JP2018108141A - Ultrasonic measurement apparatus and control method of ultrasonic measurement apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce an artifact that appears in an ultrasonic image.SOLUTION: An ultrasonic measurement apparatus includes a probe for transmitting/receiving an ultrasonic wave and an arithmetic processing part for subjecting a reception signal of the probe to arithmetic processing. The arithmetic processing part includes a reception wave estimation part for calculating an estimated reception signal by computing propagation of the ultrasonic wave for a given reflectance distribution in an object region, a reflectance distribution data update part for updating the reflectance distribution based on a difference between the reception signal and the estimated reception signal, and an ultrasonic image generation part for generating an ultrasonic image of the object region using the reflectance distribution. The calculation by the reception wave estimation part and the update by the reflectance distribution data update part are repeatedly performed.SELECTED DRAWING: Figure 14

Description

  The present invention relates to an ultrasonic measurement device that performs ultrasonic measurement.

  Conventionally, an ultrasonic probe is used to scan an ultrasonic beam using an ultrasonic probe in which a plurality of ultrasonic elements (ultrasonic transducers) are arranged, and images the state of a living body or a structure to be used for diagnosis or inspection. The device is known.

  One artifact (virtual image) that is a problem in the generation of an ultrasonic image is an artifact caused by side lobes. If a strong reflector exists in the direction of the side lobe, an unnecessary wave reflected by the strong reflector is received, resulting in deterioration of image quality. As a technique for solving this problem, a technique of adding received signals received by each element so as not to be sensitive to unwanted waves from directions other than a desired direction during reception beam forming processing performed in imaging. Is known (see, for example, Patent Document 1).

JP-A-2015-77393

  However, the technique of Patent Document 1 calculates a weight that minimizes sensitivity to a reflected wave from a direction other than a desired direction, and uses it to add received signals. The position and its reflectance are not considered. Therefore, the artifact reduction effect may be insufficient.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique capable of effectively reducing artifacts appearing in an ultrasonic image.

  1st invention for solving the said subject is provided with the probe which transmits / receives an ultrasonic wave, and the arithmetic processing part which arithmetically processes the received signal of the said probe, The said arithmetic processing part is a given of the object area | region. A received wave estimation unit that calculates an estimated received signal by calculating propagation of the ultrasonic wave with respect to the reflectance distribution, and a reflectance distribution that updates the reflectance distribution based on a difference between the received signal and the estimated received signal A data update unit, and an ultrasonic image generation unit that generates an ultrasonic image of the target region using the reflectance distribution, and the calculation by the received wave estimation unit and the update by the reflectance distribution data update unit, Is an ultrasonic measurement device that repeatedly executes.

  According to an eleventh aspect of the invention, there is provided a control method for an ultrasonic measurement apparatus that performs ultrasonic measurement using a probe that transmits and receives ultrasonic waves, and calculates the propagation of the ultrasonic wave for a given reflectance distribution in a target region. Repeating the steps of calculating an estimated received signal, updating the reflectance distribution based on a difference between the received signal of the probe and the estimated received signal, and using the reflectance distribution A control method including generating an ultrasound image of the target region may be configured.

  According to the first or eleventh invention, an estimated received signal is calculated by calculating the propagation of the ultrasonic wave with respect to a given reflectance distribution of the target region, and reflection is performed based on the difference between the received signal and the estimated received signal. The process of updating the rate distribution (hereinafter referred to as “reflectance distribution generation process”) can be repeated. An ultrasonic image of the target region can be generated using the reflectance distribution obtained as a result of repetition. According to this, artifacts appearing in the ultrasonic image can be effectively reduced, and high image quality of the ultrasonic image can be realized.

  As a second invention, the reflectance data updating unit obtains a reflectance residual distribution based on a difference signal that is a difference between the received signal and the estimated received signal, and synthesizes the reflectance residual distribution. Thus, the ultrasonic measurement apparatus according to the first aspect of the present invention may be configured to update the reflectance distribution.

  According to the second invention, each time the reflectance distribution generation process is repeated, the reflectance residual distribution is obtained based on the difference signal between the received signal and the estimated received signal, and the obtained reflectance residual distribution is determined as the reflectance distribution. Can be combined and updated.

  Further, as a third invention, the reflectance data update unit performs reception beam forming processing using the difference signal, and obtains the reflectance residual distribution from a reflectance portion that satisfies a given high reflection condition. You may comprise the ultrasonic measuring apparatus of 2nd invention.

  According to the third aspect of the invention, the reception residual beam forming process using the differential signal is performed, and the reflectance residual distribution can be obtained from the reflectance portion that satisfies the given high reflection condition in the obtained reflectance distribution. .

  Further, as a fourth invention, the repeated execution includes gradually relaxing the high reflection condition by reducing a threshold as the number of repetitions increases, the ultrasonic wave of the third invention A measuring device may be configured.

  According to the fourth aspect, by reducing the threshold value as the number of repetitions of the reflectance distribution generation process increases, the reflectance distribution generation process can be repeated while gradually relaxing the high reflection condition.

  According to a fifth aspect of the invention, the iterative execution includes ending the repetition when the high reflection condition reaches a predetermined limit threshold condition. May be.

  According to the fifth aspect, as a result of reducing the threshold value each time the reflectance distribution generation process is repeated, the repetition of the reflectance distribution generation process is terminated when the high reflection condition reaches a predetermined limit threshold condition. Can do.

  Further, as a sixth invention, the ultrasonic measurement apparatus according to any one of the first to fourth inventions, wherein the repeated execution includes terminating the repetition when the predetermined number of repetitions is performed. It may be configured.

  According to the sixth aspect, when the reflectance distribution generation process is repeated a predetermined number of times, the repetition of the reflectance distribution generation process can be terminated.

  Further, as a seventh invention, the ultrasonic image generation unit generates, as the ultrasonic image, an image obtained by combining the reflectance distribution with a distribution of a reflectance portion that does not satisfy the high reflection condition. You may comprise the ultrasonic measuring apparatus of any 5th invention.

  According to the seventh aspect of the invention, the reflectance distribution obtained by updating the reflectance portion satisfying the high reflectance condition every time the reflectance distribution generation process is repeated is changed to a distribution of the reflectance portion that does not satisfy the high reflectance condition. The synthesized image can be generated as an ultrasonic image.

  According to an eighth aspect of the invention, the reflectance data update unit performs the update by performing Kalman filter processing using the received signal as an observation value and the reflectance distribution as a state variable. The ultrasonic measurement apparatus according to any one of the inventions may be configured.

  According to the eighth aspect of the invention, the reflectance distribution can be updated by performing Kalman filter processing using the received signal as an observed value and the reflectance distribution as a state variable.

  Further, as a ninth invention, any one of the first to eighth aspects wherein the repetitive execution is that the probe repeats a plurality of times for the received signal obtained by transmitting and receiving ultrasonic waves for one frame. You may comprise the ultrasonic measuring apparatus of invention of this invention.

