JPS59118143A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus used, for example, in medical diagnosis.

[Technical background of the invention]

One type of ultrasound diagnostic equipment is a linear ultrasound diagnostic equipment that uses an electronic scanning type ultrasound probe. This device excites a desired plurality of play-type ultrasonic probes in which a large number of ultrasonic transducers are arranged side by side, for example, a predetermined number of adjacent ultrasonic transducers, as a group. The reflected wave 'f' from the living body is received by the above group of ultrasonic transducers used for ultrasonic excitation, and this corresponds to the ultrasonic beam emission position on the ultrasonic probe. Then, a new group of ultrasonic transducers, in which the above-mentioned group of ultrasonic transducers are shifted one pitch next to each other, is excited to generate one more ultrasonic transducer than the previous one. Sequentially repeating the operations of forming a spatially shifted ultrasound beam, receiving the reflected wave from the living body by this ultrasound beam, and displaying it at the display screen position corresponding to the ultrasound beam emission position. A tomographic image corresponding to a certain width of the living body is displayed.

In such an ultrasound beam scanning method in which the ultrasound beam is sequentially translated in parallel by the pitch of the ultrasound transducer, the number of tomographic images obtained per unit time is basically the same as the number of tomographic images obtained per unit time. is limited by the depth of the body and the speed of sound in the living body.

That is, the depth of the living body to be displayed is L1, the sound velocity in the living body is v[C
rn/sec], one ultrasonic beam (i.e.
The time t for capturing reflected waves for one scanning line on the display section is t 1 = 2L / V C5ee), and the total number of ultrasonic transducers in the ultrasonic probe is N1 The number of ultrasonic transducers constituting the above group Let M be the number of scanning lines required to obtain an image of one cross section of the living body.

Therefore, the number of tomographic images obtained per unit time, that is, the number of frames FN, is, for example, v = 1.53 x 10 (crn/5
ee), L=20[>:].

If N=128 and M=24, FN=36 [sheets/s
ec).

By the way, in order to increase the resolution of tomographic images, when transmitting a single ultrasound beam, it is necessary to focus the ultrasound beam on a certain point in the living body by giving each ultrasound transducer a desired delay time. It is. In this case, the ultrasound beam becomes a narrow beam at the focal point, improving resolution, but
The ultrasonic beam spreads outside the focal point, resulting in a decrease in resolution. As a means of improving the resolution over a wide area of a tomographic image, the ultrasound beam is focused at a certain depth inside the living body and the reflected waves are detected only near the focal point, and then the ultrasound beam is focused at a different depth. , a method is used in which reflected waves near the prefectural east point are detected and the signals of these detected reflected waves are combined and displayed, and this method 1d is generally called combination focus.

Problems with combination focus: When the number of combination stages is increased, the number of frames per unit time decreases, and therefore the time required to obtain an image for one frame increases.This is why real-time focusing is extremely important for ultrasound diagnostic equipment. It is a loss of sexuality.

For example, in the above example, if two-stage combination focus is used, the number of frames will be 18 frames/Bec.

As a way to avoid such a decrease in the number of frames per unit time, it is possible to use two or more groups of ultrasonic transducers separated from each other in a large number of ultrasonic transducers for excitation and reception in parallel. This is possible, but in this case, since the ultrasound waves reflected from the living body spread in all directions, interference between different ultrasound transducer groups would occur, resulting in an unclear tomographic image, making it impractical. Problems remain.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is possible to multiply the number of frames per unit time, and as a result, even when combination focus is used, real-time performance is not impaired, and the image quality is excellent. The purpose is to provide a sonic diagnostic device.

[Summary of the invention]

