JP4233087B2 - Manufacturing method of bioequivalent thermophosphor two-dimensional element - Google Patents
Manufacturing method of bioequivalent thermophosphor two-dimensional element Download PDFInfo
- Publication number
- JP4233087B2 JP4233087B2 JP2003107356A JP2003107356A JP4233087B2 JP 4233087 B2 JP4233087 B2 JP 4233087B2 JP 2003107356 A JP2003107356 A JP 2003107356A JP 2003107356 A JP2003107356 A JP 2003107356A JP 4233087 B2 JP4233087 B2 JP 4233087B2
- Authority
- JP
- Japan
- Prior art keywords
- thermophosphor
- bioequivalent
- resin
- dimensional element
- heat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Luminescent Compositions (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Description
【0001】
【発明の属する技術分野】
本発明は、生体等価型熱蛍光体二次元素子の製造方法に係わり、特に、放射線に対する相対感度の低下を抑制でき、局所被曝時の線量分布を精度良くかつ簡便に行える生体等価型熱蛍光体二次元素子の製造方法に関する。
【0002】
【従来の技術】
従来、放射線作業従事者等の個人被曝線量を計測する場合、均等全身被曝を想定し、胸部あるいは腹部に熱蛍光線量計(TLD)等の個人被曝線量計を装着して評価し、必要に応じて指先などに別の線量計を装着していた。しかし、近年の原子力利用技術の高度化に伴い、放射線源が多様化し、従来とは異なる形態、種類の放射線被曝を受けることが予想されるようになった。
【0003】
たとえば、再処理施設、高レベル放射性廃棄物貯蔵施設等の核燃料サイクル施設あるいは放射線利用の加速器施設においては、全身に均一に被曝するよりも身体部位により被曝線量が異なる場合が一般的である。しかも、被曝を受ける場所を事前に特定することは困難である。こうしたタイプの被曝を受けた場合、従来の一点型個人被曝線量計では的確な被曝評価は行えない。
【0004】
そこで、被曝線量計を一点型ではなくシート化(二次元素子化)することにより、局所被曝時の線量分布を精度良くかつ簡便に行うことができ、放射線源の多様化に応じた応答性の多様性と広いエネルギー測定域を有するものとし、被曝線量評価の精度を格段に向上させ、従事者等の被曝低減化に寄与することができる技術を開発することが求められている。
【0005】
【発明が解決しようとする課題】
上述したような技術としては、実効原子番号が人体と等価なフッ化リチウム(LiF)を母結晶とする熱蛍光体をシート化することにより、生体等価型熱蛍光体二次元素子を作製することが考えられる。すなわち、LiFにPTFE(四フッ化エチレン樹脂)を混合し、これをロール状に成型した後、360〜400℃で焼成し、切削(かつら剥ぎ)してキュア(加熱成型)することにより、生体等価型でシート化した熱蛍光体を作製するものである。
【0006】
上記のようにして作製された生体等価型熱蛍光体二次元素子に局所的にSr90の放射線を60分間、1Gyで照射し、局所被曝下での線量分布を測定した。この測定結果である線量分布を表す写真及びグラフを図4に示す。この測定結果によれば、放射線に対する相対感度が0.1まで低下してしまうことがわかる。相対感度が低下する原因には、PTFEを用いた場合に必須となる360〜400℃の焼成工程にあり、この工程の熱によって相対感度が低下してしまうことを確認した。
【0007】
本発明は上記のような事情を考慮してなされたものであり、その目的は、放射線に対する相対感度の低下を抑制でき、局所被曝時の線量分布を精度良くかつ簡便に行える生体等価型熱蛍光体二次元素子及びその製造方法を提供することにある。
【0008】
【課題を解決するための手段】
【0011】
本発明に係る生体等価型熱蛍光体二次元素子の製造方法は、LiFの単位重量に対し、バインダーとして耐熱性樹脂を5〜70重量%添加したものを主体としてシート形状に成型し、次いで260℃以下の温度で加熱硬化させることを特徴とする。
【0012】
ここで260℃以下の温度で加熱硬化させることができる耐熱性樹脂を用いるのは、260℃より高い温度で加熱硬化させると、そのときの熱によって生体等価型熱蛍光体二次元素子の相対感度が低下してしまうからである。言い換えると、相対感度が低下しないように260℃以下の温度で加熱硬化させることができる耐熱性樹脂を用いている。
【0013】
