EP0063082B1 - Röntgenstrahlungsdetektor - Google Patents

Röntgenstrahlungsdetektor Download PDF

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Publication number
EP0063082B1
EP0063082B1 EP82400628A EP82400628A EP0063082B1 EP 0063082 B1 EP0063082 B1 EP 0063082B1 EP 82400628 A EP82400628 A EP 82400628A EP 82400628 A EP82400628 A EP 82400628A EP 0063082 B1 EP0063082 B1 EP 0063082B1
Authority
EP
European Patent Office
Prior art keywords
gas
detector
rays
ionisation
plate
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
Application number
EP82400628A
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English (en)
French (fr)
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EP0063082A1 (de
Inventor
Robert Allemand
Jean-Jacques Gagelin
Edmond Tournier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
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Publication of EP0063082A1 publication Critical patent/EP0063082A1/de
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Publication of EP0063082B1 publication Critical patent/EP0063082B1/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
    • H01J47/02—Ionisation chambers

Definitions

  • the present invention relates to an X-ray detector, in particular of X-rays which have passed through an object or an organ and which are supplied by a point source emitting, towards the object or the organ, a plane beam of X-rays. incidents with a wide angular opening and a small thickness.
  • This invention applies more particularly to the tomography of organs, but also to industrial control, such as baggage control for example.
  • X-ray detectors known in particular from patent application FR-A-2 314 699, make it possible to measure the absorption of an X-ray beam passing through an object or an organ, this absorption being linked to the density of the tissues of the organ examined or the density of the materials constituting the object studied.
  • ionization X-ray detectors used in tomography are of the multicell type and include cells delimited by conductive plates perpendicular to the plane of the X-ray beam and brought alternately to positive and negative potentials. These cells are located in a sealed enclosure containing an ionizable gas.
  • the advantages of this type of multicellular detector are as follows: they provide good collimation of X-rays when the plates used in the detection cells are made of a very absorbent material; the collection time of the charges resulting from the ionization of the gas by X-rays is very short because of the small spacing of the conductive plates and the good separation between the detection cells.
  • this type of detector has significant drawbacks: it is possible to reduce the thickness of the plates in order to increase the quantity of X-rays detected, but to the detriment of collimation due to the small thickness of the plates; this small thickness of the plates also causes a very large microphone.
  • detectors of this type have a great complexity of construction which leads to a high manufacturing cost and they require mounting in a dust-free room, since any dust on one of the plates, can cause an initiation or a deterioration of the leakage current. between two consecutive plates. It is added to these drawbacks that the numerous plates used require very numerous electrical connections, inside the sealed chamber, which poses difficult problems of reliability of the welds of the connections on the plates.
  • This other type of detector comprises a sealed chamber containing a gas ionizable by rays from the organ or object and, in this chamber, a plate for collecting the electrons resulting from the ionization of the gas; this plate is parallel to the plane of the beam of incident rays and it is brought to a positive high voltage.
  • a series of electrodes for collecting the ions resulting from the ionization of the gas by the X-rays coming from the object is arranged in parallel and facing the preceding plate; these ion collection electrodes are brought to a potential close to zero and are directed towards the source which emits X-rays, in the direction of the object.
  • This type of detector has certain advantages: there are no longer, as in the detector mentioned above, separation plates; this eliminates any annoying phenomenon of microphony. Due to the removal of these separation plates, the quantity of X-rays detected is maximum; the realization of this type of detector is very simple and it is very little sensitive to dust.
  • the gas contained in the ionization chamber of this detector is a gas such as xenon; this gas can be added to other gases to improve detection.
  • This type of detector has a serious drawback which results from the fact that during a significant irradiation, the positive ions such as the Xe + ions, of which the number is large, migrate towards the most negative electrode. These ions entrain the gas atoms, which causes gas movements inside the detector causing local overpressures and depressions which disturb the sensitivity of the detection at the locations of these disturbances. In addition, these disturbances are not located at fixed locations in the detector, but move therein, which further disturbs the measurement of currents flowing in the electrodes.
