JP4860059B2 - Ultrasonic transmission / reception method and apparatus and ultrasonic imaging apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic transmission / reception method and apparatus and an ultrasonic imaging apparatus, and more particularly to an ultrasonic transmission / reception method and apparatus for performing acoustic ray sequential scanning with an ultrasonic beam (beam) with a changed focus, and the same The present invention relates to an ultrasonic imaging apparatus including such a transmission / reception device.
[0002]
[Prior art]
In ultrasonic imaging, an acoustic beam is scanned sequentially while an ultrasonic beam (beam) is transmitted and its echo is received, and an image is generated based on the echo reception signal.
[0003]
An ultrasonic beam focused at a predetermined distance is used. In that case, a plurality of scans with different focus may be performed, and images obtained by the respective scans may be connected to each focus area to form an image of one frame. This is also called a combination focus method, and is used for clear imaging from a shallow part to a deep part.
[0004]
In some cases, a plurality of scans with different transmission frequencies are performed, and images obtained by the respective scans are added to form one frame image. This is also called a frequency compound method, and is used to reduce a speckle pattern in an image.
[0005]
[Problems to be solved by the invention]
In the combination focus method, focus area joints tend to be unnatural. In the frequency compound method, there is no joint between images, but there is no effect of expanding the focus range.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to realize an ultrasonic transmission / reception method and apparatus that makes the connecting portion of the focus area inconspicuous while using the combination focus method, and an ultrasonic imaging apparatus including such a transmission / reception apparatus. It is.
[0007]
[Means for Solving the Problems]
(1) One aspect of the invention for solving the above-described problem is that sound waves are sequentially transmitted while transmitting an ultrasonic beam a plurality of times per sound ray and receiving each echo while changing the frequency and focus. Scanning, adding a plurality of echo reception signals having the same sound ray, and filtering the added echo reception signals with a filter whose frequency pass band continuously changes from a high frequency to a low frequency. This is an ultrasonic transmission / reception method.
[0008]
(2) In another aspect of the invention for solving the above-described problem, a sound ray is sequentially transmitted while receiving an echo by transmitting a plurality of ultrasonic beams per sound ray by changing the frequency and focus. Ultrasonic transmission / reception means for performing scanning, addition means for adding a plurality of echo reception signals having the same sound ray, and a frequency pass band of the added echo reception signal continuously changing from a high frequency to a low frequency An ultrasonic transmission / reception apparatus comprising: filtering means for filtering by a filter.
[0009]
(3) In another aspect of the invention for solving the above-mentioned problem, a sound ray is sequentially transmitted while receiving an echo by transmitting an ultrasonic beam a plurality of times per sound ray by changing a frequency and a focus. Ultrasonic transmission / reception means for performing scanning, addition means for adding a plurality of echo reception signals having the same sound ray, and a frequency pass band of the added echo reception signal continuously changing from a high frequency to a low frequency An ultrasonic imaging apparatus comprising: filtering means for filtering by a filter; and image generation means for generating an image based on an output signal of the filtering means.
[0010]
In the inventions according to the respective aspects described in (1) to (3), sound ray sequential scanning is performed while transmitting an ultrasonic beam a plurality of times per sound ray and receiving each echo while changing the frequency and focus. A plurality of echo reception signals having the same sound ray are added to each other and filtered with a filter whose frequency pass band continuously changes from a high frequency to a low frequency.
[0011]
The added echo reception signal includes a plurality of signals having different frequencies and focus. A signal obtained by filtering this with a filter whose frequency pass band continuously changes from a high range to a low range has a configuration ratio of a plurality of signals continuously changed. For this reason, the connection of the focus areas becomes inconspicuous.
[0012]
(4) In another aspect of the invention for solving the above-mentioned problem, an acoustic ray is transmitted while transmitting an ultrasonic beam a plurality of times per acoustic ray by changing the burst wave number and focus and receiving each echo. A sequential scan is performed, a plurality of echo reception signals having the same sound ray are added together, and the added echo reception signal is filtered by a filter whose frequency pass band continuously changes from a high frequency to a low frequency. This is a characteristic ultrasonic transmission / reception method.
[0013]
(5) In another aspect of the invention for solving the above-mentioned problem, an acoustic ray is transmitted while transmitting an ultrasonic beam a plurality of times per acoustic ray by changing the burst wave number and focus and receiving each echo. Ultrasonic transmission / reception means for performing sequential scanning, addition means for adding a plurality of echo reception signals having the same sound ray, and the frequency pass band of the added echo reception signal continuously changing from a high frequency to a low frequency An ultrasonic transmission / reception apparatus comprising: filtering means for filtering with a filter that performs the filtering.
