JPS5935204Y2 - X-ray imaging device - Google Patents

Description

[Detailed explanation of the invention] This invention is an X-ray image intensifier (hereinafter referred to as 1.I
.

(abbreviated as) 1, 1. using 9-karat gold. This invention relates to an indirect photography device.

Figure 1 shows the conventional method ■.

10 In the example of indirect photography, X-ray generator 1, X-ray grid 3,
■.

■, 5, ■.

It is composed of a holding box 4, a lens system 6, an optical camera 7, a television camera 8, and a television monitor 9.

As shown on the first surface, the subject 2 is placed close to the incident surface of 1.1.5.

An X-ray beam 10 from an X-ray generator 1 projects an image 1.1.5 of a subject 2.

The gold lens system was changed to 6-karat gold and photographed with an optical camera T.

1.1. Indirect photography has 1.1 advantages compared to direct X-ray photography using a sensitized fluorescent sheet metal used in medical X-ray diagnosis and indirect photography using mirror lenses. Due to its brightness enhancement effect, the amount of X-rays required is small, helping to reduce X-ray exposure for examinees.

However, 1.1. Indirect photography has the disadvantage that the resolution of the photograph is inferior to the above-mentioned direct photography.

This is 1.1. This is because the resolution is low.

For example, 12 type 1 where the incident surface field diameter of 1.1.5 is 12
．． When photographing on film from a distance of 1.1 m, a resolution of 25#p/cm can be obtained in terms of the subject plane.

This is significantly inferior to the approximately 501p/cm of the direct shooting method.

Therefore, the resolutions of ■ and ■ are determined by the respective resolutions of the input fluorescent surface, the electron lens system, and the output fluorescent surface.

The resolution of the input phosphor surface is strongly controlled by the thickness of the phosphor surface, and input phosphor surfaces made of the same material must be made thinner in order to improve resolution.

When the area becomes thinner, the absorption rate of X-rays decreases, resulting in a decrease in sensitivity.

The same goes for the output phosphor surface, which must be made thinner in order to improve the resolution, and when made thinner, the luminous efficiency and brightness decrease.

That is, if you increase the resolution of 1.1.5, the sensitivity, that is, the brightness multiplication factor will decrease.

When switching the field of view of 1 and 5, if the resolution of the input fluorescent surface, electronic lens, and output fluorescent surface is balanced in a large field of view and the total resolution is obtained, ■.

(2) If the field of view is made smaller, the field of view reflected on the output phosphor surface is reduced, so the resolution of the output phosphor surface converted to the incident surface is improved, and the resolution of 1.1.5 is improved.

For example, if you change the field of view of the 12〃 shape 1.1.5 so that the field of view of the 9〃 size is in the middle so that part 4 of the X-ray beam 11 is captured, the resolution of the 1.1.5 will improve, so it will be visible on the film. It improves to 281p/cIII.

However, in this case, the balance between the resolution of the input phosphor surface and the output phosphor surface is lost, and the resolution of 1.1.5 is limited by the resolution limit of the worse resolution, that is, the human-powered phosphor surface. It doesn't get better as the number decreases.

Therefore, the input fluorescent surface gold field should be designed to be thin so that the resolution is not limited even when stopped down to 4.
．． I.

5 sensitivity decreases.

Therefore, the required amount of X-rays increases, and there is a limit to the resolution improvement by this method.

From this point of view, as shown in FIG.
．． By enlarging the image of the subject 22 at a distance of 1.24 mm, the resolution can be effectively increased.

In this case, if the front of the X-ray source of the X-ray generator 21 is infinitely small, that is, a point X-ray source, the resolution will be improved by the magnification factor of the image.
It will be significantly improved.

However, in reality, the size of the X-ray source is finite, so it can be better or worse depending on its size and magnification.

Above mentioned 12//1.10 In the example of indirect photography, as shown in Figure 4, the size of the X-ray source is 0.1m1X0.1
mm, 0.3mmX0. : If 1 mm or the like is used, it will improve according to the magnification ratio.

