JP5080910B2 - Array manufacturing method, scintillator array - Google Patents

Description

  The present invention relates to a scintillator array composed of a plurality of scintillator crystals, and an array manufacturing method for manufacturing the scintillator array.

  When a drug labeled with a positron emitting isotope (RI) is administered to the subject, annihilation γ rays are emitted. Nuclear medicine imaging apparatuses such as PET (Positron Emission Tomography), SPECT (Single Photon Emission Computation Tomography), and a gamma camera are apparatuses that obtain a distribution image of RI in a subject by detecting this radiation.

  Such a nuclear medicine imaging apparatus uses a scintillator array composed of a plurality of scintillator crystals. Such a scintillator array is formed, for example, in a structure in which elongated scintillator crystals are two-dimensionally arranged at predetermined intervals in a direction orthogonal to the longitudinal direction.

  The scintillator array is connected to a photodetector such as a photomultiplier tube and used as a radiation detector. When radiation is incident on the scintillator array, the scintillator crystal at the radiation incident site emits light, and the connected photodetector is irradiated with radiation. It has a function to output a light amount proportional to the intensity.

  Also, a method of manufacturing a scintillator array by manufacturing a crystal container having enclosing holes aligned at a predetermined interval using a plate material having a high light reflectance, and fitting a scintillator crystal in the enclosing holes. Has been proposed (see, for example, Patent Document 2).

In addition, a technique has also been proposed in which cut grooves having a predetermined interval are formed vertically and horizontally in a scintillator crystal cut into a block shape, and the cut grooves are filled with a reflective material (see, for example, Patent Document 3).
JP-A-1-145596 Japanese Patent Laid-Open No. 5-341409 JP-A-5-019060

  In the technique described in Patent Document 1, it is difficult to maintain the uniformity of the thickness of the reflective agent applied and the thickness of the reflective tape, and it is very difficult to obtain the accuracy of the arrangement of the individual scintillator crystals. It is. Furthermore, the assembly work becomes complicated and it is difficult to obtain the overall dimensional accuracy.

  Moreover, in the technique described in Patent Document 2, it is easy to incorporate each scintillator crystal into a processed case, and the overall dimensions after assembly can be maintained with high accuracy. Is significantly more expensive.

  Moreover, in the technique described in Patent Document 3, it is difficult to uniformly inject a reflective agent into a plurality of grooves. In addition, the surface of the scintillator crystal becomes rough as the grooves are manufactured. Due to the roughening of the groove surface, the amount of multiple reflections of light within individual scintillator crystals increases and the amount of light output decreases, and the crystal remains unprocessed during groove cutting. The problem arises that the position resolution of the radiation detector is reduced due to the portion.

  Furthermore, the reflective material disclosed in these prior art documents is a fluororesin such as polytetrafluoroethylene or a polyester-based resin, and has a low reflectivity of 90% or less for light emission with an emission wavelength of 400 nm or less. There is a problem that the amount of light output from the scintillator crystal decreases.

  The present invention has been made in view of the above-described problems. A scintillator array in which the positional accuracy and detection sensitivity of a plurality of arranged scintillator crystals are good, and such a scintillator array can be easily manufactured. An array manufacturing method that can be used is provided.

  The array manufacturing method of the present invention is an array manufacturing method for manufacturing a scintillator array composed of a plurality of scintillator crystals, and forms a plurality of elongated scintillator crystals that generate fluorescence inside when radiation is incident thereon. The scintillator crystals are two-dimensionally arranged at predetermined intervals in a direction orthogonal to the longitudinal direction, and a mixed liquid in which resin and solvent are mixed is filled in the gaps between the arranged scintillator crystals, and the solvent is depressurized from the mixed liquid. Remove and solidify the resin.

