JP2002311142A - Method of manufacturing x-ray solid-state detector and x-ray ct apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray solid-state detector which prevents a crosstalk between scintillator segments, to provide a method of manufacturing the X-ray solid-state detector and to provide an X-ray CT apparatus which uses them. SOLUTION: The scintillator segments 5 composed of a scintillator member are partitioned and separated by reflectors 4 by a plastic sheet provided with a reflecting and light-blocking function with reference to scintillation light. Scintillator blocks 6 on which reflecting layers 7 are formed on side faces on one side are bonded to photodiode arrays 3 on side faces on the other side of the scintillator blocks 6 in a prescribed positional relationship. Thereby, the X-ray solid-state detector 1 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an X-ray solid state detector, a method for manufacturing the same, and an X-ray CT apparatus using the same.

[0002]

2. Description of the Related Art One of the X-ray solid state detectors used in X-ray CT apparatuses is a Bi ₄ Ge ₃ O ₁₂ crystal (hereinafter referred to as “BGO crystal”) as a scintillator in a photomultiplier tube.
Are optically bonded. BaSO ₄ powder is applied as a reflector to the surface of the BGO crystal. This is for efficiently transmitting the scintillation light to the photomultiplier tube.

[0003] BGO crystals are gradually being miniaturized in order to improve the resolution of tomographic images.

A method of manufacturing an X-ray solid state detector is described in, for example, Japanese Patent Application Laid-Open No. Hei 5-19060. In addition, the BGO crystal 32 cut out in the form of a block forms the scintillator segments 38 with the cut grooves 34 at regular intervals,
35 is formed by cutting it vertically and horizontally, and the cut grooves 34, 3
5 is filled with a reflective material to produce a scintillator block 30 partitioned into a plurality of BGO crystal chips in a two-dimensional array, which is mounted on a photodiode array (not shown). Each scintillator segment 38 sectioned by the cut grooves 34, 35 has a very high pitch because if the processing accuracy of the cut grooves 34, 35 by the groove processing is sufficiently compensated, no pitch shift or position shift occurs. An accurate scintillator block 30 can be manufactured.

However, the reflector 37 injected between the scintillator segments is required to have a function of reflecting and blocking light. Therefore, when the reflection material or the light-shielding material is powdered or liquid and injected into the cut grooves 34 and 35, it is easy to be unfilled, and if the dispersion inside the cut grooves 34 and 35 is not uniform, Crosstalk occurs when the scintillation light generated in the scintillator segment 38 enters the adjacent scintillator segment 38.

[0006] This crosstalk itself is difficult to completely prevent since the X-ray incidence surface side in the groove is not completely partitioned by the reflecting material or the light shielding material.
It is possible to reduce.

[0007] For example, a sheet-like reflection /
It is conceivable that a light shielding plate is inserted into a one-way groove formed in a lattice shape in advance, and a comb-shaped reflection / light shielding plate manufactured with high precision is combined in a direction perpendicular to the inserted sheet.

[0008]

However, as described above, the sheet-like reflecting plate and the light-shielding plate are inserted into the one-way grooves formed in a lattice shape in advance, and are inserted in the direction orthogonal to the inserted sheet. In addition, the comb-shaped reflecting plate and the light shielding plate to be inserted later need to be manufactured with extremely high precision, which requires a number of manufacturing steps and is expensive.

In order to form a scintillator block having a relatively large two-dimensional area, a scintillator material also needs to have an area substantially equal to the size of the scintillator block. However, it is generally difficult to obtain a scintillator material having a large area and uniform sensitivity.

[0010] Further, since it is used as it is in a grooved state, it is also difficult to prevent crosstalk through a remaining portion.

The present invention has been made based on these circumstances, and an object of the present invention is to provide an X-ray solid state detector which prevents crosstalk between scintillator segments, a method of manufacturing the same, and an X-ray CT apparatus using the same. And

[0012]

According to the first aspect of the present invention, there is provided a scintillator piece including a scintillator member, and a plastic reflector having a function of reflecting and shielding light from the scintillator light from the scintillator member. A first step of forming a stripe block for laminating and adhering each other, a second step of forming grooves at predetermined intervals in the direction of lamination and adhesion of the stripe blocks, and a step of forming a groove from the scintillator member in the groove. A third step of inserting and bonding a plastic reflector having a function of reflecting and blocking scintillator light, and a fourth step of polishing both surfaces of the stripe block to which the reflector is fixed in the third step to form a scintillator block. Mounting the scintillator block on a photodiode array; A fifth step of bonding an end reflector to an end of the data array, and a sixth step of forming a reflective layer on an X-ray incident slope of the scintillator block. .

