JPH0866394A - Nonlinear effect estimating method using rti method and nonlinear effect estimating device - Google Patents

Abstract

PURPOSE: To estimate a wave-transmitting level at which a tissue from a test body begins to heat, by performing a transmitting wave focusing on one point inside a test body and the transmitting wave not focusing on it respectively and mutually comparing the echo levels corresponding to respective transmitting waves and estimating attenuation due to nonlinear effect of the focus. CONSTITUTION: A phase of high frequency pulse generated by a pulse generator 1 is adjusted by means of a wave-transmitting beam former 2 and this wave-transmitting pulse is transmitted to an ultrasonic probe 4 through a transmit-receiving circuit 3, and an ultrasonic is transmitted with focusing one point P inside of the test body 5. And an echo generated at the focus P is received at the ultrasonic probe 4 and transmitted to a wave-receiving beam former 7 through the transmit-receiving circuit 3, and inputted to a B mode signal processing part 8 as a main output after arranging and adjusting the wave here, and an ordinary B mode image display is performed on the first display part 11a. Furthermore, the echo generated in a backward scattering region & of the focus P is inputted to a RTI observation system 9 as a sub-output and the RTI echo image of the face including the focus P is displayed on the second display part 11b.

Description

Detailed Description of the Invention

[0001]

The present invention relates to the RTI method (Reflex).
The present invention relates to a non-linear action estimation method and a non-linear action estimation device using a transmission imaging method (reflection transmission method).

[0002]

2. Description of the Related Art In recent years, ultrasonic diagnostic equipment has come to be used in the field of medical diagnosis. An ultrasonic diagnostic apparatus transmits ultrasonic waves from an ultrasonic probe to a subject, receives echoes generated at boundaries of different acoustic impedances of the subject with the ultrasonic probe, performs signal processing, and performs an echo image. Is displayed on the display device.

[0003]

Conventionally, an ultrasonic diagnostic apparatus has been compared with an X-ray diagnostic apparatus that emits X-rays harmful to the human body.
It was said to be an intrinsically safe diagnostic device. However, in recent years, a design with a high transmission level has been adopted to improve the detection capability, and as a result, it has been found that heat may be generated inside the tissue of the subject, which may have a harmful effect. It was Therefore, it has become necessary to know in advance the wave transmission level at which sufficient heat is generated inside the subject. If it is possible to know the transmission level that causes such heat generation at the same time in advance or during the execution of image acquisition, it is possible to raise the transmission level of ultrasonic waves to a limit level that causes such heat generation or danger due to it. It is possible to see an echo image of tissue at a further distance.

The present invention has been made in view of the above problems, and is a nonlinear action estimating method and a nonlinear method using the RTI method capable of estimating the transmission level at which heat is generated in the tissue of the subject. It is intended to provide an action estimation device. Another object of the present invention is to provide a non-linear action estimation method and a non-linear action estimation apparatus using the RTI method, which can reflect the ultrasonic wave transmission level determined by the RTI method in a normal ultrasonic image display. Is intended.

[0005]

A first aspect of the invention for solving the above-mentioned problems is to transmit a wave focused on one point in a subject, and to adjust the wave either not to the one point or to the one point. And the echo level corresponding to each of the waves returning from the echo source behind the focal point is compared, and based on the comparison result, the The feature is that the attenuation due to the non-linear action at the focal point is estimated.

In this case, when a normal echo image is also displayed together with the display of the estimated value of the non-linear effect estimated by the echo level from the rear echo source, the main transmission wave is simultaneously transmitted in parallel during image acquisition. It is possible to easily detect the transmission level where the attenuation due to the non-linear effect near the focal point becomes noticeable, and to set the transmission level to the level just before the attenuation becomes noticeable. Is preferred.

Furthermore, it is preferable that the normal echo image is a B-mode image, an M-mode image, a pulse Doppler image, or an MTI image in order to determine an optimum transmission level that does not cause attenuation due to a non-linear effect.

