JPH04250149A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To solve the dynamic range deficiency in an A/D converter caused by a stroke generated at the time of continuous wave Doppler mode. CONSTITUTION:When an ultrasonic beam is transmitted to a subject by an ultrasonic probe 1, the reflected wave is received from the subject, the receipt signal is detected in quadrature by multipliers 4A, 4B, and the detection signal is processed by A/D converters 8A, 8B, a phasing adder 9, and an image reconstituting arithmetic part 10 to obtain an ultrasonic image, high-pass filters 5A, 5B for passing the high frequency component of the detection signal and a means for operating the high-pass filters 5A, 5B at the time of continuous wave Doppler mode to pass the high frequency component of the detection signal, and non-operating the high-pass filters at the time of pulse Doppler B-mode to pass the whole area of the converted signal are provided.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an ultrasonic diagnostic device that detects the speed of a moving reflector such as blood flow in the heart or blood vessels, and in particular, the present invention relates to an ultrasonic diagnostic device that detects the velocity of a moving reflector such as blood flow in the heart or blood vessels, and in particular, The present invention relates to an ultrasonic diagnostic device that solves the problem of insufficient dynamic range of a converter.

0002

2. Description of the Related Art A conventional ultrasonic diagnostic apparatus has a configuration as shown in FIG. 5, for example. In the ultrasonic diagnostic apparatus shown in FIG. 5, an ultrasonic probe 1 equipped with a plurality of ultrasonic transducers 1-1 to 1-N is driven by a transmission circuit (not shown) to generate an ultrasonic beam. The ultrasonic beam is transmitted from the ultrasonic probe 1 to a subject (not shown). The ultrasonic waves reflected from the subject are then taken into the same ultrasonic transducers 1-1 to 1-N as respective received signals, and each received signal is amplified to a predetermined level by preamplifiers 3-1 to 3-N. .

[0003] Furthermore, each received signal is detected by a quadrature detector 4, frequency-converted, and a Doppler signal due to blood flow is obtained. This Doppler signal is converted into a digital signal by A/D (analog/digital converters) 8-1 to 8-N. and A/D8-1~8-
Each digital signal from N is given appropriate time compensation by a phasing adder 9, added together, and taken into an image reconstruction calculation section 10 as a phasing addition signal. Based on this phasing and addition signal, the image reconstruction calculation unit 10 performs FFT.
Arithmetic processing is performed to obtain an image, a color flow mapping image (hereinafter referred to as a CFM image), and a B-mode image.
The obtained ultrasound image is displayed on the TV monitor 12.

0004

However, in the continuous wave (CW) Doppler mode, the signal detected by the quadrature detector 4 has a low frequency component due to clutter that is approximately 40 dB larger than the Doppler signal component. Therefore, the output signals of the A/D 8 and the phasing adder 9 were saturated due to this clutter, and as a result, a good ultrasound image could not be obtained. Further, there is a problem in that crosstalk occurs between each vibrator and between each channel during transmission and reception, and the dynamic range in the A/D 8 and the phasing adder 9 is insufficient due to this crosstalk.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that can eliminate the lack of A/D dynamic range and obtain good ultrasonic images even in continuous wave Doppler mode. be.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the objects, the present invention takes the following measures. The present invention scans a subject with an ultrasound beam using an ultrasound probe equipped with a plurality of ultrasound transducers, converts the frequency of the received signal obtained by this using a conversion means, and converts the converted signal into a signal. In an ultrasonic diagnostic apparatus that obtains an ultrasound image by processing with a processing means, a high-pass filter means for passing a high frequency component of the converted signal, and the high-pass filter means is operated in continuous wave Doppler mode. , a control means for inactivating the high-pass filter means in pulsed Doppler mode and B mode.

[0007]

[Effects] By taking such measures, the following effects are achieved. In the continuous wave Doppler mode, the high-pass filter means operates and removes the low frequency components of the converted signal, reducing crosstalk (including low frequency components such as clutter and DC components), thereby improving signal processing. For example, the lack of dynamic range of A/D can be solved. In addition, in the pulsed Doppler mode and B mode, the high-pass filter means is inactive and the entire band of the converted signal passes through, so it is possible to reduce the trailing phenomenon of the signal waveform, etc. You can get the image.

[0008]

[Examples] Specific examples of the present invention will be described below. FIG. 1 is a schematic block diagram showing a first embodiment of an ultrasonic diagnostic apparatus according to the present invention. As shown in FIG. 1, an ultrasonic diagnostic apparatus includes an ultrasonic probe 1 that is equipped with a plurality of ultrasonic transducers, transmits an ultrasonic beam to a subject, and captures reflected ultrasound from the subject as a received signal. , a transmitting circuit 2 for driving each ultrasonic transducer with a continuous wave or a pulse wave for each ultrasonic transducer, and a preamplifier 3 for amplifying the received signal input from the ultrasonic probe 1 to a predetermined level.

