JP6160166B2 - Ultrasonic signal processing apparatus and ultrasonic signal processing method - Google Patents

Description

  The present invention relates to an ultrasonic signal processing apparatus and method for transmitting ultrasonic echoes, receiving ultrasonic echoes, and performing signal processing.

  In order to increase the S / N of an ultrasonic signal, the use of pulse compression in ultrasonic waves is known, and a typical method of pulse compression is a method using Golay codes.

  A Golay code is a code sequence in which the sum of the aperiodic autocorrelation functions of two code sequences becomes 0 except for the 0 shift point. For example, when the sequence S1 and the sequence S2 shown in [Equation 1] are two-phase (+, −) Golay codes having the same length L, S1 and S2 satisfy the condition of [Equation 2].

  In Equation 2, RS indicates an autocorrelation function, and τ indicates a time shift.

Japanese Patent No. 4472802

  In conventional pulse compression, an ultrasonic echo signal is used, but the S / N of the B image can be amplified when performing image diagnosis or nondestructive inspection, but there is a problem that it does not contribute to the expansion of the depth of focus. It was. As a method for extending the depth of focus of a B image when performing pulse compression, the system described in Patent Document 1 extends the depth of focus by combining Golay codes and multi-focus. However, in the system described in Patent Document 1, only a transmission ultrasonic signal having two focal points can be generated at the same time, and the extension of the focal depth is limited.

  The present invention has been made to solve the above-described problem, and generates a transmission ultrasonic signal having a plurality of focal points using pulse compression, amplifies the S / N of a B image, and extends the depth of focus. It is an object of the present invention to provide an ultrasonic signal processing apparatus and method for realizing it.

  An encoder unit 120 that generates a code sequence, a delay profile set generation unit 200 that generates a plurality of transmission delay profiles that form different focal points, and a time-varying transmission beam that generates a transmission beam profile from the code sequence and a plurality of transmission delay profiles By including the former 201 and the decoder unit 132 that performs decoding processing according to the code sequence, pulse compression is performed using a plurality of transmission ultrasonic signals having different focal points.

  According to the above configuration, the depth of focus can be expanded simultaneously with the S / N amplification of the B image.

1 is a block diagram illustrating an ultrasonic diagnostic system according to a first embodiment. Block diagram showing the ultrasonic signal processing unit 112 Flow chart of image data generation using pulse compression Flow chart of transmission ultrasonic signal generation Diagram showing code sequence signal Diagram showing transmission delay profile Diagram showing time-varying transmission delay profile Diagram showing time-varying transmit beam profile signal Flow chart of sound ray data generation in the reception ultrasonic signal processing unit 112b The figure which shows the transmission ultrasonic transmission signal of Embodiment 1. FIG. The figure which shows the B image created in Embodiment 1 Block diagram showing the received ultrasonic signal processing unit 112c The figure which shows the time-varying decoder part 202 Flow chart of sound ray data generation in the reception ultrasonic signal processing unit 112c The figure which shows the code | symbol ray data produced | generated in Embodiment 2. The figure which shows the amplitude change coefficient used with a time-variant decoder part The figure which shows the sound ray data produced | generated in Embodiment 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same element and description may be abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of an ultrasonic diagnostic system 100 according to the first embodiment.

  The ultrasonic diagnostic system 100 includes an ultrasonic diagnostic apparatus 101 and an ultrasonic probe 102. Here, the ultrasonic probe 102 includes a vibration element 110, and the ultrasonic diagnostic apparatus 101 includes a control unit 111, an ultrasonic signal processing unit 112, a mid process processing unit 113, a back end processing unit 114, and a display unit 115. Yes. The plurality of vibration elements 110 constitute a vibration element array.

  First, each configuration of the ultrasonic diagnostic system 100 in FIG. 1 will be described.

  The control unit 111 generates a control signal and outputs the control signal to the ultrasonic signal processing unit 112, the mid process processing unit 113, and the back end processing unit 114.

  The ultrasonic signal processing unit 112 receives the control signal, generates a drive signal for driving the vibration element 110, and outputs the drive signal to the vibration element 110.

  The vibration element 110 receives the drive signal, generates a transmission ultrasonic signal, outputs the transmission ultrasonic signal into the subject, receives the reception ultrasonic signal returned from the subject, and transmits the reception ultrasonic signal to the ultrasonic signal. Output to the sound wave signal processing unit 112.

  The ultrasonic signal processing unit 112 receives the received ultrasonic signal, generates sound ray data for the received ultrasonic signal, and outputs the sound ray data for the received ultrasonic signal to the mid-process processing unit 113. Here, the sound ray data is data continuous in the depth direction constituting the ultrasonic image after the phasing addition processing. The depth direction is the direction in which the transmitted ultrasonic signal travels from the body surface of the subject into the body.

  The mid process processing unit 113 receives the sound ray data for the received ultrasonic signal, generates amplitude data for the received ultrasonic signal, and outputs the amplitude data for the received ultrasonic signal to the back-end processing unit 114. Here, the amplitude data is data representing the intensity of the received ultrasonic signal.