[0014]
(6) According to another aspect of the invention for solving the above-described problem, an acoustic ray is transmitted while receiving an echo by transmitting a plurality of ultrasonic beams per acoustic ray while changing the burst wave number and focus. Ultrasonic transmission / reception means for performing sequential scanning, addition means for adding a plurality of echo reception signals having the same sound ray, and the frequency pass band of the added echo reception signal continuously changing from a high frequency to a low frequency An ultrasonic imaging apparatus comprising: filtering means for filtering with a filter that performs filtering; and image generation means for generating an image based on an output signal of the filtering means.
[0015]
In the inventions according to the respective aspects described in (4) to (6), the acoustic wave sequence is changed while receiving the respective echoes by transmitting a plurality of ultrasonic beams per acoustic line by changing the burst wave number and the focus. Scanning is performed, and a plurality of echo reception signals having the same sound ray are added together, and filtered by a filter whose frequency pass band continuously changes from high to low.
[0016]
The added echo reception signal includes a plurality of signals having different frequencies and focus. A signal obtained by filtering this with a filter whose frequency pass band continuously changes from a high range to a low range has a configuration ratio of a plurality of signals continuously changed. For this reason, the connection of the focus areas becomes inconspicuous.
[0017]
(7) In another aspect of the invention for solving the above-described problem, the frequency, the burst wave number, and the focus are changed, and a plurality of ultrasonic beams are transmitted per sound ray and each echo is received. Performs sound ray sequential scanning, adds a plurality of echo reception signals having the same sound ray, and filters the added echo reception signals with a filter whose frequency pass band continuously changes from high to low. This is an ultrasonic transmission / reception method.
[0018]
(8) In another aspect of the invention for solving the above-described problem, the frequency, the burst wave number, and the focus are changed, and a plurality of ultrasonic beams are transmitted per sound ray and each echo is received. Ultrasonic wave transmission / reception means for performing sound ray sequential scanning, addition means for adding together a plurality of echo reception signals having the same sound ray, and the frequency response band of the added echo reception signals is continuously from high to low. An ultrasonic transmission / reception apparatus comprising: filtering means for filtering with a filter that changes to
[0019]
(9) In another aspect of the invention for solving the above-described problem, the frequency, the burst wave number, and the focus are changed, and a plurality of ultrasonic beams are transmitted per sound ray and each echo is received. Ultrasonic wave transmission / reception means for performing sound ray sequential scanning, addition means for adding together a plurality of echo reception signals having the same sound ray, and the frequency response band of the added echo reception signals is continuously from high to low. An ultrasonic imaging apparatus comprising: filtering means for filtering with a filter that changes to an image; and image generation means for generating an image based on an output signal of the filtering means.
[0020]
In the invention according to each aspect described in (8) to (9), a sound ray is transmitted while transmitting an ultrasonic beam a plurality of times per sound ray by changing the frequency, burst wave number, and focus and receiving each echo. Sequential scanning is performed, and a plurality of echo reception signals having the same sound ray are added together, and filtered by a filter in which the frequency pass band continuously changes from a high range to a low range.
[0021]
The added echo reception signal includes a plurality of signals having different frequencies and focus. A signal obtained by filtering this with a filter whose frequency pass band continuously changes from a high range to a low range has a configuration ratio of a plurality of signals continuously changed. For this reason, the connection of the focus areas becomes inconspicuous.
[0022]
It is preferable that the frequency pass band is wider as the frequency is lower, from the viewpoint of improving the depiction of the deep part.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment. FIG. 1 shows a block diagram of the ultrasonic imaging apparatus. This apparatus is an example of an embodiment of the present invention. An example of an embodiment relating to the apparatus of the present invention is shown by the configuration of the apparatus. An example of an embodiment related to the method of the present invention is shown by the operation of the apparatus.
[0024]
As shown in FIG. 1, the present apparatus has an ultrasonic probe 2. The ultrasonic probe 2 has an array of a plurality of ultrasonic transducers (not shown). Each ultrasonic transducer is made of a piezoelectric material such as PZT (titanium (Ti) zirconate (Zr) acid) ceramics. The ultrasonic probe 2 is used in contact with the object 4 by the user.
