WO2013137138A1 - 放射線画像検出装置及び放射線画像撮影システム - Google Patents

放射線画像検出装置及び放射線画像撮影システム Download PDF

Info

Publication number
WO2013137138A1
WO2013137138A1 PCT/JP2013/056447 JP2013056447W WO2013137138A1 WO 2013137138 A1 WO2013137138 A1 WO 2013137138A1 JP 2013056447 W JP2013056447 W JP 2013056447W WO 2013137138 A1 WO2013137138 A1 WO 2013137138A1
Authority
WO
WIPO (PCT)
Prior art keywords
wavelength conversion
conversion layer
phosphor
phosphor particles
radiation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2013/056447
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
中津川　晴康
白水　豪
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujifilm Corp
Original Assignee
Fujifilm Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujifilm Corp filed Critical Fujifilm Corp
Priority to CN201380006771.5A priority Critical patent/CN104081224B/zh
Publication of WO2013137138A1 publication Critical patent/WO2013137138A1/ja
Priority to US14/335,260 priority patent/US9052401B2/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/2012—Measuring radiation intensity with scintillation detectors using stimulable phosphors, e.g. stimulable phosphor sheets
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
    • A61B6/4208—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector
    • A61B6/4216—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector using storage phosphor screens
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7767—Chalcogenides
    • C09K11/7769—Oxides
    • C09K11/7771—Oxysulfides
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/2008—Measuring radiation intensity with scintillation detectors using a combination of different types of scintillation detectors, e.g. phoswich
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/2018—Scintillation-photodiode combinations
    • G01T1/20186—Position of the photodiode with respect to the incoming radiation, e.g. in the front of, below or sideways the scintillator
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/2018—Scintillation-photodiode combinations
    • G01T1/20187—Position of the scintillator with respect to the photodiode, e.g. photodiode surrounding the crystal, the crystal surrounding the photodiode, shape or size of the scintillator
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens

Definitions

  • the present invention relates to an indirect conversion type radiographic image detection apparatus and a radiographic imaging system having the radiographic image detection apparatus.
  • Radiation image detection devices include a direct conversion system that converts radiation directly into electric charges and an indirect conversion system that converts radiation once into light (visible light) and converts this light into electric charges.
  • the indirect conversion type radiological image detection apparatus includes a wavelength conversion layer that converts radiation into light, and a solid state detector that converts light generated by the wavelength conversion layer into electric charges. This solid state detector has a plurality of photodiodes.
  • a wavelength conversion layer and a solid state detector are laminated, and it is classified into two types depending on which is arranged on the radiation source side.
  • a method in which the wavelength conversion layer is on the radiation source side is called a PSS (Penetration Side Sampling) method.
  • a method in which the solid state detector is used as the radiation source side is called an ISS (Irradiation Side Sampling) method (refer to JP 2010-1212733 A).
  • the wavelength conversion layer In the wavelength conversion layer, light emission occurs according to the incidence of radiation, but the light emission mainly occurs in the surface layer on the side where the radiation is incident. Therefore, in the PSS system, light emission occurs on the surface layer opposite to the solid state detector of the wavelength conversion layer, and this light propagates in the wavelength conversion layer toward the solid state detector. For this reason, part of the light is absorbed or scattered by the wavelength conversion layer itself, and the sensitivity (conversion efficiency from radiation to light) and the sharpness of the image detected by the solid state detector are reduced. There's a problem.
  • the radiation transmitted through the solid-state detector is incident on the wavelength conversion layer, so that light emission in the wavelength conversion layer occurs on the solid-state detector side.
  • the wavelength conversion layer may be thickened.
  • the phosphor particles emit light at a position far from the solid state detector, and the light from these phosphor particles spreads greatly as it propagates toward the solid state detector.
  • the sharpness of the image is reduced.
  • the sensitivity of the wavelength conversion layer is improved by increasing the size of the phosphor particles and increasing the light emission amount of the phosphor particles. In this case, the sensitivity is propagated from the phosphor particles toward the solid state detector. Light spreads further and sharpness is further reduced.
  • Japanese Patent Application Laid-Open No. 2010-112733 discloses a first phosphor layer in which phosphor particles having a small average particle diameter are dispersed in a binder, and a second phosphor in which phosphor particles having a large average particle diameter are dispersed in a binder. It has been proposed to form a wavelength conversion layer by laminating layers and to arrange the second phosphor layer on the solid state detector side. In the second phosphor layer, the size of the phosphor particles is large and the amount of emitted light is large, but since the position of each phosphor particle is close to the solid state detector, the spread of light is small and the sharpness is not lowered.
  • the position of each phosphor particle is far from the solid state detector, but since the size of the phosphor particle is small, the spread of light is small and the sharpness is not lowered. Therefore, in the radiographic image detection apparatus described in Patent Document 1, the sensitivity can be improved without reducing the sharpness.
  • the wavelength conversion layer has a two-layer structure including a first phosphor layer and a second phosphor layer, thereby improving sensitivity and sharpness.
  • this increases the manufacturing cost. For this reason, it is desired to improve sensitivity and sharpness with a single wavelength conversion layer.
  • An object of the present invention is to provide an indirect conversion type radiological image detection apparatus capable of improving sensitivity and sharpness while suppressing manufacturing cost, and a radiographic imaging system having the radiographic image detection apparatus.
  • a radiological image detection apparatus includes a wavelength conversion layer that converts radiation into light, and a solid state detector that detects light and generates image data.
  • a solid state detector and a wavelength conversion layer are arranged in this order from the side on which radiation is incident from the radiation source during imaging.
  • the wavelength conversion layer includes at least a first phosphor particle having a first average particle diameter and a second phosphor particle having a second average particle diameter smaller than the first average particle diameter in a binder. It is a mixed single-layer phosphor layer. The weight of the first phosphor particles per unit thickness of the wavelength conversion layer gradually decreases in the direction away from the solid state detector.
  • the weight of the second phosphor particles per unit thickness of the wavelength conversion layer is preferably larger on the solid detector side than on the opposite side of the solid detector.
  • the weight of the second phosphor particles per unit thickness of the wavelength conversion layer gradually increases in the direction away from the solid state detector.
  • the wavelength conversion layer is formed by applying a phosphor coating solution in which the first and second phosphor particles are dispersed in a binder solution, drying the coating solution on the temporary support, and peeling it from the temporary support. It is preferable.
  • the surface on the temporary support side is disposed on the solid detector side.
  • a light reflection layer is provided on the opposite side of the wavelength conversion layer from the solid state detector.
  • the wavelength conversion layer preferably has a convex portion on the surface on the light reflection layer side.
  • the solid state detector and the wavelength conversion layer are bonded via a bonding agent layer or are in direct contact and pressed.
  • a support is provided on the opposite side of the light reflection layer from the solid state detector, and it is preferable that the wavelength conversion layer and the support are bonded together by heat compression through the light reflection layer.
  • the weight ratio of the first phosphor particles to the second phosphor particles is preferably 20% to 40%.
  • the first average particle size is preferably 5 ⁇ m or more and 12 ⁇ m or less, and the second average particle size is preferably 1 ⁇ m or more and less than 5 ⁇ m.
