JPH0414025B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention uses the pulsed Doppler method to extract only echoes from a specific depth based on the directivity of the transmission and reception of an ultrasound transducer, and to measure the moving speed of blood flow in that area. The present invention relates to an ultrasonic pulse Doppler device for detection.

[Technical background of the invention]

Ultrasonic Doppler method utilizes the fact that when ultrasound is reflected by a moving object, the frequency of the reflected wave shifts in proportion to the moving speed of the moving object, and it generates rate pulses or continuous waves of ultrasound. If a wave is transmitted into the body and the frequency shift due to the Doppler effect is obtained from the phase change of the echo, information on the movement at the depth position where the echo was obtained can be obtained.

For example, the state of blood flow at a certain position in the living body (flow direction, flow state (disturbed or regular), flow pattern, absolute value of velocity)
This information enables tests such as cardiac function.

By the way, in the early days, the Doppler method using continuous waves was studied, but this method did not provide sufficient distance resolution and it was not clear at what location blood flow information was being captured. The resulting pulsed Doppler method (a method using rate pulse ultrasound) has become mainstream.

Furthermore, in recent years, a method has been developed in which blood flow signals and real-time tomographic images by ultrasonic pulse Doppler method can be obtained using the same ultrasound probe, and it has become possible to confirm the blood flow measurement site on the tomographic image. is about to spread rapidly.

However, in the ultrasound pulsed Doppler method, if you want to capture fast blood flow information, the ultrasound transmission pulse repetition frequency (hereinafter referred to as rate frequency)
must be made higher.

On the other hand, if the rate frequency is increased, the maximum depth of field (the distance that one transmitted ultrasound pulse can go back and forth before the next transmitted ultrasound pulse is output) will become smaller, and it will be sufficiently deep from the biological surface. However, there was a drawback that information could not be obtained.

This relationship can be explained using a mathematical formula as follows. Now, if the Doppler shift frequency is d, the center frequency of the ultrasound pulse is ₀ , the blood flow velocity is v, the sound speed is C, and the angle between the ultrasound beam and the blood flow direction is θ, then d=2vcosθ/C ₀ ... ...(1) Further, if the rate frequency is r, then from the sampling theorem, the maximum detectable Doppler shift frequency d _nax is d _nax = r/2 (2). Therefore, as can be seen from the second equation, the maximum detectable blood flow velocity v _nax is limited by the rate frequency _r .

On the other hand, if the ultrasonic pulse repetition frequency (rate frequency r) is determined, the maximum depth of field x _nax will be x _nax = C/2r...(3) For example, ₀ = 2.4 MHz, C = 1500 m/s,
When r=1.2kHz, θ=30°, from equations (1), (2), and (3),
v _nax = 2.2m/sec, x _nax = 6cm.

To summarize Equations (2) and (3), it can be written as x _nax・d _nax = C/4 ...(4), and the product of the maximum depth of field x _nax and the maximum detectable Doppler shift frequency d _nax is constant. .

As described above, it is theoretically impossible to observe high blood flow rates deep from the body surface.

Therefore, as shown in Figure 1, when obtaining an ultrasound tomogram for the first time, set r = 4 kHz (x _nax = 18 cm), for example, to allow observation deep into the body surface, and freeze the desired tomogram of the body. Then, blood flow observation positions 3, 4, and 5 are stored in advance. Next, when obtaining blood flow information, increase the rate frequency r so that even high blood flow velocities can be observed, for example,
Make it possible to measure up to the Doppler shift frequency of d _nax = 4kHz when r = 8kHz. In this method, the first
All blood flow information at positions 3, 4, and 5 in the figure is obtained without being separated. Looking at the A mode waveform, 4',
The reflected signal of 5' is detected superimposed on 3'.

In this way, according to the above method, it is possible to measure fast blood flow even deeper than the body surface.
Among points 3, 4, and 5 in the figure, for example, if there is a heart wall at 3 and you want to obtain blood flow information at point 4, the echo amplitude at point 3 is too strong and the echo amplitude at point 4 is too strong. Blood flow information cannot be detected with good S/N. The reason is that the intensity of the heart wall echo is 40-60 dB greater than the blood flow signal.

