JP2008107134A - Radiographic image detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic image detector capable of being accurately and easily assembled when is to be assembled. <P>SOLUTION: A scintillator panel has both a protective film for sealing a substrate in which a fluorescent layer is formed and a cushion member on the side of a protective cover of the substrate in the protective film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radiation image detector.

  Conventionally, radiation images represented by X-ray images have been widely used for diagnosis of medical conditions in the medical field. In recent years, digital radiation image detectors represented by flat panel radiation detectors (FPD (Flat Panel Detector)) and the like have appeared, and a radiation image is acquired as digital information and image processing can be performed freely. It is possible to transmit image information instantly.

  In the FPD, a scintillator panel that receives radiation transmitted through a subject and instantaneously emits fluorescence with an intensity corresponding to the dose is used. The light emission efficiency of the scintillator panel increases as the thickness of the phosphor layer increases. However, if the phosphor layer is too thick, scattered light is generated in the phosphor layer and the contrast is lowered. In order to improve diagnosis, it is necessary to obtain an image with high contrast.

When a phosphor having a columnar crystal structure such as cesium iodide (CsI) is used, there is little generation of scattered light in the crystal due to the light guide effect, and the phosphor layer is thickened to maintain the contrast. It is possible to increase luminous efficiency. Furthermore, it is possible to improve luminous efficiency by adding thallium (Tl) or the like as an activator to cesium iodide (CsI) (see, for example, Patent Document 1).
JP 2002-116258 A

  Usually, a protective cover for protecting the scintillator panel from an external impact or the like is provided on the radiation incident side of the scintillator panel. A light receiving element that receives light emitted from the scintillator panel is provided on the side opposite to the protective cover via the scintillator panel. In addition, a cushion member is provided between the protective cover and the scintillator panel so that the scintillator panel is properly pressed against the light receiving element, and the scintillator panel receives light by the pressure of the cushion member compressed when the protective cover is attached. The element is brought into pressure contact with an appropriate pressure.

  When assembling the radiation image detector, the scintillator panel and the cushion member are sequentially placed on the light receiving element arranged in the casing, and then the protective cover is fixed to the casing with screws or the like.

  When assembling the radiation image detector in this way, a cushion member must be placed on the light receiving element in addition to the scintillator panel. Therefore, the scintillator panel or the cushion member is easily displaced, or the cushion member is displaced. There is a problem that it takes a lot of time and effort to mount the product.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a radiographic image detector that can be easily assembled with high accuracy when the radiographic image detector is assembled.

  The radiation image detector of the present invention includes a scintillator panel having a substrate on which a phosphor layer is formed, a protective cover disposed on the radiation incident side of the scintillator panel on the opposite side of the phosphor layer through the substrate, In a radiation image detector comprising a light receiving element that is provided on the opposite side of the protective cover via a scintillator panel and in which a plurality of light receiving pixels are arranged in a two-dimensional manner to photoelectrically convert light from the scintillator panel, It has a protective film for sealing the substrate on which the phosphor layer is formed, and has a cushion member on the protective cover side of the substrate in the protective film.

  According to the present invention, since the cushion member is enclosed in the scintillator panel and integrated with the scintillator panel, when the radiation image detector is assembled, only the scintillator panel is placed on the light receiving element and the protective cover is attached. Because it is good, it can be assembled easily with high accuracy.

  Hereinafter, although this embodiment is described with reference to an accompanying drawing, it is an example and is not limited to this embodiment.

(Configuration of radiation image detector)
FIG. 1 is a configuration diagram of a radiation image detector 1 according to the present embodiment. The radiation image detector 1 is provided in a housing 11 so as to be in pressure contact with the scintillator panel 12 that receives radiation transmitted through a subject and instantaneously emits fluorescence with an intensity corresponding to the dose. A light receiving element 13 in which a plurality of light receiving pixels that photoelectrically convert light from the panel 12 are two-dimensionally arranged, and a protective cover 14 that protects the scintillator panel 12 are provided.

  In the scintillator panel 12, a cushion layer 123 as a cushion member of the present invention is disposed on the back surface of the substrate 122 on which the phosphor layer 121 is formed, and the substrate 122 and the cushion layer 123 serve as the first protective film 124 and the second protection film. The structure is sealed with the film 125.

  The substrate 122 is made of a material that transmits radiation. The substrate 122 preferably has flexibility so that the scintillator panel 12 can be brought into uniform contact with the surface of the light receiving element 13. For example, a flexible polyimide film having a thickness of 125 μm can be used. In addition to the polyimide film, a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polyamide film, a triacetate film, a polycarbonate film, or the like can be used. As thickness, 50-500 micrometers is preferable.

