JPH11347030A - Method and device for ultrasonic transmission/reception and ultrasonic imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the harmonic component to be removed from transmitted ultrasonic waves by giving drive signals whose harmonic component is removed by a filter to an ultrasonic transducer to transmit echo signals through a signal transmitting circuit by-passing the filter at a gain smaller than 1 to a transmission/reception circuit. SOLUTION: An ultrasonic probe comprising an arrayed ultrasonic transducer 30 transmits ultrasonic waves into a subject 4 by applied drive signals from a transmission/reception part. At that time, the drive signals applied on the ultrasonic transducer 30 are passed through a low band filter 640 to remove the harmonic component and made only the fundamental wave component. When receiving echoes, a diode 602 is sequentially biassed by a negative DC voltage -VEE to flow current between emitter and base of a transistor Tr 604 to turn on the transistor Tr 604 to change the collector current of the TR 604 corresponding to echo reception signals and the change is guided out through a capacitor 603.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transmission / reception method and apparatus and an ultrasonic imaging apparatus, and more particularly, to an ultrasonic transmission / reception method and apparatus using harmonic echo and an ultrasonic imaging apparatus.

[0002]

2. Description of the Related Art As an example of ultrasonic imaging using harmonic echo, there is contrast imaging using a micro balloon.
This is to image the distribution state of the microballoon injected into the body, utilizing the fact that the microballoon generates an echo including the second harmonic of the transmitted ultrasonic wave due to its nonlinear echo source characteristic. .

As another example of ultrasonic imaging using harmonic echo, there is ultrasonic imaging using a nonlinear effect of ultrasonic propagation in a subject, that is, parametric imaging. Here, when an ultrasonic wave is transmitted into a subject, imaging is performed by using second and third harmonic echoes generated by nonlinearity of ultrasonic propagation in the body.

[0004]

In any of the above, if a transmitted ultrasonic wave contains a harmonic component from the beginning, the echo can be distinguished from a harmonic echo from a microballoon or an echo due to a non-linear effect. Therefore, there is a problem that proper imaging cannot be performed. In particular, the rectangular pulse drive method, which is commonly used as the drive method of the ultrasonic transducer, cannot prevent the transmitted ultrasonic wave from containing harmonic components. Cannot do it.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an ultrasonic transmission / reception method and apparatus provided with a simple technique for removing harmonic components from transmitted ultrasonic waves, as well as ultrasonic imaging. The realization of the device.

[0006]

(1) According to a first aspect of the invention for solving the above-mentioned problems, the ultrasonic transducer is provided with a unipolar drive signal from a transmission / reception circuit to transmit ultrasonic waves. An ultrasonic transmission / reception method in which a received echo signal is received by the transmission / reception circuit, wherein a harmonic component is removed by a filter between the ultrasonic transducer and the transmission / reception circuit, and the drive signal is transmitted by the ultrasonic transducer. And transmitting the echo signal to the transmission / reception circuit with a gain smaller than 1 by a signal transmission circuit that bypasses the filter.

(2) A second aspect of the present invention to solve the above-mentioned problem is that an ultrasonic transducer is provided with a unipolar drive signal from a transmission / reception circuit to transmit an ultrasonic wave, and an echo signal received by the ultrasonic transducer is received. An ultrasonic transmitting and receiving apparatus that receives the transmitting and receiving circuit in the transmitting and receiving circuit, a filter that is interposed between the ultrasonic transducer and the transmitting and receiving circuit, removes a harmonic component, and provides the driving signal to the ultrasonic transducer, An ultrasonic transmission / reception device interposed between an ultrasonic transducer and the transmission / reception circuit, wherein the signal transmission circuit bypasses the filter and transmits the echo signal to the transmission / reception circuit with a gain smaller than 1. It is.

(3) According to a third aspect of the present invention, an ultrasonic transducer is provided with a unipolar drive signal from a transmission / reception circuit to transmit an ultrasonic wave, and an echo signal received by the ultrasonic transducer is provided. Is received by the transmitting and receiving circuit, an ultrasonic imaging apparatus that generates an image based on an echo signal, intervening between the ultrasonic transducer and the transmitting and receiving circuit, removing the harmonic components and the drive signal A filter applied to the ultrasonic transducer,
A signal transmission circuit interposed between the ultrasonic transducer and the transmission / reception circuit, the signal transmission circuit bypassing the filter and transmitting the echo signal to the transmission / reception circuit with a gain smaller than 1. An imaging device.