That is, in order to achieve the above object, the present invention uses an array-type ultrasonic probe in which a large number of ultrasonic transducers are separated, and generates a desired plurality of ultrasonic vibrations of the ultrasonic probe in the first order. By selecting a group of children and applying ultrasonic excitation to this group using the output of the transmitting system, ultrasonic beams are generated with sequentially shifted positions, and the reflected waves are received and sent to the receiving processing system, and this received signal is In an ultrasonic diagnostic apparatus that obtains an ultrasonic video signal and displays an ultrasonic tomographic image using this video signal, a plurality of groups of ultrasonic transducers are positioned at different positions relative to the ultrasonic liquid depth probe. Provide a means for selecting, and
The transmission system and the reception processing system are respectively provided corresponding to each of the groups, and each reception processing system is provided with a filter capable of variable control of the passing frequency region of the reception signal, and the output of each transmission system is provided. The generation timing is controlled to be different, and each filter in the reception processing system corresponding to each of these transmission systems is adjusted to the timing of the corresponding transmission system so that a predetermined change characteristic from a predetermined high frequency range to a low frequency range is obtained. The configuration includes a control means for variable control of the passing frequency region, and the control means causes the output generation timing of each transmission system to be shifted and generated, so that the selection means selects and outputs the output of each group. The sonic transducer groups are excited at different timings, and ultrasonic beams with different timings and the same number as the selected groups are generated from the corresponding positions of each group, and ultrasonic beams reflected from the living body are generated. Taking advantage of the fact that the wave spectrum becomes dominated by low-frequency components as the reflection depth becomes deeper, the pass frequency region of the filter that filters the received signal of the reflected wave received by each group is determined by the system to which the filter belongs. The filter is controlled to change the depth position of the reflected wave in the ultrasonic beam generated by the ultrasonic transducer group to suppress the interference of the reflected wave from other ultrasonic beams. Even if multiple ultrasound beams are mixed together, interference from other ultrasound beams can be avoided, thereby increasing the number of frames obtained per unit time, and combining Focus can be implemented without compromising real-time performance.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

First, as a method to avoid the range of the number of frames obtained per unit time, two groups of ultrasonic transducers to be excited in the ultrasonic probe are set up, and ultrasonic beams are generated in parallel, respectively. It was explained that it is not practical to receive the reflected waves due to interference between the ultrasonic transducer groups.

The present invention focuses on the fact that the spectrum of ultrasound reflected waves from a living body changes depending on the depth of the living body due to the frequency dependence of ultrasound attenuation in the living body, and uses two different groups of ultrasound transducers. By selecting the excitation timing and connecting a filter with variable characteristics to the receiving circuit for each ultrasonic transducer group and controlling the filter characteristics, mutual interference between the ultrasonic transducer groups is suppressed, and multiple ultrasonic beams are This is to enable scanning and to increase the number of frames per unit time.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the apparatus of the present invention. In the figure, 1 is a control circuit that controls the entire system, and 2 and 3 are a group of transmitting circuits that are separately controlled by this control circuit 1 and generate ultrasonic transmission outputs with different timings. 4 is an array-type ultrasonic probe for transmitting and receiving ultrasonic waves configured by arranging a plurality of ultrasonic transducers in parallel; Two groups of ultrasonic transducers are selected, each output from the transmitting circuit groups 2 and 3 corresponding to each group is applied to a corresponding transducer of the selected ultrasonic transducers, and each of the transducers is The function is to provide the received output from the receiver to a corresponding receiving circuit, which will be described later.

Reference numerals 6 and 7 each designate a receiving circuit, which performs delay setting of the received signal under the control of the control circuit 1, and also receives signals from the corresponding ultrasonic transducer of the ultrasonic transducer group selected by the selection circuit 5. The signals are delayed so that the signals from the same depth position match on the time axis, and then are combined, amplified, and output.

Reference numeral 8.9 denotes a filter provided corresponding to each of the receiving circuits 6 and 7, whose characteristics are sequentially changed over time under the control of the control circuit 1. In response to changes in attenuation rate depending on the frequency band, the ultrasonic beam is made less likely to interfere with ultrasonic reflected waves of other ultrasonic beams.
Extract the desired ultrasound wave signal.

1θ and 11 are signal processing circuits provided corresponding to the filters 8 and 9, respectively, and outputs from the corresponding filters 8 and 9 are used to display tomographic images under the control of the control circuit 1. processed into a video signal and output. 1
A display section 2 operates under the control of the control circuit 1 and displays the video signals output from the signal processing circuits 10 and 11 as images.

This device has two main parts of the transmitting/receiving circuit system, each of which is driven by a control circuit 1 at different timings, and the ultrasonic probe 4 transmits two different ultrasound beams at different timings. Then, by receiving the reflected waves and applying a filter K whose characteristics change over time, the interference of the reflected waves of each ultrasound beam is suppressed, and as a result, the two ultrasound beams are transmitted almost at the same time. If there is a slight difference in transmission time, each reflected wave can be detected separately without mutual interference. This allows a large amount of ultrasonic information to be obtained and avoids a reduction in the number of frames even in the combination focus method, allowing real-time It is possible to maintain not only the image quality but also the image quality.

