JP2004179266A - Radiation picture detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive radiation picture detector with high durability and high picture quality. <P>SOLUTION: The radiation picture detector is provided with a detection element layer 210 outputting a signal corresponding to intensity of an incident radial ray in a pixel unit and a fourth layer 214 holding the detection element layer 210. The fourth layer 214 is formed by using a material with a high shielding rate with respect to oxygen and moisture. An oxygen transmission factor of the fourth layer is set to be not more than 0.1cc/(m<SP>2</SP>day atm). A moisture transmission factor is set to be not more than 0.1g/(m<SP>2</SP>day). Transmission of oxygen and moisture in the fourth layer is reduced. Even if the detection element layer 210 is formed by using an organic material, deterioration due to oxygen and moisture is reduced and durability can be improved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the industrial field of radiation imaging in medicine. In particular, the present invention relates to a high-quality and durable radiation image detector for obtaining a radiation image used for diagnostic purposes.
[0002]
[Prior art]
With the advancement of digital technology, the transition from analog technology to digital technology is also rapidly occurring in the field of radiation image detectors. In this radiation image detector, for example, computed radiography (CR) is generally used as a digital radiation image detector.
[0003]
In this computed radiography, radiation image information is temporarily recorded on a medium called an imaging plate coated with a phosphor, and then the information is read by irradiating a laser beam to the imaging plate and the image signal of the radiation image is read. Gain. In such an imaging plate, a moisture-resistant protective film is formed so that moisture does not enter and adversely affect the phosphor layer (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2002-148343
[Problems to be solved by the invention]
By the way, the computed radiography does not have the image quality of a so-called screen film system (SF system) combining a fluorescent intensifying screen and a radiographic film. In addition, since it is necessary to read recorded information by irradiating a laser beam, it is not possible to quickly see a radiation image.
[0006]
Further, a flat panel detector (FPD) that can obtain a high-quality radiation image without reading information recorded by irradiating a laser beam like a computerized radiography has been put to practical use. In this flat panel detector, a photoelectric conversion layer that converts light emission generated according to the intensity of incident radiation into electric energy is formed of an organic material. In addition, a TFT (Thin Film Transistor) for converting electric energy generated in the photoelectric conversion layer into an electric signal and outputting the electric signal is also used when an inorganic substance is used by using an organic substance instead of amorphous silicon which is an inorganic substance. Flat panel detectors can be formed at lower temperatures. For this reason, the substrate can be changed from a thick glass plate to a resin substrate, and a lightweight and strong flat panel detector can be realized.
[0007]
However, the resin substrate does not have a high ability to shield oxygen and moisture. For this reason, the photoelectric conversion layer formed of an organic substance, the TFT, and the like are deteriorated by oxygen and moisture transmitted through the resin substrate, and it becomes difficult to obtain sufficient durability.
In view of the above, the present invention provides a radiation image detector which is excellent in durability, high in quality and inexpensive.
[0008]
[Means for Solving the Problems]
A radiation image detector according to the present invention includes a first layer that emits light in accordance with the intensity of incident radiation, and a second layer that is formed of an organic compound that converts light output from the first layer into electric energy. A third layer for storing the electric energy obtained in the second layer and outputting a signal based on the stored electric energy in pixel units, and a fourth layer for holding the first to third layers. In the radiation image detector provided, the fourth layer is formed using a member having a high shielding rate against oxygen and moisture.
[0009]
In the present invention, a first layer that emits light in accordance with the intensity of incident radiation, a second layer formed of an organic compound that converts light output from the first layer into electric energy, and a second layer are provided. A radiation image detector using a third layer that stores the stored electric energy and outputs a signal based on the stored electric energy in pixel units and a fourth layer that holds the first to third layers In forming the fourth layer, the fourth layer is formed using a member having a high shielding rate against oxygen and moisture. For example, it is formed using a resin substrate having an oxygen permeability of 0.1 cc / m ² · day · atm or less, or a resin substrate having a moisture permeability of 0.1 g / m ² · day or less. Further, the fourth layer is used is member by bonding a resin substrate having the shielding film and the detecting element layer is formed, oxygen permeability 0.1cc / m 2 ^· day · atm or less, the moisture permeability 0. 1 g / m ² · day or less. Also, a member in which the fourth layer is a resin substrate and a non-resin substrate on which a detection element layer is formed which is harder and thinner than the resin substrate, or a fourth layer which is harder and thinner than the resin substrate and the resin substrate. Is used, the oxygen permeability is set to 0.1 cc / m ² · day · atm or less, and the moisture permeability is set to 0.1 g / m ² · day or less.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of a system using a radiation image detector. In FIG. 1, radiation emitted from a radiation generator 10 is applied to a radiation image detector 20 through a subject (eg, a patient in a medical facility) 15. The radiation image detector 20 generates an image signal DFE based on the intensity of the irradiated radiation. The generated image signal DFE is read by the image processing unit 51 connected to the radiation image detector 20. Alternatively, after being stored in a portable recording medium such as a semiconductor memory card mounted on the radiation image detector 20, the recording medium is removed from the radiation image detector 20 and mounted on the image processing unit 51. Are supplied to the image processing unit 51.
[0011]
The image processing unit 51 performs shading correction, gain correction, gradation correction, edge enhancement processing, dynamic range compression processing, and the like on the image signal DFE generated by the radiation image detector 20 to obtain an image suitable for diagnosis and the like. Processing is performed so as to be a signal. The image processing unit 51 is connected to an image display unit 52 configured using a cathode ray tube, a liquid crystal display device, a projector, or the like. An image based on the subsequent image signal is displayed.
