JPH05299044A - Image intensifier - Google Patents

Abstract

PURPOSE:To improve transmissivity of X-rays in an input window, and reduce the scattering of the X-rays by constituting the input window of amorphous carbon. CONSTITUTION:An input screen 6 formed by laminating an input plane substrate 3, an input fluorescent plane 4 and a photocathode 5 upon each other is arranged on an input window 1a on the inside of a vacuum container 1. This input window 1a is formed in a cylindrical capped shape by means of an amorphous carbon thin plate. In this image intensifier, for example, when an X-ray image passes through the input window 1a after passing through a material to be inspected, the input fluorescent plane 4 emits, and photoelectrons are generated by means of the photocathode 5. In this image intensifier, since the input window is composed of amorphous carbon, transmissivity of X-rays becomes excellent, so that the transmissivity can be improved largely particularly in a soft X ray area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image intensifier (hereinafter referred to as "II") used for enhancing an X-ray signal transmitted through a human body or a material in an X-ray diagnostic apparatus, an X-ray material inspection apparatus, or the like. Regarding

[0002]

2. Description of the Related Art I and I are constructed as shown in FIG. 3, and an input screen substrate 32, an input fluorescent screen 33, and a photocathode 34 are laminated on an input window 31a inside a vacuum container 31. An input screen 35 is arranged, an output screen 38 formed by laminating a glass substrate 36 and an output fluorescent screen 37 and an anode 39 are arranged in the output window 31b, and photoelectrons are focused on the inner side wall of the vacuum container 31. The focus electrode 40 is arranged. Here, since the input window 31a forming a part of the vacuum container 31 needs to have a strength capable of withstanding atmospheric pressure and needs to have good X-ray transparency, its material is: Glass, aluminum and titanium are used.

[0003]

However, the above-mentioned I
-The input window of I requires a thickness of several mm when made of glass and about 1 mm when made of aluminum or titanium in order to maintain a certain level of strength to withstand atmospheric pressure and impact. Also, in the above-mentioned I · I, 60 ke, which is called soft X-ray
It is difficult to sufficiently convert an X-ray image having a long wavelength of V or less into a signal of a visible image (optical image), an X-ray image of human soft tissue cannot be accurately drawn on a monitor, etc. There is a problem that there is a limit. Further, aluminum and titanium are essentially crystalline metals, and depending on the incident angle of X-rays, X is due to a metal crystal lattice called Bragg reflection angle.
Since scattering and interference of rays occur, there is a problem that noise or unevenness called an artifact (artificial false image) occurs in the X-ray image when the X-ray beam is very small.

The present invention has been made to solve these problems, and an object of the present invention is to provide an image intensifier having an input window which has good X-ray transmission and little X-ray scattering.

[0005]

The image intensifier according to the present invention converts the X-ray quanta incident on the input window into photoelectrons and focuses them to obtain an optical image, which is then output from the output window. In the output image intensifier, the input window is formed by a thin plate of amorphous carbon.

Such an input window may be formed by impregnating a thin plate of amorphous carbon with a resin such as plastic.

[0007]

[Operation] The image intensifier of the above means is
Since the input window that forms part of the vacuum container is made of amorphous carbon and the material is carbon,
The transparency of soft X-rays can be improved about 10 times as compared with the case of forming with glass, and the transparency of soft X-rays is 5 times as compared with the case of forming with aluminum or titanium.
It can be improved about 10 times. Further, amorphous carbon is an aggregate of pure carbon having no crystallinity, and unlike graphite obtained by compression-molding general powder, it has no particle property and has no characteristic like CFRP (carbon fiber reinforced plastic). is there. Therefore, the incident X-rays are not scattered or interfered in the input window, and an optical image without artifacts can be obtained from the output window.

Furthermore, when a thin plate of amorphous carbon is impregnated with a resin, the airtightness and flexibility of the vacuum container can be improved, and the strength of the input window against impact can be increased.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the structure of the image intensifier of the first embodiment. An input screen 1 formed by stacking an input surface substrate 3, an input fluorescent screen 4 and a photocathode 5 is arranged in an input window 1a inside the vacuum container 1, and a glass substrate 7 and an output fluorescent screen 8 are provided in an output window 1b. A stacked output screen 9 and an anode 10 are arranged, and a focus electrode 11 for focusing photoelectrons is arranged on a side wall inside the vacuum container 1.

