JPH03261466A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To optimumly control the transmission energy of a transmitting system by providing a control means for executing variable control of pulse width or a duty ratio of a driving pulse outputted from a pulser provided on the transmitting system. CONSTITUTION:In transmitting/receiving systems 2a, 3a, a burst wave number/ duty ratio setting circuit 2D is provided between a pulse generator 2A and transmission delaying circuits 2B-1-2B-M. The burst wave number/duty ratio setting circuit 2D can set variably the number of burst waves and a duty ratio of a pulse, based on the pulse inputted from the pulse generator 2A. The burst wave number/duty ratio setting circuit 2D converts a burst frequency band to a narrow band by increasing the number of burst waves. Also, at the time of reception, only the frequency band converted to a narrow band, obtained by using the burst wave number/duty ratio setting circuit 2D is extracted by a matched filter. In such a way, since an unnecessary noise of the outside of the band is eliminated remarkably, the S/N of a blood flow signal by a Doppler is improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasonic diagnostic apparatus that uses ultrasound to obtain tomographic images or blood flow information of a living body.

(Prior Art) Ultrasonic diagnostic methods that transmit ultrasonic pulses into a living body and obtain biological information from reflected waves from various tissues within the living body are free from irradiation problems like X-rays, and do not use contrast agents. It has the advantage of being able to diagnose soft tissue without the need for The ultrasonic probes in recent ultrasonic diagnostic devices are of an array type (also called an array type).

) A piezoelectric vibrator is used. Each transducer of this ultrasonic probe is driven by a drive signal to generate ultrasonic waves, and the ultrasonic waves are transmitted into the living body. By giving a predetermined delay time to the received signal obtained from within the living body to the same transducer, the ultrasound beam is focused at a predetermined distance (position) to obtain a tomographic image with excellent resolution. There is.

FIG. 5 is a schematic block diagram showing a conventional ultrasound diagnostic device;
FIG. 6 is a block diagram showing the ultrasonic probe and transmission/reception system of the sector electronic scanning type ultrasonic diagnostic apparatus. In FIG. 5, the ultrasonic diagnostic apparatus includes an ultrasonic probe 1. Transmission system 2. Receiving system 3. B-mode processing system 4. Doppler treated yarn 51 Surface water system 6
Consisting of

The B-mode processing system 4 includes a logarithmic amplifier 4A and an envelope detection circuit 4B, and the Doppler processing system 5 includes a phase detection circuit 5.
A, Color Flow Mapping 5B (hereinafter referred to as CFM5B). Doppler processing also includes spectral Doppler processing that displays temporal changes in the Doppler spectrum at a certain point within a living body, but its explanation will be omitted here.

In FIG. 6, repetitive pulses output from a pulse generator 2A that determine the intervals of ultrasound pulses emitted into the living body are output to transmission delay circuits 2B-1 to 2B-M. This repeated pulse is transmitted by transmission delay circuits 2B-1 to 2B.
-M gives a predetermined delay time determined from the transmission direction and focal point of the transmitted ultrasonic wave, and then it is sent to the transducer drive circuits (hereinafter referred to as pulsars) 2C-1 to 2C-M, and is thereby driven. A pulse is formed. By driving the M ultrasonic transducers 1-1 to 1-M, this driving pulse
The generated ultrasonic waves are transmitted into a living body (not shown).

On the other hand, the ultrasound beam reflected from within the living body is received by the ultrasound transducers 1-1 to 1-M, further sent to preamplifiers 3A-1 to 3A-M, and further sent to reception delay circuits 3B-1 to 3A-M. Sent to 3B-M. Here, the delay time given in the transmission delay circuits 2B-1 to 2B-M and the inter-path delay time are given, and added to the received signals from other transducers in the adder 3C.

Then, as shown in FIG. 5, the output signal of the adder 3C is sent on one side to the B-mode processing system 4 and on the other to the Doppler processing system 5, where predetermined signal processing is performed.

In the B-mode processing system 4, the amplitude is logarithmically converted in a logarithmic amplifier 4A, and then the envelope of the received signal is detected by an envelope detection circuit 4B and stored in a DSC (digital scan converter) 6A.

Next, in the Doppler processing system 5, the output of the adder 3C is subjected to quadrature phase detection between the ultrasonic signal frequency and a reference signal having almost the same frequency by the phase detection circuit 5A.
``The phase detection outputs having different phases are respectively stored in a buffer memory (not shown) via a low-pass filter (L-P-F) not shown.

Further, the MTI filter provided inside the CFM information detection section 5B removes the clutter signal and extracts only the Doppler component. MT! The clutter components are removed by the filter, and only the reflected waves from the blood cells are detected by the CFM information detection unit 5B.
Frequency analysis is performed by the DSC, the center or spread (dispersion) of the spectrum is calculated, and the value is
It is stored in the blood flow signal memory inside 6A. In this way, ultrasound beams are transmitted and received in predetermined directions to obtain tomographic signals and Doppler signals.

