JP4257259B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a parallel simultaneous reception technique for forming a plurality of reception beams for each transmission beam.

Multidirectional parallel simultaneous reception is known as a technique for improving the frame rate of an ultrasonic image in an ultrasonic diagnostic apparatus. FIG. 8 is a diagram for explaining parallel simultaneous reception. FIG. 8A shows a conceptual diagram of four-way simultaneous reception, and FIG. 8B shows a conceptual diagram of two-way simultaneous reception. It is shown. In multi-directional parallel simultaneous reception, a plurality of reception beams are formed from one transmission beam. That is, in the four-direction simultaneous reception illustrated in FIG. 8A, four reception beams are formed from one transmission beam. For example, four reception beams R _{1 to} R ₄ are formed almost simultaneously (as one set of transmission and reception) from the transmission beam T ₁ . In the two-way simultaneous reception shown in FIG. 8B, two reception beams are formed from one transmission beam. For example, two reception beams R ₁ and R ₂ are formed almost simultaneously from the transmission beam T ₁ .

  In an ultrasonic image formed by parallel simultaneous reception, there is a concern about the occurrence of striped artifacts (striped pattern). The main cause is a difference in reception sensitivity between a plurality of reception beams and the strength of correlation between reception beams.

In multidirectional parallel simultaneous reception, one transmission beam is transmitted over a relatively wide range. For this reason, the transmission beam spreads in the azimuth direction and is transmitted. For example, as shown in FIG. 8A, each of the transmission beams T ₁ and T ₂ has a strong amplitude in the vicinity of the center thereof, and the amplitude decreases from the center toward the outer side in the azimuth direction. As a result, each reception beam formed as a reflected wave of the transmission beam has a relatively strong amplitude near the center and a relatively small amplitude outside the azimuth direction. For example, among the four reception beams obtained from the transmission beam T ₁ in FIG. 8A, the reception beams R ₂ and R ₃ located at the center in the azimuth direction have a relatively strong amplitude and are located outside the azimuth direction. The received beams R ₁ and R ₄ have a relatively weak amplitude. Thus, in the four-direction simultaneous reception, as shown in FIG. 8A, the strength of transmission / reception total sensitivity in the azimuth direction is repeatedly generated as weak strong strong weak strong strong and weak. This repetition of strength and weakness appears as a striped pattern on the ultrasonic image.

Further, reception beams formed from the same transmission beam have a strong correlation between the beams. For example, as shown in FIG. 8B, the correlation between the reception beams R ₁ and R ₂ corresponding to the same transmission beam T ₁ is relatively strong, and the reception beams R corresponding to the different transmission beams T ₁ and T ₂ , respectively. The correlation between ₂ and R ₃ is relatively weak. For this reason, in the two-way simultaneous reception, as shown in FIG. 8B, the strength of the correlation between the reception beams in the azimuth direction is repeatedly generated as strong, weak, strong, and strong. This repetition of strength and weakness appears as a striped pattern on the ultrasonic image.

  Conventionally, several techniques for removing a stripe pattern generated by parallel simultaneous reception are known. For example, there is a method of performing weighted addition between a plurality of reception beams received in parallel (see Patent Document 1). In addition, a technique for removing the stripe pattern by adjusting the gain of the received beam (received signal) (see Patent Document 2), and a technique for removing the stripe pattern by shifting the transmission / reception beam pattern for each frame of the ultrasonic image (see FIG. Patent Document 3) is also known.

Japanese Patent Laid-Open No. 61-135641 JP-A-6-225883 JP-A-10-118063

  When weighted addition is performed between multiple receive beams to remove the stripe pattern, for example, by averaging the multiple receive beams received simultaneously in parallel, the strength of the transmission / reception overall sensitivity and the strength of the correlation between the receive beams are alleviated. And striped patterns can be removed. On the other hand, averaging reduces the resolution in the azimuth direction (azimuth resolution) of the ultrasound image. In particular, when the number of simultaneously received beams is large and the number of beams to be averaged is large, the reduction in azimuth resolution becomes significant. For this reason, there has been a demand for a new technique for improving the image quality by removing the striped pattern without causing side effects such as a decrease in azimuth resolution.

