JPH0152021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus, and in particular, has a plurality of arranged ultrasonic transducers, and transmits and receives an ultrasonic beam toward a subject from the transducer surface, and this transmission and reception is carried out between the transducer surface and the transducer surface. The present invention relates to an ultrasonic diagnostic apparatus that is electronically scan-controlled so as to perform a plurality of consecutive scans that move approximately in parallel.

In recent years, ultrasonic diagnostic devices that perform diagnosis using ultrasound have been widely used. This ultrasonic diagnostic device utilizes the fact that tissues and organs within the body have different acoustic characteristics. That is, when ultrasonic waves are emitted into the body for a very short period of time, a portion of the ultrasonic waves will be reflected back from the boundaries of different tissues as they propagate through the human tissues. Because it takes time for ultrasound to propagate within the body, waves reflected from places close to the ultrasound emission point are returned quickly, and waves reflected from places far away are delayed. The emission of ultrasonic pulses is repeated at regular intervals, but since ultrasonic waves have short wavelengths, they can be concentrated and emitted in one direction, and in this way,
By detecting the reflected echoes that occur one after another as the ultrasound pulse propagates through the body and displaying them on a cathode ray tube or the like, it is possible to display the distribution of acoustic characteristics in the body's tissues. At this time, since healthy tissue and tumor tissue have different acoustic characteristics, it is possible to know the presence or absence of an abnormality within the tissue and its location from the pattern displayed on the cathode ray tube.

FIG. 1 shows a conventionally used electronic scanning type ultrasonic diagnostic apparatus, in which a transducer having a plurality of arrayed transducers 10-1, 10-2,...10-n is shown. 12, and transmits and receives the above-described ultrasonic beam from the transducer 10 surface of the transducer 12. Transmission and reception of such ultrasonic beams is performed by each transducer 10-1, 10-2,...10.
- Transducer/receiver 14-1, 1 provided corresponding to n
4-2, . In Figures 2 and 3,
This electronic scanning control is shown.

That is, as shown in FIG. 2, appropriate excitation control with different delay amounts is performed on a plurality of vibrators selected from the 10 planes of vibrators, and the vibrator 10 to be excited is
By increasing the amount of delay at the center of the waveform, the acoustic wave surface of the sound wave transmitted from the transducer 10 is made concave, and as a result, it is possible to transmit a composite ultrasound beam that is focused at a predetermined focal position. Then, in synchronization with the transmission of the ultrasound beam, the transducer 10 is controlled to receive reflected echoes, which are input to the delay addition circuit 20. Here, the same amount of delay as for transmission is added to the reflected echoes obtained via each transducer, and the received signals are calculated by adding these together, and the resulting received signals are output to a TV monitor, etc. via the high frequency amplifier 22. do. Then, as shown in FIG. 3, this operation is performed multiple times in succession by shifting the transducer one element at a time, thereby transmitting and receiving multiple ultrasonic beams that move approximately parallel to the surface of the transducer 10. With this, tomographic images are displayed on a cathode ray tube in almost real time.

Here, the number of arrayed vibrators 10 is n, 1
If the number of transducers to be controlled when transmitting and receiving the ultrasonic beam is m, the number N of scanning lines of the ultrasonic beam moving almost parallel to the transducer surface 10 is N=n-m+1...(1 ), and the image on the cathode ray tube is displayed based on the reflected waves of these N ultrasonic beams. Therefore, in order to improve the resolution of the image displayed on the cathode ray tube, it is sufficient to increase the number N of scanning lines of the ultrasound beam. However, due to the acoustic characteristics of ultrasonic waves, there are limits to the number n of arrayed transducers per unit length and the number m of transmitting/receiving controlled transducers per unit length, and there is a limit to the number N of scanning lines expressed by the first equation. For this reason, in conventional ultrasound diagnostic equipment, the density of the number of scanning lines N of ultrasound beams is coarse;
As a result, as shown in FIG. 5A, the image displayed on the cathode ray tube also becomes coarse, resulting in the disadvantage that sufficient resolution necessary for diagnosis cannot be obtained.