また、樹脂の添加量は、5重量%以下にするとバインダーとして機能せず、逆に70重量%以上にすると、加熱後の発光量が減少するので、5〜70重量%とすることが必要とされるものである。また、樹脂は、熱蛍光を透過させるように透光性を有することが望ましく、かつ測定時に熱を加える関係から耐熱性のものが望ましい。
【0014】
人体の被曝線量を測定するためには、生体組織等価性の点から、人体生体組織の実効原子番号である7.8に近似している8.2という実効原子番号を有するフッ化リチウム(LiF)を母体とする熱蛍光体を用いることによって、フィルタ処理をしなくてもそのまま使用できることとなる。
【0015】
上記生体等価型熱蛍光体二次元素子の製造方法によれば、LiFに対し、耐熱性樹脂を添加したものを主体としてシート形状に成型し、この成型品を260℃以下の温度で加熱硬化させるため、放射線に対する相対感度の低下を抑制できる。従って、局所被曝時の線量分布を精度良くかつ簡便に行える生体等価型熱蛍光体二次元素子を得ることが可能となる。
【0017】
また、本発明に係る生体等価型熱蛍光体二次元素子の製造方法において、前記樹脂は四フッ化エチレン−エチレン共重合樹脂、フッ化ビニリデン樹脂、三フッ化塩化エチレン樹脂のうちのいずれかであることも可能である。
【0018】
【発明の実施の形態】
以下、本発明の実施の形態について説明する。
(実施の形態1)
本発明に係る実施の形態1による生体等価型熱蛍光体二次元素子の製造方法について説明する。生体等価型熱蛍光体二次元素子は、実効原子番号が人体と等価なフッ化リチウム(LiF)を母結晶とする熱蛍光体をシート化することにより製造されるものである。
【0019】
まず、LiFに、モールディングパウダーとしての耐熱性樹脂(例えば四フッ化エチレン−エチレン共重合樹脂)を、Vタンブラー等によるドライブレンダーによって混合する。この混合時間は、ブレンダーの種類によって異なってくるものの、Vタンブラーを用いた場合には、15〜30分程度の混合時間で足りる。
【0020】
尚、この混合も、水性懸濁状態の耐熱性樹脂とLiFとを攪拌によってブレンドした後、脱水し、ブレンドした原材料を得ることも可能である。
【0021】
次いで、ブレンドした原材料を、均一になるように金型内部に収納し、成型圧力及び成型時間を調整しながら予備圧縮成型を行い、シート形状(二次元素子形状)の予備成型品を形成する。成型圧力は、成型品の厚さ、耐熱性樹脂の種類、粒度等によって異なるものの、おおむね100〜400Kg/cm2の範囲である。さらに成型時間は、成型品の厚さが増加するにつれて長時間とすることが必要とされるが、少なくとも耐熱性樹脂単独での成型時間、またはその時間よりも若干長い時間とすることが望ましい。
【0022】
その後、この予備成型品を、240〜260℃に調整された炉の中で、成型品の形状、耐熱性樹脂の種類、粒度に応じて調整した時間だけ焼成する。この後は、充分に小さい冷却速度にて室温まで冷却した後、更に、2日又は3日以上室温で放置する。このようにして生体等価型熱蛍光体二次元素子が製造される。
【0023】
上記実施の形態1によれば、LiFを母体とする熱蛍光体と耐熱性樹脂を混合した後、この混合物をシート形状に予備成型し、この成型品を加熱処理する温度を240〜260℃としている。このため、放射線に対する相対感度の低下を抑制できる。従って、局所被曝時の線量分布を精度良くかつ簡便に行える生体等価型熱蛍光体二次元素子を得ることが可能となる。
【0024】
(参考形態)
本発明の参考形態による生体等価型熱蛍光体二次元素子の製造方法について説明する。耐熱性樹脂をバインダーとし、圧縮成型によって成型シートを製造する方法である。
【0025】
まず、実施の形態1と同様のブレンドした原材料を用意する。
【0026】
次いで、ブレンドした原材料を、均一になるように金型内部に収納し、成型圧力及び成型時間を調整しながら予備圧縮成型を行う。成型圧力は、成型品の厚さ、耐熱性樹脂の種類、粒度等によって異なるものの、おおむね100〜400Kg/cm2の範囲である。さらに成型時間は、成型品の厚さが増加するにつれて長時間とすることが必要とされるが、少なくとも耐熱性樹脂単独での成型時間、またはその時間よりも若干長い時間とすることが望ましい。
【0027】
その後、この予備成型品を、240〜260℃に調整された炉の中で、成型品の形状、耐熱性樹脂の種類、粒度に応じて調整した時間だけ焼成する。この後は、充分に小さい冷却速度にて室温まで冷却した後、更に、2日又は3日以上室温で放置し、その後、この成型品を、スライサーによって所定厚にスライスしてシート形状にするものである。
【0029】
尚、本発明は上記実施の形態に限定されず、本発明の主旨を逸脱しない範囲内で種々変更して実施することが可能である。
【0030】
【実施例】
以下、図面を参照して本発明の実施例について説明する。
(実施例1)
図1(A)〜(C)は、本発明に係る実施例1による生体等価型熱蛍光体二次元素子の製造方法を説明する断面図である。図2は、図1(A)に示す金型を上から視た平面図である。生体等価型熱蛍光体二次元素子は、実効原子番号が人体と等価なフッ化リチウム(LiF)を母結晶とする熱蛍光体をシート化することにより製造するものである。
