JPS58196476A - Radiation image multiplying tube - Google Patents

Abstract

PURPOSE:To display or record a visible image corresponding to a radiation image, by a method wherein a fluorescent substance layer and an electron multiplying mechanism for multiplying an electron by the optical stimulation of said layer are accommodated in a single vacuum container to make it possible to directly multiply and convert the radiation image to an electric signal which is in turn supplied to an imaging mechanism. CONSTITUTION:After X-rays permeating a subject are irradiated to the fluorescent substance layer 2 of an X-ray image multiplying tube to form a latent image on the fluorescent surface thereof, galvanometers 7, 8 are swung by the signals of saw tooth wave generators 10, 11 and the surface of the fluorescent substance layer 2 is rapidly scanned by fine laser beams from a laser beam source 9. By this scanning, an exoelectron proportional to the irradiated X-ray amount is discharged from each scanning point and multiplied an electron multiplying mechanism 3 to be collected by an output electrode 5. The current obtained from the output electrode 5 is inputted in the Z-axis of CRT 12 through an amplifier 13 and an image treating circuit 14. Because the signals of the saw tooth wave generators 10, 11 are supplied to the X-axis terminal and the Y-axis terminal of the CRT 12, a visible image corresponding to the X-ray image permeating the subject is projected to the CRT 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation image intensifying tube for intensifying radiation images such as X-ray images, and in particular to a phosphor layer formed of a photostimulable exoelectron emitting material and a phosphor layer formed of a photostimulable exoelectron emitting material. This invention relates to a radiation image intensifier tube that is combined with an electron multiplier mechanism that multiplies images.

Conventionally, radiographic images such as X-ray images have been multiplied.1. An image tube is used to obtain a bright visible image.

This image tube consists of an input screen consisting of a phosphor screen and a photocathode, and an output phosphor screen disposed facing each other in a large vacuum container, and a focusing electrode and an anode constituting an electron lens system arranged between the two. The input screen exchanges radiation images such as X-ray images with electronic images.

This 1 is accelerated and focused by an electron lens system and multiplied on the output phosphor screen. It is designed to form a reduced image.

In addition, although the input screen of this type of image tube is formed into a spherical surface in order to reduce image distortion caused by the electron lens system, image distortion, especially in the peripheral area, is large, and the spherical shape of the input screen and the electron lens Coupled with the fact that the image tube is multiplied by the system, there is a drawback that the lengthwise dimension of the image tube becomes large. Furthermore, it can be combined with a television violet device to magnify and observe the image output from the image tube.

In order to guide the output image of the image tube to the television camera, an optical system is used between the output phosphor screen of the image tube and the television camera, resulting in poor light collection efficiency.The way to compensate for this is to increase the gain of the amplifier. As a result, the S/N ratio deteriorates, and the entire system including the image tube and television equipment becomes expensive.

Furthermore, since a phosphor screen is used to form the output image of the image tube, good image quality cannot be obtained.

In view of the above, the present invention is capable of directly multiplying and converting a radiographic image such as an X-ray image into an electrical signal corresponding to the irradiation dose, and also by supplying the electrical signal to an image forming mechanism such as a CRT. The aim is to provide a radiation image intensifier tube that can display or record visible light images corresponding to Used as a layer.

This phosphor layer and the phosphor layer emitted from this phosphor layer upon light stimulation1.
A radiation image intensifier tube is constructed by accommodating an electron multiplier mechanism that multiplies the generated electrons in a single vacuum container.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A radiation image intensifier of the present invention and a radiation image forming apparatus using the same will be described below with reference to embodiments shown in the drawings.

FIG. 1 is a schematic cross-sectional view showing the structure of an embodiment of the radiation image intensifier of the present invention, in which (1) is a vacuum container made of glass or the like, and (2) is an input window of the vacuum container (1). (11) is a flat phosphor layer provided facing the phosphor layer (3) is a phosphor layer (
2) In the electron multiplier mechanism/mechanism arranged on the rear surface, multiple dymates T'b) (42)...(46) and these diodes are used to multiply 1. The output electrode (
5) Consists of 1. ing. (6) is the phosphor layer (2)
1 and the electron multiplier mechanism (3). a focusing electrode that focuses exoelectrons emitted from the surface of the phosphor layer (2) by optical stimulation onto the diode (4) of the electron multiplication mechanism (3);
[12] is a window formed on the shoulder of the vacuum container (1) through which the back side of the phosphor layer (2) can be viewed from outside the vacuum container (1). When reading out an image, a narrow beam of light such as a laser beam is projected from this window (12).
The phosphor layer (2) is two-dimensionally scanned. nai-3,
If the vacuum container <1) is a transparent body such as glass, the window Cl2) is formed by applying an opaque substance to the outer wall of the container (1). As the fluorescent substance forming the fluorescent layer (2),
LiF, Bed, Al2O3, Ta205°CaS
Various alkali halides such as O4, BaSO4, SrSO4.

