Patent Publication Number: US-2011056618-A1

Title: Method of manufacturing radiation detector

Description:
TECHNICAL FIELD  
     This invention relates to a method of manufacturing a radiation detector having a scintillator, a light guide, and a light detector that are optically coupled to one another in turn. 
     BACKGROUND ART  
     In medical fields, emission computed tomography (ECT: Emission Computed Tomography) apparatus is used that detects radiation (such as gamma rays) emitted from radiopharmaceutical that is administered to a subject and is localized to a site of interest for obtaining sectional images of the site of interest in the subject showing radiopharmaceutical distributions. Typical ECT apparatus includes, for example, a PET (Positron Emission Tomography) device and an SPECT (Single Photon Emission Computed Tomography) device. 
     A PET device will be described by way of example. The PET device has a radiation detector ring with block radiation detectors arranged in a ring shape. The detector ring is provided for surrounding a subject, and allows detection of radiation that is transmitted through the subject. 
     Such radiation detector arranged in the detector ring of the PET device is often equipped that allows position discrimination in a depth direction of a scintillator provided in the radiation detector for improved resolution. Particularly, such radiation detector is used, for example, in a PET device set for animals.  FIG. 26  is a perspective view showing a configuration of a conventional radiation detector. Such radiation detector  50  has scintillation counter crystal layers  52 A,  52 B,  52 C, and  52 D in which scintillation counter crystals  51  of rectangular solid are accumulated in two dimensions, a light detector  53  with a function of position discrimination that detects fluorescence irradiated from each of the scintillation counter crystal layers  52 A,  52 B,  52 C, and  52 D, and a light guide  54  that receives fluorescence. Here, each of the scintillation counter crystal layers  52 A,  52 B,  52 C, and  52 D is laminated in a z-direction to form a scintillator  52  that converts incident radiation into fluorescence. The radiation detector  50  of such a configuration is disclosed in, for example, Patent Literature 1. 
     The conventional radiation detector  50  is manufactured by forming the scintillator  52 , the light detector  53 , and the light guide  54  individually, stacking them in series, and then adhering to one another. The scintillator  52  of the conventional configuration is manufactured by firstly arranging scintillation counter crystals  51  three-dimensionally, and then by penetrating a thermosetting resin into gaps between adjacent scintillation counter crystals  51  and heating the thermosetting resin for hardening. The manufactured scintillator  52  has a film excessive resin adhering on a surface thereof. This is to be removed after the thermosetting resin hardens. 
     The light guide  54  of the conventional configuration is manufactured by pouring the thermosetting resin into a mold having a rectangular recess, and then heating it. A meniscus appears on a surface of the liquid thermosetting resin with which the rectangular recess is filled. Thus, a surface of the light guide  54  that is optically coupled to the scintillator  52  is not flat merely by removing the mold from the light guide  54 . Accordingly, the surface of the light guide  54  that receives fluorescence is ground and polished to form the light guide  54  capable of installation on the radiation detector  50 . 
     Thereafter, the scintillator  52  and the light guide  54  are coupled via an optical adhesive. As noted above, the radiation detector  50  is manufactured. Here, the thermosetting resin used for the light guide  54  sometimes differs from that used for the scintillator  52 . Accordingly, in the method of manufacturing the conventional radiation detector  50 , the scintillator  52  and the light guide  54  are not manufactured collectively 
     [Patent Literature 1] 
     Japanese Patent Publication No. 2004-279057 
     DISCLOSURE OF THE INVENTION  
     Problem To Be Solved By the Invention  
     However, the method of manufacturing the conventional radiation detector has the following drawbacks. That is, the problem is that the method of manufacturing the conventional radiation detector has many numbers of processes, and thus is complicated. The scintillator and light guide in the conventional radiation detector is manufactured by hardening the different types of thermosetting resins. Thereafter, one surface of the light guide  54  that is ground and polished is contacted on one surface of the scintillator  52  with the excessive thermosetting resin already removed therefrom. 
     Where the step of hardening the thermosetting resins and the step of optically coupling the scintillator  52  and the light guide  54  may be performed en bloc with different types of thermosetting resins used for the scintillator  52  and the light guide  54 , the step may be omitted such as a processing of one surface of the scintillator  52  or the light guide  54  and a processing of optically coupling to each other. As a result, manufacture efficiency of the radiation detector may be enhanced. 
     The number of the radiation detectors arranged in one piece of the radiation tomography apparatus is considerable, since the radiation detectors form a detector ring. Consequently, it becomes important to suppress manufacturing costs of the radiation detectors for provision of radiation tomography apparatus of low price. 
     This invention has been made regarding the state of the art noted above, and its object is to provide a method of manufacturing a radiation detector having suppressed number of steps in which a step of hardening hardening resins and a step of optically coupling a scintillator and a light guide are performed en bloc even when different types of hardening resins are used for the scintillator and the light guide. 
     Means For Solving the Problem  
     This invention is constituted as stated below to achieve the above object. A method of manufacturing a radiation detector having a scintillator with scintillation crystal layers converting radiation into fluorescence being joined to one another, a light guide that receives fluorescence, and a light detector that detects fluorescence optically coupled to one another. The method includes the steps of manufacturing the light guide through hardening of a first hardening resin; forming a temporary assembly prior to joining of the scintillation counter crystals through arrangement of the scintillation counter crystals; arranging the temporary assembly in a recess of a receptacle for joint that is formed toward a vertical direction; pouring a second hardening resin prior to hardening into the recess to sink the temporary assembly thereinto; placing the light guide over one surface of the temporary assembly exposed from the recess, and interposing the second hardening resin in a gap between the light guide and the one surface of the temporary assembly; hardening the second hardening resin to manufacture the scintillator with the scintillation counter crystals joined to one another and to join the scintillator and the light guide; and optically coupling the light guide and the light detector. 
     Operation and Effect  
     According to this invention, the method of manufacturing the radiation detector may be provided in which the step of hardening the second hardening resin and the step of optically coupling the scintillator and the light guide are performed en bloc. In other words, the scintillator of this invention is manufactured by forming the temporary assembly having the scintillation counter crystals arranged therein, and penetrating gaps between the scintillation counter crystals with the second hardening resin, and then hardening it. According to this invention, the scintillator is not manufactured merely by hardening the second hardening resin, but the light guide is placed so as to cover the top face of the temporary assembly that sinks into the second hardening resin prior to hardening. As a result, the second hardening resin is to be interposed in a gap between the top face of the temporary assembly and one surface of the light guide directed downward in the vertical direction. According to this invention, the second hardening resin is hardened while the light guide is placed on the temporary assembly. Consequently, the second hardening resin that penetrates the gaps between the scintillation counter crystals constituting the temporary assembly hardens to join the scintillation counter crystals to one another. Moreover, the second hardening resin interposed in the gap between the top face of the temporary assembly and the light guide and penetrating the top surface of the temporary assembly hardens, thereby joining the scintillator and the light guide. Therefore, the configuration of this invention may realize manufacturing of the radiation detector with no complicated process of forming the scintillator and the light guide individually and coupling them with the optical adhesive. 
