JPS62145374A - Restructuring device for interest cross section image - Google Patents

Abstract

PURPOSE:To obtain an image with high spatial resolution by finding the image of interest cross section with the aid of interpolation from plural pairs of parallel tomographic image groups. CONSTITUTION:At an image collection part, the first (the second) parallel tomographic image groups A1, A2,...An, An+1,..., AN, (B1, B2,...Bm, Bm+1,..., BM) parallel with a plane inclining with an angle of theta2 (theta1) in the body axis (x) direction of a body to be inspected are collected with a slice pitch (t), then being stored at a storage part 3. An interest cross section designation part 4 designates the interest cross section of the body to be inspected with a coordinate input, etc., and an interpolation processing part 5 interpolates and finds a picture element value on the interest cross section from the first and the second parallel cross section image groups. Therefore, when a picture element value P on an optional picture element position P(p, q, r) at the interest cross section C is found, four images An, An+1, Bm, and Bm+1 enclosing the picture element P(p, q, r) are used, and an interpolation process is performed based on coordinate values Sn, Sn+1, Sm, and Sm+1 at an intersection between perpendiculars from each of images and the picture element P(p, q, r). A display device 6 displays the image of the interest cross section C based on the picture element value on the interest cross section C found at the interpolation processing part 5.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a cross-sectional image of interest (oblique image) for obtaining a cross-sectional image of interest (oblique image) in a direction intersecting the slice pitch direction from a plurality of tomographic images collected with a predetermined slice pinch. The present invention relates to a reconstruction device.

[Technical background of the invention and its problems]

In X-ray CT devices, such as medical X-ray CT devices, there is a strong need to know the anatomical positional relationship of affected areas of patients, and recognizing three-dimensional objects three-dimensionally is especially important for doctors when dealing with surgical procedures. It is very useful, and various techniques have been developed in recent years.

Incidentally, scanning with an X-ray CT device is performed on an arbitrary plane of the patient, such as a plane perpendicular to the body axis, but the target cross section is usually unknown before the scan, and the cross section that cannot be physically scanned (e.g. In some cases, the cross-section is parallel to the body axis), so a plurality of appropriate cross-sections are scanned in advance, and the desired cross-section is obtained from the collected images through image processing.

At this time, conventionally, parallel sections were scanned at a predetermined slice pitch as shown in FIG. 6, and a plurality of XY plane images sliced in the Z direction were reconstructed as shown in FIG. Then, an arbitrary cross-sectional image is created from the plurality of X-Y plane images by image processing.

However, according to the above method, the spatial resolution is high in the X-Y plane but low in the Z direction, so the resolution of oblique images near the Z direction is low and only images with poor isotropy are produced as shown in Figure 8. I couldn't get it.

In addition, in recent years, it has become possible to scan a large number of consecutive slices with slices as thin as 1111, but it is still difficult to obtain a resolution of about 0.5 mm within the scan plane, and the scanning The number will increase.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reconstruction device for a cross-section image of interest that can reconstruct a cross-section image of interest having a spatially isotropic resolution. It is something.

[Summary of the Invention] The outline of the present invention for achieving the above object is to collect tomographic images parallel to a plurality of mutually intersecting planes of a subject at a predetermined slice pitch, and collect multiple sets of parallel tomographic images. an image acquisition unit that stores parallel tomographic images, a storage unit that stores parallel tomographic images, a cross-section designation unit that specifies an arbitrary cross-section of interest in the subject, and an image acquisition unit that stores parallel tomographic images; It is characterized by having an interpolation processing unit that interpolates the pixel value of a pixel from the pixel values on the plurality of tomographic images, and a display device that displays an image of the cross section of interest based on the pixel value determined by the interpolation. That is.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an apparatus for reconstructing a cross-sectional image of interest according to the present invention. In the figure, numeral 1 is a CPU that controls the device, and the following sections are connected to its path line.