A second invention for solving the above-mentioned problem is a step of transmitting a wave by focusing on one point in the subject, and not adjusting the point or reducing the degree of adjusting the point. Means for performing time-divisionally performing the step of transmitting by means of, and means for receiving the echo levels corresponding to the respective waves returned from the echo source behind the focal point, comparing the levels, and comparing the echo levels. And a means for estimating attenuation due to a non-linear action at the focal point when the focal point is focused on the basis of the result.

In this case, a means for displaying an ordinary echo image together with the display of the estimated value of the non-linear effect estimated by the echo level from the rear echo source should be provided simultaneously during image acquisition. The transmission level at which the attenuation due to the non-linear effect near the focus of the main transmission becomes significant can be easily detected, and the transmission level can be set to the level immediately before the attenuation becomes significant. Is preferable for optimizing

Further, the normal echo image is preferably a B-mode image, an M-mode image, a pulsed Doppler image or an MTI image in order to determine an optimum transmission level that does not cause attenuation due to a non-linear effect.

A third invention for solving the above-mentioned problem is to transmit a wave at a certain level focusing on one point in the subject,
A case in which the transmission level is changed and the echo levels corresponding to the respective transmission waves returning from the echo source behind the focus are compared, and one point is focused based on the comparison result. It is characterized in that the attenuation due to the non-linear action at the focus is estimated.

In this case, when a normal echo image is also displayed together with the display of the estimated value of the non-linear effect estimated by the echo level from the rear echo source, the main transmission wave is concurrently transmitted during image acquisition. It is possible to easily detect the transmission level where the attenuation due to the non-linear effect near the focal point becomes noticeable, and to set the transmission level to the level just before the attenuation becomes noticeable. Is preferred.

Furthermore, it is preferable that the normal echo image is a B-mode image, an M-mode image, a pulse Doppler image, or an MTI image in order to determine an optimum transmission level that does not cause attenuation due to a non-linear effect.

A fourth invention for solving the above-mentioned problem is time-sharing of a step of transmitting a wave at a certain level by focusing on one point in the subject and a step of changing the wave transmission level and transmitting the wave. And means for receiving echoes returned from the echo source behind the focus and comparing the echo levels with each other, and focusing on one point based on the comparison result. In this case, a means for estimating the attenuation due to the non-linear effect at the focal point is provided.

In this case, a means for displaying an ordinary echo image together with the display of the estimated value of the non-linear effect estimated by the echo level from the rear echo source is provided at the same time during image acquisition. The transmission level at which the attenuation due to the non-linear effect near the focus of the main transmission becomes significant can be easily detected, and the transmission level can be set to the level immediately before the attenuation becomes significant. Is preferable for optimizing

Furthermore, it is preferable that the normal echo image is a B-mode image, an M-mode image, a pulse Doppler image, or an MTI image in order to determine an optimum transmission level that does not cause attenuation due to a non-linear effect.

[0017]

[Action]

(First invention) For the purpose of acquiring a main image, a main transmission wave focused on one point in a subject and a reference wave transmission unfocused or less focused Then, the echo having the point behind the focal point for each of them as an echo source is received and compared, and the difference in level between the two is detected. When the echo level for the focused transmission wave is sufficiently lower than the echo level for the non-focused or less-focused transmission wave, a nonlinear effect becomes prominent at the focal point, and the transmitted ultrasonic wave is transmitted. It means that energy is dissipated, which means that it is close to the target heat generation safety limit, or sufficiently exceeds it. That is, this corresponds to the case where the focused transmission causes a darker image from the rear echo source.

The fact that the RTI image from the rear echo source becomes darker when the focus is adjusted indicates that attenuation of the transmitted ultrasonic wave begins to occur due to the non-linear effect, and at a transmission level higher than this level. It is shown that the transmission causes sufficient heat generation in the tissue due to the nonlinearity. In this way, it is possible to estimate the transmission level at which heat is generated based on the nonlinearity of the tissue of the subject. Therefore, the darkness of the RTI image of the subject means that, for example, when performing the normal B-mode display, it is not possible to transmit at a higher transmission level. Conversely speaking, if ultrasonic waves are transmitted at this transmission level, it will be possible to transmit at a barely sufficient level without generating heat due to tissue non-linearity, and the device will reach the limit sensitivity. It can be set and you can see the echo image of the tissue at a far distance.
In this way, according to the present invention, it is possible to estimate the transmission level at which heat is generated in the tissue of the subject.

