JP2003021683A - Radiation image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation image pickup device capable of obtaining a radiation image of high image quality while minimizing exposure of a subject to a radiation, in which detectors to control the radiation are efficiently or effectively disposed, and in which deterioration or irregularity of resolution or MTF is restricted. SOLUTION: This radiation image pickup device is composed of a scintillator to convert the radiation into light, a first light detector comprising plural light detecting elements arranged in a two-dimensional form to detect light from the scintillator, a second light detector disposed on a back surface of the first light detector, and a light absorbing body disposed in a range of the back surface of the first light detector other than a range where the second light detector is disposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image capturing apparatus provided with a radiation image detecting section composed of a solid-state image sensor, and more particularly to detecting means for controlling the radiation dose to which the radiation image detecting section is exposed. The present invention relates to a radiation image capturing device.

[0002]

2. Description of the Related Art A method for obtaining a radiation image of an object by irradiating the object and detecting the intensity distribution of radiation transmitted through the object is widely used in industrial nondestructive inspection and medical diagnosis. Has been done.

Due to recent advances in semiconductor process technology,
It is possible to fabricate a solid-state photodetector that is formed by arranging a solid-state photodetection element composed of an amorphous semiconductor film, a transparent conductive film and a conductive film sandwiching the amorphous semiconductor film on a substrate such as quartz glass in a matrix. A radiation detector constructed by stacking this solid-state photodetector and a scintillator that converts radiation into visible light is disclosed in Japanese Patent Laid-Open No. 59-1999, No. 21263.
It is disclosed in the publication.

This radiation detector converts the radiation that has passed through the object into visible light by means of a scintillator, and this visible light is detected as an electric signal by the photoelectric conversion section of the solid-state light detecting element. This electric signal is read from each solid-state photodetector by a predetermined reading method and then A / D converted, and as a result, a digital radiation image signal is obtained. This radiation image signal is subjected to various kinds of signal processing by the image signal processing device in the subsequent stage, and then reproduced as a radiation image by a reproducing means such as a CRT, and is read and diagnosed by a doctor.

By the way, one of the important problems in radiography used for medical diagnosis is to obtain a high-quality radiographic image having the maximum diagnostic ability while minimizing the radiation exposure of the subject.

A radiation detector constructed by stacking a solid-state photodetector having solid-state photodetection elements arranged in a matrix and a scintillator for converting radiation into visible light is a silver salt film and a fluorescent plate (or The radiation dose range (dynamic range) that can be detected is wider than that of a radiation detector consisting of an intensifying screen, and the image signal converted into an electrical signal can be obtained immediately, so that the image after image processing can also be obtained immediately. The advantage is that Therefore, the control of the incident radiation dose does not necessarily need to be strict as compared with the imaging method using a silver salt film and a fluorescent plate that often use a so-called photo timer. The photo timer is generally configured separately from the radiation detector, and is arranged between the subject and the radiation detector. As a configuration example of radiation dose control by a phototimer, a substrate made of an acrylic resin plate is thinly coated with a phosphor, and the phosphor emits light by irradiation with radiation.
The acrylic resin plate is taken out from the end face of the acrylic resin plate as a light guide, the light from the end face is guided to the photomultiplier tube and converted into an electric signal, and based on this electric signal amount,
There is a method of controlling the irradiation time (radiation dose) of radiation.

Generally, when the amount of radiation incident on the radiation detector is small, the granularity of the radiation image is deteriorated due to fluctuations of radiation photons, and the diagnostic ability is deteriorated. Further, if a large amount of radiation is set in advance, a high-quality radiation image with good graininess can be obtained, but there is a problem in that the exposure dose of the subject increases. Reducing the exposure dose to a subject is one of the important issues in today's radiation diagnosis.

Therefore, an imaging method using a radiation detector constructed by stacking solid-state photodetectors constructed by arranging the solid-state photodetection elements in a matrix and a scintillator for converting radiation into visible light is also It is desirable to use a photo timer in order to obtain a high quality radiation image while minimizing the radiation exposure of the subject.

