JP2024000892A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a beamforming parameter which may form a high-quality ultrasonic image, or reduce a calculation amount of decision processing of an imaging parameter.

SOLUTION: A characteristic data decision unit 34 decides characteristic data expressing a change amount from a current item value for each of image quality items about the image quality of an ultrasonic image on the basis of the signal characteristic of received frame data subjected to signal processing received from a signal processing unit 18 or the image characteristic of the ultrasonic image received from an image formation unit 20. A parameter decision unit 36 decides (changes) an imaging parameter on the basis of the characteristic data that is decided (or corrected) by the characteristic data decision unit 34. A transmission unit 14, a reception unit 16, the signal processing unit 18 and the image formation unit 20 acquire the received frame data by using the imaging parameter after the change, perform signal processing to the received frame data and generate the ultrasonic image on the basis of the received frame data.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

This specification discloses an ultrasonic diagnostic device.

Ultrasonic diagnostic equipment transmits ultrasound beams generated by transmitting beamforming to a subject from multiple vibrating elements placed on an ultrasound probe, and transmits reflected waves generated during the propagation process in the subject into multiple waves. It is received by a vibrating element and converted into a received signal. Thereafter, phasing and addition processing is performed while giving a predetermined delay value to the received signal obtained for each vibrating element. This process is repeated while moving (scanning) the transmission position to obtain reception frame data, which is a phased signal within the imaging area (reception beamforming). The reception frame data acquired in this manner is subjected to signal processing including reception filter processing such as band shaping, detection processing, or image formation processing to form an ultrasound image.

Various imaging parameters are involved in each process up to forming an ultrasound image. Some of the imaging parameters can be set by a user such as a doctor. Imaging parameters include, for example, transmission beamforming parameters regarding ultrasound transmission beamforming, reception beamforming parameters regarding ultrasound reception beamforming, signal processing parameters regarding signal processing for reception frame data, or ultrasound image formation processing. This includes image forming processing parameters related to the image forming process.

The above-mentioned various parameters greatly affect the image quality such as the resolution and contrast of the ultrasonic image that is formed. Therefore, in order to obtain high-quality ultrasound images, it is desirable to appropriately set these parameters. However, since the optimal values of these parameters may vary depending on the imaging target, the biological characteristics of the subject, etc., it may be difficult to set appropriate parameters, especially for inexperienced users.

In view of the above, an automatic parameter adjustment function has been proposed for the purpose of improving the image quality of ultrasound images. For example, in Patent Document 1, in order to suppress deterioration in the image quality of ultrasound images due to attenuation of ultrasound waves within the subject, it is proposed to Based on this, a technique for setting parameters related to a transmission frequency and a reception filter is disclosed.

JP2021-83956A

The technique described in Patent Document 1 discloses an adaptive setting method regarding transmission frequencies and reception filters. However, Patent Document 1 only discloses a method for setting a limited part of the imaging parameters, and other imaging parameters, particularly the transmission beamforming parameters and the reception beamforming parameters (hereinafter, these are not included). No method is shown to appropriately set the beamforming parameters (sometimes simply referred to as "beamforming parameters"). Note that the transmission frequency is simply the frequency of the transmitted ultrasound, and is not a parameter related to transmission beamforming that forms the ultrasound beam. In addition, in many cases, it is desired that ultrasound images be formed (and displayed) in real time relative to the transmission timing of ultrasound beams. It is also desirable to reduce the amount of processing calculations.

The purpose of the ultrasound diagnostic apparatus disclosed in this specification is to determine beamforming parameters that can form high-quality ultrasound images. Alternatively, the purpose of the ultrasonic diagnostic apparatus disclosed in this specification is to reduce the amount of calculation in the imaging parameter determination process.

