JPH0471347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation image detection method. More specifically, the present invention relates to a radiation image detection method that utilizes a combination of a radiation image conversion panel and a photosensitive element.

Conventionally, the so-called radiographic method, which combines a radiographic film with an emulsion layer made of a silver salt photosensitive material and an intensifying screen, has been used to detect a radiation image of a subject and obtain it as an image. has been done. As an alternative to the conventional radiographic method mentioned above, for example, US Pat.
2. Description of the Related Art Radiation image conversion methods using photostimulable phosphors are known, such as those described in Japanese Patent Application Laid-Open No. 3859527 and Japanese Patent Application Laid-Open No. 12145/1983. This method is
By making a stimulable phosphor absorb the radiation that has passed through the subject or the radiation emitted from the subject, and then excited this phosphor in a time-series manner with electromagnetic waves (excitation light) such as visible light and infrared rays. This method consists of emitting radiation energy stored in a phosphor as fluorescence (stimulated luminescence) and detecting this fluorescence.

So far, in the radiation image conversion method, radiation image detection has been carried out using a radiation image conversion panel (stimulable phosphor sheet) containing a stimulable phosphor. It has been proposed to photoelectrically read out the energy image of the image using a radiation image reading device.

The radiation image conversion panel used in the radiation image conversion method described above has a basic structure consisting of a support and a phosphor layer provided on one side of the support. Note that a transparent protective film is generally provided on the surface of the phosphor layer opposite to the support (the surface not facing the support) to protect the phosphor layer from chemical deterioration or Protects from physical impact.

Furthermore, in radiation image reading devices, a photomultiplier tube is usually used as a photodetector, as disclosed in Japanese Patent Laid-Open No. 11395/1983, and the tip of the photomultiplier tube is is provided with a light guide sheet for condensing fluorescence emitted from the surface of the radiation image conversion panel and guiding it to a photodetector.

In other words, the radiation transmitted through the subject or the radiation emitted from the subject is absorbed by the phosphor layer of the radiation image conversion panel, and a radiation image of the subject or subject is formed on the panel as an image of accumulated radiation energy. Ru. Next, the accumulated image formed on this panel is excited by electromagnetic waves (excitation light) such as visible light and infrared rays in a radiation image reading device, and is emitted as stimulated luminescence (fluorescence). The emitted fluorescence is guided through a light-guiding sheet, then photoelectrically read by a photomultiplier tube and converted into an electrical signal. From the obtained electrical signal,
A radiation image of a subject or a subject can be imaged.

The radiation image conversion method has the advantage that it is possible to obtain a radiation image rich in information with a much lower exposure dose than when conventional radiography is used. Therefore, this radiation image conversion method has a very high utility value especially in direct medical radiography such as X-ray photography for the purpose of medical diagnosis.

However, the reading of the radiation image conversion panel has conventionally been carried out by irradiating the panel with light with a small beam diameter such as a laser beam in time series, that is, by scanning (main scanning or sub-scanning) with the laser beam. This is done by detecting the fluorescence emitted from the panel using a photodetector such as a photomultiplier tube and converting it into an electrical signal, and this readout operation takes a non-negligible amount of time (several tens of seconds). ing.

In addition, when reading out a radiation image conversion panel, in order to detect the fluorescence emitted in time series from each phosphor particle group on the radiation image conversion panel irradiated with excitation light, it is usually The panel is being moved (sub-scan or main scan).
Therefore, the operation for detecting (reading) the radiation image stored in the radiation image conversion panel has become complicated.

Furthermore, if a light-guiding sheet or the like is used in combination with a photomultiplier tube to efficiently detect fluorescence emitted from a radiation image conversion panel, the readout device becomes complicated and operational problems arise. is likely to occur.

Therefore, the main object of the present invention is to provide a radiation image detection method in which the above-mentioned problems in radiation image conversion methods using stimulable phosphors are solved or the drawbacks are reduced. It is something to do.

