Ultrasonic diagnostic apparatus and image processing method

Abstract

The present application provides an ultrasonic diagnostic apparatus and an image processing method. A first combining section (15A) combines a plurality of sub-images on the basis of applying a first weight distribution, thereby generating a first combined image. A second combining section (15B) combines the plurality of sub-images on the basis of applying a second weight distribution, thereby generating a second combined image. A generating section (32) generates a display image on the basis of the first combined image and the second combined image.

Description

Technical Field

[0001] This disclosure relates to an ultrasonic diagnostic apparatus and an image processing method, and particularly to an ultrasonic diagnostic apparatus and an image processing method for processing images according to the synthetic transmit aperture method. Background Technology

[0002] Ultrasonic diagnostic apparatus employing the transmit aperture synthesis method is described in Document 1 (JP Patent Application Publication No. 2016-77442) and Document 2 (JP Re-Table 2016-129376). In the transmit aperture synthesis method (more precisely, the transmit aperture synthesis method utilizing a virtual source), the transmit focus formed within the biological body is considered as a virtual source. Specifically, in the receiving unit, when generating or calculating delay data for phase-alignment and summing operations (delay and summing operations), the propagation time of the spherical wave from the virtual source to each receiving point is considered. Multiple sub-images (multiple low-resolution images) generated through multiple transmissions are synthesized to generate a composite image (high-resolution image).

[0003] Before combining multiple sub-images, a weight distribution (typically multiplicative) is applied to each sub-image. The weight distribution consists of multiple weights distributed in two dimensions. By applying the weight distribution, the gain in the combined image is spatially homogenized, and invalid components in each sub-image are eliminated. References 1 and 2 do not describe the parallel application of multiple weight distributions to the same sub-image.

[0004] Furthermore, in Reference 3 (JP Patent Application Publication No. 2015-213673) and Reference 4 (Chi HyungSeo, et al., Sidelobe Suppression in Ultrasound Imaging Using Dual Apodization with Cross-Correlation, IEEE UFFC, Vol. 55, No. 10, 2008.), the parallel application of multiple weighting functions to the beam data train is disclosed. However, References 3 and 4 do not disclose the structure used for transmit aperture synthesis. Summary of the Invention

[0005] The purpose of this disclosure is to improve the quality of the display image when generating it according to the transmit aperture synthesis method. Alternatively, the purpose of this disclosure is to reduce unwanted components such as sidelobe components and artifact components when generating the display image according to the transmit aperture synthesis method.

[0006] The ultrasonic diagnostic apparatus disclosed herein is characterized by comprising: a receiving unit that generates a plurality of sub-images for transmitting aperture synthesis; a first synthesis unit that synthesizes the plurality of sub-images based on a first weight distribution to generate a first synthesized image; a second synthesis unit that synthesizes the plurality of sub-images based on a second weight distribution different from the first weight distribution to generate a second synthesized image; and a generating unit that generates a display image based on the first synthesized image and the second synthesized image.

[0007] The image processing method disclosed herein is characterized by comprising the following steps: generating a plurality of sub-images for transmitting aperture synthesis; synthesizing the plurality of sub-images based on a first weight distribution to generate a first synthesized image; synthesizing the plurality of sub-images based on a second weight distribution different from the first weight distribution to generate a second synthesized image, or synthesizing the plurality of sub-images to generate a second synthesized image; calculating a similarity set based on the first synthesized image and the second synthesized image; and generating a display image by adjusting the gain of the first synthesized image based on the similarity set. Attached Figure Description

[0008] Figure 1 This is a block diagram illustrating the ultrasonic diagnostic apparatus according to the first embodiment.

[0009] Figure 2 It means Figure 1 The diagram shows a block diagram of the module's structure.

[0010] Figure 3 This is a schematic diagram illustrating the generation of sub-images under the transmit aperture synthesis method.

[0011] Figure 4 This is a schematic diagram illustrating the generation of a synthesized image using the aperture synthesis method.

[0012] Figure 5 This is a schematic diagram illustrating the sub-image processing involved in the first embodiment.