  The back-end processing unit 114 receives the amplitude data for the received ultrasonic signal, generates image data, and outputs the image data to the display unit 115. Here, the image data is data obtained by converting amplitude data into luminance values.

  FIG. 2 shows the configuration of the ultrasonic signal processing unit 112 in detail. The ultrasonic signal processing unit 112 performs a transmission ultrasonic signal processing unit 112a that performs processing on the transmission side and a processing on the reception side. A reception ultrasonic signal processing unit 112b is provided. The transmission ultrasonic signal processing unit 112a includes an encoder unit 120, an element driving unit 121, a delay profile set generation unit 200, and a time-varying transmission beamformer 201. The reception ultrasonic signal processing unit 112b includes an AD conversion unit 130. A reception beamformer 131 and a decoder unit 132.

  The encoder unit 120 receives the control signal from the control unit 111, generates a code sequence signal, and outputs the code sequence signal to the time-varying transmission beamformer 201. Here, the code sequence signal is information for encoding a transmission ultrasonic signal in advance.

  The delay profile set generation unit 200 receives the control signal from the control unit 111, generates a transmission delay profile set signal from the control signal, and outputs the transmission delay profile set signal to the time-varying transmission beamformer 201. Here, the transmission delay profile group signal is a plurality of pieces of transmission delay profile information corresponding to a plurality of focal points formed by the transmission ultrasonic signal.

  The time-varying transmission beamformer 201 receives the code sequence signal and the transmission delay profile set signal, generates a time-varying transmission beam profile signal from the code sequence signal and the transmission delay profile, and sends the time-varying transmission beam profile signal to the element driver 121. Output. Here, the time-varying transmission beam profile is obtained by changing each drive timing of a plurality of transmission delay profiles corresponding to a plurality of focal points formed by a transmission ultrasonic signal and arranging them in time series.

  The element driving unit 121 receives the time-varying transmission beam profile signal, generates a driving signal from the time-varying transmission beam profile signal, and outputs the driving signal to the vibration element 110.

  The AD conversion unit 130 receives the received ultrasound signal, generates code ultrasound data, and outputs the code ultrasound data to the receive beamformer 131. Here, the code ultrasonic data refers to ultrasonic data that digitizes a received ultrasonic signal and has code information.

  The reception beamformer 131 receives the encoded ultrasonic data, generates encoded acoustic ray data from the encoded ultrasonic data, and outputs the encoded acoustic ray data to the decoder unit 132. Here, the code sound ray data is data continuous in the depth direction constituting the ultrasonic image after the phasing addition processing having the code information.

  The decoder unit 132 receives the encoded sound ray data, generates sound ray data from the encoded sound ray data, and outputs the sound ray data to the mid process processing unit.

  FIG. 3 is a flowchart showing a series of processes relating to generation of image data using pulse compression in the vibration element 110, the ultrasonic signal processing unit 112, the mid process processing unit 113, the back end processing unit 114, and the display unit 115. . In addition, it demonstrates using the Golay code system comprised from a complementary series as a pulse compression method.

  First, a drive signal is generated by the ultrasound signal processing unit 112, the vibration element 110 is driven based on the drive signal, and a transmission ultrasound signal encoded by a Golay code is transmitted into the subject (step S100). . Here, the phase of the ultrasonic pulse constituting the transmission ultrasonic signal is encoded based on the Golay code, and each ultrasonic pulse forms a focal point at at least one or more different points.

  Next, the reception ultrasonic signal returned from the subject is received by the vibration element 110, and the ultrasonic signal processing unit 112 performs signal processing on the reception ultrasonic signal to generate sound ray data (step S101). .

  Next, amplitude data is generated by signal processing of the sound ray data by the mid process processing unit 113 (step S102).

  Finally, image data is generated by performing image processing on the amplitude data by the back-end processing unit 114 (step S103).

  Next, image data is provided to the operator by the display unit 115 (step S104).

  Next, generation of a transmission ultrasonic signal in the vibration element 110, the control unit 111, and the ultrasonic signal processing unit 112 will be described with reference to FIG.

  FIG. 4 shows a series of processes related to generation of a transmission ultrasonic signal in the vibration element 110, the control unit 111, the encoder unit 120, the element driving unit 121, the delay profile set generation unit 200, and the time-varying transmission beamformer 201. It is the shown flowchart.

  First, the control unit 111 generates a control signal, and outputs the control signal to the encoder unit 120 and the delay profile set generation unit 200. (Step S200).

  Here, the control signal has focal position vector information indicating the number of focal points formed by the transmission ultrasonic signal and the point forming the focal point in at least one transmission event. One transmission event is a period from when a transmission ultrasonic wave is transmitted into the subject until the next transmission ultrasonic wave is transmitted into the subject. Note that the control information may be generated so that the transmission ultrasonic signal does not form a focal point but has a region where the transmission ultrasonic signal is concentrated.

