JPS6234543A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an apparatus for diagnosing tissues within a subject using ultrasound, and in particular to an apparatus for diagnosing tissues within a subject by measuring the ultrasonic propagation velocity (hereinafter referred to as sound velocity) of tissue III. The present invention relates to an ultrasonic diagnostic device for diagnosis.

[Technical Background of the Invention] As a device for diagnosing living tissue, there is an ultrasonic diagnostic device that diagnoses living tissue by measuring the sound velocity of the living tissue. The basic principle of the ultrasonic diagnostic apparatus will be explained below with reference to FIG.

That is, using the linear electronic scanning probe 1, 7
One end A of the ultrasound transmitting/receiving surface 2 in contact with a body surface (not shown)
It emits ultrasonic pulses in the θ direction into the body. Then, the ultrasonic pulse travels straight along the transmission path 4 in the liver tissue, for example, and reaches the point P.
The offending ultrasonic wave passes through reception path 5 and is received by the transducer on the right end B. Since the distance y between uA and 8 is known, path 4
, 5, the sound velocity C in the liver tissue is C=y/ (t - sin θ) ・(1
It is found as 1.

In addition, the sound speed of the standard normal tissue is Go = 1530 m/S
In this case, in order to radiate the ultrasonic beam in the θ0 direction, the delay time τ0 between each adjacent (radiator) of the probe 1 is expressed as ``l:a = (d/Co > ・sinθ −(
2).

If the sound speed of the living tissue is Go, the ultrasound beam is θ0
However, in general, the value C is not limited to Go but is different from Co. At this time, the propagation direction θ of the ultrasonic wave is sin θ/C=siro from Snell's law Go / Co
= the value shown in (3).

However, in conventional ultrasonic diagnostic devices that measure the sound speed of living tissue based on the above principle, the measurement accuracy of the propagation time t used for sound speed calculation is not sufficient, and as a result,
This causes the inconvenience that the speed of sound in living tissue cannot be determined accurately.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to improve the reliability of sound velocity data by improving the measurement accuracy of ultrasound propagation time in an ultrasound diagnostic device. The aim is to improve sexual performance.

[Summary of the Invention] The outline of the present invention for achieving the above object is to have a first and a second transducer group each having a plurality of ultrasonic transducers arranged; In an ultrasonic diagnostic apparatus that calculates the ultrasonic propagation velocity of an internal tissue of a subject from received echoes of ultrasonic waves transmitted toward the subject and received by the second transducer group for diagnosis, An ultrasonic beam is applied to each of the excitation pulses used to excite each ultrasonic transducer constituting the first transducer group and the ultrasonic waves (received echoes from the transducers) constituting the second transducer group. By giving a delay time that takes into account the focal length, an ultrasonic beam is generated at the intersection of the directivity of ultrasonic waves transmitted by the first transducer group and the directivity of ultrasonic waves received by the second transducer group. The present invention is characterized by comprising a transmission delay circuit and a reception delay circuit for matching the focal points of the signals.

[Embodiments of the invention] Hereinafter, the present invention will be specifically explained with reference to Examples.

The basic principle for measuring the speed of sound in an ultrasonic diagnostic apparatus according to an embodiment of the present invention is the same as that for measuring the speed of sound explained in accordance with FIG. 9, so it will not be explained again.

FIG. 1 is a block diagram showing the configuration of the apparatus of this embodiment.

The transducer array 11 is arranged on the ultrasonic wave transmitting/receiving surface 2 of the probe shown in FIG. To detect.

The transducer array 11 (T1~'128) has a transducer width a of 0.67, and a willow one with an element center spacing d=0.72M and a transducer width a of 0.67.
Eight elements are arranged in a straight line. Electric signals are sent and received to and from each of these vibrators through lead wires 12 within the cable 3.

The clock oscillator 21 drives the 32 pulsers 14 by outputting a rate pulse of, for example, 10 Ml-1z. The output end of the pulser 14 is connected to T1 to T32 at the A end of the sensor array 11 via the multiplexer 13.
(first vibrator group).

Reference numeral 15 denotes a transmission delay circuit that provides a delay time to the excitation pulse that excites the first transducer group T1 to T32. In this embodiment, the delay time τ(X) given to the excitation pulse by the transmission delay circuit 15 is expressed by the following equation, taking into account the focal length F.

r(X)=(F/Co H+ +2 x F s
in -1)...(4) Here, X is the position of each transducer in the first transducer group T1 to T32 in the arrangement direction (
coordinates). When such a delay time is given, the relationship between each transducer position and the transmission delay time is a characteristic diagram as shown in FIG.

Reference numeral 16 denotes a receiving delay circuit which gives a delay time to the ultrasonic reception echoes taken in through the second transducer group lower 9□ to T1°8, and synthesizes and outputs them. The delay time in this reception delay circuit 16 is set based on the delay time expressed by the previous equation (3), and is determined based on the arrangement direction of each transducer in the second transducer group T9□ to T128. When the position of is set as X, the relationship between each transducer position and the reception delay time becomes a characteristic diagram as shown in FIG. 3, which is symmetrical to the characteristic curve of FIG. 2.

