JP3515630B2 - Ultrasound diagnostic equipment - Google Patents

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, and more particularly to an ultrasonic diagnostic apparatus for reducing side lobe signals (pseudo echo).

[0002]

2. Description of the Related Art In an ultrasonic diagnostic apparatus, an array transducer is composed of a plurality of transducers, and electronic focusing of an ultrasonic beam is performed by appropriately setting a delay amount of a delay circuit connected to each transducer. To be done. That is, in the transmission focus, the transmission delay amount of each transducer is set so that the time phase of the transmission wave from each transducer matches at a predetermined focus. On the other hand, also in the reception focus, a delay is given to the reception signal of each transducer so that the time phases of the reception waves from the predetermined focus coincide with each other. In the electronic sector scanning, similarly to this, the ultrasonic beam is scanned by the delay of the transmitted wave and the received wave.

According to electronic focusing, ultrasonic waves can be focused on a focal point to form an ultrasonic beam (main beam), but in reality, ultrasonic waves are also emitted as unnecessary radiation (side lobes) in other directions. Is emitted. Then, when the side lobe is reflected by a reflector in a direction different from the focus direction, it becomes a reflected wave and is received by each transducer. In particular, when the reflector is a strong reflector, the pseudo echo remains without being erased by the phase addition after the delay, and the ultrasonic image is displayed as if the reflector were in the main beam direction. The image deteriorates.

Therefore, Japanese Patent Publication No. 34410/1992 discloses an ultrasonic diagnostic apparatus for reducing side lobe signals which cause pseudo echo (artifact).
In such a conventional device, the transducer group is divided into two reception groups at the time of reception. Then, after the received signals are combined into a combined signal in each group, the combined signal is detected in a detection circuit to be an envelope signal. The envelope signals are then compared with each other. Here, the true echo has the same time phase due to the delay of the received signal, and the one pseudo echo has the time phase mismatch due to the delay.Therefore, when comparing the combined signals between the two groups, the common signal component is true. It is possible to determine that the signal components that do not match are pseudo echoes. In this conventional device, the degree of true echo is obtained based on the theory, and the pseudo echo is excluded from the received signal.

[0005]

In this conventional example, the envelope signal is formed from the combined signal by detection for waveform comparison, but in order to simplify the configuration of the device and thereby reduce the cost of the device. It is desired to reduce the side lobe signal with a circuit as simple as possible.

The present invention has been made in view of the above conventional problems, and an object thereof is to provide an ultrasonic diagnostic apparatus capable of easily reducing sidelobe signals with a simple configuration.

[0007]

In order to achieve the above object, the present invention is provided with a vibrator group composed of a plurality of vibrators, and a delay circuit is connected to each vibrator so that an ultrasonic beam electron beam is transmitted. In an ultrasonic diagnostic apparatus in which focusing is performed, a reception group setting unit that divides the transducer group into a plurality of reception groups at the time of reception, and a delayed reception signal from each transducer is combined for each of the reception groups, A combining means for forming a combined signal, an amplitude processing means for adjusting the amplitudes of the combined signals of the reception groups output from the combining means to the smaller ones, and a combined signal of the reception groups with the adjusted amplitudes before detection. And adding means for adding in the state of.

Further, according to the present invention, an A / D converter is provided between the synthesizing means and the amplitude processing means, and the amplitude processing means and the adding means are constituted by a single table. Is characterized by.

[0009]

According to the above configuration, the received signal from each transducer is first given a predetermined delay amount in the delay circuit, and then,
The synthesizing means synthesizes each reception group set by the reception group setting means. That is, a combined signal is formed for each reception group. Next, in the amplitude processing means, the amplitudes of the combined signals are adjusted to be smaller. As a result, since the true echoes have the same phase due to the delay, if the number of transducers in the group is the same, the amplitudes basically match in each synthesized signal, but the pseudo echoes have the same phase due to the delay. Because,
The amplitude of the pseudo echo (sidelobe signal) disappears or becomes smaller in each combined signal because one of them is controlled by the amplitude of the other. By adding each combined signal after that and forming an image by the added signal, a clear ultrasonic image with reduced pseudo echo can be formed.

According to the present invention, in the received signal after the delay,
The sidelobe signals are canceled out on the assumption that the true echoes basically have the same amplitude and phase, while the sidelobe signals basically do not have the same amplitude and phase. In the present invention, since the comparison of the combined signal is performed in the state of the high frequency signal, the detection circuit for forming the envelope, which is conventionally required as the preprocessing, is unnecessary. Also, since the side lobe signal can be removed and reduced by only amplitude processing, the configuration can be greatly reduced as compared with the conventional device. Therefore, a more useful circuit can be configured with an actual device.

The amplitude processing means and the adding means may be constructed by a single table. In that case, for example, the amplitude value of two combined signals is set to two inputs, and the smaller one of the two inputs. A circuit that outputs a doubled value when the same sign has the same sign and outputs a value that becomes 0 when the sign has a different sign may be used.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention. FIG. 1 shows the configuration of the receiving section of the ultrasonic diagnostic apparatus, and the transmitting section is the same as the conventional one. Therefore, the illustration is omitted.

In FIG. 1, the transducer group 10 is divided into a plurality of receiving groups during reception. In the present embodiment, it is divided into two reception groups, and is divided into a reception group having transducer numbers 1 to n / 2 and a reception group having transducer numbers (n / 2 + 1) to n. . This is done by the action of the distributor 12, which will be described later. That is, the distributor 12 has a function as a reception group setting means. In the ultrasonic diagnostic apparatus of this embodiment, electronic sector scanning is performed, and at the time of transmission, all transducers are driven and ultrasonic beams are scanned.