  The phosphor layer 121 is composed of a phosphor layer having a columnar crystal structure that has a light guide effect and high luminous efficiency. For example, a phosphor layer having a columnar crystal structure can be formed on the substrate 122 by vacuum-depositing cesium iodide (CsI) to which thallium (Tl) is added as an activator as a phosphor material. In addition to cesium iodide (CsI), cesium bromide (CsBr) or the like can be used. In addition to thallium (Tl), europium, indium, lithium, potassium, rubidium, sodium, copper, cerium, zinc, titanium, gadolinium, terbium, and the like can be used as the activator.

  The cushion layer 123 is for bringing the scintillator panel 12 into pressure contact with the light receiving element 13 with an appropriate pressure. For example, a silicon-based or urethane-based foam material that absorbs little radiation can be used. The pressure contact force of the scintillator panel 12 to the light receiving element 13 is adjusted by the thickness of the cushion layer 123.

  The 1st protective film 124 and the 2nd protective film 125 are for moisture-proofing the fluorescent substance layer 121 and suppressing deterioration of the fluorescent substance layer 121, and are comprised from a film with low moisture permeability. For example, a polyethylene terephthalate film (PET) can be used. Besides PET, a polyester film, a polymethacrylate film, a nitrocellulose film, a cellulose acetate film, a polypropylene film, a polyethylene naphthalate film, or the like can be used.

  In addition, on the surfaces of the first protective film 124 and the second protective film 125 facing each other, a fusion layer for fusing and sealing each other is formed. For example, a layer of unstretched polypropylene (CPP) is formed. The cushion layer 123 is disposed on the back surface of the substrate 122 on which the phosphor layer 121 is formed, and the substrate 122 and the cushion layer 123 are sandwiched between the first protective film 124 and the second protective film 125, and the first in a reduced pressure atmosphere. It can seal by fuse | bonding the edge part which the protective film 124 and the 2nd protective film 125 contact.

  The light receiving element 13 is composed of a plurality of light receiving pixels arranged two-dimensionally. For example, it can be constituted by a photodiode + a thin film transistor (TFT). The signal charge photoelectrically converted by the photodiode is read out using the TFT. In addition, a CMOS, a CCD, or the like can be used as the light receiving element 13.

  The protective cover 14 protects the scintillator panel 12 from external impacts and the like, and also serves to compress the cushion layer 123 and press the scintillator panel 12 against the light receiving element 13 with an appropriate pressure. For example, it is composed of a carbon plate with high radiation transparency. In addition, an aluminum plate can be used as the protective cover 14.

  When the radiation image detector 1 is assembled, the substrate 122 and the cushion layer 123 on which the phosphor layer 121 is formed on the light receiving element 13 disposed in the housing 11 are replaced with the first protective film 124 and the second protective film 125. The scintillator panel 12 sealed in the above is placed, and then the protective cover 14 is assembled to the housing 11 with screws or the like. When the protective cover 14 is attached, the cushion layer 123 enclosed in the scintillator panel 12 is compressed, and the scintillator panel 12 is pressed against the light receiving element 13 with an appropriate pressure by the repulsive force of the cushion layer 123 against the compression. To do.

  Thus, according to this embodiment, since the cushion layer 123 is enclosed in the scintillator panel 12 and integrated with the scintillator panel 12, only the scintillator panel 12 is placed on the light receiving element 13 when assembling the radiation image detector. Can be mounted and the protective cover 14 can be attached, so that it can be easily assembled with high accuracy.

  In this embodiment, the two protective films of the first protective film 124 and the second protective film 125 are used. However, the substrate 122 and the cushion on which the phosphor layer 121 is formed while the single protective film is folded. The layer 123 may be sandwiched and sealed.

It is a block diagram of the radiographic image detector which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiation image detector 12 Scintillator panel 121 Phosphor layer 122 Board | substrate 123 Cushion layer 124 1st protective film 125 2nd protective film 13 Light receiving element

Claims (3)

A scintillator panel having a substrate on which a phosphor layer is formed;
A protective cover disposed on the radiation incident side of the scintillator panel opposite to the phosphor layer through the substrate;
A light receiving element provided on the opposite side of the protective cover via the scintillator panel and having a plurality of light receiving pixels arranged in a two-dimensional manner for photoelectrically converting light from the scintillator panel;
A radiation image detector comprising:
The scintillator panel has a protective film for sealing the substrate on which the phosphor layer is formed, and has a cushion member on the protective cover side of the substrate in the protective film. The radiographic image detector according to claim 1, wherein the cushion member is made of a silicon-based or urethane-based foam material. The said protective film is comprised from the 1st protective film and the 2nd protective film, and the surface which contacts the said board | substrate or the said cushion member of each protective film consists of resin which has heat-fusibility. Item 3. The radiation image detector according to Item 1 or 2.

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