JP2774512B2 - Image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an X-ray computer tomography apparatus (hereinafter referred to as an X-ray CT apparatus) and a nuclear magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus). More particularly, the present invention relates to a three-dimensional image display device capable of displaying three-dimensional information on an image display device that displays the imaged content of an imaging device on a display screen.

(Prior art) In recent years, a number of imaging apparatuses, such as X-ray CT apparatuses and MRI apparatuses, which display various biological structures using various physical phenomena and provide the images to medical diagnosis, have been developed. A three-dimensional image display method capable of providing three-dimensional information at the time of display is particularly effective for medical diagnosis because a biological structure can be easily grasped.

However, since image display is performed on a two-dimensional display screen, some contrivance is required for displaying three-dimensional information in the three-dimensional image display method. For this reason, a cross-section conversion display in which a two-dimensional tomographic image is displayed while being sequentially converted, a surface display in which only the surface of a living body is three-dimensionally described, and a three-dimensional grid in order to easily grasp a three-dimensional position. There are methods such as wire-frame display for displaying and re-projection method for displaying a projected image in one direction of a three-dimensional image composed of multiple tomographic images. Useful for displaying.

(Problems to be Solved by the Invention) However, in the reprojection method, it is impossible to grasp the three-dimensional internal structure only by displaying one projected image, and therefore, the direction of the projection plane is sequentially converted to display a moving image or a plurality of moving images are displayed. A complicated display method such as displaying a projection image as a developed view is required.

Also, since the projection image in the reprojection method is created by integrating a stereoscopic image composed of a plurality of tomographic images in the direction of the projection plane, the region of interest is, for example, inside the brain and surrounded by the skull. In such a case, it is necessary to take complicated measures such as removing these images in advance in order to prevent the images of the skull from being integrated together.

The present invention has been made in view of the above circumstances, and performs display of a three-dimensional internal structure of a subject by a reprojection method without performing conventionally required measures such as moving image display, developed view display, and obstacle removal. It is an object of the present invention to provide an image display device capable of performing such operations.

[Constitution of the Invention] (Means for Solving the Problems) In order to solve the problems, the present invention provides a projection image of three-dimensional image data composed of a plurality of tomographic images of a subject in an appropriately selected viewing direction. An image display device for three-dimensionally displaying a subject on a screen based on an area designation means for designating an arbitrary area with respect to the three-dimensional image data; A projection image generating means for enhancing the image data and generating the projection image according to the result.

(Operation) In the present invention, an image in which an arbitrary three-dimensional region is emphasized in the projection image in the selected line-of-sight direction can be obtained by the above-described configuration. The three-dimensional internal structure of the subject is displayed.

Embodiment FIG. 1 is a block diagram of an embodiment of an image display device to which the present invention is applied.

In this embodiment, a tomographic image storage unit 1 for accumulating tomographic image data, a projected image creating unit 2 for creating a projected image by a reprojection method based on these tomographic images, Instruction input unit 3 for inputting the line of sight direction and the emphasis area, and a projection image storage unit 4 for storing the created projection image
And a display unit 5 for displaying the stored projected image as an image.

In this embodiment having such a configuration, tomographic image data captured by an imaging device such as an X-ray CT device or an MRI device is input to the tomographic image storage unit 1. This input is performed online by directly connecting the imaging device and the tomographic image storage unit 1 or by reading data stored in storage means such as a magnetic tape or a magnetic disk.

Next, based on the tomographic image data, a projection image is created by a reprojection method in the projection image creation unit 2. Here, an instruction from the instruction input unit 3 for selecting a gaze direction and an emphasis area is used. You.

First, the gaze direction will be described. FIG. 2 shows the relationship between the projection plane and the tomographic image in the reprojection method. As shown, the projection plane is a plane perpendicular to the line of sight. Where the coordinate system (x, y,
v) is a rectangular coordinate system in which v is set as a line-of-sight direction, and x and y are set as coordinates on a projection plane, and a coordinate system (x ′,
y ′, z ′) is an orthogonal coordinate system which is arbitrarily set with the imaging direction of the tomographic image as z ′ and is used for storing tomographic image data.

The projected image adds and sums the signal values at each signal sampling point arbitrarily set on each line of sight starting from the pixel on the projection plane along this line, and uses this as the signal value of the pixel on the projection plane. create. Here, the signal value at each signal sampling point arbitrarily set on the line of sight is obtained as follows. The signal value at the signal sampling point a as shown in FIG. 3 is the signal value (b ₁ , b ₂ , b ₃ , b ₄ ,
c ₁ , c ₂ , c ₃ , c ₄ ) and distances (d ₁ ,
_{d 2, d 3, d 4} , from d _5, d ₆₎ Interpolated as follows. Up to this point, it is the same as the conventional reprojection method.