  The number of focal points and focal point position vector are manipulated for each value or multiple values by the operator using a dial device, a slide device, a button device, or a touch display device, which is a physical user interface. An arbitrary value of the user may be set, or may be set using a software graphical user interface. In addition to specifying a specific focus position and focus number, you may set a range in which you want to generate a uniform ultrasound image. Specify the image improvement start point and image improvement end point for that purpose, and calculate the focus number and focus position. The focal number n and the focal position vector are calculated as in the following [Equation 3] to [Equation 5].

  The focus number n is expressed by [Expression 3] where ids is an image improvement start point and ide is an image improvement end point.

  Here, fd indicates a focal interval between a plurality of focal points in the transmission ultrasonic signal, and a value set in advance or a value set by the operator is used. The image improvement start point ids and the image improvement end point ide are expressed by the depth from the subject surface. For example, if the image improvement start point ids is 1 cm, the image improvement end point ide is 5 cm, and the focal distance fd is 1 cm, the number of focus points n is four.

  When the focal position component is fn, the focal position vector is expressed by [Equation 4].

  Here, the focal position component fn is expressed by [Equation 5].

  Note that although the focal interval fd has been described as being equal, it may be unequal.

  Next, when the encoder unit 120 receives a control signal from the control unit 111, a code sequence signal corresponding to the number of focal points is created. (Step S201).

  If the Golay codes are c1 and c2, the code sequence signals C1 and C2 are expressed by [Equation 6].

  Here, m represents a transmission numerical aperture indicating the number of vibration elements 110 to be driven in one transmission event, and Golay codes c1 and c2 satisfy the condition of [Equation 7] in the same transmission aperture.

  Further, instead of the transmission numerical aperture m, a variable transmission numerical aperture whose transmission numerical aperture changes depending on the focal position may be used. In this case, the variable transmission numerical aperture vm is set based on a predetermined F value Fnum [number 8].

  Here, i indicates the element number of the focal position vector. Furthermore, c1 and c2 are generated by applying Golay codes when the condition of [Equation 9] expressed using the variable transmission numerical aperture is satisfied.

  Here, MMax represents the maximum transmission numerical aperture among the transmission numerical apertures set for each element of each focal position vector, and j represents the position of the vibration element 110 constituting the transmission aperture. When the condition of [Equation 9] is not satisfied, the Golay code is not excited at the corresponding element position. That is. As shown in [Equation 10], the code C1 = C2 = 0.

  Here, the case where the Golay codes c1 and c2 are [Expression 10] is called a pause code.

  The Golay code constituting the code sequence signal may use a code pattern stored in advance in a memory or the like according to the number of focal points, or may use a Golay code pattern set by the operator. FIG. 5 shows a code sequence signal for generating a transmission ultrasonic signal having four different focal position components. The first code 330, the second code 331, the third code 332, and the first code signal constituting the code sequence signal are shown in FIG. A reference numeral 333 is indicated by a sine wave. Here, the first code 330, the third code 332, and the fourth code 333 have the same phase, and the second code 331 has a different phase. In addition, the shape of a code | symbol is not restricted to a sine wave.

  Next, when the delay profile set generation unit 200 receives a control signal from the control unit 111, a transmission delay profile set signal is generated from the control signal (step S202).

  Here, the transmission delay profile set signal has a transmission delay profile corresponding to at least one or more different focal points. Here, when the transmission delay profile group signal is Dp, it is expressed by [Equation 11].

  Here, dpi indicates each transmission delay profile, and the transmission delay profile is designed based on the focal position component, and the time difference of the drive timing of the vibration element 110 with the vibration element end portion as the drive timing in the transmission aperture is represented by Show. Here, it is assumed that the drive timing of each transmission delay profile is the same. The transmission delay profile dp is expressed by [Equation 12] using the transmission numerical aperture m.

  The transmission numerical aperture m can be replaced with mMax when the variable transmission numerical aperture vm is used. FIG. 6 shows an example of a transmission delay profile. FIG. 6 shows a transmission delay profile for generating a transmission ultrasonic signal having four different focal position components. The first transmission delay profile 300, the second transmission delay profile 301, and the third transmission delay profile 302 are shown in FIG. The shape of the fourth transmission delay profile 303 is different. The horizontal axis represents the element position, and the vertical axis represents the delay difference time.

  Next, when the time-varying transmission beamformer 201 receives the code sequence signal and the transmission delay profile group signal from the encoder unit 120 and the delay profile group generation unit 200, a time-varying transmission beam profile signal is created (step S203).

  The time-varying transmission beam profile signal indicates the drive timing and code shape for generating a code by driving each element in the vibration element 110, and the delay profile differs depending on each code. For this reason, the drive timing of the vibration element 110 is equally spaced at the center of the transmission aperture, but the drive timing becomes unequal at the end of the transmission aperture.

  The time-varying transmit beam profile is generated by adding different interval times to the transmit delay profile signal. The transmission delay profile group signal DP plus the interval time int is used as a time-varying transmission delay profile group signal ADp, and the interval time inti corresponds to the drive timing of each transmission delay profile. 13].

