WO2015182180A1 - Imaging tube - Google Patents

Imaging tube Download PDF

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Publication number
WO2015182180A1
WO2015182180A1 PCT/JP2015/054979 JP2015054979W WO2015182180A1 WO 2015182180 A1 WO2015182180 A1 WO 2015182180A1 JP 2015054979 W JP2015054979 W JP 2015054979W WO 2015182180 A1 WO2015182180 A1 WO 2015182180A1
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WIPO (PCT)
Prior art keywords
input
substrate
image tube
light
recess
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PCT/JP2015/054979
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French (fr)
Japanese (ja)
Inventor
隆司 野地
Original Assignee
株式会社 東芝
東芝電子管デバイス株式会社
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Application filed by 株式会社 東芝, 東芝電子管デバイス株式会社 filed Critical 株式会社 東芝
Publication of WO2015182180A1 publication Critical patent/WO2015182180A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/233—Manufacture of photoelectric screens or charge-storage screens
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/38—Photoelectric screens; Charge-storage screens not using charge storage, e.g. photo-emissive screen, extended cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/50—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output

Definitions

  • the embodiment of the present invention relates to an image tube in which an input surface is arranged in a vacuum envelope.
  • image tubes are used for medical diagnosis and industrial nondestructive inspection.
  • this image tube usually uses a system that combines an image tube and a CCD camera for imaging.
  • X-rays transmitted through the subject are converted into visible light on the input fluorescent screen provided on the input surface of the image tube, and the visible light is converted into electrons on the photocathode to electrically amplify the electrons.
  • a fluoroscopic image of the subject is obtained by converting electrons into visible light on the output phosphor screen and photographing the visible image with a CCD camera.
  • the image tube is important for performance, and it is necessary to improve resolution and brightness. Further, for the purpose of reducing X-ray exposure, the thickness of the input phosphor screen is frequently 300 to 500 ⁇ m in order to increase the X-ray absorption on the input phosphor screen.
  • the input fluorescent screen is formed on the input surface of the image tube by depositing cesium iodide (CsI) phosphor on the smooth surface of the substrate.
  • CsI cesium iodide
  • the phosphor On the input phosphor screen, the phosphor has a columnar crystal structure due to the technique of low vacuum vapor deposition or oblique vapor deposition, and minute gaps are formed between the columnar crystals. For this reason, even if the input phosphor screen is formed in a thick film by the light guide action, a certain level of resolution is obtained. However, the resolution performance is limited, and the resolution is about 0.1 mm to 0.2 mm in an image tube with a variable field of view. The main cause is that the crystal growth of the phosphor starts from the smooth surface side of the substrate, but the temperature of the substrate and the phosphor rises during the growth process, so that the columnar crystal grows as the columnar crystal grows. This is because the diameter of each book gradually increases.
  • the reflection of light due to the critical angle in the columnar crystal is reduced and the scattered light in the lateral direction is increased, and the light converted in the input phosphor screen is easily diffused widely. Further, the gap between the columnar crystals is gradually reduced, and the scattered light increases as the columnar crystal becomes thicker. As a result, the effect of the light guide is lost, and the light in the columnar crystal diffuses in the lateral direction, so the resolution decreases. This is a factor that hinders improvement in resolution, and makes observation of a minute subject difficult.
  • Such a problem is not limited to X-ray imaging for medical diagnosis, but can be similarly considered in industrial nondestructive inspection.
  • a film thickness of about 10 ⁇ m to about 2 mm is applied depending on the application, and thus the above-described phenomenon occurs in the same manner.
  • the problem to be solved by the present invention is to provide an image tube capable of improving the resolution.
  • the image tube of the present embodiment includes a vacuum envelope having an input window and an output window facing the input window, and an input surface disposed inside the input window.
  • the input surface includes a substrate having a plurality of concave portions formed on the surface, a fluorescent surface having a columnar crystal structure formed on the surface of the substrate, and a photoelectric surface formed on the fluorescent surface.
  • FIG. 1 is a cross-sectional view of an input surface of an image tube showing an embodiment.
  • FIG. 2 is a cross-sectional view of the above image tube.
  • FIGS. 3A and 3B are explanatory diagrams for comparing the propagation of light in the input surface.
  • FIG. 3A is an explanatory diagram for the input surface of this embodiment, and
  • FIG. 3B is an input surface with a smooth substrate surface. It is explanatory drawing in the case.
  • FIG. 4 is a block diagram of a radiation imaging apparatus using the same image tube.
  • FIG. 2 shows a cross-sectional view of the image tube.
  • the image tube 10 includes a vacuum envelope 11.
  • the vacuum envelope 11 has a cylindrical body portion 12, an input window 13 on one end side of the body portion 12, and an output window 14 facing the input window 13 on the other end side of the body portion 12.
  • the input window 13 is formed in a convex curved shape that protrudes toward the outside, and X-rays 15 as radiation are incident thereon, and the X-rays 15 can be transmitted.
  • an input surface 17 that converts the X-rays 15 incident from the input window 13 into electrons 16 and emits the electrons is disposed inside the input window 13, and the input surface 17 is disposed inside the output window 14.
  • An output surface 19 for converting the electrons 16 from the output 16 into a visible light image 18 and outputting the image from the output window 14 is formed.
  • a focusing electrode 21 constituting an electron lens for accelerating and focusing the electrons 16 along the path of the electrons 16 traveling from the cathode 20 including the input surface 17 toward the output surface 19, and A plurality of electrodes 23 including the anode 22 are provided.
  • the input surface 17 is formed in a convex curved shape protruding toward the input window 13 corresponding to the shape of the input window 13.
  • the output surface 19 includes an output phosphor that converts the electrons 16 into visible light.
  • FIG. 1 shows a cross-sectional view of the input surface 17.
  • the input surface 17 has a substrate 30, an input phosphor screen 31 as a phosphor screen formed on the surface 30 a of the substrate 30, and a photocathode 32 formed on the input phosphor screen 31.
  • the X-ray 15 incident from the input window 13 and transmitted through the substrate 30 is converted into light by the input phosphor screen 31, and the light from the input phosphor screen 31 is converted into electrons by the photocathode 32 and emitted toward the output surface 19. To do.
  • the substrate 30 is an aluminum substrate, for example, and is formed in a convex curved shape that protrudes toward the input window 13.
  • a plurality of recesses (concave surfaces) 33 are formed on the surface 30a of the substrate 30 on the side opposite to the input window 13, that is, the concave curved surface 30a.
  • the recessed inner surface of the recess 33 is formed as a concave curved reflecting surface 34, and the recess 33 is formed in a circular shape when viewed from the direction perpendicular to the surface 30a of the substrate 30,
  • a plurality of recesses 33 are formed continuously. Between the adjacent recesses 33, a top 35 protruding from the surface 30 a of the substrate 30 is formed.
