention can improve the low flow velocity detection capability without sacrificing the number of frames, so that the diagnosis is performed. The ability can be dramatically improved.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) This embodiment relates to an ultrasonic diagnostic apparatus for displaying a three-dimensional image in real time.

In recent years, basic research has shown that a three-dimensional image is easier to grasp the structure of an entire organ than a two-dimensional image (for example, a tomographic image), has a low frequency of overlooking an abnormal site, and has excellent diagnostic performance. It is becoming clear. In order to display a three-dimensional image, at least one of the ultrasonic resolution (beam width) is required.
The three-dimensional space must be scanned at a scanning pitch of / 2 or less. However, the conventionally known pulse reflection method emits the next transmission pulse after the ultrasonic wave from the deepest part is received. In many three-dimensional scans, the time required to construct one image is limited by the speed of sound, the number of scans, and the observation depth. Therefore, real-time display of a three-dimensional image was impossible.

In order to solve such a problem, a parallel simultaneous receiving method using an electronic scanning type ultrasonic diagnostic apparatus has been developed. In the parallel simultaneous reception method, as shown in FIG. 5, a transmission ultrasonic beam is diffused and transmitted, and at the time of reception, a plurality of delay circuits provided in parallel (two reception delay circuits A and B in FIG. ), Transmission and reception in a plurality of directions are performed simultaneously, and the number of frames can be improved according to such a parallel simultaneous reception method. In particular, recently, with the digitization of the reception delay circuit, a delay-and-sum method based on a time sharing technique can be used, and parallel simultaneous reception in four directions can be performed without increasing hardware.

However, in order to display a three-dimensional moving image of 30 frames per second or more required for diagnosis of the heart or the like, it is necessary to further improve the number of frames by 4 to 8 times.

The first point of the present invention is that, when an image is obtained by limiting a predetermined part (more specifically, "depth") in the body, the number of frames can be greatly improved. Scanning (here, temporarily referred to as "gate alternate scanning method")
It is the point which realized.

The gate alternate scanning method is effective in displaying a color (power) Doppler tomographic image of a two-dimensional image. In particular, the gate alternate scanning method requires a large number of images to obtain a single image like three-dimensional scanning. This is effective when scanning is required. However, here, for ease of explanation, a case will be described in which the gate alternating scanning method is applied to capturing of a two-dimensional image by a sector electronic scanning type device.

First, the principle of the gate alternate scanning method will be described by taking as an example the case of diagnosing the shape and motor function of the mitral valve of the heart or its peripheral portion shown in FIG.

FIG. 1A schematically shows a state in which an ultrasonic beam is transmitted and received between the ribs and an image of the mitral valve at the boundary between the left atrium and the left ventricle and an image around the mitral valve are observed. Here, as shown in FIG. 1B, when considering four regions from the region a to the region d along the depth direction, in order to obtain an image of the mitral valve and its surroundings, the region It is sufficient that an ultrasonic signal can be obtained. Note that the number of regions, the boundary positions of the regions, and the intervals at which the images are formed are arbitrary, and the examiner (doctor) or the like may perform the temporary setting while observing the image obtained by the provisional setting. After roughly observing the whole image with a conventional tomographic image, it is also possible to make optimal settings from the image. Here, for simplicity of explanation, the respective regions are set at equal intervals.

The interval between transmission pulses in the gate alternate scanning method is set as follows. That is, for example, FIG.
In S, the distance from the probe tip to the front end of the area c is S
1. Assuming that the distance to the rear end is S2, ΔS = S2−S1, and the sound velocity in the living body is V, in order to receive the reflected signal during ΔS, the transmission pulse interval Δt is required under the conditions described later.
Should be at least 2ΔS / V or more.

Next, the transmitting and receiving directions of the ultrasonic waves will be described. Here, if the image angle is θx degrees, this range is divided into, for example, four, and the first scan transmits and receives ultrasonic waves in the direction of angle −θx / 2 (direction 1), and after the next approximately Δt seconds, −
Transmission / reception is performed in the θx / 4 direction (direction 2). After 2Δt seconds and 3Δt seconds, 0 degrees (direction 3),
After transmitting and receiving in the + θx / 4 direction (direction 4), 4
After Δt seconds, in the −θx / 2 + Δθ direction (direction 5), after further 5Δt seconds, after 6Δt seconds..., -Θx / 4 + Δ
.. (direction 6), Δθ (direction 7)... Here, Δθ is the minimum scanning pitch.

Next, the gate alternate scanning method will be described with reference to the time chart shown in FIG.

FIG. 6A is a diagram showing a conventional scanning method for obtaining a two-dimensional image. First, after 4 Δt seconds after transmitting / receiving ultrasonic waves in the scanning direction 1, the adjacent scanning directions are obtained. Is transmitted / received in direction 5 which is Further, the scanning direction after 8 Δt seconds becomes the scanning direction 9 (see FIG. 1B). In other words, the transmission pulse interval needs at least 4Δt seconds because the next transmission pulse cannot be transmitted until the reflected signal from the rear end of the deepest region d is received.

On the other hand, in the gate alternating scanning method shown in FIG. 6B, ultrasonic waves are sequentially transmitted in the scanning direction 1, the scanning direction 2, and the scanning direction 3 at intervals of Δt seconds, and then the reception system After setting the directivity to the scanning direction 1 and receiving only the reflected signal from the area c for Δt seconds and transmitting the signal in the scanning direction 4, the directivity of the receiving system is set to the scanning direction 2 and the area is set to the scanning direction 2. Only the reflected signal from c is received for Δt seconds. By repeating such an operation, the scanning of the region c can be completed at four times the speed of the related art. Therefore, the number of frames of the image can be improved about four times.