In order to improve these drawbacks, conventional ultrasound diagnostic equipment takes advantage of the fact that the central axis of the ultrasound beam coincides with the central axis of the transducer that transmits and receives it, and increases the scanning line number density of the ultrasound beam by 2. A double version was used. That is, by dividing the controlled number of transducers 10 into an even number and an odd number, as shown in Fig. 4, ultrasonic beams are created at intervals of 1/2 of the arrangement interval of the transducers, and 2N ultrasonic beams are generated. It was scanning a sonic beam. As a result, as shown in FIG. 5B, an image having twice the resolution as that of the conventional apparatus described above can be displayed on the cathode ray tube.

However, this limits the number of ultrasound scanning lines to 2N. Therefore, if you want to display an image with higher resolution and image quality on a cathode ray tube, you can either display the same received signal twice, or you can memorize the received signal once and connect the lines between adjacent lines. A method of displaying the results by weighting and adding them was adopted. However, the former method has the drawback of displaying the same line on the cathode ray tube, resulting in a strong mosaic-like image quality.
In addition, the latter method requires complicated arithmetic processing by a computer, and also requires extremely high arithmetic speed due to the need for real-time display. For this reason, the calculations actually performed are not sufficient, and the image displayed on the cathode ray tube, as shown in Figure 5C, emphasizes the outline of the target area, but the resolution deteriorates and the image is It had the disadvantage that it was blurry.

The present invention was made in view of the above-mentioned problems in the prior art, and its purpose is to receive the reflected waves of the two types of ultrasound beams transmitted by two groups of receiving transducers, and thereby obtain the following benefits. An image can be displayed based on the four received signals obtained without weighting the received signals or displaying the same signal multiple times, and the resulting image has sufficiently high resolution and excellent image quality. An object of the present invention is to provide an ultrasonic diagnostic device that can perform the following functions.

In order to achieve this object, the present invention has a plurality of arranged ultrasonic transducers, transmits and receives an ultrasonic beam from the transducer surface toward the subject, and this transmission and reception causes vibrations for each group of a predetermined number of transducers. In an ultrasonic transducer that is electronically scan-controlled so as to be shifted one child at a time and to perform multiple consecutive scans, a first ultrasonic beam is transmitted from a plurality of first transducer groups in a predetermined range,
a transmitting circuit that supplies an excitation signal to each vibrator so that a second ultrasonic beam is transmitted from a second vibrator group excluding one vibrator located at an end of the first vibrator group; a receiving unit that receives reflected echoes of the first ultrasonic beam at the first transducer group and the second transducer group, adds a predetermined delay, and outputs the received signals as two types of received signals; a first receiving circuit having a first storage circuit that stores two types of received signals from the second ultrasonic beam, performs one-quarter time compression, and outputs the compressed signals; A second receiving section receives the signals from the first transducer group and the second transducer group, performs predetermined delay addition, and outputs them as two types of received signals, and stores two types of received signals from this second receiving section. A second receiving circuit has a second storage circuit that performs 1/4 time compression and outputs the result, and receives two types of output signals from each of the first and second receiving circuits, and displays each signal on a screen. and an image processing section that performs signal processing so as to perform image display based on a total of four types of signals distributed to odd and even fields respectively.

Next, preferred embodiments of the present invention will be described based on the drawings. Note that the same reference numerals are given to the members corresponding to those of the above-mentioned device, and the explanation thereof will be omitted.

FIG. 6 shows a preferred embodiment of the ultrasonic diagnostic apparatus of the present invention, which includes a transducer 12 having a plurality of transducers 10 arranged similarly to the conventional apparatus, a transceiver 14, A transmission trigger control circuit 16 and an ultrasonic signal control circuit 18 that control the transceiver 14 are provided.

