JPS632615B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus that transmits and receives ultrasound beams to obtain tomographic information of a specimen. This relates to an ultrasonic diagnostic device.

2. Description of the Related Art Ultrasonic diagnostic apparatuses that transmit ultrasound signals to living tissue and receive signals reflected at tomographic positions of the living tissue to obtain tomographic images of the living tissue are generally known.

In contrast, the applicant of this application has
Patent Application No. 11027 of 1981 (Japanese Patent Application Laid-Open No. 103837) discloses a technology for simultaneously transmitting and receiving two ultrasonic beams with different frequencies, discriminating each beam, and simultaneously obtaining tomographic information viewed from different positions. ) is proposed as.

That is, according to this technique, for example, the details of a specific organ within a biological tissue can be observed from two directions simultaneously, and if these tomographic information are displayed in combination, compared to conventionally known techniques that observe from a single direction, The effect of being able to display accurate tomographic information can be achieved.

However, differences in the frequencies of ultrasound beams propagated through biological tissue generally result in differences in attenuation rates, differences in beam focusing characteristics, differences in reflectivity at tomographic locations, and differences in beam duration. It has been known.

For this reason, when ultrasound beams with different frequencies are used, the quality of the images obtained is different.

For this reason, the previously proposed technology can certainly obtain tomographic images with better resolution compared to the technology that obtains tomographic information using a single ultrasound beam, but on the other hand, it uses a high frequency. The obtained tomographic image loses its image as the distance from the transmission position increases, and the tomographic image obtained using the other low frequency has the disadvantage that it becomes a rough image with poor resolution.

Therefore, a first object of the present invention is to provide a method for obtaining tomographic information extracted from a predetermined probe position under conditions consistent with the conditions for obtaining tomographic information extracted from other probe positions. The second objective is to obtain an ultrasonic diagnostic device that can improve the resolution compared to the resolution of existing proposals, and the third objective is to obtain Tissue Characterization
The objective is to obtain an ultrasonic diagnostic device that is capable of characterization.

In order to achieve the above object, in the present invention,
For one ultrasound probe, time-sharing
Ultrasonic beams with different properties are transmitted, and the ultrasound beams with different properties are transmitted between the ultrasound probes at the same time. Therefore, since a given probe can transmit the same ultrasonic beam as other probes at different times, biological tissues can be measured under the same conditions. Furthermore, since ultrasonic beams with different properties can be transmitted and received from one probe, different measurement methods can be employed within the scanning area of the ultrasonic beam, and the above-mentioned tissue characterization can also be performed. Furthermore, resolution can be significantly improved by combining multiple types of tomographic information obtained by one probe between each probe.

The present invention will be explained in detail below based on the drawings.

FIG. 1 is a diagram illustrating the principle of an embodiment of the present invention. In the figure, 1 is a specimen, 2 is a probe, 3 is a control device, and 4 is a display device.

In this embodiment, an ultrasonic diagnostic apparatus using two probes 2a and 2b will be described, but the number of probes is not limited to two and may be any number. Further, although an ultrasonic diagnostic apparatus employing a so-called sector scan method in which one probe scans the specimen 1 in a fan shape to obtain tomographic information will be described, it may also employ a linear scan method.

Explain the operation.

The probe section 2 has probes 2a, 2b, an arm 2d, and an angle detector 2c. The arms 2d are supported by means that allows the angle between the arms to be varied so that each probe 2b can come into contact with any position on the specimen 1. Each of the angle detectors 2c detects the opening angle of the arm 2d, and controls a signal that enables the relative position of the probe 2b between the probes 2a and the direction of the scanning center line of the ultrasound beam to be determined. Supply to the device.

At a predetermined time t1, the probes 2a and 2b are driven by the control device using signals having different properties. For example, probe 2a receives a signal with a center frequency of 2.5 MHz, and at the same time, probe 2b receives a signal with a center frequency of 3.5 MHz.
Each is driven by a Hz signal. This allows probe 2
a transmits an ultrasonic beam, receives a reflected signal obtained from the same direction within a predetermined period, and supplies it to the control device 3 as an electrical signal. Similarly, the probe 2b also transmits an ultrasonic beam in a predetermined direction and supplies the received signal to the control device 3.

