JP2015188516A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique to increase density of an ultrasonic image of a plurality of frames in a frame direction.SOLUTION: A density increasing section 20 increases density of frame data of a plurality of frames acquired by scanning an ultrasonic beam. The density increasing section 20 increases density of the frame data of the plurality of frames in a frame direction by acquiring data corresponding a frame between the frames on the basis of the data in each frame. Thereby, frame density of the frame data is increased.

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a technique for increasing the density of an ultrasonic image.

  By using an ultrasonic diagnostic apparatus, for example, a moving image of a moving tissue or the like can be obtained in real time for diagnosis. In addition, a three-dimensional ultrasonic image in which a tissue or the like is three-dimensionally expressed can be formed by three-dimensionally scanning an ultrasonic beam and obtaining echo data from within the three-dimensional space. In particular, an ultrasonic diagnostic apparatus is an extremely important medical device in recent diagnosis and treatment of the heart and the like.

  In general, it is desirable that the image quality of an ultrasonic image obtained by an ultrasonic diagnostic apparatus is good, not limited to diagnosis of the heart or the like. As a specific measure for improving the image quality of an ultrasonic image, a technique for increasing the density of the ultrasonic image has been proposed.

  For example, in Patent Document 1, pattern matching processing is executed between the previous frame and the current frame for each pixel of interest on the previous frame, and pattern matching is performed for each primitive pixel and the pixel of interest that formed the current frame. Techniques for densifying the current frame based on additional pixel groups defined by processing are described.

  In Patent Document 2, the first pixel column, the second pixel column, and the third pixel column are defined in the frame, and for each pixel of interest on the first pixel column, the first pixel column, the second pixel column, The pattern matching process is performed between the pixels, the mapping address on the second pixel column for the target pixel is calculated, and for each target pixel on the third pixel column, the third pixel column and the second pixel column Pattern matching processing is performed between them, a mapping address on the second pixel column for the target pixel is calculated, and the second pixel column is densely formed using the pixel values and mapping addresses of the plurality of target pixels. The technology to be converted is described.

  By using the techniques described in Patent Documents 1 and 2, for example, it is possible to increase the density of a low-density image obtained at a high frame rate.

JP 2012-105750 A JP 2012-105751 A

  In view of the background art described above, the inventor of the present application has conducted research and development on improved techniques for increasing the density of ultrasonic images. In particular, we focused on increasing the density in the frame direction for ultrasonic images of multiple frames.

  The present invention has been made in the process of research and development described above, and an object of the present invention is to provide a technique for increasing the density of ultrasonic images of a plurality of frames in the frame direction.

  An ultrasonic diagnostic apparatus suitable for the above object includes a probe for transmitting / receiving ultrasonic waves, a transmission / reception unit for controlling the probe to scan an ultrasonic beam, and a plurality of frames of frame data obtained by scanning the ultrasonic beam. A densification processing unit that densifies the image and an image forming unit that forms an ultrasonic image based on the densified frame data. The densification processing unit includes data in each frame. By obtaining data corresponding to between frames based on the above, the frame data of a plurality of frames is densified in the frame direction.

  In the above configuration, the probe for transmitting and receiving ultrasonic waves has various types according to diagnostic applications such as convex scanning type, sector scanning type, linear scanning type, two-dimensional image (tomographic image), three-dimensional image, etc. Can be used. A plurality of frames of frame data can be obtained by scanning the ultrasonic beam while controlling the probe.

  Within each frame, in particular, with respect to the depth direction of the ultrasonic beam, it is possible to continuously obtain ultrasonic reception signals from the shallow part (the side closer to the probe) to the deep part (the side far from the probe). Therefore, data arranged at a relatively high density can be obtained. For example, it is possible to obtain line data consisting of thousands of data along one ultrasonic beam, and each frame may be formed by using thousands of line data as they are, or thousands of pieces of data may be formed. Each frame may be formed using hundreds of pieces of data obtained by resampling (decimation) the line data. Then, by scanning the ultrasonic beam within the scanning surface, for example, by sequentially forming the position (angle) of the ultrasonic beam along the azimuth direction while forming a plurality of ultrasonic beams one after another, the scanning surface Line data is collected in each frame corresponding to.

  Further, for example, a plurality of frames are formed while shifting the frame position in the three-dimensional space. Alternatively, a plurality of frames are formed over a plurality of time phases while substantially fixing the frame position in the two-dimensional plane. However, in general, the data density (frame density) in the frame direction of a plurality of frames tends to be lower than line data obtained at a relatively high density in each frame. That is, the data density tends to be different between the data in each frame and the data arranged in the frame direction.