     It is more desirable that the step of placing a light guide jig is further included that places the light guide jig for determining a relative position of the light guide of the foregoing configuration and the temporary assembly in the receptacle for joint. 
     Operation and Effect  
     According to the foregoing configuration, accurate joining of the scintillator and the light guide may be ensured. Specifically, when the light guide is placed so as to cover the top face of the temporary assembly, the light guide and the temporary assembly are relatively positioned through contacting of the light guide to the light guide jig. The light guide jig is placed in the receptacle for joint with the temporary assembly arranged therein. Consequently, the light guide and the temporary assembly are relatively positioned via the receptacle for joint and the light guide jig. The relative position of the light guide and the temporary assembly is always fixed for every manufacture of the radiation detector. Accordingly, the relative position of the light guide and the scintillator is to be reproduced for every manufacture of the radiation detector. 
     The light guide jig of the foregoing configuration has an L-shape that extends in a first direction and a second direction seen from the vertical direction. It is more preferable that a relative position of the light guide and the temporary assembly are determined with respect to the first direction and the second direction. 
     Operation and Effect  
     According to the foregoing configuration, accurate joining of the scintillator and the light guide may be ensured. Specifically, where the light guide jig has an L-shape, the light guide may be contacted to the light guide jig in two directions of the first direction and the second direction that is perpendicular thereto. Such configuration may realize relative positioning of the light guide with respect to the temporary assembly in two directions of the first direction and second direction perpendicular thereto. Accordingly, one relative position of the light guide with respect to the temporary assembly is to be determined naturally. As noted above, the foregoing configuration may ensure accurate joining of the scintillator and the light guide. 
     This invention may be configured as stated below in order to achieve the above object. A method of manufacturing a radiation detector having a scintillator with scintillation crystal layers converting radiation into fluorescence being joined to one another, a light guide that receives fluorescence, and a light detector that detects fluorescence optically coupled to one another. The method may include the steps of manufacturing the scintillator by joining the scintillation counter crystals to one another through hardening of a second hardening resin; pouring a first hardening resin prior to hardening to a vertical opening of a mold; placing the scintillator so as to cover the opening, whereby the first hardening resin penetrates one surface of the scintillator directed downward in the vertical direction; hardening the first hardening resin to manufacture the light guide and to join the scintillator and the light guide; and optically coupling the light guide and the light detector. 
     Operation and Effect  
     With the foregoing configuration, the method of manufacturing the radiation detector may be provided in which the step of hardening the first hardening resin and the step of optically coupling the scintillator and the light guide are performed en bloc. Specifically, the light guide of the foregoing configuration is manufactured by pouring the first hardening resin into the mold and hardening it. According to the foregoing configuration, the light guide is not manufactured merely by hardening the first hardening resin, but the scintillator is placed so as to cover the opening of the mold filled with the first hardening resin prior to hardening. As a result, the first hardening resin is to penetrate one surface of the scintillator directed downward in the vertical direction. Moreover, according to the foregoing configuration, the first hardening resin hardens while the light guide is placed on the scintillator. Consequently, the first hardening resin hardens to form the light guide, and moreover, the first hardening resin that penetrates the one surface of the scintillator directed downward in the vertical direction hardens, thereby joining the scintillator and the light guide. Therefore, the foregoing configuration may realize manufacturing of the radiation detector with no complicated process of forming the scintillator and the light guide individually and coupling them with the optical adhesive. 
     The step may further be included of placing a scintillator jig on the mold for determining a relative position of the scintillator and the light guide. 
     Operation and Effect  
     According to the foregoing configuration, accurate joining of the scintillator and the light guide may be ensured. Specifically, when the first hardening resin penetrates the one surface of the scintillator directed downward in the vertical direction, the scintillator and the opening of the mold are relatively positioned through contacting of the scintillator to the scintillator jig. The scintillator jig is placed in the mold having the opening for forming the light guide. Consequently, the scintillator and the light guide are relatively positioned via the mold and the scintillator jig. The relative position of the scintillator and the opening of the mold is always fixed for every manufacture of the radiation detector. Accordingly, the relative position of the scintillator and the light guide is to be reproduced for every manufacture of the radiation detector. 
     The scintillator jig of the foregoing configuration has an L-shape that extends in a first direction and a second direction seen from the vertical direction. It may be characterized that a relative position of the scintillator and the light guide are determined with respect to the first direction and the second direction. 
     Operation and Effect  
     According to the foregoing configuration, accurate joining of the light guide and the scintillator may be ensured. Specifically, where the scintillator jig is L-shaped, the scintillator may be contacted to the scintillator jig in two directions of the first direction and the second direction perpendicular thereto when the first hardening resin penetrates the one surface of the scintillator directed downward in the vertical direction. Such configuration may realize relative positioning of the scintillator with respect to the opening of the mold in the first direction and second direction perpendicular thereto. Accordingly, one relative position of the scintillator with respect to the light guide is to be determined naturally. As noted above, the foregoing configuration may ensure accurate joining of the scintillator and the light guide. 
     The scintillator of the foregoing configuration may have the scintillation counter crystals arranged in a three-dimensional array. 
     Operation and Effect  
     According to the foregoing configuration, a radiation detector may be provided that allows three-dimensional discrimination of fluorescence generation positions in the scintillator. Such configuration may ensure more accurate mapping of radiation generation positions when the radiation detectors according to this invention are arranged in the radiation tomography apparatus. 
     The first hardening resin and the second hardening resin in the foregoing configuration may be selected from materials different from each other. 
     Operation and Effect  
     According to the foregoing configuration, a radiation detector may be provided that allows varying in setting in accordance with various applications. Suitable materials for the first hardening resin for forming the light guide and the second hardening resin for forming the scintillator through joining of the scintillation counter crystals may vary depending on a size of the radiation detector, a property of radiation to be detected, or a material of the scintillation counter crystal, etc. The foregoing configuration may realize selection of the first hardening resin and the second hardening resin from the materials different from each other, which results in provision of various types of radiation detectors. 
     Effect of the Invention  
     According to this invention, the method of manufacturing the radiation detector may be provided in which the step of hardening the hardening resin and the step of optically coupling the scintillator and the light guide are performed en bloc. Here, both steps of manufacturing the scintillator and the light guide include the step of hardening the hardening resin. Giving attention to this, this invention has no configuration of optically coupling the light guide and the scintillator after manufacturing independently the light guide or the scintillator. Instead of this configuration, this invention has a configuration of manufacturing either the light guide or the scintillator and then placing either the manufactured light guide or the scintillator on the incomplete scintillator or light guide. Such configuration allows one surface of the light guide or the scintillator to be penetrated with the hardening resin prior to hardening. When the hardening resin hardens under this state, the hardening resin that penetrates the one surface of the light guide or the scintillator is to harden, which results in joining of the light guide and the scintillator. 