Therefore, the above method has the disadvantage that blood flow information from deep parts cannot be detected without impairing S/N.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultrasonic pulse Doppler apparatus that can observe information regarding fast blood flow in deep areas without impairing S/N.

[Summary of the invention]

That is, in order to achieve the above object, the present invention transmits ultrasonic waves and detects their echo signals, obtains an ultrasonic tomographic image from this and displays it, and refers to this ultrasonic tomographic image to detect the ultrasonic wave. By specifying a desired position in a tomographic image, the echo from the inspection position corresponding to that position is extracted, and the frequency shift of the ultrasound pulse due to the Doppler effect is analyzed and its distribution is displayed. In the Doppler apparatus, ultrasonic beam transmitting means and wave receiving means are arranged at a predetermined distance apart, and the ultrasonic wave transmission and reception directions of these wave transmitting means and wave receiving means are set in the direction of the inspected position, As a result, it is possible to perform measurements with different directivity for the transmitted and received waves with respect to the inspected position, thereby eliminating the influence of the transmitted ultrasonic waves and the reflected waves from other parts. Therefore, even with fast rate pulses, it is possible to detect the reflected waves from the inspected area without any problem, and it is possible to perform deep Doppler measurement even with fast rate pulses.Moreover, it can be performed with good S/N and allows for faster blood flow velocity in the deep parts of the body. etc. can be measured with high accuracy.

[Embodiments of the invention]

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

This device uses different ultrasonic vibration elements (electroacoustic transducer elements) to transmit and receive waves when performing ultrasonic Doppler, and the details will be explained below.

FIG. 2 is a block diagram showing the configuration of this apparatus, and this embodiment shows an example of an electronic scanning type ultrasound apparatus.

Here, the electronic scanning type ultrasonic device uses an ultrasonic probe consisting of a large number of micro ultrasonic vibrating elements arranged side by side. Several adjacent micro-ultrasonic transducers are selected as a set with An excitation pulse is applied to each ultrasonic vibrating element with an appropriate delay time to excite the ultrasonic wave, and interference due to the phase difference of the ultrasonic waves from each of the excited ultrasonic vibrating elements is generated. An ultrasonic device capable of linear and sector scanning of an ultrasonic beam by electrical control to obtain an ultrasonic beam having the desired transmitting position, transmitting direction, and focal position using be.

Here, we use an electronic scanning ultrasonic device,
A tomographic image of a living body is obtained by linear electronic scanning, an observation point for performing ultrasound Doppler is determined from this tomographic image, and an ultrasound beam is transmitted to the observation point from a group of ultrasonic transducer elements for transmission, and the reflected wave ( echoes) are received by a group of ultrasonic transducer elements for wave reception.

In FIG. 2, 10 is a reference oscillator that oscillates a reference clock pulse ₀ serving as a reference signal, 11 is a frequency divider that receives this reference clock pulse ₀ and divides it into 1/250, and 12 is a group of changeover switches.

13 is a delay time control circuit that performs delay time control;
24 is a digital delay circuit composed of a shift register.

The above switch group 12, wave transmission delay circuit 1
3. There are, for example, eight systems of the digital delay circuit 24, and in the figure, each system is labeled with a suffix 1 to 8 to distinguish it.

The digital delay circuits 24-1 to 24-8 receive the reference clock pulse, count it, delay it by a given delay time, and output the reference clock pulse. The outputs of switches 1 to 24-8 are input to b input terminals of switches 12-1 to 12-8 in the respective corresponding systems of the changeover switch group 12.

In addition, in the changeover switch group 12, a frequency divider 11 is connected to the a input terminal of each switch 12-1 to 12-8.
The outputs selected by the switches 12-1 and 12-8 are transmitted to the delay circuits 14-1 and 14-14 of the corresponding systems of the switches 12-1 and 12-8. 8 and is delayed.

Further, the outputs of the respective delay circuits 14-1, .about.14-8 are output from the pulsers 15-1, .
The pulsers 15-1 to 15-8 receive the pulses from the corresponding delay circuits and generate high-voltage excitation pulses for ultrasonic excitation driving. It is something.

