WO2014162717A1

WO2014162717A1 - Scintillator array, x-ray detector and x-ray inspection apparatus

Info

Publication number: WO2014162717A1
Application number: PCT/JP2014/001866
Authority: WO
Inventors: 一光森本; 斉藤　昭久; 祥卓足達; 正規豊島; 小柳津　英二; 六反田　貴史
Original assignee: 株式会社東芝; 東芝マテリアル株式会社
Priority date: 2013-04-01
Filing date: 2014-03-31
Publication date: 2014-10-09
Also published as: CN105190775B; JP6419692B2; JPWO2014162717A1; CN105190775A

Abstract

Provided is a scintillator array which has high light output and excellent durability with respect to X-rays. This scintillator array is provided with: a plurality of scintillator blocks; and a reflective layer part that is provided among the plurality of scintillator blocks so as to integrate the plurality of scintillator blocks. The reflective layer part has a resin part. The resin part contains 70-84 parts by mass of a first metal oxide that is composed of titanium oxide and 16-30 parts by mass of a second metal oxide that is composed of a metal oxide other than titanium oxide so that the total of the first and second metal oxides is 100 parts by mass.

Description

Scintillator array, X-ray detector, and X-ray inspection apparatus

The present invention relates to a scintillator array, an X-ray detector, and an X-ray inspection apparatus.

In the fields of medical diagnosis and industrial nondestructive inspection, an X-ray inspection apparatus such as an X-ray tomographic imaging apparatus (computed tomography (CT) apparatus) is used. The X-ray CT apparatus has an X-ray tube (X-ray source) for irradiating a fan-shaped fan beam X-ray and an X-ray detector having a plurality of X-ray detection elements arranged in parallel, And the X-ray detection element is disposed to face each other such that the tomographic plane of the subject is at the center. In an X-ray CT apparatus, a subject is irradiated with a fan beam X-ray from an X-ray tube, absorption data of X-rays transmitted through the subject are collected by an X-ray detector, and the absorption data is analyzed by a computer The tomogram of the subject is reproduced by (calculating the X-ray absorptivity at each position on the tomographic plane and reconstructing the image according to the X-ray absorptivity).

As an X-ray detector of an X-ray CT apparatus, a detector using a solid scintillator which emits visible light by stimulation by X-rays is widely used. In an X-ray detector using a solid scintillator, it is easy to miniaturize the X-ray detection element and increase the number of channels, so the resolution of the X-ray CT apparatus can be further enhanced. Although various materials are known as solid scintillators, ceramic scintillators made of a sintered body of rare earth acid sulfide such as Gd ₂ O ₂ S: Pr have a large X-ray absorption coefficient and excellent luminous efficiency, Moreover, since afterglow (after glow) is short, it is suitable as a scintillator for X-ray detectors.

In the sintered body (phosphor ceramic) of the rare earth oxysulfide phosphor that constitutes the ceramic scintillator, various proposals have been made on the improvement of light output, the densification of the sintered body, the improvement of mechanical strength, etc. . For example, it is known that the light output of the ceramic scintillator can be increased by controlling the amount of PO ₄ . The light output is improved by controlling the amount of phosphorus in the ceramic scintillator (sintered body).

The improvement of the light output of the scintillator leads to the shortening of the inspection time as an X-ray inspection apparatus, that is, the reduction of exposure. Development of scintillator materials is an effective means for improving light output. In addition, since the scintillator is used as an array through the reflective layer portion, it is also considered effective to improve the reflective layer portion used for the scintillator array in order to improve the light output of the scintillator.

In the conventional scintillator array, for example, one in which a resin layer containing titanium oxide particles is provided on both sides of a radiation shielding plate is used as a reflective layer portion. If it is a scintillator array of the said structure, it is thought that reflection efficiency will improve from using a radiation shielding board. However, since both the radiation shielding plate and the resin layer containing titanium oxide particles are used as the reflective layer portion, cost increase can not be avoided.

The reflection properties of the titanium oxide particles are excellent. On the other hand, titanium oxide particles have photocatalytic properties. Therefore, when titanium oxide particles are mixed with resin to form a reflective layer portion, there is a problem that the resin is deteriorated due to the photocatalytic effect of titanium oxide particles during long-term use. When the resin of the reflective layer portion is deteriorated, the reflectance of the reflective layer portion is changed. As a result, there is a problem that the light output of the scintillator array is reduced.

Patent No. 4266114 Patent No. 3104696

The present embodiment is intended to address such a problem, and provides a scintillator array excellent in long-term reliability by improving the reflection effect of the reflection layer portion and further suppressing the deterioration of the resin. The purpose is to

The scintillator array according to the present embodiment includes a plurality of scintillator blocks and a reflective layer portion provided between the plurality of scintillator blocks so as to integrate the plurality of scintillator blocks. The reflective layer portion has a resin portion. The resin part is 100 parts by mass in total of 70 to 84 parts by mass of the first metal oxide composed of titanium oxide and 16 to 30 parts by mass of the second metal oxide composed of metal oxides other than titanium oxide To contain.

In the scintillator array according to the present embodiment, the photocatalytic property of titanium oxide can be suppressed and the deterioration of the resin can be suppressed after the reflective property is imparted to the reflective layer portion. By preventing the deterioration of the resin, the light output of the scintillator array can be stabilized. Therefore, the X-ray detector and the X-ray inspection apparatus having the scintillator array according to the embodiment can be made excellent in reliability.