[0025]
The ultrasonic probe 2 is connected to the transmission / reception unit 6. The transmission / reception unit 6 sends a drive signal to the ultrasonic probe 2 to transmit ultrasonic waves. The transmission / reception unit 6 also receives an echo signal received by the ultrasonic probe 2.
[0026]
A block diagram of the transceiver 6 is shown in FIG. As shown in the figure, the transmission / reception unit 6 includes a transmission timing generation unit (unit) 602, a transmission beamformer (beamformer) 604, a transmission / reception switching unit 606, a reception beamformer 610, an addition unit 612, and a filtering unit. 614.
[0027]
The transmission timing generation unit 602 periodically generates a transmission timing signal and inputs it to the transmission beam former 604. The transmission beamformer 604 performs beamforming of the transmission, and generates a beamforming signal for forming an ultrasonic beam having a predetermined direction based on the transmission timing signal.
[0028]
The beam forming signal includes a plurality of drive signals to which time differences corresponding to the azimuth and focus distance of the ultrasonic beam are given. Beam forming is controlled by the control unit 18 described later. The control unit 18 also controls the frequency or burst wave number of the drive signal, or the frequency and burst wave number.
[0029]
The transmission beam former 604 inputs the transmission beam forming signal to the transmission / reception switching unit 606. The transmission / reception switching unit 606 inputs a beamforming signal to the ultrasonic transducer array. In the ultrasonic transducer array, a plurality of ultrasonic transducers constituting a transmission aperture each generate an ultrasonic wave having a phase difference corresponding to a time difference of drive signals. By the wavefront synthesis of the ultrasonic waves, an ultrasonic beam having a focus at a predetermined distance along a sound ray in a predetermined direction is formed.
[0030]
A reception beam former 610 is connected to the transmission / reception switching unit 606. The transmission / reception switching unit 606 inputs a plurality of echo signals received by the reception aperture in the ultrasonic transducer array to the reception beam former 610.
[0031]
The receiving beam former 610 performs received beam forming corresponding to the sound ray of the transmitted wave, adjusts the phase by giving a time difference to a plurality of received echoes, and then adds them to generate sound in a predetermined direction. An echo reception signal along the line is formed. The beam forming of the received wave is controlled by the control unit 18 described later.
[0032]
The portion including the ultrasonic probe 2, the transmission timing generation unit 602, the transmission beam former 604, the transmission / reception switching unit 606, the reception beam former 610, and the control unit 18 is an example of an embodiment of the ultrasonic transmission / reception apparatus of the present invention. is there. Moreover, it is an example of embodiment of the ultrasonic transmission / reception means in this invention.
[0033]
Transmission of the ultrasonic beam is repeatedly performed at a predetermined time interval based on the transmission timing signal generated by the transmission timing generation unit 602, and echo reception is performed each time.
[0034]
Transmission / reception of ultrasonic waves is repeated a plurality of times per sound ray. The number of times is 2, for example, but is not limited to this and may be appropriate. The focus distance is changed every time. The focus distance is changed to sequentially follow a plurality of predetermined distances, for example, from a short distance to a long distance. Or you may make it follow in order from a long distance to a short distance, and may be random.
[0035]
FIG. 3 schematically shows an example in which the number of transmission / reception is two. As shown in the figure, ultrasonic beams focused on points P1 and P3 on the sound ray 400 are transmitted from the ultrasonic transducer array 300, respectively. The distance from the ultrasonic transducer array 300 to the point P1, that is, the near focus distance is F1. The distance from the ultrasonic transducer array 300 to the point P3, that is, the far focus distance is F3.
[0036]
Each time, the frequency of the transmitted ultrasonic wave or the burst wave number, or the frequency and the burst wave number are changed. When changing the frequency, the frequency is lowered as the focus distance becomes longer. When changing the burst wave number, the burst wave number is increased as the focus distance becomes longer. When both the frequency and the burst wave number are changed, the frequency is lowered and the burst wave number is increased as the focus distance is increased.
[0037]
The attenuation rate of the ultrasonic wave traveling through the medium has a frequency characteristic, and the attenuation increases as the frequency increases. For this reason, ultrasonic waves with high frequencies are difficult to reach far. Therefore, the longer the focus distance, the lower the transmission frequency so that it can be easily reached far. Even if the burst wave number of the transmitted ultrasonic wave is increased, the same effect can be obtained. Instead of reducing the frequency, or in addition to this, the burst wave number should be increased so that the ultrasonic wave can be easily reached. Also good.