  • the recesses 33 may have a shape other than a circle such as an ellipse, or the recesses 33 may not be continuous with each other and there may be a gap between the recesses 33.
  • the input phosphor screen 31 is formed of a CsI film 38 as a phosphor film having a columnar crystal structure having a plurality of columnar crystals 36.
  • the CsI film 38 can be formed by depositing cesium iodide (CsI) phosphor on the surface 30a of the substrate 30 and on the plurality of recesses 33 by low vacuum deposition or high vacuum oblique deposition.
  • CsI cesium iodide
  • a minute gap is formed between the plurality of columnar crystals 36. Therefore, the light generated in the columnar crystal 36 reaches the surface of the columnar crystal 36 while repeating total reflection at the boundary between the columnar crystal 36 and the gap.
  • a plurality of columnar crystals 36 are formed in one recess 33.
  • a columnar crystal 36 is not formed at the top 35 which is a boundary between the recess 33 and the recess 33 adjacent to each other, and a gap 37 is formed corresponding to the top 35 by the columnar crystals 36 competing with each other. .
  • the gap 37 extends in the direction of the surface of the input phosphor screen 31 together with the columnar crystal 36, and eventually becomes a shape such that the gap 37 is filled very close on the surface side of the input phosphor screen 31.
  • the columnar crystal 36 in the recess 33 exhibits a function like one pixel.
  • the scattering of light in the lateral direction is reduced by the columnar crystal 36 and the gap 37, and the contrast is increased by the boundary between the recess 33 and the recess 33, so that the resolution is improved overall. Will contribute.
  • the unevenness on the surface of the CsI film 38 is not greatly affected.
  • the surface of the CsI film 38 is gently uneven due to the influence of the recess 33, it becomes concave due to the effect of an electric field that allows the direction of electron emission from the photocathode 32 formed on the surface to be in the vicinity thereof. Sharp electron emission contributes to improved resolution.
  • CsI cesium iodide
  • the activator for the input phosphor screen 31 is preferably sodium iodide or thallium iodide.
  • the photocathode 32 is formed on the input phosphor screen 31 by alkali metal vacuum deposition.
  • FIG. 3 shows an explanatory diagram for comparing the propagation of light in the input surface 17.
  • FIG. 3A is an explanatory diagram in the case of the input surface 17 of the present embodiment
  • FIG. 3B is an explanatory diagram in the case of the input surface 17 having a smooth surface 30a of the substrate 30.
  • the light path 41 that does not satisfy the critical angle emitted from the light emission point 40 in the CsI film 38 propagates in the CsI film 38 in the lateral direction.
  • the light path 41 is reflected by the surface 30a of the substrate 30 and diffuses in a wide range in the lateral direction in the CsI film 38. I will do it.
  • the light path 41 hits the inclined surface of the concave portion 33 and reflects toward the surface of the CsI film 38.
  • the spread of light in the lateral direction of the CsI film 38 can be suppressed.
  • the recess 33 has, for example, a diameter of 20 ⁇ m and a depth of 3 ⁇ m. In this case, since the number of the concave portions 33 is equivalent to 50 per 1 mm scale, the resolution is 20 ⁇ m, and the resolution is improved much more than the conventional one.
  • the resolution can be prevented from being lowered by increasing the diameter of the recess 33 to, for example, 50 ⁇ m and the depth to 10 ⁇ m.
  • the diameter of the recess 33 is increased to, for example, 100 ⁇ m and the depth is increased from 10 to 15 ⁇ m, thereby preventing a decrease in resolution due to light scattering.
  • the input surface 17 capable of increasing the contrast can be obtained.
  • the level of resolution can be increased, the X-ray absorption rate can be improved (X-ray detection efficiency).
  • the diameter of the recess 33 is reduced to 20 ⁇ m and the depth is reduced to 3 ⁇ m, which contributes to improvement in resolution.
  • the concave portion 33 has a diameter of 20 ⁇ m or more and 100 ⁇ m or less and a depth of 3 ⁇ m or more and 15 ⁇ m or less according to the film thickness of the CsI film 38.
  • the film thickness of the CsI film 38 can be selected according to the application, and a range of 10 ⁇ m or more and about 2 mm or less can be applied.
  • the image tube 10 of the input surface 17 with the CsI film 38 thicker from about 1 mm is for high energy X-rays.
  • the tube voltage of the X-ray tube covers the range of 200 kV to 1 MV, such as the structure and composition in the metal. Often used for inspection.
  • the depth of the concave portion 33 depends on the formation method described later, but considering the formation of the columnar crystal 36, the mirror effect of light from the substrate 30 and the gap 37 between the concave portions 33, about 3 ⁇ m or more and 20 ⁇ m or less is effective. . Furthermore, in order to enhance the mirror effect and reflect light efficiently, the surface 30a of the substrate 30 is preferably a surface having a metallic luster of aluminum.
  • the concave portion 33 of the substrate 30 can be formed by, for example, shot blasting.
  • shot blasting a plurality of particle bodies are sprayed onto the surface 30 a of the substrate 30 to form a plurality of recesses 33.
  • a shot blasting machine capable of high-speed, short-time irradiation with a large impact is used.
  • the particles for example, particles having a particle size that does not contain specially small particles of ceramic material such as ZrO having a high hardness are used, and the particle size is, for example, 35 to 260 ⁇ m.
  • This particle size is the size obtained from the selection of the diameter and depth of the recess 33 formed by shot blasting, and is effective in each of the cases where the diameter of the recess 33 is about 20 ⁇ m and about 100 ⁇ m. is there.
  • zirconia has a true specific gravity of 3.85 (g / cm 3 )
  • stainless steel has a true specific gravity of 7.6 (g / cm 3 )
  • glass has a true specific gravity of 2.52 (g / cm 3 ).
  • Any of the particle bodies has a substantially spherical shape, and can be used by selecting conditions when forming the recess 33.
  • the particle size distribution can be selected stepwise. For example, in the case of zirconia, a range of 250 to 120 ⁇ m is suitable.
  • Zirconia is suitable for processing quality and long-term use because of less damage and wear of particles.
  • the stainless sphere has a glossy surface and excellent flatness. Since there is little damage to the surface of the aluminum to be processed, the light reflection of the aluminum substrate is not significantly reduced, which is effective in improving the luminance. In this case, since the collision energy is high, the setting range of the processing conditions is narrowed, and therefore a device for the uniform processing method of the curved aluminum substrate is required.
  • the concave portion 33 can be formed in a wide area by making the shape of the nozzle for projecting the particle body a wide angle.
  • the substrate 30 In order to form the particles with a small number of sprays, it is preferable to heat-treat the substrate 30 in advance.
  • the aluminum plate is processed into a thin plate by rolling and press-molded to form the substrate 30.
  • the aluminum structure in this state becomes linear crystals by rolling, the surface appearance is streaked, and the hardness varies.
  • the aluminum is recrystallized to form a crystal form, and the hardness is softened, so that there is an advantage that a uniform aluminum surface can be obtained.