In any one of the first to third aspects of the present invention, it is preferable that the filter is an LC filter from the viewpoint of obtaining an appropriate harmonic elimination characteristic. Further, in any one of the first to third inventions, the signal transmission circuit is a common-base transistor circuit in which a forward diode is connected in series to the emitter, thereby simplifying the circuit. preferable.

In the first invention or the third invention, the filter and the signal transmission circuit may be a detachable relay unit between the transmission / reception circuit and the ultrasonic transducer, if necessary. It is preferable in terms of utilization.

(Operation) In the present invention, the filter removes the harmonic component from the drive signal of the transmission / reception circuit and supplies it to the ultrasonic transducer. The echo signal received by the ultrasonic transducer is transmitted by the signal transmission circuit bypassing the filter. Notify the transmitting / receiving circuit.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiment. FIG. 1 shows a block diagram of the ultrasonic imaging apparatus. This apparatus is an example of an embodiment of the ultrasonic imaging apparatus of the present invention. An example of an embodiment of the device of the present invention is shown by the configuration of the present device. An example of an embodiment of the method of the present invention is shown by the operation of the present apparatus.

The configuration of the present apparatus will be described. As shown in FIG. 1, the present apparatus has an ultrasonic probe (probe) 2. The ultrasonic probe 2 has an ultrasonic transducer array (not shown). Ultrasonic probe 2
Is used in contact with the subject 4 by an operator (not shown). The subject 4 is provided with a microballoon contrast agent 4 in advance.
0 has been injected.

The ultrasonic probe 2 is connected to a transmitting / receiving unit 8 via a relay unit 6. Ultrasonic probe 2, relay section 6
The portion including the transmitting / receiving section 8 is an example of an embodiment of the ultrasonic transmitting / receiving apparatus of the present invention. The details of the relay section 6 will be described later. The transmission / reception unit 8 supplies a drive signal to the ultrasonic probe 2 via the relay unit 6 to transmit an ultrasonic wave into the subject 4. The transmitting / receiving unit 8 receives the echo from the subject 4 received by the ultrasonic probe 2 via the relay unit 6.

FIG. 2 shows a block diagram of the transmission / reception section 8. As shown in FIG. In the figure, a transmission timing (timing) generation circuit 802
Is configured to periodically generate a transmission timing signal and input the transmission timing signal to a transmission beamformer (beamformer) 804.

The transmission beamformer 804 performs transmission beamforming based on the transmission timing signal.
ming) signal, that is, a plurality of driving signals for driving a plurality of ultrasonic transducers constituting a transmitting aperture in the ultrasonic transducer array with a time difference, and inputting them to the transmission / reception switching circuit 806. I have.

The transmission / reception switching circuit 806 is configured to input a plurality of drive signals to the ultrasonic transducer array via the relay section 6. The transmit aperture in the array (ape
Each of the plurality of ultrasonic transducers constituting the rture) generates a plurality of ultrasonic waves having a phase difference corresponding to a time difference between the plurality of drive signals. An ultrasonic beam is formed by wavefront synthesis of those ultrasonic waves.

The transmission of the ultrasonic beam is repeatedly performed at predetermined time intervals by a transmission timing signal generated by a transmission timing generation circuit 802. The direction of the ultrasonic beam is sequentially changed by the transmission beam former 804.
Thereby, the inside of the subject 4 is scanned by the sound ray formed by the ultrasonic beam. That is, the inside of the subject 4 is scanned in a sound ray sequence.

A plurality of echo signals received by the reception aperture in the ultrasonic transducer array are input to the transmission / reception switching circuit 806 via the relay unit 6. The transmission / reception switching circuit 806 inputs the plurality of echo signals to the reception beam former 810. The reception beamformer 810 applies a time difference to the plurality of reception echoes to adjust the phases, and then adds them to form an echo reception signal along the sound ray, that is, to perform beamforming of the reception wave. Has become. Receive beamformer 810
Thus, the sound ray of the received wave is also scanned in accordance with the transmitted wave. The transmission timing generation circuit 802 to the reception beam former 810 are controlled by the control unit 18 described later.

The transmitting / receiving section 8 having such a configuration performs, for example, scanning as shown in FIG. That is, the radiation point 200
An ultrasonic beam (sound ray) 202 extending in the z-direction scans a fan-shaped two-dimensional area 206 in the θ-direction to perform a so-called sector scan.

When the transmitting and receiving apertures are formed by using a part of the ultrasonic transducer array, the apertures are sequentially moved along the array to perform scanning as shown in FIG. 4, for example. Can be. That is, the sound ray 2 emitted from the radiation point 200 in the z direction
02 is translated along the linear trajectory 204, so that the rectangular two-dimensional area 206 is scanned in the x direction, so-called linear scan is performed.

