JPH0581141B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to ultrasonic diagnosis that uses ultrasonic waves to obtain diagnostic information such as B-mode information and Doppler mode information and displays this information. The present invention relates to an ultrasonic diagnostic apparatus, and particularly relates to an ultrasonic diagnostic apparatus capable of implementing a simultaneous reception method in multiple directions.

(Prior art) Ultrasonic diagnostic methods use anatomical information, typically represented by B-mode images, motion information of organs within the body, typically represented by M-mode images, and Doppler images, typically represented by blood flow velocity images. Functional information associated with the movement of a moving object within a living body using this effect is used for diagnosis.

Here, a method of scanning the inside of a living body using ultrasound waves will be explained. First, the electronic scanning method will be explained. The linear scanning method uses an array type ultrasonic probe (probe) consisting of multiple ultrasonic transducers arranged side by side, with each ultrasonic transducer as one unit.
This is a method in which a unit of ultrasonic transducer is excited and an ultrasonic beam is transmitted. For example, one
This is scanning in which the position of the transmitting point of the ultrasonic beam is electronically shifted by exciting the element so that the position of each unit changes one after another while shifting the pitch by each vibration. Then, the excited ultrasonic transducer is
The timing of the excitation is shifted between those located at the center of the beam and those located at the sides, and the resulting phase difference between the sound waves generated by each ultrasonic transducer is used to convert the reflected ultrasound waves into electronic waves. Focus. The reflected ultrasound is then received by the same vibrator that was excited and converted into an electrical signal (however,
The number of transducers used for transmission and reception is not necessarily the same. ), echo information from each transmitted and received wave is formed, for example, as a tomographic image, and the image is displayed on a TV monitor or the like.

In addition, in the sector scanning method, the excitation timing of each transducer is adjusted so that the transmission direction of the ultrasonic beam sequentially changes in a fan shape for each pulse of the ultrasonic beam for one unit of excited ultrasonic transducers. It changes according to the desired direction, and the subsequent processing is basically the same as the linear scanning described above.

Furthermore, in addition to the above-mentioned linear and sector electronic scanning, there is also mechanical scanning in which a transducer (probe) is attached to a scanning mechanism and ultrasonic scanning is performed by moving the scanning mechanism.

On the other hand, regarding the imaging method, there is a B-mode method in which signals accompanying ultrasound transmission and reception are synthesized as an ultrasound raster to form a tomographic image (B-mode image).

There is also an M-mode method using fixed scanning in the same direction. The image obtained by this M-mode method, that is, the M-mode image, represents temporal changes in the ultrasound transmitting/receiving site, and is particularly suitable for diagnosing moving organs such as the heart.

Furthermore, there is an ultrasonic Doppler (D mode) method, of which the ultrasonic pulse Doppler method is a typical example. In this D-mode method, when an ultrasonic wave is reflected by a moving object,
It utilizes the ultrasonic Doppler effect in which the frequency of reflected waves shifts in proportion to the speed of movement of the moving object, and it can collect data and two-dimensional images (CFM images) related to blood flow speed as the blood flow moves. I'm trying to get it.

FIG. 5 shows a conventional example. FIG. 5 is a block diagram of a sector electronic scanning type ultrasound diagnostic apparatus. That is, as shown in FIG. 5, the repetitive pulses output from the pulse generator 1, which determine the interval of ultrasonic pulses emitted into the living body, are sent to the transmission delay circuit 2,
After being given a predetermined delay time determined from the radiation direction and the focal point of the transmitted ultrasonic waves at _2-1 to 2 _-N , the ultrasonic waves are sent to the transducer drive circuits 3 _{, 3-1} to _3-N ,
Drive pulses that are each amplified to a predetermined magnitude and superimposed are formed. By this driving pulse, N ultrasonic transducers 4 _-1 of the array type ultrasonic probe 4 are
~4 _-N is driven and ultrasonic waves are emitted into the living body.

On the other hand, the ultrasound beam reflected from within the living body (not shown) is received by each transducer 4, _4-1 to 4-N of the array type ultrasound probe 4, and is received by the preamplifiers 5, 5-1 to ₄ - _N . After being amplified to the predetermined magnitude at 5 _-N , the signal is sent to reception delay circuits 6, _{6 -1} to _{6 -N} . Here, a delay time that is almost the same as that given in the transmission delay circuits 2, _{2 -1} to _{2 -N} is given, and then added to the received signals from other oscillators in the adder 7. .