[0013] Figure 6 This is a block diagram illustrating the ultrasonic diagnostic apparatus according to the second embodiment.

[0014] Figure 7 This is a diagram illustrating the sub-image processing involved in the second embodiment.

[0015] Figure 8 This is a block diagram representing the ultrasound diagnostic device involved in the first variation.

[0016] Figure 9 This is a block diagram representing the ultrasound diagnostic device involved in the second variation. Detailed Implementation

[0017] The following description of the implementation method is based on the accompanying drawings.

[0018] (1) Overview of the implementation method

[0019] The ultrasound diagnostic apparatus according to the embodiment includes a receiving unit, a first synthesis unit, a second synthesis unit, and a generating unit. The receiving unit generates multiple sub-images for aperture synthesis. The first synthesis unit synthesizes the multiple sub-images using a first weight distribution, thereby generating a first synthesized image. The second synthesis unit synthesizes the multiple sub-images using a second weight distribution different from the first weight distribution, thereby generating a second synthesized image. The generating unit generates a display image based on the first and second synthesized images. The receiving unit corresponds to a receiver. The first synthesis unit corresponds to a first synthesizer. The second synthesis unit corresponds to a second synthesizer. The generating unit corresponds to a generator. Each weight distribution is a two-dimensional weight distribution.

[0020] Based on the above structure, a display image can be generated based on a first composite image and a second composite image that have different properties. Therefore, compared to using a single composite image unchanged as the display image, the quality of the display image can be improved. For example, as a combination of the first and second weight distributions (weight distribution pairs), a combination that reduces sidelobes or a combination that reduces artifacts can be used. Multiple weight distribution pairs can also be prepared, and a specific weight distribution pair can be selected according to the situation. In this implementation, since multiple weight distributions are applied side-by-side to the same sub-image, there is essentially no reduction in spatial resolution or frame rate.

[0021] The image processing described above is based on the transmit aperture synthesis method, particularly based on the transmit aperture synthesis method utilizing a virtual sound source. The ultrasonic diagnostic apparatus according to the embodiment includes a coordinate transformation unit that transforms an image following a transmit / receive coordinate system to an image following a display coordinate system. The sub-image, the synthesized image, and the display image are respectively the data before or after the coordinate transformation. In this specification, the term "image" is interpreted broadly. Furthermore, the contents of the first weight distribution and the second weight distribution can be dynamically changed corresponding to the position of the transmit / receive aperture in the electronic scanning direction.

[0022] In one embodiment, the generation unit includes: a calculator that calculates a similarity set based on the first composite image and the second composite image; and a gain adjuster that adjusts the gain of one or both of the first composite image and the second composite image based on the similarity set, thereby generating an image for display.

[0023] Similarity is an indicator of the probability of a true component being generated. A correlation coefficient can be used as a similarity metric. When generating an image for display, the original image that becomes its source is one or both of the first and second composite images. A gain adjuster increases the gain of the original image when the similarity is high and decreases the gain when the similarity is low. This preserves the true component and reduces sidelobe components.

[0024] In this embodiment, the gain adjuster generates a display image by applying a similarity set (similarity distribution) to the first synthesized image. In this case, the first synthesized image is used as the main image, and the second synthesized image is used as an auxiliary image or a comparison image. In this embodiment, the second weight distribution is a distribution that results in an increase in sidelobe components after weighting compared to the first weight distribution. Furthermore, when the second synthesized image is used as an auxiliary image, the second weight distribution can be a distribution with all weights equal to 1, or the application of the second weight distribution can be omitted when generating the second synthesized image.

[0025] The ultrasound diagnostic apparatus according to the embodiment further includes: a detector that performs envelope detection on a display image output from a gain adjuster; and a logarithmic transformer that performs logarithmic transformation on the display image output from the detector. Envelope data is generated from RF (radio frequency) data through envelope detection. The logarithmic transformation corresponds to brightness adjustment based on human visual characteristics.