Each oscillator 10a has a delay circuit 14
Are connected. The delay circuit 14 delays the received signal by a set delay amount for each received signal, and the delay amount is set according to the electronic sector scanning and the electronic focus. That is, the delay amount for each reception signal is set so that the phases of the reception waves from the predetermined focus points match. At the time of transmission, another delay circuit or the delay circuit 14 is used to scan the ultrasonic beam.

The received signal from each delay circuit 14 is a distributor 1
It is entered in 2. The distributor 12 adds received signals for each of the receiving groups (I) and (II) to form a combined signal. That is, the distributor 12 has a function as a combining means, in addition to the function as the reception group setting means described above.

The ADC 16 is for converting each composite signal from an analog signal to a digital signal. The equalizer 18 compares the amplitudes of the composite signals converted into digital signals with each other, and aligns the amplitudes of the received signals with the smaller amplitude. In other words, the common signal of the two combined signals is extracted. The adder 20 is for adding the combined signals having the same amplitude. The received signal (combined signal) output from the adder 20 is then subjected to predetermined processing, detected by a detection circuit, and finally sent to a display device to display a tomographic image.

Next, the operation of the above configuration will be described.
In FIG. 1, a transmission pulse (not shown) is supplied to each transducer 10a via a transmission delay circuit. As a result, ultrasonic waves are radiated into the living body from each transducer 10a. At this time, the ultrasonic waves are apparently focused in a predetermined direction due to the transmission delay, whereby an ultrasonic beam is formed. Then, the reflected wave from the reflector on the ultrasonic beam is received by each transducer 10a. Here, when a side lobe occurs in a direction other than the ultrasonic beam (main beam), if a strong reflector exists, the reflected wave from the strong reflector is also received by each transducer 10a. . As described above, the reflected wave from this strong reflector becomes a cause of deterioration of the ultrasonic image as a pseudo echo.

When the received signal is output from each transducer 10a, each received signal is delayed by the delay circuit 14 and input to the distributor 12. The distributor 12 adds the received signals for each receiving group set by itself.
1 (A) and 1 (B) show the combined signal, and FIG.
Waveforms of the combined signals are shown in (A) and (B). In FIG. 2, the true echo has a large amplitude because the time phase and the phase match in each combined reception signal, while the pseudo echo has the time phase and the phase slightly deviated due to the above-described delay, and thus has a time axis. It spreads slightly in the direction. This is the same between the two synthetic signals, and the pseudo echo basically occurs at different time phases.

Returning to FIG. 1, in the present embodiment, the received signal (combined signal) as such a high frequency signal is converted into the ADC 16
After being converted into a digital signal in, the signal is input to the equalizer 18. The equalizer 18 performs processing for adjusting the amplitudes of the two combined signals to the smaller one. That is, FIG.
As shown in (C), the two combined signals are compared and the common part is extracted. As shown in FIG. 2C, it is understood that the pseudo echoes are canceled because their time phases do not coincide with each other and only the true echoes are extracted. In the past, such comparison was performed in the state of the envelope signal, but in the apparatus of the present embodiment, the comparison is performed in the state of the high frequency signal for simplification of the apparatus. That is, the delay circuit 14
It is premised that the phase of the pseudo echo does not match the phase of the true echo due to the delay due to.

Returning to FIG. 1, the combined signals having the smaller amplitudes arranged by the equalizer 18 are added by the adder 20 to form a new combined signal, which is output to a detection circuit in the subsequent stage. It FIG. 2D shows the combined signal after the addition. As shown in FIG. 2D, only the true echo is added to reduce the pseudo echo.

As described above, according to this embodiment, the structure can be remarkably simplified as compared with the conventional device, and the cost of the device can be reduced.

The equalizer 18 and the adder 20 shown by 100 in FIG. 1 can be configured by one ROM. Such a configuration is shown in FIG. RO is the two combined signals
It is given as two inputs A and B of M, and a value obtained by adding the numerical value of the input A or B having the smaller absolute value is stored as a table. Therefore, when an address is given as the inputs A and B, the operation result stored at the address is output from the ROM. With this configuration, the device can be further simplified. Of course, in the configuration of FIG. 1, a multiplier for multiplying the coefficient 2 may be provided as the adder 20.

In the above embodiment, two receiving groups are set, but of course, three or more receiving groups may be set. However, it is desirable to set two reception groups in order to simplify the circuit configuration as much as possible. As a modified example, comparison and addition can be performed as an analog signal without converting the combined signal into a digital signal.

[0025]

As described above, according to the present invention,
The side lobe signal can be easily reduced with a simple configuration.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram showing the waveform of each signal.

FIG. 3 is an explanatory diagram showing a configuration when the circuit 100 shown in FIG. 1 is a ROM.

[Explanation of symbols]

10 oscillator group, 12 distributor, 14 delay circuit, 18
Equalizer, 20 adder.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-60-31739 (JP, A) JP-A-62-186850 (JP, A) JP-A-2-209135 (JP, A) JP-A-4- 371154 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 8/00

Claims (2)

(57) [Claims] 1. An ultrasonic diagnostic apparatus comprising a transducer group including a plurality of transducers, wherein a delay circuit is connected to each transducer to electronically focus an ultrasonic beam. To a plurality of reception groups, a combination means for combining the delayed reception signals from the transducers for each of the reception groups to form a combined signal, and output from the combination means. Amplitude processing means for adjusting the amplitude of the combined signal of each reception group to the smaller one, and addition means for adding the combined signals of the reception groups with the adjusted amplitudes in a state before detection, Ultrasonic diagnostic equipment. 2. The apparatus according to claim 1, wherein an A / D converter is provided between the synthesizing means and the amplitude processing means, and the amplitude processing means and the adding means are a single table. An ultrasonic diagnostic apparatus characterized by being configured.