Further, by combining the echo image display from the rear echo source and the normal ultrasonic image display, an ultrasonic image for the normal ultrasonic image display based on the result of the echo image display from the rear echo source is combined. The sound wave transmission level can be optimally set.

In this case, if the normal echo image is a B-mode image, an M-mode image, a pulsed Doppler image, or an MTI image, an optimum transmission level that does not cause attenuation due to a non-linear action is applied to these images. It can be decided conveniently.

(Second invention) From the transmitting means to the inside of the subject 1
A main transmission wave focused on a point and a reference wave transmission wave that is not or is not focused are time-divisionally executed by the execution means, and a point behind the focus of each is used as an echo source. The echo is received and compared by the comparison means, and the difference in level between the two is detected. If the echo level for the focused transmission is sufficiently lower than the echo level for the non-focused or less focused transmission, a non-linear effect will be noticeable at the focus,
It means that the transmitted ultrasonic wave energy is dissipated, which means that it is close to the target exothermic safety limit, or sufficiently exceeds it. That is, this corresponds to the case where the focused transmission causes a darker image from the rear echo source.

The fact that the RTI image from the rear echo source becomes darker when the focus is adjusted means that attenuation of the transmitted ultrasonic wave begins to occur due to the non-linear effect, and at a transmission level higher than this level. It is shown that the transmission causes sufficient heat generation in the tissue due to the nonlinearity. In this way, it is possible to estimate the transmission level at which heat is generated based on the nonlinearity of the tissue of the subject by the estimation means. Therefore, the darkness of the RTI image of the subject means that, for example, when performing the normal B-mode display, it is not possible to transmit at a higher transmission level. Conversely speaking, if ultrasonic waves are transmitted at this transmission level, it will be possible to transmit at a barely sufficient level without generating heat due to tissue non-linearity, and the device will reach the limit sensitivity. It can be set and you can see the echo image of the tissue at a far distance. In this way, according to the present invention, it is possible to estimate the transmission level at which heat is generated in the tissue of the subject.

Further, by combining the echo image display from the rear echo source and the normal ultrasonic image display, the ultrasonic image for the normal ultrasonic image display based on the result of the echo image display from the rear echo source is combined. The sound wave transmission level can be optimally set.

In this case, if the normal echo image is a B-mode image, an M-mode image, a pulsed Doppler image, or an MTI image, an optimum transmission level that does not cause attenuation due to a non-linear action is applied to these images. It can be decided conveniently.

(Third Invention) As in the above first and second inventions, regardless of whether or not a focus is focused on the inside of the object, only the focus level of the transmitted wave is changed and only the level of the transmitted wave is changed. To do. Depending on the result of the change, if the echo level from the back echo source of the focus also changes in response to the change of the transmission level, the energy dissipation due to the non-linear effect in the focus will not be significant. However, when the change of the echo level is slower than the change of the transmission level, that is, when the echo level is compressed, it indicates that the focus has a sufficient level dissipation due to the non-linear effect.

This means that the attenuation of the transmitted ultrasonic wave due to the non-linear effect has begun to occur, and when the wave is transmitted at a wave transmission level higher than this, sufficient heat generation due to the non-linearity occurs in the tissue. Is shown. In this way, it is possible to estimate the transmission level at which heat is generated based on the nonlinearity of the tissue of the subject. Therefore, the level change of the RTI image of the subject being gradual means that, for example, when performing the normal B-mode display, it is not possible to transmit at a transmission level higher than this. Conversely speaking, if ultrasonic waves are transmitted at this transmission level, it will be possible to transmit at a barely sufficient level without generating heat due to tissue non-linearity, and the device will reach the limit sensitivity. It can be set and you can see the echo image of the tissue at a far distance. In this way, according to the present invention, it is possible to estimate the transmission level at which heat is generated in the tissue of the subject.

Further, by combining the echo image display from the rear echo source and the normal ultrasonic image display, the ultrasonic image for the normal ultrasonic image display based on the result of the echo image display from the rear echo source is combined. The sound wave transmission level can be optimally set.