[0026] In this embodiment, the generation unit includes: a first post-processing unit that applies envelope detection and logarithmic transformation to a first composite image; a second post-processing unit that applies envelope detection and logarithmic transformation to a second composite image; and an adder that adds the first composite image output from the first post-processing unit and the second composite image output from the second post-processing unit to generate a display image. This structure adds the post-processed first composite image and the second composite image to generate a display image. The first post-processing unit corresponds to a first post-processor. The second post-processing unit corresponds to a second post-processor.

[0027] In this implementation, the first weight distribution has a shape offset to one side of the beam scanning direction at each depth position (one-dimensional distribution). The second weight distribution has a shape offset to the other side of the beam scanning direction at each depth position (one-dimensional distribution). By using such a weight distribution pair, artifacts contained in the displayed image can be reduced.

[0028] The image processing method disclosed herein includes a sub-image generation step, a first synthesis step, a second synthesis step, a calculation step, and a gain adjustment step. In the sub-image generation step, multiple sub-images for aperture synthesis are generated. In the first synthesis step, the multiple sub-images are synthesized based on a first weight distribution to generate a first synthesized image. In the second synthesis step, the multiple sub-images are synthesized based on a second weight distribution different from the first weight distribution to generate a second synthesized image. Alternatively, in the second synthesis step, the multiple sub-images are synthesized to generate a second synthesized image. In the calculation step, a similarity set is calculated based on the first synthesized image and the second synthesized image. In the gain adjustment step, the gain of the first synthesized image is adjusted based on the similarity set to generate a display image.

[0029] In the above structure, multiple sub-images are generated by repeatedly sending ultrasound waves into the organism and receiving reflected waves from the organism. A first composite image and a second composite image are generated based on these multiple sub-images. The first composite image is the main image, and the second composite image is an auxiliary image or a comparison image. Therefore, the application of the second weight distribution can be omitted when generating the second composite image. Even without omitting the application of the second weight distribution, first and second composite images with different properties can be obtained. A similarity set is generated by comparing these composite images, and a display image is generated by applying this similarity set to the first composite image.

[0030] The image processing method described above can be implemented as a hardware function or a software function. The program for executing the image processing method can be installed on an information processing device via a removable storage medium or via a network. The concept of an information processing device includes ultrasound diagnostic devices, ultrasound image processing devices, computers, etc. In the information processing device, the program can be stored in a non-temporary storage medium.

[0031] (2) Details of the implementation method

[0032] exist Figure 1The structure of the ultrasound diagnostic apparatus according to the first embodiment is shown. The ultrasound diagnostic apparatus, installed in medical institutions, etc., is a medical device that generates and displays ultrasound images based on data obtained by transmitting and receiving ultrasound waves to a subject (biological organism). The ultrasound diagnostic apparatus according to the embodiment includes a structure for performing a transmission aperture synthesis method utilizing a virtual sound source.

[0033] exist Figure 1 In this design, probe 10 is a movable transceiver that contacts the surface of the subject. An array of vibrating elements, consisting of multiple transducers, is housed within probe 10. An ultrasonic beam is formed by the array of vibrating elements, and the ultrasonic beam is electronically scanned. This creates a beam scanning surface within the subject. The electronic scanning of the ultrasonic beam is repeated, thereby repeatedly forming the beam scanning surface. The beam scanning surface is a two-dimensional data acquisition area. Known electronic scanning methods include linear electronic scanning and sector electronic scanning. A two-dimensional vibrating element array can be installed within probe 10 to acquire volumetric data from the three-dimensional space within a biological organism.

[0034] The transmitting unit 12 is a transmitting circuit that functions as a transmitting beamformer. The receiving unit 14 is a receiving circuit that functions as a receiving beamformer. During transmission, the transmitting unit 12 outputs multiple transmitting signals in parallel to the vibrating element array, thereby forming a transmitting beam. During reception, if the vibrating element array receives reflected waves from within a living organism, it outputs multiple receiving signals in parallel to the receiving unit 14.

[0035] The receiving unit 14 performs phase modulation addition (delay addition) on multiple received signals to generate beam data. The beam data is the RF data before envelope detection. The receiving unit 14 includes multiple A / D converters, multiple delay units, and an adder. In practice, parallel reception is implemented in the receiving unit 14, and each reception generates multiple beam data arranged in the electronic scanning direction (beam scanning direction).

