WO2010092869A1 - Détecteur de rayonnement et son procédé de fabrication - Google Patents

Détecteur de rayonnement et son procédé de fabrication Download PDF

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Publication number
WO2010092869A1
WO2010092869A1 PCT/JP2010/050952 JP2010050952W WO2010092869A1 WO 2010092869 A1 WO2010092869 A1 WO 2010092869A1 JP 2010050952 W JP2010050952 W JP 2010050952W WO 2010092869 A1 WO2010092869 A1 WO 2010092869A1
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Prior art keywords
scintillator
radiation detector
base material
elements
metal
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PCT/JP2010/050952
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English (en)
Japanese (ja)
Inventor
長友浩之
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日立金属株式会社
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Priority to JP2010550485A priority Critical patent/JP5170263B2/ja
Publication of WO2010092869A1 publication Critical patent/WO2010092869A1/fr

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    • 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
    • G01T1/2006—Measuring radiation intensity with scintillation detectors using a combination of a scintillator and photodetector which measures the means radiation intensity

Definitions

  • the present invention relates to a radiation detector used in a computed tomography (CT) apparatus that handles radiation such as X-rays, ⁇ -rays, ⁇ -rays, and ⁇ -rays, and in particular, a high-resolution X-ray CT apparatus that uses a scintillator element.
  • CT computed tomography
  • the present invention relates to a radiation detector.
  • a radiation CT apparatus includes a radiation source (for example, an X-ray tube) and a radiation detector arranged symmetrically with respect to an object to be imaged, and measures the radiation intensity at each detection position to measure the inside of the object to be imaged. It is configured to observe the structure.
  • a radiation source for example, an X-ray tube
  • a radiation detector arranged symmetrically with respect to an object to be imaged, and measures the radiation intensity at each detection position to measure the inside of the object to be imaged. It is configured to observe the structure.
  • the basic structure of the radiation detector is one in which a scintillator element is arranged on a plurality of arranged semiconductor photodetecting elements, and the scintillator element opens to the radiation source side to receive radiation such as X-rays.
  • the scintillator element is generally made of a material such as CdWO 4 , Bi 4 Ge 3 O 12 , or Gd 2 O 2 S processed into a columnar shape, and a plurality of scintillator elements are two-dimensionally arranged with an interval between adjacent elements. ing.
  • the scintillator element When radiation is incident on the opening surface of the scintillator element, the scintillator element itself emits light to emit visible light, and the semiconductor light detecting element disposed on the opposite surface of the opening surface receives the light and outputs an electrical signal.
  • the scintillator element of the radiation detector is designed so as to be as small as possible and the distance between adjacent elements is narrowed to improve the resolution and resolution.
  • Patent Document 1 discloses an example in which a scintillator element is coated with a white paint (light reflecting material) in which a powder such as titanium oxide is kneaded with an epoxy resin or the like.
  • Patent Document 2 discloses a metal reflection such as Au, Ag, Al, Ni, etc. on the surface of the scintillator element by a method such as sputtering or CVD (chemical vapor deposition). An example of covering the material is disclosed.
  • Patent Document 3 discloses an example in which a sintered body of metal particles is used as a reflector.
  • a metal reflector is obtained by sintering a coating material in which metal fine particles having a particle size of 1 ⁇ m or less, preferably 0.1 ⁇ m or less are dispersed in a solvent.
  • the radiation detector using the scintillator element has been improved to have a small opening area of the scintillator element and a narrow interval between adjacent elements.
  • an interval between adjacent scintillator elements is required to be 100 ⁇ m or less.
  • the production of a radiation detector in which scintillator elements are arranged at such a narrow interval has the following problems in the prior art.
  • Patent Document 1 a gap between adjacent scintillator elements is filled with a white paint obtained by kneading a powder of titanium oxide or the like with an epoxy resin or the like as a reflector.
  • a white paint obtained by kneading a powder of titanium oxide or the like with an epoxy resin or the like as a reflector.
  • the visible light emitted from the scintillator element is reflected by the titanium oxide powder in the white paint and guided to the semiconductor photodetector element.
  • the white paint to be filled becomes thin, and part of the visible light emitted by the scintillator elements is not reflected by the titanium oxide powder, but passes through the white paint and adjoins. It will enter the scintillator element. This phenomenon is called crosstalk, and causes a reduction in the resolution and resolution of the radiation detector.
