JP2005265706A - Radiation detector and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation detector which can reduce dispersion in the output. <P>SOLUTION: The radiation detector is provided with: a substrate 11; a photo diode 20 which is provided on the substrate 11 and in which a photo diode element 21 is disposed along the X direction; and a scintillator block 30 provided on the photo diode 20 and consisting of a scintillator element 31 stacked along the Y direction perpendicular to the X direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radiation detector for detecting radiation such as X-rays and a method for manufacturing the same, and more particularly to a detector capable of reducing output variations and performing highly accurate detection.

  An X-ray computed tomography apparatus (hereinafter referred to as “X-ray CT apparatus”) is known as one of X-ray diagnostic apparatuses. In the X-ray CT apparatus, an X-ray tube (radiation detector) in which an X-ray tube for irradiating a fan-shaped fan beam X-ray and a large number of X-ray detection elements are arranged in parallel is arranged in the center of the tomographic plane of the subject. It is configured. In the X-ray CT apparatus, a fan beam X-ray is irradiated from the X-ray tube toward the X-ray detector, and the X-ray is changed by changing the angle, for example, by 1 degree with respect to the tomographic plane every time irradiation is performed. After collecting the absorption data, this X-ray absorption data is analyzed by a computer to calculate the X-ray absorption rate at each position on the tomographic plane of the subject, and an image corresponding to the absorption rate is constructed. It is.

On the other hand, a radiation detector combining a ceramic scintillator obtained by sintering a CdWO ₄ single crystal or Gd ₂ O ₂ S: Pr phosphor powder and a silicon photodiode has been developed and put into practical use (for example, see Patent Document 1). In radiation detectors using these materials, it is easy to reduce the size of the detection element and increase the number of channels.

  The radiation detector is configured, for example, as shown in FIG. That is, the radiation detector 100 includes a substrate 101, a photodiode 110 on the substrate 101, and a scintillator block 120 bonded on the photodiode 110 with an optical adhesive.

The photodiode 110 includes 20 photodiode elements 111 arranged in parallel in the arrow X direction in the figure. The scintillator block 120 includes 20 scintillator elements 121 arranged in parallel in the arrow X direction in the figure, and a separator 122 sandwiched between the scintillator elements 121. That is, as shown in FIG. 6, one scintillator element 121 is provided so as to correspond to one photodiode element 111.
JP-A-11-237480

  The radiation detector described above has the following problems. In other words, since the scintillator element is manufactured by sintering and then cut into a predetermined shape, the density and composition of crystals and powders are likely to be non-uniform during sintering, and the physical properties may vary depending on the position of cutting. is there. As a result, as shown in FIG. 7, for example, the output from the photodiode 110 has a variation of about several percent, which becomes an obstacle when a clear image is formed.

  Accordingly, an object of the present invention is to provide a radiation detector capable of reducing variations in output and a method for manufacturing the same.

  In order to solve the above problems and achieve the object, the radiation detector and the manufacturing method thereof according to the present invention are configured as follows.

(1) A substrate, a photodiode provided on the substrate and having a segment disposed along the first direction, and a second direction provided on the photodiode and intersecting the first direction. A radiation detector comprising a scintillator block composed of scintillator elements stacked along the scintillator element.

(2) The radiation detector according to (1), wherein the first direction and the second direction are orthogonal to each other.

(3) The radiation detector according to (1), wherein the scintillator block has a groove formed at a position corresponding to a boundary between the segments, and a separator is inserted into the groove. It is characterized by.

(4) a scintillator element laminating step for laminating a plurality of scintillator elements to form a scintillator block; a photodiode mounting step for providing a photodiode on a substrate so that its segments are arranged along a first direction; An adhesion step of adhering the scintillator block onto the photodiode with an optical adhesive with the stacking direction of the scintillator block as a second direction intersecting the first direction.

(5) The radiation detector manufacturing method described in (4) above, wherein the first direction and the second direction are orthogonal to each other.

(6) In the radiation detector manufacturing method described in (4) above, after the scintillator element stacking step, a groove processing step of forming a groove portion at a position corresponding to a boundary between the segments, and the groove portion A separator insertion step of inserting a separator is provided.

  According to the present invention, output variations can be reduced.

  FIG. 1 is an exploded perspective view showing the radiation detector 10 according to the first embodiment of the present invention, FIG. 2 is an explanatory view showing the positional relationship between the scintillator block 30 and the photodiode 20 in the radiation detector 10, and FIG. FIG. 4 is an explanatory view showing a comparison between output variation in the radiation detector 10 and output variation in a conventional radiation detector, and FIG. 4 is an explanatory view showing a manufacturing process of the radiation detector 10.

