JP7192404B2 - ULTRASOUND DIAGNOSTIC APPARATUS, ULTRASOUND DIAGNOSTIC SYSTEM CONTROL METHOD, AND ULTRASOUND DIAGNOSTIC SYSTEM CONTROL PROGRAM - Google Patents

Description

The present disclosure relates to an ultrasonic diagnostic apparatus, an ultrasonic diagnostic apparatus control method, and an ultrasonic diagnostic apparatus control program.

2. Description of the Related Art Conventionally, an ultrasonic diagnostic apparatus using a parallel reception system is known.

1 and 2 are diagrams for explaining the parallel reception method.

In the parallel reception method, when one ultrasonic beam (Tx1 in FIG. 1) is transmitted into the subject, a plurality of reflected wave beams (Rx1, Rx2, Rx3, Rx4 in FIGS. 1 and 2) are received in parallel at the same time. 1A and 2A show a mode in which four reflected wave beams are simultaneously received per ultrasonic beam.

In the parallel reception method, when one ultrasonic beam is transmitted, the ultrasonic probe P20 receives a plurality of reflected wave beams on both sides centering on the beam center position of the ultrasonic beam. Then, the reception processing unit of the ultrasonic diagnostic apparatus performs phasing addition for each reflected wave beam based on the reception signals output from each of the plurality of piezoelectric transducers provided in the ultrasonic probe P20. Reception beam data is generated for each wave beam, and a plurality of reception beam data are obtained simultaneously from one ultrasonic beam.

Then, in this type of ultrasonic diagnostic apparatus, the position of the ultrasonic beam transmitted from the ultrasonic probe P20 (that is, the aperture) is set in units of blocks of a plurality of reflected wave beams obtained from one ultrasonic beam, One frame data (two-dimensional data) forming an ultrasonic image is generated by shifting along the scanning direction.

The parallel reception method thus increases the amount of data per unit time and improves the frame rate.

A data string generated by one reflected wave beam is hereinafter referred to as a "reception beam" or "reception beam data". Also, a plurality of reception beam data obtained simultaneously for one ultrasonic beam is called a "reception beam block" or a "reception beam data block".

JP 2005-323894 A

By the way, in the parallel reception method, a difference in signal strength of received signals is likely to occur between two adjacent receiving beams, and this causes striped artifacts (hereinafter referred to as “striped artifacts”) in an ultrasonic image. ”) appears.

FIG. 3 is a diagram showing an example of striped artifacts occurring in an ultrasound image. In FIG. 3, striped artifacts appear in the lower left area of the screen. Note that the striped artifact is a brightness gradation that extends along the distance direction (that is, the depth direction) and periodically appears along the azimuth direction (that is, the scanning direction) in the ultrasonic image. .

FIG. 1B shows the streak artifact that occurs between two adjacent receive beam blocks. The signal intensity graph shown in FIG. 1B shows the distribution of the signal intensity of each reception beam at the same depth position.

In the parallel reception method, as shown in FIG. 1B, when one ultrasonic beam is transmitted, the beam center of the ultrasonic beam is the center, and as the distance from the beam center of the ultrasonic beam increases, the reflected wave beam strength becomes smaller. Therefore, between two adjacent receive beam blocks, an area where the signal strength of the receive beam is small is generated, and as a result, striped artifacts occur in the period of the receive beam blocks (hereinafter referred to as " fringe artifacts occurring between receive beam blocks").

In this regard, Patent Literature 1 describes that, in order to remove the striped artifacts that occur between received beam blocks, the frequency components of the striped artifacts are uniformly removed from the ultrasonic image by filtering. ing.

However, since the stripe artifact depends on the difference in the signal intensity of each received beam, it does not occur uniformly throughout the ultrasound image, and even within the ultrasound image, there are areas where the stripe artifact is likely to occur and areas where it is less likely to occur. (For example, stripe artifacts are more likely to occur at positions with greater depth in the distance direction). In addition, depending on the area of the ultrasound image, the frequency band of the stripe artifact may not overlap with the frequency band containing information on the biological tissue within the subject (hereinafter abbreviated as “biological information”).

Therefore, if filter processing is uniformly performed on the entire ultrasound image as in Patent Document 1, the spatial resolution of the ultrasound image may be degraded, and necessary biological information may also be degraded. be.

FIG. 2B shows a fringe artifact occurring anywhere within the receive beam block. The signal intensity graph shown in FIG. 2B shows the distribution of the signal intensity of each reception beam at the same depth position.

In the parallel reception method, as shown in FIG. 2B, when a biological tissue Q exists, when one ultrasonic beam is transmitted, the reflection direction of the reflected wave beam from the biological tissue Q is in the distance direction. may be slanted. In such a case, even within the same receive beam block, a difference in signal strength occurs between receive beams depending on the position of the receive beam within the receive beam block. Due to this, a striped artifact occurs within the receive beam block (hereinafter referred to as "striped artifact occurring within the receive beam block").

Note that in FIG. 2B, the difference in signal strength is large between the third receive beam and the fourth receive beam in each receive beam block, and in this case, the period of one receive beam block striped artifacts occur. However, since the striped artifact in this case is superimposed on the striped artifact occurring between the receiving beam blocks, it becomes an aspect (for example, thick line shape) with the striped artifact occurring between the receiving beam blocks.

In addition, when the number of receiving beams is four or more, the striped artifacts that occur when living tissue exists have the same period as the striped artifacts that occur between the receiving beam blocks, but the number of receiving beams is less than four. In the case of , the period is different from that of the fringe artifacts that occur between receive beambooks.

The present disclosure has been made in view of the above problems, and an ultrasonic diagnostic apparatus that can suppress stripe artifacts while reducing deterioration of biological information in an ultrasonic image, and an ultrasonic diagnostic apparatus. A first object of the present invention is to provide a control method and a control program for an ultrasonic diagnostic apparatus. A second object of the present disclosure is to provide an ultrasonic diagnostic apparatus, an ultrasonic diagnostic apparatus control method, and an ultrasonic diagnostic apparatus control program capable of suppressing stripe artifacts occurring between reception beam blocks. and Furthermore, a third object of the present disclosure is to provide an ultrasonic diagnostic apparatus capable of suppressing striped artifacts occurring in a receive beam block, an ultrasonic diagnostic apparatus control method, and an ultrasonic diagnostic apparatus control program. and

The main disclosure that solves the above-mentioned problems is
An ultrasonic diagnostic apparatus for imaging information within a subject using an ultrasonic probe,
a transmitting/receiving unit that causes the ultrasonic probe to transmit/receive ultrasonic waves so as to generate a plurality of received beam data per ultrasonic beam;
an image generating unit that generates an ultrasonic image based on a plurality of received beam data generated when the ultrasonic probe scans the interior of the subject with ultrasonic waves;
For each region in the ultrasonic image, a filter to be applied is selectively determined from among a plurality of filters having mutually different frequency characteristics, and for each region, the determined filter is used to produce a striped artifact a filtering unit that performs filtering to reduce
An ultrasonic diagnostic apparatus comprising:

