JPH0414012B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an ultrasonic diagnostic apparatus, and particularly relates to a linear electronic scanning type ultrasonic diagnostic apparatus that scans an ultrasonic beam by switching a plurality of ultrasonic transducers. It is something.

[Technical Background of the Invention] Electronic scanning type ultrasound diagnostic apparatuses include a linear scanning type in which an ultrasonic beam is moved in parallel and a sector scanning type in which the beam is deflected in a fan shape, depending on the purpose.

Among these, in the linear scanning method, a large number of ultrasonic transducers (hereinafter simply referred to as transducers) are arranged in a row on a plane, and a predetermined number of adjacent transducers are selected as a set using an electronic switch. The ultrasound waves are focused into a single beam by using the interference of the ultrasound waves generated by each excited transducer, and the echoes from that beam are received by each excited transducer to produce their respective signals. After the time axes are matched by delay times corresponding to the depths of biological reflection points so that they all match in time with the depths of biological reflection points, the ultrasonic echo signals are obtained by addition and synthesis. Then, each time one pulse of beam is transmitted and received, the set of transducers is selectively switched to the next new set of transducers shifted by one adjacent transducer, and this new set of transducers Excite about. In this way, by selecting a set of transducers to be excited each time one pulse of ultrasonic beam is generated, shifted by one transducer, the ultrasonic beam is sequentially adjusted to the pitch of one transducer. Move with. The linear scanning method utilizes this principle, in which the ultrasonic beam from the ultrasonic probe is fixed by selective excitation of the transducer while the probe is fixed in one place. It can be scanned in parallel.

In this case, the scanning line interval of the ultrasound beam is equal to the pitch of the center position of a group of transducers that are excited while being switched sequentially, so the smaller the transducer aperture of the ultrasound probe, the narrower the scanning line interval. can do.

On the other hand, a set of excited oscillator apertures, namely,
It is known that when the aperture (the total area of a set of transducers used to output one pulse of an ultrasonic beam) becomes smaller, the directivity at a long distance becomes duller and the azimuth resolution decreases. Therefore, in order to obtain sharp directivity, a somewhat large aperture is required.

Therefore, conventionally, as shown in FIG. 1, the transducers 6-1, to 6-M of the ultrasonic probe 6, which is constructed by arranging a large number of transducers 6-1 to 6-M, are used as a reference. For example, N switches are selected as one set by the high voltage analog switch 5 which operates under the control of the controller 2 which performs control in response to the reference signal a output from the signal generator 1, and the reference signal a is selected as one set. The transmission delay unit 3 gives a delay time corresponding to the position of the vibrator and the focus position to each corresponding transmission circuit of the transmission circuit group 4, thereby causing the drive pulses output from each transmission circuit to be Via the high voltage analog switch 5, the vibrator selected by the high voltage analog switch 5 is excited to transmit an ultrasonic beam.

As a result, the ultrasonic beam is formed by the ultrasonic waves generated by N transducers, so the aperture corresponds to the aperture area of N transducers, so even if the aperture size of each transducer is small, the aperture In addition to increasing the number of transducers, it is also possible to select one set of N transducers to be excited by switching one transducer to the adjacent transducer every time one pulse of the ultrasonic beam is generated, and moving the transducer position one pitch at a time. By doing so, the scanning line interval can be set to an interval corresponding to the arrangement pitch of one vibrator.

In this way, an aperture that is N times the transducer spacing can be obtained, so that the directivity is improved.

Incidentally, in order to improve spatial resolution, electronic focusing is generally performed in which a delay line is used in the transmitting and receiving system to electronically focus when transmitting and receiving ultrasonic waves.

For example, considering the transmission focus, as shown in FIG. The excitation timing of each transducer so that the ultrasonic beam is converged at a desired focus point when the transducer is excited is given as a delay time, and the reference signal a is transmitted to this transmission delay section 3.
and a signal delayed by the delay time corresponding to the position of each of the N oscillators, and each of these signals is applied to a corresponding transmission circuit of a transmission circuit provided corresponding to the N oscillators. Each of the vibrators generates an excitation pulse, which is applied via the high-voltage analog switch 5 to a vibrator at a corresponding position among a set of N vibrators selected to excite the vibrator. As a result, the excitation timing of each N vibrator is shifted by the respective delay time, and as a result, N
The ultrasonic waves emitted from each set of transducers form a concave composite wavefront, and the transmitted ultrasonic beam is focused at a desired point. As a result of this focusing, the beam diameter is narrowed down at the focal point, and the spatial resolution here is dramatically improved.

