JPS6336774B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray tomographic imaging device that obtains a tomographic image from a pair of X-ray photographs that can be observed as a three-dimensional image.

Conventionally, there is a method called stereoscopic X-ray photograph analysis for analyzing X-ray photographs of patients in hospitals, for example. This method uses a pair of
A pair of X-ray photographs can be obtained using an X-ray tomography device, etc., and can be observed as a three-dimensional image by observing the pair of X-ray photographs with each eye using a stereoscope as shown in Figure 1. This is the method used. In this case, the pair of X-ray photographs described above is also referred to as a stereoscopic X-ray photograph.

FIG. 1 shows an example of a reflecting stereoscopic mirror, in which 1 and 2 are a pair of X-ray photographs, 3 and 4 are reflecting mirrors, 5 and 6 are right-angle prisms, and 7 and 8 are lenses.

On the other hand, conventionally, in order to obtain an X-ray tomogram (not a stereoscopic photograph), a tomography apparatus based on the principle configuration as shown in FIG. 2 has been used.

That is, in FIG. 2, the cross section T ₁ of the subject P
- When trying to image T ₂ , centering on a point O on the imaging cross-section, the X-ray tube 9 and the imaging cross-section T ₁ - T ₂
and a film 10 arranged parallel to each other are placed facing each other with the subject P in between, and are moved in opposite directions while irradiating X-rays while keeping the image magnification approximately constant. Get a photo. This X-ray photograph (film 10) is an X-ray tomographic image with T ₁ - _{T 2} as a cross section.

In short, conventional stereoscopic X-ray photograph analysis is a narrow field that only involves stereoscopic vision, and in conventional tomography, the burden on the examinee and operator required to obtain a single tomogram is large; The amount of X-rays they were exposed to was also quite large.

The present invention was made based on such circumstances, and makes it possible to draw an X-ray tomographic image of an arbitrary cross section based on a pair of X-ray images.
The present invention aims to expand the field of stereoscopic X-ray image analysis and to provide an X-ray tomographic imaging device that can easily obtain X-ray tomographic images.

That is, the present invention is characterized by an image input means for inputting a pair of stereoscopic X-ray image information given a parallax so that it can be observed as a stereoscopic image by observing each one with the left and right eyes separately and simultaneously. , a tomographic plane setting means for inputting required tomographic plane position information within the three-dimensional region of the stereoscopic image input by the image input means, and a common part between the pair of screens to obtain the tomographic image. a deviation setting means for setting an allowable gradation deviation for recognizing the image; and a deviation setting means for setting an amount of positional deviation (parallax) between the pair of stereoscopic X-ray images according to the tomographic plane set by the step plane setting means. At the same time, when the gradation difference between the two screens at the point corresponding to the positional deviation amount is within the deviation set by the deviation setting means, approximately that gradation is given to the corresponding point on the tomographic plane. The object of the present invention is to include an image processing means for obtaining X-ray image information on the tomographic plane, and a display means for displaying the image information obtained by the image processing means.

First, the principle of the present invention will be explained.

As shown in Figure 3, the position
X-rays are emitted at X ₁ and X ₂ (focal position), respectively.
A film placed on the opposite side of the subject P
F ₁ and F ₂ are respectively photos P ₁ and F 2 as shown in Figure 4 a and b.
A pair of radiographs such as photo P ₂ are obtained.

As is clear from FIGS. 3 and 4, point A on the body surface of the subject and points B and C within the subject are:
In the photo, they are moving from A ₁ to A ₂ , B ₁ to B ₂ , and C ₁ to C ₂ , but the amounts of movement are different. In other words, the difference in the cross-sectional position of the object (difference in the distance ratio between the X-ray tube and the film) is expressed as a difference in the amount of positional movement on the photograph, and this causes the pair of X-ray photographs P ₁ , P ₂ and can be observed as a 3D image.

Therefore, in the above-mentioned pair of X-ray photographs, it is possible to compare the corresponding densities of all points with a certain amount of positional movement, and construct an image by leaving only the points that match the same densities. For example, X of a certain cross section
It becomes possible to obtain a line tomographic image.

Here, a pair of X-ray photographs (stereoscopic X-ray
Let us explain that in a three-dimensional image that can be observed using a pair of X-ray photographs), the amount of movement of points on the same tomographic plane (hereinafter referred to as "parallax") all have the same value.

