JPS636013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus that depicts a tomographic image of a diagnostic region of a living body, for example.

2. Description of the Related Art Ultrasonic diagnostic equipment, unlike radiation and the like, can perform measurements without having any adverse effects on specimens, and has therefore begun to be widely used, particularly in the medical field.

Currently, an important issue for such ultrasonic diagnostic equipment is to obtain clear tomographic images of objects to be measured and specimens.

For example, Japanese Patent Application Laid-Open No. 156292/1983 proposes transmitting and receiving a plurality of ultrasonic beams of different frequencies to obtain images of different image quality and display them in a composite manner.

This method is certainly one of the ways to obtain clear tomographic images.
Although this method is effective, it has the following problems.

(1) Because the ultrasonic beams are transmitted and received at different positions depending on the frequency, it is not possible to display the complete frequency characteristics of the same diagnostic site.

(2) Attenuation occurs when ultrasonic waves pass through a specimen, and this attenuation increases as the frequency increases.When the received wave signals obtained from ultrasound signals of different frequencies are synthesized and displayed, the attenuation is Because they differ, it is not possible to easily compare them.

(3) When ultrasonic signals of different frequencies are synthesized and displayed, it is difficult to determine which frequency of the ultrasonic signal the displayed tomographic image was obtained from.

Therefore, it is an object of the present invention to provide a novel ultrasonic diagnostic apparatus that eliminates the above-mentioned drawbacks.The purpose of the present invention is to emit an ultrasonic signal to a measurement medium, and to detect the reflection or transmission from the measurement medium. In an ultrasonic diagnostic apparatus that obtains an ultrasonic signal obtained as a received wave signal, a broadband ultrasonic signal is emitted to the measurement medium along the same path, and the obtained received wave signal is transmitted through an attenuation correction circuit. This can be achieved by performing attenuation correction using the above method, discriminating the received wave signal through a plurality of filters having a specific center frequency and bandwidth, and displaying the output of each filter in different colors.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the ultrasonic diagnostic apparatus of the present invention.

In the figure, 1 is a specimen, 2 is a probe, 3 is a receiving amplifier, 4 is an amplitude equalization circuit, 5 is a control signal generation source, 6 is a phase control signal generation unit, 7 is a phase equalization circuit, and 8 is a matching circuit. filter, 9 is a band filter,
10 is a display control circuit, 11 is a display, and 2a is a transmission drive unit.

The transmission drive unit 2a supplies a signal of the same amplitude with the signal frequency ranging from ₁ to ₂ , like the signal SP shown in FIG. The ultrasonic signal is transmitted from child 2.

The transmitted ultrasound signals reach the interfaces 11, 12, . . . of two tissues with different acoustic impedances in the specimen.
...Reflected by 1i. reflected ultrasound signal rp ₁ ,
rp ₂ ,..., rpi... are received by the probe after a time determined by the distance from the probe to the interface and the speed of sound. The probe 2 converts this reflected ultrasound signal into an electrical signal.

The received signal thus converted is amplified by a predetermined amount by a receiving amplifier 3. The received signal amplified by the amplifier 3 is input to an amplitude equalization circuit 4 shown in FIG. 3a.

On the other hand, the control signal generation source 5 outputs the signal shown in FIG. 2b, which changes the resistance value of the resistor VCR shown in FIG. Supply to 4. In response to this control signal, the amplitude equalization circuit 4 equalizes the amplitude distortion in accordance with the frequency of the input signal.

Figure 2c shows each transmission signal SP, rp ₁ , rp ₂ , ... rpi
shows the frequency spectrum of

That is, the transmission signal SP has a frequency of ₁ to 1, as described above.
₂ has a constant amplitude. Also, each interface 11, 1
2, ..., 1i (Fig. 1) reflected signal rp ₁ ,
rp ₂ , rp ₃ . . . becomes a spectrum that is attenuated more as the depth increases and as the frequency approaches ₂ . Therefore, the amplitude equalization circuit 4 adjusts the amplitude of these signals by the control signal VC so that the amplitude increases to the shaded portions aeq1, aeq2, and aeqi.

The received signal whose amplitude has been equalized by the amplitude equalization circuit 4 is supplied to a phase equalization circuit 7.

On the other hand, the control signal VC is supplied to the phase control signal generation unit 6.

The phase control signal generation unit 6 includes an analog-to-digital converter 61, a memory 62, and a digital-to-analog converter 63. In the memory 62, the digital value of the phase control signal VC' is stored in advance at the storage address indicated by the digital value of the control signal VC. Further, the memory 62 is accessed by the digital control signal converted into a digital value by the analog-to-digital converter 61, and supplies stored data to the digital-to-analog converter 63.

The digital-to-analog converter 63 converts the supplied digital signal into an analog signal and supplies it to the phase equalization circuit 7 as a phase control signal VC'.

