JPH03224550A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To eliminate the need of correcting the sensitivity by an amplifier, etc., of a receiving side and to prevent the rise of a noise level by varying a transmission driving condition at every focus and correcting the sensitivity in a transmitting side, in the case of executing a combination focus. CONSTITUTION:A transmitting wave number controller 20 outputs to a pulser 1 a control signal for setting a transmission driving pulse to transmitting one wave driving in a focus of a shallow part N in which S/N is sufficient, and setting it to transmitting two wave driving in a focus of a deep part F in which S/N is insufficient, therefore, when an ultrasonic probe 3 is driven by this tow wave driving pulse, transmitting power of an ultrasonic wave becomes large in the deep part F, and signal sensitivity rises. Accordingly, a sensitivity correction of an STC(Sensitivity Time Control) 22 is allowed to rise slowly in the depth direction, and also, a control signal from the transmitting wave number controller 20 is sent to a transmission correcting device 21, and sensitivity of TCF COMP is controlled. In such a way, the sensitivity correction by an amplifier, etc., of a receiving side becomes unnecessary, and a rise of a noise is prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention transmits and receives ultrasonic waves from an ultrasonic probe to a subject, detects echo signals obtained thereby, and transmits and receives ultrasonic waves to and from a subject. The present invention relates to an ultrasonic diagnostic apparatus that performs scan conversion and displays ultrasonic diagnostic information.

(Prior Art) In an ultrasonic diagnostic apparatus, an ultrasonic tomographic image is obtained as follows. In other words, in the case of linear electronic scanning using an array-type ultrasonic probe consisting of multiple ultrasonic transducers, one unit of ultrasonic transducers is excited. and transmits the ultrasonic beam.

For example, this method electronically shifts the transmission point of the ultrasonic beam by sequentially shifting the pitch by one oscillator and excitation in such a way that the position of each unit of element changes one after another. .

In order to focus the ultrasonic beam as a beam, the excitation timing of the excited ultrasonic transducers is shifted between those located at the center of the beam and those located at the sides. The reflected ultrasonic waves are focused using the phase difference between the sound waves generated by the ultrasonic transducer. The reflected ultrasonic waves are received by the same vibrator as the excited vibrator and converted into electrical signals, and the echo information from each transmitted and received wave is displayed as a tomographic image on a monitor or the like.

On the other hand, in the case of sector scanning, the excitation timing of each transducer is set so that the transmission direction of the ultrasound beam changes sequentially into a fan shape for each pulse of the ultrasound beam for one unit of excited ultrasound transducers. is changed according to the desired direction.

That is, according to this sector scan, transmission pulses having different delay times tl, t2...tn are manually applied from a pulse generator to each transducer of the probe via a transmission delay circuit and a balsa, and from each transducer. Delay time 11. t2...[
Ultrasonic waves are transmitted with a delay of n.

In other words, the wavefronts of these ultrasound waves are combined and an ultrasound beam is transmitted toward the subject. When the ultrasonic beam hits the subject, it is reflected and echo signals are received by each transducer of the probe with delay times tl, t2, . . . tn. Then, this echo signal is amplified by a receiving delay circuit, and the delay times r1, . r2...rn are given. These delayed signals are thus added, and a tomographic image of the subject is obtained on the monitor.

In addition to the above-mentioned linear and sector scans, there is also mechanical scanning in which a transducer is attached to a scanning mechanism and ultrasonic scanning is performed by moving the scanning mechanism.

Further, recent ultrasonic diagnostic apparatuses are provided with a sensitivity corrector for correcting the echo signal.

For example, when performing a sector scan as shown in FIG. 6(a), the resolution S/N is a constant value from the shallow part to the deep part as shown in FIG. 6(b), but the amplitude AP of the echo signal is Since the diagnostic region of the subject becomes weaker as it gets deeper in the depth direction, the sensitivity in the deeper regions deteriorates.

Therefore, conventionally, using the sensitivity corrector described above, (C)
As shown in the figure, the sensitivity, or GAIN, is adjusted so that it increases as the depth increases. This sensitivity corrector is
For example 5ent1b1ty TimeControl
(hereinafter referred to as 5TC) is conducted using VR.

In other words, the echo signal becomes weaker as the diagnostic site gets deeper, so the echo signal is
GAIN correction is performed by CVR, and the corrected echo signal can be adjusted to a constant amplitude as shown in (d).

However, since the sensitivity corrector uses an amplifier such as a transistor, the degree of amplification increases as the depth increases, and noise is also amplified.

For this reason, there is a problem in that the noise level increases as the depth increases, as shown in (d).