19 is a receiving circuit that amplifies and detects the output of the receiving delay circuit 16; 22 is a memory that stores output data of one of the receiving circuits; This is a processing circuit that performs averaging processing in relation to newly captured data. 24 is a waveform analysis circuit that analyzes the waveform of the result of the averaging process;
25 calculates the time (address) of the peak value of the waveform from the output of the waveform analysis circuit 24 to obtain the propagation time t of the ultrasonic wave. ) and the average value Vi of the sound speed values up to the i-th
It is a calculation circuit that calculates the

The sound velocity value V1 is a value that is excluded by executing the calculation of the previous equation (1), and the average value V up to the i-th is excluded by executing the calculation of the following equation.

■・=(1/i) Heaven, Vj...(5)27
is a system control means, which is mainly composed of, for example, a CPtJ (central processing unit). This system control means 27 controls the operation of the multiplexer 13, the setting of delay times of the transmission delay circuit 15 and the reception delay circuit 16, the write control of the memory 22, and the operation control of the bar calculation circuit 25. It is something. 29 is a freeze switch (input means), and by turning on and off this freeze switch 29, the system controls whether or not to repeat the series of operations of ultrasonic wave transmission and reception, propagation time measurement, sound speed value calculation, and display display. The means 27 can be commanded.

In the embodiment apparatus having the above configuration, first, the delay times of the transmission delay circuit 15 and the reception delay circuit 16 are set under the control of the system control means 27. Then, the multiplexer 13 connects the output terminal of the pulser 14 to each of the first transducer groups T1 to T32 arranged at the A end of the transducer array 11, and the output terminal of the pulser 14 is connected to the delay set in the transmission delay circuit 15. Each ultrasonic transducer is excited according to time.

After emitting the ultrasonic pulse, the multiplexer 13 transmits the second transducer M arranged at the B end, T9□ to T128.
and a reception delay circuit 16 are connected, and the received echoes are delayed according to a reception delay time set in advance in this reception delay circuit 16, and then synthesized and output.

As a result of the above ultrasonic wave transmission and reception, transmission and reception are performed at the intersection point of the ultrasonic beam shown in FIG. The ultrasonic beam width is narrowed down, and the distance from the transducer to the intersection point P matches the focal length of the ultrasonic beam.

The output data from the receiving delay circuit 16 is sent to the receiving circuit 1.
After being amplified and detected in step 9, the signal is written into memory 22 and subjected to averaging processing by processing circuit 23. The processing results are sent to the calculation circuit 2 via the waveform analysis circuit 24.
5 is input. In the input data, the peak value of the waveform indicates the reflected wave from the intersection P, so
If the calculation circuit 25 detects the time of the peak value, the time of propagation 1 is t.
is found. Here, the transmission delay circuit 15. By applying a delay time in the reception delay circuit 16, the intersection point P of the transmitted and received ultrasonic beams is made to match the focal point, and as a result, the waveform of the received echo becomes a steep waveform as shown in FIG. 7(a). Peak value detection of this waveform, that is, the calculation circuit 25
The calculation of the propagation time t according to the method is more accurate than the conventional method.

The reason for this will be explained below with reference to FIGS. 5 (a>, (b)), FIG. 6, and FIGS. 7 (a), (b).

Figures 5(a) and (b) are illustrations of ultrasonic sound field formation, Figure 6 is an illustration of ultrasound beam intersection, and Figures 7(a) and (
b) is a characteristic diagram that does not show differences in received waveforms due to differences in focus of ultrasound beams.

The sound field created by the transducer array 11 of the ultrasound probe 1 is formed as shown in FIG. 5(a) when the focal length is infinite, and as shown in FIG. 5(b) when focused at distance F. As is well known, it is formed in Here, if the ultrasound beams cross each other in a spread state, such as when the focal length is infinite, the area of intersection becomes longer in the distance direction, so the received echo will be as shown in Figure 7 (a). As shown in ＞, the waveform becomes smooth over time.For this reason, it is difficult to detect the peak value of the waveform with high accuracy, and the propagation time 1-
measurement accuracy is low. On the other hand, when the ultrasonic beams are focused on the intersection region as shown in FIG. 6, the area of the intersection region is small and the length of the intersection region in the distance direction is also shortened. Therefore, the reception in this case]-]- is shown in Fig. 7(b).
As expected, the waveform becomes steep. Therefore, the peak value of the waveform can be detected with high accuracy, and the measurement accuracy of the propagation time t is higher than in the above case.