  • the space filling factor of the phosphor particles in the wavelength conversion layer is preferably 68% or more.
  • the phosphor particles are formed of A 2 O 2 S: X (where A is any one of Y, La, Gd, and Lu, and X is any one of Eu, Tb, and Pr). It is preferable that
  • an edge pasting member that covers the side surface of the periphery of the wavelength conversion layer.
  • the radiographic imaging system of the present invention includes a radiation source and a radiographic image detection device.
  • the radiation source emits radiation.
  • the radiation image detection apparatus includes a wavelength conversion layer that converts radiation into light, and a solid state detector that detects light and generates image data.
  • the solid state detector and the wavelength conversion layer are sequentially arranged from the side on which radiation is incident. Arranged in order.
  • the wavelength conversion layer includes at least a first phosphor particle having a first average particle diameter and a second phosphor particle having a second average particle diameter smaller than the first average particle diameter in a binder. It is a mixed single-layer phosphor layer.
  • the weight of the first phosphor particles per unit thickness of the wavelength conversion layer gradually decreases in the direction away from the solid state detector.
  • the wavelength conversion layer includes at least a first phosphor particle having a first average particle diameter and a second phosphor having a second average particle diameter smaller than the first average particle diameter.
  • a single-layer phosphor layer in which particles are mixed in a binder, and the weight of the first phosphor particles per unit thickness of the wavelength conversion layer gradually decreases in the direction away from the solid state detector. Therefore, sensitivity and sharpness are improved.
  • the radiographic imaging system 10 includes a radiation source 11, a radiographic image detection device 12, a signal processing device 13, and a display device 14.
  • the radiation source 11 emits radiation (for example, X-rays) XR toward the subject 15.
  • the radiation image detection device 12 detects the radiation XR transmitted through the subject 15, detects the radiation image of the subject 15 carried on the radiation XR, generates image data, and outputs it.
  • the signal processing device 13 performs predetermined signal processing on the image data output from the radiation image detection device 12.
  • the display device 14 displays a radiation image based on the image data subjected to signal processing by the signal processing device 13.
  • the radiological image detection apparatus 12 includes a solid state detector 20, a wavelength conversion layer 21, a support 22, an edge pasting member 23, and a protective layer 24.
  • the solid state detector 20, the wavelength conversion layer 21, the support 22 and the protective layer 24 are laminated in this order from the radiation source 11 side.
  • the radiation XR emitted from the radiation source 11 and transmitted through the subject 15 passes through the solid detector 20 and enters the wavelength conversion layer 21.
  • a radiation shielding plate (not shown) such as a lead plate is provided on the opposite side of the protective layer 24 from the radiation incident side.
  • the wavelength conversion layer 21 is a single-layer phosphor layer (scintillator) that converts the radiation XR incident upon photographing into light (visible light).
  • the solid state detector 20 detects the light converted by the wavelength conversion layer 21 and generates image data representing a radiation image.
  • the edge pasting member 23 covers the peripheral side surfaces of the wavelength conversion layer 21 and the support 22.
  • the protective layer 24 covers the surface of the support 22 opposite to the wavelength conversion layer 21.
  • the radiological image detection device 12 is often used in the form of an electronic cassette that is detachably attached to the imaging table.
  • the radiation image detection device 12 is housed in a housing (not shown).
  • An image memory and a battery (both not shown) are also accommodated in the housing.
  • An alignment mark (not shown) is provided on the incident surface on the radiation incident side of the housing in order to align the radiation source 11 and the subject 15.
  • the solid state detector 20 includes a plurality of pixels 30, a plurality of scanning lines 31, a plurality of data lines 32, a gate driver 33, a plurality of integrating amplifiers 34, a multiplexer 35, and an A / D converter 36.
  • the pixel 30 includes a photodiode 30a and a TFT switch 30b, and is two-dimensionally arranged in the XY directions.
  • the scanning line 31 is provided for each row of the pixels 30 arranged in the X direction.
  • the scanning line 31 is supplied with a scanning signal for driving the TFT switch 30b.
  • the data line 32 is provided for each column of pixels 30 arranged in the Y direction. The signal charges accumulated in the photodiode 30a and read out through the TFT switch 30b flow through the data line 32.
  • the photodiode 30a generates and accumulates signal charges according to the light generated by the wavelength conversion layer 21.
  • the TFT switch 30b is provided corresponding to each intersection of the scanning line 31 and the data line 32, and is connected to the photodiode 30a.
  • the gate driver 33 is connected to one end of each scanning line 31 and sequentially applies scanning signals to the scanning lines 31.
  • the integrating amplifier 34 is connected to one end of each data line 32, integrates the signal charge flowing through each data line 32, and outputs a voltage corresponding to the accumulated charge amount.
  • the multiplexer 35 is provided on the output side of each integrating amplifier 34 and selectively inputs the voltage output by the integrating amplifier 34 to the A / D converter 36.
  • the A / D converter 36 converts the voltage input from the integrating amplifier 34 via the multiplexer 35 into a digital signal.
  • a voltage amplifier or the like is provided between the integrating amplifier 34 and the A / D converter 36.
  • the above-described image data is constituted by digital signals for all the pixels output from the A / D converter 36.
  • the wavelength conversion layer 21 has a first surface 21 a bonded to the solid state detector 20 via a bonding agent layer 25, and a second surface 21 b bonded to the support 22.
  • the bonding agent layer 25 is made of an acrylic material.
  • the support 22 is obtained by laminating a resin film 22a, a conductive layer 22b, and a light reflecting layer 22c in this order.
  • the second surface 21b of the wavelength conversion layer 21 is bonded to the light reflection layer 22c.
  • the lower surface of the support 22 is covered with a protective layer 24.
  • the edge pasting member 23 is made of resin or the like.
  • the thickness of the edge pasting member 23 is desirably 5 ⁇ m or more and 500 ⁇ m or less.