However, providing the photo timer separately from the radiation detector causes an increase in cost and the like, and providing the photo timer between the subject and the radiation detector causes the photo timer to emit radiation. This causes problems such as absorption and increase in radiation exposure of the subject. Therefore, in order to solve such a problem, Japanese Patent Laid-Open No. 73144 of 1997 discloses a radiation detection device for detecting the intensity distribution of radiation emitted from a radiation source and transmitted through an object. A scintillator that emits light in response to the light, a light image detecting means formed by forming a solid-state light detecting element two-dimensionally on the front surface of a transparent substrate arranged behind the scintillator, and a light image detecting means behind the light image detecting means. Disclosed is an apparatus, which has a light quantity monitor means for detecting the quantity of light emitted from the scintillator and transmitted through the substrate.

On the other hand, in the photoelectric conversion device, the light to be received (for example, in the case of an X-ray imaging device, the light generated by the X-rays from the X-ray source entering the phosphor) is a photoelectric conversion element. After entering the substrate, the light may be reflected by the back surface or the end face of the substrate and enter the light receiving portion of the photoelectric conversion element, which may lead to deterioration in characteristics of the photoelectric conversion device including a reduction in resolution or MTF.
Therefore, in Japanese Patent Laid-Open No. 298287/1997, light to be received, such as light emitted from the phosphor layer (scintillator), is reflected by the back surface of the photoelectric conversion substrate other than the photoelectric conversion unit and is received. Resolution problem or resolution or M
In order to improve characteristics such as TF, a technique is disclosed in which a light absorber is provided on at least one of a back surface and an end surface of a substrate.

[0011]

However, in Japanese Patent Laid-Open No. 73144 of 1997, since the light amount monitor means is partially arranged on the back side of the transparent substrate, light reflection or scattering on the back side of the substrate is prevented. This results in non-uniformity, which in turn leads to deterioration or non-uniformity in resolution or MTF of the radiation image capturing apparatus. Therefore, in view of such problems, the present invention provides a radiation image capturing apparatus in which detectors for controlling radiation are arranged efficiently or effectively, and deterioration or nonuniformity of resolution or MTF is suppressed. The purpose is to provide.

[0012]

Therefore, a radiographic image capturing apparatus according to one aspect of the present invention has a scintillator for converting radiation into light and a plurality of photodetecting elements arranged in a two-dimensional manner, A first photodetector that detects light from a scintillator, and a second light that is disposed on the back surface of the first photodetector and that detects light from the scintillator that has passed through the first photodetector. It has a detector and a light absorber arranged in a field other than the field where the 2nd photodetector is arranged among the backs of the 1st photodetector. In such a radiation image capturing apparatus, the light absorber prevents uneven light reflection as in the conventional case.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an example of the apparatus configuration in the case of capturing a chest radiographic image of the subject S. The imaging device 3 supported by the support means 2 is disposed in front of the radiation source 1 that generates the radiation X, and the imaging device 3
The subject S to be subjected to radiation diagnosis on the radiation incidence part 4 of
Is located. The radiation incident unit 4 is made of a material having a high radiation transmittance while keeping the inside of the imaging device 3 light-tight.

FIG. 2 is a block diagram of the image pickup apparatus 3 according to the first embodiment. A radiation detector (radiation image detection unit) indicated by a chain line is provided in the imaging device 3, and a flat plate-shaped scintillator 5 that emits light by the radiation X transmitted through the subject S from the radiation incident unit 4 side, an optical image. A detector 6 and a light amount monitor 7 are arranged.

As the scintillator 5, GdO ₂ S: T
b, CaWO ₄ , C ₅ I: Tl, CaI: Na, and other fluorescent materials, and so-called scintillation fibers in which the fluorescent material is doped into the fiber plate may be used. The light image detection unit 6 joined to the scintillator 5 is configured by forming a large number of solid-state light detection elements two-dimensionally on the front surface of a transparent glass substrate 8 by a photolithography method. Further, the light quantity monitor unit 7 is configured by forming a solid-state photodetection element on the rear surface of the glass substrate 8 by the photolithography method, and among the light generated by converting the radiation X by the scintillator 5, the light image detection unit 6 and the glass. Light transmitted through the substrate 8 and emitted from the rear surface of the glass substrate 8 is detected.

