Ultrasound diagnostic equipment

Abstract

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

Description

【Technical Field】 【0001】 This specification discloses an ultrasonic diagnostic apparatus. 【Background Art】 【0002】 An ultrasonic diagnostic apparatus transmits an ultrasonic beam generated by transmission beamforming from a plurality of vibration elements arranged on an ultrasonic probe to a subject, and receives a reflected wave generated during the propagation process in the subject by the plurality of vibration elements and converts it into a received signal. Then, an addition processing is performed while giving a predetermined delay value to the received signal obtained for each vibration element. This process is repeated while moving (scanning) the transmission position to obtain received frame data, which is a coherent signal within the imaging region (received beamforming). For the received frame data thus obtained, signal processing including reception filter processing such as band shaping and detection processing, or image formation processing is performed to form an ultrasonic image. 【0003】 Various imaging parameters are involved in each process until an ultrasonic image is formed. Some of the imaging parameters can be set by a user such as a doctor. The imaging parameters include, for example, transmission beamforming parameters related to transmission beamforming of ultrasonic waves, reception beamforming parameters related to reception beamforming of ultrasonic waves, signal processing parameters related to signal processing for received frame data, or image formation processing parameters related to image formation processing of ultrasonic images. 【0004】 The above various parameters greatly affect the image quality such as the resolution and contrast of the formed ultrasonic image. Therefore, in order to obtain a high-quality ultrasonic image, it is desirable to appropriately set these parameters. However, since the optimal values of these parameters may vary depending on the imaging target and the biological characteristics of the subject, it may be difficult for a user with little experience to set appropriate parameters. 【0005】 In light of the above, an automatic parameter adjustment function has been proposed for the purpose of improving the image quality of ultrasound images. For example, Patent Document 1 discloses a technique for setting parameters related to the transmission frequency and receiving filter based on the depth penetration of the ultrasound beam obtained by analyzing the received signal at a predetermined depth, in order to suppress the deterioration of ultrasound image quality caused by the attenuation of ultrasound within the subject. [Prior art documents] [Patent Documents] 【0006】 [Patent Document 1] Japanese Patent Publication No. 2021-83956 [Overview of the project] [Problems that the invention aims to solve] 【0007】 The technology described in Patent Document 1 discloses an adaptive setting method for the transmission frequency and the receiving filter. However, Patent Document 1 only discloses a method for setting a limited portion of the imaging parameters, and does not show a method for appropriately setting other imaging parameters, particularly the transmission beamforming parameters and the receiving beamforming parameters (which may be collectively referred to simply as "beamforming parameters" in this specification). Note that the transmission frequency is simply the frequency of the transmitted ultrasound, and this is not a parameter related to transmission beamforming that forms the ultrasound beam. Furthermore, since it is often desirable for ultrasound images to be formed (and displayed) in real time with respect to the transmission timing of the ultrasound beam, it is also desirable to reduce the amount of computation required for determining imaging parameters in order to shorten the processing time for determining imaging parameters. 【0008】 The objective of the ultrasound diagnostic apparatus disclosed herein is to determine beamforming parameters that can form high-quality ultrasound images. Alternatively, the objective of the ultrasound diagnostic apparatus disclosed herein is to reduce the computational load of the imaging parameter determination process. [Means for solving the problem] 【0009】 The ultrasonic diagnostic apparatus disclosed herein is characterized by comprising a parameter determination unit that determines at least one of a transmission beamforming parameter for ultrasonic transmission beamforming or a reception beamforming parameter for ultrasonic reception beamforming, based on the signal characteristics of received frame data obtained by transmitting and receiving ultrasonic waves, or the image characteristics of an ultrasonic image formed based on the received frame data. Furthermore, the transmit beamforming parameters may include parameters for determining at least one of the following: a transmit aperture indicating a vibrating element that transmits ultrasound among the vibrating element array of the ultrasonic probe; a transmit focal point for the ultrasound transmitted to the subject; a transmit apodization indicating the amplitude of the ultrasound transmitted from each of the vibrating elements included in the transmit aperture; a waveform of the transmit signal, which is an electrical signal supplied to the ultrasonic probe; the transmit timing of the ultrasound from each of the vibrating elements included in the transmit aperture; or the transmit interval of the ultrasound transmitted to the subject. The receive beamforming parameters may include parameters for determining at least one of the following: a receive aperture indicating a transducer that receives reflected waves from the subject among the vibrating element array of the ultrasonic probe; a receive focal point for the reflected waves; a receive apodization indicating the weight of the reflected waves received by each of the vibrating elements included in the receive aperture; or a composite weight coefficient in the aperture synthesis process. 