JP2008073333A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform formation of a three-dimensional ultrasonic image at high speed by a comparatively simple technique. <P>SOLUTION: A ray setting part 22 sets a plurality of rays passing through a volume data space corresponding to a three-dimensional space. A computing section setting part 24 sets a computing section corresponding to a section on a ray where the ray permeating the volume data space enters an ultrasonic data space and leaves the same by each ray based upon a reference volume data indicating a space range of the ultrasonic data space in the volume data space. A voxel computing part 26 performs voxel computation taking a plurality of voxel data on the ray corresponding to the preset computing section as a computed object in each ray. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a technique for forming an ultrasonic image that three-dimensionally represents a target tissue.

  A volume rendering image is known as a three-dimensional ultrasonic image that three-dimensionally represents a target tissue and the like. The volume rendering image is formed as follows, for example.

  A plurality of rays (perspective lines) are set for a cubic volume data space including a plurality of voxel data obtained by transmitting and receiving ultrasonic waves, and a plurality of voxel data existing on each set ray are set. Predetermined voxel operations are sequentially performed on each of them, and the result of the voxel operation is calculated for each ray. Then, an image of a projection plane formed as a set of result values of voxel calculation regarding a plurality of rays becomes a volume rendering image.

  In an apparatus for forming a volume rendering image, a plurality of echo data are acquired three-dimensionally. That is, the ultrasonic beam is three-dimensionally scanned in the three-dimensional space including the target tissue, and a plurality of echo data are acquired from the three-dimensional scanning space. There are various shapes in the scanning space formed by three-dimensionally scanning the ultrasonic beam. For example, as shown in FIG. 13, a space (a) formed by scanning a sector type probe in a sector shape, a space (b) formed by scanning a convex type probe in a sector shape, linear There is a space (c) formed by scanning the pattern probe in a sector shape. A plurality of echo data actually acquired from the target tissue is in the scanning space of such various shapes.

  When a volume rendering image is formed, for example, a cubic or rectangular volume data space circumscribing the scanning space is set for the scanning space of various shapes, and interpolation processing is performed from a plurality of echo data in the scanning space. Thus, a plurality of voxel data in the volume data space is obtained. In this case, valid data reflecting the properties of the target tissue exists mainly in an area corresponding to the scanning space, and does not always exist throughout the entire volume data space.

  Against this background, several techniques have been proposed that attempt to shorten the calculation time by using effective data in the volume data space as the main calculation target. For example, Patent Document 1 discloses an image forming technique in which calculation is started from a position where each ray first intersects a frame in a scanning space. Patent Document 2 discloses a technique for detecting the surface of a target tissue and performing volume rendering calculation from the position of the surface.

JP 2005-328957 A Japanese Patent No. 3488771

  Under such circumstances, the inventor of the present application has studied an improved technique for image forming processing of a three-dimensional ultrasonic image.

  The present invention has been made in the course of the study, and an object thereof is to perform formation of a three-dimensional ultrasonic image at a high speed by a relatively simple method.

  In order to achieve the above object, an ultrasonic diagnostic apparatus according to a preferred aspect of the present invention scans an ultrasonic beam in a three-dimensional space including a target tissue, thereby scanning the ultrasonic beam. Transmitting and receiving means for acquiring a plurality of voxel data from, and image forming means for forming image data of an ultrasonic image representing the target tissue three-dimensionally based on the acquired plurality of voxel data, The image forming means shows a ray setting unit for setting a plurality of rays passing through the volume data space corresponding to the three-dimensional space, and a spatial range of the ultrasonic data space corresponding to the scanning space in the volume data space. Based on the reference data, for each ray, the interval on the ray from when the ray passing through the volume data space enters the ultrasound data space until it exits A calculation interval setting unit that sets a corresponding calculation interval, and a voxel calculation unit that executes a voxel calculation for a plurality of voxel data on a ray corresponding to the set calculation interval for each ray, The image data is formed from voxel calculation results obtained for each ray.

  In a preferred aspect, the calculation section setting unit forms calculation section data defining a start coordinate and an end coordinate of a section on the ray in a volume data space for each ray.

  In a preferred aspect, the calculation interval setting unit starts the search for the target ray based on the start coordinate and the end coordinate of the neighboring ray existing in the vicinity of the target ray when determining the start coordinate and the end coordinate for each of the plurality of rays. The coordinates are set, and the start and end coordinates of the target ray are searched from the search start coordinates.