  Accordingly, an object of the present invention is to provide a new technique for improving the image quality of an ultrasonic image obtained in multidirectional simultaneous reception.

  In order to achieve the above object, an ultrasonic diagnostic apparatus according to a preferred aspect of the present invention includes an ultrasonic probe including a plurality of vibration elements, and electronic scanning control of the plurality of vibration elements for each scanning frame. From a transmission unit that forms a plurality of transmission beams, a reception unit that forms a plurality of reception beams for each transmission beam, a filter unit that filters the echo data of the plurality of reception beams, and the filtered echo data An image forming unit that forms an ultrasonic image, and the filter unit includes, for each transmission beam, an azimuth direction data string obtained by arranging echo data of a plurality of reception beams in the azimuth direction in each scanning frame. It includes a notch filter that removes a spatial frequency component set according to the number of received beams.

  In the above configuration, the spatial frequency component set according to the number of reception beams for each transmission beam is, for example, a fringe generated due to a difference in reception sensitivity between a plurality of reception beams or a correlation between reception beams. The spatial frequency of the pattern. According to the above configuration, only the narrow-band frequency component including a desired spatial frequency component (for example, a striped spatial frequency) is removed by the notch filter. Image quality can be improved.

  Preferably, the notch filter is configured by a FIR (Finite Impulse Response) filter. Preferably, the notch filter is an IIR (Infinite Impulse Response) filter.

  Preferably, the azimuth direction data sequence is obtained by acquiring a plurality of data sequences of echo data arranged in the azimuth direction from the reception beam at one end toward the reception beam at the other end at different depths. Are formed by connecting the two.

  Preferably, the azimuth direction data sequence includes a predetermined number of data arranged from one end of the data sequence in each data sequence of echo data arranged in the azimuth direction from the reception beam at one end to the reception beam at the other end. It is formed by adding a predetermined number of auxiliary data obtained by folding back at one end.

  Preferably, the FIR filter includes 10 or more taps. Preferably, the FIR filter is composed of 63 taps.

  The image quality of the ultrasonic image obtained in the multi-directional simultaneous reception can be improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is an overall configuration diagram thereof.

  The probe 10 is an ultrasonic probe that transmits and receives ultrasonic waves, and has a plurality of vibration elements (not shown) therein. The transmission circuit 12 functions as a transmission beam former that forms a plurality of transmission beams for each scanning frame by electronic scanning control of a plurality of vibration elements in the probe 10. Each of the reception beam forming units 14 to 20 functions as a reception beam former that forms a reception beam by phasing and adding reception signals output from a plurality of vibration elements in the probe 10. The received signal subjected to phasing addition is subjected to LOG compression processing and detection processing. For this reason, a LOG compression unit and a detection circuit are provided in each reception beam forming unit 14-20. Thus, each of the reception beam forming units 14 to 20 performs phasing addition processing, LOG compression processing, detection processing, and the like, and outputs echo data of the corresponding reception beam. The LOG compression unit may be provided in the image forming unit 42 described in detail later.

In the present embodiment, a four-direction simultaneous reception process for forming four reception beams for each transmission beam is executed. The four reception beam forming units 14 to 20 correspond to reception beams in four directions that are simultaneously received. That is, taking the conceptual diagram of the four-direction simultaneous reception shown in FIG. 8A as an example, the transmission beam T ₁ and T ₂ are formed at the respective timings by the transmission circuit 12, and the reception beam corresponding to the transmission beam T ₁ is formed. R _{1 to} R ₄ are formed by the reception beam forming units 14 to 20, respectively. In addition, reception beams R _{5 to} R ₈ corresponding to the transmission beam T ₂ are formed by the reception beam forming units 14 to 20, respectively. In the present embodiment, four-direction simultaneous reception will be described as an example, but the present invention is not limited to four-way simultaneous reception, and can be used for two-way simultaneous reception, three-way simultaneous reception, and the like.