By the way, when gate alternate scanning is performed when observing a fast-moving organ such as the heart, for example, an image composed of the scanning direction 1, the scanning direction 5,... .. May not be displayed continuously. Therefore, it is desirable that the scanning direction 1 and the scanning direction 2 be as close as possible.

On the other hand, it is necessary to make the angle between the above two scanning directions sufficiently large with respect to the beam width of the ultrasonic wave. Otherwise, transmission beams or reception beams overlap, or reception beams and transmission beams overlap each other. In such a case, for example, the region c in the scanning direction 1
During reception from the receiver, a reception wave from the region b in the scanning direction 2 is received, and interference may occur, thereby causing a problem that an artifact appears on an image.

In order to avoid such two conflicting problems at the same time, the width of the ultrasonic beam in transmission and reception must be reduced as much as possible. Conventionally, in order to increase the number of frames of an image, two to four stages of parallel simultaneous reception are often performed. This technique is an essential technique in real-time three-dimensional image display. However, as described above, since the transmission beam spreads the beam width, overlapping of the transmission beams becomes a particular problem.

A second point of the present invention is that a "parallel simultaneous transmission / reception method" has been realized which enables scanning in a state where not only a reception beam but also a transmission beam is sufficiently focused.

FIG. 7 is a diagram showing a parallel simultaneous transmission / reception method according to the present invention, and FIG. 8 is a diagram showing transmission delay times in a conventional parallel simultaneous reception method and a parallel simultaneous transmission / reception method according to the present invention.
Again, for simplicity of explanation, 2 centered around θ = 0
The parallel simultaneous (transmission) reception of the stages will be described.

As shown in FIG. 8A, in the conventional parallel simultaneous reception method, the transmission direction is θ = 0, the reception directions are θ = −θs and θ = + θs, and therefore, the driving pulse of the vibrator at the time of transmission is Is constant regardless of the position of the transducer (τ
s0). On the other hand, as shown in FIG. 8 (b), in the parallel simultaneous transmission / reception method of the present invention, the drive pulses at the time of transmission also include delay times τ−s and τ + s,
And strictly in the direction of θ = + θs.

In the actual apparatus, it has already been described that it is necessary to further set a delay time for focusing in transmission and reception in order to focus the ultrasonic beam in order to improve the resolution. Description of the setting of the use delay time is omitted.

Here, in the case where the above-described gate alternate scanning method and parallel simultaneous transmission / reception method are combined, the following configuration may be adopted. That is, when the above-described gate alternate scanning is performed, transmission and reception are performed in two directions of -θs and + θs around each of the scanning directions 1, 2, 3,.... For example, in transmission / reception centering on θ = −θx / 2, parallel simultaneous transmission / reception is performed in the directions of θ = −θx / 2−θs and θ = −θx / 2 + θs.

Next, two configuration examples relating to the transmission system of the parallel simultaneous transmission / reception method will be described.

First, a first configuration example of the transmission system of the parallel simultaneous transmission / reception method of the present invention will be described.

FIG. 9 is a diagram for explaining a conventional transmission system and the first configuration example.

The conventional transmission system comprises a rate signal generator 40, a transmission delay circuit 41, a pulser circuit 42, and a vibrator 43 connected in series as shown in FIG. FIG. 3A shows a rate signal generator 40, a transmission delay circuit 41,
6 shows a time chart based on each output waveform of the pulser 42.

The first transmission system of the parallel simultaneous transmission / reception method of the present invention.
9B, the rate signal generator 40 and the number of parallel simultaneous transmission systems (2 in this embodiment)
Transmission delay circuit (A44-1 and B44-2)
, An adder 45, and a pulsar circuit 42. FIG. 3B shows a rate signal generator 40, transmission delay circuits (A44-1 and B44-2), an adder 45,
4 shows a time chart based on each output waveform of the pulsar circuit 42.

The operation of the first configuration of the transmission system will be described with reference to this time chart. First, the rate signal generator 40
As in the conventional case, a pulse for determining the transmission repetition period of the ultrasonic wave is generated. In the alternate gate scanning described above, Δt
However, in the conventional scanning method, 4Δt corresponds to this. This output is applied to two transmission delay circuits (ie, transmission delay circuit A).
44-1, transmission delay circuit B44-2). Here, in the transmission delay circuit A44-1, the directivity of the transmission pulse is-
A trigger pulse having a delay time τ-s is formed so as to be in the θs direction, while the delay time τ is such that the directivity of the transmission pulse is in the + θs direction in the transmission delay circuit B44-2.
A trigger pulse having a delay time obtained by adding a constant value Tx to + s is formed. These two trigger pulses are combined (added) by the adder 45, and the pulser circuit 42
A double pulse composed of two impulses as shown in the figure is generated, and the pulse drives the vibrator 43 to generate an ultrasonic wave.

The delay times .tau.-s and .tau. + S change with the change in the transmission directivity during the sector scanning. In any case, the two impulses of the pulser output include the ringing response. The predetermined interval Tx is set so as not to overlap. For example, since the delay time used in a normal sector electronic scanning type device is 0 to 10 μsec, Tx is 20 to 30 μs.
It may be set to about ec. In this scanning method, each array transducer is driven by two pulses separated by about Tx, and emits two ultrasonic pulses. To some extent, the beam deflection delay times τ−s and τ + s of the respective channels cause After this depth, these two ultrasonic pulses are separated from each other.

For example, the transmitted ultrasonic wave radiated by the first drive has a strong directivity only in the -θ direction, and weakly weakens in the + θ direction. Conversely, the transmitted ultrasonic wave radiated by the second drive after Tx seconds has strong directivity only in the + θ direction and weakens in the −θ direction.

In this way, simultaneous transmission in two directions becomes possible by the ultrasonic waves radiated from the transducer almost simultaneously with the difference of the interval Tx. On the other hand, the receiving system has a receiving circuit having directivity in the -θ direction and the + θ direction as in the related art, so that it is possible to separate and receive the received signals in each direction. In this method, the received wave from the + θ direction is always received with a delay of Tx with respect to the received wave from the −θ direction. Must be displayed earlier by Tx, but it can be easily realized technically.