[0038]
An echo for such a transmission is returned to the ultrasonic transducer array 300. The return time of the echo from the point P1 is t1. The return time of the echo from the point P2 is t2. The return time of the echo from the point P3 is t3.
[0039]
The echo is received by the ultrasonic transducer array 300 and beam-formed by the receiving beam former 610. As a result, an echo reception signal along the sound ray 400 is formed. Corresponding to two transmissions, an echo reception signal is formed twice.
[0040]
The two echo reception signals are input from the reception beam former 610 to the addition unit 612. The adding unit 612 adds the two echo reception signals related to one sound ray in accordance with the time axis. As a result, a synthesized echo reception signal as shown in FIG. 4, for example, is obtained by synthesizing the echo reception signal of the transmission ultrasonic wave focused on the point P1 and the echo reception signal of the transmission ultrasonic wave focused on the point P3. The adding unit 612 is an example of an embodiment of the adding means in the present invention.
[0041]
In the synthesized echo reception signal shown in FIG. 4, echoes from the points P1, P2, and P3 exist at positions t1, t2, and t3 on the time axis, respectively. The signal at the position t1 on the time axis is an echo from the near focus. This mainly consists of echoes of ultrasonic waves that are converged to near focus and transmitted. The transmitted ultrasonic wave converged to near focus contains many high frequency components. In addition, the echo from the near focus includes many high frequency components. Therefore, the signal at the position of t1 on the time axis is mainly composed of a high frequency component.
[0042]
The signal at the position t3 on the time axis is an echo from the far focus. This mainly consists of echoes of ultrasonic waves that are converged to a far focus and transmitted. The transmitted ultrasonic wave converged to the far focus contains many low-frequency components. Further, the echo from the far focus includes a lot of low frequency components. Therefore, the signal at the position of t3 on the time axis mainly includes a low frequency component.
[0043]
The signal at the position of t2 on the time axis is an echo from the middle of the near focus and the far focus, and is a mixture of the echo of the transmitted ultrasonic wave converged to the near focus and the echo of the transmitted ultrasonic wave converged to the far focus. is there. In this signal, the high frequency component is attenuated more than the signal at t1, and is not attenuated as much as the signal at t3, so the mid frequency component is mainly used.
[0044]
The output signal of the adding unit 612 is filtered by a filtering unit 614 and output. The filtering unit 614 is a variable band-pass filter, and the frequency pass band changes with time. Hereinafter, the frequency pass band is also referred to as a pass band. The filtering unit 614 is an example of an embodiment of the filtering means in the present invention.
[0045]
FIG. 5 schematically shows a time change of the passband of the filtering unit 614. In the figure, the horizontal axis is the frequency axis, and the vertical axis is the gain axis. As shown in the figure, the passband moves continuously from high to low with the passage of time. The length of the movement time is the same as the time length of the synthesized echo reception signal. For this reason, the pass band is in the high band as shown by the solid line at time t1, in the middle band as shown by the one-dot chain line at time t2, and in the low band as shown by the two-dot chain line at time t3. .
[0046]
The signal at the position of t1 on the time axis of the synthesized echo reception signal is filtered by the band pass indicated by the solid line. Since the signal at the position of t1 is mainly composed of high frequency components, it passes through this passband efficiently. Since this signal is mainly composed of echoes of ultrasonic waves that are converged to near focus and transmitted, the vicinity of the near focus is rendered with high spatial resolution.
[0047]
The signal at the position of t3 on the time axis of the synthesized echo reception signal is filtered by a band pass indicated by a two-dot chain line. Since the signal at the position of t3 is mainly composed of a low frequency component, it passes through this passband efficiently. Since this signal is mainly an echo of an ultrasonic wave that has been converged and transmitted to the far focus, it becomes a signal that depicts the vicinity of the far focus with high spatial resolution.
[0048]
The signal at the position t2 on the time axis of the synthesized echo reception signal is filtered by a band pass indicated by a one-dot chain line. Since the signal at the position t2 is mainly composed of the mid-band component, it passes through this passband efficiently.
[0049]
This signal is a mixture of the echo of the transmitted ultrasonic wave converged to the near focus and the echo of the transmitted ultrasonic wave converged to the far focus. The mixing ratio changes continuously as the passband moves. In this way, since the mixing ratio of the two signals changes continuously, the conventional joint does not occur in the middle portion between the near focus and the far focus.
[0050]
The pass band of the filtering unit 614 may gradually widen as it moves to the low frequency side as shown in FIG. In this way, the visibility of the deep part can be improved by widening the passband of the echo from the deep part.