The figure which shows an example of the side of the scintillator array concerning embodiment. The figure which shows an example of the upper surface of the scintillator array concerning embodiment. The figure which shows an example of the X-ray detector concerning embodiment. The figure which shows another example of the X-ray detector concerning embodiment. BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows an example of the X-ray inspection apparatus concerning embodiment. FIG. 6 is a view showing an example of a manufacturing process of the scintillator array according to the embodiment.

The scintillator array according to the embodiment includes a plurality of scintillator blocks and a reflective layer portion provided between the plurality of scintillator blocks so as to integrate the plurality of scintillator blocks. The resin part is 100 parts by mass in total of 70 to 84 parts by mass of the first metal oxide composed of titanium oxide and 16 to 30 parts by mass of the second metal oxide composed of metal oxides other than titanium oxide To contain.

An example of the side of the scintillator array concerning embodiment is shown in FIG. Moreover, an example of the upper surface of the scintillator array concerning embodiment is shown in FIG. The scintillator array 1 has a plurality of scintillator blocks 2. A reflective layer portion 3 is provided between the plurality of scintillator blocks 2. The reflective layer portion 3 is directly bonded to the scintillator block 2. The plurality of scintillator blocks 2 are integrated by the reflective layer portion 3. That is, the scintillator array 1 includes the plurality of scintillator blocks 2 and the reflective layer portion 3 provided between the plurality of scintillator blocks 2 so as to integrate the plurality of scintillator blocks 2.

The scintillator array 1 has a structure having a plurality of scintillator blocks 2 arranged in a line, or a plurality of scintillator blocks 2 arranged two-dimensionally in a predetermined number in the longitudinal direction and a lateral direction as shown in FIG. It may have a provided structure. When the plurality of scintillator blocks 2 are two-dimensionally arranged, the reflection layer portions 3 are provided between the scintillator blocks 2 in the longitudinal direction and the lateral direction. The number of scintillator blocks 2 is appropriately set according to the structure, resolution, etc. of the X-ray detector. In addition, the scintillator array 1 has a multi-channel structure.

The reflective layer portion 3 has a resin portion containing a metal oxide. The resin portion contains 70 to 84 parts by mass of the first metal oxide by mass ratio of titanium oxide (titanium oxide particles) and 30 to 16 parts by mass of the second metal by mass ratio of metal oxides other than titanium oxide. The oxide is contained in a total amount of 100 parts by mass.

The titanium oxide particles have high reflectance of light in the visible light region of 450 to 700 nm, so that the light output of the scintillator array 1 can be improved regardless of the material of the scintillator block 2. That is, the titanium oxide particles function as reflective particles. Examples of titanium oxide particles include particles of TiO ₂ . In addition, TiO ₂ includes rutile type, anatase type, brookite type and the like. Among these, rutile type is preferable. Rutile TiO ₂ is a material having low photocatalytic properties among TiO ₂ .

Moreover, it is preferable that the average particle diameter of a titanium oxide particle is 2 micrometers or less. When the average particle diameter of the titanium oxide particles exceeds 2 μm, it becomes difficult to control the dispersion state in the reflective layer portion 3. The average particle diameter of the titanium oxide particles is more preferably 1 μm or less, and still more preferably 0.4 μm or less. The lower limit of the average particle diameter of the titanium oxide particles is not particularly limited, but is preferably 0.01 μm or more in consideration of the productivity of the titanium oxide particles.

As described above, in the present embodiment, titanium oxide particles are used as the first metal oxide, and metal oxides other than titanium oxide are used as the second metal oxide. In addition, the total of the first metal oxide (titanium oxide particles) and the second metal oxide (a metal oxide other than titanium oxide) is 100 parts by mass, and the mass ratio of the first metal oxide (titanium oxide particles) is 70 It contains up to 84 parts by mass and contains 16 to 30 parts by mass of a second metal oxide (a metal oxide other than titanium oxide).

By incorporating a predetermined amount of the second metal oxide, the photocatalytic properties of the titanium oxide particles can be suppressed while making use of the reflection properties of the titanium oxide particles. When the content of the second metal oxide is less than 16 parts by mass, the amount of the second metal oxide is small, that is, the amount of titanium oxide is too large, and the effect of suppressing the deterioration of the resin can not be sufficiently obtained. On the other hand, when the amount of the second metal oxide exceeds 30 parts by mass and deterioration of the resin can be suppressed, the amount of titanium oxide is small, so the reflectance of the reflective layer decreases. When the reflectance of the reflective layer portion decreases, the light output of the scintillator array 1 decreases. Therefore, the content of the second metal oxide is more preferably 16 to 30 parts by mass, and still more preferably 17 to 25 parts by mass.

The second metal oxide is preferably at least one selected from the group consisting of aluminum oxide, zirconium oxide, tantalum oxide, and silicon oxide. Aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), and silicon oxide (SiO ₂ ) have almost no photocatalytic properties. Further, aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), and silicon oxide (SiO ₂ ) have a reflectance of visible light of a certain value or more, It is a component which contributes to reflectance improvement. Among these, aluminum oxide (Al ₂ O ₃ ) is particularly preferable. Aluminum oxide exhibits a white color when the purity is 95% or more, and the reflectance of visible light is improved. In addition, aluminum oxide has the merit of being cheaper than other metal oxides.

The second metal oxide may be contained as particles or may be contained as a surface film provided on the surface of titanium oxide particles. For example, part or all of the second metal oxide is preferably a surface film provided on the surface of titanium oxide particles. That is, the resin part may contain titanium oxide particles having a surface film of the second metal oxide.

The second metal oxide preferably contains both a surface film provided on the surface of titanium oxide particles and metal oxide particles. That is, the resin part may contain titanium oxide particles having a surface film of the second metal oxide and particles of the second metal oxide.