In addition, the reception focus detects the reflected wave propagating from the living body using the same vibrator as that used during excitation, and sends the reflected wave to the preamplifier group 7 through the high-voltage analog switch 5. a reception delay unit 8 which amplifies the signals by supplying the signals to preamplifiers provided corresponding to each of the transducers, and provides a delay time set corresponding to each preamplifier;
delay it.

This delay time is determined by a reception delay unit 8, which uses a delay element to give an appropriate delay time so that the signal phase from a certain set point in the living body matches, and then gives this delay time to an adder 9 to output N transducers. are added and synthesized here.

Then, the summation and synthesis output is detected by a video circuit 10, converted into a video signal, and provided to a display 11 to be displayed as an ultrasonic tomographic image. In this way, focus can be achieved only by processing at the time of reception.

Such ultrasonic diagnostic devices have entered a mature stage and are widely used and effective in diagnosis, but in recent years there has been an increasing demand for the development of small, low-cost devices that can be easily carried and selected.

Technically, digital technology has made remarkable progress, and ultrasonic devices are also being made smaller and lower in cost by going digital.
The problem with reducing costs is that N A/D converters for digitally converting the received signal are required for each set of N transducers, and a digital memory is also required in place of the delay element. That's true. Of these, digital memory has many other uses, and has become quite technologically advanced, becoming smaller and smaller.
Large-capacity, low-cost products are becoming available, but A/D converters are not used because the dynamic range of the ultrasonic reception signal is wide at 60 to 80 dB and the sampling frequency is high. Get A/
The package of the D converter is large and expensive, and the use of N such converters poses a major restriction in terms of cost and space factor.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a small, low-cost linear electronic scanning type ultrasonic diagnostic apparatus that makes full use of digital technology.

[Summary of the invention]

That is, in order to achieve the above object, the present invention uses an array type ultrasonic probe configured by arranging a plurality of ultrasonic receiving transducers in parallel, and uses a predetermined number of transducers of the ultrasonic probe. In an electronic scanning type ultrasound apparatus, an ultrasound beam is electronically scanned by selecting and exciting a predetermined number of transducers while sequentially changing their positions, and a video signal of an ultrasound image is obtained from the received signal. means for extracting the received signal of one vibrator at a predetermined position in the vibrator group each time it is excited; means for successively converting the extracted received signal into a digital signal; and storing the converted digital signal. a storage means; a means for reading digital signals of transducer reception signals corresponding to a predetermined number of transducer groups that are sequentially switched in response to electronic scanning among the digital signals stored in the storage means; A predetermined number of transducers of the ultrasonic probe are sequentially selected and excited by changing their positions to generate an ultrasonic beam. By doing so, the ultrasonic beam is electronically moved and scanned, and each time an ultrasonic wave is transmitted, only the received signal of one transducer at a predetermined position among the excited transducer group is extracted, converted into digital data, and then stored in the storage means. The transducer reception signals corresponding to a predetermined number of transducer groups that are sequentially selected in accordance with electronic scanning are read out from this stored data, synthesized, and converted into a video signal, from which an ultrasound image is generated. The digital signal to be stored in the storage means is only the received signal of the vibrator at a predetermined position among the excited vibrator group, and each time one set of vibrator groups is excited, the digital signal is stored in the storage means. The received signals are digitally converted and stored, thereby reducing the need for one A/D converter and reducing the amount of information stored at one time. The readout is performed as a digital signal of the corresponding transducer reception signal of a predetermined number of transducer groups that are sequentially selected in accordance with electronic scanning.
The reduction in the frame frequency of ultrasound images is also suppressed.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in Figures 2 to 4.
This will be explained with reference to the figures.