  According to the ninth aspect, the reflectance distribution generation processing is repeated a plurality of times for a received signal obtained by transmitting and receiving one frame of ultrasonic waves, thereby relating to a processing target frame (hereinafter referred to as “processing frame”). An ultrasound image can be generated.

  Further, as a tenth aspect of the invention, the repetitive execution includes updating the reflectance distribution across the frames by using the reflectance distribution related to the previous frame in the subsequent frame. The ultrasonic measurement apparatus according to any one of the first to eighth inventions may be configured.

  According to the tenth aspect of the invention, the reflectance distribution obtained in the previous frame is used in the subsequent frame to repeat the reflectance distribution generation process, and the reflectance distribution updated in the processing frame is used. An ultrasound image can be generated.

The figure which shows the system structural example of an ultrasonic measurement apparatus. The schematic diagram which shows an ultrasonic measurement simply. The figure which shows an example of an object area | region. The figure which shows an example of the ultrasonic image obtained by the conventional method. The figure which shows the general flow of an ultrasonic image generation process. The figure which shows an example of the received wave of each element. The figure which shows an example of the baseband signal which concerns on the received wave of each element. The figure which shows an example of a reception BF process result. The figure which shows an example of a reflectance residual distribution. The schematic diagram explaining the propagation model of an ultrasonic wave. The figure which shows an example of the estimated received wave of each element. The figure which shows an example of the baseband signal which concerns on the estimated received wave of each element. The figure which shows an example of the ultrasonic image obtained by the ultrasonic image generation process of embodiment. The block diagram which shows the function structural example of an ultrasonic measurement apparatus. The flowchart which shows the flow of an ultrasonic image generation process. The figure which shows an example of the ultrasonic image obtained by the ultrasonic image generation process in the modification 1. 9 is a flowchart showing a flow of ultrasonic image generation processing in Modification 1; The schematic diagram which shows the other example of an object area | region. The figure which shows the other example of the ultrasonic image obtained by the conventional method. FIG. 10 is a diagram showing another example of an ultrasound image obtained by the ultrasound image generation process of Modification 1. FIG. 10 is a diagram showing another example of an ultrasound image obtained by the ultrasound image generation process of Modification 1. 9 is a flowchart showing a flow of ultrasonic image generation processing in Modification 2.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments described below, and modes to which the present invention can be applied are not limited to the following embodiments. In the description of the drawings, the same parts are denoted by the same reference numerals.

  FIG. 1 is a diagram illustrating a system configuration example of an ultrasonic measurement apparatus 10 according to the present embodiment. The ultrasonic measurement apparatus 10 is for acquiring biological information of the subject 2 using ultrasonic measurement, for means for displaying reflected wave data and operation information, which will be described later, and for operation input. A touch panel 12 that also serves as the above means, a keyboard 14 for inputting an operation, an ultrasonic probe (probe) 16, and a processing device 30.

  A control board 31 is mounted on the processing apparatus 30 and is connected to various parts of the apparatus such as the touch panel 12, the keyboard 14, and the ultrasonic probe 16 so that signals can be transmitted and received. In addition to various integrated circuits such as a CPU (Central Processing Unit) 32, ASIC (Application Specific Integrated Circuit) and FPGA (Field-Programmable Gate Array), the control board 31 includes a storage medium 33 such as an IC memory or a hard disk, and an external device. A communication IC 34 that implements data communication with the apparatus is mounted. In the processing apparatus 30, the ultrasonic measurement apparatus 10 performs processing necessary for acquiring biological information including ultrasonic measurement by the CPU 32 and the like executing a program stored in the storage medium 33.

  Specifically, the ultrasonic measurement device 10 transmits an ultrasonic beam from the ultrasonic probe 16 to the subject 2 under the control of the processing device 30, receives the reflected wave, and performs ultrasonic measurement. Then, the reception signal of the ultrasonic probe 16 is amplified and signal-processed to generate reflected wave data such as positional information of the in-vivo structure of the subject 2 and changes with time. Ultrasonic measurement is performed at a predetermined cycle. A unit of measurement for one period is called a “frame”. In addition, if the “reception signal” is strictly defined, the reception wave received by each ultrasonic element 161 (see FIG. 2) in the ultrasonic probe 16 during ultrasonic measurement, and the reception wave when generating reflected wave data. The “reception signal” in the present embodiment has a broad meaning which may have any two meanings.

  The reflected wave data includes at least a so-called B mode image, but may include other so-called A mode, M mode, and color Doppler mode images. In the A mode, the first axis is the sampling point sequence of the received signal along the transmission / reception direction of the ultrasonic beam, the second axis is the received signal intensity (reflectance) of the reflected wave at each sampling point, and the amplitude of the reflected wave This is a mode for displaying (A mode image). In the B mode, a two-dimensional ultrasound image of a living body structure visualized by converting a reflected wave amplitude (A mode image) obtained by scanning an ultrasound beam within a predetermined scan range into a luminance value. This is a mode for displaying (B-mode image).

  FIG. 2 is a schematic diagram schematically showing a state in which ultrasonic measurement is performed by placing the ultrasonic probe 16 on the surface of an object. The ultrasonic probe 16 incorporates a plurality (n) of ultrasonic elements (ultrasonic transducers) 161 arranged at equal intervals in a row, and performs ultrasonic measurement by, for example, a linear scan method. That is, the ultrasonic probe 16 moves along the plurality of scanning lines L parallel to each other while shifting the incident position of the ultrasonic beam in the arrangement direction of the ultrasonic elements (hereinafter also simply referred to as “elements”) 161. The rectangular scan range R is scanned by transmitting / receiving. Note that the scan method is not limited to the linear scan method, and can be similarly applied to other scan methods such as a sector scan method.

  Here, the scanning direction of the ultrasonic beam is defined as the x direction, and the direction of the scanning line L orthogonal thereto is defined as the z direction. The z direction corresponds to the depth direction from the living body surface. In the ultrasonic measurement actually performed by the ultrasonic measurement apparatus 10, the ultrasonic probe 16 is applied to the living body surface of the subject 2 (the neck in FIG. 1), and a target region corresponding to the scan range is imaged. The part to which the ultrasonic probe 16 is applied is not limited to the neck, but may be a part of the subject 2 according to the purpose of measurement (diagnosis), such as a wrist, an arm, and an abdomen.

  When generating an ultrasonic image from the reception signal of the ultrasonic probe 16 based on the measurement result of the ultrasonic measurement, the processing device 30 performs reception beam forming (BF) processing and performs each element 161 for each sampling point. The received signals are phased and added. As a result, the received signal of each element 161 becomes two-dimensional data representing the reflectance at each sampling point, and the two-dimensional data is subjected to necessary processing such as detection processing and logarithmic conversion processing to obtain a luminance value for each sampling point. Thus, an ultrasonic image of the target area can be generated. When a plurality of adjacent ultrasonic elements 161 configure one channel to transmit and receive ultrasonic waves, an ultrasonic image can be generated by phasing and adding reception signals obtained for each channel.

