JPH05237115A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To realize an ultrasonic diagnostic device for improving the uniformity of resolution of an image at the time of a single focusing method, and improving the resolution extending over a whole range. CONSTITUTION:This device is provided with an input device 10 for executing designation of the single focusing method and a multi-stage focusing method, the setting of a focal position in each focusing method and the setting of an F-number, and a system controller 9 for generating a transmission signal by controlling a transmitting beam former 2, based on a set value set by the input device 10.

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,
In particular, it relates to an ultrasonic diagnostic apparatus with improved image resolution.

[0002]

2. Description of the Related Art An ultrasonic diagnostic apparatus irradiates a subject with ultrasonic waves from a transducer (ultrasound probe), and the transducer receives signals reflected from tissues and lesions in the subject. , A device for displaying a tomographic image formed by the reflection signal on a CRT and using it for diagnosis.

An image of a region of interest in the above-mentioned ultrasonic diagnostic apparatus is preferably an image with good resolution, that is, in a focused state, and a tomographic image is composed of reflection signals from portions having different depths. Therefore, it is desirable to obtain uniform resolution in the depth direction. The F number is generally used to represent this resolution. The F number is represented by the following equation.

F = transmission distance / transmission aperture (1) If the transmission distances are equal as is clear from the equation (1),
If the transmission aperture is large, the F number is small, and if the transmission aperture is small, the F number is large. Therefore, if the F number is small, the resolution is good, and if the F number is large, the resolution is bad,
It is not sensitive to changes in the transmission distance, that is, even for reflection sources having different depths, resolution is not significantly deteriorated and a uniform image can be obtained.

FIG. 4 is a diagram showing the relationship between the F number and the resolution.

In [0006] FIG, 1 is a resolution curve by transmitting a small F number that was focused to a point depth R _1, 2 is the resolution of a large F-number that has focused on the points of the same depth R ₁ It is a curve. As is clear from the figure, the resolution curve 1 of small F number has a large resolution value at the focus position R _1, but
The resolution drops sharply as the focus position R ₁ is left. Further, the resolution curve 2 of the large F number has a smaller resolution at the focal position R ₁ than the small F number, but the degree of decrease with respect to the change of the distance is small.

In transmission, there are a single focus method for selecting a focus position having a single depth and a multi-stage focus method for providing focus positions at a plurality of depths. The multi-stage focus method transmits waves several times compared to the single focus method to obtain one image. That is, the n-stage multi-stage focus is to transmit at least n waves to n focus positions.

[0008]

FIG. 5 is a diagram showing a resolution curve in the single focus method. In the figure, (a) is the resolution curve for the F number F _{1 at} the depth R ₁ , and (b) is the F number F for the depth R ₂ .
The resolution curve diagram in the case of ₂ and the (c) diagram are resolution curves in the case of the F number F _{3 at} the depth R ₃ . In each figure, the depths R _{1 to} R ₃ are as shown in the following equation.

R ₁ <R ₂ <R ₃ This figure shows the case where the F numbers F ₁ , F ₂ and F ₃ are made equal, and the resolution is obtained at the depth set at the focus position at each depth position. Is good, but the resolution becomes worse as the focus position is increased.

FIG. 6 shows the resolution curve in the multi-stage focusing method.
It is a figure which shows a line. Figure 7 shows the image of the multi-stage focus method.
In the figure which shows the state of image 3 on the surface and the data acquisition time
is there. In FIG. 6, the resolution in the case of multi-stage focus is a solid line.
It shows that the curve is represented. In the figure, R
₁, R₂, R₃Is the focus position and F₁, F₂, F₃Is it
It is the F number at each focus position. This multi-stage fo
The resolution in the circus method is the range shown by the solid line in the figure.
Is the point O the image on the screen in FIG.
Et al B₁F number to reach F₁, B₁To B₂Leading to
F number between₂, B₂F number beyond₃As
Each focus position R₁, R₂, R₃By the ultrasonic waves radiated on
It shows the state where the echo is displayed. (B) Multistage
Acquires one frame of image data in the focus method
In the figure which shows the time to₁Area (O
To B₁) Scan, then F₂Area (B₁~
B ₂) Scan, then F₃Area (B₂~)of
It shows the state of scanning. Therefore, this
In that case, it requires three times as long as the single focus method
It

In the conventional ultrasonic diagnostic apparatus, whether the single focus method or the multi-stage focus method is used,
Since the F number was not changed, the single focus method had a problem in the uniformity of the image, and the multi-step focus method should be able to obtain good resolution, but the characteristics were not fully utilized.

The present invention has been made in view of the above points, and an object thereof is to improve the uniformity of image resolution in the single focus method and to improve the resolution over the entire range in the multi-step focus method. It is to realize an ultrasonic diagnostic device.

[0013]

SUMMARY OF THE INVENTION The present invention for solving the above problems, in an ultrasonic diagnostic apparatus for performing transmission by the single focus method and the multi-step focus method, designates the single focus method and the multi-step focus method as a transmission mode, and An input device for setting a focus position and a large F number in the case of the focus method and a focus position of each stage and a small F number in the case of specifying the multi-stage focus method, and a transducer transmission by inputting a set value from the input device. And a system controller for controlling a wave transmission beamformer to generate a wave transmission signal for calculating a wave opening and supplying signals to a number of elements equal to the wave transmission numerical aperture. ..