  In a preferred aspect, the ray setting unit sets a plurality of rays starting from a virtual viewpoint and passing through the volume data space to reach a virtual projection plane, and the calculation interval setting unit is configured to include a plurality of rays. In determining the start coordinate and the end coordinate for each of the target rays, the target rays are sequentially selected from the rays on the center side of the projection surface to the rays on the end side of the projection surface, and selected. The start and end coordinates of the target ray are searched.

  According to the above aspect of the present invention, it is possible to form a three-dimensional ultrasonic image at a high speed by a relatively simple method.

  Hereinafter, preferred embodiments of the present invention will be described.

  FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a functional block diagram showing the overall configuration thereof.

  The 3D probe 10 includes a plurality of vibration elements (not shown), and scans an ultrasonic beam in a three-dimensional space including a target tissue. Thereby, a three-dimensional transmission / reception space 12 is formed.

  Here, the transmission / reception space 12 is a three-dimensional space defined by three coordinates of r, θ, and φ. For example, when the ultrasonic beam B is scanned in the θ direction, a scanning surface S is formed. When scanning in the φ direction (elevation direction), a three-dimensional transmission / reception space 12 is formed. The 3D probe 10 may be a combination of electronic scanning and mechanical scanning, but is preferably one that two-dimensionally electronically scans an ultrasonic beam. In the latter case, a known 2D array transducer is used.

  1 shows a space formed by scanning a convex probe in a sector shape (see FIG. 13B), the transmission / reception space 12 is, for example, a sector-type probe. Or a space formed by scanning a linear probe in a sector shape (see FIG. 13C), or the like.

  The transmission / reception unit 14 functions as a transmission beamformer and a reception beamformer. That is, the transmission / reception unit 14 forms a transmission beam by supplying a transmission signal corresponding to the vibration element to each vibration element included in the 3D probe 10 and also arranges reception signals obtained from the plurality of vibration elements. A phase addition process is performed to form a reception beam. As a result, a plurality of echo data is acquired from the transmission / reception space 12.

  The image forming block 20 executes image forming processing based on a plurality of echo data obtained from the transmission / reception space 12. In the present embodiment, a volume rendering image is formed as an ultrasonic image that three-dimensionally displays the target tissue. A well-known technique is used for forming the volume rendering image. For example, the technique described in Japanese Patent No. 2883584 is suitable. The outline of the processing is as follows.

  FIG. 2 is a diagram for explaining an image forming process of a volume rendering image. The volume data space (three-dimensional data space) 36 is a data space that is virtually constructed in the ultrasonic diagnostic apparatus, and is composed of voxel data of a plurality of voxels (unit solid regions) (not shown). The plurality of voxel data in the volume data space 36 is formed from a plurality of echo data in the transmission / reception wave space (reference numeral 12 in FIG. 1) by, for example, interpolation processing. The volume data space 36 has coordinate axes orthogonal to each other in X, Y, and Z, and voxel data exists at each coordinate in the volume data space 36.

  In volume rendering, a viewpoint VP is generally set outside the volume data space 36, and a screen 40 as a two-dimensional plane is virtually connected to the opposite side of the viewpoint VP via the volume data space 36. Is set. A plurality of rays (perspective lines) are defined on the basis of the viewpoint VP (only one ray 38 is shown as a representative in FIG. 2). The ray 38 penetrates the volume data space 36, and therefore, the ray 38 corresponds to a voxel data string composed of a plurality of voxel data. When a voxel operation based on the volume rendering method is sequentially executed for each voxel data from the viewpoint VP along the ray 38, a pixel value is determined as a result of the final voxel operation. The pixel value is mapped to the coordinate P corresponding to the ray 38 on the screen 40.

  The screen has Xsc and Ysc coordinate axes, and each coordinate is defined by Xsc and Ysc coordinates. A ray 38 is set for each coordinate, and a pixel value obtained for each ray 38 is mapped on the screen 40 as described above, whereby a three-dimensional image is formed on the screen 40. The plurality of rays 38 may be parallel to each other, but the plurality of rays 38 may be non-parallel to each other.

