JPH1176232A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of an ultrasonic image generation of noises from occurring by preventing an A/D converter of each channel in an ultrasonic transmitting/receiving part from being saturated. SOLUTION: In this ultrasonic diagnostic apparatus, an A/D output amplitude control circuit 15 wherein a receiving signal of each channel A/D-converted in an ultrasonic transmitting/receiving part 2 is inputted and the max. amplitude level is detected by monitoring the amplitude level and a gain correcting signal is outputted by detecting this max. amplitude level is provided and a digital variable gain amplification circuit 17 which makes gain variable on a digital receiving signal being A/D-converted in the ultrasonic transmitting/receiving part 2 and received wave-focused is provided. It is possible thereby that by controlling the A/D output amplitude control circuit 15, when the amplitude level of the receiving signal is small, amplification is performed by gain correction of analog variable gain amplification circuit 9a-9n in the ultrasonic transmitting/receiving part 2 and when the amplitude level of the receiving signal is at the max. amplitude, the amplification is performed by fixing the gain of the analog variable gain amplification circuit 9a-9n and performing gain correction of the digital variable gain amplification circuit 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus which obtains an ultrasonic image of a diagnostic site in a subject using ultrasonic waves and displays the image, and more particularly to image deterioration and noise generation of the ultrasonic image. TECHNICAL FIELD The present invention relates to an ultrasonic diagnostic apparatus capable of preventing the occurrence of an error.

[0002]

2. Description of the Related Art A conventional ultrasonic diagnostic apparatus of this type is shown in FIG.
As shown in FIG. 1, a probe 1 in which a large number of transducer elements are arranged and formed in multiple channels to transmit and receive ultrasonic waves in a subject
Then, the probe 1 is driven to transmit an ultrasonic wave, and the received reflected echo signal is amplified and variably converted into a digital signal by varying the gain in an analog manner. An ultrasonic transmission / reception unit 2 to be applied, an image processing circuit 3 for performing predetermined processing on an output signal from the ultrasonic transmission / reception unit 2, an image signal from the image processing circuit 3 to be input and written and read and displayed by a display coordinate system. Digital scan converter (hereinafter referred to as “DS
C "), and an image display device 5 for displaying an image signal from the DSC 4.

The internal configuration of the ultrasonic transmission / reception unit 2 generates a transmission signal for driving the probe 1 to transmit an ultrasonic wave, and a predetermined delay is given to each channel to focus the transmission. Sending wave focusing circuit 6
A transmission circuit 7 for converting a transmission signal generated by the transmission focus circuit 6 into a high-voltage signal to drive the transducer element group of the probe 1, and a probe receiving a reflected echo from inside the subject. First stage amplifier circuits 8a to 8n (assuming that there are n channels of transducer elements) for amplifying signals received from the transducer element group of the element 1, and receiving signals from the first stage amplifier circuits 8a to 8n, Analog variable gain amplifier circuits 9a to 9n for adjusting and amplifying gains, A / D converters 10a to 10n for converting output signals from the analog variable gain amplifier circuits 9a to 9n into digital signals,
Digital delay circuits 11a to 11n for providing a predetermined delay to digital reception signals from the D converters 10a to 10n;
A reception channel addition circuit 12 adds reception signals of the respective channels from the digital delay circuits 11a to 11n and focuses the reception.

In FIG. 2, reference numeral 13 denotes an operation panel on which the operator of the apparatus adjusts the image gain and the like. Reference numeral 14 denotes a gain adjustment signal input from the operation panel 13 to obtain an analog variable gain. Amplifier circuit 9a
9 to 9n show analog gain control signal generation circuits for transmitting gain control signals.

