JPH0875860A - Ionization chamber type x-ray detector - Google Patents
Ionization chamber type x-ray detectorInfo
- Publication number
- JPH0875860A JPH0875860A JP6239650A JP23965094A JPH0875860A JP H0875860 A JPH0875860 A JP H0875860A JP 6239650 A JP6239650 A JP 6239650A JP 23965094 A JP23965094 A JP 23965094A JP H0875860 A JPH0875860 A JP H0875860A
- Authority
- JP
- Japan
- Prior art keywords
- plate
- electrode plate
- electrode
- double
- thickness
- 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
- 229910052751 metal Inorganic materials 0.000 claims abstract description 37
- 239000002184 metal Substances 0.000 claims abstract description 37
- 239000011810 insulating material Substances 0.000 claims abstract description 4
- 239000000853 adhesive Substances 0.000 abstract description 8
- 230000001070 adhesive effect Effects 0.000 abstract description 8
- 229910052724 xenon Inorganic materials 0.000 abstract description 5
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 abstract description 5
- 239000010410 layer Substances 0.000 description 25
- 239000011295 pitch Substances 0.000 description 15
- 238000001514 detection method Methods 0.000 description 6
- 239000012212 insulator Substances 0.000 description 6
- 238000003754 machining Methods 0.000 description 5
- 239000000919 ceramic Substances 0.000 description 3
- 230000001186 cumulative effect Effects 0.000 description 3
- 230000002542 deteriorative effect Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229920006332 epoxy adhesive Polymers 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000005283 ground state Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Landscapes
- Measurement Of Radiation (AREA)
- Apparatus For Radiation Diagnosis (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、Ｘ線ＣＴ装置において
使用されるＸ線を検出するための電離箱型Ｘ線検出器に
係り、特に、電極板の一部に両面信号電極板を使用した
電離箱型Ｘ線検出器に係る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ionization chamber type X-ray detector for detecting X-rays used in an X-ray CT apparatus, and more particularly to using a double-sided signal electrode plate as a part of the electrode plate. The present invention relates to an ionization chamber type X-ray detector.
【０００２】[0002]
【従来の技術】一般的に、Ｘ線ＣＴ装置においては、装
置で使用されるＸ線を検出するための検出器として、い
わゆる電離箱型Ｘ線検出器が利用されている。かかる従
来技術のＸ線ＣＴ用電離箱型Ｘ線検出器の、特に、その
基本的な電極ブロックの構造を添付の図４により示す
と、セラミックなどの絶縁物からなる２枚の扇形の電極
保持板１の間に、信号電極板２’と高圧電極板３が交互
に配置されている。すなわち、上記の電極保持板１の表
面には複数の等間隔に刻まれた溝４が設けられており、
各電極版はこれらの溝４に挿入され、接着剤などで固定
されている。そして、かかる従来の電離箱型Ｘ線検出器
で使用されていた信号電極板２’は、一般に、単体の金
属板であり、高圧電極板３もこれと全く同一のものが使
用されており、これら板厚の等しい信号電極板２’と高
圧電極板３とは、等間隔に設けた複数の溝４内に交互に
挿入され、溝４の側壁に接着剤５により固定する構造で
あった。2. Description of the Related Art Generally, in an X-ray CT apparatus, a so-called ionization chamber type X-ray detector is used as a detector for detecting X-rays used in the apparatus. Such a conventional ionization chamber type X-ray detector for X-ray CT, in particular, a basic electrode block structure thereof is shown in FIG. 4 attached herewith. Two fan-shaped electrode holdings made of an insulator such as ceramic are shown. The signal electrode plates 2 ′ and the high voltage electrode plates 3 are alternately arranged between the plates 1. That is, the surface of the electrode holding plate 1 is provided with a plurality of grooves 4 that are carved at equal intervals.
Each electrode plate is inserted into these grooves 4 and fixed with an adhesive or the like. The signal electrode plate 2'used in such a conventional ionization chamber type X-ray detector is generally a single metal plate, and the high voltage electrode plate 3 is also the same as the above. The signal electrode plate 2 ′ and the high voltage electrode plate 3 having the same plate thickness are alternately inserted into the plurality of grooves 4 provided at equal intervals, and fixed to the side wall of the groove 4 with the adhesive 5.
【０００３】このような構造では、しかしながら、１つ
のチャンネル幅ｐ（図中、「１ｃｈ幅」で示す）の中に
は電極板が２枚入っていることになる。ところで、電離
箱型のＸ線検出器では、入射してきたＸ線が電極板間の
ギャップの部分の空間（すなわち、信号電極板２’の表
面と高圧電極板３の表面とで囲まれて形成される空間）
にある気体を電離し、それによって生じた電子イオン対
がギャップの間をドリフトし、信号電極２’に達した電
子による電流を取り出すことにより検出信号を得てい
る。このため、入射してきたＸ線のうち、信号に寄与す
るのは電極間のギャップに入射したものだけであり、電
極板に入射したものは全く信号には寄与しない。そのた
め、かかる構造のＸ線検出器におけるＸ線の利用効率
は、電極間のギャップ幅を１チャンネルの幅で割ったも
のであり、電極板の厚さが薄い程Ｘ線利用効率が高くな
る。反面、この電極板の板厚を薄くすると、機械的な振
動が伝わったときに電極板自体が揺れてしまい、電気的
なノイズ電流を発生する。そこで、電極板はこのような
ノイズを発生しないようにある程度の剛性を持たせてお
かねばならず、むやみにその板厚を薄くすることは出来
ない。In such a structure, however, one channel width p (indicated by "1ch width" in the figure) includes two electrode plates. By the way, in the ionization chamber type X-ray detector, the incident X-rays are formed by being surrounded by the space of the gap between the electrode plates (that is, surrounded by the surface of the signal electrode plate 2 ′ and the surface of the high voltage electrode plate 3). Space
The gas in the ion is ionized, the electron ion pair generated thereby drifts between the gaps, and the detection signal is obtained by extracting the current due to the electrons reaching the signal electrode 2 ′. Therefore, of the incident X-rays, only those that enter the gap between the electrodes contribute to the signal, and those that enter the electrode plate do not contribute to the signal at all. Therefore, the X-ray utilization efficiency of the X-ray detector having such a structure is obtained by dividing the gap width between the electrodes by the width of one channel, and the thinner the electrode plate, the higher the X-ray utilization efficiency. On the other hand, if the electrode plate is made thin, the electrode plate itself shakes when mechanical vibration is transmitted, and an electrical noise current is generated. Therefore, the electrode plate must have a certain degree of rigidity so as not to generate such noise, and the plate thickness cannot be reduced unnecessarily.