The above purpose is to absorb the radiation transmitted through the subject or emitted from the subject into a radiation image conversion panel having a phosphor layer containing a stimulable phosphor, and then to absorb the radiation transmitted through the subject or emitted from the subject. An insulating layer that transmits stimulated light emitted by a stimulable phosphor but does not transmit excitation light, or a laminate of an insulating layer that transmits stimulated light and a filter layer that transmits stimulated light but does not transmit excitation light. A photodetector consisting of a large number of photosensitive elements regularly arranged two-dimensionally is placed on top of the panel so that its insulating layer or laminate faces the panel, and then electromagnetic waves (excitation light) are applied to the panel.
This is achieved by the radiation image detection method of the present invention, which comprises emitting the radiation energy stored in the panel as photostimulated light, and photoelectrically reading this stimulated light with the photodetector. I can do it.

That is, according to the study of the present invention, after radiation such as X-rays transmitted through the subject or emitted from the subject is absorbed by the stimulable phosphor of the radiation image conversion panel, the radiation image conversion panel is By superimposing the panel on a photodetector consisting of a large number of photosensitive elements and then irradiating the panel with light in the excitation wavelength range of the photostimulable phosphor, the photosensitive elements receive the fluorescence emitted from the panel (stimulated luminescence). It has been found that image information related to the radiation image of a subject or a subject can be directly obtained as an electrical signal.

Therefore, according to the radiation image detection method of the present invention,
Compared to the radiation image readout methods proposed so far, since a photosensitive element is used as a photodetector, radiation image information is generated by electrical signals per pixel of a large number of photosensitive elements under irradiation with excitation light. The detection time of a radiation image can be significantly shortened.

In addition, the photodetector is made up of a large number of photosensitive elements and has the same size as the radiation image conversion panel, and during readout, the photodetector and the radiation image conversion panel are overlapped so as to be in close contact with each other. By this operation, the fluorescence emitted from the panel surface under the irradiation of excitation light is detected at each pixel of a large number of photosensitive elements adjacent to this panel.
There is no need to move the panel as in the conventional radiation image conversion panel readout operation, and the radiation image detection operation is simplified.

Furthermore, unlike conventional methods, there is no need to install a light-guiding sheet to collect the fluorescent light emitted from the panel surface, so it is possible to downsize the readout device, making it possible to capture the radiation image as described above. In the reading operation of the conversion panel, it is possible to eliminate problems such as adverse effects on image quality caused by mechanical transportation of the panel or detector.

This also means that even if the intensity of the radiation transmitted through or emitted from the subject is weak, the radiation image can be detected with high sensitivity; for example, in measurements such as autoradiography. It can also be used effectively.

The present invention will be explained in detail below.

The photodetector used in the present invention has a large number of photosensitive elements regularly arranged two-dimensionally in the horizontal direction to form a plane. A photosensitive element used in a photodetector includes, for example, a light receiving part for receiving fluorescence emitted from a phosphor layer, and a time series output of electric charges obtained through photoelectric conversion in the light receiving part as an electric signal. A known solid-state image sensor using an amorphous semiconductor or the like can be used as the photosensitive element.

An example of such a solid-state image sensor is MOS
(Metal Oxide Semiconductor), CCD (Charged
Coupled Device), BBD (Bucket Brigade)
Examples include sensors such as CID (Charge Isolated Device) and CID (Charge Isolated Device). Among these, MOS is particularly preferred. In addition, examples of photoconductive materials used in this solid-state imaging device include amorphous silicon (α-Si), ZnO, and CdS.

An insulating layer is provided on the side of the photodetector that is in contact with the radiation image conversion panel. Examples of the material for the insulating layer include light-transmitting and insulating materials such as glass and transparent polymer materials. This insulating layer transmits only light in the wavelength range of stimulated luminescence of the photostimulable phosphor contained in the radiation image conversion panel,
It is desirable to have a function as a filter that cuts out light in the wavelength range of the excitation light. Such a function as an optical filter can be imparted to the insulating layer by, for example, coloring the insulating layer with a coloring agent having selective light transmittance as described above.

