JPS59155242A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention provides a method for arranging a plurality of ultrasonic transducers in an array,
The present invention relates to an ultrasonic diagnostic apparatus that deflects an ultrasonic beam by transmitting and receiving a delay time to some or all of the ultrasonic transducers.

[Technical background of the invention and its problems]

FIG. 1 is a diagram for explaining the directivity of a rectangular vibrator.

The directivity R of the rectangular vibrator 1 shown in FIG. 1 in a far sound field is generally expressed as follows.

(A: [Math) Here, if we focus only on the xz plane in FIG. 1, we get the following equation.

(γ=−−α) FIG. 2 is a diagram showing the directivity characteristics when ultrasonic waves are transmitted from a rectangular vibrator. From the previous equation (2) and Figure 2, it can be said that the directivity of a rectangular vibrator in a far sound field is as follows: When the frequency is one foot, the wider the aperture width is, and when the aperture width is constant, the frequency is The higher the value, the sharper the directivity. Due to this effect, when rectangular vibrators are arranged in a play shape and deflected with a certain delay time, the sound pressure on the central axis is lower than when not deflected.

As mentioned above, the tendency is also sharper when the frequency is high and when the aperture width is wide.

In recent years, ultrasonic diagnostic equipment has begun to focus on higher frequencies in order to improve distance resolution and directional resolution. Generally, due to problems in manufacturing the vibrator, the method of filtering the received waves and extracting the high-frequency components is generally used.

However, due to attenuation within the subject, the center frequency of the spectrum of the transmitted wave moves to a lower level deep within the subject. Therefore, as shown in Figure 6, the center frequency of the spectrum of the filter output is set to be lower as the depth inside the object increases, and at the same time, the sound pressure also decreases as the depth inside the object increases. Conventionally, sound pressure correction has been performed using a method of changing sensitivity depending on the depth of the object, that is, a 510 circuit.

However, the decrease in sound pressure is caused not only by attenuation deep inside the subject, but also by the directional characteristics of the transducer due to the deflection of the ultrasound beam, which conventionally did not need to be considered because the frequency was low. The decrease in sound pressure that occurs when the frequency increases can no longer be ignored. In other words, as is clear from Figure 4, which shows the relationship between the depth of the object and the sound pressure on the center axis at each deflection angle, the sound pressure decreases at a shallow depth of the object and when the deflection angle is large. intense. For example, when a B-mode image fT or V is displayed on a monitor in this state, a phenomenon occurs in which the image becomes darker as the object is shallower and more deflected.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides an ultrasonic diagnostic apparatus that can obtain a clear monitor image even when deflecting an ultrasonic beam using a high frequency, and has excellent distance resolution and azimuth resolution. The purpose is to

[Summary of the invention]

To achieve the above object, the present invention provides a sound pressure correction means that performs sound pressure correction according to the depth of the object and the deflection angle of the ultrasonic beam to the received ultrasonic waves. 7 [Embodiments of the Invention] Examples of the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram showing one embodiment of the present invention.

In the figure, reference numeral 2 indicates a transmitting/receiving controller. The transmitting/receiving controller 2 generates a rate (ratg) signal. 3 is a transmission delay unit that performs phase control for deflection and focusing, and generates pulse signals for driving a plurality of ultrasonic transducers (not shown) arranged in the transducer 4. is occurring. A plurality of ultrasonic transducers (not shown) arranged in the transducer 4 transmit ultrasonic waves to a subject (hereinafter referred to as a living body 5).

It also receives ultrasound reflected from the subject and converts the received ultrasound into an electrical signal as an echo signal.

Reference numeral 5 denotes a reception delay section which performs phase control on the echo signal for deflection and focusing, and converts it into a 9-signal by addition. Reference numeral 6' denotes a filter controller, which functions to change the filter constant of the bandpass filter 6. The bandpass filter 6 extracts frequency components within a permissible range depending on the depth of the living body from among the frequency components of the echo signal. 7 is an llog amplifier, and b l'! is used to widen the dynamic range. ! Perform compression.

Reference numeral 8 denotes a detection section, which performs full-wave rectification of the echo signal and extracts its envelope i. 9 is STC (Sg
nzitivgty ControlL) Department,
This is a sound pressure corrector/stage that performs sound pressure correction according to the depth of the living body and sound pressure correction according to the deflection angle of the ultrasound beam.