【0031】
まず、図1(A)及び図2に示す金型2を準備する。この金型2は、平面形状が略四角形を有しており、深さ200μm程度の溝(窪み)1を有する鉄板からなる。この金型2の表面(少なくとも溝1の内表面)はフッ素樹脂でコーティングされており、このフッ素樹脂によって生体等価型熱蛍光体二次元素子が溝1の内表面に付着しないようになっている。
【0032】
次に、熱蛍光体は、粉末状のLiFに対して、付活剤としてMg、Cu、Pを微量混合し、これを温度700〜1000℃で、30分〜1時間熱処理を施し、その後80メッシュ以下150メッシュ以上の粒子を選別して、水あるいは希釈塩酸で洗浄後、乾燥させたものを0.4kg用意する。
【0033】
また、バインダーとしての四フッ化エチレン−エチレン共重合樹脂は、モールディングパウダーとしての市販品フルオンETFE Z-885A:旭硝子(株)製を0.6kg用意する。次いで、これら両者をVタンブラーへ入れて、20分間混合する。これにより、LiFを母体とする熱蛍光体と四フッ化エチレン−エチレン共重合樹脂が4:6の混合比で混合される。
【0034】
その後、図1(B)に示すように、金型2の溝1内に上記の混合物3を塗布する。次いで、図1(C)に示すように、金型2の溝1の上に蓋部4を載せ、この蓋部4を250Kg/cm2の圧力で30秒間加圧し、シート形状(二次元素子形状)の予備成型品3aを形成する。次いで、この予備成型品3aを金型2とともに熱風加熱炉に移す。
【0035】
その後、金型2を収納した加熱炉を徐々に加熱し、250℃に到達後、30分〜1時間保持し、室温まで徐冷する。このようにして得られた成型品を金型2から剥離することにより、生体等価型熱蛍光体二次元素子を得た。このようにして得た熱蛍光体シートは十分に使用に耐えるものであった。
【0036】
このようにして製造された生体等価型熱蛍光体二次元素子は、熱蛍光体の母結晶としてLiFを用い、粒径が数〜100μmであり、実効原子番号が8.14であり、発光波長が390nmであり、グローピーク温度が210℃であり、測定線量範囲が10−5〜102Svであり、エネルギー特性(レスポンス)が約1.3(40keV/60Co)であり、フェーディング特性が5%/3ヶ月以内であり、環境温湿度が5%以内であり、光励起がほとんど無く、光クエンチングがほとんど無いものである。
【0037】
上記生体等価型熱蛍光体二次元素子に局所的にSr90の放射線を60分間、0.5Gyで照射し、局所被曝下での線量分布を測定した。この測定結果である線量分布を表す写真及びグラフを図3に示す。この測定結果によれば、相対感度が1であり、図4に示す従来の生体等価型熱蛍光体二次元素子の相対感度0.1に比べて相対感度の低下を抑制できることが確認された。
【0038】
上記実施例1では、LiFを母体とする熱蛍光体と四フッ化エチレン−エチレン共重合樹脂を混合した後、この混合物をシート形状に予備成型し、この成型品を加熱処理する温度を250℃としている。このため、放射線に対する相対感度の低下を抑制できる。従って、局所被曝時の線量分布を精度良くかつ簡便に行える生体等価型熱蛍光体二次元素子を得ることが可能となる。
【0039】
(参考例)
本発明の参考例による生体等価型熱蛍光体二次元素子の製造方法について説明する。
熱蛍光体としてLiFを母体とするものを用い、耐熱性樹脂として四フッ化エチレン−エチレン共重合樹脂を用い、かつ両者を4:6の混合比で混合し、平面形状が200mm×500mmで0.4mm厚の生体等価型熱蛍光体シートを約100枚製造する場合について説明する。
【0040】
まず、実施例1と同様の熱蛍光体を7.2kg用意する。また、実施例1と同様のバインダーとしての四フッ化エチレン−エチレン共重合樹脂を10.8kg用意する。次いで、これら両者をVタンブラーへ入れて、20分間混合する。
【0041】
その後、上記混合物を金型の内部に収納し、250Kg/cm2の圧力で30秒間加圧し、予備成型品を形成する。次いで、この予備成型品が十分な強度がないために、注意深く熱風加熱炉に移す。
【0042】
その後、予備成型品を収納した加熱炉を徐々に加熱し、250℃に到達後、30分〜1時間保持し、室温まで徐冷する。このようにして得られた成型品をスライサーで0.4mmの厚さにスライスして生体等価型熱蛍光体シートを得た。このようにして得た熱蛍光体シートは十分に使用に耐えるものであった。
【0044】
尚、本発明は上記実施例に限定されず、本発明の主旨を逸脱しない範囲内で種々変更して実施することが可能である。例えば、上記実施例では、耐熱性樹脂として四フッ化エチレン−エチレン共重合樹脂を用いているが、260℃以下の温度で加熱硬化する耐熱性樹脂であれば、他の耐熱性樹脂を用いることも可能であり、例えば、フッ化ビニリデン樹脂、三フッ化塩化エチレン樹脂、四フッ化エチレン樹脂、パーフルオロ−アルコキシ樹脂、四フッ化エチレン−六フッ化プロピレン共重合樹脂などを用いることも可能である。
【0045】
【発明の効果】
以上説明したように本発明によれば、放射線に対する相対感度の低下を抑制でき、局所被曝時の線量分布を精度良くかつ簡便に行える生体等価型熱蛍光体二次元素子及びその製造方法を提供することができる。