  According to the above-described apparatus, it is possible to increase the density of ultrasonic images using the density relationship between the data in each frame and the data arranged in the frame direction. That is, by obtaining data corresponding to each frame based on the data in each frame, the frame data of a plurality of frames is densified in the frame direction.

  In a preferred embodiment, the densification processing unit arranges a template corresponding to a frame direction in frame data of a plurality of frames, and moves a window in each frame to search for a window that matches the template. Based on the data in the window that matches the template, data corresponding to the frames in the template is obtained.

  In a preferred embodiment, the densification processing unit searches for a window that matches the template by pattern matching based on data in the template and data in the window.

  In a preferred embodiment, the densification processing unit searches for a window that matches the template by pattern matching based on data in the template and data selected from the window at a data interval in the template. It is characterized by.

  In a preferred embodiment, the densification processing unit inserts densified data based on data in a window that matches a template between data of a plurality of data arranged in the frame direction in the template. To do.

  In a preferred embodiment, the densification processing unit sets a window corresponding to the depth direction of the ultrasonic beam.

  In a preferred embodiment, the densification processing unit sets the template and the window so that the sizes in the real space are equal to each other.

  In a preferred embodiment, the densification processing unit arranges templates at a plurality of different positions in the frame data of the original frame obtained by scanning the ultrasonic beam, and sets windows that match the template at each position. By searching, data corresponding to between frames is obtained at a plurality of positions where the template is arranged.

  In a preferred embodiment, the densification processing unit forms an insertion frame based on data corresponding to frames obtained at a plurality of positions where templates are arranged, and inserts the insertion frame between frames of the original frame. The frame density of the frame data is increased.

  The present invention provides a technique for increasing the density of a plurality of frames of ultrasonic images in the frame direction. For example, according to a preferred aspect of the present invention, it is possible to increase the density of ultrasonic images using the density relationship between the data in each frame and the data arranged in the frame direction. That is, by obtaining data corresponding to each frame based on the data in each frame, the frame data of a plurality of frames is densified in the frame direction.

1 is a functional block diagram showing an overall configuration of a preferable ultrasonic diagnostic apparatus of the present invention. It is a figure which shows the specific example of the frame data densified. It is a figure for demonstrating the densification in a frame direction. It is a figure for demonstrating evaluation of similarity. It is a figure which shows the example of calculation of densification data. It is a figure for demonstrating the specific example 1 of density increase in a frame direction. It is a figure for demonstrating the specific example 2 of density increase in a frame direction. It is a figure for demonstrating the various processes with respect to an original frame. It is a figure for demonstrating the filter process of the depth direction with respect to an insertion frame. It is a figure for demonstrating the modification of the process in the densification process part.

  FIG. 1 is a functional block diagram showing an overall configuration of an ultrasonic diagnostic apparatus suitable for implementing the present invention. The probe 10 is an ultrasonic probe that transmits and receives ultrasonic waves. For example, various ultrasonic probes such as a convex scanning type, a sector scanning type, a linear scanning type, a two-dimensional image (tomographic image), and a three-dimensional image can be used as the probe 10 in accordance with a diagnostic application. it can.

  The transmission / reception unit 12 controls transmission of a plurality of vibration elements included in the probe 10 to form a transmission beam, and scans the transmission beam in the diagnostic region. In addition, the transmission / reception unit 12 forms a reception beam by, for example, performing phasing addition processing on a plurality of reception signals obtained from the plurality of vibration elements, and collects reception beam signals from the entire diagnosis area. That is, the transmission / reception unit 12 has a beamformer function. The collected reception beam signal (RF signal) is subjected to reception signal processing such as detection processing. Thereby, the line data obtained along each received beam is sent to the densification processing unit 20 for each received beam.

  The densification processing unit 20 densifies the frame data of a plurality of frames obtained by scanning the ultrasonic beam (transmission beam and reception beam). The densification processor 20 obtains data corresponding to each frame based on the data in each frame, thereby densifying the frame data of a plurality of frames in the frame direction. That is, the frame density of the frame data is increased. Specific processing in the densification processing unit 20 will be described in detail later.

  The digital scan converter (DSC) 30 performs a coordinate conversion process or the like on the frame data densified by the densification processor 20. The digital scan converter 30 performs, for example, frame data corresponding to the display coordinate system by performing coordinate conversion processing, interpolation processing, and the like for each frame from the frame data obtained in the scanning coordinate system corresponding to the scanning of the ultrasonic beam. Get.

