JPH03233554A - X-ray radiographing device - Google Patents

Abstract

PURPOSE:To efficiently remove or attenuate secondary X-ray and to obtain a good-quality X-ray image having high diagnostic ability by supporting a front surface intensifying screen by a supporting plate consisting of an X-ray grid where an X-ray absorbing substance and an X-ray transmitting substance are alternately arranged and making the supporting plate swell to the side of a back surface intensifying screen. CONSTITUTION:When a sheet film is made contact between the front surface intensifying screen 9 and the back surface intensifying screen 10, the X-ray grid 21 which is used also as the supporting plate of the front surface intensifying screen is deformed by giving nearly equivalent surface load by the intensifying screen 10 and the convergence distance of the X-ray grid in accordance with a distance between the grid and the focal point of an X-ray tube bulb is obtained. Namely, contact moving quantity of the sheet film by the intensifying screen 10 is adjusted to deform the X-ray grid. Thus, the X-ray image which is excellent in contrast and sharpness and has the high diagnostic ability is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to secondary xIs generated from a subject during X-ray imaging.
The present invention relates to an X-ray imaging apparatus that effectively removes or attenuates X-ray images to obtain X-ray images with high diagnostic performance.

L. Prior Art] First, an outline of a film changer will be explained with reference to FIGS. 5 and 6. FIG. 5 shows the state in which the film changer 1 is used, and the film changer 1 is supported by a pedestal 2. As shown in FIG. The subject P is located in front of the film changer 1, and the subject is irradiated with X-rays from the X-ray generator 3 located behind the subject P.

FIG. 6 shows an example of the conventional film changer 1, in which two types of untransferred sheet films Sa and Sb of different sizes are shown.
Two supply magazines 4a and 4b containing film are installed vertically, and each supply magazine 4a and 4b has a rectangular opening 5a suitable for loading and unloading film on the entire surface thereof.
5b is provided.

When shooting, use these supply magazines 4a, 4
Film Sa% from b by either suction cup 6a, 6b
The sb is taken out one by one and transported by a guide plate 7 and a plurality of sets of feed rollers 8 to close contact with an intensifying screen consisting of a front intensifying screen 9 and a rear intensifying screen 10 arranged vertically near the front part. It is fed into the section 11 and sandwiched between the front intensifying screen 9 and the rear intensifying screen 10. Photographing is performed in this state, and when the photographing is completed, the film Sa or sb is dropped downward by the scraping lever 12 and collected by the feed roller 13, guide plate 14, etc. into the receive magazine 15 placed horizontally.

In such conventional general X-ray imaging equipment, there is a problem in that secondary X-rays generated from the subject become an obstructive factor, making it difficult to obtain high-quality X-ray images with high diagnostic ability. Various methods are used to remove or attenuate secondary X-rays. can be effectively removed or attenuated to obtain an X-ray image with high contrast and sharpness.

Such an X-ray grid combines an X-ray absorbing material such as lead with a thin foil of an X-ray transparent material such as aluminum or wood.
There is a parallel type grid in which the foils are arranged in parallel, with tens of foils arranged alternately per cm, and a focusing type grid in which the foils are arranged at an angle to match the X-ray emission angle. is used.

For parallel grids, the distance between the grid and the X-ray tube focal point (hereinafter referred to as grid-X-ray tube focal distance) is 100 cm.
Although it is possible to use this method in some cases, it is not possible to obtain sufficiently high quality X-ray images because the cutoff of the primary X-rays in the periphery is large in that case. Therefore, when taking images using an X-ray grid at close range or using an X-ray grid with a high grid ratio, a focusing grid is used to reduce the cutoff amount of primary It is necessary to make it as small as possible.

[Problems to be Solved by the Invention] However, in such a convergent X-ray grid, although there is a tolerance range for the distance between the grid and the focal point of the X-ray tube, the cutoff of primary X-rays in the peripheral area is Since there are some
It is not always possible to obtain a line image. Furthermore, if the distance between the grid and the focal point of the X-ray tube is extremely different depending on the part of the subject to be imaged, there is also the troublesome problem of having to replace the grid with a grid having a different convergence distance.

It is an object of the present invention to provide an XTAI imaging device that improves these problems and efficiently removes or attenuates secondary X-rays to obtain high-quality X-ray images with high diagnostic ability. It is in.

[Means for Solving the Problems] In order to achieve the above object, in the X-ray imaging apparatus according to the present invention, a sheet film is sandwiched between a front intensifying screen and a rear intensifying screen to perform imaging. In an X-ray imaging device,
The front intensifying screen is supported by a support plate consisting of an X-ray grid in which radiation-absorbing materials and X-ray transmissive materials are arranged alternately, and the support plate is bulged toward the rear intensifying screen. It is.

[Function] When the X-ray imaging apparatus having the above-mentioned configuration brings the sheet film into close contact between the front intensifying screen and the rear intensifying screen, the rear intensifying screen applies a substantially uniform surface load to the front intensifying screen. By deforming the X-ray grid that also serves as an intensifying screen support plate, a convergence distance of the X-ray grid corresponding to the distance between the grid and the focal point of the X-ray tube can be obtained.

[Example] The present invention will be explained in detail based on the example illustrated in FIGS. 1 to 4. Note that the same reference numerals as in FIGS. 5 and 6 indicate the same members.