[principle]
When transmitting and receiving an ultrasonic beam, an ultrasonic beam with low sensitivity is also emitted in an oblique direction away from the direction of the scanning line L along with the main lobe with high sound pressure radiated along the scanning line L. Yes (side lobe). Therefore, when a reflector exists in the direction of the side lobe, there is a problem that the virtual image (artifact) appears in the ultrasonic image and the image quality is deteriorated. For example, as shown in FIG. 3, when an ultrasonic image is generated by performing ultrasonic measurement of a target area where two reflectors O11 and O13 exist as entities, as shown in FIG. Show artifacts around the reflectors O11 and O13.

  Therefore, in the present embodiment, artifacts appearing in the ultrasound image are reduced by generating an ultrasound image based on the principle described below. FIG. 5 is a diagram showing a rough flow of the ultrasonic image generation processing. In the ultrasonic image generation processing of the present embodiment, the step of calculating the propagation of ultrasonic waves in the target region based on given reflectance distribution data 540 and calculating the estimated received signal, the received signal, the estimated received signal, The process including the step of updating the reflectance distribution data 540 based on the difference between them (reflectance distribution generation process) is repeated. The given reflectance distribution data 540 represents the reflectance distribution in the target area where the reflectance of each sampling point is determined, and the value of each sampling point is initialized to “0” for each frame. The repetition of the reflectance distribution generation process is performed a plurality of times for each frame using the reception signal of the ultrasonic probe 16 for one frame in the processing frame, and the reflectance distribution data 540 obtained by repeating the plurality of times is used. Then, an ultrasonic image in the processing frame is generated.

  First, an ultrasonic measurement for one frame is performed and a reflected wave is received (step S1). Thereafter, the first reflectance distribution generation process is performed, and the initialized reflectance distribution data 540 is updated. That is, first, a baseband signal is extracted from the received wave received by each element 161 in step S1 (step S3). Then, difference detection processing is performed (step S5), and reception BF processing is performed (step S7). The difference detection process in step S5 is a process for obtaining a difference between the baseband signal extracted in step S3 and a baseband signal extracted in step S15 described later, and outputting a difference signal of each baseband signal. By calculating the difference signal of the baseband signal, the signal band is limited to reduce the amount of data, and then the received wave (also referred to as a received signal) and the estimated received wave (also referred to as an estimated received signal) of each element 161. Can be compared. In the first difference detection process, the difference signal is calculated with the baseband signal related to the estimated received wave as the initial value “0”, and the baseband signal related to the received wave obtained in step S3 is directly transferred to the subsequent reception BF process. And pass.

  FIG. 6 is a diagram illustrating an example of the received wave received in step S1. FIG. 6 shows a received waveform example of a received wave received by each element 161 as a result of transmitting and receiving an ultrasonic beam along the central scanning line L passing through the reflector O11 in the target region shown in FIG. FIG. 7 is a diagram showing the magnitude of the baseband signal extracted from the received wave of FIG. 6 and 7, the horizontal axis represents the reception time (corresponding to the depth), the vertical axis represents the element number assigned to each element 161 in the order of arrangement in the ultrasonic probe 16, and individual signal waveforms are represented in the vertical direction. This corresponds to the received wave received by the element 161 having the element number indicated on the axis and the baseband signal extracted therefrom.

  Here, as shown in FIGS. 6 and 7, the reflected wave from the reflector O11 first reaches each element 161 of the ultrasonic probe 16 at the central element 161 closest to the reflector O11. The elements 161 on both sides arrive later than that. The reflected wave reaches the element 161 at both ends farthest from the reflector O11. In the reception BF process performed in step S7 in FIG. 5, the baseband signal from each element 161 is delayed for the distance difference to align the phase, and then the process of adding them is performed for each scanning line L. Thus, the reflectance at each sampling point is obtained.

  FIG. 8 is a diagram illustrating a reception BF processing result. A B-mode image obtained by imaging this is an ultrasonic image (FIG. 4) obtained by a conventional method. As shown in FIG. 8, the reflectance of the target region obtained as a result of the reception BF process is large at the positions of the reflectors O11 and O13. However, the reflectance component which becomes an artifact is distributed around the reflectors O11 and O13.

  By the way, a normal artifact appears to be a reflected wave that is weaker than a reflected wave from an entity (reflector) from a direction different from the direction of the entity. Therefore, the reflectance related to the artifact is the reflectance of the entity. Smaller than. Therefore, by extracting a region having a high reflectance from the reception BF processing result, it is possible to expect an effect of selecting a region having a high possibility of a reflected wave with respect to an entity, by removing the reflectance distribution of the artifact portion.

  Therefore, in the subsequent step S9 in FIG. 5, the reflectance residual distribution calculation process is performed, and the reflectance residual distribution is obtained from the reception BF processing result. Specifically, the distribution of the reflectance portion where the reflectance at each sampling point, which is the reception BF processing result, satisfies a given high reflectance condition is obtained. For example, a sampling point that satisfies the high reflection condition is extracted by setting “the reflectance is equal to or higher than the determination threshold” as a high reflection condition. And the reflectance distribution of each extracted sampling point is obtained as a reflectance residual distribution.

  The threshold value for determination is set so as to decrease, for example, by a predetermined amount as the number of repetitions of the reflectance distribution generation process increases with the initial determination threshold value set in advance as an initial value. In this way, by reducing the determination threshold step by step, the high reflection condition can be gradually relaxed at each repetition. Then, when the determination threshold value is reduced to a lower limit determination threshold value or less, it is assumed that the high reflection condition has reached a predetermined limit threshold condition, and the repetition of the reflectance distribution generation process for the processing frame is finished. The lower limit determination threshold value may be set in advance as a predetermined value, or may be set for each frame using the maximum reflectance value in the first received BF processing result. For example, a range of 40 [dB] from the maximum value may be specified, and the lower limit value may be used as the lower limit determination threshold value.

  FIG. 9 is a diagram showing the reflectance residual distribution obtained from the first reception BF processing result shown in FIG. In the first reflectance residual distribution calculation process, the distribution of the high reflectance portion of the reflectance distribution of the target region obtained by performing the reception BF process on the measurement result is obtained as the reflectance residual distribution. In the example of FIG. 9, the reflectance distribution of the artifact portion is substantially removed, and the reflectance distribution of the two reflectors O11 and O13 that are the substance is obtained as the reflectance residual distribution.

  Subsequently, as shown in FIG. 5, the obtained reflectance residual distribution is synthesized by adding it to the reflectance distribution data 540, and this is updated (step S11). Since the reflectance distribution data 540 is initialized prior to the first reflectance distribution generation process, the reflectance residual distribution obtained in step S9 is used as the reflectance distribution data 540 in the first update.

  Subsequently, based on the updated reflectance distribution data 540, the propagation of the ultrasonic wave in the target region is calculated, and the estimated received wave of each element 161 that is the estimated received signal is calculated (step S13).