  The image forming unit 40 forms an ultrasonic image based on the frame data obtained from the digital scan converter 30, that is, the frame data of a plurality of frames that have been densified and converted into a display coordinate system. For example, based on frame data of a plurality of frames obtained three-dimensionally from within a three-dimensional space including the diagnosis target, a three-dimensional ultrasound image that displays the diagnosis target three-dimensionally is formed. In addition, for example, based on frame data of a plurality of frames obtained from a diagnosis target over a plurality of time phases, an ultrasonic image of a moving image that dynamically displays the diagnosis target is formed.

  The ultrasonic image formed in the image forming unit 40 is combined with graphic data or the like as necessary and displayed on the display unit 42. And the control part 50 controls the inside of the ultrasound diagnosing device of FIG. 1 entirely.

  In FIG. 1, the densification processing unit 20 is disposed in the previous stage of the digital scan converter 30, but the densification processing unit 20 may be disposed in the subsequent stage of the digital scan converter 30. In that case, the frame data of a plurality of frames obtained from the transmission / reception unit 12 is converted into the display coordinate system by the digital scan converter 30, and the frame data of the plurality of frames converted into the display coordinate system is converted by the densification processing unit 20. The image forming unit 40 forms an ultrasonic image based on the frame data of a plurality of frames corresponding to the display coordinate system that is densified in the frame direction and densified.

  In the configuration (functional blocks) shown in FIG. 1, the transmission / reception unit 12, the densification processing unit 20, the DSC 30, and the image forming unit 40 are realized by using hardware such as a processor or an electronic circuit, respectively. In the realization, a device such as a memory may be used as necessary. A suitable specific example of the display unit 42 is, for example, a liquid crystal display. The control unit 50 can be realized by, for example, cooperation between hardware such as a CPU, a processor, and a memory, and software (program) that defines the operation of the CPU and the processor.

  The overall configuration of the ultrasonic diagnostic apparatus in FIG. 1 is as described above. Next, the densification process in the ultrasonic diagnostic apparatus will be described. In addition, about the structure (block) shown in FIG. 1, the code | symbol of FIG. 1 is utilized in the following description.

  FIG. 2 is a diagram illustrating a specific example of frame data to be densified. FIG. 2 shows a specific example of frame data of a plurality of frames obtained by scanning an ultrasonic beam.

  For example, each frame is formed by electronically scanning an ultrasonic beam formed along the depth direction r in the azimuth direction θ, and three-dimensionally moving each frame electronically or mechanically in the frame direction. By scanning the ultrasonic beam, the frame data of a plurality of frames can be obtained three-dimensionally from within the three-dimensional space. The frame direction in this case is a spatial direction (for example, direction φ) in which each frame moves. Incidentally, the frame data obtained by, for example, the rθφ coordinate system corresponding to the scanning of the ultrasonic beam is coordinate-converted by the digital scan converter 30 into frame data of, for example, an xyz orthogonal coordinate system suitable for display.

  Further, an ultrasonic beam formed along the depth direction r is electronically scanned in the azimuth direction θ to form each frame for each time phase, and the position of each frame is left as it is over a plurality of time phases. By scanning the ultrasonic beam, frame data of a plurality of frames corresponding to a plurality of time phases can be obtained. The frame direction in this case is a time direction indicating a time phase at which each frame is obtained. Incidentally, the data of each frame obtained by, for example, the rθ coordinate system corresponding to the scanning of the ultrasonic beam is coordinate-converted by the digital scan converter 30 into, for example, xy orthogonal coordinate system data suitable for display.

  Each frame is composed of a plurality of line data arranged two-dimensionally along the depth direction r and the azimuth direction θ. Line data is collected along the depth direction r of the ultrasonic beam. Regarding the depth direction r, since ultrasonic reception signals can be continuously obtained from the shallow part (side closer to the probe 10) to the deep part (side far from the probe 10), they are arranged at a relatively high density. Line data can be obtained. For example, thousands of line data can be obtained along one ultrasonic beam, and thousands of line data can be used as they are, or thousands of line data can be resampled (decimation). Hundreds of line data obtained by the above method may be used.

  Then, the ultrasonic beam is scanned in the azimuth direction θ, and a plurality of ultrasonic beams are formed one after another while gradually shifting the angle and position of the ultrasonic beam. For each frame, for example, about several tens to one hundred ultrasonic beams are formed, and a plurality of line data are collected two-dimensionally.