The ultrasound diagnostic apparatus disclosed in this specification is based on signal characteristics of received frame data obtained by transmitting and receiving ultrasound, or image characteristics of an ultrasound image formed based on the received frame data. The present invention is characterized by comprising a parameter determination unit that determines at least one of a transmission beamforming parameter regarding ultrasound transmission beamforming or a reception beamforming parameter regarding ultrasound reception beamforming.
In addition, the transmission beamforming parameters include a transmission aperture indicating a transducer element that transmits ultrasonic waves in the transducer array of the ultrasonic probe, a transmission focus of the ultrasonic wave to be transmitted to the subject, and a transmission aperture included in the transmission aperture. transmission apodization indicating the amplitude of the ultrasonic waves transmitted from each of the vibration elements included in the transmission aperture; a waveform of a transmission signal that is an electrical signal supplied to the ultrasound probe; A parameter for determining at least one of the transmission timing or the transmission interval of ultrasound transmitted to the subject is included, and the reception beamforming parameter includes a parameter for determining at least one of the transmission timing or the transmission interval of ultrasound transmitted to the subject, and the reception beamforming parameter includes a A receiving aperture indicating a transducer that receives a reflected wave from a subject, a receiving focus of the reflected wave, and a receiving area attached to each of the vibrating elements included in the receiving aperture and indicating the weight of the reflected wave received by each vibrating element. It is preferable that a parameter for determining at least one of apodization, a reception interval of the reflected waves, or a synthesis weighting coefficient in aperture synthesis processing is included.

According to this configuration, at least one of the transmission beamforming parameter and the reception beamforming parameter is determined (in other words, automatically adjusted) based on the signal characteristics of the reception frame data or the image characteristics of the ultrasound image. Therefore, by forming an ultrasound image using the transmission beamforming parameters or reception beamforming parameters determined by the parameter determination unit, an ultrasound image formed using the transmission beamforming parameters or reception beamforming parameters before the change is created. It is possible to form a high-quality ultrasound image compared to the conventional method.

Based on the signal characteristics of the received frame data or the image characteristics of the ultrasound image formed based on the received frame data, characteristic data representing the amount of change for each of a plurality of image quality items regarding the image quality of the ultrasound image is generated. It is preferable that the apparatus further includes a characteristic data determining section for determining, and the parameter determining section determines at least one of the transmitting beamforming parameter or the receiving beamforming parameter based on the determined characteristic data.

According to this configuration, the parameter determination unit determines at least one of the transmission beamforming parameter and the reception beamforming parameter using the amount of change in each image quality item indicated by the characteristic data as an index, thereby determining the transmission beamforming parameter. The amount of calculation for determining at least one of the forming parameter and the reception beamforming parameter can be reduced.

The ultrasound diagnostic apparatus disclosed in this specification is based on signal characteristics of received frame data obtained by transmitting and receiving ultrasound, or image characteristics of an ultrasound image formed based on the received frame data. a characteristic data determination unit that determines characteristic data representing the amount of change for each of a plurality of image quality items regarding the image quality of the ultrasound image, and formation of an ultrasound image from transmission and reception of ultrasound based on the determined characteristic data. and a parameter determination unit that determines imaging parameters related to the processing up to.
Further, the imaging parameters include transmission beamforming parameters regarding ultrasound transmission beamforming, reception beamforming parameters regarding ultrasound reception beamforming, signal processing parameters regarding signal processing for reception frame data, or formation of ultrasound images. It is preferable that at least one image forming processing parameter related to processing is included.

According to this configuration, the imaging parameters are determined (in other words, automatically adjusted) based on the signal characteristics of the received frame data or the image characteristics of the ultrasound image. Therefore, by forming an ultrasound image using the imaging parameters determined by the parameter determination unit, a higher quality ultrasound image is formed compared to an ultrasound image formed using the imaging parameters before the change. be able to. At the same time, according to the configuration, by performing the process of determining the imaging parameters using the amount of change in each image quality item indicated by the characteristic data as an index, it is possible to reduce the amount of calculations in the process of determining the imaging parameters. .

The parameter determining unit refers to an imaging parameter database storing a plurality of combinations of the characteristic data and information indicating the amount of change in the imaging parameter, and selects a characteristic that is the same as or similar to the characteristic data in the imaging parameter database. The imaging parameter may be determined based on information indicating an amount of change in the imaging parameter associated with the data.

According to this configuration, by determining the imaging parameters with reference to the imaging parameter database, it is possible to further reduce the amount of calculation in the imaging parameter determination process.

It is preferable that the parameter determination unit determines the imaging parameters through an optimization process that optimizes an image quality item of interest among the plurality of image quality items.

According to this configuration, the imaging parameter determination process can be performed without the need to prepare an imaging parameter database in advance.

It is preferable that the parameter determination unit determines the imaging parameters through the optimization process that imposes constraints on image quality items other than the image quality item of interest among the plurality of image quality items.

According to this configuration, it is possible to determine imaging parameters in which the image quality item of interest is optimized while suppressing deterioration of image quality items other than the image quality item of interest.