     As noted above, the method of manufacturing the radiation detector may be provided in which the step of hardening the hardening resin to manufacture the scintillator or the light guide and the step of optically coupling the scintillator and the light guide are performed en bloc. Accordingly, the radiation detector may be manufactured with no complicated process of forming the scintillator and the light guide individually and coupling them with the optical adhesive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a perspective view of a radiation detector according to Embodiment 1. 
         FIG. 2  is a plan view showing a configuration of a light guide according to Embodiment 1. 
         FIG. 3  is a plan view showing processes of discriminating fluorescence generating positions of the radiation detector according to Embodiment 1. 
         FIG. 4  is a perspective view showing a configuration of an optical member frame according to Embodiment 1. 
         FIG. 5  is a flow chart showing a method of manufacturing the radiation detector according to Embodiment 1. 
         FIG. 6  is a perspective view showing a step of manufacturing the optical member frame according to Embodiment 1. 
         FIG. 7  is a perspective view showing a configuration of a mold according to Embodiment 1. 
         FIG. 8  is a sectional view showing a step of inserting the optical member frame and a step of pouring a first hardening resin according to Embodiment 1. 
         FIG. 9  is a perspective view showing a configuration of a receptacle for arrangement according to Embodiment 1. 
         FIGS. 10 to 16  are sectional views each showing a method of manufacturing a scintillator according to Embodiment 1. 
         FIG. 17  is a sectional view showing a step of pouring a second hardening resin and a step of placing a temporary assembly according to Embodiment 1. 
         FIG. 18  is a sectional view showing the step of placing the temporary assembly according to Embodiment 1. 
         FIG. 19  is a perspective view showing a step of placing a light guide jig and a step of placing a light guide according to Embodiment 1. 
         FIG. 20  is a plan view showing the step of placing the light guide according to Embodiment 1. 
         FIG. 21  is a sectional view showing the step of placing the light guide according to Embodiment 1. 
         FIG. 22  is a flow chart showing a method of manufacturing a radiation detector according to Embodiment 2. 
         FIG. 23  is a perspective view showing the method of manufacturing the radiation detector according to Embodiment 2. 
         FIG. 24  is a plan view showing a step of placing a light guide according to Embodiment 2. 
         FIG. 25  is a sectional view showing the step of placing the light guide according to Embodiment 2. 
         FIG. 26  is a perspective view showing a configuration of a conventional radiation detector. 
     
    
    
     DESCRIPTION OF REFERENCES  
       1  radiation detector 
       2  scintillator 
       2   p  temporary assembly 
       3  light detector 
       4  light guide 
       8  thermosetting resin (first hardening resin) 
       11  scintillation counter crystal 
       20  receptacle for joint 
       20   a  recess 
       21  optical adhesive (second hardening resin) 
       22  scintillator jig 
       24  light guide jig 
     BEST MODE FOR CARRYING OUT THE INVENTION  
     Description will be give hereinafter of a method of manufacturing a radiation detector according to this invention with reference to the drawings. 
     Embodiment 1  
     Prior to description of a method of manufacturing a radiation detector according to Embodiment 1, a configuration is to be described of a radiation detector  1  according to Embodiment 1.  FIG. 1  is a perspective view of the radiation detector according to Embodiment 1. As shown in  FIG. 1 , the radiation detector  1  according to Embodiment 1 includes a scintillator  2  that is formed of scintillation counter crystal layers each laminated in order of a scintillation counter crystal layer  2 D, a scintillation counter crystal layer  2 C, a scintillation counter crystal layer  2 B, and a scintillation counter crystal layer  2 A, in turn, in a z-direction, a photomultiplier tube (hereinafter referred to as a light detector)  3  having a function of position discrimination that is provided on an undersurface of the scintillator  2  for detecting fluorescence emitted from the scintillator  2  for receiving fluorescence, and a light guide  4  arranged between the scintillator  2  and the light detector  3 . Consequently, each of the scintillation counter crystal layers is laminated in a direction toward the light detector  3 . In other words, the scintillator  2  has scintillation counter crystals arranged in a three-dimensional array. Here, the z-direction corresponds to the vertical direction in this invention. 
     Here, the scintillation counter crystal layer  2 A corresponds to an incident surface of radiation in the scintillator  2 . Each of the scintillation counter crystal layers  2 A,  2 B,  2 C, and  2 D is optically coupled, and includes a transparent material t of a hardened thermosetting resin between each of the layers. A thermosetting resin composed of a silicone resin may be used for the transparent material t. The scintillation counter crystal layer  2 A corresponds to a receiver of the gamma rays emitted from a radioactive source. The scintillation counter crystals in a block shape are arranged in a two-dimensional array with thirty-two numbers of the scintillation counter crystals in an x-direction and thirty-two numbers of the scintillation counter crystals in a y-direction relative to a scintillation counter crystal a (1, 1). That is, the scintillation counter crystals from a (1, 1) to a (1, 32) are arranged in the y-direction to form a scintillator crystal array. Thirty-two numbers of the scintillator crystal arrays are arranged in the x-direction to form a scintillation counter crystal layer  2 A. Here, as for the scintillation counter crystal layers  2 B,  2 C, and  2 D, thirty-two numbers of the scintillator counter crystals are also arranged in the x-direction and the y-direction in a matrix in a two-dimensional array relative to a scintillation counter crystal b (1, 1), c (1, 1), and d (1, 1), respectively. In each of the scintillation counter crystal layers  2 A,  2 B,  2 C, and  2 D, the transparent material t is also provided between the scintillation counter crystals adjacent to each other. Consequently, each of the scintillation counter crystals is to be enclosed with the transparent material t. The transparent material t has a thickness around 25 μm. The x-direction and the y-direction correspond to the first direction and the second direction, respectively, in this invention. A gamma ray corresponds to radiation in this invention. 
     First reflectors r that extend in the x-direction and second reflectors s that extend in the y-direction are provided in the scintillation counter crystal layers  2 A,  2 B,  2 C, and  2 D provided in the scintillator  2 . Both reflectors r and s are inserted in a gap between the arranged scintillation counter crystals. 
     The scintillator  2  has scintillation counter crystals suitable for detection of gamma rays in a three-dimensional array. That is, the scintillation counter crystal is composed of Ce-doped Lu 2(1-X) Y 2 XSiO 5  (hereinafter referred to as LYSO.) Each of the scintillation counter crystals is, for example, a rectangular solid having a length of 1.45 mm in the x-direction, a width of 1.45 mm in the y-direction, and a height of 4.5 mm regardless of the scintillation counter crystal layer. The scintillator  2  has four side end faces that are covered with a reflective film not shown. The light detector  3  is multi-anode type, and allows position discrimination of incident fluorescence in the x and y. 
