JPS6160695B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic focus type ultrasonic diagnostic apparatus that uses an array probe and is capable of real-time display.

As shown in FIG. 1, an array type probe 1 used in an ultrasonic diagnostic apparatus includes, for example, a plurality of ultrasonic transducers (hereinafter referred to as elements) 2 arranged in parallel in a straight line.
One group of a predetermined number (seven in the figure) of these two is selectively connected to the delay circuit 4 via the switching circuit 3, and when excited, the The acoustic field is configured to be focused onto a focal region A. Then, by operating the switching circuit 3 and shifting the excited elements one by one, the focal region A is also shifted by a distance corresponding to one element, and linear scanning is performed. In addition, by suitably variably setting the time constant in the delay circuit 4, each element 2...
If the phase difference of the signals given to ... is made different from the above, the ultrasonic sound field will be focused on the focal region B. When multiple focal areas are generated using signals with different phase differences in this way, it is called a dynamic focus method, and areas A and B are focused by appropriately setting the phase difference. be able to. Although the case of transmission has been described above, the case of receiving reflected waves is almost the same. However, the reception delay circuit used is one that can delay the received waveform without changing it.

Now, if the total number of elements used is n, the number of elements excited simultaneously is m, and the number of switching times is N, then
There is a relationship of N=n-m+1. On the other hand, if the depth of the measurement part of the person to be diagnosed is l and the speed of sound in the body is C, then the time t required for one scanning line is expressed as t=2l/C+a. However, a is a margin time for eliminating effects such as switching time and reverberation. In the case of cathode ray tube display, the time T to create one frame is T = Nt, and in order to obtain flicker-free images during real-time display, it is desirable to set the number of frames per second 1/T to about 30 frames/second. However, as mentioned above, when displaying two areas A and B alternately, compared to the case where only one of them is displayed, if other conditions are the same, the above time t is doubled, so the number of frames per second is 1. /T becomes 1/2, and the image quality inevitably deteriorates. In other words, the conventional dynamic
The focus method has the disadvantage that even if two focal regions are generated, the effect is significantly diminished.

The present invention has been made under the above circumstances, and an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of displaying multiple focal areas in real time using a dynamic focus method without reducing the number of frames per second. Our goal is to provide the following.

An illustrated embodiment of the present invention will be described below. In FIG. 2, numeral 10 is a synchronization section which generates synchronization pulses with a predetermined repetition period. Reference numeral 11 denotes a transmission delay circuit, which alternately transmits pulse signals with a phase difference corresponding to, for example, two focal areas A and B, each time one synchronization pulse is inputted, to a predetermined number of elements m.
(The figure shows the case where m=7). Reference numeral 12 denotes a transmitter, which includes switching circuits corresponding to the total number n of elements. Reference numeral 13 denotes an array type probe, which includes, for example, a plurality of n elements arranged linearly. Reference numeral 14 denotes a preamplifier section for echo signals, which is equipped with a switching circuit corresponding to all the elements (n pieces) and an amplifier corresponding to a predetermined number of elements (m pieces), and is equipped with a switching circuit for each of the m excited element groups. is configured to output an echo signal. The output signal of the preamplifier section 14 is sent to the amplification/detection section 18 via the reception delay circuit 15, buffer amplifier 16, and adder 17.
is input. Reference numeral 19 denotes an amplitude correction circuit, which is configured to compensate for sensitivity differences due to the depth (l) from the body surface to the measuring section. If necessary, the output signal of the amplitude correction circuit 19 may be guided to the preamplifier section 14 instead of the amplification/detection section 18. 2
0 is a control signal generating section which alternately generates control signals corresponding to the focal areas A and B each time a synchronization pulse is input. The above configuration may be the same as in the conventional device.

The first mixer 21 is configured to send out only one of the focal regions A and B of the output signal of the amplification/detection section 18 according to the output signal of the control signal generation circuit 20. First mixer 21
The output signals of are guided to a storage section 24 and a second mixer 25 via A/D converters 22 and 23, respectively. The second mixer 25 is an A/D converter 23
and mixes and synthesizes each output signal of the storage section 24,
The output signal is guided to a display unit 27 such as a CRT via a D/A converter 26.

Next, the operation of the apparatus configured as described above will be explained. The synchronization unit 10 sends synchronization pulse signals P ₁ , P ₂ ... as shown in FIG. Gate signals A ₁ and A ₂ are used as control signals corresponding to B, respectively.
......and B ₁ , ...... B ₂ ...... are generated. The transmission delay section 11 and the reception delay section 15 are activated by such a gate signal or focal region identification signal.
is controlled, ultrasonic pulses corresponding to focal areas A and B are sequentially transmitted to each selected element group in the probe 13, and echoes from the measuring section are received. FIG. 3 shows this received echo group. In the first mixer 21, as shown in the figure, for example, odd-numbered and even-numbered synchronization pulses P ₁ , P ₃ ...... and P ₂ , P ₄ ......
Corresponding to each, the effective gates A ₁ , A ₃ ......
...and B ₂ , B ₄ ...... are respectively set,
Of the input echo signals, an echo signal from the focal region A is sent out in response to an odd-numbered synchronization pulse, and an echo signal is sent out from the focal region B in response to an even-numbered synchronization pulse. and,
The A/D converters 22 and 23 output digitized echo signals A' ₁ , A' ₃ ...... and B' ₂ , corresponding to the focal areas A and B, as shown schematically in FIG. B' ₄ . The stored echo signal is read out from the storage section 24 in response to the next synchronization pulse, and this read signal and the signal directly output as a signal from the A/D converter 23 are sent to the second mixer 25. input, mixed, and synthesized. This is shown in the figure. In the figure, arrows indicate the mixing process. As shown in FIG. 3, the second mixer 25 outputs an echo signal A' 1 in the focal area A corresponding to the first synchronizing pulse P ₁ and an echo signal A' ₁ in the focal area B corresponding to the second synchronizing pulse P ₂ . An echo signal A' ₁ +B' ₂ which is a continuation of the echo signal B' ₂ is extracted in synchronization with the second synchronizing pulse P ₂ . Furthermore, the third and fourth...
Echo signals A′ ₃ +B′ ₂ , A′ ₃ +B′ ₄ ...... are sequentially extracted in synchronization with the synchronizing pulses P ₃ , P ₄ ......, respectively, and sent to the D/A converter 26. The signal is then guided to the display section 27 as a video signal.