Alternatively, a filter layer having optical transparency as described above may be provided on the insulating layer.

Furthermore, the radiation image conversion panel used in the present invention basically consists of a support and a phosphor layer, but if the phosphor layer is self-supporting, it may be composed only of the phosphor layer. You can leave it there.

The support used is one that transmits at least excitation light, and can be suitably selected from various materials used as supports for intensifying screens in conventional radiography. Examples of such materials include films of plastic materials such as cellulose acetate, polyester, polyethylene terephthalate, and the like.

The phosphor layer is generally a layer made of a binder containing and supporting particles of a stimulable phosphor in a dispersed state.

The stimulable phosphor used in the present invention is a phosphor that exhibits stimulated luminescence when irradiated with radiation and then with excitation light as described above, but from a practical point of view, the wavelength is 400~ The phosphor is preferably a phosphor that exhibits stimulated luminescence in the wavelength range of 300 to 500 nm by excitation light in the 800 nm range. Examples of such stimulable phosphors include those described in U.S. Pat. No. 3,859,527.
Phosphors expressed by composition _formulas such as SrS:Ce, Sm, SrS:Eu, Sm, _ThO2 :Er, and _La2O2S :Eu,Sm, as described in JP-A-55-12142. There is
ZnS: Cu, Pb, BaO・xAl ₂ O ₃ : Eu [however, 0.8
≦x≦10], and M ²⁺ O・xSiO ₂ :A [however,
M ²⁺ is Mg, Ca, Sr, Zn, Cd, or Ba;
A is Ce, Tb, Eu, Tm, Pb, Tl, Bi, or
A phosphor represented by a composition formula such as Mn and x is 0.5≦x≦2.5] (Ba _1-xy , Mgx, Cay) FX described in Japanese Patent Application Laid-open No. 12143/1983: aHu ²⁺ [However, X
is at least one of Cl and Br,
A phosphor represented by the composition formula: x and y are 0<x+y≦0.6 and xy≠0, and a is 10 ^-6 ≦a≦5×10 ^-2 JP-A-12144-1987 stated in the issue
LnOX: xA [However, Ln is La, Y, Gd, and
At least one of Lu, X is at least one of Cl and Br, A is at least one of Ce and Tb, and x is 0<x<0.1
A phosphor _represented by the composition formula of (Ba _1-x , M〓
At least one of Ca, Sr, Zn, and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho,
A phosphor represented by a composition formula of at least one of Nd, Yb, and Er, and x is 0≦x≦0.6, and y is 0≦y≦0.2, JP-A-55-160078 M〓 written in
FX・xA: yLn [However, M〓 is Ba, Ca, Sr,
At least one of Mg, Zn, and Cd, A
are BeO, MgO, CaO, SrO, BaO, ZnO,
Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , TlO ₂ ,
ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and
At least one of ThO ₂ , Ln is Eu, Tb,
Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Sm,
and at least one of Gd, X is Cl, Br,
and I, and x and y are respectively 5×10 ^-5 ≦x≦0.5 and 0<
y≦0.2], described in JP-A-55-116777, (Ba _1-x ,M〓 _x )F ₂・aBaX ₂ : yEu, zA
M〓 is beryllium, magnesium, calcium,
at least one of strontium, zinc, and cadmium; X is at least one of chlorine, bromine, and iodine; A is at least one of zirconium and scandium;
a, x, y, and z are each 0.5≦a≦1.25,
0≦x≦1, 10 ^-6 ≦y≦2×10 ^-1 , and 0<z
≦10 ^-2 ], which is described in Japanese Patent Application Laid-Open No. 57-23673 (Ba _1-x , M〓 _x ) F ₂・aBaX ₂ : yEu, zB ,
M〓 is beryllium, magnesium, calcium,
at least one of strontium, zinc, and cadmium;
10 ^-6 ≦y≦2×10 ^-1 and 0<z≦2×10 ^-2 ] A phosphor is described in JP-A-57-23675 (Ba _{1 -x} , M〓 _x )F ₂・aBaX ₂ :yEu, zA [however,