The surface coating of the second metal oxide can reduce the photocatalytic effect of the titanium oxide particles. On the other hand, if the surface coating amount is too large, the goodness of the reflectance of the titanium oxide particles is difficult to utilize. In addition, the reflectance of the surface-coated titanium oxide particles may change depending on the surface coating amount. Therefore, by causing particles of metal oxides other than titanium oxide to be present together, it is possible to reduce partial variation in reflectance in the reflective layer portion 3.

When the second metal oxide is present in both the surface film and the particles, the ratio (A / B) of the metal oxide amount A (mass parts) to be the surface film to the metal oxide amount B (mass parts) to be particles Is preferably 0.10 or more when A + B = 100 parts by mass (the total of A and B is 100 parts by mass). The thickness of the surface film is preferably 1/10 or less of the diameter of the titanium oxide particles. If the surface film is too thick, the reflection properties of the titanium oxide particles may not be utilized. Moreover, it is preferable that the average particle diameter of a 2nd metal oxide particle is 2 micrometers or less.

The resin portion preferably contains, for example, a thermosetting resin. As a thermosetting resin, 1 type chosen from the group which consists of an epoxy resin, a silicone resin, a phenol resin, a melamine resin, a urea resin, unsaturated polyester resin, an alkyd resin, a polyurethane resin, and a polyimide resin is preferable, for example. Among these resins, it is preferable to use an epoxy resin or a silicone resin. Epoxy resin or silicone resin is preferable because of high photocatalytic resistance.

When the mass of the resin contained in the resin portion is 100 parts by mass, the mass of the reflective particles is preferably in the range of 0.2 to 4 parts by mass. If the mass of the reflective particles is less than 0.2 parts by mass, the reflection properties of the reflective layer portion 3 may be insufficient. In addition, if the mass of the reflective particles exceeds 4 parts by mass, the adhesion strength between the scintillator block 2 and the reflective layer portion 3 may be reduced, and the intensity of the scintillator array 1 may be reduced. When the mass of the reflective particles is in the range of 0.2 to 4 parts by mass, the viscosity of the resin mixture described later can be easily adjusted. When the mass of the resin is 100 parts by mass, the mass of the reflective particles is more preferably 1 to 3 parts by mass. Here, the mass of the reflective particles indicates the total content of the first metal oxide and the second metal oxide.

The epoxy resin is preferably a two-component epoxy resin. Moreover, it is preferable that an epoxy resin is what does not have a double bond. The epoxy resin is a general term for a resin having two or more epoxy groups (oxysilane ring) in one molecule and which is three-dimensionally cured by a curing agent or the like. The one-pack type epoxy resin is a liquid resin in which an epoxy resin main agent and a curing agent are previously mixed, and is cured by heating. The two-part epoxy resin is a liquid resin in which an epoxy resin main agent and a curing agent are separate, and is cured by mixing two liquid materials. That is, in the case of a two-part epoxy resin, it can be cured at room temperature. By curing at room temperature, the thickness of the reflective layer portion 3 and the width W of the reflective layer portion 3 can be easily adjusted. In addition, since the reflective layer portion 3 can be formed without heating, it is possible to prevent the surface coating from being altered in the surface coated titanium oxide particles. In addition, since the two-pack type epoxy resin is mixed and cured with the epoxy resin main agent and the curing agent, the epoxy resin main agent and the curing agent before mixing can be stored separately and are easy to store.

The epoxy resin is preferably an aromatic epoxy resin or an aliphatic epoxy resin. The aromatic epoxy resin has a benzene ring in its molecular structure. In addition, aliphatic type epoxy resins do not have a benzene ring in the molecular structure. Both the aromatic epoxy resin and the aliphatic epoxy resin are transparent resins. In addition, the benzene ring is easily activated by X-ray irradiation or the photocatalytic effect of titanium oxide, and tends to cause deterioration of the resin. On the other hand, the adhesive strength of the aromatic epoxy resin having a benzene ring is higher than that of the aliphatic epoxy resin. Therefore, it is preferable to use an aliphatic epoxy resin in order to prevent deterioration of the resin of the scintillator array 1 and obtain long-term reliability. On the other hand, when it is desired to improve the bonding strength between the scintillator blocks 2 of the scintillator array 1, it is preferable to use an aromatic epoxy resin. With an aliphatic epoxy resin, the shear strength can be 1.5 kgf / mm ² or more, and with an aromatic epoxy resin, the shear strength can be 2.0 kgf / mm ² or more. The shear strength is measured using a bond tester, and is measured by a die shear test (at room temperature) in accordance with MIL STD-883.

When the mass of the epoxy resin is 100 parts by mass, the mass of the reflective particles is preferably in the range of 0.2 to 4 parts by mass. If the mass of the reflective particles is less than 0.2 parts by mass, the reflection characteristics of the reflective layer portion may be insufficient. In addition, if the mass of the reflective particles exceeds 4 parts by mass, the adhesive strength may be reduced, and the strength of the scintillator array 1 may be reduced. When the mass of the reflective particles is in the range of 0.2 to 4 parts by mass, the viscosity of the resin mixture described later can be easily adjusted. When the mass of the epoxy resin is 100 parts by mass, the mass of the reflective particles is more preferably 1 to 3 parts by mass. Here, the mass of the reflective particles indicates the total content of the first metal oxide and the second metal oxide.

