JPS62218887A - X-ray image receiving apparatus - Google Patents

Abstract

PURPOSE:To attain to enhance resolving power, by simple constitution such that latent images are formed to the photoconductive layers each consisting of a required number of layers laminated to both sides of a light previous substrate having light wave guides formed so as to be arranged thereto and scanned by a detection head. CONSTITUTION:The photoconductive layer 11 comprising amorphous Se laminated to a light previous glass fiber substrate 14 having light wave guides formed so as to be arranged thereto and positively charged uniformly is irradiated with and excited by incident X-rays to form an electron hole pair. X-rays transmitted through the layer 11 transmit through a SnO2 transparent electrode layer 12a and absorbed by a CsI fluorescent layer 13 to be converted to light. A part of said X-rays is again incident to the layer 11 to again form a hole pair and the latent image corresponding to X-rays is formed to the layer 11. At the same time, the same transparent electrode layer 12a and the same photoconductive layer 15 are laminated to the opposite side of the substrate 14 and a charged latent image is formed to the layer 15 and both charged latent images are detected by the scanning of detection heads 16a, 16b. Therefore, it is unnecessary to convert the latent images to visible ones or to polarizing an electrode and the enhancement of resolving power is attained by simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an X-ray image receiving apparatus using fluorescence sensitization.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, X-ray image receiving devices have been known in which a phosphor layer and a photoconductor layer are integrated to improve X-ray detection sensitivity.

FIG. 4 shows an example of such an X-ray image receiving device, which is used for electronic X-ray photography. In the figure, 31
is a plastic substrate, on which a phosphor layer 32, a transparent electrode 33, a lower transparent insulating film 34, a photoconductor layer 35, and an upper transparent insulating film 36 are sequentially laminated. In this structure, the X-ray image is irradiated from the plastic substrate 31 side. Phosphor! ! 32, transparent electrode 33 and transparent insulating film 34
The X-rays that have passed through and reached the photoconductor layer 35 excites the photoconductor layer 35, where electron-hole pairs are generated. on the other hand,
A portion of the incident X-rays is absorbed by the phosphor layer 32 and converted into light, and this light is incident on the photoconductor layer 35. This light also excites electron-hole pairs in the photoconductor layer 35.

As a result, a charge latent image is formed on the surface of the upper transparent insulating film 36 of the photoconductor layer 35. This latent image is developed by toner, and the toner image is transferred to paper or a transparent film, etc., and transmitted X-rays are generated. You can get the image.

The conventional X-ray receiver shown in FIG. 4 utilizes a hard copy process in which toner is used to develop and transfer images. This hard copy typically has high contrast between black and white, but the intermediate layers are unclear and the resolution is low. Therefore, for example, when used for medical purposes, precise transmission
It is difficult to obtain line images. Further, in this structure, Se and a compound of Se and Te are used as the photoconductor layer 35, but although these lack mechanical strength, Se in particular has the characteristic that X-rays can be directly detected.

As a conventional X-ray detection device using the fluorescence sensitization method, one having the structure shown in FIG. 5 is also known. This is a structure in which a phosphor layer 42, a transparent electrode 43, a photoconductor layer 44, and a transparent electrode 45 are sequentially laminated on a substrate 41, and the transparent electrode 45 is a divided electrode. In this structure, the transparent electrode 4
A voltage is applied between 3 and 45, a photocurrent is extracted, and X-ray detection is performed. Therefore, in order to use this structure as an X-ray image receiving device, it is essential to segment either the transparent electrode 43 or 45. However, it is difficult to form electrodes with fine patterns to obtain sufficient resolution, especially when the image receiving area is large. Furthermore, even if a fine pattern of electrodes can be formed, a voltage must be applied to each electrode and a current from the electrodes must be detected, making the arrangement of lead wires complicated. Furthermore, the device for controlling each divided electrode also becomes complicated.

(Object of the Invention) An object of the present invention is to provide an X-ray image receiving system that solves the above-mentioned problems.

[Summary of the invention]

In the X-ray image receiving device according to the present invention, a phosphor layer, a transparent electrode, and a photoconductor layer are sequentially laminated on one surface of a transparent substrate on which a large number of optical waveguides are arranged and formed in the thickness direction. It is characterized in that an X-ray image is obtained by a configuration in which a transparent electrode and a photoconductor layer are sequentially stacked on the other side of a photoconductor, and a detection head provided on the opening side of each photoconductor. .