FIG. 10 is a schematic diagram illustrating an ultrasonic wave propagation model. In FIG. 10, of the n elements 161, the i-th element 161 is a transmitting element, and the j-th element 161 is a receiving element, which is transmitted from the transmitting element and reflected by the k-th reflector (O2). The propagation path of the ultrasonic wave received by the element is shown. Using the propagation model shown in FIG. 10, the received wave at the receiving element can be calculated by superimposing and superimposing the propagation waveform of the ultrasonic wave propagating on the propagation path to the receiving element for all combinations of the transmitting element and the reflector. it can. Here, the propagation distance pl of the ultrasonic wave from the transmitting element to the receiving element is the distance l (i, k) from the transmitting element to the reflector O2, and the distance l (j, k) from the reflector O2 to the receiving element. And is represented by the following formula (1).

In actual propagation calculation, an ultrasonic wave propagation simulation is performed by dividing the target region into a mesh shape. If the propagation from each transmitting element is i (i = 1 to n) and each mesh part is k (k = 1 to nk), the received wave r _j of the receiving element can be expressed by the following equation (2). . In Expression (2), α represents the reflectance of the mesh portion k, att represents attenuation according to the propagation distance pl, and pulse represents the transmission waveform. The transmission waveform pulse is set in consideration of a delay according to the propagation distance pl and a transmission delay time delay for transmission focus. c represents the speed of sound. In step S13 of FIG. 5, the received wave r _j is calculated according to the expressions (1) and (2) for all the elements 161 and obtained as the estimated received wave of each element 161.

  The propagation model used for the propagation calculation is not limited to the propagation model shown in FIG. 10, and a propagation path between a plurality of reflectors is added in consideration of multiple reflections, or the directivity effect on the reflector surface is propagated in the propagation direction. It is possible to use a propagation model that appropriately incorporates factors that affect the image quality of an ultrasonic image, such as the reflectivity depending on the frequency. Alternatively, if the transmittance of each reflector existing in the target region is known in advance, a propagation model can be constructed in consideration of this.

  Returning to the description of FIG. If propagation calculation is performed and the estimated received wave of each element 161 is calculated, a baseband signal is extracted from the estimated received wave (step S15). Thereafter, the process proceeds to step S5, and a difference detection process related to the second reflectance distribution generation process is performed.

  Here, the estimated received wave obtained as a result of the propagation calculation in step S13 is received by each element 161 in step S1 if the reflectance distribution data 540 matches the reflectance distribution of the actual target region. Matches the received wave. The baseband signal related to the estimated received wave extracted in step S15 also matches the baseband signal related to the received wave extracted in step S3. 11 is a diagram showing the estimated received wave of each element 161 calculated for the same scanning line L as in FIG. 6, and FIG. 12 is a diagram showing the magnitude of the baseband signal extracted from the estimated received wave in FIG. is there. In this example, since the reflectance distribution of the two reflectors O11 and O13 existing in the target region is obtained as the reflectance residual distribution in the reflectance residual distribution calculation process in the previous stage, the reflectance distribution data 540 is This is almost the same as the reflectance distribution of the target area. Therefore, the estimated received wave and the baseband signal extracted therefrom have a waveform that substantially matches the received wave of FIG. 6 and the baseband signal of FIG. Therefore, the difference signal obtained in the second difference detection process is substantially “0”, and the reflectance distribution data 540 converges without being changed in the subsequent step S11.

  If the reflectance distribution data 540 that substantially matches the reflectance distribution of the actual target region is obtained in this way, the reflectance distribution data 540 is imaged, and an ultrasonic image with artifacts removed or reduced is imaged. Generation can be realized. FIG. 13 is a diagram illustrating an ultrasonic image generated by using the reflectance distribution data 540 updated with the reflectance residual distribution of FIG. 9 and converting the reflectance at each sampling point into a luminance value. As shown in FIG. 13, by generating an ultrasonic image using the reflectance distribution data 540, an ultrasonic image with few artifacts can be generated.

  However, in reality, the reflectances of the entities existing in the target area are not always the same as in this example. In addition, the number of entities having a certain degree of reflectivity is unknown. For this reason, it is rare that the reflectance distribution for a target region that exists as an entity with a certain degree of reflectance satisfies the high reflectance condition in all regions by performing the reflectance distribution generation process only once. The second and subsequent reflectance distribution generation processes are repeated in order to reflect the reflectance distribution of the substantial part that does not yet satisfy the high reflection condition in the reflectance distribution data 540. In other words, each time the reflectance distribution generation process is repeated, the threshold value for determination used in the reflectance residual distribution calculation process is gradually reduced, so that the reflectance component related to the substantial part remaining in the difference signal is reflected in the reflectance. A residual distribution is obtained and added to the reflectance distribution data 540 to be synthesized. As a result, it is possible to gradually extract an entity having a certain degree of reflectance while eliminating a virtual image that is not an entity. Can be generated.

[Function configuration]
FIG. 14 is a block diagram illustrating a functional configuration example of the ultrasonic measurement apparatus 10. The ultrasonic measurement device 10 includes a processing device 30 and an ultrasonic probe 16, and the processing device 30 includes an operation input unit 310, a display unit 330, a communication unit 350, an arithmetic processing unit 370, and a storage unit 500. With.

  The ultrasonic probe 16 includes a plurality of ultrasonic elements 161 arranged, and transmits ultrasonic waves based on the pulse voltage from the processing device 30 (more specifically, the ultrasonic measurement control unit 371 of the arithmetic processing unit 370). . And the reflected wave of the transmitted ultrasonic wave is received, and the received wave received by each element 161 is output to the ultrasonic measurement control unit 371.

  The operation input unit 310 receives various operation inputs from the user and outputs an operation input signal corresponding to the operation input to the arithmetic processing unit 370. It can be realized with a button switch, lever switch, dial switch, trackpad, mouse, etc. In FIG. 1, the touch panel 12 and the keyboard 14 correspond to this.

  The display unit 330 is realized by a display device such as an LCD (Liquid Crystal Display), and performs various displays based on display signals from the arithmetic processing unit 370. In FIG. 1, the touch panel 12 corresponds to this.

  The communication unit 350 is a communication device for transmitting / receiving data to / from the outside under the control of the arithmetic processing unit 370. As a communication method of the communication unit 350, a method of wired connection via a cable compliant with a predetermined communication standard, a method of connection via an intermediate device also used as a charger called a cradle, etc., wireless communication is used. Various systems such as a wireless connection type can be applied. In FIG. 1, the communication IC 34 corresponds to this.

  The arithmetic processing unit 370 is realized by, for example, a microprocessor such as a CPU or a GPU (Graphics Processing Unit), or an electronic component such as an ASIC, FPGA, or IC memory. The arithmetic processing unit 370 performs data input / output control with each functional unit, and performs various operations based on a predetermined program and data, an operation input signal from the operation input unit 310, a reception signal of the ultrasonic probe 16, and the like. The biological information of the subject 2 is calculated by executing the above calculation process. In FIG. 1, the CPU 32 corresponds to this. Each unit constituting the arithmetic processing unit 370 may be configured by hardware such as a dedicated module circuit.

