JP2003329797A - Material and method for forming radiation image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel and a method for forming radiation images which have a high detection quantum efficiency. <P>SOLUTION: The method for forming radiation images consists of a radiation absorption phosphor layer containing phosphors that emit light through the absorption of radiation, a storage phosphor layer containing storage phosphors that emit energy stored by exciting an electric field as light, a two-dimensional light detection layer and a radiation image formation material that has an electrode layer for applying the electric field to the storage phosphor layer and is composed through the formation of images corresponding to the spatial energy distribution of radiation by secondarily exciting the storage phosphor layer of the radiation image formation material through the application of the electric field to detect the storage phosphor layer of the radiation image formation material in the two-dimensional light detection layer. The two-dimensional light detection layer is not always required. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image forming method using a storage phosphor and a radiation absorbing phosphor.

[0002]

2. Description of the Related Art When irradiated with radiation such as X-rays, it absorbs and stores a part of the radiation energy, and when it is subsequently irradiated with electromagnetic waves (excitation light) such as visible light and infrared rays, it responds to the accumulated radiation energy. Using a stimulable phosphor that has the property of exhibiting luminescence (such as a stimulable phosphor that exhibits stimulated emission), the sheet-like radiation image conversion panel containing this stimulable phosphor transmits the subject Or after the radiation image information of the subject is once accumulated and recorded by irradiating the radiation emitted from the subject, the conversion panel is scanned with excitation light such as laser light and sequentially emitted as fluorescence (light emission), A radiation image recording / reproducing method (radiation image forming method), which comprises photoelectrically reading the fluorescence to obtain an image signal
Is widely used in practice. The conversion panel which has finished reading the image information is prepared for the next imaging after the remaining radiation energy is erased and is repeatedly used.

A radiation image conversion panel (also referred to as a stimulable phosphor sheet) used in the radiation image recording / reproducing method has a basic structure comprising a support and a phosphor layer provided thereon. However, when the phosphor layer is self-supporting, a support is not always necessary. In addition, a protective layer is usually provided on the upper surface of the phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact. The phosphor layer is composed of a stimulable phosphor and a binder that contains and supports the stimulable phosphor in a dispersed state, does not include a binder formed by a vapor deposition method or a sintering method, and only an aggregate of the stimulable phosphor. There are known ones composed of, and ones in which the polymer substance is impregnated in the gaps of the aggregates of the stimulable phosphor.

The radiation image recording / reproducing method is a method having a number of excellent advantages as described above, and even the radiation image conversion panel used in this method is as sensitive as possible and has a high image quality (sharpness). It is desired to provide an image having a good degree, graininess, etc.). Further, it is desired to read the radiation image information accumulated and recorded in the radiation image conversion panel at a higher speed, and to reduce the size and cost of the reading device for reading.

Patent Document 1 discloses a radiation image conversion panel containing a stimulable phosphor (energy storage phosphor) by separating the radiation absorption function and the energy storage function in a conventional stimulable phosphor. There is disclosed a radiation image forming method using a combination with a phosphor screen containing a phosphor that absorbs radiation and emits light in the ultraviolet to visible region (radiation absorbing phosphor). In this method, radiation that has passed through the subject is first converted into light in the ultraviolet or visible region by the radiation-absorbing phosphor of the fluorescent screen or conversion panel, and then the light (primary excitation light) is converted into energy of the conversion panel. Accumulative phosphor is used to store and record as radiation image information. Next, this conversion panel is excited by excitation light (secondary excitation light)
The light is emitted by scanning with, and the light is photoelectrically read to obtain an image signal.

Certain stimulable phosphors (ZnS: Cu, etc.)
Is excited by light in the visible to infrared region (primary excitation),
It is known that when an electric field is applied, it is secondarily excited and emits light. This phenomenon is called Gudden-Poh.
l) Called the effect.

Patent Document 2 discloses a two-dimensional radiation detector utilizing the Gooden-Paul effect. This radiation detector includes a stimulable phosphor layer, an electrode or a group of electrodes for electric field excitation of the phosphor layer, and a two-dimensional photodetection function layer for detecting light emitted from the phosphor layer, as constituent elements. These are close to each other and form a multilayer structure. The light emitted from the phosphor layer by electric field excitation of the stimulable phosphor layer on which a latent image is formed by incidence of radiation is detected as a photocurrent by the two-dimensional photodetection function layer.

[0008] In Patent Document 3, a recording support medium (photosensitive layer) is provided in which a layer made of a phosphor that stores radiation energy and emits the energy as light upon excitation by an electric field is disposed between substrates having two electrodes. A memory display system including a sex screen is disclosed. In this system, the light emitted from the phosphor layer of the screen by electric field excitation is
It is detected by a photodetector such as a photomultiplier tube or a photodiode arranged in close proximity.

In any of the above cases, since only the phosphor layer to which an electric field is applied absorbs radiation energy, accumulates it, and releases it, a high radiation absorption rate and application of a strong electric field are achieved. It is difficult to make them compatible.

[0010]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-255610

[Patent Document 2] JP-A-62-69182

[Patent Document 3] US Pat. No. 4,818,877

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radiation image forming method capable of giving a high quality radiation image having high detection quantum efficiency and capable of high-speed reading.
Another object is to provide a radiation image forming material and a radiation image forming assembly which can be advantageously used in the above-mentioned radiation image forming method.

[0012]

DISCLOSURE OF THE INVENTION As a result of a comprehensive study on the detection quantum efficiency (DQE) of a radiation image conversion panel, that is, the radiation absorption rate, the emission efficiency, and the emission efficiency of emission (fluorescence), the present inventor By utilizing a system that separates the radiation absorption function and the energy storage function of the stimulable phosphor of, and makes the two kinds of phosphors share each function, It has been found that it is possible to use an excellent stimulable phosphor, and as a result, the radiation absorption rate can be increased.
Further, it was also found that in the system, a phosphor capable of exciting an electric field is used as the stimulable phosphor, and the phosphor is secondarily excited by applying an electric field, whereby the luminescence (fluorescence) can be amplified. As a result, the device requirement for photodetection sensitivity is reduced, and it has been found that secondary excitation for reproduction of a radiation image can be realized by a simpler device.

Further, the application of an electric field as a secondary excitation means,
By performing point scanning or line scanning, and further detecting or condensing light emission (fluorescence) using a photoelectric conversion device (eg, photoconductive layer) or a fluorescent light condensing layer provided in the conversion panel, It has been found that it is possible to provide a radiation image forming method capable of eliminating the loss of light emission (fluorescence) caused by such a separation operation from excitation light and thus providing a radiation image of high sensitivity and high image quality. At the same time, it has been found that since an excitation light source such as a laser light source and a transfer means for the conversion panel are not required, the size and cost of the device used in this method can be greatly reduced.

The present invention provides at least one radiation-absorbing phosphor layer containing a phosphor that absorbs radiation and emits light (preferably light in the ultraviolet to visible range), A stimulable phosphor layer containing a stimulable phosphor that stores light energy and emits the stored energy as light by electric field excitation, and at least one side attached to an upper surface and a lower surface of the stimulable phosphor layer is A radiation image forming material including a pair of light transmitting electrode layers for applying an electric field, and a two-dimensional photodetection layer provided on the light transmitting electrode layer side of the stimulable phosphor layer (radiation image forming material). In A).

In the present specification, the term "light-transmissive electrode" mainly means a known transparent electrode, but it is a metal electrode in the form of a mesh or fine stripes and shows a partial light-transmittance. It is used to include an electrode and an electrode in which the above-mentioned partial metal electrode and a transparent electrode are used in combination. In particular, a mesh-shaped or fine stripe-shaped metal electrode has a high transmittance for ultraviolet light and is suitable for the electrode layer on the stimulable phosphor layer side. The two-dimensional photodetection layer is a photoelectric conversion layer, and a pair of electrode layers provided on the upper surface and the lower surface of the photoelectric conversion layer (provided that at least the surface on the stimulable phosphor layer side is provided). The electrode layer is light-transmissive), or a configuration including an optical waveguide type fluorescence condensing layer can be advantageously used.

The radiation image-forming material A of the present invention is obtained by irradiating the radiation image-forming material with radiation which has been transmitted through the subject, diffracted or scattered by the subject, or emitted from the subject. After the two-dimensional distribution of the energy of the radiation is recorded as a latent image directly on the stimulable phosphor layer of the forming material and further via the light converted from the radiation in the radiation-absorbing phosphor layer, An electric field is applied to the phosphor layer to emit light from the latent image of the stimulable phosphor layer, and the light is photoelectrically converted in a two-dimensional photodetection layer to obtain an image signal corresponding to the latent image, Advantageously used in a radiation image forming method, which comprises electrically processing the image signal to form an image corresponding to a two-dimensional distribution of radiation energy recorded as a latent image in the stimulable phosphor layer. You can

The present invention also relates to at least one radiation-absorbing phosphor layer containing a phosphor which absorbs radiation and emits light (preferably light in the ultraviolet to visible range), the energy of which is absorbed by the light. A stimulable phosphor layer containing a stimulable phosphor that emits the stored energy as light by electric field excitation, and a pair of electric fields for applying an electric field attached to the upper surface and the lower surface of the stimulable phosphor layer. There is also a radiation image-forming material (radiation image-forming material B) containing a light-transmitting electrode layer.

The radiation image-forming material B of the present invention is obtained by irradiating the radiation image-forming material with radiation which has been transmitted through a subject, diffracted or scattered by the subject, or emitted from the subject. After the two-dimensional distribution of the energy of the radiation is recorded as a latent image directly on the stimulable phosphor layer of the forming material and further via the light converted from the radiation in the radiation-absorbing phosphor layer, An electric field is applied to the phosphor layer to cause light to be emitted from the latent image of the stimulable phosphor layer, and the light is transmitted to the radiation image forming material on the side opposite to the side of the radiation absorbing phosphor layer. By photoelectrically detecting from the surface of the layer, an image signal corresponding to the latent image is obtained, and by electrically processing the image signal, the radiation recorded as a latent image in the stimulable phosphor layer. Image corresponding to the two-dimensional distribution of energy It can be advantageously used for forming a radiation image-forming method which comprises.

The present invention also relates to a stimulable phosphor layer containing a stimulable phosphor that absorbs light, stores the energy, and emits the stored energy as light when excited by an electric field.
And a radiation image conversion panel having a pair of light-transmitting electrode layers for applying an electric field provided on the upper surface and the lower surface of the stimulable phosphor layer, and a radiation absorbing material containing a phosphor that absorbs radiation and emits light. There is also a radiation image forming assembly comprising a fluorescent screen having a fluorescent layer.

The above-mentioned radiation image forming assembly of the present invention comprises:
A radiation image forming assembly composed of a radiation image conversion panel and a fluorescent screen is closely arranged so that the fluorescent screen is adjacent to the light transmissive electrode layer of the storage phosphor layer of the radiation image conversion panel. Alternatively, the surface of the fluorescent screen is irradiated with radiation that has been transmitted through the subject, diffracted or scattered by the subject, or emitted from the subject, and directly to the stimulable phosphor layer of the radiation image conversion panel, and Further, a two-dimensional distribution of the energy of the radiation is recorded as a latent image through the light converted from the radiation in the radiation absorbing phosphor layer, and then an electric field is applied to the stimulable phosphor layer to cause the accumulation property. By emitting light from the latent image of the phosphor layer and photoelectrically detecting this light from the surface of the radiation image conversion panel, an image signal corresponding to the latent image is obtained, and the image signal is electrically processed. It makes it possible to advantageously used for radiographic image forming method comprises forming an image corresponding to the two-dimensional distribution of the recorded have radiation energy as a latent image on the stimulable phosphor layer.

In the present invention, radiation means X-ray, γ
Rays, beta rays, alpha rays, ionizing radiation such as ultraviolet rays, and neutron rays. In general, the ultraviolet to visible region is 2
It means a wavelength range of 00 nm to 600 nm, and the visible to infrared region means a wavelength range of 400 nm to 1600 nm.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION [Structure of Radiation Image Forming Material] Next, the radiation image forming material of the present invention will be described in detail. The radiation image forming material (A and B) of the present invention comprises at least one radiation absorbing phosphor layer, a stimulable phosphor layer,
And a pair of electrode layers (disposed on each surface on both sides of the stimulable phosphor layer, one or both of which is a light transmissive electrode layer). The radiation absorbing phosphor layer is
A phosphor that absorbs radiation and emits light (preferably light in the ultraviolet to visible region) (hereinafter referred to as a radiation-absorbing phosphor)
Is a layer containing. The stimulable phosphor layer is a layer containing a stimulable phosphor that absorbs light (fluorescence) emitted from a radiation-absorbing phosphor, accumulates the energy, and emits the accumulated energy as light by electric field excitation. Since the stimulable phosphor layer absorbs a part of radiation, the energy of the radiation directly absorbed by the stimulable phosphor layer also contributes to the formation of a radiation image.