Also, in other aspects,
A control method for an ultrasonic diagnostic apparatus for imaging information within a subject using an ultrasonic probe,
A process of causing the ultrasonic probe to transmit and receive ultrasonic waves so as to generate a plurality of received beam data per ultrasonic beam;
A process of generating an ultrasonic image based on a plurality of received beam data generated when the ultrasonic probe scans the interior of the subject with ultrasonic waves;
For each region in the ultrasonic image, a filter to be applied is selectively determined from among a plurality of filters having mutually different frequency characteristics, and for each region, the determined filter is used to produce a striped artifact a process of filtering to reduce the
is a control method comprising

Also, in other aspects,
A control program that causes an ultrasonic diagnostic apparatus that uses an ultrasonic probe to image information within a subject to perform processing,
A process of causing the ultrasonic probe to transmit and receive ultrasonic waves so as to generate a plurality of received beam data per ultrasonic beam;
A process of generating an ultrasonic image based on a plurality of received beam data generated when the ultrasonic probe scans the interior of the subject with ultrasonic waves;
For each region in the ultrasonic image, a filter to be applied is selectively determined from among a plurality of filters having mutually different frequency characteristics, and for each region, the determined filter is used to produce a striped artifact a process of filtering to reduce the
is a control program comprising

According to the ultrasonic diagnostic apparatus according to the present disclosure, striped artifacts can be suppressed while reducing deterioration of biological information in an ultrasonic image.

Diagram explaining the parallel reception method Diagram explaining the parallel reception method A diagram showing an example of a striped artifact that occurs in an ultrasound image 1 is a diagram showing the appearance of an ultrasonic diagnostic apparatus according to a first embodiment; FIG. 1 is a block diagram showing an example of the overall configuration of an ultrasonic diagnostic apparatus according to a first embodiment; FIG. FIG. 4 is a diagram showing a mode of ultrasonic scanning in the transmitting/receiving unit according to the first embodiment; FIG. 4 is a diagram showing a mode of ultrasonic scanning in the transmitting/receiving unit according to the first embodiment; FIG. 4 is a diagram schematically showing processing in a filter processing unit according to the first embodiment; A diagram showing the relationship between the frequency band of biological information and striped artifacts contained in an ultrasound image (FIG. 9A) and the frequency characteristics of various filters (FIGS. 9B to 9D) Diagram explaining an example of how to set a Gabor filter A diagram showing the filter characteristics of a Gabor filter in which the directional direction is set only in the azimuth direction. A diagram showing an example of a parameter table for determining the type of filter in the filter table Diagram showing the relationship between the position in the ultrasound image and the frequency characteristics of the applied filter A diagram showing an example of a data table for selecting a parameter table to be applied based on the probe type and imaging mode. Flowchart showing the operation of the ultrasonic diagnostic apparatus according to the first embodiment Flowchart showing the operation of the ultrasonic diagnostic apparatus according to the first embodiment An ultrasonic image (FIG. 17A) when striped artifact suppression processing is not performed by the filter processing unit according to the second embodiment, and an ultrasound image when striped artifact suppression processing is performed by the filter processing unit (FIG. 17A). 17B) in comparison FIG. 11 is a diagram schematically showing striped artifact detection processing by a filter processing unit according to the second embodiment; Flowchart showing the operation of the ultrasonic diagnostic apparatus according to the second embodiment

Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functions are denoted by the same reference numerals, thereby omitting redundant description.

(First embodiment)
[Overall Configuration of Ultrasound Diagnostic Apparatus]
An example of the overall configuration of the ultrasonic diagnostic apparatus according to the present embodiment will be described below with reference to FIGS. 4 to 7. FIG.

FIG. 4 is a diagram showing the appearance of the ultrasonic diagnostic apparatus 1 according to this embodiment. FIG. 5 is a block diagram showing an example of the overall configuration of the ultrasonic diagnostic apparatus 1 according to this embodiment. 6 and 7 are diagrams showing aspects of ultrasonic scanning in the transmitting/receiving section 11 according to the present embodiment.

An ultrasonic diagnostic apparatus 1 according to this embodiment is configured by attaching an ultrasonic probe 20 to a main body 10 of the ultrasonic diagnostic apparatus 1 . Note that the main body 10 and the ultrasonic probe 20 are electrically connected via a cable.

A main body 10 of the ultrasonic diagnostic apparatus 1 includes a transmission/reception section 11, a control section 12, an image generation section 13, a filter processing section 14, a digital scan converter 15, a display section 16, an operation input section 17, and a filter table DF. there is

The ultrasonic probe 20 includes a plurality of piezoelectric transducers 21-T1 to 21-T1024 (here, 1024 piezoelectric transducers) that perform mutual conversion between ultrasonic waves and electric signals, and a plurality of piezoelectric transducers 21 It includes a channel switching unit (not shown) for individually switching and controlling the ON/OFF of the driving state of the . The plurality of piezoelectric transducers 21 individually convert voltage pulses generated by the transmitting/receiving unit 11 into ultrasonic beams and transmit the ultrasonic beams into the subject, and the ultrasonic beams are reflected within the subject. It receives the reflected wave beam generated by the transmission, converts it into an electrical signal, and outputs it to the transmitting/receiving section 11 .

The plurality of piezoelectric vibrators 21 are arranged, for example, in an array along the scanning direction. The ON/OFF states of the drive states of the plurality of piezoelectric vibrators 21 are controlled by the control unit 12 individually or in units of blocks, and sequentially switched along the scanning direction. As a result, the ultrasonic probe 20 transmits and receives ultrasonic waves so as to scan the inside of the subject.

The transmission/reception unit 11 is a transmission/reception circuit that causes the piezoelectric transducer 21 of the ultrasonic probe 20 to transmit and receive ultrasonic waves.

The transmission/reception unit 11 includes a transmission unit 11a that generates a voltage pulse (hereinafter referred to as a “driving signal”) and sends it to the piezoelectric transducer 21, and an electric signal ( and a receiving section 11b for receiving and processing a received signal (hereinafter referred to as a "received signal"). Under the control of the control unit 12, the transmission unit 11a and the reception unit 11b each cause the piezoelectric transducer 21 to transmit and receive ultrasonic waves.

The transmission unit 11 a includes, for example, a pulse oscillator and a pulse setting unit provided for each channel connected to the piezoelectric vibrator 21 . The transmission unit 11 a adjusts the voltage pulse generated by the pulse oscillator to the voltage amplitude, pulse width, and timing set by the pulse setting unit, and transmits the voltage pulse to the piezoelectric vibrator 21 . In addition, the transmission unit 11a appropriately sets a delay time for each channel so that the ultrasonic waves output from each piezoelectric transducer 21 are focused in a beam shape, and transmits a drive signal to each piezoelectric transducer 21. supply.

