JPH0226548A - Ultrasonic diagnosing device - Google Patents

Abstract

PURPOSE:To improve the accuracy of a delay time and to cause the accuracy of a resolution to be good by providing an analog reception delaying means to cause the delay time to be variable at the delay time successively in a small step in the preceding stage of a digital reception delaying means. CONSTITUTION:In the preceding stage of a digital delay line 25 to delay an ultrasonic echo signal obtained from an object, an analog small delay line 23 and an A/D converter 24 are provided. The analog small delay line 23 can cause the delay time of the echo signal to be variable successively in the small step. The delay times of the analog small delay line 23 and digital delay line 25 are controlled by a control part 10. The output of the digital delay line 25 is supplied through adders 26a and 26b, receivers 7a and 7b and a DSC 8 to a display part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasonic diagnostic apparatus equipped with a reception delay means for delaying echo signals in ultrasonic diagnosis.

(Prior art) Fig. 5 is a diagram showing an ultrasonic diagnostic apparatus that employs a sector electronic scanning method, Fig. 6 is a diagram showing how an ultrasound beam is deflected by electronic scanning, and Fig. 7 is a diagram showing a delay line. It is a figure showing an effect. In FIG. 5, a B-mode image is obtained on the display section 9 by an ultrasonic transducer l having n divided elements la to 1n.

First, as shown in FIG. 5, different delay times tl, t2...
- A transmission pulse having tn is transmitted from the reference pulse generator 11 to the transmission delay line 2. The signal is input via the balsa 3 to each element 1a-In of the ultrasonic transducer 1.

Then, as shown in FIG. 7, each element la~
Ultrasonic waves are transmitted with a delay of delay times tl, t2, . . . tn from 1n. That is, as shown in FIG. 6, the wavefronts 13 of these ultrasonic waves are combined and an ultrasonic beam is transmitted toward the object 12 to be observed.

When the ultrasonic beam hits the object 12, it is reflected and an echo signal 19 is transmitted to each of the elements 1a to 12.
The waves are received with delay times tl, t2...tn.

This echo signal 19 is then transmitted to the preamplifier 4 (4a to 4n).
) and the delay time tl is amplified by the reception delay line 5 (5a to 5n) which is subjected to delay control by the control unit IO.

t2...Delay time rl having a pattern opposite to tn.

r2 .

Note that the delay time pattern can be changed to scan the ultrasonic beam in a desired range, and ultrasonic echoes from the two-dimensionally distributed object 12 can be obtained to be displayed as a B-mode image.

By the way, the delay times tl, t2...tn and the delay times "l..."n are set with an accuracy of about 10nJf by the transmission delay line 2 and the reception delay line 5. Ultrasonic transmission For this purpose, it is sufficient to apply a binary electric pulse to the transducer 1, and the transmission delay line 2 can be easily constructed with a digital circuit, allowing highly accurate delay control.

On the other hand, when receiving ultrasonic waves, it is necessary to apply a delay in steps of approximately 1Qns to received echoes that include many frequency components generated in each element of the transducer and have a wide dynamic range. If this is done digitally, an A/D converter is connected to each of the simultaneous receiving elements, and the reception echo obtained from each element is directly A/D converted, and a shift register or the like is used to adjust the data read time to 10 nm. A possible method is to perform control in steps of s. However, in this case,
The delay quantization accuracy is the conversion rate of the A/D converter, so to obtain the delay quantization accuracy of Ions, l /
It is necessary to use as many A/D converters as there are simultaneously receiving elements, each operating at a conversion frequency of 10 ns = 100 MHz. An A/D converter that satisfies this performance is very expensive, has a large size, and consumes a large amount of power, so it is extremely difficult to implement it using this. A method using an inexpensive A/D converter with a slow conversion rate (for example, 50 ns) results in degraded resolution and increased artifacts. Therefore, generally the coil L and capacitor C
An analog reception delay line consisting of the following is used, and the precision of the delay time is ensured on the order of a long time.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional analog reception delay line,
There are the following problems. That is, (1) frequency characteristics are poor.