  • This method is effective when processing the surface of the substrate 30 with the shape of the recess 33 aligned.
  • a hard alumina layer is formed on the aluminum surface used for the substrate 30, it is effective to improve the workability by removing the alumina layer with an alkali or the like.
  • the recesses 33 are not circular but have an oval shape as viewed from the direction perpendicular to the surface 30a of the substrate 30, or the recesses 33 are not continuous with each other and there is a gap between the recesses 33. In other words, there may be a crater-shaped recess 33.
  • the shape of the concave portion 33 is determined depending on how the particle bodies collide, even if there are non-perfect circular portions among the many concave portions 33, the effect is the same.
  • FIG. 4 shows a configuration diagram of the radiation imaging apparatus 50 using the image tube 10.
  • the radiation imaging apparatus 50 is, for example, an X-ray apparatus. 4 is a subject such as a human body or various articles. The subject 51 is irradiated with X-rays 15 from a radiation source 52.
  • the X-ray 15 absorbed or scattered by the subject 51 enters the input surface 17 from the input window 13 of the image tube 10.
  • the X-ray 15 is converted into light at the input phosphor screen 31 of the input surface 17 and the light is converted into electrons 16 at the photocathode 32.
  • the electrons 16 are accelerated and focused, and enter the output phosphor screen of the output surface 19.
  • the electrons 16 are converted into visible light on the output fluorescent screen of the output surface 19, and a visible light image 18 is output to the output window 14.
  • the visible light image 18 in the output window 14 is captured by the CCD camera 54 through the optical system 53 and displayed on the monitor 55.
  • the image tube 10 of the present embodiment is configured such that an image with an appropriate resolution can be obtained by one imaging by adjusting the thickness of the input phosphor screen 31 according to the subject and the subject. .
  • the medical image tube 10 it is possible to achieve both a thick film with enhanced X-ray absorption in the CsI film 38 and a high resolution that enables fine angiography.
  • the industrial image tube 10 can be applied to a wide range of applications such as incident energy of soft X-rays to high energy X-rays and neutron beams.
  • An image obtained with a neutron beam that requires observation and analysis of a fine part has a higher resolution, and is suitable for realizing a resolution of about 10 ⁇ m.
  • the image tube 10 has a higher resolution than the conventional image tube, the amount of information from the obtained image is large, and a portion or a minute portion of a subject having a different thickness is reproduced on the image. can do. Therefore, for medical use, the necessary input X-rays can be reduced to the required amount with the thick film while maintaining a higher resolution than before in the same subject, which is effective in reducing the exposure X-ray dose to the subject and the operator. Become. Therefore, in various types of radiography including medical diagnostic radiography and wide industrial examination, it is possible to increase examination information and improve examination accuracy.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)

Abstract

This imaging tube comprises a vacuum envelope having an input window and an output window facing the input window, and an input surface (17) disposed on the inner side of the input window. The input surface (17) is provided with a substrate (30) with a surface (30a) on which a plurality of concave portions (33) are formed, an input fluorescent surface (31) with a columnar crystal (36) structure formed on the surface (30a) of the substrate (30), and a photoelectric surface (32) formed on the input fluorescent surface (31). As a result, an imaging tube having a higher resolution than in prior art can be achieved.

Description

イメージ管Image tube
　本発明の実施形態は、真空外囲器内に入力面が配置されたイメージ管に関する。 The embodiment of the present invention relates to an image tube in which an input surface is arranged in a vacuum envelope.
　従来、イメージ管は、医療診断や工業用非破壊検査などに利用されている。このイメージ管は、通常、撮影系の感度を向上させるために、撮像にイメージ管とＣＣＤカメラとを組み合わせたシステムが使用されている。その撮影においては、被検体を透過したＸ線をイメージ管の入力面が備える入力蛍光面で可視光に変換されるとともに光電面でその可視光を電子に変換し、電子を電気的に増幅し、出力蛍光面で電子を可視光に変換し、その可視画像をＣＣＤカメラで撮影することで、被検体の透視画像を得ている。 Conventionally, image tubes are used for medical diagnosis and industrial nondestructive inspection. In order to improve the sensitivity of the photographing system, this image tube usually uses a system that combines an image tube and a CCD camera for imaging. In the imaging, X-rays transmitted through the subject are converted into visible light on the input fluorescent screen provided on the input surface of the image tube, and the visible light is converted into electrons on the photocathode to electrically amplify the electrons. A fluoroscopic image of the subject is obtained by converting electrons into visible light on the output phosphor screen and photographing the visible image with a CCD camera.
　イメージ管は、医療用の場合、性能が重視され、分解能、輝度の向上が必要になっている。さらに、Ｘ線被曝の低減を目的とし、入力蛍光面でのＸ線吸収を高めるために入力蛍光面の膜厚は３００～５００μｍが多用されている。 In the case of medical use, the image tube is important for performance, and it is necessary to improve resolution and brightness. Further, for the purpose of reducing X-ray exposure, the thickness of the input phosphor screen is frequently 300 to 500 μm in order to increase the X-ray absorption on the input phosphor screen.
　イメージ管の入力面には、基板の平滑な表面にヨウ化セシウム（ＣｓＩ）蛍光体が蒸着されることで、入力蛍光面が形成されている。 The input fluorescent screen is formed on the input surface of the image tube by depositing cesium iodide (CsI) phosphor on the smooth surface of the substrate.
　入力蛍光面においては、低真空蒸着や斜め蒸着の技術により、蛍光体が柱状結晶構造になり、その柱状結晶の間に微小な隙間が形成される。このことから、光ガイド作用によって入力蛍光面を厚膜に形成しても、分解能はある程度の性能が得られている。しかし、分解能の性能には限界があり、視野可変型のイメージ管において０．１ｍｍ～０．２ｍｍ程度の分解能である。その主な原因は、蛍光体の結晶成長は基板の平滑な表面側から始まるが、その成長の過程で基板および蛍光体の温度上昇が発生するため、柱状結晶の成長が進むにつれて柱状結晶の１本毎の径が徐々に大きくなるためである。 On the input phosphor screen, the phosphor has a columnar crystal structure due to the technique of low vacuum vapor deposition or oblique vapor deposition, and minute gaps are formed between the columnar crystals. For this reason, even if the input phosphor screen is formed in a thick film by the light guide action, a certain level of resolution is obtained. However, the resolution performance is limited, and the resolution is about 0.1 mm to 0.2 mm in an image tube with a variable field of view. The main cause is that the crystal growth of the phosphor starts from the smooth surface side of the substrate, but the temperature of the substrate and the phosphor rises during the growth process, so that the columnar crystal grows as the columnar crystal grows. This is because the diameter of each book gradually increases.
　そのため、柱状結晶内の臨界角による光の反射が減少して横方向への散乱光が増加し、入力蛍光面内で変換された光は広く拡散しやすくなる。また、柱状結晶間の隙間は徐々に小さくなり、柱状結晶が厚膜になるほど、散乱光が増加してしまう。その結果、光ガイドの効果はなくなり、柱状結晶内の光が横方向に拡散していくので、分解能は低下していくことになる。これが分解能の向上を妨げる要因になっているので、微小な被検体の観察を難しくしている。 Therefore, the reflection of light due to the critical angle in the columnar crystal is reduced and the scattered light in the lateral direction is increased, and the light converted in the input phosphor screen is easily diffused widely. Further, the gap between the columnar crystals is gradually reduced, and the scattered light increases as the columnar crystal becomes thicker. As a result, the effect of the light guide is lost, and the light in the columnar crystal diffuses in the lateral direction, so the resolution decreases. This is a factor that hinders improvement in resolution, and makes observation of a minute subject difficult.
　このような問題は、医療診断用のＸ線撮影に限らず、工業用の非破壊検査においても同様に考えられる。工業用はその用途により入力蛍光面の膜厚は１０μｍから約２ｍｍ程度が適用されるので、上述した現象が同様に発生することになる。 Such a problem is not limited to X-ray imaging for medical diagnosis, but can be similarly considered in industrial nondestructive inspection. For industrial use, a film thickness of about 10 μm to about 2 mm is applied depending on the application, and thus the above-described phenomenon occurs in the same manner.
特開２０１１－４４３８５号公報JP 2011-44385 A 米国特許第４４３７０１１号明細書U.S. Pat. No. 4,437,011 米国特許第３８２５７６３Ａ号明細書US Pat. No. 3,825,763A
　上述したように、従来のイメージ管においては、分解能を向上させることが困難になっている。 As described above, it is difficult to improve the resolution in the conventional image tube.
　本発明が解決しようとする課題は、分解能を向上できるイメージ管を提供することである。 The problem to be solved by the present invention is to provide an image tube capable of improving the resolution.
　本実施形態のイメージ管は、入力窓およびこの入力窓と対向する出力窓を有する真空外囲器と、入力窓の内側に配置される入力面とを備える。入力面は、表面に複数の凹部が形成された基板と、基板の表面に形成された柱状結晶構造の蛍光面と、蛍光面上に形成された光電面とを備える。 The image tube of the present embodiment includes a vacuum envelope having an input window and an output window facing the input window, and an input surface disposed inside the input window. The input surface includes a substrate having a plurality of concave portions formed on the surface, a fluorescent surface having a columnar crystal structure formed on the surface of the substrate, and a photoelectric surface formed on the fluorescent surface.
図１は、一実施形態を示すイメージ管の入力面の断面図である。FIG. 1 is a cross-sectional view of an input surface of an image tube showing an embodiment. 図２は、同上イメージ管の断面図である。FIG. 2 is a cross-sectional view of the above image tube. 図３は、同上入力面内での光の伝搬を比較する説明図であり、（ａ）は本実施形態の入力面の場合の説明図、（ｂ）は基板の表面が平滑な入力面の場合の説明図である。FIGS. 3A and 3B are explanatory diagrams for comparing the propagation of light in the input surface. FIG. 3A is an explanatory diagram for the input surface of this embodiment, and FIG. 3B is an input surface with a smooth substrate surface. It is explanatory drawing in the case. 図４は、同上イメージ管を用いた放射線撮影装置の構成図である。FIG. 4 is a block diagram of a radiation imaging apparatus using the same image tube.
　以下、一実施形態を、図１ないし図４を参照して説明する。 Hereinafter, an embodiment will be described with reference to FIGS. 1 to 4.
　図２にイメージ管の断面図を示す。イメージ管１０は、真空外囲器１１を備えている。真空外囲器１１は、円筒状の胴部１２、胴部１２の一端側の入力窓１３、および胴部１２の他端側で入力窓１３と対向する出力窓１４を有している。入力窓１３は、外側に向けて突出する凸曲面状に形成されており、放射線としてのＸ線１５が入射し、このＸ線１５を透過可能とする。 Figure 2 shows a cross-sectional view of the image tube. The image tube 10 includes a vacuum envelope 11. The vacuum envelope 11 has a cylindrical body portion 12, an input window 13 on one end side of the body portion 12, and an output window 14 facing the input window 13 on the other end side of the body portion 12. The input window 13 is formed in a convex curved shape that protrudes toward the outside, and X-rays 15 as radiation are incident thereon, and the X-rays 15 can be transmitted.
　真空外囲器１１内には、入力窓１３の内側にその入力窓１３から入射したＸ線１５を電子１６に変換して放出する入力面１７が設置され、出力窓１４の内側に入力面１７からの電子１６を可視光像１８に変換して出力窓１４から出力する出力面１９が形成されている。さらに、真空外囲器１１内には、入力面１７を含む陰極２０から出力面１９に向かって進行する電子１６の進路に沿って電子１６を加速および集束する電子レンズを構成する集束電極２１および陽極２２を含む複数の電極２３が設置されている。入力面１７は、入力窓１３の形状に対応して、入力窓１３に向けて突出する凸曲面状に形成されている。出力面１９は、電子１６を可視光に変換する出力蛍光体を備えている。 In the vacuum envelope 11, an input surface 17 that converts the X-rays 15 incident from the input window 13 into electrons 16 and emits the electrons is disposed inside the input window 13, and the input surface 17 is disposed inside the output window 14. An output surface 19 for converting the electrons 16 from the output 16 into a visible light image 18 and outputting the image from the output window 14 is formed. Further, in the vacuum envelope 11, a focusing electrode 21 constituting an electron lens for accelerating and focusing the electrons 16 along the path of the electrons 16 traveling from the cathode 20 including the input surface 17 toward the output surface 19, and A plurality of electrodes 23 including the anode 22 are provided. The input surface 17 is formed in a convex curved shape protruding toward the input window 13 corresponding to the shape of the input window 13. The output surface 19 includes an output phosphor that converts the electrons 16 into visible light.
　次に、図１に入力面１７の断面図を示す。入力面１７は、基板３０、この基板３０の表面３０ａに形成された蛍光面としての入力蛍光面３１、およびこの入力蛍光面３１上に形成された光電面３２を有している。入力窓１３から入射して基板３０を透過したＸ線１５を入力蛍光面３１で光に変換し、入力蛍光面３１からの光を光電面３２で電子に変換して出力面１９へ向けて放出する。 Next, FIG. 1 shows a cross-sectional view of the input surface 17. The input surface 17 has a substrate 30, an input phosphor screen 31 as a phosphor screen formed on the surface 30 a of the substrate 30, and a photocathode 32 formed on the input phosphor screen 31. The X-ray 15 incident from the input window 13 and transmitted through the substrate 30 is converted into light by the input phosphor screen 31, and the light from the input phosphor screen 31 is converted into electrons by the photocathode 32 and emitted toward the output surface 19. To do.
