JPH0982251A - X-ray fluorescent image multiplier tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray fluorescent image multiplier tube device capable of easily measuring the brightness drop of an X-ray fluorescent image multiplier tube by providing a luminous element having emitted light irradiated to an input part. SOLUTION: Voltage is applied to a luminous element 21 laid at a position faced to the photoelectric surface of an input part 14, thereby generating light 22. As a result, the light 22 passes a gap between an annular grid electrode 17 and a positive electrode 18 for irradiating a part of the photoelectric surface, thereby generating photoelectrons 23. The photoelectrons 23 so generated are incident on an output phosphor 20, converted to a visible ray image and introduced outside via an output window 19. In this case, the extent of the brightness deterioration of an X-ray fluorescent image multiplier tube can be determined by measuring the degree of a drop in the brightness level of the outputted visible ray image, provided that the light quantity of the luminous element 21 is constant. Also, the luminous element 21 preferably has such a characteristic as capable of emitting the prescribed quantity of light under the application of the preset voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray fluorescence image intensifier tube device for converting X-rays into visible light or the like.

[0002]

2. Description of the Related Art Conventionally, an X-ray fluorescence image intensifier device has been used for a radiographic device or a radiographic device for examining the internal structure of a human body or an object, and is used for measuring the concentration distribution of the radiation transmitted through the human body or the object. The corresponding radiation image is converted into a visible light image, for example.

Here, a conventional X-ray fluorescence image intensifier tube apparatus will be described with reference to the schematic structural view of FIG. Reference numeral 61 denotes a tube container, and a vacuum envelope 62 constituting an X-ray fluorescence image intensifier tube is housed in the tube container 61. The vacuum envelope 62 is formed of a glass tube or the like, and the front surface of the vacuum envelope 62 is an input window 63 made of aluminum or aluminum alloy. An input unit 64 is provided near the input window 63 inside the vacuum envelope 62.

The input section 64 converts an X-ray image incident through the input window 63 into a photoelectron image 65. The photoelectron image 65 converted by the input unit 64 is a cylindrical grid electrode 66 formed along the side wall portion inside the vacuum envelope 62, an annular grid electrode 67 formed at the other end portion, an anode 68, etc. It is accelerated and focused by. The accelerated and focused photoelectron image 65 is formed on the output phosphor 69. Output phosphor 6
9 is formed on the inner surface of the output window 70 located at the other end of the vacuum envelope 62, and converts the formed photoelectron image 65 into a visible light image. The visible light image is taken out through the output window 70. In the X-ray fluorescence image intensifier device described above, X
Photoelectrons 65 emitted from the input section 64 of the linear fluorescence image intensifier tube
Is accelerated and focused by the grid electrodes 66 and 67 and the anode 68, and collides with the output phosphor 69 to emit light.
Therefore, when the X-ray fluorescence image intensifier is used for a long time, the inner surface of the output window 70 and the phosphor 69 are burnt. Burning of the inner surface of the output window 70 and the phosphor 69 deteriorates the brightness of the visible light image output from the X-ray fluorescence image intensifier. As the brightness deteriorates, the amount of incident radiation increases in order to brighten the visible light image. For this reason, it is necessary to manage the degree of deterioration in luminance so that the amount of radiation exposed to the human body or object does not increase.

By the way, in medical diagnosis and the like, it is desired that the human body is exposed to as little radiation as possible. Therefore, when the brightness of the image output from the X-ray fluorescence image intensifier falls below a certain standard, it is replaced with a new one.