The present invention is an improvement of the intensifying screen contact portion 11 in the film changer 1 shown in FIG. 6, and FIG. 1 shows a perspective view of the intensifying screen contact portion 11, and FIG. 2 is a sectional view. . Here, 20 is a fixing member in the intensifying screen contact portion 11, and 21 is an X
The X-ray grid 21 also serves as a support plate for the front intensifying screen 9. The X-ray grid 21 to which the front intensifying screen 9 is attached has only two opposing sides 21a and 21b fixed to the fixing member 20, as shown in FIG.
As shown in FIG. 2, some of the sides 21a and 21b are bulged or protruded toward the rear intensifying screen lo side, as shown in FIG. Further, a cushion layer 23 is interposed between the rear intensifying screen 10 and its support plate 22, and this cushion layer 23 can absorb some deformation of the front intensifying screen 9. In the cushion layer 23 behind the rear intensifying screen 1o, an appropriate number of X-ray detectors 24a, 24b, 24
c is embedded so that the X-rays that have passed through the X-ray grid 21, the front intensifying screen 9, and the rear intensifying screen 10 can be extracted as electrical signals.

3 and 4 show enlarged cross-sectional views of the X-ray grid 21, in which the X-ray grid 21 has a lead foil 25 which is an X-ray absorbing material.
, spacers 26 made of an X-ray transparent material are alternately arranged in parallel. FIG. 3 shows the state before the sheet film is adhered, and FIG. 4 shows the state after the sheet film F is adhered. In the state shown in FIG. 3, the X-ray grid 21 protrudes toward the rear intensifying screen 10 from its center, so the lead foil 25 and spacer 26 within the X-ray grid 21 are angled and tilted. There is.

However, when the sheet film F is inserted and the flat rear intensifying screen 10 is pressed, the X
The ray grid 21 and the front intensifying screen 9 are also flat. In this state, the convergence distance of the X-ray grid 21 may be set in advance to be about 180 cm (grid-X-ray tube focal distance).

From the position where the X-ray grid 21 and the front intensifying screen 9 become flat, the rear intensifying screen 10 is gradually separated in the direction of the arrow 6 (and the rear intensifying screen of the X-ray grid 21, which had been flat Since the planes of the 10 examples are gradually curved, the convergence distance also gradually changes to become shorter.

Therefore, if the correspondence between the amount of movement in the direction of arrow A and the convergence distance is clarified, even if the distance between the grid and the X-ray tube focal point changes depending on the part of the patient to be imaged, the rear intensifying screen By adjusting the movement amount of 10, an appropriate convergence distance of the X-ray grid 21 can be obtained. When strictly reducing the cutoff amount of the primary X-ray at the periphery, the rear intensifying screen 10 is moved to a close position corresponding to the grid = X-ray tube focal length change. .

Next, a small amount of X-rays are irradiated without the patient being examined, and
The X-rays transmitted through the ray grid 21, the front intensifying screen 9, and the rear intensifying screen 10 are received by the X-ray detectors 24a, 24b, and 24c, and by comparing these electrical signals, that is, the amount of X-rays, the rear intensifying screen is detected. By finely adjusting the amount of movement of the paper 10 in the direction A, it is possible to obtain a high-quality X-ray image in which the cut-off amount of -order X-rays is reduced as much as possible.

In addition, in the above embodiment, in order to deform the X-ray grid 21 which also serves as a front intensifying screen support plate, the amount of movement of the rear intensifying screen 10, that is, the surface load is changed, but another method may be used. May be used. For example, the X-ray grid 21 is deformed in advance according to the required convergence distance of the X-ray grid 21 by a mechanical method or a method using a thermal expansion difference of the grid surface material, and a sheet film is formed using the rear intensifying screen 10. A similar effect can also be obtained by a method of pressing F to such an extent that the X-ray grid 21 and the front intensifying screen 9 are not deformed.

[Effects of the Invention] As explained above, the X-ray imaging device according to the present invention uses a converging X-ray grid as a film changer,
By adjusting the amount of contact movement by the rear intensifying screen of the sheet film and deforming the
Since the convergence distance can be obtained according to the distance between the X-ray tube focal points, it is possible to obtain X-ray images with excellent contrast and sharpness and high diagnostic ability.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the X-ray imaging device according to the present invention, in which Figure 1 is a perspective view of the intensifying screen contact area, Figure 2 is a sectional view thereof, and Figure 3 is a sheet. FIG. 4 is an enlarged sectional view of the film not in close contact with the film, FIG. 4 is an enlarged sectional view of the film in close contact with the film, FIG. 5 is a schematic diagram of how the film changer is used, and FIG. 6 is a configuration diagram of the film changer. 9 is a front intensifying screen, 10 is a rear intensifying screen, 20 is a fixing member, 21 is an X-ray grid, 22 is a support plate, 23 is a cushion layer, and 24a, 24b, and 24c are xi detectors.

Claims (1)

[Scope of Claims] 1. In an X-ray imaging device that performs imaging by sandwiching a sheet film between a front intensifying screen and a rear intensifying screen, An X-ray imaging apparatus characterized in that the front intensifying screen is supported by a support plate made of a ray grid, and the support plate is bulged toward the rear intensifying screen. 2. The X-ray imaging according to claim 1, wherein the front intensifying screen is provided with means for adjusting the amount of movement of the rear intensifying screen so that the sheet film is brought into close contact with the sheet film by the surface load of the rear intensifying screen. Device. 3. The X-ray imaging apparatus according to claim 1, further comprising an X-ray detector embedded in the rear part of the rear intensifying screen.