The output signal of the adder 7 is sent on one side to a receiver circuit 20 for tomographic image display, and on the other side to a circuit 21 for detecting blood flow information, where it is subjected to predetermined signal processing. First, in the receiver circuit 20, after the signal amplitude is logarithmically converted in the logarithmic amplifier 8, the envelope of the received signal is detected in the envelope detection circuit 9, and the envelope of the received signal is detected in the A/D converter (A/D-C) 10. After being digitized, it is stored in the image memory 11.

On the other hand, in the blood flow information detection circuit 21, the output of the adder 7 is generated by the phase detection circuits 13 _-1 and 13 _-2 , the signal source 15, and the π/2 phase shifter 14, so that the output is almost the same as the frequency of the ultrasound signal. It is mixed (quadrature phase detection) with a reference signal having a certain frequency, passes through low-pass filters (L・P・F) 16 _-1 and 16 _-2 , and then is sent to an A/D converter (A/D-C )17 _-1 ,17
MTI filter (high pass filter) consisting of a digital filter after being digitized in _-2
18 _-1 and 18 _-2 remove signals from the heart and blood vessels (clutter signals) with very little Doppler frequency deviation, and only minute signals from blood cells are separated and detected. After this signal is subjected to, for example, frequency analysis in the arithmetic circuit 19, the center or spread (dispersion) of its spectrum is calculated, and the value is stored in the blood flow signal memory in the image memory 11. The tomographic image signal and blood flow signal obtained by electronically scanning the ultrasound beam are temporarily stored in the image memory 11, and the tomographic image is black and white.
Further, blood flow information (direction, speed) is displayed in color on the TV monitor 12.

On the other hand, in order to further improve this type of ultrasound diagnostic equipment as an image diagnostic device, it is necessary to increase the number of scanning lines of ultrasound images (increase the scanning line density) without sacrificing real-time performance. It is essential to obtain a highly visible image by obtaining a denser image or by increasing the number of frames (reducing the time required to form one screen). A method for increasing the number of scanning lines and frames will be described below.

That is, the number N _R of scanning lines is roughly expressed by the following equation (1).

N _R = r/N _F・N _S ...(1) r is the ultrasonic pulse repetition frequency, N _F is the number of frames, and N _S is the number of ultrasonic wave transmission/reception per direction. be.

Also, according to equation (1) above, the number of frames N _F is
It is shown by the following formula (2).

N _F = r/N _R・N _S ...(2) In this case, the number of times M _S transmits and receives ultrasound to obtain a tomographic image is normally N _S = 1, and the ultrasound pulse repetition frequency r = 4 kHz. , the number of frames N _F =30, the number of scanning lines N _R is calculated by the above equation (1) as N _R
≒133. This is because, as shown in FIG. 6, in the case of sector scanning, the intervals between scanning lines become coarse in deep parts of the living body, making it impossible to obtain a good tomographic image. Therefore, one possible method to increase the number of scanning lines N _R is to increase the ultrasound pulse repetition frequency r, but this would reduce the maximum depth of field and, on the other hand, increase the number of frames N _F
If it is made small, real-time performance will be impaired, which is not preferable in any case.

The above is for the case of tomographic images, but CFM
In the case of a Doppler tomographic image in which a blood flow image such as a blood flow image is displayed together with a tomographic image, the above-mentioned problems become even more noticeable. In other words, in a Doppler tomogram, the number of ultrasound transmissions and receptions N _S requires N _S ≧8, the ultrasound pulse repetition frequency r = 4 kHz, and the number of scanning lines N _R = 30.
Then, according to equation (2) above, the number of frames N _F is N _F
= 16, and even if the scanning angle is made small and the scanning line density is made the same as in the case of a tomographic image, the real-time performance will be extremely poor. In order to solve this problem, the ultrasonic pulse repetition frequency r may be increased to increase the number of frames N _F , but this would reduce the maximum depth of field. On the contrary, if the number of scanning lines N _R is decreased,
The scanning angle becomes narrower, the blood flow display range becomes narrower,
Undesirable.

As a method that can solve the above-mentioned problems, there is a multi-directional simultaneous reception method. This is the seventh
As shown in the figure, M types of reception directivity are set for one ultrasound transmission direction, and thereby information on M scanning lines is transmitted and received for one ultrasound transmission/reception. Obtainable. FIG. 8 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus that realizes this kind of simultaneous multi-directional reception system. Here, the configuration of the part in FIG. 8 is different from that in FIG. 5. I will explain about it.