The received frame data may be volume data obtained by a two-dimensional ultrasound probe in which vibrating elements are two-dimensionally arranged.

According to this configuration, when the received frame data is volume data, which requires a particularly large amount of calculation in the imaging parameter determination process, it is possible to reduce the calculation amount in the imaging parameter determination process.

According to the ultrasonic diagnostic apparatus disclosed in this specification, beamforming parameters that can form a high-quality ultrasonic image can be determined. Alternatively, according to the ultrasonic diagnostic apparatus disclosed in this specification, it is possible to reduce the amount of calculation in the imaging parameter determination process.

1 is a schematic diagram of the configuration of an ultrasonic diagnostic apparatus according to the present embodiment. FIG. 3 is a diagram showing a first example of specific characteristic data. It is a figure which shows the 2nd example of specific characteristic data. It is a figure which shows the 3rd example of specific characteristic data. FIG. 3 is a diagram showing the distribution of signal intensity of an ultrasound beam in the azimuth direction and the depth direction. FIG. 3 is a diagram showing the distribution of signal intensity of an ultrasound beam in the azimuth direction at a predetermined depth. FIG. 6 is a diagram showing how the S/N ratio of an ultrasound beam is improved according to a change in a transmission beamforming parameter. It is a flowchart which shows the flow of processing of the ultrasonic diagnostic device concerning this embodiment.

FIG. 1 is a schematic diagram of the configuration of an ultrasound diagnostic apparatus 10 according to this embodiment. The ultrasound diagnostic apparatus 10 is a medical device installed in a medical institution such as a hospital and used during ultrasound examinations.

The ultrasonic diagnostic apparatus 10 can operate in multiple operation modes including B mode. B mode is an ultrasound image (B mode image) in which the amplitude intensity of the reflected wave from the scanning surface is converted into brightness based on the received frame data obtained by scanning the ultrasound beam (transmission beam). This is the mode to generate and display.

The probe 12, which is an ultrasound probe, is a device that transmits ultrasound beams and receives reflected waves. Specifically, the probe 12 is brought into contact with the body surface of the subject, transmits an ultrasonic beam toward the subject, and receives reflected waves reflected from tissues within the subject. A vibrating element array consisting of a plurality of vibrating elements is provided within the probe 12. Each vibrating element included in the vibrating element array is supplied with a transmission signal, which is an electric signal, from a transmitter 14, which will be described later, and thereby an ultrasonic beam (transmission beam) is generated. In this specification, the process of generating an ultrasound beam based on a transmission signal is referred to as transmission beamforming. Further, each vibrating element included in the vibrating element array receives a reflected wave from the subject, converts the reflected wave into a received signal that is an electric signal, and transmits the received signal to a receiving unit 16, which will be described later.

The probe 12 may be a one-dimensional ultrasound probe consisting of a plurality of transducer elements in which a transducer array is arranged in one dimension, or may be a one-dimensional ultrasonic probe in which a transducer array is composed of a plurality of transducer elements in which a transducer array is arranged in two dimensions. It may also be a two-dimensional ultrasonic probe.

The transmitter 14 supplies a plurality of transmit signals to the probe 12 (specifically, the vibrating element array) in parallel when transmitting ultrasonic waves. As a result, transmission beam forming is performed, and an ultrasound beam is transmitted from the probe 12.

The transmitter 14 generates a plurality of transmit signals to be supplied to the probe 12 based on the transmit beamforming parameters. The transmission beamforming parameters include a transmission aperture indicating a transducer element that transmits ultrasonic waves in the transducer array of the probe 12, a transmission focal point of the ultrasonic waves to be transmitted to the subject, and a transmission beam from each transducer element included in the transmission aperture. at least one of transmission apodization indicating the amplitude of the ultrasound to be transmitted, the waveform of the transmission signal, the transmission timing of the ultrasound from each vibrating element included in the transmission aperture, or the transmission interval of the ultrasound to be transmitted to the subject. Contains parameters for determining.

The transmission beamforming parameters referred to by the transmitter 14 may be predetermined (default values) in the ultrasound diagnostic apparatus 10. Further, the transmission beamforming parameters referred to by the transmitter 14 may be determined based on instructions from a user such as a doctor, which are input from an input interface 26, which will be described later. Further, in the present embodiment, the transmission beamforming parameters referred to by the transmitting section 14 may be determined by a parameter determining section 36, which will be described later.