Next, a second configuration example of the transmission system of the parallel simultaneous transmission / reception method of the present invention will be described.

As shown in FIG. 10, the second configuration example includes a rate signal generator 40 and transmission delay circuits (A44-) corresponding to the number of parallel simultaneous transmission systems (two systems in this embodiment).
1 and B4-2), a waveform generator (47-1 and 47-2) connected to each transmission delay circuit, a digital adder 45, a D / A converter 46, and a vibrator drive It comprises a linear amplifier 48 and a vibrator 43.
Also, in the figure, the rate signal generator 40, the transmission delay circuits (A44-1 and B44-2), and the waveform generator (47-1)
And 47-22), and a time chart based on each output waveform of the adder 45 and the linear amplifier 48.

The operation of the second configuration of the transmission system will be described with reference to this time chart. First, the rate signal generator 40 generates a pulse for determining a transmission repetition period of an ultrasonic wave. In the alternate gate scanning described above, Δt corresponds, and in the conventional scanning method, 4t corresponds to this. The output from the rate signal generator 40 is sent to two transmission delay circuits (that is, a transmission delay circuit A 44-1 and a transmission delay circuit B 44-2). Here, in the transmission delay circuit A44-1, a series of trigger pulses having a delay time τ-s such that the directivity of the transmission pulse is in the −θ direction is formed. A trigger pulse having a delay time τ + s such that the directivity of the pulse is in the + θ direction is formed.

These two trigger pulses are, for example, R
It is sent to the waveform generators 47-1 and 47-2 composed of OM (Read Only Memory). These two
One ROM stores in advance a transmission waveform (for example, a sine wave (one wave) having the same frequency as the ultrasonic center frequency or a few sine waves having the same frequency as the ultrasonic center frequency whose envelope is Gaussian). Are stored in advance as data, and a trigger pulse for determining each read timing is supplied from the transmission delay circuit 44. Note that reading requires a clock pulse supplied from a central control circuit (not shown).

The waveform generator 47-1 and the waveform generator B47-
The outputs from 2 are combined (added) by a digital adder 45 and then converted into a drive waveform by a D / A converter 46.
This drive waveform drives the vibrator 43 via the vibrator driving linear amplifier 48. Although the timing chart shows the waveform of each output of the waveform generator 47 and the adder 45, since these components are originally digital circuits, it is impossible to actually observe such waveforms. However, for ease of explanation, they are shown after being converted into analog signals. Further, the waveform generator 47 and the adder 4
Regarding the specific configuration of the operation process 5, if the D / A converter output or the amplifier output is obtained in a form in which two drive waveforms having different delay times are combined as shown in the figure, any configuration is possible. It may be. For example, a signal equivalent to the output signal from the adder 45 may be directly calculated and generated by another calculator. In the present embodiment, the vibrator 43 is driven by the two combined drive waveforms to generate ultrasonic waves.

The delay times τ-s and τ + s change with the change in the transmission directivity during the sector scanning. Therefore, when the phases of the two waveforms match, the amplitudes are doubled. Therefore, it is necessary to design an amplifier having such amplitude characteristics. In this scanning method, each array transducer is simultaneously driven with two types of transmission drive waveforms and emits ultrasonic pulses. These ultrasonic pulses are generated by the respective beam deflection delay times τ-s and τ + s.
After a certain depth, they are separated. On the other hand, since the receiving system also has a receiving circuit having directivity in the -θ direction and the + θ direction, it is possible to separate and receive the received signals in each direction.

In each of the first configuration example and the second configuration example relating to the transmission system of the parallel simultaneous transmission and reception described above, the parallel transmission and reception directions are two directions, but the present invention is not limited to this.

By the way, when the above-mentioned parallel simultaneous transmission and reception is performed, the number of transmission pulses per unit time increases by the number of parallel stages in the transmission system according to the first configuration example (in the case of four directions, increases by four times). Also, in the second configuration example, the amplitude and wave number increase, and the transmission energy similarly increases by the number of parallel stages. In such a case, heat generation of the probe becomes a problem.

In general, it is said that the maximum condition for obtaining high image quality in an ultrasonic diagnostic apparatus is to secure a good S / N. To that end, it is desirable to put a lot of ultrasonic (acoustic) energy into the body. However, on the other hand, safety standards for living organisms are defined, and the sound pressure in the living organism or the temperature of the contact surface of the probe with the living organism must be kept within the standard value. For this reason, in the conventional apparatus, the ultrasonic energy is suppressed and emitted to the living body so as not to exceed the standard value.

In the parallel transmission method in the case of the parallel simultaneous transmission and reception according to the present invention, since the former sound pressure is transmitted to a plurality of independent parts (in the direction), the energy is dispersed so that there is no big problem. As described above, since the contact surface temperature increases by the number of parallel transmission stages, a countermeasure is required.

One of the major factors of heat generation at the probe tip is ultrasonic energy stored in the probe when left in the air. Originally, in a medical ultrasonic probe, an ultrasonic pulse propagates into a living body when its radiation surface touches the living body. When the probe radiation surface is air, the difference between the acoustic impedances of the vibrator and air is large,
The sound wave does not propagate into the air, but causes multiple reflections inside the transducer or inside the probe. The energy at that time is stored inside the probe.

Considering such a mechanism, the ultrasonic diagnosis generates a larger amount of heat during the diagnosis, that is, when the probe is separated from the living body than during the diagnosis.

FIG. 11 is a block diagram showing a configuration in a case where measures against heat generation are taken. As shown in the figure, the configuration is such that a gate circuit 25 is connected to the detection circuit 9, and an integration circuit 26, a comparator 27, and a voltage control circuit 28 are connected in series to the gate circuit 25.