Alternatively, an assembly comprising a radiation image conversion panel having a stimulable phosphor layer and a pair of light transmissive electrode layers, and a fluorescent screen having a radiation absorbing phosphor layer (a radiation image forming assembly). ).

A two-dimensional photodetection layer (for example, a two-dimensional photodetection layer adjacent to the light-transmissive electrode layer on the surface of the stimulable phosphor layer for detecting a two-dimensional distribution of light generated by excitation of the stimulable phosphor layer (for example,
It is preferable that a photoconductive layer or a layer including an optical waveguide type fluorescence condensing layer) is provided (image forming material A).

The constitution of the radiation image forming material of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing a typical example of the configuration of the radiation image storage panel A of the present invention. The arrow indicates the irradiation direction of radiation such as X-rays.

In FIG. 1, the radiation image forming material 10 is shown.
Are, in order, a support (or protective layer) 11, a radiation-absorbing phosphor layer 12, a light-transmitting electrode layer 13, a storage phosphor layer 14, a light-transmitting electrode layer 15, a photoconductive layer (photoelectric conversion layer). 1
6, light transmissive electrode layer 17, radiation absorbing phosphor layer 18,
And a support (or protective layer) 19.

The layer thickness of the radiation absorbing phosphor layer 12 on the radiation irradiation side (referred to as the front side) is generally 50 to 20.
0 μm, preferably 100 to 150 μm
Is in the range. In addition, the layer thickness of the radiation absorbing phosphor layer 18 on the side opposite to the side irradiated with radiation (called the back side) is preferably equal to or larger than the layer thickness of the front side phosphor layer 12. , Generally 50 to 300
It is in the range of μm, preferably in the range of 150 to 250 μm. However, when the radiation-absorbing phosphor layer has anisotropy, the layer thickness is about 800 μm or less (preferably 600 μm or less) on either the front side or the back side (preferably the back side). ) May be sufficient.

Since energy is accumulated by absorption of light in the stimulable phosphor layer 14, the layer thickness can be made thin, generally in the range of 1 to 50 μm, preferably in the range of 5 to 20 μm. is there. Storage phosphor layer 14
Is preferably thinner than the radiation absorbing phosphor layer 12. More preferably, the layer thickness of the stimulable phosphor layer 14 is smaller than the total layer thickness of the two radiation absorbing phosphor layers 12 and 18, and is 0.1% or more and 50% or less, particularly 0.2%.
With the above, the range is set to 20% or less. This facilitates application of a strong electric field by the transparent electrode layers 13 and 15 on both sides.

The layer thickness of the photoconductive layer 16 is generally in the range of 0.1 to 50 μm, 0.1 to 5 μm when an inorganic material such as a-Si is used, and when an organic material is used. It is preferable that the thickness is in the range of 5 to 20 μm. The thickness of the supports (protective layers) 11 and 19 is generally in the range of 2 to 1000 μm. If the support function is emphasized, it is preferable to adjust the thickness to be in the range of 50 to 350 μm. For the support,
A substrate such as a carbon fiber sheet or an aluminum sheet may be attached.

The light-transmissive electrode layers 13, 15, 17 are made of IT
It may be a transparent electrode made of O or the like, or a metal electrode made of aluminum or the like in a mesh shape or a fine stripe shape. In particular, since the mesh-shaped metal electrode has a high transmittance for ultraviolet light, it is preferably used for the electrode layers 13 and 15 on the stimulable phosphor layer 14 side.

Further, since the photoconductive layer exists inside the radiation image forming material 10, it is desirable that outside light does not enter the inside of the image forming material. For this reason, it is desirable that the support be formed of a light-impermeable material or that the support be provided with a light-impermeable layer. Further, in order to prevent the invasion of external light, it is also effective to apply a light shielding edge around the radiation image forming material. However, when the image forming material is housed and stored in a light shielding container such as a cassette, the light shielding structure of the image forming material itself need not be considered.

On both sides of the stimulable phosphor layer 14 of the radiation image forming material 10, a total of two layers of the radiation absorbing phosphor layer 1 are provided.
Since 2 and 18 are provided and the primary excitation by the emitted light (fluorescence) is performed from both sides of the phosphor layer 14, higher image quality can be achieved.

Reading of the radiation image information accumulated and recorded in the stimulable phosphor layer 14 of the radiation image forming material 10
As will be described later, the light transmissive electrode layers 13 and 15 on both sides apply an electric field to the stimulable phosphor layer 14 to excite the electric field,
This is performed by emitting light, converting the light into a photocurrent in the photoconductive layer 16, and detecting the photocurrent from the light transmissive electrode layer 17.

When this electric field excitation is performed by point scanning, two light transmitting electrode layers 13 and 15 for exciting the stimulable phosphor layer 14 in the electric field and the light transmitting electrode layer 1 for the photoconductive layer are provided.
The strip 7 has a strip parallel structure in which a plurality of strips are arranged apart from each other, as shown in FIG. 2, for example. In FIG. 2, the distance between the strip-shaped electrodes is shown large for easy visual identification, but the distance should be small as long as the mutual insulation can be maintained. In the configuration of FIG. 2, the electrode layer 15 serves as both the electrode of the phosphor layer 14 and the electrode of the photoconductive layer 16. However, the phosphor layer 14
It is also possible to separately prepare the electrode layer of (1) and the electrode layer of the photoconductive layer 16 and to laminate them by interposing an optically transparent insulating layer.

Reference numerals 13a, 15a and 17a in FIG. 2 are plan views showing an example of the structure of the electrodes in each light-transmissive electrode layer, and 13a is a front electrode layer 13, 15a.
Indicates an electrode structure on the back side electrode layer 15, and 17a indicates an electrode structure in the photoconductive layer electrode layer 17. The front side electrode structure and the back side electrode structure may be interchanged. Each of the front-side and back-side electrode layers 13a and 15a has a structure in which a large number of strip-shaped electrodes having the same shape are regularly arranged in the plane direction at regular intervals. However, the parallel directions of the electrodes on the front side and the back side are orthogonal to each other.
The width of one strip-shaped electrode is, for example, 5 to 500 μm,
The distance between the electrodes may be, for example, 0.1 to 50 μm. Note that the front and back electrodes do not necessarily need to be parallel to each other in the parallel direction, but they must at least intersect in order to perform point scanning.

On the other hand, the photoconductive layer electrode layer 17a may have an electrode structure in which the entire layer is integrated. Therefore,
Photocurrent is taken out from the entire surface of the photoconductive layer 16.
However, in order to improve the response and the like, the electrode layer may be divided into several in the plane direction or in accordance with the arrangement of 15a.

When the electric field excitation is performed by line scanning, the two light transmissive electrode layers 13 and 15 for exciting the stimulable phosphor layer 14 in the electric field and the light transmissive electrode layer 17 for the photoconductive layer.
Has a structure as shown in FIG. 3, for example.

Reference numerals 13b, 15b and 17b in FIG. 3 are plan views showing the structure of the electrodes in the respective light transmissive electrode layers. 13b is the front electrode layer 13, 15b is the back electrode layer 15, and 17b is Photoconductive layer electrode layer 17
The electrode structure in FIG. Here, the configurations of the front electrode structure 13b and the back electrode structure 15b may be exchanged. Electrode layer 13b for the front side and the photoconductive layer,
Each of 17b has a structure in which a large number of strip-shaped electrodes having the same shape are regularly arranged in the plane direction at regular intervals. The electrode layer 15b is a common electrode layer, and the entire electrode is integrated. On the other hand, the parallel direction of the electrodes of the photoconductive layer electrode layer 17b is orthogonal to the parallel direction of the electrodes of the front side 13b. Therefore, the photocurrent generated in the photoconductive layer 16 is individually taken out for each electrode of the electrode layer 17.

Alternatively, the electrode layer 15 may be composed of two electrode layers sandwiching an insulator. Further, as for the electrodes on both sides of the stimulable phosphor layer and / or the photoconductive layer, if at least one is a parallel strip-shaped array, the other may be integrated. At that time, the electrode shape of the electrode layer 15 may be a two-layer structure with a light-transmissive insulating layer in the middle so that the electrode shape can be independently selected for each application.

The radiation image forming material may be provided with two photoconductive layers (photoelectric conversion layers). FIG. 20 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material A of the present invention.
Radiation absorbing phosphor layer 12, light transmissive electrode layer 17 ′, photoconductive layer 16 ′, light transmissive electrode layer 13, storage phosphor layer 1
4, light transmissive electrode layer 15, photoconductive layer 16, light transmissive electrode layer 17, radiation absorbing phosphor layer 18, and support 19
It consists of The light transmissive electrode layer 17 ′ has an electrode structure similar to that of the light transmissive electrode layer 17.

The radiation image information accumulated and recorded in the stimulable phosphor layer 14 is read by the light-transmissive electrode layers 13 on both sides.
The stimulable phosphor layer 14 is excited by an electric field by 15 to emit light, and the light is converted into photocurrent by the photoconductive layers 16 and 16 ′ on both sides, and the photocurrent is converted into phototransmissive electrode layers 17 and 17. 'Better by detecting. Therefore, a radiation image conversion panel having higher detection quantum efficiency can be obtained.

In the radiation image forming material, the radiation absorbing phosphor layer on one side (for example, the back side) may be omitted. FIG. 4 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material A of the present invention.
Support 11, radiation absorbing phosphor layer 12, light transmissive electrode layer 13, storage phosphor layer 14, light transmissive electrode layer 1 in this order
5, a photoconductive layer 16, a light transmissive electrode layer 17, and a support 19. This structure is used for the stimulable phosphor layer 14
Can be advantageously used when the absorption of light emitted from the radiation absorbing phosphor is large.

In the radiation image forming material, an insulating layer may be provided between the stimulable phosphor layer and each electrode layer. FIG. 5 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material A of the present invention, which is between the stimulable phosphor layer 14 and the light transmissive electrode layer 13 and the stimulable phosphor layer 14. And the light-transmissive electrode layer 15 between the insulating layer 13 and
c and 15c are provided. However, it is preferable to adjust the interface of the phosphor particles or the phosphor layer so that electroluminescence (EL) light emission does not occur when an electric field is applied without irradiating the stimulable phosphor layer with radiation. Only one insulating layer may be provided.

21 and 22 are schematic sectional views showing another example of the constitution of the radiation image forming material A of the present invention. In FIG. 21, the radiation image forming material comprises a support 11, a radiation absorbing phosphor layer 12, and a light transmitting electrode layer 1 in this order.
7 ', a photoconductive layer 16', a light transmissive electrode layer 13, a stimulable phosphor layer 14, a light transmissive electrode layer 15, a photoconductive layer 16, a light transmissive electrode layer 17, and a support 19. . In FIG. 22, the radiation image forming material is the support 11,
Radiation absorbing phosphor layer 12, light transmissive electrode layer 17 ', photoconductive layer 16', insulating layer 13c, light transmissive electrode layer 13, storage phosphor layer 14, insulating layer 15c, light transmissive electrode layer 1
5, a photoconductive layer 16, a light transmissive electrode layer 17, a radiation absorbing phosphor layer 18, and a support 19.

FIG. 6 is a schematic sectional view showing another example of the constitution of the radiation image forming material A of the present invention. In FIG. 6, the radiation image-forming material 20 comprises a support 21, a radiation-absorbing phosphor layer 22, a light-transmitting electrode layer 23, a stimulable phosphor layer 24, a light-transmitting electrode layer 25, and an optical waveguide type fluorescence collector. Light layer 26, radiation absorbing phosphor layer 28, and support 29
Composed of.

