JPH01204653A - Ultrasonic doppler device - Google Patents

Abstract

PURPOSE:To enable the measurement and display of the absolute velocity and vector velocity of a moving reflector by radiating a plurality of ultrasonic beams on the same site at defined deflection angles. CONSTITUTION:Mutually different frequency signals are fed from a transmitting portion 100 to two groups of oscillators in a probe 12, and ultrasonic beams are radiated from the groups of oscillators with a certain interval onto defined sites. The echo signals thereof are received by two receiving portions 200A and 200B respectively via the same group of oscillators. After the signals are converted into complex signals having mutually different phases, the deviation frequency of a carrier frequency is operated from these complex signals. The deviation frequency signals outputted from the receiving portions 200A, 200B are fed into a vector velocity operating portion 36, where the operation of absolute velocity is carried out. The absolute velocity is fed to a display 38 and the moving condition of a moving reflector such as blood is displayed by spectrum by means of absolute velocity. The vector velocity operating portion 36 can also measure a moving direction. The moving direction is suitable at the time of displaying a velocity condition being superposed on a fault image in a B mode.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an ultrasonic Doppler device, and particularly to an ultrasonic Doppler device that accurately displays the speed and other conditions of a moving reflector such as blood flow on a screen. .

[Prior Art] Ultrasonic Doppler devices are well known that display an image of the motion state of a moving reflector by emitting ultrasound beams into a living body at a constant repetition period or continuously. The velocity distribution state of the reflector is determined by receiving reflected echoes from the reflector and detecting the Doppler effect on the reflected echoes as a frequency shift of the ultrasonic carrier frequency.

Therefore, by properly detecting the Doppler shift frequency, it is possible to accurately display an image of the blood flow and body temperature in the living body, especially the motion state of the cardiac blood flow. The image display can be performed according to the purpose, such as M mode, which shows changes in the velocity as a waveform, spectrum display, which displays the spectrum of velocity (deviation frequency), or B mode, which displays the velocity distribution state superimposed on the tomographic image. ing.

[Problems to be Solved by the Invention] However, since the Doppler effect on ultrasound only shows changes in velocity along the radiation of the ultrasound beam, a reflector that moves along the beam line is good, but other reflectors are An accurate Δ-1 constant could not be determined for the speed of .

That is, as shown in FIG. 5, when emitting an ultrasound beam from the probe 12 to the blood vessel 10 to determine the velocity of blood flow, the velocity Va at which the ultrasound beam can be detected as the Doppler effect is , if the velocity of blood flow is V, then Va-Vc
It becomes osθ. Therefore, there is a problem in that an error occurs in the detected speed by the speed V-Va, and the direction of the speed cannot be detected accurately.

Conventionally, as a device for determining the vector velocity of a motion reflector, there is a device such as that shown in Japanese Patent Application No. 60-292112.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide an ultrasonic Doppler device capable of detecting an accurate motion state based on the absolute velocity of a motion reflector in a hub.
It's about doing.

[Means for Solving the Problems] In order to achieve the above object, the present invention demodulates a reflected echo signal from a moving reflector and detects a Doppler shift frequency, thereby obtaining an image of the moving state of the reflector. The ultrasonic Doppler device used for displaying uses one probe with a large number of transducers arranged, the transducer array within this probe is divided into multiple transducer groups, and the divided transducer groups are A transceiver unit that sends and receives multiple ultrasound beams from different directions to the same area by electronic scanning, and a vector velocity calculation that calculates vector velocities from multiple Doppler shift frequencies obtained by this transceiver unit. It is characterized by comprising:

[Operation] According to the second configuration, a plurality of transducers in one probe; Ultrasonic beams are emitted from different directions toward the same identified site. In this case, the angle of intersection of the two ultrasonic beams is deflection-controlled in advance so that it becomes a predetermined angle. The two reflected echoes from this site are received by the same transducer group, and the Doppler shift frequencies of the two received signals are detected.

This Doppler shift frequency information is supplied to a vector velocity calculation unit, where, for example, a vector velocity is calculated from two frequency information and the intersection angle of the ultrasound beam, and the two frequency information are converted into ΔfA, Δf8, and the intersection angle. When θ is assumed, the absolute velocity V is as follows, and from this, the absolute velocity and direction of motion of the moving body can be accurately determined.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a block circuit schematically configuring an ultrasonic Doppler apparatus according to a first embodiment of the present invention, in which a probe 12 that emits ultrasonic waves includes a plurality of transducers, For example, one in which 64 or 128 vibrators are arranged is used.