  Further, for example, a plurality of frames are formed while shifting the frame position in a three-dimensional space, and a plurality of line data is collected three-dimensionally to constitute frame data. Alternatively, a plurality of frames are formed over a plurality of time phases while fixing the frame position in the two-dimensional plane, and a plurality of line data are collected over a plurality of time phases in the two-dimensional plane to form frame data. . Note that the frame data obtained three-dimensionally from within the three-dimensional space is called volume data, and furthermore, by obtaining volume data over a plurality of time phases, an ultrasonic image based on a three-dimensional moving image may be formed. It becomes possible.

  However, in order to obtain volume data, it is necessary to collect a lot of line data by three-dimensionally scanning an ultrasonic beam, and the data collection time becomes long. Therefore, the volume rate (number of volumes per unit time) is increased. There are concerns about such problems.

  For example, in order to increase the line density in each frame (the density of line data constituting each frame) while maintaining the volume rate, it is necessary to reduce the frame density (the number of frames per unit length) in the frame direction. There is. In order to increase the frame density while maintaining the volume rate, it is necessary to reduce the line density. That is, when maintaining the volume rate, the line density and the frame density are in a trade-off relationship with each other. In general, line data is obtained at a relatively high density in each frame by electronic scanning. Therefore, the line density is maintained at a high density and the image quality of the electronic scanning surface is emphasized, and the frame density is low. Tend to be.

  Therefore, the high-density processing unit 20 obtains data corresponding to the frames based on the relatively high-density data (line data) constituting each frame, so that the frame density in the relatively low-density frame direction is obtained. To increase. The high density processing unit 30 arranges a template corresponding to the frame direction in the frame data of a plurality of frames, and moves the window in each frame to search for a window that matches the template, thereby matching the template. Data corresponding to the frames in the template is obtained based on the data in the window, and the frame data is densified in the frame direction.

  FIG. 3 is a diagram for explaining an increase in density in the frame direction, and shows a specific example of a search using a template and a window. FIG. 3 illustrates frame data of a plurality of frames including frames F1 to F6, a template T arranged in the frame data of the plurality of frames, and a window I that is used for searching by moving in each frame. ing.

  In the specific example shown in FIG. 3, the template T has a one-dimensional shape extended in the frame direction, which is the arrangement direction of a plurality of frames. Assuming that the data arranged along the frame direction in the frame data is the frame direction data, the frame direction data including the six data T1 to T6 belonging to the six frames F1 to F6 is included in the template T in FIG. include.

  Note that the template T is preferably a shape (shape or extension direction) corresponding to the frame direction, but it is not necessarily parallel to the frame direction. For example, a template T inclined obliquely with respect to the frame direction may be set. Further, the template T is not limited to a one-dimensional shape, and may be a two-dimensional shape (rectangular or other polygonal shape, circular shape, elliptical shape, or the like), or a three-dimensional shape template T may be used.

  In the specific example shown in FIG. 3, the window I has a one-dimensional shape extended in the depth direction r of the ultrasonic beam. Of the data constituting each frame, if the data arranged along the depth direction r is the depth direction data, the window I in FIG. 3 includes six pieces of data S31 to S36 (or data S41 to S46). Depth direction data is included.

  Note that the window I is preferably a shape (shape or extension direction) corresponding to the depth direction r, but it is not necessarily parallel to the depth direction r. For example, a window I inclined obliquely with respect to the depth direction r may be set. A window I corresponding to the azimuth direction θ may be set. For example, a window I parallel to the azimuth direction θ or a window I inclined obliquely with respect to the azimuth direction θ may be set. Further, the window I is not limited to a one-dimensional shape, and may be a two-dimensional shape (rectangular or other polygonal shape, circular or elliptical shape), or a three-dimensional window I may be used.

  The template T and the window I preferably have the same shape, although the extension directions are different from each other. Further, it is desirable that the data interval in the template T and the data interval selected in the window I are equal to each other in the real space.

  The densification processing unit 20 sets a search area for the window I, moves the window I within each frame to be the search area, and searches for the window I that matches the template T. For example, the densification processing unit 20 desirably sets a search region based on a frame corresponding to the template T. In the specific example shown in FIG. 3, the template T corresponds to a frame F3 ′ inserted between the frame F3 and the frame F4. Therefore, the densification processing unit 20 uses, for example, the frames F3 and F4 adjacent to the frame F3 ′ corresponding to the template T as search areas. Then, the densification processing unit 30 searches for the window I that matches the template T by moving the window I in the frame F3 and the frame F4.