  In the volume rendering method, various types of calculation formulas for voxel calculation for each voxel data are known. Basically, in any arithmetic expression, opacity (opacity) is used as a parameter for each voxel calculation of each voxel data. Using such parameters, an output light amount (output value) is obtained for each voxel operation, and this is used as an input light amount (input value) in the next voxel operation. This is repeated, and the output light amount at the time when the calculation end condition is satisfied is converted into a pixel value. That is, it is based on a model in which light propagates through a medium while being scattered and attenuated. In the present embodiment, for example, the following expression is used as an arithmetic expression for voxel arithmetic.

  Of course, a formula other than Equation 1 may be used. The voxel calculation for each ray 38 is performed, for example, when the target coordinate exceeds the volume data space 36, or when the cumulative added value of opacity used in each voxel calculation exceeds a predetermined value (for example, 1). When the predetermined condition is satisfied, the process ends. Then, the output light amount at the end of the calculation is associated with the pixel value.

  Returning to FIG. 1, the image forming block 20 forms image data of a volume rendering image using the image forming process described above. Specific image forming processing by the image forming block 20 will be described in detail later.

  The display processing unit 30 forms a display image based on the image data obtained by the image forming process of the image forming block 20, and the formed display image is displayed on the display unit 32. Thus, the ultrasonic image (volume rendering image) formed by the image forming block 20 is displayed on the display unit 32.

  The control unit 35 is constituted by a CPU and an operation program therefor, and performs operation control of each component shown in FIG. An input unit 34 constituted by an operation panel or the like is connected to the control unit 35. The user can use the input unit 34 to perform various input operations such as mode selection and parameter specification. The user can also set the viewpoint in volume rendering to a desired position using the input unit 34.

  Next, the internal configuration of the image forming block 20 will be described. The image forming block 20 includes a ray setting unit 22, a calculation section setting unit 24, and a voxel calculation unit 26.

  The ray setting unit 22 sets a plurality of rays starting from a virtual viewpoint and passing through the volume data space to reach a virtual projection plane (screen) (see FIG. 2). For example, the user sets a viewpoint at a desired position via the input unit 34, and the ray setting unit 22 sets a plurality of rays according to the set viewpoint.

  The calculation section setting unit 24 sets a calculation section for each ray. The calculation section is a section on the ray from when each ray enters the ultrasonic data space corresponding to the transmission / reception wave space 12 until it exits. In setting the calculation section, the calculation section setting unit 24 uses reference volume data.

  FIG. 3 is an explanatory diagram of the reference volume data 50. The reference volume data 50 is data indicating the spatial range of the ultrasonic data space 12 ′ in the volume data space 36. The ultrasonic data space 12 ′ is a data space corresponding to the transmission / reception space (reference numeral 12 in FIG. 1).

  The plurality of voxel data in the volume data space 36 is formed from a plurality of echo data in the transmission / reception wave space (reference numeral 12 in FIG. 1) by, for example, interpolation processing. Therefore, the voxel data in the ultrasonic data space 12 ′ corresponding to the transmission / reception space is greatly affected by the echo data obtained by transmitting / receiving the ultrasonic wave, and is effective in forming image data. Treated as data. In contrast, voxel data that does not exist in the ultrasound data space 12 'has its voxel value set to, for example, zero.

  The reference volume data 50 is used to check whether or not a ray set so as to pass through the volume data space 36 crosses the ultrasonic data space 12 ′. When the ray crosses the ultrasonic data space 12 ′, the coordinates of the position where the ray enters the ultrasonic data space 12 ′ (start coordinates) and the coordinates of the position where the ray leaves the ultrasonic data space 12 ′ ( Used to obtain the end coordinates).

  Therefore, in the reference volume data 50, the voxel values of all the voxel data in the ultrasonic data space 12 ′ are set to, for example, the luminance value 255, and the voxel values of all other voxel data are set to, for example, the luminance value 0. ing.

  The calculation section setting unit (reference numeral 24 in FIG. 1) uses the reference volume data 50 to form ray mask data as calculation section data in which start coordinates and end coordinates are determined for each ray. Therefore, ray mask data will be described with reference to FIGS. As described with reference to FIG. 2, each ray 38 set based on the viewpoint VP reaches the coordinate P on the screen 40 after passing through the volume data space 36. Therefore, in the present embodiment, each of the plurality of rays 38 is managed by the coordinate system (Xsc-Ysc coordinate system) of the screen 40.