A characteristic feature of the present invention is that the ultrasonic beams are angularly deflected by electronic scanning from different directions of the same probe and emitted toward the same site, and the probes 12 are driven simultaneously. It is divided into multiple transducer groups. In other words, in the present invention, it is important that the current number of ultrasonic beams that intersect at the detection site (sample volume) form a predetermined angle. is set to meet the conditions specified. This intersection angle is determined from the distance between the transducer groups, that is, the distance between the multiple ultrasound beams emitted from the probe 12, and the distance to the detection site (distance 1111 from the probe 12). can be specified. In the first embodiment, a case will be described in which the ultrasound beams are divided into two groups of transducers and performed using two ultrasound beams.

First, a transmitting section 100 that supplies a transmitting signal for ultrasonic radiation to the probe 12 is composed of an oscillation circuit 13, two frequency setting circuits 14a, 14b, and a drive circuit 16, and has two types of frequencies. The transmission signal (oscillator excitation signal) can be supplied. In the present invention, it is possible to use one type of ultrasonic wave (frequency) and emit them simultaneously or with a slight time difference, but in order to avoid interference between ultrasonic waves, in the embodiment, two types of ultrasonic waves with different frequencies are used. Ultrasonic beam (
A and B) are emitted toward the same site.

In Fig. 2, Fig. (a) shows a state in which the two ultrasound beams are radiated to a blood vessel (site S), and Fig.
An enlarged view of the detection area S is shown in b). When the ultrasonic beams A and B are emitted toward 8 points as shown in the figure, 2
The intersection angle of the two beams is Δθ. Then, the angle formed by the radiation direction of ultrasonic beam A and the blood flow direction is θ
Then, the speed detected by each ultrasound beam A and B is
Va-Vcos θ, Vb-Vcos (θ + Δθ).

Therefore, as will be described later, the true velocity (absolute velocity) ■ and the direction of movement θ are determined from Va, Vb, and Δθ.

Further, the receiving section 200 that receives the echo waves received by the probe 12 includes an electronic scanning receiver 1g, two quadrature detectors 20a and 20b, and a π/
High-pass filters 26a, 26b, two low-pass filters 28 of phase shifter 22.2f14 giving a phase change of 2
a, 28b, two amplifiers 30a, 30b, two A/
It is composed of a D (7oG digital) conversion aW 32a, 32b and an FFT 34 as a frequency analyzer, and the phase shifter 22 inputs the signal from the oscillation circuit 13,
This receiving section 200 has the same configuration as a conventional ultrasonic Doppler device. This receiving section 200 is provided corresponding to the number of ultrasound beams emitted simultaneously or with a slight time difference, and in the embodiment, the receiving section 200A has the same configuration for the ultrasound beams A and B.

200B is provided.

According to this receiving section 200, the echo signal is treated as a complex signal consisting of a real part and an imaginary part, and thereby F
The FT 34 outputs a shift frequency in the ultrasound carrier frequency, and since this shift frequency is a result of the Doppler effect, it indicates the velocity in each ultrasound beam direction.

Next, the receiving sections 200A and 200B are provided with a vector I-le velocity calculating section 36 that manually inputs the signals outputted from these, and thereby calculates the vector speed of the motion reflector. The calculation of this vector velocity will be briefly explained using an equation.

Assuming that ultrasound beams A and B are simultaneously emitted to the same site S as shown in Figure 2, Doppler shift frequencies Δ[A (for ultrasound A), ΔfB (for ultrasound A), ΔfB (for ultrasound B) is as follows.

ΔfA-(2V/c) focos O・(1) Δf,
, = (2V/c) fa cos (θ + Δθ)
... (2) Here, the above C is F in the medium? velocity, ■ is the absolute velocity of the motion reflector (blood flow), θ is the angle formed by the ultrasound beam A direction and the self-flow direction, ΔO is the intersection angle of the two ultrasound beams, f
O is the ultrasound frequency.

Therefore, in equations (1) and (2) above, ΔfA, Δ'I
is determined by the Al1 constant, and c, V, Δθ, and fo are known values, so the vector velocity can be calculated using the above two equations, for example, from the following equation.

That is, (Δ[ −ΔfA)/Δθ − (2V/c)fo ・ (cos (θ+Δθ) −cosθ)/Δθ= (
2V/c)fo ・((cosθcosΔθ/Δθ) (sinθsinΔ0/Δθ) −(cos O/Δθ)) −(2V/c)fo (−sin O>Therefore, Δf13−ΔfA−1ll−2vfOΔθsinθ/C
...(3) Then, by eliminating θ using the above equations (1) and (3), v2 is obtained. Therefore, ...(4) is obtained.

The embodiment has the above configuration, and its operation will be explained below.

First, different frequency signals are transmitted from the transmitter 100 to the probe 12.
0 (0) is supplied to the two transducer groups in the
Ultrasonic beams are emitted from the two transducer groups to a predetermined site S. Then, the echo signals are received by the two receiving sections 200A and 200B via the same transducer group, and the electronic scanning receiver 1 in the receiving section 200
The echo signal received at 8 is transmitted to quadrature detectors 20a, 2
At 0b, the signals are converted into tow signals having phases different from each other by π/2, and predetermined signal processing is performed on each of the tow signals.