That is, regarding the reception delay circuits, the one in Fig. 5 has one reception delay circuit 6 _-1 to 6 _-N per channel, whereas the one in Fig. 8 has M pieces per channel. (Reception delay circuit 6 _-1
-1 ~ 6 _-1-M ~ 6 _-N-1 ~ 6 _-NM ), regarding the adder,
The one in Fig. 5 has one adder 7, while the one in Fig. 8 has M pieces (adder 7
_-1 to 7 _-M ), regarding the receiver circuit, the one in Fig. 5 has one receiver circuit 20, whereas the one in Fig. 8 has M pieces (receiver circuit 20).
0 _-1 to 20 _-M ), regarding the blood flow information detection circuit, the fifth
In the diagram, one blood flow information detection circuit 2 is provided.
1, the one shown in FIG. 8 has M pieces (blood flow information detection circuits 21 _-1 to 21 _-M ). Regarding the image memory, the one shown in FIG. 8 uses a high-speed one (high-speed image memory 22).

According to the ultrasonic diagnostic apparatus shown in FIG. 8, it is possible to set M types of reception directivity for one ultrasound transmission direction, that is, it is possible to realize a simultaneous reception system in multiple directions. So, with this,
Information on M scanning lines can be obtained for one transmission and reception of ultrasonic waves.

By using such a multidirectional simultaneous reception system, it is possible to increase the scanning line density in a tomographic image, and a highly dense tomographic image can be obtained. In the case of a Doppler tomogram, one frame can be formed in the transmitting and receiving direction of 1/M, so the number of frames N _F
This can significantly improve real-time performance. It goes without saying that it is also possible to obtain a wide blood flow image display range by increasing the scanning angle, or to obtain a very dense Doppler tomographic image by increasing the scanning line density as in the case of tomographic images. .

(Problems to be Solved by the Invention) According to the conventional multi-direction simultaneous reception type ultrasonic diagnostic apparatus as described above, tomographic images with an increased number of scanning lines and frames can be obtained without impairing real-time performance. Although Doppler tomographic images can be obtained, there are the following problems. That is, for tomographic images, M sets of reception delay circuits and receiver circuits are required for simultaneous reception directions, and for Doppler tomographic images, M sets of blood flow information detection circuits are also required, resulting in an enormous circuit scale. It must be said that it is extremely difficult to realize this, including in terms of cost.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ultrasonic diagnostic apparatus that is capable of implementing a multi-directional simultaneous reception method while suppressing an increase in circuit scale as much as possible.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following means are taken to solve the above problems and achieve the objects.
That is, the present invention includes a plurality of transducers arranged in parallel constituting an array type ultrasound probe, and a plurality of memories provided for each of the transducers and storing echo data from each transducer separately. a means for adding the echo data read out from each of the memories; a signal processing system for processing the output from the adding means to generate an ultrasound image; and a signal processing system for generating an ultrasound image from the signal processing system. a means for displaying the echo data, and a means for controlling writing and reading of the echo data in the memory, the time at which the next echo data is written by the next ultrasonic transmission/reception from the time when the echo data is written into the memory; The present invention is characterized by comprising means for repeatedly reading out the echo data from the memory a plurality of times within a period of 1 to 3, and providing different directivity by giving a different delay time each time the echo data is read out from the memory.

(Function) With such a configuration, by means of controlling writing and reading, echo data is written from the memory within a period from the time when echo data is written to the memory to the time when the next echo data is written by the next ultrasonic wave transmission/reception. Since the data is repeatedly read out a plurality of times and a different delay time is given each time, the directivity is changed each time the data is read out, thereby implementing a multi-directional simultaneous reception system.

(Embodiment) An embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described below with reference to FIGS. 1 and 2. 1st
The figure is a block diagram showing a first embodiment of the present invention, and FIG. 2 is a timing diagram regarding data of the same embodiment. In addition, in Figure 1, Figures 5 and 8
The same parts as in the figure are given the same reference numerals.