In this case, if the normal echo image is a B-mode image, an M-mode image, a pulsed Doppler image, or an MTI image, an optimum transmission level that does not cause attenuation due to a non-linear action is applied to these images. It can be decided conveniently.

(Fourth Invention) As in the first and second inventions, regardless of whether or not a focus is focused on the inside of the subject, only the transmission level is executed while the focused transmission is still performed. Change by means. Depending on the result of the change, if the echo level from the back echo source of the focus also changes in response to the change of the transmission level, the energy dissipation due to the non-linear effect in the focus will not be significant. However, if the comparison means detects that the change in the echo level is slower than the change in the transmission level, that is, is compressed, the focus has sufficient level dissipation due to the non-linear effect. Is shown.

This indicates that the attenuation of the transmitted ultrasonic wave due to the non-linear effect has begun to occur, and when the wave is transmitted at a wave transmission level higher than this, heat is sufficiently generated in the tissue due to the non-linearity. Is shown. In this way, it is possible to estimate the transmission level at which heat is generated based on the nonlinearity of the tissue of the subject. Therefore, the level change of the RTI image of the subject being gradual means that, for example, when performing the normal B-mode display, it is not possible to transmit at a transmission level higher than this. Conversely speaking, if ultrasonic waves are transmitted at this transmission level, it will be possible to transmit at a barely sufficient level without generating heat due to tissue non-linearity, and the device will reach the limit sensitivity. It can be set and you can see the echo image of the tissue at a far distance. In this way, according to the present invention, the transmission level at which heat is generated in the tissue of the subject can be estimated by the estimation means.

Further, by combining the echo image display from the rear echo source and the normal ultrasonic image display, an ultrasonic image for normal ultrasonic image display based on the result of the echo image display from the rear echo source is combined. The sound wave transmission level can be optimally set.

In this case, if the normal echo image is a B-mode image, an M-mode image, a pulsed Doppler image, or an MTI image, an optimum transmission level that does not cause attenuation due to a non-linear effect is applied to these images. It can be decided conveniently.

[0033]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are flowcharts showing the principle of the method of the present invention, and FIG. 3 is a configuration block diagram showing an embodiment of the present invention. The first method of the present invention is, as shown in FIG. 1, a transmission wave focused on one point in the subject and a transmission wave which is not focused on the one point or is less focused on the one point. Wave (S1), the echo levels corresponding to the respective transmitted waves returning from the echo source behind the focus are compared (S2), and one point is focused based on the comparison result. The feature is that the attenuation due to the non-linear action at the focus is estimated (S3).

Here, when the level of the echo relating to the focused transmission wave is sufficiently lower than the echo level relating to the non-matching or less-matching transmission wave, a non-linear effect remarkably appears at the focus. , It means that the transmitted ultrasonic wave energy is dissipated, which means that it is close to the target exothermic safety limit or sufficiently exceeds it.

In the second method of the present invention, as shown in FIG. 2, a wave at a certain level focused on one point in the subject and a wave with a changed wave level are transmitted. Execute (S
1) Comparing the echo levels corresponding to the respective transmitted waves returning from the echo source behind the focus (S2), and based on the comparison result, due to the non-linear effect in the focus when one point is focused. Estimate attenuation (S3)
It is characterized by that.

Here, when the level difference between the echo level related to the planned transmission level and the echo level related to the transmission level changed is sufficiently smaller than the transmission level difference. , Means that a nonlinear effect appears remarkably at the focal point and the transmitted ultrasonic wave energy is dissipated, which means that the target heat generation safety limit is close to or sufficiently exceeded. To do.

In FIG. 3, reference numeral 1 is a pulse generator for generating a high frequency pulse, and 2 is a transmission beam former for receiving the output of the pulse generator 1 and adjusting the phase of an ultrasonic pulse for transmission. A transmitting / receiving circuit 3 receives the output of the transmitting beamformer 2 and switches between transmitting and receiving waves, and 4 is connected to the transmitting / receiving circuit 3 to transmit an ultrasonic wave toward a subject 5 and This is an ultrasonic probe that receives the echo from the specimen 5. The number of elements of the ultrasonic probe 4 is, for example, 64, but is not limited to this, and an ultrasonic probe having an arbitrary number of elements can be used.

