JPH03254738A - Blood vessel position-measuring device - Google Patents

Abstract

PURPOSE:To measure the position of a blood vessel with high precision by catching the blood vessel within a supersonic beam convergence region in a living body and judging the blood vessel on the basis of the doppler shift frequency obtained from the reflection waves and preventing the erroneous judgement of the echo signal of the blood vessel. CONSTITUTION:A supersonic contactor 8 is constituted by arranging a plurality of vibrators in array form, and a variable delaying circuit 7 is formed form a plurality of variable delaying elements for providing each individual delaying time for the input/output signal of each vibrator element. A supersonic wave receiving/transmission means carries out the receiving/transmission of supersonic waves into a measured living body through the variable delaying circuit 7 and the supersonic contactor 8, and an electronic scan control part 9 controls the delay time for each of a plurality of variable delay time elements, in order to form the convergence region of the supersonic beams in the prescribed direction and distance in the body, and a doppler frequency-detecting circuit 5 detects the doppler shift frequency of the received echo signal supplied from the living body, and a blood vessel judging and position-measuring part 6 judges if the output signal of the doppler frequency-detecting means is the echo signal supplied from the blood vessel, and if the judgement is 'YES', the position is measured. Accordingly, the blood vessel position can correctly be measured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes an electronic scanning ultrasound transmitting/receiving means, a Doppler frequency detection means, and a blood vessel discrimination/position measuring means, and measures the position of blood vessels in a living body to be measured. The present invention relates to a blood vessel position measuring device.

[Prior Art] Conventionally, as a method for measuring the position of a blood vessel in a living body, for example, a reflection method using ultrasonic pulses has been adopted.

FIG. 6 is a schematic block diagram of a conventional ultrasonic measuring device.

In the figure, 30 is an ultrasonic transmitting/receiving device, which includes a transmitting section 31, a receiving section 32, and a propagation time measuring section 33 inside. 34 is an ultrasonic probe, which contains an ultrasonic transducer inside and mutually converts electrical signals and acoustic signals.
Transmits and receives ultrasonic waves. 35 is ultrasound probe 3
4 and the ultrasonic transmitter/receiver 30.

7(a) and 7(b) are diagrams showing the measurement target and measurement waveforms to explain the operation of FIG. 6. FIG. 7(a) shows the measurement target and FIG. Each signal is shown.

The operation of FIG. 6 will be explained with reference to FIGS. 7(a) and 7(b).

For example, several MH from the transmitter 31 in the ultrasonic transmitter/receiver 30
A burst wave having a frequency of approximately z is transmitted at a constant repetition period to drive the ultrasonic probe 34 via the connection cable 35. The ultrasonic probe 34 converts the input electric signal into an acoustic signal, and makes the converted ultrasonic wave enter the living body. Ultrasonic waves incident into a living body are transmitted to interfaces with different acoustic impedances (for example, the interface between fat and muscle,
A portion of the ultrasound waves is reflected from the interface between muscles and blood vessels, etc.), and the ultrasound probe 34 converts the ultrasound waves into electrical signals again.
This converted electrical signal is supplied to the receiving section 32 via the connection cable 35. The receiving section 32 performs amplification, range gate processing, etc. of the human signal, and transmits the output signal to the propagation time measuring section 3.
Supply to 3. The propagation time measurement unit 33 measures the time from the transmission of the burst wave until the received echo is obtained (that is, the ultrasonic propagation time), and calculates the distance to the measurement object from which the echo signal was obtained from the propagation velocity. . Figure 7(a)
The state in which echo signals are obtained as shown in the waveforms shown in FIG. 2B is shown corresponding to the interfaces with different acoustic impedances and the respective positions of the blood vessels shown in FIG.

The vertical axis in Figure 7(b) is the amplitude of the echo signal, which is related to the magnitude of the difference in acoustic impedance, and the horizontal axis is time, which is the distance to the reflective target (i.e., the distance from the biological surface). depth).

Blood vessels in the living body are detected using an ultrasound probe 3 that is brought into contact with the surface of the living body.
By detecting the echo signal obtained by the ultrasound transmitting/receiving device 30 while changing the position of the ultrasound probe 4, the position (i.e., the measured depth position in the living body vertically downward from the living body surface where the ultrasound probe is placed) is detected. Measure.

[Problems to be Solved by the Invention] In the conventional blood vessel position measuring device as described above, the blood vessel position is measured by simply measuring the propagation time of the received echo reflected from the blood vessel. There has been a problem in that when reflected echoes from interfaces with different impedances are mixed, it is difficult to identify received echoes from blood vessels.

Furthermore, since the amplitude of received echoes reflected from blood vessels with small diameters is small, there is also the problem that it is difficult to detect signals effectively.