【０００４】上述の従来の単体電極構造に対し、信号電
極板の表・裏を電気的に絶縁させ、それぞれ別のチャン
ネルに割り当てる両面電極板を採用した構造の電離箱型
Ｘ線検出器が既に提案されている。このような両面電極
板２を利用した構造では、図５及び図６に示すように、
１つのチャンネル幅ｐ（図中、「１ｃｈ幅」で示す）の
中に電極板が約１枚分だけが入っていることになり、そ
のため、従来の全体が金属板の信号電極板の従来構造の
検出器に比較して、その空間利用効率を向上することが
出来るという利点がある。In contrast to the conventional single electrode structure described above, there is already an ionization box type X-ray detector having a structure in which the front and back sides of the signal electrode plate are electrically insulated and a double-sided electrode plate assigned to each channel is adopted. Proposed. In the structure using the double-sided electrode plate 2 as described above, as shown in FIGS.
Only one electrode plate is contained in one channel width p (indicated by "1ch width" in the figure), so that the conventional structure of the signal electrode plate is entirely metal plate. There is an advantage that the space utilization efficiency can be improved as compared with the above detector.
【０００５】また、電離箱型Ｘ線検出器において、その
電極板には、高電圧のバイアスを印加する（高圧電極板
３）、あるいは、Ｘ線によって電離された電子を集める
（信号電極板２）といった電気的な役割だけではなく、
さらに、Ｘ線によるクロストークを防止する役割もあ
る。すなわち、電極間ギャップに入射したＸ線はキセノ
ンガスを電離し、それにより生じた電子が信号電極に集
められることにより信号電流として取り出されている
が、しかし、入射したＸ線のエネルギーの一部はキセノ
ンのＫ殻電子を励起し、この励起電子が基底状態に戻る
ときに蛍光Ｘ線を放出する。この蛍光Ｘ線はエネルギー
の関係からキセノンガス中では吸収され難く、隣のチャ
ンネルへのクロストークとなり、検出器の空間分解能の
低下を招いてしまう。そのため、電極板によってこの蛍
光Ｘ線を吸収させて隣接チャンネルへのＸ線の漏れ込み
を少なくしてやる必要がある。In the ionization chamber type X-ray detector, a high voltage bias is applied to the electrode plate (high-voltage electrode plate 3) or electrons ionized by X-rays are collected (signal electrode plate 2). ) Not only electrical role,
Further, it also has a role of preventing crosstalk due to X-rays. That is, the X-rays incident on the inter-electrode gap ionize the xenon gas, and the electrons generated thereby are collected as signal currents by being collected at the signal electrodes. However, some of the energy of the incident X-rays is extracted. Excites K-shell electrons of xenon, and emits fluorescent X-rays when the excited electrons return to the ground state. This fluorescent X-ray is difficult to be absorbed in the xenon gas due to the relation of energy and causes crosstalk to the adjacent channel, resulting in a decrease in the spatial resolution of the detector. Therefore, it is necessary to absorb the fluorescent X-rays by the electrode plate and reduce the leakage of the X-rays into the adjacent channel.
【０００６】そこで、通常、これら電極板の材質とし
て、Ｘ線吸収係数の高い金属（例えば、タングステン、
モリブデンなど）を、このＸ線によるクロストークが十
分小さくなるような板厚にして使用することが行われて
いる。このことは、上記の両面電極板２でも同様であ
り、やはりチャンネル間のＸ線のクロストークを考慮す
ると、その中心金属板は高圧電極板と同じ材質、同じ板
厚であることが好ましい。そのため、従来の両面信号板
を使用した電離箱検出器では、両面信号電極板は高圧電
極板と同じ板厚の中心金属板の両面に絶縁層を設け、さ
らに、その両面に金属電極層を積層し、いわゆる５層構
造となっており、この両面信号電極板は、一枚の金属板
から成る高圧電極板３に比較するとその絶縁層と表面金
属層の分だけ板厚が厚くなっている。Therefore, as a material for these electrode plates, a metal having a high X-ray absorption coefficient (for example, tungsten, or the like) is usually used.
Molybdenum or the like) is used with a plate thickness such that crosstalk due to this X-ray is sufficiently small. The same applies to the double-sided electrode plate 2 described above, and in consideration of X-ray crosstalk between channels, the central metal plate is preferably made of the same material and has the same plate thickness as the high voltage electrode plate. Therefore, in the conventional ionization chamber detector that uses a double-sided signal plate, the double-sided signal electrode plate is provided with an insulating layer on both sides of a central metal plate having the same plate thickness as the high-voltage electrode plate, and further a metal electrode layer is laminated on both sides. However, it has a so-called five-layer structure, and this double-sided signal electrode plate is thicker by the insulating layer and the surface metal layer than the high-voltage electrode plate 3 made of one metal plate.
【０００７】[0007]
【発明が解決しようとする課題】ところで、上述の従来
技術になる検出器では、高圧電極板と信号電極板とを交
互に配置する場合、各チャンネルの特性を揃えるために
はこれら電極板間のギャップが等しくなるように配置す
る必要がある。しかしながら、信号電極板として、特
に、上記従来の両面電極板２を使用する場合において、
高圧電極板３と板厚の異なる両面信号電極板２との間の
ギャップを等しくするためには、厚さの異なる２種類の
電極板の中心位置がそれぞれ等間隔になるように配置す
る必要がある。By the way, in the above-mentioned conventional detector, when the high-voltage electrode plates and the signal electrode plates are alternately arranged, in order to make the characteristics of each channel uniform, a gap between these electrode plates is required. The gaps should be arranged so that they are equal. However, when the above-mentioned conventional double-sided electrode plate 2 is used as the signal electrode plate,
In order to equalize the gap between the high-voltage electrode plate 3 and the double-sided signal electrode plate 2 having a different plate thickness, it is necessary to dispose the center positions of the two types of electrode plates having different thicknesses at equal intervals. is there.
【０００８】しかし、実際に組立を行う場合には、これ
ら電極板の中心位置を直接知ることは出来ず、実際上
は、電極板を配置する作業上の基準は電極板の表面の位
置となる。このため、厚さの異なる高圧電極板３と両面
信号電極板２とでは電極板を配置する位置（電極板表面
の位置）は等間隔にはならず、その板厚に応じて不等間
隔となってしまう。However, when actually assembling, it is not possible to directly know the center positions of these electrode plates, and in practice, the work standard for arranging the electrode plates is the position of the surface of the electrode plates. . Therefore, the high-voltage electrode plate 3 and the double-sided signal electrode plate 2 having different thicknesses do not have the same positions (positions on the surface of the electrode plate) where the electrode plates are arranged, but have unequal intervals according to the plate thicknesses. turn into.
【０００９】これを避けるためには、上記の図６に示す
ように、電極板を上下両側から保持している絶縁物サポ
ートである電極保持板１に形成されている溝４の位置
を、電極板の板厚の差を考慮に入れて設定することが考
えられる。すなわち、上述の電極保持板１の対向表面上
に形成された溝４内に電極板の端を挿入接着する方法で
は、上記溝４の側壁と電極板の端部を接着剤で固定する
ため、厚さの異なる高圧電極板３と両面信号電極板２と
を交互に並べた時、その電極間のギャップを均一に揃え
るため、形成する溝４のピッチを電極板の板厚差に応じ
て不等間隔（ｐa、ｐb：但し、ｐa−ｐb＝ｄS−ｄH）に
すればよい。In order to avoid this, as shown in FIG. 6 described above, the position of the groove 4 formed in the electrode holding plate 1 which is an insulator support holding the electrode plate from the upper and lower sides is set to the electrode position. It is conceivable to set it in consideration of the difference in plate thickness. That is, in the method of inserting and adhering the end of the electrode plate into the groove 4 formed on the facing surface of the electrode holding plate 1 described above, since the side wall of the groove 4 and the end of the electrode plate are fixed with an adhesive, When the high-voltage electrode plates 3 and the double-sided signal electrode plates 2 having different thicknesses are alternately arranged, the pitch of the grooves 4 to be formed is not uniform according to the plate thickness difference of the electrode plates in order to make the gaps between the electrodes uniform. equidistant (p a, p b: However, p a -p b = d S -d H) may be set to.
【００１０】ところで、現在使用しているような絶縁物
電極保持板１の加工方法では、加工機に寸法の基準とな
る溝ピッチ寸法をセットし、所定の回数だけ溝加工とワ
ークの送りを繰り返すことによって上記溝４の加工が行
われている。そのため、所定の溝ピッチを設定しても１
００本以上の溝４を加工するときには、加工機特有の僅
かな誤差などによって、累積誤差を生じてしまう。この
ため、形成する全部の溝４を所定の位置に収めるために
は、最初に設定した溝ピッチで全溝の加工を行い、その
ときの累積誤差を測定し、その累積誤差が設定値内に収
まるように設定する溝ピッチの値を補正するという調整
作業を行わねばならない。これに対して、不等間隔ピッ
チの溝加工は、上記の等間隔ピッチの溝加工に比較する
と、加工時のワークの送り量を少なくとも２種類持たね
ばならず、出来上がりの寸法精度を確保するためには、
さらに、必要な調整作業が複雑になるという問題点があ
る。By the way, in the processing method of the insulator electrode holding plate 1 which is currently used, the groove pitch dimension which is the standard of the dimension is set in the processing machine, and the groove processing and the work feeding are repeated a predetermined number of times. Thus, the groove 4 is processed. Therefore, even if a predetermined groove pitch is set, 1
When processing the grooves 4 of 00 or more, a cumulative error occurs due to a slight error peculiar to the processing machine. Therefore, in order to fit all the formed grooves 4 in a predetermined position, all the grooves are machined at the groove pitch initially set, the cumulative error at that time is measured, and the cumulative error is within the set value. Adjustment work must be performed to correct the groove pitch value that is set to fit. On the other hand, grooving with unequal pitches must have at least two types of feed amount of the work during machining, in order to secure finished dimensional accuracy, as compared with grooving with equidistant pitches described above. Has
Further, there is a problem that necessary adjustment work becomes complicated.
【００１１】そこで、本発明の目的は、上記の従来技術
における問題点に鑑み、両面信号電極板を使用したＸ線
ＣＴ装置用電離箱検出器において、組立加工が容易で、
かつ、実用的な性能を低下させることなく、診断能の高
い良好なＣＴ画像を堤供することの可能な電離箱型Ｘ線
検出器を提供することにある。Therefore, in view of the above problems in the prior art, an object of the present invention is to easily assemble an ionization chamber detector for an X-ray CT apparatus using a double-sided signal electrode plate,
Another object of the present invention is to provide an ionization chamber type X-ray detector capable of providing a good CT image having a high diagnostic ability without deteriorating practical performance.
【００１２】[0012]
【課題を解決するための手段】上記目的を達成するため
に、本発明によれば、高圧の電離気体が内部に封入され
たケースと、このケース内に並行に配置され、その対向
表面に複数の同一ピッチの溝を放射状に形成した絶縁材
からなる電極保持板と、前記対向する絶縁電極保持板の
同一ピッチ溝内に交互に配列して一方の側壁に接着固定
される、少なくとも、一枚の金属板からなる高圧電極板
と、中心金属板の両面に絶縁層と金属電極層を積層した
多層構造の両面電極板とを含んだ電極板とからなり、前
記電極板からの電気信号を前記ケースを貫通して取り出
す構造の電離箱型Ｘ線検出器において、前記電極板のう
ちの多層構造の前記両面電極板の中心金属板の板厚は、
Ｘ線による隣接チャンネルへのクロストークの影響を防
止するのに必要な厚さの板厚であると同時に、前記一枚
の金属板からなる高圧電極板の板厚を、前記両面電極板
の全体の板厚と同じ厚さにしたことを特徴とする電離箱
型Ｘ線検出器が提案されている。In order to achieve the above object, according to the present invention, a case in which a high-pressure ionized gas is enclosed, and a plurality of cases are arranged in parallel in the case and are arranged on opposite surfaces thereof. Electrode holding plates made of an insulating material in which grooves of the same pitch are formed radially, and alternately arranged in the same pitch grooves of the opposed insulating electrode holding plates and fixedly adhered to one side wall, at least one sheet A high-voltage electrode plate made of a metal plate, and an electrode plate including a double-sided electrode plate having a multilayer structure in which an insulating layer and a metal electrode layer are laminated on both sides of a central metal plate, and an electric signal from the electrode plate is In an ionization box type X-ray detector having a structure of penetrating through a case, a plate thickness of a central metal plate of the double-sided electrode plate having a multilayer structure among the electrode plates is
The thickness of the high-voltage electrode plate made of the one metal plate is the same as the thickness of the double-sided electrode plate at the same time as the plate thickness required to prevent the influence of X-rays on crosstalk to adjacent channels. There is proposed an ionization chamber type X-ray detector characterized in that it has the same thickness as the plate thickness.
【００１３】[0013]
【作用】上記の本発明によれば、まず、検出器の空間分
解能の低下を防止するため、少なくとも、前記電極板の
うちの多層構造の前記両面電極板の中心金属板の板厚を
Ｘ線による隣接チャンネルへのクロストークの影響を防
止するのに必要な厚さの板厚にすると共に、前記高圧電
極板と多層構造の両面信号電極板との板厚が異なること
から生じる不都合を回避するため、単体の金属板である
前記高圧電極板の板厚を、前記中心金属板の両面に絶縁
層及び金属電極層を積層してなる多層構造の両面電極板
の全体の板厚と同じ厚さにした。このことにより、絶縁
電極保持板の対向面に同一ピッチで形成した溝内に前記
高圧電極板と前記両面信号電極板とを交互に挿入し、一
方の側壁に接着固定しながら配列することによって、容
易に電極板間のギャップを均一にすることが出来、チャ
ンネル間の特性ばらつきが少なく、Ｘ線ＣＴ装置で利用
した場合にも画像ノイズが少なく診断能の高いＣＴ画像
が得られる電離箱型Ｘ線検出器を得ることが可能にな
る。また、その組立てに際しても、絶縁物の前記電極保
持板の溝加工は、単純な均一ピッチの繰り返しだけで可
能となるため、溝の加工及び加工後の溝ピッチの測定・
精度管理などの作業を単純化することが出来、加工組立
の面からも大変に有利となる。また、前記高圧電極板の
板厚を前記両面電極板の全体の板厚と同じ厚さにしたこ
とによる空間利用率の低下量は実用上問題を生じること
はない。According to the present invention described above, first, in order to prevent the spatial resolution of the detector from deteriorating, at least the thickness of the central metal plate of the double-sided electrode plate having the multi-layer structure among the electrode plates is determined by X-ray. The plate thickness is set to a thickness necessary to prevent the influence of crosstalk on adjacent channels due to the above, and avoids the disadvantage caused by the difference in plate thickness between the high-voltage electrode plate and the double-sided signal electrode plate having a multilayer structure. Therefore, the thickness of the high-voltage electrode plate, which is a single metal plate, is the same as the total thickness of the double-sided electrode plate having a multilayer structure in which an insulating layer and a metal electrode layer are laminated on both surfaces of the central metal plate. I chose Thereby, by alternately inserting the high-voltage electrode plate and the double-sided signal electrode plate in the groove formed at the same pitch on the opposing surface of the insulated electrode holding plate, by arranging while adhering and fixing to one side wall, Ionization box type X that can easily make the gap between the electrode plates uniform, has less variation in characteristics between channels, and can obtain CT images with high diagnostic ability with little image noise when used in an X-ray CT system. It is possible to obtain a line detector. Further, also in the assembling, since the groove processing of the electrode holding plate of the insulator can be performed by simply repeating the uniform pitch, the groove processing and the measurement of the groove pitch after the processing can be performed.
Operations such as accuracy control can be simplified, which is extremely advantageous from the aspect of processing and assembly. In addition, the reduction amount of the space utilization factor caused by making the plate thickness of the high-voltage electrode plate the same as the total plate thickness of the double-sided electrode plate does not cause a practical problem.
【００１４】[0014]
【実施例】以下、本発明になる実施例の詳細について、
添付の図面を参照しながら説明を加える。まず、図３に
は、本発明の実施例である電離箱型Ｘ線検出器を採用し
たＸ線ＣＴ装置の全体構造が示されており、この図にお
いて、組み立てられた複数の電極ブロック１６は検出器
容器（ケース）１５の中に円弧状に配列されている。こ
の検出器容器（ケース）１５の中には、例えばキセノン
などの電離気体が高圧状態で封入されており、この検出
器容器（ケース）１５は装置の回転板１３の上に、Ｘ線
管１１と対向するように、扇状に配置され、固定されて
いる。なお、この回転板１３の中央部には被検体１２を
配置するための中心穴１４が形成されており、この回転
板１３は被検体１２を中心として回転しながら上記被検
体１２の各方向からのＸ線透過データの計測を行うこと
が出来るようになっている。The details of the embodiments of the present invention will be described below.
Description will be added with reference to the accompanying drawings. First, FIG. 3 shows the entire structure of an X-ray CT apparatus that employs an ionization chamber type X-ray detector that is an embodiment of the present invention. In this figure, the assembled electrode blocks 16 are Arranged in a circular arc shape in the detector container (case) 15. An ionized gas such as xenon is enclosed in the detector container (case) 15 in a high pressure state, and the detector container (case) 15 is placed on the rotary plate 13 of the apparatus and the X-ray tube 11 is provided. It is arranged in a fan shape and is fixed so as to face with. A central hole 14 for arranging the subject 12 is formed in the center of the rotary plate 13, and the rotary plate 13 rotates from the subject 12 as a center from the respective directions of the subject 12. The X-ray transmission data can be measured.
【００１５】図２には、上記Ｘ線ＣＴ装置においてＸ線
を検出するための電離箱型Ｘ線検出器の特徴部分である
電極ブロック１６の一つが拡大されて示されている。図
示の複数の内の一つの電極ブロック１６は、例えばセラ
ミックス等の絶縁性を持った素材で作られた扇状の２枚
の支持板１と、その間に交互に配列された電極版とから
構成されており、この図においても、やはり、符号２
は、中心の金属板の両側面に絶縁層を設け、更に、この
両側面に両面信号電極板となる金属層を積層した多層
（この実施例では５層）構造の両面信号電極板を、符号
３は単体金属板の高圧電極板を示している。そして、上
記扇状の２枚の支持板１の対向面には、これらの両面信
号電極板２と高圧電極板３とを放射線状に規則正しく配
列するため、複数の溝４が放射線状に形成されており、
これらの溝４に上記の両面信号電極板２及び高圧電極板
３の上下の端を差し込み、両側から支持板ｌで挟んで保
持し、さらに、接着剤等を用いて上記信号電極板２及び
高圧電極板３を支持板１に固定する構造となっている。FIG. 2 is an enlarged view of one of the electrode blocks 16 which is a characteristic part of the ionization chamber type X-ray detector for detecting X-rays in the X-ray CT apparatus. One of the plurality of illustrated electrode blocks 16 is composed of two fan-shaped support plates 1 made of an insulating material such as ceramics, and electrode plates arranged alternately between them. In this figure as well, reference numeral 2
Is a double-sided signal electrode plate having a multi-layer (five layers in this embodiment) structure in which insulating layers are provided on both side surfaces of a central metal plate, and metal layers to be double-sided signal electrode plates are further laminated on the both side surfaces. Reference numeral 3 indicates a high-voltage electrode plate which is a single metal plate. A plurality of grooves 4 are formed in a radial pattern on the opposing surfaces of the two fan-shaped support plates 1 in order to regularly arrange the double-sided signal electrode plates 2 and the high-voltage electrode plates 3 in a radial pattern. Cage,
The upper and lower ends of the double-sided signal electrode plate 2 and the high-voltage electrode plate 3 are inserted into these grooves 4 and sandwiched and held by support plates 1 from both sides, and further, the signal electrode plate 2 and the high-voltage plate 2 are bonded with an adhesive or the like. The structure is such that the electrode plate 3 is fixed to the support plate 1.