[0036] In the receiving unit 14, delay data assigned to each delay unit is calculated according to the transmitting aperture synthesis method. Specifically, when calculating each delay data, the propagation time of the transmitted wave from the center of the transmitting aperture (the reference position when determining the transmission reference) to the virtual sound source (transmission focus), the propagation time of the reflected wave from the receiving point to each vibrating element, and the propagation time of the spherical wave from the virtual sound source to the receiving point are taken into account.

[0037] As described above, multiple beam data arranged in parallel along the electronic scanning direction are generated in each transmission and reception cycle. These multiple beam data are combined into a single sub-image. This sub-image can also be described as a low-resolution image. Multiple sub-images arranged in the electronic scanning direction are generated by repeatedly transmitting and receiving while changing the positions of the transmitting and receiving apertures. These multiple sub-images partially overlap with each other. The multiple sub-images are then sequentially output side-by-side to the first combining unit 15A and the second combining unit 15B.

[0038] The first synthesis unit 15A and the second synthesis unit 15B each have a structure that follows the transmit aperture synthesis method. Specifically, the first synthesis unit 15A has a first weighting unit 16, a first storage unit 20, and a first synthesizer 24. The second synthesis unit 15B has a second weighting unit 18, a second storage unit 22, and a second synthesizer 26.

[0039] The first weighter 16 applies (specifically, a multiplication operation) to each sub-image and stores it in the first storage unit 20 using a first weight distribution. This generates multiple weighted sub-images. These weighted sub-images are then combined in the first synthesizer 24. This generates a first composite image. The first composite image can be considered a high-resolution image. Similarly, the second weighter 18 applies (specifically, a multiplication operation) to each sub-image and stores it in the second storage unit 22 using a second weight distribution. This generates multiple weighted sub-images. These are then combined in the second synthesizer 26. This generates a second composite image. The second composite image can also be considered a high-resolution image.

[0040] The contents of the first weight distribution and the second weight distribution are different. They are each composed of multiple weights in a two-dimensional distribution. Each sub-image is composed of multiple signal values ​​in a two-dimensional distribution. Each signal value is multiplied by its corresponding weight to obtain the weighted signal value. Each weight has a value between 0 and 1.0, for example. The signal value string is composed of RF signals or IQ signals (complex signals) with phase information.

[0041] In the first embodiment, the generation unit 32 includes a correlation coefficient calculator and a gain adjuster (multiplier). The generation unit 32 generates a display image based on the first composite image and the second composite image. Specifically, the generation unit 32 calculates a correlation coefficient set based on the first composite image and the second composite image, as a similarity set. Then, the correlation coefficient set is multiplied by the first composite image. This multiplication operation is for gain adjustment.

[0042] In the first embodiment, a first weight distribution and a second weight distribution are determined to reduce sidelobes after gain adjustment. Specifically, the first weight distribution is one that reduces sidelobes. The second weight distribution is one that retains more sidelobes after weighting compared to the first weight distribution. That is, the first weight distribution has a greater suppressive effect on sidelobes than the second weight distribution. The first weight distribution is the primary distribution, and the second weight distribution is an auxiliary distribution used for comparison.

[0043] In the first embodiment, the signal processing unit 34 includes an envelope detector and a logarithmic converter. Other circuits may also be included within the signal processing unit 34. In the first embodiment, the generation unit 32 and the signal processing unit 34 constitute module 30. A specific structural example of module 30 will follow. Figure 5 As shown.

[0044] The DSC (Digital Scan Converter) 36 functions as a coordinate transformation unit. That is, the DSC 36 transforms data following the transceiver coordinate system into data following the display coordinate system. In this embodiment, the DSC 36 performs coordinate transformation on the image to be displayed. The coordinate-transformed image is then sent to the display 38. The coordinate-transformed image is displayed on the display 38. This image is, for example, a tomographic image. In addition to coordinate transformation, the DSC 36 also has pixel interpolation and frame rate conversion functions. In practice, the display 38 displays a dynamic image composed of multiple images arranged on a time axis. The display 38 is composed of an LCD, an organic EL device, or the like.