The scintillator block 2 is preferably a solid scintillator made of single crystals or polycrystals of metal oxides, metal sulfides, metal oxysulfides. As a metal oxide fluorescent substance which comprises a solid scintillator, the metal oxide which has a garnet structure is mentioned. The garnet-type metal oxide is preferably aluminum garnet having a composition represented by the following formula (1).
(Gd _1-α-β-γ Tb _α Lu _β Ce _γ ) ₃ (Al _1-x Ga _x ) _a O _b (1)
(Wherein α and β are numbers satisfying 0 <α ≦ 0.5 atomic%, 0 <β ≦ 0.5 atomic%, α + β ≦ 0.85 atomic%, γ is 0.0001 ≦ γ ≦ 0. Number satisfying 1 atomic%, x is a number satisfying 0 <x <1 atomic%, a is a number satisfying 4.8 ≦ a ≦ 5.2 atomic%, b is 11.6 ≦ b ≦ 12. It is a number satisfying 4 atomic%.

The metal sulfide phosphor constituting the solid scintillator is preferably a rare earth sulfide, and examples thereof include composite sulfides such as NaGdS ₂ : Bi. Examples of metal oxysulfide phosphors include rare earth oxysulfides. The rare earth acid sulfide is preferably gadolinium oxysulfide having a composition represented by the following formula (2).
Gd ₂ O ₂ S: Pra _a (2)
a is an activation amount of praseodymium (Pr) with respect to 1 mol of gadolinium oxysulfide (Gd ₂ O ₂ S), and is preferably in the range of 0.0001 to 0.005 mol.

The scintillator block 2 consisting of a single crystal or polycrystal of the above-mentioned metal oxide, metal sulfide or metal oxysulfide is easy to emit light when excited by X-rays, and also has high photosensitivity. Suitable for line detectors. The scintillator block 2 is at least one selected from a sintered body of aluminum garnet having a composition represented by the formula (1) and a sintered body of gadolinium oxysulfide having a composition represented by the formula (2) More preferably, Moreover, since the sintered body represented by Formula (1) and Formula (2) does not deteriorate by heating at the time of hardening a resin part, it is preferable.

The thickness T of the scintillator block 2 is preferably in the range of 0.5 to 3 mm, and more preferably in the range of 1 to 2 mm. If the thickness T of the scintillator block 2 is less than 0.5 mm, the X-ray component passing through the scintillator block 2 may be increased, and the light output may be reduced. Even if the thickness T of the scintillator block 2 exceeds 3 mm, it is difficult to obtain a further improvement in light output, which causes an increase in manufacturing cost. The longitudinal and lateral lengths of the scintillator block 2 are not particularly limited. When the scintillator block 2 is a bar type (rod-like), it is preferable that the length in the longitudinal direction is in the range of 20 to 50 mm and the length in the lateral direction is in the range of 1 to 3 mm. As shown in FIG. 2, when the scintillator blocks 2 are two-dimensionally arranged, it is preferable that the lengths in the longitudinal direction and the lateral direction be in the range of 0.5 to 2 mm.

The width W of the reflective layer portion 3 (the distance between adjacent scintillator blocks 2 / the width W in FIG. 1) is preferably in the range of 10 to 100 μm. The width W of the reflective layer portion 3 is not particularly limited as long as the scintillator block 2 is disposed on the pixel of the photoelectric conversion element described later. However, when the width W of the reflective layer portion 3 is less than 10 μm, the function of the reflective layer portion 3 as an adhesive layer is reduced, and the adhesive strength of the reflective layer portion 3 to the scintillator block 2 is easily reduced. As a result, the intensity of the scintillator array 1 may be reduced. When the width of the reflective layer portion 3 exceeds 100 μm, the scintillator array 1 becomes larger than necessary. The width W of the reflective layer portion 3 is more preferably in the range of 20 to 80 μm. In the scintillator array 1 shown in FIG. 2, the width W of the reflective layer portion 3 may not be the same in the vertical direction and the horizontal direction.

The scintillator block 2 preferably has a surface roughness of 5 μm or less in arithmetic average roughness Ra (JIS B 0601-2001). By setting the surface of the scintillator block 2 as a flat surface having an arithmetic average roughness Ra of 5 μm or less, irregular reflection of X-rays can be suppressed. That is, the irradiation amount of X-rays to the scintillator block 2 can be increased. Therefore, the measurement accuracy of the X-ray by the scintillator block 2 is improved. The arithmetic average roughness Ra of the scintillator block 2 is more preferably 1 μm or less, further preferably 0.1 μm or less.

The reflective layer portion 3 preferably has a reflectance of 90% or more to light having a wavelength of 510 nm. Furthermore, it is preferable that the reflective layer portion 3 have a reflectance of 88% or more with respect to light having a wavelength of 670 nm. The X-ray detector detects the visible light emitted by exciting the scintillator block 2 with X-rays and converting the visible light into an electrical signal by a photoelectric conversion element. Therefore, the reflective layer portion 3 is required to have a high reflectance to light having a wavelength of 450 to 700 nm which is a visible light region. The reflectance for light in all visible light regions is more preferably 85% or more. The above-described gadolinium oxysulfide phosphor has large emission peaks in the range of 500 to 520 nm and in the range of 650 to 680 nm as the emission spectrum when excited by X-rays. Therefore, it is possible to further increase the light output of the scintillator array 1 by improving the reflectance of light in the above-mentioned wavelength region of the reflective layer portion 3.

Next, the X-ray detector and the X-ray inspection apparatus of the embodiment will be described with reference to the drawings. FIG. 3 and FIG. 4 are diagrams showing the configuration of the X-ray detector of the embodiment. The scintillator array 1 has a surface 1a to be an X-ray irradiation surface, and the photoelectric conversion element 4 is integrally installed on the surface 1b opposite to the surface 1a. For example, a photodiode is used as the photoelectric conversion element 4. The photoelectric conversion element 4 is disposed at a position corresponding to the scintillator block 2 constituting the scintillator array 1. As shown in FIG. 4, the surface reflection layer 6 may be provided on the surface 1 a of the scintillator array 1. The X-ray detector 5 is comprised by these.