〔Effect of the invention〕

According to the present invention, it is possible to directly detect the X-ray image electrically compared to the case where the phenomenon is transferred using toner, and by making the detection head minute, high spatial resolution can be obtained, and the transmitted X-ray image can be detected with high resolution. A line image can be obtained. Also, unlike the current detection method, there is no need for fine pattern electrode processing.
There is no need for a complicated detection process of voltage application for current detection, nor is there a need for a detection device, nor is there any need for complicated wiring for that purpose, making it possible to improve resolution with a simple structure.

Furthermore, according to the present invention, since the two photoconductor layers and one phosphor layer can absorb all the energy of incident X-rays, the energy utilization efficiency of X-rays is greatly improved. become. That is, the X-ray detection process involves direct detection of X-rays and light detection from the phosphor in the a-Se layer, and light detection from the phosphor and direct detection of X-rays in the a-Si layer. Since X-ray energy can be detected efficiently, an X-ray image receiving device with high X-ray sensitivity can be provided. In general, energy subtraction is possible by utilizing the difference in the X-ray energy absorption spectra of the two photoconductor layers and the first phosphor layer, which is a major advantage. Since subtraction only needs to be done once, enemy shadows can be seen at low lines and in a short time.

In particular, if an amorphous material mainly composed of Si is used as the photoconductor layer, an X-ray image receiving device with high photosensitivity, high mechanical strength, and high durability can be obtained. Amorphous Si is harmless and heat resistant, making it easy to handle.

Furthermore, since the fabrication is performed in plasma, the size, shape, etc. of the substrate can be arbitrarily selected.

[Embodiments of the invention]

The present invention will be explained in detail below.

FIG. 1 shows the configuration of an X-ray image receiving apparatus according to an embodiment of the present invention. This configuration is Xi! And on one side of the glass fiber substrate 14, which is a light-transmitting substrate, a C3I layer 13 as a phosphor layer and a button layer 1 as a transparent electrode.
2 a 1 Amorphous 5e (a-3
e) The layers 11 are sequentially laminated, and a button 021112, which is a transparent electrode, is further placed on the other side of the glass fiber substrate 14.
b, amorphous 5i(a-Si)E as photoconductor layer
i15 is sequentially laminated and jq is formed. a-Se layer, C
The 3I layer is formed by vacuum evaporation.

The SnQ 2 layer is formed by vacuum evaporation or sputtering. The a-Si layer is formed by a plasma CVD method using glow discharge decomposition of 5iHq, 5i2He, etc., a photoCVD method using photoexcitation decomposition, or the like. In this example, the a-Se layer 11 is 200 μft or more, the Csl layer 13 is 100 μft or more, and the Sn02 layers 12a, 12b are
is 500 Å or more, and the a-Si layer 15 is 0.5 μm or more.

The glass fiber substrate 14 has a fiber diameter of 6 μm or more and a thickness of 1 μm or more. 16a and 16b are each a
This is a metal detection head that scans the surfaces of the -3ell 11 and the a-Si layer 15, detects the amount of charge or potential of each part of the surface, and obtains an electrical signal. Further, 17 is a subject for taking an X-ray image.

The operation of the X-ray receiving apparatus configured as described above will be explained next. Before the X-ray irradiation, the a-Se layer 11 and the a-8i
The surface of the layer 15 is uniformly charged with a positive charge by a corona charger (not shown). In this state, when X-rays (arrows) emitted from an X-ray tube (not shown) and transmitted through the subject 17 as shown enter the a-3elill, a part of the X-rays is transferred to the a-Se layer 11. is directly excited to generate electron-hole pairs. Furthermore, the X-rays transmitted through the a-Se layer 11 are
The light passes through the nO21!112a without being absorbed by it and enters the C3I layer 13. Most of the X-rays entering the C5I layer 13 are absorbed there and converted into light, and some of the light enters the a-3ellll side where electron-hole pairs are generated again. The amount of charge of the a-3e layer 11, which is pre-charged by the electron-hole pairs generated in this way, changes,
As shown in the figure, the charge latent image corresponding to the transmission XII image is a-3
It is formed on the surface of the e-layer 11. Also, C3I FJ13
Most of the light from goes straight through the glass fiber substrate 14,
It enters the a-Si layer 15 without being almost absorbed by the second SnO2 layer 12b.