The receiving unit 11b includes, for example, a preamplifier, an AD converter, and a reception beamformer. A preamplifier and an AD converter are provided for each channel connected to the piezoelectric vibrator 21, amplify weak reception signals, and convert the amplified reception signals (analog signals) into digital signals. The reception beamformer phasing-adds the reception signals (digital signals) of the piezoelectric transducers 21 to combine the reception signals D<b>1 of the plurality of piezoelectric transducers 21 into one, and outputs the signal to the image generation unit 13 .

The receiving unit 11b has, for example, a plurality of receiving beamformers provided in parallel, and is configured to be able to perform parallel simultaneous receiving processing. The receiving unit 11b obtains a plurality of reception beams from one ultrasonic beam by, for example, setting different focal positions for each of the plurality of reception beamformers. Further, the receiving unit 11b is configured so that the number of beams to be parallel-received for one ultrasonic beam can be changed.

The control unit 12 controls the channel switching unit of the ultrasonic probe 20 to determine the plurality of piezoelectric transducers 21 to be driven, and controls the transmission/reception unit 11 to select the plurality of piezoelectric transducers 21 to be driven. to transmit and receive ultrasonic waves. The control unit 12 scans the interior of the subject with ultrasonic waves by sequentially driving the plurality of piezoelectric transducers 21 in the ultrasonic probe 20 .

At this time, the control unit 12 determines the transmission position and transmission method of the ultrasonic beams by controlling the number and positions of the piezoelectric transducers 21 (that is, the transmission aperture) used for transmission of the ultrasonic beams, for example. Further, the control unit 12 controls, for example, the number and positions of the piezoelectric transducers 21 (that is, the reception aperture) used when receiving the reception beams, thereby adjusting the reception positions and parallelism of the reception beams received by the ultrasonic probe 20 . Determine the reception method such as the number of beams to be received.

The control unit 12 controls the number of beams to be parallel-received per one ultrasonic beam set in the operation input unit 17, the type of the ultrasonic probe 20 (for example, the compex type, the sector type, or the like), the intra-subject The transmission/reception conditions of the transmission/reception unit 11 are determined based on the depth of the object to be imaged, the imaging mode (for example, B mode, C mode, or E mode), and the like. The control unit 12 also transmits these pieces of information to the filter processing unit 14 as well.

The image generation unit 13 acquires the reception signal D1 at each scanning position output from the transmission/reception unit 11, sequentially accumulates the reception signal D1 in a line memory, and generates two-dimensional data in frame units. The two-dimensional data is composed of signal intensity information and the like at each position in the cross section of the subject along the scanning direction and the depth direction.

Then, the image generator 13 generates image data related to the ultrasonic image D2 (hereinafter abbreviated as “ultrasonic image D2”) based on the two-dimensional data. The image generation unit 13 converts, for example, sampling data (for example, signal strength of a received signal) at each position in a cross section along the scanning direction and the depth direction into pixel values, and converts them into pixel values for one-frame B-mode display. A sound wave image D2 is generated. Then, the image generation unit 13 generates such an ultrasound image D2, for example, each time the transmission/reception unit 11 scans the inside of the subject.

The filtering unit 14 acquires the ultrasonic image D2 generated by the image generating unit 13, and converts image data (hereinafter referred to as , abbreviated as “ultrasound image D3”) is output to the subsequent stage.

At this time, the filter processing unit 14 determines the type of filter for extracting the striped artifact generated in each region in the ultrasonic image D2, and uses the determined type of filter for each region. filtered. Filter data used by the filter processing unit 14 is stored in the filter table DF, and the filter processing unit 14 selects one of the filters stored in the filter table DF for each region to be filtered. as the filter to use. Details of the processing of the filter processing unit 14 will be described later.

The image generation unit 13 and the filter processing unit 14 according to this embodiment are realized by a digital arithmetic circuit configured by a DSP (Digital Signal Processor), for example. However, part or all of these may be realized by a CPU (Central Processing Unit) performing arithmetic processing according to a program.

A digital scan converter 15 acquires image data related to the filtered ultrasonic image D3 from the filtering unit 14, and converts the image data of the ultrasonic image D3 into a television signal on the display unit 16. It is converted into image data for display according to the scanning method (that is, display image D4). In the digital scan converter 15, even if general-purpose image processing such as gradation correction is performed on the ultrasonic image D3 before the filtered ultrasonic image D3 is converted into the display image D4. good.

The display unit 16 is, for example, a display such as an LCD (Liquid Crystal Display). The display unit 16 acquires the display image D4 from the digital scan converter 15 and displays the display image D4.

The operation input unit 17 is, for example, a keyboard or a mouse, and acquires an operation signal input by an operator. The operation input unit 17, for example, based on the user's operation input, the type of the ultrasonic probe 20, the number of beams to be parallel received, the type of the subject (that is, the type of living tissue), the depth of the imaging target in the subject Alternatively, an imaging mode (for example, B mode, C mode, or E mode) or the like can be set.

The transmitting/receiving unit 11 according to this embodiment employs the parallel receiving method as described above.

FIG. 6A shows a mode of ultrasound scanning when four-beam parallel simultaneous reception is performed. Also, FIG. 6B shows the distribution of signal strength of reception beam blocks generated when four beam parallel simultaneous reception is performed. Note that T1 to T6 shown in FIGS. 6A and 6B respectively represent reflected wave beams and received beam data thereof received when one ultrasonic beam is transmitted.

In the case of four-beam parallel simultaneous reception, as shown in FIG. 6A, each time one ultrasonic beam is transmitted, the ultrasonic probe 20 has two probes on each side centering on the position of the ultrasonic beam. , a total of four reflected wave beams are received. At this time, the receiver 11b simultaneously acquires four pieces of reception beam data (reception beam data blocks) from the reception signal obtained by one ultrasonic beam.

Then, the control unit 12 sets the transmission aperture so that the center axis of the ultrasonic beam transmitted the second time moves from the center axis of the ultrasonic beam transmitted the first time by the width of the four reflected wave beams in the scanning direction. to select. By repeating this process, the control unit 12 performs ultrasonic scanning in order of T1, T2, T3, T4, T5, and T6.

FIG. 7A shows a mode of ultrasound scanning when performing 8-beam parallel simultaneous reception. Also, FIG. 7B shows the signal strength distribution of the reception beam data block generated when 8-beam parallel reception is performed. Note that T11 to T14 shown in FIGS. 7A and 7B respectively represent reflected wave beams and received beam data thereof received when one ultrasonic beam is transmitted.