  FIG. 4 is a diagram for explaining the ray mask. FIG. 4 shows the screen 40 and its coordinate system (Xsc-Ysc coordinate system). A region 42 in the screen 40 indicates a range where a ray that does not pass through the ultrasonic data space (reference numeral 12 'in FIG. 3) reaches. That is, a plurality of rays corresponding to the coordinates (Xsc, Ysc) in the region 42 do not cross the ultrasonic data space.

  On the other hand, an area 44 in the screen 40 indicates a range where a ray passing through the ultrasonic data space reaches. That is, the plurality of rays corresponding to the coordinates (Xsc, Ysc) in the region 44 are rays that cross the ultrasonic data space. In the present embodiment, for a ray passing through the ultrasonic data space, the coordinates of the position where the ray enters the ultrasonic data space (calculation start point) and the coordinates of the position where the ray exits from the ultrasonic data space (calculation end point) are obtained. It is done.

  FIG. 5 is a diagram for explaining the calculation start point and calculation end point. FIG. 5 shows the volume data space when viewed along the Z-axis direction of the XYZ coordinate system (see FIGS. 2 and 3). 36, screen 40 and ray 38 are shown. A ray 38 shown in FIG. 5 passes through the ultrasonic data space 12 ′ in the volume data space 36 and reaches the screen 40. The calculation start point corresponds to the position where the ray 38 starting from the viewpoint VP enters the ultrasonic data space 12 ′. On the other hand, the calculation end point corresponds to the position where the ray 38 leaves the ultrasonic data space 12 '.

  In the present embodiment, the coordinates of the calculation start point and the calculation end point in the XYZ coordinate system are obtained using the reference volume data (reference numeral 50 in FIG. 3). In the reference volume data, the voxel data in the ultrasonic data space 12 ′ has a luminance value of 255, and the other voxel data is set to a luminance value of 0. Therefore, the luminance value of the voxel data is examined along the ray 38 set for the data volume 36 of the reference volume data, the position where the luminance value changes from 0 to 255 is detected, and the position is calculated as the calculation start point. And On the other hand, the luminance value of the voxel data is examined along the ray 38, the position where the luminance value 255 changes from the luminance value 255 is detected, and the position is set as the calculation end point. The brightness values inside and outside the ultrasonic space data space 12 ′ in the reference volume data may be set to values other than the above values as long as the inside and outside can be identified.

  Then, with respect to each of the plurality of rays 38, the calculation start point and the calculation end point are obtained, whereby ray mask data is formed.

  FIG. 6 is a diagram for explaining ray mask data. The ray mask data is managed in a screen coordinate system (Xsc-Ysc coordinate system) and stored in, for example, a memory. In the ray mask data, a calculation start point and a calculation end point are associated as data with a memory address specified by coordinates (Xsc, Ysc). Since a ray is designated by coordinates (Xsc, Ysc) on the screen, the address of the ray mask data functions as a ray address that designates a ray.

  Then, for each address, that is, for each ray, the coordinate value (Start X coordinate, Start Y coordinate, Start Z coordinate) of the calculation start point in the XYZ coordinate system (see FIGS. 2 and 3) of the volume data space, and the calculation end point Coordinate values (StopX coordinate, StopY coordinate, StopZ coordinate) are associated as data.

  The ray mask data is associated with data relating to all rays designated by coordinates (Xsc, Ysc) on the screen. However, for a ray that does not pass through the ultrasonic data space, that is, a ray that reaches the region 42 on the screen 40 shown in FIG. 4, for example, the coordinate value of the calculation start point and the coordinate value of the calculation end point are both 0. Is set.

  Thus, in the present embodiment, ray mask data indicating the coordinate values of the calculation start point and calculation end point for each of the plurality of rays is formed. At that time, the search start coordinates of the target ray are set based on the calculation start point and calculation end point of the neighboring ray existing in the vicinity of the target ray, and the coordinates of the calculation start point and calculation end point of the target ray are determined from the search start coordinates. Is searched. At that time, among the plurality of rays that reach the screen, the target ray is sequentially selected from the ray on the center side of the screen toward the ray on the end side of the screen, and the calculation start point and calculation end point for the selected target ray The coordinates of are searched.

  FIG. 7 is a diagram for explaining selection of a target ray according to the present embodiment. In FIG. 7A, the screen 40 is divided into four quadrants (I to IV), and the target ray is moved from the ray located at the center of the screen 40 toward the ray on the end side of the screen 40 for each quadrant. It shows how they are sequentially selected.

