JP2002345810A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic device which is always capable of obtaining the best sensitivity and resolution. SOLUTION: This ultrasonic diagnostic device is composed of a section of generating transmission signals that change the transmission signals or waveforms according to a specified depth of a subject 11 and a search unit 1 for transmitting ultrasonic waves according to the transmission signals, wherein either the transmission signal or waveform has central frequencies higher than the standard frequencies when the above specified depth is made proximal in distance while either the transmission signal or waveform has central frequencies lower than the standard frequencies when the above specified depth is made distal in distance.

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 using a coded transmission / reception system, and more particularly to an ultrasonic diagnostic apparatus capable of always obtaining the best sensitivity and resolution.

[0002]

2. Description of the Related Art In a conventional medical ultrasonic diagnostic apparatus, attempts have been made to improve the sensitivity and resolution by narrowing the width of a transmission pulse and increasing the amplitude, but the circuit scale and the size of the probe have to be improved. There is a limit to this method due to the limitation of withstand voltage and the like, and an ultrasonic diagnostic apparatus of a coded transmission / reception method has been conceived there.

[0003] The ultrasonic diagnostic apparatus of the coded transmission / reception system encodes a transmission waveform to form a transmission waveform having a long time, thereby transmitting more power to improve the sensitivity. By performing signal processing, the resolution can be improved.

[0004] As typical coded transmission / reception methods, those using a chirp waveform and those using a complementary code are known. The transmission code or transmission waveform is changed between a B mode and a color flow mode, or a diagnostic mode such as a Doppler mode. It is common.

For example, according to JP-A-1-303135, a complementary sequence is used for the B mode, and M is used for the Doppler mode.
A series is used. According to Japanese Patent Application Laid-Open No. 2-142550, a chirp waveform is used in the B mode, and a simple burst signal is used in the Doppler mode.

[0006]

However, in the conventional ultrasonic diagnostic apparatus, there is a problem that a long transmission code is used to deteriorate the resolution at a short distance depending on the setting of the zoom mode and the depth of the living body to be diagnosed. Was. Further, the phased array probe has a problem that the sensitivity and the resolution vary depending on the deflection angle, and a uniform image cannot be obtained.

The present invention has been made to solve such a conventional problem, and provides an ultrasonic diagnostic apparatus capable of always obtaining the best sensitivity and resolution.

[0008]

According to an ultrasonic diagnostic apparatus of the present invention, a transmission signal generator for generating a transmission signal for changing a transmission code or a transmission waveform according to a set depth of a living body to be diagnosed; And a probe for transmitting ultrasonic waves.

With this configuration, the resolution can be changed by changing the transmission code or the transmission waveform according to the set depth, and the best sensitivity and resolution can always be obtained.

The transmission signal is a transmission code or transmission waveform having a center frequency higher than a reference frequency when the set depth is set to a short distance, and a transmission code having a center frequency lower than the reference frequency when the set depth is set to a long distance. It was configured to be a sign or a transmission waveform.

With this configuration, when the set depth is short, a high-frequency component with high resolution is used, and when the set depth is long, a low-frequency component with high sensitivity is used. Sensitivity and resolution can be obtained.

The transmission signal is a transmission code or transmission waveform having a short time length when the set depth is set to a short distance, and a transmission code or transmission waveform having a long time length when the set depth is set to a long distance. Was adopted.

With this configuration, when the set depth is short, a short transmission code or transmission waveform is used to increase the resolution at a short distance, and at a long distance, a long transmission code or transmission waveform is used to increase the sensitivity. Diagnosis according to the target can be performed, and the best sensitivity and resolution can always be obtained.

An ultrasonic diagnostic apparatus according to the present invention includes a transmission signal generator for generating a transmission signal having a predetermined transmission code or transmission waveform, a probe for transmitting an ultrasonic wave based on the transmission signal, And a reception signal processing unit that processes a reception signal obtained by transmitting the ultrasonic wave according to the reflection depth.

[0015] With this configuration, the diagnosis according to the diagnosis target of the living body to be diagnosed is performed by the reception signal processing according to the reflection depth of the reception signal, and the best sensitivity and resolution can always be obtained.

The reception signal processing section is configured to perform processing for extracting only a high-frequency component of a transmission waveform or a transmission code when the reflection depth of the reception signal is short.