As shown in FIGS. 6B and 7B, also in the ultrasonic diagnostic apparatus 1 according to the present embodiment, stripe artifacts corresponding to the number of parallel-received beams appear in the ultrasonic image D2 between two adjacent reception beam blocks. will occur in between. In addition, in the ultrasonic diagnostic apparatus 1 according to the present embodiment as well, the position of any of the reception beams in the reception beam block is displayed in the ultrasonic image D2 based on the positional relationship with the living tissue in the subject. banding artifacts will occur (see FIG. 2).

From this point of view, the ultrasonic diagnostic apparatus 1 according to this embodiment suppresses these striped artifacts in the filtering unit 14 .

[Configuration of filter processing part]
Next, the configuration of the filter processing unit 14 will be described with reference to FIGS. 8 to 14. FIG.

FIG. 8 is a diagram schematically showing processing in the filter processing unit 14. As shown in FIG.

The filtering unit 14 has, for example, a striped artifact extraction unit 14a and a striped artifact removal unit 14b.

For example, the striped artifact extracting unit 14a sets a region to be filtered (hereinafter referred to as a “processing target region D2a”) so as to raster scan the ultrasonic image D2, and for each processing target region D2a , filter processing using a filter DFa for extracting striped artifacts. Thereby, the component of the striped artifact included in the processing target area D2a is extracted. The size of the processing target area D2a may be arbitrary, but is set to, for example, 15 pixels×15 pixels.

The filtering process in the striped artifact extracting unit 14a can be performed, for example, by convolution integration between the ultrasonic image D2 and a filter function (here, a Gabor function to be described later). Specifically, the striped artifact extraction unit 14a multiplies the pixel values of the target pixel and the peripheral pixels (peripheral pixels included in the filter size) included in the processing target region D2a by the filter coefficients determined by the filter DFa, Furthermore, the result of summing these is calculated as a filter output value. As a result, the striped artifact component present in the pixel of interest in the region D2a to be processed is extracted as the filter output value.

The striped artifact removal unit 14b subtracts the filter output value of the pixel of interest extracted by the striped artifact extraction unit 14a from the pixel value of the pixel of interest in the original processing target region D2a to obtain the filtered ultrasonic image. Stored as the pixel value of the pixel of interest in D3. As a result, the data of the ultrasonic image D3 is generated in which the striped artifact component is removed from the pixel of interest in the processing target region D2a.

The processing of the striped artifact extracting unit 14a and the striped artifact removing unit 14b as described above is executed in each processing target region D2a in the ultrasonic image D2, thereby removing the striped artifact from the ultrasonic image D2. An ultrasound image D3 is generated.

The filter DFa applied by the filtering unit 14 to each processing target region D2a is typically a striped artifact occurring between receive beam blocks (see FIG. 1) or a striped artifact occurring within a receive beam block (see FIG. 1). (See FIG. 2).

From this point of view, the filter DFa applied by the filter processing unit 14 to each processing target region D2a typically eliminates striped artifacts (that is, linear portions extending along the distance direction of the ultrasonic image D2, It is preferable to have a directivity in the extraction direction so that only periodic occurrences in the azimuth direction are extracted. In other words, the filter DFa captures striped pixel value changes (that is, periodicity) in the azimuth direction of the ultrasonic image, and the striped pixel values are continuous in the distance direction of the ultrasonic image. It is desirable that it is a function that captures what is being done. The filter DFa is expressed by, for example, a Gabor function, a wavelet function, or a rectangular wave function. (also called Gabor filter) is used.

However, the manner in which the stripe artifact is expressed depends on the transmission/reception conditions of the transmission/reception unit 11, the depth within the subject, the type of biological tissue within the subject, the positional relationship with the biological tissue within the subject, and the like. It differs for each processing target area D2a in the image D2. Further, the frequency characteristics of the filter DFa to be applied to the processing target region D2a also differ depending on the frequency band of the biological information included in the processing target region D2a (described later with reference to FIG. 13). Therefore, the filtering unit 14 determines a filter DFa to be applied from the filter table DF for each processing target area D2a in the ultrasonic image D2, and performs filtering using the determined filter DFa.

At this time, for each processing target region D2a, the filter processing unit 14 selectively reads out a filter having a desired frequency characteristic from a filter table DF pre-stored in a ROM or the like, for example, so that the processing target region D2a is filtered. A filter with a desired frequency characteristic is applied for each. The filter table DF stores, for example, a plurality of filters set with reference to a frequency band to be filtered in the azimuth direction and a frequency band to be filtered in the distance direction. These filters are, for example, the number of beams to be received in parallel, the type of ultrasonic probe (for example, linear type, compex type, sector type, etc.), and the type of imaging mode of the ultrasonic diagnostic apparatus 1. (eg, B mode, color flow mode, M mode, etc.), etc., and stored in the filter table DF.

The filter processing unit 14 determines the transmission/reception conditions of the transmission/reception unit 11, the depth in the subject, the type of the biological tissue in the subject, and the type of biological tissue in the subject by the input operation or automatic detection by the operation input unit 17. By setting the information such as the positional relationship, each position of the processing target region D2a in the ultrasonic image D2 (for example, the X coordinate and Y coordinate of the center position of the region) is stored in the filter table DF. A filter DFa to be applied to the processing target region D2a is selectively determined from among the plurality of filters.

The frequency characteristics required for filters for removing stripe artifacts in the ultrasound image D2 will be described in detail below.

FIG. 9 is a diagram showing the relationship between the frequency band F1 of biological information and the frequency band F2 of stripe artifacts (FIG. 9A) contained in an ultrasound image D2 and the frequency characteristics of various filters (FIGS. 9B to 9D). be. 9A to 9D, the vertical axis is the frequency axis in the distance direction, and the horizontal axis is the frequency axis in the azimuth direction. 9B-9D are shown on the same scale as FIG. 9A.

As shown in FIG. 9A, the frequency band F2 of the stripe artifact occurs on the high frequency side with respect to the frequency band F1 of the biometric information, but in many cases part of it overlaps the frequency band F1 of the biometric information. Therefore, depending on how the striped artifact is removed, biometric information may be degraded. However, the frequency band F2 in which the striped artifact appears varies depending on the transmission/reception conditions of the ultrasonic waves as described above, and also varies depending on the degree of occurrence of the striped artifact within the received beam block.

FIG. 9B is a diagram showing frequency characteristics of a general low-pass filter. FIG. 9C is a diagram showing frequency characteristics of a general notch filter. FIG. 9D is a diagram showing the frequency characteristics of the Gabor filter applied by the filter processing unit 14 according to this embodiment. In addition, the area of Fa in FIGS. 9B to 9D represents the frequency area that remains in the ultrasonic image D2 after filtering, and the area of Fb is the frequency area that is removed from the ultrasonic image D2 after filtering. show.