  • the invention aims to remedy these drawbacks and in particular to produce an X-ray detector which has the structure which has just been described, but in which one succeeds, thanks to an additional gas, in reducing the disturbances of the sensitivity of the detector, by attenuating the overpressures and depressions which appear in it, during a significant irradiation.
  • the subject of the invention is an X-ray detector, suitable for example for detecting rays having passed through an object or an organ and being supplied by a source emitting, towards the object, a plane beam of incident X-rays, this beam having a wide angular opening and a small thickness, this detector comprising at least one sealed ionization chamber containing at least one gas ionizable by rays, coming from the object, and, in this chamber, a plate for collecting charges resulting from the ionization of the gas, this plate being parallel to the plane of the beam of incident rays and being brought to a first potential and a series of electrodes for collecting charges resulting from the ionization of the gas, these electrodes for collecting the charges being brought to a second potential and being directed towards the source, in a plane parallel to the plane of the beam of incident rays opposite the charge collection plate, these charge collection electrodes es providing a current resulting from the ionization of the gas opposite each of the electrodes under the effect of X-
  • the electronegative gas is sulfur hexafluoride.
  • this electronegative gas can be oxygen or nitrogen.
  • the ionizable gas is xenon, or another neutral gas.
  • Figure 1 shows schematically and in perspective, a detector according to the invention comprising a plate 1 brought to a positive high voltage + HT and, opposite, a series of planar electrodes 2 brought to a potential close to 0 volts.
  • This plate and these electrodes are located in a sealed main chamber 3, shown diagrammatically and which contains at least one ionizable gas such as xenon for example, added with an electronegative gas such as sulfur hexafluoride SF6, oxygen or nitrogen.
  • This detector makes it possible to detect the X-rays which have passed through an object or an organ 0, these rays being supplied by a source S which emits towards the object or the organ, a plane beam F of incident X-rays; this beam has a wide angular opening and a small thickness.
  • the plate 1 is parallel to the plane of the beam of incident rays, while the electrodes 2 are located in a plane parallel to the plane of the beam of incident rays, opposite the plate 1.
  • the plate 1 which is brought to a neighboring positive potential of a few kilovolts, is a collection plate for negative charges, in particular negative ions SF6--.
  • the electrodes 2 are electrodes for collecting the positive ions obtained by ionization of the gas contained in the detector.
  • these positive ions are Xe + ions.
  • the electrodes are generally carried by an insulating plate (not shown in this figure) and are electrically isolated from each other. They can be obtained by depositing copper on an insulating support.
  • the pressure of the xenon inside the sealed chamber has a value between 5 and 30 bars; this gas can also be added to other gases intended to improve detection.
  • the electrodes 2 form bands converging in the direction of the point source S.
  • the currents which circulate in the electrodes 2, currents induced by the displacement of the charges, are amplified by amplifiers 5, before being treated by a system not shown, allowing the visualization of a section of the organ or the object studied.
  • Negative ions (SF6- for example in the example considered) are captured by plate 1.
  • FIG. 2 schematically represents a side view of the detector of the invention.
  • the plate 1 brought to a positive high voltage + HT this plate is assumed to be fixed to an insulating support 6 and the sealed chamber 3 has not been shown in this figure 3.
  • the detection gas is xenon and that the electronegative gas is sulfur hexafluoride; due to the ionization of the detection gas by X-rays from the object or organ O, the electrode 2 receives positive ions Xe +, while the released electrons are entrained towards the positive plate 1 with the electronegative gas.
  • sulfur hexafluoride SF6, for example. sulfur hexafluoride SF6, for example.
  • the electronegative gas introduced into the detector makes it possible to trap the free electrons coming from the ionization of the gas; this results in a movement of negative ions in the opposite direction to that of positive ions which reduces the importance of the disturbances.
  • the electronegative gas is an inert gas such as sulfur hexafluoride, in order to avoid ter any corrosion in the detector; it is however possible to use a non-inert gas such as oxygen for example, provided that electrodes and a gold plate are used or electrodes and a copper plate covered with a gold foil.