The receiver 16 receives a plurality of reception signals from the probe 12 (specifically, the transducer array) in parallel when receiving reflected waves. The receiving unit 16 performs various processes on the plurality of received signals, thereby generating received frame data. In this specification, the process of generating receive frame data based on a plurality of received signals is referred to as receive beamforming.

The receiving unit 16 performs receive beamforming based on the receive beamforming parameters. The reception beamforming parameters are assigned to each transducer element included in the reception aperture, the reception focus of the reflected wave, and the reception aperture that indicates the transducer that receives the reflected wave from the subject in the transducer array of the probe 12. It includes a parameter for determining at least one of reception apodization indicating the weight of reflected waves received by the vibrating element, a reception interval of reflected waves, or a synthesis weighting coefficient in aperture synthesis processing.

The reception beamforming parameters referred to by the reception unit 16 may be predetermined (default values) in the ultrasound diagnostic apparatus 10. Further, the reception beamforming parameters referred to by the reception unit 16 may be determined based on user instructions input from the input interface 26, which will be described later. Further, in the present embodiment, the reception beamforming parameters referred to by the reception unit 16 may be determined by a parameter determination unit 36, which will be described later.

The signal processing unit 18 performs various signal processing, including filter processing and gain correction processing, on the received frame data from the reception unit 16. The signal processing unit 18 performs various signal processing based on signal processing parameters related to signal processing on received frame data. The signal processing parameters include, for example, coefficients of a filter (for example, a bandpass filter) used in filter processing, a gain coefficient referred to during gain correction processing, and the like.

The signal processing parameters referred to by the signal processing unit 18 may be predetermined (default values) in the ultrasound diagnostic apparatus 10. Furthermore, the signal processing parameters referred to by the signal processing section 18 may be determined based on user instructions input from the input interface 26, which will be described later. Furthermore, in the present embodiment, the signal processing parameters referred to by the signal processing section 18 may be determined by a parameter determining section 36, which will be described later.

The image forming unit 20 includes a digital scan converter and the like, and executes image forming processing to form an ultrasound image (B-mode image in this embodiment) based on the received frame data from the signal processing unit 18. In the image forming process, various image processes such as gain correction processing, noise removal processing, or edge enhancement processing are performed based on image forming processing parameters related to the ultrasonic image forming process. The image forming processing parameters include, for example, a gain coefficient referred to during gain correction processing, parameters related to noise removal processing and edge enhancement processing, and the like.

The image forming processing parameters referred to by the image forming unit 20 may be predetermined (default values) in the ultrasound diagnostic apparatus 10. Further, the image forming processing parameters referred to by the image forming section 20 may be determined based on user instructions input from the input interface 26, which will be described later. Further, in the present embodiment, the image forming processing parameters referred to by the image forming section 20 may be determined by a parameter determining section 36, which will be described later.

The display control unit 22 causes the ultrasound image generated by the image forming unit 20 to be displayed on a display 24 configured with, for example, a liquid crystal panel.

The input interface 26 includes, for example, buttons, a trackball, or a touch panel. The input interface 26 is for inputting user instructions to the ultrasound diagnostic apparatus 10.

The memory 28 is configured to include an HDD (Hard Disk Drive), an SSD (Solid State Drive), an eMMC (Embedded Multi Media Card), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The memory 28 stores an ultrasound diagnostic program for operating each part of the ultrasound diagnostic apparatus 10. Note that the ultrasound diagnostic program can also be stored in a computer-readable non-temporary storage medium such as a USB (Universal Serial Bus) memory or a CD-ROM. The ultrasound diagnostic apparatus 10 can read and execute an ultrasound diagnostic program from such a storage medium. Further, as shown in FIG. 1, an imaging parameter DB (Data Base) 30 is stored in the memory 28. The imaging parameter DB 30 will be described later.

The control unit 32 includes a general-purpose processor (for example, a CPU (Central Processing Unit), etc.) and a dedicated processor (for example, a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and an FPGA (Field-Programmable Gate Array)). , programmable logic device, etc.). The control unit 32 may be configured not by one processing device but by the cooperation of a plurality of processing devices located at physically separate locations. The control unit 32 controls each part of the ultrasound diagnostic apparatus 10 according to the ultrasound diagnostic program stored in the memory 28.