  • the edge pasting member 23 is a cured film made of, for example, a silicone polymer and polyisocyanate.
  • silicone-based polymer these are alternately formed by condensation reaction or polyaddition reaction of a component having a polysiloxane unit (polymer, prepolymer, or monomer) and another component (polymer, prepolymer, or monomer), A polymer attached to the block or pendant is used.
  • a component having a polysiloxane unit polymer, prepolymer, or monomer
  • a polymer attached to the block or pendant is used.
  • examples thereof include polyurethane having a polysiloxane unit, polyurea having a polysiloxane unit, polyester having a polysiloxane unit, and an acrylic resin having a polysiloxane unit.
  • Polyisocyanates include various polyisocyanate monomers, polyols such as TMP (trimethylolpropane) and isocyanates such as TDI (tolylene diisocyanate) or adducts of polyisocyanates, dimers of TDI or trimers of TDI.
  • a polymer such as a polymer of HMDI (hexamethylene diisocyanate), a compound such as a polyisocyanate and a polyfunctional hydroxyl or amine compound, or an isocyanato prepolymer obtained by reaction of a polyisocyanate and a hydroxy polyether or polyester is used.
  • the mixing ratio of the silicone polymer to the polyisocyanate is generally 99: 1 to 10:90 (polymer: polyisocyanate) by weight, preferably 95: 5 to 20:80, and more preferably 90:10 to 70:30 is preferred.
  • the material of the resin film 22a of the support polyethylene terephthalate (PET), cellulose acetate, polyester, polyamide, polyimide, triacetate, polycarbonate, or the like is used.
  • the thickness of the resin film 22a is preferably 20 ⁇ m or more and 2 mm or less, and more preferably 70 ⁇ m or more and 0.5 mm or less.
  • the conductive layer 22b is obtained by dispersing a conductive agent such as SnO 2 in a resin such as polyester.
  • the light reflecting layer 22c is obtained by dispersing a light reflecting material such as alumina fine particles in a resin such as acrylic.
  • a super barrier film (SBF: trade name) manufactured by FUJIFILM Corporation is used as the protective layer 24.
  • the edge pasting member 23 may contain conductivity.
  • the polymer is mixed with conductive fine particles such as SnO 2 : Sb and ZnO, and carbon clusters such as carbon black, fullerene, and carbon nanotube.
  • the sheet resistance of the edge pasting member 23 is desirably 10 8 ⁇ or less.
  • the wavelength conversion layer 21 is formed by dispersing phosphor particles 40 such as GOS (Gd 2 O 2 S: Tb) in a binder 41 such as a resin.
  • phosphor particles 40 such as GOS (Gd 2 O 2 S: Tb)
  • a binder 41 such as a resin.
  • the phosphor particles 40 have an average particle diameter of about 5 ⁇ m.
  • the average particle size is, for example, the average value of the particle sizes measured by the Fisher Sub-Sieve Sizer method.
  • a 2 O 2 S: X (where A is any one of Y, La, Gd, and Lu, and X is any one of Eu, Tb, and Pr).
  • grains represented by are used.
  • a 2 O 2 S: X containing cerium (Ce) or samarium (Sm) as a coactivator may be used, and further, a mixed crystal phosphor is used. May be.
  • the weight of the phosphor particles 40 per unit thickness of the wavelength conversion layer 21 gradually decreases from the first surface 21a side toward the second surface 21b side opposite to the radiation XR incident side.
  • the weight of the binder 41 per unit thickness of the wavelength conversion layer 21 gradually increases from the first surface 21a side toward the second surface 21b side. Therefore, since the space filling factor of the phosphor particles 40 is large on the solid detector 20 side and small at a position away from the solid detector 20, the wavelength conversion layer 21 has a large light emission amount on the solid detector 20 side, and The spread of light emission from the phosphor particles 40 to the solid state detector 20 is suppressed. For this reason, the sensitivity and sharpness of the image obtained by the solid state detector 20 are improved.
  • the space filling rate of the phosphor particles 40 in the wavelength conversion layer 21 is desirably 63% or more.
  • the space filling factor of the phosphor is obtained by the following method. First, a part of the wavelength conversion layer is cut out and the volume is measured. Next, the weight of the phosphor extracted from the wavelength conversion layer using a solvent or the like is measured, and the volume of the phosphor is calculated from the density of the phosphor. Each of the above volume ratios is expressed as the space filling factor of the phosphor. When the composition of the phosphor is unknown, composition analysis is performed and the density is calculated from the constituent elements and the crystal structure.
  • a release agent layer 51 is formed by applying a release agent such as silicone on the surface of a temporary support 50 formed of a resin such as PET.
  • a phosphor coating solution in which phosphor particles 40 are dispersed in a solution of binder 41 (binder solution) is applied onto the release agent layer 51 using a doctor blade.
  • the phosphor coating liquid contains a volatile solvent (such as MEK).
  • MEK volatile solvent
  • the wavelength conversion layer 21 is formed as a phosphor sheet.
  • the specific gravity of the phosphor particles 40 is large in the binder 41 solution, so that the phosphor particles 40 settle and move to the temporary support 50 side (the first surface 21a side). This movement is further facilitated by drying.
  • the weight of the binder 41 per unit thickness of the wavelength conversion layer 21 is changed from the side opposite to the temporary support 50 (second surface 21b side) to the temporary support 50 side (first surface 21a side). It gets smaller gradually.
  • a conductive layer 22b is formed by applying a conductive coating liquid to the surface of a resin film 22a formed of a resin such as PET, drying, and curing.
  • the light reflecting layer 22c is formed by applying the coating liquid in which the light reflecting material is dispersed onto the conductive layer 22b using a doctor blade and drying it. Thereby, the above-mentioned support body 22 is completed.
  • the wavelength conversion layer 21 created in the step shown in FIG. 6B is peeled off from the temporary support 50, and as shown in FIG. 7C, the wavelength conversion layer 21 is light-transmitted by the second surface 21b. It overlaps on the support 22 so as to be in contact with the reflective layer 22c. And in the state which accumulated the wavelength conversion layer 21 and the support body 22 in this way, it heat-compresses using a calender machine. Thereby, the second surface 21b of the wavelength conversion layer 21 is fused to the light reflecting layer 22c. Since the second surface 21b of the wavelength conversion layer 21 has a larger amount of the binder 41 than the first surface 21a, the melting amount of the binder 41 is large during the heat compression, and the adhesiveness with the light reflecting layer 22c. Excellent.
  • a pressure-sensitive adhesive sheet 53 is prepared by laminating a first release film 52a, a bonding agent layer 25, and a second release film 52b in this order. After peeling, the bonding agent layer 25 is bonded to the wavelength conversion layer 21 as shown in FIG.
  • the bonding agent layer 25 is formed of an acrylic bonding agent, and the first and second release films 52a and 52b are formed of a PET liner.
  • the radiation conversion sheet 54 created in the above process is cut into a specified size, and as shown in FIG. 8A, the edge pasting member 23 is used on the peripheral side surface of the cut radiation conversion sheet 54 using a dispenser. Coating. At this time, the edge pasting member 23 covers the outer periphery of the first release film 52a and the outer periphery of the resin film 22a. Then, as shown in FIG. 8B, a protective layer 24 is formed on the lower surface of the resin film 22a.
  • the second release film 52b is peeled off, and the first surface 21a of the wavelength conversion layer 21 is bonded to the surface of the solid state detector 20 manufactured by a known semiconductor process via the bonding agent layer 25. Specifically, first, when the second release film 52b is peeled off, dust on the surface of the bonding agent layer 25 is removed with an ionizer. Then, the radiation conversion sheet 54 and the solid detector 20 are bonded to each other through the bonding agent layer 25 by a bonding machine, and the solid detector 20 is pressed with a roller from the back surface of the solid detector 20, whereby the wavelength detector layer 21 is joined.
  • the radiological image detection apparatus 12 is completed through the above steps.
  • the first surface 21 a with a small amount of the binder 41 is bonded to the solid state detector 20. However, since the bonding is performed through the bonding agent layer 25, adhesion is ensured.
  • radiation XR is emitted from the radiation source 11 toward the subject 15.
  • the radiation XR that passes through the subject 15 and carries the radiation image of the subject 15 enters the radiation image detection device 12 from the solid detector 20 side.
  • the radiation XR incident on the radiation image detection device 12 passes through the solid detector 20 and enters the wavelength conversion layer 21 from the first surface 21a. In the wavelength conversion layer 21, the incident radiation XR is converted into light (visible light).
  • the amount of the binder 41 in the wavelength conversion layer 21 is small on the first surface 21 a side and the space filling rate of the phosphor particles 40 is large, the light emission amount of the phosphor particles 40 in the vicinity of the solid state detector 20. The spread of light from the phosphor particles 40 to the solid state detector 20 is small.
  • the amount of the binder 41 is small on the first surface 21a side, light is suppressed from propagating through the binder 41 in the lateral direction (direction orthogonal to the incident direction of the radiation XR).
  • the light converted by the wavelength conversion layer 21 enters the solid state detector 20.
  • the solid state detector 20 photoelectric conversion is performed, and signal charges generated by the photoelectric conversion are accumulated for each pixel 30.
  • the solid state detector 20 reads the signal charges accumulated in each pixel 30, converts each signal charge for one screen into image data, and outputs the image data.
  • the image data output from the solid state detector 20 is input to the signal processing device 13, subjected to signal processing in the signal processing device 13, and then input to the display device 14.
  • the display device 14 displays an image based on the input image data.
  • Example 1 Formation of wavelength conversion layer 20% by weight of a mixture of polyvinyl butyral resin, urethane resin fat and plasticizer was dissolved in 80% by weight of a mixed solvent of toluene, 2-butanol and xylene, and stirred sufficiently to obtain a binder solution ( A binder solution).
  • This binder solution and a Gd 2 O 2 S: Tb phosphor having an average particle diameter of 5 ⁇ m were mixed as a solid component at a mass ratio of 15:85, and dispersed by a ball mill to prepare a phosphor coating solution.
  • this phosphor coating solution was applied to the surface of PET (temporary support, thickness: 190 ⁇ m) coated with a silicone release agent in a width of 430 mm, dried, and then removed from the temporary support. It peeled and the wavelength conversion layer (thickness: 300 micrometers) was obtained.
  • a conductive layer A material having the following composition was added to 5 g of MEK (methyl ethyl ketone) and mixed and dispersed to prepare a coating solution. Then, this coating solution was applied to the surface of PET (support, thickness: 188 ⁇ m, haze 27%, Lumirror (registered trademark) S-10, manufactured by Toray Industries, Inc.) using a doctor blade, dried and cured. A conductive layer (film thickness: 5 ⁇ m) was formed.
  • MEK methyl ethyl ketone
  • Resin MEK solution (solid content 30% by weight) of saturated polyester resin (Byron 300 (registered trademark), manufactured by Toyobo Co., Ltd.) 20 g Curing agent: Polyisocyanate (Olestar NP38-70S (registered trademark, manufactured by Mitsui Toatsu Co., Ltd.) solid content 70%) 2 g Conductive agent: SnO 2 (Sb dope) needle-shaped fine particle MEK dispersion (solid content 30% by weight) 50 g
  • Light-reflective material 444 g of high-purity alumina fine particles (average particle size: 0.4 ⁇ m)
  • Binder Soft acrylic resin (Chriscoat P-1018GS (registered trademark, manufactured by Dainippon Ink & Chemicals, Inc.) “20% toluene solution”) 100 g
  • edge pasting member After cutting the radiation conversion sheet prepared in 1) to 5) to a specified size, set it in the dispenser of the edge pasting member, and control the robot to border the peripheral side surface of the phosphor layer. It covered with the pasting member.
  • a coating solution prepared by dissolving a mixture having the following composition in 150 g of methyl ethyl ketone was used.
  • Silicone polymer Polyurethane having a polydimethylsiloxane unit (Daiichi Seika Co., Ltd., Dialoma-SP3023 [15% methyl ethyl ketone solution]) 700 g
  • Crosslinking agent 30 g of polyisocyanate (Daiichi Seika Co., Ltd., Crossnate D-70 [50% solution])
  • Yellowing prevention agent Epoxy resin (Oilized Shell Epoxy Co., Ltd., Epicoat # 1001 [solid]) 6 g
  • Sliding agent Alcohol-modified silicone (Shin-Etsu Chemical Co., Ltd., X-2 2-2809 [66% xylene-containing paste]) 2 g
  • the obtained coating liquid is applied to the entire circumference of the end portion of the radiation conversion sheet that has been subjected to the corona discharge treatment (including from the end portion to the inside of 1 mm), and is sufficiently dried at room temperature to obtain an end having a film thickness of about 25 ⁇ m. A partial film was formed.