[0012]
Further, the image processing section 51 enlarges or reduces the image, and also performs compression or decompression processing of the image signal in order to facilitate accumulation and transfer of the image signal. Therefore, by enlarging or reducing the image displayed on the image display unit 52, it is possible to easily confirm the imaging region and perform the processing state. Further, it is also possible to specify a displayed image or a region of the displayed image, and automatically perform appropriate image processing on the specified image or the specified region.
[0013]
Further, an information input unit 53 configured using a keyboard, a mouse, a pointer, and the like is connected to the image processing unit 51. The information input unit 53 inputs patient information and the like, and converts the additional information into an image signal. Can be added. The information input unit 53 also designates image processing, saves and reads image signals, and sends and receives image signals via a network.
[0014]
The image processing unit 51 is further connected to an image output unit 54, an image storage unit 55, and a computer-aided image automatic diagnosis unit (CAD) 56.
[0015]
The image output unit 54 displays a radiographic image on recording paper, film, or the like and outputs the radiographic image. For example, assuming that a silver halide photographic film is used, exposure is performed based on an image signal. The exposed silver halide photographic film is subjected to a development process to draw and output a radiation image as a silver image. In addition, when printing and outputting a radiation image on recording paper, an ink jet printer that applies pressure to the ink based on the image signal, wipes the ink on the recording paper from the tip of a thin nozzle, and prints, based on the image signal A thermal printer that transfers the image to recording paper by melting or sublimating the ink, scans the photoreceptor with laser light based on the image signal, transfers the toner adhering to the photoreceptor to the paper, and applies heat and pressure. The image output unit 54 is configured using a laser printer or the like that forms an image on recording paper by fixing.
[0016]
The image storage unit 55 stores the image signal of the radiation image so that the image signal can be appropriately read as needed. The image storage unit 55 stores an image signal using, for example, magnetic properties, a hologram element, perforation, a change in pigment distribution, and the like.
[0017]
The CAD 56 performs computer processing and computer analysis of the captured radiographic image, and provides information necessary for diagnosis to a doctor, thereby supporting diagnosis so that a lesion is not overlooked. Diagnosis is automatically performed based on computer processing and computer analysis results.
[0018]
The image signal of the radiation image is transmitted not only to the image output unit 54, the image storage unit 55, and the CAD 56, but also to other units in the hospital facility via a network 60 such as a so-called LAN, the Internet, and a PACS (medical image network). Alternatively, it can be sent to a remote location. In addition, the image signal obtained from the CT 61 or the MRI 62 or the image signal obtained from the CR or another FPD 63 and other inspection information can be transmitted through the network. In order to compare the obtained radiographic image with the obtained radiographic image, an image signal, inspection information, or the like transmitted via the network 60 is displayed on the image display unit 52 or output from the image output unit 54. Further, the transmitted image signal, inspection information, and the like can be stored in the image storage unit 55. In addition, an image signal or the like of a radiation image obtained by the radiation image detector 20 may be stored in the external image storage device 64, or the radiation image obtained by the radiation image detector 20 may be displayed on the screen of the external image display device 65. Displaying an image is also performed.
[0019]
Next, an example of the structure of the radiation image detector 20 is shown in FIG. The radiation image detector 20 includes an imaging panel 21, a control circuit 30 for controlling the operation of the radiation image detector 20, and an image signal output from the imaging panel 21 using a rewritable read-only memory (for example, a flash memory). , An operation unit 32 for switching the operation of the radiation image detector 20, a display unit 33 indicating completion of preparation for radiographic image capturing, and indicating that a predetermined amount of image signal has been written to the memory unit 31, A power supply unit 34 for supplying power required to drive the imaging panel 21 to obtain an image signal is provided, and a communication connector 35 for performing communication between the radiation image detector 20 and the image processing unit 51 is provided. These are housed in a portable housing 40. Further, the imaging panel 21 has a scan driving circuit 25 for reading out the stored electric energy according to the intensity of the irradiated radiation, and a signal selecting circuit 27 for outputting the stored electric energy as an image signal. Note that the inside of the housing 40, the scanning drive circuit 25, the signal selection circuit 27, the control circuit 30, the memory unit 31, and the like are covered with a radiation shielding member (not shown). And radiation of radiation to each circuit is prevented.
[0020]
In addition, it is preferable that the outer shape of the housing 40 be made of a material that can withstand an external impact and that is as light as possible so as to be easily carried, that is, aluminum or an alloy thereof. The radiation incident surface side of the housing 40 is formed using a nonmetal, such as carbon fiber, which easily transmits radiation. In addition, on the back side opposite to the radiation incident surface, it is generated for the purpose of preventing radiation from transmitting through the radiation image detector 20 or by absorbing the radiation by the material constituting the radiation image detector 20. It is a preferred embodiment to use a material that effectively absorbs radiation, such as a lead plate, in order to prevent the influence from secondary radiation.
[0021]
FIG. 3 shows the configuration of the image pickup panel 21. The image pickup panel 21 has two-dimensionally arranged collecting electrodes 220 for reading out electric energy stored in accordance with the intensity of irradiated radiation. 220 is one electrode of the capacitor 221, and electric energy is stored in the capacitor 221. Here, one collection electrode 220 corresponds to one pixel of the radiation image.
[0022]
The scanning lines 223-1 to 223-m and the signal lines 224-1 to 224-n are arranged between the pixels so as to be orthogonal to each other. A transistor 222- (1,1) formed of a silicon laminated structure or an organic semiconductor is connected to the capacitor 221- (1,1). The transistor 222- (1,1) is, for example, a field-effect transistor. The drain electrode or the source electrode is connected to the collection electrode 220- (1,1), and the gate electrode is connected to the scanning line 223-1. You. When the drain electrode is connected to the collection electrode 220- (1,1), the source electrode is connected to the signal line 224-1. When the source electrode is connected to the collection electrode 220- (1,1), the drain electrode is connected to the signal line. Connected to line 224-1. In addition, the scanning line 223 and the signal line 224 are connected to the collecting electrode 220, the capacitor 221 and the transistor 222 of other pixels in the same manner.