  The beam selector 22 outputs echo data output from each of the reception beam forming units 14 to 20 to the frame selector (1) 24. The beam selector 22 selects, for example, an output in the order of the output of the reception beam forming unit 14, the output of the reception beam forming unit 16, the output of the reception beam forming unit 18, and the output of the reception beam forming unit 20 to select the frame selector (1). To 24.

  The frame selector (1) 24 outputs the echo data output from each of the reception beam forming units 14 to 20 to the frame memory A26 or the frame memory B28. The frame selector (1) 24 selects the frame memory A26 or the frame memory B28 according to the scanning frame. For example, the frame memory A26 is selected when the scan frame is an odd frame, and the frame memory B28 is selected when the scan frame is an even frame.

The frame selector (2) 36 outputs echo data read from the frame memory A26 or the frame memory B28 to the band rejection filter (BRF) 40. The echo data is output to the BRF 40 as an azimuth direction data string obtained by arranging echo data of a plurality of reception beams in the azimuth direction in each scanning frame. Azimuth data sequence, taking as an example a schematic diagram of a four-way simultaneous reception shown in FIG. 8 (A), receiving a plurality of echo data in the depth of transducing direction beam _{R 1, R 2, R 3} , Time series data extracted in the order of R ₄ , R ₅ , R ₆ . A method for forming the azimuth direction data string will be described in detail later with reference to FIG. The BRF 40 removes a spatial frequency component set according to the number of received beams for each transmission beam from the azimuth direction data string.

  FIG. 2 is an internal configuration diagram of the BRF 40 of FIG. Hereinafter, the internal configuration of the BRF 40 will be described with reference to FIG.

FIG. 2 shows an FIR (Finite Impulse Response) filter including a plurality of delay elements 50, a plurality of multipliers 52, and a plurality of adders 54. Each echo data in the azimuth direction data string (time series data) input to the BRF 40 for each time phase is subjected to delay processing for one time phase by each delay element 50. Each echo data (including those after delay processing) is multiplied by predetermined filter coefficients (h ₁ , h ₂ ,..., H _n ) in each multiplier 52. Further, addition processing is executed in each adder 54.

  The filter characteristics of the FIR filter depend on the filter coefficient. In the present embodiment, the frequency (spatial frequency) of the striped artifact is set to the notch frequency (frequency to be removed) in order to remove the striped artifact (striped pattern) generated in the ultrasonic image formed by parallel simultaneous reception. A notch filter is formed.

  The main cause of the striped artifact is the difference in reception sensitivity between multiple beams and the strength of correlation between beams. Taking the conceptual diagram shown in FIG. 8 as an example, in FIG. 8A, the strength of transmission / reception comprehensive sensitivity in the azimuth direction is repeatedly generated as weak, strong, weak, weak, strong and weak, and so on. It appears as a light and dark stripe pattern on the top. This strong and weak periodicity is expressed by the normalized spatial frequency, that is, the ratio of the number of fringes to the total number of beams in one scanning frame. In the four-direction simultaneous reception in FIG. 8A, the standardized spatial frequency of fringes is “0.25”, and the number of fringes is ¼ of the total number of beams. That is, fringes are generated at a rate of one for every four beams.

  In the two-direction simultaneous reception in FIG. 8B, the strength of the correlation between the received beams in the azimuth direction is repeatedly generated as strong, weak, strong, and so on, and the repetition of this strength is a striped pattern on the ultrasonic image. It appears. In this case, the normalized spatial frequency of the fringes is “0.5”, and half the number of the fringes is generated. That is, fringes are generated at a rate of one for every two beams.

  In this way, since the normalized spatial frequency of fringes varies according to the number of reception beams for each transmission beam, in the present embodiment, the notch frequency according to the number of reception beams for each transmission beam (the number of simultaneous reception beams). Is set, and a filter coefficient corresponding to the notch frequency is set. The filter coefficient is set by the control unit 30 according to the number of simultaneously received beams, for example.