FIG. 12 is a timing chart showing the principle of measures against heat generation. FIG. 2A shows a rate pulse, and a transmission pulse is emitted at the timing of the rising edge.
FIG. 3B shows a received signal (a signal after detection) when the probe is in contact with the body surface, and a reflected signal from the body is received for a long time during one rate section.
On the other hand, FIG. 7E shows a reflected signal when the probe is under an air load. A signal due to multiple reflections in the probe can be seen immediately after the transmission pulse emission, but a received signal is obtained thereafter. Disappears. If the difference between the characteristics of these received signals is determined, it is possible to automatically determine whether the probe is touching the living body.

Next, the operation of the apparatus relating to heat generation countermeasures will be described with reference to the block diagram shown in FIG. 11 and the time chart shown in FIG.

The reception signal output from the addition circuit 7 passes through a logarithmic amplifier 8 and a detection circuit 9 in the same manner as the conventional one, and a part thereof is cut out in a gate circuit 25. Is integrated by the integration circuit 26. For example, as shown in FIG. 12C or 12F, the gate circuit 25 opens after t0 from the rise of the rate pulse and closes after t1. The received signal during this time is cut out and integrated by the integrator 26. The received signal when the probe is in contact with the living body (FIG. 12 (b)) has a remarkably large amplitude in the interval t0-t1 as compared with the air load, so that the integrator output is also as shown in FIGS. As is clear from g), it is larger at the time of biological contact.

Therefore, if the output of the integrator is compared with a predetermined judgment level in the comparator 27, if it is larger, it is judged that the probe is in contact with the living body (ie, during a medical examination), and the voltage of the pulsar 3 remains unchanged. In this state, transmission of ultrasonic waves is continued. Conversely, if the output of the integrator is smaller than the determination level, it is determined that the probe has an air load, and the voltage of the pulser 3 is reduced to a predetermined level by the voltage control circuit 28. In this case, an appropriate voltage value (V0) may be selected so that the image can be observed to some extent rather than lowering to a level at which the image is completely invisible, and the heat generation is significantly lower than the standard value.

In the above method, it is determined whether or not the probe is in contact with the living body based on the reflected signal of the ultrasonic wave based on the received signal. However, another method may be used. For example, it may be detected whether or not the body of the subject (patient) or the hand of the examiner (doctor or technician) is touching the probe. Alternatively, for example, an electrostatic sensor or an infrared detection sensor may be used as the probe. It may be built in and configured to detect this by a sensor.

Next, the specific configuration and operation of the sector electronic scanning type ultrasonic diagnostic apparatus for displaying a three-dimensional image in real time will be described.

According to the gate alternate scanning method described above, the number of scans can be greatly increased when obtaining an image of a specific part in the body. In particular, it is necessary to obtain one image as in three-dimensional scanning. If many scans are required, the number of frames can be greatly improved. If such gate alternate scanning and parallel simultaneous transmission / reception methods are applied, real-time three-dimensional display by an ultrasonic diagnostic apparatus becomes possible.

As shown in FIG. 1, when an ultrasonic wave is transmitted and received through the intercostal space and an image of the mitral valve at the boundary between the left atrium and the left ventricle and its surroundings is to be observed, the depth to be diagnosed is determined in the region a. When the ultrasonic signal from the region c is obtained by dividing the region into four regions from to the region d, the above object is achieved.
However, here, the respective regions are set at equal intervals to simplify the description.

Next, the interval between transmission pulses in the present apparatus will be described. For example, in FIG. 1, the distance from the probe tip to the front end of the region c is S1, the distance from the rear end is S2,
ΔS = S2−S1, and if the speed of sound in a living body is V0,
In order to receive the reflected signal during ΔS, at least the transmission pulse interval Δt needs to be 2ΔS / V0 or more under the conditions described later.

Next, the transmitting and receiving directions of the ultrasonic waves will be described. The scanning range around the mitral valve (50 mm from the probe) is 70 mm in both the X and Y directions. However, the XY plane is set in a direction substantially perpendicular to the transmission / reception direction (Z direction) of the ultrasonic beam as shown in FIG. The scanning pitch when three-dimensionally scanning this area of 70 mm × 70 mm must be smaller than the ultrasonic beam width (resolution) of scanning transmission / reception. Here, the beam width of the ultrasonic wave is 3 mm, and the scanning pitch in the X and Y directions is 1.5 mm, which is half of the beam width. Therefore, the number of scans in each of the X and Y directions is 48,
The total number of scans is 2304.

The specifications of the sparse array transducer used to realize such a beam width will be described later. At this time, the scanning area (X-
(Y plane) is shown in FIG. The scanning area is composed of a 48 × 48 minute area, and further has two areas in the X direction.
A total of 4 areas (a, b, c, d in the figure) are 2 in the Y direction and 1
And a middle region is formed. That is, 23
The minute area of 04 is grouped into the middle area of 1/4 to 576, and the above-mentioned parallel simultaneous transmission / reception is performed in each of the grouped four minute areas.

At this time, the two-dimensional array vibrator constituting the ultrasonic probe is driven by the method shown in FIG. 9 or FIG. 10 so that the directivity coincides with the center of the micro regions a to d. Similarly, in reception, four kinds of predetermined delay times are given to the reception signals received by the transducers of the two-dimensional array so that the reception directivity coincides with the center positions of the minute areas a to d. Are synthesized. The scanning by controlling the delay time is the same as that of the conventional ultrasonic diagnostic apparatus. However, in the two-dimensional array transducer, the ultrasonic beam is two-dimensionally deflected by controlling the delay time of the drive signal. It is already widely known that this can be performed, and a detailed description thereof will be omitted.