Here, in the amplitude equalization circuit 4, the control voltage
The phase characteristic F(W, VC) with respect to VC is already known, and also in the phase equalization circuit, the control voltage
Assume that the phase characteristic G(W, VC') with respect to VC' is known.

Then, the phase characteristic F( The deviation of W, VC) from the desired characteristic may be corrected using the phase characteristic G(W, VC') of the phase equalization circuit 7. In other words, the deviation of the phase characteristics of F(W, VC) from the desired characteristics can be determined once VC is determined, so VC
Data may be stored in the memory 62 so as to generate an appropriate VC' corresponding to the VC'.

FIG. 2d shows the equalization amount of the phase equalization circuit at each time point. That is, in the band of frequencies ₁ to ₂ , the phase equalization amounts peq1, . . . peqi change sequentially.

The signal thus equalized is supplied to a matching filter 8 for matching with the transmitted waveform.

FIG. 8 shows an embodiment of the amplitude equalization circuit 4 shown in FIG. 1, FIG. 3A shows a specific example of the circuit, and FIG. 3B shows a characteristic diagram. In FIG. 3B, the horizontal axis shows frequency, and the vertical axis shows amplitude A and phase φ. That is, this amplitude equalization circuit includes a voltage control resistor VCR, a capacitor C,
Using a resonant circuit consisting of coil L, variable resistance
By changing the resistance value of the VCR over time and changing the Q constant of the resonant circuit, the degree of signal attenuation in the corresponding frequency region (B) is compensated for using its amplitude characteristics.

Furthermore, regarding the equalization circuit according to the present invention, the patent application No.
Details are given in No. 55-79715.

The signal thus obtained is inputted from a matching filter 8 to a band filter 9 as shown in FIG. 1, and the obtained signal is separated into predetermined bands.

The output of each of these filters 9 is transmitted to a display control circuit 10.
The outputs of each filter 9 are displayed in different colors on the display 11.

Further, as in a color television, if the output of each filter 9 is set to red, blue, or green and brightness modulation is applied to the display 11, the outputs of each filter can be displayed in color.

Figure 4 shows the present invention in a transmission type, for example, in Japanese Patent Application Laid-open No.
This is an embodiment applied to an imaging type ultrasonic diagnostic apparatus disclosed in No. 73474.

In the figure, the same symbols as in FIG. 1 indicate the same things, and in the figure, 12 indicates an acoustic lens, and 13 indicates an ultrasonic emitting device.

Although some of the circuit parts in FIG. 1 are omitted in FIG. 4, the circuit configuration can be considered to be substantially the same.

The ultrasonic diagnostic apparatus shown in FIG. 4 is configured to see the transmission of the specimen 1.

That is, the ultrasonic wave emitting device 13 is driven by the transmission drive unit 2a' to emit ultrasonic waves to the specimen 1. Thereafter, the ultrasonic signal obtained by passing through the specimen 1 is received by the probe 2 through the acoustic lens 12 .
All of these are performed by timing signals from the transmission drive unit 2a.

After the signal obtained in this way is amplitude-equalized by the amplitude equalization circuit 4 as explained in FIG.
The band filter 9 separates the signal into each band, and the display control circuit 10 controls the display 11 for color-coded display.

In this way, it can also be used in a transmission type ultrasound diagnostic device.

As described above, the present invention emits broadband ultrasonic signals along the same path, attenuates the obtained received wave signal using an attenuation correction circuit, and uses a plurality of filters having a specific center frequency and bandwidth. In addition to discriminating the received wave signal through the filter, the output of each filter is displayed in different colors.
This solves the difficulty in tissue discrimination due to differences in attenuation characteristics depending on frequency, and further facilitates tissue discrimination by displaying tissue characteristics for each frequency in different colors.

Note that the attenuation correction circuit of the present invention may be only an amplitude equalization circuit, or may be combined with a phase correction circuit.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the ultrasonic diagnostic device of the present invention, FIG. 3 shows an embodiment of the amplitude equalization circuit of the present invention, and FIG. 4 shows other embodiments of the ultrasonic diagnostic device of the present invention. This is an example. In the figure, 1 is a specimen, 2 is a probe, 3 is a receiving amplifier, 4 is an amplitude equalization circuit, 5 is a control signal generation source, 6 is a phase control signal generation unit, 7 is a phase equalization circuit, and 8 is a matching circuit. filter, 9 is a band filter,
10 is a display control circuit, 11 is a display, 12 is an acoustic lens, and 13 is an ultrasonic emitting device.

Claims (1)

[Claims] 1. In an ultrasonic diagnostic apparatus that emits an ultrasonic signal to a measurement medium and obtains the ultrasonic signal obtained by reflection or transmission from the measurement medium as a received wave signal, a broadband signal is applied to the measurement medium. The ultrasonic signal is emitted along the same path, and the received wave signal is attenuated by an attenuation correction circuit,
An ultrasonic diagnostic apparatus characterized in that a received wave signal is discriminated through a plurality of filters having a specific center frequency and a specific bandwidth, and the output of each filter is displayed in different colors.