[0045] Control unit 40 control Figure 1 The operation of each structure shown. The control unit 40 is composed of a CPU that executes the program. The first synthesis unit 15A, the second synthesis unit 15B, the generation unit 32, the signal processing unit 34, and the DSC 36 can each be composed of a processor. The CPU can function as the first synthesis unit 15A, the second synthesis unit 15B, the generation unit 32, the signal processing unit 34, and the DSC 36.

[0046] The control unit 40 is connected to the operation panel 42. The operation panel 42 is an input device equipped with multiple buttons, multiple knobs, a trackball, a keyboard, etc. Users (doctors, examination technicians, etc.) can use the operation panel 42 to set the transmission aperture synthesis conditions.

[0047] exist Figure 2The diagram illustrates a sub-image generation method. Reference numeral 52 indicates a vibrating element array. Reference numeral 54 indicates a transmit / receive aperture. The transmit and receive apertures can be set independently. Multiple transmit signals with a certain delay relationship are supplied to multiple vibrating elements within the transmit / receive aperture 54. This forms a transmit beam 56. The transmit beam 56 has a transmit focus 58. Figure 2 In the image, the gray areas represent the sound pressure levels above a certain value.

[0048] The transmission beam 56, viewed as a whole, has an hourglass shape. Within the transmission beam 56, the portion near the transmission focal point 58 tapers, creating a necking effect. The transmission beam 56 consists of a shallow portion 56A extending upwards from the transmission focal point 58 and a deep portion 56B extending downwards from the transmission focal point 58.

[0049] A receiving beam array 60 is formed by performing parallel reception during reception. The receiving beam array consists of multiple receiving beams arranged at certain intervals along the electronic scanning direction. Dynamic focusing technology is used during the formation of each receiving beam; that is, multiple receiving points (multiple receiving focal points) are sequentially formed along the depth direction. Figure 2 In the image, a specific receiving point 62 is shown.

[0050] To establish a receiving focus at receiving point 62, the first propagation time of the spherical wave from the transmitting focus (virtual sound source) 58 to receiving point 62 (refer to reference numeral 64) and the second propagation time of the reflected wave from receiving point 62 to each vibrating element (refer to, for example, 66A, 66B, 66C) are considered according to the virtual sound source method. Specifically, the delay data used for phase modulation addition is calculated by adding the propagation time of the transmitted wave from the center of the transmitting aperture to the transmitting focus 58, the first propagation time, and the second propagation time.

[0051] Multiple beam data constituting one sub-image are generated in a single transmit / receive cycle. By repeatedly performing transmit and receive operations while shifting the transmit and receive apertures, multiple sub-images arranged in the electronic scanning direction are generated per frame.

[0052] exist Figure 3 The diagram illustrates the method for generating a composite image. The horizontal axis represents the direction of electronic scanning. The vertical axis is the time axis.

[0053] In the first compositing unit, multiple sub-images La to Lk arranged along the electron scanning direction are each multiplied by a weight distribution WP1. A composite image H1 is generated by compositing the weighted sub-images. Similarly, in the second compositing unit, the aforementioned multiple sub-images La to Lk are each multiplied by a weight distribution WP2. A composite image H2 is generated by compositing the weighted sub-images.

[0054] exist Figure 4 The multiplication operation is shown for a first weight distribution WP1 and a second weight distribution WP2 for multiple sub-images La, Lb, ... The result of this multiplication operation is the generation of weighted sub-images La1, Lb1, ... and weighted sub-images La2, Lb2, ...

[0055] The first weight distribution WP1 has a symmetrical shape centered on the central axis C. Specifically, the first weight distribution WP1 has a peak-shaped profile at each depth, with the apex coinciding with the central axis C at each depth. The width of the peak-shaped profile gradually expands from the transmission focus upwards, and from the transmission focus downwards, the width of the peak-shaped profile also expands.