  • FIG. 8 shows the relationship between the thickness of the reflective material and the light transmittance of light having a wavelength of 500 nm in a white paint kneaded with titanium oxide powder and an epoxy resin.
  • the white paint which is a reflective material
  • the light transmittance tends to increase.
  • the thickness is 100 ⁇ m or less
  • the increase in light transmittance is remarkable. With such light transmittance, the occurrence of crosstalk is inevitable in the radiation detector.
  • the reflective material is metal
  • the thickness is approximately 0.1 ⁇ m or more, total reflection is possible without transmitting visible light. Therefore, if metal is used for the reflective material that covers the scintillator elements, crosstalk can be avoided even if the interval between adjacent scintillator elements is narrow.
  • FIG. 9 shows an Ag film thickness distribution in the groove depth direction when an Ag film is formed in a groove having a width of 100 ⁇ m and a depth of 1.7 mm by sputtering.
  • the film is formed so that the Ag film thickness at the top of the groove is 1 ⁇ m.
  • the film thickness of Ag formed on the side surface of the groove is reduced in proportion to the groove depth, and the depth from the surface is reduced.
  • the thickness is 0.2 mm or more, the Ag film is not formed on the side surface of the groove. Therefore, with the method as shown in FIG. 9, it is not possible to form a reflector in the gap between adjacent scintillator elements.
  • a method of forming a metal reflector on the side surface of a groove having a high aspect ratio a method of forming a metal film by applying and sintering a solution containing metal fine particles as disclosed in Patent Document 3 is considered. It is done. However, in this method, since the film structure becomes rough reflecting the particle size of the metal fine particles, light cannot be scattered and high light reflectance cannot be obtained.
  • FIG. 10 shows the reflection characteristics of an Ag film obtained by applying a solution in which Ag fine particles having an average particle diameter of 25 nm are dispersed to the surface of the scintillator element and sintering it.
  • a light reflectance of 50% or less can be obtained in the entire visible light region with a wavelength of 400 nm to 900 nm.
  • a solution containing metal fine particles becomes a very expensive solution because a step of producing metal fine particles and dispersing them in a solvent is required. Therefore, when a solution containing fine metal particles is used, there is a problem that the manufacturing cost of the radiation detector is increased.
  • the present invention solves the above problems, and provides a radiation detector and a method for manufacturing the same, in which crosstalk is small even when the interval between adjacent scintillator elements is narrow.
  • a plurality of scintillator elements are arrayed on a semiconductor photodetector element array in which a plurality of semiconductor photodetector elements are arranged in a matrix so that the bottom faces the semiconductor photodetector elements.
  • a radiation detector provided with a light reflecting material on a surface other than the bottom surface of the scintillator element,
  • the scintillator elements are arranged adjacent to each other with an interval of 100 ⁇ m or less, and the light reflecting material is formed by sequentially forming a base material and a metal reflecting material.
  • the base material may be a base material containing an inorganic oxide.
  • the inorganic oxide may include silicon oxide.
  • the inorganic oxide film may contain titanium oxide.
  • the inorganic oxide containing silicon oxide may be a fired product of SOG (Spin On Glass).
  • the inorganic oxide containing titanium oxide may be a fired product of a titanium oxide precursor.
  • the metal reflector may be a fired product of an organometallic compound containing at least one of Ag, Au, Al, and Ni.
  • a step of forming a processing groove having a grid shape of 100 ⁇ m or less on one side of a scintillator substrate, and an inorganic oxide base material and a metal reflecting material are sequentially formed on the side of the processing groove.
  • the inorganic oxide precursor solution is filled in the processed groove by one of a dip coating method, a screen printing method, a spin coating method, and a dispensing method and baked to form the base material. Also good. Further, the viscosity of the inorganic oxide precursor solution may be 20 cP (0.020 Pa ⁇ s) or less.
  • the metal reflector may be formed by filling the groove and firing.
  • the viscosity of the organometallic compound solution may be 20 cP (0.020 Pa ⁇ s) or less.
  • the radiation detector of the present invention can be used as a radiation detector for a high-resolution X-ray CT apparatus with high resolution and resolution.
  • FIG. 1 is a perspective view showing the radiation detector of the present embodiment.
  • a scintillator array 3 is attached to a semiconductor photodetector element array 2 via an adhesive layer 4.
  • the semiconductor photodetecting element array 2 has a plurality of semiconductor photodetecting elements 21 arranged on a flat plate.
  • N pieces are arranged in a row direction and M pieces are arranged in a column direction.
  • the arrangement method is not limited to this.