Reference numeral 2 denotes an image collecting unit of, for example, an X-ray CT device, which collects tomographic images parallel to a plurality of mutually intersecting planes of the subject at a predetermined slice pitch, and collects multiple sets of parallel tomographic images. be. In this embodiment, as shown in FIG. 2, for example, a first parallel tomographic image group A 11 A 2 is parallel to a plane that is inclined at an angle θ2 in the body axis direction (X direction) of the subject.
,...A,,A,. ,...

AN and a second parallel tomographic image group B I+ B Z+...Bm+Bn+1+... parallel to the plane inclined at an angle θ1
, Bo are collected at a slice pitch of t.

3 is the first. This is a storage unit that stores a second group of parallel tomographic images.

Reference numeral 4 denotes a section of interest specifying section, which specifies an arbitrary section of interest of the subject by inputting coordinates or the like. In this embodiment, it is assumed that a cross section of interest parallel to the xy plane is specified.

5 is an interpolation processing unit, which first calculates the pixel values on the cross section of interest.
．． This is determined by interpolation from the second group of parallel cross-sectional images.

For this reason, when determining the pixel value P at an arbitrary pixel position P (p, q, r) on the cross section of interest C shown in FIG. Image A n +
Using An+++ Bm + B111+11, the coordinate values S, , S, at the intersection of each image and the perpendicular drawn from the pixel P (p, q, r). t+s+a+s□1
Interpolation processing is performed from Also, the coordinate value S
,,+Sn+++Sm+Sfi,I is not necessarily equal to each image AI'llA n+I+Aa+ + A□1
As shown in FIG. 5, for example, the coordinate value S may not match the pixel values Uz, i+ +01+1. to *Ut+*
*+, Ut. It is determined by interpolation from I+ l+, 1. Note that details of the above-mentioned interpolation processing will be described later.

Reference numeral 6 denotes a display device, which displays an image of the cross-section of interest C based on the pixel values on the cross-section of interest C obtained by the interpolation processing section 5.

The operation of the device configured as above will be explained.

In this embodiment, unlike the conventional apparatus, two sets of parallel tomographic images A+, .
・AN+BI+...B is collected by the image collecting section 2.

An example will be described in which the pixel value P of the pixel P (p, q, r) on the cross section C of interest is obtained by interpolation from two sets of parallel tomographic images.

Four tomographic images A surrounding pixel P (p + q + r)
71 HA h* HHB□, B,,. Let's focus on 1. The Z coordinate of the tomographic image B1 plane is: Z=tanθ, −x −m 0tanθ, −1. Tomographic image B. , the Z coordinate of the I plane can be found in the same way. Also, the Z coordinate of the tomographic image A1 plane is Z = -ta
n θ2−x+n9 tan θ2 °t.

Next, when we calculate the distance PS□ between the pixel P (p, q, r) and the coordinate Sm (x+y+z) on the tomographic image Affi, we also find that the X coordinate x at the coordinate S#l (x, y, z), .

yII and zI are respectively 1m3tan2θ, -t+rtanθ5+p 1ylI
= q. Therefore, the coordinate density So can be determined from this coordinate position as will be described later.

Similarly, yn=q can be found. And PS-+ and Sm++(Ly+2)
+PS,... and S nil (x+y+z) are calculated in the same manner as above.

Here, the coordinate concentrations s,,s,1. ．． ．． s,,s,. 1 is known, the pixel density P on the cross section C of interest can be more easily determined. That is, it is determined by an interpolation method that weights in proportion to the distance from the coordinates P (p, q, r) and averages them. In this way, pixel values are obtained for all pixels on the cross-section of interest C by the interpolation method described above, and based on this, the image of the cross-section of interest C can be reconstructed and displayed on the display device 6.