According to the second aspect of the present invention,
A first step of joining a reflective layer to a stripe block formed by laminating and adhering a scintillator piece made of a scintillator member and a plastic reflector having a function of reflecting and blocking light from the scintillator member; A second step of forming a groove halfway in the reflective layer at a predetermined interval with respect to the direction in which the stripe blocks are laminated and bonded; and reflecting and blocking light from the scintillator member from the scintillator member in the groove. A third step of inserting and bonding a plastic reflector having the function of: a fourth step of forming a scintillator block by polishing the opposite surface of the stripe layer to which the reflector is fixed in the third step, opposite to the reflection layer; Mounting the scintillator block on a photodiode array; 5 for bonding the end reflector to an end
And a method for manufacturing an X-ray solid state detector.

According to the third aspect of the present invention,
When inserting a plastic reflector having a function of reflecting and blocking scintillator light from the scintillator member into the groove formed in the stripe block, the stripe block is formed on the outer peripheral surface of an arc-shaped jig. A method of manufacturing an X-ray solid state detector, characterized in that the X-ray detector is fixed and the groove is widened to facilitate insertion.

According to a fourth aspect of the present invention,
The groove positioned at the center in the slice direction of the stripe block has a larger cut depth than other grooves so that the reflector positioned at the center can be observed from the X-ray incident surface side. It is a manufacturing method of a detector.

According to the fifth aspect of the present invention,
A plurality of X-ray solid state detectors are arranged in a direction (channel direction) perpendicular to the body axis direction of the X-ray source and the subject and the X-ray incident direction, and the X-rays are rotated around the subject to rotate. In an X-ray CT apparatus that obtains data by scanning while constantly changing the angle at which the beam intersects the subject, the X-ray solid-state detector includes a scintillator segment including a scintillator member that reflects and scintillates light. It has a scintillator block having a reflective layer formed on one side by being separated by a reflector made of a plastic sheet having a light-shielding function, and a photodiode array joined to the other side of the scintillator block in a predetermined positional relationship. X characterized by the following:
It is a line CT apparatus.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an external perspective view of an X-ray solid state detector according to the present invention.

An X-ray fan beam (X-ray beam) emitted from an X-ray source is used to detect projection data, which is a measured value of X-ray attenuation due to transmission through a subject such as a human body. The solid-state linear detector 1 is formed by mounting a scintillator block 2 on a photodiode array 3. The scintillator block 2 is sectioned and separated by a reflector 4 made of white plastic or the like, and receives scintillator segments 5a and 5b that emit X-rays and emit fluorescence.
.. 5n form a scintillator array 6. A white reflective layer 7 having a thickness of about 400 μm is formed on the X-ray beam incident surface of the scintillator array 6. The end face of the scintillator array 6 is connected to an end reflector 8.
a and 8b are adhered. On the other hand, the photodiode array 3 is composed of photodiodes (not shown) arranged corresponding to the scintillator segments 5a, 5b... 5n of the scintillator array 6. Fluorescence, which is scintillation light emitted by the scintillator array 6 upon receiving X-rays, is converted into a charge amount (current) by the photodiode array 3.

Next, a method for manufacturing the X-ray solid state detector 1 of the present invention will be described.