P is the focal point of the ultrasonic beam transmitted from the ultrasonic probe 4, and 6 is the backscattering region behind the focal point P. The backscattering region 6 is for uniformly scattering from any region, and corresponds to, for example, the skin interface portion of the subject. Reference numeral 7 is a wave-receiving beamformer for phasing and adding the wave-received echo signals transmitted via the transmission / reception circuit 3. A B-mode signal processing unit 8 receives the output of the received beam former 7 and performs signal processing for B-mode echo image observation.

Numeral 9 receives the output of the receiving beam former 7 and receives RTI (Reflex Transmission).
R for performing echo processing based on the (Imaging) method
It is a TI observation system. Here, the RTI method refers to a method of obtaining an image when an ultrasonic wave passing through a destination and reflected from a distance from the destination again passes through the destination. Reference numeral 10 is a controller that controls the operations of the transmission beam former 2, the reception beam former 7, the B-mode signal processing unit 8 and the RTI observation system 9, and 11 is a display unit that displays an echo image.
As the display unit 11, for example, a CRT is used. The display unit 11 is a first display unit 11 that displays a B-mode image.
a and a second display section 11b for displaying an RTI image. The operation of the apparatus configured as described above will be described below.

First, a transmission pulse is applied from the transmission beam former 2 to the ultrasonic probe 3 via the transmission / reception circuit 3 to transmit an ultrasonic wave focused on a point P in the subject 5. An echo is generated at the focal point P, and this echo is received by the ultrasonic probe 4 and then given to the receiving beam former 7 via the transmitting / receiving circuit 3 to perform phasing and addition by the receiving beam former 7. After that, the B-mode signal processing unit 8 is input as a main output. The B-mode signal processing unit 8 performs processing such as logarithmic compression and detection of the input echo signal, and performs normal B-mode image display on the first display unit 11a.

Next, the operation of the RTI method by the RTI observation system 9 will be described. The ultrasonic wave transmitted through the focal portion travels behind the focal point P and produces an echo in the backscattering region 6 (in this sense, the backscattering region 6 is referred to as a back echo source). The backscattering region 6 is composed of a medium that produces uniform scattering as described above, and corresponds to, for example, the skin interface portion of the subject. FIG. 4 is an explanatory diagram of the operation of the RTI method.

In response to the ultrasonic waves transmitted through the focal point P, echoes return from the region R (backscattering region 6) behind it. The echo having R as an echo source passes through the subject 5 and reaches the ultrasonic probe 4. The echo received by the ultrasonic probe 4 is phased and added by the reception beam former 7, and then enters the RTI observation system 9 as a sub output. RTI
In the observation system 9, the input echo signal is processed and the focus P
The RTI echo image of the surface including is calculated. This RTI image is displayed on the second display unit 11b.

FIG. 5 is an operation explanatory diagram of the RTI method, and FIG. 5A shows a display example of the second display portion 11b. θ and φ are two-dimensional azimuth angles. An RTI echo image of the surface Q including the focal point P is displayed on the second display unit 11b. In FIG. (A), 20 is the RT of the echo passing through the focal point P on the return path.
I echo images 21 to 23 are RTI echo images of echoes passing through points other than the focal point P on the return path.

When there is a sufficient non-linear effect in the forward transmission pulse at the focal point P, the level of ultrasonic waves is sufficiently attenuated by such non-linear transmission. When the ultrasonic wave sufficiently attenuated by the non-linear transmission reaches the backscattering region 6, an echo is similarly generated, but this echo is also sufficiently weak. This echo is received by the ultrasonic probe 4, phased and added by the received beam former 7, and R
The TI observation system 9 is entered, signal processing is performed, and an RTI echo image of the surface Q including the focal point P is calculated and displayed on the second display section 11b as shown in FIG.

Here, in order to appropriately simultaneously receive the echo returning through the focal point P and returning, and the echo returning without passing through the return path, the receiving beamformer 7 is used.
Has been set up or allocated resources so that it can receive the required number of simultaneous polyphonic rays. Such simultaneous polyphonic ray reception is a well-known general-purpose technique and configuration in echo imaging, and what is required here is within the range.