【0010】 According to this configuration, at least one of the transmit beamforming parameters or receive beamforming parameters is 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 transmit beamforming parameters or receive beamforming parameters determined by the parameter determination unit, a higher-quality ultrasound image can be formed compared to an ultrasound image formed using the transmit beamforming parameters or receive beamforming parameters before the change. 【0011】 The system further includes a characteristic data determination unit that determines characteristic data representing the amount of change for each of a plurality of image quality items relating to the image quality of an ultrasonic image, based on the signal characteristics of the received frame data or the image characteristics of an ultrasonic image formed based on the received frame data, and the parameter determination unit may determine at least one of the transmitted beamforming parameter or the received beamforming parameter based on the determined characteristic data. 【0012】 According to this configuration, the parameter determination unit performs a process to determine at least one of the transmit beamforming parameters or the receive beamforming parameters using the amount of change in each image quality item indicated by the characteristic data as an indicator, thereby reducing the computational load for determining at least one of the transmit beamforming parameters or the receive beamforming parameters. 【0013】 The ultrasound diagnostic apparatus disclosed herein is characterized by comprising: a characteristic data determination unit that determines characteristic data representing the amount of change for each of a plurality of image quality items relating to the image quality of an ultrasound image 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; and a parameter determination unit that determines imaging parameters relating to the processing from transmitting and receiving ultrasound to forming an ultrasound image based on the determined characteristic data. Furthermore, the imaging parameters may include at least one of the following: a transmission beamforming parameter related to the transmission beamforming of ultrasound, a reception beamforming parameter related to the reception beamforming of ultrasound, a signal processing parameter related to signal processing of received frame data, or an image forming processing parameter related to the formation of an ultrasound image. 【0014】 According to this configuration, 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 can be formed compared to an ultrasound image formed using the imaging parameters before the change. At the same time, according to this configuration, the computational load of the imaging parameter determination process can be reduced by performing the processing of determining imaging parameters using the amount of change in each image quality item indicated by the characteristic data as an indicator. 【0015】 The parameter determination unit may refer to an imaging parameter database which stores multiple combinations of characteristic data and information indicating the amount of change in the imaging parameters, and determine the imaging parameters based on the information in the imaging parameter database that indicates the amount of change in the imaging parameters associated with characteristic data that is the same as or similar to the characteristic data. 【0016】 According to this configuration, the computational load of the imaging parameter determination process can be further reduced by determining the imaging parameters by referring to the imaging parameter database. 【0017】 The parameter determination unit may determine the imaging parameters by performing an optimization process that optimizes the image quality item of interest among the multiple image quality items. 【0018】 This configuration allows for the determination of imaging parameters without the need to prepare an imaging parameter database in advance. 【0019】 The parameter determination unit may determine the imaging parameters by the optimization process that imposes constraint conditions on image quality items other than the target image quality item among the plurality of image quality items. 【0020】 According to this configuration, it is possible to determine imaging parameters in which the target image quality item is optimized while suppressing deterioration of image quality items other than the target image quality item. 【0021】 The received frame data may be volume data obtained by a two-dimensional ultrasonic probe in which vibration elements are two-dimensionally arranged. 【0022】 According to this configuration, when the received frame data is volume data, which causes a particularly large amount of computation in the determination process of imaging parameters, it is possible to reduce the amount of computation in the determination process of imaging parameters. 