The surface reflection layer 6 is not limited to the surface 1 a of the scintillator array 1, and may be provided on the surface 1 b which is the installation surface of the photoelectric conversion element 4. Furthermore, the surface reflection layer 6 may be provided on both the surface 1 a and the surface 1 b of the scintillator array 1. By providing the surface reflection layer 6 in the scintillator array 1, the reflection efficiency of visible light emitted from the scintillator block 2 can be further improved, and thus the light output of the scintillator array 1 can be increased. For the surface reflective layer 6, a mixture of reflective particles and a transparent resin, a lacquer-based paint, or the like is used. The mixture of the reflective particles and the transparent resin preferably has the same dispersion state of reflective particles as the reflective layer portion 3. The thickness of the surface reflection layer 6 is preferably in the range of 50 to 250 μm. If the thickness of the surface reflection layer 6 is less than 50 μm, the effect of improving the reflection efficiency can not be sufficiently obtained. When the thickness of the surface reflection layer 6 exceeds 250 μm, the transmitted X-ray dose decreases and the detection sensitivity decreases.

FIG. 5 shows an X-ray CT apparatus 10 which is an example of the X-ray inspection apparatus of the embodiment. The X-ray CT apparatus 10 includes the X-ray detector 5 of the embodiment. The X-ray detector 5 is attached to the inner wall surface of the cylinder on which the imaging region of the subject 11 is placed. An X-ray tube 12 for emitting X-rays is installed at substantially the center of the circular arc of the cylinder to which the X-ray detector 5 is attached. A subject 11 is disposed between the X-ray detector 5 and the X-ray tube 12. A collimator (not shown) is provided on the X-ray irradiation surface side of the X-ray detector 5.

The X-ray detector 5 and the X-ray tube 12 are configured to rotate around the subject 11 while performing X-ray imaging. Image information of the subject 11 is collected three-dimensionally from different angles. The signal (electrical signal converted by the photoelectric conversion element) obtained by the X-ray imaging is processed by the computer 13 and displayed as the object image 15 on the display 14. The subject image 15 is, for example, a tomogram of the subject 11. As shown in FIG. 2, it is also possible to construct a multi-tomographic image type X-ray CT apparatus 10 by using a scintillator array 1 in which scintillator blocks 2 are two-dimensionally arranged. In this case, a plurality of tomograms of the subject 11 can be simultaneously captured, and for example, imaging results can be depicted in three dimensions.

The X-ray CT apparatus 10 shown in FIG. 5 includes an X-ray detector 5 having the scintillator array 1 of the embodiment. As described above, the scintillator array 1 according to the embodiment has excellent light output because the reflection efficiency of visible light emitted from the scintillator block 2 is high based on the configuration of the reflective layer portion 3 and the like. By using the X-ray detector 5 having such a scintillator array 1, the imaging time by the X-ray CT apparatus 10 can be shortened. As a result, the exposure time of the subject 11 can be shortened, and it is possible to realize low exposure. The X-ray inspection apparatus (X-ray CT apparatus 10) of the embodiment is applicable not only to X-ray inspection for medical diagnosis of human body but also to X-ray inspection of animals, X-ray inspection for industrial use, etc. .

The scintillator array 1 of the embodiment is manufactured, for example, as follows. Hereinafter, a method for efficiently manufacturing the scintillator array 1 of the embodiment will be described. The manufacturing method of the scintillator array 1 of the embodiment is not limited to this. The scintillator array 1 may have any configuration as described above, and is not limited to the manufacturing method.

First, titanium oxide particles having an average particle diameter of 2 μm or less are prepared. The titanium oxide particles preferably have a particle size distribution in which a peak is present in the range of 0.2 to 0.3 μm. The titanium oxide particles preferably have a rutile structure.

Next, a metal oxide to be a second metal oxide is prepared. When the second metal oxide is added as metal oxide particles, it is preferable to use a metal oxide having an average particle diameter of 2 μm or less. Moreover, when providing a surface film in a titanium oxide particle, a surface treatment process is performed. The surface treatment process includes a chlorine method, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, a colloid method and the like. In addition, the amount of the second metal oxide that has become the surface coating can be determined by comparing the mass of the titanium oxide particles before the surface treatment step and the mass of the surface-coated titanium oxide particles after the surface treatment. In addition, the mass ratio of titanium oxide to the second metal oxide can also be determined from the peak ratio of the peak of titanium oxide to the peak of the second metal oxide by X-ray diffraction (XRD) analysis. In addition, analysis by X-ray fluorescence (X-ray fluorescence: XRF) is also possible.

Next, when the total of the titanium oxide particles and the second metal oxide is 100 parts by mass, a process of 70 to 84 parts by mass of the titanium oxide particles and 30 to 16 parts by mass of the second metal oxide Do. When adding a 2nd metal oxide only by metal oxide particle, it mix | blends so that the mass of a titanium oxide particle and the mass of a 2nd metal oxide particle may become a target ratio. When both surface-coated titanium oxide particles and second metal oxide particles are present, the amount of the second metal oxide film in the surface-coated titanium oxide particles is determined in advance, and the insufficiency is determined by oxidation of the second metal oxide. It mixes as a thing particle. In addition, in the case where only the surface-coated titanium oxide particles are used, only the surface-coated titanium oxide particles are prepared.