The device also receives a reference signal S1 consisting of a sine wave.
A reference signal generator 11 generates a reference signal S2 consisting of a cosine wave and a cosine wave, and the received signal is frequency-converted and detected by multiplying the received signal from the preamplifier 3 and the reference signal S1 from the reference signal generator 11. It is composed of a multiplier 4A that obtains a signal, and a multiplier 4B that converts the frequency of the received signal by multiplying the received signal from the preamplifier 3 and the reference signal S2 from the reference signal generator 11 to obtain a detected signal. It has a Cladracha detector.

Furthermore, the device operates high-pass filters 5A, 5B that pass high-frequency components of the signal frequency-converted by the multipliers 4A, 4B, and operates the high-pass filters 5A, 5B in the continuous wave Doppler mode to generate pulse waves. Doppler mode, B
Switch S that deactivates the high-pass filters 5A and 5B in mode and passes the entire frequency-converted signal band.
W1, SW2, and a mode switching control unit 6 that provides a control signal to SW1, SW2 for inactivating both switches SW1 and SW2 in continuous wave Doppler mode and operating both switches SW1 and SW2 in pulsed wave Doppler mode and B mode. and has.

[0011] The high-pass filter 5A includes multipliers 4A and L
A capacitor C1 is provided between the PF7A and a resistor R whose one end is connected to the capacitor C1 and the other end is grounded.
1, the high-pass filter 5B is composed of a multiplier 4B
and a capacitor C2 provided between the LPF7B and the LPF7B,
It consists of a resistor R2, one end of which is connected to the capacitor C2, and the other end of which is grounded. Switch SW1 is connected in parallel to capacitor C1, and switch SW2 is connected in parallel to capacitor C2.

The device further includes low-pass filters 7A, 7B for removing high frequency components, and removing unnecessary band signals of the Doppler signals taken in from the high-pass filters 5A, 5B or the switches SW1, SW2; A/Ds 8A and 8B that convert the outputs from the low-pass filters 7A and 7B into digital signals, and a phasing circuit that adds these signals together to obtain a phased sum signal after giving appropriate time compensation to the digital signals. Phase adder 9 and mode switching control section 6
An image reconstruction calculation unit 10 performs calculations to reconstruct FFT images, CFM images, and B-mode images showing temporal changes in blood flow velocity according to control signals from the It has a TV monitor 12 for displaying images.

Next, the operation of the first embodiment configured as described above will be explained. An ultrasound probe 1 equipped with a plurality of ultrasound transducers is driven to transmit by a transmission circuit 2, and transmits an ultrasound beam to a subject (not shown). Ultrasonic waves reflected from the subject are received by each ultrasonic transducer of the ultrasound probe 1, and each received signal is amplified by a preamplifier 3 provided for each ultrasonic transducer.

Each received signal amplified by the preamplifier 3 is taken into multipliers 4A and 4B, and the multipliers 4A and 4B receive a reference signal S1 consisting of a sine wave and a cosine wave from the reference signal generator 11. The reference signal S2 is taken in with a phase difference of 90° from each other. The multiplier 4A multiplies each received signal by the reference signal S1, and the multiplier 4B multiplies each received signal by the reference signal S2. Therefore, the multipliers 4A, 4B perform frequency conversion by quadrature detection, and the detected signal due to the blood flow is separated into a real component and an imaginary component, which are taken into the high-pass filters 5A, 5B or SW1, SW2.

Here, a continuous wave is transmitted from the ultrasound probe 1, and when the ultrasound reception mode is the continuous wave Doppler mode (FFT
(only), the switches SW1 and SW2 are inactivated (turned off) and the high-pass filters 5A and 5B are activated (turned on) by a control signal from the mode switching control section 6. Then, low frequency components of the detected signal are removed by capacitor C1 and resistor R1, capacitor C2 and resistor R2. That is, crosstalk components (including low frequency components such as clutter and DC components) contained in the detected signal are sufficiently removed. Therefore, the lack of dynamic range of the A/Ds 8A, 8B and the phasing adder 9 after the low-pass filters 7A, 7B, for example, can be solved, and a good ultrasound image can therefore be obtained. In addition, since the lack of dynamic range of A/Ds 8A and 8B can be resolved, the number of data and bit length after A/Ds 8A and 8B can be reduced.

Next, a pulse wave is transmitted from the ultrasound probe 1, and the ultrasound reception mode is set to pulse wave Doppler mode (FFT,
CFM) or B mode, the mode switching control section 6
The switches SW1 and SW2 are operated (turned on) by control signals from the switch SW1 and SW2. At this time, the detection signal is
It passes through W1 and SW2 and is output as is from LPF7A and 7B.