  The radiation detector 10 includes a substrate 11 made of a glass epoxy material, a photodiode 20 on the substrate 11, and a scintillator block 30 bonded on the photodiode 20 with an optical adhesive.

  The photodiode 20 includes 20 photodiode elements 21 arranged in parallel in the arrow X direction in the figure. The scintillator block 30 includes a plurality of scintillator elements 31 arranged side by side in the arrow Y direction in the figure, and a separator plate 32 made of molybdenum or the like that is provided between the scintillator elements 31 and absorbs scattered light. I have.

  As shown in FIG. 2, in the photodiode 20 and the scintillator block 30, the parallel arrangement direction (arrow X direction) of the photodiode elements 21 of the photodiode 20 and the stacking direction (arrow Y direction) of the scintillator elements 31 are orthogonal to each other. Are arranged to be.

  Next, the manufacturing process of such a radiation detector 10 will be described. The scintillator element P is cut out from a massive scintillator formed by sintering in advance. The scintillator element P is, for example, 1 mm long × 2 mm wide × 30 mm long. The long sides of the scintillator element P are bonded to each other with an optical adhesive. In addition, you may make it insert the separator S between the scintillator elements P in order to prevent bending.

  Next, a groove G is formed along the Y direction in the drawing. The groove G corresponds to the boundary position between the photodiode elements 21. Next, the separator S is inserted into the groove G.

  Next, after double-side polishing and finishing to a predetermined size, it is bonded to the photodiode 20 using an optical adhesive.

  According to the radiation detector 10 described above, the arrangement direction of the 20 photodiode elements 21 (arrow X direction) and the stacking direction of the scintillator elements 31 (arrow Y direction) are arranged so as to be orthogonal to each other. Each of the photodiode elements 21 corresponds to six common scintillator elements 31. For this reason, even if the scintillator elements 31 have non-uniform composition and density and may have different physical characteristics, they are provided in common to the respective photodiode elements 21, so that variations are averaged. Therefore, as shown in FIG. 3, the variation is about 1/6 to 1/2, and sufficient accuracy for constructing the image can be obtained. The dotted line Q indicates the output of the conventional radiation detector. Note that although there is some variation even in the radiation detector 10, this is considered to be derived from the non-uniformity of the composition and density in one scintillator element 31.

  As described above, according to the radiation detector 10 according to the present embodiment, it is possible to average the composition / density non-uniformity for each scintillator element 31, thereby preventing variations in output for each photodiode element 21. It becomes possible to do. Therefore, when used as an X-ray detector such as an X-ray CT apparatus, a clear image can be formed.

  It is also possible to adopt a simple configuration in which the groove G is not formed, the separator S is omitted, and the separator 32 is not provided.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The disassembled perspective view which shows the radiation detector which concerns on one embodiment of this invention. Explanatory drawing which shows the relationship between the scintillator element and photodiode in the radiation detector. Explanatory drawing which compares and shows the dispersion | variation in the output in the radiation detector, and the dispersion | variation in the output in the conventional radiation detector. Explanatory drawing which shows the manufacturing process of the radiation detector. The disassembled perspective view which shows an example of the conventional radiation detector. Explanatory drawing which shows the relationship between the scintillator element and photodiode in the radiation detector. Explanatory drawing which shows the dispersion | variation in the output in the same radiation detector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Radiation detector, 20 ... Photodiode, 21 ... Photodiode element, 30 ... Scintillator block, 31 ... Scintillator element, 32 ... Separator plate.

Claims (6)

A substrate,
A photodiode provided on the substrate and having segments disposed along the first direction;
A radiation detector comprising: a scintillator block that is provided on the photodiode and includes a plurality of scintillator elements stacked in a second direction crossing the first direction.   The radiation detector according to claim 1, wherein the first direction and the second direction are orthogonal to each other.   The radiation detector according to claim 1, wherein a groove portion is formed in the scintillator block at a position corresponding to a boundary between the segments, and a separator is inserted into the groove portion. A scintillator element laminating step of laminating a plurality of scintillator elements to form a scintillator block;
A photodiode mounting step of providing the photodiode on the substrate such that the segment is disposed along the first direction;
An adhesion step of adhering the scintillator block on the photodiode via an optical adhesive with a laminating direction of the scintillator block as a second direction intersecting the first direction. Radiation detector manufacturing method.   The radiation detector manufacturing method according to claim 4, wherein the first direction and the second direction are orthogonal to each other. After the scintillator element laminating step, a groove processing step of forming a groove portion at a position corresponding to the boundary between the segments,
The radiation detector manufacturing method according to claim 4, further comprising a separator insertion step of inserting a separator into the groove portion.

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