  The search area is not limited to only a frame adjacent to the frame corresponding to the template T. For example, the search area may be from a frame corresponding to the template T to a frame several frames away. In addition, when volume data is composed of frame data of a plurality of frames and volume data can be obtained over a plurality of time phases, in addition to one or more frames included in the volume data of the time phase where the template T is arranged. Thus, one or more frames included in volume data of another time phase, for example, an adjacent time phase, may be set as the search area.

  When the template T is arranged and the search area of the window I is set, the high-density processing unit 20 performs pattern matching between data belonging to the template T (frame direction data) and data belonging to the window I (depth direction data). Thus, the window I that matches the template T is searched. The densification processing unit 20 searches for a window that matches the template by pattern matching based on the similarity between the data in the template T and the data selected from the window I at the data interval in the template T. To do.

  For example, in the specific example shown in FIG. 3, the similarity between the template T and the window I in the frame F4 has six data T1 to T6 belonging to the template T, the six data T1 to T6, and the actual data. Evaluation is performed between six pieces of data S41 to S46 selected from the window I at the same interval in the space.

  FIG. 4 is a diagram for explaining the evaluation of the degree of similarity. FIG. 4 shows specific examples of the template T and the window I. In the evaluation of the similarity, for example, a similarity calculation represented by the sum of squares of luminance difference (SSD) shown in Formula 1 or the absolute sum of brightness differences (SAD) shown in Formula 2 can be used.

  In addition, the ultrasonic diagnostic apparatus of FIG. 1 adjusts the gain in an ultrasonic image locally by gain adjustment (STC etc.) according to depth, or gain adjustment (ANGLEGAIN etc.) of an azimuth | direction direction, for example. Can do. Therefore, in pattern matching, it is desirable to use an evaluation value that is robust to brightness (luminance magnitude). Therefore, ZSAD (Zero-mean Sum of Absolute Difference) shown in the following equation is defined as the evaluation value, and the densification processing unit 20 calculates similarity by using ZSAD of the following equation in pattern matching. Also good.

  The symbols shown in FIG. 4 correspond to the variables in Equation 1 to Equation 3. For example, L, M, and N indicate the size of the template T. L indicates the size of the template T in the frame direction, that is, the number of data arranged in the frame direction. M indicates the size of the template T in the azimuth direction, that is, the number of data arranged in the azimuth direction. N indicates the size of the template T in the depth direction, that is, the number of data arranged in the depth direction. In the specific example shown in FIG. 4, L = 4, M = 1, and N = 1.

  T (i + p, j + q, k + r) indicates the value (pixel value) of each data (each pixel) in the template T, i + p is the azimuth direction coordinate, j + q is the depth direction coordinate, and k + r is the frame direction. Coordinates (frame number).

  Further, I (a + p, b + d · r, c + q) indicates the value (pixel value) of each data (each pixel) in the window I, a + p is the azimuth direction coordinate, and b + d · r is the depth direction coordinate. And c + q is a frame direction coordinate (frame number). In the window I, each data in the depth direction is selected at a data interval in the frame direction in the template T. The data interval in the selection is d, and one data is selected from the window I for every d pieces of data arranged along the depth direction.

  In FIG. 4 and Equations 1 to 3, the number of frames (total number of plural frames) is D, the number of lines in each frame (total number of lines constituting each frame) is W, and The number of data per line (the total number of data constituting one line) is H.

  Returning to FIG. 3, in pattern matching, while moving the window I stepwise along the depth direction r within each frame serving as a search region, for example, the data lined up in high density along the depth direction r While moving the window I one by one, at each position, the evaluation value of the similarity is calculated between the window I and the template T by, for example, any one of the equations (1) to (3). Furthermore, the position is shifted by one ultrasonic beam along the azimuth direction θ and the window I is moved along the depth direction r, and an evaluation value of similarity is calculated at each position. Note that the window I may be moved stepwise along the depth direction r at several data intervals and along the azimuth direction θ at several beam intervals.

  In this way, the evaluation value of the similarity is calculated at each position while moving the window I over the entire area in one or more frames serving as search areas. A part of each frame may be a search area. In the search area, for example, the window I at the position where the evaluation value of the similarity is the minimum value is set as the window I that matches the template T.