【Advantages of the Invention】 【0023】 According to the ultrasonic diagnostic apparatus disclosed in this specification, it is possible to determine beamforming parameters capable of forming a high-quality ultrasonic image. Alternatively, according to the ultrasonic diagnostic apparatus disclosed in this specification, it is possible to reduce the amount of computation in the determination process of imaging parameters. 【Brief Description of the Drawings】 【0024】 [Figure 1] It is a schematic configuration diagram of an ultrasonic diagnostic apparatus according to this embodiment. [Figure 2A] It is a diagram showing a first example of specific characteristic data. [Figure 2B] It is a diagram showing a second example of specific characteristic data. [Figure 2C] It is a diagram showing a third example of specific characteristic data. [Figure 3] It is a diagram showing the distribution of signal intensities of ultrasonic beams in the azimuth direction and the depth direction. [Figure 4] It is a diagram showing the distribution of signal intensities of ultrasonic beams with respect to the azimuth direction at a predetermined depth. [Figure 5] This figure shows how the signal-to-noise ratio (S / N ratio) of the ultrasonic beam improved in response to changes in the transmitted beamforming parameters. [Figure 6] This flowchart shows the processing flow of the ultrasound diagnostic device according to this embodiment. [Modes for carrying out the invention] 【0025】 Figure 1 is a schematic diagram of the configuration of the ultrasound diagnostic device 10 according to this embodiment. The ultrasound diagnostic device 10 is a medical device installed in a medical institution such as a hospital and used during ultrasound examinations. 【0026】 The ultrasound diagnostic device 10 can operate in multiple operating modes, including B-mode. B-mode is a mode in which an ultrasound image (B-mode image) is generated and displayed based on received frame data obtained by scanning an ultrasound beam (transmitting beam), in which the amplitude intensity of the reflected wave from the scanning surface is converted into brightness. 【0027】 The probe 12, which is an ultrasonic probe, is a device that transmits an ultrasonic beam and receives reflected waves. Specifically, the probe 12 is in contact with the surface of the subject's body, transmits an ultrasonic beam toward the subject, and receives reflected waves reflected from the tissue within the subject. Inside the probe 12 is a vibrating element array consisting of multiple vibrating elements. Each vibrating element in the vibrating element array is supplied with a transmission signal, which is an electrical signal, from the transmission unit 14 (described later), thereby generating an ultrasonic beam (transmitting beam). In this specification, the process of generating an ultrasonic beam based on the transmission signal is called transmitting beamforming. In addition, each vibrating element in the vibrating element array receives reflected waves from the subject, converts the reflected waves into received signals, which are electrical signals, and transmits them to the receiving unit 16 (described later). 【0028】 The probe 12 may be a one-dimensional ultrasonic probe composed of multiple vibrating elements in which the transducer array is arranged in one dimension, or it may be a two-dimensional ultrasonic probe composed of multiple vibrating elements in which the transducer array is arranged in two dimensions. 【0029】 The transmitting unit 14 supplies multiple transmission signals in parallel to the probe 12 (more specifically, the vibrating element array) when transmitting ultrasound. This enables transmission beamforming, and an ultrasonic beam is transmitted from the probe 12. 【0030】 The transmitting unit 14 generates a plurality of transmission signals to be supplied to the probe 12 based on the transmission beamforming parameters. The transmission beamforming parameters include parameters for determining at least one of the following: a transmitting aperture indicating the vibrating element that transmits ultrasound among the vibrating element array of the probe 12; a transmitting focus of ultrasound transmitted to the subject; a transmitting apodization indicating the amplitude of ultrasound transmitted from each vibrating element included in the transmitting aperture; a waveform of the transmission signal; the transmission timing of ultrasound from each vibrating element included in the transmitting aperture; or the transmission interval of ultrasound transmitted to the subject. 【0031】 The transmission beamforming parameters referenced by the transmission unit 14 may be predetermined (default values) in the ultrasound diagnostic device 10. Alternatively, the transmission beamforming parameters referenced by the transmission unit 14 may be determined based on instructions from a user, such as a physician, input through the input interface 26 described later. Furthermore, in this embodiment, the transmission beamforming parameters referenced by the transmission unit 14 may be determined by the parameter determination unit 36 ​​described later. 【0032】 When receiving reflected waves, the receiving unit 16 receives multiple received signals from the probe 12 (more specifically, the vibrating element array) in parallel. The receiving unit 16 performs various processing on the multiple received signals, thereby generating received frame data. In this specification, the process of generating received frame data based on multiple received signals is called received beamforming. 