In the ultrasound diagnostic apparatus 10, imaging parameters can be automatically adjusted based on the signal characteristics of the received frame data signal-processed by the signal processing section 18 or the image characteristics of the ultrasound image formed by the image forming section 20. It becomes. The imaging parameters include transmission beamforming parameters referred to by the transmitter 14, reception beamforming parameters referred to by the receiver 16, signal processing parameters referred to by the signal processing unit 18, and image forming processing referred to by the image forming unit 20. At least one of the parameters is included. The details of the characteristic data determining section 34 and the parameter determining section 36 as well as the automatic adjustment process of the imaging parameters will be described below.

Note that each of the transmitting section 14, receiving section 16, signal processing section 18, image forming section 20, display control section 22, characteristic data determining section 34, and parameter determining section 36 includes one or more processors, chips, electrical It is made up of circuits, etc. Each of these parts may be realized by cooperation between hardware and software.

The characteristic data determining section 34 determines the image quality of the ultrasound image based on the signal characteristics of the signal-processed received frame data received from the signal processing section 18 or the image characteristics of the ultrasound image received from the image forming section 20. characteristic data representing the amount of change from the current item value for each of the plurality of image quality items is determined.

2A to 2C are diagrams showing examples of specific characteristic data. Here, an example will be described in which a transmission beamforming parameter of image data is adjusted. In this example, the characteristic data includes "resolution (azimuthal resolution)," "S/N ratio," and "sensitivity" as a plurality of image quality items. Note that the plurality of image quality items included in the characteristic data are not limited to these. In FIGS. 2A to 2C, item values for each of a plurality of image quality items are expressed in the form of a triangular radar chart.

Before explaining the characteristic data, image quality items such as "resolution (azimuth resolution)", "S/N ratio", and "sensitivity" will be explained. FIG. 3 is a diagram showing the distribution of the signal intensity of the ultrasound beam in the azimuth direction X (scanning direction of the ultrasound beam) and the depth direction Z, and FIG. 4 is a diagram showing the distribution of the signal intensity of the ultrasound beam in the azimuth direction FIG. 3 is a diagram showing the distribution of signal intensity of an ultrasound beam in the azimuth direction X in FIG.

Referring to FIG. 4, the sensitivity is determined based on the peak value P _max of signal strength in the azimuth direction X. The resolution is determined based on the width (for example, half width) W of the peak (main lobe) that constitutes the peak value P _max of the signal intensity. The S/N ratio is determined based on the ratio between the main lobe signal component E _S and the side lobe signal component E _N.

In the upper radar charts of FIGS. 2A to 2C, the item values of each image quality item in the current shooting parameters are shown as reference values. In the lower radar charts of FIGS. 2A to 2C, the item value of each image quality item after the change is shown, and the reference value (current item value) of each image quality item is shown with a broken line. The lower radar charts in FIGS. 2A to 2C are characteristic data indicating the amount of change from the current item value for each image quality item.

In the example of FIG. 2A, for example, the signal characteristics of the received frame data or the image characteristics of the ultrasound image indicate that ultrasound waves have poor passage and deep sensitivity is low. Depending on the characteristics, characteristic data that increases sensitivity is determined. Note that in the example of FIG. 2A, the characteristic data indicates that the resolution is lowered, but the resolution does not necessarily need to be lowered.

In the example of FIG. 2B, for example, the signal characteristics of the received frame data or the image characteristics of the ultrasound image indicate that deep parts are depicted with sufficient sensitivity, so the characteristic data determining unit 34 Depending on the characteristics, characteristic data that increases resolution is determined. Note that in the example of FIG. 2B, the characteristic data indicates that the sensitivity is lowered, but the sensitivity does not necessarily need to be lowered.

In the example of FIG. 2C, for example, the signal characteristics of the received frame data or the image characteristics of the ultrasound image indicate that there is a considerable amount of noise, so the characteristic data determining unit 34 determines the S Characteristic data that increases the /N ratio is determined. Note that in the example of FIG. 2C, the characteristic data indicates that the resolution is lowered, but the resolution does not necessarily need to be lowered.

As described above, the characteristic data determining unit 34 automatically determines the characteristic data based on the signal characteristics of the received frame data or the image characteristics of the ultrasound image. The determined characteristic data may be presented to the user, and the determined specific data may be modified based on instructions from the user.