(2) Artifacts occur due to crosstalk and signal waveforms are disturbed.

(3) Signal waveform is disturbed by reflection.

(4) There is large variation in delay time.

There is a problem in that the B-mode image deteriorates due to factors such as the following.

On the other hand, as a technology that increases the number of scanning lines to obtain detailed ultrasound images and improves real-time performance by increasing the number of frames without changing the number of scanning lines, ultrasonic waves that employ multiple simultaneous reception methods are being developed. There is a sonic device.

FIG. 8 is a diagram showing a multi-directional simultaneous reception system, and FIG. 9 is a diagram showing a schematic configuration when two-directional simultaneous reception is performed. As shown in FIG. 9, the ultrasonic device employing the multiple simultaneous reception method has two reception delay lines 5 (5aL to 5n2) and two reception delay lines 5, as compared to the device shown in FIG.
Two adders 8 correspond to (5al to 5n2)
a, 8b and receiver 7a.

7b is provided. Then, as shown in FIG. 8, an ultrasonic beam having reception directivity 18 based on the two-way simultaneous reception system is transmitted. However, since this device uses an analog reception delay line, it is not possible to set multiple reception directivities at the same time.

For this reason, it is necessary to have as many reception delay units as there are simultaneous reception directions, which poses a problem in that the system becomes enormous.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that can improve the accuracy of delay time, improve resolution, and improve image quality by reducing artifacts caused by reflections and crosstalk, and which has a simple configuration. The goal is to provide equipment.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems and achieve the objects, the present invention takes the following measures. That is, the present invention transmits and receives ultrasonic waves to and from a subject from an ultrasonic transducer consisting of a plurality of elements, delays the resulting echo signals using a digital reception delay means, and adds the delayed signals to generate ultrasonic waves. In an ultrasonic diagnostic apparatus for obtaining sonic diagnostic information, analog reception delay means for continuously varying the delay time in small steps is provided upstream of the digital reception delay means.

In addition, ultrasonic waves are transmitted and received from an ultrasonic transducer made up of multiple elements to and from the subject, the resulting echo signals are delayed by a digital reception delay means, the delayed signals are added, and low-pass filtering is performed. In the ultrasonic diagnostic apparatus for obtaining ultrasonic diagnostic information, multiplication means for multiplying the digital signal by the phase control signal is provided before or after the digital reception delay means.

(Effects) By taking such measures, the following effects are achieved. According to the present invention, since the analog reception delay means is provided before the digital reception delay means, the delay time can be changed continuously in small steps by the analog reception delay means. As a result, even if the conversion rate of the A/D converter used in the digital delay means connected after the analog reception delay means is slow, the precision of the delay time can be improved and phase matching can be achieved appropriately. The analog reception delay means in the previous stage has a minute delay time, so it can be easily manufactured with good characteristics.Furthermore, the reception delay means connected in the subsequent stage is constructed digitally, so the signal is Ultrasonic diagnostic images can be obtained without deterioration.

Furthermore, since received echoes can be stored in the digital delay means, simultaneous reception in multiple directions (reception directivity settings in multiple directions) can be performed with a single system of reception delay means, increasing the number of scanning lines and frames. can be easily carried out.

In addition, since the multiplication means can perform phase matching that is higher than the A/D conversion rate, a high-resolution, low-artifact ultrasound image can be obtained, and each point on the image to be reproduced can be focused for reception, resulting in a high-resolution image. can get.

(Example) Fig. 1 is a schematic configuration diagram showing an embodiment of an ultrasonic diagnostic apparatus that employs a two-way simultaneous reception method according to the present invention, and Fig. 2 shows an ultrasonic diagnostic apparatus that uses a one-way reception method. FIG. Note that the same parts as those in the conventional device will be described with the same reference numerals. This ultrasonic diagnostic apparatus is provided with an analog small delay line 23 upstream of the A/D converter 24 and digital delay line 25.