  • the wavelength conversion layer 21 is formed by dispersing the phosphor particles 40 having a substantially constant size in the binder 41.
  • the wavelength conversion layer 60 may be formed by mixing different first and second phosphor particles 61 and 62 in the binder 63.
  • the radiological image detection apparatus of the second embodiment has the same configuration as that of the radiological image detection apparatus 12 of the first embodiment except that the wavelength conversion layer 60 is used instead of the wavelength conversion layer 21.
  • the average particle diameter D1 of the first phosphor particles 61 is larger than the average particle diameter D2 of the second phosphor particles 62.
  • the average particle diameter D1 of the first phosphor particles 61 is preferably 5 ⁇ m or more and 12 ⁇ m or less, and more preferably about 6 ⁇ m.
  • the average particle diameter D2 of the second phosphor particles 62 is preferably 1 ⁇ m or more and less than 5 ⁇ m, and more preferably about 2 ⁇ m.
  • the space filling rate of the phosphor is improved and the image quality is improved. To do.
  • Both the first phosphor particles 61 and the second phosphor particles 62 may be formed of the same material (for example, GOS), or different materials (for example, GOS and LOS (Lu 2 O 2)). S: Tb)) may be used.
  • the space filling ratio SFR of the first phosphor particles 61 and the second phosphor particles 62 in the wavelength conversion layer 60 is a weight ratio WR of the second phosphor particles 62 to the first phosphor particles 61.
  • the weight ratio WR is preferably in the range of 20% to 40%, and in this range, the space filling rate SFR is about 68% or more.
  • the weight W1 of the first phosphor particles 61 per unit thickness of the wavelength conversion layer 60 gradually decreases from the solid state detector 20 side toward the support 22 side.
  • the weight W2 of the second phosphor particles 62 per unit thickness of the wavelength conversion layer 60 gradually increases from the solid state detector 20 side toward the support 22 side.
  • the first phosphor particles 61 having a large average particle diameter are present on the solid detector 20 side
  • the second phosphor particles 62 having a small average particle diameter are present on the support 22 side.
  • An image with high sensitivity and high sharpness can be obtained.
  • the weight distribution is schematically represented by a straight line, but is actually a curved line.
  • a phosphor coating solution in which the first phosphor particles 61 and the second phosphor particles 62 are dispersed in a solution of a binder 63 is coated on a temporary support and dried. You can do it. By doing so, the first phosphor particles 61 having a large average particle size settle and move to the temporary support side. On the other hand, the second phosphor particles 62 having a small average particle diameter are mostly occupied by the first phosphor particles 61 on the temporary support side, so that the second phosphor particles 62 enter the gaps between the first phosphor particles 61. Otherwise, it moves to the opposite side of the temporary support. As a result, the aforementioned weight distribution is obtained. As in the first embodiment, the weight of the binder 63 per unit thickness of the wavelength conversion layer 60 gradually decreases from the side opposite to the temporary support toward the temporary support.
  • the amount of movement of the first phosphor particles 61 toward the temporary support can be adjusted by controlling the drying conditions of the phosphor coating liquid. For example, when the phosphor coating liquid is slowly dried over time, the amount of movement of the first phosphor particles 61 to the temporary support side is large, and the first phosphor particles 61 on the temporary support side have a large amount of movement. The space filling rate is further increased.
  • the viscosity of the phosphor coating solution is decreased, One phosphor particle 61 is easily moved.
  • the movement amount of the first phosphor particles 61 toward the temporary support can be adjusted by controlling the temperature at the time of applying the phosphor coating liquid.
  • the wavelength conversion layer 60 formed in this manner is bonded to the surface 60a on the temporary support side through the bonding agent layer 25 to the solid state detector 20, and is opposite to the temporary support.
  • the light reflection layer 22c is bonded to the surface 60b.
  • the weight W2 of the second phosphor particles 62 is near the solid detector 20 side from the solid detector 20 side to the support 22 side. May not increase monotonously toward. This is because the first phosphor particles 61 prevent the second phosphor particles 62 from rising in the direction of the coating surface when the phosphor coating liquid is dried.
  • One of the first phosphor particles 61 has a larger particle diameter than that of the second phosphor particles 62, so that the blocking by the second phosphor particles 62 hardly occurs, and from the solid detector 20 side to the support body 22 side. It decreases monotonously.
  • FIG. 13 shows a case where the weight W2 monotonously increases after decreasing from the solid state detector 20 side toward the support body 22 side.
  • FIG. 14 shows a case where the weight W2 increases monotonously after increasing and decreasing from the solid state detector 20 side toward the support body 22 side.
  • the aggregates 63b raise the surface 60b so as to escape from the binder 63.
  • a crack 60c is generated between the aggregate 63b and the surface 60b, and the volatilized solvent in the aggregate 63b is released through the crack 60c.
  • a caldera-like blister is formed on the surface 60b, and a convex portion 60d is formed.
  • the diameter of the caldera-like convex portion 60d is about several mm to 1 cm.
  • the amount of protrusion of the protrusion 60d from the surface 60b is about 100 to 200 ⁇ m.
  • the thickness of the wavelength conversion layer 60 is about 300 ⁇ m.
  • This blister tends to occur more easily as the average particle diameter D1 of the first phosphor particles 61 near the surface 60b is larger. This is because the rise of the volatile solvent to the surface 60b side due to drying is blocked by the first phosphor particles 61 having a large particle diameter and remains.
  • the amount of the first phosphor particles 61 on the surface 60b side is reduced by increasing the drying time of the phosphor coating liquid and moving the binder 63 more toward the coating surface side of the phosphor coating liquid. Therefore, the generation of blisters is reduced.
  • the convex portion 60d by the blister generates an air layer 65 between the surface 60b of the wavelength conversion layer 60 and the light reflecting layer 22c. However, since the refractive index of the air layer 65 is lower than that of the wavelength conversion layer 60, the reflectance of light between the wavelength conversion layer 60 and the light reflection layer 22c is increased, thereby contributing to high sensitivity.