[0056] For example, at depth D1, the contour 74 becomes a peak that extends to a considerable degree, and at depth D2, the contour 76 becomes a peak that extends but is suppressed. By utilizing such a first weight distribution WP1, sidelobes generated by aperture synthesis can be reduced, and furthermore, brightness variations in the depth direction can be smoothed in the synthesized image. In each contour 74, 76, the horizontal axis corresponds to the electronic scanning direction, and the vertical axis represents the magnitude of the weight.

[0057] The second weight distribution WP2 has a symmetrical shape centered on the central axis C. Specifically, the second weight distribution WP2 has a trapezoidal profile at each depth. At each depth, the center of the profile coincides with the central axis C. The width of the trapezoidal profile extends from the transmission focus upwards and from the transmission focus downwards.

[0058] For example, at depth D1, the contour 78 becomes a trapezoid that extends to a considerable degree, and at depth D2, the contour 80 becomes a trapezoid that extends but is suppressed. By utilizing such a second weight distribution WP2, a synthetic image with more sidelobe components can be generated compared to the case using the first weight distribution WP1.

[0059] exist Figure 5 Show Figure 1 The diagram shows an example of the structure of module 30. The generation unit 32 consists of a correlation coefficient calculator 44 and a multiplier 46. The signal processing unit 34 consists of a detector 48 and a logarithmic converter 50.

[0060] The correlation coefficient calculator 44 compares the first composite image H1 and the second composite image H2 with each other, thereby calculating the correlation coefficient set as a similarity set. For example, the correlation coefficient ρ(m, n) is calculated according to the following equation (1).

[0061]

[0062] In equation (1) above, HRI1 represents the first composite image H1, and HRI2 represents the second composite image H2. Furthermore, m represents the receiving beam number, and n represents the receiving point number (sampling point number) in the depth direction. The size of the reference range in the depth direction is defined by A. The reference range has a size of 1 in the electronic scanning direction and a size of 2A+1 in the depth direction. A two-dimensional reference range can also be set instead of a one-dimensional reference range. Additionally, each composite image can be composed of real signals or IQ signals (complex signals).

[0063] In multiplier 46, each signal value constituting the first composite image is multiplied by its respective correlation coefficient. In fact, the multiplication is performed by the absolute value of the correlation coefficient calculated using equation (1). Multiplier 46 functions as a gain adjuster for the first composite image H1.

[0064] Detector 48 performs envelope detection on the image output from multiplier 46. Envelope detection converts the RF data into baseband data. Logarithmic converter 50 performs a logarithmic transformation on the detected image output from detector 48. This generates a logarithmically transformed image. This image is then output to the DSC for display.

[0065] According to the first embodiment, sidelobe components contained in the display image can be effectively suppressed without causing a reduction in frame rate. Multiple weight distribution pairs can also be prepared, and the weight distribution pair used can be selected according to the situation. Three or more composite images can also be generated using three or more weight distributions, and the display image can be generated based on these.

[0066] According to the first embodiment, unwanted components other than sidelobe components (e.g., multiple reflection components) can also be suppressed. The generation unit 32 can be equipped with a generator that includes a machine learning model for generating a display image based on the first and second synthesized images. In this case, the machine learning model can be trained to suppress unwanted components such as sidelobe components.

[0067] In the first embodiment, the contents of the first weight distribution and the second weight distribution can be dynamically changed during the electronic scanning of the ultrasonic beam, i.e., the electronic scanning of the transceiver aperture. During weighting and synthesis, processing can be performed on the data of each beam constituting each sub-image.

[0068] Next, based on Figure 6 as well as Figure 7 To illustrate the second implementation method. Figure 6 The structure of the ultrasound diagnostic device according to the second embodiment is shown. Additionally, in Figure 6 In the middle, to and Figure 1The structures shown are labeled with the same reference numerals as those in the accompanying drawings, and their descriptions are omitted. This is important for the explanations that follow. Figure 6 as well as Figure 9 The same applies.

[0069] In the second embodiment, a first weight distribution for artifact reduction is stored in the first storage unit 20, and a second weight distribution for artifact reduction is stored in the second storage unit 22. In the first weighter 16, multiple sub-images are multiplied by the first weight distribution, and the weighted multiple sub-images are combined in the first synthesizer 24 to generate a first composite image. Similarly, in the second weighter 18, multiple sub-images are multiplied by the second weight distribution, and the weighted multiple sub-images are combined in the second synthesizer 26 to generate a second composite image.