Reference numeral 16 represents a main control circuit that controls the entire system, and 17 represents an electronic switch that is controlled on and off by this main control circuit 16, including a plurality of switches 17-1, .
Consists of 17-64. Reference numeral 18 denotes an ultrasonic probe, which is an electronic scanning probe in which a plurality of electroacoustic transducers 18-, .about.18-64 for transmitting and receiving ultrasonic waves are arranged in parallel.

The electronic switch 17 is connected to each switch 17-
Electroacoustic transducer elements (hereinafter referred to as transducer elements) 17-1, -17 corresponding to 1, -17-64, respectively.
-64 in a 1:1 correspondence. 1
9 is a preamplifier, 8 systems of preamplifiers 19
-1, to 19-8.

These preamplifiers 19-1, -19-8 and the pulsers 15-1, -15-8 are of the first system indicated by subscript 1, and are connected to switches 17-1, 17-9, 17-8 in the electronic switch 17. 17,17
-25,..., and the second system indicated by subscript 2 is switched to switches 17-2, 17-10, 17-1.
8,..., similarly, switch 17-3, 17-11, 17-1 of the third system indicated by subscript 3 is applied.
9,... are connected to corresponding switches shifted by 8 for each system, and the desired eight switches 17-1, ~17-8, or 17-
9, ~17-17, or 17-18, ~17-
25, 17-26, .

Reference numeral 20 denotes a receiving delay line, which is composed of eight delay lines consisting of an LC delay line using an inductance L and a capacitor C, and each delay line 20-1, to 20-8 corresponds to each other. The preamplifiers 19-1 to 19-8 of the system
It is connected to the. This day line 20-
1 to 20-8 are used to apply a delay corresponding to the delay time during excitation of the conversion element of the corresponding system to the echo signal detected by the conversion element to align the time axes. Reference numeral 21 denotes an adder, which is a circuit that adds and synthesizes echo signals delayed by delay lines 20-1 to 20-8 so that their time axes coincide. 22 is a detection circuit for detecting the output of the adder 21, and 23 is a display device using a CRT (cathode ray tube) or the like for displaying images.

25-1 and 25-2 are mixers, and 26 is a phase shifter that shifts the phase of the reference clock pulse ₀ by 90 degrees.
5-2. The mixer 25-2 mixes the output of the adder 21 with a pulse shifted by 90 degrees from the reference clock pulse ₀ , and the mixer 25-1 mixes the output of the adder 21 with the reference clock pulse ₀ . conduct.

27-1 and 27-2 are low-pass filters, the low-pass filter 27-1 waves the output of the mixer 25-1 to extract low-frequency components, and the low-pass filter 27-2 mixes the output. The output of the device 25-2 is waveformed to extract low frequency components.

28-1 and 28-2 are sample and hold circuits,
Reference numeral 29 denotes a range gate setting circuit which counts based on the reference clock pulse ₀ and generates a sampling/hold control output in accordance with the echo detection timing of the set desired depth position section. The sample and hold circuits 28-1 and 28-2 receive the sample and hold control outputs and sample and hold the outputs of the corresponding low-pass filters 27-1 and 27-2, thereby obtaining the desired depth position section set above. Extract the echo detection output of

30-1 and 30-2 are band-pass filters provided corresponding to these sample-and-hold circuits 28-1 and 28-2, and 31 is a phase filter that shifts the output of the band-pass filter 30-2 by 90 degrees. 32-1, 32-2, and 33 are adders, respectively.
Adders 32-1 and 32-2 add the output of bandpass filter 30-1 and the output of phase shifter 31, respectively, and adder 33 adds these adders 32-1,
Add the outputs of 32-2.

34 is a frequency analyzer that analyzes the frequency of the output of the adder 33, and 38 is a CRT display device that displays the frequency analysis results.

Reference numeral 36 denotes a freeze circuit, which stores and reads out one desired frame of the ultrasonic tomographic image obtained by the detection circuit 22 and displays it on the display device 23. The timing of writing is determined by the control circuit 16. controlled.