  For example, in the quadrant I, the ray located at the center of the screen 40 is selected as the first target ray, and the coordinates of the calculation start point and calculation end point of the target ray are obtained. Next, the target ray is shifted by one in the positive direction of the Xsc axis, and the coordinates of the calculation start point and calculation end point of the target ray are searched. Thereafter, the search is performed by sequentially shifting the target rays one by one in the positive direction of the Xsc axis. Thus, when the target rays are sequentially selected in the positive direction of the Xsc axis and the search for a plurality of rays arranged in a line along the Xsc axis is completed, the column is shifted by one row in the positive direction of the Ysc axis. , The target rays are sequentially selected in the positive direction of the Xsc axis. Then, by sequentially selecting the target rays while shifting the columns one by one in the positive direction of the Ysc axis, the target rays are selected in the entire area within the first quadrant.

  7A, the target rays are sequentially selected from the ray located at the center of the screen 40 toward the ray on the end side of the screen 40, respectively.

  On the other hand, FIG. 7B shows a state in which the target rays are sequentially selected in a spiral shape from the ray located at the center of the screen 40 toward the ray on the end side of the screen 40. As shown in FIG. 7B, the target rays may be sequentially selected in a spiral shape.

  In the present embodiment, in the process of selecting the target rays one after another, the search start point of the next ray is set based on the search result of the coordinates of the calculation start point and the calculation end point regarding the previous ray. The

  FIG. 8 is a diagram for explaining a search start point set on a ray. FIG. 8A shows a search start point on the current ray by subtracting a certain offset from the coordinates of the calculation start point of the previous ray (the target ray that was searched immediately before). A state is shown in which a search start point of the current ray is searched along the search direction from the search start point. Similarly, in FIG. 8A, a search start point is set on the current ray by subtracting a certain offset from the coordinates of the calculation end point of the previous ray, and from the search start point. A state of searching for the calculation end point of the current ray along the search direction is shown.

  On the other hand, in FIG. 8B, a search start point is set at a position on the current ray closest to the calculation start point of the previous ray, and the positive direction of the ray from the search start point (direction toward the screen). And the search is alternately performed in the negative direction of the ray and the direction of returning to the viewpoint.

  In general, the calculation start point for the previous ray, that is, the neighboring ray, and the calculation start point of the current ray are very likely to be close to each other. Therefore, as shown in FIG. 8, the search time is shortened by setting the search start point of the next ray based on the search result (calculation start point and calculation end point) regarding the previous ray. It becomes possible.

  Returning to FIG. 1, the calculation section setting unit 24 forms ray mask data as calculation section data in which start coordinates and end coordinates are determined for each ray by the method described with reference to FIGS. 4 to 8. .

  Then, the voxel calculation unit 26 calculates a plurality of voxel data on the ray corresponding to the set calculation interval (the interval from the calculation start point to the calculation end point) for each ray with reference to the ray mask data. As a target, voxel calculation is performed. Thus, an image formed on the screen as a set of voxel operation result values obtained for each ray is a volume rendering image.

  Next, the operation of the ultrasonic diagnostic apparatus in FIG. 1 will be described using a flowchart. In the following description, the reference numerals shown in FIG. 1 are used for the portions (configurations) shown in FIG.

  FIG. 9 is a flowchart for explaining image forming processing by the ultrasonic diagnostic apparatus shown in FIG. First, for example, when the apparatus is powered on, an apparatus initialization process is executed (S902). Next, the control unit 35 checks whether or not the apparatus is set to the 3D image mode (S904). If it is not set to the three-dimensional image mode, this flowchart is terminated, and for example, the change of the image mode is periodically confirmed. On the other hand, if the 3D image mode is set in step S904, the image forming block 20 creates reference volume data (see FIG. 3) (S906). A plurality of rays are set by the ray setting unit 22, and ray mask data is created by the calculation interval setting unit 24 (S908). The ray mask data creation process will be described in detail later with reference to FIG.

  When the ray mask data is created, the voxel computing unit 26 refers to the ray mask data, and for each ray, on the ray corresponding to the set computation interval (the interval from the computation start point to the computation end point). The voxel calculation (3D rendering process) is executed with the plurality of voxel data as the calculation target (S910). Thus, a volume rendering image is formed and displayed on the display unit 32 via the display processing unit 30.