Based on the propagation time t obtained with high accuracy in this way, the correction circuit 25 excludes the first value of the sound speed C, which is the sound speed value Vi, from the equation (1) above, and also excludes the sound speed value Vi from the equation (5) above. The average value v1 of the first sound velocity values is calculated from the formula.

The calculation results are displayed on the display 2 as sound speed data.
6.

Various formats are possible for displaying sound velocity data on the display 26, but in this embodiment,
The sound velocity value V is digitally displayed, and the sound velocity value V
and its average value Vi is displayed in a graph. Figure 8 shows an example of this graph display, where the horizontal axis represents the number of measurements io
The vertical axis is the sound velocity value V1 and its average (direction Vi).In this way, if the average value Vi of the first up to each time is displayed as a graph at the same time, the measurement data will be stabilized depending on whether this graph fluctuates or converges. For example, if the fluctuation of the average 111Ivi is large (in this case, the amplitude of \/i also becomes large), it is possible to easily judge whether the
] - There may be a problem in the relative positional relationship between the ultrasonic wave transmitting/receiving surface 2 of the waveguide 1 and the living body to be examined, or there may be a non-uniform medium mixed into the ultrasonic propagation path. Therefore, in this case, the operator selects the block [1 - block 1] so that the fluctuation of the average value Vi is minimized.
When the fluctuation of the average value \/i is converged by this operation, the freeze switch 29 is turned on.

In other words, under the control of the system control means 27, the repetition of a series of operations such as transmission and reception of ultrasonic waves, measurement of propagation time, measurement of sound velocity values, and display display is stopped, and the display 26 shows the information displayed when the freeze switch 29 is turned on. The displayed content is maintained. Of course, if the freeze switch 29 is turned off again, the series of operations described above, such as transmission and reception of ultrasonic waves and measurement of propagation time, are repeated.

In this way, in the device of this embodiment, by matching the intersection point P of the ultrasound beam (directivity intersection point) with the focal point, it is possible to improve the measurement accuracy of the propagation time t.
As a result, the reliability of the sound speed data can be improved. In addition, by making the transmission and reception deflection angles θ of the ultrasonic waves equal, the reception delay time can be easily set based on the transmission delay time τ(X) obtained by the above equation (3), so the system control means The delay time data is reduced compared to 27. Roughly speaking, when the refreeze switch 29 is off, a series of operations such as transmitting and receiving ultrasonic waves, measuring propagation time, increasing the sound velocity value, and displaying the display are repeated, and when the freeze switch 29 is on, the series of operations described above is stopped. Moreover, since it continues to display the final data at that time, it can be said that it is a device that is easy to use and suitable for clinical settings. In particular, by graphically displaying the sound speed value Vi and its average value Vi on the display of the sound speed data, it is possible to easily check whether the data is stable or not.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above-mentioned embodiment, and can be modified as appropriate within the scope of the gist of the present invention.

Effects of the Invention] As detailed above, according to the present invention, it is possible to improve the accuracy of measuring the propagation time of ultrasonic waves. It is possible to provide an ultrasonic diagnostic device that can perform

4. Simple Explanation of Diagrams Fig. 1 is a block diagram of an ultrasonic diagnostic apparatus which is an embodiment of the present invention, and Figs. 2 and 3 are characteristic diagrams of transmission delay time and reception delay time, respectively, in the apparatus of this embodiment. , Figure 4 is an explanatory diagram of the relationship between the intersection and focus of the ultrasound beam, and Figure 5 (
a) and (b) are illustrations of ultrasonic sound field formation, Fig. 6 is an illustration of ultrasonic beam crossing, and Fig. 7 (a) and (b) are received waveforms due to differences in ultrasound focus. Characteristic diagram showing the difference between
FIG. 8 is an explanatory diagram showing an example of sound velocity data display in the apparatus of this embodiment, and FIG. 9 is an explanatory diagram of the measurement principle of ultrasonic propagation velocity.

15... Delay circuit for transmission, 16... Delay circuit for reception, 27... System control means, 29... Freeze switch (input means), T1 to T3
2: First transducer group, T9□ to T128: Second transducer group.

Road (0) (b)

Claims (1)

[Claims] The first and second parts are each formed by arranging a plurality of ultrasonic transducers.
It has a group of transducers, and detects ultrasonic waves in the tissue inside the subject's body from the received echo of the ultrasound transmitted from the first group of transducers toward the subject and received by the second group of transducers. In an ultrasonic diagnostic apparatus that calculates a propagation velocity for diagnosis, an excitation pulse used to excite each ultrasonic transducer constituting the first transducer group and an ultrasonic pulse constituting the second transducer group. By giving each of the received echoes from the sonic transducer a delay time that takes into account the ultrasound beam focal length, the first
a transmitting delay circuit and a receiving delay circuit for aligning the focus of the ultrasonic beam with the intersection of the directivity of the ultrasonic wave transmitted by the transducer group and the directivity of the ultrasonic wave received by the second transducer group. An ultrasonic diagnostic device comprising: