JP2001327506A - Ultrasonic diagnostic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily form the tomographic image of a designated cross section within a three-dimensional space in an ultrasonic diagnostic system. SOLUTION: A table preparing part 38 prepares a transforming table to a transmission/reception coordinate system from a displaying coordinate system in accordance with the designated cross section. When a displaying address generator 36 generates displaying addresses in order, addresses on a 3D memory 22 are designated in order, interpolation processing is performed based on many pieces of read echo data and then, the tomographic image equivalent to the designated cross section is constructed on a frame memory 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to processing of three-dimensional echo data.

[0002]

2. Description of the Related Art Recently, an ultrasonic diagnostic apparatus for displaying a three-dimensional ultrasonic image has been put to practical use. In such a device,
The ultrasonic beam is electronically scanned to form a scanning surface, and the scanning surface is mechanically scanned to form a three-dimensional space as a space for capturing three-dimensional echo data. A sound image is formed. There is also a device that allows a user to specify an arbitrary cross section in a three-dimensional space and display a tomographic image (B-mode image) corresponding to the cut surface. U.S. Pat.
546,807 and JP-A-2000-239 disclose related techniques.

[0003]

However, in order to form a tomographic image corresponding to an arbitrary cross section by hardware, a very complicated configuration is required. On the other hand, the formation of a tomographic image can be processed by software, but in that case, a large amount of calculations must be performed each time complicated address conversion is performed, and there is a surface lacking in real-time property. In particular, in the case where the electronically-scanned array vibrator arranged in an arc is mechanically oscillated and scanned, the correspondence between the transmission / reception coordinate system and the display coordinate system becomes complicated. Further, when the apex of the electronic scanning is different from the apex of the mechanical scanning or when the freehand scanning is performed, the correspondence between the two coordinate systems becomes extremely complicated. Therefore, if the coordinate conversion is performed each time, the image cannot be displayed quickly.

Further, an interpolation operation is usually required due to the difference between the transmission / reception coordinate system and the display coordinate system, and the interpolation operation also needs to be performed quickly.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to rapidly form a tomographic image of a cross section using echo data in a three-dimensional space.

[0006]

(1) In order to achieve the above object, the present invention relates to a transmission / reception system which scans an ultrasonic beam in a three-dimensional space and takes in echo data specified by a transmission / reception wave coordinate system. Wave means, write control means for writing echo data captured by the wave transmitting and receiving means to an address in the three-dimensional echo data memory according to the wave transmitting and receiving coordinate system, and designating a position of a cross section with respect to the three-dimensional space. Specifying means for performing the display, a display address generating means for sequentially generating a display address on a display screen, and a conversion for converting the display address into a corresponding address on the transmission / reception wave coordinate system according to the position of the specified cross section. Table creating means for creating a table, and reading out the echo data specified by the corresponding address from the three-dimensional echo data memory And control means, characterized in that it comprises a tomographic image forming means for forming a tomographic image, a based on the read echo data.

According to the above configuration, when a cross section is manually or automatically designated, software processing (or hardware processing) for automatically creating a conversion table on a RAM, for example, is executed prior to image display. At the time of reading the echo data, each display address on the cross section is converted into a corresponding address (memory address) of the transmission / reception wave coordinates by the conversion table, and the echo data of the corresponding address is read from the three-dimensional echo data memory. Thus, a tomographic image is formed.

Although the three-dimensional space is basically a three-dimensional space, even if one axis is a time axis, the same processing as described above can be applied. The scanning of the ultrasonic beam is performed by electronic scanning, mechanical scanning, manual scanning, or a combination thereof. The position of the cross section is basically specified by the user, but may be automatically specified. Further, basically, a conversion table corresponding to the designated section is created prior to displaying the tomographic image, but a typical conversion table may be preset.