Note that it is obvious to those skilled in the art, an expert or an experienced person that information processing equivalent to the above can be performed by Fourier-transforming or Fresnel-transforming a time-gated or range-gated hologram on the aperture plane. Is.

Therefore, while performing such an observation, the degree of focus at the focus P is changed in a time division manner, or the transmission level itself is changed. In this case, changing the degree of focus means intentionally blurring the focus, and moving the focus backward or closer to the observation (transmission) aperture plane, or changing the shape of the converging wavefront. It means things. Simultaneously with this trial, the related RTI echo images 20 to 23 are displayed on the second display section 11b.
Is always displayed for level comparison. For example, the out-of-focus images 21 to 23 are normalized by the average value, and the in-focus image 20 is displayed at a relative level.

With a change in the degree of focus at the focus P or with a change in the transmission level, the stronger the focus, or the stronger the level of the transmission,
If the RTI echo image of the focus is relatively dark and appears at a lower level, it means that there is sufficient or significant non-linear attenuation in the focus P on the outward path.

The comparison can be performed by providing means for comparing the corresponding pixel values of the normalized RTI echo image.
Typically, although not shown or described in detail, it can be easily realized by a known method by a microprocessor or an image processing device coupled to a corresponding display image memory.

FIG. 5B is a diagram showing the echo intensity between BB 'in FIG. 5A. It can be seen that the echo intensity is attenuated in the portion of the echo image 20 corresponding to the focus. FIG. 5C shows a plot of echo intensity obtained by sampling several points as an echo image. Focus-corresponding echo image 20
This number of samples may be used to see whether or not the intensity of is significantly lower than the surrounding echo image.

When the focus-corresponding echo image 20 is darker than the surrounding echo images, it means that there is nonlinear attenuation in the focus portion. With this non-linear attenuation, if the transmission level of ultrasonic waves is raised too high, the probability that biological effects based on non-linearity will occur increases. Therefore, the transmission level at which the focus-corresponding echo image 20 becomes darker than the surroundings is set as the maximum transmission level at which it is estimated that no biological action occurs, and the B-mode image is obtained with this being the upper limit.

In other words, if managed in this way, it is possible to prevent excessively lowering the transmission level due to excessive awareness of safety, and also to maintain the depth of arrival of ultrasonic waves at which images can be acquired. It becomes possible to perform various ultrasonic diagnosis. Also, while being self-evident, B mode image and RTI
It is possible to display both images of the echo image in real time.

In the above embodiment, the case where the B mode image display is obtained in parallel with the image display by the RTI method has been described, but the present invention is not limited to this, and other modes such as the M mode display and the pulse Doppler mode. You may make it display etc.

Further, in the above-mentioned embodiment, the case where the display section is divided into two, the first display section and the second display section, and the image by the RTI method and the B-mode image are displayed is shown. However, the present invention is not limited to this, and the image by the RTI method and the B-mode image may be displayed on different display devices.

[0055]

As described above in detail, according to the first aspect of the invention, the transmission wave focused on one point in the subject,
The echo level corresponding to each of the echoes returned from the echo source behind the focus is compared with the echo level which is not adjusted to the one point or is reduced in the degree of adjustment to the one point, and Non-linearity using the RTI method that can estimate the transmission level at which heat is generated in the tissue of the subject by estimating the attenuation due to the non-linear effect at the focus when focusing on one point based on the comparison result An action estimation method can be provided.

According to the second aspect of the invention, the step of transmitting the light by focusing on one point in the subject, and the step of not transmitting to the one point,
Alternatively, a means for time-divisionally executing the step of transmitting the wave while reducing the degree of adjustment to the one point, and receiving an echo level corresponding to each of the waves returned from the echo source behind the focus, By providing means for comparing these levels and means for estimating the attenuation due to the non-linear effect at the focal point when focusing on one point based on the comparison result, the transmission of heat that begins to occur in the tissue of the subject is started. It is possible to provide a non-linear effect estimation device using the RTI method capable of estimating the wave level.

In this case, by combining the echo image display from the rear echo source and the normal ultrasonic image display, a normal ultrasonic image display based on the result of the echo image display from the rear echo source is performed. The ultrasonic wave transmission level of can be optimally set.