  Data constituting each frame (line data arranged in the depth direction r) may be before or after the decimation (resampling). Since there is a large amount of data before decimation, the accuracy of pattern matching is increased, and after decimation, data is thinned out, so that the calculation load of pattern matching can be reduced.

  When the window I matching the template T is searched, the data in the template T is densified by the densified data obtained from the window I. In the specific example shown in FIG. 3, the window I of the frame F4 is selected as the window I that matches the template T, and the data SR obtained from the window I becomes the densified data, and the data T3 and data of the template T Inserted between T4. That is, data SR that is high-density data is inserted as data of frame F3 ′.

  The window I that conforms to the template T is the window I in which the evaluation value of any one of the equations (1) to (3) is minimum in the search region, and is the image portion most similar to the template T. The template T corresponds to the frame direction, and the window I corresponds to the depth direction r (which may be the azimuth direction θ). Although the directions corresponding to each other are different, the template T and the window I matching it are the most similar images. It is very likely that the acoustic behavior of the ultrasonic waves and the tissue properties are very similar to each other.

  Therefore, as in the specific example shown in FIG. 3, the data SR obtained from the window I that matches the template T is used as the densified data, and is inserted into the gap between the data arranged in the frame direction of the template T. It is desirable that the position of the high density data in the window I and the insertion position of the high density data in the template T are equal to each other. For example, as in the specific example shown in FIG. 3, it is desirable that the densified data obtained from the center of the window I is inserted into the center of the template T. Note that the high-density data may be selected from data other than the center of the window I. Further, the densified data may be calculated by calculation based on the data in the window I.

  FIG. 5 is a diagram illustrating a calculation example of the densified data. FIG. 5 shows specific examples of the luminance pattern (pixel values 70, 80, 75, 50) in the template T and the luminance pattern (pixel values 100, 110, 105, 80) in the window I.

In the specific example shown in FIG. 5, R _SAD = 120 when the SAD of Formula 2 is used. On the other hand, in the specific example shown in FIG. 5, if ZSAD of Formula 3 is used, R _ZSAD = 0, and there is a possibility that the window I in FIG. 5 is selected as the window I that matches the template T in FIG. Rise. That is, by using the ZSAD of Formula 3, even when there is gain adjustment, for example, the similarity can be evaluated by subtracting the overall (average) fluctuation component due to gain adjustment etc. from the luminance pattern. The pattern matching accuracy can be improved.

  In the specific example shown in FIG. 5, when the pixel D (pixel value D) in the window I is inserted between the pixels in the template T (between frames) to be the pixel D ′ (pixel value D), A pixel value is determined based on the following equation.

  Returning to FIG. 3, the densification processing unit 20 moves the template T, that is, the template T corresponding to the frame F3 ′, in the depth direction r and the azimuth direction θ, so that a plurality of the density increase processing unit 20 extends over the entire area of the frame F3 ′. The template T is arranged at the position, and the window I that matches the template T at each position is searched. Thereby, the densified data to be inserted into the template T at a plurality of positions is determined, and data of the frame F3 ′ is formed. Further, the densification processing unit 20 also applies the templates T to the frames F1 ′, F2 ′, F4 ′, F5 ′,... Shown in FIG. By arranging and searching for a window I that matches the template T at each position, densified data to be inserted into the template T at a plurality of positions is determined, and data for each frame is formed.

  Thus, for example, as in the specific example shown in FIG. 3, a plurality of frames F1 ′ to F5 ′ obtained based on pattern matching are added to the initial plurality of frames F1 to F6 (original frames) obtained by transmitting and receiving ultrasonic waves. (Inserted frame) is inserted, and the frame density of frame data composed of a plurality of frames is increased. That is, the frame data is densified in the frame direction.

  FIG. 6 is a diagram for explaining a specific example 1 of increasing the density in the frame direction. Specific example 1 shown in FIG. 6 is an example in which high-density volume data is formed from frame data of a plurality of frames.

  In FIG. 6, a plurality of original frames including frames F <b> 1 to F <b> 6 are frame data before densification processing obtained by transmitting and receiving ultrasonic waves. The frame data of the original frame is stored in a 3D memory or the like for each volume, for example. Then, from the frame data of the original frame, the densification processing unit 20 forms insertion frames of the frames F1 ′ to F5 ′ by the processing described with reference to FIG.