  Therefore, in the array manufacturing method of the present invention, a plurality of elongated scintillator crystals that are two-dimensionally arranged in a direction orthogonal to the longitudinal direction at a predetermined interval, and a resin that fills the gaps between the plurality of scintillator crystals A scintillator array consisting of can be manufactured. Since the plurality of scintillator crystals are arranged two-dimensionally and then the mixed liquid filled in the gap is solidified, the positional accuracy of the plurality of scintillator crystals is good. In addition, there is no need to arrange a plurality of scintillator crystals in which an outer surface is coated with a reflective material or a reflective tape, and there is no need to press-fit a plurality of scintillator crystals into a storage container. There is no need to cut the scintillator crystal to form a scintillator array.

  Further, in the array manufacturing method of the present invention, a powder of a reflective material may be mixed in the mixed solution.

In the array manufacturing method of the present invention, the reflector powder may be made of at least one of BaSO ₄ , TiO ₂ , Al ₂ O ₃ , and MgO.

  In the array manufacturing method of the present invention, the average particle size of the powder of the reflective material may be 1 μm or less.

  Moreover, in the array manufacturing method of the present invention, the composition ratio of the mixed solution may be 5 parts by weight or less of the resin by weight with respect to 100 parts by weight of the reflective material.

  In the array manufacturing method of the present invention, the resin may be composed of at least one of acrylic resin, polyvinyl alcohol, silicone resin, and epoxy resin.

  In the array manufacturing method of the present invention, a scintillator crystal that emits fluorescence having an emission wavelength of 400 nm or less may be formed.

  The scintillator array of the present invention is a scintillator array composed of a plurality of scintillator crystals that generate fluorescence inside when radiation is incident, and has a long and narrow shape arranged in two dimensions in a direction orthogonal to the longitudinal direction. A plurality of scintillator crystals, and a resin in which a powder of a reflecting material is mixed and filled in a gap between the plurality of scintillator crystals.

In the scintillator array of the present invention, the reflective material powder may be made of at least one of BaSO ₄ , TiO ₂ , Al ₂ O ₃ , and MgO.

  In the scintillator array of the present invention, the average particle size of the powder of the reflective material may be 1 μm or less.

  In the scintillator array of the present invention, the resin may be composed of at least one of acrylic resin, polyvinyl alcohol, silicone resin, and epoxy resin.

  In the scintillator array of the present invention, the scintillator crystal may have a fluorescence emission wavelength of 400 nm or less.

  The scintillator array of the present invention may be manufactured by the array manufacturing method of the present invention.

  The various components of the present invention do not necessarily have to be independent of each other. A plurality of components are formed as a single member, and a single component is formed of a plurality of members. It may be that a certain component is a part of another component, a part of a certain component overlaps with a part of another component, or the like.

  In the array manufacturing method of the present invention, since the plurality of scintillator crystals are arranged two-dimensionally and then the mixed liquid filled in the gap is solidified, the positional accuracy of the plurality of scintillator crystals is good. In addition, there is no need to arrange a plurality of scintillator crystals in which an outer surface is coated with a reflective material or a reflective tape, and there is no need to press-fit a plurality of scintillator crystals into a storage container. There is no need to cut the scintillator crystal to form a scintillator array. For this reason, a scintillator array with good alignment accuracy and detection accuracy of the scintillator crystals can be easily manufactured without damaging the outer surface of the scintillator crystals arranged in an array.

  An embodiment of the present invention will be described below with reference to the drawings. The scintillator array 100 of the present embodiment is composed of a plurality of scintillator crystals 110 that generate fluorescence internally when radiation enters.

  More specifically, as shown in FIG. 1 and FIG. 2, the scintillator array 100 of the present embodiment includes a plurality of elongated scintillators that are two-dimensionally arranged at predetermined intervals in a direction orthogonal to the longitudinal direction. A crystal 110 and a resin 120 in which a powder of a reflecting material (not shown) is mixed and filled in a space between the plurality of scintillator crystals 110.

The reflecting material powder is made of, for example, BaSO ₄ and has an average particle size of 1 μm or less. The resin 120 is made of, for example, an acrylic resin. The scintillator crystal 110 has a fluorescence emission wavelength of 400 nm or less.