  The arithmetic processing unit 370 includes an ultrasonic measurement control unit 371 and a received signal processing unit 400.

  The ultrasonic measurement control unit 371 configures the ultrasonic measurement unit 20 together with the ultrasonic probe 16, and ultrasonic measurement is performed by the ultrasonic measurement unit 20. The ultrasonic measurement control unit 371 can be realized using a known technique. That is, the ultrasonic measurement control unit 371 controls the transmission timing of the ultrasonic pulse by the ultrasonic probe 16, generates a pulse voltage at the transmission timing, and outputs the pulse voltage to the ultrasonic probe 16. At that time, transmission delay processing is performed to adjust the output timing of the pulse voltage to each element 161. In addition, the reception wave received by each element 161 is amplified and filtered, and the received wave (measurement result) of each element 161 after processing is output to the baseband signal acquisition unit 410 of the reception signal processing unit 400.

  The reception signal processing unit 400 includes a baseband signal acquisition unit 410, a difference detection unit 420, a reception BF processing unit 430, a reflectance residual distribution calculation unit 440, a reflectance distribution data update unit 450, and a reception wave estimation. A unit 460 and an ultrasonic image generation unit 470.

  The baseband signal acquisition unit 410 extracts a baseband signal from the received wave of each element 161 input from the ultrasonic measurement control unit 371 and outputs the baseband signal to the difference detection unit 420. In addition, the baseband signal acquisition unit 410 receives the estimated reception wave of each element 161 calculated by the reception wave estimation unit 460 in the previous reflectance distribution generation process in the processing frame. Baseband signal acquisition section 410 extracts a baseband signal from the estimated received wave of each element 161 and outputs the baseband signal to difference detection section 420.

  The difference detection unit 420 performs difference detection processing to calculate a difference signal between the baseband signal related to the reception wave of each element 161 and the baseband signal related to the estimated reception wave, and outputs the difference signal to the reception BF processing unit 430.

  The reception BF processing unit 430 performs reception BF processing, performs phasing addition on the difference signals of the respective elements 161, and outputs the result to the reflectance residual distribution calculation unit 440.

  The reflectance residual distribution calculation unit 440 extracts a sampling point having a reflectance equal to or higher than the determination threshold from the reception BF processing result that the reception BF processing unit 430 performed on the difference signal of each element 161, thereby satisfying the high reflection condition. Find the reflectance residual distribution to satisfy. The obtained reflectance residual distribution is output to the reflectance distribution data update unit 450. The reflectance residual distribution calculation unit 440 includes a high reflection condition setting unit 441 and a limit threshold condition determination unit 443.

  The high reflection condition setting unit 441 sets the determination threshold value by decreasing the initial determination threshold value by a predetermined amount as the number of repetitions of the reflectance distribution generation process increases in each frame. The number of repetitions of the reflectance distribution generation process and the timing for reducing the threshold for determination can be arbitrarily determined. For example, the threshold value for determination may be gradually reduced for each repetition count, or the threshold value for determination may be decreased for every second repetition count. The limit threshold condition determination unit 443 determines that the determination threshold is equal to or lower than the lower limit determination threshold in each frame as the limit threshold condition.

  The reflectance distribution data update unit 450 combines the reflectance residual distribution with the reflectance distribution data 540 and updates the reflectance distribution data 540.

  The reception wave estimation unit 460 performs ultrasonic wave propagation calculation in the target region based on the reflectance distribution data 540 updated by the reflectance distribution data update unit 450, calculates an estimated reception wave of each element 161, and generates a baseband signal. The data is output to the acquisition unit 410.

  The ultrasonic image generation unit 470 generates an ultrasonic image using the reflectance distribution data 540.

  The storage unit 500 is realized by a storage medium such as an IC memory, a hard disk, or an optical disk. The storage unit 500 stores in advance a program for operating the ultrasonic measurement apparatus 10 to realize various functions provided in the ultrasonic measurement apparatus 10, data used during execution of the program, and the like. Alternatively, it is temporarily stored for each processing. In FIG. 1, the storage medium 33 mounted on the control board 31 corresponds to this. Note that the connection between the arithmetic processing unit 370 and the storage unit 500 is not limited to a connection by an internal bus circuit in the apparatus, but may be realized by a communication line such as a LAN (Local Area Network) or the Internet. In that case, the storage unit 500 may be realized by an external storage device different from the ultrasonic measurement device 10.

  The storage unit 500 stores an ultrasonic measurement program 510, received wave data 520, estimated received wave data 530, reflectance distribution data 540, and ultrasonic image data (reflected wave data) 550. .

  The arithmetic processing unit 370 implements the functions of the ultrasonic measurement control unit 371, the reception signal processing unit 400, and the like by reading and executing the ultrasonic measurement program 510. When these functional units are realized by hardware such as an electronic circuit, a part of a program for realizing the functions can be omitted.

  The received wave data 520 stores the received wave received by each element 161 as a result of ultrasonic measurement for each frame. It can also be referred to as received signal data. The estimated received wave data 530 stores the estimated received wave of each element 161 obtained by ultrasonic propagation calculation performed in the process of the reflectance distribution generation for each frame. It can also be referred to as estimated received signal data.

  The reflectance distribution data 540 stores the reflectance distribution in the target region that is initialized and updated for each frame.

  The ultrasonic image data 550 stores B-mode image data of each frame, which is an ultrasonic image generated for each frame based on the measurement result of the ultrasonic measurement.

[Process flow]
FIG. 15 is a flowchart showing the flow of ultrasonic image generation processing in the present embodiment. The processing described here is started when, for example, the user places the ultrasonic probe 16 on the living body surface of the subject 2 and inputs a predetermined measurement start operation. This processing can be realized by causing the arithmetic processing unit 370 to read out and execute the ultrasonic measurement program 510 from the storage unit 500 and operate each unit of the ultrasonic measurement apparatus 10.

  As shown in FIG. 15, in the ultrasonic image generation process of the present embodiment, the process of loop A is repeated for each frame (steps S101 to S139). In loop A, first, the reflectance distribution data 540 is initialized (step S103). In addition, the initial value “0” used as the estimated received wave of each element 161 in the first reflectance distribution generation process is stored and set in the estimated received wave data 530 (step S105), and the determination threshold is the initial value. The threshold is set as the initial determination threshold (step S107).

  After the above initial setting, the ultrasonic measurement unit 20 starts ultrasonic measurement for one frame (step S109). By the processing here, the measurement result of the processing frame (the reception wave of each element 161) is stored in the reception wave data 520.