In order to prevent aggregation of titanium oxide particles and the like in the reflective layer portion 3, it is preferable to previously crush aggregates of titanium oxide particles with an ultrasonic vibrator or the like. The amount of impurity components in the titanium oxide particles is preferably 1% by mass or less. Next, a resin is prepared. The resin is preferably a resin such as the epoxy resin and silicone resin described above. The epoxy resin is preferably a two-component epoxy resin as described above.

Reflective particles such as titanium oxide particles and a resin such as epoxy resin are mixed. In the case of a two-part epoxy resin, an epoxy resin main agent and reflective particles such as titanium oxide particles are mixed. It is preferable that the reflective particles (titanium oxide particles, second metal oxide particles, or surface-coated titanium oxide particles) be uniformly dispersed in the resin. For uniform dispersion, mixing using a three-roll is preferred. Three-roll is a mixer that mixes using three rolls. Since three rolls are simultaneously moved and mixed, the mixing direction becomes a plurality of directions, and it becomes difficult to form aggregates during the mixing process. It is preferable to perform the mixing process using 3 rolls for 10 hours or more. In addition, it is also effective to mix the organic solvent and reduce the viscosity of the transparent resin, if necessary. In mixing the reflective particles with the transparent resin, it is preferable to mix little by little (for example, one-third), instead of mixing all the reflective particles at once.

A plurality of scintillator blocks 2 processed into a predetermined shape are arranged at regular intervals. A mixture of reflective particles and resin (hereinafter referred to as a resin mixture) is filled between adjacent scintillator blocks 2. By setting the viscosity of the resin mixture to 1 to 10 Pa · s (1000 to 10000 cps), the resin mixture can be smoothly filled between the scintillator blocks 2. If the viscosity of the resin mixture is less than 1 Pa · s (1000 cps), the viscosity is too low, and when the transparent resin is cured, the dispersion state of the reflective particles may not be controlled well. When the viscosity of the resin mixture exceeds 10 000 Pa · s (10,000 cps), the viscosity is too high, and it becomes difficult to uniformly fill the scintillator blocks 2. In the case of a two-pack epoxy resin, a curing agent or the like is added before adjusting the viscosity.

The filling step is preferably performed in vacuum. This can suppress the formation of a void in the reflective layer portion 3. The degree of vacuum at the time of filling is preferably 4 kPa (30 Torr) or less. If in a vacuum atmosphere of 4 kPa or less, it is easy to control the existence ratio of voids in the thickness direction of the reflective layer portion 3 to 0.1% or less. The surface of the scintillator block 2 is preferably processed flat so that the arithmetic average roughness Ra is 5 μm or less. After filling the resin mixture, heat treatment is performed to cure the transparent resin. The heat treatment is preferably performed, for example, at a temperature in the range of 80 to 160 ° C., depending on the curing temperature of the transparent resin. The scintillator block 2 made of a gadolinium oxysulfide sintered body or an aluminum garnet sintered body is preferable because it does not deteriorate in the heat treatment step. In order to prevent the reflective particles from being deposited in the transparent resin before curing, it is preferable to perform heat treatment within 3 hours after the transparent resin mixed with the reflective particles is filled. In the case of a two-component epoxy resin, it can be cured by leaving it at room temperature without heating. It is preferable to use a curing agent having such properties.

Another filling method of the resin (resin mixture) mixed with the reflective particles will be described with reference to FIG. The scintillator block element 7 shown in FIG. 6 is a plate-like element before being cut into individual scintillator blocks 2. As shown in FIG. 6A, the groove portion 8 to be the formation portion of the reflective layer portion 3 is formed in the scintillator block element 7. The groove portion 8 is formed by processing the scintillator block element 7 to a predetermined depth so as not to penetrate to the back surface of the scintillator block element 7. The scintillator block element 7 is provided with vertical and horizontal grooves, and the scintillator block element 7 is grooved so that the scintillator block 2 of a predetermined size is finally obtained.

Next, as shown in FIG. 6B, the groove 8 provided in the scintillator block element 7 is filled with the resin mixture to be the reflective layer portion 3. By setting the viscosity of the resin mixture in the range of 0.5 to 2.5 Pa · s, the resin mixture can be smoothly filled in the groove portion 8. Furthermore, the void can be suppressed by filling the resin mixture into the groove 8 in vacuum. The degree of vacuum at the time of filling is preferably 4 kPa or less. If in a vacuum atmosphere of 4 kPa or less, it is easy to control the existence ratio of voids in the thickness direction of the reflective layer portion 3 to 0.1% or less.

It is also effective to fill the grooves 8 with a resin (resin mixture) mixed with reflective particles using a centrifugal machine. The resin mixture can be uniformly filled in the grooves 8 provided in a large number in the scintillator block element 7 by utilizing the centrifugal force of the centrifugal machine. The centrifugal machine is effective when a large number of scintillator block elements 7 are filled with the resin mixture at one time or when a large scintillator block element 7 is filled with the resin mixture. Furthermore, it is also effective to fill the resin mixture in a vacuum. When the resin mixture is filled using a centrifuge, the rotation speed of the centrifuge is preferably 500 to 3000 rpm, and the rotation time is preferably 30 minutes or more.