【００１６】かかる構成の電極ブロックにおいては、上
記の両面信号電極板２と高圧電極板３とに挟まれた空間
が１チャンネルの検出素子（１ＣＨ）となっており、Ｘ
線ＣＴ装置のＸ線源（図３のＸ線管１１）から放射され
たＸ線１０がこのチャンネル空間を通過するときに生じ
る電離を測定することによって、通過するＸ線を検出す
ることとなる。In the electrode block having such a structure, the space sandwiched between the double-sided signal electrode plate 2 and the high-voltage electrode plate 3 serves as a one-channel detection element (1CH).
The X-rays that pass are detected by measuring the ionization that occurs when the X-rays 10 emitted from the X-ray source (X-ray tube 11 in FIG. 3) of the CT apparatus pass through this channel space. .
【００１７】次に、図１には、上記電極ブロック１６に
おける電極板の保持構造の詳細が示されており、この図
において、セラミックなどの絶縁物を使用した電極保持
板１の表面には溝４が等間隔ｐで形成されている。これ
らの溝４には、上述のモリブデンやタングステンなどの
Ｘ線透過率の低い金属を使用した高圧電極板３と、中心
に同種の金属を使用しその両側の表面に絶縁層を介して
銅箔などの表面導電層を設けた５層構造の両面信号電極
板２とが、交互に配置されている。これら両面信号電極
板２の表裏の表面導電層は、それぞれ、別のチャンネル
に割り当てられている。Next, FIG. 1 shows the details of the electrode plate holding structure in the electrode block 16, and in this figure, a groove is formed on the surface of the electrode holding plate 1 using an insulator such as ceramic. 4 are formed at equal intervals p. In these grooves 4, a high voltage electrode plate 3 made of a metal having a low X-ray transmittance such as molybdenum or tungsten is used, and the same kind of metal is used at the center, and copper foil is provided on both sides of the foil with insulating layers interposed therebetween. And a double-sided signal electrode plate 2 having a five-layer structure provided with surface conductive layers such as. The front and back surface conductive layers of the double-sided signal electrode plate 2 are respectively assigned to different channels.
【００１８】ところで、本発明によれば、両面信号電極
板２の中心金属板２１は、Ｘ線による隣接チャンネルへ
のクロストークの影響を防止するのに必要な厚さにする
必要があり、具体的には、上記金属材料を使用した場合
には、０．１〜０．１５mm程度の板厚が適当である。さ
らに、その表面に絶縁層２２、表面導電層２３をそれぞ
れ設けると、全体の板の厚さは０．２〜０．２５mm程度
となる。一方、上記の単体金属板からなる高圧電極板３
の厚さは、単にＸ線による隣接チャンネルへのクロスト
ークの影響を防止するのに必要な厚さを考慮するだけで
なく、上記の両面信号電極板２の全体厚さと等しくして
あり、上述の本発明の実施例では、これらる高圧電極板
３の厚さも０．２〜０．２５mm程度としている。By the way, according to the present invention, the central metal plate 21 of the double-sided signal electrode plate 2 needs to have a thickness necessary to prevent the influence of X-rays on crosstalk to adjacent channels. Specifically, when the above metal material is used, a plate thickness of about 0.1 to 0.15 mm is suitable. Further, when the insulating layer 22 and the surface conductive layer 23 are respectively provided on the surface, the thickness of the whole plate becomes about 0.2 to 0.25 mm. On the other hand, the high-voltage electrode plate 3 made of the above single metal plate
The thickness of is not only the thickness necessary to prevent the influence of X-rays on crosstalk on adjacent channels, but is made equal to the total thickness of the double-sided signal electrode plate 2 described above. In the embodiment of the present invention, the thickness of these high voltage electrode plates 3 is also about 0.2 to 0.25 mm.
【００１９】そして、上述のような高圧電極板３及び両
面信号電極板２は、その両端部に塗布された接着剤５に
よって上記電極保持板１の溝４の側壁に接着固定されて
いる。なお、この接着剤は、例えばエポキシ系の接着剤
などをスクリーン印刷法などで塗布するとにより、その
接着層の厚さを高い精度で管理することが出来る。ま
た、上記電極保持板１の表面に等間隔（＝ｐ）に設けら
れた溝４に、板厚の等しい上記両面信号電極板２と高圧
電極板３とを交互に配列していくと、これら両面信号電
極板２と高圧電極板３との間に形成されるギャップはす
べて等しく（＝ｇ）なる。The high voltage electrode plate 3 and the double-sided signal electrode plate 2 as described above are adhered and fixed to the side walls of the groove 4 of the electrode holding plate 1 by the adhesive 5 applied to both ends thereof. This adhesive can control the thickness of the adhesive layer with high accuracy by applying, for example, an epoxy adhesive by a screen printing method or the like. Further, when the double-sided signal electrode plates 2 and the high voltage electrode plates 3 having the same plate thickness are alternately arranged in the grooves 4 provided at equal intervals (= p) on the surface of the electrode holding plate 1, these The gaps formed between the double-sided signal electrode plate 2 and the high voltage electrode plate 3 are all equal (= g).