  Thereafter, the processes of steps S111 to S135, which are the reflectance distribution generation process, are repeated a plurality of times. That is, first, the process of loop B is executed for each scanning line L (steps S111 to S125). Then, in the loop B, first, the baseband signal acquisition unit 410 reads the reception wave of each element 161 related to the scanning line (processing scanning line) L to be processed from the reception wave data 520 and obtains the baseband signal from the reception wave. Take out (step S113). In addition, the estimated received wave of each element 161 calculated in the subsequent step S135 in the previous reflectance distribution generation process for the processing frame is read from the estimated received wave data 530, and the baseband signal is extracted from the estimated received wave (step). S115). When this processing is performed for the processing frame for the first time, the initial value “0” stored in the estimated received wave data 530 is read in step S105, and the extracted baseband signal also has the initial value “0”.

  Subsequently, the processing scanning line L is sampled for a certain time, and the processing of the loop C is executed with each sampling point as a processing target point in sequence (steps S117 to S123). In the loop C, first, the difference detection unit 420 performs difference detection processing, and relates to the baseband signal related to the received wave of each element 161 extracted in step S113 and the estimated received wave of each element 161 extracted in step S115. A difference signal from the baseband signal is calculated for each element 161 (step S119). Thereafter, the reception BF processing unit 430 performs reception BF processing, and performs phasing addition of the differential signals of the respective elements 161 calculated in step S119 (step S121).

  When the processing of the loop C is repeated and the sampling of the processing scanning line L is finished, the processing of the loop B for the processing scanning line L is finished. Then, when the process of loop B is performed for all the scanning lines as processing targets, the process proceeds to step S127.

  In step S127, the reflectance residual distribution calculating unit 440 performs the reflectance residual distribution calculating process, and obtains the reflectance residual distribution satisfying the high reflectance condition from the reception BF processing result in step S121. Thereafter, the reflectance distribution data updating unit 450 combines the reflectance residual distribution with the reflectance distribution data 540 and updates it (step S129).

  Subsequently, the high reflection condition setting unit 441 determines whether the current determination threshold is equal to or lower than the lower limit determination threshold. If it is larger than the lower limit determination threshold value (step S131: NO), the determination threshold value is reset by subtracting a predetermined value from the current determination threshold value (step S133). Then, the reception wave estimation unit 460 performs ultrasonic wave propagation calculation in the target region using the reflectance distribution data 540, and calculates an estimated reception wave of each element 161 for each scanning line L (step S135). By the processing here, the estimated received wave of each element 161 is stored in the estimated received wave data 530. Thereafter, the process returns to step S111, and the next repetition of the reflectance distribution generation process is performed.

  On the other hand, if the current determination threshold value is less than or equal to the lower limit determination threshold value (step S131: YES), the ultrasonic image generation unit 470 uses the reflectance of each sampling point set in the reflectance distribution data 540 as the luminance value. To generate an ultrasonic image (step S137). The generated ultrasonic image is appropriately displayed on the display unit 330. This completes the ultrasonic image generation process for the processing frame.

  As described above, according to the present embodiment, the reflectance distribution satisfying the high reflectance condition is obtained based on the reflectance distribution of the target region obtained from the received wave of each element 161, and given reflectance distribution data. 540 can be generated. Further, the propagation of ultrasonic waves in the target region can be calculated based on the reflectance distribution data 540, and the estimated received wave of each element 161 can be calculated. Then, the difference signal between the baseband signal related to the received wave of each element 161 and the baseband signal related to the estimated received wave is subjected to reception BF processing to obtain a reflectance residual distribution, and this is combined to update the reflectance. The process of calculating the estimated received wave of each element 161 from the distribution data 540 can be repeated. According to this, the reflectance distribution data 540 can be converged close to the reflectance distribution of the actual target region. Also, an ultrasonic image can be generated using the reflectance distribution data 540 thus obtained. Therefore, artifacts appearing in the ultrasonic image can be effectively reduced, and high image quality of the ultrasonic image can be realized.

  In the above embodiment, the repetition of the reflectance distribution generation process is terminated when the high reflection condition reaches the limit threshold condition. However, the baseband signal and the estimated reception wave related to the reception wave of each element 161 are terminated. It may be configured to end when the difference signal from the baseband signal approaches “0” and the difference signal becomes sufficiently small to a predetermined value or less. According to this, since an ultrasonic image can be generated using the reflectance distribution data 540 that substantially matches the reflectance distribution of the actual target region, artifacts can be reliably reduced.

[Modification 1]
In addition, the number of repetitions of the reflectance distribution generation process may be a predetermined number (for example, 20 times) set in advance. In the above embodiment, the ultrasound image is generated using the reflectance distribution data 540 obtained by repeating the reflectance distribution generation process a plurality of times. On the other hand, after repeating a plurality of times, the distribution of the reflectance portion that does not satisfy the high reflection condition in the final reflectance distribution generation processing for the processing frame is added to the reflectance distribution data 540 and synthesized. It is good. Then, an ultrasonic image may be generated using the combined reflectance distribution data 540. For example, FIG. 16 shows an ultrasonic image generated by combining the reflectance distribution data 540 shown in FIG. 13 with the low reflectance distribution obtained when the reflectance residual distribution related to the reflectance distribution data 540 is obtained. Show.

  If the number of repetitions of the reflectance distribution generation process is small, the repetition of the reflectance distribution of the low-reflectance entity part existing in the target region does not satisfy the high reflection condition, and the reflectance distribution is the reflectance. The distribution data 540 may not be reflected. On the other hand, since the propagation calculation of the ultrasonic wave is performed at each repetition, the processing time increases correspondingly if the number of repetitions is increased.

  Here, the reflectance distribution of the entity that does not satisfy the high reflection condition even if the reflectance distribution generation process is repeated a predetermined number of times is a sampling point that is not extracted from the reception BF process result in the last reflectance residual distribution calculation process Are included in the reflectance distribution (hereinafter referred to as “low reflectance distribution”). Accordingly, after the repetition of the reflectance distribution generation process, the entity can be depicted in the ultrasonic image by combining the remaining low reflectance distribution with the reflectance distribution data 540. However, in this case, the low reflectance distribution may include the reflectance distribution of the artifact portion. However, a part of the reflectance distribution of the original artifact part has disappeared from the reflectance residual distribution as a result of the reflectance distribution generation process repeated so far. Therefore, also in the first modification, an ultrasonic image with fewer artifacts than the conventional method can be generated. Therefore, according to the first modification, the artifact appearing in the ultrasonic image can be reduced while the processing time is shortened by adjusting the number of repetitions of the reflectance distribution generation process.

  FIG. 17 is a flowchart showing a flow of ultrasonic image generation processing in the first modification. In FIG. 17, the same processing steps as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 17, in Modification 1, the process of loop D is repeated for each frame (steps S201 to S247). Then, after the reflectance residual distribution is synthesized and updated in the reflectance distribution data 540 in step S129, it is determined whether or not the reflectance distribution generation processing has been repeated a predetermined number of times (step S241). If it has not been repeated a predetermined number of times (step S241: NO), the process proceeds to step S133. On the other hand, when the process is repeated a predetermined number of times (step S241: YES), the low reflectance distribution that does not satisfy the high reflectance condition in step S127 performed immediately before the processing frame is combined with the reflectance distribution data 540 and updated. (Step S243). Thereafter, an ultrasonic image is generated using the reflectance distribution data 540 updated in step S243 (step S245).