【0033】 The receiving unit 16 performs receive beamforming based on the receive beamforming parameters. The receive beamforming parameters include parameters for determining at least one of the following: a receiving aperture that indicates the oscillator among the vibrating element array of the probe 12 that receives the reflected wave from the subject; a receiving focus for the reflected wave; a receiving apodization that is applied to each vibrating element included in the receiving aperture and indicates the weight of the reflected wave received by each vibrating element; a receiving interval for the reflected wave; or a composite weighting coefficient in the aperture synthesis process. 【0034】 The receiving beamforming parameters referenced by the receiving unit 16 may be predetermined (default values) in the ultrasound diagnostic device 10. Alternatively, the receiving beamforming parameters referenced by the receiving unit 16 may be determined based on user instructions input from the input interface 26 described later. Furthermore, in this embodiment, the receiving beamforming parameters referenced by the receiving unit 16 may be determined by the parameter determination unit 36 ​​described later. 【0035】 The signal processing unit 18 performs various signal processing on the received frame data from the receiving unit 16, including filtering and gain correction. The signal processing unit 18 performs various signal processing based on signal processing parameters related to signal processing on the received frame data. These signal processing parameters include, for example, the coefficients of the filter used for filtering (e.g., a bandpass filter) and the gain coefficients referenced during gain correction processing. 【0036】 The signal processing parameters referenced by the signal processing unit 18 may be predetermined (default values) in the ultrasound diagnostic device 10. Alternatively, the signal processing parameters referenced by the signal processing unit 18 may be determined based on user instructions input from the input interface 26 described later. Furthermore, in this embodiment, the signal processing parameters referenced by the signal processing unit 18 may be determined by the parameter determination unit 36 ​​described later. 【0037】 The image forming unit 20 is composed of a digital scan converter and the like, and performs image forming processing to form an ultrasonic image (B-mode image in this embodiment) based on frame data received from the signal processing unit 18. In the image forming processing, various image processing such as gain correction processing, noise reduction processing, and edge enhancement processing are performed based on image forming processing parameters related to the ultrasonic image formation processing. The image forming processing parameters include, for example, a gain coefficient referenced during gain correction processing, and parameters related to noise reduction processing and edge enhancement processing. 【0038】 The image forming processing parameters referenced by the image forming unit 20 may be predetermined (default values) in the ultrasound diagnostic apparatus 10. Alternatively, the image forming processing parameters referenced by the image forming unit 20 may be determined based on user instructions input from the input interface 26 described later. Furthermore, in this embodiment, the image forming processing parameters referenced by the image forming unit 20 may be determined by the parameter determination unit 36 ​​described later. 【0039】 The display control unit 22 displays the ultrasonic image generated by the image forming unit 20 on a display 24, which is made up of, for example, a liquid crystal panel. 【0040】 The input interface 26 consists of, for example, buttons, a trackball, or a touch panel. The input interface 26 is for inputting user instructions to the ultrasound diagnostic device 10. 【0041】 The memory 28 is composed of components such as an HDD (Hard Disk Drive), SSD (Solid State Drive), eMMC (embedded Multi Media Card), ROM (Read Only Memory), or RAM (Random Access Memory). The memory 28 stores ultrasound diagnostic programs for operating each part of the ultrasound diagnostic device 10. The ultrasound diagnostic programs can also be stored on a computer-readable non-temporary storage medium such as a USB (Universal Serial Bus) memory or CD-ROM. The ultrasound diagnostic device 10 can read and execute ultrasound diagnostic programs from such storage media. In addition, as shown in Figure 1, the memory 28 stores an imaging parameter DB (Data Base) 30. The imaging parameter DB 30 will be described later. 【0042】 The control unit 32 is comprised of at least one general-purpose processor (e.g., a CPU (Central Processing Unit)) and a dedicated processor (e.g., a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a programmable logic device). The control unit 32 may not consist of a single processing unit, but rather of multiple processing units located in physically separate locations working together. The control unit 32 controls each part of the ultrasound diagnostic device 10 according to the ultrasound diagnostic program stored in the memory 28. 