FIG. 7 is a schematic sectional view showing an example of the structure of the optical waveguide type fluorescent light condensing layer 26. In FIG. 7, the optical waveguide type light-collecting layer 26 is a core portion 2 made of a high refractive index fluorescent layer.
6a and clad portion 26 composed of low refractive index layers on both sides thereof
b, 26c, which is an optical waveguide type fluorescent light condensing layer, and three end faces of the fluorescent light condensing layer are covered with a light reflecting member 261. At the time of reading, the fluorescence remains on one end face 2
It is emitted from 62 and is photoelectrically detected by a photodetector 65 arranged adjacent to the end face 262. Fluorescent light collecting layer 26
The layer thickness is generally in the range of 2 to 50 μm, preferably in the range of 5 to 20 μm. If necessary, a selective reflection layer (multi-layer film) may be further provided outside the low refractive index layer.
May be attached.

The radiation image information accumulated and recorded in the stimulable phosphor layer 24 of the radiation image forming material 20 is read by the stimulable phosphor layer 24 and the light-transmissive electrode layers 13 and 15 on both sides, as will be described later. Is applied to excite the electric field to emit light, and the light is absorbed by the core portion 26a of the optical waveguide type fluorescence condensing layer to generate fluorescence, which is guided to guide the fluorescence condensing layer. This is performed by photoelectrically detecting with a photodetector (for example, photodetector 65 in FIG. 7) installed so as to be in close contact with one end surface of 26.

When the electric field excitation is performed by point scanning, the two light transmissive electrode layers 23 and 25 and the optical waveguide type light condensing layer 26 for electric field exciting the stimulable phosphor layer 24 are shown in FIG. Make the structure as shown.

Reference numerals 23a and 25a in FIG. 8 are plan views showing the structure of the electrodes in the respective light transmissive electrode layers 23 and 25, and 26a is a plan view showing the structure of the optical waveguide type light collecting layer 26. Front-side and back-side electrode layers 23
Each of a and 25a has a structure in which a large number of strip-shaped electrodes of the same shape are regularly arranged in the plane direction at regular intervals. However, the parallel directions of the electrodes on the front side and the back side intersect (orthogonal). On the other hand, the optical waveguide type light collecting layer 26a has a structure in which the entire layer is integrated (optical waveguide type fluorescent light collecting layer) as shown in the cross-sectional shape of FIG.
Collects light on the entire surface.

When the electric field excitation is performed by line scanning, the two light transmissive electrode layers 23 and 25 and the optical waveguide type light collecting layer 26 for electric field exciting the stimulable phosphor layer 24 are shown in FIG. Make the structure as shown.

Reference numerals 23b and 25b in FIG. 9 are top views showing the structure of the electrodes in the respective light transmissive electrode layers 23 and 25, and 26b is a plan view showing the structure of the optical waveguide type light collecting layer 26. Front side and back side electrode layers 23b, 2
Each of 5b has a structure in which a large number of strip-shaped electrodes having the same shape are regularly arranged in the plane direction at regular intervals. However, the front side 23b and the back side 25b are arranged such that the parallel directions of the electrodes are the same and the respective electrodes overlap. On the other hand, the optical waveguide type light-collecting layer 26b has a structure in which a large number of linear light-collecting elements 263 such as optical fibers are arranged at regular intervals so as to intersect (orthogonally) the electrodes of the light-transmitting electrode layers 23b and 25b. , Light is condensed for each condensing element. Also in this case, one end surface of each condensing element 263 is covered with the light reflecting member, and light is emitted only from the other end surface. However, one of the front side electrode layer 23b and the back side electrode layer 25b has an electrode structure in which the entire layer is integrated, as shown at 25c, or some of them are provided in correspondence with the other electrode structure. The structure may be divided into.

FIG. 23 shows a radiation image forming material A of the present invention.
It is a schematic sectional drawing which shows another example of a structure. In FIG. 23, the radiation image forming material includes a support 21, a radiation absorbing phosphor layer 22, an optical waveguide type fluorescent light collecting layer 26 ′, a light transmissive electrode layer 23, a stimulable phosphor layer 24, and a light transmissive electrode in this order. Layer 2
5, an optical waveguide type fluorescent light condensing layer 26, a radiation absorbing phosphor layer 28, and a support 29.

FIG. 10 shows a radiation image forming material B of the present invention.
3 is a schematic cross-sectional view showing an example of the configuration of FIG. In FIG. 10, the radiation image forming material 30 includes a support 31, a radiation absorbing phosphor layer 32, a light transmissive electrode layer 33, a stimulable phosphor layer 34, a light transmissive electrode layer 35, and a support 39 in this order. Composed.

The two light-transmissive electrode layers 33 and 35 have the structure shown in 13a and 15a of FIG. 2 when the electric field excitation is performed by point scanning, and the structure shown in FIG. 13b and 15b. 15b to 1
A shape similar to 3b is also possible. In any case, the light emitted from the stimulable phosphor layer 34 by the electric field excitation is generated by a combination of a light collecting guide and a photomultiplier tube, an avalanche photodiode, or a combination of a Selfoc lens array and a line CCD. It is detected using a known light detecting means.

The stimulable phosphor layer 34 and each electrode layer 3 of FIG.
An insulating layer may be provided between each of the insulating layers 3 and 35.

FIG. 11 is a schematic sectional view showing a typical example of the constitution of the radiation image forming assembly of the present invention. In FIG. 11, the radiation image forming assembly 40 includes a front side radiation image conversion panel 40a and a back side fluorescent screen 40b. Front side radiation image conversion panel 4
0a is, in order, the support 41 and the radiation absorbing phosphor layer 4
2, a light transmissive electrode layer 43, a storage phosphor layer 44, a light transmissive electrode layer 45, and a protective layer 46. The fluorescent screen 40b on the back side is, in order, a protective layer (support)
47, a radiation absorbing phosphor layer 48, and a protective layer (support) 49. Protective layer (support) 46, 47
The film thickness is generally in the range of about 1 μm to 20 μm, preferably in the range of 2 to 15 μm.

The two light-transmissive electrode layers 43 and 45 have the structure shown in 13a and 15a of FIG. 2 when the electric field excitation is performed by point scanning, and the structure shown in FIG. 13b and 15b. In either case, the light emitted from the stimulable phosphor layer 44 due to the electric field excitation is detected by using a known light detecting means as described with reference to FIG.

As shown in FIG. 12, the radiation absorbing phosphor layer 42 may be omitted in the radiation image conversion panel 40a. FIG. 12 is a schematic cross-sectional view showing another example of the configuration of the radiation image forming assembly of the present invention. The radiation image conversion panel on the front side includes a support body 41 and a light transmissive electrode layer 4 in that order.
3, a stimulable phosphor layer 44, a light transmissive electrode layer 45, and a support (protective layer) 46. The fluorescent screen on the back side is composed of a protective layer (support) 47, a radiation absorbing phosphor layer 48, and a protective layer (support) 49 in this order.

Also in the radiation image conversion panel 40a, similarly to the radiation image forming material 10, an insulating layer may be provided between the stimulable phosphor layer 44 and the electrode layers 43 and 45.

In FIG. 1 to FIG. 12 and FIG. 20, the irradiation direction of the radiation is indicated by an arrow, but any of the above radiation image forming materials (image forming assemblies) is turned upside down. Can be irradiated. However, even in that case, it is preferable that the radiation absorbing phosphor layers on the front side and the back side have a small thickness on the front side.

(Storable Phosphor) The stimulable phosphor used in the radiation image forming material and the assembly for radiation image formation of the present invention is a luminescent light (light in the ultraviolet to visible region) from a radiation absorbing phosphor described later. It is a phosphor that absorbs and accumulates its energy and emits that energy as light when excited by an electric field. That is, it is a phosphor that is primarily excited by the emitted light from the radiation absorbing phosphor and is secondarily excited by the electric field. A stimulable phosphor that can be primarily excited by light in the ultraviolet to green region is preferable. Examples of such a stimulable phosphor (stimulable phosphor) include ZnS: C.
u, ZnS: Mn, Cu, ZnS: Mn: Pb, Cl,
Examples thereof include SrS: Eu, Sm, KI: Cu, CdS: Ag.

The stimulable phosphor is generally used in the form of particles,
The average particle size is preferably about 5 μm or less,
2 μm or less is particularly preferable.

(Radiation Absorbing Phosphor) Used in the Present Invention
Radiation absorbing phosphors are X-ray, γ-ray, β-ray, α-ray, ultraviolet
Absorbs radiation such as neutron rays and neutron rays, and usually emits ultraviolet light instantly.
To a phosphor that emits light in the visible region. Particularly preferred
Is a phosphor that absorbs X-rays and emits light in the ultraviolet to green region
Is. The radiation-absorbing phosphor used in the present invention is mainly composed of the matrix.
As a component, a phosphor containing an element with an atomic number of 37 or more
It is preferable that the atomic number is 5
It is a phosphor containing 5 to 83 elements. Examples of the phosphor
As LnTaO_FourSystem (However, it functions as an activator
Containing no impurities, Ln is a rare earth element), L
nTaO_Four: (Nb, Gd, Tm) system, Ln₂SiO_Five:
Ce system, LnAlO₃: Ce system, LnOX: (Tb, T
m) system (X is halogen), Ln₂O ₃: Eu system, Ln₂O₂
S: (Gd, Tb, Tm) system, CsX: Na system, Cs
X: Tl system, CsX: Eu system, BaFX: Eu system, Zn
WO_Four, CaWO_Four, HfP₂O₇, Hf₃(PO_Four)₃Such
Can be mentioned. The density of the phosphor is 7.0 or more
It is preferably, and particularly preferably 9.0 or more.
An example of such a phosphor is LuTaO._Four, LuT
aO_Four: Nb, Lu₂SiO_Five: Ce, LuAlO ₃: C
e, Lu₂O₂S: (Gd, Tb, Tm) system, Lu₂O₃:
(Eu, Gd, Tb, Er, Tm) system, Gd₂O₃: (T
b, Tm) system, Gd₂O₂S: Tb, Gd₂O₂S: (P
r, Ce), CdWO_Four, Gd₃Ga_FiveO₁₂: (Cr, C
e), HfO ₂, TlCl: (Be, I), Bi_FourGe₃
O₁₂And so on.

Table 1 below shows the density and emission wavelength of typical radiation absorbing phosphors. As the storage phosphor which is preferably combined with the radiation absorbing phosphor, the above-mentioned ones can be used.

[0065]

[Table 1] Table 1 ────────────────────────── Density Emission peak wavelength Radiation absorbing phosphor (g / cm ³ ) (nm) ─ ───────────────────────── YTaO ₄ 7.5 340 YTaO ₄ : Tm 7.5 360,460 LaOBr: Tm 6.3 360,460 YTaO ₄ : Nb 7.5 410 CsI: Na 4.5 420 LuAlO ₃ : Ce 8.4 365 Lu ₂ SiO ₅ : Ce 7.4 420 LuTaO ₄ : Nb 9.8 394 Lu ₂ O ₂ S: Tb 8. 9 550 ──────────────────────────

However, the radiation absorbing phosphor used in the present invention is not limited to the phosphors shown in Table 1. The radiation absorbing phosphor is selected in consideration of matching with the primary excitation property of the stimulable phosphor. The radiation absorbing phosphor is generally used in the form of particles, and the particle size is about 1 to 2
It is preferably in the range of 0 μm.

From the viewpoint of matching, the emission wavelength region of the radiation absorbing phosphor and the primary excitation wavelength region of the storage phosphor are 7
It is preferable that they overlap by 0% or more. In this definition, each wavelength region means a wavelength range showing a value of 10% or more of the peak value of the emission spectrum or the excitation spectrum.

The radiation absorbing phosphor is contained in the radiation absorbing phosphor layer on the front side and the radiation absorbing phosphor layer on the back side are different from each other as the main component of the matrix ( It is preferable to include an element (atomic number is 37 or more). More preferably, the radiation absorbing phosphor on the back side contains an element having a relatively large atomic number. In this way, by changing the kind of the element of the phosphor and shifting the absorption characteristic for the radiation, it is possible to efficiently absorb the radiation in both the phosphor layers.
Two or more types of radiation absorbing phosphors may be contained in one phosphor layer.

[Production Method of Radiation Image-Forming Material] Next, the production method of the radiation image-forming material used in the present invention will be described. The case where the binder is contained and supported in the state will be described as an example. Each phosphor layer can be sequentially formed on the support by, for example, the following known method.