FIG. 2 is a flow chart showing a first embodiment of the method for manufacturing an X-ray solid state detector according to the present invention. First, as shown in FIG. 3, Nal (Tl),
Csl (Tl), BGO (Bi ₄ Ge ₃ O ₁₄ ), Cd
A scintillator piece 9 formed of a rectangular parallelepiped scintillator member such as WO ₄ and a reflector formed of PET or the like having the same cross section as the scintillator piece 9 and formed of a white plastic plate having a function of reflecting and blocking scintillation light. 4 are alternately bonded and fixed in a laminated state to form a striped stripe block 11. (S
1) Next, as shown in FIG. 4, in a direction perpendicular to the stripes of the stripe block 11, a width of 0.0
The groove 12 is formed by cutting using a blade (grinding stone) of 8 to 0.1 mm and performing groove processing at a predetermined pitch. The remaining portion 13 of the stripe block 11 at the time of groove processing
Was set to 0.1 to 0.3 mm. In this case, the height of the stripe block 11 is 2.3 mm. (S2) Next, as shown in FIG. 5, after injecting an adhesive into the formed groove 12, a reflector 4 made of white plastic having a width of about 0.08 mm is inserted and fixed. When inserting the reflector 4 into the groove 12, as shown in FIG. 6, by fixing the grooved stripe block 11 on the outer periphery of the arc-shaped jig 14, the opening of the groove 12 is expanded. The reflector 4 can be easily inserted. (S3) Next, as shown in FIG. 7, the surface on which the groove 12 of the stripe block 11 in which the reflector 4 is inserted and the back surface thereof, that is, both surfaces of the X-ray incident surface and the adhesive surface to the photodiode array 3 are placed. Grind at the same time. By this polishing, the remaining portion 13 remaining in the stripe block 11 is removed, and a scintillator array 6 (scintillator block 2) in which the scintillator segments 5 are two-dimensionally arranged is formed. (S4) Next, as shown in FIG. 8, the scintillator block 2 is aligned with the photodiode array 3 and mounted on the photodiode array 3. In addition, the end reflector 8
a, 8b are adhered to the end of the scintillator block 2.
When the scintillator block 2 is mounted on the photodiode, it can be easily aligned by observing the pattern formed by the scintillator array 6 of the scintillator block 2 (S5). As shown in FIG. 9, X of the scintillator block 2
The reflection layer 7 is formed by coating the line incident surface side with white paint. As the white paint, for example, a solution obtained by mixing a dispersion of BaSO ₄ powder with water and polyvinyl alcohol in a white paint of an acrylic resin is applied to a thickness of about 400 μm with a spray gun to detect X-ray solids. The vessel 1 is completed. (S6) Next, a second embodiment of the method for manufacturing an X-ray solid state detector according to the present invention will be described. FIG. 10 is a flowchart showing a second embodiment of the method for manufacturing an X-ray solid state detector according to the present invention. This manufacturing method is a manufacturing method in which the step of applying a white paint performed in the first embodiment is omitted.

First, as shown in FIG.
Nal (Tl), Csl (Tl), BGO, CdWO ₄
A scintillator piece 9 formed of a rectangular parallelepiped scintillator member, and a reflector 4 formed of a white plastic plate having a function of reflecting and blocking scintillation light by PET or the like having a cross section equal to the scintillator piece 9. Are alternately adhered and fixed in a stacked state to form a stripe block 11 having a vertical stripe shape. On one side of the stripe block 11, the width of the stripe block 11
Sheet-like PET with the same dimensions and a thickness of about 0.5 mm and a glass plate 16 with the same width and a thickness of 0.05 to 0.5 mm
Or a white plastic plate 18 of PET or the like having the same dimensions as the stripe block 11 and a thickness of about 0.5 mm. (S11) Next, as shown in FIG. 12, in a direction perpendicular to the stripes of the stripe block 11, a width of 0.08 is set by a slicer (not shown).
The groove 12a is formed by cutting using a blade (grinding stone) of about 0.1 mm and performing groove processing at a predetermined pitch. In this case, as shown in FIG. 13, the blade is cut by cutting the stripe block 11 down to the glass plate 16 or the white plastic plate 18. (S12) Next, FIG.
As shown in (1), after an adhesive (not shown) is injected into the formed groove 12, a reflector 4 made of white plastic having a width of about 0.08 mm is inserted and fixed. When inserting the reflector 4 into the groove 12, as shown in FIG. 6, by fixing the grooved stripe block 11 to an arc-shaped jig 14, the opening of the groove 12 is widened. Can be easily inserted. (S13) Next, as shown in FIG. 15, the bonding surface of the stripe block 11 to the photodiode array 3 where the reflective layer 7 is not formed is polished. By this polishing, a scintillator array 6 (scintillator block 2) having a reflective layer 7 in which the scintillator segments 5 are two-dimensionally arranged is formed. (S14) Next, as shown in FIG. 16, the scintillator block 2 is aligned with the photodiode array 3 and mounted on the photodiode array 3.
The end reflectors 8a and 8b are adhered to the end of the scintillator block 2 to complete the X-ray solid state detector 1a.