The ultrasonic transducer array is
In the case of a so-called convex array formed along an arc extending in the ultrasonic wave transmission direction, for example, as shown in FIG. The point 200 is moved along the arc-shaped trajectory 204, and the fan-shaped two-dimensional area 20 is moved.
It is needless to say that so-called convex scanning can be performed by scanning 6 in the θ direction.

The transmission / reception unit 8 is connected to a B mode (mode) processing unit 10 and inputs an echo reception signal for each sound ray to the B mode processing unit 10. B-mode processing unit 10
Is for forming B-mode image data (data). B
The mode processing unit 10 includes a fundamental wave processing unit 110 and a harmonic processing unit 130, for example, as shown in FIG. The output signal of the receiving beamformer 810 is commonly input to the fundamental wave processing unit 110 and the harmonic processing unit 130.

The fundamental wave processing unit 110 has a filter (not shown) for passing a fundamental wave echo, that is, an echo reception signal having the same frequency as the center frequency of the transmitted ultrasonic wave. The harmonic processing unit 130 has a filter (not shown) that passes an echo reception signal having a frequency corresponding to the second harmonic (second harmonic) of the fundamental frequency. This filter is not limited to the second harmonic, and may be a filter adapted to a third or higher harmonic.

The fundamental wave processing unit 110 performs
By performing logarithmic amplification and envelope detection of the fundamental wave echo, a signal representing the intensity of the echo at each reflection point on the sound ray, that is, an A scope signal is obtained, and the instantaneous amplitude of the A scope signal is obtained. B-mode image data is formed as each luminance value. That is, the fundamental wave processing unit 110 generates B-mode image data based on the fundamental wave echo.

The harmonic processing unit 130 converts the input signal
By performing logarithmic amplification and envelope detection of the second harmonic echo, a signal representing the intensity of the echo at each reflection point on the sound ray, that is, an A scope signal is obtained, and the amplitude of each instant of the A scope signal is determined. B-mode image data is formed as the luminance value. That is, the harmonic processing unit 130 generates B-mode image data based on the second harmonic echo.

The B mode processing unit 10 is connected to the image processing unit 14. The image processing unit 14 includes the B-mode processing unit 10
A plurality of B-mode images are respectively generated based on two types of B-mode image data input from.

As shown in FIG. 7, the image processing unit 14 includes a sound ray data memory (d) connected by a bus 140.
ata memory) 142, digital scan converter
(digital scan converter) 144, an image memory 146 and an image processor 148.

The B-mode image data based on the fundamental echo and the second harmonic echo input from the B-mode processing unit 10 for each sound ray is stored in the sound ray data memory 142, respectively. Each sound ray data space is formed in the sound ray data memory 142.

Digital Scan Converter 144
Is for converting data in a sound ray data space into data in a physical space by scan conversion. The image data converted by the digital scan converter 144 is stored in the image memory 146. That is, the image memory 1
Reference numeral 46 stores image data of the physical space. The image processor 148 performs predetermined data processing on the data in the sound ray data memory 142 and the image memory 146, respectively.

A display unit 16 is connected to the image processing unit 14. The display unit 16 is provided with an image signal from the image processing unit 14 and displays an image based on the image signal. The display unit 16 is configured by, for example, a graphic display capable of displaying a color image.

The transmission / reception section 8, the B-mode processing section 10,
The image processing unit 14 and the display unit 16 are connected to the control unit 18. The control unit 18 supplies a control signal to each unit to control its operation. Further, the control unit 18 is configured to receive various notification signals from the controlled units. Ultrasonic imaging is performed under the control of the control unit 18.

An operation unit 20 is connected to the control unit 18. The operation unit 20 is operated by the operator, and the control unit 18
A desired command or information is input to the device. The operation unit 20 includes, for example, an operation panel provided with a keyboard and other operation tools.

FIG. 8 shows an example of the structure of the relay section 6 together with the ultrasonic transducer for one channel of the ultrasonic transducer array. In the figure, an ultrasonic transducer 30 is an ultrasonic transducer for one channel in an ultrasonic transducer array. A resistor 32 is connected to the ultrasonic transducer 30 in parallel.
One end of a capacitor 34 is connected to a parallel circuit of the resistor 32 and the resistor 32.