  Here, the interval time is at least longer than the time for driving the vibration element 110 necessary for constituting each code, and the time-varying transmission beam profile is designed so that each delay profile has no intersection. Specifically, the focal position is set closer to the vibration element 110 as the drive timing of the time-varying transmission beam profile is earlier, and the design is performed so as to satisfy the condition of [Equation 14].

  Alternatively, the time-varying transmission beam profile satisfies the condition of [Equation 15].

  Here, the time-varying transmission delay profile will be described with reference to FIG. FIG. 7 shows a time-varying transmission delay profile generated based on the transmission delay profile described in FIG. The time-varying transmission delay profile indicates the driving timing for each vibration element 110. The time-varying transmission profile 314 includes a first time-varying transmission profile 310 having the same delay profile as the first transmission delay profile 300, a second time-varying transmission profile 311 obtained by adding an interval time to the second transmission delay profile 301, The third transmission variable profile 312 includes an interval time added to the third transmission delay profile 302, and the fourth variable transmission profile 313 includes an interval time added to the fourth transmission delay profile 303. The horizontal axis represents the element position, and the vertical axis represents the drive timing. Here, it is assumed that each vibration element has four drive timings in one transmission event, and the drive timing is equally spaced at the center of the transmission aperture, but the drive timing is unequal as the transmission aperture ends. It becomes an interval.

  A transmission beam profile signal is generated from the code sequence signal and the time-varying transmission delay profile. A time-varying transmission beam profile signal will be described with reference to FIG. FIG. 8 shows a time-varying transmission beam profile generated based on the code sequence signal, the time-varying transmission delay profile signal described in FIG. 7, and the code sequence signal described in FIG. The horizontal axis is the element position, and the vertical axis is the drive timing of the vibration element 110. The first time-varying transmission beam profile 320 includes a first transmission profile 300 (FIG. 6) and a first code 330 (FIG. 5), and the second time-varying transmission beam profile 321 is the second transmission profile 301 (FIG. 6). ) And a second symbol 331 (FIG. 5), and the third time-varying transmission beam profile 322 is composed of a third transmission profile 302 (FIG. 6) and a third symbol 332 (FIG. 5). 4 transmission profile 303 (FIG. 6) and a third code 333 (FIG. 5).

  Finally, when the element driving unit 121 receives a time-varying transmission beam profile signal from the time-varying transmission beamformer 201, a driving signal is generated, and a transmission ultrasonic signal is generated by driving the vibration element 110 based on the driving signal. (Step S204).

  Next, generation of sound ray data in the vibration element 110 and the ultrasonic signal processing unit 112 will be described with reference to FIG.

  FIG. 9 is a flowchart showing a series of processes relating to the generation of sound ray data in the vibration element 110, the AD conversion unit 130, the reception beamformer 131, and the decoder unit 132.

  When the vibration element 110 receives the received ultrasonic signal, the received ultrasonic signal is output to the AD conversion unit 130, and code ultrasonic data is generated (step S210). Here, the AD conversion unit 130 converts the digitally converted code ultrasonic signal into digital data.

  Next, when the reception beamformer 131 receives the digital data, the reception beamformer 131 performs a phasing addition process on the code ultrasonic data to generate code sound ray data (step S211).

  Next, when the decoder unit 132 receives the code sound ray data, the decoder unit decodes the code sound ray data to generate sound ray data (step S212).

  As described above, the ultrasonic signal processing apparatus can transmit an ultrasonic beam to a subject with respect to a plurality of different focal positions or focal regions within the same transmission event, as shown in FIG. It is possible to create a transmission ultrasonic transmission signal that is narrower than pulse compression. Here, the transmission ultrasonic signal 340 of the present invention and the conventional transmission ultrasonic signal 341 are shown. As a result, the ultrasonic signal processing unit 112 can generate sound ray data based on a narrow transmission ultrasonic signal. Thereafter, the mid-process signal processing is performed by the mid-process processing unit 113, the image processing is performed by the back-end processing unit 114, and the ultrasonic image is displayed by the display unit 115. Thus, the depth of focus is higher than that of the conventional ultrasonic image using pulse compression. A deep image can be generated. FIG. 11 shows the effect of the present invention by simulation as a B image. Here, the B image 350 generated by the present invention and the B image generated by the conventional method are 351. As shown in FIG. 11, the B image 350 generated by the present invention can draw up to a deep target.

  Although the first embodiment has been described using a complementary sequence code as a pulse compression method, the present invention is not limited to this, and a general ultrasonic system such as a Bakar code, an M sequence, or a chirp wave is used. It is possible to adapt to the pulse compression method used.

  2, the element driving unit 121, the time-varying transmission beamformer 201, the encoder unit 120, the delay profile set generation unit, the AD conversion unit 130, the reception beamformer 131, and the decoder unit 132 are included in the ultrasonic signal processing unit 112. However, a part of the configuration may be mounted on the ultrasonic probe 102.