[0070] Module 82 includes a first post-processing unit 83A composed of a detector 84 and a logarithmic transformer 88, and a second post-processing unit 83B composed of a detector 86 and a logarithmic transformer 90. Furthermore, module 82 includes an adder 92. First post-processing (envelope detection and logarithmic transformation) is applied to the first composite image. Second post-processing (envelope detection and logarithmic transformation) is applied to the second composite image. The composite image after the first post-processing and the composite image after the second post-processing are added in the adder 92, thereby generating a display image. The display image is then sent to the DSC 36.

[0071] exist Figure 7 The diagram illustrates the weighting method according to the second embodiment. A first weighter multiplies multiple sub-images La, Lb, ... by a first weight distribution WP3. This generates multiple weighted sub-images La1, Lb1, ... . A first composite image is generated by combining these sub-images.

[0072] The first weighted distribution WP3 has a shape that is offset to one side relative to the central axis C in the electron scanning direction. For example, at depth D1, it becomes a peak-shaped profile 94 offset to one side in the electron scanning direction, and at depth D2, it also becomes a peak-shaped profile 96 offset to one side in the electron scanning direction. The width of the profile increases as it moves away from the transmission focus upwards or downwards. At each depth, the apex of the profile is offset to one side in the electron scanning direction.

[0073] The second weighter multiplies the multiple sub-images La, Lb, ... by the second weight distribution WP4. This generates multiple weighted sub-images La2, Lb2, ... . The second composite image is generated by combining these sub-images.

[0074] The second weight distribution WP4 has a shape that is offset to the opposite side relative to the central axis C in the electron scanning direction. For example, at depth D1, it becomes a peak-shaped profile 98 offset to the opposite side of the electron scanning direction, and at depth D2, it also becomes a peak-shaped profile 100 offset to the opposite side of the electron scanning direction. The width of the profile increases as it moves away from the transmission focus upwards or downwards. At each depth, the apex of the profile is offset to the opposite side of the electron scanning direction. The first weight distribution WP3 and the second weight distribution WP2 have a linearly symmetrical relationship with respect to the central axis.

[0075] According to the second embodiment, by adding the first composite image and the second composite image generated as described above, artifacts can be effectively reduced. In the second embodiment, the first composite image after the first post-processing and the second composite image after the second post-processing are added together. However, it is also possible to apply post-processing (i.e., envelope detection and logarithmic transformation) to the display image based on the first composite image and the second composite image before post-processing. Alternatively, the first composite image after envelope detection and the second composite image can be added together.

[0076] exist Figure 8 The structure involved in the first modification is shown. The first modification is equivalent to a scheme in which the structure of the receiving unit is changed in the ultrasonic diagnostic apparatus according to the first embodiment.

[0077] In the first modification, the receiving unit 14A has two processing systems arranged in parallel. Specifically, the receiving unit 14A includes a first pre-stage weighting unit 102, a second pre-stage weighting unit 104, a first phase modulation adder 110, a second phase modulation adder 112, and a pre-stage synthesizer 114. The first pre-stage weighting unit 102 multiplies the multiple received signals output from the transceiver aperture by a first weighting function 106. The second pre-stage weighting unit 104 multiplies the multiple received signals output from the transceiver aperture by a second weighting function 108. The first weighting function 106 and the second weighting function 108 are each composed of weight strings arranged along the electronic scanning direction. These have a form for reducing unwanted components such as sidelobe components. Examples of these functions are shown, for example, in the aforementioned documents 3 and 4.

[0078] In the first phase modulation adder 110, multiple weighted received signals are subjected to phase modulation addition using a parallel receiving method, thereby generating multiple beam data. These correspond to the first sub-image. Similarly, in the second phase modulation adder 112, multiple weighted received signals are subjected to phase modulation addition using a parallel receiving method, thereby generating multiple beam data. These correspond to the second sub-image. The weighted first sub-image and the weighted second sub-image are combined (added) in the pre-combiner 114. This generates a composite sub-image. Multiple composite sub-images are generated sequentially during electronic scanning and sent side-by-side to the first combining unit 15A and the second combining unit 15B.