     The light guide  4  is provided for guiding fluorescence emitted in the scintillation  2  into the light detector  3 . Consequently, the light guide  4  is optically coupled to the scintillator  2  and the light detector  3 . The configuration of the light guide  4  will be described.  FIG. 2  is a plan view showing a configuration of the light guide according to Embodiment 1. As shown in  FIG. 2 , the light guide  4  has thirty-one elongated first optical members  4   a  extending in the x-direction that are arranged in the y-direction so as to pass through the light guide  4  in the z-direction. Moreover, the light guide  4  has thirty-one elongated second optical members  4   b  extending in the y-direction that are arranged in the x-direction so as to pass through the light guide  4  in the z-direction. The first optical members  4   a  and the second optical members  4   b  form a lattice optical member frame  6  as shown in  FIG. 4 , when seen as a whole the light guide  4 . A resin block  4   c  that transmits light is inserted into each section that the optical member frame  6  divides (see  FIG. 2 .) The resin block  4   c  is also provided on the side end of the light guide  4 . Consequently, each of the first optical members  4   a  and the second optical members  4   b  is interposed between the resin blocks  4   c.  Here, the resin block  4   c  has a same arrangement pitch as the scintillation counter crystal layers  2 A,  2 B,  2 C, and  2 D. As a result, each of the resin blocks  4   c  and scintillation counter crystals d that form the scintillation counter crystal layer  2 D is combined by one to one. The configuration of the optical member frame  6  will be described in detail hereinafter. Both of the first optical member and the second optical member is preferably an ESR film (Sumitomo 3M) as a reflector having a thickness of around 65 μm. 
     The first optical member  4   a  and the second optical member  4   b  are composed of a reflector that reflects fluorescence emitted in the scintillator  2 . Consequently, the optical member frame  6  (see  FIG. 4 ) does not permit fluorescence that enters from the scintillator  2  into the light guide  4  to spread in the xy-directions. Fluorescence enters into the light detector  3 . Accordingly, the light guide  4  allows fluorescence to receive from the scintillator  2  to the light detector  3  while maintaining a position where fluorescence is generated in the xy-directions. 
     Description will be given of a process of discriminating a fluorescence generating position in the z-direction in the radiation detector  1  according to Embodiment 1. As shown in  FIG. 3 , each of the scintillation counter crystal layers  2 A,  2 B,  2 C, and  2 D that form the scintillator  2  differs from one another in inserting positions of the first reflectors r and the second reflectors s.  FIG. 3  shows one end of the scintillator  2  according to Embodiment 1, and (a), (b), (c) and (d) therein illustrate configurations of the scintillation counter crystal layers  2 A,  2 B,  2 C, and  2 D, respectively. Directing attention to the scintillation counter crystals a (2, 2), b (2, 2), c (2, 2), and d (2, 2) on (2, 2), all of the four have two sides adjacent to each other that are covered with the reflectors. The scintillation counter crystals on (2, 2) differ from one another in direction where the reflectors are provided. Thus, four scintillation counter crystals (2, 2), b (2, 2), c (2, 2), and d (2, 2) that are identical to one another in the xy-positions have different optical conditions. The fluorescence generated in the scintillation counter crystal reaches the light detector  3  while spreading in the xy-directions. Providing the reflectors leads to addition of directivity to the spreading. Moreover, comparing fluorescence generated in the four scintillation counter crystals having the same xy-positions, they differ from one another in direction of spreading. That is, differences in position of generating fluorescence in the z-direction in the scintillator  2  are to be converted into differences of fluorescence in the xy-directions. The light detector  3  may detect a slight deviation of the fluorescence in the xy-directions due to the differences in the position in the z-direction, and may calculate the position of generating fluorescence in the z-direction from it. 
     Description will be given of a method of manufacturing such a radiation detector noted above.  FIG. 5  is a flow chart showing a method of manufacturing the radiation detector according to Embodiment 1. As shown in  FIG. 5 , the method of manufacturing the radiation detector according to Embodiment 1 includes the step S 1  of manufacturing an optical member frame that constitutes a light guide, the step S 2  of inserting an optical member frame that inserting the optical member frame  6  into an opening  7   a  of the mold  7 , the step S 3  of pouring a first hardening resin that pours the first hardening resin into the opening  7   a,  and the step S 4  of hardening the light guide that hardens and completes the light guide  4 . The foregoing steps correspond to the step of manufacturing the light guide according to Embodiment 1. 
     The method of manufacturing the radiation detector according to Embodiment 1 includes, subsequent to the step of manufacturing the light guide, the step S 5  of manufacturing a temporary assembly that manufactures the temporary assembly  2   p  having the scintillation counter crystals  11  arranged three-dimensionally; the step S 6  of pouring a second hardening resin that pours the second hardening resin into the recess  20   a  in the receptacle for joint  20 ; the step S 7  of arranging the temporary assembly that arranges the temporary assembly in the recess  20   a;  the step S 8  of placing a light guide jig  24  that places the light guide jig  24  in the receptacle for joint  20 ; the step S 9  of placing a light guide  4  that places the light guide  4  in the receptacle for joint  20 ; the step S 10  of hardening the second hardening resin that hardens the second hardening resin; and the step S 11  of optically coupling the light guide  4  and the light detector  3 . Each of the foregoing will be described hereinafter. 
     &lt;Optical Member Frame Manufacturing Step S 1 &gt; 
       FIG. 6  is a perspective view showing a process of manufacturing the optical member frame according to Embodiment 1. The first optical members  4   a  are arranged in the y-direction for manufacturing the optical member frame  6  according to Embodiment 1. As shown in  FIG. 6 , the first optical member  4   a  is a strip member having a long side direction along the x-direction, a short side direction along the z-direction, and a thickness direction along the y-direction. The first optical member  4   a  has grooves  5   a  along the z-direction. Directing attention to the single optical member  4   a,  the grooves  5   a  are arranged approximately at equal intervals, and have openings provided in a uniform direction with respect to the z-direction. Moreover, as shown in  FIG. 6 , the second optical member  4   b  is a strip member having a long side direction along the y-direction, a short side direction along the z-direction, and a thickness direction along the x-direction. The second optical member  4   b  has grooves  5   b  along the z-direction. 
     Directing attention to the single second optical member  4   b,  the grooves  5   b  are arranged approximately at equal intervals, and have openings provided in a uniform direction with respect to the z-direction. In the optical member frame manufacturing step S 1 , the second optical members  4   b  approach the first optical members  4   a  along the z-direction, thereby fitting the grooves  5   a  and  5   b  of both optical members  4   a  and  4   b  to one another. Thus, the second optical members  4   b  are arranged in the x-direction. The first optical members  4   a  and the second optical members  4   b  are integrated with each other to manufacture the optical member frame  6  having both optical members  4   a,    4   b  arranged in a lattice shape as shown in  FIG. 4 . 