In such an ultrasonic diagnostic apparatus, the intensity of the reflected echo from the surface layer of the subject and the intensity of the reflected echo from the deep part of the received signal processed by the ultrasonic transmission / reception unit 2 are low. When displayed, particularly with respect to an ultrasonic image in a deep part, a good image cannot be obtained because of low contrast. On the other hand, the analog variable gain amplifying circuits 9a to 9n are provided in order to perform gain control so that the received signal from the surface layer is not greatly amplified according to the depth of the subject and the received signal from the deep part is greatly amplified. Have been. Further, since the signal level of the received signal is different between a fat person and a thin person depending on the physique of the subject, the analog variable gain amplifier circuits 9a to 9n operate in conjunction with the gain adjustment signal input on the operation panel 13. The gain can be controlled. Further, in order to improve the S / N of the digital phasing means including the digital delay circuits 11a to 11n and the reception channel adding circuit 12, the reception signals are converted into A / D converters 10a to 10n at a signal level as large as possible. It is desirable to input to

[0006]

However, in such a conventional ultrasonic diagnostic apparatus, each of the above A / D converters 1 is used.
The number of digital bits of the output signals 0a to 10n is usually about 8 to 12 bits in view of the processing speed and cost. With such digital bit numbers of the A / D converters 10a to 10n, the analog variable gain amplifier circuits 9a to 9n
If the gain of n becomes too high, the input signal becomes excessive and the A / D converters 10a to 10n are saturated. Therefore, A / D converters 10a to 10a
The output digital signal of n became abnormal, and the finally obtained ultrasonic image deteriorated or noise was generated.

Accordingly, the present invention addresses such a problem, and the A / D of each channel in the ultrasonic transmission / reception unit.
It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of preventing saturation of a converter and preventing image deterioration and noise generation of an ultrasonic image.

[0008]

In order to achieve the above object, a probe in which a large number of transducer elements are arranged and formed in multiple channels and transmits and receives ultrasonic waves to and from a subject is provided. An ultrasonic transmitting and receiving unit that drives and transmits ultrasonic waves and converts a received reflected echo signal into a digital signal,
An image processing circuit that performs a predetermined process on an output signal from the ultrasonic transmission / reception unit, a digital scan converter that reads an image signal from the image processing circuit, converts the read image signal into a display coordinate system, and outputs the digital signal. In the ultrasonic diagnostic apparatus having an image display device for displaying the image signal of the above, the received signal of each channel A / D converted in the ultrasonic transmitting and receiving unit is inputted, and the correction signal is outputted by detecting the signal level. A / D output control circuit is provided, and a digital variable gain amplifying circuit for varying the gain of a digital reception signal A / D converted in the ultrasonic transmission / reception unit is provided.

An ultrasonic diagnostic apparatus according to a preferred embodiment of the present invention comprises a probe in which a number of transducer elements are arranged and formed in multiple channels to transmit and receive ultrasonic waves to and from a subject. An ultrasonic transmitting and receiving unit that drives and transmits an ultrasonic wave and amplifies the received reflected echo signal by changing the gain in an analog manner and converts it to a digital signal, further giving a predetermined delay, and performing reception focusing, An image processing circuit that performs predetermined processing on an output signal from the ultrasonic transmission / reception unit, a digital scan converter that inputs and writes an image signal from the image processing circuit, reads the image signal, converts it into a display coordinate system, and outputs the digital scan converter. In an ultrasonic diagnostic apparatus having an image display device for displaying an image signal from the digital scan converter, an A / D conversion is performed in the ultrasonic transmitting and receiving unit. An A / D output amplitude control circuit for receiving a received signal of each channel, monitoring a signal amplitude level thereof, detecting a maximum amplitude level, and outputting a gain correction signal by detecting the maximum amplitude level; A digital variable gain amplifying circuit for varying the gain of a digital received signal that has been A / D converted and received and focused in the unit is provided. When the signal amplitude level of the received signal is small by the A / D output amplitude control circuit, The gain of the analog variable gain amplifying circuit in the ultrasonic transmission / reception unit is corrected and amplified, and when the signal amplitude level of the received signal becomes the maximum amplitude, the gain of the analog variable gain amplifying circuit is fixed and the digital variable gain amplifying circuit is fixed. The gain is corrected and amplified.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention. This ultrasonic diagnostic apparatus obtains an ultrasonic image of a diagnostic site in a subject using ultrasonic waves and displays the image. As shown in FIG. 1, a probe 1 and an ultrasonic transmitting / receiving unit 2 are provided. , An image processing circuit 3, a digital scan converter (hereinafter abbreviated as "DSC") 4, and an image display device 5, and further includes an A / D output amplitude control circuit 15, a digital gain control signal generation circuit 16 And a digital variable gain amplifier 17.