37 corresponds to the depth position of the observation point to be sampled, the position of the transmitting ultrasonic transducer element group, and the delay time required for each of the ultrasonic transducer groups to obtain the transmission/reception direction with respect to the observation point given to the receiving ultrasonic transducer group. A ROM (read-only memory) 38 in which data is stored is a Doppler marker generator for receiving the output of the control circuit 16 and displaying a Doppler marker at a position corresponding to the Doppler viewpoint position on the ultrasound tomographic image.

Next, the operation of this device having the above configuration will be explained.

This device first obtains ultrasonic tomographic images, sets Doppler observation points, and then begins Doppler observation. For example, a reference clock pulse ₀ of 10 MHz output from the reference oscillator 10 is frequency-divided to 4 kHz by a frequency divider 11 that divides the frequency by 1/250, thereby creating a rate pulse with a period corresponding to the ultrasound transmission repetition period. and are applied to the a-side terminals of the changeover switch group 12, respectively. This device has a tomographic information extraction mode,
It is possible to select one of the blood information extraction modes, and these modes are selected by a changeover switch group 12, which is turned to side a when in the tomographic image information extraction mode. Therefore, when obtaining an ultrasonic tomographic image, the rate pulses are inputted to the corresponding delay circuits 14-1 to 14-8 via the changeover switch group 12, respectively. The above rate pulse is generated by the delay time control circuit 1
Wave transmission delay circuit 14 controlled by 3
After a predetermined delay time necessary for electron focusing of the ultrasonic beam is given at the pulsers 15-1 and 14-8, the pulsers 15-1 and 14-8 are supplied as drive signals to the corresponding pulsers 15-1 and 15-8, respectively. (Here, as an example, a case is shown in which eight ultrasonic transducer elements are driven simultaneously in order to focus the ultrasonic beam.)
On the other hand, electronic switches 17-1 and 17-64 provided corresponding to the ultrasonic transducer elements 18-1 and 18-64 constituting the ultrasonic probe are connected to a main control circuit so that linear electronic scanning can be performed. 16, eight pulsers 17-1, ~17-8 are turned on at the first rate, and pulsers 15-1, ~15-8 are turned on.
The output of these switches 17-
The waves are applied to corresponding ultrasonic transducer elements 18-1 and 18-8 via ultrasonic transducers 1 and 17-8, respectively. As a result, each of the vibrating elements 18-1 to 18-8 is excited and transmits ultrasonic waves. These vibration elements 18-
The ultrasonic waves transmitted from 1 to 18-8 become a beam due to interference due to their phase difference, and this ultrasonic beam is transmitted toward the inside of the living body. Then, the reflected ultrasound in the living body uses the same vibrating element 18-1 as when transmitting the wave,
After being received at ~18-8 and converted into an electrical signal,
Receiving delay circuits 20-1, 20-20 are added to preamplifiers 19-1, 19-8 via switches 17-1, 17-8, are amplified as appropriate, and are further controlled by delay time control circuit 13. -8
After a delay time comparable to that at the time of wave transmission is given to align the time axes, an adder 21 adds and synthesizes the signals.

The output of this adder 21 is detected by a detection circuit 22 and then applied to the Z-axis of a CRT display device 23 as a luminance modulation signal. On the other hand, the CRT display device 23
A deflection signal synchronized with the scanning of the ultrasonic beam is applied from the main control circuit 16 to the X and Y axes of the main control circuit 16. Then, at the next rate in the tomographic image information extraction mode, the eight switches 17-1, ~17-64, 17-2, ~17-9, which are shifted by one position, are turned on, and this time, the Sonic vibration element 18-2
Ultrasonic waves are transmitted by 18-9. Similarly, for each rate, one group of vibrating elements is used for transmitting and receiving waves.
By exciting eight new beams shifted one by one, linear electronic scanning of the ultrasonic beam is performed. As a result, an in-vivo tomographic image is displayed on the screen of the CRT display device 23.