[0006]

The burning of the inner surface of the output window and the phosphor is influenced by the total amount of radiation incident on the X-ray fluorescence image intensifier and the time used. For example, if the total incident dose is small, sufficient brightness is maintained even after 10 years of use. However, even if the period of use is as short as 3 months, the brightness may fall below the reference level if the total amount of incident radiation is large. Therefore, when measuring the brightness of the X-ray fluorescence image intensifier, a certain X-ray quality and X-ray dose should be specified, and the brightness of the output of the X-ray fluorescence image intensifier under the X-ray condition should be measured by a brightness meter. become. Therefore, accurate measurement of the X-ray quality and the X-ray dose is required for the measurement of such luminance. However, the X-ray quality may change due to deterioration of the surface condition of the anode of the X-ray tube. In addition, the X-ray tube voltage or tube current of the X-ray generator may change due to humidity or the like. Therefore, in reality, it is not easy to manage the degree of deterioration in the brightness of the X-ray fluorescence image intensifier.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide an X-ray fluorescence image intensifier tube device which can easily measure a decrease in the brightness of the X-ray fluorescence image intensifier tube.

[0008]

According to the present invention, an input unit for converting X-rays into photoelectrons, an electrode for accelerating and focusing the photoelectrons, and an output unit for converting the photoelectrons accelerated and focused by the electrodes into light. In an X-ray fluorescence image intensifier device including a vacuum envelope accommodating each of the input unit, the electrode unit, and the output unit, a light-emitting element is provided to irradiate the input unit with emitted light. There is.

Further, the light emitting element has a characteristic of emitting a constant amount of light when a constant voltage is applied.

Further, a light detecting means for measuring the level of the light converted at the output portion is optically connected to the side of the light passage directly or through an optical fiber.

According to the above structure, the light emitting element is provided in which the emitted light is applied to the input section. At this time, the input unit generates photoelectrons by the emitted light. The generated photoelectrons are accelerated and focused, reach the output unit, and are converted into light. Then, this optical signal is converted into, for example, a video signal of a TV camera, and the magnitude of light is detected as the level of the video signal. In this case, the magnitude of the light output from the X-ray fluorescence image intensifier is evaluated as the relative output brightness.

Therefore, for example, a light emitting element having a characteristic of emitting a constant amount of light by applying a constant voltage is used, and a constant voltage is applied to the light emitting element so that the energy and spectrum of the emitted light are always constant. By measuring the change in the magnitude of the output light in this way, the degree of deterioration of the luminance can be known without the incidence of X-rays.

According to this method, since X-rays are not required to be incident, it is possible to avoid deterioration of reliability due to the influence of X-ray quality and X-ray dose. Further, the reliability is not deteriorated due to the change of the brightness of the X-ray fluorescence image intensifier tube due to the replacement of the X-ray tube.

The light emitted from the light emitting element substitutes for the light emitted by the input phosphor of the input section of the X-ray fluorescence image intensifier. Therefore, since the emission spectrum of CsI, which is the input phosphor, has a peak near 410 nm, it is suitable that the emission spectrum of the light emitting element also has a peak near 410 nm.

According to the above-mentioned structure, the incidence of X-rays and the measurement of X-ray quality and X-ray dose are unnecessary, and
X-ray fluorescence image intensifier tube has a relative decrease in output brightness, which causes X
Since it is a method of measuring the brightness decrease of the linear fluorescence image intensifier,
It becomes easy to control the decrease in brightness of the X-ray fluorescence image intensifier.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG.

Reference numeral 11 denotes a tube container, and a vacuum envelope 12 constituting an X-ray fluorescence image intensifier tube is housed in the tube container 11.
The vacuum envelope 12 is formed of a glass tube or the like. The front surface of the vacuum envelope 12 is an input window 13,
An input unit 14 is provided near the input window 13. The input unit 14 includes the input phosphor screen layer 14 as shown in the circle in FIG.
a, the transparent conductive layer 14b, and the photocathode 14c, and the input phosphor screen layer 14a converts an X-ray image into light. The light converted by the input phosphor screen layer 14a passes through the transparent conductive layer 14b, and then converted into a photoelectron image 15 by the photocathode 14c.