Then, in the same way as normal electronic scanning, an ultrasonic beam as shown in FIG.
A plurality of ultrasonic beams moving approximately parallel to the transducer 10 plane are obtained. In this embodiment, in performing the above scanning, the following control is performed in order to scan with 2N ultrasonic beams. That is, by utilizing the fact that the central axis of the ultrasonic beam coincides with the central axis of the array transducer 10 whose excitation is controlled,
As shown in FIG. 7, by alternately selecting even-numbered and odd-numbered oscillators from the 10 groups of oscillators in the transducer 12 and controlling their excitation, the 10 faces of the oscillators in the transducer 12 and Obtain 2N ultrasonic beams that move approximately in parallel and at intervals of 1/2 the array interval of each transducer. FIG. 8A shows the ultrasonic beam transmitted in this way, where the solid line shows the ultrasonic beam transmitted by controlling the excitation of an even number of transducers and the broken line by controlling the excitation of an odd number of transducers. . In the embodiment, the total number n of vibrators 10
= 64 transducers, and the number of even-numbered transducers to be excited controlled is set to m = 8, so the number of scanning lines of the ultrasound beam is
From equation (1) above, 2N is 2N=2(64-8+1)=114 2N=114.

A feature of the present invention is that the reflected echoes for one ultrasound beam transmission are received by two sets of 10 groups of transducers in different combinations, and two series of reception signals are simultaneously received by one ultrasound beam transmission. It is about forming. As a result, an image with high resolution and high quality can be displayed on the cathode ray tube without performing calculations such as weighting on the received signal and displaying it, or without performing processing such as displaying the same signal twice. for example,
In the embodiment, 2N ultrasonic beams are scanned, but according to the present invention, two series of received signals are obtained for one ultrasonic beam, so it is the same as doubling the scanning line density. You can think about it.
As a result, an image can be displayed on the cathode ray tube with the same resolution and quality as an image displayed based on scanning with 4N ultrasonic beams.

In this way, in order to simultaneously obtain two systems of reception signals for one transmission of an ultrasound beam, the apparatus of this embodiment is provided with two systems of receiving circuits 30 and 32. Then, the transmitter/receiver 14 is controlled in synchronization with the transmission of the ultrasonic beam, and the plurality of transducers 10 selected to receive the reflected waves of the ultrasonic beam are set in a receiving state. In the example, when eight transducers were used and the ultrasonic beam was transmitted,
Set the eight transducers as they are for reception,
When transmitting an ultrasonic beam using seven transducers, those seven transducers and one other adjacent transducer
A total of 8 transducers are set for reception. The reflected echoes received by the eight transducers 10 set in the receiving state in this manner are transmitted to two series of receiving circuits 3 via an ultrasonic signal control circuit 18.
0 and 32 respectively, and do the following:
Two series of received signals are obtained.

First, one of the receiving circuits 30 uses the eight input reflected echoes as they are to obtain one series of received signals. For this reason, the delay adding circuit 40 calculates the phase amount of each reflected echo using eight transducers in advance.
-1 is provided, and the eight reflected echoes that are input are subjected to delay addition based on the above-mentioned phase amount to calculate one series of received signals, which is outputted via the high frequency amplification circuit 42-1.

The other receiving circuit 32 selects seven reflected echoes from the input reflected echoes by a switching circuit 44, and obtains the other series of received signals based on these seven reflected echoes. For this reason, a delay addition circuit 40-2 is provided in which the phase amount of each reflected echo is calculated in advance using seven transducers, and the seven reflected echoes inputted via the switching circuit 44 are delayed based on the phase amount. Addition is performed to calculate the received signal of the other series and output it via the high frequency amplification circuit 42-2.

2 in each of the receiving circuits 30 and 32 as described above.
The calculations of the series of received signals are performed simultaneously.

In the embodiment, as described above, transmission of ultrasound beams by eight transducers T and transmission of ultrasound beams by seven transducers T are repeated. Therefore, when eight transducers T transmit ultrasonic beams, the delay addition circuit 40-1
, the reflected echoes are inputted via the eight transducers R shown in FIG.
Reflected echoes are input to the oscillator via the seven transducers R shown in FIG. 9b. These delay adder circuits 40-1 and 40-2 calculate received signals a and b shown as A _ODD and B _ODD in FIG. 46-
Enter each in 2. Next, when the ultrasonic beam is transmitted by the seven transducers T, the delay addition circuit 4
Reflected echoes are input to delay circuit 40-1 through eight transducers R shown in FIG.
2, reflected echoes are inputted via the seven transducers R shown in FIG. 9c. These delay adder circuits 40-1 and 40-2 calculate received signals d and c shown as D _ODD and C _ODD in FIG. 4
Enter each information in 8-2.