[0051]
Each time the transmitting beamformer 604 and the receiving beamformer 610 perform transmission / reception, for example, twice per sound ray under the control of the control unit 18 described later, the direction of the sound ray is changed by a predetermined amount. Thereby, the inside of the object 4 is scanned in a sound ray sequence.
[0052]
The transmission / reception unit 6 having such a configuration performs scanning as shown in FIG. 7, for example. That is, the fan-shaped two-dimensional region 206 is scanned in the θ direction by the sound ray 202 extending in the z direction from the radiation point 200, and so-called sector scan is performed.
[0053]
When the transmission and reception apertures are formed by using a part of the ultrasonic transducer array, the apertures are sequentially moved along the array, for example, to perform scanning as shown in FIG. That is, by moving a sound ray 202 emitted from the radiation point 200 in the z direction along a linear locus 204, a rectangular two-dimensional region 206 is scanned in the x direction, and a so-called linear scan is performed. Do.
[0054]
When the ultrasonic transducer array is a so-called convex array formed along an arc extending in the ultrasonic wave transmission direction, for example, as shown in FIG. Thus, it goes without saying that the so-called convex scan can be performed by moving the radiation point 200 of the sound ray 202 along the arc-shaped locus 204 and scanning the fan-shaped two-dimensional region 206 in the θ direction.
[0055]
The transmission / reception unit 6 is connected to a B-mode processing unit 10. The echo reception signal for each sound ray output from the transmission / reception unit 6 is input to the B-mode processing unit 10.
[0056]
The B-mode processing unit 10 forms B-mode image data (data). As shown in FIG. 10, the B-mode processing unit 10 includes a logarithmic amplification unit 104 and an envelope detection unit 106.
[0057]
The B mode processing unit 10 logarithmically amplifies the echo reception signal by the logarithmic amplification unit 104, envelope detection by the envelope detection unit 106, and a signal representing the echo intensity at each reflection point on the sound ray, that is, an A scope ( (scope) signal is obtained, and B-mode image data is formed using the instantaneous amplitude of the A scope signal as a luminance value.
[0058]
The B mode processing unit 10 is connected to the image processing unit 14. The image processing unit 14 generates a B-mode image based on data input from the B-mode processing unit 10. A display unit 16 is connected to the image processing unit 14. The display unit 16 receives the B mode image data from the image processing unit 14 and displays an image based on the B mode image data. The portion including the B-mode processing unit 10, the image processing unit 14, and the display unit 16 is an example of an embodiment of the image generation unit in the present invention.
[0059]
By the processing of the echo reception signal as described above in the transmission / reception unit 6, the B-mode image draws both near focus and near focus with good spatial resolution. Further, the processing of the echo reception signal as described above by the transmission / reception unit 6 does not cause a conventional joint between the near focus region and the far focus region.
[0060]
A control unit 18 is connected to the transmission / reception unit 6, the B-mode processing unit 10, the image processing unit 14, and the display unit 16. The control unit 18 gives control signals to these units to control their operation. Various signals are input to the control unit 18 from each part to be controlled.
[0061]
An operation unit 20 is connected to the control unit 18. The operation unit 20 is operated by a user and inputs appropriate commands and information to the control unit 18. The B mode operation as described above is executed under the control of the control unit 18.
[0062]
【Effect of the invention】
As described above in detail, according to the present invention, an ultrasonic transmission / reception method and apparatus that makes the connecting portion of the focus area inconspicuous while using the combination focus method, and an ultrasonic wave equipped with such a transmission / reception apparatus An imaging device can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram of a transmission / reception unit.
FIG. 3 is a schematic diagram showing focusing of a transmitted ultrasonic beam.
FIG. 4 is a schematic diagram showing an echo reception signal.
FIG. 5 is a schematic diagram showing a pass band of a filtering unit.
FIG. 6 is a schematic diagram showing a pass band of a filtering unit.
FIG. 7 is a schematic diagram of sound ray scanning.
FIG. 8 is a schematic diagram of sound ray scanning.
FIG. 9 is a schematic diagram of sound ray scanning.
FIG. 10 is a block diagram of a B mode processing unit.