(Embodiment 2)
FIG. 12 is a block diagram of a configuration of the reception ultrasonic signal processing unit 112c in the ultrasonic signal processing system according to the second embodiment. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The reception ultrasonic signal processing unit 112c is configured as the time-varying decoder unit 202 instead of the decoder unit 132 in the configuration of the reception ultrasonic signal processing unit 112b of the first embodiment.

  The time-varying decoder unit 202 receives the encoded sound ray data, generates sound ray data from the encoded sound ray data, and outputs the sound ray data to the mid-process processing unit 113.

  FIG. 13 shows the configuration of the time varying decoder unit 202 in detail. The time varying decoder unit 202 includes a time varying filter A 210, a time varying filter B 211, a memory 212, and an addition processing unit 213.

  The time varying filter A 210 receives the code sound ray data as input, generates filter sound ray data A obtained by performing filter processing on the code sound ray data with the time varying filter A 210, and outputs the filter sound ray data A to the memory 212. .

  The time varying filter B211 receives the code sound ray data as input, generates the filter sound ray data B obtained by performing filter processing on the code sound ray data with the time varying filter B211, and supplies the filter sound ray data B to the addition processing unit 213. Output.

  The memory 212 receives the filter sound ray data A and holds it until the filter sound ray data B is generated by the time-varying filter B211 after the filter sound ray data A is input, and the filter sound ray data A is added. To 213.

  Next, the addition processing unit 213 receives the filter sound ray data A and the filter sound ray data B as input, generates the sound ray data by adding the filter sound ray data A and the filter sound ray data B, and processes the sound ray data. Output to the processing unit 11.

  FIG. 14 is a flowchart showing a method of decoding the code sound ray data in the time-varying decoder unit 202.

  When the time-varying decoder unit 202 receives the code sound ray data from the reception BF 131, the number of transmission events is determined. If the transmission event is the first time, the process proceeds to step S221. If the transmission event is two times, the process proceeds to step S223. The process proceeds to step S220.

  Next, when the transmission event is the first time, when the time-varying filter A210 receives the code sound ray data from the reception BF 130, the filter sound ray data A is generated by performing a convolution operation on the code sound ray data ( Step S111).

  Here, the shape of the code sound ray data varies depending on the position in the depth direction. FIG. 15 shows changes in the code sound ray data depending on the depth direction. Here, the code sound ray data from the probe vicinity target generated based on the time-varying transmission delay profile described with reference to FIG. 7 is used as the code sound ray data 400 at the probe vicinity target, and the code sound ray data from the probe far target is obtained. Is the code ray data 410 at the probe remote target. The code sound ray data 400 at the probe vicinity target shows a case where the position in the depth direction is relatively shallow, and the code sound ray data 410 at the probe far target shows a case where the position in the depth direction is relatively deep. Yes.

  The code sound ray data 400 at the probe vicinity target includes the first code sound ray data 401 at the probe vicinity target generated from the first time-varying transmission beam profile 320 (FIG. 7) and the second time-varying transmission beam profile 321 (FIG. 7). ) Generated second code sound ray data 402 in the probe vicinity target generated from the third time-varying transmission beam profile 322 (FIG. 7), third code sound ray data 403 in the probe vicinity target generated from the fourth time It consists of fourth code sound ray data 404 at the probe vicinity target generated from the variable transmission beam profile 323 (FIG. 7).

  Here, if the probe vicinity target is close to the focal point of the first time-varying transmission beam profile 320 (FIG. 7), the first code sound ray data 401 at the probe vicinity target is represented by the code sound ray data 400 at the probe vicinity target. Is the largest, and the amplitude of the fourth code sound ray data 404 at the probe vicinity target is the smallest.

  Also, the code sound ray data 410 at the probe far target includes the first code sound ray data 411 at the probe far target generated from the first time-varying transmission beam profile 320 (FIG. 7) and the second time-varying transmission beam profile 321 (see FIG. 7). The second code sound ray data 412 at the probe far target generated from 7), the third code sound ray data 413 at the probe far target generated from the third time-varying transmission beam profile 322 (FIG. 7), and the fourth The fourth code sound ray data 414 at the probe remote target generated from the time-varying transmission beam profile 323 (FIG. 7).

  Here, if the probe far target is close to the focal point of the fourth time-varying transmission beam profile 323 (FIG. 7), the first coded sound ray data 401 at the probe nearby target is represented by the coded sound ray data 410 at the probe far target. Is the smallest, and the amplitude of the fourth code sound ray data 404 at the probe vicinity target is the largest.

  In this way, the code sound ray data generated based on the code time-varying transmission profile undergoes amplitude fluctuation because the focal points of the code time-varying transmission profiles are different. Therefore, a decoding process in consideration of amplitude fluctuation is performed using a time-varying filter. Here, the time-varying filter A210 is represented by [Expression 16] as FA.

  Here, fai represents a time-varying filter coefficient and is represented by [Equation 17].