The present invention was made to solve such problems, and even when detecting received echoes from blood vessels with a small diameter,
Another object of the present invention is to provide a blood vessel position measuring device that can accurately measure the position of a blood vessel even if reflected waves from targets other than blood vessels are present.

[Means for Solving the Problems] A blood vessel position measuring device according to the present invention includes an ultrasonic probe formed by arranging a plurality of transducers in an array, and a human power signal and an output signal of each of the plurality of transducers. , a variable delay circuit including a plurality of variable delay elements each giving an individual delay time; a sound wave transmitting/receiving means; an electronic scanning control means for controlling the delay time of each of the plurality of variable delay elements in order to form a focused region of the ultrasound beam at a predetermined direction and distance within the living body; Doppler frequency detection means for detecting the Doppler shift frequency of the received echo signal obtained from the living body to be measured by the transmitting and receiving means; and determining whether the output signal of the Doppler frequency detection means is an echo signal from a blood vessel; In the case of a blood vessel, the device includes blood vessel discrimination/position measuring means for measuring the position of the blood vessel.

[Operation] In the present invention, an ultrasonic probe is constructed by arranging a plurality of transducers in an array, and individual delay times are set for the human input signal and the output signal of each of the plurality of transducers. A variable delay circuit is formed by the plurality of variable delay elements provided.

The ultrasonic transmitting/receiving means transmits and receives ultrasonic waves into the living body to be measured via the variable delay circuit and the ultrasonic probe, and the electronic scanning control means transmits and receives ultrasonic waves within the living body to be measured in a predetermined direction and distance. In order to form a focused region of the ultrasound beam, the delay time of each of the plurality of variable delay elements is controlled, and the Doppler frequency detection means detects the Doppler shift frequency of the received echo signal obtained from the living body to be measured by the ultrasound transmission/reception means. The blood vessel discriminating/positioning means determines whether the output signal of the Doppler frequency detecting means is an echo signal from a blood vessel, and if the determination result indicates that it is a blood vessel, the position of the blood vessel is measured.

[Embodiment] FIG. 1 is a schematic block diagram of a blood vessel position measuring device showing an embodiment of the present invention. In the figure, 1 is a transmission wave generation circuit, which has a constant frequency f. A transmission wave (for example, about 10 to 20 MHz) is generated and supplied to the Doppler frequency detection circuit 5, and a part of the generated transmission wave is supplied to the transmitter 2 as a burst wave with a constant repetition period. A transmitter 2 amplifies and outputs the human power signal from the transmit wave generating circuit 1, drives the ultrasound probe 8 via the variable delay circuit 7, and transmits an ultrasound beam. 3 is a receiving section, which amplifies and outputs a received signal inputted manually via the ultrasonic probe 8 and the variable delay circuit 7. 4 is a range gate circuit, which operates based on a range setting signal manually inputted from the electronic scanning control section 9.
A gating operation is performed to extract only signals near the focal region of the ultrasound beam. Reference numeral 5 denotes a Doppler frequency detection circuit, which detects the Doppler shift frequency since the reception frequency of the ultrasonic wave shifts from the transmission frequency (this is called a Doppler shift) when the target object from which a reflected signal can be obtained moves. The purpose of this embodiment is to detect the blood flow velocity in a blood vessel as a Doppler shift frequency. Reference numeral 6 denotes a blood vessel discrimination/position measurement unit, which discriminates whether the output signal of the Doppler frequency detection circuit 5 is an echo signal from a blood vessel and not a reflected signal from a heart or the like, and if the discrimination result is a blood vessel, The azimuth signal of the focused ultrasound beam obtained from the electronic scanning control unit 9, the ultrasound propagation time from the transmission of the ultrasound until the Doppler detection signal is obtained (this time is proportional to the distance from the biological surface to the blood vessel), The position of the blood vessel is measured from the position of the blood vessel, and the measurement result is output to a display, printer, etc. (not shown).

7 is a variable delay circuit, which has N variable delay elements 7 inside.
-1 to 7-N. In addition, each variable delay element 7-1 to 7-
The delay time of N (the delay time from when a signal is supplied to the input end until the signal is output to the output side) is controlled by the electronic scanning control section 9. Reference numeral 8 denotes an ultrasonic probe, which includes N ultrasonic transducers 8-1 to BN arranged in an array inside. Reference numeral 9 denotes an electronic scanning control section, which variably sets the delay time of each of the variable delay elements 7-1 to 7-N based on, for example, manual operation by an operator. As a result, the position of the ultrasound beam focus zone is controlled, and the operator can manipulate the blood vessel so that it falls within this focus zone. In this way, the electronic scanning control section 9 controls each of the variable delay elements 7-1 to 7-N.
In addition to supplying a delay time setting signal for each time, a range setting signal corresponding to the distance to the ultrasound beam focusing area is supplied to the range gate circuit 4, and a scanning direction signal of the ultrasound beam is also supplied to the blood vessel discrimination/position measurement unit 6. supply.