Oxides, sulfides and mixtures thereof may be used.

For example, a mixture of BeO powder and graphite is applied to a substrate (eg, graphite) to form a phosphor layer (2).

These fluorescent substances are excited by irradiation with radiation such as X-rays,
It is known that when exposed to light such as a laser, exoelectrons are emitted in proportion to the amount of radiation irradiated.1. I'm here.

In the above configuration, when the X-rays transmitted through the object (7) are irradiated onto the phosphor layer (2) through the entrance window (11), the phosphor layer (2) absorbs the fidgeting and forms a latent image. Ru.

After the formation of the latent image, 1. is formed on the shoulder of the vacuum container (1). A narrowly focused light beam such as a laser beam is projected onto the back surface of the phosphor layer (2) through the window (12), and this light beam illuminates the phosphor layer (2).
2) When a surface is two-dimensionally scanned, electrons proportional to the amount of X-rays irradiated at the scanning point are emitted from the scanning point of the light beam.

Emitted by this light beam scanning: 1. The electrons are focused by the focusing electrode (6)
focused on the dynode (4) at 1. are sequentially multiplied and captured by the output electrode (5).1. 1. Ru.

That is, an enhanced current is extracted from the output electrode (5) in proportion to the amount of X-rays irradiated at each point on the phosphor layer (2).

Therefore, the output signal of the output electrode (5) is transferred to the CRT's 2(
(brightness) signal, light beam scanning and CRT (7) X axis, Y axis
By synchronizing the axis sweep signals, a visible image corresponding to the X-ray transmitted image of the object can be obtained on the CRT. Also,
Using a facsimile technique, the light beam scanning of the phosphor layer (1) in the X-axis direction and the scanning of the CRT in the X-axis direction are synchronized, and the light beam scanning of the phosphor layer (1) in the Y-axis direction and the feeding of the recording medium are performed. It is possible to record on photographic paper if the images are synchronized by 1°.

In addition, in Figure 1, the electron multiplication mechanism (3) is replaced by the phosphor layer (2).
The light beam for scanning the phosphor layer (2) was arranged perpendicularly to the phosphor layer (2), and the light beam for scanning was projected from an oblique direction. .

An electron multiplier may be provided at the position of the window (12) in FIG.

FIG. 2 is a diagram showing the configuration of an X-ray image forming system that combines the X-ray image intensifier tube configured in FIG. 1, a light beam scanning mechanism for reading out latent images, and an image forming mechanism such as a CRT. Note 1
In the figure, the same components as in FIG. 1 are given the same reference numerals.

In the figure, +71 and +81 are an X-axis scanning galvanometer and a Y-axis scanning galvanometer that constitute the light beam scanning mechanism. Mirror (71)
(81). (9) is a laser light source, and the narrowly focused laser light B is projected onto the phosphor layer (2) from the window (12) of the vacuum container (1) via the mirror (71) (8t). Ru.

α (IcIII is a sawtooth wave generator around the n, x, and y axes.

The output signal is transmitted to the corresponding galvanometer (71 (8)
1 given to 1. The mirrors (71) and (81) are swung as shown by the arrows in the figure.1. Ru. By swinging these mirrors (71,) (81), the laser beam B scans the surface of the phosphor layer (2) two-dimensionally.

The tapping is a CRT, and the x-axis and Y-axis terminals have the corresponding x-axis,
The output signal of the sawtooth wave generator α[I for the Y axis is supplied, and the output signal of the output electrode (5) of the electron multiplier (3) is supplied to the amplifier α31 and the image processing circuit α gradient on the Z axis. It is supplied via l.

With the above configuration, the X-rays transmitted through the object are irradiated onto the phosphor layer (2) of the X-ray image intensifier.12. After a latent image is formed on the fluorescent screen, the signal from the sawtooth wave generator αB turns the galvanometer +7.
When 81 swings, the surface of the phosphor layer (2) is scanned at high speed with a narrow laser beam from a laser light source (9).

Irradiation X from each scanning point by scanning with this laser beam
Exoelectrons proportional to the dose are emitted (read out)11.
These electrons are captured by the output electrode (5) with an electron multiplier (3) at a multiplication level of 1°. Ru.