The other end of the capacitor 34 is connected to a connector 500
Through the contact of the cathode of the diode 602 (ca
thode) is connected. The anode of the diode 602 is connected to the emitter of a transistor 604. The base of the transistor 64 is connected to common. The collector of transistor 604 is connected to resistor 606
And a contact point of the connector 900 to a supply source of a positive DC voltage + VCC (not shown). The value of the DC voltage VCC is, for example, + 5V.

The collector of transistor 604 also
The capacitor 608 is connected to the signal line 610. The signal line 610 is connected to the transmitting / receiving unit 8 through the contact of the connector 900.

The signal line 610 also includes a capacitor 61
2 are connected at one end. The other end of the capacitor 612 is connected to one end of a series circuit of inductors 614 to 620. A connection point between the inductors 614 and 616, a connection point between the inductors 616 and 618, and
Capacitors 622, 624, and 626 are connected between the connection point of inductors 618 and 620 and the common, respectively. Such inductors 614-620
And capacitors 622 to 626 constitute an LC filter.

The other end of the series circuit of the inductors 614 to 620 is connected to a connection point between the capacitor 34 and the diode 602. The connection point between the capacitor 34 and the diode 602 is connected to a negative DC voltage -VEE supply source (not shown) through a resistor 628 and a contact point of the connector 900. The value of the DC voltage -VEE is-
5V.

Here, a circuit including the diode 602, the transistor 604, and the capacitor 608 constitutes a signal transmission circuit 630 for transmitting an echo reception signal to the transmission / reception section 8, as described later. The signal transmission circuit 630 is an example of an embodiment of the signal transmission circuit of the present invention.
Inductors 614-620 and capacitors 616-6
The LC filter composed of 20 constitutes a low-pass filter 640 that blocks harmonic components of the drive signal, as described later. The low-pass filter 640 is an example of an embodiment of the filter according to the present invention.

At the time of transmitting an ultrasonic wave, a predetermined number of unipolar square wave drive pulses arrive via a signal line 610. The unipolar drive pulse has an amplitude of, for example, +100 V and a frequency of, for example, 1.5 MHz. The drive pulse is applied to the ultrasonic transducer 30 through the low-pass filter 640 and the capacitor 34.

The driving signal applied to the ultrasonic transducer 30 passes through the low-pass filter 640 so that harmonic components are removed and becomes only the fundamental wave component. Therefore, the ultrasonic transducer 30 driven by such a signal is driven.
Transmits an ultrasonic wave consisting of only a fundamental wave component.

At this time, on the signal transmission circuit 630 side, a positive high voltage drive signal is applied to the anode of the diode 602, so that the diode 602 is reverse biased (b
ias). Therefore, the base of the transistor 604
Since no current flows between the emitters and the transistor 604 is turned off, the drive signal does not pass through the signal transmission circuit 630.

When the echo is received, the diode 602 is forward-biased by the negative DC voltage -VEE, so that a current flows between the base and the emitter of the transistor 604, and the transistor 604 is in a conductive state. Then, the base-emitter current of the transistor 604 is
Modulated by the echo received signal of the ultrasonic transducer 30 provided through the capacitor 34, whereby the collector current changes, and the collector voltage changes due to the effect of the resistor 606. The change in the collector voltage is output to the inner conductor of the signal line through the capacitor 608 and received by the transmission / reception unit 8.

The output signal of the transistor 604 is fed back to the anode of the diode 602 through the low-pass filter 640. However, since the transistor 604 has a grounded base circuit, the gain of amplification is smaller than 1, and the oscillation It works stably without doing anything.

Such a circuit is provided for all channels of the ultrasonic transducer array. In this case, a unit including the signal transmission circuit 630 and the filter 640 for all channels is connected to a relay unit (unit) 70 that can be connected to a connector, for example, as schematically shown in FIG.
0, the relay unit 700 may be an intermediate connecting member between the connector 500 of the ultrasonic probe 2 and the connector 900 on the ultrasonic imaging apparatus main body side. This makes it possible to easily add a harmonic removing unit to a general ultrasonic imaging apparatus that includes harmonics in transmitted ultrasonic waves.

The operation of the present apparatus will be described. The operator touches the ultrasonic probe 2 to a desired portion of the subject 4 and operates the operation unit 20 to perform imaging. The imaging is performed under the control of the control unit 18.

For imaging, a sector scan as shown in FIG. 3, for example, is performed in the order of sound rays, an ultrasonic beam for imaging is transmitted for each sound ray, its echo is received, and the echo is received. To generate a B-mode image. Of course, the linear scan and the convex scan shown in FIGS. 4 and 5 may be performed.