Thereafter, the control device 3 sequentially changes the transmission direction of the ultrasonic beam at predetermined time intervals, and obtains a received signal in the corresponding direction. When both the probes 2a and 2b have respectively transmitted ultrasonic beams to all scanning areas and have received reflected signals, the control device 3 controls the probes 2a and 2b to
b is driven with a signal of a different nature than before. for example,
The probe 2a is driven by a signal having a center frequency of 3.5MHz, and the probe 2b is driven by a signal having a center frequency of 2.5MHz.

Similarly, each time the scanning areas 2sa and 2sb are scanned, one probe sends out an ultrasonic beam with a different property.

On the other hand, the control device 3 identifies the relative position of the probe based on the signal from the angle detector 2c mentioned above,
The received signals obtained for each scan are transmitted to the scanning area 2sa,
2sb is displayed on the display screen 4a of the display device 4.

Here, for example, if the specimen 1 is a heart, a specimen in which tissue exists in the ventricular septum 1a near the body surface and in the ventricular rear wall 1b at the farthest position from the transmission position will be described as an example. An image 1a' and an image 1b' are obtained in one unit frame of the display device 4 created from the received signal obtained when this specimen is scanned with an ultrasonic beam having a frequency of 2.5 MHz. However, only the image 1a' is obtained in the unit image frame obtained when scanning with an ultrasonic beam having a frequency of 3.5 MHz.

Therefore, as described above, when one probe alternately transmits ultrasound beams of different quality and creates an image frame from the obtained signals, the image 1b' is displayed intermittently. Therefore, if the display device displays "60" unit image frames per second, "30" unit image frames will display the tissue 1b measured from at least one direction 30 times. Moreover, the image 1b' can be displayed 30 times at different timings depending on the signals obtained from other probes, and the image 1b' can be observed on the display screen 4a without flickering as if it were constantly displayed.

Note that another method for processing the intermittent image 1b' is to use a normal refresh memory. This is suitable for displaying the posterior wall of the ventricle, where the movement is not as intense as that of the mitral valve, and image 1b′, which cannot be obtained with the 3.5MHz scan, is continuously displayed as the image obtained with the previous 2.5MHz scan. If memory synthesis is performed as much as possible, and this memory is used as a refresh memory for display, reading and displaying at a rate of, for example, 60 fields/sec, display can be achieved without flickering.

Furthermore, since the image 1a' is always extracted regardless of the signal obtained from any probe, it can be clear. Therefore, it is suitable for displaying objects that move rapidly, such as the mitral valve.

From the above results, images of higher quality can be obtained from each of the probes 2a and 2b. Moreover, when they are displayed in a composite manner, the image can be further improved by the compound effect.

FIG. 2 is a block diagram of essential parts of an embodiment of the present invention, and FIG. 3 is a diagram showing frequency characteristics.

Further, FIG. 2 is a block diagram embodying the part of the control device 3 shown in FIG. 1, particularly for sending and receiving signals to and from the probes 2a and 2b.

Components in the figure that are the same as those in FIG. 1 are designated by the same numbers.

Further, the probes 2a and 2b are each composed of a plurality of transducers 2a1 to 2an and 2b1 to 2bn. In addition, in this example, the transmission direction of the ultrasonic beam transmitted by the probe,
and to define the direction of the received signal, a so-called phased array technique is used.

Drivers 306a, b, switch 307a,
b, filter 308a, b, filter 309a,
b, amplifier 300a, b, switch 301a,
b, filter 302a, b, filter 303a,
b, delay elements (delay elements) 304a, b are the above-mentioned transducers 2a1 to 2an and 2a, respectively.
2n pieces of numbers b1 to 2bn are provided,
For convenience of explanation, transducer 2a1 is shown in the figure.
Only those provided corresponding to transducer 2b1 and transducer 2b1 are shown.

Explain the operation.

The phase control section 312 has a function of controlling the drive of the transducer and the reproduction phase of the received data.

That is, the phase control unit 312 provides the drive timing generation circuits 305a and 305b with timing information for driving the transducers of the respective probes, and the delay control units 310a and 310b with the received signals in the receiving direction. The information for changing the delay amount by a predetermined period of time is supplied. With this information,
The drive timing generation circuit 305a controls each driver 3 so that the ultrasonic beam transmitted from each transducer of each probe is focused at a predetermined position.
06a, the drive timing circuit 305b drives each driver 306b, respectively.