     &lt;Optical Member Frame Insertion Step S 2 &gt; 
     Next, the optical member frame  6  is inserted into the mold  7 . Prior to explanation on the optical member insertion step S 2 , description will be given of the configuration of the mold  7 .  FIG. 7  is a perspective view showing a configuration of the mold according to Embodiment 1. The mold  7  of Embodiment 1 has an opening  7   a  upward in the z-direction. The opening  7   a  is rectangular seen in the z-direction, and has a depth in the z-direction approximately equal to a thickness of the light guide according to Embodiment 1 in the z-direction. The bottom of the opening  7   a  in the z- direction constitutes a close end face  7   b  in a planar shape. The close end face  7   b  may have a pressing plug, etc., formed thereon for removing the hardened light guide  4  from the mold  7 . The mold  7  may be formed of a fluorocarbon resin, for example. 
       FIG. 8  is a sectional view showing the step of inserting the optical member frame and the step of pouring the first hardening resin according to Embodiment 1. As shown in  FIG. 8 , in step S 2  of inserting the optical member frame, the optical member frame  6  is inserted into the opening  7   a  in the z-direction. Here, the opening  7   a  has a length in the x-direction approximately equal to that of the first optical member  4   a  in the long side direction, and a length of the opening  7   a  in the y-direction approximately equal to that of the second optical member  4   b  in the long side direction. As a result, four side ends of the optical member frame  6  contacts the four side end faces of the opening  7   a.  As shown in  FIG. 7 , the optical member frame  6  is inserted into the opening  7   a  of the mold  7 . A release agent is applied in advance to the opening  7   a  of the mold  7  for releasing the hardened thermosetting resin  8 . In  FIG. 8 , the number of the optical members that form the optical member frame  6  is omitted. Likewise, the number of the optical members is to be omitted in the subsequent drawings.  FIG. 8  is a sectional view in the zx-plane. Embodiment 1 has a similar yz-plane in its sectional view. The z-direction here corresponds to the vertical direction in this invention. 
     &lt;First Hardening Resin Pouring Step S 3 &gt; 
     Subsequently, the first liquid thermosetting resin is poured into the opening  7   a.  As shown in  FIG. 8 , the liquid thermosetting resin  8  is poured into the opening  7   a  of the mold  7  in the z-direction. The thermosetting resin  8  prior to hardening is liquid. Thus, the opening  7   a  may readily be filled with the thermosetting resin  8 . Moreover, degassing process is performed in advance to the thermosetting resin  8 . When hardens, the thermosetting resin  8  is changed into a transparent solid resin so as to transmit fluorescence. In the first hardening resin pouring step S 3 , the optical member frame  6  inserted into the opening  7   a  goes down into the thermosetting resin  8 . Accordingly, an upper end of the optical member frame  6  in the z-direction is covered with the thermosetting resin  8 . The thermosetting resin  8  is raised from the opening  7   a  due to a surface tension when seen as a whole the mold  7 . Here, the thermosetting resin corresponds to the first hardening resin in this invention. Specifically, an epoxy resin or acrylic resin may be used, for example. 
     &lt;Light Guide Hardening Step S 4 &gt; 
     Next, the mold  7  is put into an oven maintained at a predetermined temperature for hardening the thermosetting resin  8 . Thereafter, the light guide  4  is drawn out and removed from the mold  7 . The light guide  4  has a hardened meniscus on the surface that receives the light. Accordingly, the surface of the light guide  4  that receives fluorescence is ground and polished to form the light guide  4  capable of installation on the radiation detector  1 . As noted above, the step of manufacturing the light guide in this invention includes the steps of manufacturing the optical member frame, inserting the optical member frame, pouring the first hardening resin, and hardening the light guide. 
     Next, the scintillator  2  according to Embodiment 1 is to be manufactured. Prior to manufacture of the scintillator  2 , a scintillator frame  9  is formed having the first reflectors r extending in the x-direction and arranged in the y-direction and the second reflectors s extending in the y-direction and arranged in the x-direction that are coupled in a lattice shape. Since this manner is the same as that of the foregoing optical member frame  6  for the light guide  4 , explanation thereon is to be omitted. 
     Next, the scintillator frame  9  is inserted into the receptacle for arrangement  10 . Prior to explanation on this step, description will be given to the configuration of the receptacle for arrangement  10 .  FIG. 9  is a perspective view showing a configuration of the receptacle for arrangement  10  according to Embodiment 1. The receptacle for arrangement  10  of Embodiment 1 has an opening  7   a  upward in the z-direction. The opening  10   a  is rectangular seen in the z-direction, and has a depth in the z-direction approximately equal to a thickness of the scintillation crystal layer according to Embodiment 1 in the z-direction. Here, the opening  10   a  has a close end face  10   b  in a planar shape as a bottom thereof in the z-direction. The receptacle for arrangement  10  may be composed of, for example, a fluorocarbon resin. 
       FIG. 10  is a sectional view showing a process of manufacturing the scintillator according to Embodiment 1. As shown in  FIG. 10 , the scintillator frame  9  is inserted into the opening  10   a  in the z-direction. Here, the opening  10   a  has a length in the x-direction approximately equal to that of the first reflector r in the long side direction, and a length in the y-direction approximately equal to that of the second reflector s in the long side direction. As a result, four side ends of the scintillator frame  9  contact the four side end faces of the opening  10   a.  As shown in  FIG. 10 , the scintillator frame  9  is inserted into the opening  10   a  of the receptacle for arrangement  10 . Here in  FIG. 10 , the number of the reflectors that constitute the scintillator frame  9  is omitted. Likewise, the number of the reflectors is to be omitted in the subsequent drawings.  FIGS. 10 to 12  are sectional views in the zx-plane. Embodiment 1 has a similar yz-plane in its sectional view. 
     &lt;Temporary Assembly Manufacturing Step S 5 &gt; 
     Thereafter, the scintillation counter crystals  11  are inserted into the opening  10   a,  whereby the scintillation counter crystal layer  2 A is formed. The opening  10   a  has a depth in the z-direction approximately equal to a height of the scintillation counter crystals  11  in the z-direction. Here, clearance of the adjacent first reflectors r in the scintillator frame  9  is twice a length of the scintillation counter crystals  11  to be inserted in the y-direction. Clearance of the adjacent second reflectors s in the scintillator frame  9  is twice a length of the scintillation counter crystals  11  to be inserted in the x-direction. In this step, the scintillation counter crystals  11  are inserted into each section divided by the scintillator frame  9 . Accordingly, two scintillation counter crystals  11  are inserted between the first reflectors r adjacent to each other, and two scintillation counter crystals  11  are inserted between the second reflectors s adjacent to each other. Consequently, as shown in  FIG. 11 , the opening  10   a  is filled with the scintillation counter crystals  11 . Seen as a whole of the opening  10   a,  thirty-two scintillation counter crystals  11  are arranged two-dimensionally in the xy-directions. 