In Fig. 5, the point on the body surface of the subject is designated as A, and this is the reference point for determining the cross-sectional position (hereinafter referred to as
It is called a "control point." ), consider points B and C, which are points on the same cross section within the subject, and points A, B, and C on the left and right photographs are a ₁ , b ₁ , c ₁ , and a ₂ , respectively.
Suppose the image is taken at b ₂ and c ₂ positions. Now on the diagram
Shift c ₂ a ₂ to the right and overlap a ₂ with a ₁ to make ₂ ′ ₂ ′,
Similarly, a ₂ of _{2 2} is superimposed on a ₁ to form ₂ ′ ₂ ′. In this case, △X ₁ BC∽△X ₁ b ₁ c ₁ , so becomes.

Here, D ₁ and D ₂ are the distances from the X-ray tube focal points X ₁ and X ₂ and the films F ₁ and F ₂ to the cross section including points B and C in stereoscopic X-ray photography, respectively, as shown in the figure.

Also, since △X ₂ BC∽△X ₂ b ₂ c ₂ becomes.

Therefore, Therefore, _{1 1} = _{2 2 1 2} ′= _{1 2} ′+ ₂ ′ ₂ ′ = _{1 2} ′+ _{2 2} = _{1 2} ′+ _{1 1} = _{1 2} ′ Therefore, the parallax of point B and the parallax of point C are equal. That is, in a pair of X-ray photographs obtained by stereoscopic X-ray photography, the parallaxes of points on the same cross section all have the same value.

Next, the parallax of each point within the object is D _e , D ₁ , D ₂ ,
Let me explain what can be determined by D ₃ and D ₄ .

Here, D _e is the moving distance of the focal point of the X-ray tube for stereoscopic X-ray photography, and D ₃ and D ₄ are the points from the X-ray tube focal points X ₁ and X ₂ and the films F ₁ and F ₂ , respectively, as shown in the figure. This is the distance to the plane parallel to the fault plane containing A.

In △BX ₁ X ₂ and △Bb ₁ b ₂ Therefore, _{1 2} = D ₂ /D ₁ D _e △AX ₁ X ₂ and △Aa ₁ a ₂ Therefore, _{1 2} = D ₄ /D ₃ D _e Therefore, the parallax of point B with point A as the control point is _{1 2} ′ = _{1 2} − _{2 2} ′ = _{1 2} − ( _{2 2} + _{2 2} ′) = _{1 2} − ( ₂ ′ ₂ ′ + _{2 2} ′) = _{1 2} − _{2 2} ′ = _{1 2} − _{1 2} = D ₂ /D ₁ D _e −D ₄ /D ₃ D _e =D ₂ /D ₁ −D ₄ /D ₃ D _e =K (1) Therefore, once the cross-sectional position of the required cross-sectional image is determined, the parallax is uniquely determined using the position of the control point A. This indicates that K is a constant value.

One embodiment of the present invention based on this principle is constructed as shown in FIG.

In the figure, 11 is an input device for inputting parameters such as cross-sectional position and density comparison deviation for data processing, 12 is an optical system used to take a pair of X-ray photographs, and 13 is an optical system 12.
14 is an image pickup tube control device that controls the image pickup tube 13; 15 is a VTR (VTR) that records an image signal captured by the image pickup tube 13 and obtained via the image pickup tube control device 14; video tape
16 is a central processing control unit (hereinafter referred to as "CPU") using, for example, a minicomputer, which processes images by predetermined arithmetic control.
It is called. ), 17 is a storage device such as a magnetic tape recording device connected to the CPU 16, and 18 is a CRT.
A display device such as a cathode ray tube (cathode ray tube) 19 is an interface for exchanging signals and data between the CPU 16 and the input device 11, the image pickup tube control device 14, the VTR 15, the display device 18, and the like.

Next, the operation of the above configuration will be described.

Two parameters, cross-sectional position and density comparison deviation, for data processing are input from the input device 11 to the CPU 16 via the interface 14.
Generally, a so-called video signal consists of a synchronization signal and a video signal portion, and the synchronization signal is separated to form the base point of the digital address of the video. The video signal portion is sampled at the digital address, and then A/D (analog-digital) converted into a digital image, which is then stored in the storage device 1 by the CPU 16 along with the digital address.
7. The stored data is processed by a data processing method to be described later and displayed on a cathode ray tube of the display device 18 or on a film by a so-called digital imager.
After inputting the above parameters, the first one of the pair of X-ray photographs is set on a predetermined photographic stand and an image optical signal S ₁ is sent to the imaging tube 13 via the optical system 12 .
The image pickup tube control device 1 receives input from the input device 11.
Scanning start signal for 4 and VTR15
S ₂ is given. Through this scanning, the video signal _S3 output from the image pickup tube control device 14 is transmitted to the VTR.
Recorded on 15th. The video signal recorded on the VTR 15 is converted into a digital image by the interface 19 and the CPU 16 according to a command from the input device 11, and is recorded in the storage device 17. After the first X-ray photograph is recorded on a magnetic tape or the like in this manner, the second X-ray photograph is then set on the photo stand and recorded on the magnetic tape or the like in the same manner as described above.