  Further, the densification processing unit 20 synthesizes the original frame and the insertion frame to form the densified volume data. For example, as shown in FIG. 6, a frame F1 ′ is inserted between the frames F1 and F2, a frame F2 ′ is inserted between the frames F2 and F3, and a frame F3 ′ is inserted between the frames F3 and F4. Is inserted, the frame F4 ′ is inserted between the frames F4 and F5, and the frame F5 ′ is inserted between the frames F5 and F6, thereby forming the volume data with high density.

  FIG. 7 is a diagram for explaining a specific example 2 of high density in the frame direction. Specific example 2 shown in FIG. 7 is an example in which a moving image (for example, a real-time B-mode image) of a two-dimensional ultrasonic image is formed from frame data of a plurality of frames corresponding to a plurality of time phases.

  In FIG. 7, a plurality of original frames including frames F <b> 1 to F <b> 6 are frame data before densification processing obtained by transmitting and receiving ultrasonic waves. For example, each frame is generated for each time phase in the order of frame F1, frame F2, frame F3,. The frames generated one after another are temporarily stored in the frame buffer. For example, a plurality of frames necessary as at least a search area (FIG. 3) are temporarily stored in the frame buffer.

  Then, from the frame data of the original frames stored in the frame buffer one after another, the densification processing unit 20 forms inserted frames of the frames F1 ′ to F5 ′ one after another by the process described using FIG.

  Further, the densification processing unit 20 alternately selects each frame of the original frame and each frame of the insertion frame in time order by the selector, and outputs the frame data densified in the frame direction, that is, in the time phase direction. To do. For example, as shown in FIG. 7, the frames are output in the order of frame F1, frame F1 ′, frame F2, frame F2 ′, frame F3, frame F3 ′,. As a result, the frame rate is higher than the frame rate in the case of only the original frame.

  As described above, by inserting the insertion frame into the original frame, the frame data is densified in the frame direction. At that time, it is desirable that the original frame and the inserted frame are not greatly different in image quality and the like. Therefore, the ultrasonic diagnostic apparatus of FIG. 1 performs processing equivalent to various processing on the original frame on the insertion frame.

  FIG. 8 is a diagram for explaining various processes for the original frame. FIG. 8 shows various processes for line data constituting each frame of the original frame. The various processes shown in FIG. 8 are executed by, for example, the transmission / reception unit 12 or the densification processing unit 20.

  (A) shows the original line data obtained in the transmission / reception unit 12. The original line data shown in (A) is data for one ultrasonic beam (received beam), and is composed of, for example, hundreds to thousands of sampling data.

  The ultrasonic diagnostic apparatus in FIG. 1 performs filtering in the depth direction r on the original line data. For example, FIR filter processing is performed on some sampling data arranged in the depth direction r. FIG. 8A shows an nTap (tap) FIR filter for n sampling data (n is a natural number) as a specific example of the filter processing. For example, the filtered line shown in (B) is obtained by sequentially obtaining the data after filtering while shifting the window (n data range) of the nTapFIR filter one by one along the depth direction r. Data is obtained.

  The ultrasonic diagnostic apparatus of FIG. 1 performs re-sampling processing on the filtered line data shown in FIG. 8B to obtain the re-sampled line data shown in FIG. For example, sampling data is extracted at several data intervals from filtered line data arranged in the depth direction r, and line data after resampling is obtained.

  It should be noted that by shifting the nTapFIR filter several data at a time and obtaining the filtered data, the resampled line data shown in (C) is obtained directly from the original line data shown in (A). It may be.

  The ultrasound diagnostic apparatus in FIG. 1 uses, as an original frame, frame data of a plurality of frames constituted by the line data after resampling shown in (C) of FIG. 8, that is, the line data shown in (C ′). Then, an insertion frame is formed from the original frame by the pattern matching process described with reference to FIG. The ultrasonic diagnostic apparatus in FIG. 1 performs a filtering process in the depth direction r described below on the formed insertion frame.

  FIG. 9 is a diagram for explaining the filtering process in the depth direction for the insertion frame. FIG. 9 shows one (one) insertion frame. That is, the depth direction r of the ultrasonic beam and the azimuth direction θ of the ultrasonic beam are shown, and a plurality of white circles (unfilled circles) arranged along the depth direction r are subjected to pattern matching processing ( This is the data (densified data) obtained by FIG.

  The ultrasonic diagnostic apparatus in FIG. 1 performs a filtering process similar to the filtering process in the depth direction r on the original line data in FIG. 8 on the densified data (white circles) constituting the insertion frame in FIG. . The same level means, for example, that the lengths of filters (number of data) in real space are the same or substantially the same, and the weights (filter coefficients) for each data are the same or substantially the same. Etc.