The parameter determining unit 36 determines (changes) imaging parameters based on the characteristic data determined (or modified) by the characteristic data determining unit 34. In the examples of FIGS. 2A to 2C, the parameter to be adjusted is the transmit beamforming parameter, but as described above, the imaging parameters include the transmit beamforming parameter, the receive beamforming parameter, the signal processing parameter, and the image capture parameter. Since at least one of the forming process parameters is included, the parameter determining unit 36 determines at least one of these parameters.

For example, if the characteristic data determined by the characteristic data determining section 34 is such as to increase the sensitivity (for example, as shown in FIG. 2A), the parameter determining section 36 adjusts the imaging parameters so that the sensitivity increases. Here, the transmission beam parameters may include a plurality of parameters, and each parameter may affect a plurality of image quality items. Also, depending on the image quality item included in the characteristic data, multiple parameters included in multiple parameter types (transmission beamforming parameters, reception beamforming parameters, signal processing parameters, and image forming processing parameters) included in the imaging parameters may be affected. There may be cases. Therefore, the parameter determining unit 36 determines the imaging parameters using the following method.

A first method for determining imaging parameters is to refer to the imaging parameter DB 30 stored in the memory 28 as an LUT (Look Up Table). The imaging parameter DB 30 includes characteristic data (as described above, representing the amount of change from the current item value for each of a plurality of image quality items) and information indicating the amount of change in the imaging parameter (each parameter included). Multiple combinations are stored. The imaging parameter DB 30 is created in advance by, for example, the manufacturer or administrator of the ultrasound diagnostic apparatus 10, and is stored in the memory 28. The parameter determining unit 36 searches the imaging parameter DB 30 using the specific data determined by the characteristic data determining unit 34 as a key, and identifies the amount of change in the imaging parameter associated with the specific data (or specific data similar thereto). . Then, by applying the specified change amount to the current imaging parameter, the adjusted imaging parameter is obtained.

The second method for determining imaging parameters is to generate an objective function regarding the image quality item of interest among a plurality of image quality items using the imaging parameter as a variable, and to optimize the objective function. This is a method of determining imaging parameters that increase (or decrease) the number of image quality items of interest. According to this method, there is no need to prepare the imaging parameter DB 30 in advance. For example, a case will be described in which the image quality item of interest is the S/N ratio and a plurality of parameters included in the transmission beamforming parameters are optimized so as to minimize the S/N ratio.

となる。式１において、ｐは送信ビームフォーミングパラメータに含まれる複数のパラメータから成るパラメータベクトルｐ＝（ｐ_１、ｐ_２、・・・、ｐ_ｎ）を表し、Ｅ_Ｎはサイドローブの信号成分を表し、Ｅ_Ｓはメインローブの信号成分を表す（図４参照）。パラメータ決定部３６は、この目的関数を最小化するようなパラメータベクトルｐを探索する。 The objective function here is

becomes. In Equation 1, p represents a parameter vector p=(p ₁ , p ₂ , . . . , p _n ) consisting of multiple parameters included in the transmit beamforming parameters, E _N represents a sidelobe signal component, E _S represents the main lobe signal component (see FIG. 4). The parameter determination unit 36 searches for a parameter vector p that minimizes this objective function.

∇ｆ（ｐ）は、パラメータベクトルｐを微量変化させたときにｆ（ｐ）の変化量が最大となる方向を意味する。したがって、パラメータ決定部３６は、演算した勾配ベクトル∇ｆ（ｐ）が示す方向とは反対方向、すなわち、－∇ｆ（ｘ）の方向にパラメータベクトルｐの各成分を所定量（微量）変化させる。ここでの変化量は、予め定められていてよい。 First, the parameter determining unit 36 calculates the gradient vector ∇f(p) of f(p), which is expressed by the following equation 2.

∇f(p) means the direction in which the amount of change in f(p) is maximum when the parameter vector p is slightly changed. Therefore, the parameter determining unit 36 changes each component of the parameter vector p by a predetermined amount (a small amount) in the opposite direction to the direction indicated by the calculated gradient vector ∇f(p), that is, in the direction of −∇f(x). . The amount of change here may be determined in advance.

The parameter determination unit 36 calculates the gradient vector ∇f(p) again using the above equation (2) for the parameter vector p after the change, and repositions each component of the parameter vector p in the direction of -∇f(x). Change quantitatively.

By repeating this process and searching for the parameter vector p, if f(p) is determined to be sufficiently small, for example, if the magnitude of the gradient vector ∇f(x) is less than a predetermined value. In this case, the parameter vector p is set as the adjusted transmission beamforming parameter.