Therefore, the loss of phase information due to the trailing phenomenon of the signal waveform caused by the detection signal passing through the high-pass filters 5A and 5B can be reduced by simply increasing the circuit configuration.

Furthermore, since quadrature detection is performed on the received signal before the A/Ds 8A and 8B, the frequency of the converted signal becomes lower than the received signal, and the A/Ds 8A and 8B
The conversion period of B can be slowed down.

Next, a second embodiment of the present invention will be explained with reference to FIG. The second embodiment processes only analog signals, and in contrast to the first embodiment described above, the A/Ds 8A and 8B are removed and a phasing adder 9a having analog delay means is added. It is characterized by having been provided.

The second embodiment configured as described above also provides the same effects as the first embodiment. Further, after the received signal is subjected to quadrature phase detection by multipliers 4A, 4B to lower the frequency, high-pass filters 5A, 5B, LP
Since the signals are added by the phasing adder 9a via F7A and 7B, the frequency of the signal in the phasing adder 9a is low, so the influence of stray capacitance in the analog delay means can be reduced. Frequency characteristics can be improved.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment has the following points in contrast to the first embodiment:
A phasing adder 9 is provided between the preamplifier 3 and multipliers 4A, 4B, and a B mode processing section 15 and a DSC (digital scan converter) 17 are provided between the phasing adder 9 and the TV monitor 12. It is characterized by having been provided.

That is, each received signal is added by the phasing adder 9 to obtain a phasing sum signal, and the envelope of this signal is detected by the B mode processing section 15 to obtain a B mode image. The image is sent to the TV monitor 1 via the DSC 17.
Display on 2.

On the other hand, the signal from the phasing adder 9 is transmitted to the multiplier 4
The Doppler signals obtained by quadrature phase detection by A and 4B are passed through high-pass filters 5A and 5B and low-pass filters 7A and 7.
B, A/D 8A, and 8B perform signal processing to reconstruct an FFT image or a CFM image in an image reconstruction calculation unit 10, and display the ultrasound image on a TV monitor 12. Even in such a third embodiment, the same effects as in the first embodiment can be obtained.

Next, a fourth embodiment of the present invention will be explained with reference to FIG. The fourth embodiment is a modification of the second and third embodiments, and has a configuration in which analog signals are processed and a B-mode processing system is provided separately. Even in such a fourth embodiment, the same effects as in the second embodiment described above can be obtained.

Note that the present invention is not limited to the embodiments described above. In the first and third embodiments described above, L
Although the A/Ds 8A and 8B are provided after the PFs 7A and 7B, for example, the LPFs 7A and 7B may be provided after the A/Ds 8A and 8B. Further, in this embodiment, the high-pass filter is constructed of a resistor R and a capacitor C, but it may be a higher-order filter, and any filter having the function of a high-pass filter may be used. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

[0026]

According to the present invention, the high-pass filter operates during continuous wave Doppler mode, and low frequency components of the converted signal are removed, thereby reducing crosstalk (low frequency components such as clutter and direct current). (including components) can be reduced, it is possible to solve the problem of a lack of dynamic range in the signal processing means, such as an A/D. Furthermore, in the pulse Doppler and B modes, the high-pass filter is inactive and the entire band of the converted signal passes through, so it is possible to reduce the trailing phenomenon of the signal waveform. Therefore, it is possible to provide an ultrasonic diagnostic apparatus that can obtain good ultrasonic images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the ultrasonic diagnostic apparatus according to the present invention.

FIG. 3 is a block diagram showing a third embodiment of the ultrasonic diagnostic apparatus according to the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the ultrasonic diagnostic apparatus according to the present invention.

FIG. 5 is a block diagram showing an example of a conventional ultrasound diagnostic apparatus.

[Explanation of symbols]

1...Ultrasonic probe, 2...Transmission circuit, 3...Preamplifier, 4
A, 4B...multiplier, 5A, 5B...HPF, 6A, 6B...
Mode switching control section, 7A, 7B...LPF, 8A, 8B...
A/D, 9... phasing adder, 10... image reconstruction calculation unit, 1
2...TV monitor.

Claims (1)

[Claims] Claim 1: An ultrasonic probe equipped with a plurality of ultrasonic transducers scans an ultrasonic beam onto a subject, and a received signal obtained thereby is frequency-converted by a converting means to convert the converted signal. An ultrasonic diagnostic apparatus that obtains an ultrasound image by processing with a signal processing means, comprising: a high-pass filter means for passing a high-frequency component of the converted signal; and the high-pass filter means is operated in a continuous wave Doppler mode. and control means for inactivating the high-pass filter means in pulsed Doppler mode and B mode.