  Here, dc1i represents a time-varying filter coefficient and is automatically determined according to the code sequence C1. For example, when encoding is performed using phases of 0 degrees and 180 degrees, dc1i takes either a positive or negative value depending on the phase of the code being 0 degrees or 180 degrees. Further, api represents the amplitude variation coefficient of the time-varying filter coefficient, and d represents the position of the code sound ray data in the depth direction.

  FIG. 16 shows the amplitude change coefficient of the time-varying filter coefficient. Here, the first amplitude change coefficient 420, the second amplitude change coefficient 421, the third amplitude change coefficient 422, and the fourth amplitude change coefficient 423 are shown. Each amplitude change coefficient is changed linearly or nonlinearly according to the position of the code sound ray data in the depth direction. The absolute value of the filter coefficient takes a maximum value at the focal position of the transmission ultrasonic signal.

  In [Equation 16], Zn represents a zero matrix and is represented by [Equation 19].

  Here, Ln indicates the length of the zero matrix and is expressed by [Equation 19].

  Here, fs represents the sampling frequency, and fc represents the center frequency of the transmission ultrasonic signal. Filter sound ray data A is calculated using the time-varying filter A, and the filter sound ray data A is expressed by [Equation 20].

  Here, CDASA represents code sound ray data A, and symbol * represents convolution.

  Next, the memory 212 receives the filter sound ray data A from the time varying filter A210, and stores the data in the memory space until a predetermined timing (step S222).

  Here, the predetermined timing is a timing at which the filter sound ray data A is delivered from the memory 212 to the addition processing unit 213. When step S223 is completed, the filter sound ray data A is delivered.

  When the transmission event is the second time, when the time-varying filter B211 receives the code sound ray data from the reception BF 130, the filter sound ray data B is generated by performing a convolution operation on the code sound ray data (step S223). . The time-varying filter B211 is represented by [Expression 21] as FB.

  Here, fbi represents a time-varying filter coefficient and is represented by [Equation 22].

  Here, dc2i represents a time-varying filter coefficient and is automatically determined according to the code sequence C2.

  Filter sound ray data B is calculated using the time-varying filter B. The filter sound ray data B is expressed by [Equation 23].

  Here, CDASB represents the code sound ray data B.

  Finally, when the addition processing unit 213 receives the code sound ray data A and the code sound ray data B from the time-varying filter A 210 and the memory 212, the sound ray data is calculated from the code sound ray data A and the code sound ray data B. (Step S224). Here, the sound ray data generated in the addition processing unit 213 is expressed by [Equation 24].

  Here, the sound ray data generated using the encoded sound ray data A and the encoded sound ray data B will be described with reference to FIG. The sound ray data generated by the conventional filtering process is referred to as the sound ray data 430 generated by the conventional method, and the sound ray data generated using the time-varying filter is the sound ray data 431 generated by the present invention. In the sound ray data 430, a decoding error occurs due to the amplitude fluctuation of the code, and a time side lobe which is a small amplitude decoding error is generated before and after the large amplitude signal from the target. Occurrence can be suppressed.

(Other variations)
Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and the following cases are also included in the present invention.

  (1) When all or a part of each of the above devices is configured by a computer system including a microprocessor, a ROM, a RAM, a hard disk unit, and the like. The RAM or the hard disk unit stores a computer program that achieves the same operation as each of the above devices. Each device achieves its functions by the microprocessor operating according to the computer program.

  (2) A part or all of the components constituting each of the above devices may be configured by one system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on a single chip, and specifically, a computer system including a microprocessor, ROM, RAM, and the like. . The RAM stores a computer program that achieves the same operation as each of the above devices. The system LSI achieves its functions by the microprocessor operating according to the computer program. Further, the present invention is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  (3) Part or all of the constituent elements constituting each of the above devices may be configured from an IC card that can be attached to and detached from each device or a single module. The IC card or the module is a computer system including a microprocessor, a ROM, a RAM, and the like. The IC card or the module may include the super multifunctional LSI described above. The IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.

  (4) The present invention may be a method realized by the computer processing described above. In addition, the present invention may be a computer program that is realized by a processor such as a CPU executing these methods, or may be a digital signal composed of the computer program.

  Further, the present invention may be the computer program or the digital signal recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include a flexible disk, a hard disk, a CD-ROM, an MO, a DVD, a DVD-ROM, a DVD-RAM, a BD (Blu-ray (registered trademark) Disc), and a semiconductor memory. Further, the present invention may be the digital signal recorded on these recording media.

  Further, the present invention may transmit the computer program or the digital signal via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.

  The present invention may also be a computer system including a microprocessor and a memory, wherein the memory stores the computer program, and the microprocessor operates according to the computer program.

  In addition, the program or the digital signal is recorded on the recording medium and transferred, or the program or the digital signal is transferred via the network or the like, and executed by another independent computer system. It is good.

  (5) The above embodiment and the above modifications may be combined.