[Explanation of symbols]
2 Ultrasonic probe 4 Target 6 Transmission / reception unit 10 B mode processing unit 14 Image processing unit 16 Display unit 18 Control unit 20 Operation unit 602 Transmission timing generation unit 604 Transmission beamformer 606 Transmission / reception switching unit 610 Reception beamformer 612 Addition unit 614 Filtering unit 104 Logarithmic amplification unit 106 Envelope detection unit

Claims (12)

Scanning the sound ray sequentially while changing the frequency and focus, sending multiple ultrasonic beams per sound ray and receiving each echo,
Adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted by changing the frequency and focus for the same sound line ,
Filtering the added echo reception signal with a filter whose frequency passband continuously changes from high to low;
An ultrasonic transmission / reception method. Change the burst wave number and focus, send multiple ultrasonic beams per sound ray and receive each echo to scan the sound ray sequentially,
Adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted by changing the burst wave number and focus for the same sound line ,
Filtering the added echo reception signal with a filter whose frequency passband continuously changes from high to low;
An ultrasonic transmission / reception method. Change the frequency, burst wave number and focus, send multiple ultrasonic beams per sound ray and receive each echo, scan the sound ray sequentially,
Adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted by changing the frequency, burst wave number and focus for the same sound line ,
Filtering the added echo reception signal with a filter whose frequency passband continuously changes from high to low;
An ultrasonic transmission / reception method. The frequency pass band is wider as it becomes lower,
The ultrasonic transmission / reception method according to claim 1, wherein the ultrasonic transmission / reception method is performed. Ultrasonic transmission / reception means for changing the frequency and focus and transmitting a plurality of ultrasonic beams per sound ray and receiving the respective echoes while scanning the sound rays sequentially;
An adding means for adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted at different frequencies and focus for the same sound line ;
Filtering means for filtering the added echo reception signal with a filter whose frequency passband continuously changes from a high frequency to a low frequency;
An ultrasonic transmission / reception apparatus comprising: Ultrasonic transmission / reception means for changing the burst wave number and focus and transmitting the ultrasonic beam a plurality of times per sound ray and receiving the respective echoes, and performing sound ray sequential scanning;
An adding means for adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted by changing the burst wave number and focus for the same sound line ,
Filtering means for filtering the added echo reception signal with a filter whose frequency passband continuously changes from a high frequency to a low frequency;
An ultrasonic transmission / reception apparatus comprising: Ultrasonic transmission / reception means for changing the frequency, burst wave number, and focus, transmitting a plurality of ultrasonic beams per sound ray and receiving respective echoes, and performing sound ray sequential scanning;
Adding means for adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted by changing the frequency, burst wave number and focus for the same sound line ;
Filtering means for filtering the added echo reception signal with a filter whose frequency passband continuously changes from a high frequency to a low frequency;
An ultrasonic transmission / reception apparatus comprising: The frequency pass band is wider as it becomes lower,
The ultrasonic transmission / reception apparatus according to any one of claims 5 to 7, wherein the ultrasonic transmission / reception apparatus is characterized. Ultrasonic transmission / reception means for changing the frequency and focus and transmitting a plurality of ultrasonic beams per sound ray and receiving the respective echoes while scanning the sound rays sequentially;
An adding means for adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted at different frequencies and focus for the same sound line ;
Filtering means for filtering the added echo reception signal with a filter whose frequency passband continuously changes from a high frequency to a low frequency;
Image generating means for generating an image based on an output signal of the filtering means;
An ultrasonic imaging apparatus comprising: Ultrasonic transmission / reception means for changing the burst wave number and focus and transmitting the ultrasonic beam a plurality of times per sound ray and receiving the respective echoes, and performing sound ray sequential scanning;
An adding means for adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted by changing the burst wave number and focus for the same sound line ,
Filtering means for filtering the added echo reception signal with a filter whose frequency passband continuously changes from a high frequency to a low frequency;
Image generating means for generating an image based on an output signal of the filtering means;
An ultrasonic imaging apparatus comprising: Ultrasonic transmission / reception means for changing the frequency, burst wave number, and focus, transmitting a plurality of ultrasonic beams per sound ray and receiving respective echoes, and performing sound ray sequential scanning;
Adding means for adding a plurality of echo reception signals of the same sound line corresponding to the different ultrasonic beams transmitted by changing the frequency, burst wave number and focus for the same sound line ;
Filtering means for filtering the added echo reception signal with a filter whose frequency passband continuously changes from a high frequency to a low frequency;
Image generating means for generating an image based on an output signal of the filtering means;
An ultrasonic imaging apparatus comprising: The frequency pass band is wider as it becomes lower,
The ultrasonic imaging apparatus according to claim 9, wherein the ultrasonic imaging apparatus is characterized in that

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