JPH06316494A - Single crystal for scintillator - Google Patents
Single crystal for scintillatorInfo
- Publication number
- JPH06316494A JPH06316494A JP5123058A JP12305893A JPH06316494A JP H06316494 A JPH06316494 A JP H06316494A JP 5123058 A JP5123058 A JP 5123058A JP 12305893 A JP12305893 A JP 12305893A JP H06316494 A JPH06316494 A JP H06316494A
- Authority
- JP
- Japan
- Prior art keywords
- scintillator
- single crystal
- crystal
- ray
- additive
- 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.)
- Pending
Links
- 239000013078 crystal Substances 0.000 title claims abstract description 29
- 229910052688 Gadolinium Inorganic materials 0.000 claims abstract description 7
- 239000000654 additive Substances 0.000 claims abstract description 6
- 230000000996 additive effect Effects 0.000 claims abstract description 6
- -1 gadolinium aluminate Chemical class 0.000 claims abstract description 5
- 229910052751 metal Inorganic materials 0.000 claims abstract description 3
- 239000002184 metal Substances 0.000 claims abstract description 3
- 229910052684 Cerium Inorganic materials 0.000 claims description 2
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 2
- 229910052793 cadmium Inorganic materials 0.000 claims 1
- 229910052748 manganese Inorganic materials 0.000 claims 1
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000012010 growth Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000003325 tomography Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000010261 cell growth Effects 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000001917 fluorescence detection Methods 0.000 description 1
- 230000005251 gamma ray Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、Ｘ線ＣＴ用シンチレ
ーター等に有効なシンチレーター用単結晶に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scintillator single crystal effective for an X-ray CT scintillator and the like.
【０００２】[0002]
【従来の技術】従来より、酸化物シンチレーター、例え
ばＮａＩ：Ｔｌ結晶シンチレーター、ＢＧＯ（Ｂｉ4 Ｇ
ｅ3 Ｏ12）結晶シンチレーター、ＣＷＯ（ＣｄＷＯ4 ）
結晶シンチレーター及びＧｄ2 Ｏ2 Ｓ：Ｐｒセラミック
ス結晶シンチレーターは、Ｘ線ＣＴ（断層撮影装置）の
検出器及びポジトロンＣＴ（陽電子放出核種断層撮影装
置）の検出器、中高エネルギー物理研究のγ線検出器等
に使用されていることが知られている。2. Description of the Related Art Conventionally, oxide scintillators such as NaI: Tl crystal scintillator, BGO (Bi 4 G)
e 3 O 12) crystal scintillator, CWO (CdWO 4)
Crystal scintillators and Gd 2 O 2 S: Pr ceramics crystal scintillators are X-ray CT (tomography) detectors, positron CT (positron emission nuclide tomography detectors) detectors, and γ-ray detectors for mid-high energy physics research. It is known to be used for
【０００３】[0003]
【発明が解決しようとする課題】例えばＸ線ＣＴの検出
器用シンチレーターとして要求される特性は、第１に蛍
光出力が大きいこと、第２に減衰時間が短く、残光性が
小さいこと、第３にＸ線の吸収率が大きいことである。
現在のＸ線ＣＴの検出器の傾向としては、画像の分解能
力の向上と高速化にあると言われている。空間分解能力
の向上は、検出素子を小型にして多くの情報を入力する
ことにより、また高速化は多数個の検出器を放射状に並
べてＸ線源を高速に回転移動させることにより実現させ
ている。したがって小型化に寄与する特性も要求され
る。For example, the characteristics required as a scintillator for a detector of X-ray CT are firstly a large fluorescence output, secondly a short decay time and a small afterglow, and a third. That is, the X-ray absorption rate is high.
It is said that the current tendency of X-ray CT detectors is to improve the resolution of images and increase the speed. The spatial resolution is improved by reducing the size of the detection element and inputting a lot of information, and the speedup is achieved by arranging a large number of detectors radially and rotating the X-ray source at high speed. . Therefore, characteristics that contribute to miniaturization are also required.