(Support) The support is usually a sheet or film made of a flexible resin material and having a thickness of 50 μm to 1 mm. The support may be transparent, or a light-reflecting material (eg, alumina particles, titanium dioxide particles, barium sulfate particles) for reflecting excitation light (primary or secondary) or stimulated emission light on the support. ) May be filled, or a void may be provided. Alternatively, the support may be filled with a light absorbing material (eg, carbon black) for absorbing stimulated emission light. Examples of resin materials that can be used to form the support include polyethylene terephthalate, polyethylene naphthalate, aramid resin,
Various resin materials such as polyimide resin can be mentioned. The support may be a metal sheet, a ceramic sheet, a glass sheet, a quartz sheet or the like, if necessary.

(Radiation-Absorbing Phosphor Layer) First, the above-mentioned radiation-absorbing phosphor particles and a binder are added to a solvent and mixed sufficiently to make the radiation-absorbing phosphor particles uniformly in the binder solution. A dispersed coating solution is prepared. Various types of resin materials are known for the binder that disperses and supports the phosphor particles, and also in the production of the radiation image storage panel of the present invention, any resin material centered on those known binder resins is known. Can be appropriately selected and used. The mixing ratio of the binder and the phosphor in the coating liquid varies depending on the characteristics of the intended radiation image conversion panel, the kind of the phosphor, etc., but generally the mixing ratio of the binder and the phosphor (bond / phosphor). ) Is selected from the range of 1 to 0.01 (weight ratio). The coating liquid further includes a dispersant for improving the dispersibility of the phosphor in the coating liquid, and a plasticizer for improving the binding force between the binder and the phosphor in the phosphor layer after formation. Various additives such as an agent, an anti-yellowing agent for preventing discoloration of the phosphor layer, a curing agent, and a crosslinking agent may be mixed.

Next, the coating liquid thus prepared is applied uniformly on the surface of the support to form a coating film. The coating operation can be performed by a conventional coating means such as a doctor blade, a roll coater or a knife coater. The coating film is dried to complete the formation of the radiation absorbing phosphor layer on the support. The phosphor layer does not necessarily have to be formed by directly applying the coating liquid on the support as described above, and for example, a separate glass plate,
After a phosphor layer is formed by applying a coating solution on a temporary support such as a metal plate or a plastic sheet and drying it, the phosphor layer is pressed onto the support, or by using an adhesive or the like on the support. You may utilize the method of joining a fluorescent substance layer to. Alternatively, a phosphor layer obtained by orienting a needle-shaped phosphor and making it anisotropic can also be used.

The radiation-absorbing phosphor layer according to the present invention is not only composed of the radiation-absorbing phosphor and a binder containing and supporting the radiation-absorbing phosphor in a dispersed state, but also the radiation-absorbing phosphor containing no binder. A polymer substance is impregnated in the gap between the aggregates of the aggregates, the phosphor layer formed by the vapor deposition method (in particular, the columnar crystal vapor deposition film is preferable), or the aggregates of the radiation absorbing phosphors. It may be a phosphor layer or the like.

In the case of the vapor deposition method, the above-mentioned radiation absorbing phosphor or its raw material is evaporated and vaporized by a vapor deposition method (electron beam vapor deposition, resistance heating vapor deposition), a sputtering method, a chemical vapor deposition (CVD) method or the like. By depositing on the substrate,
A phosphor layer is formed. For example, in the electron beam evaporation method, an evaporation source is irradiated with an electron beam generated from an electron gun. As the evaporation source, one evaporation source composed of the phosphor or its raw material mixture may be used (single-source deposition), or two or more evaporation sources separately containing the matrix component and the activator component of the phosphor may be used. It may be used (multi-source vapor deposition). By irradiation with an electron beam, the phosphor or its matrix component, activator component, etc. are heated to evaporate and scatter, and in some cases react to form the phosphor,
Deposit on the surface of the substrate (support or temporary support). The deposition rate of the phosphor is generally in the range of 0.1 to 1000 μm / min, preferably 1 to 100 μm / min. It is also possible to form the phosphor layer of two or more layers by performing electron beam irradiation in several times. The substrate may be cooled or heated at the time of vapor deposition, or the vapor deposition film obtained may be heat-treated after the vapor deposition is completed.

The phosphor layer formed by a vapor deposition method such as the above vapor deposition method is composed of columnar crystals of phosphor, and voids (cracks) exist between the columnar crystals. Therefore, it is possible to prevent the emitted light from being scattered in the planar direction.

(Partition) In order to improve the image quality of an image obtained by preventing the scattering of emitted light, the radiation absorbing phosphor layer composed of phosphor particles and a binder is arranged in a plane direction. A partition wall may be provided along the partition.
Since the radiation absorbing phosphor layer has a relatively large layer thickness, the partition of the radiation absorbing phosphor layer can effectively prevent the diffusion of the emitted light. The partition wall may be provided in any shape such as a stripe shape or a grid shape, or may be formed so as to surround a region filled with the radiation absorbing phosphor of any shape such as a circular shape or a hexagonal shape. Further, both the top and bottom of the partition wall may be exposed on both surfaces of the phosphor layer, or both the top and / or the bottom may be buried in the phosphor layer.

The partition wall should be subjected to an etching treatment suitable for a metal plate such as aluminum, titanium or stainless steel, a ceramic plate such as aluminum oxide or aluminum silicate, or a sheet made of an organic polymer such as a photosensitive resin. By preparing a honeycomb-shaped sheet in which a large number of recesses (holes) or through holes are formed, and by placing the above-mentioned phosphor layer on the honeycomb-shaped sheet and then heat-compressing the honeycomb-shaped sheet, It can be pressed into the body layer. Alternatively, a large number of thin-film phosphor sheets made of a binder containing dispersed fluorescent particles and a large number of thin-film partition sheets made of a polymeric substance are respectively formed, and a large number of phosphor sheets and partition sheets are alternately formed. It can also be formed by a laminated slicing method, which comprises cutting the sheets perpendicularly to the laminating direction after laminating the sheets. Alternatively, when the phosphor layer is composed of an aggregate of radiation-absorbing phosphors such as a vapor deposition film, the barrier ribs can be formed by forming cracks. Examples of such a phosphor layer include CsI: Na and CsI: T.
1, a needle-like crystal film such as CsBr: Tl. The partition walls may contain low-light-absorbing fine particles such as aluminum oxide and titanium dioxide dispersed therein, or may be colored with a coloring agent that selectively absorbs the emitted light from the radiation-absorbing phosphor. Good.

Alternatively, the partition wall is made of a phosphor layer material (however,
The ratio of binder: phosphor and particle size are different from those in forming the phosphor layer). Generally, since the radiation absorbing phosphor has a high refractive index, it is possible to more effectively prevent the scattering in the plane direction. Also, an image with high sharpness can be obtained while maintaining high radiation absorption.

Alternatively, the radiation absorbing phosphor layer may be formed as shown in FIG.
As shown in FIG. 3, it may be composed of a fiber plate and a needle crystal film of a radiation absorbing phosphor. In FIG. 13, the radiation absorbing phosphor layer 18 is composed of a fiber plate 18a and a needle-like crystal film 18b of a phosphor provided below the fiber plate 18a. The needle crystal film 18b of the phosphor has cracks as partition walls as described above. On the other hand, the fiber plate 18a is an optical sheet in which millions of fibers each having a diameter of several μm are bundled in the depth direction, and the acicular crystal film 1 of the phosphor is formed.
Light converted from radiation such as X-rays into light in the ultraviolet or visible region by 8b does not scatter in the plane direction through the fiber plate 18a and reaches the stimulable phosphor layer 14 with little light loss. You can By inserting the fiber plate, the needle-shaped crystal film having poor moisture resistance can be sealed only within the range of 18 and 19. If the whole is sealed, it is also possible to adopt a configuration that does not include the fiber plate.

In FIG. 13, the radiation absorbing phosphor layer 18 on the back side, not the radiation absorbing phosphor layer 12 on the front side, is composed of a fiber plate 18a and a needle crystal film 18b of the phosphor. Although shown, from the viewpoint of improving the sharpness, including this configuration, the partition wall is preferably provided in the radiation absorbing phosphor layer having a larger layer thickness than the stimulable phosphor layer, and more preferably on the back side. It is to be provided in the radiation absorbing phosphor layer. On the other hand, a configuration in which the radiation-absorbing phosphor layer 12 is not included and radiation is applied from the support (protective layer) 19 side is also useful.

(Light-Transmissive Electrode Layer) The light-transmissive electrode layer is made of a material such as metallic aluminum or indium-tin oxide (ITO) by a vacuum deposition method, a sputtering method, or the like.
It can be provided by being formed directly on the radiation absorbing phosphor layer or by adhering a separately formed light transmitting electrode layer. The light-transmissive electrode layer may be a transparent electrode, or may be a mesh-shaped or fine stripe-shaped metal electrode. In particular, since the mesh-shaped or fine stripe-shaped metal electrode transmits ultraviolet light well, it is preferably used for the electrode layer adjacent to the stimulable phosphor layer. Furthermore, the formed light-transmissive electrode layer may be subjected to etching treatment or the like to form a layer composed of a large number of strip-shaped electrodes as shown in FIG. 2 or 3. As the electrode layer, a layer that transmits 50% or more, preferably 70% or more, and more preferably 90% or more of light emitted from the radiation absorbing phosphor layer and the stimulable phosphor is used.

(Storable phosphor layer) In the same manner as above, a stimulable phosphor layer made of a binder containing and supporting the stimulable phosphor in a dispersed state is formed on the light transmissive electrode layer. However, it is preferable to use a binder having a high dielectric constant as the binder, for example, a high dielectric constant inorganic or organic material, or a composite of high-dielectric-constant inorganic ultrafine particles dispersed in a known organic binder. Material is used. As the organic material having a high dielectric constant, a cyanocellulose resin can be mentioned.
In addition, examples of the inorganic ultrafine particles having a high dielectric constant include ultrafine particles of BaTiO ₃ and SrTiO ₃ .

In the present invention, since the secondary excitation of the stimulable phosphor layer is performed not by the excitation light but by the electric field, it is not necessary to consider the scattering of the excitation light in the phosphor layer as in the conventional case, and thus the fluorescence is reduced. The binder of the body layer can be made to have a form in which the phosphor particles are highly filled with almost no voids.

Alternatively, the stimulable phosphor layer is formed by the vapor deposition method, is composed only of aggregates of the stimulable phosphor, and the polymer substance is impregnated into the gaps between the aggregates of the stimulable phosphor. May be provided, or a partition wall may be provided.

The radiation absorbing phosphor layer and the stimulable phosphor layer are preferably formed by appropriately combining the above-mentioned coating method and vapor phase deposition method (especially vapor deposition method).

When both the radiation absorbing phosphor layer and the stimulable phosphor layer are composed of phosphor particles and a binder by the above coating method, in order to obtain a higher quality radiation image, The weight ratio of the binder and the phosphor in the radiation absorbing phosphor layer (binder B ₁ / phosphor P ₁ ) is the weight ratio of the binder and the phosphor in the storage phosphor layer (binder B ₂ / phosphor). P ₂ ) or less and less than 1
The following is desirable (1 ≧ B ₂ / P ₂ ≧ B ₁ /
P ₁ ). That is, it is desirable that the ratio of the phosphor in the radiation absorbing phosphor layer is equal to or higher than the ratio of the phosphor in the stimulable phosphor layer.

The B ₁ / P ₁ ratio (weight ratio) of the radiation absorbing phosphor layer is preferably in the range of 1/8 to 1/50, more preferably in the range of 1/15 to 1/40. is there. The B ₂ / P ₂ ratio (weight ratio) of the stimulable phosphor layer is 1/1
The range is preferably from 1 to 1/20, more preferably from 1/2 to 1/10.

(Particle Diameter of Phosphor) The average particle diameter of the radiation-absorbing phosphor and the stimulable phosphor contained in each phosphor layer is (average particle diameter of the stimulable phosphor) ≦ ( Average particle size) Particularly preferably, the relationship of (average particle size of stimulable phosphor) ≤ (average particle size of radiation absorbing phosphor) x 0.5 is satisfied. As a result, the relatively large particle size of the radiation-absorbing phosphor can increase the emission efficiency against radiation and enhance the sensitivity, and the relatively small particle size of the stimulable phosphor can enhance the sharpness of the image. it can.

The average particle size of the radiation absorbing phosphor is generally 1 μm or more and 20 μm or less, preferably 2 μm.
m or more and 10 μm or less. On the other hand, the average particle size of the stimulable phosphor is generally 0.2 μm or more and 20 μm or less, preferably 0.5 μm or more and 5 μm or less.
However, as described in Japanese Patent Application No. 2000-219877, such as a stimulable quantum dot phosphor,
Even the smaller particles are fine to use, as long as their efficiency is high.