The probe 1 transmits and receives an ultrasonic wave toward a diagnostic site in a subject. Although not shown, the probe 1 is a source of the ultrasonic wave and receives a reflected echo. Are arranged in a multi-channel probe.

The ultrasonic transmission / reception unit 2 drives the probe 1 to transmit ultrasonic waves, amplifies the received reflected echo signal by changing the gain in an analog manner, converts the signal into a digital signal, and further converts the signal into a digital signal. The receiver focuses by giving a delay, and its internal configuration is to generate a transmission signal for driving the probe 1 to transmit an ultrasonic wave and to apply a predetermined delay to each channel in order to focus the transmission. Transmission focus circuit 6 for providing
The transmission circuit 7 converts the transmission signal generated in the above into a high-voltage signal and drives the transducer element group of the probe 1, and the transducer element group of the probe 1 that receives the reflected echo from inside the subject. First stage amplifier circuits 8a to 8n (assuming that the vibrator element has n channels), and the first stage amplifier circuit 8a
Analog gain amplifier circuits 9a to 9n, which receive the received signals from .about.8n and adjust and amplify the gain of each channel.
and an A / D converter 10 for converting output signals from the analog variable gain amplifier circuits 9a to 9n into digital signals.
a to 10n, digital delay circuits 11a to 11n for giving a predetermined delay to digital reception signals from the A / D converters 10a to 10n, and digital delay circuits 11a to 11n.
And a reception channel addition circuit 12 for adding the reception signals of the respective channels from 11n to focus the reception wave.

The image processing circuit 3 includes the ultrasonic transmitting / receiving unit 2
A predetermined process is performed on the output signal from the device, and for example, signal compression, envelope detection, and the like are performed. The DSC 4 receives the image signal from the image processing circuit 3 and writes and reads the image signal. The DSC 4 converts the image signal into a display coordinate system of an image display device 5 to be described later and outputs the converted image signal. , A memory writing unit, a digital memory unit, a memory reading unit, and the like. Further, the image display device 5 receives and displays the image signal from the DSC 4, and is composed of, for example, a television monitor.

In FIG. 1, reference numeral 13 denotes an operation panel on which an operator of the apparatus adjusts the gain of an image and the like, and reference numeral 14 denotes an analog variable gain obtained by taking in the gain adjustment signal input from the operation panel 13. Amplifier circuit 9a
9 to 9n show analog gain control signal generation circuits for transmitting gain control signals.

Here, in the present invention, an A / D output amplitude control circuit 15 is provided between the ultrasonic transmission / reception unit 2 and the operation panel 13, and the A / D output amplitude control circuit 15 has a digital gain. A control signal generation circuit 16 is connected, and a digital variable gain amplifier circuit 17 is provided between the reception channel addition circuit 12 and the image processing circuit 3 in the ultrasonic transmission / reception section 2. When the signal amplitude level of the received signal is small by the circuit 15, the analog variable gain amplifier circuits 9a to 9n in the ultrasonic transmission / reception unit 2 perform gain correction and amplify the signal, and the signal amplitude level of the received signal becomes the maximum amplitude. In this case, the gains of the analog variable gain amplifying circuits 9a to 9n are fixed, and the digital variable gain amplifying circuit 17 performs gain correction to amplify. There.