Landscapes

  • Measurement Of Radiation (AREA)
  • Electron Tubes For Measurement (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Claims (5)

1. Röntgenstrahlungsdetektor, beispielsweise für Röntgenstrahlen, die ein Objekt oder Organ (0) durchquert haben und von einer Quelle (S) stammen, die in Richtung des Objektes ein ebenes Bündel (F) von Röntgenstrahlen abgibt, das einen großen Öffnungswinkel und eine geringe Dicke aufweist, bestehend aus wenigstens einer hermetisch abgeschlossenen lonisationskammer (3), die wenigstens ein von den vom Objekt ausgehenden Strahlen ionisierbares Gas enthält, und in der Kammer eine Platte (1) zum Sammeln der Ladungen, die aus der Gasionisation hervorgehen, wobei sich die Platte parallel zur Ebene des Bündels (F) der einfallenden Röntgenstrahlen erstreckt und auf einem ersten Potential (+HT) gehalten ist, und eine Reihe von Elektroden (2) zur Aufnahme von Ladungen, die aus der Gasionisation stammen, wobei diese Ladungen aufnehmenden Elektroden auf einem zweiten Potential gehalten sind und gegen die Quelle (F) in einer Ebene zusammenlaufen, die sich parallel zur Ebene des einfallenden Strahlenbündels (F) gegenüber der Elektronen sammelden Platte (1) erstreckt, wobei jede der Ladung sammelnden Elektroden (2) einen Strom abgibt, der aus der Ionisation des Detektorgases unter der Wirkung von Röntgenstrahlen entsteht, dadurch gekennzeichnet, daß die lonisationskammer (3) weiterhin ein Gas enthält, das dazu geeignet ist, innerhalb des so gebildeten Gemisches eine Gasbewegung im umgekehrten Sinne zur lonenbewegung hervorzurufen.
2. Detektor nach Anspruch 1, dadurch gekennzeichnet, daß das Gas elektronegativ ist.
3. Detektor nach Anspruch 2, dadurch gekennzeichnet, daß das elektronegative Gas Schwefelhexafluorid ist.
4. Detektor nach Anspruch 1, dadurch gekennzeichnet, daß das elektronegative Gas Sauerstoff oder Stickstoff ist.
5. Detektor nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß das ionisierbare Gas Xenon ist.
EP82400628A 1981-04-15 1982-04-06 Röntgenstrahlungsdetektor Expired EP0063082B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8107567 1981-04-15
FR8107567A FR2504277A1 (fr) 1981-04-15 1981-04-15 Detecteur de rayons x

Publications (2)

Publication Number Publication Date
EP0063082A1 EP0063082A1 (de) 1982-10-20
EP0063082B1 true EP0063082B1 (de) 1985-01-23

Family

ID=9257429

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82400628A Expired EP0063082B1 (de) 1981-04-15 1982-04-06 Röntgenstrahlungsdetektor

Country Status (5)

Country Link
US (1) US4461953A (de)
EP (1) EP0063082B1 (de)
JP (1) JPS57179775A (de)
DE (1) DE3262010D1 (de)
FR (1) FR2504277A1 (de)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4691108A (en) * 1983-12-27 1987-09-01 General Electric Company Ionization detector
US5767518A (en) * 1996-11-27 1998-06-16 Westwood Biomedical Fiber optic x-ray exposure control sensor
SE513161C2 (sv) * 1997-11-03 2000-07-17 Digiray Ab En metod och en anordning för radiografi med plant strålknippe och en strålningsdetektor
SE514472C2 (sv) * 1999-04-14 2001-02-26 Xcounter Ab Strålningsdetektor och en anordning för användning vid radiografi
SE514460C2 (sv) * 1999-04-14 2001-02-26 Xcounter Ab Förfarande för detektering av joniserande strålning, strålningsdetektor och anordning för användning vid radiografi med plant strålknippe
SE514443C2 (sv) * 1999-04-14 2001-02-26 Xcounter Ab Strålningsdetektor och en anordning för användning vid radiografi med plant strålknippe
SE514475C2 (sv) * 1999-04-14 2001-02-26 Xcounter Ab Strålningsdetektor, en anordning för användning vid radiografi med plant strålknippe och ett förfarande för detektering av joniserande strålning
SE515884C2 (sv) * 1999-12-29 2001-10-22 Xcounter Ab Förfarande och anordning för radiografi samt strålningsdetektor
SE0000957D0 (sv) * 2000-02-08 2000-03-21 Digiray Ab Detector and method for detection of ionizing radiation
JP4498779B2 (ja) * 2004-03-15 2010-07-07 川崎重工業株式会社 Ｘ線イオンチャンバ検出器およびｘ線検出装置
JP5930628B2 (ja) * 2011-08-22 2016-06-08 株式会社日立製作所 放射線照射装置及び放射線計測方法
KR102679513B1 (ko) 2014-03-26 2024-07-01 벤클로스 인코포레이티드 정맥 질환 치료
CN112326774B (zh) * 2020-10-30 2024-04-23 四川赛康智能科技股份有限公司 高能射线照射sf6气体的电离测试方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2936388A (en) * 1958-12-15 1960-05-10 Talbot A Chubb Counters with a negative-ion-forming vapor additive
US3126479A (en) * 1962-03-01 1964-03-24 X-ray analyzer system with ionization
FR2314699A1 (fr) * 1975-06-19 1977-01-14 Commissariat Energie Atomique Dispositif d'analyse pour tomographie a rayons x par transmission
US4047041A (en) * 1976-04-19 1977-09-06 General Electric Company X-ray detector array
JPS5856957B2 (ja) * 1978-04-21 1983-12-17 日本原子力研究所 放射線計数管

Also Published As

Publication number Publication date
JPS57179775A (en) 1982-11-05
FR2504277A1 (fr) 1982-10-22
EP0063082A1 (de) 1982-10-20
DE3262010D1 (en) 1985-03-07
US4461953A (en) 1984-07-24
FR2504277B1 (de) 1983-05-27

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