     Next, as shown in  FIG. 12 , an adhesive tape  12  is joined to an exposed surface of the scintillation counter crystal layer  2 A that is exposed from the opening  10   a  to temporarily join each of the scintillation counter crystals  11 . Thereafter, the scintillation counter crystal layer  2 A is drawn out in the z-direction with the tape joined thereto to remove the scintillation counter crystal layer  2 A from the opening  10   a  of the receptacle for arrangement  10 . 
     Four scintillation counter crystal layers are to be manufactured by repeating each of such steps illustrated in  FIGS. 10 to 12 . Each of the scintillation counter crystals is drawn out from the receptacle for arrangement  10 , and then stacked in the z-direction, whereby the temporary assembly  2   p  is formed having the scintillation counter crystals arranged three-dimensionally. Explanation is to be given on this manner. Prior to explanation on each of the steps concerning such operations, a configuration of a receptacle for stack  15  according to Embodiment 1 is to be described.  FIG. 13  is a sectional view showing a configuration of the receptacle for stack according to Embodiment 1. As shown in  FIG. 13 , the receptacle for stack  15  that is used for stacking the scintillation counter layers has a receptacle body  16 , a top board  17 , and a screw shaft  18 . The receptacle body  16  has a recess  16   a  that is open upward in the z-direction and a screw hole  16   b  formed on the bottom face thereof. The plate top board  17  is provided inside the recess  16   a  so as to close thereof. The top board  17  is supported by one end of the screw shaft  18  that extends in the z-direction. Moreover, a handle not shown is attached on the other end of the screw shaft  18  that turns the screw shaft  18 . The level of the screw shaft  18  that projects in the z-direction is adjusted through operation of the handle. Accordingly, the top board  17  may move vertically in the z-direction. Here, the screw shaft  18  supports the top board  17  so as to rotate freely. The four side surfaces of the recess  16   a  guide the top board  17 , whereby the top board  17  moves vertically in the z-direction without rotating along with the screw shaft  18 .  FIGS. 13 to 18  are sectional views in the zx-plane. Embodiment 1 has a similar yz-plane in its sectional view. 
     Prior to insertion of the scintillation counter layers into the recess  16   a  of the receptacle for stack  15 , a pair of strip films  19  is placed along the recess  16   a.  In  FIG. 13 , the film  19  is placed along the recess  16   a  so as to cover two side surfaces among the four side surfaces of the recess  16   a  that face to the yz-plane and are directed to each other and the top board  17  collectively. Here, merely one film  19  is illustrated in the drawings. Likewise, the other film  19  is placed along the recess  16   a  so as to cover two side surfaces that face to the zx-plane and are directed to each other and the top board  17  collectively. The top board  17  is controlled as to have a distance Dz from the top face thereof to the front end of the receptacle for stack  15 . Here, Dz is no more than the level of the scintillation counter crystal layer in the z-direction. 
     Next, the scintillation counter layer  2 A is inserted into the recess  16   a  of the receptacle for stack  15 . A pair of films  19  is already placed on the recess  16   a,  and thus five surfaces among six surfaces of the scintillation counter crystal layer  2 A are adjacent to the films  19 . The rest one surface is an exposed surface that is exposed from the opening of the recess  16   a.  A direction where the scintillation counter crystal layer  2 A is inserted into the recess  16   a  is selected such that the surface with the tape  12  joined thereto is the exposed surface. 
       FIG. 14  is a sectional view showing a method of manufacturing the temporary assembly according to Embodiment 1. In this step, the tape  12  joined to the scintillation counter layer  2 A is separated from the scintillation counter layer  2 A. Description will be given of a position of the tape  12  in the z-direction. Here, Dz is no more than the level of the scintillation counter crystal layer in the z-direction. Consequently, all spaces formed with the top board  17  and the recess  16   a  are filled again with the scintillation counter crystal layer  2 A. Consequently, the tape  12  fails to enter into the recess  16   a.  The tape  12  may be readily separated with no interference of the receptacle body  16 . 
     Thereafter, as shown in  FIG. 15 , the handle attached on the screw shaft  18  operates to move the top board  17  downward and controls as to have a distance Dz from the top surface of the scintillation crystal layer  2 A to the front end of the receptacle for stack  15 . Then, the scintillation counter crystal layer  2 B is inserted so as to cover the scintillation counter crystal layer  2 A. Such operation is repeated, and consequently the temporary assembly  2   p  having the scintillation counter crystals arranged three-dimensionally is formed inside the recess  16   a  (see  FIG. 16 .) 
     Subsequently, the temporary assembly  2   p  is surrounded with the films  19  by folding opposite ends of the films  19  toward the inside of the recess  16   a,  which is illustrated in  FIG. 16 . As a result, all six surfaces of the temporary assembly  2   p  are covered with the films  19  and two or more scintillation counter crystal layers are surrounded with a pair of films  19  collectively. Moreover, tongues of the films  19  are joined to each other, whereby the scintillation counter crystals  11  are bound firmly with the films  19 . 
     &lt;Second Hardening Resin Pouring Step S 6  and Temporary Assembly Arranging Step S 7 &gt; 
     Next, as shown in  FIG. 17 , the optical adhesive  21  prior to hardening is poured in advance into the recess  20   a  of the receptacle for joint  20  that is formed toward the z. The receptacle for joint  20  has the recess  20   a  of a level approximately equal to that of the scintillator  2  in the z-direction. The recess  20   a  has a U-shaped section along the zx-plane and the xz-plane. The recess  20   a  has a depth approximately equal to the level of the temporary assembly  2   p  in the z-direction. Moreover, the receptacle for joint  20  has two or more slits  20   c  provided in the front surface thereof. The slits  20   c  are arranged in the L-shape along two sides of the recess  20   a  that is rectangular seen in the vertical direction (see  FIG. 19 .) A release agent is applied to the recess  20   a  prior to pouring of the optical adhesive  21 . Here, the optical adhesive  21  is, for example, a silicon or epoxy adhesive, and corresponds to the second hardening resin in this invention. 
     Next, the temporary assembly  2   p  surrounded with the films  19  is drawn out from the receptacle for stack  15 . Specifically, the handle is operated to lift for removal of the temporary assembly  2   p  ejected from the front of the receptacle for stack  15 . The scintillation counter crystals  11  are bound firmly with a pair of the films  19  collectively. Accordingly, the scintillation counter crystals  11  are not separated at this time. Thereafter, the temporary assembly  2   p  is inserted into the recess  20   a  of the receptacle for joint  20  together with the films  19 , and sinks into the optical adhesive  21 . Here, the recess  20   a  is set under a reduced pressure environment, whereby the optical adhesive  21  is completely spread over the gaps between the scintillation counter crystals  11 . Then, joining of each tongue in the films  19  is released and folding thereof is also released. The films  19  are drawn out from the recess  20   a  in the z-direction, which is illustrated in  FIG. 18 . 