When the scintillator block 2 is mounted on the photodiode array 3, alignment can be easily performed if the scintillator block 2 can be mounted while observing a pattern formed by the scintillator array 6 of the scintillator block 2. In this case, white plastic is used. Since the scintillator block 2 has the plate 18 and the like bonded thereto, the pattern of the scintillator block 2 cannot be seen from the white plastic plate 18 side. Therefore, the end reflector 8 at the end in the slice direction and the channel direction of the scintillator block 2
What is necessary is just to align based on a and 8b. Further, when a higher precision alignment is required, as shown in the sectional view of FIG. 17A and the perspective view of the appearance of FIG. The groove 12b is cut completely with a larger cutting depth than the other grooves 12a, and the reflector 4 located at the center from the side of the white plastic plate 18 can be observed and aligned with each other when bonded. .
(S15) In each of the above embodiments, when forming the stripe block 11, if the end reflectors 8a and 8b at both ends in the channel direction are bonded in advance,
Burrs are likely to occur on the end reflectors 8a and 8b during groove processing. If burrs are generated, burrs are formed in the grooves 12, 12a,
12b to prevent the reflector 4 from being inserted,
It may cause unfilling of the adhesive and increase the pitting error. To prevent them, the bonding of the end reflectors 8a, 8b to the stripe block 11
Adhere after polishing.

In the X-ray solid state detectors 1 and 1a according to the manufacturing methods shown in the above embodiments, the sheet material as the reflector 4 having both the function as a reflecting material and the function as a light shielding material has grooves 12, Since the scintillator segments 5 are reliably partitioned by being inserted into the 12a and 12b, it is possible to prevent crosstalk from occurring in each scintillator segment 5 through the reflector 4.

Next, an X-ray CT apparatus equipped with an X-ray solid state detector according to the manufacturing method of the present invention will be described. FIG.
3 is a perspective view of a detection unit of the X-ray CT apparatus.

The medical X-ray CT apparatus is supported by a supporting member 22 together with a collimator 21 in a direction (channel direction) perpendicular to the X-ray source as a radiation, the body axis direction of the subject, and the X-ray incidence direction. A plurality of X-ray detectors 1, 1
By rotating a around the subject together with the gantry (not shown), data is obtained by scanning while constantly changing the angle at which the X-ray beam intersects the subject.

The X-ray detectors 1 and 1a are arranged in a row in the channel direction in a plurality of rows, that is, 8 rows or more, for example, 10 rows.
An array is provided to detect projection data, which is an X-ray attenuation measurement of an X-ray fan beam (X-ray beam) emitted from an X-ray source.

That is, the X-ray detectors 1 and 1a faithfully convert the dose of the X-ray transmitted through the subject into a charge amount, and constitute each scintillator segment (not shown) used therein. Each scintillator member receives X-rays and emits fluorescence, which is converted into a charge (current) by a photodiode array 3 composed of photodiodes. A signal output of the converted detection data is selected by a switch element connected to the photodiode array 3, and is a DAS (Data Acquisition System) which is a data collection element including an integrated circuit (not shown).
em). Note that DAS is X
An amplifier, a sample hold, a multiplexer, an A / D converter, an interface, and a computer are sequentially connected from the X-ray detector in accordance with the processing order of the signal after the line is detected by the X-ray detector.

Since this X-ray CT apparatus is equipped with the X-ray solid state detector of the present invention, crosstalk in each scintillator segment is prevented, and precise data can be obtained.

[0030]

According to the present invention, an X-ray solid state detector in which crosstalk is prevented can be realized. Further, by using it, a highly accurate X-ray CT apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an X-ray solid state detector according to the present invention.

FIG. 2 is a flowchart showing a first embodiment of a method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 3 is a schematic explanatory view showing a manufacturing process of the first embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 4 is a schematic explanatory view showing a manufacturing process of the first embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 5 is a schematic explanatory view showing a manufacturing process of the first embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 6 is a schematic explanatory view showing a manufacturing process of the first embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 7 is a schematic explanatory view showing a manufacturing process of the first embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 8 is a schematic explanatory view showing the manufacturing process of the first embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 9 is a schematic explanatory view showing a manufacturing process according to the first embodiment of the method for manufacturing an X-ray solid state detector of the present invention.

FIG. 10 is a flowchart showing a second embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 11 is a schematic explanatory view showing a manufacturing process according to a second embodiment of the method for manufacturing an X-ray solid state detector of the present invention.