With this configuration, when the set depth is short, a high-frequency component with high resolution is used, and when the set depth is long, a low-frequency component with high sensitivity is used. Sensitivity and resolution can be obtained.

An ultrasonic diagnostic apparatus according to the present invention comprises: a transmission signal generator for generating a transmission signal for changing a transmission code or a transmission waveform in accordance with a transmission direction of an ultrasonic wave transmitted to a living body to be diagnosed; And a probe for transmitting a sound wave.

With this configuration, it is possible to obtain the optimum transmission code or transmission waveform in the deflection direction and always obtain the best sensitivity and resolution.

The transmission signal is a transmission code or a transmission waveform having a center frequency higher than a reference frequency when the deflection angle of the transmitted ultrasonic wave is small, and a transmission code having a center frequency lower than the reference frequency when the deflection angle is large. Alternatively, the transmission waveform is used.

With this configuration, when the deflection angle of the apparent aperture is large and the deflection angle is small, the resolution is improved by using the high frequency component. When the deflection angle of the apparent aperture is small and the deflection angle is large, the sensitivity can be improved by using the low frequency component. .

The transmission signal has a transmission code or transmission waveform having a short time length when the deflection angle of the transmitted ultrasonic wave is small, and a transmission code or transmission waveform having a long time length when the deflection angle is large. Configuration.

According to this configuration, when the deflection angle with a large apparent aperture is small, the resolution is improved by using a short transmission code or transmission waveform, and when the deflection angle with a small apparent aperture is large, the resolution is improved by using a long transmission code or transmission waveform. Sensitivity can be improved.

The transmission signal has a configuration in which the transmission waveform is a chirp waveform.

According to this configuration, an ultrasonic wave having power and a high reflection effect can be obtained, and the best sensitivity and resolution can always be obtained.

The chirp waveform is a binary or ternary chirp waveform.

With this configuration, it is possible to obtain a simple circuit configuration and always obtain the best sensitivity and resolution.

The transmission signal has a configuration in which the transmission code has a complementary sequence.

According to this configuration, an ultrasonic wave having power and a high reflection effect can be used, and the best sensitivity and resolution can always be obtained.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

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

As shown in FIG. 1, the ultrasonic diagnostic apparatus according to the first embodiment of the present invention uses a coded transmission / reception system, and a transmission signal generator 3 transmits, for example, a coded transmission signal of a chirp signal. Is generated, and the transmission unit 2 amplifies the transmission signal generated by the transmission signal generation unit 3 and drives the probe 1. In the electronic scanning or deflection type ultrasonic diagnostic apparatus, a predetermined delay is given to each transducer so that the ultrasonic waves converge and deflect in a predetermined position and direction.

The probe 1 converts a transmission signal transmitted from the transmission unit 2 into an ultrasonic signal and transmits the ultrasonic signal to the living body 11 to be diagnosed (see FIG. 2 described later). It receives the signal reflected by the organ and converts it into an electric signal. The receiving unit 4 amplifies the received signal converted from the ultrasonic signal into the electric signal by the probe 1. In an electronic scanning or deflection type ultrasonic diagnostic apparatus, a predetermined delay is given to each transducer so that an ultrasonic wave reflected at a predetermined position is appropriately amplified, and a reception signal is added. The reception signal processing unit 5 starts the reception signal processing of the coded transmission / reception method on the reception signal,
Performs various signal processing such as depth-dependent filtering, gain adjustment, and detection.

The scan converter 6 converts the signal processed by the received signal processor 5 into a television image signal and displays it on the monitor 7. The control unit 8 controls the entire ultrasonic diagnostic apparatus.

Next, the first embodiment of the present invention constructed as described above will be described.
The operation of the ultrasonic diagnostic apparatus according to the embodiment will be described.

FIG. 2 shows a monitor screen displayed on the monitor 7, FIG. 2 (a) shows a monitor screen A when the set depth is reduced, and FIG. 2 (b) shows a monitor screen A when the set depth is increased. 2C shows a monitor screen C when the zoom mode is set, and FIG. 2D shows an ultrasonic signal transmitted from the probe 1 into the living body 11 to be diagnosed. The situation at the time is shown.

As shown in FIG. 2D, in this ultrasonic diagnostic apparatus, the depth of the subject 11 from the probe 1 provided on the probe can be set to about 2 cm to 30 cm. It is possible to monitor the field of view when the set depth is shallow, the field of view when the set depth is deep, and the field of view in the zoom mode.