As described above, when determining imaging parameters by minimizing the objective function, even if the image quality item of interest is optimized, the values of other image quality items may become undesirable. In the above example, it is not appropriate for minimizing the signal-to-noise ratio to result in a significant decrease in resolution or sensitivity.

Therefore, the parameter determining unit 36 sets the imaging parameters by minimizing the objective function after imposing constraints on image quality items other than the image quality item of interest among the plurality of image quality items in the objective function regarding the image quality item of interest. It is good to decide. For example, if equation 1 is the objective function,
Constraints on resolution: average value of resolution within the imaging range > current value x W ₁
Constraints on sensitivity: average value of sensitivity within the imaging range > current value x W ₂
It is recommended to add a constraint condition such as: Here, W ₁ and W ₂ are weights, which may be predetermined by the user or the like.

According to the above constraint conditions, when optimizing the image quality item of interest, it is possible to prevent image quality items other than the image quality item of interest from falling below a predetermined value (more specifically, current value x weight). As a method for minimizing the objective function with constraint conditions imposed, for example, sequential quadratic programming, interior point method, extended Lagrangian function method, etc. can be used.

As described above, in this embodiment, the characteristic data determining section 34 determines the characteristic data, and the parameter determining section 36 determines the imaging parameters based on the characteristic data. However, the parameter determining unit 36 can also directly determine the imaging parameters (particularly the transmit beamforming parameters or the receive beamforming parameters) based on the signal characteristics of the received frame data or the image characteristics of the ultrasound image. However, in this case, the signal characteristics of the received frame data or the image characteristics of the ultrasonic image may have characteristic values for a huge number of characteristic items. If you try to optimize it, the amount of calculations may become large. In particular, when the probe 12 is a two-dimensional ultrasound probe and the received frame data is volume data, the amount of calculation becomes particularly large.

Therefore, it is desirable that the characteristic data determination section 34 determine the characteristic data, and that the parameter determination section 36 determine the imaging parameters based on the characteristic data. That is, by using the characteristic data, it is possible to reduce the amount of calculation for determining the imaging parameters.

The parameter determining section 36 transmits the determined (changed) imaging parameters to each section of the transmitting section 14, the receiving section 16, the signal processing section 18, or the image forming section 20. Each of the above units that has received the changed imaging parameters performs processing using the changed imaging parameters. Thereby, a higher quality ultrasound image can be formed compared to the case where the imaging parameters before the change are used.

Similar to FIG. 4, FIG. 5 is a diagram showing the distribution of the signal intensity of the ultrasound beam in the azimuth direction X at a predetermined depth. In FIG. 5, the broken line shows the distribution of the ultrasound beam signal intensity when transmitting beamforming is performed using the transmitting beamforming parameters before the change, and the solid line shows the transmitting beam signal intensity distribution when transmitting beamforming is performed using the transmitting beamforming parameters after the change. It shows the distribution of ultrasound beam signal intensity when forming. As shown in FIG. 5, the S/N ratio of the ultrasound beam is improved according to changes in the transmit beamforming parameters.

Hereinafter, the flow of processing of the ultrasound diagnostic apparatus 10 according to this embodiment will be explained according to the flowchart shown in FIG.

In step S10, the transmitter 14 transmits a transmit signal based on the current transmit beamforming parameters to the probe 12. As a result, transmission beam forming is performed by the probe 12, and an ultrasound beam is transmitted to the subject. Then, the probe 12 receives the reflected wave from the subject and transmits the received signal to the receiving section 16. The receiving unit 16 performs receive beamforming based on current receive beamforming parameters and generates a receive frame signal.

In step S12, the signal processing unit 18 performs signal processing based on the current signal processing parameters. The image forming unit 20 also performs image forming processing based on current image forming parameters to form an ultrasound image.

In step S14, the characteristic data determination unit 34 analyzes the signal characteristics of the received frame data after signal processing or the image characteristics of the ultrasound image.

In step S16, the characteristic data determination unit 34 determines characteristic data (see FIGS. 2A to 2C) based on the analysis result in step S14.

In step S18, the parameter determination unit 36 determines the changed imaging parameters based on the characteristic data determined in step S16, by a method using an LUT, a method of optimizing an objective function, or the like.

In step S20, the parameter determining unit 36 transmits the changed imaging parameters determined in step S18 to at least one of the transmitting unit 14, the receiving unit 16, the signal processing unit 18, or the image forming unit 20.