【図面の簡単な説明】
【図1】(A)〜(C)は、本発明に係る実施例1による生体等価型熱蛍光体二次元素子の製造方法を説明する断面図である。
【図2】図1(A)に示す金型を上から視た平面図である。
【図3】本発明に係る実施例1による生体等価型熱蛍光体二次元素子に局所的に放射線を照射し、局所被曝下での線量分布を示す写真及びグラフである。
【図4】従来の生体等価型熱蛍光体二次元素子に局所的に放射線を照射し、局所被曝下での線量分布を示す写真及びグラフである。
【符号の説明】
1…溝(窪み)
2…金型
3…混合物(LiFを母体とする熱蛍光体と四フッ化エチレン−エチレン共重合樹脂の混合物)
3a…予備成型品
4…蓋部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a bioequivalent thermophosphor two-dimensional element , and more particularly, a bioequivalent thermophosphor that can suppress a decrease in relative sensitivity to radiation and can accurately and easily perform dose distribution during local exposure. The present invention relates to a method for manufacturing a two-dimensional element .
[0002]
[Prior art]
Conventionally, when measuring individual doses of radiation workers, etc., it is assumed that uniform whole body exposure is assumed, and an individual dose meter such as a thermofluorescence dosimeter (TLD) is attached to the chest or abdomen for evaluation. And another dosimeter was attached to the fingertip. However, with the advancement of nuclear power technology in recent years, radiation sources have diversified, and it is expected that they will be exposed to different forms and types of radiation.
[0003]
For example, in a nuclear fuel cycle facility such as a reprocessing facility, a high-level radioactive waste storage facility, or an accelerator facility using radiation, the radiation dose is generally different depending on the body part rather than being uniformly exposed to the whole body. Moreover, it is difficult to specify in advance the place to receive exposure. When such a type of exposure is received, an accurate exposure evaluation cannot be performed with a conventional single-point individual dose meter.
[0004]
Therefore, by making the dosimeter into a sheet (two-dimensional element) instead of a single point type, the dose distribution at the time of local exposure can be performed accurately and simply, and the responsiveness according to the diversification of radiation sources There is a need to develop technologies that have diversity and a wide energy measurement range, can significantly improve the accuracy of dose assessment, and contribute to reducing the exposure of workers and others.