Each of these memory circuits 46-1, 46-2, 48-
1 and 48-2 time-compress the input and stored received signals a, b, d, and c at a compression rate of 4 using a known TV scanning line conversion method for ultrasonic received signals using a line memory, and display them. Via the signal selection circuit 50
output to the TV monitor, and as shown in E _ODD in Figure 10, the received signals a and b are displayed in the odd fields, and the received signals c and b are displayed in the odd fields.
Display d. Note that the memory circuits 48-1, 48-2
The inputs of the receiving circuits d and c to the storage circuit 46-
1 and 46-2 are performed while signals are being displayed in the fields . By repeating this operation, the odd field M=4n+1,
M=4n+2 (n=0, 1, 2...) in Figure 10.
E Displays the received signals shown in _ODD in sequence. When the display of the received signal in the odd field is completed, the same display method is used to display the even field M=4n of the TV signal to be scanned without interlace using the equivalent pulse control of the standard TV synchronization signal.
+3, M=4n+4 (n=0, 1, 2, . . . ), the received signals shown at E _EVEN in FIG. 10 are sequentially displayed.
In this way, an image with a scanning line density of 4N is displayed on the cathode ray tube, as shown in FIG. 8B.

The present invention has the above configuration, and its operation will be explained next.

First, when the transducers 10-1 to 10-8 are excited and controlled and an ultrasonic beam is transmitted, the reflected echoes are transmitted to each receiving circuit 3 via the transducers 10-1 to 10-8.
It is input to 0,32. The delay adding circuit 40-1 of the receiving circuit 30 is connected to the transducers 10-1 to 10-.
10 from the reflected echo input via 8.
One series of received signals a shown in A _ODD is calculated and stored in the storage circuit 46-1. At the same time,
Delay addition circuit 40-2 of the other receiving circuit 32
calculates the other received signal b shown in B _ODD in FIG.
to be memorized.

Then, the memory circuits 46-1 and 46-2 use the TV scanning line system of the ultrasonic reception signal using the known line memory, as shown in E _ODD in FIG.
The received signals a and b are time-compressed with a compression ratio of 4 and displayed in the odd field.

Next, when the transducers 10-2 to 10-8 are excited and controlled and an ultrasonic beam is transmitted, the reflected echoes are transmitted to each receiving circuit 3 via the transducers 10-2 to 10-9.
It is input to 0,32. The delay addition circuit 40-1 of the receiving circuit 30 is connected to the transducers 10-2 to 10-.
10 from the reflected echo input via 9.
The received signal d indicated by D _ODD is calculated and stored in the storage circuit 48-1. At the same time, the delay adding circuit 40-2 of the receiving circuit 32 has a switching circuit 44.
Due to the operation of
calculates a received signal c shown as C _ODD in FIG. 10 from these reflected echoes, and stores this in the storage circuit 48-2.

And these memory circuits 48-1, 48-2
The first
As shown in E _ODD in Figure 0, the received signal time-compressed with a compression rate of 4 is displayed in the odd field.

Repeat the above operation and set M of the odd field.
=4n+1, M=4n+2 (n=0, 1, 2...) The received signals shown in E _ODD in FIG. 10 are sequentially displayed.

After the received signal has been displayed on the odd field, the even field M=4n+3, M=4n+4 (n=0, 1,
2,...), the received signals shown at E _EVEN in FIG. 10 are sequentially displayed.

As a result, an image as shown in FIG. 8B is displayed on the cathode ray tube in real time.