The analog small delay line 23 continuously varies the delay time of the echo signal in small steps, and can easily be manufactured with good characteristics.

Figure 3(a) shows an analog small delay line 23 using the tap method.
FIG. 3(b) is a diagram showing a continuously variable analog small delay line 23b. The analog small delay line 23a using the tap method has a plurality of taps 31 on the coil 31.
A to 31e are provided, and a plurality of switches 32 (32a to 32e) are provided corresponding to the plurality of taps 31a to 31e, so that the delay time can be varied in small steps. The continuously variable delay line 21b continuously changes the capacitance C of the variable capacitance diode 3B by the control circuit 34, and continuously changes the delay time based on the LC constant with the coil 31. In this case, since the characteristic impedance of the delay line changes depending on the value of C, the FET 35 is used as a matching resistor, and the resistance value of the FET 35 is changed together with the value of C to achieve matching. therefore,
The analog small delay line 23 connects the ultrasonic transducer 1
The maximum delay time of 40nsec for the echo signal received at each element is 10nsec.
It is given by the delay time of the step. A/D
Converter 24 converts the delayed signal to 20MHz8b
It is sampled every 1 t, that is, every 50 nsec, and converted into a digital signal.

The digital delay line 25 is made of a RAM, for example, and digitally delays the digital signal by 50nse.
This gives a delay time of c steps. The receiver 7 detects the combined ultrasonic echo signal and converts it into a B-mode image signal. DSC (Digital
5canConverter) 8 converts the output signal of the receiver 7 into a B-mode image. The display section 9 displays the output image of the DSC &.

Next, the operation of the embodiment configured as described above will be explained. The ultrasonic beam is transmitted to and received from an object, and the echo signals input to each element 1a to 1n of the transducer 1 are amplified by the preamplifier 4 and output to the analog small delay line z3. The echo signals of each element are matched in phase by the analog small delay line 23 with a delay accuracy of 1 On sec step, and are matched in phase by the A/D converter 24.
The signal is sampled at 0nsec and further delayed by 50nsec by digital delay line 25. Then, the echo signals are combined into one by the digital adder 26, detected by the receiver 7, configured into a B-mode image by the DSC 8, and the B-mode image is displayed on the display section 9. Note that when multiple simultaneous receptions are performed as described above, the echo signals are stored in the digital delay line 23, and the delay time can be set only by timing control during readout, so only one system is required.

As described above, according to this embodiment, since the analog reception delay line 23 is provided before the digital delay line 25,
This analog reception delay line 23 allows the delay time to be changed continuously in small steps. As a result, even if the conversion rate of the A/D converter used in the digital delay means connected after the analog reception delay means is slow, the accuracy of the delay time can be improved and phase matching can be achieved appropriately.

The analog reception delay means in the previous stage has a minute delay time, so it can be easily manufactured with good characteristics.Furthermore, the reception delay means connected in the subsequent stage is constructed digitally, so the signal is Ultrasonic diagnostic images can be obtained without deterioration. Furthermore, since received echoes can be stored in the digital delay means, simultaneous reception in multiple directions (reception directivity settings in multiple directions) can be performed with a single system of reception delay means, increasing the number of scanning lines and frames. can be easily carried out.

Next, a second embodiment of the ultrasonic diagnostic apparatus of the present invention will be described with reference to FIG. Preamplifier 4 and 50ns e
Digital delay lines 41a, 41b are connected to the output of the memory 40 via the A/D converter 24 sampling at
, a multiplier 41a that multiplies the signal delayed by the digital delay line 41 and the phase control signal whose phase is controlled.
, 41b, adders 42a, 42b for adding echo signals of a plurality of elements, and LPFs 43a, 43b for low-pass filtering are arranged in parallel.

The operation of the embodiment configured in this way will be explained.