That is, the high-pass filter 26 and the low-pass filter 2
8 removes unnecessary signal components and noise components, and this signal is amplified by an amplifier 30 at a predetermined amplification factor.

Then, the output signal of the amplifier 30 is converted into a digital signal by the A/D converter 32, and then supplied to the FFT 34. Since the outputs of the two amplifiers 30a and 30b correspond to signals (real part and imaginary part) constituting the tow signal, the FFT 34 calculates the shift frequency of the carrier frequency from this 1SL tow signal. become.

In this way, the shift frequency signals output from the receiving sections 200A and 200B are supplied to the vector velocity calculator 36, where the absolute velocity is computed based on equation (4) above.

Since the absolute velocity is supplied to the display 38, the motion state of the motion reflector is displayed on the display 38 in spectrum (or M mode) based on the absolute velocity, thereby allowing accurate motion state to be grasped.

In addition, the vector velocity calculator 36 calculates not only absolute velocity but also
The direction of movement can also be measured. That is, regarding the velocity Va of the ultrasonic beam A, since Va-Vcosθ holds true, 0-eos'' (Va/V) - (5)
The direction of blood flow movement can be determined by:

This direction of movement is suitable for displaying the velocity state by 1n on the B-mode tomographic image, and thereby allows the actual blood flow state to be accurately observed on both edges.

Next, a second embodiment of the present invention will be described in which velocity is detected using three ultrasonic beams.

FIG. 3 shows a state in which three ultrasonic beams are radiated to a predetermined portion of blood flow, and FIG. 4 shows a circuit block in this case.

As shown in FIG. 3, according to the three ultrasonic beams, the motion state of the region S is determined by three velocity values Va, Vb.
, Vc.

Therefore, the difference in the configuration in FIG. 4 from the configuration in FIG. 1 is that the transmitter 100 has three frequency setting circuits 14a, 1
4b and 14c are provided, and a drive circuit 16 forms a transducer excitation signal of a predetermined frequency, and the ultrasonic beam is angularly deflected and radiated toward the detection site S. In this case as well, ultrasonic waves of the same frequency may be used as in the first embodiment, but in order to avoid interference, ultrasonic waves of three different frequencies are used in the second embodiment as well.

On the other hand, the transmitting section 200 is also provided with three transmitting sections 20QA, 200B, and 200C corresponding to the three ultrasound beams, and their internal configurations are the same as in the first embodiment.

According to the third embodiment, there is an advantage that vector velocity can be measured with high accuracy. In other words, the greater the number of data, the more reliable the calculated value becomes.For example, when using two ultrasound beams, depending on the direction of the moving reflector, one of the detection speeds may be a small value that is inappropriate as a measurement value. As a result, the accuracy of vector velocity detection may deteriorate. According to the third embodiment, this problem can be resolved and velocity can be detected accurately.

[Effects of the Invention] As explained above, according to the present invention, since a plurality of ultrasonic beams are radiated to the same part at a predetermined deflection angle, the absolute velocity or direction of motion of the motion reflector is It has the advantage of being able to measure and display vector velocities, including vector velocities, and provide information useful for image diagnosis.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing a schematic configuration of an ultrasound Doppler apparatus according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram showing a detection state when two ultrasound beams are emitted, and FIG. is an explanatory diagram showing the detection state when three ultrasonic beams are emitted. 12... Probe 14... Frequency setting circuit 16... Drive circuit 18... Electronic scanning receiver 34... FFT 36... Vector velocity Arithmetic section 38...Display section 100...Transmission section 200...Reception section.

Claims (3)

[Claims] (1) In an ultrasonic Doppler device that displays an image of the moving state of a reflector by demodulating the reflected echo signal from a moving reflector and detecting the Doppler shift frequency, a single device with a large number of transducers arranged The probe and the transducer array within this probe are divided into multiple transducer groups, and the divided transducer groups are electronically scanned to direct multiple ultrasound beams from different directions to the same site. 1. An ultrasound Doppler apparatus comprising: a transmitting/receiving section that transmits and receives waves, and a vector velocity calculating section that calculates a vector velocity from a plurality of Doppler shift frequencies obtained by the transmitting/receiving section. (2) The ultrasonic Doppler apparatus according to claim (1), wherein the transmitter/receiver section transmits and receives ultrasonic beams of different frequencies in order to eliminate interference between the ultrasonic beams. (3) The ultrasonic Doppler apparatus according to claim (1), wherein the transmitter/receiver section manually or automatically changes the angle at which different ultrasonic beams intersect at a predetermined location.