The radiation-absorbing phosphor particles and the stimulable phosphor particles used in the present invention are each described in, for example, JP-A-2000.
It may have a particle size distribution as described in JP-A-284097, JP-A-2000-192030 or JP-A-58-182600.

(Absorption Coefficient of Phosphor) From the viewpoint of improving the image quality of the radiation image, the radiation absorption coefficient of the radiation absorbing phosphor layer and the emission light (primary excitation light) from the radiation absorbing phosphor of the storage phosphor layer. It is desirable that the following relationship be satisfied with respect to the absorption coefficient. (Absorption coefficient of primary excitation light of storage phosphor layer)> (Radiation absorption coefficient of radiation absorption phosphor layer) x 2 Particularly preferably, (absorption coefficient of primary excitation light of storage phosphor layer)> (Radiation The radiation absorption coefficient of the absorptive phosphor layer) × 5 is satisfied.

Here, the absorption coefficient of the primary excitation light is an apparent absorption coefficient, and is a value defined as follows. It is assumed that the phosphor layer is a uniform layer having a thickness d, and the light reflectance is r and the light transmittance is t when the phosphor layer is placed separately in space. The light reflectance r is determined by relative comparison with a standard white plate. Let R _w and R _b be the reflectances of the entire system when a white plate (reflectance r _w ) is placed on the back side of the phosphor layer and a black plate (reflectance r _b ) is placed on it. The reflection of the entire system is the sum of the reflection by the phosphor layer and the reflection by the white plate or the black plate, and is represented by the following formula. R _w = r + r _w × t ₂ R _b = r + r _b × t ₂

The apparent absorption coefficient K of the phosphor layer is such that the sum of reflection, absorption and transmission is 1 according to the law of conservation of energy, assuming that the absorption decays exponentially with respect to the thickness d of the phosphor layer. From, it is calculated by the following equation. K = − (1 / d) × ln [t / (1-r)] = − (1 / d) × ln [{(R _w −R _b ) / (r _w −r _b )} ^1/2 / _{{1-R w + r w} (R w -R b) / (r w -r b)}]

On the other hand, the radiation absorption coefficient can be obtained as a value obtained by multiplying the mass energy absorption coefficient μ _en / ρ by the density of the phosphor layer. The mass energy absorption coefficient μ _en / ρ in the X-ray region of each substance can be obtained using the mass absorption coefficient and the mass ratio of the constituent elements of each substance. The data of mass energy absorption coefficient of each element is http: //physics.n
It can be obtained from ist.gov/PhysRefData/XrayMassCoef/cover.html. The density ρ of the phosphor layer is obtained as a value obtained by multiplying the density of the phosphor itself by the phosphor filling rate in the layer, and is usually a value of about 3 to 5.

In order to increase the radiation absorption coefficient and obtain a high quality radiation image, the radiation absorbing phosphor layer has a density of the radiation absorbing phosphor of 6.0 g / cm ³ or more, or The average density of the phosphor layer is 4.0 g / cm ^3.
The above is preferable.

(Photoconductive layer) As an example of the photoconductive layer which exhibits photoconductivity by absorbing light emitted from the stimulable phosphor layer, a photoconductive material such as amorphous silicon can be cited. Further, as the photoconductive layer made of an organic material, there are a function separation type in which a charge generation layer and a charge transport layer are laminated and a single layer structure type, and either of them can be used. Furthermore, an electron-accepting substance (eg, JP-A-2000-298361)
Or a metal such as selenium, silicon, sulfur, cadmium sulfide, zinc sulfide, or a compound thereof, a phthalocyanine-based or perinine-based coloring material) or an ultraviolet absorber, Antioxidants and the like may be added. The photoconductive layer may be directly formed on the light transmissive electrode layer by a vacuum deposition method, a sputtering method, a coating method, or the like. Alternatively, it can be provided by adhering a separately formed photoconductive layer to the light transmissive electrode layer by calendering or the like. When the photoconductive layer is formed, a peelable temporary support may be bonded underneath. When it is used between the radiation-absorbing phosphor layer and the stimulable phosphor layer, it is desirable that the absorption of the light emitted from the radiation-absorbing phosphor is small.
% Or less, preferably 30% or less, more preferably 10%
The following are good: Further, it is desirable that the absorption of the light emitted from the stimulable phosphor is large, but even a small amount such as a few% can be practically used in consideration of the amplification function by the electric field.

(Insulating Layer) Silicon dioxide is used when an insulating layer is provided between the light-transmitting electrode layer and the stimulable phosphor layer, or between the two electrode layers by separating the light-transmitting electrode layer. It can be formed by a vacuum evaporation method, a sputtering method, or the like using a material such as silicon nitride, or aluminum oxide. Alternatively, an insulating inorganic or organic material or a composite material may be formed into a film by a coating method or the like.
Methods such as sol-gel method and spray pyrolysis method are included in this.

(Optical Waveguide Type Fluorescent Light Collecting Layer) When an optical waveguide type fluorescent light collecting layer is provided instead of the photoconductive layer and the light transmissive electrode layer (FIGS. 6 and 7), for example, a temporary peelable After forming a layer of low-refractive-index polymer such as acrylic resin or fluororesin as a clad on the support, high-refractive-index polymer such as styrene resin or epoxy resin (high refractive index due to the inclusion of inorganic nanoparticles such as acrylic resin) (Although it may be indexed), a layer containing a fluorescent substance such as a nanoparticle fluorescent substance or an organic fluorescent substance that emits fluorescence by absorbing the emission of the storage fluorescent substance is formed as a core, and then the low refractive index substance is again used. Is laminated as a clad. Next, a sheet having a white reflection or specular reflection structure provided with light reflecting members on the three end faces of this laminate was peeled off from the temporary support,
It is stuck on the light-transmissive electrode layer. As the light reflecting member, a thin film made of a binder containing a light reflecting substance such as titanium dioxide, yttrium oxide, zirconium oxide, or aluminum oxide (alumina), or an aluminum vapor deposition film is used. The outer surface of the low refractive index layer may be further provided with the following selective reflection layer (multilayer film). A thin layer may be formed and used as the optical waveguide type fluorescence condensing layer by using a material appropriately selected from the above-mentioned support materials.

When the optical waveguide type fluorescent light condensing layer is composed of a large number of linear light condensing elements such as optical fibers (26b in FIG. 9), the core absorbs the luminescence of the stimulable phosphor and fluoresces. By using an optical fiber containing a fluorescent substance that emits light, by arranging the light-collecting elements provided on the light-reflecting member only on one end face and then fixing with a binder, or by pressure-bonding the radiation-absorbing phosphor layer. Can be formed.

(Selective Reflecting Layer) Further, at any position between the radiation absorbing phosphor layer and the adjacent layer such as the stimulable phosphor layer, the emitted light from the radiation absorbing phosphor is transmitted, A selective reflection layer that reflects the emitted light from the stimulable phosphor may be provided. Thereby, the utilization efficiency of light at the time of reading radiation image information can be improved.

The selective reflection layer may have, for example, a property of transmitting light in the short wavelength region including the emission wavelength of the radiation absorbing phosphor and reflecting light in the longer wavelength region than that.
The selective reflection layer can be composed of a thin film and a multilayer film formed on the thin film and having such characteristics. The multilayer film is formed by sequentially stacking two or more kinds of substances having different refractive indexes with a thickness of about ¼ of the wavelength of light (about 50 to 200 nm), and specifically, SiO ₂ , M
Low refractive index materials such as gF ₂ and TiO ₂ , ZrO ₂ , Ta ₂ O
₅ , a multilayer interference filter having a total thickness of about 0.1 to 10 μm in which a high refractive index material such as ZnS is alternately laminated to several layers to several tens layers.

The selective reflection layer is formed by sequentially laminating the above-mentioned multilayer film material on a thin film (thickness: 4 to 20 μm) made of a polymer substance or the like by a method such as vapor deposition, sputtering or ion plating. can do. Then, a thin film having this multilayer film is laminated on the radiation absorbing phosphor layer by calendering or the like. At the time of forming the above-mentioned multilayer film, a peelable temporary support may be bonded under the thin film, or a material appropriately selected from the above-mentioned support materials may be used as the selective reflection layer. To form a thin layer.

(Diffuse Reflecting Layer) Further, a diffuse reflecting layer having a function of reflecting emitted light from the radiation absorbing phosphor may be provided between the support on the front side and the radiation absorbing phosphor layer. . By providing the diffuse reflection layer, it is possible to increase the light amount of the emitted light (primary excitation light) from the radiation absorbing phosphor that is incident on the stimulable phosphor layer, and to obtain a highly sensitive radiation image conversion panel.

The diffuse reflection layer is a layer containing a light-reflecting substance such as titanium dioxide, yttrium oxide, zirconium oxide, and aluminum oxide (alumina). Considering that the diffuse reflection layer is provided on the front side, the light-reflecting substance needs to have a small absorption of radiation such as X-rays and has a high refractive index in terms of the sharpness of reflection. desirable. Therefore, titanium dioxide is preferable as the light-reflecting substance, and rutile type having a higher refractive index is particularly preferable. However, since titanium dioxide exhibits a high reflectance in a wavelength region longer than about 430 nm, it is suitable when the radiation absorbing phosphor is Gd ₂ O ₂ S: Tb or the like. When the emission wavelength of the radiation absorbing phosphor is shorter than about 430 nm, it is necessary to select a substance that does not absorb in the emission wavelength region, such as aluminum oxide, yttrium oxide, or zirconium oxide.

As described in detail in JP-A-9-21899, it is desirable that the diffuse reflection layer achieves a high light reflectance with a layer thickness as thin as possible in terms of sensitivity and sharpness. The average particle size of the light-reflecting substance is generally in the range of 0.1 to 0.5 μm, preferably 0.
It is in the range of 1 to 0.4 μm. The volume filling rate of the light-reflecting substance in the diffuse reflection layer is generally in the range of 25 to 75%, preferably 40% or more. The layer thickness of the diffuse reflection layer is generally in the range of 15 to 100 μm. The diffuse reflection layer can be formed by mixing and dispersing the fine particle light-reflecting substance and the binder in a solvent to prepare a coating solution, and then coating and drying the coating solution on a support.
The binder and the solvent can be appropriately selected and used from those that can be used for the phosphor layer.

Instead of providing a diffuse reflection layer on the support,
The above-mentioned light-reflecting substance may be dispersedly contained in the support itself to form a support having a diffuse reflection function. Also,
As described below, the diffuse reflection layer and / or the support may be colored. If a diffuse reflection layer is provided between the support on the back side and the radiation absorbing phosphor layer, it is possible to design one having excellent sensitivity.

Further, depending on the purpose, a light absorbing layer, an adhesive layer, a layer between the support and an adjacent layer such as a radiation absorbing phosphor layer,
An auxiliary functional layer such as a conductive layer may be provided, and a large number of recesses may be formed on the surface of the support. A friction-reducing layer or a scratch-resistant layer may be provided on the surface of the support on the side where the phosphor layer is not provided, in order to improve transportability and scratch resistance.

The radiation image forming material according to the present invention can be obtained by utilizing the above-mentioned materials and manufacturing methods. The radiation image forming material of the present invention has various constitutions of known radiation image conversion panels. It may include one. Although the panel having the support has been described above, the panel according to the present invention does not necessarily have to have the support when the phosphor layer is self-supporting.

(Coloring) For the purpose of enhancing the sharpness of the radiation image, at least one layer of the radiation image-forming material is added,
It may be colored with a coloring agent that absorbs the emitted light from the radiation-absorbing phosphor, or in some cases, a coloring agent that absorbs part of the emitted light from the stimulable phosphor. Specifically, it is desirable to color the intermediate layers such as the radiation absorbing phosphor layer and the undercoat layer with a colorant that absorbs the emitted light from the radiation absorbing phosphor. The coloring may be only one of the above layers or may be partial,
Moreover, you may combine arbitrarily. It is desirable that the colorant does not absorb the emitted light from the stimulable phosphor in a point detection system using a photomultiplier tube described later.

As the colorant, for example, when the emitted light from the radiation absorbing phosphor is green light and the stimulable phosphor emits red light, it absorbs light in the green region and emits light in the red region. Colorants that do not absorb are preferred (when used in point detection systems). You may use it in combination of 2 or more types of coloring agent. Examples of red colorants suitable for the above purpose include:
Inorganic pigments such as cadmium red, red iron oxide and molybdenum red can be mentioned.