As shown in the monitor screen A of FIG.
When the set depth is made shallow, the organ 12A which is relatively shallow from the skin is displayed larger, and the monitor screen B shown in FIG.
As shown in FIG. 5, when the set depth is increased, the organ 12A located relatively deep from the skin and the organ 12B located deep
A large area is displayed up to. Further, as shown in a monitor screen C in FIG. 2C, the deep organ 12B can be displayed in an enlarged manner by setting the zoom mode.

In the three modes shown in FIG. 2, if the transmission and reception are performed by the coded transmission and reception method using the same transmission code or transmission waveform, the vertical resolution deteriorates when the set depth is reduced or in the zoom mode. However, when the set depth is deepened or when the zoom mode is a deep part, the sensitivity is insufficient.

Therefore, in the ultrasonic diagnostic apparatus of the present invention, when the set depth is made shallow, the resolution becomes important by enlarging and displaying a narrow area. Therefore, the transmission code or the transmission waveform is changed according to the set depth. A wideband transmission code or waveform containing many high frequency components that can provide high resolution is used. In this case, a transmission code or a transmission waveform which is short in time can be used.

On the other hand, when the set depth is increased, attenuation due to the living body to be diagnosed is large and sensitivity improvement is important. Therefore, a transmission code or a transmission waveform containing many low frequency components with small attenuation is used. Further, in this case, a transmission code or a transmission waveform that is long in time can be used.

In the zoom mode, sensitivity and resolution are both important, and a transmission code or a transmission waveform in which both the frequency component and the time length are balanced are used.

Further, the ultrasonic diagnostic apparatus of the present invention changes not only the transmission code or transmission waveform but also the reception signal processing according to the reflection depth of the reception signal. The received signal reflected from the living body 11 to be diagnosed is attenuated depending on the frequency, and the signal reflected at a deeper portion is more attenuated at higher frequencies. Therefore, sensitivity can be improved by performing signal processing for efficiently extracting low frequency components. Conversely, since the signal reflected from the shallow portion includes the high-frequency component without being attenuated, the resolution can be increased by using these components.

Therefore, when imaging a deep part, signal processing for increasing sensitivity such as a matched filter is performed, and for imaging a shallow part, signal processing for increasing resolution such as a reverse filter is performed.

As described above, by performing such an operation,
The best sensitivity and resolution can always be obtained at the set depth.

Next, an ultrasonic diagnostic apparatus according to a second embodiment of the present invention will be described.

Since the ultrasonic diagnostic apparatus according to the second embodiment of the present invention has the same configuration as the ultrasonic diagnostic apparatus according to the first embodiment, the operation will be described below.

FIG. 3 shows the field of view of the ultrasonic diagnostic apparatus, FIG. 3 (a) shows the field of view of the convex type ultrasonic diagnostic apparatus, and FIG. 3 (b) shows the field of view of the phased array type ultrasonic diagnostic apparatus. Is shown.

As shown in FIG. 3A, in the convex type ultrasonic diagnostic apparatus, a transducer group 15 is used for the probe 1 (see FIG. 1), and the transducer group 15 is used for actual transmission and reception. The scanning line is moved by switching the plurality of sub-vibrators 15a. Therefore, the aperture as viewed from the reflection point on the scanning line is the same for both the scanning line 13A and the scanning line 13B.

On the other hand, as shown in FIG. 3B, in the phased array type ultrasonic diagnostic apparatus, the transducer group 16 is used for the probe 1 (see FIG. 1), and the amount of delay given to the transmission / reception signal is varied. The transmission / reception direction of the ultrasonic wave is changed by changing for each of the plurality of sub-vibrators 16a of the child group 16.
Therefore, the scanning line 13C at a position away from the center of the image
The opening viewed from the upper reflection point is narrow, and the opening viewed from the reflection point on the scanning line 13D near the center of the image is wide.

This situation appears as a difference in brightness in the image. As the end of the image is approached, the direction of the scanning line 13C becomes dark, and the direction of the scanning line 13D near the center of the image becomes bright.

In the conventional ultrasonic diagnostic apparatus, this problem is corrected by changing the gain of the received signal. In the ultrasonic diagnostic apparatus of the present invention, the transmission code is changed depending on the scanning direction. In the vicinity of the center of the image, a wideband transmission code or transmission waveform containing many high frequency components that can obtain higher resolution than sensitivity is used. In this case, a transmission code or a transmission waveform which is short in time can be used. On the other hand, at the end of the image, a transmission code or transmission waveform containing many low frequency components with little attenuation or a transmission code or transmission waveform that is long in time is used. By doing so, a uniform image having no difference in brightness can be obtained.

