1. Field of the Invention
The present invention generally relates to a radiation detecting apparatus, a manufacturing method thereof, a scintillator panel and a radiation detecting system which are used for a medical diagnostic device, a nondestructive inspection device and the like, and more particularly to a scintillator panel, a radiation detecting apparatus and a radiation detecting system which are used for X-ray radiographing and the like. Incidentally, in the present specification, the description is given on the basis of the supposition that the category of a radiation includes an electromagnetic wave such as an X-ray and a γ-ray.
2. Related Background Art
In recent years, the digitization of X-ray radiographing has been accelerated, and various radiation detecting apparatuses have been announced. Their systems are roughly divided into two types of a direct system and an indirect system. The direct system is a type which directly converts an X-ray into an electric signal, and reads the converted electric signal. The indirect system is a type which once converts an X-ray into visible light and then converts the converted visible light into an electric signal to read the converted electric signal.
On the sensor protecting layer 104, a phosphor layer 111 made of CsI:Tl of a columnar crystal is formed as a wavelength conversion body converting a radiation into the light which the photoelectric conversion elements 102 can sense. The humidity proof protection of the phosphor layer 111 from the exterior is implemented by a phosphor protecting layer 112 consisting of an organic film made of poly-para-xylylene (trademark name: Parylene) having a thickness of about 10 μm, a reflecting layer 113 made of aluminum, and a protecting layer 114 made of Parylene. The reflecting layer 113 made of aluminum is provided for reflecting the light proceeding to the opposite side of the photoelectric conversion unit from the phosphor layer 111 and for leading the reflected light to the photoelectric conversion unit. The reflecting layer 113 is in a thin film state having a thickness of a submicron level by a vapor deposition method or the like. A reference numeral 115 denotes a covering resin for preventing the exfoliation of the phosphor protecting layer 112.
The radiation detecting apparatus shown in
The above-mentioned material called as Parylene constituting the humidity proof protecting layer (composed of the phosphor protecting layer 112 and the protecting layer 114) on the phosphor layer 111 is stated in “Parylene coating system”, Three Bond Technical News, Three Bond Co., Ltd., Sep. 23, 1992, vol. 39, pp. 1-10. Parylene can be acquired as follows. A raw material called as di-para-xylylene (dimer) is heated and sublimated under a low pressure, and then a para-xylylene radical gas in a state of being heated to about 600° C. to be thermally decomposed is introduced to the adherend. Thereby, polymeric para-xylylene having a molecular weight of about 500,000 is condensed and polymerized to be acquired as Parylene.
However, the Parylene used as the material of the phosphor protecting layer in the prior art radiation detecting apparatus mentioned above is very reactive in a para-xylylene radical gas state in which one kind of dimer is thermally decomposed. Consequently, reactions sometimes advance in a gaseous state depending on changes of the temperature and the pressure in the system, and the produced organic film may become a heterogeneous film or have generated projections owing to by-products on the surface thereof. Such states will roughen the reflection surface of the reflecting layer 113 formed in the upper part of the phosphor protecting layer 112, and image defects may be caused in the worst case.
In the view of the problems mentioned above, it is an object of the present invention to provide a radiation detecting apparatus including a phosphor protecting layer which does not make the reflection surface of a reflecting layer on a phosphor layer produce structural disorder, and being capable of suppressing the generation of image defects.
For solving the problems mentioned above, a radiation detecting apparatus according to the present invention includes a substrate, a phosphor layer formed on the substrate to convert a radiation into light, and a phosphor protecting layer covering the phosphor layer to adhere closely to the substrate, wherein the phosphor protecting layer is made of an organic film formed by vapor deposition polymerization.
A scintillator panel according to the present invention includes a supporting member, a phosphor layer formed on the supporting member to convert a radiation into light, and a phosphor protecting layer covering the phosphor layer to adhere closely to the supporting member, wherein the phosphor protecting layer is made of an organic film formed by vapor deposition polymerization.
A manufacturing method of a radiation detecting apparatus according to the present invention is a manufacturing method of a radiation detecting apparatus including a substrate, a phosphor layer formed on the substrate to convert a radiation into light, and a phosphor protecting layer covering the phosphor layer to adhere closely to the substrate, the method including the step of forming the phosphor protecting layer by a vapor deposition polymerization method so as to cover the phosphor layer and to adhere closely to the substrate.
According to the present invention, because the organic film formed by the vapor deposition polymerization is used as the phosphor protecting layer, the polymerization reaction of the organic film is performed by the vapor deposition polymerization on an attachment. Thereby, in comparison with Parylene formed by the radical polymerization of the prior art, the generation of by-products is suppressed and the uniformity of film quality can be easily acquired. Consequently, it is possible to greatly suppress the generation of the disadvantageous situation in which image defects are caused by the generation of structural disorders on the reflection surface of the reflecting layer owing to the formation of a heterogeneous film or the generation of by-product projections on the surface.