[0023]
FIG. 4 is a partial cross-sectional view of the imaging panel 21. The imaging panel 21 includes a first layer 211 that emits light according to the intensity of incident radiation, and an electromagnetic wave (light) output from the first layer. Is converted into electric energy, and a third layer 213 that stores the electric energy obtained by the second layer 212 and outputs a signal based on the stored electric energy is laminated, and the intensity of the incident radiation is stacked. Is formed on the fourth layer 214. The detection element layer 210 outputs a signal corresponding to the pixel signal on a pixel-by-pixel basis.
[0024]
The first layer 211 is irradiated with, for example, so-called X-rays having a wavelength of about 1Å (1 × 10 ⁻¹⁰ m) and being electromagnetic waves that pass through a human body, a ship, members of an aircraft, and the like. The X-rays are output from the radiation generator 10, and the radiation generator 10 generally uses a fixed anode or a rotating anode X-ray tube.
[0025]
The first layer 211 has a phosphor as a main component, and has an electromagnetic wave having a wavelength of 300 nm to 800 nm based on incident radiation, that is, an electromagnetic wave (light) ranging from ultraviolet light to infrared light with a focus on visible light. Is output. Note that the first layer 211 is generally called a scintillator layer.
[0026]
The phosphor used in the first layer 211 is a tungstate phosphor such as CaWO ₄ , CaWO ₄ : Pb, MgWO, Y ₂ O ₂ S: Tb, Gd ₂ O ₂ S: Tb, La ₂ O _{2 S: Tb, (Y, Gd} ) 2 O 2 S: Tb, (Y, Gd) 2 O 2 S: Tb, terbium activated rare earth oxysulfide phosphors such as _{Tm, YPO 4: Tb, GdPO} 4: Tb , Terbium-activated rare earth phosphors such as LaPO ₄ : Tb, LaOBr: Tb, LaOBr: Tb, Tm, LaOCl: Tb, LaOCl: Tb, Tm, GdOBr: Tb, GdOBr: Tb, Tm, GdOCl: Tb GdOCl: Terbium-activated rare earth oxyhalide-based phosphors such as Tb and Tm, LaOBr: Tm and thulium-activated rare earth oxy such as LaOCl: Tm Rhodium-based phosphors, gadolinium-activated rare earth oxyhalide-based phosphors such as LaOBr: Gd, LuOCl: Gd, GdOBr: Ce, GdOCl: Ce, (Gd, Y) OBr: Ce, (Gd, Y) OCl: Ce Barium sulfate-based phosphors such as cerium-activated rare earth oxyhalide-based phosphors such as BaSO ₄ : Pb, BaSO ₄ : Eu ²⁺ , (Ba, Sr) SO ₄ : Eu ²⁺ , and Ba ₃ (PO ₄ ) ₂ : Eu ²⁺ , (Ba ₂ PO ₄ ) ₂ : Eu ²⁺ , Sr ₃ (PO ₄ ) ₂ : Eu ²⁺ , (Sr ₂ PO ₄ ) ₂ : Eu ²⁺ divalent europium-activated alkaline earth metal phosphate-based phosphor ^{, BaFCl: Eu 2+, BaFBr:} Eu 2+, BaFCl: Eu 2+, Tb, BaFCl: Eu 2+, Tb, BaF 2 _{^{BaCl 2 · KCl: Eu 2+,}} (Ba, Mg) F 2 · BaCl 2 · KCl: 2 divalent europium activated alkaline earth metal fluoride halide phosphors such as ^{Eu 2+, CsI: Na, CsI} : Tl, Iodide-based phosphors such as NaI, KI: Tl, and sulfide-based phosphors such as ZnS: Ag, (Zn, Cd) S: Ag, (Zn, Cd) S: Cu, (Zn, Cd) S: Cu, Ag Phosphors, HfP ₂ O ₇ , HfP ₂ O ₇ : Cu, Hf ₃ (PO ₄ ) ₄ and other hafnium phosphate-based phosphors, YTaO ₄ , YTaO ₄ : Tm, YTaO ₄ : Nb, (Y, Sr) TaO _{4 : Nb, LuTaO 4, LuTaO 4} : Tm, LuTaO 4: Nb, (Lu, Sr) TaO 4: Nb, GdTaO 4: Tm, Mg 4 Ta 2 O 9: Nb, Gd 2 O 3 · Ta 2 ₅ · _B 2 _O 3: tantalate based phosphor such as Tb, _{^{other, Gd 2 O 2 S: Eu}} 3+, (La, Gd, Lu) 2 Si 2 O 7: Eu, ZnSiO 4: Mn, Sr ₂ P ₂ O ₇ : Eu or the like can be used.
[0027]
Further, (Gd, M1, Eu) ₂ O ₃ and (Gd, M2, Tb) ₂ O ₃ can be used. Here, “M1” is at least one or more rare earth elements of yttrium Y, niobium Nb, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, and ytterbium Yb. “M2” is at least one or more rare earth elements of yttrium Y, niobium Nb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, and ytterbium Yb. In this case, the content of Gd is preferably 70 to 98%, the crystallite size of the phosphor particles is preferably 10 to 100 nm, and the particle size of the phosphor particles is preferably 0.1 to 5 μm.