【０００４】またポジトロンＣＴ用シンチレーターにお
いて要求される特性は、第１に人体に投射したＲＩの陽
電子消滅に伴なって放射されるγ線の捕捉効率を高める
ために吸収率が大きいこと、第２に蛍光出力が大きいこ
と、第３に同時計測の時間分解能力が良いことである。
ポジトロンＣＴの空間分解能力を高めるためにはできる
だけ多くの検出器を使用する必要があり、そのために吸
収率は特に重要である。蛍光出力が大きいとエネルギ分
解能力が良くなり、良好な時間分解能力を示す関係が生
じる。The characteristics required of the scintillator for positron CT are, firstly, that the absorptivity is large in order to enhance the trapping efficiency of γ-rays emitted along with the annihilation of positrons of the RI projected on the human body. First, the fluorescence output is large, and thirdly, the time resolution capability of simultaneous measurement is good.
It is necessary to use as many detectors as possible in order to enhance the spatial resolution capacity of the positron CT, and therefore the absorption rate is particularly important. When the fluorescence output is large, the energy resolving ability is improved, and a relationship showing good time resolving ability is generated.
【０００５】ところで、ＮａＩ：Ｔｌ単結晶は、Ｘ線Ｃ
ＴやポジトロンＣＴの検出器用シンチレーターとして用
いられていたが、残光性があって、画像に悪影響を及ぼ
し、しかも吸湿性があるので、シールする必要が生じ
て、検出器を小型化できにくい欠点がある。ＢＧＯ（Ｂ
ｉ4 Ｇｅ3 Ｏ12）単結晶は、Ｘ線ＣＴの検出器に使用さ
れていたが、最近ではγ線を応用した医療機器（例えば
ポジトロンＣＴ）や欠陥検査等の装置の検出器、さらに
原子核実験や高エネルギ素粒子実験用としてに使用され
ているが、蛍光出力が小さいので、ポジトロンＣＴ用に
使用する場合には十分な電気的出力を得る必要から蛍光
の検出に光電子増倍管（ＰＭＴ）が必要となり、Ｓｉフ
ォトダイオード（ＳＰＤ）とを組合せた小型検出器がで
きない欠点がある。ＢＧＯは、融点が１０４４°Ｃであ
り、メルトの粘度は非常に高く、過冷却が起り易く、通
常の冷却速度では融点の３００°Ｃ以下でも凝固せず、
メルトのまま保持される。このために、結晶の成長速度
を大きくできず、そしてセルの成長に伴なってパイプ状
の気泡が発生しやすく、加工上の問題がある。ＣＷＯ
（ＣｄＷＯ4 ）単結晶はＸ線ＣＴの検出器に使用されて
いるが、発光効率が低く、小型化に難がある。発光効率
を高くするためには、結晶の成長速度を遅くしたり、高
い純度の原材料を使用しなければならなので、製造コス
トが高くなる問題が新たに生じる。Ｇｄ2 Ｏ2 Ｓ：Ｐｒ
は発光効率が高いが、実用的な大きさの単結晶ができ
ず、透光性セラミックを作るのがやっとである。光の透
過率は約６０％／ｍｍであり、シンチレーター内で発し
た蛍光がホトダイオードまで全量届かないために、感度
が低くなってしまう。By the way, the NaI: Tl single crystal is an X-ray C
Although it was used as a scintillator for detectors of T and positron CT, it has afterglow and adversely affects the image, and also has hygroscopicity, so it is necessary to seal it and it is difficult to miniaturize the detector. There is. BGO (B
The i 4 Ge 3 O 12 ) single crystal has been used as a detector for X-ray CT, but recently, it has been used as a detector for medical devices (eg, positron CT) to which γ-rays are applied, devices for defect inspection, and atomic nucleus. It is used for experiments and high-energy elementary particle experiments, but since the fluorescence output is small, it is necessary to obtain a sufficient electrical output when used for positron CT, so it is necessary to obtain a photomultiplier tube (PMT) for fluorescence detection. ) Is required, and a small detector combined with a Si photodiode (SPD) cannot be used. BGO has a melting point of 1044 ° C, the viscosity of the melt is very high, supercooling easily occurs, and at a normal cooling rate, it does not solidify even at a melting point of 300 ° C or less,
Holds as melt. Therefore, the crystal growth rate cannot be increased, and pipe-shaped bubbles are likely to be generated along with the growth of cells, which is a problem in processing. CWO
The (CdWO 4 ) single crystal is used for a detector of X-ray CT, but its light emission efficiency is low and it is difficult to miniaturize it. In order to increase the luminous efficiency, it is necessary to slow down the growth rate of crystals and use raw materials of high purity, which causes a new problem of high manufacturing cost. Gd 2 O 2 S: Pr
Has high luminous efficiency, but a single crystal of practical size cannot be formed, and it is only possible to make a translucent ceramic. The light transmittance is about 60% / mm, and the fluorescence emitted from the scintillator does not reach the photodiode in its entirety, resulting in low sensitivity.