  Then, it is confirmed whether or not the volume data space has been updated to the next time phase data (S912). If updated, the process returns to step S910 to perform the 3D rendering process for the next time phase volume data space. Executed.

  If the volume data space has not been updated to the next time phase data, the viewpoint change is confirmed (S914). If the viewpoint has been changed, the process returns to step S908, a plurality of rays are set according to the changed viewpoint, and ray mask data is created.

  If the viewpoint has not been changed, the change of the diagnostic range is confirmed (S916). If the diagnostic range has been changed, the process returns to step S906, and reference volume data is created according to the changed diagnostic range.

  If the diagnostic range has not been changed, for example, it is confirmed whether or not the user has performed the end operation of the three-dimensional image mode (S918). If the end operation of the three-dimensional image mode has not been performed, the process returns to step S912, and confirmations such as updating of volume data are sequentially performed. On the other hand, if the end operation of the three-dimensional image mode has been performed, this flowchart is ended, and for example, the change of the image mode is periodically confirmed.

  Next, ray mask data creation processing in step S908 of FIG. 9 will be described in detail.

  FIG. 10 is a flowchart for explaining ray mask data creation processing. First, normalization of the line-of-sight vector and initialization of ray mask data are performed (S1002). Thereby, for example, as a line-of-sight vector, a unit ray vector for sequentially obtaining coordinates to be calculated in each ray is obtained. In addition, all the data of the ray mask data (see FIG. 6) is initialized to zero.

  Next, elements (ΔX, ΔY, ΔZ) of each axis of the line-of-sight vector in the XYZ coordinate system (see FIG. 2) are calculated (S1004), and the screen coordinate value Ysc in the Xsc-Ysc coordinate system (see FIG. 2) is initially set. The value Ysc_start is set (S1006), and the coordinate value Xsc is set to the initial value Xsc_start (S1008).

  Then, the coordinates (Xs, Ys, Zs) of the point at which the ray passing through the screen coordinates (Xsc, Ysc) first intersects the ultrasonic data space (reference numeral 12 'in FIG. 3) are calculated (S1010), and the screen coordinates The coordinates (Xe, Ye, Ze) of the point where the ray passing through (Xsc, Ysc) finally intersects the ultrasonic data space are calculated (S1012). The processing in each step of S1010 and S1012 will be described in detail later using FIG. 11 and FIG.

  When the coordinates (Xs, Ys, Zs) and coordinates (Xe, Ye, Ze) of the intersection are obtained, the coordinates of these intersections are stored in the ray mask data (see FIG. 6) (S1014). That is, the coordinate values of the coordinates (Xs, Ys, Zs) are stored in the coordinate value of the calculation start point of the address (Xsc, Ysc) of the ray mask data, and the coordinate value of the calculation end point of the same address (Xsc, Ysc). Each coordinate value of the coordinates (Xe, Ye, Ze) is stored in.

  Next, Xstep is added to the screen coordinate value Xsc (S1016), thereby selecting a new target ray. Then, it is confirmed whether or not the screen coordinate value Xsc of the new target ray is the search end X coordinate Xsc_end (S1018). If it is not the search end X coordinate, the process returns to step S1010, and the processing from S1010 to S1014 is executed for the new target ray. In step S1016, Xstep is added to the screen coordinate value Xsc, and the next new target ray is selected. The

  Thus, new target rays are selected one after another, and when the screen coordinate value Xsc becomes the search end X coordinate Xsc_end in S1018, Ystep is added to the screen coordinate value Ysc (S1020), and the screen coordinate value Ysc is the search end Y coordinate Ysc_end. It is confirmed whether or not (S1022). If it is not the search end Y coordinate, the screen coordinate value Xsc is returned to the initial value in S1008, and the processing from S1010 to S1022 is executed.

  By repeatedly executing the processes from S1008 to S1022 according to the flowchart, rays are sequentially selected over the entire area of the screen coordinates, and ray mask data is created. Note that the method of sequentially selecting rays over the entire area of the screen coordinates may be, for example, the method described with reference to FIG.

  When rays are sequentially selected over the entire area of the screen coordinates, the screen coordinate value Ysc becomes the search end Y coordinate Ysc_end in step S1022, and this flowchart ends.

  Next, the calculation process of the coordinates (Xs, Ys, Zs) in step S1010 of FIG. 10 will be described in detail.