Next, the blood flow information detection mode will be explained.
FIG. 3 shows the relationship between the tomographic image 9 obtained by the above method and the ultrasound probe 1, in which the blood vessel 8 is extracted. Now, when we want to capture blood flow information flowing at high speed at point P, we operate the operating means (not shown) and use the Doppler marker generator 38 in FIG. Display the transmit beam marker 7. Next, an instruction to freeze the tomographic image is given by an operation means (not shown), and the tomographic image is frozen by the freezing circuit 36 and displayed on the CRT display device 23.
At the same time, an instruction is given to switch to blood flow information extraction mode. moreover,
At the same time, the frequency divider 11 in FIG. 2 switches the ultrasonic transmission repetition frequency (rate frequency r) from 4 kHz to 8 kHz, for example, so that blood flow information can be sampled at a high frequency.

In this blood flow information extraction mode, selector switch 1
2 is switched to the b side, thereby shifting the shift registers 24-1 to 24-, which are digital delay circuits.
The output of 8 is the transmitting delay circuit 14-1, ~14-8.
supplied to Shift register 24-1, ~24
-8 is driven by the reference clock pulse from reference oscillator 10 to shift. shift register 2
4-1 to 24-8 are preset with data corresponding to the deflection angle θ ₁ of the ultrasonic transmission beam shown in FIG. 3 from the ROM 37. The pulses to which the shift registers 24-1 to 24-8 have given a delay time for deflection of the ultrasonic beam are sent via the changeover switch 12 to the wave transmission delay circuits 14-1 to 24-8.
After further delay time for ultrasonic beam convergence is given at 14-8, the pulsers 15-1, ~15-
8 as a drive signal. At the time of wave transmission, the electronic switches 17-1 to 17-64 are mainly controlled so that only eight of the transducer elements 18-1 to 18-64 corresponding to the transducer group A in FIG. 3 are selected. Controlled by circuit 16, pulser 15-
The outputs 1 to 15-8 are applied to the eight vibrating elements selected in this manner, and are transmitted into the living body with an ultrasonic beam deflection angle θ ₁ .

On the other hand, during reception, the switches 17-1 to 17-64 are controlled so that only the eight vibrating elements corresponding to the vibrating element group B in FIG. 3 are selected, and the selected eight vibrating elements Reflected ultrasound waves from inside the living body are received and blood flow signals are extracted. One way to select the vibrating element group B is to select the deflection angle θ ₁ of the transmitted ultrasonic beam, the distance d _T between A and P, the distance d _R between B and P, and the deflection angle of the received echo in FIG. is θ ₂ , the distance R between A and B is calculated as follows: R=√ ² _T + ² _R −2 _{T R} ( ₁ + ₂ ) …(5) By storing the correspondence relationship between B and the distance R in the ROM in the main control circuit, it is possible to select the vibrating element group B in conjunction with the sample marker P.

The above received signals obtained by the transducer group B are each amplified by preamplifiers 19-1 to 19-8, and the delay time for receiving ultrasound beam deflection and ultrasound beam convergence is used for reception. After being given by the delay circuits 20-1 to 20-8, the adder 21
is synthesized with

This composite signal is input to mixers 25-1 and 25-2, where it is mixed with a reference clock and a signal obtained by shifting the phase of ₀ by 90 degrees in a phase shifter 26, and then further passed through a low-pass filter 27-1. , 27-2, only the Doppler shift frequency component d is extracted.

This Doppler shift frequency component is then applied to sample and hold circuits 28-1 and 28-2.
In order to obtain a blood flow signal at point P in FIG.
= t ₂ - _{t 1} (however, t ₂ is the time for the ultrasonic wave to pass between A-P and B-P, and t ₁ is (rate frequency) ^-1 )
By sampling and holding the pulses with a time delay of 0.05, only the signal component from the sample marker portion 4 in FIG. 3 is extracted. This relationship will be explained in more detail using FIG. Waveform a is a rate pulse signal, for example r = 8kHz (t ₁ = 125μsec)
It is. Furthermore, waveform b is an excitation pulse signal for ultrasonic excitation, and waveform e is a received echo signal from point P in Figure 3, and the received echo at point P is the output of the excitation pulse at the following rate. From the timing,
Sample and hold is performed at time t ₂ - _{t 1} .