When light enters the a-Sil 115, it excites the a-SR layer 15 and generates electron-hole pairs. Also, a-3e layer 11
, first and second SnO2FfN12a, 12b, C
The remaining X-rays transmitted through the 3I layer 13 and the glass fiber substrate 14 directly excite the a-Si layer 15 to generate electron-hole pairs. The electron-hole pairs generated in this way change the amount of charge on the a-Si layer 15 that has been charged in advance, and as shown in the figure, a latent charge image corresponding to the transmitted X-ray image is formed on the surface of the a-Si layer 15. It is formed.

The charge latent image obtained by such an X-ray image detection process is read as an electric signal by scanning the detection heads 16a and 16b, and subjected to signal processing to reproduce the X-ray image. The detection heads 16a and 16b may be in non-contact with the a-8e layer 11, and in either non-contact or contact with the a-Si layer 15. Also, in the figure, the detection head 16a.

Although only one 16b is shown, for example, a large number of detection l\rads are arranged in the direction perpendicular to the drawing (Y direction), and signals are read out by scanning these in parallel in the arrow direction (X direction) in the drawing. You can also do it like this. It is also possible to scan in the X direction and the Y direction using one detection head at a time, and serially read out signals from all pixel areas.

According to this embodiment, by reducing the size of the detection head and the scanning pitch, higher resolution can be obtained than in the case of electrophotography. Furthermore, compared to a method in which a charge latent image is directly developed with toner, a high S/N ratio can be obtained because an X-ray image is obtained by reading the electric signal once and performing signal processing. In addition, since there is no need for fine electrode pattern processing or wiring, manufacturing is easy and the structure is simple.
The cost of the X-ray image receiving device can be reduced. Furthermore, since the a-Si layer is used as the photoconductor layer, it has excellent photosensitivity, mechanical strength, and durability, is harmless, and has excellent heat resistance, making it easy to handle.

FIG. 2 shows the structure of an embodiment in which the main body portion of the X-ray image receiving apparatus shown in FIG. 1 is modified. In this embodiment, the a-Si layer 25 is composed of a non-doped a-Si layer 25a and a boron-doped P-type a-S layer.
As the double structure of the i-layer 25b, this P-type a-Se layer 25
a-s i
The charging voltage of the layer 25 is improved, and sensitivity can be effectively improved. In addition, as a protective layer, a-3elil 2
On the 2 side, there is a 5102 layer 27, which is a transparent insulating layer, and a-Si5
On the 25 side, an amorphous carbon hydrogenated film (a-Si:
C:H) layer 28, which increases the mechanical strength of each photoconductor layer. Further, the a-Si:C
:8 layer 28 has the characteristic that it also contributes to improving the charging voltage of a-SiF325, and this a-Si :C:
The interaction between the 8 layer 28 and the P-type a-Si layer 25b greatly increases the charging voltage.

As is clear from the embodiments shown in FIGS. 1 and 2 above, the X-ray image detection process in the present invention consists of two methods: direct detection of the X-ray image and indirect detection by converting the XIi image into light. These mutual effects make it possible to use X-ray energy very efficiently, making it possible to obtain X-ray images with high resolution and extremely high sensitivity.

Further, the feature of the present invention is that energy subtraction can be performed by the above-mentioned groove formation. Figure 3 simply shows the absorption spectrum of X-ray energy in the present invention.
Most of it is absorbed by 3I phosphor. The X-ray energy spectrum immediately after exiting the X-ray tube is distributed as shown in the diagram (2), but before it enters the X-ray receiver according to the present invention, it is distributed on the lower X-ray energy side as shown in the diagram @. Absorbed by air. Next, the X-ray energy is incident on a subject (not shown), where the X-ray energy is absorbed to some extent by the subject, and then enters the X-ray image receiving apparatus of the present invention. Then, the X-ray energy is absorbed by a-Se, csI, and a-3t from the lower side (as shown in the figure).
C) becomes zero at U (e) ). The X-rays transmitted through the object are absorbed by the a-3e layer to form a charge latent image of xP; 1 m, and the peak of the X-ray energy absorbed here is shown as E1o in the figure. The X-rays that have passed through a-8elli then pass through Csl 5, where they are similarly absorbed and become X
Light is emitted corresponding to a line image, passes through the glass fiber substrate, and enters the a-Si layer. Most of the light from this CsI layer is absorbed by the a-Si layer, and a charge latent image is formed on the a-Si5 in the form of an X-ray image converted into an optical image.
The X-ray energy absorbed by the CsI layer is equivalently a
- It can be considered that it is absorbed by Sili, that is, Csl
The peak of X-ray energy absorbed by E is a-Sil
It can be considered as the peak of the X-ray energy absorbed by i5, and the peak at this time is designated as E2 in the figure. Zarani a-
The remaining X-ray energy that is almost absorbed by the CsI layer is almost absorbed by the a-Sili layer and becomes zero. The X-ray energy peak absorbed here is illustrated.E
Set it to 3. By image processing these Elo, E2, and E3 using the energy subtraction method, it is possible to obtain a clear image of an invisible part of the subject. That is, according to the present invention, unlike the general case where at least two X-ray shadows are required, only one radiograph is required, resulting in the great advantage of low radiation dose and shortened time.