  • the scintillator array 3 includes scintillator elements 31 processed into a columnar shape. In this scintillator array 3, each scintillator element 31 is aligned so that its bottom surface coincides with the surface of the corresponding semiconductor photodetecting element 21, and is attached via an adhesive layer 4.
  • the scintillator element 31 for example, a ceramic scintillator material such as CdWO 4 , Bi 4 Ge 3 O 12 , Gd 2 O 2 S or the like can be used, and the adhesive layer 4 is an optical adhesive having a high light transmittance, such as Epoxy Technologies. Epo-Tek301 (trademark) manufactured by KK is used.
  • Epo-Tek301 (trademark) manufactured by KK is used.
  • a reflecting material that reflects visible light emitted from the scintillator element 31 is formed on the side surface and the upper surface of the scintillator element 31 (opposite surface opposite to the surface facing the semiconductor light detection element 31). Has been.
  • FIG. 2 is an enlarged schematic view of the cross section of the radiation detector 1 shown in FIG.
  • a base material 32 and a metal reflector 33 are sequentially formed on the side surface of the scintillator element 31, and the scintillator element 31 is attached to the corresponding semiconductor photodetecting element 21 through the adhesive layer 4.
  • the base material 32 is formed to a thickness of 10 nm to 10 ⁇ m using an inorganic oxide material having high light transmittance at the emission wavelength of the scintillator element 31 such as silicon oxide or titanium oxide.
  • the metal reflector 33 is made of a material containing at least one of Ag, Au, Al, and Ni and having a high light reflectivity at the emission wavelength of the scintillator element 31 to a thickness of 0.1 ⁇ m to 10 ⁇ m.
  • a protective material such as silicon oxide may be further coated on the metal reflector 33.
  • the filler 34 may be filled in the gap between the adjacent scintillator elements 31.
  • a resin such as an epoxy resin, an ultraviolet curable resin, or a polyimide resin can be used.
  • these resins are filled with a mixture of heavy metal powders such as tungsten and molybdenum, the radiation shielding effect between the scintillator elements 31 can be enhanced, and the occurrence of crosstalk can be further prevented.
  • An upper surface reflecting material 35 is formed on the surface of the scintillator element 31 opposite to the surface facing the semiconductor light detection element 21.
  • the upper surface reflecting material 35 may be formed by sequentially forming a base material 32 and a metal reflecting material 33, or titanium oxide powder or the like used as a reflecting material in a conventional radiation detector is epoxy. A white paint kneaded with a resin may be used.
  • step 1 grooves are formed in a lattice pattern at a substantially constant pitch on a Gd 2 O 2 S scintillator substrate 5 processed to a desired size (FIG. 3A).
  • step 2 the grooved scintillator substrate 5 is dipped in the SOG solution 6 of HSG-R7-13 manufactured by Hitachi Chemical Co., Ltd., and the SOG solution 6 is filled into the groove formed in the scintillator substrate 5.
  • filling may be performed using a method such as a screen printing method, a spin coating method, or a dispensing method.
  • a pretreatment for improving wettability such as HMDS (hexamethyldisilazane) treatment or oxygen plasma irradiation is performed before filling the groove with the SOG liquid 6. You can do it. Furthermore, when the SOG liquid 6 in the groove is excessive, the SOG liquid 6 is shaken off using centrifugal force, or the SOG liquid 6 is sucked off with a non-woven fabric (Asahi Kasei Fibers Co., Ltd., Bencott). The SOG liquid 6 may be removed.
  • HMDS hexamethyldisilazane
  • the viscosity of the SOG liquid 6 is considered to be experimentally appropriate. It is preferable to prepare. In the present embodiment, an example in which the SOG liquid 6 having a viscosity of 15 cP (0.015 Pa ⁇ s) is used will be described.
  • step 3 the SOG liquid 6 is baked to form a base material 32 containing silicon oxide.
  • An electric furnace is used for firing, the temperature is raised from room temperature, and the temperature is kept at a predetermined temperature for a predetermined time.
  • the oxygen concentration during firing is sufficiently reduced, for example, 1000 ppm or less.
  • the base material 32 containing silicon oxide is formed on the groove processing surface, and the surface roughness of the groove processing surface is reduced.
  • the substrate is baked at 400 ° C. for 30 minutes, the thickness of the base material 32 on the grooved surface is 0.1 to 2 ⁇ m, and the surface roughness Ra of the grooved surface is 500 nm or less. (FIG. 3C) was obtained.