     &lt;Light Guide Jig Placing Step S 8 &gt; 
     Subsequently, as shown in  FIG. 19 , the light guide jig  24  is placed on the upper end of the receptacle for joint  20 . The light guide jig  24  is a jig having a first portion  24   a  extending in the x-direction and a second portion  24   b  extending in the y-direction that are coupled in the L-shape. Consequently, the light guide jig  24  is L-shaped seen in the z-direction (the vertical direction.) The first portion  24   a  and the second portion  24   b  of the light guide jig  24  have nibs  24   c  that extend downward in the vertical direction. Upon placing of the light guide jig  24  in the receptacle for joint  20 , the nibs  24   c  are fitted into the slits  20   c  on the upper end of the receptacle for joint  20  that are arranged in the L-shape. 
     &lt;Light Guide Placing Step S 9 &gt; 
     Next, as shown in  FIG. 19 , the light guide  4  is placed so as to cover the upper surface of the temporary assembly  2   p  that is exposed from the recess  20   a  of the receptacle for joint  20 . Taking into consideration that the temporary assembly  2   p  sinks into the optical adhesive  21 , the upper surface of the temporary assembly  2   p  is to be penetrated with the optical adhesive  21 . When the light guide  4  is placed under this state so as to cover the upper surface of the temporary assembly  2   p,  a film of the optical adhesive  21  is interposed between one surface of the light guide  4  directed downward vertically and the upper surface of the temporary assembly  2   p.  Here, the position of the temporary assembly  2   p  with respect to the light guide  4  is determined with the light guide jig  24 . Specifically, as shown in  FIG. 20 , the light guide  4  placed in the receptacle for joint  20  slides so as to contact one surface  24   x  extending in the x-direction and the other surface  24   y  extending in the y-direction. Accordingly, the light guide  4  is guided so as to contact the light guide jig  24  in the x-direction and the y-direction. Taking into consideration that the light guide jig  24  has the L-shape, the light guide  4  is relatively positioned en bloc with respect to the temporary assembly  2   p  in both x-direction and y-direction. The x-direction and the y-direction correspond to the first direction and the second direction, respectively, in this invention. 
       FIG. 21  is a sectional view of the receptacle for joint on arrow at a position of numeral  25  in  FIG. 20  when cutting thereof. As shown in  FIG. 21 , the relative position of the light guide  4  and the temporary assembly  2   p  is determined with the light guide jig  24 .  FIG. 21  is a sectional view in the zx-plane. Embodiment 1 has a similar yz-plane in its sectional view. 
     &lt;Second Hardening Resin Hardening Step S 10 &gt; 
     Subsequently, the optical adhesive  21  hardens. Consequently, the scintillator  2  is formed inside the recess  20   a  having the scintillation counter crystals coupled three-dimensionally. Simultaneously, the optical adhesive  21  between the scintillator  2  and the light guide  4  also hardens. As a result, the scintillator  2  and the light guide  4  are to be joined and coupled optically. As noted above, with the method of manufacturing the radiation detector  1  according to Embodiment 1, the scintillator  2  and the light guide  4  are already coupled optically. 
     &lt;Coupling Step S 11 &gt; 
     At the time the light guide  4  and the scintillator  2  are joined, the light guide jig  24  is removed from the receptacle for joint  20 . As a result, the light guide  4  is exposed on the upper surface of the receptacle for joint  20 . Then, the scintillator  2  is drawn out from the recess  20   a  of the receptacle for joint  20  using the light guide  4  as a handle. The light detector  3  approaches the light guide  4  such that the light guide  4  is sandwiched between the light detector  3  and the scintillator  2  to optically couple both  3  and  4  via the optical adhesive. As mentioned above, the radiation detector  1  according to Embodiment 1 is completed. 
     With the configuration of Embodiment 1 as mentioned above, the method of manufacturing the radiation detector  1  may be provided in which the step of hardening the optical adhesive  21  and the step of optically coupling the scintillator  2  and the light guide  4  are performed en bloc. In other words, the scintillator  2  of the configuration in Embodiment 1 is manufactured by forming the temporary assembly  2   p  having the scintillation counter crystals  11  arranged therein, and penetrating gaps between the scintillation counter crystals  11  with the optical adhesive  21 , and then hardening it. According to the configuration in Embodiment 1, the scintillator  2  is not manufactured merely by hardening the optical adhesive  21 , but the light guide  4  is placed so as to cover one surface of the temporary assembly  2   p  that sinks into the optical adhesive  21  prior to hardening. As a result, the optical adhesive  21  is to be interposed between the one surface of the temporary assembly  2   p  and the light guide  4 . According to the configuration in Embodiment 1, the optical adhesive  21  hardens while the light guide  4  is placed on the temporary assembly  2   p.  Consequently, the optical adhesive  21  that penetrates between the scintillation counter crystals  11  constituting the temporary assembly  2   p  hardens to join the scintillation counter crystals  11  to one another. Moreover, the optical adhesive  21  interposed between one surface of the temporary assembly  2   p  and the light guide  4  hardens, thereby joining the scintillator  2  and the light guide  4 . Therefore, the foregoing configuration in Embodiment 1 may realize manufacturing of the radiation detector  1  with no complicated process of forming the scintillator  2  and the light guide  4  individually and coupling them with the optical adhesive. 
     Embodiment 2  
     Next, description will be given of a configuration in Embodiment 2. Embodiment 2 differs from Embodiment 1 in manufacturing in advance of the scintillator  2 .  FIG. 22  is a flow chart showing a method of manufacturing a radiation detector according to Embodiment 2. The configuration of Embodiment 2 includes the step of manufacturing the scintillator. The same steps proceed as the step S 5  of manufacturing the temporary assembly and the step S 6  of pouring the second hardening resin in Embodiment 1 upon manufacturing of this scintillator. Thus, the explanation thereof is to be omitted. In Embodiment 2, at the time the temporary assembly  2   p  is placed in the receptacle for joint  20 , the optical adhesive  21  (the second hardening resin) hardens, and the scintillator  2  having the scintillation counter crystals  11  joined to one another is removed from the receptacle for joint  20 . This unique step in Embodiment 2 is referred to as the step T 1  of joining the scintillation counter crystals. Here, at the time the scintillator  2  is removed from the receptacle for joint  20 , the excessive film optical adhesive  21  is removed that adheres to each surface of the scintillator  2 . In this way, the scintillator  2  is firstly manufactured in Embodiment 2. That is, the step S 5  of manufacturing the foregoing temporary assembly, the step S 6  of pouring the second hardening resin, and the step T 1  of joining the scintillation counter crystals correspond to the scintillator manufacturing step according to this invention. 
     Next, the light guide  4  is to be manufactured. In this situation, the same steps proceed as the optical member frame manufacturing step S 1 , the optical member frame insertion step S 2 , and the first hardening resin pouring step S 3  described in Embodiment 1. The explanation thereof is to be omitted. Here, the optical member frame  6  is inserted into an opening  27   a  of the mold  27  (corresponding to the mold  7  in Embodiment 1), and sinks into the thermosetting resin  8  prior to hardening. 