Further, for example, when the emission light from the radiation absorbing phosphor is near-ultraviolet emission light and the stimulable phosphor emits blue to green light, it absorbs light in the near-ultraviolet region and emits blue to green light. Colorants that do not absorb light in the green region are preferred (when used in point detection systems).

Examples of suitable blue to green organic colorants include Zabon Fast Blue 3G (manufactured by Hoechst),
Estrol Brill Blue N-3RL (Sumitomo Chemical Co., Ltd.)
Sumitomo Chemical Co., Ltd.)
Made), D & C Blue No1 (made by National Aniline), Spirit Blue (made by Hodogaya Chemical Co., Ltd.), Oil Blue No603 (made by Orient), Kiton Blue A (made by Ciba Geigy), Aizenkachi Ron Blue G
LH (Hodogaya Chemical Co., Ltd.), Lake Blue A, F, H
(Kyowa Sangyo Co., Ltd.), Rhodolin Blue 6GX (Kyowa Sangyo Co., Ltd.), Brimosyanine Blue 6GX (Inabata Sangyo)
Brill Acid Green 6BH (Hodogaya Chemical Co., Ltd.)
Cyanine Blue BNRS (Toyo Ink Co., Ltd.)
Manufactured by Toyo Ink Co., Ltd.). Further, as an example of the inorganic colorant,
Examples include ultramarine blue, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—CoO—NiO pigments.

Alternatively, as will be described later, when the radiation image information is read by line detection using a line sensor or the like instead of point detection using a photomultiplier tube or the like, the radiation absorbing phosphor layer and the The intermediate layer such as the coating layer is preferably colored with a colorant that absorbs the emitted light from the radiation absorbing phosphor and / or the emitted light from the stimulable phosphor. This is because the portion of the emitted light from the stimulable phosphor that is wider than the excited portion causes blurring of the image.

As the colorant, when the emitted light from the radiation absorbing phosphor is green light and the emitted light from the stimulable phosphor is red light, it absorbs light in the green and / or red region. Colorants are preferred. That is, red, blue to green or gray colorants are preferred. As the red colorant and the blue to green colorants, the above colorants can be used. Examples of gray colorants include carbon black,
Cu-Fe-Mn oxide can be mentioned.

When the radiation absorbing phosphor emits near-ultraviolet light and the stimulable phosphor emits blue to green light, it absorbs light in the near-ultraviolet and / or blue to green regions. Colorants are preferred. That is, yellow, blue to green or gray colorants are preferred. The blue to green and gray colorants described above can be used. Examples of yellow colorants include yellow iron oxide, titanium yellow, and cadmium yellow.

The decrease in the sensitivity of the radiation image-forming material due to coloring can be adjusted by increasing the layer thickness of the radiation absorbing phosphor layer or increasing the electric field applied during reading, and the sensitivity and the sharpness are improved. It is possible to optimize them in relation to.

The radiation image conversion panel and the fluorescent screen constituting the assembly for forming a radiation image of the present invention are also the same as those described above, and the radiation absorbing phosphor layer, the light transmissive electrode layer, and the stimulable fluorescent layer are formed on the support. After the body layer and the like are sequentially provided, the following protective layer can be further provided to produce the layer. When used in a system involving transportation of a radiation image conversion panel, when a partition is provided in the phosphor layer, the partition is formed only in the radiation absorbing phosphor layer of the fluorescent screen, and the radiation image conversion panel is flexible. It is preferable that the image forming system (for example, the radiation image information reading device) can be made more compact and a high quality radiation image can be obtained.

(Protective Layer) A transparent protective layer may be provided on the surface of the light transmitting electrode layer or the radiation absorbing phosphor layer in order to physically and chemically protect these layers. It is desirable that the protective layer does not substantially exhibit light absorption so that it hardly affects the emission of emitted light, and that the radiation image conversion panel and the fluorescent screen are sufficiently protected from external physical shock and chemical influences. It is desirable that it be chemically stable and have high physical strength so that it can be protected. As the protective layer, a solution prepared by dissolving a transparent organic polymer substance such as a cellulose derivative, polymethylmethacrylate, or an organic solvent-soluble fluororesin in an appropriate solvent is formed on the electrode layer (or phosphor layer). Or a polymer layer such as polyethylene terephthalate or a protective layer forming sheet such as a transparent glass plate, which is formed by being applied to the surface of the electrode layer and provided on the surface of the electrode layer with a suitable adhesive. For example, those obtained by depositing an inorganic compound on the electrode layer by vapor deposition or the like are used. In addition, various additives such as a slip agent such as perfluoroolefin resin powder and silicone resin powder, and a crosslinking agent such as polyisocyanate may be dispersed and contained in the protective layer. Further, for the purpose of enhancing the sharpness of the radiation image, the protective layer is colored with a coloring agent (for example, the coloring agent described above) that absorbs the emitted light from the radiation absorbing phosphor and / or the emitted light from the stimulable phosphor. You may.

In order to enhance the sharpness of the radiation image, it is desirable that the protective layer has a light scattering property within a certain range. Generally, the light scattering length of the protective layer is in the range of 5 to 80 μm, and preferably in the range of 10 to 70 μm at the main emission wavelength of the emitted light from the stimulable phosphor. The light-scattering protective layer can be formed by dispersing and containing light-scattering fine particles in the protective layer material. The light-scattering fine particles preferably have a light refractive index of 1.6 or more and a particle diameter of 0.1 to 1.0 μm. Particularly preferably, the photorefractive index is 1.9 or more and the particle size is 0.
It is in the range of 1 to 0.5 μm. Examples of suitable light scattering particles include benzoguanamine resin particles, melamine formaldehyde condensed resin particles, zinc oxide, zinc sulfide, titanium oxide and lead carbonate particles.

A fluorine resin coating layer may be further provided on the surface of the protective layer in order to enhance the stain resistance of the protective layer. The fluororesin coating layer can be formed by applying a fluororesin solution prepared by dissolving (or dispersing) a fluororesin in an organic solvent onto the surface of the protective layer and drying.
Although the fluororesin may be used alone, it is usually used as a mixture of the fluororesin and a resin having high film forming property. Further, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used together. The fluororesin coating layer may be filled with a fine particle filler in order to reduce interference unevenness and further improve the quality of a radiation image. The layer thickness of the fluororesin coating layer is usually in the range of 0.5 μm to 20 μm. In forming the fluororesin coating layer, an additive component such as a cross-linking agent, a hardener, an anti-yellowing agent, etc. can be used. In particular, the addition of the crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.

In order to improve the handling property such as the adhesion between the radiation image conversion panel and the fluorescent screen and the ease of separation, the protective layer or the fluororesin coating layer has a maximum friction coefficient of 0.
It is preferably 18 or less, particularly preferably 0.1.
It is 2 or less. The average surface roughness is preferably in the range of 0.05 to 0.5 μm, particularly preferably in the range of 0.1 to 0.3 μm. For example, minute unevenness may be provided on the surface of the protective layer or the fluororesin coating layer by performing embossing treatment or the like.

In order to effectively prevent charging of the radiation image conversion panel, particularly peeling charging which tends to occur when the panel is separated from the fluorescent screen, charging of both protective layers of the panel and the screen, which are superposed in close contact, are opposed to each other. It is desirable that the rows are aligned. The charge trains of both protective layers can be made uniform by forming both protective layers using the same material, for example. Further, in radiography, it is preferable to remove the electric charge before inserting the both into the cassette.

Alternatively, a conductive fine powder having a particle size smaller than the emission wavelength of the transparent conductive polymer such as polypyrrole and / or the stimulable phosphor is used in any one of the layers constituting the radiation image storage panel. It is preferable to contain (fine powder of tin oxide, etc.). By making the particle diameter smaller than the emission wavelength of the stimulable phosphor, it is possible to form a thin film having a high conductivity and avoid the loss of light collection efficiency due to absorption of emitted light.

(Encapsulation) Further, the radiation image forming material, the radiation image conversion panel and the fluorescent screen described above are provided with a moisture-proof thin film on the outer surface thereof in order to enhance moisture resistance and prevent chemical change due to moisture absorption. Alternatively, a moisture-proof edge may be attached to the side surface. As the moisture-proof thin film, a metal thin film such as aluminum foil or magnesium alloy foil; Si
C, SiO ₂ , Si ₃ N ₄ , Si nitride oxide, laminated film of inorganic material such as Al ₂ O ₃ ; cellulose acetate, nitrocellulose, polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene ,
Polypropylene, polyvinylidene chloride, nylon, polytetrafluoroethylene, polytrifluoroethylene chloride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene chloride-
Examples thereof include vinyl chloride copolymers, vinylidene chloride-acrylonitrile copolymers, resin films such as polyamide and polyimide, metal oxide vapor deposition resin films, and glass. These moisture-proof thin films can be attached by, for example, adhering the upper surface, the lower surface and / or the side surface of the image forming material with an adhesive. Further, examples of the moisture-proof edging material include silicone resin, epoxy resin, and phenol resin. By applying a solution of these resins to the side surface of the image forming material and drying the solution, an edge can be attached.

[Radiation Image Forming Method] Next, regarding the radiation image forming method using the radiation image forming material of the present invention, a point scanning type radiation image forming material having a photoconductive layer (FIGS. 1 and 2) is taken as an example. First, description will be made with reference to FIG. 14 of the accompanying drawings. FIG. 14 is a schematic perspective view showing an example of the configuration of a radiation image information reading apparatus that uses current detection by point scanning.

First, radiation image information (two-dimensional distribution of radiation or spatial energy distribution information) is recorded on the radiation image forming material 10 shown in FIG. A radiation imaging device (not shown) or the like is used to arrange the subject between the radiation source such as the X-ray generator and the radiation image forming material, and then the subject is irradiated with the radiation generated from the radiation source. As the radiation, ionizing radiation such as X-rays, γ-rays, α-rays, β-rays, electron beams and ultraviolet rays, and neutron rays can be used. When neutron rays are used, it is preferable to use a matrix containing Gd, ¹⁰ B, ⁶ Li, or the like as a radiation-absorbing phosphor, or a mixture of compounds containing these elements with the phosphor.

The radiation passes through the subject or is diffracted or scattered by the subject depending on the type of the radiation and the subject, and the radiation has a spatial energy distribution information about the subject. It is made incident from the side of the support. Part of the incident radiation is
It is absorbed by the radiation-absorbing phosphor of the radiation-absorbing phosphor layer 12 on the front side and converted into light (preferably light in the ultraviolet to visible region, instantaneous light emission). The emitted light passes through the transparent electrode layer 13 and enters the stimulable phosphor layer 14,
The energy is absorbed by the stimulable phosphor in the phosphor layer and the energy is accumulated, and a two-dimensional energy distribution indicating information on the subject is recorded as a latent image in the stimulable phosphor layer 14.

Radiation that has passed from the radiation-absorbing phosphor layer 12 to the light-transmitting electrode layer 17 is absorbed by the radiation-absorbing phosphor of the radiation-absorbing phosphor layer 18 on the back side, and the light (preferably ultraviolet or Light in the visible range). In the photoconductive layer 16, most of the emitted light passes and is absorbed by the stimulable phosphor of the stimulable phosphor layer 14 and accumulated as energy, which also contributes to latent image formation. That is, the stimulable phosphor layer 14 is exposed to the emitted light of the radiation absorbing phosphor from both sides thereof.

The irradiation of radiation may be carried out from the opposite side by arranging the radiation image forming material 10 in the opposite direction. Further, when the subject itself emits radiation such as β-ray as in the case of autoradiography, the subject itself serves as a radiation source, and thus it is not necessary to separately provide a radiation source.

Next, the spatial energy distribution information of the subject recorded in the radiation image forming material 10 is read by using the radiation image information reading device of FIG.

In FIG. 14, radiation image forming material 1
Each electrode of the front side light transmissive electrode layer 13 of 0 is connected to the X direction control circuit 51 of the device, and each electrode of the back side light transmissive electrode layer 15 is connected to the Y direction control circuit 52. The photoconductive layer electrode layer 17 is connected to the signal processing unit 55.