[0028]
In the above-mentioned phosphor, cesium iodide CsI: Tl, gadolinium oxysulfide Gd ₂ O ₂ S: Tb, or (Gd, Y, Eu) ₂ O ₃ , which has particularly high radiation absorption and luminous efficiency (large luminous amount), (Gd, Y, Tb) ₂ O ₃ is preferable, and by using these, a high-quality image with low noise can be obtained.
[0029]
Further, for cesium iodide CsI: Tl, a scintillator layer having a columnar crystal structure can be formed. In this case, in the columnar crystal, a light guiding effect, that is, an effect of reducing emission of light emitted in the crystal from the side surface of the columnar crystal can be obtained, so that a decrease in sharpness can be suppressed. By increasing the thickness of the phosphor layer, the radiation absorption is increased and the graininess can be improved.
[0030]
Note that the phosphor used in the present invention is not limited to these, and any phosphor that emits electromagnetic waves in a region where the light receiving element has sensitivity, such as a visible, ultraviolet, or infrared region, upon irradiation with radiation. good. The diameter of the phosphor particles used in the present invention is 7 μm or less, preferably 4 μm or less. This is because the smaller the diameter of the phosphor particles, the more the light can be scattered in the scintillator layer, and a higher sharpness can be obtained. The phosphor particles are dispersed in the following binder. For example, polyurethane, vinyl chloride copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative, styrene-butadiene copolymer, various synthetic rubber resins, phenolic resin, Epoxy resins, urea resins, melanin resins, phenoxy resins, silicone resins, acrylic resins, urea-formamide resins, and the like. Among them, it is preferable to use polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, and nitrocellulose. By using such a preferable binder, the dispersibility of the phosphor can be increased, and the filling rate of the phosphor can be increased, which contributes to the improvement of the granularity.
[0031]
The weight content of the phosphor dispersed in the binder is 90 to 99%. The thickness of the first layer used in the present invention is determined by the balance between the granularity and sharpness of the radiographic image. The thicker the first layer, the better the granularity but the worse the sharpness. When the first layer is thin, the sharpness is improved but the granularity is deteriorated. In order to obtain good granularity and sharpness, the thickness is preferably 50 μm to 300 μm.
[0032]
The second layer 212 is formed on the surface of the first layer 211 opposite to the radiation irradiation surface. The second layer 212 is provided with a diaphragm 212a, a transparent electrode film 212b, a hole conduction layer 212c, a charge generation layer 212d, an electron conduction layer 212e, and a conductive layer 212f from the first layer 211 side. Here, the charge generation layer 212d contains an organic compound capable of performing photoelectric conversion, that is, an organic compound capable of generating electrons and holes by electromagnetic waves (light). Preferably, the second layer is formed as shown in FIG.
[0033]
The diaphragm 212a is for separating the first layer 211 from other layers, and for example, Oxi-nitride or the like is used. The transparent electrode film 212b is formed using a conductive transparent material such as indium tin oxide (ITO), SnO ₂ , and ZnO. In the formation of the transparent electrode film 212b, a thin film can be formed by using a method such as evaporation or sputtering. In addition, a pattern having a desired shape may be formed by a photolithography method, or when high pattern accuracy is not required (about 100 μm or more), a mask having a desired shape is used during vapor deposition or sputtering of the electrode material. A pattern may be formed. This transparent electrode desirably has a transmittance of more than 10% and a sheet resistance of preferably several hundreds Ω / □ or less. Further, although the thickness depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 nm to 200 nm. This is because when the film thickness is small, the transparent electrode becomes an island shape, and when the film thickness is large, it takes time to form the transparent electrode.
[0034]
In the charge generation layer 212d, electrons and holes are generated by the electromagnetic wave (light) output from the first layer 211. The holes generated here are collected on the transparent electrode film 212b side, and the electrons are collected on the conductive layer 212f side. In order to improve the conversion efficiency of the charge generation layer 212d and the efficiency of carrier transfer to the electrode, a hole conduction layer 212c is formed on the charge generation layer 212d on the transparent electrode film 212b side as shown in FIG. The electron conductive layer 212e is formed on the conductive layer 212f side of the generating layer 212d. Note that, in the present structure, the hole conduction layer 212c and the electron conduction layer 212e are not necessarily essential.
[0035]
For the charge generation layer 212d, a configuration of a so-called organic EL element can be applied, and the organic EL element may be a low molecular weight type or a high molecular weight type (also referred to as a light emitting polymer). Examples of the photoelectrically convertible material used in the charge generation layer 212d of the present invention include a conductive polymer material (such as a π-conjugated polymer material and a silicon-based polymer material) and a light-emitting material used in a low-molecular organic EL device. And the like. For example, examples of the conductive polymer material include poly (2-methoxy, 5- (2′ethylhexyloxy) -p-phenylenevinylene), and poly (3-alkylthiophene). Further, compounds described on pages 190 to 203 of “Organic EL Materials and Displays (published by CMC Co., Ltd. on February 28, 2001)”, and “Organic EL Devices and Their Forefront of Industrialization ( On November 81, 1998 (published by NTT Corporation) on pages 81 to 99. Examples of the light-emitting material used in the low-molecular-weight organic EL device include, for example, “Organic EL Devices and the Forefront of Their Industrialization (NTS, November 30, 1998)”, pp. 36-56. And the compounds described on pages 148 to 172 of "Organic EL Materials and Displays (published by CMC Co., Ltd. on February 28, 2001)". . In the present invention, a particularly preferred organic compound capable of photoelectric conversion is a conductive polymer compound, and the most preferred is a π-conjugated polymer compound.