M〓 is beryllium, magnesium, calcium,
at least one of strontium, zinc, and cadmium; X is at least one of chlorine, bromine, and iodine; A is at least one of arsenic and silicon; a, x, y, and z are each 0.5 ≦a≦1.25, 0≦x≦1, 10 ^-6
≦y≦2×10 ^-1 and 0<z≦10 ^-1 ], M〓OX described in the specification of Japanese Patent Application No. 167498/1983 filed by the present applicant. :xCe[However, M〓 is Pr,
Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm,
is at least one trivalent metal selected from the group consisting of Yb and Bi, X is one or both of Cl and Br, and x satisfies 0<x<0.1. The represented phosphor is Ba _1-x M _x/2 L _x/2 FX:yEu ²⁺ [However,
M represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; L represents Sc, Y, La, Ce, Pr, Nd, Pm,
Sm, Gd, Tb, y, Ho, Er, Tm, Yb, Lu,
represents at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; X is Cl,
represents at least one halogen selected from the group consisting of Br, and I; and x is 10 ^-2 ≦
x≦0.5, y is 0<y≦0.1] BaFX xA:yEu ²⁺ [However, ,X is
is at least one halogen selected from the group consisting of Cl, Br, and I; A is a fired product of a tetrafluoroboric acid compound; and x is
10 ^-6 ≦x≦0.1, y is 0<y≦0.1] BaFX xA: yEu described in Japanese Patent Application No. 158048/1983 filed by the present applicant ²⁺ [However, X is
at least one halogen selected from the group consisting of Cl, Br, and I; A is a hexafluoro compound consisting of a monovalent or divalent metal salt of hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid; and x is 10 ^-6 ≦x≦0.1, and y is 0<1≦0.1. BaFX・xNaX′: aEu ²⁺ described in Application No. 166320/1987 [However,
X and X' are each at least one of Cl, Br, and I, and x and a are 0<x≦2 and 0<a≦0.2, respectively.] , M〓FX・xNaX′:yEu ²⁺ :zA [where M〓 is selected from the group consisting of Ba, Sr, and Ca at least one alkaline earth metal; X and X' are Cl, Br, and I, respectively;
at least one halogen selected from the group consisting of; A is at least one transition metal selected from V, Cr, Mn, Fe, Co, and Ni; and x is 0<x≦2, y is 0<y≦
0.2, and z is 0<z≦10 ^-2 ], M〓FX・aM〓X′ described in the specification of Japanese Patent Application No. 184455/1983 filed by the present applicant.・bM′〓X″ ₂・cM〓
X ₃・xA:yEu ²⁺ [However, M〓 is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; M〓 is Li, Na, K,
is at least one alkali metal selected from the group consisting of Rb, and Cs; M′〓 is Be and
is at least one divalent metal selected from the group consisting of Mg; M is at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; A is a metal oxide; ;X is Cl, Br,
and at least one kind of halogen selected from the group consisting of;
is at least one kind of halogen selected from the group consisting of Cl, Br, and a is 0≦
a≦2, b is 0≦b≦10 ^-2 , c is 0≦c≦10 ^-2 ,
and a+b+c≧10 ^-6 ; x is 0<x≦0.5,
y is 0<y≦0.2], and the like.

Note that the stimulable phosphor used in the present invention is not limited to the above-mentioned phosphors, but any phosphor that exhibits stimulated luminescence when irradiated with radiation and then irradiated with excitation light. It may be hot.

Examples of binders for the phosphor layer include proteins such as gelatin, polysaccharides such as dextran, or natural polymeric substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride, etc. Vinyl chloride copolymer, polymethyl methacrylate, vinyl chloride/vinyl acetate copolymer,
Examples of binders include synthetic polymeric substances such as polyurethane, cellulose acetate butyrate, polyvinyl alcohol, and linear polyester.