Next, a case where the gate alternate scanning method is applied will be described below. Here, the number of stages of gate alternate scanning is four. That is, the transmission pulses for the middle regions 1 to 576 are sequentially emitted toward 1, 2, 3, 4,... 576 at intervals of Δt (see FIG. 6 for Δt). On the other hand, for reception, 1, 2, 3,.
6. The reception directivity is sequentially changed in the direction of 6.
Reception is performed with a delay of t seconds and at intervals of Δt. Alternatively, when the movement of the living body is so fast that an image shift occurs between the middle areas 12 and 13, the transmission and reception order is set to 1,
2,3,4,13,14,22,5,6,8,14
・ The order may be as described above, and the order is not limited.

Next, a method 2 for realizing such three-dimensional scanning is described.
The dimensional array will be described. FIG. 15 is a diagram showing a two-dimensional array vibrator in which 31 × 31 vibrating elements are arranged at intervals of 0.32 mm within 10 mm length and 10 mm width. The center frequency of the ultrasonic wave is 2.5 MHz. The pitch of the vibrating element is 70 mm at a distance of 50 mm already described.
When scanning the XY plane of × 70 mm, it is set based on the condition that the grating lobe does not occur even if the edge is scanned. Here, if a transmission / reception circuit is made to correspond to each of a total of 961 elements as in a conventional ultrasonic diagnostic apparatus, an extremely large-scale circuit configuration is obtained. A so-called sparse array method is adopted.

FIG. 14 shows the transmission and reception in 121
This figure shows a method of arranging each of the vibrators when using two vibrators. The transmitting vibrators are arranged around an 11 × 11 vibrator at an interval in the X and Y directions. ,
The receiving transducers are also spaced at two intervals in both the X and Y directions,
The x11 vibrator is arranged such that its center substantially coincides with the center of the transmitting vibrator group. In this arrangement, the arrangement is such that side lobes and grating lobes which cause deterioration of the SN of an image or the occurrence of artifacts in a total sound field during transmission and reception are not generated. In addition, the transmission aperture is smaller than the reception because the transmission focusing is preferably slightly weaker during the reception dynamic focusing, or the transmission aperture is large when an ultrasonic beam is incident from between the ribs. In this case, multiple reflection occurs between the probe and the rib, and an artifact is easily displayed near the probe.

FIG. 16 is a graph showing the directional characteristics of the total transmission and reception. The side lobe level is extremely small, and is a sufficiently practicable characteristic. At this time, the beam width ΔX of the ultrasonic wave in the X direction on the scanning plane XY is represented by ΔX = λR / D (or the same applies to the beam width ΔY in the Y direction). Here, λ is the ultrasonic wavelength, 0.6 mm in the case of 2.5 MHz, R is the distance of the scanning surface from the probe,
D is the total length (diameter) of the transducer array. In this case, since they are 50 mm and 10 mm, respectively, ΔX is 3 mm. Therefore, the scanning pitch on the above-described scanning plane is ΔX of 1
It turns out that 1.5 mm of / 2 is a proper value. The transmission and reception are performed while changing the directivity at intervals of Δt, and the parallel simultaneous transmission and reception is performed in each transmission and reception, so that scanning in 2304 directions can be performed in a short time.

Next, the number of frames will be described. Assuming that the thickness ΔS of each region when divided into four in the depth direction is 20 mm and the sound speed is 1500 m / s, the transmission interval Δt is set even if some margin is given in consideration of reverberation (multiplexing etc.) in a living body.
Should be about 50 μsec. Therefore, the time required for transmission and reception in the portion 576 of the middle area is about 30 msec, and the number of images (number of frames) that can be displayed per second is 35 frames. That is, by employing the gate alternate scanning method and the parallel simultaneous reception method of the present invention, a three-dimensional image having 2304 pixels can be displayed as a real-time image at a rate of 35 frames per second.

Table 1 shows more specific specifications of the real-time three-dimensional ultrasonic diagnostic apparatus employing the gate alternate scanning method and the parallel simultaneous transmission / reception method of the present invention. In this specification, the number of transmission and reception channels is 121 respectively, which is the number of transmission and reception channels 128 of the current ultrasonic diagnostic apparatus.
And about the same.

[0092]

[Table 1]

Here, the configuration of the transducer in the probe, the first-stage amplifier, the cable, the transmission / reception circuit section of the main body and the like will be described with reference to FIG. As shown in FIG. 14, two-dimensional array transducers of a sparse array include (1) a transducer commonly used in transmission and reception, (2) a transducer used only in transmission, and (3) a transducer used only in reception. There are four types of vibrators that are used and (4) vibrators that are not used.

FIG. 17A shows the configuration of a transmitting / receiving circuit connected to a transmitting / receiving vibrator, and FIG. 17B shows the configuration of a transmitting / receiving circuit connected to a pair of transmitting and receiving vibrators. ing.

The transmitting / receiving vibrator 50-1 transmits the vibrator drive signal from the pulsar 51-1 on the main body side to the cable 58-1.
Further, an input is made via a diode 154. At this time,
The preamplifier 53-1 on the main body side is protected by a limiter circuit 52-1. The impedance converter (buffer amplifier) 56-1 in the probe is also a diode 2 (55).
And diode 3 (57-1).

On the other hand, at the time of reception, a minute reception signal from the vibrator 50-1 passes through the diode 2 (55) which is in a conductive state due to the bias voltage, and is further reduced by the impedance converter 56-1. The signal is output at the output impedance and supplied to the preamplifier 53-1 in the main body via the diode 3 (57-1), the cable 58-1, and the limiter circuit 52-1.

The pair of transmitting transducers 50-2 receives the transducer driving signal from the pulsar 51-2 on the main body side through the cable 58.
-2 directly. At this time, the preamplifier 53-2 on the main body side is protected by the limiter circuit 52-2, and the impedance converter (buffer amplifier) 56-2 in the probe connected to the receiving transducer 50-3 is connected to the diode 3 (57). -2).