【0043】 In the ultrasound diagnostic apparatus 10, imaging parameters can be automatically adjusted based on the signal characteristics of the received frame data processed by the signal processing unit 18, or the image characteristics of the ultrasound image formed by the image forming unit 20. The imaging parameters include at least one of the following: a transmission beamforming parameter referenced by the transmission unit 14, a reception beamforming parameter referenced by the reception unit 16, a signal processing parameter referenced by the signal processing unit 18, and an image forming processing parameter referenced by the image forming unit 20. The automatic adjustment process of imaging parameters will be described below, along with details of the characteristic data determination unit 34 and the parameter determination unit 36. 【0044】 The transmitting unit 14, receiving unit 16, signal processing unit 18, image forming unit 20, display control unit 22, characteristic data determination unit 34, and parameter determination unit 36 ​​are each composed of one or more processors, chips, electrical circuits, etc. These units may also be realized through the cooperation of hardware and software. 【0045】 The characteristic data determination unit 34 determines characteristic data representing the amount of change from the current item value for each of several image quality items related to the image quality of the ultrasound image, based on the signal characteristics of the signal-processed received frame data received from the signal processing unit 18, or the image characteristics of the ultrasound image received from the image forming unit 20. 【0046】 Figures 2A to 2C show examples of specific characteristic data. Here, we will explain using the case of adjusting the transmit beamforming parameter in the imaging data as an example. In this example, the characteristic data has multiple image quality items: "resolution (azimuth resolution)", "S / N ratio", and "sensitivity". Note that the multiple image quality items that the characteristic data has are not limited to these. In Figures 2A to 2C, the item values ​​for each of the multiple image quality items are represented in the form of a triangular radar chart. 【0047】 Before explaining the characteristic data, we will explain the image quality parameters: "resolution (azimuth resolution)," "S / N ratio," and "sensitivity." Figure 3 shows the distribution of the ultrasonic beam signal intensity in the azimuth direction X (scanning direction of the ultrasonic beam) and the depth direction Z, and Figure 4 shows the distribution of the ultrasonic beam signal intensity with respect to the azimuth direction X at a predetermined depth (depth indicated by A in Figure 3). 【0048】 Referring to Figure 4, sensitivity is the peak value P of signal intensity in the azimuthal direction X. max It is determined based on the peak value of the signal intensity P. max The signal-to-noise ratio (S / N ratio) is determined based on the width (e.g., full width at half maximum) W of the main lobe that makes up the signal. S and the signal component E of the side lobe N It is determined based on the ratio. 【0049】 In the upper radar charts of Figures 2A to 2C, the item values ​​for each image quality parameter with the current shooting parameters are shown as reference values. In the lower radar charts of Figures 2A to 2C, the item values ​​for each image quality parameter after the change are shown, and the reference value (current item value) for each image quality parameter is shown by a dashed line. The lower radar charts of Figures 2A to 2C are characteristic data showing the amount of change from the current item value for each image quality parameter. 【0050】 In the example in Figure 2A, for example, the signal characteristics of the received frame data or the image characteristics of the ultrasound image showed that ultrasound penetration was poor and the sensitivity to deep areas was low. Therefore, the characteristic data determination unit 34 determined characteristic data that would increase the sensitivity according to those characteristics. Note that in the example in Figure 2A, the characteristic data indicates that the resolution will decrease, but it is not always necessary to decrease the resolution. 【0051】 In the example in Figure 2B, for example, the signal characteristics of the received frame data or the image characteristics of the ultrasound image showed that the depths were depicted with sufficient sensitivity. Therefore, the characteristic data determination unit 34 determined characteristic data that would increase the resolution according to these characteristics. Note that in the example in Figure 2B, the characteristic data shows that the sensitivity should be reduced, but it is not always necessary to reduce the sensitivity. 【0052】 In the example in Figure 2C, for example, the signal characteristics of the received frame data or the image characteristics of the ultrasound image showed a considerable amount of noise. Therefore, the characteristic data determination unit 34 determined characteristic data that would increase the signal-to-noise ratio according to those characteristics. Note that in the example in Figure 2C, the characteristic data shows that the resolution will decrease, but it is not always necessary to decrease the resolution. 