  • the SOG liquid 6 is filled in the groove of the scintillator substrate 5 and baked to form the base material 32 containing silicon oxide.
  • a base material containing another inorganic oxide may be formed.
  • the base material 32 containing titanium oxide may be formed by filling a precursor liquid of titanium oxide into the groove of the scintillator substrate 5 and baking it. Even when another oxide precursor liquid is used, the viscosity of the liquid is preferably 20 cP (0.020 Pa ⁇ s) or less from the viewpoint of easy filling into the grooves.
  • the metal is less likely to segregate from the organometallic compound liquid 7 on the base material 32 in the next step, and a uniform metal reflector 33 can be obtained.
  • This effect is considered to be because the base material 32 containing an inorganic oxide hardly reacts with the organic solvent contained in the organic compound liquid 7, and the starting point for segregation of the metal hardly occurs.
  • step 4 the scintillator substrate 5 on which the base material 32 is formed is immersed in the organometallic compound solution 7, and the organometallic compound solution 7 is filled in the grooves of the scintillator substrate 5.
  • the organometallic compound solution 7 Nano Dotite XA-9069 manufactured by Fujikura Kasei Co., Ltd., which is an organic silver compound solution, is used (FIG. 3 (d)).
  • the organometallic compound liquid 7 is filled in the groove of the scintillator substrate 5 by the dip coating method, but it may be filled by using other methods such as a screen printing method, a spin coating method, and a dispensing method. good. Furthermore, when the organometallic compound liquid 7 in the groove is excessive, the organometallic compound liquid 7 is shaken off using centrifugal force, or the non-woven fabric (Asahi Kasei Fibers Co., Ltd., Bencott) is used. The excess organometallic compound liquid 7 may be removed by sucking off the liquid.
  • the organometallic compound liquid 7 When the viscosity of the organometallic compound liquid 7 is increased, bubbles are likely to be entrained when filling the grooves, and uniform filling becomes difficult. 6 is preferably prepared.
  • the organometallic compound liquid 7 having a viscosity of 15 cP (0.015 Pa ⁇ s) is used.
  • the metal reflecting material 33 containing Ag is formed by baking the organometallic compound 7.
  • a hot plate is used and held at a predetermined temperature (for example, 150 ° C.) for a predetermined time (for example, 30 minutes).
  • the organometallic compound 7 before firing is colorless and transparent, but when Ag particles are deposited during firing, the color changes to brown, and then the Ag particles are bonded together to form a silver continuous film.
  • the thickness of the metal reflecting material 33 in the groove containing this Ag is 0.1 to several ⁇ m (FIG. 3E).
  • the metal metal compound liquid 7 is filled in the groove of the scintillator substrate 5 and fired to form the metal reflector 33 containing Ag.
  • a metal fine particle paste containing Ag, Au, Al, Ni, etc., which has a relatively high light reflectance with respect to visible light is filled in the groove of the scintillator substrate 5 and fired to obtain a fired metal fine particle.
  • the metal reflector 33 containing may be formed. Even when such a metal fine particle paste is used, the viscosity of the paste is preferably 20 cP (0.020 Pa ⁇ s) or less because of easy filling into the grooves.
  • step 6 the filler 34 is filled into the grooves of the scintillator substrate 5.
  • an epoxy resin mixed with a curing agent is used as the filler 34 and the grooves of the scintillator substrate 5 are filled by screen printing.
  • it may replace with the example which fills an epoxy resin using a screen printing method, and may use other filling methods, such as a dispensing method.
  • the epoxy resin is filled in a reduced-pressure atmosphere so that no bubbles remain inside the epoxy resin. Then, this epoxy resin is heated and cured for a predetermined time in an electric oven set at a predetermined temperature (FIG. 3 (f)).
  • step 7 the surface of the scintillator substrate 5 is ground.
  • the substrate surface grooved surface
  • the upper surface reflecting material 35 is formed.
  • the upper surface reflecting material 35 is made of epoxy resin mixed with a curing agent and further mixed with titanium oxide powder to form a white paint, and screen printing is performed on the surface (grooved surface) of the scintillator substrate 5. It will be applied by the method.
  • other application methods such as a dispensing method may be used.
  • the white paint is heated and cured for a predetermined time in an electric oven set at a predetermined temperature (FIG. 3 (h)).
  • a white paint in which an epoxy resin and titanium oxide powder are kneaded is used as the upper surface reflecting material 35.