The present invention is not limited to the embodiments described above, and can be implemented with various modifications as illustrated below.

) The a-Si layer which is the photoconductor layer is made of non-doped a-Si.
Not limited to. Generally, non-doped a-Si is a weak n-type, and its resistance is not so high as about 1012 Ωcm. Therefore, for example, boron rays may be doped with a small amount of oxygen, nitrogen, carbon, etc. to make it close to intrinsic and increase the resistance. This makes it possible to reduce the dark decay of the charge amount.

(c) It is also effective to dope the surface of the photoconductor layer with carbon or provide an insulating film such as an amorphous SiC, 5iQ2 film, or Si3N4 film to protect the surface of the photoconductor layer.

(C) In the example, the surface of the photoconductor layer was previously charged positively, but it may be charged negatively. In this case, an n-type a-Si layer may be used as the blocking M shown in FIG. Further, when used for both positive and negative charging, an insulating layer may be used as a blocking layer, for example, SiO2, Si3
N4, SiC, etc. may be used.

The direction of incidence of X-rays may be not on the phosphor layer side but on the photoconductor layer side of the a-Si layer.

(e) The transparent electrode provided on one side of the photoconductor layer is ITO.
In addition to a combination of ITO and SnO2, a single layer of In2O3 may be used, or a combination of these may also be used.

Metal films such as Ti and Ta can also be used.

(D In addition to CsI as the phosphor layer, NaI 1Bi+
Other materials such as Ge3Ch2, CaWO+, etc. can be used.

The photoconductor layer uses a-3e and a-Si,
Only a-s i E may be used for a-3e, or a-8i may be used on the phosphor layer side and a-3e may be used on the opposite side.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an X-ray image receptor δ according to an embodiment of the present invention, Fig. 2 is a diagram showing a modified example of the main body, and Fig. 3 is a diagram showing the absorption spectrum of the X-ray energy. Figure 4
The figure shows an example of a conventional X-ray image receiving device, and FIG. 5 shows an example of a conventional X-ray detector. 11, 21・a-3efffi 12a, 12b, 22a, 22b-SnO2 layer 13, 2
3.C5I 1 14, 24...Glass fiber substrate 15, 25.a-Si layer 16a, 16b-Detection head 17...Object 27...Si0
2 layer 28・a-Si:C:Hffl Fig. 1 Fig. 2 Fig. 3 Fig. 5

Claims (6)

[Claims] (1) A first photoconductor layer having a first transparent electrode on the side opposite to the X-ray incident direction, into which the X-rays that have passed through the subject are incident; A phosphor layer on which X-rays enter, and a phosphor layer that transmits the light generated from this phosphor layer.
a light-transmitting substrate on which a large number of optical waveguides are arranged in the thickness direction; a second photoconductor layer having a second transparent electrode on the light incidence side where light transmitted through the light-transmitting substrate is incident; This second
The other surface of the photoconductor layer and the X-ray incident surface of the first photoconductor layer on which the X-rays transmitted through the object are incident are scanned, and the transmitted X-rays are scanned.
An X-ray image receiving apparatus comprising: a detection head that detects charges or potentials of various parts corresponding to a ray image. (2) The phosphor layer, the first transparent electrode, and the first photoconductor layer are laminated in this order on one surface of a translucent substrate, and the second photoconductor layer is further laminated on the other surface of the translucent substrate. The X-ray image receiving device according to claim 1, wherein the transparent electrode and the second photoconductor layer are laminated in this order. (3) The first and second photoconductor layers generate electron-hole pairs when receiving X-rays, and generate electron-hole pairs when receiving light from the phosphor layer. An X-ray image receiving apparatus according to claim 1. (4) The X-ray image receiving device according to claim 1, wherein the first and second photoconductor layers have a charge or potential accumulation effect. (5) The first and second photoconductor layers are an amorphous material mainly composed of Si or Se.
The X-ray image receiving device described in . (6) The X-ray image receiving device according to claim 1, wherein the transparent substrate is made of glass fiber.