  • the first phosphor particles 61 having a large average particle diameter D1 can be used.
  • the first phosphor particles 61 having an average particle diameter D1 of 10 ⁇ m that can obtain a space filling rate SFR of 75% at the maximum, and the sensitivity is further improved.
  • the adhesiveness of the bonding agent layer 25 is high.
  • an air layer is hardly generated between the surface 60a and the bonding agent layer 25, light reflection and scattering are unlikely to occur. This is also advantageous for high sensitivity and high sharpness.
  • the radiation XR is incident from the surface 60a side of the wavelength conversion layer 60, and the main light emission region in the wavelength conversion layer 60 is on the surface 60a side, so that light emission is affected by the blister. No, it is advantageous for high sharpness.
  • the second embodiment two types of phosphor particles having different sizes are mixed in the binder to form the wavelength conversion layer, but three types of phosphor particles having different sizes are further mixed in the binder.
  • a wavelength conversion layer may be formed.
  • the small phosphor particles enter the gaps between the other phosphor particles, the space filling rate of the phosphor is further improved, and the image quality is further improved.
  • a wavelength conversion layer 70 shown in FIG. 17 is applied.
  • the wavelength conversion layer 70 is obtained by dispersing first phosphor particles 71, second phosphor particles 72, and third phosphor particles 73 having different sizes in a binder 74.
  • the average particle diameter of the first phosphor particles 71 is preferably 9 ⁇ m or more and 12 ⁇ m or less, and more preferably about 10 ⁇ m.
  • the average particle diameter of the second phosphor particles 72 is preferably 1 ⁇ m or more and less than 5 ⁇ m, and more preferably about 2 ⁇ m.
  • the average particle diameter of the third phosphor particles 73 is preferably 5 ⁇ m or more and less than 9 ⁇ m, and more preferably about 6 ⁇ m.
  • the first phosphor particles 71, the second phosphor particles 72, and the third phosphor particles 73 may be formed of the same material, or may be formed of different materials.
  • the weight ratio of the first phosphor particles 71, the second phosphor particles 72, and the third phosphor particles 73 is preferably about 5: 2: 3.
  • the space filling factor of the first to third phosphor particles 71 to 73 in the wavelength conversion layer 70 is preferably 68% or more.
  • the weight W1 of the first phosphor particles 71 per unit thickness of the wavelength conversion layer 70 gradually decreases from the solid state detector 20 side toward the support 22 side.
  • the weight W2 of the second phosphor particles 72 per unit thickness of the wavelength conversion layer 70 gradually increases from the solid state detector 20 side toward the support 22 side.
  • the weight W3 of the third phosphor particles 73 per unit thickness of the wavelength conversion layer 70 does not change much in the thickness direction.
  • the space filling rate increases in the order of the second phosphor particles 72, the third phosphor particles 73, and the first phosphor particles 71, and on the support 22 side
  • the space filling rate increases in the order of the first phosphor particle 71, the third phosphor particle 73, and the second phosphor particle 72.
  • a large number of first phosphor particles 71 having a large average particle diameter are present on the solid detector 20 side, and a large number of second phosphor particles 72 having a small average particle diameter are present on the support 22 side. A sharp image can be obtained.
  • the weight W2 of the second phosphor particles 72 and the weight W3 of the third phosphor particles 73 on the solid detector 20 side may be reversed. Also in the present embodiment, the weight W2 of the second phosphor particles 72 may not monotonously increase from the solid detector 20 side to the support 22 side in the vicinity of the solid detector 20 side.
  • the first phosphor particles 71, the second phosphor particles 72, and the third phosphor particles 73 are each dispersed in a solution of the binder 74.
  • the phosphor coating solution may be applied on a temporary support and dried. The surface on the temporary support side of the thus formed wavelength conversion layer 70 is joined to the solid state detector 20.
  • Other configurations of the present embodiment are the same as those of the second embodiment.
  • blisters are generated on the coating surface due to the drying of the phosphor coating solution.
  • the amount of the first phosphor particles 71 having a large average particle diameter is used as the phosphor. Since the amount of the coating liquid is reduced on the coating surface side, the generation of blisters is reduced. For this reason, the big 1st fluorescent substance particle 71 whose average particle diameter is 10 micrometers can be used, for example.
  • Other effects of the present embodiment are the same as those of the second embodiment.
  • the wavelength conversion layer may be formed by dispersing four or more kinds of phosphor particles having different average particle diameters in a binder.
  • the weight of the temporary support (the space filling factor) is obtained by applying the phosphor coating liquid to the temporary support and moving the phosphor particles having a large average particle diameter to the temporary support by its own weight.
  • a surfactant may be attached to the surface of the phosphor particles, and the phosphor particles may be moved to the opposite side of the temporary support by buoyancy obtained with the surfactant.
  • the surfactant is attached to a plurality of phosphor particles of different sizes and these are dispersed in a binder, the larger the average particle diameter, the greater the buoyancy that can be obtained. Easy to move to the side. In this case, what is necessary is just to join the solid light detector 20 on the opposite side to the temporary support body of the formed wavelength conversion layer.
  • the wavelength conversion layer is bonded to the solid state detector via the bonding agent layer, but the wavelength conversion layer may be pressed so as to be in direct contact with the solid state detector.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Medical Informatics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Radiology & Medical Imaging (AREA)
  • Optics & Photonics (AREA)
  • Pathology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Biophysics (AREA)
  • Measurement Of Radiation (AREA)
PCT/JP2013/056447 2012-03-12 2013-03-08 放射線画像検出装置及び放射線画像撮影システム Ceased WO2013137138A1 (ja)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN201380006771.5A CN104081224B (zh) 2012-03-12 2013-03-08 放射线图像检测装置及放射线图像摄影系统
US14/335,260 US9052401B2 (en) 2012-03-12 2014-07-18 Radiation image detection device and radiation imaging system