  • white powder that reflects visible light emitted by the scintillator element 31, such as silicon oxide or A white paint using aluminum oxide powder or titanium oxide powder coated with silicon oxide may be used.
  • the base material and the metal reflecting material may be formed in order under the same conditions as in Steps 2 to 6 without using the white paint.
  • step 9 the back surface of the scintillator substrate 5 (the surface opposite to the groove processing surface) is ground to remove the base material 32, the metal reflector 33, and the filler 34 attached to the back surface of the scintillator substrate 5.
  • the scintillator substrate 5 is separated into a plurality of columnar scintillator elements 31, and the scintillator array 3 is formed (FIG. 3 (i)).
  • step 10 alignment is performed so that the plurality of scintillator elements 31 and the plurality of semiconductor light detection elements 21 face each other, and the opposite surface of the upper surface reflecting material 35 of the scintillator array 3 and the semiconductor light detection element array 2.
  • the surface is bonded through an adhesive layer 4.
  • the adhesive layer 4 is bonded to the scintillator array 3 and the semiconductor photodetecting element array 2 by using an optical adhesive and heating the adhesive layer 4 for a predetermined time in an electric furnace set at a predetermined temperature.
  • the radiation detector 1 of the present embodiment is completed (FIG. 3 (j)).
  • the interval between adjacent scintillator elements 31 is set to 100 ⁇ m or less.
  • step 1 a Gd 2 O 2 S scintillator substrate 5 machined to a width of 73 mm, a height of 22 mm, and a thickness of 2.0 mm is machined to form grooves having a width of 80 ⁇ m and a depth of 1.7 mm at a pitch of 1 mm. (FIG. 3A).
  • step 2 the grooved scintillator substrate 5 is dipped in the SOG solution 6 of HSG-R7-13 manufactured by Hitachi Chemical Co., Ltd., and the SOG solution 6 is filled into the groove formed in the scintillator substrate 5.
  • FIG. 3B the SOG solution 6 of HSG-R7-13 manufactured by Hitachi Chemical Co., Ltd.
  • the SOG liquid 6 is filled in the groove of the scintillator substrate 5 by the dip coating method, but it may be filled by a method such as a screen printing method, a spin coating method, or a dispensing method.
  • a pretreatment for improving wettability such as HMDS (hexamethyldisilazane) treatment or oxygen plasma irradiation is performed before filling the groove with the SOG liquid 6. You can do it. Furthermore, when the SOG liquid 6 in the groove is excessive, the SOG liquid 6 is shaken off using centrifugal force, or the SOG liquid 6 is sucked with a non-woven fabric (Asahi Kasei Fibers Co., Ltd., Bencott). Excess SOG liquid 6 may be removed.
  • HMDS hexamethyldisilazane
  • the viscosity of the SOG liquid 6 When the viscosity of the SOG liquid 6 is increased, bubbles are likely to be involved when filling the groove, and uniform filling becomes difficult. As a result of making and studying SOG liquids 6 having various viscosities, the present inventor has found that if the viscosity of the SOG liquid 6 is 20 cP (0.020 Pa ⁇ s) or less, it can be uniformly filled without entraining bubbles. In this example, the SOG liquid 6 having a viscosity of 15 cP (0.015 Pa ⁇ s) was used with sufficient margin.
  • step 3 the SOG liquid 6 was baked to form a base material 32 containing silicon oxide.
  • An electric furnace was used for firing, and the temperature was raised from room temperature and held at 400 ° C. for 30 minutes.
  • the oxygen concentration during firing was set to 1000 ppm or less.
  • a base material 32 containing silicon oxide was formed on the groove processing surface, and the surface roughness of the groove processing surface was alleviated.
  • the thickness of the base material 32 on the groove processed surface was 0.1 to 2 ⁇ m, and the surface roughness Ra of the groove processed surface was 500 nm or less (FIG. 3C).
  • the surface roughness Ra is measured by using an atomic force microscope, that is, an AFM (Digital Instruments, Nano Scope III), and the surface of the groove processing surface in the region of 5 ⁇ m square (5 mm ⁇ 5 mm) in the tapping mode and the probe. The distance was measured, and the difference in the irregularities on the surface of the grooved surface was calculated.
  • the SOG liquid 6 is filled in the groove of the scintillator substrate 5 and baked to form the base material 32 containing silicon oxide.
  • the base material 32 containing titanium oxide may be formed by filling a precursor liquid of titanium oxide into the groove of the scintillator substrate 5 and baking it. Even when another oxide precursor liquid is used, the viscosity of the liquid is preferably 20 cP (0.020 Pa ⁇ s) or less from the viewpoint of easy filling into the grooves.
  • the base material 32 containing an inorganic oxide By setting it as the base material 32 containing an inorganic oxide, in the next process, it is hard to segregate a metal from the organometallic compound liquid 7 on the base material 32, and it can be set as the uniform metal reflector 33. This effect is considered to be because the base material 32 containing an inorganic oxide hardly reacts with the organic solvent contained in the organic compound liquid 7, and the starting point for segregation of the metal hardly occurs.
  • the base material 32 is selected from those that are not dissolved by the organometallic compound liquid described below.
  • the base material 32 containing silicon oxide or other inorganic oxide is formed by using a material such as SOG liquid 6 containing silicon dioxide or other inorganic oxide without containing silicone resin. To do.
  • step 4 the scintillator substrate 5 on which the base material 32 was formed was immersed in the organometallic compound solution 7, and the organometallic compound solution 7 was filled in the grooves of the scintillator substrate 5.
  • an organic silver compound solution manufactured by Fujikura Kasei Co., Ltd., Nano-Dotite XA-9069 was used as the organometallic compound solution 7 (FIG. 3 (d)).
  • the organometallic compound liquid 7 is filled in the groove of the scintillator substrate 5 by the dip coating method, but it may be filled by a method such as a screen printing method, a spin coating method, or a dispensing method. Furthermore, when the organometallic compound liquid 7 in the groove is excessive, the organometallic compound liquid 7 is shaken off using centrifugal force, or the non-woven fabric (Asahi Kasei Fibers Co., Ltd., Bencott) is used. The excess organometallic compound liquid 7 may be removed by sucking off the liquid.
  • organometallic compound liquid 7 When the viscosity of the organometallic compound liquid 7 is increased, bubbles are easily involved when filling the groove, and uniform filling becomes difficult.
  • the inventor of the present application made organometallic compound liquids 7 having various viscosities, and as a result of repeated examination, as long as the viscosity of the organometallic compound liquid 7 is 20 cP (0.020 Pa ⁇ s) or less, it is uniform without entraining bubbles. In this example, the organometallic compound liquid 7 having a viscosity of 15 cP (0.015 Pa ⁇ s) was used with a sufficient margin.
  • step 5 the organometallic compound 7 was fired to form a metal reflector 33 made of Ag.
  • a hot plate was used and held at 150 ° C. for 30 minutes.
  • the organometallic compound 7 before firing was colorless and transparent, but when the Ag particles were precipitated during firing, the color turned brown, and then the Ag particles were combined to form a silver continuous film.
  • the thickness of the metal reflector 33 in the groove made of Ag was 0.1 to several ⁇ m (FIG. 3E).
  • FIG. 4 is an SEM image of the surface of the metal reflector 33 after firing
  • FIG. 11 is an image obtained by adjusting the contrast of FIG. 4 to make the grain noticeable.
  • a continuous Ag microstructure as shown in FIG. 4 (or FIG. 11) was formed by thermal decomposition of organic silver.
  • the light reflectance and light transmittance on the surface of the metal reflector 33 were measured at a wavelength of 500 nm, the light reflectance was 95.26% and the light transmittance was 0%.
  • the metal reflector 33 used in the radiation detector 1 It was confirmed that the light reflection characteristics were sufficient.
  • the ability to confine the visible light emitted by the scintillator element is improved, and the visible light emitted by the scintillator element is efficiently guided to the semiconductor photodetector element.
  • the output of the radiation detector can be increased.
  • Example 2 Next, examples in which the firing temperature in step 5 is varied will be described.
  • the metal reflector 33 is obtained by holding for 30 minutes on a hot plate set at a plurality of different firing temperatures. Then, 5 lines having a length of 2 microns are drawn from the SEM image of the metal reflector 33 at each firing temperature, and the average number is obtained by counting the number of Ag grains on the line, and 2 microns is divided by the average number. The results of calculating the particle size are shown below. 140 ° C firing: (Cannot be counted in a continuous film state)
  • 150 degreeC baking 38.4 counts, average particle diameter 52nm.
  • 160 degreeC baking 25.6 counts, average particle diameter 78nm.