In other words, if you double the magnification with a focus of 0.1mm x 0.1mm, it will be 461p/C in terms of the subject plane on the film.
Improve to rfL.

If the size of the X-ray source is further reduced, the magnification can be made even louder and the resolution will be improved.
As the size of the source becomes smaller, the radiation capacity of X-rays decreases,
Therefore, there are limits to its size depending on the application.

The advantages of this method are 1. I. Since the resolution of has great advantages.

However, such 1.1. Even in magnified imaging, the required X-ray dose increases approximately in proportion to the square of the magnification rate, which is not fully satisfactory from the perspective of reducing exposure.

This invention was made in view of the above circumstances, and includes 1.1.
The objective is to provide a means to significantly reduce the amount of X-rays required for magnified imaging.

The implementation of the present invention will be described in detail below with reference to the drawings.The X-ray imaging apparatus includes an X-ray generator 51,
An X-ray grid 53.1.1.54, a lens system 55, and an optical camera 58 are sequentially arranged, and the lens system 55
A television camera 59 and a television monitor 60 are disposed corresponding to the X-ray generators 51 and 1.
．． I.

54 and the X-ray grid 53 placed immediately in front of it.

The X-ray grid absorbs the scattered X-rays generated when passing through the object.

■It is used to prevent the light from entering.

The distance between the subject 52 and the incident plane of 1.1.54 is configured to be changeable, and when this distance is increased, the X-ray grid 53 can be removed from the path of the X-rays.

X-ray grid 53k To remove from the path of X-rays,
Possible methods include attaching a single tone to the line grid 53 and sliding it by remote control by pulling the X-ray grid 53 with a gold motor, or removing it by rotating one end of the X-ray grid 61 as the tone axis.

That is, the subject 52 and I.

When taking images close to 1.54, use X-ray grid 5:
1-1, 1, 54, and an image k of the subject 52 is generated by the X-ray beam 56 from the X-ray generator 51.
XX dagrid 61 gold and photographed on 1.1.54, photographed with gold television camera 59 and monitored on television monitor 60, then switched to 55 gold lens system and photographed with optical camera 58.

On the other hand, subject 52 and ■.

When taking images at a distance of 1.54 mm, use an X-ray grid of 53 k.
Remove from the X-ray path and take images without passing the X-ray grid 53.

Let's consider the sound effects of this invention.

Now, in the configuration shown in FIG. 5, (1) the X-ray source of the ray generator 51;

■. The position of 54 is fixed at, for example, 125 CrrL, and the distance between the subject 52 and the entrance plane of 1.1.54 is set as fx.

An example of measuring the amount of X-rays incident on 1.1.54 when a phantom gold equivalent to the thickness of 20 crrL of water is used as the object 52 and the X-ray tube voltage is 80 KVp is shown in FIG.

Curve 32 represents the x-ray dose 4 in the conventional case in which the x-ray grid 61 is placed on the path of the x-rays.

In this example, the X-ray grid 61 is 401 p/cm, the grid ratio is 8:1, and the filling is aluminum.

The curve 31 corresponds to the X-ray grid 53 as shown in FIG.
It was measured in the same way as the X-ray dose 4 curve 32 when removed from the radiation path.

As will be seen from now on, when the X-ray grid 61 is present, the X-ray dose hardly changes.

In other words, there is almost no dose due to scattered X-rays, and there is only a dose due to direct rays.

However, when the X-ray grid 53 gold is removed, the object 52 and ■.

(2) The amount of X-rays varies greatly depending on the distance 54. When this distance is small, the X-ray dose is very large, and as this distance increases, it converges to a constant value.

This means that when the distance is small, the dose increases significantly due to the effect of scattered radiation from the object, but as the distance increases, the effect of scattered radiation becomes 7'J'/JXG<, and only the direct radiation component transmitted by the object becomes Therefore, it converges to a constant value.

The difference between this convergence value and the curve 32 represents the absorption amount 4 of the X-rays transmitted through the object by the X-ray grid 53.

In this example, it can be seen that about half of the dose incident on the X-ray grid is absorbed.