  Next, an array manufacturing system and an array manufacturing method for manufacturing the scintillator array 100 as described above will be described in order below. The array manufacturing system according to the present embodiment includes a crystal holding mechanism that holds a plurality of elongated scintillator crystals 110 in a two-dimensional manner at a predetermined interval in a direction orthogonal to the longitudinal direction, and a gap between the arranged scintillator crystals 110. And a mixed solution filling mechanism for filling a mixed solution obtained by mixing the resin 120 and the solvent, and a reduced pressure removing mechanism for solidifying the resin 120 by removing the solvent from the mixed solution under reduced pressure (not shown).

  As shown in FIG. 3, the crystal holding mechanism includes a flat plate-like lower end holding jig 210 that holds lower ends of a plurality of scintillator crystals 110 arranged in a state where the longitudinal direction is parallel to the vertical direction, and as shown in FIG. In addition, the upper end holding jig 220 for holding the upper ends of the plurality of scintillator crystals 110 with the lower ends held therein and the plurality of scintillator crystals 110 in a state of being in close contact with at least the lower end holding jig 210 as shown in FIG. Resin mold 230.

  In the array manufacturing method of manufacturing the scintillator array 100 using the array manufacturing system as described above, a plurality of elongated scintillator crystals 110 that generate fluorescence at a wavelength of 400 nm or less inside when radiation is incident are formed.

  Next, as shown in FIGS. 3 to 5, a plurality of scintillator crystals 110 are two-dimensionally arranged at predetermined intervals in a direction orthogonal to the longitudinal direction. Next, the mixed liquid in which the resin 120 and the solvent are mixed is filled in the gaps between the plurality of arranged scintillator crystals 110.

  More specifically, as shown in FIG. 3, a plurality of insertion holes are formed in the lower end holding jig 210 at predetermined intervals in order to insert the scintillator crystal 110. The scintillator crystal 110 is inserted into the insertion hole.

  Further, as shown in FIG. 4, the upper part of the scintillator crystal 110 is fixed by using an upper end holding jig 220 in which wires are assembled in a lattice shape, and the periphery is surrounded by a resin mold 230 as shown in FIG.

Next, a mixture of BaSO ₄ reflector powder having an average particle diameter of 1 μm or less, the resin 120 and a solvent is filled in the gaps of the scintillator crystals 110. The composition ratio of the mixed liquid is set such that the weight part of the resin 120 is 5 or less with respect to the weight part 100 of the reflecting material.

  When this filling is completed, the reflective layer is formed by removing the solvent under reduced pressure and solidifying the resin. Thereafter, the resin mold 230, the lower end holding jig 210, and the upper end holding jig 220 are removed. As shown in FIG. 1, the scintillator array 100 is completed by applying the mixed liquid to the bottom surface of the scintillator array 100 and drying it.

  According to the array manufacturing method using the array manufacturing system of the present embodiment, the plurality of scintillator crystals 110 are two-dimensionally arranged and then the mixed liquid filled in the gap is solidified. Good positional accuracy.

  Further, it is not necessary to arrange a plurality of scintillator crystals 110 coated with a reflective material or a reflective tape on the outer surface in an array, and there is no need to press-fit a plurality of scintillator crystals 110 into a storage container. There is no need to cut the large scintillator crystal 110 to form the scintillator array 100.

  For this reason, the scintillator array 100 with good alignment accuracy and detection accuracy of the scintillator crystals 110 can be easily manufactured without damaging the outer surface of the scintillator crystals 110 arranged in an array.

  In addition, since the powder of the reflective material is mixed in the mixed solution, the plurality of scintillator crystals 110 can be fixed in an array, and at the same time, the outer surface of the plurality of scintillator crystals 110 can be used as a reflective surface.

In particular, the scintillator crystal 110 emits light at a wavelength of 400 nm or less, and the reflector powder is made of BaSO ₄ . For this reason, the reflectance of a reflection layer can be 95% or more in wavelength 300-400 nm.