At this time, drive timing circuits 305a, 3
05b controls each driver so that the distance between the focusing position and the transmission position of each probe 2a, 2b is different between the probes 2a, 2b, based on information from the phase control unit 312. to start.

Each of the drivers 306a,..., 306b,... is activated by a corresponding activation signal supplied from the drive timing generation circuits 305a, 305b, and each generates a signal having a wideband signal component, for example, an impulse signal, at different timings. Occur.

On the other hand, the switching control circuit 311 allows each of the probes 2a and 2b to simultaneously generate the aforementioned signals with different properties, and allows the same probe to generate signals with different properties in a time-sharing manner. used for.

That is, filters 308a and b and filter 30
9a and 9b each have the function of filtering different frequency bands. Also, switches 307a, 307b
According to the output signal of this switching control circuit 311,
The drivers 306a and 306b are connected to the filter 30.
8a and filter 309b, and filter 309a
and has a function of connecting to the filter 308b. Therefore, when the switching control section 311 outputs a predetermined signal at time _t1 , the signals provided from each of the drivers 306a and 306b are filtered by the filters 308a and 309b, respectively, as described above. The frequency components of the filtered signal components are therefore distributed in different bands.

Further, the switches 307a and 307b connect the respective drivers 306a and 306b to the filter 309a and the filter 308b, respectively, by a signal given from the switching control section 311 at time _t2 .
As a result, the signal input from _the driver after time _t2 is transmitted to _the probe 2a,
2b to a signal different from that applied to each of the filters.

The switching control unit 311 synchronously switches the switches 307a and 307b every time one scan of the area is completed.

The probes 2a and 2b transmit ultrasonic beams by signals supplied from the filter 308a or 309a and the filter 309b or 308b. FIG. 3 shows the frequency characteristics of the transmitted ultrasound beam. In the figure, solid lines CS and CR indicate the transducers 2a1 to 2an and 2b that constitute the probe, respectively.
Transmission filtering characteristics and reception filtering characteristics of 1 to 2bn,
Further, dashed lines CF1 and CF2 indicate filters 308, respectively.
a, 308b and filter characteristics of filters 309a, 309b.

That is, at time _t1 , transducers 2a1-2
The signal band of the ultrasound beam transmitted from an is
The band F1 is indicated by the shaded area, and the signal band of the ultrasonic beams transmitted from the transducers 2b1 to 2bn is the band F2 shown by the shaded area, which can be distinguished. After time _t2 , on the contrary, transducers 2a1 to 2an transmit ultrasound beams in band F2, and transducers 2b1 to 2bn transmit ultrasound beams in band F1.

A single impulse-like ultrasound beam is applied to sample 1.
After transmitting the signal, the received signal is extracted from each transducer for a predetermined period of time.

Each transducer 2a1~2an, 2b1~
The received signals extracted from 2bn are each input to a corresponding amplifier (amplifier).

For example, the received signal of the transducer 2a1 is inputted to the amplifier 300a, and the received signal of the transducer 2b1 is inputted to the amplifier 300b.

The amplifiers 300a and 300b amplify the received signals at a predetermined amplification rate, and are further controlled so that the amplification rate increases as time passes.

Now consider the frequency components of the received signal.

FIG. 4 shows the frequency components of the received signal.

That is, as explained with reference to FIG. 2, the probes 2a and 2b each transmit an ultrasonic beam having a band indicated by hatching in FIG. 3.

On the other hand, the reception filtering characteristic of each transducer is shown by a curve CR.

For this reason, even if the frequency bands of the ultrasound beams transmitted from each probe are different, one probe can transmit a frequency that includes both bands F1 and F2 (part of F2) shown by the grid. Component ultrasonic signals are output.

In this embodiment, in order to distinguish this, filters 302a, b and 303a, b having the same characteristics CF3, CF4 as the filters 308a, b and 309a, b described above in FIG. 2 are provided. Similarly to the filter on the transmitting side, the switch 301
A and 301b are provided, and the switching timing signals supplied by the switching control unit 311 to the switches 307a and 307b are supplied to the switches 301a and 301b, whereby each filter is alternately switched. For example, regarding the transducer 2a1, at the above-mentioned time _t1 , the ultrasonic beam of the band F1 is transmitted, and at this time the switch 3
01a connects the amplifier 300a to a filter 302a having filtering characteristics CF3. At the same time, since the ultrasonic beam of band F2 is being transmitted from transducer 2b1, switch 301b connects filter 303b having filtering characteristic CF4 to amplifier 300b.

