JPH04114638A - Doppler ultrasonic diagnosing apparatus - Google Patents

Abstract

PURPOSE:To improve an S/N ratio of a Doppler signal by inputting a clock signal cleared of noise components into a transmitting/receiving means and a detection means for obtaining a Doppler signal to allow the feeding of a base clock signal with noises lowered to an analog processing system. CONSTITUTION:In this apparatus, a clock signal is sent out to transmit an ultrasonic pulse from a digital circuit 6. The clock signal contains noise components owing to other circuits in the digital circuit 6. So. when the clock signal is inputted into a quartz filter 51 a series resonance frequency alone of a quartz resonator X in the clock signal passes selectively. As a result, the clock signal cleared of noises is outputted from the quartz filter 5. The clock signal cleared of the noise components is inputted into a transmitting/ receiving control circuit 4 and a Doppler detection circuit 8. Thus, a Doppler signal with a better S/N ratio is obtained thereby enabling the gaining of a blood flow data with a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a Doppler ultrasonic diagnostic apparatus having a Doppler detection circuit for obtaining blood flow information.

[Conventional technology]

Ultrasonic diagnostic equipment used in the medical field, for example, displays tomographic data of the heart on a monitor in real time, or measures blood flow velocity in a specific region using the pulsed Doppler method, and displays this distribution on a monitor in the same way as above. things are being done.

Ultrasonic diagnostic equipment for obtaining tomographic data and blood flow information as described above generally includes a digital signal processing circuit including a CPU, and analog circuits such as a wave transmitting/receiving circuit, a tomographic detection circuit, or a Doppler detection circuit. It consists of The clock signal and data sent from the digital signal processing circuit are then received by an analog circuit, where various signal processing is performed. On the other hand, in digital signal processing circuits, various lock signals are used, and these clock signals are generated from separate clock generators. Based on these clock signals, signal processing and C
Display on the RT monitor, etc. is performed.

[Problem to be solved by the invention]

In a Doppler ultrasound d#T device, the rate of ultrasound pulses must be stable in order to obtain a Doppler shift signal. Furthermore, the reference signal input to the Doppler detection circuit must be an integral multiple of the pulse period and must be accurately synchronized with the ultrasound pulse.

The periods of these ultrasonic pulses and reference signals are set by a clock signal output from a digital signal processing circuit.

However, the clock signal sent from the digital signal processing circuit is likely to be superimposed with noise components caused by other clock signals, such as clock signals for writing to and reading from memory, clock signals for Fourier calculations, and the like. If such a clock signal with superimposed noise components is used as is, noise will be displayed on the blood flow spectrum, making it impossible to obtain accurate blood flow data.

An object of the present invention is to be able to send a basic clock signal with reduced noise to an analog processing system, and to
An object of the present invention is to provide a Doppler ultrasonic diagnostic apparatus that can improve the N ratio.

[Means to solve the problem]

The Doppler ultrasound diagnostic apparatus according to the present invention includes a wave transmitting/receiving means,
It includes a detection means, a digital signal processing means, and a filter means.

The wave transmitting/receiving means is a means for transmitting an ultrasonic beam into the living body and for receiving reflected ultrasonic echoes. The detection means is means for detecting the echo signal received by the wave transmitting/receiving means to obtain a Doppler signal. The digital signal processing means is a means for transmitting a clock signal used by each transmitting/receiving means and detecting means, transmitting digital data to the transmitting/receiving means, and processing the digital data from the detecting means. The filter means is provided between the digital signal processing amnion, the wave transmitting/receiving means, and the detection means, and is a means for removing noise contained in the clock signal output from the digital signal processing means.

[Effect]

In the present invention, the clock signal sent from the digital signal processing means is input to the filter means before being input to the analog circuit. This filter means is constituted by, for example, a crystal filter with a very narrow pass band, and this crystal filter removes noise components contained in the clock signal. This clock signal from which noise components have been removed is input to a wave transmitting/receiving means or a detection means for obtaining a Doppler signal.

This makes it possible to reduce noise in the transmitted signal emitted from the ultrasound transducer, and the reference signal during Doppler detection is accurately synchronized with the transmitted pulse, improving the S/N ratio of the Doppler signal. .

〔Example〕

FIG. 1 is a schematic block diagram of a Doppler ultrasound diagnostic apparatus according to an embodiment of the present invention.

The ultrasonic diagnostic apparatus includes a main body 1 and a probe 2 connected to the main body 1. probe 2
is composed of a plurality of micro oscillators. Device body 1
has a wave transmitting/receiving circuit 3 for transmitting an ultrasonic beam and receiving reflected echoes. The wave transmitting/receiving circuit 3 includes a high frequency pulse oscillator for transmitting an ultrasonic beam, an amplifier for amplifying reflected echoes, and the like. Transmission/reception wave port l1
A wave transmission/reception control circuit 4 is connected to s3, and this wave transmission/reception control circuit 4 is comprised of a delay circuit, a delay amount control circuit, etc. for performing electronic scanning. Wave transmission/reception control circuit 4
A clock signal is inputted from a digital circuit 6 through a crystal filter 5, and control data is also inputted from the digital circuit 6. The digital circuit 6 is a CP circuit that includes a digital scan converter (DSC) and processes digital data.