　基板３０は、例えばアルミニウム基板であり、入力窓１３に向けて突出する凸曲面状に形成されている。入力窓１３とは反対側となる基板３０の表面３０ａすなわち凹曲面状の表面３０ａには複数の凹部（凹面）３３が形成されている。本実施形態では、凹部３３の窪んだ内面は、凹曲面状の反射面３４に形成され、さらに、凹部３３は、基板３０の表面３０ａに垂直な方向から見て円形に形成されているとともに、複数の凹部３３が連続して形成されている。隣り合う凹部３３間には、基板３０の表面３０ａから突出する頂部３５が形成されている。なお、凹部３３は、形成方法によって、楕円形など円形以外の形状となったり、凹部３３同士が連続せずに凹部３３間に間隔があく場合もある。 The substrate 30 is an aluminum substrate, for example, and is formed in a convex curved shape that protrudes toward the input window 13. A plurality of recesses (concave surfaces) 33 are formed on the surface 30a of the substrate 30 on the side opposite to the input window 13, that is, the concave curved surface 30a. In the present embodiment, the recessed inner surface of the recess 33 is formed as a concave curved reflecting surface 34, and the recess 33 is formed in a circular shape when viewed from the direction perpendicular to the surface 30a of the substrate 30, A plurality of recesses 33 are formed continuously. Between the adjacent recesses 33, a top 35 protruding from the surface 30 a of the substrate 30 is formed. Depending on the formation method, the recesses 33 may have a shape other than a circle such as an ellipse, or the recesses 33 may not be continuous with each other and there may be a gap between the recesses 33.
　また、入力蛍光面３１は、複数の柱状結晶３６を有する柱状結晶構造の蛍光体膜としてのＣｓＩ膜３８によって形成されている。ＣｓＩ膜３８は、基板３０の表面３０ａ上であって複数の凹部３３上に、ヨウ化セシウム（ＣｓＩ）蛍光体を低真空蒸着や高真空の斜め蒸着することにより形成することができる。 The input phosphor screen 31 is formed of a CsI film 38 as a phosphor film having a columnar crystal structure having a plurality of columnar crystals 36. The CsI film 38 can be formed by depositing cesium iodide (CsI) phosphor on the surface 30a of the substrate 30 and on the plurality of recesses 33 by low vacuum deposition or high vacuum oblique deposition.
　複数の柱状結晶３６の間には微小な隙間が形成されている。そのため、柱状結晶３６内で発生した光は、柱状結晶３６と隙間との境界で全反射を繰り返しながら柱状結晶３６の表面に到達する。 A minute gap is formed between the plurality of columnar crystals 36. Therefore, the light generated in the columnar crystal 36 reaches the surface of the columnar crystal 36 while repeating total reflection at the boundary between the columnar crystal 36 and the gap.
　１個の凹部３３の中には複数個の柱状結晶３６が形成されている。互いに隣接する凹部３３と凹部３３との境界である頂部３５には、柱状結晶３６は形成されず、その頂部３５に対応して柱状結晶３６同士が競合してできた隙間３７が形成されている。この隙間３７は、柱状結晶３６とともに入力蛍光面３１の表面方向に伸びていき、やがて入力蛍光面３１の表面側で極めて近接して、その隙間３７が埋められたような形状になる。 A plurality of columnar crystals 36 are formed in one recess 33. A columnar crystal 36 is not formed at the top 35 which is a boundary between the recess 33 and the recess 33 adjacent to each other, and a gap 37 is formed corresponding to the top 35 by the columnar crystals 36 competing with each other. . The gap 37 extends in the direction of the surface of the input phosphor screen 31 together with the columnar crystal 36, and eventually becomes a shape such that the gap 37 is filled very close on the surface side of the input phosphor screen 31.
　凹部３３毎に凹部３３の周囲に隙間３７が形成されることにより、凹部３３内の柱状結晶３６はいわば１画素のような機能を発揮することになる。 By forming the gap 37 around the recess 33 for each recess 33, the columnar crystal 36 in the recess 33 exhibits a function like one pixel.
　したがって、入力蛍光面３１内では、柱状結晶３６および隙間３７によって光の横方向への散乱が低減され、かつ凹部３３と凹部３３との境界によりコントラストが高くなるので、総合して分解能の向上に寄与することになる。 Therefore, in the input phosphor screen 31, the scattering of light in the lateral direction is reduced by the columnar crystal 36 and the gap 37, and the contrast is increased by the boundary between the recess 33 and the recess 33, so that the resolution is improved overall. Will contribute.
　ＣｓＩ膜３８の全体の膜厚に比較して凹部３３の深さは小さいため、ＣｓＩ膜３８の表面の凹凸には大きな影響を与えない。凹部３３の影響でＣｓＩ膜３８の表面に緩やかな凹凸ができている場合は、その表面に形成される光電面３２からの電子放出の向きがその近傍にできる電界の効果により凹状になり、よりシャープな電子放出になるので解像度向上に寄与することになる。 Since the depth of the concave portion 33 is smaller than the total film thickness of the CsI film 38, the unevenness on the surface of the CsI film 38 is not greatly affected. When the surface of the CsI film 38 is gently uneven due to the influence of the recess 33, it becomes concave due to the effect of an electric field that allows the direction of electron emission from the photocathode 32 formed on the surface to be in the vicinity thereof. Sharp electron emission contributes to improved resolution.
　柱状結晶３６上には高真空による多方向成長するヨウ化セシウム（ＣｓＩ）蛍光体層が形成されている。 On the columnar crystal 36, a cesium iodide (CsI) phosphor layer that is grown in multiple directions by high vacuum is formed.
　なお、入力蛍光面３１の活性剤はヨウ化ナトリウムやヨウ化タリウムが好ましい。 The activator for the input phosphor screen 31 is preferably sodium iodide or thallium iodide.
　また、光電面３２は、アルカリ金属の真空蒸着により入力蛍光面３１上に形成されている。 The photocathode 32 is formed on the input phosphor screen 31 by alkali metal vacuum deposition.
　次に、図３に入力面１７内での光の伝搬を比較する説明図を示す。図３（ａ）は本実施形態の入力面１７の場合の説明図、図３（ｂ）は基板３０の表面３０ａが平滑な入力面１７の場合の説明図である。 Next, FIG. 3 shows an explanatory diagram for comparing the propagation of light in the input surface 17. FIG. 3A is an explanatory diagram in the case of the input surface 17 of the present embodiment, and FIG. 3B is an explanatory diagram in the case of the input surface 17 having a smooth surface 30a of the substrate 30.
　ＣｓＩ膜３８内の光の発光点４０から出た臨界角を満たさない光のパス４１はＣｓＩ膜３８内を横方向に伝搬する。 The light path 41 that does not satisfy the critical angle emitted from the light emission point 40 in the CsI film 38 propagates in the CsI film 38 in the lateral direction.