(2) To achieve the above object,
The present invention relates to a transmitting and receiving means for scanning an ultrasonic beam in a three-dimensional space and capturing echo data specified by a transmitting and receiving coordinate system, and the echo data captured by the transmitting and receiving means, the three-dimensional echo data Writing control means for writing to an address according to the transmission / reception coordinate system in a memory, designation means for designating a cross-sectional position with respect to the three-dimensional area,
A display address generating means for sequentially generating display addresses on a display screen, and a table for creating a conversion table for converting the display addresses to corresponding addresses on the transmission / reception wave coordinate system according to the position of the designated cross section Creating means, reading control means for reading a plurality of interpolation echo data specified by an integer part of the corresponding address from the three-dimensional echo data memory, and reading the plurality of interpolation echo data in accordance with a decimal part of the corresponding address. And a tomographic image forming means for forming a tomographic image based on the interpolated data.

According to the above configuration, a tomographic image can be formed while performing three-dimensional interpolation. Even in that case, there is an advantage that the echo data for interpolation can be easily specified.

(3) Desirably, the table creation means creates a plurality of conversion tables corresponding to a plurality of cross sections, and a table selection means for selecting a conversion table from the plurality of conversion tables is provided. Preferably, the table creating means creates a plurality of conversion tables corresponding to a plurality of sections arranged in a predetermined direction in the three-dimensional space. Preferably, the table creating means creates a plurality of conversion tables corresponding to a plurality of cross sections arranged around a predetermined axis in the three-dimensional space. Preferably, the table creation unit creates a plurality of conversion tables corresponding to a plurality of cross sections having different sizes in a predetermined plane in the three-dimensional space. These plurality of conversion tables can be easily created by changing parameters included in a calculation formula for creating the tables.

(4) In a desirable mode of the present invention, three-dimensional echo data obtained by repeating two-dimensional scanning or one-dimensional scanning for a certain time is temporarily stored in a memory. Each echo data is written in this memory in a transmission / reception wave coordinate system. Next, the echo data is read out and displayed according to the display coordinate system. That is, a pixel on the display screen is scanned, the coordinates of this pixel are converted into a transmission / reception coordinate system using a coordinate conversion table, and higher data of an address specified thereby is used as a memory address. Specifically, A plurality of echo data in the vicinity of the interpolation point used in the interpolation is specified by the upper data, and the plurality of echo data are weighted based on the lower data of the address. -Linear
Interpolation) to obtain interpolation data for each pixel on the cross section. It is desirable that the coordinate conversion table include address information for specifying a plurality of pieces of interpolation data.

As described above, by using the adaptively configured coordinate conversion table and performing the conversion from the display coordinate system to the transmission / reception coordinate system, a tomographic image of an arbitrary cross section can be reproduced relatively easily and at high speed. Can be configured. Further, by using the conversion table, it is possible to cope with any scan such as free hand scan.

Further, by creating a coordinate conversion table while changing parameters required for calculation of the conversion table, rotation about an arbitrary axis with respect to a designated section can be performed.
It can also be translated or scaled. Further, by having a plurality of conversion tables and continuously switching them to continuously display cross-sectional images, the images can be rotated or translated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

(1) Designation of cut plane FIG. 2 shows a transmission / reception coordinate system corresponding to a three-dimensional echo data acquisition space. The scanning surface 100 is, for example, a two-dimensional area configured by electronic scanning of an ultrasonic beam. Reference numeral 102 indicates the electronic scanning direction. Reference numeral 104 represents the mechanical scanning direction of the scanning surface 100. Of course, using a 2D array transducer, electronic scanning of the ultrasonic beam in the direction can be performed to acquire three-dimensional echo data, or manual scanning can be performed.

The origin O ₁ represents a vertex of electronic scanning, and the origin O ₂ represents a vertex of mechanical scanning. As shown, the two do not match. However, the present invention can also be applied to a case where the two match. In addition, the present invention can be applied to a case where a wave transmitting / receiving area having another three-dimensional shape is formed instead of forming a wave transmitting / receiving area having a pyramid shape as illustrated.

As shown in FIG. 3, the user designates a cut plane in the transmission / reception space (object space) by designating three points. Specifically, a plane including the three points is a designated cutting plane.