Further, the reflected echo signal obtained by the transmission/reception port 83 is input to the tomographic detection circuit 7 and the Doppler detection circuit 8. The tomographic detection circuit 7 includes an A/D conversion circuit and outputs tomographic data. The Doppler detection circuit 8 is composed of a 90° phase shifter, a mixer, etc., and is a circuit for detecting the output of the wave transmitting/receiving circuit 3 to detect the imaginary part (i) and the real part (R). . An A/D conversion circuit 9 is connected to the Doppler detection circuit 8. The A/D conversion circuit 9 is a Doppler detection circuit 8
This is a circuit for converting analog signals output from a digital signal into digital signals. The output of the A/D conversion circuit 9 is FFT
The signal is input to the arithmetic circuit 10. The FFT calculation circuit 10 is a circuit for performing fast Fourier transform calculations to obtain a blood flow spectrum of a certain sample volume. The blood flow data that is the output of the FFT calculation circuit 10 and the tomographic data that is the output of the tomographic detection circuit 7 are input to the digital circuit 6. A display device 11 for displaying tomographic data and blood flow data is connected to the digital circuit 6.

FIG. 2 shows the digital circuit 6 and the wave transmission/reception control circuit 4.
FIG. 2 is a circuit diagram of a crystal filter 5 provided between a Doppler detection circuit 8 and a Doppler detection circuit 8. FIG. A clock signal from the digital circuit 6 is input between terminals 11 and 12. This crystal filter 5 is composed of a parallel connection of a capacitor C1 and a coil L, capacitors C2 and C3, and a crystal resonator X. A clock signal from which noise has been removed is obtained between terminals 01 and 02 between the center tap of the coil L and the crystal oscillator X.

In the apparatus configured as described above, the digital circuit 6 sends and outputs a clock signal for transmitting ultrasonic pulses. This clock signal includes noise components caused by other circuits in the digital circuit 6. This clock signal is input to the crystal filter 5. The crystal filter 5 selectively passes only the series resonance frequency of the crystal resonator X of the clock signal. As a result, the crystal filter 5 outputs a clock signal from which noise has been removed. This clock signal from which noise components have been removed is input to the wave transmission/reception control circuit 4 and the Doppler detection circuit 8. The wave transmitting/receiving control circuit 4 drives the wave transmitting/receiving circuit 3 based on this clock signal, and transmits ultrasonic pulses from the probe 2.

On the other hand, the reflected echo received by the probe 2 is received by the wave transmitting/receiving circuit 3 and input to the tomographic detection circuit 7 and the Doppler detection circuit 8. The Doppler detection circuit 8 performs quadrature detection using the reflected echo signal and the reference wave signal based on the clock signal to obtain a Doppler shift signal. This Doppler shift signal is converted into a digital signal by the A/D conversion circuit 9 and then input to the FFT calculation circuit 1o. This FFT calculation circuit 1o performs fast Fourier transform processing to obtain blood flow spectrum data.

This data is sent to the digital circuit 6, converted into a television signal by the digital circuit 6, and then displayed on the display device 11. Further, the tomographic data obtained by the tomographic detection circuit 7 is converted into a digital signal by the A/D conversion circuit of the tomographic detection circuit 7, and then is sent to the digital circuit 6.
is input. This tomographic data is also converted into a television signal by a digital scan converter or the like of the digital circuit 6 and displayed on the display device 11.

In the above embodiment, a crystal filter 5 as shown in FIG. 2 was used as the filter means, but the filter means
It is not limited to the configuration shown in the figure. If good selectivity is obtained, a filter constructed by combining several crystal oscillators may be used.

〔Effect of the invention〕

As described above, in the present invention, a filter means composed of a crystal filter or the like is provided between the digital signal processing circuit and the analog circuit to remove the noise component contained in the clock signal. A Doppler signal with a good /N ratio can be obtained, and highly accurate blood flow data can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a crystal filter used in the apparatus. 3... Wave transmitting/receiving circuit, 4... Wave transmitting/receiving control circuit, 5...
・Crystal filter, 6...Disicle circuit, 8...Doppler detection circuit.

Claims (1)

[Claims] (1) Transmitting/receiving means for transmitting an ultrasound beam into a living body and receiving reflected ultrasound echoes, and detection for obtaining a Doppler signal by detecting the echo signal received by the transmitting/receiving means. means; digital signal processing means for transmitting a clock signal used by both the means, transmitting digital data to the wave transmitting/receiving means, and processing digital data from the detecting means; and transmitting/receiving with the digital signal processing means. A Doppler ultrasonic diagnostic apparatus, comprising: a filter means provided between a wave means and a detection means, and which removes noise contained in a clock signal output from the digital signal processing means.