The input window 1a of the vacuum container 1 is formed of a thin plate of amorphous carbon into a cylindrical lid shape. The end portion of the joining peripheral edge of the input window 1a is formed to be large outside by one step, and can be overlapped and joined to the opening peripheral edge portion of the cylindrical main body 2. The lap joining is performed by diffusion welding, organic or inorganic adhesive, or the like.

Here, the input window 1 of amorphous carbon is used.
The production of a is performed by melting and solidifying a special resin such as polycarbodiimide in an inert gas. Since the specific gravity of such amorphous carbon can be freely deformed to about 1.0 to 1.5, when the specific gravity is lowered to form a fine bubble structure, a thin plate of amorphous carbon is coated with a resin such as plastic. To improve the flexibility and airtightness of the thin plate.

In the above image intensifier,
For example, the X-ray image transmitted through the subject is the input window 1a of I · I.
, The input fluorescent screen 4 emits light, and photocathodes 5 generate photoelectrons. At this time, a voltage is applied to each of the photocathode 5, focus electrode 11, and anode 10 by the acceleration power supply 12. Then, the photoelectrons generated by the photocathode 5 are focused and accelerated by the electric field generated by the focus electrode 11 of the vacuum container 1, and then enter the output fluorescent screen 8 to cause the output fluorescent screen 8 to emit light. When the output fluorescent screen 8 emits light in this way, an optical image is projected on the back side of the output screen 9, converted into a video signal by a television image pickup tube (not shown), and then displayed as an X-ray transmission image on the monitor. It has become.

FIG. 2 is a block diagram showing the image intensifier of the second embodiment.

The I / I of this embodiment is different from the I / I of the above-described embodiment except that the joining means for connecting the input window 20 and the main body 21 is different.
It has the same structure as.

The I / I input window 20 of this embodiment is formed of a thin plate of amorphous carbon into a cylindrical lid shape, and a cylindrical main body 21 is provided with an annular auxiliary contact plate 22 on the inner peripheral edge thereof. It is fixed. Input window 20 and tubular body 2
The connection with 1 is performed by abutting them via the auxiliary contact plate 22.

For such joining, in addition to the diffusion welding described in the above embodiment, metal coating, metallizing,
A method such as metal impregnation may be used.

As described above, in the first and second embodiments, only the input windows 1a and 20 of the vacuum container are made of amorphous carbon. However, the present invention is not limited to this, and the entire vacuum container may be made of amorphous carbon. In this case, the same effect can be obtained.

[0019]

In the image intensifier of the present invention, since the input window is made of amorphous carbon, the X-ray transparency is good, and the transparency especially in the soft X-ray region can be greatly improved, and the resolution is improved. It is possible to display an X-ray image, which is excellent in organ depiction and noise reduction, on a monitor. In particular, it is possible to reduce the beam hardening (Beam Herdning) phenomenon that accompanies the transmission of X-rays.
The depiction of human soft tissue can be improved. Furthermore,
When a thin plate of amorphous carbon is impregnated with a resin, the airtightness and flexibility of the vacuum container can be improved, so that the molding of I · I can be facilitated and the strength can be increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a first embodiment I / I of the present invention.

FIG. 2 is a sectional view showing the configuration of a second embodiment I / I of the present invention.

FIG. 3 is a cross-sectional view showing a conventional I / I configuration.

[Explanation of symbols]

 1 Vacuum Container 1a, 20 Input Window 1b Output Window 2, 21 Main Body 3 Input Surface Substrate 4 Input Fluorescent Surface 5 Photocathode 6 Input Screen 7 Glass Substrate 8 Output Fluorescent Surface 9 Output Screen 10 Anode 11 Focus Electrode 12 Acceleration Power Supply 22 Auxiliary Board

Claims (2)

[Claims] 1. An image intensifier in which X-ray quanta incident on an input window are converted into photoelectrons, which are focused to obtain an optical image, and the optical image is output from the output window, the input window is amorphous carbon. An image intensifier characterized by being formed from a thin plate. 2. An image intensifier in which X-ray quanta incident on an input window are converted into photoelectrons, which are focused to obtain an optical image, and the optical image is output from the output window, the input window is amorphous carbon. An image intensifier characterized by being formed by impregnating a thin plate with resin.