[0079] according to Figure 8 The first variation shown can further suppress unwanted components such as sidelobe components. In this variation, the first preamplifier 102 and the second preamplifier 104 can operate alternately in a time-division manner.

[0080] exist Figure 9 The structure involved in the second modification is shown in the figure. The structure involved in the second modification is equivalent to a scheme in which the second assembly part is partially changed in the structure involved in the first embodiment.

[0081] exist Figure 9 In the second modified example shown, the first composite part 15A has the same as Figure 1 The first synthesis unit 15A shown has the same structure. However, in the second variation, the second synthesis unit 15C does not have a second weighter, but only a second synthesizer 26A. In the second synthesizer 26A, multiple sub-images output from the receiving unit 14 are synthesized unchanged, thereby generating a second synthesized image. In the generation unit 32, a correlation coefficient set is calculated based on the first synthesized image and the second synthesized image, and this correlation coefficient set is multiplied by the first synthesized image. Thus, a display image is generated.

[0082] In the second modification, sidelobe components contained in the displayed image can also be suppressed. According to the second modification, since weighting processing is not required in the second synthesis unit 15C, the structure of this part of the ultrasound diagnostic device can be simplified.

Claims

1. An ultrasonic diagnostic device, characterized in that, Include: The receiving unit (14) generates multiple sub-images for transmitting aperture synthesis. The first synthesis unit (15A) synthesizes the plurality of sub-images based on the first weight distribution, thereby generating a first synthesized image; The second compositing unit (15B) combines the multiple sub-images using a second weight distribution that is different from the first weight distribution, thereby generating a second composite image; and The generation unit (32) generates a display image based on the first composite image and the second composite image. The first weight distribution and the second weight distribution are applied to the same sub-image.

2. The ultrasonic diagnostic device according to claim 1, characterized in that, The generating unit (32) includes: The processor (44) calculates a similarity set based on the first synthesized image and the second synthesized image; and A gain adjuster (46) adjusts the gain of one or both of the first composite image and the second composite image based on the similarity set, thereby generating the image for display.

3. The ultrasonic diagnostic device according to claim 2, characterized in that, The gain adjuster (46) generates the display image by multiplying the first synthesized image by the similarity set.

4. The ultrasonic diagnostic device according to claim 3, characterized in that, The second weighted distribution is a distribution that, compared to the first weighted distribution, results in an increase in the sidelobe component after weighting.

5. The ultrasonic diagnostic device according to claim 3, characterized in that, The ultrasonic diagnostic device includes: Detector (48) performs envelope detection on the display image output from the gain adjuster (46); and Logarithmic transformer (50) applies logarithmic transformation to the display image output from the detector (48).

6. The ultrasonic diagnostic device according to claim 1, characterized in that, The generating unit (32) includes: The first post-processor (83A) applies envelope detection and logarithmic transformation to the first synthesized image; The second post-processor (83B) applies envelope detection and logarithmic transformation to the second synthesized image; and The adder (92) adds the first composite image output from the first post-processor and the second composite image output from the second post-processor to generate the display image.

7. The ultrasonic diagnostic device according to claim 6, characterized in that, The first weight distribution has a shape that is offset to one side of the electron scanning direction at each depth position. The second weight distribution has a shape that is offset to the other side of the electron scanning direction at each depth position.

8. An image processing method, characterized in that, Include: Step (14) generates multiple sub-images for sending aperture synthesis; Step (24): The multiple sub-images are synthesized based on the first weight distribution to generate the first synthesized image; Step (26): The multiple sub-images are synthesized using a second weight distribution that is different from the first weight distribution to generate a second composite image; or, the multiple sub-images are synthesized to generate a second composite image. Step (44): Calculate a similarity set based on the first synthesized image and the second synthesized image; and Step (46): Adjust the gain of the first synthesized image based on the similarity set, thereby generating a display image. The first weight distribution and the second weight distribution are applied to the same sub-image.

Images