  FIG. 11 is a flowchart for explaining a calculation process of coordinates (Xs, Ys, Zs) which are calculation start coordinates. First, it is confirmed whether or not the search for the proximity ray has been completed (S1102). If the proximity ray search has not been completed, that is, in the case of the first ray, the process proceeds to step S1104, and the coordinates of the point where the ray first intersects with the volume data space (reference numeral 36 in FIG. 3) in the reference volume data. Is calculated and set to the search point Pc (Xc, Yc, Zc).

  Then, it is confirmed whether or not the search point Pc is a coordinate in the volume data space (S1114). If it is a coordinate in the volume data space, only one coordinate of the search point Pc is advanced on the ray (S1116). That is, the search point Pc is advanced by the line-of-sight vector calculated in S1004 of FIG. 10, and the coordinates of the search point are set to Pc (Xc + ΔX, Yc + ΔY, Zc + ΔZ).

  Next, it is confirmed whether or not the luminance value of the voxel data of the newly set search point Pc is 255 (S1118). That is, it is confirmed whether or not the search point Pc is in the ultrasonic data space (reference numeral 12 ′ in FIG. 3) in the reference volume data. If the brightness value of the search point Pc is not 255, the process returns to S1114, and when proceeding to S1116, only one coordinate of the search point Pc is advanced, and the brightness value is confirmed in S1118. When it is confirmed in S1118 that the luminance value is 255, the coordinates of the search point are set to the coordinates (Xs, Ys, Zs) that are the calculation start coordinates (S1120), and this flowchart is ended.

  If the ray does not intersect with the ultrasonic data space, the process always proceeds from step S1118 to step S1114, and when it is determined in step S1114 that the search point Pc has come out of the volume data space, this flowchart. Ends. In this case, the coordinates (Xs, Ys, Zs), which are the calculation start coordinates, remain at the initial value 0 set in S1002 of FIG.

  If it is determined in step S1102 that the proximity ray has been searched, that is, in the case of the second and subsequent rays, the coordinates (Xs, Ys, Zs) as the calculation start point of the proximity ray are The closest point Pc ′ (Xc ′, Yc ′, Zc ′) on the ray is calculated (S1106).

  Then, it is confirmed whether or not the coordinate values of the points Pc ′ are all 0 (S1108). If all the values are 0, the current ray is the first volume data space (reference numeral 36 in FIG. 3) in the reference volume data. The coordinates of the intersecting point are calculated and set to the search point Pc (Xc, Yc, Zc) (S1110). On the other hand, if it is determined in step S1108 that the coordinate values of the point Pc ′ are not all 0, that is, if at least one of Xc ′, Yc ′, and Zc ′ has a value other than 0, the point Pc The offset value is added to the coordinate value of ′ to set the search point Pc (S1112).

  Thus, when the search point Pc is set on the current ray in step S1110 or S1112, the steps after S1114 described above are executed, and the calculation start coordinates (Xs, Ys, Zs) relating to the current ray are set. Is done.

  Next, the calculation process of the coordinates (Xe, Ye, Ze) in step S1012 of FIG. 10 will be described in detail.

  FIG. 12 is a flowchart for explaining a calculation process of coordinates (Xe, Ye, Ze) which are calculation end coordinates. First, it is confirmed whether or not the coordinate values of the calculation start points related to the target ray are all 0 (S1202). If all the coordinate values of the calculation start point are 0, it is determined that the ray does not pass through the ultrasonic data space (reference numeral 12 'in FIG. 3), and this flowchart is ended. In this case, the coordinates (Xe, Ye, Ze) that are the calculation end coordinates remain at the initial value 0 set in S1002 of FIG.

  If it is determined in step S1202 that the coordinate values of the calculation start point for the target ray are not all 0, that is, if at least one of Xs, Ys, and Zs has a value other than 0, It is confirmed whether or not the ray search has been completed (S1204). If the proximity ray search has not been completed, the process proceeds to step S1206, and the coordinate value of the calculation start point is set to the search point Pc (Xc, Yc, Zc).

  On the other hand, if it is determined in step S1204 that the proximity ray search has been completed, the closest point Pc ′ () on the current ray to the coordinates (Xe, Ye, Ze) that is the calculation end point of the proximity ray. Xc ′, Yc ′, Zc ′) is calculated (S1208). Then, the search point Pc is set by adding the offset value to the coordinate value of the point Pc ′ (S1210).