The B-mode image data is formed by the B-mode processing unit 10 based on the echo reception signal of each sound ray. The B-mode image data is formed based on the fundamental echo and the second harmonic echo, respectively, and is stored in the sound ray data memory 142 of the image processing unit 14.

The image processor 148 scan-converts a plurality of B-mode image data in the sound ray data memory 142 with the digital scan converter 144 and writes the data into the image memory 146.

The operator operates the operation unit 20 to display these B-mode images on the display unit 16. That is,
For example, as shown in FIG.
A composite image with the harmonic echo image 162 is displayed. Since the transmitted ultrasonic wave does not include harmonics, the second harmonic echo image 162 shows only the image of the microballoon, and correct contrast imaging can be performed.

The above is an example of performing contrast imaging using harmonic echoes. However, the present invention is not limited to this, and it goes without saying that parametric imaging based on non-linear effects may be performed.

Although the example of capturing a B-mode image has been described, ultrasonic imaging is not limited to this, and a dynamic image may be captured using Doppler shift of an echo. Needless to say.

[0053]

As described above in detail, according to the present invention, it is possible to realize an ultrasonic transmission / reception method and apparatus and an ultrasonic imaging apparatus having a simple technique for removing harmonic components from transmitted ultrasonic waves. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device according to an example of an embodiment of the present invention.

FIG. 2 is a block diagram of a transmission / reception unit in the device according to an embodiment of the present invention;

FIG. 3 is a conceptual diagram of sound ray scanning performed by the apparatus according to the embodiment of the present invention;

FIG. 4 is a conceptual diagram of sound ray scanning performed by the apparatus according to an embodiment of the present invention;

FIG. 5 is a conceptual diagram of sound ray scanning performed by the apparatus according to the embodiment of the present invention;

FIG. 6 is a block diagram of a B-mode processing unit in the device according to an example of the embodiment of the present invention.

FIG. 7 is a block diagram of an image processing unit in the apparatus according to the embodiment of the present invention;

FIG. 8 is a circuit diagram illustrating an example of a relay unit in the device according to an example of the embodiment of the present invention;

FIG. 9 is a schematic diagram illustrating a use state of a relay unit in the device according to the embodiment of the present invention;

FIG. 10 is a schematic diagram of a display image in the device according to an example of the embodiment of the present invention.

[Explanation of symbols]

 2 Ultrasonic probe 4 Subject 40 Micro balloon contrast agent 6 Relay unit 8 Transmitter / receiver unit 10 B-mode processing unit 14 Image processing unit 16 Display unit 18 Control unit 20 Operation unit 802 Transmission timing generation circuit 804 Transmission beamformer 806 Transmission / reception switching Circuit 810 Receive beamformer 110 Fundamental wave processing unit 130 Harmonic processing unit 630 Signal transmission circuit 640 Filter 700 Relay unit

Claims (3)

[Claims] An ultrasonic transmission / reception method in which a unipolar drive signal is applied to an ultrasonic transducer from a transmission / reception circuit to transmit ultrasonic waves, and an echo signal received by the ultrasonic transducer is received by the transmission / reception circuit. Between the ultrasonic transducer and the transmitting and receiving circuit,
The drive signal is supplied to the ultrasonic transducer by removing a harmonic component by a filter, and the echo signal is transmitted to the transmission / reception circuit with a gain smaller than 1 by a signal transmission circuit bypassing the filter. Ultrasonic transmission and reception method. 2. An ultrasonic transmitting and receiving apparatus, wherein an ultrasonic transducer is supplied with a driving signal of a single polarity from a transmitting and receiving circuit to transmit an ultrasonic wave, and an echo signal received by the ultrasonic transducer is received by the transmitting and receiving circuit. Interposed between the ultrasonic transducer and the transmitting and receiving circuit, a filter for removing the harmonic component and providing the drive signal to the ultrasonic transducer, interposed between the ultrasonic transducer and the transmitting and receiving circuit, A signal transmission circuit that transmits the echo signal to the transmission / reception circuit with a gain smaller than 1 by bypassing the filter. 3. An ultrasonic transducer is provided with a unipolar drive signal from a transmission / reception circuit to transmit an ultrasonic wave, an echo signal received by the ultrasonic transducer is received by the transmission / reception circuit, and based on the echo signal. An ultrasonic imaging apparatus that generates an image, a filter that is interposed between the ultrasonic transducer and the transmission / reception circuit, removes a harmonic component, and applies the drive signal to the ultrasonic transducer, and the ultrasonic transducer And a signal transmission circuit interposed between the transmission / reception circuit and bypassing the filter and transmitting the echo signal to the transmission / reception circuit with a gain smaller than 1.