FIG. 2 is a block diagram showing the configuration of the apparatus of the present invention. In the figure, 11 is a reference signal generator that generates a reference signal a corresponding to the transmission repetition period of the ultrasonic beam, and 12 is a reference signal generator that generates a reference signal a corresponding to the transmission repetition period of the ultrasonic beam. A transmitting circuit 13 is a controller that operates in response to the reference signal a and switches the high voltage analog switch 5. This controller 5 controls the ultrasonic probe 6 in which M ultrasonic transducers are arranged in parallel, in units of T transducers (T<M), and the reference signal a.
The high-voltage analog switch 5 is controlled so as to select and switch T vibrators used for transmission and reception so as to shift one vibrator to the adjacent position each time the T vibrators are generated. The output of the transmitting circuit 12 is given to the vibrator via this high voltage analog switch 5.

14 is a preamplifier that amplifies the received output of one of the T oscillators obtained via the high-voltage analog switch 5; An analog-to-digital converter (hereinafter referred to as an A/D converter) converts the output of 14 into a digital signal, and 17 is a digital memory that stores the output of this A/D converter 15. N+1 according to the number of N transducers used for reception N>T
It has 1 line memory. Here, the line memory is a memory that stores the received signal of the ultrasonic echo obtained by one pulse of the ultrasonic beam.
The received signal of the oscillator on the time axis (in the depth direction of the living body)
It is stored based on the correspondence.

16 operates in response to the output signal of the reference signal generator 11, selects the line memory in which the output of the A/D converter 15 is to be stored, updates the address in accordance with the time axis, and performs readout. In this case, N line memories are sequentially read out while focusing on the depth direction of the living body, that is, while setting the read address of the line memory so that the phase of the received signal matches with the depth direction. It is a controller that goes.

Reference numeral 18 denotes an adder that adds and outputs data read out from N line memories of the digital memory 17 under the control of the controller 16;
A video circuit 9 converts the added data into a video signal, and a display 20 displays the output signal of the video circuit 19 as an image.

FIG. 3 is a block diagram showing an example of the configuration of the digital memory 17, in which 16 is the aforementioned controller and 18 is the aforementioned adder. The digital memory 17 has N+1 switches S1 to SN+1.
and line memories M1 to Mn+1 provided corresponding to these switches S1 to SN+1, and when one switch from S1 to SN+1 is selected by the controller 16, the A/D
The output of the converter 15 is applied to the line memory corresponding to the selected switch via the selected switch, and addresses corresponding to the time axis are sequentially designated to the line memory by the controller 16. When reading the contents of the line memories, the switches of the N line memories that store the latest data among the N+1 line memories are selected, and the contents of the N line memories are given to the adder 18. It's becoming like that.

Next, the operation of this device having the above configuration will be explained.

First, a signal a corresponding to the repetition period of the ultrasonic beam is output from the reference signal generator 11, and the transmitting circuit 12 is driven by this signal a to output a transmitting pulse.

On the other hand, the controller 13 operates in response to the signal a, and controls the high-voltage analog switch 5 every time the signal a is input to select adjacent T transducers among the M transducers of the ultrasound probe 6. The vibrator is selected while being shifted by one vibrator in one direction every time the signal a is generated.

As a result, T transducers are selected while sequentially changing their positions, and the transmission pulse output from the transmitting circuit 12 is applied to the selected T transducers via the high-voltage analog switch 5 to excite them. be done. Therefore, ultrasonic waves are transmitted from the T transducers, and ultrasonic pulses centered at the center positions of the T transducers are transmitted.

When T oscillators are excited, the controller 13
Immediately controls the high voltage analog switch 5 to extract only the received output of one of the vibrators.

The device is shown in FIG. Here, the explanation is given assuming that the number T of driving elements of the vibrator is five elements.

First, the transducer group corresponding to the ultrasonic probe 6 is excited with a transmission pulse to transmit ultrasonic waves, and when the echo is received, only the received signal of the transducer ′ at the center position in the transducer group is received. Select and extract, and also
When transmitting the next ultrasonic wave, select a new transducer group whose pitch is shifted by one oscillator from the previous transducer group, give it a transmission pulse, excite it and transmit the ultrasonic wave, and when receiving the echo, Each time an ultrasonic wave is transmitted, the transducer group is sequentially moved in parallel by one pitch and excited, so that only the received signal of the transducer' at the center position in the transducer group is selectively extracted. Extract the signal received by the vibrator.