Next, for the emphasis area, emphasis parameters Kx (x), Ky (y) and Kv (v) are set in each direction of the coordinate system (x, y, v), and these are added on each line of sight described above. It is specified by using the coefficient related to the signal value of each signal sampling point at the time of totaling.
That is, the signal value F of the pixel located at (x, y, o) on the projection plane is Given by Here, P (x, y, v) is the signal value at the point (x, y, v) obtained from equation (1), and n is the total number of signal sampling points on each line of sight, where n≫1.

For example, in order to obtain a spherical emphasized area centered on the point (X, Y, V) as shown in FIG. 4 (d), the coordinates shown in FIGS. 4 (a), (b) and (c) The emphasis parameters as shown in are set. Where the enhancement parameters are X, Y, and V, respectively.
Since the value is almost 0 except for the vicinity of, the signal value at a point other than the spherical emphasized area hardly contributes to the signal value of the pixel on the projection plane according to the equation (2). Therefore the fourth
A circular projected image as shown in FIG. 3D is an image reflecting only the signal in the emphasized area.

Further, in order to obtain a slice-like emphasized area at the coordinate V in the v direction as shown in FIG. 5 (d), each coordinate must be emphasized as shown in FIG. 5 (a), (b) and (c). Set parameters. Here, the emphasis parameters in the x and y directions are constant values over the entire range, but the emphasis parameter in the v direction is 0 outside the vicinity of V. Therefore, the signal value at a point other than the slice-shaped emphasis area is expressed by the equation ( No contribution is made to the signal value of the pixel on the projection plane according to 2). Therefore the fourth
A projected image of a square as shown in FIG. 3D is an image reflecting only the signal in the emphasized area. That is, in this case, v
This is equivalent to displaying a tomographic image at the coordinate V in the direction.

The projection image created by the projection image creation unit 2 as described above is stored in the projection image storage unit 4 and displayed on the display screen of the display unit 5 as an image.

The above is the basic operation of this embodiment. To obtain three-dimensional information from this and utilize it as a three-dimensional image display device, the emphasis parameters set in the instruction input unit 3 are sequentially changed to sequentially move the emphasis area. Let it. This allows
A three-dimensional structure can be grasped by sequentially observing three-dimensionally different regions. Here, such a conversion of the emphasis parameter is performed by inputting the center Mx, My, Mz of the emphasis parameter for each direction and the emphasis range Wx, Wy, Wz into the instruction input unit 3 as shown in FIG. 6, for example. This is performed by providing an instruction dial and operating these appropriately. By doing so, the Mx, My, and Mz can be arbitrarily selected from the entire range in each direction, and the Wx, Wy, and Wz can be freely changed from one-point enhancement to the entire range uniformly. It is possible to appropriately respond to the position and shape of.

In this embodiment, the emphasis area is defined by a coordinate system (x, y, v).
Is specified using the coordinate system (x ', y',
It is also possible to use z ').

The emphasis parameter may be a pattern other than the normal curve as shown in FIG.
It is also possible to select as appropriate.

In addition, various modifications can be made without departing from the gist of the present invention, such as the interpolation method using the above equation (1) and the mode of the emphasis parameter setting operation.

[Effects of the Invention] As described above, in the image display device to which the present invention is applied, an image in which an arbitrary region of the projected image by the reprojection method is enhanced can be obtained. The three-dimensional internal structure of the subject can be observed. This eliminates the need for conventional measures such as moving image display, development view display, and obstacle removal, and makes it easier to grasp the three-dimensional position and shape than before, which is more effective for medical diagnosis.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS.
FIG. 4, FIG. 5, FIG. 5 and FIG. 6 are diagrams for explaining the configuration and function of each part of the embodiment. DESCRIPTION OF SYMBOLS 1 ... Tomographic image storage part, 2 ... Projection image creation part 3 ... Instruction input part, 4 ... Projection image storage part 5 ... Display part

Claims (3)

(57) [Claims] An image display apparatus for displaying a subject in a three-dimensional manner on a screen based on a projection image of a three-dimensional image data composed of a plurality of tomographic images of the subject in an appropriately selected direction of sight. Area designating means for designating an arbitrary area with respect to the three-dimensional image data; and a projection image generating means for enhancing the three-dimensional image data with respect to the area designated by the area designating means, and generating the projection image according to the result. And an image display device. 2. The image display apparatus according to claim 1, wherein said area designating means designates an area by setting an arbitrary enhancement coefficient in each coordinate axis direction. 3. The image display apparatus according to claim 2, wherein said area specifying means can set a center coordinate and an emphasis range of emphasis independently in respective coordinate axis directions.