With reference to the attached drawings, the best modes for implementing a radiation detecting apparatus, a manufacturing method thereof, a scintillator panel and a radiation detecting system according to the present invention are described below.
A radiation detecting apparatus according to the present embodiment includes a substrate, a phosphor layer formed on the substrate to be made of CsI:Tl having a columnar crystal, the phosphor layer converting a radiation into light, and a phosphor protecting member containing a phosphor protecting layer covering the phosphor layer, the phosphor protecting member adhering closely to the substrate. The phosphor protecting member includes the phosphor protecting layer made of an organic film formed by vapor deposition polymerization, a reflecting layer reflecting light converted by the phosphor layer, and a protecting layer for protecting the reflecting layer.
Here, referring to
The vapor deposition polymerization method is a method of vaporizing two monomers of a polymeric material acquired by a condensation polymerization reaction or by a polyaddition reaction simultaneously by a binary vapor deposition method to acquire a polymeric thin film by a polymerization reaction on a substrate. Because the amount of evaporation of each monomer can be independently controlled according to the sublimation temperature of each monomer in the method, it is possible to adjust the stoichiometric mixture ratio of a polymerized film to be optimum. Moreover, because the transportation of a monomer is performed by the same technique as that of the usual process of vacuum sublimation generation, the purity of a generated film is high, and the method does not include the processes of the addition, the removal, the recovery and the like of solvents (pollution-free). Consequently, it is known that a film with very little mixing of impurities can be obtained. That is, because the polymerization reaction is performed on the substrate, the generation of by-products is suppressed and the uniformity of film quality can be easily acquired in comparison with the radically polymerized film of the prior art.
As the combinations of two kinds of functional groups to be the two monomers to react in the vapor deposition polymerization method and the polymeric thin films (organic films) generated by the condensation polymerization or the polyaddition reaction of the two kinds of functional groups, the following ones shown in
1) polyimide produced by the condensation polymerization reaction of a monomer diamine component and dianhydride (
2) polyamide produced by the condensation polymerization reaction of a monomer diamine component and acid dichloride (
3) polyurea produced by the polyaddition reaction of a monomer diamine component and diisocyanate (
4) polyamide-imide produced by the condensation polymerization reaction of a monomer diamine component and diisocyanate,
5) polyazomethine produced by the condensation polymerization reaction of a monomer diamine component and dialdehyde (
6) polyurethane produced by the polyaddition reaction of a hydroquinone component and diphenylmethane diisocyanate (
7) polyester produced by the condensation polymerization reaction of hydroquinone and biphenyl carbonyl chloride (
The production of various polymeric thin films is enabled using these functional groups by changing the combination of the functional groups and the backbone structures of monomer molecules.
For example, as shown in
On the other hand, as shown in
Incidentally, because a dehydration reaction occurs in a film acquired by the condensation polymerization reaction and no dehydration reactions occur in a film acquired by the polyaddition reaction, the film acquired by polyaddition reaction (e.g. polyurea, polyurethane) is preferable as the phosphor protecting layer for protecting the phosphor layer of the columnar crystal structure having deliquescence in the present embodiment.
The radiation detecting apparatus shown in
The sensor panel 100 includes an insulative substrate 101, a light receiving unit composed of a plurality of photoelectric conversion elements 102 two-dimensionally arranged on the substrate 101 to convert the light converted by the phosphor layer 111 into an electric signal, and a sensor protecting layer 104 protecting the light receiving unit. The wiring 103 extending from the photoelectric conversion elements 102 is connected to a bonding pad portion (electrode extracting portion) 106. On the sensor protecting layer 104, the phosphor layer 111 is formed with a passivation layer 105 put between the phosphor layer 111 and the sensor protecting layer 104.
The phosphor protecting member 110 is composed of the phosphor protecting layer (humidity proof protecting layer) 116 protecting the phosphor layer 111, the reflecting layer 113 made of a metal film such as aluminum to reflect the light converted by the phosphor layer 111, and a protecting layer (humidity proof protecting layer) 117 protecting the reflecting layer 113. The reflecting layer 113 is provided for reflecting the light proceeding to the opposite side of the light receiving unit from the phosphor layer 111 to lead the light to the light receiving unit. The reflecting layer 113 is formed in a thin film state with a thickness of a submicron level by the methods such as vapor deposition.
The phosphor layer 111 made of CsI:Tl of a columnar crystal structure, and the humidity proof protection of the phosphor layer 111 from the exterior is implemented by the phosphor protecting member 110 (composed of the phosphor protecting layer 116, the reflecting layer 113 and the protecting layer 117).