The phosphor layer can be formed on the support, for example, by the following method.

First, the above-mentioned stimulable phosphor particles and binder are mixed in a suitable solvent (for example, lower alcohol, ketone,
ester, ether) and thoroughly mixed to prepare a coating solution in which the phosphor particles are uniformly dispersed in the binder solution.

The mixing ratio of the binder and the stimulable phosphor particles in the coating solution varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor particles, etc., but in general, the mixing ratio of the binder and the stimulable phosphor particles is Mixing ratio is 1:1
The range is from 1:100 to 1:100 (by weight), and particularly preferably from 1:8 to 1:40 (by weight).

Note that the coating liquid contains a dispersant for improving the dispersibility of the phosphor particles in the coating liquid, and
Various additives such as a plasticizer may be mixed in order to improve the bonding force between the binder and the phosphor particles in the phosphor layer after formation.

The coating solution containing the stimulable phosphor particles and binder prepared as described above is then uniformly applied to the surface of the support to form a coating film. This coating operation can be carried out using conventional coating means such as a doctor blade, roll coater, knife coater, etc. Then, the formed coating film is dried by gradually heating it.

The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor particles, the mixing ratio of the binder and the phosphor particles, etc.
The thickness should be between 20μm and 1mm. However, the thickness of this layer is preferably 50 to 500 μm.

Note that the phosphor layer does not necessarily need to be formed by directly applying a coating liquid onto the support as described above; for example, it is possible to form the phosphor layer by separately applying the coating liquid onto a sheet such as a glass plate, metal plate, plastic sheet, etc. After the phosphor layer is formed by drying, the phosphor layer may be pressed onto the support, or the support and the phosphor layer may be bonded together using an adhesive.

In addition, the phosphor layer can be formed by other known methods.

Preferably, a transparent protective film is provided on the phosphor layer to protect the phosphor layer from physical impact and chemical alteration. This protective film may be made of, for example, a cellulose derivative such as cellulose acetate or nitrocellulose; or polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride/vinyl acetate copolymer,
It is formed from synthetic polymeric substances such as polyethylene terephthalate, polyethylene, vinylidene chloride, and polyamide. The thickness of the protective film is preferably about 3 to 20 μm.

However, in the radiation image conversion panel and photodetector used in the present invention, the wavelength range of stimulated luminescence of the stimulable phosphor contained in the panel is used in the light receiving part of the photosensitive element that is the photodetector. It is necessary to use them in combination so that they overlap with the light absorption wavelength range of the photoconductive material. That is, the photostimulable phosphor and photoconductive material used in the present invention must be selected so that at least a portion of the emission wavelength region of stimulated light overlaps at least a portion of the light absorption wavelength region of the photoconductive material. Must be. For example, when using α-Si as a photoconductive material, the stimulable phosphor is 600nm.
A phosphor having a stimulated emission wavelength in the vicinity is preferred.
In addition, as a stimulable phosphor, there is a divalent europium-activated alkaline earth metal fluorohalide phosphor (the peak wavelength of light emission is approximately 390 nm), which has a stimulable emission wavelength in the near ultraviolet to visible range. When using phosphor, ZnS is the photoconductive material.
and CdS are preferred.

Next, regarding the radiation image detection method of the present invention, the partial sectional view of the radiation image conversion panel shown in FIG. 1, the partial sectional view of the photodetector shown in FIG. 2, and the partial sectional view of the photodetector shown in FIG. A detailed description will be given with reference to an example of a circuit diagram of a photodetector.

FIG. 1 is a partial cross-sectional view of a radiation image conversion panel which is constituted of a protective film 1, a phosphor layer 2 containing a stimulable phosphor, and a support 3 in this order.

First, the radiation that has passed through the subject (or, if the subject itself emits radiation, i.e., the subject, the radiation emitted from the subject)
incident on the radiation image conversion panel. Radiation having strengths and weaknesses corresponding to the radiographic image of the subject is absorbed by the phosphor layer 2, and an accumulated image of radiation energy (a kind of latent image) corresponding to the radiographic image of the subject is formed on the phosphor layer 2. be done.