As shown in FIG. 1, the repetitive pulses output from the pulse generator 1, which determine the interval of ultrasound pulses emitted into the living body, are sent to transmission delay circuits 2, 2 _-1
After being given a predetermined delay time determined from the radiation direction and focal point of the transmitted ultrasonic waves at ~2 _-N , the ultrasonic waves are sent to the transducer drive circuits 3 and _3-1 to _3-N , each having a predetermined size. A drive pulse that is amplified and weighted is formed. By this drive pulse, N pieces (N channels) of ultrasound transducers 4 _-1 to 4 _-N of the array type ultrasound probe 4 are driven, and ultrasound waves are emitted into the living body.

On the other hand, the ultrasonic beam reflected from within the living body (not shown) is received by each transducer 4, 4 _-1 to 4 _-N of the array type ultrasonic probe 4, and is sent to a preamplifier of each channel of the receiving system. 5, 5 _-1 to 5 _-N are output as amplified echo data. After being amplified to a predetermined size in the preamplifiers 5, _{5 -1} to _{5 -N} , the A/D-Cs 23, 23 _-1 to 23 _-N and multiport RAM prepared for all channels forming the reception delay system are etc. memory 24, 24 _-1 ~ 24 _-
Sent to _N.

The digitized echo data output from each channel of the reception delay system is summed for all channels in a digital adder 26, and then the echo data for all simultaneous reception directions forming the signal processing system, that is, M
Individually prepared latches 25, 25 _-1 ~ 25
_-M , digitizing receiver circuit 27, 27 _-1 ~2
3 _-M and digitized blood flow information detection circuit 28, 2
8 _-1 ~ 24 Sent to _-M .

Here, in the digitizing receiver circuit 27,
After the signal amplitude of the digitized echo data from each channel is logarithmically converted in the logarithmic amplifier 29, the envelope of the echo is detected in the envelope detection circuit 30, and the echo data is stored in the high-speed image memory 22.
Stored in

Further, in the digitized blood flow information detection circuit 28, the phase detection circuits 31 _-1 and 31 _-2 and the reference signal generators 32 _-1 and 32 _-2 generate a reference signal having a frequency almost the same as the frequency of the ultrasound signal. The MTI filter (high pass filter) _33-1 , _33-2 composed of digital filters mixes (digital quadrature phase detection) with the signal from the heart and blood vessels with extremely little Doppler frequency deviation. (clutter signal) is removed, and only minute signals from blood cells are separated and detected. After this signal is frequency-analyzed, for example, by the calculator 34, the center or spread (dispersion) of its spectrum is calculated, and the value is stored in the blood flow signal memory in the high-speed image memory 22. The tomographic image signal and blood flow signal obtained by electronically scanning the ultrasound beam are temporarily stored in the high-speed image memory 22, and the tomographic image is in black and white, and the blood flow information (direction, velocity) is in color. is displayed on the TV monitor 12.

Here, the conversion timing in A/D-C 23, 23 _-1 to 23 _-N , the memory 24, 24 _-1 to 24
- Timing to write data at _N , timing to read data, and latches 25, 25 _-1 to 24
- Latch timing at _M (latch pulse)
is the timing shown in FIG. 2, and is implemented by the control circuit 35.

With the above configuration, the digitized echo data of each channel is written into the memories 24, 24 _-1 to 24 _-N using write addresses generated by a clock of frequency _W. Next, data is read from the memories 24, 24 _-1 to 24 _-N using independent read addresses for each channel generated by a clock with frequency RE=M· _W .

As a result, the ultrasonic echo data of each channel obtained by one transmission/reception of ultrasonic waves can be read out with a delay time required to obtain M different reception directivities, and the digital adder 26 can read out the ultrasonic echo data of each channel obtained by transmitting and receiving ultrasonic waves once. After adding the minutes, the latch 25, 25 _-1 ~ 25 _-M
By separating the signals, it is possible to obtain received signals corresponding to M different reception directivities. In other words, the memories 24, 24 _-1 to 24 _-N of ultrasound echo data
This is a time-division operation for reading data.

Therefore, according to this embodiment, M types of reception directivity can be obtained with one digital reception delay system. Therefore, the circuit size of the reception delay system is reduced to 1/M compared to the conventional one, and simultaneous reception in multiple directions can be realized while tomographic images and Doppler tomographic images with an increased number of scanning lines and frames can be processed without compromising real-time performance. Obtainable.

Further, since the reception delay is performed by a digital method, there is an effect of improving delay accuracy and reducing artifacts due to reflections, etc., and it is expected that image quality will be improved.