By the configuration mentioned above, in the radiation detecting apparatus of the present embodiment, an X-ray having entered from the upper part of the drawing transmits the protecting layer 117, the reflecting layer 113 and the phosphor protecting layer 116, and is absorbed by the phosphor layer 111. After that, the light emitted from the phosphor layer 111 reaches the photoelectric conversion elements 102, and electric signals generated by the photoelectric conversion elements 102 are read by a not shown external circuit through the wiring 103. Then, the entered X-ray information is converted into a two-dimensional digital image.
In the radiation detecting apparatus according to the present embodiment, vapor deposition polymerization polyimide formed by the vapor deposition polymerization is applied as the phosphor protecting layer 116 in the upper part of the phosphor layer 111, and vapor deposition polymerization polyurea formed by the vapor deposition polymerization is applied as the protecting layer 117 on the reflecting layer 113, respectively.
Next, the manufacturing method of the radiation detecting apparatus according to the present embodiment is described.
As a general process, columnar structure phosphor CsI:Tl used as the phosphor layer 111 is vapor-deposited. After that, the phosphor protecting layer 116 is formed through an anneal process at 200° C. or more for Tl activation. On the other hand, in the present embodiment, after the vapor deposition of the phosphor CsI:Tl having the columnar crystal structure has been performed, the processing of the present embodiment shifts to a vapor deposition polymerization process of a phosphor protecting layer as it is, without passing any anneal processes.
In the vapor deposition polymerization process of the phosphor protecting layer, two kinds of reactive groups (monomers) used as raw materials, i.e. a monomer diamine component and a dianhydride, are heated in a vacuum using the vapor deposition polymerization method of the polyimide used as the phosphor protecting layer mentioned above, and the reactive groups are coevaporated on the substrate. Then, a condensation polymerization reaction is performed on the substrate through a dehydration cyclization reaction by heating. By the processing, the vapor deposition polymerization polyimide which becomes the phosphor protecting layer 116 is produced on the phosphor layer 111. In addition to it, a change to be imide and the activation of Tl in CsI:Tl of the phosphor layer 111 are simultaneously realized at the time of the change to be imide by heating at 200° C. or more in the process. It becomes also possible to suppress the generation of the deliquescence of CsI:Tl in the anneal process. Moreover, in order to suppress the generation of the adhesion of the vapor deposition polymerization polyimide to the bonding pad portion 106, the vapor deposition polymerization polyimide is formed, with the bonding pad portion 106 being masked by a substrate holder or the like.
Successively, the thin film of aluminum which becomes the reflecting layer 113 is formed by a method such as a sputtering method. The bonding pad portion 106 is also masked in this process.
Subsequently, using the vapor deposition polymerization method of the polyurea mentioned above, the two kinds of reactive groups (monomers) used as the raw materials, i.e. a monomer diamine component and diisocyanate, are severally heated in a vacuum, and are vaporized. By the processing, the polyaddition reaction is performed on the substrate and the polyurea to be the protecting layer 117 is vapor-deposited on the reflecting layer 113. The bonding pad portion 106 is masked also in this case. Because the substrate temperature is a room temperature at this time, it is possible to suppress the generation of the damage to the aluminum thin film, or the reflecting layer 113.
According to the present embodiment, the vapor deposition polymerization polyimide formed by the condensation polymerization reaction is used as the phosphor protecting layer, and the vapor deposition polymerization polyurea formed by the polyaddition reaction is used as the protecting layer, respectively. Consequently, the polymerization reactions of the organic films are performed on the substrate by the vapor deposition polymerization, and thereby the generation of by-products is suppressed and the uniformity of the film quality can be easily acquired in comparison with the Parylen formed by the prior art radical polymerization. Consequently, it is possible to greatly suppress the generation of the disadvantageous situation such that heterogeneous films are formed or projections owing to by-products are produced on the surface so that structural disorders are caused on the reflection surface of the reflecting layer to cause image defects.
In addition, in the present embodiment, polyimide and polyurea are used as the phosphor protecting layer and the protecting layer, respectively. However, the present invention is not limited to the above-mentioned materials, but the same effects can be acquired by using two different organic materials selected from the group of combinations of the organic materials such as polyurea, polyimide, polyamide, polyamide-imide, polyazomethine, polyester and polyurethane. However, as the phosphor protecting layer, as described above, the layer acquired by the polyaddition reaction (for example, polyurea, polyurethane and the like) is more preferable than the layer acquired by the condensation polymerization reaction (for example, polyimide, polyamide, polyazomethine, polyester and the like) owing to the existence of the dehydration reaction.
In the present embodiment, as shown in
Next, the manufacturing method of the radiation detecting apparatus according to the present embodiment is described.