The received signal selected by the high-voltage analog switch 5 and controller 13 in this way is amplified by one preamplifier 14, and then applied to one A/D converter 15 to be converted into digital data. .

Here, the received signal l amplified by the preamplifier 14 is converted from an analog signal to a digital signal and recorded in the digital memory 17 at the next stage. Here, the frequency of the sampling clock signal i of the A/D converter 15 is generally said to be about 10 times the ultrasonic frequency, and for example, when a 5 MHz vibrator is used, it will be about 50 MHz. Further, the number of bits of the A/D converter 15 is determined by the dynamic range of the ultrasonic echo, and if the dynamic range is 80 dB, approximately 14 bits or more is required. However, since such an A/D converter is difficult to obtain at present, as a countermeasure, an STC is installed in the preamplifier 14.
(Sensitivity Time Control) is installed to obtain only signals in the necessary level range in accordance with the level of echoes that attenuate depending on the depth position of the living body, and to reduce the number of bits of the A/D converter. You should do it.

In this way, the received signal is sampled at high speed and sequentially converted into a digital signal, which is applied to the digital memory 17 and recorded.

The digital memory 17 is configured as shown in FIG. 3, and the controller 16 responds to the output of the reference signal generator 11 at the stage when the received signal ' explained in FIG. The switch S1 is selected and the digital signal is given to the line memory M1 corresponding to this switch S1, and the line memory M1 is set to the write mode by the signal q-1 output from the controller 16 to record the signal. .

Similarly, when the aforementioned signal '' is received, the switch S2 is selected and the signal is recorded in the line memory M2.

In this way, the received signals are sequentially recorded in the line memories M3, . . . MN.

Then, when the received signal N+1' is input, the switch SN+1 is selected and the received signal is recorded in the line memory MN+1, but at the same time, the line memory M1 in which the received signal has already been recorded is , ~MN are sequentially focused in the depth direction of the living body using the controller 16, that is, by setting the read address of the line memory so that the phase of the received signal matches the depth direction, and reading these lines. Adder 18 adds data read from memories M1, ~MN.
are added and synthesized here.

This results in one raster (one scanning line) of ultrasonic waves.
data is obtained.

Next, when a received signal of N+2' comes in,
This time, the received signal is recorded again in the line memory M1, and at the same time data is read out from the line memories M2, .about.MN+1. Next, the received signal is recorded in the line memory M2, and read out in the line memories M3, .about.MN+1 and M1.

By doing this, the readout data of the ultrasonic reception signal is not given to the adder 18 from the first ultrasonic pulse transmission to N○, but after that, the data recorded up to the previous time is not given to the adder 18 every time an ultrasonic pulse is transmitted. The N received signals are read out from the line memory and given to the adder 18, and outputted from the adder 18 as waveform-matched received signals. The output after this addition is given to a video circuit 19 to be converted into a video signal, and then given to a display 20 to display an image at a display position corresponding to the ultrasound beam scanning position with the ultrasound probe as a reference. will be displayed and the ultrasound image will be visible.

In this way, using multiple line memories, the received signals of the vibrator at the center position of the excited vibrator group are sequentially recorded in the selected line memory in a predetermined order, and the N signals recorded up to the previous time are By reading out the contents of the line memory, synthesizing it, and displaying it, each line memory records the received signal obtained when each vibrator is excited, corresponding to each vibrator, although there is a time lag. If the method is to excite T transducers at a time to obtain an ultrasound image, the contents of the line memory that records each received signal of N adjacent transducers will be read out and the depth direction will be matched. If these read contents are added in this state, the reception focus is achieved and the reception signal of the ultrasonic echo on the line of the center position of the N reception transducers is obtained. and,
In this device, each time a newly selected T transducer group is excited, only the output of the transducer at the center position is recorded in the line memory, and at the same time one raster is recorded from the other recorded line memories. By reading out the echo information for 10 minutes, the ultrasonic tomographic image can be displayed without lowering the frame frequency of the ultrasonic tomographic image. Also, according to this method,
Since data for only one oscillator is recorded at a time, only one preamplifier and one A/D converter are required, and the device can be made smaller and lower in price.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with appropriate modifications within the scope of the gist thereof.For example, in the above embodiments, the number of vibrators driven simultaneously is In the explanation, it is assumed that there are five, but the number may be one or several, and the number of preamplifiers and A/D converters is not limited to one, but a plurality of preamplifiers and A/D converters can also be used together. However, in this case, the number of line memories needs to be equal to the number of A/D converters plus N.