  In addition, it is easy to adjust the viscosity of the liquid mixture containing the reflective material powder to ensure fluidity by mixing the reflective material powder, the polymer binder, and the solvent. In addition, since the average particle diameter of the reflector powder is 1 μm or less, the mixed liquid can be satisfactorily filled in the gaps of the scintillator crystals 110.

  Further, although precision is required for processing of the array manufacturing system, the array manufacturing system itself is not a constituent element of the scintillator array 100 and can be used any number of times once manufactured.

  For this reason, by using the array manufacturing system of the present embodiment, it is possible to easily mass-produce the scintillator array 100 with good alignment accuracy and detection accuracy of the scintillator crystals 110.

  The inventor actually made a prototype of the scintillator array 100 using the above-described array manufacturing system. This will be briefly described below. First, a 2 × 2 × 15 mm Pr: LuAG crystal is formed as the scintillator crystal 110, and the resin mold 230, the lower end holding jig 210, and the upper end holding jig 220 are used to form 8 × 7 pixels with a 0.15 mm gap. It was fixed to become.

Next, after injecting the mixed solution prepared as described above into the resin mold 230, the Pr: LuAG crystal is put together with the resin mold 230 into the decompression device, and the decompression device is evacuated to 1.0 × 1010. ^The pressure was reduced to ⁵ Pa or less.

  The liquid mixture has fluidity, and flows to the deep part of the gap between the scintillator crystals 110, and the solvent component is vaporized and degassed by vacuum. By these operations, a reflective layer in which the reflector powder is densely filled is formed in the gap between the scintillator crystals 110. After forming the reflective layer, the Pr: LuAG crystal was taken out from the decompression device, and the resin mold 230, the lower end holding jig 210, and the upper end holding jig 220 were removed.

Next, as shown in FIG. 6, an array block using a fluororesin tape, an ESR film, and a BaSO ₄ reflector was adhered to a position-sensitive photomultiplier tube (H8500) and irradiated with ¹³⁷ Csγ rays. .

  A two-dimensional map at this time is shown in FIG. Table 1 shows the relationship between the reflective material and the light emission amount.

Table 2 shows the amount of light emission and energy resolution when an array block using each reflecting material containing BaSO ₄ powder having an average particle size of 100 μm, 1 μm, and 130 nm is bonded to a photomultiplier tube and irradiated with ¹³⁷ Csγ rays. Show.

As shown in Table 2, the array block using each reflecting material containing each BaSO ₄ powder having an average particle size of 130 nm had the maximum light emission amount of the scintillator crystal 110 of 15 ch, and the position discrimination characteristics were the best.

  Table 3 also shows the relationship between the reflective material and the light emission amount.

表３のように、反射材としてＢａＳＯ_４が好適であることが確認された。

As shown in Table 3, it was confirmed that BaSO ₄ was suitable as the reflecting material.

  The present invention is not limited to the present embodiment, and various modifications are allowed without departing from the scope of the present invention. For example, in the above embodiment, the composition, size, and the like of the scintillator crystal 110 are specifically exemplified.

Further, in the above embodiment exemplifies the case where powder of reflective material is made of BaSO _4. However, as the powder of the reflecting material, TiO ₂ , Al ₂ O ₃ , MgO, a mixture thereof, or the like can be used.

  Furthermore, it illustrated that resin 120 consists of an acrylic resin. However, as the resin 120, polyvinyl alcohol, silicone resin, epoxy resin, a mixture thereof, or the like can be used.

  Further, the size of the insertion hole for the scintillator crystal 110 of the lower end holding jig 210, the size of the lattice of the upper end holding jig 220, and the interval between the scintillator crystals 110 are the size of the scintillator crystal 110 and the size used. It is determined by the diameter of the wire.

  Needless to say, the above-described embodiment and a plurality of modifications can be combined within a range in which the contents do not conflict with each other. Further, in the above-described embodiments and modifications, the structure of each part has been specifically described, but the structure and the like can be changed in various ways within a range that satisfies the present invention.