  Here, in order to make a comparative study, it is assumed that there is a target region where four reflectors O31 to O34 arranged two by two vertically as shown in FIG. A sonic image was generated. Of the four reflectors O31 to O34, the lower left reflector O32 is a weak reflector, and the other three reflectors O31, O33, and O34 are strong reflectors. FIG. 19 is a diagram showing an ultrasound image of the target region obtained by the conventional method, and FIGS. 20 and 21 show ultrasound images of the target region obtained by the ultrasound image generation processing of the first modification. FIG. FIG. 20 shows ultrasonic images when the reflectance distribution generation processing is repeated 15 times, and FIG. 21 shows 25 times. As shown in FIG. 19, in the ultrasonic image obtained by the conventional method, the weak reflector O32 below it cannot be observed because it is hidden by artifacts appearing around the strong reflector O31. On the other hand, when the number of repetitions of the reflectance distribution generation process is increased, the artifact is gradually reduced as shown in FIGS. 20 and 21, and the weak reflector O32 can be visually recognized in the ultrasonic image of FIG. .

  Instead of synthesizing the low reflectance distribution with the reflectance distribution data 540, an image generated from the low reflectance distribution may be combined with an image generated from the reflectance distribution data 540 to generate an ultrasonic image. .

  In that case, a predetermined filter is applied to either the image generated from the reflectance distribution data 540 or the image generated from the low reflectance distribution, or different filters are applied to both images prior to synthesis. May be. Further, the filter to be applied may be determined according to a user operation input.

  For example, when displaying an ultrasonic image, it is desirable to display the boundary of the living tissue and the outline of the organ. On the other hand, a display in which speckle noise is suppressed is required for an area inside a living tissue or an area inside an organ. Here, the reflectance distribution data 540 includes a large number of reflectance distributions of the substantial part in the target region, specifically, the reflectance distributions of the tissue boundary and the contour part of the organ. That is, the reflectance distribution data 540 represents the in vivo structure in the target region. On the other hand, the low reflectance distribution includes many reflectance distributions inside a tissue or an organ. Therefore, the speckle reduction filter or the like is applied to the image generated from the low reflectance distribution to perform smoothing processing, while the image generated from the reflectance distribution data 540 is subjected to filter processing for enhancing the edge. It may be done. According to this, it is possible to generate an easy-to-see ultrasonic image in which the generation of speckle noise is suppressed while enhancing the contour of the in vivo structure.

[Modification 2]
In the embodiment and the first modification, the reflectance distribution generation process is repeated a plurality of times for each frame. On the other hand, the reflectance distribution generation process performed in each frame is performed once, and the reflectance distribution data 540 obtained in the previous frame is used in the subsequent frame, so that the reflectance distribution data 540 is straddled between frames. It is good also as updating with continuous cotton.

  For example, in a usage mode in which an ultrasonic image of the target area is observed without moving the position where the ultrasonic probe 16 is applied, the image of the target area does not change significantly. In such a case, by updating the reflectance distribution data 540 obtained in the previous frame, the reflectance distribution data 540 can be converged close to the reflectance distribution of the actual target region. The same effect as the form can be achieved.

  In this case, the dispersion value of the reflectance distribution data 540 updated for each frame is used as the reliability, and predetermined filter processing and weighting are performed to smooth the image change between frames and reduce noise. can do.

As an example, Kalman filter processing may be performed in which the received wave of each element 161 is the observation value y and the reflectance distribution of the reflectance distribution data 540 is a state variable. The Kalman filter is defined by a state equation of the following equation (3) and an observation equation of the following equation (4). In equations (3) and (4), F represents a linear model of time transition, G represents a noise model, H represents an observation model, w represents observation noise, and v represents a process error. The Kalman filter may be applied to the entire area of the reflectance distribution data 540 or may be applied to the representative value.
x (k + 1) = Fx (k) + Gw (3)
y (k) = Hx (k) + v (4)

  When the Kalman filter process is performed, when the change in the reflectance distribution data 540 between frames is small, the updated reflectance distribution data 540 is corrected by relying on the reflectance distribution data 540 before the update. Therefore, the reflectance distribution data 540 can be stabilized, and the flickering of the ultrasonic image between frames can be suppressed. The Kalman filter process can be regarded as a process subsequent to the process of updating the reflectance distribution data 540, and thus can be regarded as a part of the update process of the reflectance distribution data 540. Note that the time transition linear model F of Equation (3) is not necessary when the ultrasonic probe 16 is stationary, but the amount of movement of the ultrasonic probe 16 is detected to obtain the time transition linear model F. By reflecting, the followability when the ultrasonic probe 16 is moved is improved.

  The amount of movement of the ultrasonic probe 16 is, for example, the reflectance distribution data 540 before update (reflectance distribution data 540 updated in the previous frame) and the reflectance distribution data 540 after update (reflectance updated in the processing frame). It can be detected by comparing with the distribution data 540). That is, the reflectance distribution data 540 mainly includes the reflectance distribution of the boundary of the living tissue and the outline of the organ as described above, and represents the in-vivo structure in the target region. By comparing 540, the amount of movement of the ultrasonic probe 16 between the corresponding frames can be detected.

  FIG. 22 is a flowchart showing a flow of ultrasonic image generation processing in the second modification. In FIG. 22, the same processing steps as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 22, in the second modification, the process of loop E is repeated for each frame (steps S301 to S351). Then, after updating the reflectance distribution data 540 in step S129, Kalman filter processing is performed (step S330). Moreover, in the modification 2, after performing propagation calculation in step S135, it transfers to step S349. In step S349, an ultrasonic image is generated using the reflectance distribution data 540 that is updated in step S129 in the processing frame and corrected by the Kalman filter processing in step S330. Prior to step S349, a low reflectance distribution that does not satisfy the high reflection condition in step S127 performed on the processing frame may be combined with the reflectance distribution data 540 as in Modification 1. Alternatively, an ultrasonic image may be generated by combining an image generated from the corrected reflectance distribution data 540 and an image generated from the low reflectance distribution.

[Other variations]
In the above-described embodiment and the like, the determination threshold is reset by subtracting a predetermined value from the current determination threshold in step S133 in FIG. Then, in the reception BF processing result related to the current iteration, the reflectance residual distribution is obtained under the condition that the reflectance is equal to or higher than the current determination threshold. On the other hand, using the maximum value of the reflectance in the reception BF processing result according to the current iteration, the reflectance residual is assumed to be that the reflectance is within 10% of the maximum value, for example, as a high reflection condition. The distribution may be obtained. Alternatively, the beam diameter of the ultrasonic beam transmitted and received by the ultrasonic probe 16 is used, and “within the range of the beam diameter, the diameter is centered on the sampling point where the reflectance is maximum in the reception BF processing result according to the current repetition. It is also possible to obtain a reflectance residual distribution by extracting sampling points within the range under the condition that “there is” a high reflection condition.