　このとき、図３（ｂ）のように、基板３０の表面３０ａが平滑であると、光のパス４１は基板３０の表面３０ａで反射して、ＣｓＩ膜３８内の横方向の広い範囲に拡散していく。 At this time, if the surface 30a of the substrate 30 is smooth as shown in FIG. 3B, the light path 41 is reflected by the surface 30a of the substrate 30 and diffuses in a wide range in the lateral direction in the CsI film 38. I will do it.
　これに対して、図３（ａ）のように、基板３０の表面３０ａに凹部３３が形成されていると、光のパス４１は凹部３３の斜面に当たってＣｓＩ膜３８の表面方向へ反射するので、ＣｓＩ膜３８の横方向への光の広がりを抑制することができる。 On the other hand, as shown in FIG. 3A, when the concave portion 33 is formed on the surface 30a of the substrate 30, the light path 41 hits the inclined surface of the concave portion 33 and reflects toward the surface of the CsI film 38. The spread of light in the lateral direction of the CsI film 38 can be suppressed.
　このため、柱状結晶３６内のライトガイド効果、および凹部３３と凹部３３との境界部でのライトガイド効果と相俟って、ＣｓＩ膜３８の横方向への光の広がり抑制効果により光が集光されるため、分解能の向上が大きくなる。 Therefore, combined with the light guide effect in the columnar crystal 36 and the light guide effect at the boundary between the concave portion 33 and the concave portion 33, light is collected by the effect of suppressing the spread of light in the lateral direction of the CsI film 38. Since the light is emitted, the resolution is greatly improved.
　凹部３３は、例えば、直径が２０μｍ、深さが３μｍである。この場合、凹部３３は１ｍｍスケール当たり５０個相当になるので、分解能は２０μｍになり、従来よりもはるかに分解能が向上する。 The recess 33 has, for example, a diameter of 20 μm and a depth of 3 μm. In this case, since the number of the concave portions 33 is equivalent to 50 per 1 mm scale, the resolution is 20 μm, and the resolution is improved much more than the conventional one.
　ＣｓＩ膜３８の膜厚が厚い場合には、凹部３３の径を例えば５０μｍ、深さを１０μｍに大きくすることにより、分解能の低下を防ぐことができる。 When the film thickness of the CsI film 38 is thick, the resolution can be prevented from being lowered by increasing the diameter of the recess 33 to, for example, 50 μm and the depth to 10 μm.
　さらに、ＣｓＩ膜の膜厚が厚い場合には、凹部３３の径を例えば１００μｍ、深さを１０から１５μｍに大きくすることにより、光の散乱による分解能の低下を防ぐ。また、１００μｍに位置する頂部３５に形成される隙間３７での光の反射により、横方向への光の散乱が防がれるため、コントラストを高めることが可能な入力面１７を得ることができる。これにより、分解能のレベルを高めることができるので、Ｘ線の吸収率の向上（Ｘ線検出効率）を図ることができる。また、高エネルギーＸ線の吸収効率が良く、分解能が高いイメージ管１０を得ることができる。 Furthermore, when the CsI film is thick, the diameter of the recess 33 is increased to, for example, 100 μm and the depth is increased from 10 to 15 μm, thereby preventing a decrease in resolution due to light scattering. Further, since light is scattered in the lateral direction by reflection of light at the gap 37 formed in the top portion 35 located at 100 μm, the input surface 17 capable of increasing the contrast can be obtained. Thereby, since the level of resolution can be increased, the X-ray absorption rate can be improved (X-ray detection efficiency). In addition, it is possible to obtain the image tube 10 with high energy X-ray absorption efficiency and high resolution.
　ＣｓＩ膜３８が１００μｍ以下の薄い場合には、凹部３３の径を２０μｍ、深さを３μｍに小さくすることにより、分解能の向上に寄与する。 When the CsI film 38 is as thin as 100 μm or less, the diameter of the recess 33 is reduced to 20 μm and the depth is reduced to 3 μm, which contributes to improvement in resolution.
　したがって、凹部３３は、ＣｓＩ膜３８の膜厚に応じて、直径が２０μｍ以上かつ１００μｍ以下、深さが３μｍ以上かつ１５μｍ以下の範囲にあることが好ましい。 Therefore, it is preferable that the concave portion 33 has a diameter of 20 μm or more and 100 μm or less and a depth of 3 μm or more and 15 μm or less according to the film thickness of the CsI film 38.
　また、ＣｓＩ膜３８の膜厚は用途に応じて選定することができ、１０μｍ以上かつ約２ｍｍ以下の範囲を適応することができる。ＣｓＩ膜３８が約１ｍｍから上に厚い入力面１７のイメージ管１０は、高エネルギーＸ線用であり、Ｘ線管の管電圧では２００ｋＶから１ＭＶの範囲を対象に金属内の構造、組成などの検査に多用される。 Also, the film thickness of the CsI film 38 can be selected according to the application, and a range of 10 μm or more and about 2 mm or less can be applied. The image tube 10 of the input surface 17 with the CsI film 38 thicker from about 1 mm is for high energy X-rays. The tube voltage of the X-ray tube covers the range of 200 kV to 1 MV, such as the structure and composition in the metal. Often used for inspection.
　凹部３３の深さは、後述する形成方法に依存するが、柱状結晶３６の形成と基板３０からの光のミラー効果と凹部３３間の隙間３７を考慮すると３μｍ以上かつ２０μｍ以下程度が有効である。さらに、このミラー効果を高めて光を効率よく反射させるためには、基板３０の表面３０ａは、アルミニウムの金属光沢を有する面にすることが好ましい。 The depth of the concave portion 33 depends on the formation method described later, but considering the formation of the columnar crystal 36, the mirror effect of light from the substrate 30 and the gap 37 between the concave portions 33, about 3 μm or more and 20 μm or less is effective. . Furthermore, in order to enhance the mirror effect and reflect light efficiently, the surface 30a of the substrate 30 is preferably a surface having a metallic luster of aluminum.
　次に、基板３０の凹部３３の形成方法について説明する。 Next, a method for forming the concave portion 33 of the substrate 30 will be described.