That is, in this device, the control circuit 1 controls the selection circuit 5 to select two different ultrasonic transducer groups of the ultrasound probe 4, and then controls the two transmission circuit groups 2 and 3. A transmission command is given from circuit 1 to generate ultrasonic excitation/gurus. Each of the transmitting circuit groups 2 and 3 has the same number of transmitting circuits as the number of ultrasonic transducers in a group to be excited, and each transmitting circuit receives the two-press ultrasonic wave selected by the selecting circuit 5 via the selecting circuit 5. The transmitting circuits are connected to corresponding ultrasonic transducers in a group of acoustic transducers, and the output of each transmitter circuit is input to the corresponding ultrasonic transducer to excite the ultrasonic transducer.

In this device, transmitting circuit group 2 and transmitting circuit group 3 are driven with slightly different times, and each transmitting circuit group 2 is driven at a slightly different time.
, 3, when each ultrasonic transducer is excited by the output of each transmitting circuit, the ultrasonic waves generated from each ultrasonic transducer interfere and propagate as a beam in a desired direction. A delay is applied to the output of each transmitting circuit so that the ultrasonic beam is focused at a depth of .

As a result, the output from the transmitting circuit #2 is first inputted to the selected group of ultrasonic transducers of the ultrasonic probe 4 via the selection circuit 5, and the group of ultrasonic transducers is excited. An ultrasonic beam UBI focused in the set direction υ and at the set depth from the center position of the group of ultrasonic transducers is transmitted.

Then, the reflected waves of the ultrasonic beam are detected by the group of ultrasonic transducers, converted into electrical signals, and sent to the receiving circuit 6.
will be sent to.

On the other hand, the transmission circuit group 3 of the other system is driven with a timing slightly delayed from the transmission of this ultrasound beam UBI, and its output is sent to the selected other group of ultrasound probes 4 via the selection circuit 5. input to the ultrasonic transducer. As a result, the other group of ultrasonic transducers is excited and an ultrasonic beam UB;zy)x is transmitted from the center position of the other group of ultrasonic transducers in a set direction and at a set depth. It turns out. Ultrasonic beam UB1. The transmission direction and focus point of UB2 are controlled by control circuit 1.

The reflected wave of the ultrasonic beam UB2 is detected by the other group of ultrasonic transducers, converted into an electrical signal, and sent to the receiving circuit 7.

When the signals are sent in this way, the receiving circuits 6 and 7 give each ultrasonic transducer a delay time corresponding to the excitation timing of the ultrasonic transducer for each output of the ultrasonic transducer. After aligning the signals from the same time position, that is, the signals from the same depth, they are combined and amplified, and the output of the receiving circuit 6 is applied to the film 8, and the output of the receiving circuit 7 is applied to the filter 9.

Each of the filters 8 and 9 has a pass band within a predetermined frequency range for a period of time after the ultrasonic wave is transmitted from the circuit of the system to which it belongs until the next ultrasonic wave is transmitted from the system. On the other hand, the reflected waves of the ultrasonic beams have different frequency bands depending on the depth of reflection, and the ultrasonic beams UBI and UB2 are Since the transmission timings are slightly different, interference with the other ultrasonic beam can be avoided by passing each ultrasonic beam through a filter.

Therefore, signals due to the reflected waves of the ultrasonic beams of each thread are extracted from the filters 8 and 9.
The signal is input to a signal processing circuit 10.11 located at a subsequent stage.

Here, the signal extracted by the filter is added with a synchronization signal etc. to become a video signal, and is input to the display unit 12, which displays the ultrasound beam transmission position and transmission direction of the ultrasound probe 4. An image of the reflected wave of the ultrasonic beam will be displayed at the display screen position I2.

Here, the reason why the filters 8 and 9 can suppress the interference of the other ultrasonic beam will be explained in a little more detail.

FIG. 2 shows the excitation timings of two different ultrasonic transducer groups in the ultrasonic probe 4 selected by the selection circuit 5 and the filters with variable pass frequency ranges connected to the receiving circuits of each ultrasonic transducer group. 8.9 shows the temporal change in the pass frequency region.