On the other hand, at the time of reception, a minute reception signal from the receiving oscillator 50-3 set in advance so as to be paired with the transmitting oscillator 50-2 is directly converted by the impedance converter 56-2. Output at low output impedance, diode 3 (57-2), cable 58-2,
The preamplifier 53 in the main body via the limiter circuit 52-2
-2.

When the area of the vibrating element is reduced as in a two-dimensional array, the electrical impedance of the vibrator increases. Therefore, when the vibrator is directly connected to a cable, the frequency characteristics and the gain are significantly deteriorated. Therefore, the impedance converter is housed in the probe as in the present embodiment,
It is important to reduce the output impedance of the received signal and output it to the cable. Since the transmission and reception signals are grouped as a pair as in this embodiment, even if the transducers for transmission and reception are different, the number of signal cables can be 121, which is the same as the conventional one, and the operability is excellent. 2
A dimensional array probe can be realized.

According to the present embodiment described above, even when the present ultrasonic diagnostic apparatus is used as a base, software and hardware for three-dimensional display and software for delay time control of ultrasonic transmission and reception are used. Although there are additions, no significant circuit changes are required, and an ultrasonic diagnostic apparatus having a real-time three-dimensional display capability can be realized with a circuit size and price substantially equal to those of a conventional ultrasonic diagnostic apparatus.
In addition, compatibility with tomographic image display by the conventional ultrasonic diagnostic apparatus can be ensured. That is, by mounting a new two-dimensional array probe, not only a new three-dimensional image but also a conventional two-dimensional image can be obtained with the same probe. It is also possible to display the two-dimensional image and the three-dimensional image obtained at this time in combination. Also, when obtaining only a two-dimensional image, use the same apparatus body,
If a dedicated probe is attached, an image with excellent SN ratio and resolution can be obtained. Furthermore, since it is not necessary to change the probe shape significantly compared to the conventional probe, a probe excellent in operability can be realized.

In the above embodiment, the case where a fast-moving organ such as the heart is observed has been described.
The present invention is also effective in three-dimensional display such as abdomen and obstetrics. In this case, the number of frames is half that for the heart (15 per second).
Frame), it is sufficient to use only the gate alternate scanning method or only the parallel simultaneous transmission / reception method. Even with such a configuration, the performance required from the clinical side may be satisfied.

(Second Embodiment) The second embodiment relates to a method for displaying a three-dimensional image in the real-time three-dimensional ultrasonic diagnostic apparatus.

Here, as shown in FIG. 18, a model in which a hollow spherical shell has a conical projection (phantom)
A case in which three-dimensional display is performed using will be described.

By the above-described three-dimensional scanning, three-dimensional image data is stored in a memory circuit in the apparatus. Therefore, it is possible to freely set the observation direction and perform three-dimensional display according to the manner of reconstructing the three-dimensional image data stored in the memory circuit.

In order to display an object (eg, heart) in a closed space as in the model shown in FIG. 18, it is necessary to set a cutting plane.
FIGS. 18A, 18B, and 18C schematically show three-dimensional images reconstructed by changing the position of the front cutting plane and obliquely upward in the observation direction. The positions of these cutting planes may be set at the start of data collection of the gate circuit at the time of data collection (for example, at the front end of the area c in FIG. 1), but are newly set according to instructions from the observer after data is captured. You may do so.

The position of the cutting plane can be freely set by the observer as needed and almost in real time. FIG. 18 shows observation from obliquely above, but observation from directly above may be suitable for diagnosis in some cases, and such a case can be easily dealt with. Further, the cutting plane does not need to be horizontal, and its plane can be set in any direction or at any angle. Further, as shown in FIG. 19, if the cutting plane is set at the front end and the rear end, respectively, the three-dimensional image observed from above (or obliquely above) and the three-dimensional image observed from below (or obliquely below as shown in FIG. 19). It is also possible to observe a two-dimensional image at the same time.

Incidentally, in order to secure real-time performance and resolution, the size of the region of interest for real-time display may be smaller than before. In this case, orienteering for determining the region of interest may be difficult. In such a case, the same probe is used, and the whole image is first captured by pre-scanning in which the scanning interval is made coarser than that at the time of the main inspection, and then a region for obtaining a high-quality three-dimensional image is determined. First, a conventional tomographic image is observed using the same two-dimensional array probe as shown in FIG.
After confirming the position of the region of interest, the mode may be shifted to the three-dimensional mode.

(Third Embodiment) The third embodiment relates to an ultrasonic diagnostic apparatus for improving the low flow velocity detection capability of a color Doppler.

As described above, in the coronary artery or abdominal blood vessel, the blood flow velocity is slow, and the flow velocity difference from the signal (clutter signal) from the blood vessel wall and the organs around the blood vessel does not become remarkable. In order to separate the MTI filters, an MTI filter having excellent frequency resolution is required. This frequency resolution is proportional to the number of data (ie, the number of scans in the same direction). For example, if the number of scans is doubled, the shoulder characteristic of the filter becomes twice as steep.

When diagnosing an ischemic condition based on the measurement of blood flow in the coronary artery of the heart, it is sufficient to observe a diagnostic site within a predetermined range in which the coronary artery is running. Can be applied. That is, according to the gate alternating scanning method, the number of scans per unit time in a predetermined area can be increased by 2 to 4 times as compared with the conventional case, so that the frequency resolution of the filter is improved without sacrificing the number of image frames. And the ability to detect low flow rates can be dramatically improved.

In the above-described embodiment, the focusing of the transmitting and receiving beams is not particularly described. However, a focusing point is set at an observation site (for example, a region c in FIG. 1) at the time of transmission, and the conventional method is used at the time of reception. It is desirable to apply a so-called dynamic focusing method as in the case of the ultrasonic diagnostic apparatus.