(Problems to be Solved by the Invention) On the other hand, in order to improve the resolution and S/N in shallow and deep areas, transmission combination focusing technology has come to be used. What is this transmission combination focus?
For example, if there are two stages of transmission, the shallow part N should be the first stage of transmission,
In deep F, the second stage of transmission is used. However, if the focus is placed on strong transmission, the transmission regulation power will be exceeded. For this reason, lowering the transmission voltage,
Alternatively, the focus is set to a unique position in order to satisfy the regulation value, but if this is done, the resolution and S/N deteriorate.

Furthermore, as shown in FIG. 7(b), the first stage of transmission and the second stage of transmission
Since the noise level differs between stages, reverse correction is performed using TCF COMP to correct this. Further, in order to improve the amplitude characteristic shown in (b), when the above-mentioned STC is used in combination as shown in (c), the amplitude characteristic shown in (d) can be obtained.

However, since STC is used, the noise level increases as the depth increases.

Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that can appropriately correct sensitivity without increasing the noise level from shallow to deep areas, obtain tomographic images of good image quality, and reduce the operating burden on the operator. It is about providing.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems and achieve the objects, the present invention takes the following measures. That is, the present invention generates a plurality of focuses using a transmitting means, transmits and receives ultrasound waves from an ultrasound probe to a subject, and detects the resulting echo signals and converts them into TV scans to obtain ultrasound diagnostic information. The ultrasonic diagnostic apparatus for displaying the image data is characterized by comprising a control means for controlling the pulse driving wave number for the transmitting means to be changed for each focus.

(Effects) By taking such measures, the following effects are achieved. When performing combination focus,
By changing the transmission drive conditions for each focus, the sensitivity can be corrected on the transmitting side, so there is no need to perform sensitivity correction using an amplifier or the like on the receiving side, so that the noise level does not increase.

In addition, in shallow areas where sensitivity is sufficient, the transmission power is weakened under the transmission drive conditions, and in deep areas where sensitivity is insufficient, the transmission power is increased under the transmission drive conditions, thereby improving only the deep sensitivity. It can also comply with regulations.

(Example) Fig. 1 is a schematic block diagram showing an embodiment of the ultrasonic diagnostic apparatus according to the present invention, Fig. 2 is a diagram for explaining the present invention in detail, and Fig. 3 is a transmission in the depth direction. FIG. 4 is a diagram showing the number of stages, FIG. 4 is a diagram showing transmission power with respect to the number of transmission stages, and FIG. 5 is a diagram for explaining sensitivity correction and S/N improvement of the present invention.

The ultrasonic diagnostic device is Pulsar 1. Channel selector 2. Ultrasonic probe 3. Preamplifier 4° reception delay circuit 5.
Adder 6. Reception detection section 7°FFT12. CFM13. D
It has an SC 14 and a monitor 15. The device also includes a transmission wave number controller 20 as a control means. It has a transmission sensitivity corrector 21.5TC22.

The pulser 1 inputs rate pulses delayed for each channel by a transmission delay circuit (not shown), and drives the ultrasound probe 3 via the channel selector 2 with these rate pulses.

The ultrasonic probe 3 has multiple channels (for example, 128 channels).
), and when only the channel selected by the channel selector 2 is driven by the pulser 1, an ultrasonic wave is generated and the ultrasonic wave is transmitted toward a subject (not shown).

The ultrasonic waves reflected from the object are received by the same transducer of the ultrasonic probe 3. Preamplifier 4 is
This received signal is amplified to a predetermined level. The reception delay circuit 5 applies a delay time to the reception signal of each channel inputted from the preamplifier 4 so as to restore the time delayed by the transmission delay circuit. The adder 6 is
The received signals of each channel delayed by the reception delay circuit 5 are added and combined.

The reception detection section 7 includes a reception filter 8. It has a sensitivity corrector 9° detection circuit 10, and inputs the received signal added from the adder 6. That is, the reception filter 8 extracts only the signal components necessary to obtain a tomographic image from the received signal. Further, the reception gain corrector 9 corrects the received signal according to the STC signal input from the 5TC 22.

Further, the reception gain corrector 9 corrects the reception signal according to the sensitivity correction signal manually input from the transmission sensitivity corrector 21. The sensitivity-corrected signal is then input to the detection circuit 10. The detection circuit 1o performs envelope detection on the sensitivity-corrected reception signal input from the reception gain corrector 9 in order to obtain a tomographic image, and outputs the obtained detection signal to the DSC 14.

The FFT 12 applies a range gate to a certain observation point on one scanning line using 1-point Doppler based on the received signal input from the adder 6, and frequency-analyzes the Doppler signal at this observation point to determine temporal changes in blood flow velocity. To obtain FFT data.

The CFM 13 (color flow mapping) has an MTI filter (moving number target indicator), etc., receives the received signal from the adder 6 at a plurality of times (for example, 10 times), and calculates a phase change. Accordingly, the average value 1 variance of the blood flow velocity and the power are calculated.