[0053]

As described above, according to the present invention,
An ultrasonic diagnostic apparatus that can always obtain the best sensitivity and resolution can be realized.

[Brief description of the drawings]

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

2 shows a diagram of a monitor screen displayed on a monitor, and FIG.
(A) is a diagram of a monitor screen when the set depth is reduced,
2B is a diagram of the monitor screen when the set depth is increased, FIG. 2C is a diagram of the monitor screen when the zoom mode is set, and FIG. Diagram showing the situation when an ultrasonic signal is transmitted into a living body

FIG. 3 shows a view of a field of view of the ultrasonic diagnostic apparatus, and FIG.
Fig. 3 is a view of the field of view of a convex type ultrasonic diagnostic apparatus, and Fig. 3
(B) is a view of a field of view of a phased array type ultrasonic diagnostic apparatus.

[Explanation of symbols]

 Reference Signs List 1 probe 2 transmission unit 3 transmission signal generation unit 4 reception unit 5 reception signal processing unit 6 scan conversion unit 7 monitor 8 control unit 11 subject to be diagnosed 12 organ 13 scan line 15, 16 transducer group 15a, 16a sub transducer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Fukukita 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa F-term (reference) in Matsushita Communication Industrial Co., Ltd. 4C301 AA02 EE01 EE06 HH01 HH07 HH43 HH60

Claims (11)

[Claims] 1. A transmission signal generating section for generating a transmission signal for changing a transmission code or a transmission waveform according to a set depth of a living body to be diagnosed, and a probe for transmitting an ultrasonic wave based on the transmission signal. An ultrasonic diagnostic apparatus characterized by the above-mentioned. 2. The transmission signal has a transmission code or a transmission waveform having a center frequency higher than a reference frequency when the set depth is set to a short distance, and a center frequency lower than the reference frequency when the set depth is set to a long distance. The ultrasonic diagnostic apparatus according to claim 1, wherein the transmission code or the transmission waveform is used. 3. The transmission signal is a transmission code or a transmission waveform having a short time length when the set depth is set to a short distance, or a transmission code or a transmission code having a long time length when the set depth is set to a long distance. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus has a transmission waveform. 4. A transmission signal generator for generating a transmission signal having a predetermined transmission code or transmission waveform, a probe for transmitting an ultrasonic wave by the transmission signal, and a reflection depth of the transmission signal, An ultrasonic diagnostic apparatus comprising: a reception signal processing unit that processes a reception signal obtained by transmitting an ultrasonic wave. 5. The reception signal processing unit according to claim 4, wherein the reception signal processing unit performs processing for extracting only a high-frequency component of a transmission waveform or a transmission code when the reflection depth of the reception signal is a short distance. Ultrasound diagnostic device. 6. A transmission signal generating section for generating a transmission signal for changing a transmission code or a transmission waveform according to a transmission direction of an ultrasonic wave transmitted to a living body to be diagnosed, and a probe for transmitting an ultrasonic wave based on the transmission signal. An ultrasonic diagnostic apparatus comprising: 7. The transmission signal has a transmission code or transmission waveform having a center frequency higher than a reference frequency when the deflection angle of the transmitted ultrasonic wave is small, and has a center frequency lower than the reference frequency when the deflection angle is large. The ultrasonic diagnostic apparatus according to claim 6, wherein the transmission code or the transmission waveform is used. 8. A transmission code or a transmission waveform having a short temporal length when the deflection angle of the transmitted ultrasonic wave is small, and a transmission code or transmission waveform having a long temporal length when the deflection angle is large. The ultrasonic diagnostic apparatus according to claim 6, wherein the ultrasonic diagnostic apparatus has a waveform. 9. The ultrasonic diagnostic apparatus according to claim 1, wherein the transmission signal has the transmission waveform as a chirp waveform. 10. The chirp waveform is binary or tri-level.
The ultrasonic diagnostic apparatus according to claim 9, wherein the chirp waveform has a value. 11. The ultrasonic diagnostic apparatus according to claim 1, wherein the transmission signal has the transmission code as a complementary sequence.