Next, referring to FIGS. 3 and 4, the second embodiment of the present invention will be described.
An example will be explained. In the first embodiment, the signal processing system includes M latches 25, 25 _-1 to 24 _-M , digitizing receiver circuits 27, 27 -1 to 23 -M, and digitizing receiver circuits 27, 27 _-1 to 23 -M, which are prepared for all simultaneous reception directions, that is, _M latches. Blood flow information detection circuit 28, 28 _-1 to 24
_-M is provided, but in the second embodiment, only one system of digitizing receiver circuit 27 and digitizing blood flow information detection circuit 28 is provided, and these are connected to the first
This allows the operation to be performed M times faster than in the embodiment. In other words, the process from reading out ultrasonic echo data from the memories 24, 24 _-1 to 24 _-N to writing the data into the high-speed image memory 22 is a time-division operation. However, A/D-C2
The conversion timing in 3, 23 _-1 to 23 _-N , the timing to write data in memories 24, 24 _-1 to 24 _-N , and the timing to read data are based on the fourth
The timing shown in the figure is implemented by the control circuit 35.

With the above configuration, the same effects as in the first embodiment can be obtained, and the signal processing circuit can be
It can be reduced to about 1/M compared to that of the first embodiment.

In the first and second embodiments described above, the digitalized ultrasound diagnostic apparatus was explained as an example. Various modifications can be made within the scope of the configuration to obtain reception directivity in various directions.

[Effects of the Invention] As described above, in the present invention, by means of controlling writing and reading, within the period from the time when echo data is written in the memory to the time when the next echo data by the next ultrasound reception is written. In addition, the echo data is repeatedly read out from the memory multiple times, and a different delay time is given each time the echo data is read out, so that its directivity changes each time it is read out.
A multi-directional simultaneous reception scheme is implemented.

Therefore, according to the present invention, it is possible to provide an ultrasonic diagnostic apparatus that makes it possible to implement a multi-directional simultaneous reception method while suppressing an increase in circuit scale as much as possible.

[Brief explanation of the drawing]

FIG. 1 shows a first diagram of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 is a timing diagram regarding data of the same embodiment, FIG. 3 is a block diagram showing a second embodiment of the ultrasonic diagnostic apparatus according to the present invention, and FIG. 4 is a diagram showing the same implementation. Timing diagram for example data; Figure 5 is a block diagram showing a general electronic scanning ultrasonic diagnostic device; Figure 6 is a diagram showing scanning lines in sector scanning; Figure 7 shows the principle of simultaneous reception in multiple directions. FIG. 8 is a block diagram of a conventional multi-directional simultaneous reception type ultrasonic diagnostic apparatus. 1... Pulse generator, 2, 2 _-1 to 2 _-N ... Transmission delay circuit, 3, 3 _-1 to 3 _-N ... Vibrator drive circuit,
4...Array type ultrasonic probe, 5,5 _-1 ~5 _-N ...
... Preamplifier, 12 ... TV monitor, 22 ... High-speed image memory, 23, 23 _-1 ~ 23 _-N ... A/D
Converter (A/D-C), 24, 24 _-1 ~ 24 _-N ...
...Memory, 25, 25 _-1 ~ 25 _-M ...Latch, 2
6...Digital adder, 27, 27 _-1 ~ 23 _-M
...Digitization receiver circuit, 28, 28 _-1 ~
24 _-M ...Digitized blood flow information detection circuit, 29
... Logarithmic amplifier, 30 ... Envelope detection circuit, 31
_-1 , 31 _-2 ... Phase detection circuit, 32 _-1 , 32 _-2 ...
... Reference signal generator, 33 _-1 , 33 _-2 ... MTI filter (high pass filter), 34 ... Arithmetic unit 34.

Claims (1)

[Scope of Claims] 1. A plurality of transducers arranged in parallel constituting an array-type ultrasonic probe, and a plurality of transducers provided for each of the transducers and storing echo data from each transducer separately. a memory; means for adding the echo data read from each of the memories; a signal processing system for processing the output from the adding means to generate an ultrasound image; and the ultrasound image from the signal processing system. means for displaying the echo data; and a means for controlling writing and reading of the echo data in the memory, and writing the next echo data by the next ultrasonic transmission/reception from the time when the echo data was written in the memory. Ultrasonic diagnosis characterized by comprising means for repeatedly reading out the echo data from the memory a plurality of times within a period up to a time, and giving different directivity by giving a different delay time for each repetition. Device.