　基板３０の凹部３３は、例えばショットブラスト加工によって形成することができる。ショットブラスト加工では、基板３０の表面３０ａに複数の粒子体を吹き付けて複数の凹部３３を形成する。ショットブラスト加工には、打撃の大きい高速短時間照射が可能なショットブラスト機が用いられる。粒子体は、硬度の高い例えばＺｒＯなどのセラミック系材料の特別に小さな粒子を含まない粒径をそろえた粒子体が使用され、その粒径は例えば３５～２６０μｍである。この粒径は、ショットブラスト加工により形成される凹部３３の直径と深さの選択から得られた大きさであり、凹部３３の直径が約２０μｍの場合と約１００μｍの場合のそれぞれにおいて効果的である。粒子体の種類としては、ジルコニアが真比重３．８５（ｇ／ｃｍ3）、ステンレスが真比重７．６（ｇ／ｃｍ3）、ガラスが真比重２．５２（ｇ／ｃｍ3）であり、いずれの粒子体もほぼ真球の形状であり、凹部３３の形成に際して条件を選択して使用できる。粒径分布は、段階的に選択が可能であり、例えばジルコニアの場合は、２５０～１２０μｍの範囲が適している。 The concave portion 33 of the substrate 30 can be formed by, for example, shot blasting. In shot blasting, a plurality of particle bodies are sprayed onto the surface 30 a of the substrate 30 to form a plurality of recesses 33. For shot blasting, a shot blasting machine capable of high-speed, short-time irradiation with a large impact is used. As the particles, for example, particles having a particle size that does not contain specially small particles of ceramic material such as ZrO having a high hardness are used, and the particle size is, for example, 35 to 260 μm. This particle size is the size obtained from the selection of the diameter and depth of the recess 33 formed by shot blasting, and is effective in each of the cases where the diameter of the recess 33 is about 20 μm and about 100 μm. is there. As the types of particles, zirconia has a true specific gravity of 3.85 (g / cm 3 ), stainless steel has a true specific gravity of 7.6 (g / cm 3 ), and glass has a true specific gravity of 2.52 (g / cm 3 ). Any of the particle bodies has a substantially spherical shape, and can be used by selecting conditions when forming the recess 33. The particle size distribution can be selected stepwise. For example, in the case of zirconia, a range of 250 to 120 μm is suitable.
　ジルコニアは、粒子の破損や摩耗が少ないため、加工の品質や長期間使用に適している。一方、ステンレス球は、その表面に光沢があり平坦度が優れている。加工されるアルミニウム表面に傷を付ける程度が少ないため、アルミニウム基板の光の反射を著しく低下させないので、輝度の向上には有効である。この場合、衝突エネルギーが高いために加工条件の設定幅が狭くなるので、湾曲したアルミニウム基板の一様な加工方法には工夫が必要であった。 Zirconia is suitable for processing quality and long-term use because of less damage and wear of particles. On the other hand, the stainless sphere has a glossy surface and excellent flatness. Since there is little damage to the surface of the aluminum to be processed, the light reflection of the aluminum substrate is not significantly reduced, which is effective in improving the luminance. In this case, since the collision energy is high, the setting range of the processing conditions is narrowed, and therefore a device for the uniform processing method of the curved aluminum substrate is required.
　このショットブラスト加工では、基板３０の表面３０ａに粒子体を多数回吹き付けると、凹部３３の境界位置が下がるため、吹付条件を選定する必要がある。また、広い面積を加工する際には、加工面の光反射の均一性が重要である。この場合、粒子体を投射するノズルの形状を広角にすることにより、広い面積に凹部３３を形成することができる。 In this shot blasting process, if the particle body is sprayed many times on the surface 30a of the substrate 30, the boundary position of the concave portion 33 is lowered, so it is necessary to select spraying conditions. Also, when processing a large area, the uniformity of light reflection on the processed surface is important. In this case, the concave portion 33 can be formed in a wide area by making the shape of the nozzle for projecting the particle body a wide angle.
　粒子体の少ない吹付回数で形成するためには、基板３０を予め熱処理し、軟化させておくことが好ましい。アルミニウムの板は圧延加工により薄板に加工され、プレス成形されて基板３０になる。この状態でのアルミニウムの組織は圧延加工により線状の結晶になり、表面の外観はすじ状になっていて硬度はバラツキがある。これを熱処理にてアニールすることによりアルミニウムは再結晶して結晶の形が形成され、しかも硬度は軟化するので均一なアルミニウムの表面を得ることができる利点がある。この方法は、基板３０の表面に凹部３３の形をそろえて加工する場合に有効である。 In order to form the particles with a small number of sprays, it is preferable to heat-treat the substrate 30 in advance. The aluminum plate is processed into a thin plate by rolling and press-molded to form the substrate 30. The aluminum structure in this state becomes linear crystals by rolling, the surface appearance is streaked, and the hardness varies. By annealing this by heat treatment, the aluminum is recrystallized to form a crystal form, and the hardness is softened, so that there is an advantage that a uniform aluminum surface can be obtained. This method is effective when processing the surface of the substrate 30 with the shape of the recess 33 aligned.
　一般に、基板３０に用いるアルミニウム表面には、硬度のあるアルミナ層が形成されているため、このアルミナ層をアルカリなどにより除去しておくことが加工性を良くすることに有効になる。 Generally, since a hard alumina layer is formed on the aluminum surface used for the substrate 30, it is effective to improve the workability by removing the alumina layer with an alkali or the like.
　なお、このような形成方法では、凹部３３は、基板３０の表面３０ａに垂直な方向から見て円形以外に楕円形などになったり、凹部３３同士が連続せずに凹部３３間に間隔があいていわばクレーター状の凹部３３となる場合もある。また、粒子体の衝突の仕方で凹部３３の形状は決まるので、多数の凹部３３の中では完全な円形でない部分があっても効果は同等になる。 In such a formation method, the recesses 33 are not circular but have an oval shape as viewed from the direction perpendicular to the surface 30a of the substrate 30, or the recesses 33 are not continuous with each other and there is a gap between the recesses 33. In other words, there may be a crater-shaped recess 33. In addition, since the shape of the concave portion 33 is determined depending on how the particle bodies collide, even if there are non-perfect circular portions among the many concave portions 33, the effect is the same.
　また、図４にイメージ管１０を用いた放射線撮影装置５０の構成図を示す。 FIG. 4 shows a configuration diagram of the radiation imaging apparatus 50 using the image tube 10.
　放射線撮影装置５０は、例えばレントゲン装置である。図４の５１は人体や各種物品などの被検体であり、この被検体５１に対して放射線源５２からＸ線１５が照射される。 The radiation imaging apparatus 50 is, for example, an X-ray apparatus. 4 is a subject such as a human body or various articles. The subject 51 is irradiated with X-rays 15 from a radiation source 52.
　被検体５１により吸収もしくは散乱されたＸ線１５は、イメージ管１０の入力窓１３から入力面１７に入射される。入力面１７の入力蛍光面３１でＸ線１５が光に変換されるとともに光電面３２で光が電子１６に変換される。電子１６は、加速、集束されて出力面１９の出力蛍光面に入射される。出力面１９の出力蛍光面で電子１６を可視光に変換し、出力窓１４に可視光像１８が出力される。 The X-ray 15 absorbed or scattered by the subject 51 enters the input surface 17 from the input window 13 of the image tube 10. The X-ray 15 is converted into light at the input phosphor screen 31 of the input surface 17 and the light is converted into electrons 16 at the photocathode 32. The electrons 16 are accelerated and focused, and enter the output phosphor screen of the output surface 19. The electrons 16 are converted into visible light on the output fluorescent screen of the output surface 19, and a visible light image 18 is output to the output window 14.