[0014]

[Operation] The single focus method and the multi-stage focus method are selected by the input device. In the case of the single focus method, the focus position and the large F number are designated and input to the system controller. In the case of the multi-stage focus, the focus of each stage is selected. The position and the small F number are designated and input to the system controller, and the system controller calculates the transmission aperture and causes the transmission beamformer to generate transmission signals of the number of channels corresponding to the transmission aperture.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. In the figure, 1 is a trigger generator that generates a transmission trigger that serves as a reference for a transmission signal, 2 is a transmission beamformer that receives a trigger from the trigger generator 1 and converts it into a signal that forms a transmission sound ray, and 3 is a transmission beamformer. A power amplifier for amplifying the power of the transmission signal to supply the transmission signal to the transducer 4, a reception amplifier for amplifying the reception signal, and a TR switch for preventing the transmission signal from flowing into the reception circuit and being destroyed are provided. It is a transmission / reception circuit. Reference numeral 5 denotes a wave-receiving beamformer for phasing and adding multi-channel reception signals forming a sound ray into a serial signal, the output of which is subjected to processing such as amplification, detection, and filtering in a reception processing circuit 6. 7 is a DSC that converts an acoustic scanning signal into a television mode signal
(Digital Scan Converter), 8 is a CRT for displaying signals in the television mode of the DSC 7. The system controller 9 controls the transmitting beam former 2 and the receiving beam former 5 to convert them into signals of a desired format, and
Control such as supplying a sampling lock for AD conversion and DA conversion of the DSC 7 is performed. An input device 10 designates the single focus method and the double focus method, sets other operating conditions, and commands the start and stop of the operation of the apparatus.

Next, the operation of the apparatus of the embodiment constructed as described above will be explained. A switch for starting the operation of the input device 10 is turned on. The trigger generator 1 generates a trigger according to the clock from the system controller 9. This trigger is converted into a signal forming a desired sound ray in the transmission beamformer 2. When the single focus method is designated by the input device 10, the focus position and the F number are further set and input to the system controller 9. A large value is selected for the F number set at this time. The system controller 2 determines the number of transmission channels by calculating the transmission aperture from the set focus position and F number according to equation (1). The transmission beamformer 2 outputs a transmission signal under the control of the system controller 9, undergoes processing such as amplification by the transmission / reception circuit 3, and is transmitted from the transducer 4. The resolution in this case is as shown in FIG. In the figure, each curve has a different focus position R ₁ , R ₂ , R
₃ is a curve when ₃ is set and the F number is set to F ₂ .

In the multi-stage focusing method, the input device 10 sets a plurality of focal positions and a small F number and inputs the data to the system controller 9. The transmission beamformer 2 creates a transmission signal whose focal position is changed for each transmission a specified number of times. This transmission signal is composed of signals of the number of transmission channels that satisfy the transmission aperture calculated by the system controller 9 from the F number set by the input device 10 and each focus position.

The output of the transmitting beam former 2 is transmitted from the transducer 4 via the transmitting / receiving circuit 3. The number of elements transmitted at this time, that is, the transmission aperture is determined by the number of channels of the transmission signal formed by the transmission beam former 2. The resolution in this multi-stage focusing method is as shown by the solid line in FIG. In the figure, the first transmission is F number Fs at the focus position R ₁ , the second transmission is F number Fs at the focus position R ₂ , and the third transmission is F number Fs at the focus position R _3. Indicates the resolution due to the specified transmitted signal.

The echo signal reflected from the inside of the subject is received by the transducer 4, converted into an electric signal, and input to the reception beamformer 5 via the transmission / reception circuit 3. The receiving beamformer 5 phase-adds the received signals and outputs them as a serial signal. This output signal is received by the reception processing circuit 6
In, it is processed by detection, amplification, filtering, etc. and is input to the DSC 7.

The DSC 7 converts the input signal into a television mode signal and displays it on the CRT 8.

As described above, according to the present embodiment, the F number is set large in the single focus method by the input device 10 and set to the small F number in the multi-stage focus method. Since uniform resolution with little change is obtained over portions of different depths, high resolution is obtained at each focus position during multi-stage focusing, and in the image displayed as shown in FIG. 6, the portion with degraded resolution is cut off. An image with good resolution can be obtained.

[0023]

As described in detail above, according to the present invention, a uniform resolution characteristic can be obtained by the single focus method, and a high resolution can be obtained by the multi-stage focusing method, which has a large practical effect.

[Brief description of drawings]

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

FIG. 2 is a resolution curve diagram in the single focus method.

FIG. 3 is a resolution curve diagram in the multi-stage focusing method.

FIG. 4 is a diagram showing a relationship between F number and resolution.

FIG. 5 is a diagram showing a resolution curve in a single focus method.

FIG. 6 is a diagram showing a resolution curve in the multi-stage focusing method.

FIG. 7 is a diagram showing an image on a screen and a data acquisition time in the multi-stage focusing method.

[Explanation of symbols]

 2 Transmitting beamformer 4 Transducer 9 System controller 10 Input device

Claims (1)

[Claims] 1. An ultrasonic diagnostic apparatus that performs transmission by the single focus method and the multi-step focus method, specifies the single focus method and the multi-step focus method as a transmission mode, sets a focus position and a large F number in the case of the single focus method, and Input device (10) for setting the focus position and small F number of each stage when the multi-stage focus method is specified
And a transmission beamformer (2) for transmitting a transmission signal for calculating a transmission aperture of the transducer (4) by inputting a set value from the input device (10) and supplying a signal to a number of elements equal to the transmission aperture number. ) Is provided with a system controller (9) for controlling the ultrasonic diagnostic apparatus.