  FIG. 4 is a diagram for explaining filter characteristics for four-way simultaneous reception (four-way parallel reception), and FIG. 4A shows frequency characteristics of a 63-tap FIR notch filter. The number of taps of the FIR filter corresponds to the number of filter coefficients (that is, the number of multipliers 52 in FIG. 2). In the frequency characteristics shown in FIG. 4A, a notch frequency is set at the position of the normalized spatial frequency “0.25”. FIG. 4B shows a filter coefficient string of a 63 tap FIR notch filter corresponding to the frequency characteristic of FIG.

  In the present embodiment, by using a 63 tap FIR notch filter, it is possible to efficiently remove only the vicinity of the frequency component of the striped artifact included in the azimuth direction data string. That is, the amplitude suddenly becomes “0” at the position of the frequency component of the striped artifact (the position of the normalized spatial frequency “0.25” in the case of simultaneous reception in four directions), and only the narrow band component in the vicinity is removed. In other frequency regions, the amplitude is maintained at approximately “1” and passes through the filter without being attenuated.

  For reference, FIG. 4C shows frequency characteristics corresponding to the average processing of four received beams received simultaneously. This characteristic corresponds to a case where all four filter coefficients in a 4-tap FIR filter are set to ¼. As shown in FIG. 4C, even when the four received beams are averaged, the amplitude becomes “0” at the position of the normalized spatial frequency “0.25”, and the frequency component of the striped artifact can be removed. it can. However, in comparison with FIG. 4A, in FIG. 4C, frequency components in a relatively wide range centered on the normalized spatial frequency “0.25” are greatly attenuated. For this reason, the frequency component that is originally required is attenuated or removed, and the azimuth resolution of the ultrasonic image is reduced.

  FIG. 5 is a diagram for explaining filter characteristics for two-way simultaneous reception (two-way parallel reception). FIG. 5A shows frequency characteristics of a 63-tap FIR notch filter. In the frequency characteristics shown in FIG. 5A, a notch frequency is set at the position of the normalized spatial frequency “0.5”. FIG. 5B shows a filter coefficient string of a 63 tap FIR notch filter corresponding to the frequency characteristic of FIG.

  In the present embodiment, by using a 63 tap FIR notch filter, it is possible to efficiently remove only the frequency components of the striped artifacts included in the azimuth direction data string. That is, the amplitude suddenly becomes “0” at the position of the frequency component of the striped artifact (the position of the normalized spatial frequency “0.5” in the case of two-way simultaneous reception), and only the narrow band component in the vicinity is removed. In other frequency regions, the amplitude is maintained at approximately “1” and passes through the filter without being attenuated.

  For reference, FIG. 5C shows frequency characteristics corresponding to the average processing of two received beams received simultaneously. This characteristic corresponds to the case where the two filter coefficients in the 2-tap FIR filter are both set to ½. As shown in FIG. 5C, even when the two received beams are averaged, the amplitude becomes “0” at the position of the normalized spatial frequency “0.5”, and the frequency component of the striped artifact can be removed. it can. However, in comparison with FIG. 5A, in FIG. 5C, a relatively wide range of frequency components in the vicinity of the normalized spatial frequency “0.5” is greatly attenuated. For this reason, the frequency component that is originally required is attenuated or removed, and the azimuth resolution of the ultrasonic image is reduced.

  FIG. 6 is a diagram for explaining filter characteristics for three-way simultaneous reception (three-way parallel reception), and FIG. 6A shows frequency characteristics of a 63-tap FIR notch filter. In the frequency characteristic shown in FIG. 6A, a notch frequency is set at the position of the normalized spatial frequency “0.33”. FIG. 6B shows a filter coefficient string of a 63 tap FIR notch filter corresponding to the frequency characteristic of FIG.

  In the present embodiment, by using a 63 tap FIR notch filter, it is possible to efficiently remove only the frequency components of the striped artifacts included in the azimuth direction data string. That is, the amplitude sharply becomes “0” at the position of the frequency component of the striped artifact (the position of the normalized spatial frequency “0.33” in the case of simultaneous reception in three directions), and only the narrow band component in the vicinity is removed. In other frequency regions, the amplitude is maintained at approximately “1” and passes through the filter without being attenuated.