At time _t2 , which is a predetermined time after time _t1 , the switching control section 311 switches the switches 307a and 307a.
Since a switching signal is issued at 07b, switches 301a and 301b are also switched at the same time.

Therefore, at time _t2 , the amplifier 300a is 303
a, the amplifier 300b is connected to the switch 30 to 302b.
1a and 301b.

The signal in the region F1 shown in the grid in FIG. 4 extracted by each filter on the receiving side is supplied to a delay circuit 304a, and the signal in the region F2' is supplied to a delay circuit 304b. Delay circuit 30
4a and 304b each have a delay control circuit 310.
A, 310b provides the time information to be delayed.

The signal delayed by the delay circuit 304a is added to the filtered and delayed signal extracted from other transducers belonging to the probe 2a at the connection point a.

That is, in the delay circuit, the amount of delay of the signals obtained from each transducer is controlled by the control section 310a so that the signals reflected at the same point on the specimen 1 are simultaneously outputted to this point a.

Further, signals extracted from the transducer belonging to the probe 2b are also added at point b in the same manner.

At this time, it is preferable that the amount of delay given to the delay circuit 304b and the amount of delay given to the delay circuit 304a be optimally selected depending on the frequency.

The signal lines obtained from each of the probes 2a and 2b obtained as described above, the above-mentioned angle detection signal line, and the switching control signal line from the switching control section 311 are connected to the display control section 313, respectively.

The display control unit 313 has multiple screen memories. One of this screen memory is, for example, 2.5MHz
It is used to store the received signal obtained when scanning areas 2sa and 2sb, and the other one is 3.5MHz.
is used to store the received signal obtained by scanning the areas 2sa and 2sb, and the other one is used to store the received signal obtained by scanning the areas 2sa and 2sb.

These received signals are binarized or analog-to-digital converted and stored by a calculation device (not shown) at a position corresponding to the time and angle detection signals. The display section 4 (shown in FIG. 1) has a display screen corresponding to the memory, and sequentially reads and displays data at addresses corresponding to display positions on the screen of the memory.

FIG. 5 is a block diagram of a second embodiment of the invention. In the figure, blocks having the same properties as the blocks used in FIGS. 1 to 4 are given the same reference numerals. In the case of the embodiment shown in the figure, the probes 2a,
2b is different from that shown in FIG. The basic configuration of this probe is shown in FIG.

In the figure, 20 is a fluid liquid such as water or oil, 21 to 24
is a transducer, 21t to 24t are drive terminals, G is a ground terminal, 25 is a probe fixing jig,
26 is a shaft, 27 is a motor, 28 is an outer casing, and 29 is a contact surface.

A rotating shaft of the motor 27 is connected to the shaft 26.

Further, the shaft 26 fixes a fixing jig 25, and the transducers 21 to 24 are further fixed to the jig 25.

Further, the transducer 23 facing the transducer 21 has the same resonant frequency as the transducer 21, and the transducer 22 facing the transducer 24 has the same resonance frequency as the transducer 21.
The transducers are piezoelectric elements having the same resonant frequency and different convergence positions of the ultrasonic beams, and adjacent transducers are arranged so as to be piezoelectric elements having different resonant frequencies.

When measuring a specimen, the contact surface 29 is pressed against the specimen.

Next, a control signal for rotating the motor 27 is supplied to the motor from a control device (not shown). As the motor rotates, a rotation angle detection mechanism 27a (not shown) transmits the rotation angle of the motor 27 to the control device. While moving within this range θ, a plurality of activation signals are supplied from the control device via the corresponding terminal 23t to the transducer within the angle θ indicated by the dashed line, in the case of the same figure, the transducer 23. be done. As a result, ultrasonic signals are transmitted and received from the transducer in the direction toward which the transducer faces. As the probes 2a and 2b in FIG. 5, probes having the above configuration are used.

The switching control unit 311 controls the probe 2 configured as described above.
A, 2b receives the rotation angle detection signal, selects the switches 307a, 307b, 301a, 301b so that the transducer corresponding to the angle is selected, and every time the rotation angle θ rotates, the driver 3
A synchronizing signal is given to 05a and 305b.