  Moreover, all the numbers used above are illustrated for specifically explaining the present invention, and the present invention is not limited to the illustrated numbers.

  In addition, division of functional blocks in the block diagram is an example, and a plurality of functional blocks can be realized as one functional block, a single functional block can be divided into a plurality of functions, or some functions can be transferred to other functional blocks. May be. In addition, functions of a plurality of functional blocks having similar functions may be processed in parallel or time-division by a single hardware or software.

  In addition, the order in which the above steps are executed is for illustration in order to specifically describe the present invention, and may be in an order other than the above. Also, some of the above steps may be executed simultaneously (in parallel) with other steps.

  Further, various modifications in which the present embodiment is modified within the scope conceivable by those skilled in the art are also included in the present invention without departing from the gist of the present invention.

  As described above, the ultrasonic transmission signal acquisition apparatus and method according to the present invention includes the delay profile set generation unit 200 and the time-varying transmission beamformer 201, and improves the performance of the conventional ultrasonic signal acquisition apparatus, in particular. It is possible to simultaneously realize S / N amplification and depth of focus expansion in ultrasonic image generation using pulse compression.

DESCRIPTION OF SYMBOLS 100 Ultrasonic diagnostic system 101 Ultrasonic diagnostic apparatus 102 Ultrasonic probe 110 Vibration element 111 Control part 112 Ultrasonic signal processing part 113 Mid process processing part 114 Back end processing part 115 Display part 112a Transmission ultrasonic signal processing part 112b Reception ultrasonic wave Signal processing unit 112c Reception ultrasonic signal processing unit 121 Element driving unit 130 AD conversion unit 131 Reception beamformer 132 Decoder unit 200 Delay profile set generation unit 201 Time-varying transmission beamformer 202 Time-varying decoder unit 210 Time-varying filter A
211 Time-varying filter B
212 memory 213 addition processing unit 300 first transmission delay profile 301 second transmission delay profile 302 third transmission delay profile 303 fourth transmission delay profile 310 first time varying transmission profile 311 second time varying transmission profile 312 third time varying transmission Profile 313 4th time varying transmission profile 314 Time varying transmission profile 320 1st time varying transmission beam profile 321 2nd time varying transmission beam profile 322 3rd time varying transmission beam profile 323 4th time varying transmission beam profile 330 1st code 331 Second code 332 Third code 333 Fourth code 340 Transmission ultrasonic signal of the present invention 341 Transmission ultrasonic signal of the conventional system 350 B image generated by the present invention 351 B image generated by the conventional system 400 Probe vicinity data Coded ray data at the target 401 First code ray data at the probe vicinity target 402 Second code ray data at the probe vicinity target 403 Third code ray data at the probe vicinity target 404 Fourth code ray data at the probe vicinity target 410 Code Sound Ray Data at Probe Remote Target 411 First Code Sound Ray Data at Probe Remote Target 412 Second Code Sound Ray Data at Probe Remote Target 413 Third Code Sound Ray Data at Probe Remote Target 414 Fourth Code at Probe Remote Target Sound ray data 420 First amplitude change coefficient 421 Second amplitude change coefficient 422 Third amplitude change coefficient 423 Fourth amplitude change coefficient 430 Sound ray data generated by a conventional method 431 The present invention Ray ray data generated by

Claims (18)