  For reference, FIG. 6C shows frequency characteristics corresponding to the average processing of three received beams received simultaneously. This characteristic corresponds to a case where all three filter coefficients in the 3-tap FIR filter are set to 1/3. As shown in FIG. 6C, even when three received beams are averaged, the amplitude becomes “0” at the position of the normalized spatial frequency “0.33”, and the frequency component of the striped artifact can be removed. it can. However, in comparison with FIG. 6A, in FIG. 6C, frequency components in a relatively wide range near the normalized spatial frequency “0.33” are greatly attenuated. For this reason, the frequency component that is originally required is attenuated or removed, and the azimuth resolution of the ultrasonic image is reduced.

Note that the notch filter may be an IIR (Infinite Impulse Response) filter. FIG. 3 is another internal configuration diagram of the BRF 40 of FIG. 1 and shows an IIR filter including a plurality of delay elements 50, a plurality of multipliers 52, and a plurality of adders 54. Also in the IIR filter, each echo data in the azimuth direction data string (time series data) input to the BRF 40 for each time phase is subjected to delay processing for one time phase by each delay element 50. Each echo data (including those after delay processing) includes predetermined filter coefficients (a ₀ , a ₁ ,..., A _n , b ₁ ,..., B _n ) in each multiplier 52. Is multiplied. Further, addition processing is executed in each adder 54.

  The filter characteristic of the IIR filter is also set by the filter coefficient as in the case of the FIR filter. That is, each filter coefficient of the IIR filter in FIG. 3 is set to have the filter characteristics shown in FIGS. 4A, 5A, and 6A, for example, according to the number of simultaneous reception beams. The

  Returning to FIG. 1, in the present embodiment, the filter coefficient in the BRF 40 is changed by the control unit 30 in accordance with the number of simultaneously received beams. For example, in the case of the four-way simultaneous reception mode, the filter coefficient is set according to the characteristic of FIG. 4A, and in the case of the two-way simultaneous reception mode, the filter coefficient is set according to the characteristic of FIG. In the case of the three-way simultaneous reception mode, the filter coefficient is set in accordance with the characteristics shown in FIG.

  The azimuth direction data string (echo data) from which the frequency component of the striped artifact is removed in the BRF 40 is stored in the frame memory C44 in the image forming unit 42. The image forming unit 42 forms an ultrasonic image (for example, a B mode image) from the echo data in the frame memory C44. The formed ultrasonic image is displayed on the display 46.

  The control unit 30 controls each unit in the ultrasonic diagnostic apparatus of FIG. In the control unit 30, a write control unit 32 and a read control unit 34 are provided, and execute write / read control of the frame memory A26, the frame memory B28, and the frame memory C44. In a series of writing and reading control, the echo data is handled as an azimuth direction data string obtained by arranging echo data of a plurality of reception beams in the azimuth direction in each scanning frame.

  FIG. 7 is a diagram for explaining a method of forming the azimuth direction data string, and FIGS. 7A to 7C correspond to three different formation methods of the azimuth direction data string, respectively. 7A to 7C show scanning frames formed by arranging a plurality of reception beams 60 in the azimuth direction. Hereinafter, a method for forming an azimuth direction data string will be described with reference to FIG.

  In the method shown in FIG. 7A, a plurality of data sequences of echo data arranged in the azimuth direction from the reception beam at one end toward the reception beam at the other end are acquired at different depths, and the acquired plurality of data sequences are acquired. Are connected to form an azimuth direction data string. At this time, echo data is extracted along the path 62. That is, after a data string arranged from one end receiving beam to the other end receiving beam at a certain depth is extracted, the data string arranged from the other end receiving beam to the one end receiving beam at a position one step deeper. Are extracted, and the same end points of the extracted data string are connected one after another to form an azimuth direction data string.