The A / D output amplitude control circuit 15 receives the received signal of each channel A / D converted in the ultrasonic transmission / reception unit 2, monitors the signal amplitude level, and detects the maximum amplitude level. A gain correction signal is output by detecting the maximum amplitude level, and comprises a maximum amplitude detection circuit 18 and a gain correction signal generation circuit 19. The maximum amplitude detection circuit 18 controls the A /
It receives the signals received from each channel of the D converters 10a to 10n, constantly monitors the signal amplitude level, and detects the maximum amplitude level. In the case where at least one channel reaches the signal amplitude level immediately before the maximum amplitude. Outputs the detection signal. Further, the gain correction signal generation circuit 19 includes the maximum amplitude detection circuit 1.
8 to output a gain correction signal by inputting a detection signal output from the control panel 8 and to input a detection signal of the maximum amplitude level and a gain adjustment signal from the operation panel 13 to generate an analog gain control signal. The gain correction signal is sent to the circuit 14 and the digital gain control signal generation circuit 16.

Also, a digital gain control signal generating circuit 1
Numeral 6 is for inputting a gain correction signal from a gain correction signal generation circuit 19 in the A / D output amplitude control circuit 15 to generate a gain control signal. Further, the digital variable gain amplifying circuit 17
The gain control signal from the digital gain control signal generation circuit 16 is input to the reception channel addition circuit 12 in the ultrasonic transmission / reception unit 2 for varying the gain of the digital reception signal subjected to the / D conversion and the reception focus. The gain of the received output signal is digitally varied. The digital variable gain amplifier 17 is not limited to the inside of the ultrasonic transmission / reception unit 2 and may be provided outside.

Next, the operation of the thus configured ultrasonic diagnostic apparatus of the present invention will be described. First, the maximum amplitude detection circuit 18 in the A / D output amplitude control circuit 15 fetches reception signals from each channel of the A / D converters 10a to 10n in the ultrasonic transmission / reception unit 2 and constantly changes the signal amplitude level. Monitor and detect the maximum amplitude level. At this time, if at least one channel reaches the signal amplitude level immediately before the maximum amplitude, the detection signal is output and sent to the gain correction signal generation circuit 19. Then, the gain correction signal generation circuit 19 is connected to the maximum amplitude detection circuit 1.
8 and the gain adjustment signal from the operation panel 13 as well as the maximum amplitude level detection signal
A gain correction signal is sent to the analog gain control signal generation circuit 14 and the digital gain control signal generation circuit 16.

At this time, the gain correction signal generation circuit 1
Reference numeral 9 denotes an analog variable gain amplifying circuit 9 via an analog gain control signal generating circuit 14 in accordance with the content of the detection signal of the signal amplitude level output from the maximum amplitude detecting circuit 18.
a to 9n and the digital variable gain amplifying circuit 17 via the digital gain control signal generating circuit 16 are controlled as follows. First, when the signal amplitude level detected by the maximum amplitude detection circuit 18 is small, the amplification of the reception signal in the ultrasonic transmission / reception unit 2 is performed by the analog variable gain amplification circuit 9a.
The gain of the digital variable gain amplifying circuit 17 is fixed to the minimum gain.
On the other hand, when the signal amplitude level reaches just before the maximum amplitude even in one channel, the analog variable gain amplifier circuit 9a
The gains up to 9n are fixed at the gains immediately before reaching the maximum level, and the remaining amplification gains amplify the received signal by varying the gain of the digital variable gain amplifier circuit 17.

For example, when the number of digital bits of the output signals of the A / D converters 10a to 10n is 10 bits, the maximum output data is 3FFH, but the detection signal of the signal amplitude level output from the maximum amplitude detection circuit 18 is If even one channel exceeds 3A0H (for example, about 90% of 3FFH, which is just before the maximum amplitude), the detection signal is output to the gain correction signal generation circuit 19, and the gain correction signal generation circuit 19 , Analog variable gain amplifier circuit 9a
A gain correction signal for fixing the gain of .about.9n is sent to the analog gain control signal generation circuit 14. Then, the analog gain control signal generation circuit 14 sends a gain control signal to the analog variable gain amplifier circuits 9a to 9n, and the gain is fixed at the gain immediately before reaching the maximum level. In this case, there is a margin until the A / D converters 10a to 10n are saturated by 3FFH-3A0H = 5FH. Thereby, the A / D converters 10a to 10n
Can operate without saturation. Therefore, it is possible to prevent saturation of the A / D converters 10a to 10n of each channel in the ultrasonic transmission / reception unit 2, thereby preventing image deterioration of the ultrasonic image and generation of noise.