  • the reflectance decreases as the area of the recesses formed between the Ag grains increases, but it has been found from experiments that the recesses tend to be conspicuous when the average particle size is 100 nm or more. Therefore, the reflectance characteristics as described above are achieved when the average particle size is less than 100 nm. Further, it has been confirmed that when the particle size of the structure of the metal reflective film is about 1/10 or less of the light wavelength of 500 nm, scattering is further suppressed and it contributes to an improvement in reflectance. Therefore, more preferable reflectance characteristics are achieved when the average particle diameter is less than 60 nm. Moreover, it is also preferable that the tissue is joined to form an integrated Ag film.
  • the firing temperature in step 5 is preferably 140 ° C. and 200 ° C. or less, more preferably 140 ° C. and less than 160 ° C., for example, about 150 ° C. Is preferred.
  • FIG. 5 is an SEM image of the surface of the metal reflector 33 obtained by firing the organometallic compound 7 by holding it on a hot plate at 250 ° C. for 30 minutes, and FIG. 12 is adjusted for contrast so that the granularity in FIG. 5 is conspicuous. Is.
  • the Ag microstructure became large and irregular in comparison with FIG. 4 (or FIG. 11).
  • grains has also increased.
  • the light transmittance and light transmittance on the surface of the metal reflector 33 were measured at a wavelength of 500 nm, the light transmittance was 0%, but the light reflectance was 92.54%. It was confirmed that the light reflectivity of the reflecting material 33 was lowered.
  • the SEM image of FIG. 4, 5 (or FIG. 11, 12) was observed with the sample for a measurement produced on the same conditions. That is, in the configuration of FIG. 2, force was continuously applied along the surface of the metal reflector 33, the base material 32 was cleaved, and the exposed surface was observed with an SEM to obtain a fine microstructure photograph of Ag. Is.
  • FIG. 6 shows the relationship between the light reflectance of the metal reflector 33 measured at a wavelength of 500 nm and the firing temperature. As the firing temperature increased, the light reflectance of the metal reflector 33 tended to decrease.
  • the reason why the light reflection characteristics of the metal reflector 33 are changed with respect to the firing temperature is considered to be due to the difference in the metal reflector structure with respect to the firing temperature.
  • the organometallic compound 7 is baked at a low temperature, the decomposition reaction of the organic silver is slow. Therefore, the precipitated Ag particles are bonded over time to form a continuous microstructure. It is thought that the structure of large and irregular particles is formed because the Ag particles precipitated before the formation of a continuous fine structure is fast and the reaction is completed. Accordingly, the temperature for firing the organometallic compound 7 is preferably as low as possible within the temperature range in which the thermal decomposition reaction occurs.
  • the metal metal compound liquid 7 is filled in the groove of the scintillator substrate 5 and baked to form the metal reflector 33 made of Ag.
  • the metal fine particle paste is put into the groove of the scintillator substrate 5.
  • the metal reflector 33 made of a fired metal fine particle may be formed by filling and firing.
  • the metal fine particles used for the metal fine particle paste are preferably metal fine particles containing Ag, Au, Al, Ni, etc., which have a high light reflectance with respect to visible light. Even when the metal fine particle paste is used, the viscosity of the paste is preferably 20 cP (0.020 Pa ⁇ s) or less from the viewpoint of easy filling into the grooves.
  • step 6 the filler 34 was filled into the grooves of the scintillator substrate 5.
  • the filler 34 a scintillator substrate manufactured by Three Bond Co., Ltd., mixed with epoxy resin of main agent 2023 and curing agent 2131D in a ratio of main agent 100: curing agent 30 (weight ratio) is used. 5 grooves were filled.
  • the epoxy resin is filled using a screen printing method, but other filling methods such as a dispensing method may be used. Furthermore, it is more preferable that the epoxy resin is filled in a reduced-pressure atmosphere so that no bubbles remain inside the epoxy resin.
  • the epoxy resin was cured by heating at 100 ° C. for 1 hour in an electric oven (FIG. 3 (f)).
  • step 7 the surface of the scintillator substrate 5 was ground.
  • the substrate surface grooved surface
  • a top reflector 35 was formed.
  • a white paint obtained by kneading 3 ⁇ m titanium oxide powder was applied to the surface (grooved surface) of the scintillator substrate 5 by screen printing. In this embodiment, the white paint is applied by the screen printing method, but other application methods such as a dispensing method may be used.
  • the white paint was cured by heating in an electric oven at 100 ° C. for 1 hour. (FIG. 3 (h)).