Here, the coordinate density S mentioned above. lsl'l. l +
Sll lS ff1(-1 does not necessarily mean tomographic image A,...
A. I r B@+B,. The density on one pixel is not limited. When viewed from the plane shown in FIG. 4, in most cases the density is at a position between adjacent pixels. In such a case, as shown in FIG. 5, for the coordinate value S1, the tomographic image B surrounding it, the pixel values of the four points above U l , w ,
Ut. 1. ,.

U1. −+ and U 1°1□1, the coordinate value S6 can be determined by interpolation by weighting according to the distance determined from the previously determined coordinate Ss (L3'+2). Coordinate value S n + S + H11 S1 + 1 + 1
can be found in the same way.

In this way, in this embodiment, the first. Since the pixel values on the section of interest C are determined by interpolation from the second group of parallel tomographic images, the spatial resolution is also improved in the slice pitch direction compared to the conventional method, which is determined by interpolation from a set of parallel tomographic images. It is possible to obtain a high-quality image, and to reconstruct an image with good isotropy for any cross section of interest.

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention. The intersection angle of parallel tomographic images that intersect with each other is preferably 90' for convenience of calculation, but is not limited to this. The degree of achievement of the effect decreases as the intersection angle approaches 0° or 1806 degrees.In addition, if the parallel tomographic image group is interpolated not only from two sets but from multiple parallel tomographic image groups with different inclination angles. , the spatial resolution can be further improved. In the above-mentioned embodiment, the cross-section of interest is parallel to the The embodiment is merely an example, and various known interpolation methods may be employed.

〔Effect of the invention〕

As explained above, according to the present invention, since the image of the cross section of interest is obtained by interpolation from multiple sets of parallel tomographic images, compared to the conventional case where interpolation processing is performed from one set of parallel tomographic images, An image with high spatial resolution can be obtained, and the above effects can be achieved without reducing the slice thickness.

Therefore, it is particularly useful when reconstructing an oblique image of a cross section parallel to the body axis rather than an X-ray CT image.

Furthermore, since industrial CT apparatuses do not have the problem of exposure to X-rays, they have a great effect in improving spatial resolution.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, FIG. 2 is a schematic explanatory diagram showing an example of an X-ray CT scan according to this embodiment, and FIG. 3 is a diagram showing the positional relationship between a cross section of interest and a parallel cross-sectional image. FIG. 4 is a diagram of a plane perpendicular to the Z axis passing through point P on the cross section of interest, an explanatory diagram showing the relationship between point P and each point on the cross section, and FIG. 5 is a diagram showing the relationship between point P and each point on the cross section. 6th explanatory diagram for explaining the method of determining the density value of arbitrary coordinates by interpolation from the pixel value of
The figure is a schematic explanatory diagram illustrating the collection of a group of parallel tomographic images by a conventional device, and FIG. 7 is a schematic explanatory diagram showing the group of parallel tomographic images,
FIG. 8 is a schematic illustration of an oblique image with poor isotropy. 2... Pixel collection unit, 3... Storage unit, 4... Cross section of interest designation unit, 5... Interpolation processing unit, 6... Display device. Agent Patent attorney Rule Ken Chika Yudo Dai Ko Noritake Mistake 1 Figure k k++ Figure 5

Claims (1)

[Claims] an image collecting unit that collects tomographic images parallel to a plurality of mutually intersecting planes of the subject at a predetermined slice pitch, and collects a plurality of parallel tomographic image groups; a storage unit that stores each parallel tomographic image group; a cross-section of interest designation unit that specifies an arbitrary cross-section of interest in the subject; and a cross-section of interest designation unit that specifies an arbitrary cross-section of interest in the subject, and interpolates the pixel value of a pixel on the cross-section of interest that exists between a plurality of mutually intersecting tomograms from the pixel values on the plurality of tomograms. What is claimed is: 1. An apparatus for reconstructing an image of a cross-section of interest, comprising: an interpolation processing unit that calculates pixel values obtained by interpolation; and a display device that displays an image of the cross-section of interest based on the pixel values obtained by interpolation.