【０００６】この発明の目的は、発光効率の高い例えば
Ｇｄ2 Ｏ2 Ｓ：Ｐｒとほぼ同程度であって、しかも安価
で製造がしやすいシンチレーター用単結晶を提供するこ
とにある。An object of the present invention is to provide a single crystal for a scintillator which has a high luminous efficiency, for example, about the same level as Gd 2 O 2 S: Pr, and is inexpensive and easy to manufacture.
【０００７】[0007]
【課題を解決するための手段】課題解決のために、ま
ず、Ｘ線等を受けて発光する材料として希土類酸化物単
結晶に着目した。この希土類酸化物単結晶は、その融点
が２３００°Ｃ以上（例えばＧｄ2 Ｏ3 の融点は約２３
３０°Ｃ）と高いために、結晶が作りにくい。また融点
と室温との間に何回も相転移があるために結晶にクラッ
クが入りやすく、このために大型良質結晶が作りにく
い。そこで、この発明においては、アルミン酸ガドリニ
ウムを基礎にして、これに添加剤を金属として約０．１
〜５ｍｏｌ％の範囲で添加して構成したものである。上
記添加剤は、下記の（１），（２），（３）うちから少
なくとも１つの元素を選択するものである。 （１）希土類元素（ただし、Ｃｅ及びＧｄの各元素を除
く。） （２）Ｃｄ （３）Ｍｎ 添加剤の添加量の範囲に関して、約０．１ｍｏｌ％より
小さいと、有効な蛍光出力を得ることができないという
問題が生じ、また約５ｍｏｌ％を越えると、単結晶を製
造することができないという問題が生じる。したがって
上記の範囲は約０．１〜５ｍｏｌ％が望ましい。[Means for Solving the Problems] In order to solve the problems, first, attention was paid to a rare earth oxide single crystal as a material which emits light upon receiving an X-ray or the like. This rare earth oxide single crystal has a melting point of 2300 ° C. or higher (for example, the melting point of Gd 2 O 3 is about 23).
Since it is as high as 30 ° C, it is difficult to form crystals. In addition, since there are many phase transitions between the melting point and room temperature, the crystal is likely to be cracked, which makes it difficult to form a large-sized good quality crystal. Therefore, in the present invention, gadolinium aluminate is used as a base, and an additive is added to this as a metal of about 0.1
It is constituted by adding in the range of up to 5 mol%. The above-mentioned additive selects at least one element from the following (1), (2), and (3). (1) Rare earth elements (excluding each element of Ce and Gd) (2) Cd (3) When the addition amount range of Mn additive is less than about 0.1 mol%, an effective fluorescence output is obtained. However, if it exceeds about 5 mol%, a single crystal cannot be produced. Therefore, the above range is preferably about 0.1 to 5 mol%.