(2) Calculation of Pixel Coordinates on Cross Section FIG. 3 shows a cross section 104 designated by three points V0, Vx, and Vy in the transmission / reception space. here,
(x, y, z) is a target pixel (target voxel) on the cross section 104, the line address of the ultrasonic beam passing through the target pixel is indicated by L, and the plane address of the scanning plane including the target pixel is P. And the depth address of the pixel of interest is indicated by R.

Actually, three points are three vertices of a rectangle so as to match the screen shape to be displayed, and the sides V0Vx and V0Vy
Is desirably the adjacent side, so that is assumed. Here, the XYZ coordinates (= Cartesian coordinates) of V0, Vx, Vy

It is assumed that V0 = (V0x, V0y, V0z) Vx = (Vxx, Vxy, Vxz) Vy = (Vyx, Vyy, Vyz).

At this time, for example, a change amount vste in the XYZ direction when the pixel is moved by one pixel in the vertical direction of the cross section with reference to Vy.
px, vstepy, and vstepz are obtained as follows.

[0022]

## EQU2 ## vstepx = (V0x-Vyx) / (HEIGHT-1) vstepy = (V0y-Vyy) / (HEIGHT-1) vstepz = (V0z-Vyz) / (HEIGHT-1) Similarly, move 1 pixel in the horizontal direction Change amount h in XYZ direction
stepx, hstepy, hstepz are obtained as follows.

[0023]

Hstepx = (Vxx-V0x) / (WIDTH-1) hstepy = (Vxy-V0y) / (WIDTH-1) hstepz = (Vxz-V0z) / (WIDTH-1) where HEIGHT and WIDTH are cross sections Is the number of pixels in one direction and the other direction.

For the pixel of interest on the cross section 104, the coordinates (x, y, z) in the object space (transmit / receive wave space)
Is defined by the number of pixels in each direction from the cross-sectional reference point (Vyx, Vyy, Vyz) and the above-described variation. For example, the coordinates of each pixel on the cross section are calculated as follows.

[0025]

(4) for (j = 0; j <HEIGHT; j ++) {/ * vertical loop * / for (i = 0; i <WIDTH; i ++) {/ * horizontal loop * / x = Vyx + vstepx * j + hstepx * i; y = Vyy + vstepy * j + hstepy * i; z = Vyz + vstepz * j + hstepz * i;}} However, as described above, vstepx, vstepy, and vstepz are 1 pixel in the vertical direction of the section 104. Hstepx, hstepy, hstepz are the amounts of change in the XYZ direction when the image is moved 1 pixel in the horizontal direction of the cross section 104, and each is easily obtained from the coordinates of three vertexes of the cross section 104. Required.

(3) Preparation of Conversion Table For the target pixel, the plane address P, the line address L, and the sample address R are obtained as follows.

[0027]

(Equation 5) However, it is as follows.

(X, y, z): Display coordinates [v
oxel] Q: Vertical position on plane (scanning plane) [voxel] PlaneDensity: Plane density [plane / radian] RScaleFactor: Sample density [sample / voxel] LineDensity: Line density [line / radian] (Xms0, Yms0, Zms0 ): Display coordinates of mechanical scan vertex [voxel] (Xes0, Yes0, Zes0): Object space coordinates of electronic scan vertex [voxel] Poffset: Plane offset [plane] Qoffset: Q offset [voxel], Roffset: Sample offset [sample Loffset: Line offset [line] FIG. 4 shows a conceptual diagram of how to obtain P and Q. FIG.
And FIG.

As described above, for each pixel of the cross section specified in the transmission / reception wave space, the corresponding address on the transmission / reception wave coordinate system can be obtained. Therefore, if the above-described calculation is executed when the cross section is designated by the user, the conversion table can be created instantaneously. After the table is created, the display addresses are actually generated in order, the addresses on the transmission / reception coordinate system corresponding to each display address are output from the conversion table, and the echo data corresponding to the addresses are sequentially read from the 3D memory. It is. When an address for one frame is generated, one tomographic image is formed.