Of the two selected groups, one of the ultrasonic transducer groups is excited at time TI, and 21 hours later, approximately corresponding to the time for the ultrasonic waves generated thereby to travel back and forth to the desired biological depth.
That is, at time T1+ΔT, the selection circuit 5 selects and switches the group of ultrasonic transducers selected by the selection circuit 5 to a group of ultrasonic transducers at a new position shifted by one pitch to the adjacent group 9, and at the same time, the selection circuit 5 switches the ultrasonic transducers of the group selected by the selection circuit 5 to a group of ultrasonic transducers at a new position shifted by one pitch 9. The ultrasonic transducer of T1+
Excite at time ΔT. , the other group of ultrasonic transducers is excited at time T2, which is approximately halfway between time TI and time T1+ΔT, and then a new group of ultrasonic transducers shifted by one pitch is excited again at T2+ΔT.

By repeating this process alternately, tomographic images are obtained while sequentially shifting the position of the ultrasound beam by one pitch of the ultrasound transducer.

The pass frequency mantissa region of the filter for one group of ultrasonic transducers is controlled such that the center frequency is set high at time TI and becomes lower with time, as shown by 1 in FIG. Further, as shown in the filter characteristic H for the other ultrasonic transducer group, the center frequency is high at time T2 and controlled so as to become lower with time, similar to I above.

This type of filter characteristic corresponds to the fact that the spectrum of ultrasonic waves in a living body gradually moves to a lower range due to installation in a living body, and is designed to match the actual conditions inside a living body. This characteristic is determined in advance.

In this way, the generation timings of the two ultrasound beams are staggered, so when the other ultrasound transducer group is receiving ultrasound reflected waves from a shallow position, one ultrasonic transducer group is receiving Even if the reflected wave of the transmitted ultrasound comes in and is received, this reflected wave is from a deep reflection position, so the frequency spectrum belongs to the reduced range and the frequency range is different from the other one. Since the component that falls within the pass frequency range of the filter given to the reflected wave of the ultrasonic transducer group is extremely weak, the interference effect is significantly reduced.

Furthermore, when one of the ultrasonic transducer groups is detecting reflected waves from deep inside, the influence of the reflected waves of the ultrasonic waves emitted from the other ultrasonic transducer group is that the spectrum of this reflected wave is Since it is mainly a high frequency component, this component is blocked by the filter for one of the ultrasonic transducer groups, and the reflected wave from the shallow part of the body is transmitted to the ultrasonic transducer group at a different ultrasound beam position. Since the light enters at a large angle of incidence, the interference effect is reduced due to two effects: the reception sensitivity is originally low.

As described above, by controlling the excitation timing of the two ultrasonic transducer groups and the filter characteristics for each ultrasonic transducer group, the interference effect between the two ultrasonic transducer groups can be reduced. Since the ultrasound beam can scan different areas with a slight temporal shift and mix them, each reflected wave can be detected separately, reducing the time required to obtain one frame of an ultrasound tomographic image. Therefore, it is possible to increase the total number of frames per unit time to about twice that of the conventional method, and even when combination focus is used, real-time performance can be maintained, and image quality is not impaired.

FIG. 3 shows the excitation timing and reception timing of the ultrasonic transducer group and their filter characteristics in an embodiment in which this method is applied to a two-stage combination focus.

In the combination focus, (c) the number of ultrasonic transducers and the focus of the one ultrasonic transducer group and the other ultrasonic transducer group are set to different desired values.

When the focus of one of the ultrasonic transducer groups is set to a deep part, the part of the ultrasonic reflected waves for this transducer group corresponding to the deep part, that is, from time Tl' to T1+
Ultrasonic reflected waves up to ΔT are received through filter characteristic 1. Still, the focus of the ultrasonic beam for the other ultrasonic transducer group is set to a shallow part, and the focus of the ultrasonic beam for this ultrasonic transducer group is at a short distance, that is, at time T2.
Ultrasonic reflected waves up to T2' are received through the filter characteristic 11.

By sequentially displaying and combining these two received signals, a tomographic image can be displayed with twice the number of frames as in normal combination focus.

In addition, in FIG. 3, T2 and T1' are shifted because T2
This is to prevent leakage of excitation pulses from affecting the received signal for the one ultrasonic transducer group.