[0005]
[Problems to be solved by the invention]
As a technique as described above, a bioequivalent thermophosphor two-dimensional element is manufactured by forming a thermophosphor having an effective atomic number of lithium fluoride (LiF) equivalent to a human body as a mother crystal. Can be considered. That is, PTFE (tetrafluoroethylene resin) is mixed with LiF, molded into a roll, fired at 360-400 ° C., cut (wig removed), and cured (heat-molded). An equivalent type sheet of thermophosphor is produced.
[0006]
The bioequivalent thermophosphor two-dimensional element produced as described above was locally irradiated with Sr90 radiation at 1 Gy for 60 minutes, and the dose distribution under local exposure was measured. FIG. 4 shows a photograph and a graph showing the dose distribution as the measurement result. According to this measurement result, it can be seen that the relative sensitivity to radiation decreases to 0.1. The cause of the decrease in relative sensitivity is in the baking process at 360 to 400 ° C., which is essential when PTFE is used, and it was confirmed that the relative sensitivity is decreased by the heat of this process.
[0007]
The present invention has been made in consideration of the above-described circumstances, and its purpose is to suppress a decrease in relative sensitivity to radiation, and to perform bioequivalent thermoluminescence that can accurately and easily perform dose distribution during local exposure. The object is to provide a two-dimensional body element and a method for manufacturing the same.
[0008]
[Means for Solving the Problems]
[0011]
In the method for producing a two-dimensional bioequivalent thermophosphor according to the present invention, a material obtained by adding 5 to 70% by weight of a heat-resistant resin as a binder to the unit weight of LiF is molded into a sheet shape, and then 260. It is characterized by being heat-cured at a temperature of ℃ or less.
[0012]
Here, the heat-resistant resin that can be heat-cured at a temperature of 260 ° C. or lower is used when the heat-cured resin is heat-cured at a temperature higher than 260 ° C., and the relative sensitivity of the two-dimensional bioequivalent thermophosphor by the heat at that time. It is because it will fall. In other words, a heat-resistant resin that can be heat-cured at a temperature of 260 ° C. or lower is used so that the relative sensitivity does not decrease.
[0013]
Further, if the amount of the resin added is 5% by weight or less, it does not function as a binder, and conversely if it is 70% by weight or more, the amount of light emission after heating is reduced. It is what is done. Further, it is desirable that the resin has translucency so as to transmit thermofluorescence, and it is desirable that the resin be heat resistant because heat is applied during measurement.
[0014]
In order to measure the exposure dose of the human body, from the viewpoint of biological tissue equivalence, lithium fluoride (LiF) having an effective atomic number of 8.2 which is close to 7.8 which is an effective atomic number of the human biological tissue. ) Can be used as they are without filtering.
[0015]
According to the above-described method for producing a two-dimensional bioequivalent thermoluminescent material, LiF is molded into a sheet shape mainly composed of a heat-resistant resin added, and the molded product is heated and cured at a temperature of 260 ° C. or lower. Therefore, a decrease in relative sensitivity to radiation can be suppressed. Accordingly, it is possible to obtain a bioequivalent thermophosphor two-dimensional element that can accurately and easily perform dose distribution during local exposure.
[0017]
Further, in the method for manufacturing a bioequivalent thermophosphor two-dimensional element according to the present invention, the resin is one of ethylene tetrafluoride-ethylene copolymer resin, vinylidene fluoride resin, and ethylene trifluoride chloride resin. It is also possible.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
(Embodiment 1)
A method for manufacturing a bioequivalent thermophosphor two-dimensional element according to Embodiment 1 of the present invention will be described. The bioequivalent thermophosphor two-dimensional element is manufactured by forming a thermophosphor having a mother crystal of lithium fluoride (LiF) whose effective atomic number is equivalent to that of a human body.
[0019]
First, a heat resistant resin (for example, a tetrafluoroethylene-ethylene copolymer resin) as a molding powder is mixed with LiF by a drive render such as a V tumbler. Although the mixing time varies depending on the type of blender, when a V tumbler is used, a mixing time of about 15 to 30 minutes is sufficient.
[0020]
In this mixing, the heat-resistant resin in an aqueous suspension and LiF can be blended by stirring and then dehydrated to obtain a blended raw material.
[0021]
Next, the blended raw materials are stored in the mold so as to be uniform, and pre-compression molding is performed while adjusting the molding pressure and molding time to form a sheet-shaped (two-dimensional element shape) preform. Although the molding pressure varies depending on the thickness of the molded product, the type of heat-resistant resin, the particle size, etc., it is generally in the range of 100 to 400 Kg / cm 2 . Further, the molding time is required to be longer as the thickness of the molded product increases, but it is desirable that the molding time be at least a molding time with the heat resistant resin alone or a little longer than that time.