     Now, description will be given of the mold  27  according to Embodiment 2.  FIG. 23  is a perspective view showing the method of manufacturing the radiation detector according to Embodiment 2. As shown in  FIG. 23 , the mold  27  with a rectangular opening  27   a  has on its front surface two or more slits  27   c.  The slits  27   c  are arranged in the L-shape along two sides of the opening  27   a  that is rectangular seen in the vertical direction. 
     &lt;Scintillator Jig Placing Step T 2 &gt; 
     Next, as shown in  FIG. 23 , the scintillator jig  22  is placed on the mold  27 . The scintillator jig  22  is a jig having a first portion  22   a  extending in the x-direction and a second portion  22   b  extending in the y-direction that are coupled in the L-shape. Consequently, the scintillator jig  22  is L-shaped seen in the z-direction (the vertical direction.) The first portion  22   a  and the second portion  22   b  of the scintillator jig have nibs  22   c  that extend downward in the vertical direction. Upon placing of the scintillator jig  22  in the mold  27 , the nibs  22   c  are fitted into the slits  27   c  on the upper end of the mold  27 . 
     The scintillator jig  22  is divided into an upper region  22   m  and a lower region  22   n  that are stacked in the z-direction. The upper region  22   m  is provided on the upper end side of the scintillator jig  22 . The upper region  22   m  has a first surface  22   x  extending in the x-direction and a second surface  22   y  extending in the y-direction that contact the scintillator  2 . On the other hand, the lower region  22   n  is provided on the lower end side having nibs  22   c  provided thereon, and has a cut-out with a portion that contacts the scintillator  2  being cut out in an L-shape. The cut-out is provided for suppressing penetrating of the thermosetting resin  8  that covers the opening  27   a  of the mold  27  between the scintillator jig  22  and the mold  27 . 
     &lt;Scintillator Placing Step T 3 &gt; 
     Next, the scintillator  2  is placed so as to cover the opening  27   a  of the mold  27 , whereby the thermosetting resin  8  is interposed between the scintillator  2  and the light guide  4 . Here, as shown in  FIG. 24 , the scintillator jig  22  positions the light guide  4  with respect to the scintillator  2 . Specifically, the light guide  4  placed on the mold  27  slides to guide the scintillator  2  so as to contact each of the first surface  22   x  as the zx-plane of the scintillator jig  22  and the second surface  22   y  as the yz-plane in the x-direction and the y-direction, respectively. Taking into consideration that the scintillator jig  22  has the L-shape, the light guide  4  is relatively positioned en bloc with respect to the scintillator  2  in both x-direction and y-direction. The x-direction and the y-direction correspond to the first direction and the second direction, respectively, in this invention. 
     &lt;First Hardening Resin Hardening Step T 4 &gt; 
     Next, the thermosetting resin  8  hardens. Accordingly, the light guide  4  that receives light is manufactured inside the opening  27   a.  Simultaneously, the thermosetting resin  8  interposed between the scintillator  2  and the light guide  4  hardens, thereby optically joining and coupling the scintillator  2  and the light guide  4 . In this way, with the method of manufacturing the radiation detector  1  according to Embodiment 2, the scintillator  2  and the light guide  4  are already coupled optically when the light guide  4  is manufactured. 
       FIG. 25  is a sectional view of the receptacle for joint on arrow at a position of numeral  26  in  FIG. 24  when cutting thereof. As shown in  FIG. 25 , the relative position of the scintillator  2  and the opening  27   a  is determined with the scintillator jig  24 . 
     &lt;Coupling Step T 5 &gt; 
     At the time the light guide  4  and the scintillator  2  are joined, the scintillator jig  22  is removed from the mold  27 . As a result, the scintillator  2  is exposed on the upper surface of the mold  27 . Then, the light guide  4  is drawn out from the opening  27   a  of the mold  27  using the scintillator  2  as a handle. The light detector  3  approaches the light guide  4  such that the light guide  4  is sandwiched between the light detector  3  and the scintillator  2  to optically couple both  3  and  4  via the optical adhesive. As mentioned above, the radiation detector  1  according to Embodiment 2 is completed. 
     According to Embodiments 1 and 2 as noted above, both steps of manufacturing the scintillator  2  and the light guide  4  include the step of hardening the hardening resin. Giving attention to this, Embodiments 1 and 2 have a configuration of manufacturing either the light guide  4  or the scintillator  2  and then placing either the manufactured scintillator  2  or the light guide  4  on the incomplete scintillator  2  or light guide  4 . Such configuration allows one surface of the light guide  4  or the scintillator  2  to be penetrated with the hardening resin prior to hardening. When the hardening resin hardens under this state, the hardening resin that penetrates the one surface of the scintillator  2  or the light guide  4  is to harden, which results in joining of the light guide  4  and the scintillator  2 . As noted above, the method of manufacturing the radiation detector  1  may be provided in which the step of hardening the hardening resin to manufacture the scintillator  2  or the light guide  4 , and the step of optically coupling the scintillator  2  and the light guide  4  are performed en bloc. Therefore, the radiation detector  1  may be manufactured with no complicated process of forming the scintillator  2  and the light guide  4  individually and coupling them with the optical adhesive. 
     This invention is not limited to the foregoing configurations, but may be modified as follows. 
     (1) In each of the foregoing embodiments, the scintillation counter crystal is composed of LYSO. Alternatively, the scintillation counter crystal may be composed of another materials, such as GSO (Gd 2 SiO 5 ), may be used in this invention. According to this modification, a method of manufacturing a radiation detector may be provide that allows provision of a radiation detector of low price. 
     (2) In each of the foregoing embodiments, the scintillator  2  has four scintillation counter crystal layers. This invention is not limited to this embodiment. 
     For instance, the scintillator formed of one scintillation counter crystal layer may be applied to this invention. Moreover, the scintillation counter crystal layer may be freely adjusted in number depending on applications of the radiation detector. 
     (3) The light detector in each of the foregoing embodiments is formed of the photomultiplier tube. This invention is not limited to this embodiment. A photodiode or an avalanche photodiode, etc. may be used instead of the photomultiplier tube. 
     (4) In each of the foregoing embodiments, the first optical member and the second optical member that constitute the light guide are formed of a reflector that reflects fluorescence. This invention is not limited to this embodiment. A material of the first plate may be selected from one of a material that reflects light, a material that absorbs light, and a material that transmits light. Likewise, a material of the optical member may be selected from one of a material that reflects light, a material that absorbs light, and a material that transmits light. According to this modification, the first optical member and the second optical member may freely vary in material depending on applications of the radiation detector. 
     INDUSTRIAL UTILITY  
     As described above, this invention is suitable for a radiation detector for use in a medical field.