The light absorber 55 is arranged over the entire rear surface of the glass substrate 8 so as to cover the light quantity monitor 7. Figure 2
Then, the light quantity monitor 7 is covered with the light absorber 55,
It is not always necessary to do so, and it suffices that the portion of the glass substrate 8 that is not in contact with the light quantity monitor 7 is covered with the light absorber 55. As will be described later, the light absorber 55 needs to absorb the light emitted by the phosphor (scintillator 5) as the light converter. Further, the light absorber 55 is preferably made of a black material or a material exhibiting a color complementary to the color of the light to be received by the photoelectric conversion element of the light quantity monitor unit 7 or the light emitted by the scintillator 5. Further, it is most desirable that the light amount monitor section 7 is made of a material having a light absorption characteristic that is similar or approximately equal to the light absorption characteristic. By using such a light absorber 55, it is possible to suppress the deterioration of the resolution or the MTF of the image pickup device 3 or to make the resolution or the MTF more uniform.

In disposing the light absorbing material (light absorber), for example, an adhesive having a light absorbing characteristic (for example, an adhesive containing a material having a predetermined light absorbing characteristic) is absorbed. It can be used as a body, or the function as an adhesive and the function as a light absorbing material can be separated from each other, and a light absorbing body made of a material having a predetermined light absorbing property can be bonded with an adhesive. . Examples of the light absorber used in the present invention include inorganic materials such as metal oxides and organic materials such as resins.

As a method for producing a light absorber made of an organic material, for example, there is a method of directly coloring a resin by using a dye, a method of appropriately mixing a resin with a light absorbing pigment, or the like. Generally, as a method that can be easily performed, a method of appropriately mixing a pigment with a resin to create a desired hue is suitable.

The types of pigments include, for example, organic pigments such as nitro dyes, azo pigments, indanthrenes, thioindigoperinones, perylenes, dioxazines, quinacridones, phthalocyanines, isoindolinones, and quinophthalone pigments. Inorganic pigments include carbon black, yellow lead, cadmium yellow, clover million (orange) red iron oxide, red, red cadmium, cadmium red, mineral violet (purple), cobalt blue, cobalt green, chromium oxide, and viridian (green). . By properly selecting these pigments, a light absorber having a desired hue or a black light absorber depending on the emission wavelength of the phosphor can be prepared.

Furthermore, examples of the resin used in the light absorber of the present invention include epoxy resin, acrylic resin (methacrylic resin), and silicone resin. The epoxy resin is, for example, B, which is the condensation of bisphenol A and epichlorohydrin, which is the most widely used in practice.
AE type epoxy resin can be used. With this resin as the main component, bisphenol F and a series of homologous forms thereof, halogenated resins thereof, polyalcohol, dimer acid, trimer acid,
A resin in which an epoxy group is introduced with epichlorohydrin into a novolac type phenol resin, a resin in which an epoxy group is introduced into a polyolefin with a peroxide, an epoxy resin called an alicyclic epoxy resin, or the like is used. The BAE type epoxy resin is a material that can be used with confidence because the usage and properties of the cured product for each curing agent have been well investigated and sufficient data are available.

As a method of disposing the light absorber used in the embodiment of the present invention at a predetermined position, for example, a sputtering method, a vacuum deposition method, a CVD method or the like can be used. A method of applying a light absorbing layer to the substrate is suitable.

On the other hand, examples of the method for providing the organic light absorbing layer include spinner coating, curtain coating, transfer method such as screen printing or offset printing, and coating with a dispenser.

FIG. 3 is a front view of the light amount monitor unit 7, and shows the arrangement of the light detection elements (sensor units) constituting the light amount monitor unit 7. The sensor unit of the light amount monitor unit 7 corresponds to the light-collecting field of the photo timer, and the arrangement (shape, size, position, number, etc.) of this light-collecting field varies depending on the region to be imaged of the person S to be imaged. It can be arranged in various ways. FIG. 3 shows an example suitable for chest radiography, and the light amount monitor unit 7 includes three light detection elements (sensor units) 7a, 7b,
7c. Photodetectors 7a, 7b, 7c
The size of each is, for example, 30 × 50 mm. The broken line S'represents the lung field of the subject S,
The light detecting element 7a is in the right lung field, 7b is in the left lung field, and 7c.
Are arranged at positions corresponding to the mediastinum.