【０００８】[0008]
【実施例】Ａｌ2 Ｏ3 ，Ｇｄ2 Ｏ3 ，Ｅｕ2 Ｏ3 を所定
の組成比に混合焼成し、原料粉末を調整した。ベルヌー
イ法を用い，Ｈ2 ２５ ｌ／ｍｉｎ、Ｏ2 １０ ｌ／ｍ
ｉｎ，速度１０ ｍｍ／ｈｒで約１５φ×３５ｍｍの結
晶を育成した。この時のメルトの温度は２０６０℃であ
った。この結晶は、内部に双晶があったが、クラックは
なかった。この結晶から所定の寸法に加工し、Ｇｄ2 Ｏ
3 結晶と比較評価した。ＧｄＡｌＯ3 及びＧｄ2 Ｏ3 の
それぞれにＸ線や紫外線を照射したところ、これらが発
する蛍光出力は肉眼で観察する限りにおいて、殆んど同
じであった。Ｇｄ2 Ｏ3 とＣＷＯとの螢光出力を肉眼で
比較したが、Ｇｄ2 Ｏ3 の方が大きかった。EXAMPLE Al 2 O 3 , Gd 2 O 3 and Eu 2 O 3 were mixed and fired at a predetermined composition ratio to prepare a raw material powder. Using Bernoulli method, H 2 25 l / min, O 2 10 l / m
A crystal of about 15φ × 35 mm was grown at a speed of 10 mm / hr. At this time, the melt temperature was 2060 ° C. This crystal had twins inside but no cracks. This crystal is processed into a predetermined size, and Gd 2 O
Comparative evaluation was performed with 3 crystals. When each of GdAlO 3 and Gd 2 O 3 was irradiated with X-rays or ultraviolet rays, the fluorescence output emitted from them was almost the same as observed with the naked eye. The fluorescence outputs of Gd 2 O 3 and CWO were compared with the naked eye, but Gd 2 O 3 was larger.
【０００９】[0009]
【発明の効果】この発明は、発光効率を従来の例えばＧ
ｄ2 Ｏ2 Ｓ：Ｐｒとほぼ同程度であって、しかも加工も
しやすいシンチレーター単結晶を提供でき、そしてアル
ミン酸ガドリニウムは希土類酸化物より低融点で単結晶
を製造できるので、低コストで例えばＧｄ2 Ｏ2 Ｓ：Ｐ
ｒより高感度のシンチレーターを容易に製造加工でき
る。According to the present invention, the luminous efficiency can be reduced to that of the conventional G
Since it is possible to provide a scintillator single crystal which has almost the same degree as d 2 O 2 S: Pr and is easy to process, and gadolinium aluminate can produce a single crystal with a melting point lower than that of a rare earth oxide, it can be produced at low cost, for example, with 2 O 2 S: P
A scintillator with higher sensitivity than r can be easily manufactured and processed.
Claims (2)
として約０．１〜５ｍｏｌ％の範囲で添加して構成した
ものであって、 上記添加剤は、希土類元素（ただし、Ｃｅ及びＧｄの各
元素を除く。）、Ｃｄ及びＭｎのうちから少なくとも１
つの元素を選択することを特徴とするシンチレーター用
単結晶。1. A gadolinium aluminate containing an additive as a metal in a range of about 0.1 to 5 mol%, wherein the additive is a rare earth element (provided that each element of Ce and Gd is contained. At least 1 out of Cd and Mn.
A single crystal for a scintillator, which is characterized by selecting two elements.
レーターに用いることを特徴とするシンチレーター用単
結晶。2. The single crystal for a scintillator according to claim 1, which is used as a scintillator for an X-ray detector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5123058A JPH06316494A (en) | 1993-04-28 | 1993-04-28 | Single crystal for scintillator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5123058A JPH06316494A (en) | 1993-04-28 | 1993-04-28 | Single crystal for scintillator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06316494A true JPH06316494A (en) | 1994-11-15 |
Family
ID=14851162
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5123058A Pending JPH06316494A (en) | 1993-04-28 | 1993-04-28 | Single crystal for scintillator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06316494A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012149223A (en) * | 2010-12-27 | 2012-08-09 | Tohoku Univ | Material for x-ray scintillator |
| CN106835280A (en) * | 2017-01-17 | 2017-06-13 | 中国科学院福建物质结构研究所 | A kind of rare earth ion Ln3+ doping gadolinium aluminates strontium laser crystal |
-
1993
- 1993-04-28 JP JP5123058A patent/JPH06316494A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012149223A (en) * | 2010-12-27 | 2012-08-09 | Tohoku Univ | Material for x-ray scintillator |
| CN106835280A (en) * | 2017-01-17 | 2017-06-13 | 中国科学院福建物质结构研究所 | A kind of rare earth ion Ln3+ doping gadolinium aluminates strontium laser crystal |
| CN106835280B (en) * | 2017-01-17 | 2019-04-16 | 中国科学院福建物质结构研究所 | A kind of rare earth ion Ln3+Doping gadolinium aluminate strontium laser crystal |
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| Date | Code | Title | Description |
|---|---|---|---|
| A02 | Decision of refusal |
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