As can be seen from FIG. 9B, when striped artifacts are removed by applying a general low-pass filter, all biological information in the high-frequency band is lost. Also, as can be seen from FIG. 9C, when a general notch filter is applied to remove the striped artifacts, although it is possible to select the frequency band, the frequency band is changed in both the azimuth direction and the distance direction. Since selectivity cannot be maintained, part of the biological information (for example, high-frequency components in the distance direction) is lost.

In this regard, the Gabor filter is a filter that has frequency selectivity in both the azimuth direction and the distance direction, as shown in FIG. 9D. Therefore, when the striped artifact is removed by applying the Gabor filter, loss of biometric information can be minimized.

FIG. 10 is a diagram explaining a method of setting a Gabor filter. FIG. 11 is a diagram showing filter characteristics of a Gabor filter in which the directional direction is set only in the azimuth direction.

A Gabor filter is represented by a product of a Gaussian function and a sine wave (or cosine wave), and is a filter using a Gabor function that has a filtering function of extracting a desired spatial frequency feature quantity in a specified direction. A Gabor function is generally represented by the following equation (1).

In equation (1), λ is the wavelength (i.e., spatial frequency), σ _x is the extraction bandwidth of frequencies in the x direction, σ _y is the extraction bandwidth of frequencies in the y direction, and θ is the pointing direction, and these parameters are A desired spatial frequency can be extracted in an arbitrary direction by making an appropriate selection. Note that the phase offset is omitted here.

The directional direction θ represents the angle formed with the x-axis, and the Gabor filter has an edge in the vertical direction (parallel to the y-axis, that is, the distance direction) when θ=0 degrees, and a horizontal direction (parallel to the y-axis, that is, the distance direction) when θ=90 degrees. Edges along the x-axis (parallel to the azimuthal direction) can be extracted.

Since the filter DFa according to the present embodiment extracts striped artifacts extending parallel to the distance direction, the directivity direction θ of the Gabor filter applied to the filter DFa is typically θ=0 degrees.

Then, as shown in FIG. 10, the Gabor filter applied to the filter DFa has a wavelength λ, x direction The frequency extraction bandwidth σ _x and the y-direction frequency extraction bandwidth σ _y are appropriately set.

Note that FIG. 11A shows the filter characteristics of a Gabor filter set to λ (wavelength)=5 and θ (directional direction)=0 degrees, and FIG. represents the filter characteristics of a Gabor filter set to degrees.

FIG. 12 is a diagram showing an example of a parameter table for determining the filter DFa in the filter table DF. FIG. 12A is a parameter table showing an example of the relationship between the number of parallel-received beams and the extraction center frequency in the azimuth direction of the applied filter DFa. FIG. 12B is a parameter table showing an example of the relationship between the position within the ultrasound image D2 and the extraction bandwidth of the applied filter DFa.

FIG. 13 is a diagram schematically showing the parameter table of FIG. 12B. Note that F1 in FIG. 13 represents the frequency band of the biological information included in the ultrasonic image D2, and Fb represents the extraction band extracted by the filter DFa.

In the striped artifact removal process in the filtering unit 14, there is a trade-off relationship between the suppression effect of striped artifacts and the degree of degradation of biometric information. That is, the wider the extraction bandwidth of the filter DFa, the more the striped artifact can be suppressed, but the biometric information is also degraded. On the other hand, if the extraction bandwidth of the filter DFa is narrowed, deterioration of biometric information is suppressed, but the ability to suppress striped artifacts is also lowered. Therefore, the characteristics of the filter DFa applied to the processing target region D2a are determined by considering both the frequency characteristics of the striped artifacts occurring in the processing target region D2a and the frequency characteristics of the biological information included in the processing target region D2a. preferably determined.

The mode of the striped artifacts changes based on the transmission/reception conditions of the transmitter/receiver 11. Typically, the stripe artifacts occurring between the reception beam blocks are shifted to the lower frequency side as the number of beams for parallel reception increases. , and the lower the number of beams, the higher the frequency.

Moreover, the striped artifact that occurs in the received beam block changes according to the type of biological tissue in the subject, or the positional relationship (for example, tilt angle or distance) between the biological tissue and the ultrasonic probe 20. . For example, the striped artifact is less likely to occur in a received beam from a biological tissue extending in a planar shape, but is more likely to occur in a received beam from a living tissue extending in a curved surface. It is likely to occur in the tissue boundary area (edge).

On the other hand, the biometric information in the ultrasound image D2 typically contains less high-frequency band information toward the edge of the image in the ultrasound image. Specifically, as the depth in the distance direction increases, the center frequency of the ultrasonic beam decreases. is no longer included in the high frequency band of In addition, since the transmission aperture becomes narrower and the beam width of the transmitted ultrasonic wave widens toward both ends of the image in the azimuth direction, the biometric information in the ultrasonic image D2 is higher in the azimuth direction in the image regions on both ends of the image in the azimuth direction. not included in the frequency band.

Note that the number of beams to be parallel-received and the frequency band of biological information to be obtained vary depending on the type of probe, the imaging mode, etc. Therefore, in the filter table DF, the parameter tables in FIGS. and preferably provided separately for each imaging mode.

FIG. 14 is a diagram showing an example of a data table for selecting a parameter table to be applied based on the probe type and imaging mode. In FIG. 14, probes 1, 2 and 3 represent types of probes such as linear probes, convex probes and sector probes. Mode 1, mode 2, and mode 3 represent imaging modes such as B mode, Color Flow mode, and elasticity mode, for example.

From the above point of view, the filtering unit 14 determines a filter DFa to be applied to each processing target region D2a in the ultrasound image D2 from the filter table DF as follows.

First, the filtering unit 14 determines the parameter table to be applied based on the probe type and imaging mode (see FIG. 14).

Next, the filter processing unit 14 determines the central frequency in the azimuth direction to be extracted by the filter DFa based on the number of parallel-received beams (see FIG. 12A).

Then, the filter processing unit 14 considers that the frequency band of the striped artifacts overlaps the frequency band of the biological information to a large extent, and the filter DFa applied to the central region D2a of the ultrasonic image D2 is The extraction bandwidth is narrowed in any direction in the distance direction to reduce the degree of degradation of biometric information (R1 area in FIG. 13A). In addition, the filter processing unit 14 considers that the amount of overlap of the frequency band of the stripe artifact with the frequency band of the biometric information is small for the filter DFa applied to the image edge region D2a in the azimuth direction of the ultrasonic image D2. to widen the extraction bandwidth in the azimuth direction and reliably suppress the streak artifact (region R2 in FIG. 13A). Further, the filter processing unit 14 determines that the amount of overlap of the frequency band of the stripe artifact with the frequency band of the biological information is small for the filter DFa applied to the region D2a of the position where the depth in the distance direction of the ultrasonic image D2 is deep. Considering this, the extraction bandwidth in the distance direction is widened to increase the degree of suppression of the striped artifact in the distance direction (region R3 in FIG. 13A). In addition, the filter processing unit 14 widens the extraction bandwidths in both the distance direction and the azimuth direction for the filter DFa applied to the region D2a at the image edge in the azimuth direction of the ultrasonic image D2 and having a deep depth in the distance direction ( R4 region in FIG. 13A).

