JPS6240013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus.

As an ultrasound diagnostic device, a probe emits ultrasound towards a subject, the probe receives the ultrasound signal reflected from the subject, and a display displays an ultrasound tomographic image of the subject. Devices for displaying are known.

In the receiving system of such an ultrasonic diagnostic apparatus, as illustrated in FIG. 1, an ultrasonic signal received by a probe 1 is amplified by a high frequency amplifier 2, and the amplified signal is used to improve amplitude display characteristics. is logarithmically compressed through a logarithmic amplifier 3, then detected by a detection circuit 4, amplified by a video amplifier 5, and applied to a display 6.

However, what is required for diagnosis is to brighten the boundaries of reflective areas that are stronger than a certain level in a tomographic image as necessary to make the outline clear, and in order to meet this requirement, the output of the detection circuit 4 A part with a steep rise (contour signal component) is extracted by a differentiation circuit 7, and this is further mixed with the original video signal and transmitted as a composite signal to a display 6 for display. (Fast Time
Constant (short time constant) processing method is known.

The differentiating circuit 7 in this processing method is composed of a capacitor C _d , a resistor R _d and an amplifier 7 _a as shown in FIG.
When a ₀ ' is passed through the differentiating circuit 7, the amplitude of the rising part of the video signal increases as shown by a ₁ ',
The waveform is attenuated with a time constant R _d ·C _d =τ (approximately 10 μs), and the boundary of the reflective area can be strongly illuminated to make its outline clear.

Another processing method is Delayed Automatic Gain Control, in which a part of the output of the detection circuit 4 is integrated by the integrating circuit 8, and the output is applied as a negative feedback signal to the high frequency amplifier 2.
Processing methods are also known. This integrating circuit 8 is the fourth
As shown in the figure, it is composed of a resistor R _i , a capacitor C _i and a return rate regulator 9 .

The high frequency signal C ₀ has a large amplitude at the rising part due to the negative feedback signal e generated in the integrating circuit 9 _{as shown} in FIG _.
The waveform C ₀ ' attenuates in 5 μs), and the detected output is the waveform shown by f, which is the same as the FTC described above.
Similar to the processing method, it is possible to strongly illuminate the boundaries of the reflective parts to make their outlines sharp, and this processing method is characterized by the ability to adjust the integration time constant and return rate.

However, in these two processing methods,
There is a limit to image processing due to the respective time constants τ and τ _i . That is, in the former case, a negative voltage is generated at the falling edge of the video signal a ₁ ' shown in FIG. 3, and so-called follow-up development occurs, which returns with a time constant τ _d . Therefore, if there is an adjacent small signal as shown by b ₀ ', it will be erased as shown in waveform b ₁ ' due to the negative voltage generated at the falling edge of the video signal a ₀ ', and will not be displayed on the display section 6. There are drawbacks.

In addition, in the latter processing method, since the negative feedback signal e shown in FIG. 5 returns with a time constant τ _i from the falling portion of the high frequency signal C ₀ , the adjacent small signal d ₀ entering this portion is applied with a negative feedback ring, and the small signal d ₀
has the disadvantage that it becomes d ₀ ′ and is almost eliminated. In order to improve this, the time constant and return rate can be adjusted, but there is a limit because even if the time constant is shortened to a certain extent, oscillation still occurs.

An object of the present invention is to provide an ultrasonic diagnostic apparatus equipped with an image processing circuit that eliminates the above-mentioned drawbacks and makes contours clear without eliminating minute signals. The following is a detailed description of the embodiments of the present invention.

As shown in FIG. 6, the ultrasonic signal received by the probe 1 is amplified by a high frequency amplifier 2 and a logarithmic amplifier 3, and a part of the video signal detected by a detection circuit 4 is passed through a high frequency cutoff inverting amplifier 10 to determine the phase. An inverted high-frequency cutoff video signal is generated, the high-frequency cutoff video signal and a part of the video signal are combined, that is, differentially processed, and the processed signal is applied to a video amplifier 5 for amplification and displayed on a display 6. Send.

Figure 7 shows the difference processing circuit 1 surrounded by the dotted line in Figure 6.
In this differential processing circuit 11, IC ₁ is an inverting amplifier, R _f is a negative feedback resistance, and C
_f is a high-pass capacitor, which constitutes a high-frequency cutoff inverting amplifier 10. The high cutoff frequency f _p can be expressed as f _p = 1/2πR _f・C _f , and the resistors R ₁ and R ₂ convert the video signals a ₀ and b ₀ input from terminal A into the inverse ratio of R ₁ and R ₂ . Divided by,
The respective waveforms are waveforms a ₁ , b ₁ or a ₂ , shown in FIG.
b becomes ₂ . The high frequency component of the waveform input to the inverting amplifier IC ₁ , that is, the rising portion, is connected to the bypass capacitor C.
It is cut by _f and further inverted to output waveforms shown by a ₃ and b ₃ . The wave heights of these output waveforms a ₃ and b ₃ are adjusted by a resistor R ₃ and are combined with the video signals a ₁ and b ₁ . In this case, since waveforms a ₃ and b ₃ are inverted from the original video signals shown by waveforms a ₁ and b ₁ , the synthesis of these waveforms is essentially to find the difference between the two waveforms, and the obtained result is The resulting waveform, as shown by a ₄ and b ₄ , emphatically represents the rising portion of the video signal a ₀ , making it possible to strongly illuminate the boundary of the reflection site and clarify the outline of the image.

As described above, according to the present invention, the drawbacks of conventional image processing methods can be overcome, and the outline of the boundary of the reflection site can be made extremely clear without losing ultrasonic signals, including minute signals.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the reception system of a conventional ultrasound diagnostic device, Figure 2 is a detailed diagram showing the main parts of one of the processing methods in Figure 1, and Figure 3 is a video signal waveform diagram of that method. , FIG. 4 is a detailed diagram showing the main parts of another method in FIG. 1, FIG. 5 is a waveform diagram of each part of the method, FIG. 6 is a block diagram showing an example of this invention, and FIG. FIG. 8 is a detailed view of the main parts, and is a waveform diagram of each part of FIG. 7. 1... Probe, 2... High frequency amplifier, 3... Logarithmic amplifier, 4... Detection circuit, 5... Video amplifier, 6... Display, 7... Differentiating circuit, 8... Integrating circuit, 9 ... Return rate adjuster, 10 ... High frequency cutoff inverting amplifier, 11 ... Differential processing circuit.

Claims (1)

[Claims] 1. An amplifier that blocks the high frequency part of a part of the video signal after amplifying and detecting the ultrasonic signal received by the probe and inverts its phase, and the output signal of the amplifier and part of the original video signal. 1. An ultrasonic diagnostic apparatus comprising: a differential processing circuit comprising a circuit for synthesizing the signals and sending the synthesized signals to a display device