  • the base material 32 and the metal reflecting material 33 formed up to step 6 are formed under conditions optimal for forming between the scintillator elements. For this reason, the base material and the metal reflector formed on the upper surface are thick on the upper surface side, and cracks may be formed at the bent corners and may be peeled off. Therefore, the base material 32 and the metal reflecting material 33 adhering to the upper surface side of the scintillator substrate 5 are temporarily removed in step 7, and then the upper surface reflecting material 35 is re-formed in step 8.
  • a white paint kneaded with an epoxy resin and titanium oxide powder was used as the upper surface reflector 35, but white powder that reflects visible light emitted by the scintillator element 31, for example, silicon oxide or aluminum oxide powder, You may use the white coating material which used the powder which coat
  • step 9 the back surface of the scintillator substrate 5 (the surface opposite to the groove processing surface) was ground.
  • the base material 32, the metal reflector 33, and the filler 34 attached to the back surface of the scintillator substrate 5 are removed, and the scintillator substrate 5 is ground until the thickness of the scintillator substrate 5 is reduced from 2.0 mm to 1.7 mm. 5 was separated into a plurality of columnar scintillator elements 31 to form a scintillator array 3 (FIG. 3 (i)).
  • step 10 the opposite surface of the upper surface reflector 35 of the scintillator array 3 and the surface of the semiconductor light detection element array 2 are bonded so that the plurality of scintillator elements 31 and the plurality of semiconductor light detection elements 21 face each other. Bonded through layer 4.
  • the adhesive layer 4 is made of Epoxy Technologies, Epo-Tek301 optical adhesive, and heated in an electric furnace at 80 ° C. for 1 hour, so that the scintillator array 3 and the semiconductor photodetector array 2 are cured and bonded. And the radiation detector 1 was completed (FIG.3 (j)).
  • Example 3 Next, the crosstalk between the radiation detector of the present invention and a conventional radiation detector using a reflective material of white paint was compared.
  • radiation detectors having different scintillator element intervals of 20 ⁇ m to 150 ⁇ m were produced by the same manufacturing method as in Example 1.
  • a radiation detector having the same scintillator element size as in the present embodiment and a different scintillator element interval of 20 ⁇ m to 150 ⁇ m was manufactured using Three Bond Co., Ltd., main agent 2023, curing agent 2131D epoxy resin, main agent 100: cured. It was prepared using a white paint reflecting material in which titanium oxide powder having an average particle size of about 0.3 ⁇ m was kneaded with the mixture of the agent 30 (weight ratio).
  • FIG. 7 shows the relationship between scintillator element spacing and crosstalk.
  • the crosstalk increased as the scintillator element interval narrowed.
  • the scintillator element interval was Even if it becomes narrow, crosstalk is kept small. From the above, it was confirmed that the radiation detector of the present example was superior in crosstalk as compared with the radiation detector of the comparative example.
  • 1 radiation detector 2 semiconductor photodetector array, 21 semiconductor light detection element, 3 scintillator array, 31 scintillator elements, 32 Base material, 33 metal reflector, 34 filler, 35 top reflector, 4 Adhesive layer, 5 Scintillator board, 6 SOG liquid, 7 Organometallic compound solution.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Measurement Of Radiation (AREA)

Abstract

La présente invention concerne un détecteur de rayonnement utilisé pour un appareil de tomographie à rayons X haute résolution, l'intervalle entre des éléments scintillateurs adjacents étant inférieur ou égal à 100 µm et un élément réfléchissant possédant une faible diaphonie. L'invention concerne également un procédé de fabrication d'un tel détecteur de rayonnement. Sur une matrice d'éléments semi-conducteurs de détection de la lumière, des éléments semi-conducteurs de détection de la lumière étant agencés en matrice, des éléments scintillateurs sont fixés et disposés en matrice de façon que la partie inférieure de chaque élément scintillateur soit face à l'élément semi-conducteur de détection de la lumière correspondant. Un élément réfléchissant la lumière est disposé sur les surfaces autres que la partie inférieure de chaque élément scintillateur. L'élément réfléchissant la lumière est formé par la formation séquentielle d'un élément de base et d'un élément réfléchissant en métal.
PCT/JP2010/050952 2009-02-12 2010-01-26 Détecteur de rayonnement et son procédé de fabrication WO2010092869A1 (fr)

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WO2014109691A1 (fr) * 2013-01-08 2014-07-17 Scint-X Ab Scintillateur à rayons x présentant un revêtement multicouche
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WO2017104400A1 (fr) * 2015-12-14 2017-06-22 浜松ホトニクス株式会社 Panneau scintillateur et détecteur de rayonnement
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