When the voltages from the voltage sources 53 and 54 are applied to the stimulable phosphor layer 14 through the control circuits 51 and 52 in the X and Y directions, the stimulable phosphor in the stimulable phosphor layer 14 is subjected to an electric field. Upon being excited, light corresponding to the stored energy level (that is, carrying the energy distribution information of the radiation recorded and stored as a latent image) is emitted. The application of the electric field may be an AC pulse or a DC pulse, or may be a single pulse or a plurality of pulses. Application of an electric field to the stimulable phosphor layer 14 is performed by the control circuit 5
Since the two-dimensional control in the X direction and the Y direction is performed by the elements 1 and 52, only a minute region of the phosphor layer 14 corresponding to the portion where each one electrode of the electrode layers 13 and 15 is orthogonal is excited by an electric field. become. Then, the emitted light passes through the light transmissive electrode layer 15 and enters the photoconductive layer 16, and is converted into a photocurrent by the photoconductive layer 16. This photocurrent is generated by the photoconductive layer electrode layer 17
Is output to the signal processing unit 55. Control circuit 51, 52
Are controlled and managed by the signal processing unit 55. In this way
The emitted light having radiation image information is photoelectrically converted in time series and detected.

The signal processing unit 55 performs appropriate arithmetic processing such as addition and subtraction on the sent electric signal, which is predetermined based on the type of the intended radiation image and the characteristics of the radiation image forming material. , Sends the processed signal as an image signal.

The image signal sent out is reproduced as a visible image by an image reproducing device (not shown), whereby an image corresponding to the spatial energy distribution of radiation relating to the subject is reconstructed. The reproducing device may be a display device such as a CRT, a liquid crystal display device, or an electroluminescence (EL) device, or a recording device for performing optical scanning recording on a photosensitive film or thermal recording with a thermosensitive recording film. Alternatively, for that purpose, the image signal may be replaced with a device for temporarily storing the image signal in an image file such as an optical disk or a magnetic disk.

Radiation image forming material 1 after reading
An electric field is applied to the stimulable phosphor layer 14 of 0 through the electrode layers 13 and 15 again by the voltage sources 53 and 54, and the stimulable phosphor layer 14 is subjected to the erasing step. As a result, the accumulated energy remaining in the stimulable phosphor layer after the reading step is released and removed so that the latent image due to the residual energy does not adversely affect the next radiation image recording (imaging) step. To be done. Sodium lamp,
Irradiation from an erasing light source such as a fluorescent lamp or an infrared lamp may be used, or irradiation of erasing light and application of an electric field may be used together.

In the case of a line-scanning type radiation image forming material having a photoconductive layer (FIGS. 1 and 3), the radiation image information is read using an apparatus as shown in FIG. Figure 15
FIG. 3 is a schematic perspective view showing an example of the configuration of a radiation image information reading device that uses current detection by line scanning.

In FIG. 15, the radiation image forming material 10 is shown.
Front and back side light-transmissive electrode layers 13, 1
Each electrode of 7 is connected to the X-direction control circuit 51 of the device,
It is connected to the Y-direction control circuit 52. Photoconductive layer electrode layer 1
The electrode of No. 5 covers the entire surface.

When the voltage from the voltage source 53 is applied to the stimulable phosphor layer 14 through the control circuit 51 in the X direction, the stimulable phosphor in the stimulable phosphor layer 14 is excited by an electric field and accumulated. Light is emitted corresponding to the radiation image depending on the energy level. Since the electric field is applied to the stimulable phosphor layer 14 by the one-dimensional control in the X direction only by the control circuit 51, the phosphor layer 1 corresponding to the electrode portion of the electrode layer 13 is formed.
Only the linear region of 4 will be field excited. Then, the emitted light passes through the light transmissive electrode layer 15 and passes through the photoconductive layer 1.
6 and is converted into photocurrent by the photoconductive layer 16. This photocurrent is individually output from each electrode of the photoconductive layer electrode layer 17 under the control of the Y-direction control circuit 52, and sent to the signal processing unit 55. The control circuits 51 and 52 are controlled and managed by the signal processing unit 55. In this way, the emitted light having the radiation image information is one-dimensionally sequentially photoelectrically converted and detected.

In the case of the point scanning type radiation image forming material having the optical waveguide type fluorescence condensing layer (FIGS. 6 to 8), the radiation image information is read using the apparatus as shown in FIG. FIG. 16 is a schematic perspective view showing an example of the configuration of a radiation image information reading apparatus that uses light detection by point scanning.

In FIG. 16, the radiation image forming material 20 is used.
Each electrode of the front-side light-transmissive electrode layer 23 of the
It is connected to the direction control circuit 61, and each electrode of the back side light transmissive electrode layer 25 is connected to the Y direction control circuit 62. The voltage from the voltage sources 63 and 64 is two-dimensionally controlled by the control circuits 61 and 62 in the X and Y directions, and the stimulable phosphor layer 2
When applied to No. 4, the stimulable phosphor in the applied minute region in the stimulable phosphor layer 24 is excited by an electric field, and light corresponding to the accumulated energy level is emitted. The emitted light passes through the light-transmissive electrode layer 25, enters the optical waveguide type fluorescence collecting layer 26, is excited by it, and the light emitted from the optical waveguide type fluorescence collecting layer 26 is totally reflected and Toward the end face 262 on which the photodetector 65 having a circular shape is installed. And the end face 2
The light is emitted from 62, photoelectrically converted in time series by the photodetector 65, and then output to the signal processing unit 66. The photodetector 65 may be divided into a plurality of parts, and a photomultiplier tube, a photodiode, or the like can be used.

In the case of the line-scanning type radiation image forming material having a light collecting layer composed of a large number of light collecting elements (FIGS. 6 and 9), a device as shown in FIG. Read. FIG. 17 is a schematic perspective view showing an example of the configuration of a radiation image information reading device that uses light detection by line scanning.

In FIG. 17, the radiation image forming material 2
0 front and back side light-transmissive electrode layers 23,
Each of the 25 electrodes is connected to the X-direction control circuit 61 of the device. When the voltage from the voltage source 63 is one-dimensionally controlled by the control circuit 61 in the X direction and applied to the stimulable phosphor layer 24, the stimulable phosphor in the linear region to which the stimulable phosphor layer 24 is applied is applied. Is excited by an electric field, and light corresponding to the stored energy level is emitted. The emitted light passes through the light-transmissive electrode layer 25 and is incident on each condensing element 263 of the optical waveguide type fluorescent condensing layer 26, and the emitted light is reflected while totally reflecting inside the condensing element 263. Head toward the end face where the detector 67 is installed. Then, the light is individually emitted from each end face, and one-dimensionally photoelectrically converted by the photodetector 67, and then the signal processing unit 6
6 is output. As the one-dimensional photodetector 67, a line sensor or the like in which a large number of solid-state image pickup devices are linearly arranged can be used.

In the reader shown in FIGS. 14 to 17, the secondary excitation is performed by applying an electric field and the photodetector is fixed to the device, so that the device having no movable parts can be realized. Therefore, the device can be significantly downsized, at the same time the cost can be reduced, and the device can be easily moved or carried. For example, in the case of the reading device shown in FIG. 14, if the control circuit and the signal processing unit can be housed in the cassette, the digital signal having the image information can be directly obtained only by connecting the power supply to the cassette. Furthermore, wireless signal transmission is also possible, and if the power supply is built into the cassette, it can be made cordless.

In the method of the present invention, the image information is read at a practical speed by adopting the point scanning type or the line scanning type according to the response speed of the stimulable phosphor used for the radiation image forming material. be able to. Furthermore, it is possible to alternately perform radiation irradiation and reading of the radiation image forming material, and further add an erasing step after that, and by taking the difference from the immediately preceding read data, it is also possible to support moving images. is there.

In the case of the point scanning type, if the area of the photoconductive layer is large and there is a problem in response, the electrode layer for the photoconductive layer may be divided. Further, when the emitted light is detected from the entire surface of the photoconductive layer, the afterglow may be a problem, but the effect of the afterglow can be suppressed by reading at high speed.

In the case of a point scanning type radiation image forming material having neither a photoconductive layer nor an optical waveguide type condensing layer (FIGS. 10 and 2), the radiation image information can be read using an apparatus as shown in FIG. To do. The reading is performed from the surface of the radiation image forming material 30 on the side of the support (protective layer) 39. FIG. 18 is a schematic perspective view showing an example of the configuration of a radiation image information reading apparatus that uses light detection by point scanning.

In FIG. 18, the radiation image forming material 30 is used.
Each electrode of the front-side light-transmissive electrode layer 33 of the
It is connected to the direction control circuit 71, and each electrode of the back side light transmissive electrode layer 35 is connected to the Y direction control circuit 72. The voltage from the voltage sources 73 and 74 is two-dimensionally controlled by the control circuits 71 and 72 in the X and Y directions, and the stimulable phosphor layer 3 is formed.
When applied to No. 4, the stimulable phosphor in the applied minute region in the stimulable phosphor layer 34 is excited by an electric field, and light corresponding to the accumulated energy level is emitted. The emitted light passes through the light transmissive electrode layer 35 to the support 39 and is emitted from the surface of the radiation image forming material 30. The emitted light is condensed by the light collecting guide 75 provided on the surface of the image forming material, and is condensed. After being photoelectrically converted in time series by a photodetector 76 connected to the guide 75, it is output to the signal processing unit 77. As the photodetector 76, a photomultiplier tube, a photodiode or the like is used. The condensing guide 75 and the photodetector 76 condense and detect the emitted light over the entire surface of the radiation image forming material 30 while sequentially moving in the direction of the arrow according to the application speed of the electric field.

In the case of a line-scanning type radiation image forming material having neither a photoconductive layer nor an optical waveguide type light collecting layer (FIGS. 10 and 3), the radiation image information can be read using an apparatus as shown in FIG. To do. The reading is performed from the surface of the radiation image forming material 30 on the support 39 side. FIG. 19 is a schematic perspective view showing an example of the configuration of a radiation image information reading apparatus that uses light detection by line scanning.

In FIG. 19, the radiation image forming material 30 is used.
Front and back side light-transmissive electrode layers 33, 3
Each electrode of 5 is connected to the X-direction control circuit 71 of the device. When the voltage from the voltage source 73 is one-dimensionally controlled by the control circuit 71 in the X direction and applied to the stimulable phosphor layer 34, the stimulable fluorescent light in the linear region to which the stimulable phosphor layer 34 is applied is applied. The body is excited by an electric field and emits light according to the stored energy level. The emitted light passes through the light-transmissive electrode layer 35 to the support 39 and the radiation image forming material 30.
Is linearly emitted from the surface of the image forming material, is one-dimensionally photoelectrically converted by a photodetector 78 provided on the surface of the image forming material, and is then output to the signal processing unit 77. One-dimensional photodetector 7
A line sensor or the like is used as 8. Photo detector 7
Reference numeral 8 collects and detects emitted light over the entire surface of the radiation image forming material 30 while sequentially moving in the direction of the arrow according to the application speed of the electric field.

In the reader shown in FIGS. 18 and 19, the reading is carried out while moving the photodetector such as the photomultiplier tube or the line sensor, but the light is used for the secondary excitation as in the conventional case. Therefore, the problem of wavelength separation between the excitation light and the emitted light does not occur, and since the emitted light is amplified by the application of the electric field, the light collection efficiency of the light collection system and / or the quantum efficiency of the photodetector are improved. Even if it is low, the image quality of the radiation image is unlikely to be deteriorated, so that the restriction on the design of the apparatus can be relieved significantly.

In the case of the radiation image forming assembly (FIG. 11), first, the radiation image conversion panel 40a and the fluorescent screen 40b of the radiation image forming assembly 40 are provided in the respective protective layers 4.
After they are superposed in close contact with each other so that 6 and 49 are in contact with each other, radiation is irradiated from the side of the conversion panel 40a in the same manner as described above to record radiation image information on the conversion panel 40a. At this time, it is desirable to fix the assembly in a close contact state with a cassette, and the fluorescent screen 40b
Normally, it is desirable to use it by fixing it in the cassette.
Alternatively, a similar configuration can be used inside the radiographic imaging table. Further, the irradiation of the radiation may be performed from the side of the fluorescent screen 40b by reversing the positions of the conversion panel 40a and the fluorescent screen 40b.