  Further, these high reflection conditions may be variably set according to a user operation input. That is, the user may be able to specify a numerical value of the predetermined value or the ratio (for example, “10%” described above). Alternatively, the beam diameter of the ultrasonic beam may be set in accordance with a user operation input, and the reflectance residual distribution may be obtained according to the beam diameter designated by the user.

  Further, for each element 161, the received waveform and the estimated received waveform may be compared to perform processing for evaluating coherency. When the reflected wave on which the scattered signal is superimposed is received, the image quality is deteriorated due to speckle noise. Here, when the scattered signal is superimposed on the reflected wave, the difference between the received wave and the estimated received wave varies greatly at each reception time, so that the coherency decreases. Therefore, a region with low coherency can be identified from the magnitude of variation, and a tissue boundary and a scattering region in the target region can be discriminated. Therefore, the scattering region with low coherency may be a speckle region, and the reflectance distribution of the region may not be updated by masking the speckle region when updating the reflectance distribution data 540. Alternatively, the speckle region may be smoothed with respect to the reflectance residual distribution and then combined with the reflectance distribution data 540.

  In the above-described embodiment and the like, the entire scan range of the ultrasonic probe 16 is set as a target region, and an ultrasonic image of the target region is generated. On the other hand, it is good also as a structure which produces | generates an ultrasonic image by making the one part area | region of a scanning range into an object area | region. In this case, for example, an area selection operation for selecting an arbitrary area within the scan range is accepted. When the user inputs the region selection operation, the ultrasound image is generated using the selected region as a target region. The area to be selected may be a rectangular area or a fan-shaped area, and the shape is not particularly limited. According to this, since the region narrower than the scan range can be set as the target region, the amount of propagation calculation can be reduced, and the processing time required for one reflectance distribution generation process can be increased.

  Also, instead of storing and saving all the ultrasonic images generated for each frame in the ultrasonic image data 550, only the ultrasonic image (still image) of the frame when the user inputs a save instruction operation. May be saved.

  In that case, the ultrasonic image generation processing of the above-described embodiment or the like may be performed only for the frame at the time of storage in which the storage instruction operation is input, and an ultrasonic image may be generated by a conventional method in a frame other than the time of storage. Alternatively, the number of repetitions of the reflectance distribution generation process in a frame at the time of storage is increased, and the number of repetitions of the reflectance distribution generation process in a frame other than at the time of storage is decreased to reduce the number of repetitions of the reflectance distribution generation process. May be performed. Further, in the frames other than the storage time, the reflectance distribution data 540 may be thinned out and used for propagation calculation.

  In addition, the ultrasonic measurement apparatus of the present invention is not limited to the case where an ultrasonic image of a target region in a living body is generated using ultrasonic measurement as in the above-described embodiment, and for example, a structure other than a living body. The present invention can also be applied to the case where an ultrasonic image is generated using the region inside the target region as a target region and used for the inspection or the like.

  DESCRIPTION OF SYMBOLS 10 ... Ultrasonic measurement apparatus, 16 ... Ultrasonic probe, 161 ... Ultrasonic element, 20 ... Ultrasonic measurement part, 30 ... Processing apparatus, 310 ... Operation input part, 330 ... Display part, 350 ... Communication part, 370 ... Calculation Processing unit 371 Ultrasonic measurement control unit 400 Reception signal processing unit 410 Baseband signal acquisition unit 420 Difference detection unit 430 Reception BF processing unit 440 Reflectance residual distribution calculation unit 441 ... High reflection condition setting unit, 443 ... Limit threshold condition determination unit, 450 ... Reflectance distribution data update unit, 460 ... Received wave estimation unit, 470 ... Ultrasonic image generation unit, 500 ... Storage unit, 510 ... Ultrasonic measurement program 520 ... received wave data, 530 ... estimated received wave data, 540 ... reflectance distribution data, 550 ... ultrasound image data, 2 ... subject

Claims (11)

A probe for transmitting and receiving ultrasound,
An arithmetic processing unit for arithmetically processing the received signal of the probe;
With
The arithmetic processing unit includes:
A received wave estimator that calculates an estimated received signal by calculating the propagation of the ultrasonic wave for a given reflectance distribution of the target region;
A reflectance distribution data update unit that updates the reflectance distribution based on a difference between the received signal and the estimated received signal;
An ultrasonic image generation unit that generates an ultrasonic image of the target region using the reflectance distribution;
With
An ultrasonic measurement apparatus that repeatedly executes calculation by the received wave estimation unit and update by the reflectance distribution data update unit. The reflectance distribution data update unit obtains a reflectance residual distribution based on a difference signal that is a difference between the received signal and the estimated received signal, and synthesizes the reflectance distribution by combining the reflectance residual distribution. Update,
The ultrasonic measurement apparatus according to claim 1. The reflectance distribution data update unit performs reception beam forming processing using the difference signal and obtains the reflectance residual distribution from a reflectance part that satisfies a given high reflectance condition.
The ultrasonic measurement apparatus according to claim 2. The repeated execution includes gradually relaxing the high reflection condition by reducing a threshold as the number of repetitions increases.
The ultrasonic measurement apparatus according to claim 3. Performing the iteration includes terminating the iteration when the high reflection condition reaches a predetermined threshold threshold condition;
The ultrasonic measurement apparatus according to claim 4. The repeated execution includes terminating the repetition when the repetition is performed a predetermined number of times.
The ultrasonic measurement apparatus according to any one of claims 1 to 4. The ultrasonic image generation unit generates, as the ultrasonic image, an image obtained by combining the reflectance distribution with a distribution of a reflectance portion that does not satisfy the high reflection condition.
The ultrasonic measurement apparatus according to any one of claims 3 to 5. The reflectance distribution data update unit performs the update by performing a Kalman filter process using the received signal as an observation value and the reflectance distribution as a state variable.
The ultrasonic measurement apparatus according to claim 1. The repetitive execution is to repeat the reception signal obtained by transmitting / receiving ultrasonic waves for one frame a plurality of times.
The ultrasonic measurement apparatus according to claim 1. The repeated execution includes updating the reflectance distribution continuously between frames by using the reflectance distribution related to the previous frame in the subsequent frame.
The ultrasonic measurement apparatus according to claim 1. A method for controlling an ultrasonic measurement apparatus that performs ultrasonic measurement using a probe that transmits and receives ultrasonic waves,
Calculating an estimated received signal by calculating propagation of the ultrasonic wave for a given reflectance distribution in a target area; and determining the reflectance distribution based on a difference between the received signal of the probe and the estimated received signal. Repeating the updating step;
Generating an ultrasound image of the target region using the reflectance distribution;
Control method.