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2012054507 2012-03-12
JP2012-054507 2012-03-12
JP2013045386A JP5744941B2 (ja) 2012-03-12 2013-03-07 放射線画像検出装置及び放射線画像撮影システム
JP2013-045386 2013-03-07

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US14/335,260 Continuation US9052401B2 (en) 2012-03-12 2014-07-18 Radiation image detection device and radiation imaging system

Publications (1)

Publication Number Publication Date
WO2013137138A1 true WO2013137138A1 (ja) 2013-09-19

Family

ID=49161048

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2013/056447 Ceased WO2013137138A1 (ja) 2012-03-12 2013-03-08 放射線画像検出装置及び放射線画像撮影システム

Country Status (4)

Country Link
US (1) US9052401B2 (enExample)
JP (1) JP5744941B2 (enExample)
CN (1) CN104081224B (enExample)
WO (1) WO2013137138A1 (enExample)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6226579B2 (ja) * 2013-06-13 2017-11-08 東芝電子管デバイス株式会社 放射線検出器及びその製造方法
JP6326006B2 (ja) * 2014-06-20 2018-05-16 富士フイルム株式会社 転写材料、液晶パネルの製造方法および液晶表示装置の製造方法
JP6575105B2 (ja) 2015-03-27 2019-09-18 コニカミノルタ株式会社 シンチレータパネルおよびその製造方法
CN116293491A (zh) * 2016-04-25 2023-06-23 日本特殊陶业株式会社 波长转换构件、其制造方法及发光装置
JP2018189425A (ja) * 2017-04-28 2018-11-29 三菱ケミカル株式会社 Ｘ線像変換スクリーン、ｘ線撮影装置、及びｘ線検査装置
JP2019023579A (ja) * 2017-07-24 2019-02-14 コニカミノルタ株式会社 シンチレータ
CN111819707B (zh) * 2018-03-08 2023-05-02 夏普株式会社 元件、电子设备以及元件的制造方法
JP7333244B2 (ja) * 2019-10-24 2023-08-24 浜松ホトニクス株式会社 放射線検出器、及び、放射線検出器の製造方法
JP7325295B2 (ja) * 2019-10-24 2023-08-14 浜松ホトニクス株式会社 シンチレータパネル、放射線検出器、シンチレータパネルの製造方法、及び、放射線検出器の製造方法
JP7661243B2 (ja) * 2020-01-15 2025-04-14 株式会社小糸製作所 シンチレータおよびシンチレータの製造方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62212600A (ja) * 1986-03-14 1987-09-18 コニカ株式会社 放射線画像変換パネル
JP2007041008A (ja) * 2006-11-06 2007-02-15 Toshiba Corp 放射線増感紙の製造方法

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3913342B2 (ja) * 1997-12-18 2007-05-09 株式会社東芝 放射線増感紙とそれを用いた放射線検査装置
JP3838849B2 (ja) * 2000-03-28 2006-10-25 株式会社東芝 Ｘ線平面検出器
JPWO2003067282A1 (ja) * 2002-02-08 2005-06-02 株式会社東芝 Ｘ線検出器およびｘ線検出器の製造方法
EP1620750A1 (en) * 2003-04-24 2006-02-01 Philips Intellectual Property & Standards GmbH Detector element for spatially resolved detection of gamma radiation
EP1494067B1 (de) * 2003-07-02 2008-01-23 Agfa-Gevaert HealthCare GmbH System mit einem Scanner und einer Speicherschicht sowie Speicherschicht zum Speichern von Röntgeninformationen
JP2005106682A (ja) * 2003-09-30 2005-04-21 Konica Minolta Medical & Graphic Inc 放射線像変換パネル及び放射線像変換パネルの製造方法
US7304309B2 (en) * 2005-03-14 2007-12-04 Avraham Suhami Radiation detectors
JP4134993B2 (ja) * 2005-03-24 2008-08-20 日立金属株式会社 Ｘ線検出装置
JP5313632B2 (ja) * 2008-11-04 2013-10-09 富士フイルム株式会社 放射線画像検出器
JP2010121997A (ja) * 2008-11-18 2010-06-03 Fujifilm Corp 放射線画像検出器
JP2012026932A (ja) * 2010-07-26 2012-02-09 Fujifilm Corp 放射線検出器
JP5340444B2 (ja) * 2012-03-12 2013-11-13 富士フイルム株式会社 放射線画像検出装置及び放射線画像撮影システム

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62212600A (ja) * 1986-03-14 1987-09-18 コニカ株式会社 放射線画像変換パネル
JP2007041008A (ja) * 2006-11-06 2007-02-15 Toshiba Corp 放射線増感紙の製造方法

Also Published As

Publication number Publication date
CN104081224B (zh) 2016-02-03
US20150010130A1 (en) 2015-01-08
JP2013217913A (ja) 2013-10-24
CN104081224A (zh) 2014-10-01
JP5744941B2 (ja) 2015-07-08
US9052401B2 (en) 2015-06-09

Similar Documents

Publication Publication Date Title
JP5744941B2 (ja) 放射線画像検出装置及び放射線画像撮影システム
JP5340444B2 (ja) 放射線画像検出装置及び放射線画像撮影システム
JP5791281B2 (ja) 放射線検出装置及び放射線検出システム
US8399842B2 (en) Digital radiographic detector with bonded phosphor layer
JP5785201B2 (ja) 放射線画像検出装置
US8399841B2 (en) Digital radiographic detector with bonded phosphor layer
CN101002110A (zh) 放射线探测装置、闪烁体板及其制造方法和放射线探测系统
JP2008215951A (ja) 放射線検出器
US8647965B2 (en) Radiographic image detector, method of producing the same, and protective member
JP5313632B2 (ja) 放射線画像検出器
JP2010096616A (ja) 放射線画像検出器
JP5702047B2 (ja) 放射線変換シートおよび放射線画像検出器
WO2016167334A1 (ja) 放射線像変換スクリーン、フラットパネルディテクタ、放射線検出装置、及びシンチレータ
JP5102398B2 (ja) 放射線画像検出器
JP2007071836A (ja) 放射線検出装置及び放射線撮像システム
JP2019060821A (ja) Ｘ線タルボ撮影用パネル
JP4307127B2 (ja) 放射線撮影装置
JP7503969B2 (ja) 放射線撮像パネル、放射線撮像装置、放射線撮像システム、および、シンチレータプレート
JP7520643B2 (ja) 放射線撮像パネル、放射線撮像装置、放射線撮像システム、および、シンチレータプレート
US11520062B2 (en) Radiation imaging panel, radiation imaging apparatus, radiation imaging system, and scintillator plate
JP2010107198A (ja) 放射線画像検出器
JP2017049100A (ja) 放射線検出装置、放射線検出システム及び放射線検出装置の製造方法

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13761654

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 13761654

Country of ref document: EP

Kind code of ref document: A1