Next, the sample-and-hold output signal passes through bandpass filters 30-1 and 30-2, and the Doppler signal due to the blood flow, which moves slower than the blood flow, appears as a low-frequency signal. Only the deviation frequency d is extracted. and,
The outputs of filters 30-1 and 30-2 are 90° phase shifter 31, adders 32-1 and 32-2, and adder 3.
After the forward flow and backward flow of blood flow are determined and synthesized in step 3, the frequency, that is, the Doppler shift frequency due to the blood flow, is analyzed by a frequency analyzer 34 and displayed on the screen of a CRT display device 35.

According to the above configuration, in the ultrasound Doppler mode, the Doppler observation point is determined while looking at the ultrasound tomographic image,
In addition, the ultrasonic vibrating element group for ultrasonic wave transmission and the ultrasonic vibrating element group for ultrasonic wave reception are different, and the ultrasonic vibrating elements of the probe are selectively used so that the transmitting and receiving positions are different. Since measurements are made with different directivity for the transmitted and received waves to the observation point, it is now possible to detect reflected waves from the observation point without being affected by the transmitted ultrasonic waves. Therefore, even with a fast rate pulse, deep Doppler measurement is possible and can be performed with good S/N, so faster blood flow velocity in the deep part of the living body can be captured without deteriorating S/N.

Therefore, it is useful for detecting the velocity of jet flow in patients with mitral valve stenosis, for example.

Note that the ultrasonic probe that can be used in the present invention is not limited to one in which ultrasonic vibration elements are arranged in a line.

Although the above embodiments are based on the electronic scanning method, the present invention can also be implemented using two probes each using a single ultrasonic transducer. The embodiment will be described below with reference to FIG.

Here, a case will be described in which a total of two probes are used, one for transmitting waves and one for receiving waves.

In this device, a wave transmitting probe 61 and a wave receiving probe 62 are arranged at a predetermined distance apart, and the ultrasonic beam transmitting/receiving direction of each probe is set so as to face a desired observation point A of the living body.

In such a state, the reference signal generation circuit 6
When a reference pulse is given to the rate pulse generation circuit 64 from 3, the rate pulse generation circuit 64 divides the frequency of the reference pulse to generate a rate signal for repeatedly transmitting ultrasonic pulses. This rate signal is given to the wave transmitting circuit 65 to drive the wave transmitting probe 61 and transmit an ultrasonic pulse.

On the other hand, another wave receiving probe 62 receives echoes from the wave transmitting/receiving area Z where the wave transmitting probe 61 and the wave receiving probe 62 overlap each other. The electrical signal from this wave receiving probe 62 is transmitted to the wave receiving circuit 6.
6, where it is amplified and input to mixers 67a and 67b, respectively. Mixer 67a, 6
7b receives one of the different reference signals from a phase shifter 70 that converts the output of the reference signal generation circuit 63 into two reference signals having a phase difference of 90 degrees,
Each is mixed with its different reference signal and phase detected. As a result, signals each having a difference from the reference signal are extracted.

In other words, with a reference signal with a 90 degree phase difference,
On the one hand, those with earlier frequency shifts are extracted, and on the other hand, those with later frequency shifts are extracted.

The thus extracted phase-detected signals are extracted by range gate circuits 71a and 71b which apply a time gate to extract only the signal corresponding to a predetermined position and extract the signal within the gate. That is, in order to extract a signal at a position corresponding to the observation point A position, a range gate is applied to extract a signal corresponding to the position.

Thereafter, the signal is passed through bandpass filters 68a and 68b to remove the effects of large echoes such as the walls of organs and remove harmonics caused by range gates, and then sent to a frequency analyzer 69. In other words, if the observation site is the heart, the effects of the moving heart's septum and boundaries with other tissues, and if the target is blood vessels, the effects of the vessel walls (these move slower than the blood flow, so they can be removed by cutting out the low frequencies) ) and range gate harmonics are removed.