Next, by changing the amount of delay in the transmission and reception delay circuits, the direction is changed and the ultrasonic waves are transmitted and received. A tomographic image signal and a Doppler signal in this transmission/reception direction are obtained in the same manner as described above, and these are stored in the tomographic image memory and blood flow signal memory, respectively. By doing this, the inside of the living body is scanned.

(Problems to be Solved by the Invention) By the way, in the transmission system 2, there are many cases where it is necessary to control the transmission energy for some reason. In such a case, the pulsers 2C-1 to 2C-
It is conceivable to control the transmission energy by increasing and decreasing the drive voltage of M.

However, when controlling to increase the drive voltage of the pulser, the time response is slow, so the transmission energy is increased in real time to #I? There was a problem that it was not possible to do this.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that can optimally control the transmission energy of a transmission system even in real time.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems and achieve the objects, the present invention takes the following measures. The present invention provides an ultrasonic probe equipped with a plurality of transducers, a transmission system having a pulser that transmits ultrasonic waves to a subject by driving the ultrasonic probe, and a transmission system that transmits ultrasonic waves from the subject. a receiving system that receives reflected ultrasound waves from the ultrasound probe through the ultrasound probe, and an ultrasound diagnostic apparatus that collects received signals from the receiving system to obtain ultrasound information; The present invention is characterized by comprising a control means for variably controlling the pulse width or duty ratio of the drive pulse output from the pulser.

Further, the control means is characterized in that the vibrator is burst-driven and the pulse width or duty ratio of the burst wave is controlled in accordance with the burst wave number in order to keep the transmission output substantially constant.

Furthermore, the control means is characterized in that it changes the pulse width or duty ratio of the drive pulse for each vibrator of the ultrasonic probe.

(Effects) By taking such measures, the following effects are achieved. Since the pulse width or duty ratio of the drive pulse output from the pulser is variably controlled, the transmission energy of the transmission system can be optimally controlled in real time even with a constant drive voltage.

In addition, since the pulse width or duty ratio of the burst wave can be controlled according to the burst wave number to keep the transmission output approximately constant, Doppler can be S of
/N can be improved.

Furthermore, since the pulse width or duty ratio of the drive pulse can be changed for each transducer of the ultrasound probe, side lobes can be suppressed, and high-quality ultrasound images can be obtained.

(Example) Hereinafter, specific examples of the present invention will be described. 1st
The figure is a schematic block diagram showing a transmitting and receiving system as a main part of an ultrasonic diagnostic apparatus according to the present invention. FIG. 2 is a diagram showing a pulse output signal from the pulser in FIG. 1.

Note that the same parts as those shown in FIGS. 5 and 6 are designated by the same reference numerals, and the details thereof will be omitted.

The transmitting/receiving systems 2a, 3a in FIG. 1 are different from the transmitting/receiving systems 2, 3 shown in FIG. The difference is that a ratio setting circuit 2D is provided. That is, this burst wave number/duty ratio setting circuit 2D can variably set the burst wave number based on the pulses input from the pulse generator 2A, and also can vary the pulse duty ratio based on the pulses input from the pulse generator 2A. It is configurable.

For example, the burst wave number/duty ratio setting circuit 2D
is from burst wave number 2 shown in Fig. 2(a) to Fig. 2(b).
) The frequency band is narrowed by increasing the burst wave number as shown in burst wave number 8.

Further, during reception, only a narrow frequency band obtained by using a matched filter reverse burst wave number/duty ratio setting circuit 2D (not shown) is extracted. As a result, unnecessary noise outside the band is largely removed, so that the S/N of the Doppler blood flow signal can be significantly improved.

Note that here, the driving voltage is set to a constant voltage, and the burst wave number is 2.
The front and rear are the ultrasound transmission outputs to the living body.

However, the burst wave number/duty ratio setting circuit 2
When the burst wave number is significantly increased from 2 as shown in FIG. 2(a) to 8 as shown in FIG. 2(b) due to D, a large amount of ultrasonic waves will be transmitted to the living body,
Safety becomes an issue.

Therefore, the burst wave number/duty ratio setting circuit 2
By using D, the duty ratio is made small and the number of burst waves is set to 8 as shown in FIG. 2(C), thereby suppressing the total transmission energy.

In this way, the total transmission energy can be calculated as shown in Figure 2 (a
) can be suppressed in real time. Also, the sensitivity at this time deteriorates compared to Fig. 2(b), but
By narrowing the band of the signal and extracting only the desired frequency band using a matched filter, the S/N can be increased more than in FIG. 2(a).

In addition, in the pulser output, the burst wave number, duty
Since the ratio can be easily controlled in real time, when B mode and Doppler mode are displayed simultaneously as shown in FIG. For modes, see Figure 2 (a
) Switch to a burst waveform consisting of two waves as shown in (). In this way, distance resolution can be improved preferentially.