[0036]
The conductive layer 212f is made of, for example, chromium. In addition, although it is possible to select from a general metal electrode or the transparent electrode, in order to obtain good characteristics, a metal, an alloy, an electrically conductive compound having a small work function (4.5 eV or less) and a mixture thereof are used. It is preferable to use an electrode material. Specific examples of such an electrode material include sodium, sodium-potassium alloy, magnesium, lithium, aluminum, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, indium, lithium / aluminum mixtures, all rare earths, and the like. The conductive layer 212f can be formed by using such an electrode material as a raw material by a method such as vapor deposition or sputtering. Further, the sheet resistance of the conductive layer 212f is preferably several hundreds Ω / □ or less, and the film thickness is generally selected in the range of 10 nm to 1 μm, preferably 50 nm to 500 nm. This is because if the film thickness is small, the conductive layer becomes an island shape, and if the film thickness is large, it takes time to form the conductive layer.
[0037]
The third layer is formed on the surface of the second layer 212 opposite to the radiation irradiation surface. The third layer 213 includes a capacitor 221 that stores the electric energy generated by the second layer 212 for each pixel, and a transistor 222 that is a switching element for outputting the stored electric energy as a signal. . The third layer is not limited to the one using the switching element. For example, the third layer may be configured to generate and output a signal corresponding to the energy level of the stored electric energy.
[0038]
As shown in FIG. 3 and FIG. 4, a collecting electrode 220 that stores electric energy generated in the second layer 212 and is one electrode of a capacitor 221 is connected to the transistor 222 that is a switching element. . The electric energy generated in the second layer 212 is stored in the capacitor 221, and the stored electric energy is read out by driving the transistor 222. That is, by driving the switching elements, a radiation image can be generated for each pixel. Note that in FIG. 4, the transistor 222 includes a gate electrode 222a, a source electrode 222b, a drain electrode 222c, an organic semiconductor layer 222d, and an insulating layer 222e. The capacitor 221 is configured by interposing an insulating layer 222e between the collecting electrode 220 and the electrode 221a. Further, an insulating layer 222f for protecting the transistor 222 is provided.
[0039]
The compound forming the organic semiconductor layer 222d may be a single-crystal material or an amorphous material, and may be a low-molecular or high-molecular compound. Particularly preferred is a condensed aromatic represented by pentacene, triphenylene, anthracene, or the like. Examples thereof include a single crystal of a hydrocarbon compound and the π-conjugated polymer. Further, the gate electrode 222a, the source electrode 222b, and the drain electrode 222c may be any of a conductive inorganic compound and a conductive organic compound with a metal, but are preferably a conductive organic compound from the viewpoint of easiness of manufacture. Representative examples of the π-conjugated polymer compound include Lewis acids (such as iron chloride, aluminum chloride, and antimony bromide), halogens (such as iodine and bromine), sulfonates (sodium salt of polystyrenesulfonic acid (PSS), Examples thereof include those doped with potassium p-toluenesulfonate and the like, and specific examples thereof include a conductive polymer obtained by adding PSS to PEDOT.
[0040]
The fourth layer 214 holding the detection element layer 210 is formed using a member having a high shielding rate against oxygen and moisture, and has an oxygen transmission rate of 0.1 cc / m ² · day · atm or less, preferably 0.01 cc / m ^2. / M ² · day · atm, more preferably 0.001 cc / m ² · day · atm or less, and a moisture permeability of 0.1 g / m ² · day or less, preferably 0.01 g / m ² · day · atm or less. And more preferably 0.001 g / m ² · day · atm or less. For example, it is configured using a resin substrate, a shielding film, or a non-resin substrate that satisfies the above-described oxygen permeability and moisture permeability. Alternatively, a resin substrate is bonded to a shielding film or a non-resin substrate to satisfy the above-described oxygen permeability and moisture permeability.
[0041]
Here, when the fourth layer 214 is formed using the resin substrate 214a having a high shielding factor against oxygen and moisture, the resin substrate 214a is disclosed in JP-A-2002-55246, “Heat-resistant plastic optical fiber unit”. As described above, an ethylene / vinyl alcohol copolymer having excellent oxygen blocking ability is used. The ethylene / vinyl alcohol copolymer preferably has an ethylene copolymerization ratio of 20 to 47 mol%, more preferably 25 to 32 mol%. In the copolymer, the lower the ethylene ratio is, the higher the oxygen shielding ability is, but the melting point is high, and problems in processability such as thermal decomposition during molding are likely to occur.
[0042]
As the fourth layer 214, as shown in FIG. 5A, a resin substrate 214b on which a shielding film 214c is formed can be used. In this case, as the resin substrate 214b, a plastic film such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polyimide Examples include films made of carbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), and the like. As described above, by using a plastic film, the weight can be reduced as compared with the case where a glass substrate is used, and the resistance to impact can be improved.
[0043]
Further, a plasticizer such as trioctyl phosphate or dibutyl phthalate may be added to these plastic films, or a known ultraviolet absorber such as benzotriazole or benzophenone may be added. In addition, a resin prepared by applying a so-called organic-inorganic polymer hybrid method, in which a raw material of an inorganic polymer such as tetraethoxysilane is added, and a high molecular weight is obtained by applying energy such as a chemical catalyst, heat, and light. It can also be used as a raw material. Note that, as the resin substrate 214b, a resin substrate 214a having a high shielding rate against the above-described oxygen and moisture may be used.
[0044]
As the shielding film 214c, for example, a thin film layer of magnesium oxide is used as disclosed in JP-A-63-257630 “Transparent plastic film having excellent gas barrier properties”. This thin film layer of magnesium oxide can be formed using magnesium oxide by any one of a vacuum deposition method, a sputtering method, and an ion plating method.
[0045]
Also, a plasma polymerized film and polyparaxylene described in JP-A-5-101886, "Protection of an electroluminescent element", and JP-A-8-222368, "Organic electroluminescent element, method for producing the same, and apparatus for producing the same" Can be used as the shielding film 214c.