FIG. 12 is a schematic explanatory view showing a manufacturing process according to a second embodiment of the method for manufacturing an X-ray solid state detector of the present invention.

FIG. 13 is a schematic explanatory view showing a manufacturing process according to a second embodiment of the method for manufacturing an X-ray solid state detector of the present invention.

FIG. 14 is a schematic explanatory view showing a manufacturing process according to a second embodiment of the method for manufacturing an X-ray solid state detector of the present invention.

FIG. 15 is a schematic explanatory view showing a manufacturing process of a second embodiment of the method for manufacturing an X-ray solid state detector according to the present invention.

FIG. 16 is a schematic explanatory view showing a manufacturing process according to a second embodiment of the method for manufacturing an X-ray solid state detector of the present invention.

FIG. 17 is a schematic explanatory view showing a manufacturing process according to a second embodiment of the method for manufacturing an X-ray solid state detector of the present invention.

FIG. 18 is a perspective view of a detection unit of the X-ray CT apparatus.

FIG. 19 is a partial cross-sectional perspective view of a conventional X-ray solid state detector.

[Explanation of symbols]

1, 1a: X-ray solid state detector, 2: scintillator block, 3: photodiode array, 4: reflector, 5
... scintillator segment, 6 ... scintillator array,
7: Reflective layer, 8: End reflector, 9: Scintillator piece, 11: Stripe block, 12, 12a, 12b
... groove, 18 ... white plastic plate

Continuing from the front page (72) Inventor Kenji Igarashi 33, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Toshiba Production Technology Center (reference) 2G088 EE02 FF02 GG19 JJ05 JJ09 JJ13 JJ37 5F088 AA01 BA03 EA04 HA09 JA17 LA08

Claims (5)

[Claims] A first step of forming a stripe block in which a scintillator piece made of a scintillator member and a plastic reflector having a function of reflecting and shielding light from the scintillator member are laminated and bonded to each other; A second step of forming grooves at predetermined intervals in the direction in which the stripe blocks are laminated and bonded; and a plastic having a function of reflecting and blocking light from scintillator from the scintillator member in the grooves. A third step of inserting and bonding a reflector, a fourth step of polishing both surfaces of the stripe block to which the reflector is fixed in the third step to form a scintillator block, and mounting the scintillator block on a photodiode array, Fifth bonding end reflector to the end of the array Degree and sixth step of the manufacturing method of the X-ray solid-state detector, characterized in that it comprises a forming the reflective layer on the X-ray entrance slopes of the scintillator block. 2. A reflection layer is formed on a stripe block formed by laminating and adhering a scintillator piece made of a scintillator member and a plastic reflector having a function of reflecting and blocking light from the scintillator member. A first step of joining, and a second step of forming a groove halfway in the reflective layer at a predetermined interval with respect to the direction in which the stripe blocks are stacked and bonded.
And a third step of inserting and bonding a plastic reflector having a function of reflecting and blocking scintillator light from the scintillator member into the groove, and a step of attaching the reflector in the third step to the stripe block. A fourth step of polishing the opposite surface of the reflective layer to form a scintillator block; and a fifth step of mounting the scintillator block on a photodiode array and bonding an end reflector to an end of the scintillator array. A method for manufacturing a solid-state X-ray detector. 3. An outer periphery of an arc-shaped jig when a plastic reflector having a function of reflecting and blocking scintillator light from the scintillator member is inserted into the groove formed in the stripe block. 3. The method of manufacturing an X-ray solid state detector according to claim 1, wherein the stripe block is fixed to a surface, and a groove is widened to facilitate insertion. 4. The groove located at the center of the stripe block in the slice direction has a larger cutting depth than other grooves so that the reflector located at the center can be observed from the X-ray incident surface side. 3. The method for manufacturing an X-ray solid state detector according to claim 2, wherein 5. A plurality of solid state X-ray detectors are arranged in a direction (channel direction) perpendicular to the body axis direction of the X-ray source and the subject and the X-ray incident direction, and are rotated around the subject. In the X-ray CT apparatus which obtains data by scanning while constantly changing the angle at which the X-ray beam intersects the subject, the X-ray solid state detector includes a scintillator segment comprising a scintillator member. And a scintillator block having a reflective layer formed on one side surface and separated by a reflector made of a plastic sheet having a reflection and light blocking function, and a photo bonded to the other side surface of the scintillator block in a predetermined positional relationship. An X-ray CT apparatus comprising: a diode array.