The above-described gate alternate scanning method, parallel simultaneous transmission / reception method, and method of reducing the heat generation of the probe may be used independently according to the purpose. For example, the problem of probe heating is a problem that has already become apparent even in a conventional apparatus for obtaining an ultrasonic tomographic image, and can be improved by using the present invention.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications.

[0114]

As described above, according to the ultrasonic diagnostic apparatus of the present invention, by obtaining an ultrasonic image from a predetermined limited area, the number of scans per unit time can be increased without increasing the circuit scale. Can be greatly increased.
Therefore, it is possible to relatively easily realize a real-time display such as a three-dimensional image display requiring a large number of scans in order to obtain one image, and a color Doppler display based on a low flow rate detection capability.

Further, since the same portion can be scanned about twice to four times more while maintaining the same number of frames and the same scanning line density, the low-speed blood flow detection ability is dramatically improved. This makes it possible to observe blood flow at the distal end of the coronary artery, which has been difficult until now. Moreover, the ultrasonic diagnostic apparatus according to the present invention can be realized without significantly changing the conventional apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a scanning method when diagnosing the shape and motor function of a mitral valve of a heart or a peripheral portion thereof.

FIG. 2 is a block diagram showing a schematic configuration of a sector electronic scanning type ultrasonic diagnostic apparatus.

FIG. 3 is a perspective sectional view showing a configuration of a linear array ultrasonic probe.

FIG. 4 is a graph showing spectra of a Doppler signal and a clutter signal.

FIG. 5 is a diagram showing a parallel simultaneous reception method.

FIG. 6 is a timing chart for explaining the principle of the alternate gate scanning method.

FIG. 7 is a diagram showing a parallel simultaneous transmission / reception method.

FIG. 8 is a diagram showing a transmission delay time in the parallel simultaneous transmission / reception method.

FIG. 9 is a diagram illustrating a first configuration example of a transmission system of a parallel simultaneous transmission / reception method.

FIG. 10 is a diagram showing a second configuration example of the transmission system of the parallel simultaneous transmission / reception method.

FIG. 11 is a block diagram showing a configuration in a case where measures against heat generation are taken.

FIG. 12 is a timing chart for explaining the principle of measures against heat generation.

FIG. 13 is a diagram showing a scanning area composed of 48 × 48 minute areas.

FIG. 14 is a view showing a sparse array.

FIG. 15 is a diagram showing a two-dimensional array transducer and its scanning plane.

FIG. 16 is a graph showing overall directional characteristics of transmission and reception.

FIG. 17 is a block diagram showing a configuration of a transducer in a probe, a first-stage amplifier, a cable, a transmission / reception circuit unit of a main body and the like according to a sparse array.

FIG. 18 is an explanatory diagram of a case where three-dimensional display is performed using a model (phantom) in which a conical protrusion is present in a hollow spherical shell.

FIG. 19 is a diagram illustrating a three-dimensional image when a cutting plane is set at a front end and a rear end.

FIG. 20 is a diagram showing two-dimensional and three-dimensional scanning areas when the same two-dimensional array probe is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transmission rate signal generator 2 ... Transmission delay circuit 3 ... Drive circuit (pulsar) 4 ... Ultrasonic transducer 5 ... Preamplifier 7 ... Adder 8 ... Logarithmic amplifier 9 ... Detection circuit 10 ... A / D converter 11 ... Image Memory 12: D / A converter 13: TV monitor 14: Mixer 15: π / 2 phase shifter 16: Low-pass filter 17: A / D converter 18: FFT circuit 19: Arithmetic unit 20: Reference signal generator 21: Delay Time control circuit 22 ... MTI filter

Claims (19)

[Claims] 1. An ultrasonic probe for transmitting an ultrasonic beam and receiving a reflected wave thereof, comprising: a plurality of ultrasonic transducers arranged in a row; and sequentially changing directions at predetermined direction intervals. Transmitting means for transmitting an ultrasonic beam; receiving only in a period during which a reflected wave from a specific depth region reaches the ultrasonic transducer, receiving in substantially the same direction as the transmitted ultrasonic beam that is the source of the reflected wave A receiving unit that sets a directivity to obtain a reception signal, a generation unit that performs signal processing on the reception signal obtained from the reception unit to generate an ultrasonic diagnostic image, and a display unit that displays the ultrasonic diagnostic image An ultrasonic diagnostic apparatus, comprising: 2. The transmitting means transmits a second ultrasonic beam before all reflected waves generated by transmitting the first ultrasonic beam reach the ultrasonic vibrator. The ultrasonic diagnostic apparatus according to claim 1, wherein: 3. The ultrasonic diagnostic apparatus according to claim 1, wherein a direction interval between the ultrasonic beams transmitted by the transmitting unit is wider than a width of the ultrasonic beam. 4. The ultrasonic beam transmitted by the transmitting means has a directional interval wider than a width of a received beam of the ultrasonic beam.
An ultrasonic diagnostic apparatus according to item 1. 5. The ultrasonic transducer is arranged in a two-dimensional manner, a three-dimensional space is scanned by the transmitting means, and a reflected wave from a three-dimensional area having a specific depth is provided. The reception signal is obtained by setting the reception directivity in substantially the same direction as the transmission ultrasonic beam that is the source of the reflected wave only during the period in which the ultrasonic wave reaches the ultrasonic transducer. 5. The ultrasonic diagnostic apparatus according to claim 4. 6. A vibrator group comprising a plurality of vibrators among the two-dimensionally arranged ultrasonic vibrators is a vibrator for both transmission and reception, a vibrator dedicated to transmission, or a vibrator dedicated to reception. The ultrasonic diagnostic apparatus according to claim 5, wherein the ultrasonic diagnostic apparatus is used as one of a child. 7. The ultrasonic diagnostic apparatus according to claim 6, wherein the transmission-only transducer group is provided closer to the center of the two-dimensional array than the reception-only transducer group. 8. A detecting means for detecting a Doppler signal contained in the reflected wave, wherein the generating means generates an ultrasonic Doppler image based on the Doppler signal detected by the detecting means, and the display means The ultrasonic diagnostic apparatus according to any one of claims 1 to 7, wherein the ultrasonic diagnostic apparatus displays the ultrasonic Doppler image. 9. An ultrasonic probe for transmitting an ultrasonic beam and receiving a reflected wave thereof, comprising an arrayed plural ultrasonic transducers, and sequentially changing directions at predetermined direction intervals. Transmitting means for transmitting ultrasonic beams in at least two directions substantially simultaneously; receiving means for obtaining a reception signal based on a reflected wave of the ultrasonic beam received by the ultrasonic vibrator; An ultrasonic diagnostic apparatus comprising: a generating unit that performs signal processing on the received signal to generate an ultrasonic diagnostic image; and a display unit that displays the ultrasonic diagnostic image. 10. The transmitting means comprises: a rate signal generating means for generating a rate signal; and each of the transmitting means giving a different delay time to the rate signal.
At least two transmission delay units, an addition unit that adds and outputs a rate signal from each of the transmission delay units, a driving pulse is formed based on an output of the addition unit, and the driving pulse is applied. The ultrasonic diagnostic apparatus according to claim 9, comprising: a driving unit that drives the ultrasonic vibrator. 11. The transmitting means comprises: a rate signal generating means for generating a rate signal; and providing different delay times to the rate signal.
At least two transmission delay units, storage units provided corresponding to the transmission delay units, and storing predetermined digital waveform data having timing signals from the respective transmission delay units as read timings; and reading from the storage units. Digital adding means for adding and calculating each of the output digital waveform data; converting means for converting an output from the digital adding means from a digital signal to an analog signal; and amplifying means for amplifying the analog signal from the converting means. The ultrasonic diagnostic apparatus according to claim 9, comprising: 12. The reception device according to claim 9, wherein the reception unit simultaneously obtains reception signals based on reflected waves of the ultrasonic beam in at least two directions transmitted by the transmission unit. An ultrasonic diagnostic apparatus according to claim 1. 13. The ultrasonic diagnostic apparatus according to claim 9, wherein said transmitting means transmits ultrasonic beams in at least two directions in a three-dimensional space substantially simultaneously. 14. An ultrasonic probe for transmitting an ultrasonic beam and receiving a reflected wave thereof, comprising: a plurality of ultrasonic transducers arranged in a line; and sequentially changing directions at predetermined direction intervals. Transmitting means for transmitting an ultrasonic beam,
Receiving means for obtaining a received signal based on a reflected wave of the ultrasonic beam received by the ultrasonic transducer, and generating means for performing signal processing on the received signal obtained from the receiving means to generate an ultrasonic diagnostic image And a display unit for displaying the ultrasonic diagnostic image, wherein the reflected wave continues for a specific period excluding a certain period from a rising point of a rate pulse for driving the ultrasonic vibrator. Determining means for determining whether or not the ultrasonic wave is obtained, and voltage control means for controlling a driving voltage of the ultrasonic vibrator based on a result of the determination by the determining means. Diagnostic device. 15. An ultrasonic probe for transmitting an ultrasonic beam and receiving a reflected wave thereof, comprising: a plurality of ultrasonic transducers arranged in a line; and sequentially changing directions at predetermined direction intervals. Transmitting means for transmitting an ultrasonic beam,
Receiving means for obtaining a received signal based on a reflected wave of the ultrasonic beam received by the ultrasonic transducer, and generating means for performing signal processing on the received signal obtained from the receiving means to generate an ultrasonic diagnostic image And an ultrasonic diagnostic apparatus comprising: a display unit that displays the ultrasonic diagnostic image; a detecting unit that detects whether a part of a living body is in contact with the ultrasonic probe; and a detecting unit that detects the detecting unit. An ultrasonic diagnostic apparatus, comprising: voltage control means for controlling a drive voltage of the ultrasonic transducer based on a result. 16. The ultrasonic diagnostic apparatus according to claim 15, wherein said detecting means is constituted by a means for detecting infrared rays. 17. An ultrasonic diagnostic apparatus according to claim 15, wherein said detecting means comprises means for detecting static electricity. 18. An ultrasonic probe for transmitting an ultrasonic beam and receiving its reflected wave, comprising: a plurality of ultrasonic transducers arranged two-dimensionally; Transmitting means for transmitting an ultrasonic beam while changing the frequency, receiving means for obtaining a received signal based on a reflected wave of the ultrasonic beam received by the ultrasonic transducer, and a received signal obtained from the receiving means In an ultrasonic diagnostic apparatus comprising: signal processing means for generating an ultrasonic diagnostic image, and display means for displaying the ultrasonic diagnostic image, wherein the transmitting means substantially converts the ultrasonic beam in at least a plurality of directions. Transmitting at the same time, The receiving unit sets reflected waves of the ultrasonic beams in a plurality of directions transmitted by the transmitting unit almost simultaneously to have the same directivity as these ultrasonic beams. With URN received simultaneously, the ultrasonic diagnostic apparatus characterized by obtaining only the reception signal based on the reflected wave from the 3-dimensional region of a specific depth. 19. An image reconstructing means for reconstructing a three-dimensional image viewed from an arbitrary line-of-sight direction or angle based on a reception signal obtained by the receiving means, and setting a cutting plane on the three-dimensional image. The ultrasonic diagnostic apparatus according to claim 18, further comprising: a setting unit; and a unit configured to change a region of the three-dimensional image reconstructed by the image reconstructing unit according to the cutting plane.