【0053】 As described above, the characteristic data determination unit 34 automatically determines characteristic data based on the signal characteristics of the received frame data or the image characteristics of the ultrasound image. The characteristic data determination unit 34 may also present the determined characteristic data to the user and modify the determined specific data based on instructions from the user. 【0054】 The parameter determination unit 36 ​​determines (changes) the imaging parameters based on the characteristic data determined (or modified) by the characteristic data determination unit 34. In the example shown in Figures 2A to 2C, the parameter to be adjusted is the transmit beamforming parameter, but as described above, the imaging parameters include at least one of the transmit beamforming parameter, receive beamforming parameter, signal processing parameter, and image formation processing parameter. Therefore, the parameter determination unit 36 ​​determines at least one of these parameters. 【0055】 For example, if the characteristic data determined by the characteristic data determination unit 34 is such that it increases sensitivity (as shown in Figure 2A, for example), the parameter determination unit 36 ​​adjusts the imaging parameters to increase sensitivity. Here, the transmission beam parameters may consist of multiple parameters, and each parameter may affect multiple image quality items. Also, depending on the image quality items of the characteristic data, multiple parameters of multiple parameter types included in the imaging parameters (transmission beamforming parameters, reception beamforming parameters, signal processing parameters, and image formation processing parameters) may have an effect. Therefore, the parameter determination unit 36 ​​determines the imaging parameters in the following manner. 【0056】 The first method for determining imaging parameters is to refer to the imaging parameter DB30 stored in memory 28 as a LUT (Look Up Table). The imaging parameter DB30 stores multiple combinations of characteristic data (which, as described above, represents the amount of change from the current item value for each of the multiple image quality items) and information indicating the amount of change of imaging parameters (each parameter included in them). The imaging parameter DB30 is created in advance by, for example, the manufacturer or manager of the ultrasound diagnostic device 10 and stored in memory 28. The parameter determination unit 36 ​​searches the imaging parameter DB30 using the specific data determined by the characteristic data determination unit 34 as a key and identifies the amount of change of the imaging parameter associated with that specific data (or similar specific data). Then, by applying the identified amount of change to the current imaging parameter, the adjusted imaging parameter is obtained. 【0057】 A second method for determining imaging parameters involves generating an objective function for a particular image quality item among multiple image quality items, using the imaging parameters as variables, and then optimizing this objective function to determine imaging parameters that increase (or decrease) the particular image quality item as indicated by specific data. This method eliminates the need to prepare the imaging parameter DB30 in advance. For example, let's consider a case where the particular image quality item is the signal-to-noise ratio (S / N ratio), and multiple parameters included in the transmission beamforming parameters are optimized to minimize the S / N ratio. 【0058】 The objective function here is: 【number】 In equation 1, p is a parameter vector consisting of multiple parameters included in the transmit beamforming parameters p=(p1, p2, ..., p n ) represents E N represents the signal component of the side lobe, E S This represents the signal component of the main lobe (see Figure 4). The parameter determination unit 36 ​​searches for a parameter vector p that minimizes this objective function. 【0059】 First, the parameter determination unit 36 ​​calculates the gradient vector ∇f(p) of f(p), which is represented by the following equation 2. 【number】 ∇f(p) represents the direction in which the change in f(p) is maximized when the parameter vector p is changed by a small amount. Therefore, the parameter determination unit 36 ​​changes each component of the parameter vector p by a predetermined amount (a small amount) in the direction opposite to the direction indicated by the calculated gradient vector ∇f(p), i.e., in the direction of -∇f(x). The amount of change here may be predetermined. 【0060】 The parameter determination unit 36 ​​calculates the gradient vector ∇f(p) again using equation (2) above for the changed parameter vector p, and changes each component of the parameter vector p again by a predetermined amount in the direction of -∇f(x). 【0061】 This process is repeated to search for the parameter vector p, and if it is determined that f(p) is sufficiently small, for example, if the magnitude of the gradient vector ∇f(x) is less than a predetermined value, then the parameter vector p is used as the adjusted transmit beamforming parameter. 【0062】 As mentioned above, when determining imaging parameters by minimizing the objective function, even if the image quality parameter of interest is optimized, the values ​​of other image quality parameters may become undesirable. In the example above, it is inappropriate if minimizing the signal-to-noise ratio results in a significant decrease in resolution or sensitivity. 