The present invention can also be applied to an ultrasonic TV scan converter such as a digital scan converter or an XY monitor having a storage capacity for one frame. 11th
The figure shows an ultrasonic diagnostic apparatus used in such cases. In this device, the received signal calculated by the delay adder circuit 40-1 is directly transmitted to the display signal selection circuit 5 via the high frequency amplifier circuit 42-1.
The received signal inputted to 0 and calculated by another delay addition circuit 40-2 is inputted to the storage circuit 46 via the high frequency amplification circuit 42-2, where it is given a predetermined delay and then sent to the display signal selection circuit. 50 is entered. Therefore, the received signal shown in FIG. 12 will be displayed on the frame.

However, if this continues, the number of frames will be reduced by half. Therefore, when using the apparatus of the present invention for such purposes, it is sufficient to use the circuit shown in FIG. 6 and display the image on a frame with the compression ratio doubled as shown in FIG. 13.

Further, the present invention can be used not only for linear scan type ultrasound diagnostic equipment but also for other types of ultrasound diagnostic equipment, such as sector scan type ultrasound diagnostic equipment.

As described above, according to the present invention, each reflected echo due to the transmission of two types of ultrasound beams is
The four types of received signals obtained here can be displayed on one screen after performing processing such as predetermined time compression, so the received signals can be weighted and the same received signal can be displayed multiple times. Images with high resolution and high quality can be displayed without displaying them.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional ultrasound diagnostic device.
FIG. 2 is an explanatory diagram of the operation of a group of transducers that transmit an ultrasound beam, and FIG. 3 is an explanatory diagram of excitation control for the transducers performed when the ultrasound beam is continuously scanned multiple times along the transducer surface. Fig. 4 is an explanatory diagram of the excitation control of the transducer when scanning the ultrasonic beam at intervals of 1/2 of the arrangement interval of the transducers, and Fig. 5 is an image of the tomographic plane of the subject displayed on the cathode ray tube. 6th
The figure is a block diagram showing a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention, FIG. 7 is an explanatory diagram of excitation control for the transducer, and FIG. 8 is an illustration of the scanning density of the ultrasonic beam and the display on the cathode ray tube. FIG. 9 is an explanatory diagram showing the relationship between a transducer that transmits an ultrasound beam and a transducer that receives reflected echoes;
FIG. 10 is an explanatory diagram for converting a received signal into a TV display line with a compression ratio of 4, FIG. 11 is a block diagram showing another embodiment of the apparatus of the present invention, and FIG.
An explanatory diagram for converting the received signal of the device shown in the figure to a TV display line, etc., Figure 13 shows the received signal at a compression rate of 2.
FIG. 4 is an explanatory diagram when converting to a TV display line or the like. 10... Vibrator.

Claims (1)

[Claims] 1. A device that has a plurality of arranged ultrasonic transducers and transmits and receives an ultrasonic beam from the transducer surface toward the subject, and this transmission and reception is performed by one transducer for each predetermined number of transducer groups. In an ultrasonic transducer that is electronically scan-controlled so as to perform a plurality of consecutive scans at different times, a first ultrasonic beam is transmitted from a plurality of first transducer groups in a predetermined range to the first transducer group. a transmitting circuit that supplies an excitation signal to each transducer so that a second ultrasonic beam is transmitted from a second transducer group excluding one transducer located at an end of the first transducer; A receiving section that receives reflected echoes of the ultrasonic beam by the first transducer group and the second transducer group, adds a predetermined delay, and outputs them as two types of received signals; and two types of received signals from the receiving section. a first storage circuit that stores each of the received signals and compresses the received signals by one-fourth of the time and outputs the compressed signals;
a receiving circuit; a second receiving circuit that receives reflected echoes of the second ultrasonic beam at the first transducer group and the second transducer group, adds a predetermined delay, and outputs two types of received signals; and a second storage circuit that stores two types of reception signals from the second reception unit and compresses them by one-quarter time and outputs the compressed signals; 2 each from the receiving circuit
an image processing unit that receives different types of output signals and performs signal processing to distribute the signals to odd fields and even fields of the screen of each signal so as to perform image display based on a total of four types of signals. Ultrasound diagnostic equipment.