【００２０】このように、単体の金属板である高圧電極
板３の板厚を、Ｘ線による隣接チャンネルへのクロスト
ークの影響を防止するのに必要な厚さを超えて、さら
に、両面構造の両面信号電極板２と同じ板厚にすること
により、これら電極板の板厚が異なることから生じる不
都合を回避することとなるが、このように高圧電極板３
の板厚を厚くすることは、入射Ｘ線の空間利用率という
点では不利になる。しかしながら、上述のように、この
高圧電極板３は、本来、隣接チャンネルへのクロストー
クの影響を防止するのには０．１〜０．１５mm程度の板
厚が適当であるが、これをさらに両面信号電極２の板厚
である０．２〜０．２５mm程度にしても、これら単体構
造の電極板と両面構造の電極板との板厚の差は０．１５
mmであり、例えば電極間ピッチを１mmとすれば、この入
射Ｘ線の空間利用率の低下量を具体的に求めてもその低
下量は高々５％以下であり、特に、実用上の大きな問題
を生じることはないことが分かる。As described above, the thickness of the high-voltage electrode plate 3 which is a single metal plate exceeds the thickness required to prevent the influence of X-rays on crosstalk to adjacent channels, and further, the double-sided structure is adopted. By making the plate thickness the same as that of the double-sided signal electrode plate 2, the inconvenience caused by the difference in plate thickness of these electrode plates can be avoided.
Increasing the plate thickness of is disadvantageous in terms of the space utilization rate of incident X-rays. However, as described above, this high-voltage electrode plate 3 is originally suitable to have a plate thickness of about 0.1 to 0.15 mm in order to prevent the influence of crosstalk on adjacent channels. Even if the plate thickness of the double-sided signal electrode 2 is about 0.2 to 0.25 mm, the difference in plate thickness between the single-sided electrode plate and the double-sided electrode plate is 0.15.
mm, for example, if the pitch between the electrodes is 1 mm, the amount of decrease in the space utilization factor of the incident X-rays is 5% or less at the most, even if a specific determination is made. It turns out that it does not occur.
【００２１】これに対し、単体の金属板である高圧電極
板３の板厚を両面構造の両面信号電極板２と同じ板厚に
することにより、絶縁物の保持板の溝加工は、従来の加
工技術を利用した単純な均一ピッチの繰り返しだけで可
能となることから、溝の加工及び加工後の溝ピッチの測
定・精度管理などの作業を単純化することが出来、加工
組立の面から考慮すると大変有利な物となる。かつ、電
極板間のギャップを好ましい等ギャップとすることが出
来ることから、組み立てられた装置の特性の面からも、
チャンネル間の特性ばらつきが少なく、この検出装置を
ＣＴ装置で利用した場合にも、画像ノイズの少ない診断
能の高いＣＴ画像が得られることとなる。On the other hand, by making the thickness of the high-voltage electrode plate 3 which is a single metal plate the same as that of the double-sided signal electrode plate 2 having the double-sided structure, the groove processing of the holding plate of the insulator is performed by the conventional method. Since it is possible by simply repeating the uniform pitch using machining technology, it is possible to simplify work such as machining the groove, measuring the groove pitch after machining, and controlling accuracy, and consider it from the aspect of machining and assembly. Then it becomes a very advantageous thing. Moreover, since the gap between the electrode plates can be set to a preferable equal gap, in terms of the characteristics of the assembled device,
Even if this detection device is used in a CT device, there is little variation in characteristics between channels, and a CT image with low image noise and high diagnostic ability can be obtained.
【００２２】[0022]
【発明の効果】以上の本発明の詳細な説明からも明らか
なように、本発明になる電離箱型Ｘ線検出器によれば、
特に、５層構造の両面信号電極板を使用したＸ線ＣＴ装
置用電離箱検出器において、製作・精度管理し易い等間
隔の溝を設けるだけで電極板の組立を可能とすることに
よりその組立加工が容易で、かつ、電極板によるストロ
ークの防止により検出器の空間分解能の低下を招くこと
なく、電極板間の均等ギャップにより各チャンネル間の
Ｘ線検出出力や検出特性のばらつきをなくしてチャンネ
ル間の検出特性の一様性を向上し、かつ、空間利用率の
低下量を最小限に押さえ、もって、実用的な性能を低下
させることなく、診断能の高い良好なＣＴ画像を堤供す
ることの可能な電離箱型Ｘ線検出器を提供することが可
能になるという実用的にも優れた効果を発揮する。As is clear from the above detailed description of the present invention, according to the ionization chamber type X-ray detector of the present invention,
In particular, in an ionization chamber detector for an X-ray CT device that uses a double-sided signal electrode plate with a five-layer structure, the electrode plate can be assembled by simply providing grooves at equal intervals for easy production and quality control. The channels are easy to process and prevent the stroke of the electrode plates from deteriorating the spatial resolution of the detector. The uniform gap between the electrode plates eliminates variations in X-ray detection output and detection characteristics between channels. To improve the uniformity of detection characteristics between areas, and to minimize the amount of decrease in space utilization rate, thereby providing a good CT image with high diagnostic ability without degrading practical performance. It is possible to provide an ionization chamber type X-ray detector capable of achieving a practically excellent effect.
【図１】本発明の実施例である電離箱型Ｘ線検出器の特
徴部分である電極板の固定構造を示す一部拡大断面図で
ある。FIG. 1 is a partially enlarged sectional view showing a fixing structure of an electrode plate which is a characteristic part of an ionization chamber type X-ray detector according to an embodiment of the present invention.
【図２】本発明の実施例である電離箱型Ｘ線検出器の一
つの電極ブロックの全体詳細構造を示すための一部展開
斜視図である。FIG. 2 is a partially exploded perspective view showing the entire detailed structure of one electrode block of the ionization chamber type X-ray detector according to the embodiment of the present invention.
【図３】本発明の実施例である電離箱型Ｘ線検出器を採
用したＣＴ装置全体の断面構造を示す断面図である。FIG. 3 is a cross-sectional view showing the cross-sectional structure of the entire CT apparatus which employs the ionization chamber type X-ray detector according to the embodiment of the present invention.