[0022]
Thereafter, the preform is fired in a furnace adjusted to 240 to 260 ° C. for a time adjusted according to the shape of the molded product, the type of heat-resistant resin, and the particle size. After this, after cooling to room temperature at a sufficiently low cooling rate, the mixture is further allowed to stand at room temperature for 2 days or 3 days. In this way, a bioequivalent thermophosphor two-dimensional element is manufactured.
[0023]
According to the first embodiment, after mixing a thermoluminescent material based on LiF and a heat-resistant resin, the mixture is preformed into a sheet shape, and the temperature at which the molded product is heat-treated is set to 240 to 260 ° C. Yes. For this reason, the fall of the relative sensitivity with respect to a radiation can be suppressed. Accordingly, it is possible to obtain a bioequivalent thermophosphor two-dimensional element that can accurately and easily perform dose distribution during local exposure.
[0024]
( Reference form )
A method for manufacturing a bioequivalent thermophosphor two-dimensional element according to a reference embodiment of the present invention will be described. This is a method for producing a molded sheet by compression molding using a heat-resistant resin as a binder.
[0025]
First, the same raw material blended as in the first embodiment is prepared.
[0026]
Next, the blended raw materials are accommodated inside the mold so as to be uniform, and preliminary compression molding is performed while adjusting the molding pressure and molding time. Although the molding pressure varies depending on the thickness of the molded product, the type of heat-resistant resin, the particle size, etc., it is generally in the range of 100 to 400 Kg / cm 2 . Further, the molding time is required to be longer as the thickness of the molded product increases, but it is desirable that the molding time be at least a molding time with the heat resistant resin alone or a little longer than that time.
[0027]
Thereafter, the preform is fired in a furnace adjusted to 240 to 260 ° C. for a time adjusted according to the shape of the molded product, the type of heat-resistant resin, and the particle size. After this, after cooling to room temperature at a sufficiently low cooling rate, it is further left to stand at room temperature for 2 or 3 days, and then this molded product is sliced to a predetermined thickness by a slicer to form a sheet It is.
[0029]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
[0030]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
Example 1
FIGS. 1A to 1C are cross-sectional views illustrating a method for manufacturing a two-dimensional bioequivalent thermophosphor element according to Example 1 of the present invention. FIG. 2 is a plan view of the mold shown in FIG. The bioequivalent thermophosphor two-dimensional element is manufactured by forming a thermophosphor having a base crystal of lithium fluoride (LiF) whose effective atomic number is equivalent to that of a human body.
[0031]
First, the metal mold | die 2 shown to FIG. 1 (A) and FIG. 2 is prepared. The
[0032]
Next, the thermoluminescent material is mixed with a small amount of Mg, Cu, P as an activator to the powdered LiF, subjected to heat treatment at a temperature of 700 to 1000 ° C. for 30 minutes to 1 hour, and then 80 0.4 kg of particles having a mesh size of 150 mesh or more are selected, washed with water or diluted hydrochloric acid, and dried.
[0033]
Further, 0.6 kg of commercially available full-on ETFE Z-885A: Asahi Glass Co., Ltd. as a molding powder is prepared as the tetrafluoroethylene-ethylene copolymer resin as the binder. The two are then placed in a V tumbler and mixed for 20 minutes. As a result, the thermoluminescent material based on LiF and the tetrafluoroethylene-ethylene copolymer resin are mixed at a mixing ratio of 4: 6.
[0034]
Thereafter, as shown in FIG. 1B, the
[0035]
Then, the heating furnace which accommodated the metal mold | die 2 is heated gradually, and after reaching | attaining 250 degreeC, it hold | maintains for 30 minutes-1 hour, and cools slowly to room temperature. The molded product thus obtained was peeled from the
[0036]
The bioequivalent thermophosphor two-dimensional element manufactured in this way uses LiF as a mother crystal of the thermophosphor, has a particle size of several to 100 μm, an effective atomic number of 8.14, and an emission wavelength. Is 390 nm, glow peak temperature is 210 ° C., measurement dose range is 10 −5 to 10 2 Sv, energy characteristic (response) is about 1.3 (40 keV / 60 Co), fading characteristic Is within 5% / 3 months, the ambient temperature and humidity are within 5%, there is almost no photoexcitation, and there is almost no photoquenching.