Further, a cylindrical grid electrode 16 is provided along the side wall portion inside the vacuum envelope 12, and an annular grid electrode 17 is provided at the other end portion. An anode 18 is provided at the other end. An output window 19 is provided at the other end of the vacuum envelope 12, and an output phosphor 20 for converting a photoelectron image into a visible light image is formed on the inner surface of the output window 19. The visible light image converted by the output phosphor 20 is taken out from the output window 19.

A light emitting element 21 is arranged, for example, outside the vacuum envelope 12 near the circular grid electrode 17. The light emitting element 21 has a characteristic of emitting a constant amount of light when a constant voltage is applied, and the photocathode 14 of the input unit 14
It is located so as to face c.

In the above structure, when a voltage is applied to the light emitting element 21 to emit the light 22, the light 22 passes between the circular grid electrode 17 and the anode 18 and the photocathode 14 is formed.
A part of c is irradiated to generate photoelectrons 23. The generated photoelectrons 23 enter the output phosphor 20, are converted into a visible light image, and are taken out from the output window 19.

At this time, if the light amount of the light emitting element 21 is constant, the relative brightness of the X-ray fluorescence image intensifier, that is, the relative brightness of the X-ray fluorescence image intensifier tube is measured by measuring the degree of decrease in the brightness level of the output visible light image. The degree of deterioration in brightness can be measured.

As a method for measuring the brightness level of the output of the X-ray fluorescence image intensifier, a method of precisely measuring it using a luminance meter or inputting the output of the X-ray fluorescence image intensifier into a TV camera, There is a method of measuring the obtained video signal level.

In the case of the method using a TV camera, T
It is necessary to make the optical aperture of the V camera constant. But,
Recent X-ray diagnostic apparatuses and the like are provided with an automatic brightness adjusting mechanism for automatically adjusting the optical aperture of a TV camera in accordance with the brightness level of the X-ray fluorescent image intensifier. Therefore, T
When measuring the output brightness according to the video signal level obtained from the V camera, it is necessary to set the optical diaphragm so that it is not automatically adjusted.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 3 shows the output window portion of the vacuum envelope forming the X-ray fluorescence image intensifier tube.

Reference numeral 31 denotes a tube container, and a vacuum envelope 32 is housed in the tube container 31, and an output window 33 is formed in the vacuum envelope 32. The output phosphor 34 is provided on the surface of the output window 33.
And the anode 35 is located in front of the output phosphor 34. A light emitting element 36 is attached to the outer wall of the vacuum envelope 32 outside the anode 35. As the light emitting element 36, for example, a light emitting element having a characteristic capable of emitting a certain amount of light is used. Further, a photodetector 37 for detecting light passing through the output window 33 is provided on a part or the entire circumference of the side surface of the output window 33. The light detected by the photodetector 37 is sent to the meter M and its magnitude is measured.

In this case, the brightness level of the visible light image converted by the output phosphor 34 is measured by the photodetector 37 and the meter M separately from the optical system of the TV camera. As the photodetector 37, a semiconductor element such as a CCD or a photocell is used. The CCD is small, has high sensitivity and reliability, and can perform stable luminance measurement.

Even if a detector or an electron tube such as a large photomultiplier tube which has a problem with static electricity generated in the output window is optically connected to the side surface of the output window 33 by an optical fiber or the like. The effects of static electricity,
Also, the detector can be placed in another open space.

According to the above structure, the light emitted from the light emitting element 36 forms a photoelectron image from the input portion, and the photodetector 37 detects the light converted by the output phosphor 34. . Therefore, by periodically measuring the light detected by the photodetector 25 and measuring the state in which the level of the optical signal decreases, the pattern of the decrease in the brightness of the X-ray fluorescence image intensifier tube can be quantitatively detected.

Next, another embodiment of the present invention will be described with reference to FIG.