【0063】 Therefore, the parameter determination unit 36 ​​may determine the imaging parameters by minimizing the objective function for the image quality item of interest, after imposing constraints on image quality items other than the item of interest among multiple image quality items. For example, if Equation 1 is the objective function, Constraints on resolution: Average resolution within the imaging range > Current value × W1 Constraints on sensitivity: Average sensitivity within the imaging range > Current value × W2 It is advisable to add the following constraint: Here, W1 and W2 are weights, which may be predetermined by the user or other means. 【0064】 Under the above constraints, when optimizing the image quality parameter of interest, it is possible to prevent other image quality parameters from falling below a predetermined value (specifically, current value × weight). Methods for minimizing the objective function under these constraints include, for example, successive quadratic programming, interior-point methods, and extended Lagrangian function methods. 【0065】 As described above, in this embodiment, the characteristic data determination unit 34 determines the characteristic data, and the parameter determination unit 36 ​​determines the imaging parameters based on the characteristic data. However, the parameter determination unit 36 ​​can also directly determine the imaging parameters (particularly the transmit beamforming parameters or 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 ultrasound image may have characteristic values ​​for a vast number of characteristic items, and attempting to optimize the imaging parameters without an optimization index such as characteristic data may result in a large amount of computation. In particular, if the probe 12 is a two-dimensional ultrasound probe and the received frame data is volume data, the amount of computation becomes especially large. 【0066】 Therefore, it is desirable that the characteristic data determination unit 34 determines the characteristic data, and the parameter determination unit 36 ​​determines the imaging parameters based on the characteristic data. In other words, by utilizing the characteristic data, the amount of computation required to determine the imaging parameters can be reduced. 【0067】 The parameter determination unit 36 ​​transmits the determined (modified) imaging parameters to the transmission unit 14, the reception unit 16, the signal processing unit 18, or the image forming unit 20. The respective units that receive the modified imaging parameters process the data using the modified parameters. This makes it possible to form higher-quality ultrasound images compared to when the original imaging parameters were used. 【0068】 Figure 5, like Figure 4, shows the signal intensity distribution of the ultrasonic beam with respect to the azimuth direction X at a predetermined depth. In Figure 5, the dashed line shows the distribution of the ultrasonic beam signal intensity when transmitting beamforming is performed using the transmission beamforming parameters before the change, and the solid line shows the distribution of the ultrasonic beam signal intensity when transmitting beamforming is performed using the transmission beamforming parameters after the change. As shown in Figure 5, the signal-to-noise ratio of the ultrasonic beam is improved in accordance with the change in the transmission beamforming parameters. 【0069】 The following describes the processing flow of the ultrasound diagnostic device 10 according to this embodiment, following the flowchart shown in Figure 6. 【0070】 In step S10, the transmitting unit 14 transmits a transmission signal to the probe 12 based on the current transmission beamforming parameters. As a result, the probe 12 performs transmission beamforming, and an ultrasonic beam is transmitted to the subject. The probe 12 then receives the reflected wave from the subject and transmits the received signal to the receiving unit 16. The receiving unit 16 performs received beamforming based on the current received beamforming parameters and generates a received frame signal. 【0071】 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 the current image forming parameters to form an ultrasonic image. 【0072】 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. 【0073】 In step S16, the characteristic data determination unit 34 determines characteristic data (see Figures 2A to 2C) based on the analysis results in step S14. 【0074】 In step S18, the parameter determination unit 36 ​​determines the modified imaging parameters based on the characteristic data determined in step S16, using methods such as a method using a LUT or a method of optimizing the objective function. 【0075】 In step S20, the parameter determination unit 36 ​​transmits the modified imaging parameters determined in step S18 to at least one of the transmission unit 14, the reception unit 16, the signal processing unit 18, or the image forming unit 20. 【0076】 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 modified imaging parameters, perform signal processing on the received frame data, and generate an ultrasound image based on the received frame data. 【0077】 Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols] 【0078】 10 Ultrasound diagnostic device, 12 Probe, 14 Transmitter, 16 Receiver, 18 Signal processing unit, 20 Image generation unit, 22 Display control unit, 24 Display, 26 Input interface, 28 Memory, 30 Imaging parameter DB, 32 Control unit, 34 Characteristic data determination unit, 36 Parameter determination unit.