It is a typical perspective view which shows the external appearance of the scintillator array of embodiment of this invention. It is a typical perspective view which shows the internal structure of a scintillator array. It is a typical disassembled perspective view which shows the process of an array manufacturing method. It is a typical disassembled perspective view which shows the process of an array manufacturing method. It is a typical perspective view which shows the process of an array manufacturing method. It is a typical perspective view which shows the experimental method in the scintillator array made as an experiment. It is a characteristic view which shows the experimental result in the scintillator array made as an experiment.

Explanation of symbols

100 scintillator array 110 scintillator crystal 120 resin 210 lower end holding jig 220 upper end holding jig 230 resin mold

Claims (15)

An array manufacturing method for manufacturing a scintillator array having a plurality of scintillator crystals,
Forming a plurality of elongated scintillator crystals that generate fluorescence inside when radiation is incident thereon,
A plurality of the scintillator crystals are arranged two-dimensionally at a predetermined interval in a direction orthogonal to the longitudinal direction,
By surrounding a plurality of the scintillator crystals arranged with a mold, and filling a mixed solution in which a resin and a solvent are mixed into a region surrounded by the mold, a plurality of gaps and a plurality of scintillator crystals are filled. the mixture was filled around the scintillator crystal,
In Rukoto the solvent to coagulate the resin was removed under reduced pressure from the mixture, scintillator solidified the resin, together with fills the gaps of a plurality of the scintillator crystals, and surrounds the periphery of a plurality of the scintillator crystals An array manufacturing method comprising forming an array.   The array manufacturing method according to claim 1, wherein a powder of a reflective material is mixed in the mixed solution. The array manufacturing method according to claim 2, wherein the reflective material powder is made of at least one of BaSO ₄ , TiO ₂ , Al ₂ O ₃ , and MgO.   The array manufacturing method according to claim 2 or 3, wherein an average particle size of the powder of the reflecting material is 1 µm or less.   5. The array manufacturing method according to claim 2, wherein the composition ratio of the mixed liquid is 5 parts by weight or less of the resin with respect to 100 parts by weight of the reflective material.   6. The array manufacturing method according to claim 1, wherein the resin is made of at least one of acrylic resin, polyvinyl alcohol, silicone resin, and epoxy resin.   The array manufacturing method according to claim 1, wherein the scintillator crystal that generates the fluorescence having an emission wavelength of 400 nm or less is formed. The process of filling the mixed solution in the region surrounded by the mold is
The array manufacturing method according to any one of claims 1 to 7, wherein the array manufacturing method is performed in a state where the lower end of the scintillator crystal is held so as to suppress the scintillator crystal from moving in a direction orthogonal to the longitudinal direction. The process of filling the mixed solution in the region surrounded by the mold is
The array manufacturing method according to any one of claims 1 to 8, which is performed in a state in which an upper end of the scintillator crystal is held so as to prevent the scintillator crystal from moving in a direction perpendicular to the longitudinal direction. A resin of a predetermined shape mixed with powder of the reflective material;
  A plurality of elongated scintillator crystals that generate fluorescence inside when radiation is incident thereon, and
  The plurality of scintillator crystals are arranged two-dimensionally at a predetermined interval in a direction orthogonal to the longitudinal direction,
  The scintillator array, wherein the resin has a portion that fills gaps between the plurality of scintillator crystals and a portion that surrounds the periphery of the plurality of scintillator crystals, and these two portions are integrally formed. 11. The scintillator array according to claim 10 , wherein the reflective material powder is made of at least one of BaSO ₄ , TiO ₂ , Al ₂ O ₃ , and MgO. The scintillator array according to claim 10 or 11 , wherein an average particle diameter of the powder of the reflecting material is 1 µm or less. The scintillator array according to any one of claims 10 to 12 , wherein the resin is made of at least one of acrylic resin, polyvinyl alcohol, silicone resin, and epoxy resin. The scintillator array according to any one of claims 10 to 13 , wherein the scintillator crystal has an emission wavelength of the fluorescence of 400 nm or less. The scintillator array according to any one of claims 10 to 14 , wherein the scintillator array is manufactured by the array manufacturing method according to any one of claims 1 to 9 .

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