(4) Interpolation Of the addresses of the echo data obtained by the above conversion formula,
The integer part is used as a read address of the three-dimensional echo data memory, and interpolation is performed using a decimal part. An example of performing Tri-linear interpolation is shown below. Interpolation is Tri-line from eight neighboring points.
In addition to ar interpolation, spline interpolation or the like may be performed by increasing interpolation data. The tri-linear interpolation value v is obtained by the following equation.

[0031]

(Equation 6) However, it is as follows.

Pi: integer part of plane address, Pf: decimal part of plane address Li: integer part of line address, Lf: decimal part of line address Ri: integer part of sample address, Rf: decimal part of sample address v _{Pi , Li, Ri} : Address (Pi, Li, Ri) value (5) Section switching As an application, by changing the parameters used for coordinate transformation calculation and creating a coordinate transformation table, the section can be rotated about an arbitrary axis. It can be translated or scaled. In addition, by having a plurality of conversion tables, by continuously switching these to form a cross-sectional image, by rotating or translating the image,
It is also possible to provide a display that makes it easy to visually recognize a three-dimensional object.

When such a cross-section switching is performed, it is desirable to first prepare the following coordinate transformation matrix. That is, it represents an arbitrary cross section (vertex V0,
Vx, Vy)
Create a 3x3 transformation matrix Mrot that combines the following coordinate transformations.

Rotation about the X axis Rotation about the Y axis Rotation about the Z axis If a transformation matrix such as that above the rotation about the section normal (the line perpendicular to the section passing through the intersection of the diagonal lines of the section) is created. The coordinates of the vertices V0, Vx, Vy of the cross section are converted. The reference point is the intersection of the diagonal lines of the cross section. The coordinate conversion is performed in the following steps.

As an example, taking the coordinate transformation of V0 as an example, V0 = (V0x, V0y, V0
Translate z). Vc = (Vcx, Vx
y, Vcz), the coordinate V0 '= (V0'x, V0'y,
V0'z) is as follows.

V0′x = V0x−Vcx, V0′y = V0y−Vcy, V0′z = V0z−Vcz If the above conversion matrix is Mrot, the coordinates Vrot after the conversion
= (Vrotx, Vroty, Vrotz) is as follows.

Vrot = V0 '· Mrot Translate Vrot to the original position, and further move (Xt,
Yt, Zt) translates to final coordinates V0t = (V0tx, V0t
y, V0tz).

V0tx = Vrotx + Vcx + Xt, V0ty = Vroty + Vcy + Yt,
V0tz = Vrotz + Vcz + Zt Therefore, using these coordinates as a reference, a conversion table can be created according to the above principle.

Further, by fixing the plane address by coordinate conversion, it is easy to construct a conventional two-dimensional image, and one circuit can be used to share the creation of an arbitrary cross-sectional image of the conventional image. In addition, it is easy to create an M-mode image in an arbitrary direction by setting a capture plane address as a time axis address without scanning in the plane direction.

(6) Apparatus Configuration FIG. 1 shows a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration.

The 3D probe 10 is a so-called ultrasonic probe for acquiring three-dimensional echo data. 3D probe 10
Has a vibrator array 16 including a plurality of vibrating elements, and the vibrator array 16 is mechanically scanned by a scanning mechanism 14 which is a mechanical mechanism. The scanning position is detected by the scanning position detector 12. The scanning control unit 18 controls mechanical scanning, and the control is performed based on the scanning position detected by the scanning position detector 12. The scanning control unit 18 also controls electronic scanning, and specifically controls the formation of transmission / reception beams in the transceiver 20. The transceiver 20 is a circuit that supplies a transmission signal to the transducer array 16 and performs a predetermined process on a reception signal output from the transducer array 16. The transceiver 20 has a transmitting beam forming function and a receiving beam forming function. The received signals output from the plurality of vibrating elements are subjected to phasing and addition, and the received signals after the phasing and addition are stored in the 3D memory 22.