[0046]
For the plasma polymerized film, any conventionally known monomer gas can be used. For example, in addition to hydrocarbon monomers such as methane, ethane, propane, butane, pentane, ethylene, propylene, butene, butadiene, acetylene, and methylacetylene, silicon monomers such as tetramethoxysilane, and hydrogen fluoride monomers such as tetrafluoroethylene And methyl methacrylate.
[0047]
Polyparaxylylene, particularly a p-xylylene polymerized film or a chlorinated p-xylylene polymerized film is preferable because it has extremely low gas and water vapor permeability, can suppress contamination of impurities, and can form a uniform film with few pinholes. . However, this material has extremely low adhesiveness as it is, so it is preferable to use it together with a plasma treatment and / or a plasma polymerized film. Such xylene resins include Parylene N (poly p-xylylene), Parylene C (polymonochloro p-xylylene), Parylene D (polydichloro p-xylylene), etc., from Union Carbide, USA, but have low gas permeability. Therefore, parylene C is particularly preferable. A film of poly-p-xylylene or the like can be obtained by thermally decomposing a dimer gas under reduced pressure.
[0048]
The polyurea protective film is formed by heating and evaporating the raw material monomers Y and Z of the polyurea film (the raw material Y is a diamine monomer and the raw material monomer Z is a diisocyanate monomer) to a predetermined temperature with an infrared heater in a vacuum. A polyurea film is formed thereon. Since this polyurea film is a low molecular weight oligomer film, it is cross-linked by irradiating ultraviolet rays and polymerized to form a polyurea protective film.
[0049]
Further, a gas barrier film described in Japanese Patent Application Laid-Open No. 8-281861 “Gas barrier film” may be used as the shielding film 214c. This gas barrier film has a silicon oxide layer formed by a plasma chemical vapor deposition method using at least an organic silicon compound and oxygen as raw materials, and a silicon oxide layer obtained by applying a liquid containing at least polysilazane and then performing a heat treatment. Are laminated.
[0050]
Further, an organic gas barrier layer described in JP-A-2001-343633, “Liquid Crystal Cell Substrate, Manufacturing Method Thereof, and Liquid Crystal Display Device” can be used as the shielding film 214c. This organic gas barrier layer is formed using a material having a low oxygen permeability such as polyvinyl alcohol and a partially saponified product thereof, a vinyl alcohol-based polymer such as an ethylene-vinyl alcohol copolymer, and polyacrylonitrile and polyvinylidene chloride. Vinyl alcohol-based polymers are particularly preferred from the viewpoint of high gas barrier properties. The organic gas barrier layer can be formed by spreading a polymer solution used for the organic gas barrier layer on a resin substrate by a suitable coating method such as a casting method or a spin coating method, and thermally curing the polymer solution.
[0051]
Further, as disclosed in JP-A-2002-117977, “Organic electroluminescent device and its manufacturing apparatus”, an organic protective film containing a polymer of a heterocyclic compound, or an organic protective film and an inorganic protective film are laminated. The protected film thus formed can be used as the shielding film 214c.
[0052]
The organic protective film is a polymer film formed using one kind of a five-membered ring compound such as furan, pyrrole or thiophene as a material, or a copolymer film formed using plural kinds of materials, such as plasma polymerization, electrolytic polymerization, and thermal polymerization. Can be formed by
[0053]
When an organic protective film and an inorganic protective film are stacked, a silicon nitride film, a silicon oxide film, a silicon oxynitride film, a DLC film (diamond-like carbon film), an amorphous carbon film, an aluminum oxide film, and an amorphous silicon film are used as the inorganic protective film. A film or the like is used. This inorganic protective film can be formed by using a CVD apparatus, a vacuum evaporation apparatus, a sputtering apparatus, an ALE apparatus, or the like in addition to the plasma CVD apparatus.
[0054]
In addition, as described in JP-A-2002-190384, “Electroluminescent device”, a resin material is applied to the resin substrate 214b, a metal oxide is deposited by vapor deposition, sputtering, or the like, or is easily thermally decomposed. The shielding film 214c may be provided by stacking a metal oxide by applying an organic metal material and then heating it. Here, as a resin material used for the purpose of lowering the oxygen permeability, polyvinyl alcohol, Saran, and the like can be given. Examples of the metal oxide used for the same purpose include silicon dioxide, aluminum nitride, silicon nitride, and aluminum oxide. An organic metal material used for the same purpose includes a metal alcoholate. _ Further, the fourth layer 214 can be formed by alternately stacking the resin substrates 214b and the shielding films 214c. For example, as shown in JP-B-59-47996, “Multilayer laminated film”, a layer composed of an ethylene-vinyl acetate copolymer ken compound and a layer composed of polyamide are alternately laminated to form a multilayer. A support can also be formed.
[0055]
It is needless to say that a substrate may be formed of the material used for the above-described shielding film 214c, and this substrate may be used as the resin substrate 214a.
[0056]
In the fourth layer 214 configured as described above, the thickness of the resin substrate 214a and the thickness of the shielding film 214c are adjusted so as to satisfy the above-described oxygen transmittance and moisture transmittance.
[0057]
By the way, in FIG. 5A, by providing the shielding film 214c on the surface of the resin substrate 214b on the side opposite to the detection element layer 210 side, it is possible to prevent moisture and the like from entering the detection element layer 210 side via the resin substrate 214a. To prevent this, the shielding film 214c may be provided so as to be interposed between the detection element layer 210 and the resin substrate 214b. In this case, it is possible to prevent moisture or the like contained in the resin substrate 214b from entering the detection element layer 210 side.