10 indicates DECCD1g1tat 5can
Converter) unit processes the echo signal sent from the src unit 9 as an entire video signal. Reference numeral 11 denotes a monitor, which displays images based on the video signal from the DSC unit.

Next, the operation of the above configuration will be described.

The rate signal generated by the transmitting/receiving controller 2 is as follows.

Transmission delay unit 6. Reception delay section 5. The signal is input to the filter controller 6', the src section 9, and the DSC section 10 as respective control signals. The transmission delay unit 6 has the above-mentioned τat
Perform phase control for deflection and focusing based on the e signal,
A pulse signal for driving a plurality of ultrasonic transducers arranged in the transducer 4 is generated. The transducer 4 vibrates each ultrasonic transducer according to the pulse signal from the transmission delay unit 6, transmits the ultrasonic wave to the living body, receives the ultrasonic wave reflected from the living body, and generates a plurality of echoes. The signal is sent to the reception delay section 5 as a signal. Reception delay section 5
transmits the plurality of echo signals to the transmitting/receiving controller 2.
After performing phase control based on the rαtg signal from the echo signal, the signal is added and converted into one echo signal, which is sent to the bandpass filter 6 at the next stage. The bandpass filter 6 extracts the highest frequency range allowed according to each depth of the living body from the signal components of the echo signal sent from the reception delay section 5. In this case, as mentioned above, it is advantageous for the ultrasonic frequency to be as high as possible in order to improve the distance resolution and azimuth resolution of the ultrasonic diagnostic apparatus.

This is because the high-frequency component of the ultrasonic wave is considered to be highly attenuated deep in the living body, and the constant number of filters of the bandpass filter 6 is determined by the
It is controlled by a control signal from a filter controller 6' based on the signal. The echo signal that has passed through the bandpass filter 6 is.

Next, the signal is subjected to llo data compression in the 1lol amplifier 7, and is further subjected to full-wave rectification in the detection section 8, after which it is input to the 510 section 9. 510 part 9 is γ from the transmitting/receiving controller 2
Sound pressure correction according to the depth of the living body based on the α1g signal,
Performs sound pressure correction according to the deflection angle of the ultrasound beam. In other words, it works to increase the sensitivity to echo signals from deep inside the living body, and when the deflection angle of the ultrasound beam is large, it works to increase the sensitivity to echo signals from shallow parts of the living body. It is. Next 510
The Echoi= issue for which sound pressure correction was performed in Section 9 is DS.
In section C, after video processing is performed based on the rat-signal from the transmission/reception controller 2, the image is displayed on the monitor 11. As mentioned above, the image on this monitor 11 is subjected to sound pressure correction according to the deflection angle of the ultrasound beam in the 510 unit 9, so even when the deflection angle is large, the image becomes dark at shallow parts of the living body. This phenomenon does not occur.

Furthermore, it goes without saying that the present invention is not limited to the above embodiments, but includes various modifications within the scope of the gist of the present invention. The following is an example of this.

FIG. 6 is a block diagram showing main parts in another embodiment of the present invention. The figure shows the part 1 surrounded by the broken line in Figure 5.
This shows a part corresponding to 2, and the difference from that in FIG. 5 is that a 510 part 14 is incorporated inside it. Therefore, in this case, the detection section 8 in FIG.
The fLfcsTc section 9 inserted between the DSC section 10 and the DSC section 10 can be omitted. In addition, in FIG. 6, blocks having the same functions as those in FIG. 5 are given the same numbers, and a detailed explanation of the functions will be omitted.

In Fig. 6, 1-α to 1-x indicate a plurality of ultrasonic transducers arranged in the transducer 4', which transmit ultrasonic waves to the living body and reflect them at the living body. It works to receive ultrasonic waves. 16-α~16-
The preamplifier is indicated by x, and the ultrasonic transducer 1-α~
The echo signal received at i-x is amplified, and the amplification degree of each amplifier is changed by the correction signal from the src unit 14. The 510 unit 14 generates a correction signal for performing all the sound pressure corrections according to the depth of the living body and the deflection angle of the ultrasound beam based on the rate signal from the transmission/reception controller 2.