When photodetecting elements are formed on both surfaces of one glass substrate by the photolithography method, the surface on which the elements are first formed becomes a base surface when the elements are formed on the other surface, but is easily scratched. This problem can be overcome by giving a sufficient margin to the film thickness, the electrode size, and the like. That is, the process design may be performed so that the function as the photodetecting element can be maintained even if some scratches are formed. Further, it is obvious that the light image detection unit 6 should be protected more from being damaged than the light amount monitor unit 7. Therefore, in the present embodiment, first, the process of forming the light quantity monitor unit 7 including the photodetection elements 7a, 7b, and 7c on the transparent glass substrate 8 is performed, and then the light image detection including the solid-state photodetection element 6a is performed. It is preferable to adopt the procedure of performing the process of forming the portion 6 on the glass substrate 8.

The outputs of these photodetection elements 7a, 7b, 7c are the detection circuit 11, the three integration circuits 12a, 12b,
12c, arithmetic circuits 13a, 13b and 13c, and a comparison circuit 14 that outputs a radiation cutoff signal in sequence.
Although these electric circuits are housed in the image pickup apparatus 3, the setting circuit 15 connected to the comparison circuit 14 is provided outside the image pickup apparatus 3.

FIG. 4 shows a sensor structure of a pin type photodiode as an example of a solid-state photodetecting element which constitutes the photoimage detecting section 6 and the light quantity monitoring section 7. Optical image detector 6
Is composed of a plurality of solid-state photo-detecting elements 6a. The solid-state photo-detecting element 6a is composed of a signal line (electrode) 21 and a signal line (electrode) 21 made of a conductive film patterned on the surface 8a of the transparent glass substrate 8 by photolithography. 22, a pin type photodiode section 25 as a photoelectric conversion section composed of amorphous silicon 23 and a transparent electrode 24, and a thin film transistor (TFT) 28 as a transfer section having a transfer electrode 27 in amorphous silicon 26. There is.

The transfer electrode 27 is a gate, which is connected to a scanning line (not shown), and the signal line 22 is a drain, which is connected to a signal line (not shown). Then, the plurality of solid-state photodetecting elements 6a thus configured are arranged in a matrix. The transfer electrode 27 and the signal line 22 may be transparent electrodes or opaque electrodes. However, when the transparent electrodes are used, a large amount of light passes through the light image detection unit 6 and the glass substrate 8 and reaches the light amount monitor unit 7. Is desirable.

In the optical image detecting section 6, the light from the scintillator 5 emitted by the irradiation of radiation is detected by the photodiode section 2
5, the signal charge of an amount corresponding to the intensity of the incident light is generated and accumulated in the photodiode portion 25. Next, a predetermined scanning signal is sent to the scanning line from a signal reading circuit (not shown) connected to the scanning line (not shown),
A voltage is applied to the transfer electrode 27 as a gate connected to the scanning line, and as a result, a current flows between the signal lines 21 and 22. That is, the signal charges generated in the photodiode section 25 are transferred through the thin film transistor 28 to
It is transferred to a transfer register (not shown) and output.

On the other hand, the photodetection elements 7a, 7b and 7c constituting the light quantity monitor section 7 are formed on the surface 8b of the glass substrate 8 opposite to the surface 8a on which the photoimage detection section 6 is arranged by the photolithography method. As a photoelectric conversion unit composed of signal lines (electrodes) 29 and 30 made of a transparent conductive film such as an ITO film patterned by the above, amorphous silicon 31, and a transparent electrode 32 (this electrode does not necessarily have to be transparent). It is composed of a pin type photodiode section 33 and a thin film transistor 36 as a transfer section having a transfer electrode 35 in an amorphous silicon 34. In addition,
The transfer electrode 35 is a gate, which is connected to a scanning line (not shown), and the signal line 30 is a drain, which is connected to a signal line (not shown).

In the light quantity monitor section 7, of the light from the scintillator 5 emitted by the irradiation of the radiation X, the light that has passed through the optical image detection section 6 and the glass substrate 8 enters the photodiode section 33, and this photo In the diode portion 33, an amount of signal charge corresponding to the intensity of incident light is generated and accumulated. Next, a predetermined scanning signal is sent from the signal reading circuit (detection circuit 11) connected to the scanning line (not shown) to the scanning line, and a voltage is applied to the transfer electrode 35 as a gate connected to the scanning line. , As a result, signal lines 29 and 3
A current flows between 0 and this. That is, the signal charge generated in the photodiode unit 33 can be detected through the thin film transistor 36.