An ultrasonic signal processing device that emits a transmission ultrasonic signal to a subject through a vibration element array composed of vibration elements and receives a reception ultrasonic signal reflected from the subject,
An encoder for generating a code sequence including a plurality of codes;
A delay profile set generation unit that generates a transmission delay profile set including at least two transmission delay profiles corresponding to a focus formed by the transmission ultrasonic signal;
Based on the code sequence and the transmission delay profile set, a time-varying transmission beamformer that generates a time-varying transmission beam profile having waveform information and driving timing information of a driving signal that drives the vibration element array;
An element driver that generates the drive signal according to the time-varying transmission beam profile;
A reception ultrasonic signal processing unit that performs reception ultrasonic signal processing on the reception ultrasonic signal received through the vibration element array,
The transmission delay profile set includes a set of the transmission delay profiles having different shapes,
The element driving unit transmits the driving signal to the vibrating element array,
The transmitted ultrasonic signal emitted from the vibrating element array includes a set of ultrasonic pulses having different shapes, and forms at least two different focal points .
The ultrasonic signal processing apparatus , wherein the transmission delay profile has a focal position closer to the vibration element array as the drive timing for driving the vibration element is earlier . The delay profile set generation unit receives the control information and generates the transmission delay profile set,
The control information has focal number information corresponding to the focal number formed by the transmission ultrasonic signal,
The number of focal points is set based on an image quality improvement depth that specifies an image quality improvement range of an ultrasonic image generated based on the received ultrasonic signal, and the focal number increases as the image quality improvement depth increases. And
The ultrasonic signal processing apparatus according to claim 1. The image quality improvement depth is represented by an image improvement start point and an image improvement end point, and the image improvement start point and the image improvement end point are represented by positions in a direction in which the transmission ultrasonic signal from the subject surface travels. Features
The ultrasonic signal processing apparatus according to claim 1 or 2. The control information further includes focal position information about a focal position formed by the transmission ultrasonic signal,
The focal position is at least two or more,
The focal position is generated based on the image quality improvement depth, and the larger the image quality improvement depth, the larger the interval between the focal positions.
The ultrasonic signal processing apparatus according to claim 1. The encoder unit generates the code sequence having the codes equal to or less than the number of focal points.
The ultrasonic signal processing apparatus according to claim 1. Each of the transmission delay profiles has no intersection point,
The ultrasonic signal processing apparatus according to claim 1. The time-varying transmission beam profile is generated by adding an interval time indicating a driving interval time for driving the code to the transmission delay profile,
The interval time is at least greater than the time for forming the code,
Ultrasonic signal processing apparatus according to any one of claims 1-6. The transmission aperture constituting the transmission beam profile is characterized in that the transmission aperture is smaller as the focal position is closer to the vibration element array,
Ultrasonic signal processing apparatus according to any one of claims 1-7. The transmission aperture is determined based on the focal position information and F value,
Ultrasonic signal processing apparatus according to any one of claims 1-7. Each of the codes included in the code sequence is encoded with a phase of the transmission ultrasonic wave,
Ultrasonic signal processing apparatus according to claim 1-9. The code sequence is a Golay code,
The ultrasonic signal processing apparatus according to claim 10 . The code sequence is a Barker code,
The ultrasonic signal processing apparatus according to claim 10 . An ultrasonic signal processing device that emits a transmission ultrasonic signal to a subject through a vibration element array composed of vibration elements and receives a reception ultrasonic signal reflected from the subject,
An encoder for generating a code sequence including a plurality of codes;
A delay profile set generation unit that generates a transmission delay profile set including at least two transmission delay profiles corresponding to a focus formed by the transmission ultrasonic signal;
Based on the code sequence and the transmission delay profile set, a time-varying transmission beamformer that generates a time-varying transmission beam profile having waveform information and driving timing information of a driving signal that drives the vibration element array;
An element driver that generates the drive signal according to the time-varying transmission beam profile;
A reception ultrasonic signal processing unit that performs reception ultrasonic signal processing on the reception ultrasonic signal received through the vibration element array,
The transmission delay profile set includes a set of the transmission delay profiles having different shapes,
The element driving unit transmits the driving signal to the vibrating element array,
The transmitted ultrasonic signal emitted from the vibrating element array includes a set of ultrasonic pulses having different shapes, and forms at least two different focal points.
The reception ultrasonic signal processing unit converts a transmission ultrasonic signal received by the vibration element into digital data, and generates an encoded ultrasonic data; and
A reception beamformer that performs phasing addition processing on the code ultrasonic data and generates code sound ray data;
A time-varying decoder unit that performs a decoding process on the code sound ray data according to the code sequence;
The filter coefficient of the time-varying decoder unit is a position of the sound ray data constituting the ultrasonic image generated based on the received ultrasonic signal in the direction in which the transmission ultrasonic signal from the subject surface travels. It is determined according to
Ultrasonic signal processing apparatus. The ultrasonic signal processing apparatus according to claim 13 , wherein the absolute value of the filter coefficient takes a maximum value at a focal position formed by the transmission ultrasonic signal. The ultrasonic signal processing apparatus according to claim 1,
An ultrasonic diagnostic apparatus that generates an ultrasonic image from the received ultrasonic signal. The ultrasonic diagnostic apparatus of claim 15 ;
An ultrasonic diagnostic system comprising an ultrasonic probe that transmits the transmission ultrasonic signal to the subject and receives the reception ultrasonic signal. An ultrasonic signal processing method for emitting a transmission ultrasonic signal to a subject through a vibration element array composed of vibration elements and receiving a reception ultrasonic signal reflected from the subject,
An encoding step for generating a code sequence including a plurality of codes;
A delay profile set generation step for generating a transmission delay profile set including at least two transmission delay profiles corresponding to a focus formed by the transmission ultrasonic signal;
Based on the code sequence and the transmission delay profile set, a time-varying transmission beamforming step for generating a time-varying transmission beam profile having waveform information and driving timing information of a driving signal for driving the vibration element array;
An element driving step for generating the driving signal according to the time-varying transmission beam profile;
A reception ultrasonic signal processing step of performing reception ultrasonic signal processing on the reception ultrasonic signal received through the vibration element array,
The transmission delay profile set includes a set of the transmission delay profiles having different shapes,
The element driving unit transmits the driving signal to the vibrating element array,
The transmitted ultrasonic signal emitted from the vibrating element array includes a set of ultrasonic pulses having different shapes, and forms at least two different focal points .
The ultrasonic signal processing method , wherein the transmission delay profile has a focal position closer to the vibration element array as the drive timing for driving the vibration element is earlier . A program causing a computer to execute the ultrasonic signal processing method according to claim 17 .