Claims

[Claim 1] A characteristic data determination unit that determines characteristic data representing the amount of change for each of a plurality of image quality items relating to the image quality of an ultrasonic image based on the signal characteristics of received frame data obtained by transmitting and receiving ultrasonic waves, or the image characteristics of an ultrasonic image formed based on the received frame data, presents the characteristic data to the user, and modifies the characteristic data based on instructions from the user, A parameter determination unit determines at least one of the following parameters for the ultrasonic image: a transmitting beamforming parameter, which is a parameter for determining at least one of the following: a transmitting aperture indicating a vibrating element in the vibrating element array of the ultrasonic probe that transmits ultrasonic waves; a transmitting focus of ultrasonic waves transmitted to a subject; a transmitting apodization indicating the amplitude of ultrasonic waves transmitted from each of the vibrating elements included in the transmitting aperture; a transmitting signal waveform, which is an electrical signal supplied to the ultrasonic probe; a transmitting timing of ultrasonic waves transmitted from each of the vibrating elements included in the transmitting aperture; or a transmitting interval of ultrasonic waves transmitted to the subject; or a receiving beamforming parameter, which is a parameter for determining at least one of the following: a receiving aperture indicating a vibrator in the vibrating element array that receives reflected waves from the subject; a receiving focus of the reflected waves; a receiving apodization indicating the weight of the reflected waves received by each of the vibrating elements included in the receiving aperture; a receiving interval of the reflected waves; or a composite weight coefficient in aperture synthesis processing; such that the plurality of image quality items relating to the ultrasonic image become the modified characteristic data; An ultrasound diagnostic device characterized by being equipped with the following features. [Claim 2] A characteristic data determination unit determines characteristic data representing the amount of change for each of several image quality items related to the image quality of an ultrasound image, based on the signal characteristics of the received frame data obtained by transmitting and receiving ultrasound, or the image characteristics of the ultrasound image formed based on the received frame data, presents the characteristic data to the user, and modifies the characteristic data based on instructions from the user. A parameter determination unit determines imaging parameters related to the processing from ultrasound transmission and reception to the formation of an ultrasound image, such that the plurality of image quality items relating to the ultrasound image become the modified characteristic data, 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. An ultrasound diagnostic device characterized by being equipped with the following features. [Claim 3] The imaging parameters include at least one of the following: a transmit beamforming parameter related to the transmit beamforming of ultrasound, a receive beamforming parameter related to the receive beamforming of ultrasound, a signal processing parameter related to signal processing of received frame data, or an image forming processing parameter related to the formation of an ultrasound image. The ultrasound diagnostic apparatus according to feature 2. [Claim 4] The parameter determination unit refers to an imaging parameter database which stores multiple combinations of characteristic data and information indicating the amount of change in the imaging parameter, and determines the imaging parameter based on the information indicating the amount of change in the imaging parameter associated with characteristic data that is the same as or similar to the characteristic data in the imaging parameter database. The ultrasound diagnostic apparatus according to claim 2 or 3. [Claim 5] The parameter determination unit determines the imaging parameters by performing an optimization process that optimizes the image quality item of interest among the plurality of image quality items. The ultrasound diagnostic apparatus according to claim 2 or 3. [Claim 6] The parameter determination unit determines the imaging parameters by the optimization process which imposes constraints on image quality items other than the image quality item of interest among the plurality of image quality items. The ultrasound diagnostic apparatus according to feature 5. [Claim 7] The received frame data is volume data obtained with a two-dimensional ultrasonic probe having a two-dimensional arrangement of vibration elements. The ultrasound diagnostic apparatus according to feature 2.

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