Further, if the normal echo image is a B-mode image, an M-mode image, a pulse Doppler image or an MTI image, an optimum transmission level that does not cause attenuation due to a non-linear effect on these images is determined. be able to.

According to the third invention, the transmission at a certain level focused on a point in the subject and the transmission with a changed transmission level are executed, and the echo source behind the focus is executed. By comparing the echo levels corresponding to the respective returned waves that are further returned, and estimating the attenuation due to the non-linear effect at the focus when focusing on one point based on the comparison result, heat is generated in the tissue of the subject. It is possible to provide a non-linear action estimation method using the RTI method capable of estimating the transmission level at which the occurrence of noise occurs.

According to the fourth aspect of the invention, the step of transmitting at a certain level focusing on one point in the subject and the step of changing the transmission level and transmitting are performed in a time division manner. Means for receiving echoes corresponding to the respective transmitted waves returning from an echo source behind the focus, and comparing the echo levels with each other; and a means for focusing on one point based on the comparison result. By providing a means for estimating the attenuation due to the non-linear effect at the focal point, it is possible to provide a non-linear effect estimation method using the RTI method capable of estimating the transmission level at which heat is generated in the tissue of the subject. .

In this case, by combining the echo image display from the rear echo source and the normal ultrasonic image display, the normal ultrasonic image display based on the result of the echo image display from the rear echo source is performed. The ultrasonic wave transmission level of can be optimally set.

Further, if the normal echo image is a B-mode image, an M-mode image, a pulsed Doppler image or an MTI image, an optimum transmission level that does not cause attenuation due to a non-linear effect on these images is determined. be able to.

[Brief description of drawings]

FIG. 1 is a flow chart showing the principle of the method of the present invention.

FIG. 2 is a flowchart showing another principle of the method of the present invention.

FIG. 3 is a configuration block diagram showing an embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the RTI method.

FIG. 5 is an operation explanatory diagram of the RTI method.

[Explanation of symbols]

 1 pulse generator 2 transmitting beamformer 3 transmitting / receiving circuit 4 ultrasonic probe 5 subject 6 rear echo source 7 receiving beamformer 8 B-mode signal processing unit 9 RTI observation system 10 controller 11 display unit

Claims (6)

[Claims] 1. A transmission wave focused on one point in the subject and a transmission wave not adjusted to the one point or reduced in the degree of adjustment to the one point are executed, The RTI method is characterized in that the echo levels corresponding to the respective waves returned from the echo source are compared, and the attenuation due to the non-linear action at the focus is estimated when one point is focused on the basis of the comparison result. Nonlinear action estimation method using. 2. A step of transmitting waves by focusing on one point in the subject and a step of transmitting waves without focusing on the one point or with less degree of focusing on the one point. And means for receiving echo levels corresponding to the respective transmitted waves returning from the echo source behind the focal point, comparing the levels, and focusing on one point based on the comparison result. And a means for estimating the attenuation due to the non-linear action at the focal point in the case. 3. A transmission at a certain level focused on a point in the subject and a transmission with a changed transmission level are executed, and each of the echoes is returned from an echo source behind the focus. A non-linear effect estimation method using the RTI method, characterized in that the echo levels corresponding to the transmitted waves are compared, and the attenuation due to the non-linear effect at the focus is estimated when one point is focused on the basis of the comparison result. 4. A means for time-divisionally executing a step of transmitting a wave at a certain level focused on a point in the subject, and a step of changing the wave transmission level and transmitting the waves in a time-division manner; Means for receiving echoes corresponding to the respective transmitted waves returning from the rear echo source and comparing the echo levels with each other, and attenuation due to non-linear action at the focus when focusing on one point based on the comparison result A non-linear effect estimating apparatus using the RTI method, which comprises: 5. The means for displaying a normal echo image together with the display of the estimated value of the non-linear effect estimated by the echo level from the rear echo source, according to claim 2 or 4. A non-linear effect estimation apparatus using the described RTI method. 6. The nonlinear action estimating apparatus using the RTI method according to claim 5, wherein the normal echo image is a B-mode image, an M-mode image, a pulse Doppler image, or an MTI image.