And, these band pass filters 68a, 68
The signal passed through b is sent to a frequency analyzer 69 for frequency analysis, and the distribution of frequency deviation of the echo within the range gate is analyzed from both signals. The results of this analysis are sent to a display device 72 such as a TV monitor or a recorder (not shown), where they are displayed or recorded. Thereby, velocity information such as blood flow at the observation point A position can be known. In this case, interference of velocity information due to echoes from a position C/2r away, as in the conventional pulsed Doppler method, can be prevented by the directivity of the probe, making it possible to observe deep parts of the living body. Further, the wave transmitting probe 61 can also be used for UCG image display using the conventional echo method. Further, the wave transmitting probe 61 is also connected to the M mode wave receiving circuit 73,
The output of the wave receiving circuit 73 is detected by the wave transmitting circuit 74 having logarithmic characteristics, and is sent to the display system at the same time as the output of the frequency analyzer 69, and is displayed on the display device 72, so that it can be observed together with the M mode image. can.

Although an example has been described above in which one wave transmitting probe and one wave receiving probe are used, for example, one of the transmitting and receiving probes may be an electronic scanning type probe. Further, the wave transmitting probe and the wave receiving probe may be integrally attached to the same probe at a predetermined distance apart.

〔Effect of the invention〕

As described in detail above, the present invention transmits ultrasonic waves and detects their echo signals, obtains an ultrasonic tomographic image from this, displays it, and refers to the ultrasonic tomographic image. A Doppler system that specifies a desired position in an image, extracts the echo from the inspection position corresponding to that position, analyzes the frequency shift of the ultrasound pulse due to the Doppler effect, and displays its distribution. In the apparatus, ultrasonic beam transmitting means and wave receiving means are arranged at a predetermined distance apart, and the ultrasonic wave transmission and reception directions of these wave transmitting means and wave receiving means are set in the direction of the inspected position. This makes it possible to perform measurements with different directivity for the transmitted and received waves at the inspected position, so there is no possibility that the measurement will be affected by the transmitted ultrasonic waves or reflected waves from other parts. It is now possible to detect reflected waves from the inspected area without
Therefore, it is possible to perform deep Doppler measurements even with fast rate pulses, and because it can be performed with good S/N, it is possible to accurately measure faster blood flow velocities in the deeper parts of the body, making it extremely useful for diagnosis, making it a breakthrough. It is possible to provide a typical ultrasonic pulsed Doppler device.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the drawbacks of the conventional example, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG.
4 is a time chart for explaining the operation of the present invention, and FIG. 5 is a block diagram showing another embodiment of the present invention. 10... Reference oscillator, 11... Frequency divider, 12... Switch, 13... Delay time control circuit, 14... Delay circuit, 15... Pulser, 16... Control circuit, 17... Switch, 18... Ultrasonic vibration element, 19... Preamplifier , 20...day line, 21, 32-1, 3
2-2, 33... adder, 22, 74... detection circuit,
23, 35, 72...Display device, 25-1, 25-
2... Mixer, 26, 31, 70... Phase shifter, 27-
1,27-2...low-pass filter, 28-1,28-
2...Sample hold circuit, 29...Range gate setting circuit, 30-1, 30-2, 68a, 68b
... band pass filter, 34, 69 ... frequency analyzer, 36 ... freeze circuit, 38 ... Doppler marker generator, 61, 62 ... probe, 63 ... reference signal generation circuit, 64 ... rate pulse generation circuit, 65 ... wave transmission circuit, 66, 73...Receiving circuit, 71a, 71b
...Range gate circuit.

Claims (1)

[Claims] 1. An ultrasonic wave transmitting means for transmitting ultrasonic waves toward a Doppler observation point, and this ultrasonic wave transmitting means are located at different positions, and from a direction different from the wave transmitting direction,
An ultrasonic wave receiving means that receives reflected waves from this Doppler observation point, and an ultrasonic wave receiving means that transmits ultrasonic waves and receives the reflected waves at a period shorter than the time it takes to transmit the ultrasonic waves and receive the reflected waves. An ultrasonic pulse Doppler apparatus comprising: a driving means for driving; and a Doppler analysis means for performing a Doppler analysis of the received reflected waves.