At the time of radiography, first, the respective elements of the light image detecting section 6 and the light quantity monitoring section 7 are reset by setting the respective elements in an output state to eliminate the influence of dark current. Then
Radiation X is emitted from the radiation source 1, and the subject S is irradiated. In synchronization with the irradiation of the person S to be photographed with the radiation X, a predetermined scanning signal is sent to the scanning line from the detection circuit 11 connected to the scanning line of the thin film transistor 36 to serve as a gate connected to the scanning line. A voltage is applied to the transfer electrode 35, and as a result, a current flows between the signal lines 29 and 30.

The intensity distribution of the radiation X which has been partially absorbed by the subject S and transmitted through the subject S carries information (radiation image information) on the internal structure of the subject S. The radiation X transmitted through the person S to be photographed is incident on the radiation detector after passing through the radiation incidence unit 4 of the image pickup device 3 kept light tight. The radiation X incident on the radiation detector is converted into visible light by the scintillator 5. This visible light has radiation image information of the person S to be photographed, and is detected by the photodiode unit 25 of the light image detection unit 6. The detection signal is accumulated in each solid-state photodetecting element 6a as a charge according to the light emission intensity of the scintillator 5.

On the other hand, of the light from the scintillator 5 emitted by the irradiation of the radiation X, the light that has passed through the light image detecting portion 6 and the glass substrate 8 is incident on the photodiode portion 33 of the light amount monitoring portion 7 on the surface 8b. To do. Photodiode section 3
Since the signal line 29 in 3 is a transparent electrode, a quantity of signal charges corresponding to the intensity of incident light is generated in the photodiode section 33.

In the light quantity monitor unit 7, a predetermined scanning signal has already been sent from the detection circuit 11 connected to the scanning line to the scanning line, and a voltage is applied to the transfer electrode 35 as a gate connected to the scanning line. As a result, the signal lines 29 and 30
A current is flowing between and. Therefore, the signal charge generated in the photodiode section 33 is continuously detected by the detection circuit 11 through the thin film transistor 36, and integrated (integrated) by the integration circuits 12a, 12b, 12c, respectively. In this way, by detecting the light transmitted through the optical image detection unit 6 and the glass substrate 8 among the light emitted by the scintillator 5 by the light amount monitor unit 7, the amount of the applied radiation can be detected in almost real time. You can

The outputs of the integrating circuits 12a, 12b, 12c are weighted by the arithmetic circuits 13a, 13b, 13c, respectively, and the arithmetic outputs are optimum values preset by the setting circuit 15 in the comparison circuit 14. It is compared with the set value. As a result of this comparison, if the calculation output does not reach the set value, irradiation of the radiation X to the radiation detector is continued, and if it reaches the set value, the irradiation of the radiation X from the comparison circuit 14 is shut off. A cutoff signal to that effect is output,
As a result, for example, the radiation source 1 is based on the cutoff signal.
The control for stopping the operation of is performed, and the radiation irradiation ends.

With the above-described operation, the radiation dose for obtaining the radiation image of the subject S with high image quality can be optimally controlled in real time. After the irradiation of radiation is completed, a predetermined scanning signal is sent to the scanning line from an image information reading circuit (not shown) connected to the scanning line of the optical image detecting section 6, so that the transfer electrode 27 as a gate connected to the scanning line is formed. A voltage is applied to the signal lines, and a current flows between the signal lines 21 and 22. Therefore, the signal charge generated in each photodiode section 25 is sequentially read by the image information reading circuit through each thin film transistor 28, and as a result, the radiation image information of the subject S is obtained.

In the description of the present embodiment, the solid-state photodetector having the structure shown in FIG. 4 is shown as an example of the photodetector of the light image detector 6 and the light quantity monitor 7. The structure of the scintillator 5 is not limited to this.
Any light can be used as long as it can detect the light emitted in the above. Further, the light quantity monitor unit 7 is not limited to the solid-state photodetector formed on the rear surface of the glass substrate 8 by the photolithography method, but may be a general light detector such as a photodiode arranged behind the glass substrate 8. It may be a detection element.

In the present embodiment, a method of continuously detecting the output from the light amount monitor unit 7 has been described as the method of reading the signal from the light amount monitor unit 7 for controlling the radiation dose, but it is disclosed in Japanese Patent Laid-Open No. Similar to the one disclosed in Japanese Patent No. 72259 of 1995, a method of reading the output from the light quantity monitor unit 7 a plurality of times in a short cycle may be used. Further, in the present embodiment, the output signal from the light quantity monitor unit 7 is analog-processed, but after the output circuit detects the output signal, the A /
The digital signal obtained by D conversion may be similarly processed.