Next, this radiation image conversion panel and photodetector are
The protective film 1 of the panel shown in FIG. 1 and the insulating layer 4 of the photodetector shown in FIG. 2 are placed on the inside so that they are in close contact with each other.

FIG. 2 is a longitudinal sectional view of one pixel of the photodetector. The photosensitive element includes a photodiode 5 which is a light receiving section provided on an insulating layer 4, and a MOS:FET (Metal Oxide Semiconductor) which is a transfer section.
Field Effect Transistor)6. The insulating layer 4 has such a light transmittance that it transmits only light in the wavelength range of stimulated luminescence emitted from the radiation image conversion panel, and cuts out light in the wavelength range of excitation light. The photodiode 5 consists of, in order, a metal layer 7 such as aluminum which is ground, a p-type α-Si:H layer 8, an i-type α-Si:H layer 9, and a transparent electrode layer 10 of tin dioxide (SnO ₂ ). . Mataru
The MOS:FET 5 includes metal layers 11 and 12 such as aluminum provided at both ends, an α-Si:H layer 13 provided in this order inside these metal layers, an insulator layer 14 of silicon (SiO ₂ ), and aluminum. It consists of transfer electrodes 15 such as. This metal layer 12 is a drain and is connected to the transfer register. On the other hand, the transfer electrode 15 is a gate and is connected to a scanning pulse generator.

FIG. 3 is a schematic circuit diagram of a photodetector.
One pixel 16 corresponds to FIG. 2, and the light receiving section 17
and a transfer unit 18. In each transfer section, a scanning pulse generator 19 and a transfer register 20 are provided with output terminals 21, respectively.

Next, when electromagnetic waves in the excitation wavelength region of the stimulable phosphor are irradiated from the support 3 side of the radiation image conversion panel shown in FIG. 1, the accumulated radiation energy image formed on the phosphor layer 2 is Fluorescence (stimulated luminescence)
radiated as. This fluorescence is proportional to the intensity of radiation energy absorbed by the phosphor layer 2. Only the emitted fluorescence is received by a photodiode 5 passing through an insulating layer 4 which also serves as a filter of the photosensitive element shown in FIG. 2, and a signal charge is generated in the photodiode 5. In this way, a signal charge is generated in each pixel of the photosensitive element in proportion to the luminance of fluorescence, that is, the intensity of the radiation incident on the phosphor layer of the radiation image conversion panel.

In the circuit diagram shown in FIG. 3, when a transfer pulse is sent from the scanning pulse generator 19 to each pixel in the top row, the switch of each transfer section in the top row is turned on (in FIG. 2, voltage is applied to the transfer electrode 15). This results in a state in which current flows between metal layers 11 and 12.
That is, the signal charge generated in the photodiode 5 shown in FIG. 2 is transferred through the MOS:FET 6. Therefore, the signal charges of each pixel in the top row are sent to the transfer register 20 simultaneously. Transfer register 2
From the output terminal 21 of 0, electrical signals for each pixel are extracted in time series.

In this way, transfer pulses are sent from the scanning pulse generator 19 to each column sequentially from the top column to the bottom column in FIG. 3, and electrical signals from each pixel in each column containing radiation image information are sent to the output terminal 21 and is output in chronological order.

The electrical signal output from the photodetector is amplified by an amplifier and reproduced as an image by an image reproduction device. The electrical signal obtained here may be subjected to image processing such as spatial frequency processing, gradation processing, averaging processing, reduction processing, and enlargement processing, if desired. The obtained image may then be recorded on a recording medium or displayed on an image display device. As the recording medium, for example, one that records optically by scanning a photographic light-sensitive material with a laser beam or the like, and one that records on a light-sensitive recording material using heat rays can be used. Further, as the image display device, display devices based on various principles can be used, such as one that displays electronically on a CRT or the like, or one that records a radiation image displayed on a CRT or the like on a video printer or the like. Further, this radiation image information of the subject may be recorded and stored on a magnetic tape or the like.