[0037]
The biological equivalent type thermophosphor two-dimensional element was locally irradiated with Sr90 radiation at 0.5 Gy for 60 minutes, and the dose distribution under local exposure was measured. A photograph and a graph showing the dose distribution as the measurement result are shown in FIG. According to this measurement result, it was confirmed that the relative sensitivity was 1, and a decrease in relative sensitivity could be suppressed as compared with the relative sensitivity 0.1 of the conventional bioequivalent thermophosphor two-dimensional element shown in FIG.
[0038]
In Example 1 above, after mixing a thermoluminescent material based on LiF and a tetrafluoroethylene-ethylene copolymer resin, this mixture is preformed into a sheet shape, and the temperature at which this molded product is heat-treated is 250 ° C. It is said. For this reason, the fall of the relative sensitivity with respect to a radiation can be suppressed. Accordingly, it is possible to obtain a bioequivalent thermophosphor two-dimensional element that can accurately and easily perform dose distribution during local exposure.
[0039]
( Reference example )
A method for manufacturing a bioequivalent thermophosphor two-dimensional element according to a reference example of the present invention will be described.
A material based on LiF is used as a thermoluminescent material, an ethylene tetrafluoride-ethylene copolymer resin is used as a heat-resistant resin, and both are mixed at a mixing ratio of 4: 6. A case where about 100 bio-equivalent thermophosphor sheets having a thickness of 4 mm are manufactured will be described.
[0040]
First, 7.2 kg of the same thermophosphor as in Example 1 is prepared. Moreover, 10.8 kg of tetrafluoroethylene-ethylene copolymer resin as a binder similar to Example 1 is prepared. The two are then placed in a V tumbler and mixed for 20 minutes.
[0041]
Thereafter, the above mixture is accommodated in a mold and pressurized at a pressure of 250 kg / cm 2 for 30 seconds to form a preformed product. The preform is then carefully transferred to a hot air oven because it is not strong enough.
[0042]
Thereafter, the heating furnace containing the preform is gradually heated and, after reaching 250 ° C., held for 30 minutes to 1 hour and gradually cooled to room temperature. The molded product thus obtained was sliced to a thickness of 0.4 mm with a slicer to obtain a bioequivalent thermophosphor sheet. The thermophosphor sheet thus obtained was sufficiently durable for use.
[0044]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, tetrafluoroethylene-ethylene copolymer resin is used as the heat resistant resin, but other heat resistant resins may be used as long as they are heat resistant resins that are cured by heating at a temperature of 260 ° C. or lower. For example, vinylidene fluoride resin, trifluoroethylene chloride resin, tetrafluoroethylene resin, perfluoro-alkoxy resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, etc. can be used. is there.
[0045]
【The invention's effect】
As described above, according to the present invention, it is possible to suppress a decrease in relative sensitivity to radiation, and to provide a bioequivalent thermophosphor two-dimensional element capable of accurately and simply performing dose distribution at the time of local exposure and a method for manufacturing the same. be able to.
[Brief description of the drawings]
FIGS. 1A to 1C are cross-sectional views illustrating a method for manufacturing a bioequivalent thermoluminescent two-dimensional element according to Example 1 of the present invention.
FIG. 2 is a plan view of the mold shown in FIG. 1 (A) as viewed from above.
FIGS. 3A and 3B are a photograph and a graph showing a dose distribution under local exposure by locally irradiating a biological equivalent type thermophosphor two-dimensional element according to Example 1 of the present invention. FIGS.
FIG. 4 is a photograph and a graph showing a dose distribution under local exposure by locally irradiating a conventional bioequivalent thermophosphor two-dimensional element with radiation.
[Explanation of symbols]
1 ... groove
2 ...