In step S22, the transmitting unit 14, receiving unit 16, signal processing unit 18, and image forming unit 20 acquire received frame data using the changed imaging parameters, perform signal processing on the received frame data, and receive Generate ultrasound images based on frame data.

Although the embodiments according to the present invention have been described above, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

Reference Signs List 10 ultrasound diagnostic apparatus, 12 probe, 14 transmitter, 16 receiver, 18 signal processor, 20 image generator, 22 display controller, 24 display, 26 input interface, 28 memory, 30 imaging parameter DB, 32 controller , 34 characteristic data determination section, 36 parameter determination section.

Claims (9)

Transmission beamforming parameters related to ultrasound transmission beamforming based on signal characteristics of reception frame data obtained by transmitting and receiving ultrasound or image characteristics of an ultrasound image formed based on the reception frame data. , or a parameter determination unit that determines at least one of reception beamforming parameters regarding ultrasound reception beamforming;
An ultrasonic diagnostic device comprising: The transmission beamforming parameters include a transmission aperture indicating a transducer element that transmits ultrasonic waves out of the transducer array included in the ultrasound probe, a transmission focus of the ultrasonic wave to be transmitted to the subject, and each of the transmission apertures included in the transmission aperture. Transmission apodization indicating the amplitude of the ultrasonic waves transmitted from the transducer element, a waveform of a transmission signal that is an electric signal supplied to the ultrasonic probe, and transmission timing of the ultrasonic waves from each of the transducer elements included in the transmission aperture. , or a transmission interval of ultrasonic waves transmitted to the subject,
The reception beamforming parameters include a reception aperture indicating a transducer that receives reflected waves from the subject in the transducer array of the ultrasonic probe, a reception focus of the reflected waves, and each of the transducers included in the reception aperture. Includes a parameter for determining at least one of reception apodization that is attached to a vibrating element and indicates the weight of a reflected wave received by each vibrating element, a reception interval of the reflected waves, or a synthesis weighting coefficient in aperture synthesis processing. Become,
The ultrasonic diagnostic apparatus according to claim 1, characterized in that: Based on the signal characteristics of the received frame data or the image characteristics of the ultrasound image formed based on the received frame data, characteristic data representing the amount of change for each of a plurality of image quality items regarding the image quality of the ultrasound image is generated. a characteristic data determining unit to determine;
Furthermore,
The parameter determining unit determines at least one of the transmit beamforming parameter or the receive beamforming parameter based on the determined characteristic data.
The ultrasonic diagnostic apparatus according to claim 1 or 2, characterized in that: Each of a plurality of image quality items related to the image quality of an ultrasound image is determined based on the signal characteristics of received frame data obtained by transmitting and receiving ultrasound, or the image characteristics of an ultrasound image formed based on the received frame data. a characteristic data determination unit that determines characteristic data representing the amount of change in;
a parameter determination unit that determines imaging parameters related to processing from transmission and reception of ultrasound to formation of ultrasound images based on the determined characteristic data;
An ultrasonic diagnostic device comprising: The imaging parameters include transmission beamforming parameters related to ultrasound transmission beamforming, reception beamforming parameters related to ultrasound reception beamforming, signal processing parameters related to signal processing for received frame data, or signal processing parameters related to ultrasound image formation processing. at least one image forming processing parameter is included;
The ultrasonic diagnostic apparatus according to claim 4, characterized in that: The parameter determining unit refers to an imaging parameter database storing a plurality of combinations of the characteristic data and information indicating the amount of change in the imaging parameter, and selects a characteristic that is the same as or similar to the characteristic data in the imaging parameter database. determining the imaging parameter based on information indicating the amount of change in the imaging parameter associated with data;
The ultrasonic diagnostic apparatus according to claim 4 or 5, characterized in that: The parameter determination unit determines the imaging parameters by an optimization process that optimizes a focused image quality item among the plurality of image quality items.
The ultrasonic diagnostic apparatus according to claim 4 or 5, characterized in that: The parameter determining unit determines the imaging parameters by the optimization process that imposes constraints on image quality items other than the image quality item of interest among the plurality of image quality items.
The ultrasonic diagnostic apparatus according to claim 7, characterized in that: The received frame data is volume data obtained by a two-dimensional ultrasound probe in which vibrating elements are two-dimensionally arranged.
The ultrasonic diagnostic apparatus according to claim 6, characterized in that:

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