Note that the filter processing unit 14 preferably widens the extraction bandwidth in the area of the edge of the biological tissue in the ultrasonic image D2 because the stripe artifact is enhanced.

Furthermore, the filter processing unit 14 shifts the center frequency determined based on the number of receive beams for parallel reception to the high frequency side in a region where there is a possibility that stripe artifacts appear in the receive beam flock. However, there are cases where the striped artifacts occurring between the received beam blocks become invisible due to the striped artifacts occurring within the received beam blocks. The center frequency may be shifted to the low frequency side.

In this way, the filter processing unit 14, for each processing target region D2a (for example, the X coordinate and Y coordinate of the pixel of interest in the processing target region D2a) in the ultrasonic image D2, selects a filter to be applied to the processing target region D2a. Calculate the frequency characteristics of Then, the filter processing unit 14 selects a filter that matches the calculated frequency characteristic from the filter table DF, and determines it as the filter DFa to be applied to the processing target region D2a. Then, the filtering unit 14 uses the determined filter DFa to perform filtering on the processing target region D2a.

However, the filter DFa to be applied to the processing target region D2a within the ultrasonic image D2 may be determined based on the state of the generated ultrasonic image D2. In particular, such an aspect is preferable because the striped artifact that occurs in the received beam block also depends on the positional relationship with the living tissue in the subject.

On the other hand, it is desirable that the degree to which the filter processing unit 14 removes the striped artifact from the ultrasonic image D2 can be set and changed by the operation input unit 17 or the like. This makes it possible to prevent the biometric information from being excessively degraded when the striped artifact is removed by the filter processing unit 14 .

In this way, the filter processing unit 14 does not uniformly use the same filter for the entire area of the ultrasonic image D2, but applies a filter DFa having a different frequency characteristic for each processing target area D2a of the ultrasonic image D2. By doing so, it is possible to remove only the striped artifact while suppressing the deterioration of the spatial resolution of the biological information.

[Operation Flow of Ultrasound Diagnostic Apparatus]
Next, an example of the operation of the ultrasonic diagnostic apparatus 1 according to this embodiment will be described with reference to FIGS. 15 to 17. FIG.

15 and 16 are flowcharts showing the operation of the ultrasonic diagnostic apparatus 1 according to this embodiment. FIG. 16 shows the subroutine processing of step S6 of FIG. The flowcharts shown in FIGS. 15 and 16 are executed, for example, by each part of the ultrasonic diagnostic apparatus 1 according to a computer program.

FIG. 17 shows an ultrasonic image D4 ( FIG. 17A ) when the striped artifact suppression process is not performed by the filter processing unit 14 according to the present embodiment, and an ultrasound image D4 ( FIG. 17A ) when the striped artifact suppression process is performed by the filter processing unit 14 according to the present embodiment. FIG. 17B is a diagram showing an ultrasound image D4 (FIG. 17B) for comparison;

First, the ultrasonic diagnostic apparatus 1 sets transmission conditions such as an image mode (B mode or color Doppler mode) and the type of the ultrasonic probe 20 (step S1), and sets reception conditions such as the number of beams to be parallel-received. Set (step S2). Then, the ultrasonic diagnostic apparatus 1 determines a filter DFa to be applied to each processing target area D2a in the ultrasonic image D2 based on the transmission conditions and reception conditions set in steps S1 and S2 (step S3).

Next, the ultrasonic diagnostic apparatus 1 causes the ultrasonic probe 20 to transmit and receive ultrasonic waves based on the transmission conditions and reception conditions set in steps S1 and S2, and acquires image data of an ultrasonic image D2. (Step S4), striped artifact suppression processing is applied to the image data of the ultrasonic image D2 (Step S5).

The striped artifact suppression process shown in step S5 is based on the processes of steps S51 to S57 as shown in FIG. First, the ultrasonic diagnostic apparatus 1 acquires the coordinates (x, y) of the pixel of interest in the ultrasonic image D2 acquired in S4 (step S51), and coordinates the pixel of interest (x, y) in the ultrasonic image D2. A processing target area D2a is set (step S52).

Next, the ultrasonic diagnostic apparatus 1 acquires the filter DFa corresponding to the coordinates (x, y) of the pixel of interest from the filter table (step S53), and performs convolution integral using the filter DFa on the processing target region D2a. , the filter output value S(x, y) is calculated (step S54). Next, the ultrasonic diagnostic apparatus 1 calculates a pixel value O(x, y) by subtracting the filter output value S(x, y) from the pixel value I(x, y) of the pixel of interest (step S55). , the pixel value O(x, y) is set to the coordinates (x, y) of the output image D3 (step S56).

Next, the ultrasonic diagnostic apparatus 1 determines whether or not the processing of all the coordinates has been completed. , the process returns to step S51, and the processes from steps S51 to S56 are executed again. At this time, if the processing of all coordinates has been completed (step S57: YES), the ultrasonic diagnostic apparatus 1 proceeds to the subsequent step S6.

Returning to FIG. 15, the ultrasonic diagnostic apparatus 1 generates a display image D4 from the filtered ultrasonic image D3 obtained in step S5 (step S6). Then, the ultrasonic diagnostic apparatus 1 outputs the display image D4 to the display section 150 and causes the display section 150 to display the display image D4 (step S7). After such processing, the ultrasonic diagnostic apparatus 1 returns to step S4 and repeats the processing.

As described above, the ultrasonic diagnostic apparatus 1 according to the present embodiment causes the display unit 16 to continuously display ultrasonic images (display images D4) from which striped artifacts have been removed.

[effect]
As described above, in the ultrasonic diagnostic apparatus 1 according to the present embodiment, the filter processing unit 14 selects a filter to be applied from among a plurality of filters having different frequency characteristics for each region in the ultrasonic image. DFa is selectively determined, and filtering for reducing stripe artifacts is performed for each region using the determined filter.

Therefore, according to the ultrasonic diagnostic apparatus 1 according to the present embodiment, striped artifacts (striped artifacts occurring between receive beam blocks, or occurring within receive beam blocks) caused by using the parallel reception method striped artifact) can be accurately extracted, and the striped artifact can be removed from the ultrasonic image D2.

In particular, the ultrasonic diagnostic apparatus 1 according to the present embodiment determines the filter DFa to be applied to each processing target region D2a in the ultrasonic image D2. is useful in that it is possible to display an ultrasound image (display image D4) in which the is suppressed.