　出力窓１４の可視光像１８を光学系５３を通してＣＣＤカメラ５４で撮像し、モニタ５５に表示する。 The visible light image 18 in the output window 14 is captured by the CCD camera 54 through the optical system 53 and displayed on the monitor 55.
　本実施形態のイメージ管１０は、被検者や被検体に応じて入力蛍光面３１の厚さを調整することで、１回の撮影で適切な分解能の画像が得られるようにしたものである。医療用のイメージ管１０においては、ＣｓＩ膜３８でのＸ線吸収を高めた厚膜にすることと、微細な血管撮影を可能にする高分解能とを両立することができる。工業用のイメージ管１０においては、入射エネルギーが軟Ｘ線から高エネルギーＸ線のもの、さらに中性子線用などの広い用途に適応可能である。微細部の観察解析が求められる中性子線で得られる画像は、より高分解能になり、分解能が１０μｍ程度を実現するのに好適である。 The image tube 10 of the present embodiment is configured such that an image with an appropriate resolution can be obtained by one imaging by adjusting the thickness of the input phosphor screen 31 according to the subject and the subject. . In the medical image tube 10, it is possible to achieve both a thick film with enhanced X-ray absorption in the CsI film 38 and a high resolution that enables fine angiography. The industrial image tube 10 can be applied to a wide range of applications such as incident energy of soft X-rays to high energy X-rays and neutron beams. An image obtained with a neutron beam that requires observation and analysis of a fine part has a higher resolution, and is suitable for realizing a resolution of about 10 μm.
　以上のように、イメージ管１０は、従来のイメージ管に比較して高い分解能のため、得られる画像からの情報量が多く、より厚さの異なる被写体の部位や微小な部位を画像上に再現することができる。このため、医療用では同一被写体において従来よりも高分解能を維持しつつ厚膜により必要な入力Ｘ線を所要量に引き下げることができ、被検者や操作者に対する被曝Ｘ線量の低減に有効になる。したがって、医療診断用放射線撮影や広い工業用の検査をはじめとする各種の放射線撮影において、検査情報の増大、検査精度の向上などを図ることが可能となる。 As described above, since the image tube 10 has a higher resolution than the conventional image tube, the amount of information from the obtained image is large, and a portion or a minute portion of a subject having a different thickness is reproduced on the image. can do. Therefore, for medical use, the necessary input X-rays can be reduced to the required amount with the thick film while maintaining a higher resolution than before in the same subject, which is effective in reducing the exposure X-ray dose to the subject and the operator. Become. Therefore, in various types of radiography including medical diagnostic radiography and wide industrial examination, it is possible to increase examination information and improve examination accuracy.
　本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら新規な実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれるとともに、特許請求の範囲に記載された発明とその均等の範囲に含まれる。 Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.
　１０…イメージ管、１１…真空外囲器、１３…入力窓、１４…出力窓、１７…入力面、３０…基板、３０ａ…表面、３１…蛍光面としての入力蛍光面、３２…光電面、３３…凹部、３５…頂部、３６…柱状結晶、３７…隙間。 DESCRIPTION OF SYMBOLS 10 ... Image tube, 11 ... Vacuum envelope, 13 ... Input window, 14 ... Output window, 17 ... Input surface, 30 ... Substrate, 30a ... Surface, 31 ... Input fluorescent screen as fluorescent screen, 32 ... Photocathode, 33 ... concave, 35 ... top, 36 ... columnar crystal, 37 ... gap.

Claims (6)

  1. 　入力窓およびこの入力窓と対向する出力窓を有する真空外囲器と、前記入力窓の内側に配置される入力面とを備えるイメージ管であって、
    　前記入力面は、表面に複数の凹部が形成された基板と、この基板の表面に形成された柱状結晶構造の蛍光面と、この蛍光面上に形成された光電面とを備える
    　イメージ管。     An image tube comprising: a vacuum envelope having an input window and an output window facing the input window; and an input surface disposed inside the input window,
    The input surface includes an image tube including a substrate having a plurality of recesses formed on a surface thereof, a phosphor screen having a columnar crystal structure formed on the surface of the substrate, and a photocathode formed on the phosphor screen.
  2. 　前記凹部は、直径が２０μｍ以上かつ１００μｍ以下、深さが３μｍ以上かつ１５μｍ以下である
    　請求項１のイメージ管。     The image tube according to claim 1, wherein the recess has a diameter of 20 μm to 100 μm and a depth of 3 μm to 15 μm.
  3. 　前記凹部は、ブラスト加工によって形成されている
    　請求項１のイメージ管。     The image tube according to claim 1, wherein the recess is formed by blasting.
  4. 　前記基板は、隣り合う前記凹部間に前記基板の表面から突出する頂部が形成され、
    　前記蛍光面は、前記頂部に対応して柱状結晶間に隙間が形成されている
    　請求項１のイメージ管。     The substrate is formed with a top portion protruding from the surface of the substrate between the adjacent recesses,
    The image tube according to claim 1, wherein a gap is formed between the columnar crystals on the phosphor screen corresponding to the top.
  5. 　前記凹部は、直径が２０μｍ以上かつ１００μｍ以下、深さが３μｍ以上かつ１５μｍ以下である
    　請求項４のイメージ管。     The image tube according to claim 4, wherein the recess has a diameter of 20 μm to 100 μm and a depth of 3 μm to 15 μm.
  6. 　前記凹部は、ブラスト加工によって形成されている
    　請求項４のイメージ管。     The image tube according to claim 4, wherein the concave portion is formed by blasting.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55150535A (en) * 1979-05-11 1980-11-22 Shimadzu Corp Input fluorescent screen for x-ray image tube
JPS5765654A (en) * 1980-10-08 1982-04-21 Toshiba Corp Input face for image multiplier tube
JPS5782940A (en) * 1980-11-12 1982-05-24 Toshiba Corp Input screen for radiant ray image intensifying tube
JPH06236742A (en) * 1991-10-31 1994-08-23 Thomson Tubes Electron Radioactive ray image reinforcing pipe
WO1998012731A1 (en) * 1996-09-18 1998-03-26 Kabushiki Kaisha Toshiba X-ray image tube and method for manufacturing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55150535A (en) * 1979-05-11 1980-11-22 Shimadzu Corp Input fluorescent screen for x-ray image tube
JPS5765654A (en) * 1980-10-08 1982-04-21 Toshiba Corp Input face for image multiplier tube
JPS5782940A (en) * 1980-11-12 1982-05-24 Toshiba Corp Input screen for radiant ray image intensifying tube
JPH06236742A (en) * 1991-10-31 1994-08-23 Thomson Tubes Electron Radioactive ray image reinforcing pipe
WO1998012731A1 (en) * 1996-09-18 1998-03-26 Kabushiki Kaisha Toshiba X-ray image tube and method for manufacturing the same

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