【図４】従来技術になる単一の金属板を信号電極板とし
て使用している検出器の電極取付け構造を示した断面図
である。FIG. 4 is a cross-sectional view showing an electrode mounting structure of a detector using a single metal plate as a signal electrode plate according to the related art.
【図５】やはり、従来技術になる、中心金属板の上に絶
縁層を介して表面導体層を形成した両面信号電極板を使
用した検出器の電極取付け構造を示した断面図である。FIG. 5 is a sectional view showing an electrode mounting structure of a detector using a double-sided signal electrode plate in which a surface conductor layer is formed on a central metal plate via an insulating layer, which is also a conventional technique.
【図６】上記図５と同様に、厚さの異なる両面構造の信
号電極板と高圧電極板を、電極間ギャップが等しくなる
ように配置する従来の電極取付け構造の一例を示した断
面図である。FIG. 6 is a cross-sectional view showing an example of a conventional electrode mounting structure in which a signal electrode plate and a high voltage electrode plate having a double-sided structure with different thicknesses are arranged so that the inter-electrode gaps are the same as in FIG. is there.
１ 電極保持板 ２ 多層構造の両面信号電極板 ２’ 単板構造の信号電極板 ３ 高圧電極板 ４ 溝 ５ 接着剤 １１ Ｘ線管 １２ 被検体 １３ 回転板 １４ 穴 １５ 検出器容器（ケース） １６ 電極ブロック ２１ 中心金属板 ２２ 絶縁層 ２３ 表面導電層 DESCRIPTION OF REFERENCE NUMERALS 1 electrode holding plate 2 double-sided signal electrode plate 2'single plate signal electrode plate 3 high-voltage electrode plate 4 groove 5 adhesive 11 X-ray tube 12 subject 13 rotating plate 14 hole 15 detector container (case) 16 Electrode block 21 Central metal plate 22 Insulating layer 23 Surface conductive layer
Claims (1)
と、このケース内に並行に配置され、その対向表面に複
数の同一ピッチの溝を放射状に形成した絶縁材からなる
電極保持板と、前記対向する絶縁電極保持板の同一ピッ
チ溝内に交互に配列して一方の側壁に接着固定される、
少なくとも、一枚の金属板からなる高圧電極板と、中心
金属板の両面に絶縁層と金属電極層を積層した多層構造
の両面電極板とを含んだ電極板とからなり、前記電極板
からの電気信号を前記ケースを貫通して取り出す構造の
電離箱型Ｘ線検出器において、前記電極板のうちの多層
構造の前記両面電極板の中心金属板の板厚は、Ｘ線によ
る隣接チャンネルへのクロストークの影響を防止するの
に必要な厚さの板厚であると同時に、前記一枚の金属板
からなる高圧電極板の板厚を、前記両面電極板の全体の
板厚と同じ厚さにしたことを特徴とする電離箱型Ｘ線検
出器。1. A case in which a high-pressure ionized gas is sealed inside, and an electrode holding plate made of an insulating material which is arranged in parallel in the case and has a plurality of grooves of the same pitch radially formed on its opposing surfaces. , Arranged alternately in the same pitch groove of the opposed insulating electrode holding plates and fixed to one side wall by adhesion.
At least a high-voltage electrode plate consisting of a single metal plate, and an electrode plate including a double-sided electrode plate having a multilayer structure in which an insulating layer and a metal electrode layer are laminated on both sides of a central metal plate, In an ionization box type X-ray detector having a structure for extracting an electric signal through the case, the thickness of the central metal plate of the double-sided electrode plate having a multi-layered structure among the electrode plates is equal to that of an adjacent channel by X-rays. The thickness of the high-voltage electrode plate made of the one metal plate is the same as the total thickness of the double-sided electrode plate at the same time as the plate thickness of the thickness required to prevent the influence of crosstalk. An ionization chamber type X-ray detector characterized in that
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6239650A JPH0875860A (en) | 1994-09-08 | 1994-09-08 | Ionization chamber type x-ray detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6239650A JPH0875860A (en) | 1994-09-08 | 1994-09-08 | Ionization chamber type x-ray detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0875860A true JPH0875860A (en) | 1996-03-22 |
Family
ID=17047864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6239650A Pending JPH0875860A (en) | 1994-09-08 | 1994-09-08 | Ionization chamber type x-ray detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0875860A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010185754A (en) * | 2009-02-12 | 2010-08-26 | Hitachi Cable Ltd | Radiation detector stand |
| CN110764129A (en) * | 2019-11-15 | 2020-02-07 | 中国科学院合肥物质科学研究院 | Multi-channel low-pressure ionization chamber gas detector |
| CN111157562A (en) * | 2020-01-17 | 2020-05-15 | 胜科纳米（苏州）有限公司 | Method for eliminating interference signal in narrow-side-wall sample photoelectron spectroscopy test and sample clamp |
-
1994
- 1994-09-08 JP JP6239650A patent/JPH0875860A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010185754A (en) * | 2009-02-12 | 2010-08-26 | Hitachi Cable Ltd | Radiation detector stand |
| CN110764129A (en) * | 2019-11-15 | 2020-02-07 | 中国科学院合肥物质科学研究院 | Multi-channel low-pressure ionization chamber gas detector |
| CN111157562A (en) * | 2020-01-17 | 2020-05-15 | 胜科纳米（苏州）有限公司 | Method for eliminating interference signal in narrow-side-wall sample photoelectron spectroscopy test and sample clamp |
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