In addition, in order to process these two X-ray photographs, there must be a control point whose location is known in advance, and a light pen (not shown) can be used to correspond to common areas on each photograph. Record the address using the image position as a reference point. The digital image is sent to the CPU according to instructions from the input device 11.
The data is processed in 16, and a tomographic image is displayed on a display device 18 based on the processing result.

Next, a data processing method for creating a tomographic image will be explained. The parallax between a pair of X-ray photographs with point A as the reference point is determined as in the above-mentioned equation (1). Now, if the pair of X-ray photographs in Fig. 4 are superimposed with _A1 and _A2 aligned, the result will be as shown in Fig. 7. If point B and point C are on the same cross section, the parallaxes K ₁ and K ₂ are the same, respectively, and K ₁ = K ₂ = K
becomes.

Therefore, when trying to obtain a tomographic image of a certain cross section, each point of one photograph in FIG.
Points B ₂ and C ₂ of the other photograph, which are separated by a certain parallax from points B ₁ and C _1, are found, and the density of each point is compared to ensure that the density is within the certain density deviation input to the input device 11. The position and density of the object are displayed faithfully on the screen of the display device 18, and the tomographic image to be obtained is created when this process is completed for all pixels of the pair of X-ray photographs.

In addition, in the above, all cross-sections or tomographic planes were explained as being perpendicular to the depth direction of the field of view of a stereoscopic Basically, it is the same as above, only that the parallax at the point changes continuously at a constant rate depending on the position, so if you find the parallax at each point according to the cross-sectional position and angle, you can obtain the image of such a cross-section. It is also possible to obtain

In addition, it is not limited to images from a pair of X-ray photographs (stereoscopic X-ray photographs) obtained from a tomographic imaging device, but also stereoscopic X-ray television video signals when configured as a stereoscopic X-ray television apparatus, etc., as described above. The same processing as described above is possible for any stereoscopic X-ray image information.

In addition, the present invention can be implemented with various modifications without changing the gist thereof.

As described in detail above, according to the present invention, it is possible to obtain an X-ray tomographic image of an arbitrary cross section in the three-dimensional space represented by the stereoscopic images based on a pair of X-ray images. It is possible to provide an X-ray tomographic imaging device that expands the field of ray image analysis and can easily obtain X-ray tomographic images.

[Brief explanation of the drawing]

Figure 1 shows an example of a reflective stereoscope for viewing stereoscopic X-ray photographs with the naked eye, and Figure 2 shows a conventional X-ray stereoscope.
A diagram for explaining the imaging principle of a line tomography device,
3 to 5 are diagrams for explaining the principle of creating a tomographic image according to the present invention, FIG. 6 is a block diagram showing an embodiment of the tomographic imaging apparatus according to the present invention, and FIG. FIG. 7 is a diagram for explaining the drawing process in more detail. 11...Input device, 12...Optical system, 13...
Image pickup tube, 14... Image pickup tube control device, 15...
VTR, 16...Central control unit, 17...Storage device, 18...Display device, 19...Interface.

Claims (1)

[Claims] 1. An image input means for inputting a pair of three-dimensional X-ray image information given parallax so that it can be observed as a three-dimensional image by observing each one separately and simultaneously with the left and right eyes, and the image input by this image input means. a tomographic plane setting means for inputting required tomographic plane position information within a three-dimensional area of a stereoscopic image; and a tomographic plane setting unit for inputting required tomographic plane position information in a three-dimensional area of a stereoscopic image, and a gradation level allowed for recognizing a common region between the pair of screens to obtain a tomographic image. a deviation setting means for setting a deviation of the tomographic plane, and determining a positional deviation amount (parallax) between the pair of stereoscopic X-ray images according to the tomographic plane set by the tomographic plane setting means, and determining a positional deviation amount (parallax) corresponding to the positional deviation amount. When the gradation difference between the two screens of a point is within the deviation set by the deviation setting means, the X on the tomographic plane is given approximately the same gradation to the corresponding point on the tomographic plane.
An X-ray tomographic imaging apparatus comprising an image processing means for obtaining line image information and a display means for displaying the image information obtained by the image processing means.