  Specifically, when the nTapFIR filter shown in FIG. 8A is used for the original line data, three pieces of data are added to the densified data of the inserted frame as shown in FIG. The target 3Tap (tap) FIR filter is applied. In the nTapFIR filter shown in FIG. 8A, the length of the filter is n data, and the length in the real space corresponds to the three pieces of data (for example, R1 to R3) in FIG. 8C. Therefore, a 3TapFIR filter having a length corresponding to three pieces of original line data is applied to the densified data of the inserted frame shown in FIG.

  Further, for example, the coefficient of the top data of the nTapFIR filter (FIG. 8), the coefficient of the center data, and the coefficient of the final data are normalized as necessary, and the coefficient and center of the top data of the 3TapFIR filter (FIG. 9) are processed. Data coefficient and final data coefficient.

  The filter lengths and weights described above are one specific example, and the filter lengths and weights are not limited to the above specific examples. Moreover, it is good also as a structure which a user can adjust the length and weight of a filter.

  Next, a modification of the densification processing unit 20 will be described. The densification processing unit 20 may perform pattern matching based on the data after the filter processing.

  FIG. 10 is a diagram for explaining a modification of the processing in the densification processing unit 20. In the modification shown in FIG. 10, the densification processing unit 20 performs filter processing for noise removal or smoothing on the line data obtained from the transmission / reception unit 12 of FIG. 1 (S21). Thereby, noise that adversely affects pattern matching is removed.

  Subsequently, the densification processing unit 20 performs pattern matching processing by setting the template T and the window I in the frame data of the original frame composed of the line data from which noise has been removed (S22, see FIG. 3). ). Thereby, data constituting the insertion frame is selected.

  Then, the densification processing unit 20 increases the line data from the transmission / reception unit 12 corresponding to the position of the data selected in S22 in the frame data of the original frame composed of the line data obtained from the transmission / reception unit 12. Inserted as densified data, the frame data is densified (S23, see FIG. 5). The densified frame data is output to the digital scan converter (DSC) 30 in FIG.

  In the modification shown in FIG. 10, since the data constituting the insertion frame is selected by pattern matching in S22 based on the line data that has been subjected to the filter processing in S21, the deterioration of pattern matching accuracy due to noise is suppressed. it can. In S23, since the frame data is densified based on the line data obtained from the transmission / reception unit 12, that is, the original line data before the filtering process in S21, the densification is performed with respect to the original line data. Can be realized.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above is only a mere illustration in all the points, and does not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

  DESCRIPTION OF SYMBOLS 10 Probe, 12 Transmission / reception part, 20 Densification process part, 30 Digital scan converter (DSC), 40 Image formation part, 42 Display part, 50 Control part.

Claims (9)

A probe for transmitting and receiving ultrasound,
A transceiver for controlling the probe and scanning the ultrasonic beam;
A densification processing unit for densifying frame data of a plurality of frames obtained by scanning an ultrasonic beam;
An image forming unit that forms an ultrasonic image based on the densified frame data;
Have
The densification processing unit obtains data corresponding to the frames based on the data in each frame, thereby densifying the frame data of a plurality of frames in the frame direction.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The densification processing unit arranges a template corresponding to the frame direction in frame data of a plurality of frames, and moves the window in each frame to search for a window that matches the template, thereby matching the template. Based on the data in the window, data corresponding to the frames in the template is obtained.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 2,
The densification processing unit searches for a window that matches the template by pattern matching based on the data in the template and the data in the window.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 3.
The densification processing unit searches for a window that matches the template by pattern matching based on data in the template and data selected from within the window at a data interval in the template.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 2 to 4,
The densification processing unit inserts densified data based on data in a window that conforms to the template between a plurality of data arranged in the frame direction in the template.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 2 to 5,
The densification processing unit sets a window corresponding to the depth direction of the ultrasonic beam.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 2 to 6,
The densification processing unit sets a template and a window so that sizes in real space are equal to each other.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 2 to 7,
The densification processing unit arranges templates at a plurality of positions different from each other in the frame data of the original frame obtained by scanning the ultrasonic beam, and searches for a window that matches the template at each position. Get data corresponding to the frame at multiple locations where the template is placed.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 8,
The densification processing unit forms an insertion frame based on data corresponding to frames obtained at a plurality of positions where templates are arranged, and inserts the insertion frame between frames of the original frame, thereby Increase density,
An ultrasonic diagnostic apparatus.

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