The writing control unit 24 controls the writing of the echo data on the 3D memory 22. Specifically, the writing control unit 24 writes the echo data into a memory address corresponding to a transmission / reception coordinate system for taking in the echo data. Control. Therefore, in the 3D memory 22, each echo data (voxel data) in the three-dimensional space shown in FIG. 2 or FIG. 3 described above is stored in association with the transmission / reception wave coordinate system.

The read control unit 26 has one or a plurality of conversion tables 28 in this embodiment, and the address signal output from the conversion table 28
Is output to Then, the echo data stored at the address specified by the integer part (upper bit) of the address on the 3D memory 22 is read and output to the interpolation unit 30 at the subsequent stage. In this embodiment,
The conversion table 2 is used for the interpolation processing in the interpolation unit 30.
8 or the other configuration or the operation of the 3D memory 22, the addresses of a plurality of voxels (eg, a plurality (8 or 16) existing in the vicinity of the pixel of interest) to be obtained by interpolation are specified. Echo data (interpolated data) specified by
Are output to the interpolation unit 30 simultaneously or sequentially.
The interpolation unit 30 executes, for example, three-dimensional linear interpolation, and outputs echo data of the pixel of interest, which is the interpolation result, to the frame memory 32. Here, a decimal part (lower-order bit) of the address data output from the conversion table 28 is used for weighting in the interpolation operation.

The display address generator 36 sequentially generates display addresses on the display screen in accordance with the raster scan. As a result, a plurality of display addresses in the interpolation relationship on the 3D memory 22 are displayed for each display address by the operation of the conversion table 28. Are designated, an interpolation operation is performed for each display address, and finally, echo data for one tomographic image is stored in the frame memory 32. Then, such image data is output to the display 34, and a tomographic image of the designated cross section is displayed on the display 34.

The table creation unit 38 creates the conversion table 28 based on the slice designation information output from the control unit 42 in order to form such a tomographic image of the designated slice. The table creation unit 38 is configured by software in the present embodiment, but may be configured by hardware. The conversion table 28 is constructed on a RAM in an actual device, and a display address output from the display address generator 36 is input to an address terminal of the RAM.

Here, the table creating section 38 is a table for performing conversion from the display coordinate system to the transmission / reception wave coordinate system based on the principle described above. Therefore, according to such a configuration, when the position of the cross section is designated, the conversion table is quickly configured in accordance with the designation, and as a result, a tomographic image corresponding to an arbitrary cross section can be quickly configured.

A plurality of conversion tables 28 may be provided on the read control unit 26, and one of them may be selected by the table selection unit 40, or the conversion tables may be sequentially selected. The conversion table 28 may be constructed on the ROM for a section that is frequently used, or such a conversion table may be automatically created when the apparatus is started up even if no section is designated.

The control section 42 controls the overall operation of the apparatus. In particular, it controls the table selection unit 40 and the table creation unit 38, outputs section designation information based on signals from a scanning unit (not shown), and performs control for table selection.

FIG. 6 shows a display example on the display unit 34. Reference numeral 200 denotes a plurality of tomographic images 201 to 2
This corresponds to guidance display for specifying the cross-sectional position of No. 03, and the position of each cross-section with respect to the three-dimensional space is conceptually represented as a schematic diagram. Incidentally, the direction of each cross section is conceptually indicated by a triangular mark displayed at one corner of each cross section. The image denoted by reference numeral 201 corresponds to a tomographic image of an X-Z section in this example, the tomographic image denoted by reference numeral 202 corresponds to a YZ section, and the tomographic image denoted by reference numeral 203 is an XY section. Is equivalent to Of course, the present invention is not limited to the case where such orthogonal cross sections are displayed simultaneously. In the present embodiment, it is also possible to arbitrarily specify the position of the cross section and display the other two orthogonal cross sections based on the position of the cross section. is there. Further, it is also possible to simultaneously display a plurality of tomographic images in which the position of the cross section is slightly shifted by using a plurality of image display areas, or to display each tomographic image in which the position of the cross section is rotated. . Further, it is also possible to dynamically express a tomographic image in accordance with the parallel movement and rotation of those cross sections.