FIG. 2 is a diagram illustrating the Doppler effect of reflected waves obtained from blood flow according to the present invention. In the figure, a transmission frequency f is applied to scattered particles such as red blood cells contained in blood flowing at a blood flow velocity V in a blood vessel. When an ultrasonic wave is incident, the frequency of the reflected wave becomes f due to the Doppler effect of blood flow. +f. In the figure, an ultrasonic wave is incident on a blood vessel at an incident angle θ, and the Doppler frequency f is proportional to the velocity component v ” cos θ in the incident direction.
An example in which d is obtained is shown.

FIG. 3 is a block diagram of a Doppler frequency detection circuit according to the present invention, in which the Doppler frequency detection circuit 5 includes a frequency mixer 51.
and a low-pass filter (hereinafter referred to as LPF) 52. In the figure, a transmitted wave with a frequency f and a received wave 0 with a frequency f + fd are mixed by a frequency mixer 51, and a sum frequency and a difference frequency of the two frequencies are output, but only this difference frequency is output. , and is output as a Doppler frequency fd.

4(a) to 4(e) are diagrams showing the measurement target and measurement waveforms to explain the operation of FIG. 1, and FIG. 4(a) shows the measurement target, and FIG. The detection signal is shown in the same figure (C).
indicate range gate signals, respectively. In the figure, since the boundary surface with different acoustic impedances shown in FIG. 3(a) is stationary and has no velocity component, no Doppler detection signal can be obtained from the reflected wave at this boundary surface. A Doppler detection signal corresponding to the blood flow velocity is obtained from the reflected wave from the blood vessel. This state is shown in the same figure (b).

Furthermore, the gate position and gate width of the range gate signal are set so that the range gate signal includes the blood vessel shown in FIG. The state in which the Doppler frequency signal is detected from the echo signal contained in the range gate signal and the propagation time from the transmission of the ultrasonic wave to the detection of the Doppler frequency signal is measured is shown in the same figure (C).

FIG. 5 is a diagram illustrating the focused state of the ultrasonic beam according to the present invention. The figure shows the timing of driving the ultrasonic transducers 7-1 to 7-N arranged in an array to transmit ultrasonic waves, and the signals received and output to each of the ultrasonic transducers 7-1 to 7-N. The timing of synthesizing the beams is controlled by controlling the delay time of each variable delay element connected to each vibrator, and a beam focusing area is obtained at a desired position (azimuth and distance).

In this embodiment, an operator manually controls the electronic scanning control section 9 shown in FIG. 1 to set the ultrasound beam focusing area at a position where a blood vessel exists in the living body.
Effective reflected signals can be obtained even from small diameter blood vessels. However, the present invention is not limited to the above-mentioned embodiments, and a program that prescribes the blood vessel detection control operation of the electronic scanning control unit 9 is built into the device, and the beam focusing area is automatically adjusted based on the program. change the position,
It may also be possible to detect whether a blood vessel has entered the inside.

The operation in FIG. 1 will be explained with reference to FIGS. 2 to 5. The burst wave of frequency fo outputted from the transmission wave generation circuit 1 is signal-amplified by the transmission section 2, and then sent to the ultrasonic probe via each of the variable delay elements 7-1 to 7-N in the variable delay circuit 7. It is supplied to each of the ultrasonic transducers 8-1 to 8-N in the child 8. Since the signal delay time of each variable delay element 7-1 to 7-111 is controlled by the electronic scanning control section 9, the ultrasound probe 8 focuses the ultrasound beam as explained in FIG. to form a focused area at a predetermined location within the body. The operator of this apparatus operates the electronic scanning control section 9 to perform control so that a desired blood vessel to be measured in the living body falls within this focusing area, as explained in FIG. When a blood vessel enters this focusing area, as a result of beam focusing, a sufficient reflected signal can be obtained even when the diameter of the blood vessel is small.

Here, when the target object from which the reflected signal is obtained in the living body is stationary, the reception frequency is f, which is the same as the transmission frequency. However, as explained in FIG. 2, the Doppler effect occurs from the blood vessel due to the moving speed of particles such as red blood cells within the blood vessel, and the reception frequency is f. +f.