Reference numeral 41 denotes a tube container in which a vacuum envelope 42 constituting an X-ray fluorescence image intensifier tube is housed in the tube container 41.
The vacuum envelope 42 is formed of a glass tube or the like. The front surface of the vacuum envelope 42 is an input window 43,
An input unit 44 is provided near the input window 43. The input unit 44 includes an input fluorescent screen layer that converts an X-ray image into light, a photocathode that converts light into a photoelectron image, and the like. Reference numeral 45 indicates a photoelectron image output from the input unit 44.

Further, along the side wall portion inside the vacuum envelope 42, the cylindrical first grid electrode 46a and the cylindrical second grid electrode 46a are formed.
The grid electrode 46b is provided, and the annular grid electrode 47 is provided behind it. An anode 48 is provided on the other end portion. An output window 49 is provided at the other end of the vacuum envelope 42, and an output phosphor 50 that converts a photoelectron image into a visible light image is formed on the inner surface of the output window 49. The visible light image converted by the output phosphor 50 is taken out from the output window 49.

In this case, the grid electrode is divided into the cylindrical first grid electrode 46a and the cylindrical second grid electrode 46b, so that the input section 44 cannot be irradiated with sufficient light from the annular grid electrode 47 portion. There is. Therefore, for example, an opening is provided in a part of the cylindrical first grid electrode 46 a, and the light emitting element 51 a is arranged inside the vacuum envelope 42. The light emitting element 51b is arranged outside the vacuum envelope 42, and the input section 44 is irradiated with light through the gap between the first grid electrode 46a and the second grid electrode 46b. Also in this case, the light emitting elements 51a and 51b
Has a characteristic of emitting a constant amount of light when a constant voltage is applied.

In the above structure, the light emitting element 51a,
When a voltage is applied to 51b to emit light, this light irradiates the photoelectric surface of the input section 44 and generates photoelectrons. Then, the generated photoelectrons enter the output phosphor 50, are converted into a visible light image, and are taken out through the output window 49.

At this time, if the light intensity of the light emitting elements 51a and 51b is constant, the relative brightness of the X-ray fluorescence image intensifier is measured by measuring the degree of decrease in the brightness level of the visible light image to be output. That is, the degree of deterioration of brightness can be measured.

In the above embodiment, the light emitting elements 51a and 51b are provided inside and outside the vacuum envelope 42, respectively. However, the configuration may be such that only one of the two light emitting elements 51a and 51b is provided.

[0036]

According to the present invention, it is possible to realize an X-ray fluorescence image intensifier tube device capable of easily measuring the degree of deterioration of the X-ray fluorescence image intensifier tube.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of the present invention.

FIG. 2 is a schematic sectional view illustrating the present invention.

FIG. 3 is a schematic sectional view showing another embodiment of the present invention.

FIG. 4 is a schematic sectional view showing another embodiment of the present invention.

FIG. 5 is a schematic sectional view showing a conventional example.

[Explanation of symbols]

 11 ... Tube container 12 ... Vacuum envelope 13 ... Input window 14 ... Input part 15 ... Photoelectron image 16 ... Cylindrical grid 17 ... Toroidal grid 18 ... Anode 19 ... Output window 20 ... Output phosphor 21 ... Light emitting element

Claims (3)

[Claims] 1. An input unit for converting X-rays into photoelectrons, an electrode for accelerating and focusing the photoelectrons, an output unit for converting the photoelectrons accelerated and focused by the electrodes into light, the input unit and the electrode unit. And an X-ray fluorescence image intensifier tube apparatus including a vacuum envelope accommodating each of the output sections, wherein an X-ray fluorescence device is provided in which the input section is irradiated with emitted light. Image intensifier device. 2. The X-ray fluorescence image intensifier tube apparatus according to claim 1, wherein the light emitting element has a characteristic of emitting a constant amount of light when a constant voltage is applied. 3. The light detecting means for measuring the level of the light converted at the output section is optically connected to the side of the light path directly or through an optical fiber. The described X-ray fluorescence image intensifier tube apparatus.