  When the search point Pc is set in step S1206 or S1210, it is confirmed whether or not the search point Pc is a coordinate in the volume data space (S1212). Only one coordinate of Pc is advanced (S1214). That is, the search point Pc is advanced by the line-of-sight vector calculated in S1004 of FIG. 10, and the coordinates of the search point are set to Pc (Xc + ΔX, Yc + ΔY, Zc + ΔZ).

  Next, it is confirmed whether or not the brightness value of the newly set voxel data at the search point Pc is 0 (S1216). That is, it is confirmed whether or not the search point Pc has left the ultrasonic data space (reference numeral 12 ′ in FIG. 3) in the reference volume data. If the luminance value of the search point Pc is not 0, the process returns to S1212, and when proceeding to S1214, only one coordinate of the search point Pc is advanced, and the luminance value is confirmed in S1216. Then, when it is confirmed in S1216 that the luminance value is 0, the coordinates of the search point are set to the coordinates (Xe, Ye, Ze) which are the calculation end coordinates (S1218), and this flowchart ends.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above has the following effects, for example. In the present embodiment, since the voxel data in the ultrasonic data space corresponding to the transmission / reception space is a calculation target, the image forming process is performed as compared with the case where all the voxel data in the volume data space is the calculation target. Time can be shortened.

  Further, in the present embodiment, when the ray mask data is created, the search start point of the target ray is set with reference to the calculation result of the close ray, so compared with the case where the calculation result of the close ray is not referred to. Ray mask data creation time can be shortened.

  In addition, embodiment mentioned above and its effect are only illustrations in all the points, and do not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

1 is a functional block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. It is a figure for demonstrating the image formation process of a volume rendering image. It is explanatory drawing of reference volume data. It is a figure for demonstrating a ray mask. It is a figure for demonstrating a calculation start point and a calculation end point. It is a figure for demonstrating ray mask data. It is a figure for demonstrating selection of the object ray by this embodiment. It is a figure for demonstrating the search start point set on ray. 6 is a flowchart for explaining an image forming process of the present embodiment. It is a flowchart for demonstrating the production | generation process of ray mask data. It is a flowchart for demonstrating the calculation process of a calculation start coordinate. It is a flowchart for demonstrating the calculation process of a calculation end coordinate. It is a figure for demonstrating the scanning form of an ultrasonic beam.

Explanation of symbols

  20 image forming block, 22 ray setting unit, 24 calculation section setting unit, 26 voxel calculation unit.

Claims (4)

Wave transmitting / receiving means for acquiring a plurality of voxel data from within a scanning space in which the ultrasonic beam is scanned by scanning the ultrasonic beam in a three-dimensional space including the target tissue;
Image forming means for forming image data of an ultrasonic image representing the target tissue three-dimensionally based on the acquired plurality of voxel data;
Have
The image forming unit includes:
A ray setting unit for setting a plurality of rays passing through the volume data space corresponding to the three-dimensional space;
Based on the reference data indicating the spatial range of the ultrasonic data space corresponding to the scanning space in the volume data space, for each ray, the ray passing through the volume data space until entering the ultrasonic data space and exiting A calculation interval setting unit for setting a calculation interval corresponding to the interval on the ray;
For each ray, a voxel operation unit that performs a voxel operation on a plurality of voxel data on the ray corresponding to the set operation interval,
Including
Forming the image data from the result of the voxel operation obtained for each ray;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The calculation section setting unit forms calculation section data defining start coordinates and end coordinates of a section on the ray in the volume data space for each ray.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 2,
The calculation interval setting unit sets the search start coordinates of the target ray based on the start coordinates and end coordinates of the neighboring rays existing in the vicinity of the target ray when determining the start coordinates and the end coordinates for each of the plurality of rays. Search the start and end coordinates of the target ray from the search start coordinates.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 3.
The ray setting unit sets a plurality of rays starting from a virtual viewpoint and passing through the volume data space to reach a virtual projection plane;
The calculation interval setting unit determines a start coordinate and an end coordinate for each of a plurality of rays from a ray on the center side of the projection surface to a ray on the end side of the projection surface among the plurality of rays reaching the projection surface. To select the target ray sequentially and search for the start and end coordinates of the selected target ray.
An ultrasonic diagnostic apparatus.

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