Next, the conversion panel 40a and the fluorescent screen 40b which are in close contact are separated from each other, and only the conversion panel 40a is loaded into the reading device shown in FIG. 18 or 19, and the radiation image information is read in the same manner as described above. I do. At this time, the conversion panel 40a is arranged so that the side of the protective layer 46 faces upward (to the photodetector side). When the conversion panel 40a is of the point scanning type (13a and 15a in FIG. 2), FIG.
Electric field excitation is performed by point scanning using the apparatus shown in FIG.
On the other hand, when the conversion panel 40a is a line scanning type (13b and 15b in FIG. 3), electric field excitation is performed by line scanning using the device shown in FIG.

When the radiation image conversion panel has a structure as shown in FIG. 12 (no radiation absorbing phosphor layer), the support and the protective layer are made transparent,
The emitted light can be read from both sides of the conversion panel.
For example, in FIG. 18, by arranging the condensing guide 75 and the photodetector 76 also on the lower surface of the radiation image conversion panel 40a, reading can be performed from both sides of the conversion panel 40a.

[0154]

According to the present invention, the radiation absorption function and the energy storage function of the phosphor relating to the radiation image formation are separated so that the two types of phosphors share the respective functions, and the phosphor having the radiation absorption function is selected. By using a phosphor having a high radiation absorptivity and exposing the stimulable phosphor layer from both sides, image formation with high detection quantum efficiency can be realized. Further, by using a phosphor capable of exciting an electric field as a phosphor having an energy storage function, it is possible to achieve image formation with higher detection quantum efficiency without using the photoexcitation system device used in the conventional method. it can. As a result, it is possible to reduce the exposure dose to the subject (subject), or when the subject itself emits radiation, such as in autoradiography,
It is possible to analyze a smaller amount of radiation.

Further, according to the radiation image forming method of the present invention, the radiation image forming material is made to have the light detecting function and the light collecting function so that the radiation image information can be read by using the reading device having no movable parts. It is possible to realize high-speed reading, drastic downsizing of the device, cost reduction, and portability. Then, it is possible to obtain the two-dimensional information of radiation also in X-ray analysis and autoradiography.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a typical example of the constitution of a radiation image forming material of the present invention.

FIG. 2 is a top view showing an example of the configuration of a light transmissive electrode layer according to the present invention.

FIG. 3 is a top view showing another example of the configuration of the light transmissive electrode layer according to the present invention.

FIG. 4 is a schematic sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 5 is a schematic sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 6 is a schematic sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 7 is a schematic cross-sectional view showing an example of an optical waveguide type fluorescent light collecting layer.

FIG. 8 is a top view showing an example of the structures of a light transmissive electrode layer and an optical waveguide type light collecting layer used in the radiation image forming material of the present invention.

FIG. 9 is a top view showing another example of the configuration of the light transmissive electrode layer and the optical waveguide type light collecting layer according to the present invention.

FIG. 10 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 11 is a schematic cross-sectional view showing a typical example of the configuration of the radiation image forming assembly of the present invention.

FIG. 12 is a schematic cross-sectional view showing another example of the configuration of the radiation image forming assembly of the present invention.

FIG. 13 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 14 is a schematic perspective view showing an example of the configuration of a reading device used in the radiation image forming method of the present invention.

FIG. 15 is a schematic perspective view showing another example of the configuration of the reading device used in the radiation image forming method of the present invention.

FIG. 16 is a schematic perspective view showing another example of the configuration of the reading device used in the radiation image forming method of the present invention.

FIG. 17 is a schematic perspective view showing another example of the configuration of the reading device used in the radiation image forming method of the present invention.

FIG. 18 is a schematic perspective view showing another example of the configuration of the reading device used in the radiation image forming method of the present invention.

FIG. 19 is a schematic perspective view showing another example of the configuration of the reading device used in the radiation image forming method of the present invention.

FIG. 20 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 21 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 22 is a schematic cross-sectional view showing another example of the constitution of the radiation image forming material of the present invention.

FIG. 23 is a schematic sectional view showing another example of the constitution of the radiation image forming material of the present invention.

[Explanation of symbols]

10, 20, 30 Radiation image forming material 40 Radiation image forming assembly 40a Radiation image conversion panel 40b Fluorescent screen 12, 18, 22, 28, 32, 38, 42, 48 Radiation absorbing phosphor layer 13, 15, 17 , 23, 25, 33, 35, 43, 4
5 Light-transmissive electrode layers 14, 24, 34, 44 Storage phosphor layer 16 Photoconductive layer 26 Optical waveguide type fluorescent light condensing layer 51 X direction control circuit 52 Y direction control circuit 53, 54 Voltage source 55 Signal processing unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 42/02 G03B 42/02 B 5F088 H01L 27/14 H04N 5/32 27/146 H01L 31/00 A 31 / 09 27/14 C H04N 5/32 K F Term (Reference) 2G083 AA02 AA03 BB03 BB04 CC02 CC07 CC08 CC10 DD02 DD11 DD16 DD17 DD18 EE02 EE03 2G088 EE01 FF02 GG10 GG14 GG15 GG01 ACC3 JJ01 JJ01 JJ01 JJ01 JJ01 JJ04 JJ01 JJ01 JJ04 JJ01 JJ01 JJ04 JJ01 JJ01 JJ04 JJ01 JJ01 JJ04 BA05 CA14 CA32 CB11 FB09 FB25 FB26 5C024 AX11 AX16 CX00 5F088 AA11 AB05 BA01 BA02 BA15 BA20 BB07 DA20 EA07 EA08 EA09 EA11 EA16 FA04 FA05 FA09 FA11 FA14 HA10 HA12 LA15 HA20 JA20 KA02 LA08 KA03 KA08 LA08

Claims (17)

[Claims] 1. At least one radiation-absorbing phosphor layer containing a phosphor that absorbs radiation and emits light, absorbs this light and accumulates its energy, and the accumulated energy is converted into light by electric field excitation. A stimulable phosphor layer containing a stimulable phosphor that emits light, a pair of electric field applying electrode layers attached to the upper surface and the lower surface of the stimulable phosphor layer, at least one side of which is light transmissive, and the accumulator. Image forming material including a two-dimensional photodetection layer provided on the side of the light-transmitting electrode layer of the fluorescent layer. 2. A two-dimensional photodetection layer, a photoelectric conversion layer, and a pair of electrode layers provided on the upper surface and the lower surface of the photoelectric conversion layer (provided that at least the surface on the stimulable phosphor layer side is provided). The radiographic imaging material according to claim 1, wherein the electrode layer is transparent. 3. The radiation image forming material according to claim 1, wherein the two-dimensional photodetection layer includes an optical waveguide type fluorescent light condensing layer. 4. The radiation absorbing phosphor layer, the light transmissive electrode layer, the storage phosphor layer, the light transmissive electrode layer, and the two-dimensional photodetection layer are laminated in this order. The radiation image forming material according to any one of the above items. 5. A radiation-absorbing phosphor layer, a two-dimensional photodetection layer, a light-transmitting electrode layer, a storage phosphor layer, and a light-transmitting or light-impermeable electrode layer are laminated in this order. The radiation image forming material according to any one of claims 1 to 3. 6. A first radiation-absorbing phosphor layer, a light-transmitting electrode layer, a stimulable phosphor layer, a light-transmitting electrode layer, a two-dimensional photodetection layer, including two radiation-absorbing phosphor layers. The radiation image forming material according to claim 1, wherein the second radiation absorbing phosphor layer is laminated in this order. 7. A radiation-absorbing phosphor layer, a first two-dimensional photodetecting layer, a light transmissive electrode layer, comprising two two-dimensional photodetecting layers.
The radiation image forming material according to claim 1, wherein the stimulable phosphor layer, the light transmissive electrode layer, and the second two-dimensional photodetection layer are laminated in this order. 8. A first radiation-absorbing phosphor layer, comprising two layers each of a radiation-absorbing phosphor layer and a two-dimensional photodetection layer,
A first two-dimensional photodetection layer, a light transmissive electrode layer, a storage phosphor layer, a light transmissive electrode layer, a second two-dimensional photodetection layer, and a second radiation absorbing phosphor layer are laminated in this order. The radiation image forming material according to any one of claims 1 to 3, wherein 9. A pair of electrode layers for applying an electric field of a stimulable phosphor layer, each of which is composed of a large number of strip electrodes arranged regularly in parallel in a plane direction, or one of which is an integral electrode. The radiation image forming material according to any one of claims 1 to 8. 10. The radiation image forming material according to claim 1, wherein the radiation is transmitted through a subject, diffracted or scattered by the subject, or emitted from the subject. And the two-dimensional distribution of the energy of the radiation is recorded as a latent image directly on the stimulable phosphor layer of the forming material and further through the light converted from the radiation in the radiation-absorbing phosphor layer. After that, an electric field is applied to the stimulable phosphor layer to emit light from the latent image of the stimulable phosphor layer, and the light is photoelectrically converted by the two-dimensional photodetection layer to correspond to the latent image. Radiation image formation comprising obtaining an image signal and electrically processing the image signal to form an image corresponding to a two-dimensional distribution of radiation energy recorded as a latent image in the stimulable phosphor layer. Method. 11. At least one radiation-absorbing phosphor layer containing a phosphor that absorbs radiation and emits light, absorbs this light and accumulates its energy, and the accumulated energy is converted into light by electric field excitation. A radiation image forming material comprising: a stimulable phosphor layer containing a stimulable phosphor that emits light; and a pair of light-transmissive electrode layers for applying an electric field, which are attached to an upper surface and a lower surface of the stimulable phosphor layer. 12. A pair of light-transmissive electrode layers for applying an electric field of a stimulable phosphor layer, each of which is composed of a large number of strip-shaped electrodes regularly arranged in a plane direction, or one of which is an integrated electrode. The radiation image forming material according to claim 11, which is 13. The radiation image forming material according to claim 11 or 12 is irradiated with radiation that has been transmitted through a subject, diffracted or scattered by the subject, or radiated from the subject to form the image. After the two-dimensional distribution of energy of the radiation is recorded as a latent image directly in the stimulable phosphor layer of the material and further through the light converted from the radiation in the radiation-absorbing phosphor layer, the stimulable phosphor layer is recorded. An electric field is applied to the body layer to cause light to be emitted from the latent image of the stimulable phosphor layer, and the light is passed through the light-transmitting electrode layer of the radiation image-forming material opposite to the side of the radiation-absorbing phosphor layer. By photoelectrically detecting from the surface of the, the image signal corresponding to the latent image is obtained, and by electrically processing the image signal, the radiation energy recorded as a latent image in the stimulable phosphor layer is obtained. Image corresponding to the two-dimensional distribution of Forming a radiographic image. 14. A fluorescent screen having a radiation-absorbing phosphor layer containing a phosphor that absorbs radiation and emits light, and absorbs the light to accumulate the energy, and the accumulated energy is excited by an electric field. Image conversion panel having a stimulable phosphor layer containing a stimulable phosphor that emits light by light, and a pair of light-transmissive electrode layers for applying an electric field provided on the upper surface and the lower surface of the stimulable phosphor layer For forming a radiation image. 15. A radiation-absorbing fluorescent material containing a phosphor that absorbs radiation and emits light, adjacent to either one of the light-transmitting electrode layers on both surfaces of the storage phosphor layer of the radiation image storage panel. The radiation image forming assembly according to claim 14, wherein a body layer is additionally provided. 16. A pair of light-transmissive electrode layers for applying an electric field of a stimulable phosphor layer, each of which is composed of a large number of strip-shaped electrodes regularly arranged in a plane direction, or one of which is an integrated electrode. The radiation image forming assembly according to claim 14 or 15. 17. A radiation image forming assembly comprising the radiation image conversion panel according to any one of claims 14 to 16 and a fluorescent screen, which is used as a light storage phosphor layer of a radiation image conversion panel. The fluorescent screen is closely attached to the transmissive electrode layer so that it is adjacent to the surface, and the surface of the radiation image conversion panel or the fluorescent screen is transmitted through the subject, diffracted or scattered by the subject, or emitted from the subject. A latent image of the two-dimensional distribution of the energy of the radiation is obtained by irradiating the radiation, directly on the storage phosphor layer of the radiation image conversion panel, and further through the light converted from the radiation in the radiation absorption phosphor layer. After recording as, by applying an electric field to the stimulable phosphor layer to emit light from the latent image of the stimulable phosphor layer, by photoelectrically detecting this light from the surface of the radiation image conversion panel, By obtaining an image signal corresponding to the latent image and electrically processing the image signal, an image corresponding to the two-dimensional distribution of radiation energy recorded as a latent image in the stimulable phosphor layer is formed. A radiation image forming method comprising the following.