The echo signal is amplified by the preamplifier 4, converted to a digital signal by the A/D converter 24, and stored in the memory 40. This echo signal is then branched into digital delay lines 41a and 41b, and each echo signal is multiplied by the echo signal delayed by 50 nsec by a phase control signal by multipliers 42a and 42b, so that the phases thereof are matched. The multiplied signals are then sent to adders 43a, 4
3b, and low-pass filtering is performed by LPF44a, 44b to obtain an image.

Therefore, it is possible to perform phase matching that is better than that achieved by A/D conversion, so a high-resolution, low-artifact ultrasound image can be obtained, and since the reception focus can be applied to each point on the image to be reproduced, a high-resolution image can be obtained. It will be done.

Note that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, ultrasonic waves are transmitted and received from an ultrasonic transducer including a plurality of elements to and from a subject, and the echo signals obtained thereby are delayed by a digital reception delay means. In an ultrasonic diagnostic apparatus that obtains ultrasonic diagnostic information by adding together the signals obtained by adding signals, an analog reception delay means that continuously varies the delay time in small steps is provided before the digital reception delay means, so that the accuracy of the delay time can be improved. Since signal processing is roughly performed digitally, artifacts caused by single reflections and crosstalk can be reduced to improve image quality, and an ultrasonic diagnostic apparatus having a simple configuration can be provided. In addition, phase matching can be performed at a rate higher than the A/D conversion rate, resulting in high resolution.

Since an ultrasonic image with low artifacts can be obtained and the reception focus can be applied to each point on the image to be reproduced, it is possible to provide an ultrasonic diagnostic apparatus that obtains high-resolution images.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of an ultrasound diagnostic apparatus employing a two-way simultaneous reception method according to the present invention, and FIG. 2 is a diagram showing an ultrasound diagnostic apparatus employing a one-way reception method. FIG. 3(a) is a diagram showing the configuration of an analog small delay line using a tap method, FIG. 3(b) is a diagram showing a continuously variable analog small delay line, and FIG. 4 is a diagram showing a second embodiment of the present invention. FIG. Fig. 5 is a diagram showing an ultrasound diagnostic apparatus that employs the conventional sector electronic scanning method, Fig. 6 is a diagram showing how an ultrasound beam is deflected by electronic scanning, and Fig. 7 is a diagram showing the effect of a delay line. 8 are diagrams showing a multi-directional simultaneous reception system, and FIG. 9 is a diagram showing a schematic configuration when two-directional simultaneous reception is performed. ■...Ultrasonic transducer, 2...Transmission delay line, 3...Pulser, 4...Preamplifier, 5...Reception delay line, 6...Adder, 7...Receiver 8.・・・
DSC. 9...Display unit, 10...Control unit, 11...Reference pulse, 12...Object to be observed, 13...Wave front of the transmitted wave in each element of the transducer, 14...
Combined wavefront, 15... Direction of ultrasound beam, 16
...Shape of transmitted ultrasound beam, 17... Transmission directivity, 18... Reception directivity, 19... Transmission waveform in each element, 20... Transmission waveform in each element, 21... Received waveform in each element with aligned delay times, 22... Combined received waveform, 23.
...Analog small delay line, 24...A/D converter, 25
...Digital delay line, 2B...Digital adder.

Claims (2)

[Claims] (1) Ultrasonic waves are transmitted and received from an ultrasound transducer made up of multiple elements to and from a subject, the resulting echo signals are delayed by a digital reception delay means, and the delayed signals are added together for ultrasound diagnosis. An ultrasonic diagnostic apparatus for obtaining information, characterized in that an analog reception delay means for continuously varying the delay time in small steps is provided upstream of the digital reception delay means. (2) Ultrasonic waves are transmitted and received from an ultrasound transducer consisting of multiple elements to and from the subject, the resulting echo signal is delayed by a digital reception delay means, the delayed signals are added, and low-pass filtering is performed. What is claimed is: 1. An ultrasonic diagnostic apparatus that obtains ultrasonic diagnostic information by using a multiplier for multiplying the digital signal by a phase control signal, the ultrasonic diagnostic apparatus comprising: a multiplier for multiplying the digital signal by a phase control signal, either before or after the digital reception delay means.