FIG. 5 shows a second embodiment of the present invention. In the first embodiment, the light quantity monitor unit 7 is formed on the rear surface of the glass substrate 8 of the optical image detection unit 6 by the photolithography method, but in the second embodiment, another glass substrate 41 is used. It is provided above.

In this case, the glass substrate 8 and the optical image detector 6
And an image information detection unit including a scintillator 5,
The radiation amount detecting unit composed of the substrate 41 and the light amount monitor unit 7 is individually prepared by using a photolithography method, and both parts are predetermined at a stage of assembly by a fixing means such as adhesion or screwing. Fixed in positional relationship. In this case, the electrode on the substrate 41 side of the light quantity monitor unit 7 does not need to be transparent, and other configurations and operations are the same as those in the first embodiment.

FIG. 6 shows a third embodiment of the present invention,
For example, it is an example applied to a radiation detector having a large detection surface of 14 inches × 17 inches. On the front surface of the substrate 42, a light amount monitor unit 7 including photodetection elements 7a, 7b and 7c as shown in FIG. 3 is formed by a photolithography method. Then, on the front surface of the substrate 42, a light absorber 55 is formed in a portion other than the light amount monitor portion 7. A light image detecting unit 6 configured by two-dimensionally arranging solid-state light detecting elements on the front surface of the glass substrate 8, specifically, for example, four glass substrates 8 of 7 × 8.5 inches.
The solid-state photo-detecting elements are formed in a matrix on the front surface of each of the above, and the photo-image detecting unit 6 configured by bonding the four glass substrates 8 via the end faces thereof is a light amount monitor unit. 7 and the light absorber 55 are attached to the front surface side of the substrate 42 by means such as adhesion. A transparent or translucent adhesive is used for this adhesion. Further, the scintillator 5 is arranged on the front surface of the optical image detector 6.

In this embodiment, a plurality of optical image detectors 6 are provided.
It is characterized in that the light amount monitor 7 and the light absorber 55 are formed on a single substrate 42 for bonding. The operations of the light quantity monitor unit 7 and the light absorber 55 are the same as those in the first embodiment, but in the present embodiment, an optical image having a large detection surface for obtaining radiation image information of the subject S. It is particularly suitable when the detector is constructed by joining a plurality of optical image detectors 6.

FIG. 7 shows a fourth embodiment of the present invention.
The difference from the first embodiment is that the rear surface 8 of the glass substrate 8 is
Not only the light amount monitor unit 7 having the photodetection elements 7a, 7b, 7c is formed on the surface b by the photolithography method, but also in a region other than the light amount monitor unit 7 on the rear surface 8b of the glass substrate 8, By the photolithography method, the film 55 that is the same as or similar to the light amount monitor unit 7 (a film that has the same or similar light absorption characteristics as the light amount monitor unit 7) 55 is formed as a light absorber, not as a photodetector. That is. As described above, the radiation image capturing apparatus according to the embodiment of the present invention configures, of the light emitted by the scintillator by the irradiation of radiation, the light that has passed through the optical image detection unit, behind the substrate of the optical image detection unit. Since the light amount monitor detects the radiation dose in real time, the radiation dose of the subject can be suppressed and an image can be taken with an appropriate radiation amount, and a high-quality radiation image can be obtained. At the same time, a light absorber having a light absorption characteristic similar to the light absorption characteristic of the light amount monitor is seamlessly arranged in a region other than the region where the light amount monitor is arranged on the back surface of the substrate of the light image detector. As a result, it is possible to avoid the deterioration or nonuniformity of the resolution or MTF of the radiation image capturing apparatus due to the nonuniformity of light reflection or light scattering behind the light image detection unit. Further, in the embodiment of the present invention, it is no longer necessary to use the chamber type phototimer which has been arranged in front of the light image detection unit (radiation image detection unit) as the light amount (radiation amount) detection unit in the past. Since the absorption of X-rays (several%) by the chamber can be reduced, the exposure dose of the subject (subject) can be reduced. In addition, structurally the amount of light (the amount of radiation)
The detection unit can be configured to be thin, and thus the radiation image capturing apparatus can be thin, lightweight, and inexpensive.