  Generally, the number of reception beams in one scanning frame is about 100 (for example, 128). Therefore, when a data string arranged from the one end receiving beam to the other end receiving beam is extracted at a certain depth, a data string consisting of about 100 data is formed. However, the FIR filter used in the BRF 40 is “the number of effective output data = the number of input data− (the number of taps−1)”. For example, in the case of 63 taps, the effective filter obtained by a data string composed of 100 data items. The output data is reduced to 38 pieces. For this reason, when the BRF 40 is used by using only one column of data arranged from the reception beam at one end toward the reception beam at the other end, a reduction in the number of effective output data becomes a problem. Therefore, as shown in FIG. 7A, a plurality of data strings are connected to form an azimuth direction data string. In the method shown in FIG. 7A, the same end points of the extracted data string are connected to each other, so that spatial continuity in the connected part is maintained.

  In the method shown in FIG. 7B, similarly to the case of FIG. 7A, each data string of echo data arranged in the azimuth direction from the reception beam at one end to the reception beam at the other end is different in depth. A plurality of acquired data strings are connected, and the acquired plurality of data strings are connected to form an azimuth direction data string. 7A differs from FIG. 7A in that echo data is extracted along the path 64 in FIG. 7B. That is, after a data string arranged from one end receiving beam to the other end receiving beam at a certain depth is extracted, a data string arranged from one end receiving beam to the other end receiving beam at a position one step deeper. Are extracted, and different end points of the extracted data string are connected one after another to form an azimuth direction data string. Since different end points are connected to each other, the FIR filter is a steep notch filter although it has poor spatial continuity in the connected portion as compared with the method of FIG. 7A, and is obtained from the echo data after filtering. In comparison of the ultrasonic images to be obtained, it is possible to expect an image quality of almost the same level as that in FIG.

  In the method shown in FIG. 7C, a predetermined number of pieces of data (a) arranged from one end of the data sequence are arranged in each data sequence of echo data arranged in the azimuth direction from the reception beam at one end to the reception beam at the other end. ... Z) is added at one end to add a predetermined number of auxiliary data (z... A) 66 to form an azimuth direction data string. In this case, the number of end point data (z... Aa... Z) obtained by the addition is preferably about the number of taps of the FIR filter. For example, in the case of a 63 tap FIR filter, 62 or 64 is desirable. In the method shown in FIG. 7C, the number of effective output data of the FIR filter can be secured by the number of beams without connecting data strings in the depth direction.

  The control unit 30 executes write / read control of the frame memory A26, the frame memory B28, and the frame memory C44 by any one of the methods described with reference to FIGS. In the frame memory A26 and the frame memory B28, echo data of a plurality of scan frames acquired sequentially are alternately stored for each scan frame via the frame selector (1) 24. For example, it is stored in the frame memory A26 when the scan frame is an odd frame, and is stored in the frame memory B28 when the scan frame is an even frame. Therefore, for example, after echo data of the first scanning frame is stored in the frame memory A26, echo data (azimuth direction data string) is output (read) from the frame memory A26 to the BRF 40 via the frame selector (2) 36. While being executed, the echo data of the second scanning frame is stored (written) in the frame memory B 28 via the frame selector (1) 24. Further, after the echo data of the second scanning frame is stored in the frame memory B28, the echo data is output from the frame memory B28 to the BRF 40 via the frame selector (2) 36, while the third scanning frame is output. The echo data is stored in the frame memory A26 via the frame selector (1) 24. Thus, when one of the frame memory A26 and the frame memory B28 is being written, the other is read.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above is only a mere illustration in all the points, and does not limit the scope of the present invention. For example, in the above-described embodiment, the case where the number of taps of the FIR filter is 63 has been described. For example, if the number of taps is about 10 taps or more, a somewhat steep filter (notch filter) can be configured. In general, as the number of taps increases, a steeper filter characteristic can be realized. Therefore, an FIR filter having 63 taps or more may be used. The number of taps may be set based on the total number of received beams in each scanning frame, the total number of echo data in each scanning frame, or the like.