Further, in particular, the ultrasonic diagnostic apparatus 1 according to the present embodiment is configured such that the position of the processing target region D2a in the ultrasonic image D2, the transmission/reception conditions in the transmission/reception unit 11 (the number of beams to be parallel-received, the depth of the imaging target region, etc.), A filter DFa to be applied to each processing target region D2a is determined based on various conditions such as the type of living tissue in the subject. As a result, it is possible to more effectively generate an ultrasound image D3 in which striped artifacts are suppressed without degrading the spatial resolution of the biological information.

(Second embodiment)
Next, the configuration of the ultrasonic diagnostic apparatus 1 according to the second embodiment will be described with reference to FIGS. 18 and 19. FIG. In the ultrasonic diagnostic apparatus 1 according to the present embodiment, after the filter processing unit 40 detects the frequency band of the striped artifact that occurs in each processing target region D2a of the ultrasonic image D2, This differs from the first embodiment in that the filter DFa to be applied is determined. Note that the description of the configuration common to the first embodiment will be omitted.

FIG. 18 is a diagram schematically showing the striped artifact detection processing of the filter processing unit 40 according to this embodiment. In FIG. 18, FIG. 18A is a graph showing pixel values for one line in the azimuth direction within the ultrasonic image D2. FIG. 18B is a graph showing absolute values (filter output values) of convolution integral values at respective corresponding positions in FIG. 18A. The graphs of Filter 1, Filter 2, and Filter 3 in FIG. 18B show filter output values when Filter 1, Filter 2, and Filter 3, which have different frequency characteristics, are applied to ultrasound image D2. .

The filter processing unit 40 applies a plurality of filters having mutually different frequency characteristics when performing the striped artifact extraction processing on each processing target region D2a of the ultrasonic image D2, and obtains the filter output of each of the plurality of filters. Calculate the value. Then, the filter processing unit 40 compares the filter output values of each of the plurality of filters, and determines the filter with the maximum filter output value as the filter to be applied to the processing target region D2a. Then, the filter processing unit 40 subtracts the filter output value of the determined filter from the pixel value of the pixel of interest in the processing target region D2a to obtain the pixel value of the output image.

As described in the first embodiment, the filter used here is a filter having directivity in the extraction direction so as to extract only striped artifacts whose linear portions extend along the distance direction. , typically a Gabor filter. That is, the filter processing unit 40 according to the present embodiment uses a plurality of Gabor filters having mutually different frequency characteristics to perform filtering on the processing target region D2a on a trial basis. Detect the frequency band of the shape artifact.

This makes it possible to remove the striped artifact from the ultrasound image D2 even when the mode of the striped artifact included in each processing target region D2a of the ultrasound image D2 is unknown.

FIG. 19 is a flow chart showing the operation of the ultrasonic diagnostic apparatus 1 according to this embodiment. 19 shows only the subroutine processing of step S5 of FIG. 15, which is a different flow from the first embodiment.

First, the ultrasonic diagnostic apparatus 1 acquires the coordinates (x, y) of the pixel of interest in the ultrasonic image D2 acquired in S4 (step St51), and coordinates the pixel of interest (x, y) in the ultrasonic image D2. A central processing target area D2a is set (step St52).

Next, the ultrasonic diagnostic apparatus 1 performs convolution integral using each filter to be tested (here, filter DF1 to filter DFN) on the processing target region D2a, and obtains each filter output value (here, Filter output value S1(x, y) to filter output value SN(x, y) are calculated (step St53).

Next, the ultrasonic diagnostic apparatus 1 selects the maximum filter output value from among the filter output values S(x, y) to SN(x, y) calculated in step St53, and selects the pixel value of the pixel of interest. A pixel value O(x, y) is calculated by subtracting the maximum filter output value from I(x, y) (step St54). Then, the ultrasonic diagnostic apparatus 1 sets the pixel value O(x, y) calculated in step St55 to the coordinates (x, y) of the output image D3.

Next, the ultrasonic diagnostic apparatus 1 determines whether or not the processing of all the coordinates has been completed. , the process returns to step 51, and the processing of steps St51 to St55 is executed again. At this time, if the processing of all coordinates has been completed (step St56: YES), the ultrasonic diagnostic apparatus 1 proceeds to the subsequent step S6.

The processing after step S6 is as described above with reference to FIG.

As described above, the filter processing unit 14 according to the present embodiment detects the frequency band of the striped artifact for each processing target region D2a in the ultrasonic image D2, and the frequency band of the striped artifact in the detected region. Based on the band, determine the filter to apply to the region. As a result, the filter processing unit 14 can detect the biological information even when the form of the stripe artifacts occurring in the ultrasonic image is not clear due to the type of subject (for example, tissue parts with large individual differences). A suitable filter can be determined that can suppress streak artifacts without causing degradation.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and various modifications are conceivable.

In the above-described embodiment, as an example of the filtering unit 14, a mode of performing filtering by spatial filtering has been described. However, the filtering unit 14 may perform a Fourier transform on the ultrasonic image D2 and perform filtering in the frequency space.

Further, in the above-described embodiment, as an example of the ultrasonic diagnostic apparatus 1, a mode applied to a B-mode image has been shown. However, the ultrasonic diagnostic apparatus 1 according to the present invention can be applied to arbitrary imaging modes such as color Doppler images, three-dimensional ultrasonic images, elastic mode images, and the like.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

According to the ultrasonic diagnostic apparatus according to the present disclosure, striped artifacts can be suppressed without causing deterioration of biological information in an ultrasonic image.

Reference Signs List 1 ultrasonic diagnostic apparatus 10 main body 11 transmitter/receiver 11a transmitter 11b receiver 12 controller 13 image generator 14 filtering unit 15 digital scan converter 16 display unit 17 operation input unit 20 ultrasonic probe 21 piezoelectric transducer D1 received signal D2 Ultrasound image D3 Ultrasound image D4 Display image DF Filter table DFa Filter

Claims (12)