In addition, as a photosensitive element of the photodetector used in the present invention, for example, one pixel has a size of approximately 200 μm x 200 μm.
can be used. For example, the size of the radiation image conversion panel and photodetector should be set to about the same size as a conventional radiation intensifying screen (430 mm x
354mm), the photodetector is 2150 x 1750
Consists of pixels. α-Si is preferable as a material for a uniform photosensitive element that forms such a large area, and it is desirable that the area of the light receiving portion be as large as possible. In a photodetector having the structure and size as described above, the pulse output from the scanning pulse generator of the photosensitive element is preferably about 3 kHz, for example.

However, the radiation image conversion panel, photodetector, and photosensitive element included therein used in the present invention are
It is not limited to the above size.

The radiation image conversion panel used in the present invention is not limited to the configuration illustrated in FIG. Any configuration is possible as long as it is possible. Furthermore, the photodetector composed of a large number of photosensitive elements used in the present invention is not limited to the configuration illustrated in FIGS. It can take any form as long as the photostimulance can be read.

Furthermore, the radiation image detection method of the present invention is not limited to the methods exemplified above, for example,
As a method for detecting the radiation image stored and recorded in the phosphor layer of the radiation image conversion panel, a preliminary operation is performed by irradiating weak electromagnetic waves to measure the amount of photostimulated light before the main operation described above. It's okay,
Based on the results of this preliminary operation, it is also possible to set the amplification factor of the obtained electrical signal, the reproduction image processing conditions, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic partial sectional view of a radiation image conversion panel used in the radiation image detection method of the present invention. 1: Protective film, 2: Phosphor layer, 3: Support FIG. 2 is a schematic partial cross-sectional view of a photodetector used in the radiation image detection method of the present invention. 4: Insulating layer, 5: Photodiode, 6:
MOS: FET, 7: Metal layer, 8: p-type α-Si:H
layer, 9: i-type α-Si:H layer, 10: transparent electrode layer,
11, 12: metal layer, 13: α-Si:H layer, 1
4: Insulator layer, 15: Transfer electrode FIG. 3 is a schematic circuit diagram of a photodetection method used in the radiation image detection method of the present invention. 16: one pixel, 17: light receiving section, 18: transfer section,
19: Scanning pulse generator, 20: Transfer register,
21: Output terminal.

Claims (1)

[Claims] 1. Radiation transmitted through a subject or emitted from a subject is absorbed by a radiation image conversion panel having a phosphor layer containing a stimulable phosphor,
Next, a photodetector comprising a large number of photosensitive elements regularly arranged two-dimensionally on the panel and an insulating layer that transmits stimulated light emitted by the stimulable phosphor but does not transmit excitation light. are stacked so that the insulating layer faces the panel, and then the panel is irradiated with excitation light to release the radiation energy stored in the panel as photostimulated light. A radiation image detection method comprising photoelectrically reading the photodetector. 2. The radiation image detection method according to claim 1, wherein the phosphor layer contains a divalent eurobium-activated alkaline earth metal fluorohalide phosphor. 3. The radiation transmitted through the subject or emitted from the subject is absorbed by a radiation image conversion panel having a phosphor layer containing a stimulable phosphor,
Next, a large number of photosensitive elements are arranged on a laminate of the panel, an insulating layer that transmits the stimulated light emitted by the stimulable phosphor, and a filter layer that transmits the stimulated light but does not transmit the excitation light. After stacking the photodetectors arranged in a two-dimensional manner so that the stack faces the panel, the panel is irradiated with excitation light to detect the radiation accumulated in the panel. A radiation image detection method comprising emitting energy as photostimulated light and photoelectrically reading this stimulated light using the photodetector. 4. The radiation image detection method according to claim 3, wherein the phosphor layer contains a divalent eurobium-activated alkaline earth metal fluorohalide phosphor.