In addition, for Doppler mode, if you switch to a burst waveform with a small duty ratio and 8 waves as shown in Figure 2 (C), you can easily improve the S/N preferentially in real time. I can do it.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a schematic diagram showing the main parts of the second embodiment of the present invention;
FIG. 4 is a diagram showing a pulse output signal from the pulser in FIG. 3.

This embodiment differs from the first embodiment in that Pulsar 2C
The duty ratio of the burst wave output from -1 to 2C-M (for example, T 2 / T 1T3 / TI, T
4/TI) for each transducer 1-1 of the ultrasound probe 1.
It is characterized in that duty ratio setting circuits 2E-1 to 2E-M serving as control means for changing the duty ratio every 1-M are provided between the pulse generator 2A and the transmission delay circuits 2B-1 to 2B-M. .

That is, transmission apodization is performed in which the duty ratio of the burst wave is varied for each oscillator using the duty ratio setting circuits 2E-1 to 2E-M as shown in FIG. 4, that is, the transmission energy for each oscillator is weighted. will be carried out. In the example shown in Figure 4, the weighting is maximum and the duty ratio is 1/2.
The smaller the weighting, the lower the duty ratio.

Since the duty ratio of the drive pulse can be changed for each vibrator in this way, the transmission energy is reduced as it approaches the side of the vibrator. As a result, side lobes can be suppressed, artifacts can be reduced, and images of higher quality can be obtained.

Note that the present invention is not limited to the embodiments described above. In the embodiment, a sector electronic scanning type ultrasonic diagnostic apparatus has been described, but a linear electronic scanning type ultrasonic diagnostic apparatus may be used, for example. Furthermore, although the above-mentioned embodiments have been explained using a blood flow imaging processing system, the same can be applied to a B-mode processing system or a spectral Doppler processing system.

Furthermore, in the above-described embodiments, the case where the pulse is two or more waves has been described, but it may be one wave. However, in the case of one wave, the concept of duty ratio disappears, so if the pulse width is changed, exactly the same thing will be done.

Furthermore, if the pulse is two or more waves, the duty
Although the ratio has been explained using the case of 1/2 or less, it is not limited to this. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, the pulse width or duty ratio of the drive pulse output from the pulser is variably controlled, so even with a constant drive voltage, the transmission energy of the transmission system can be optimized in real time. can be controlled.

In addition, since the pulse width or duty ratio of the burst wave can be controlled according to the burst wave number to keep the transmission output approximately constant, Doppler can be S of
/N can be improved.

Furthermore, since the pulse width or duty ratio of the drive pulse can be changed for each transducer of the ultrasound probe, side lobes can be suppressed, making it possible to use ultrasonic diagnostic equipment that can obtain high-quality ultrasound images. Can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a transmitting/receiving system as the main part of an ultrasonic diagnostic apparatus according to the present invention, FIG. 2 is a diagram showing a pulse output signal from the pulser in FIG. 1, and FIG. FIG. 4 is a schematic diagram showing a second embodiment of the present invention, FIG. 4 is a diagram showing a pulse output signal from the pulser in FIG. 3, and FIG. 5 is a schematic block diagram showing an example of a conventional ultrasonic diagnostic device. FIG. 6 is a schematic diagram showing an example of the transmitting/receiving system in FIG. 5. 1... Ultrasonic probe, 2... Transmission system, 2A... Pulse generator, 2B... Transmission delay (b) path, 2C...
Pulser, 2D...burst wave number/duty setting circuit, 2E...duty ratio setting circuit, 3A...preamplifier, 3B...reception delay circuit, 3C...adder,
4... B mode processing system, 4A... Logarithmic amplifier, 4B
... Envelope detection circuit, 5... Doppler processing system, 5A.
... Phase detection circuit, 5B... CFM information detection section, 6.
...Display system, 6A...DSC, 6B...Monitor.

Claims (3)

[Claims] (1) An ultrasonic probe equipped with multiple transducers, a transmission system including a pulser that transmits ultrasonic waves to a subject by driving the ultrasonic probe, and reflections from the subject. An ultrasonic diagnostic apparatus comprising a receiving system that receives ultrasonic waves via the ultrasonic probe, and obtains ultrasonic information by collecting received signals from the receiving system, the pulser included in the transmitting system. An ultrasonic diagnostic apparatus characterized by comprising a control means for variably controlling the pulse width or duty ratio of a drive pulse output from the ultrasonic diagnostic apparatus. (2) The control means controls the pulse width or duty ratio of the burst wave according to the burst wave number in order to burst-drive the vibrator and keep the transmission output substantially constant. Sonic diagnostic equipment. (3) The ultrasonic diagnostic apparatus according to claim 1, wherein the control means changes the pulse width or duty ratio of the drive pulse for each vibrator of the ultrasonic probe.