Obtained from the output electrode (5) 1. The current generated by the amplifier α31.
The signal is input to the Z axis of CRTQ3 via image processing circuit α4.

The signal of the sawtooth wave generator Q (1 (Ill) is supplied to the X-axis terminal and Y-axis terminal of the CRT a7J, so
A visible image corresponding to the transmitted X-ray image of the object is displayed on the CRTt13.

Furthermore, as in the embodiment shown in FIG. 2, an erasing light source is used to irradiate uniform light over the entire surface of the phosphor layer (2) and erase the latent image accumulated and formed on the phosphor layer (2). A control circuit (161) is provided to control the lighting of the erasing light source, pulsed X-ray irradiation, and laser beam scanning (reading), and the timing of X-ray irradiation, reading, and erasing is shown in the time chart of FIG. By repeatedly controlling the CRT Q3, a real-time X-ray image (moving image) can be displayed on the CRT Q3.At this time, if a recording/playback device α indicated by a dotted line is provided, pulse X-ray fluoroscopy becomes possible.

Furthermore, if a frame memory (181) 118z) and a subtraction circuit a9 are provided as shown in the dashed line in FIG. 2, a subtraction image can be obtained, and a recording bag can be used instead of a CRT! If (2) is provided, it becomes possible to record an X-ray image on photographic paper or film.

In addition, C! in Figure 2! 11 i,t A/D converter, (2
It is a 21-channel D/A converter. Also, the image processing circuit (141
performs processing such as improving gradation and contrast.

Although the above embodiments have explained the multiplication of X-ray images, the radiation image intensifier of the present invention can also be applied to the multiplication of gamma-ray images and neutron-ray images.

Furthermore, although laser light was used to read out the latent image in the embodiment, it is not limited to laser light, and visible, infrared, or ultraviolet light may be used, and the light scanning mechanism is not limited to the galvanometer of the embodiment.

Further, in the embodiment, the electron multiplication mechanism is constructed of a dynode and an output electrode, but two types of electron multiplication mechanisms such as channel and plate type electron multiplication mechanisms can be applied.

Furthermore, although the light beam scanning mechanism is provided outside the vacuum container in the embodiment, it can also be housed within the vacuum container in the same manner as the phosphor layer and the electron multiplier.

As described above, the radiation image intensifier of the present invention combines a phosphor layer that emits exo-electrons upon optical stimulation and an electron multiplier mechanism that multiplies the exo-electrons emitted from this phosphor layer in a single vacuum. Since it is housed in a container, it is possible to directly convert a radiation image into an electrical signal, and the electrical signal can already be applied to image formation.

Therefore, there is no need for an electron lens system or an output phosphor screen for image formation, which are indispensable in image tubes conventionally used to multiply radiation images.

1. The conversion efficiency from a radiation image to a visible image is significantly improved, and together with the planarization of the phosphor layer, an image without image distortion can be obtained.1. It is something that

In addition, since the phosphor layer absorbs radiation and forms a latent image, the integrated amount of radiation can be detected, resulting in good quantum efficiency.
/N good images can be obtained.

Furthermore, the radiation image intensifier tube can be made smaller and an electrical signal corresponding to the radiation image can be obtained, which can be directly supplied to an image display means such as a CRT, so there is no need for a television camera or the like to connect the limb tube and the CRT. This provides remarkable effects such as a simplified configuration.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the configuration of an embodiment of the radiation image intensifier of the present invention, FIG. 2 is a block diagram showing the configuration of an image forming system using the radiation image intensifier configured in FIG. 1, and FIG. FIG. 3 is a waveform diagram for explaining the operation. 1: Vacuum container 2: Phosphor layer 3: Electron multiplication mechanism (4... dynode, 5... output electrode) 6: Focusing electrode

Claims (3)

[Claims] (1) A phosphor layer formed of a phosphor material that absorbs radiation to form a latent image and emits exo-electrons upon optical stimulation;
Emitted from this phosphor layer1. What is claimed is: 1. A radiation image intensifier tube, comprising: an electron multiplier for multiplying electrons, and a phosphor layer and the electron multiplier are housed in a single vacuum container. (2) The electron multiplication mechanism consists of a dynode group that sequentially multiplies the electrons emitted from the phosphor layer, and an output electrode that supplements the electron flow multiplied by the dynode group.1. A radiation image intensifying tube according to claim 1, characterized in that the radiation image intensifying tube is (3) The radiation image intensifier tube according to claim 1 or 2, wherein the vacuum container has an entrance window for the light beam for scanning the phosphor layer.