An ultrasonic diagnostic apparatus for imaging information within a subject using an ultrasonic probe,
a transmitting/receiving unit that causes the ultrasonic probe to transmit/receive ultrasonic waves so as to generate a plurality of received beam data per ultrasonic beam;
an image generating unit that generates an ultrasonic image based on a plurality of received beam data generated when the ultrasonic probe scans the interior of the subject with ultrasonic waves;
For each region in the ultrasonic image, a filter to be applied is selectively determined from among a plurality of filters having mutually different frequency characteristics, and for each region, the determined filter is used to produce a striped artifact a filtering unit that performs filtering to reduce
with
The filter applied to each region by the filter processing unit is a two-dimensional frequency set with reference to an extraction frequency band in the azimuth direction in the ultrasonic image and an extraction frequency band in the distance direction in the ultrasonic image is a selection filter,
The filter processing unit is
Based on the number of received beam data generated per one ultrasonic beam, the extraction center frequency in the azimuth direction of the filter applied to each region is set, and the filter applied to each region in the distance direction a first sub-processing unit that sets an extraction band to a predetermined band in the low frequency band;
For the filter applied to the central region of the ultrasonic image, the extraction bandwidth is set narrower than a specified width in both the azimuth direction and the distance direction, and at the image edge in the azimuth direction of the ultrasonic image and For the filter applied to an area with shallow depth in the distance direction, the extraction bandwidth in the distance direction is set to a specified width, and the extraction bandwidth in the azimuth direction is set to be wider than the specified width, and the ultrasonic image For the filter applied to a region other than the edge of the image in the azimuth direction and having a deep depth in the distance direction, the extraction bandwidth in the azimuth direction is set to the specified width, and the extraction bandwidth in the distance direction is set to be larger than the specified width. For the filter that is widened and applied to the image edge in the azimuth direction of the ultrasonic image and the depth in the distance direction is deep, the extraction bandwidth in both the distance direction and the azimuth direction is widened more than the specified width. a second sub-processing unit for setting
Ultrasound diagnostic equipment. The determined filter is a filter corresponding to the frequency band of the striped artifact that occurs in the region.
The ultrasonic diagnostic apparatus according to claim 1. The filter is a filter for extracting striped artifacts in the region,
The filter processing unit extracts striped artifacts based on the determined filter for each region, and performs processing for removing the extracted striped artifacts from the region of the ultrasonic image.
The ultrasonic diagnostic apparatus according to claim 2. The striped artifact includes a striped artifact occurring at a position between two blocks adjacent to each other with reference to a block of the received beam data generated per ultrasonic beam.
The ultrasonic diagnostic apparatus according to any one of claims 1 to 3. The striped artifact includes a striped artifact that occurs at any position of the received beam data within the block, with the block of the received beam data generated per ultrasonic beam as a reference,
The ultrasonic diagnostic apparatus according to any one of claims 1 to 4. The filter applied to each region by the filter processing unit captures striped pixel value changes in the azimuth direction of the ultrasonic image, and captures striped pixel value changes in the distance direction of the ultrasonic image. has a filter characteristic that captures that the values are continuous,
The ultrasonic diagnostic apparatus according to any one of claims 1 to 5. The filter applied to each region by the filtering unit is a filter using a Gabor function,
The ultrasonic diagnostic apparatus according to claim 6. The filter processing unit determines the filter to be applied to each region based on one or a combination of the depth of the imaging target region within the subject, the type of the ultrasonic probe, and the type of imaging mode. ,
The ultrasonic diagnostic apparatus according to any one of claims 1 to 7 . The filtering unit sets an area to be filtered so that the ultrasonic image is raster-scanned every predetermined size,
The ultrasonic diagnostic apparatus according to any one of claims 1 to 8 . The degree to which the filtering unit removes the striped artifact from the ultrasound image is configurable.
The ultrasonic diagnostic apparatus according to any one of claims 1 to 9 . A control method for an ultrasonic diagnostic apparatus for imaging information within a subject using an ultrasonic probe,
A first process for causing the ultrasonic probe to transmit and receive ultrasonic waves so as to generate a plurality of received beam data per ultrasonic beam;
a second process of generating an ultrasonic image based on a plurality of received beam data generated when the ultrasonic probe scans the inside of the subject;
For each region in the ultrasonic image, a filter to be applied is selectively determined from among a plurality of filters having mutually different frequency characteristics, and for each region, the determined filter is used to produce a striped artifact a third process for filtering to reduce
with
The filter applied to each region in the third processing is a two-dimensional frequency set with reference to an extraction frequency band in the azimuth direction in the ultrasonic image and an extraction frequency band in the distance direction in the ultrasonic image is a selection filter,
In the third process,
Based on the number of received beam data generated per one ultrasonic beam, the extraction center frequency in the azimuth direction of the filter applied to each region is set, and the filter applied to each region in the distance direction a first sub-process for setting an extraction band to a predetermined band in the low frequency band;
For the filter applied to the central region of the ultrasonic image, the extraction bandwidth is set narrower than a specified width in both the azimuth direction and the distance direction, and at the image edge in the azimuth direction of the ultrasonic image and For the filter applied to an area with shallow depth in the distance direction, the extraction bandwidth in the distance direction is set to a specified width, and the extraction bandwidth in the azimuth direction is set to be wider than the specified width, and the ultrasonic image For the filter applied to a region other than the edge of the image in the azimuth direction and having a deep depth in the distance direction, the extraction bandwidth in the azimuth direction is set to the specified width, and the extraction bandwidth in the distance direction is set to be larger than the specified width. For the filter that is widened and applied to the image edge in the azimuth direction of the ultrasonic image and the depth in the distance direction is deep, the extraction bandwidth in both the distance direction and the azimuth direction is widened more than the specified width. a second sub-process to set;
control method. A control program that causes an ultrasonic diagnostic apparatus that uses an ultrasonic probe to image information within a subject to perform processing,
A first process for causing the ultrasonic probe to transmit and receive ultrasonic waves so as to generate a plurality of received beam data per ultrasonic beam;
a second process of generating an ultrasonic image based on a plurality of received beam data generated when the ultrasonic probe scans the inside of the subject;
For each region in the ultrasonic image, a filter to be applied is selectively determined from among a plurality of filters having mutually different frequency characteristics, and for each region, the determined filter is used to produce a striped artifact a third process for filtering to reduce
with
The filter applied to each region in the third processing is a two-dimensional frequency set with reference to an extraction frequency band in the azimuth direction in the ultrasonic image and an extraction frequency band in the distance direction in the ultrasonic image is a selection filter,
In the third process,
Based on the number of received beam data generated per one ultrasonic beam, the extraction center frequency in the azimuth direction of the filter applied to each region is set, and the filter applied to each region in the distance direction a first sub-process for setting an extraction band to a predetermined band in the low frequency band;
For the filter applied to the central region of the ultrasonic image, the extraction bandwidth is set narrower than a specified width in both the azimuth direction and the distance direction, and at the image edge in the azimuth direction of the ultrasonic image and For the filter applied to an area with shallow depth in the distance direction, the extraction bandwidth in the distance direction is set to a specified width, and the extraction bandwidth in the azimuth direction is set to be wider than the specified width, and the ultrasonic image For the filter applied to a region other than the edge of the image in the azimuth direction and having a deep depth in the distance direction, the extraction bandwidth in the azimuth direction is set to the specified width, and the extraction bandwidth in the distance direction is set to be larger than the specified width. For the filter that is widened and applied to the image edge in the azimuth direction of the ultrasonic image and the depth in the distance direction is deep, the extraction bandwidth in both the distance direction and the azimuth direction is widened more than the specified width. a second sub-process to set;
control program.

Images