[0058]
As shown in FIG. 5B, the fourth layer 214 may use a non-resin substrate 214d, which is harder and thinner than the resin substrate, instead of the shielding film 214c. As the non-resin substrate 214d, a glass plate having a low oxygen permeability or a low moisture permeability, a substrate or a film made of a metal such as aluminum or an oxide thereof, a ceramic, or the like is used. As described above, the oxygen permeability and the moisture permeability of the fourth layer 214 are reduced by using the non-resin substrate 214d. Note that if a material that allows easier formation of the detection element layer 210 than the resin substrate 214b is used as the non-resin substrate 214d, a radiation image detector can be easily manufactured.
[0059]
Further, the fourth layer 214 may be formed so as to sandwich the resin substrate 214b between the shielding film 214c and the non-resin substrate 214d as shown in FIG. 5C. With this configuration, it is possible to prevent moisture and the like from entering the detection element layer 210 side via the resin substrate 214a, and to detect moisture and the like even if the resin substrate 214b contains the moisture and the like in advance. It can be prevented from entering the element layer 210 side. Note that, as shown in FIG. 5C, if the detection element layer 210 is formed on the non-resin substrate 214d side, as described above, a material in which the detection element layer 210 is easier to form than the resin substrate 214b is used as the non-resin substrate 214d. Thereby, a radiation image detector can be easily manufactured. Although not shown, a shielding film 214c may be provided on both sides of the resin substrate 214b, or a non-resin substrate 214d may be provided on both sides of the resin substrate 214b so that the oxygen permeability and the moisture permeability of the fourth layer 214 can be reduced. It may be low.
[0060]
When the imaging panel 21 configured as described above is used, the power supply unit 34 such as a manganese battery, a nickel-cadmium battery, a mercury battery, a lead battery, or the like is provided on the surface of the fourth layer 214 opposite to the surface on the detection element layer side. A primary battery and a rechargeable secondary battery may be provided. As a form of this battery, a flat form is preferable so that the radiation image detector can be made thin.
[0061]
In the imaging panel 21, for example, transistors 232-1 to 232-n for initialization to which drain electrodes are connected are provided on the signal lines 224-1 to 224-n. The source electrodes of the transistors 232-1 to 232-n are grounded. The gate electrode is connected to the reset line 231.
[0062]
The scanning lines 223-1 to 223-m and the reset line 231 of the imaging panel 21 are connected to the scanning drive circuit 25 as shown in FIG. When the read signal RS is supplied from the scan drive circuit 25 to one of the scan lines 223-1 to 223-m (p is any value of 1 to m), the scan line 223 The transistors 222- (p, 1) to 222- (p, n) connected to -p are turned on, and the electricity stored in the capacitors 221- (p, 1) to 221- (p, n) is turned on. Energy is read out to the signal lines 224-1 to 224-n, respectively. The signal lines 224-1 to 224-n are connected to the signal converters 271-1 to 271-n of the signal selection circuit 27, and the signal lines 224-1 to 224 are connected to the signal converters 271-1 to 271-n. -N to generate voltage signals SV-1 to SV-n proportional to the amount of electric energy read. The voltage signals SV-1 to SV-n output from the signal converters 271-1 to 271-n are supplied to the register 272.
[0063]
In the register 272, the supplied voltage signals are sequentially selected and converted into digital image signals for one scanning line (for example, 12 bits to 14 bits) by the A / D converter 273. A readout signal RS is supplied to each of the lines 223-1 to 223-m via the scanning drive circuit 25 to perform image scanning, capture a digital image signal for each scanning line, and generate an image signal of a radiation image. . This image signal is supplied to the control circuit 30. Note that the reset signal RT is supplied from the scan driving circuit 25 to the reset line 231 to turn on the transistors 232-1 to 232-n, and the read signal RS is supplied to the scan lines 223-1 to 223-m. When the transistors 222- (1,1) to 222- (m, n) are turned on, the electric energy stored in the capacitors 221- (1,1) to 221- (m, n) is stored in the transistors 232-1 to 232-1. Release through 232-n can initialize the imaging panel 21.
[0064]
The control circuit 30 is connected to a memory unit 31 and an operation unit 32, and controls the operation of the radiation image detector 20 based on an operation signal PS from the operation unit 32. The operation unit 32 is provided with a plurality of switches, and performs initialization of the imaging panel 21 and generation of an image signal of a radiation image based on an operation signal PS corresponding to a switch operation from the operation unit 32. The generation of the image signal of the radiation image may be performed when a radiation irradiation end signal is supplied from the radiation generator 10 via the connector 35. Further, processing for storing the generated image signal in the memory unit 31 is performed.
[0065]
If the memory unit 31 to which the image signal is written is configured to be detachable from the radiation image detector 20, it is possible to easily obtain the radiation image without carrying the radiation image detector 20 after capturing the radiation image. it can. That is, if the memory unit 31 is detached from the radiation image detector 20 and attached to the image processing unit 51 after capturing the radiation image, the image signal of the radiation image can be easily supplied to the image processing unit 51. The radiation image can be displayed on the image display unit 52 or the radiation image can be output from the image output unit 54 without carrying the detector 20.
[0066]
As described above, in the above-described embodiment, since the fourth layer is formed using a member having a high shielding rate against oxygen and moisture, when the flat panel detector is formed using the resin substrate, sufficient oxygen and moisture can be obtained. Can be shielded. For this reason, sufficient durability can be obtained without causing deterioration of the photoelectric conversion layer, the TFT, and the like formed of an organic substance due to oxygen or moisture transmitted through the resin substrate.