〔Effect of the invention〕

As described in detail above, the present invention uses an ultrasonic probe configured by arranging a plurality of transducers for transmitting and receiving ultrasonic waves in parallel, and sequentially changes the position of a predetermined number of transducers of this ultrasonic probe. In an electronic scanning type ultrasound apparatus, an ultrasound beam is electronically scanned by selectively exciting the ultrasound beam, and a video signal of an ultrasound image is obtained from the received signal. 1 at a predetermined position in the transducer group
means for extracting the received signal of the vibrator, means for sequentially converting the extracted received signal into a digital signal, storage means for storing the converted digital signal, and each digital signal stored in the storage means. Means for reading digital signals of corresponding transducer reception signals of a predetermined number of transducer groups that are sequentially switched in response to electronic scanning among the signals, and synthesizing the plurality of read digital signals to form a video signal. means for electronically moving and scanning the ultrasonic beam by selecting and exciting a predetermined number of transmitting transducers of the ultrasonic probe while sequentially changing their positions to generate an ultrasonic beam; At the same time, only the received signal of the vibrator at a predetermined position of the group of vibrators excited each time an ultrasound is transmitted is extracted and converted into a digital signal, and then stored in a storage means. The digital signals of the transducer reception signals corresponding to a predetermined number of reception transducer groups sequentially selected are read out and synthesized, and converted into a video signal, from which an ultrasound image is obtained and stored in the storage means. The digital signal to be generated is only the signal received by a transducer at a predetermined position among the excited transducer group, and each time a set of transducers is excited, the received signal from one transducer at a predetermined position is digitally converted and stored. A/
Fewer D converters are required, and the amount of information stored at one time is smaller, so it can be stored at high speed, and readout corresponds to a predetermined number of transducer groups that are sequentially selected in accordance with electronic scanning. To provide a small and inexpensive electronic scanning type ultrasonic diagnostic device capable of displaying an ultrasonic image without lowering the frame frequency of an ultrasonic tomographic image by converting the transducer received signal into a digital signal. I can do it.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of a conventional device, Figure 2 is a block diagram showing the configuration of the device of the present invention, and Figure 3 is a block diagram showing the configuration of the device of the present invention.
The figure is a block diagram showing the configuration of the digital memory, and FIG. 4 is a diagram for explaining the relationship between the excitation vibrator and the vibrator for extracting the received signal in the present invention. 5...High voltage analog switch, 6...Ultrasonic probe, 6-1, 6-M...Ultrasonic transducer, 11...Reference signal generator, 12...Transmission circuit, 13, 16...Controller, 14...Preamplifier , 15...Analog・
Digital converter, 17...Digital memory, 1
8...Adder, 19...Video circuit, 20...Display device,
S1~SN+1...Switch, M1~MN+1...Line memory.

Claims (1)

[Claims] 1. Using an ultrasonic probe configured by arranging multiple transducers for transmitting and receiving ultrasonic waves in parallel, a predetermined number of transducers of this ultrasonic probe are selected and excited while sequentially changing their positions. In an electronic scanning type ultrasound device that electronically scans an ultrasound beam and obtains a video signal of an ultrasound image from the received signal and displays the ultrasound image, each time the predetermined number of transmitting transducer groups are excited. 1 at a predetermined position in the group of transducers
means for extracting the received signal of the vibrator, means for sequentially converting the extracted received signal into a digital signal, storage means for storing the converted digital signal, and each digital signal stored in the storage means. Means for reading out stored digital signals of transducer reception signals corresponding to a predetermined number of reception transducer groups that are sequentially switched in response to electronic scanning among the signals, and a video signal by combining the plurality of read digital signals. 1. An ultrasonic diagnostic apparatus comprising: means for converting