JP2874301B2 - Ultrasound Doppler blood flow device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial application field The present invention is used in the field of an ultrasonic diagnostic apparatus.

The present invention relates to ultrasonic Doppler blood flow devices, and more particularly to improved Doppler sound detection.

(B) Prior art Ultrasonic Doppler blood flow devices that observe the blood flow velocity using the Doppler effect are widely known.

The Doppler effect means that when a wave radiated from a wave source is reflected by an object that is moving relative to the wave and returns, the frequency of the reflected wave deviates from the frequency of the original wave source. Refers to the phenomenon observed. A frequency corresponding to this shift is called a Doppler shift (shift) frequency.

If the difference between the frequency of the reflected wave and the frequency of the wave source (beat frequency or Doppler shift frequency) is extracted and analyzed, the velocity distribution of the reflector in the ultrasonic beam direction can be known.

In an ultrasonic Doppler blood flow device, this reflector is used as a blood flow in a living body, and a frequency analysis is performed by separating a Doppler shift frequency from an echo obtained by emitting an ultrasonic wave to the reflector,
The blood flow distribution is observed on the screen.

By the way, regarding Doppler sound, it has been conceived to radiate an ultrasonic wave continuously, extract a beat from an echo, and follow the change with a speaker earlier than image display. At present, abnormalities are determined by listening to the Doppler sound while observing the screen.

However, the problem is that the Doppler shift frequency itself is the pitch of the Doppler sound.

(C) Problems to be Solved by the Invention In the prior art, if the center frequency of the probe, that is, the reference frequency is different, the pitch of the Doppler sound changes in proportion to the center frequency of the probe even for the same blood flow velocity. There is a problem.

Also, the blood flow velocity is underestimated according to the angle θ between the ultrasonic beam and the direction of the blood flow, so that the effect of this parameter remains as it is, and the Doppler sound also has such an angle θ.
The pitch changes according to.

An object of the present invention is to be able to hear a Doppler sound at a pitch proportional to the actual velocity of blood flow without depending on the center frequency of the probe or the angle between the blood flow direction and the ultrasonic beam direction, and to have high objectivity. It is an object of the present invention to provide an ultrasonic Doppler blood flow device that can recognize by Doppler sound.

(D) Means for Solving the Problems The object described above comprises a frequency conversion means of a Dopplerist (shift) frequency separated from an ultrasonic echo and a speaker drive circuit, and this frequency conversion means is a V / F A converter, a V / V converter for converting the voltage between the input and output, an F / V converter, and an amplitude detector, and a control circuit for calculating and setting the V / V conversion coefficient is added. This is achieved by:

(E) Operation With respect to the Doppler shift frequency obtained from the conventional example, while the duration of the Doppler sound is kept almost unchanged, the frequency is converted while maintaining the proportional relationship between the input frequency and the output frequency. Later, it is led to the speaker drive circuit.

In an ultrasonic Doppler blood flow apparatus for observing the blood flow velocity using the Doppler effect, the angle θ between the center frequency (reference frequency) of the probe and / or the beam direction and the blood flow direction is determined by means for converting the Doppler shift frequency. The coefficient of the frequency conversion is changed in accordance with the above, whereby the value of the blood flow velocity and the pitch of the Doppler sound are always constant without depending on the center frequency of the probe or the angle θ between the blood flow direction and the beam direction. I can listen to it.

(F) Embodiment A preferred embodiment of the present invention will be described with reference to the drawings.

Reference numeral 10 denotes an ultrasonic wave transmitting / receiving circuit, 12 denotes a control circuit, 14 denotes an operation panel, and 16 denotes a Doppler shift frequency separation circuit, which separates and outputs a Doppler shift frequency from an ultrasonic echo. 18
Is a frequency converter, and 18a is a frequency / voltage converter (F
/ V), 18b is a voltage converter between input and output (V / V), 18c is a voltage / frequency converter (V / F), and 18d is an amplitude detector. 20 is a speaker drive circuit.

The probe is connected before the ultrasonic wave transmitting / receiving circuit 10, but is not shown.

The control unit 12 detects the type of the probe and its center frequency in order to obtain the Doppler shift frequency, and controls to transmit and receive ultrasonic waves.

The operation unit 14 performs positioning of the sample volume (set site), setting of the blood flow direction, and the like with reference to the B-mode image.

The control unit 12 detects the angle θ between the blood flow direction and the beam direction set by the operation unit and the center frequency fc of the probe,
The proportional coefficient of the V / V converter 18b of the frequency converter 18 is calculated and set.

The Doppler frequency fd is proportional to fc · cos θ · V. Here, fc is the center frequency or reference frequency of the probe, θ is the angle between the ultrasonic beam and the blood flow direction, and V is the blood flow velocity.

Therefore, the conversion coefficient is obtained by 1 / (fc · cos θ), this coefficient is set in the V / V converter 18b, and its output characteristic is determined.

The amplitude of the signal from the Doppler shift frequency is detected by the amplitude detection circuit 18d, and the intensity of the converted frequency (Doppler sound frequency) is controlled.

In the illustrated embodiment, the blood flow velocity V and the Doppler sound do not depend on other conditions but have a proportional relationship. However, as another method for giving the Doppler sound an objectivity, for example, 0.5 m
/ s, the pitch for the blood flow, the center frequency fc of the probe is made to correspond to cos θ with respect to the blood flow direction,
It can also be realized as a device that generates during a time phase in which there is no Doppler sound from the bloodstream.

(G) Effect A Doppler pitch proportional to the blood flow velocity V can be heard.

Also, the pitch of the Doppler sound can be set to a frequency region that is most sensitive to humans.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a main part showing one embodiment of the present invention. 10 is an ultrasonic transmission / reception circuit, 12 is a control circuit, 14 is an operation panel, 16 is a Doppler shift frequency separation circuit, 18 is a frequency converter, 18a is an F / V converter, 18b is a V / V converter, and 18c is A V / F converter, 18d is an amplitude detector, and 20 is a speaker drive circuit.

Claims (1)

(57) [Claims] 1. A frequency converter comprising a frequency converter for a Doppler shift (shift) frequency decomposed from an ultrasonic echo and a speaker drive circuit, wherein the frequency converter comprises an F / V converter;
A V / V converter for converting the voltage between the input and output, a V / F converter, and an amplitude detector, and a control circuit for calculating and setting the V / V conversion coefficient is added. Features,
Ultrasonic Doppler blood flow device.