1 is an overall configuration diagram of an ultrasonic diagnostic apparatus according to the present invention. It is an internal block diagram of a band rejection filter. It is another internal block diagram of a band rejection filter. It is a figure for demonstrating the filter characteristic for 4 directions simultaneous reception. It is a figure for demonstrating the filter characteristic for two-way simultaneous reception. It is a figure for demonstrating the filter characteristic for 3 directions simultaneous reception. It is a figure for demonstrating the formation method of an azimuth | direction data string. It is a figure for demonstrating parallel simultaneous reception.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Probe, 12 Transmitter circuit, 14, 16, 18, 20 Receive beam forming part, 40 band rejection filter.

Claims (7)

An ultrasonic probe including a plurality of vibration elements;
A transmission unit that electronically scans a plurality of vibration elements to form a plurality of transmission beams for each scanning frame;
A receiver that forms a plurality of receive beams for each transmit beam;
A filter unit that performs a filtering process on echo data of a plurality of reception beams;
A control unit for setting a spatial frequency component to be removed by filtering,
An image forming unit that forms an ultrasonic image from the filtered echo data;
Have
The control unit sets the spatial frequency component to be removed according to the number of reception beams for each transmission beam,
The filter unit includes a notch filter that removes the set spatial frequency component from an azimuth direction data string obtained by arranging echo data of a plurality of reception beams in the azimuth direction in each scanning frame.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The notch filter is composed of a FIR (Finite Impulse Response) filter.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The notch filter is composed of an IIR (Infinite Impulse Response) filter.
An ultrasonic diagnostic apparatus. An ultrasonic probe including a plurality of vibration elements;
A transmission unit that electronically scans a plurality of vibration elements to form a plurality of transmission beams for each scanning frame;
A receiver that forms a plurality of receive beams for each transmit beam;
A filter unit that performs a filtering process on echo data of a plurality of reception beams;
An image forming unit that forms an ultrasonic image from the filtered echo data;
Have
The filter unit removes a spatial frequency component set according to the number of reception beams for each transmission beam from an azimuth direction data string obtained by arranging echo data of a plurality of reception beams in the azimuth direction in each scanning frame. Including a notch filter,
The azimuth direction data sequence acquires a plurality of data sequences of echo data arranged in the azimuth direction from the reception beam at one end to the reception beam at the other end at different depths, and connects the acquired data sequences. Formed,
An ultrasonic diagnostic apparatus. An ultrasonic probe including a plurality of vibration elements;
A transmission unit that electronically scans a plurality of vibration elements to form a plurality of transmission beams for each scanning frame;
A receiver that forms a plurality of receive beams for each transmit beam;
A filter unit that performs a filtering process on echo data of a plurality of reception beams;
An image forming unit that forms an ultrasonic image from the filtered echo data;
Have
The filter unit removes a spatial frequency component set according to the number of reception beams for each transmission beam from an azimuth direction data string obtained by arranging echo data of a plurality of reception beams in the azimuth direction in each scanning frame. Including a notch filter,
The azimuth direction data sequence is a data sequence of echo data arranged in the azimuth direction from the reception beam at one end to the reception beam at the other end, and a predetermined number of data arranged from one end of the data sequence at one end. Formed by adding a predetermined number of auxiliary data obtained by folding,
An ultrasonic diagnostic apparatus. An ultrasonic probe including a plurality of vibration elements;
A transmission unit that electronically scans a plurality of vibration elements to form a plurality of transmission beams for each scanning frame;
A receiver that forms a plurality of receive beams for each transmit beam;
A filter unit that performs a filtering process on echo data of a plurality of reception beams;
An image forming unit that forms an ultrasonic image from the filtered echo data;
Have
The filter unit includes a notch filter that removes a spatial frequency component corresponding to a striped artifact from an azimuth direction data string obtained by arranging echo data of a plurality of reception beams in the azimuth direction in each scanning frame,
Switch the type of fringe artifact to be removed according to the number of receive beams for each transmit beam,
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 6,
Depending on the number of received beams for each transmit beam, the type of striped artifacts to be removed is striped artifacts due to differences in reception sensitivity between multiple received beams, and striped patterns due to the strength of correlation between received beams. Switching between artifacts,
An ultrasonic diagnostic apparatus.

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