The drivers 305a and 305b are each synchronized by the synchronization signal, and generate a plurality of impulse signals with predetermined synchronization while the transducer rotates through the rotation angle θ.

Impulse signals with broadband frequency components are
As mentioned above, the signals are filtered by the filters 308a, 308b through the switches 307a, 307b into bands that can be divided into transmission bands, and the signals are transmitted to the probe 2.
It is supplied to the terminals a and 2b. probe 2a,
Each terminal 21t, 22t, 23t, 24t of 2b
In this case, the switching control section 311 switches between the probes 2a and 2b.
The selection is made based on the angle signal obtained from.

After being transmitted as described above, the signals received by the same transducer are transmitted to the amplifiers 300a and 300b, the switch 301a, and
The signal is supplied to the display control circuit 313 via filters 302a and 303b.

What should be noted in this embodiment is that the rotation control of the fixing jig 25 is taken into consideration by the switching control unit 311 in the control device so that the probes 2a and 2b do not transmit ultrasound beams of the same nature at the same time. The point is that it is.

For example, by simultaneously rotating the fixing jigs 25 at different angles by 90 degrees, ultrasonic beams of different properties can be transmitted at the same time. Also, if we look at one probe, 4
It is possible to obtain tomographic information measured using ultrasound beams with different properties. In the first embodiment, the time from time t ₁ to t ₂ indicates the time to start scanning the unit scanning area, but the number of beams is n (n = 1, 2, 3, ...). The properties of the beam may be changed each time.

Further, in the first and second embodiments, it has been described that the obtained tomographic information is displayed, but it is also effective to display the pattern in a different color for each frequency.

As described above in detail using the examples, it is possible to combine signals obtained by transmitting ultrasound beams with similar properties from different probes even at different times, so that the image itself becomes clear, 1
In terms of probes, since tomographic information can be obtained using multiple types of ultrasound beams, simple tissue characterization becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the principle of an embodiment of the invention, Fig. 2 is a concrete block diagram of an embodiment of the invention, and Figs. 3 and 4 show filtering characteristics of an embodiment of the invention. 5 and 6 are block diagrams of other embodiments of the present invention and diagrams for explaining the specific principle of the probe. In the figure, 1 is the specimen, 2 is the probe section, 3 is the control device,
4 is a display device, 2a, 2b are probes, 2sa, 2sb
4a is a scanning area, and 4a is a display screen.

Claims (1)

[Scope of Claims] 1. In an ultrasonic diagnostic apparatus having a plurality of ultrasonic probes and transmitting and receiving ultrasonic beams to and from a specimen to obtain tomographic information of the specimen, each probe sequentially What is claimed is: 1. An ultrasonic diagnostic apparatus comprising: a control device configured to transmit an ultrasonic beam with a property of different characteristics, and to make the characteristics of the ultrasonic beams transmitted by each probe different at least at the same time point; 2. An ultrasonic beam with a predetermined property transmitted by a predetermined probe at a predetermined time is characterized by being transmitted by a different probe at another time different from the said time. An ultrasonic diagnostic apparatus according to claim 1. 3. The ultrasonic diagnostic apparatus according to claim 1 or 2, wherein the properties of the ultrasonic beam include a sound field within the specimen. 4. Claim 1, characterized in that the ultrasonic diagnostic apparatus includes a display device, and the display device displays a combination of a plurality of pieces of tomographic information obtained by ultrasound beams of different properties. Or the ultrasonic diagnostic device according to item 2 or 3. 5. Claims 1 or 2 or 5, characterized in that the control device includes a discrimination filter that separates the different characteristics of received ultrasound signals from a plurality of ultrasound probes. The ultrasonic diagnostic device according to item 3 or 4. 6. The ultrasonic probe is configured such that a plurality of transmitting/receiving elements that emit ultrasonic beams of different properties are rotated, and the control device is configured to rotate the ultrasonic beams that are transmitted to and received from the specimen. Claim 1 or 2 or 3 or 4 is characterized in that the rotation of the ultrasound probes is controlled so that the ultrasound beams have different properties at the same time. or fifth
The ultrasonic diagnostic device described in Section 1.