This absorption results in a completely unnecessary loss of useful X-rays.

Therefore, the subject 52 and 1. I.

If you can get enough distance gold for 54, use X-ray grid 53ff.
: It can be seen that the effective X-ray dose is doubled by removing it.

In other words, the amount of X-rays from the X-ray generator 51 can be halved, and the amount of X-rays to which the subject is exposed is halved, which is of great benefit to the subject's health.

Therefore, when removing the X-ray grid from the X-ray path, the object and 1.1. The distance differs depending on the thickness of the subject, and as shown in Figure 3, the larger the distance, the better. However, considering the allowable limit for resolution degradation due to scattered X-rays, let us assume that the distance is 20% of the transmitted X-rays. If it is decided to recognize scattered X-rays equivalent to , the distance should be about 40 crth or more.

When the object 52 is thin, the influence of scattered radiation is small, so the distance power bJs may be further reduced.

Furthermore, if the present invention is applied to the following case where the resolution is to be further improved, the effect will be even greater.

That is, there is a limit to the improvement in resolution by increasing the distance sound between the subject 52 and the subject 1.1.54 described above, due to the size of the X-ray source, and the gap between the X-ray source and the subject 52 also increases.
There is a lower limit to the gap in order to reduce the exposure of the subject to scattered radiation from the radiation source.

Therefore, there is a limit in terms of the overall size of the system.

Therefore, as shown in FIG. 5, 1.
1. lf: Use the voltage of the electrodes 62 and 63 to measure 1. I.

1.1. Change the field of view from X-ray beam width 56 to 57.
By switching according to the size of the field of view of 1.1.54 and combining it with the improvement of the resolution of 1.1.54 itself, the resolution can be dramatically improved and unnecessary exposure of the subject to radiation can be eliminated.

12//1.1. In the example of spending money, 1. I. field of view gold 9
Take advantage of the large size of 〃 and also take pictures with the subject ■.

(2) When the distance of the incident surface is raised and the magnification is doubled, the resolution on the film becomes 501 p/cm in terms of the subject surface.

In this case, the sensitivity decreases due to magnification as described above, so by appropriately combining both metals, it is possible to photograph the subject 52.
The required resolution can be obtained while reducing the amount of X-ray exposure.

As described above, according to the present invention, 1.1. It is possible to provide a means to significantly reduce the amount of X-rays required for magnified imaging.

This effect not only reduces the amount of X-rays the subject is exposed to, but also lightens the load on the X-ray generator, allowing the use of an X-ray tube with a small focal point.1.1. The degree of improvement in resolution due to enlarged shooting is 4 good, and the effect is very large.

[Brief explanation of the drawing]

Figure 1 shows the conventional 1.1. FIG. 2 is an explanatory diagram of the configuration showing one side sound of an indirect photographing device, FIG. 2 is an explanatory diagram of the configuration of another example, and FIG. Figure 4 shows the characteristic curve diagram of the transmission and scattering degree of X-rays by the subject in indirect imaging equipment.
Curve diagram showing one side tone of the resolution characteristics of the device shown in Fig. 5.
The figure is an explanatory diagram of the construction of an embodiment of the X-ray imaging apparatus of the present invention. 51...X-ray generator, 52...Subject, 61°53...X-ray grid, 54...
...1.1. ．． 55... Lens system, 58...
...Optical camera, 59...Television camera, 60...Television monitor.

Claims (2)

[Scope of utility model registration request] (1) X-ray photography in which a Xi generator, an X-ray grid, an X-ray image intensifier, an optical camera or a television camera are arranged in sequence, and the subject is placed between the X-ray generator and the X-ray grid. In the device, the distance between the subject and the entrance plane of the X-ray image intensifier can be changed,
An X-ray imaging apparatus characterized in that, when this distance increases by 40 crfL or more, the X-ray grid is removed from the X-ray path while being slid or rotated in remote practice. (2) The X-ray imaging apparatus according to claim 1, characterized in that the Xi image intensifier is of a variable entrance surface field of view type.