In any case, according to the present embodiment, since the conversion table is formed in accordance with the designated cross section, a tomographic image of an arbitrary cross section can be easily formed without significantly increasing the amount of hardware. There is an advantage.

[0051]

As described above, according to the present invention,
It is possible to quickly form a tomographic image of a cross section using echo data in a three-dimensional space.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a diagram for explaining a transmission / reception wave coordinate system.

FIG. 3 is a diagram for explaining a relationship between a transmission / reception coordinate system and a designated cross section.

FIG. 4 is a conceptual diagram for explaining parameters P and Q.

FIG. 5 is a conceptual diagram for explaining parameters L and R.

FIG. 6 is a diagram showing a display example.

[Explanation of symbols]

10 3D probe, 12 scanning position detector, 14 scanning mechanism, 16 transducer array, 18 scanning controller, 20
Transceiver, 22 3D memory, 24 write controller, 26 read controller, 28 conversion table, 30
Interpolator, 32 frame memory, 34 display, 36
Display address generator, 38 table creation unit, 40 table selection unit, 42 control unit.

Continuing on the front page F-term (reference) 4C301 AA02 BB05 BB13 BB28 BB29 CC01 EE10 GB02 GB03 GB09 JB29 JC01 JC20 KK07 KK08 KK13 KK18 KK19 LL02 LL03 5B047 AA17 AB02 CA21 CB25 EA01 EB13 CA12 CB13 CA12 BA02CAB CH07 5C076 AA21 AA40 BA03 BA04 BA07 BB04 BB25

Claims (6)

[Claims] 1. A transmitting / receiving means for scanning an ultrasonic beam in a three-dimensional space to capture echo data specified in a transmitting / receiving coordinate system; Writing control means for writing to an address in the data memory according to the transmission / reception coordinate system; designation means for designating a position of a cross section in the three-dimensional space; display address generation for sequentially generating display addresses on a display screen Means, table creation means for creating a conversion table for converting the display address to a corresponding address on the transmission / reception wave coordinate system in accordance with the position of the designated section, and the correspondence from the three-dimensional echo data memory. Reading control means for reading the echo data specified by the address; An ultrasonic diagnostic apparatus comprising: a tomographic image forming unit that forms an image. 2. A transmitting and receiving means for scanning an ultrasonic beam in a three-dimensional space to capture echo data specified by a transmitting and receiving coordinate system, and a three-dimensional echo Writing control means for writing to an address in the data memory in accordance with the transmission / reception coordinate system; designation means for designating a cross-sectional position with respect to the three-dimensional area; display address generation for sequentially generating display addresses on a display screen Means, table creation means for creating a conversion table for converting the display address to a corresponding address on the transmission / reception wave coordinate system in accordance with the position of the designated section, and the correspondence from the three-dimensional echo data memory. Reading control means for reading a plurality of echo data for interpolation specified by an integer part of an address; An interpolation means for performing interpolation calculation on the plurality of echo data for interpolation to calculate interpolation data, and a tomographic image forming means for forming a tomographic image based on the interpolation data. Ultrasound diagnostic device. 3. The apparatus according to claim 1, wherein said table creating means creates a plurality of conversion tables corresponding to a plurality of cross sections, and selects a conversion table from among the plurality of conversion tables. An ultrasonic diagnostic apparatus characterized by comprising means. 4. The apparatus according to claim 3, wherein said table creating means creates a plurality of conversion tables corresponding to a plurality of sections arranged in a predetermined direction in said three-dimensional space. Diagnostic device. 5. The apparatus according to claim 3, wherein the table creating means creates a plurality of conversion tables corresponding to a plurality of cross sections arranged around a predetermined axis in the three-dimensional space. Ultrasound diagnostic equipment. 6. The apparatus according to claim 3, wherein said table creating means creates a plurality of conversion tables corresponding to a plurality of cross sections having different sizes in a predetermined plane in said three-dimensional space. An ultrasonic diagnostic apparatus characterized by the above-mentioned.