JPH0419855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an improvement of an arbitrary cross-sectional image extracting device for extracting an image of a cross-sectional plane at an arbitrary height of a subject in an X-ray tomography apparatus.

(b) Prior Art The present inventors have invented this arbitrary cross-sectional image extraction device and have already filed an application (see Japanese Patent Application No. 167228/1983). The principle of this arbitrary cross-sectional image extraction device is as follows. In Fig. 1, Fi and Fi+1 are the X-ray tube focal positions at the i-th and i+1-th imaging times, and the projected image of point O at each imaging time appears at points O′i and O′i+1. . This point
A normal X-ray tomography system obtains a tomographic image in the x-plane including point O by moving the film for each exposure and performing multiple exposures so that O'i and O'i+1 are located at the center of the image-receiving surface. It is. In this case, the images from each shooting are stored as they are, read out later, and the i-th image is shifted to the left by Δxi,
Shifting the i+1-th image to the left by Δxi+1 and superimposing these images yields point P′i and point P′i+1
will overlap, and the image of point P projected onto this point will appear. In other words, only the image on the tomographic plane parallel to the x-plane at the height Δy that includes point P appears clearly, and the image at other heights becomes blurred. And these Δxi and Δxi+1 can be determined by the following equation.

Δxi (H・Δy/h−Δy)・tanθi Δxi+1= (H.Δy/h−Δy)・tanθi+1 Therefore, the X-ray tube device and imaging device are
Similar to a line tomography device, images are obtained at each position by symmetrical linear movement around point O, and images of tomographic planes at arbitrary heights can be extracted by performing image processing later. I can do it.

By the way, in this case, since the X-ray tube device and the imaging device must be moved linearly while maintaining a specific relationship, it is necessary to use a dedicated X-ray tomography device having a special structure.

(c) Purpose This invention improves the arbitrary cross-sectional image extracting device described above, makes it possible to obtain a tomographic image at an arbitrary height even by rotational movement, and uses a general-purpose cardiovascular X-ray diagnostic device. The purpose is to make it possible to obtain tomographic images at arbitrary heights.

(D) Configuration The arbitrary cross-sectional image extracting device according to the present invention converts an image obtained by rotating the X-ray tube device and the imaging device into an image projected onto a plane parallel to the tomographic plane. The image is similar to the image obtained by linear motion, and the images are shifted and superimposed.

(e) Example In Fig. 2, the tomographic plane (x plane) of subject 1
A connecting rod 2 can be rotated around a point O, and an X-ray tube device 3, an X-ray image intensifier 4, and a TV camera 5 are connected to this connecting rod 2. They are held facing each other. Such a mechanism is a mechanism employed in ordinary cardiovascular X-ray diagnostic equipment. Video signals obtained from the TV camera 5 at each angle are sent to an image memory 6, where a large number of images are stored. Further, the angle at which each image was taken is detected by the rotation detector 7, sent to the CPU 8, and similarly stored.

After storing the images in this manner, each image is read out from the image memory 6 and first sent to the image conversion circuit 9. This image conversion circuit 9 performs the following image conversion. Assuming that the i-th image is taken at an angle θ as shown in FIG. 3, the image read out from the image memory 6 is projected onto a plane Ii perpendicular to the direction facing point O. In other words, it forms an angle θ with respect to the x plane. Therefore, the image Pi of point P projected onto the plane Ii
Let's consider what happens if we project it directly onto a plane I′i parallel to the x-plane. If the image of point P projected onto plane I'i is P'i, it can be seen that the relationship O'Pi/O'P'i=cosθ holds true. Therefore, by calculating O′P′i=O′Pi/cosθ, point Pi on plane Ii becomes
This means that it has been converted to P′i. If this calculation is performed for all planes Ii, the image on plane Ii becomes plane I′i
You can convert it to the image above. The thus converted image is converted to an arbitrary height Δy set by the setting device 15 using the above formula as in the conventional arbitrary cross-sectional image extracting device.
Shift circuit 1 by the distance Δxi determined according to
0, and added by an adder circuit 11,
If displayed on the display device 12, a tomographic plane at an arbitrary height Δy can be obtained. The image of this tomographic plane is
It is recorded on the VTR 13 or printed with a printing device 14 such as a dot image printer.

(f) Effects According to the present invention, a tomographic image at any height can be obtained using a general-purpose cardiovascular X-ray diagnostic device,
There is no need to use a dedicated X-ray tomography device with a special mechanism.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the principle of a conventional arbitrary cross-sectional image extraction device, Fig. 2 is a block diagram of an embodiment of the present invention, and Fig. 3 is a diagram for explaining the operation of Fig. 2. It is. 1... Subject, 2... Connecting rod, 3... X-ray tube device, 4... X-ray image intensifier, 5
...TV camera, 6...Image memory, 7...Rotation detector, 8...CPU, 9...Image conversion circuit, 1
0...Shift circuit, 11...Addition circuit, 12...
Display device, 13... VTR, 14... Printing device,
15...Setting device.

Claims (1)

[Claims] 1. An X-ray tube device that irradiates X-rays toward a subject, an imaging device that converts images from the X-rays that have passed through the subject into electrical signals, and the X-ray tube device and imaging device face each other with the subject in between. a connecting rod that rotates around the subject while holding these; an image storage circuit that stores image signals obtained from the photographing device for each position of the rotation; and an image storage circuit that stores each image from the image storage circuit. An arbitrary image conversion circuit that reads out and converts it into an image projected on a plane parallel to the tomographic plane, a shift circuit that shifts each converted image by a predetermined amount, and an addition circuit that superimposes each shifted image. Cross-sectional image extraction device.