This correction signal is input to each of the amplifiers 16-α to 16-x. Reference numeral 15 denotes a delay circuit, which inputs the echo signals sent from the preamplifiers 16-α to 16-x based on the rα1g signal from the transmitting/receiving controller 2, and performs phase control for deflection and focusing. Let's do it. Reference numeral 16 denotes a Calo calculator, which calculates multiple echo signals sent from the delay circuit 15 to calculate
Convert to one echo signal. Further, the output of the adder 16 is sent to the bandpass filter 6. The block configuration after the bandpass filter 6 is the same as that shown in FIG. 5 (however, the 510 section 9 is omitted), so the explanation will be omitted.

Next, the operation of the above configuration will be explained.

In FIG. 6, the pulse signal from the transmission delay section 6 causes
The ultrasonic transducers 1-α to i-x vibrate, and ultrasonic waves are transmitted to the living body. The ultrasonic waves reflected from the living body are received by ultrasonic transducers 1-α to 1-3: and input as echo signals to preamplifiers 13-α to 13-x, respectively. On the other hand, the amplification degree of the preamplifiers 13-α to 13-x is set to 51 based on the rαte signal from the transmitting/receiving controller 2.
The sound pressure of the echo signal is corrected at this stage because it changes depending on the correction signal generated in the 0 section 14. That is, the 510 unit 14 generates a correction signal for sound pressure correction according to the depth of the living body and the deflection angle of the ultrasound beam based on the rate signal from the transmission/reception controller 2, This correction signal controls the amplification degree of each preamplifier 16-α to 13-x. The sound pressure corrected echo signal is then sent to a delay circuit 15 without phase control for deflection and focusing, and further added to a multiplier 16 to be converted into a single signal, and then sent to a bandpass filter. It will be done. The actions after the band pass filter 6 are the same as those shown in FIG. 5, so they will be omitted.
Each preamplifier 13-
Even if the amplification degree of α to 13-x is controlled, it is possible to perform sound pressure correction according to the depth of the living body and also according to the deflection angle of the ultrasonic beam. Similarly, even when the deflection angle of the ultrasonic beam is large, the phenomenon in which the image on the monitor 11 becomes dark in shallow areas of the living body does not occur.

In addition, in the explanation of FIG. 6, the DSC unit 10 in FIG.
510 part 9, which should have been inserted before the sr.
The c section 14 has only a sound pressure correction function according to the deflection angle of the ultrasound beam, and is enlarged before the STC section fDsc section 10, which has only a sound pressure correction function according to the depth of the living body, so that both It is also possible to have a configuration that distributes the information.

〔Effect of the invention〕

As explained above, according to the present invention, even if the ultrasonic frequency in the ultrasonic diagnostic device is increased, a clear monitor image can be obtained because of the ultrasonic waves, and an ultrasonic diagnostic device with excellent distance resolution and azimuth resolution is provided. can do.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the directivity of a rectangular vibrator, Figure 2
The figure shows the directional characteristics when ultrasound is transmitted from a rectangular transducer, Figure 3 shows the center frequency of the filter output spectrum at the distance inside the object, and the M4 diagram was obtained from Figure 6. A diagram showing the relationship between the depth inside the subject and the sound pressure on the central axis at each deflection angle, FIG. 5 is a block diagram showing the first embodiment of the present invention, and FIG. FIG. 2 is a block diagram showing an example. DESCRIPTION OF SYMBOLS 1... Rectangular transducer, 1-α~i-x... Ultrasonic transducer, 2... Transmission/reception controller, 6...
Transmission delay unit, 4.4”...transducer (
array transducer group, ), 5.5'...reception delay unit,
6...ノ(nd pass filter, 7...!0
! 1 amplifier, 8...detection section, 9.14=・5T
Cs, 10=・DSC section, 11...monitor,
16-α ~ 13-T... preamplifier, 15.
...Delay circuit, 16...Adder.

Claims (1)

[Claims] In an ultrasonic diagnostic device that deflects an ultrasonic beam by arranging multiple ultrasonic transducers in a 7-lay pattern and transmitting and receiving a delay time to some or all of the ultrasonic transducers, the received ultrasonic waves are 1. An ultrasonic diagnostic apparatus comprising a sound pressure correction means for correcting sound pressure according to the depth of a subject and a deflection angle of an ultrasonic beam.