When a centrifugal force is applied to fill the resin mixture in the groove portion 8, the voids contained in the resin are released by the centrifugal force. At this time, when the viscosity of the resin mixture exceeds 2.5 Pa · s, it is difficult for the void to be released outside due to the centrifugal force. When the viscosity of the resin mixture is less than 0.5 Pa · s, the resin mixture may flow to the outside of the scintillator block element 7 when centrifugal force is applied. The viscosity of the resin mixture is preferably in the range of 0.5 to 2.5 Pa · s. Furthermore, in order to uniformly fill the resin mixture in the grooves 8 provided in the scintillator block element 7, a certain rotational speed is required. The rotational speed of the centrifuge is preferably 500 rpm or more. If the rotation speed is too fast, the resin mixture may flow to the outside of the scintillator block element 7 and fall. The rotational speed of the centrifuge is preferably 3000 rpm or less.

As described above, the groove 8 provided in the scintillator block element 7 by adjusting the viscosity of the resin (resin mixture) containing reflective particles, the degree of vacuum during the filling process, the number of rotations and the rotation time of the centrifugal machine, and the like. The resin mixture can be uniformly filled inside. Furthermore, the percentage of voids present in the thickness direction of the reflective layer portion 3 can be 1% or less, further 0.1% or less, or even 0% (or less than the detection limit).

Next, the resin in the resin mixture filled in the groove 8 is cured. By curing the resin, the scintillator block element 7 having the reflective layer portion 3 is formed. Next, as shown in FIG. 6C, the scintillator block element 7 is separated into individual scintillator blocks 2 by polishing the scintillator block element 7 having the reflection layer portion 3 and at the same time the reflection layer The portion 3 is processed to have a shape penetrating the front and back of the scintillator array 1. Polishing may be performed on either one side or both sides of the scintillator block element 7. The polishing process of the scintillator block element 7 is preferably performed such that the arithmetic average roughness Ra of the scintillator block 2 is 5 μm or less. Further, for the polishing process of the scintillator block element 7, for example, a lapping process using diamond abrasive is applied. As shown in FIG. 6, the method of providing the grooves 8 in the scintillator block element 7 is effective for producing a large array.

(Examples 1 to 5 and Comparative Examples 1 to 3)
As a scintillator block element, a plate (40 mm long × 20 mm wide × 1.5 mm thick) made of a gadolinium oxysulfide sintered body (Gd ₂ O ₂ S: Pr _a , a = 0.01) was prepared. Next, wire sawing was performed so that the size of each scintillator block was 1.0 mm long × 1.0 mm wide × 1.4 mm thick, and the groove width was 0.05 mm (50 μm). Further, after the wire saw processing, a strain removing heat treatment was performed. Next, titanium oxide particles were prepared as reflective particles. As titanium oxide particles, those having an average particle diameter of 0.2 μm and a peak of particle size distribution of 0.22 μm were prepared. Moreover, the titanium oxide particle prepared the rutile type thing.

Next, aluminum oxide (Al ₂ O ₃ ) particles, zirconium oxide (ZrO ₂ ) particles, tantalum oxide (Ta ₂ O ₅ ) particles, and silicon oxide (SiO ₂ ) particles were prepared as the second metal oxide. Moreover, as for the second metal oxide particles, those having an average particle diameter of 0.3 μm were prepared. The titanium oxide particles and the second metal oxide particles were mixed. The mixed powder was subjected to an ultrasonic vibrator to sufficiently crush the aggregates.

Next, an epoxy resin shown in Table 1 was prepared, mixed powder was added, and a mixing process was performed for 20 to 50 hours with a three-roll mixer. The viscosity of the obtained resin mixture was adjusted to be in the range of 0.5 to 2.5 Pa · s. In the resin mixture, when the epoxy resin was 100 parts by mass, the mass of the reflective particles (the total of the titanium oxide particles and the second metal oxide particles) was unified at 1.5 parts by mass.

Next, the resin mixture was filled into the grooves of the scintillator block element using a centrifuge. The filling step was performed in a vacuum (4 kPa or less) at a rotational speed of 500 to 3000 rpm. Moreover, the heating process was performed as needed, and the epoxy resin was hardened. Then, the back surface side (surface side in which the groove part is not formed) of the scintillator block element was grind | polished with a diamond grindstone, and the scintillator array concerning an Example and a comparative example was produced. The material, the addition amount of the second metal oxide, and the material of the epoxy resin are as shown in Table 1.

(Examples 6 to 15)
As a scintillator block element, a plate (40 mm long × 20 mm wide × 1.5 mm thick) made of a gadolinium oxysulfide sintered body (Gd ₂ O ₂ S: Pr _a , a = 0.01) was prepared. Next, wire sawing was performed so that the size of each scintillator block was 1.0 mm long × 1.0 mm wide × 1.4 mm thick, and the groove width was 0.05 mm (50 μm). Further, after the wire saw processing, a strain removing heat treatment was performed. Next, titanium oxide particles were prepared as reflective particles. As titanium oxide particles, those having an average particle diameter of 0.2 μm and a peak of particle size distribution of 0.22 μm were prepared. The titanium oxide particles were rutile type.

Aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), and silicon oxide (SiO ₂ ) were prepared as the second metal oxide. Next, a surface treatment step was performed on the titanium oxide particles to provide a surface coating of the second metal oxide. In addition, the surface treatment process was performed by the chlorine method. Further, the mass ratio of the titanium oxide particles to the surface coating (second metal oxide) in the surface-coated titanium oxide particles is as shown in Table 2.

Further, to meet the conditions shown in Table 2, second metal oxide particles were prepared, and surface-coated titanium oxide particles and second metal oxide particles were added. In addition, as a second metal oxide particle, one having an average particle diameter of 0.3 μm was prepared. Further, the surface-coated titanium oxide particles (a mixture of the surface-coated titanium oxide particles and the second metal oxide particles when the second metal oxide particles were added) were subjected to an ultrasonic vibrator to sufficiently crush aggregates.