According to the above configuration, the echo signals corresponding to the focal areas A and B are alternately extracted via the first mixer 21 according to the gate signal or the focal area identification signal from the control signal generator 20, and are stored. Since the output signals of the first mixer 21 and the storage section 24 are mixed and synthesized in the second mixing section 25, two focal points can be displayed on one sweep line on the display section 27. It is possible to display converted echoes. Therefore, it is possible to perform real-time display without reducing the number of frames per second as in the conventional dynamic focus method, and it is also possible to display high-quality images without blurring or flickering. Obtainable.

For ease of understanding, the case of two zones targeting the two focal areas A and B has been explained above, but for example, in the case of three zones, the transmission delay circuit 11, the reception delay circuit 15, the control The signal generating section 20, the first mixer 21, etc. are configured to correspond to the three focal areas A, B, and C, respectively, and are connected to the second storage section and between this and the first mixer. What is necessary is to provide an A/D converter or the like. In this case, as illustrated in FIG. 4, the effective gates (shown in the same figure) corresponding to the synchronizing pulses P ₁ , P ₂ ……, respectively, are A ₁ ,
B ₂ , C ₃ , A ₄ , B ₅ , C ₆ ......, and the echo signals shown schematically in the figure and in the second mixer are inputted as shown by the arrows, and the echo signals shown in the figure are input to the second mixer as shown in the arrows. A composite signal A′ ₁ +B′ ₂ +C′ ₃ , A′ ₄ +B′ ₂ +C′ ₃ , A′ ₄ +
B′ ₅ +C′ ₃ , A′ ₄ +B′ ₅ +C′ ₆ ...... are obtained. Otherwise, the operation is substantially the same as that described with reference to FIG. 3, except that the number of gate signals is different. When the number of zones is 4 or more, it can be applied in almost the same way as described above, but if the number of zones is too large, an image resulting from several previous synchronization pulses will be displayed on one scanning line, so The image quality will be poor, and in practical terms, it is thought that up to about 5 zones can be used.

In addition, although the above description has been made regarding the case of linear scanning, it can also be applied to real-time display in cases such as sector scanning in the case of the heart, radial scanning in the case of urinary organs, etc., depending on the diagnosis target. .

Furthermore, the transmitting section 12 and the preamplifier section 1
Instead of having a switching circuit and a predetermined number (m) of amplifiers each corresponding to the total number of elements (n) as in 4, for example, a switch circuit and a predetermined number (m) of both switching circuits and amplifiers may be provided. , the connection may be switched to each element using an appropriate analog switch. Further, the focal region identification signal may be directly obtained from the synchronization section 10 instead of the control signal generation section 20, for example.

It goes without saying that various other modifications and applications can be made within the scope of the gist of the present invention.

As described above, the present invention includes a first mixing section that sequentially sends echo signals corresponding to each focal region for each synchronization pulse according to an output signal from a control signal generation section; The device includes a storage unit that stores output signals, and a second mixing unit that mixes and synthesizes each output signal of the first mixing unit and the storage unit, and the second mixing unit that mixes and synthesizes the output signals of the first mixing unit and the storage unit, and Since a video signal consisting of a combination is extracted for each synchronization pulse, echo signals corresponding to a plurality of focal areas can be displayed simultaneously, although there is a slight time difference between them. Therefore, compared to a conventional device that displays these images sequentially, there is no reduction in the number of frames per second, making it possible to display images of better quality in real time.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the dynamic focus system, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 or a timing diagram for explaining the operation of the same example, and Figs. These are timing diagrams when the number of zones is different. 10...Synchronization section, 11, 15...Delay circuit, 1
3...Array type probe, 20...Control signal generation section, 21...First mixing section, 24...Storage section, 2
5...Second mixing section, 27...Display section.

Claims (1)

[Claims] 1. An array type probe having a plurality of ultrasonic transducers, a synchronization section that generates a synchronization pulse with a predetermined repetition period, and a synchronization section that corresponds to a plurality of focal areas of the probe each time the synchronization pulse is input. and a delay circuit capable of selectively and variably setting the focal region in accordance with the control signal, the control signal generating section being capable of generating a control signal for each of the focal regions in response to the control signal. A first transmitter that sequentially sends out corresponding echo signals for each of the synchronization pulses.
a mixing section, a storage section that stores the output signal of the first mixing section, and a second mixing section that mixes and synthesizes the output signal of the first mixing section and the storage contents of the storage section. An ultrasonic diagnostic apparatus characterized in that a video signal consisting of different combinations of echo signals corresponding to each of the focal areas is extracted for each of the synchronization pulses.