[0067]
【The invention's effect】
In the present invention, a first layer that emits light in accordance with the intensity of incident radiation, a second layer formed of an organic compound that converts light output from the first layer into electric energy, and a second layer are provided. In a radiation image detector including a third layer for storing the stored electric energy and outputting a signal based on the stored electric energy in pixel units, and a fourth layer for holding the first to third layers, The four layers are formed using members having a high shielding rate against oxygen and moisture. Therefore, the amount of oxygen and moisture passing through the fourth layer can be reduced, so that deterioration due to oxygen and moisture can be prevented, and a radiation image detector that has good durability, high image quality, and low cost can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a system using a radiation image detector.
FIG. 2 is a diagram illustrating an example of the structure of a radiation image detector.
FIG. 3 is a diagram showing a circuit configuration of a radiation image detector.
FIG. 4 is a partial cross-sectional view of the imaging panel.
FIG. 5 is a diagram showing another configuration of the fourth layer.
[Explanation of symbols]
Reference Signs List 10 radiation generator 20 radiation image detector 21 imaging panel 25 scanning drive circuit 27 signal selection circuit 30 control circuit 31 memory unit 32 operation unit 33 display unit 34 power supply unit 35 connector 40 housing 51 image processing unit 52 image display unit 53 information Input unit 54 Image output unit 55 Image storage unit 210 Detection element layer 211 First layer 212 Second layer 212b Transparent electrode film 212d Charge generation layer 212f Conductive layer 213 Third layer 214 Fourth layer 214a Resin substrate 214b Resin substrate 214c Shielding film 214d Non-resin substrate 220 Collection electrode 221 Capacitor 222, 232 Transistor 223 Scan line 224 Signal line 231 Reset line 271 Signal converter 272 Register 273 A / D converter

Claims (25)

A first layer that emits light in accordance with the intensity of the incident radiation;
A second layer formed of an organic compound that converts light output from the first layer into electric energy;
A third layer for storing the electric energy obtained in the second layer and outputting a signal based on the stored electric energy for each pixel;
A radiation image detector including a fourth layer holding the first to third layers,
The said 4th layer was formed using the member with a high shielding rate with respect to oxygen and moisture, The radiographic image detector characterized by the above-mentioned. The radiation image detector according to claim 1, wherein the fourth layer is formed using a resin substrate having an oxygen permeability of 0.1 cc / m ² · day · atm or less. The radiation image detector according to claim 1, wherein the fourth layer is formed using a resin substrate having a moisture permeability of 0.1 g / m ² · day or less. The radiation image detector according to claim 1, wherein the fourth layer uses a member in which the resin substrate and a shielding film are bonded. 5. The radiation image detector according to claim 4, wherein the oxygen permeability of the shielding film is 0.1 cc / m ² · day · atm or less. Radiation image detector according to claim 4, wherein the moisture permeability of the shielding film is not more than 0.1g / m 2 · ^day. 5. The radiation image detector according to claim 4, wherein the member formed by laminating the resin substrate and the shielding film has an oxygen permeability of 0.1 cc / m ² · day · atm or less. Radiation image detector according to claim 4, wherein the moisture permeability of the member by bonding the resin substrate and the shielding film is equal to or less than 0.1g / m 2 · ^day. The radiation image detector according to claim 1, wherein the fourth layer uses a member in which a resin substrate and a non-resin substrate that is harder and thinner than the resin substrate are bonded. The radiation image detector according to claim 9, wherein the non-resin substrate has an oxygen transmission rate of 0.1 cc / m ² · day · atm or less. The radiation image detector according to claim 9, wherein the non-resin substrate has a moisture permeability of 0.1 g / m ² · day or less. 10. The radiation image detector according to claim 9, wherein an oxygen permeability of the member in which the resin substrate and the non-resin substrate are bonded is 0.1 cc / m ² · day · atm or less. Radiation image detector of claim 9, wherein the moisture permeability of the member by bonding the resin substrate and the non-resinous substrate is not more than 0.1g / m 2 · ^day. The radiation image detector according to claim 1, wherein the fourth layer uses a member in which a resin substrate, a shielding film, and a non-resin substrate that is harder and thinner than the resin substrate are bonded. 15. The radiation image detector according to claim 14, wherein the oxygen permeability of the shielding film is 0.1 cc / m ² · day · atm or less. Radiation image detector according to claim 14, wherein the moisture permeability of the shielding film is not more than 0.1g / m 2 · ^day. 15. The radiation image detector according to claim 14, wherein an oxygen transmission rate of a member in which the resin substrate, the shielding film, and the non-resin substrate are bonded is 0.1 cc / m ² · day · atm or less. The radiation image detector according to claim 14, wherein a moisture permeability of a member in which the resin substrate, the shielding film, and the non-resin substrate are bonded is 0.1 g / m ² · day or less. The first _{layer, CsI: Tl, Gd 2 O} 2 S: Tb, (Gd, M1, Eu) 2 O 3, formed using any of _{(Gd, M2, Tb) 2} O 3 ( Note, “M1” is at least one or more rare earth elements of Y, Nb, Tb, Dy, Ho, Er, Tm and Yb, and “M2” is at least one or more of Y, Nb, Dy, Ho, Er, Tm and Yb. Rare earth element)
The radiation image detector according to any one of claims 1 to 18, wherein: 20. The radiation image detector according to claim 1, wherein the third layer is formed of an organic semiconductor. 20. The radiation image detector according to claim 1, wherein the third layer is formed using a divided silicon laminated structure element. 22. The radiation image detector according to claim 1, wherein the radiation image detector is housed in a portable housing. 23. The radiation image detector according to claim 22, further comprising a power supply unit that supplies electric power required to drive the radiation image detector. 23. The radiation image detector according to claim 22, further comprising storage means for storing the image signal. The radiation image detector according to claim 24, wherein the storage unit is detachable.

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