3a ... preformed
Claims (2)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003107356A JP4233087B2 (en) | 2003-04-11 | 2003-04-11 | Manufacturing method of bioequivalent thermophosphor two-dimensional element |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003107356A JP4233087B2 (en) | 2003-04-11 | 2003-04-11 | Manufacturing method of bioequivalent thermophosphor two-dimensional element |
Publications (2)
Publication Number | Publication Date |
---|---|
JP2004317136A JP2004317136A (en) | 2004-11-11 |
JP4233087B2 true JP4233087B2 (en) | 2009-03-04 |
Family
ID=33469212
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2003107356A Expired - Fee Related JP4233087B2 (en) | 2003-04-11 | 2003-04-11 | Manufacturing method of bioequivalent thermophosphor two-dimensional element |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP4233087B2 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007139435A (en) * | 2005-11-15 | 2007-06-07 | Mitsubishi Electric Corp | Radiation monitor |
JP5185515B2 (en) * | 2006-09-06 | 2013-04-17 | オリンパスメディカルシステムズ株式会社 | Fluorescent subject |
JP5863123B2 (en) | 2011-03-31 | 2016-02-16 | 学校法人立教学院 | Silver-containing lithium heptaborate photostimulable phosphor, method for producing the same, and laminate using the photostimulable phosphor |
JP7095937B2 (en) * | 2018-03-09 | 2022-07-05 | ミネベアミツミ株式会社 | Manufacturing method of fluorescent sheet |
JP7347292B2 (en) * | 2019-09-27 | 2023-09-20 | 東レ株式会社 | radiation detector |
-
2003
- 2003-04-11 JP JP2003107356A patent/JP4233087B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JP2004317136A (en) | 2004-11-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Kennedy et al. | Experimental and Monte Carlo determination of the TG‐43 dosimetric parameters for the model 9011 THINSeed™ brachytherapy source | |
JP4457219B1 (en) | Thermoluminescent laminate, thermoluminescent plate, method for producing thermoluminescent laminate, method for producing thermoluminescent plate, and method for obtaining three-dimensional dose distribution of radiation | |
JP4431701B1 (en) | Method for producing thermoluminescent plate, method for producing thermoluminescent laminate, thermoluminescent plate, and thermoluminescent laminate | |
JP4233087B2 (en) | Manufacturing method of bioequivalent thermophosphor two-dimensional element | |
US20140023842A1 (en) | Silver-containing lithium heptaborate photostimulable phosphor, method for producing same, and laminate using said photostimulable phosphor | |
US3471699A (en) | Phosphor-polytetrafluoroethylene thermoluminescent dosimeter | |
WO2010064594A1 (en) | Thermofluorescent stack, thermofluorescent plate, process for producing thermoflorescent stack, process for producing thermofluorescent plate, and method of acquiring three-dimensional radiation dose distribution | |
Salah et al. | The influence of high-energy 7Li ions on the TL response and glow curve structure of CaSO4: Dy | |
Eyadeh et al. | Measurement of skin surface dose distributions in radiation therapy using poly (vinyl alcohol) cryogel dosimeters | |
Solberg et al. | Dosimetric parameters of three new solid core I‐125 brachytherapy sources | |
Kunert et al. | Tissue equivalence of 3D printing materials with respect to attenuation and absorption of X‐rays used for diagnostic and interventional imaging | |
Kłosowski et al. | Novel thermoluminescence foils for 2-D clinical dosimetry, based on CaSO4: Dy | |
Aoyama et al. | Physical and dosimetric characterization of thermoset shape memory bolus developed for radiotherapy | |
JP3853614B2 (en) | Manufacturing method of CaSO4 series TL device mixed with phosphorus compound | |
JP5692883B1 (en) | Thermophosphor and thermoluminescent radiation detection device | |
Asfia et al. | Infill selection for 3D printed radiotherapy immobilisation devices | |
JPS61269100A (en) | Thermal fluorescent sheet | |
Barbina et al. | Preliminary results on dosimetric properties op MgB4O7: Dy | |
Nilsson et al. | Build-up effects at air cavities measured with thin thermoluminescent dosimeters | |
Lakshmanan et al. | High-level gamma-ray dosimetry using common TLD phosphors | |
US4290909A (en) | Process for producing a lithium borate thermoluminescent and fluorescent substance | |
Santos et al. | Development of a realistic 3D printed eye lens dosemeter using CAD integrated with Monte Carlo simulation | |
KR100450154B1 (en) | Manufacturing method of far-infrared-and-negative-ion-emitting machine | |
Szpala et al. | Calorimeter measurements of absolute dose in aluminum, a surrogate of bone, to validate dose-to-medium in Acuros XB | |
JP2008256404A (en) | Thermofluorescent dose measuring element |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060407 |
|
A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20080730 |
|
A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080805 |
|
A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20081006 |
|
TRDD | Decision of grant or rejection written | ||
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20081118 |
|
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20081208 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111219 Year of fee payment: 3 |
|
R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111219 Year of fee payment: 3 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20141219 Year of fee payment: 6 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20141219 Year of fee payment: 6 |
|
S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20141219 Year of fee payment: 6 |
|
LAPS | Cancellation because of no payment of annual fees | ||
S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
R370 | Written measure of declining of transfer procedure |
Free format text: JAPANESE INTERMEDIATE CODE: R370 |