The DSC 14 has a frame memory, and the detection circuit 10
The detection signal for obtaining a tomographic image from FFT12 and F
The FT data and the CFM data from the CFM 13 are manually input, these data are written into the frame memory, and a signal scan-converted from an ultrasound scan to a TV scan is output to the monitor 15.

The monitor 15 obtains a tomographic image of the subject and displays a color flow mapping image in which FFTl indicating temporal changes in blood flow velocity, the direction of blood flow, and the magnitude of blood flow velocity are expressed in color.

Next, the features of this embodiment will be explained. First, this device adopts a two-stage transmission focus system, and focuses alternately on the shallow part N (Near) and the deep part F (Far) in the depth direction for each rate pulse. . The present embodiment is characterized in that it includes a transmission wave number controller 20 as a control means for controlling the pulse driving wave number for the pulser 1 to be changed for each focus.

Specifically, as shown in FIG. 2, the transmission wave number controller 20 sets the transmission drive pulse to 1-wave drive when the focus is on the shallow part N where the S/N is sufficient, and when the focus is on the deep part N where the S/N is insufficient.
At the focus, a control signal for driving two transmission waves is output to the pulser 3. As shown in FIG. 4, this transmission drive pulse has a power peak point at A in single-wave drive.
On the other hand, in the two-wave drive, the power peak point at B is larger than the peak point in the one-wave drive.

Therefore, if the ultrasound probe 1 is driven by such a two-wave drive pulse, the transmission power of the ultrasound becomes large in the deep part F. Along with this, the received signal becomes larger than the conventional received signal, so the signal sensitivity increases. therefore,
As shown in FIG. 5(C), the sensitivity correction of the 5TC22 may be gradually increased in the depth direction. Further, a control signal is sent from the transmission wave number controller 20 to the transmission corrector 21 to control the sensitivity of TCF COMP.

Then, the transmission sensitivity corrector 21 corrects the sensitivity of the preamplifier 4 and the sensitivity of the reception gain corrector 9.

That is, the overall signal amplitude is approximately constant from the shallow part N to the deep part F, as shown in FIG. 5(d).

Further, according to the transmission wave number drive, since the amplification degree is not changed in the depth direction as in 5TC22, the increase in noise due to the increase in the amplification degree disappears even in the deep part F as shown in the figure.

This makes it possible to improve the S/N ratio in deep areas. Further, as shown in FIG. 4, correction for the change in the band can be performed by inputting a control signal from the transmission wave number controller 20 to the reception filter 8.

According to this embodiment, when performing combination focusing, the sensitivity can be corrected on the transmitting side by changing the transmission drive conditions for each focus, so the sensitivity can be corrected using an amplifier on the receiving side. Since it is no longer necessary, there is no need to increase the noise level.

In addition, in shallow areas where sensitivity is sufficient, the transmission power is weakened under the transmission drive conditions, and in deep areas where sensitivity is insufficient, the transmission power is increased under the transmission drive conditions, thereby improving only the deep sensitivity. It can also comply with regulations. Furthermore, the S/N ratio in deep areas and the resolution in the azimuth direction can be improved.

It should be noted that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, when performing combination focusing, the sensitivity can be corrected on the transmitting side by changing the transmission drive conditions for each focus, so the sensitivity can be corrected using an amplifier or the like on the receiving side. Since there is no need to do this, there is no need to increase the noise level.

In addition, in shallow areas where sensitivity is sufficient, the transmission power is weakened under the transmission drive conditions, and in deep areas where sensitivity is insufficient, the transmission power is increased under the transmission drive conditions, thereby improving only the deep sensitivity. Compatible with regulations and S/N
Also, it is possible to provide an ultrasonic diagnostic apparatus that can improve azimuth resolution.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of the ultrasonic diagnostic apparatus according to the present invention, FIG. m2 is a diagram for explaining the present invention in detail, and FIG. FIG. 4 is a diagram showing the transmission power with respect to the number of transmission stages, and FIG. 5 is a diagram for explaining the sensitivity correction and S/N improvement of the present invention.
Figures 6 and 7 show sensitivity correction and S/
It is a figure for explaining N. 1...Pulsar 2...Channel selector 3.
...Ultrasonic probe, 4...Preamplifier, 5...Receiving delay circuit, 6...Adder, 7...Receiving detection unit, 8...
... Reception filter, 9... Adder, 10... Detection wave circuit, 12... FFT, 13... CFM, 14...
・DSC. 15... Monitor, 20... Transmission wave number controller,
22...5TC0

Claims (1)

[Claims] Ultrasonic diagnosis that generates multiple focuses using a transmitting means, transmits and receives ultrasonic waves from an ultrasound probe to a subject, detects the resulting echo signals, converts them into TV scans, and displays ultrasound diagnostic information. An ultrasonic diagnostic apparatus characterized in that the apparatus further comprises a control means for controlling the pulse driving wave number for the transmitting means to be changed for each focus.