First, by the same method as the prior art, the phosphor CsI:Tl which has a columnar crystal structure is formed, and annealing treatment thereof is carried out. Subsequently, the vapor deposition polymerization of polyurea is performed using the vapor deposition polymerization method of the polyurea mentioned above. At that time, as shown in
According to the present embodiment, because vapor deposition polymerization polyurea is used for both the phosphor protecting layer and the protecting layer, the same effects as those of the first embodiment can be acquired. In addition, because both the protecting layers are made by the polyaddition reaction, it is possible to obtain the phosphor protecting layer in which there is no generation of excessive impurities and the projections by by-products and the like are difficult to produce. Moreover, because the polyurea obtained by the polyaddition reaction is used as the phosphor protecting layer, it becomes possible to prevent the deliquescence of the phosphor layer which has the columnar crystal structure by the dehydration reaction. Moreover, the formation of the phosphor protecting layer in the bonding pad portion can be prevented by heating the bonding pad portion of the sensor panel at the time of vapor deposition polymerization.
In addition, in the present embodiment, polyurea is used as both of the phosphor protecting layer and the protecting layer. However, the present invention is not limited to the material, but the same effects can be acquired by using the two same organic materials selected from the group of combinations of the organic materials such as polyurea, polyimide, polyamide, polyamide-imide, polyazomethine, polyester and polyurethane. However, as the phosphor protecting layer, as described above, the layer acquired by the polyaddition reaction (for example, polyurea, polyurethane and the like) is more preferable than the layer acquired by the condensation polymerization reaction (for example, polyimide, polyamide, polyazomethine, polyester and the like) owing to the existence of the dehydration reaction.
In a radiation detecting apparatus of the present embodiment, vapor deposition polymerization polyimide is used as a phosphor protecting layer (thin film layer) 121 on the phosphor layer 111 made of CsI:Tl having a columnar crystal structure. Moreover, two layers of reflecting layers 122 and 123 are formed on the phosphor protecting layer 121. A moisture sealing layer 124 made of a silicone potting material is formed around the formed layers, and a radiation transmitting window 125 and a surrounding wall 126, both made of aluminum, are formed at the outermost circumference.
Consequently, also in the present embodiment, because vapor deposition polymerization polyimide is used for the phosphor protecting layer, the same effects as those of the first embodiment can be acquired.
Incidentally, when the phosphor protecting film 121 made of vapor deposition polymerization polyimide is formed to the protecting film 104 of the photoelectric conversion elements 102 as the present embodiment, the moisture sealing layer 124 may be omitted.
In addition, in the present embodiment, polyimide is used as the phosphor protecting layer. However, the present invention is not limited to the material, but the same effects can be acquired by using polyurea, polyamide, polyamide-imide, polyazomethine, polyester and polyurethane in addition to the polyimide. However, as the phosphor protecting layer, as described above, the layer acquired by the polyaddition reaction (for example, polyurea, polyurethane and the like) is more preferable than the layer acquired by the condensation polymerization reaction (for example, polyimide, polyamide, polyazomethine, polyester and the like) owing to the existence of the dehydration reaction.
In a radiation detecting apparatus according to the present embodiment, as shown in
The radiation detecting apparatus is one formed by pasting the scintillator panel 200 and the sensor panel 100 together with each other by a bonding layer 212.
Also in the present embodiment, because vapor deposition polymerization polyurea is used as the phosphor protecting layer, the defects are few, which is a feature of the vapor deposition polymerization organic film. Consequently, it is possible to remove optical artifacts.
In addition, in the present embodiment, polyurea acquired by the vapor deposition polymerization method is used as the phosphor protecting layer. However, the present invention is not limited to the material, but the same effects can be acquired by using polyimide, polyamide, polyamide-imide, polyazomethine, polyester, polyurethane and the like in addition to the polyurea. However, as the phosphor protecting layer, the layer acquired by the polyaddition reaction (for example, polyurea, polyurethane and the like) is more preferable than the layer acquired by the condensation polymerization reaction (for example, polyimide, polyamide, polyazomethine, polyester and the like) owing to the existence of the dehydration reaction.
In the radiation detecting system shown in
Moreover, the information can be transmitted to a remote place by transmission means such as a telephone line 6090 and the like, and the information can be displayed on a display 6081 in a doctor room or the like at another place, or the information can be saved in a recording medium such as an optical disc. It is also possible for a doctor at a remote place to perform the diagnosis of the image. Moreover, the image can be recorded on a film 6110 with a film processor 6100.
As described above, the present invention can be applied to a medical X-ray diagnosis apparatus and the like, and the invention is also effective in the case of being applied to nondestructive inspection and the like other than the medical X-ray diagnosis apparatus.
This application claims priority from Japanese Patent Application No. 2004-233420 filed on Aug. 10, 2004, which is hereby incorporated by reference herein.
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