Next, an epoxy resin shown in Table 2 was prepared, mixed powder was added, and a mixing process was performed for 20 to 50 hours with a three-roll mixer. The viscosity of the obtained resin mixture was adjusted to be in the range of 0.5 to 2.5 Pa · s. When the amount of the epoxy resin was 100 parts by mass, the amount of the reflective particles (the total of the surface-coated titanium oxide particles and the second metal oxide particles) was unified to 2 parts by mass.

Next, the resin mixture was filled into the grooves of the scintillator block element using a centrifuge. The filling step was performed in a vacuum (4 kPa or less) at a rotational speed of 500 to 3000 rpm. Moreover, the heating process was performed as needed, and the epoxy resin was hardened. Then, the back surface side (surface side in which the groove part is not formed) of the scintillator block element was grind | polished with a diamond grindstone, and the scintillator array concerning an Example and a comparative example was produced. The material, the addition amount of the second metal oxide, and the material of the epoxy resin are as shown in Table 2.

With respect to the scintillator arrays according to Examples 1 to 15 and Comparative Examples 1 to 3, the reflectance of the reflective layer portion, the durability to X-rays, and the shear strength were measured. As the reflectance of the reflective layer portion, the light reflectance (%) at wavelengths of 510 nm and 670 nm was determined. In addition, as a measurement of the durability to X-rays, the reduction rate of light output before and after X-ray irradiation of 10 kGy (10 kilograms) was determined. Specifically, it was determined by (light output after X-ray irradiation / light output before X-ray irradiation) × 100 (%). Further, 10 kGy which is the X-ray irradiation condition corresponds to the X-ray irradiation amount irradiated to the scintillator array when used for about 10 years in the X-ray CT apparatus. The shear strength was measured using a bond tester, and was performed by a die shear test (at room temperature) in accordance with US MIL STD-883. The measurement results are shown in Table 3.

As can be seen from Table 3, the scintillator array according to the example had excellent reflectance. Therefore, it turns out that it can be set as the scintillator array excellent in light output. In addition, it can be seen that the durability to X-rays is also excellent. In addition, the use of both the surface-coated titanium oxide particles and the second metal oxide particles was superior in the characteristics.

As described above, the scintillator array according to the embodiment is excellent in light output, and moreover, is excellent in durability to X-rays. Therefore, a scintillator array excellent in long-term reliability can be obtained. Therefore, it is understood that the long-term reliability is enhanced in the X-ray detector and the X-ray inspection apparatus using the scintillator array of the embodiment.

(Examples 16 to 19)
The epoxy resin of Example 1 was changed to a silicone resin, Example 16 was used, and the epoxy resin of Example 2 was changed to a silicone resin, Example 17 was used, and the epoxy resin of Example 1 was changed to a polyimide resin. The product is referred to as Example 18 and the epoxy resin of Example 2 is changed to a polyimide resin to obtain Example 19. The same measurements as in Example 1 were performed on the scintillator arrays according to Examples 16-19. The results are shown in Table 4.

As can be seen from Table 4, excellent effects were obtained even when the resin was changed.

While certain embodiments of the present invention have been illustrated, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in other various forms, and various omissions, replacements, changes, and the like can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof. In addition, the embodiments described above can be implemented in combination with each other.

Claims

A scintillator array comprising: a plurality of scintillator blocks; and a reflective layer portion provided between the plurality of scintillator blocks so as to integrate the plurality of scintillator blocks,
The reflective layer portion has a resin portion,
The resin part is a total of 100 parts by mass of 70 to 84 parts by mass of the first metal oxide of titanium oxide and 16 to 30 parts by mass of the second metal oxide of metal oxides other than the titanium oxide. The scintillator array characterized in that it contains.
The scintillator array according to claim 1, wherein the second metal oxide contains at least one selected from the group consisting of aluminum oxide, zirconium oxide, tantalum oxide, and silicon oxide.
The said resin part contains the particle | grains of the said titanium oxide, The scintillator array of Claim 1 characterized by the above-mentioned.
The scintillator array according to claim 3, wherein an average particle diameter of the titanium oxide particles is 2 μm or less.
The scintillator array according to claim 1, wherein the resin portion includes particles of the titanium oxide having a surface film of the second metal oxide.
The scintillator array according to claim 1, wherein the resin portion includes particles of the titanium oxide having a surface film of the second metal oxide and particles of the second metal oxide.
When the sum of the amount of the surface film of the second metal oxide and the amount of the particles of the second metal oxide is 100 parts by mass, the second metal oxide relative to the mass part B of the particles of the second metal oxide The scintillator array according to claim 6, wherein a ratio (A / B) of mass parts A of the surface film of the object is 0.10 or more.
The scintillator array according to claim 5, wherein the thickness of the surface coating of the second metal oxide is 1/10 or less of the diameter of the titanium oxide particles.
The scintillator array according to claim 1, wherein the resin portion comprises an epoxy resin or a silicone resin.
The scintillator array according to claim 1, wherein the resin part comprises a two-part epoxy resin.
The scintillator array according to claim 1, wherein the resin portion comprises an aromatic epoxy resin or an aliphatic epoxy resin.
When the mass of the resin contained in the resin part is 100 parts by mass, the total content of the first metal oxide and the second metal oxide is 0.2 to 4 parts by mass. The scintillator array according to claim 1.
The scintillator array according to claim 1, wherein the scintillator block comprises a gadolinium oxysulfide sintered body or an aluminum garnet sintered body.
An X-ray detector comprising the scintillator array according to claim 1.
An X-ray examination apparatus comprising the X-ray detector according to claim 14.