[0044]

As described above, according to the present invention, the detector for controlling the radiation is arranged efficiently or effectively, and the exposure dose of the subject (subject) can be reduced, and It is possible to provide a radiographic image capturing apparatus in which deterioration or nonuniformity of resolution or MTF is suppressed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a radiation detection apparatus of the present invention.

2 is a block diagram showing a configuration of a first embodiment of an image pickup apparatus used in the radiation detection apparatus shown in FIG.

3 is a schematic front view of a light amount monitor unit of the image pickup apparatus shown in FIG.

FIG. 4 is a diagram showing a structure of a solid-state photodetection element that constitutes the photoimage detection unit and the light amount monitor unit shown in FIG.

5 is a block diagram showing a configuration of a second embodiment of an image pickup apparatus used in the radiation detection apparatus shown in FIG.

6 is a block diagram showing a configuration of a third embodiment of an image pickup apparatus used in the radiation detection apparatus shown in FIG.

7 is a block diagram showing a configuration of a fourth embodiment of an image pickup apparatus used in the radiation detection apparatus shown in FIG.

[Explanation of symbols]

3 Imaging device 5 scintillator 6 Optical image detector 7 Light intensity monitor 55 Light absorber

[Procedure amendment]

[Submission date] December 21, 2001 (2001.12.
21)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

As the scintillator 5, GdO ₂ S: T
_{b, CaWO 4, C S I} : Tl, CaI: phosphor or the like Na, so various ones are used, such as so-called scintillation fiber doped with phosphor into the fiber plate. The light image detection unit 6 joined to the scintillator 5 is configured by forming a large number of solid-state light detection elements two-dimensionally on the front surface of a transparent glass substrate 8 by a photolithography method. Further, the light quantity monitor unit 7 is configured by forming a solid-state photodetection element on the rear surface of the glass substrate 8 by the photolithography method, and among the light generated by converting the radiation X by the scintillator 5, the light image detection unit 6 and the glass. Light transmitted through the substrate 8 and emitted from the rear surface of the glass substrate 8 is detected.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G088 EE01 FF02 GG13 GG16 GG19                       GG20 JJ03 JJ05 JJ09 JJ37                       KK06 KK18 KK24 KK32 LL08                       LL12 LL15                 4M118 AB01 AB10 BA05 CA05 CB06                       CB11                 5C024 AX12 CX37 CY48 EX11 EX22                       EX24 HX31                 5F088 AA03 AB05 BA16 BA20 BB03                       BB07 EA04 GA02 HA10 JA17                       KA06 KA10 LA07 LA08

Claims (9)

[Claims] 1. A first photodetector for detecting light from the scintillator, the scintillator for converting radiation into light, and a plurality of photodetection elements arranged in a two-dimensional manner, and the first photodetector. A second photodetector arranged on the back surface of the photodetector for detecting light from the scintillator that has passed through the first photodetector; and a second photodetector of the back surface of the first photodetector. And a light absorber arranged in a region other than the region where the photodetector is arranged. 2. The radiation image according to claim 1, wherein the light absorption characteristic of the light absorber and the light absorption characteristic of the second photodetector with respect to the light from the scintillator are substantially equal. Imaging device. 3. The radiation image capturing apparatus according to claim 1, wherein each of the first and second photodetectors is an amorphous silicon sensor. 4. A calculation means for performing at least an integral calculation on the output of the second photodetector, and an output means for outputting a signal for controlling the radiation based on the output of the calculation means. The radiographic image capturing apparatus according to claim 1, wherein 5. The first photodetector has a transparent substrate,
The second photodetector is arranged on the back surface of the transparent substrate, and the light absorber is arranged on an area other than the area where the second photodetector is arranged on the back surface of the transparent substrate. The radiographic image capturing device according to claim 1. 6. The radiation image capturing apparatus according to claim 5, wherein the transparent substrate is a common substrate for the first photodetector and the second photodetector. 7. The radiation image capturing apparatus according to claim 5, wherein the second photodetector has a substrate different from the transparent substrate. 8. The first photodetector comprises a plurality of photodetectors supported by a common substrate, and the substrate and the first photodetector.
The radiation image capturing apparatus according to claim 1, wherein the second photodetector and the light absorber are arranged between the photodetector and the photodetector. 9. The radiation image capturing apparatus according to claim 8, wherein each of the plurality of photodetectors has a transparent substrate.