In order for the composite screen to cover the entire area without gaps, it is necessary to set the time from Tl to T2, / so that the time from T2 to T2' matches.

As described above, since the time required to obtain an image for one frame is shortened, it becomes possible to increase the number of frames per unit time of the linear electronic scanning ultrasonic diagnostic apparatus. This is especially effective when real-time performance is an issue, such as in multi-stage combination focusing.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof. For example, in the above embodiments, two ultrasonic beams are used. Although the case where tomographic images are obtained has been shown, the number of these may be three or more, and in this case, the number of transmitting/receiving circuit systems may be increased in accordance with the number of ultrasound beams.

〔Effect of the invention〕

As described in detail above, the present invention uses an array type ultrasonic probe in which a large number of ultrasonic transducers are arranged in parallel, and sequentially selects a desired plurality of ultrasonic transducers of the ultrasonic probe as a group. death,
By applying ultrasonic excitation to this group using the output of the transmitting system, ultrasonic beams are generated by sequentially shifting their positions, and the reflected waves are received and sent to the reception processing system. In an ultrasound diagnostic apparatus that obtains a video signal and displays an ultrasound tomographic image using the video signal, means is provided for selecting a plurality of groups of ultrasound transducers positioned at different positions with respect to the ultrasound probe, and , the transmission system and the reception processing system are respectively provided corresponding to each of the groups, and each reception processing system is provided with a filter capable of variable control of the passing frequency region of the reception signal, and each of the transmission systems The timing of output generation is controlled to be different, and each filter in the reception processing system corresponding to each of these transmission systems is controlled to have a predetermined change characteristic from a predetermined high frequency range to a low frequency range in accordance with the timing of the corresponding transmission system. The structure includes a control means for controlling the passing frequency region variable ft1lJ so that the output generation timing of each transmission system is shifted and generated by the control means, and the output is selected and set by the selection means. The ultrasound transducers in each group are excited with different timings, and multiple ultrasound beams with different timing and the same number of groups as selected are generated from the corresponding positions of each group, and reflected from the living body. The spectrum of the ultrasonic reflected wave becomes deeper as the reflection depth increases.
Taking advantage of the fact that low-frequency components are the main component, the passing frequency region of a filter that filters the received signal of the reflected wave received by each group is used to filter the ultrasonic beam generated by the ultrasonic transducer group of the system to which the filter belongs. The filter is controlled to vary according to the depth position of the reflected waves in order to suppress the interference of the reflected waves from other ultrasound beams. However, since interference by other ultrasound beams can be avoided, the number of frames obtained per unit time can be increased without degrading the image quality. Therefore, combination focusing can be performed. Since the time required to obtain an image for one frame can be greatly shortened compared to the conventional method, it is possible to provide an ultrasonic diagnostic apparatus that can be used without impairing real-time performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining the principle of operation of the device of the present invention, and FIG. 3 is a diagram for explaining the principle of operation when applied to combination focus. This is a diagram that provides a detailed explanation. 1... Control circuit, 2, 3... Transmission circuit group, 4...
Ultrasonic probe, 5... Selection circuit, 6, 7... Receiving circuit, 8.9... Filter, 10.11... Signal processing circuit, 12... Display section.

Claims (1)

[Claims] Using an array-type ultrasonic probe in which a large number of ultrasonic transducers are arranged in parallel, a desired plurality of ultrasonic transducers of this ultrasonic probe are sequentially selected as a group, and the output of the transmitting system is selected for this group. In order to perform ultrasonic excitation, an ultrasonic beam is generated by sequentially shifting the position, and the reflected wave is received and sent to the reception processing system, and an ultrasonic video signal is obtained from this received signal. In an ultrasonic diagnostic apparatus that displays ultrasonic slag, means is provided for selecting a plurality of groups of ultrasonic transducers positioned at different positions with respect to the ultrasonic probe, and the A transmitting system and a receiving processing system are respectively provided, and each receiving processing system is provided with a filter capable of variable control of the passing frequency region of the received signal, and the output timing of each of the transmitting threads is controlled to be different. In addition, each filter in the reception processing system corresponding to each of these transmission systems is adjusted to the timing of the corresponding transmission system, and the passage tube V number region is adjusted so that a desired change characteristic from the high frequency range to the low frequency range is obtained. An ultrasonic diagnostic apparatus characterized by being provided with a control means that performs variable control.