Changes to In this way, the ultrasound reflected waves reflected from the stationary target or the moving target in the living body are received again by each of the ultrasound transducers 8-1 to 8-N in the ultrasound probe 8, and Each output of each variable delay element 7 in the variable delay circuit 7
-1 to 7-N and then supplied to the receiving section 3. From the received wave whose signal has been amplified by the receiving section 3, only the signal within the gate width generated by the range gate circuit 4 is extracted and supplied to the Doppler frequency detection circuit 5, as shown in FIG. 4(C). be done.

As explained in FIG. 3, the Doppler frequency detection circuit 5
The Doppler shift frequency of the received wave is detected by comparing the transmitted wave of frequency fo that is manually inputted from the transmitted wave generation circuit 1 with the received wave within the range gate that is manually inputted from the range gate circuit 4. For example, if the reception frequency in the previous example is f 2 +fd, the Doppler shift frequency fd is detected and this frequency data is supplied to the blood vessel discrimination/position measurement section 6. The blood vessel determination/position measurement unit 6 calculates the blood flow velocity from this Doppler frequency data, and uses this calculated value to determine whether the received signal is a reflected wave from the blood vessel. In other words, in living organisms there are objects that move, such as the heart and diaphragm, but the position, size, and form of movement of these objects (for example, the heart makes reciprocating motion, but blood flow always flows in one direction). As the current flows, the Doppler frequency periodically becomes f + f or f o
It does not become f d or Od. There is always only one. ), movement speed (for example, the blood flow speed in the human body is within a substantially constant range, and its value is known), etc., to determine whether this Doppler frequency detection data is a reflected wave from a blood vessel. I can do it. If the discrimination result is a blood vessel, the blood vessel discrimination/position measurement unit 6 detects its position as follows. The direction of the blood vessel is read by the scanning direction signal of the ultrasound beam supplied from the electronic scanning control unit 9, and the distance to the blood vessel is determined by the Doppler detection signal obtained from the ultrasound transmission, as shown in FIG. 4(e). It can be calculated from the propagation time of the ultrasonic wave. In this way, the direction and distance of the blood vessel to be measured are measured. The measurement results are outputted to the operator via a display or printer (not shown).

[Effects of the Invention] As described above, according to the present invention, the apparatus is equipped with an electronic scanning ultrasound transmitting/receiving means, a Doppler frequency detection means, and a blood vessel discrimination/positioning means, and is capable of capturing blood vessels within an ultrasound beam focusing area within a living body. Since it is determined whether a blood vessel is a blood vessel or not based on the Doppler shift frequency obtained from the reflected wave, there is no need to erroneously measure echo signals other than blood vessels, and it is also possible to detect blood vessels with small diameters. Since a sufficient reflected signal can be obtained, blood vessels are not overlooked and the blood vessel position can be accurately measured.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a blood vessel position measuring device showing an embodiment of the present invention, FIG. 2 is a diagram illustrating the Doppler effect of reflected waves obtained from a blood vessel according to the present invention, and FIG. Block diagram of such Doppler frequency detection circuit, FIG. 4(a)-
(c) is a diagram showing the measurement target and measurement waveform to explain the operation of Figure 1, Figure 5 is a diagram to explain the focused state of the ultrasound beam according to the present invention, and Figure 6 is a diagram showing the conventional ultrasound beam. A schematic block diagram of the measuring device, FIGS. 7(a) and 7(b), is a diagram showing a measurement target and a measurement waveform for explaining the operation of FIG. 6. In the figure, 1 is a transmission wave generation circuit, 2.31 is a transmitter,
3.32 is a receiving section, 4 is a range gate circuit, 5 is a Doppler frequency detection circuit, 6 is a blood vessel discrimination/position measuring section, 7 is a variable delay circuit, 7-1 to 7-N are variable delay elements, 8.34 is an ultrasonic probe, 8-1 to gN are ultrasonic transducers, 9 is an electronic scanning control section, 30 is an ultrasonic transmitter/receiver, 33 is a propagation time measuring section, and 35 is a connection cable. fo° transmission frequency ■, blood flow velocity

Claims (1)

[Claims] An ultrasonic probe including a plurality of transducers arranged in an array, and an input signal and an output signal of each of the plurality of transducers,
a variable delay circuit comprising a plurality of variable delay elements each giving an individual delay time; and an ultrasonic transmitting/receiving means for transmitting and receiving ultrasonic waves into a living body to be measured via the variable delay circuit and an ultrasonic probe. , electronic scanning control means for controlling the delay time of each of the plurality of variable delay elements in order to form a focused region of the ultrasound beam in a predetermined direction and distance within the living body; Doppler frequency detection means for detecting a Doppler shift frequency of a received echo signal obtained from a living body to be measured; 1. A blood vessel position measuring device comprising: blood vessel discrimination/position measuring means for measuring the position of the blood vessel.