If the maximum amplitude of the signal level is detected by the maximum amplitude detection circuit 18, the A / D
The warning of the saturation of the converters or the generation of a warning sound can also alert the operator to the saturation of the A / D converters 10a to 10n. Further, even when the signal level of the received signal greatly changes depending on the physique of the subject, the A / D
Before the warning display or warning sound of the saturation of the converter is generated, the A / D converters 10a to 10n are not saturated.
A received signal having a maximum amplitude level can be input to the input terminal. From this, it is possible to improve the S / N of digital phasing. Therefore, even if the subject changes and the signal level of the received signal changes, the operator can operate the operation panel 13 and input the gain adjustment signal to achieve the best gain, thereby improving the image quality of the ultrasonic image. can do.

[0022]

The present invention has been configured as described above.
A / D which receives a received signal of each channel which has been A / D converted in the ultrasonic transmission / reception unit, monitors the signal amplitude level, detects a maximum amplitude level, and outputs a gain correction signal by detecting the maximum amplitude level. By providing an output amplitude control circuit and providing a digital variable gain amplifying circuit that varies the gain of a digital reception signal that has been A / D converted and received and focused in the ultrasonic transmission / reception unit,
If the signal amplitude level of the received signal is small by the control of the A / D output amplitude control circuit, the analog variable gain amplifier circuit in the ultrasonic transmission / reception unit performs gain correction to amplify the signal, and the signal amplitude level of the received signal is maximized. In the case of the amplitude, the gain of the digital variable gain amplifier circuit can be corrected by fixing the gain of the analog variable gain amplifier circuit to amplify. Therefore, it is possible to prevent saturation of the A / D converter of each channel in the ultrasonic transmission / reception unit, thereby preventing image deterioration of the ultrasonic image and generation of noise.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a block diagram showing a conventional ultrasonic diagnostic apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 probe 2 ultrasonic transmission / reception unit 3 image processing circuit 4 DSC 5 image display device 8 a to 8 n initial stage amplifier 9 a to 9 n analog variable gain amplifier 10 a to 10 n A / D converter 11 a to 11 n digital delay circuit 12 reception channel Addition circuit 13 Operation panel 14 Analog gain control signal generation circuit 15 A / D output amplitude control circuit 16 Digital gain control signal generation circuit 17 Digital variable gain amplification circuit 18 Maximum amplitude detection circuit 19 Gain correction signal generation circuit

Claims (1)

[Claims] 1. A probe in which a large number of transducer elements are arranged and formed in multiple channels to transmit and receive an ultrasonic wave into a subject, and a reflection device which drives the probe to transmit the ultrasonic wave and receives the ultrasonic wave. An ultrasonic transmitting / receiving unit that converts an echo signal into a digital signal, an image processing circuit that performs predetermined processing on an output signal from the ultrasonic transmitting / receiving unit, and reads an image signal from the image processing circuit and converts it into a display coordinate system In an ultrasonic diagnostic apparatus having a digital scan converter for outputting and outputting, and an image display device for displaying an image signal from the digital scan converter, a reception signal of each channel A / D-converted in the ultrasonic transmission / reception unit is transmitted. An A / D output control circuit for inputting and outputting a correction signal upon detection of the signal level is provided, and reception of A / D-converted digital data in the ultrasonic transmitting / receiving section is performed. An ultrasonic diagnostic apparatus comprising a digital variable gain amplifier circuit that varies a gain of a signal.