EP0056552B2 - Tube radiogène comportant un limiteur universel de rayonnement secondaire - Google Patents

Tube radiogène comportant un limiteur universel de rayonnement secondaire Download PDF

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Publication number
EP0056552B2
EP0056552B2 EP81402080A EP81402080A EP0056552B2 EP 0056552 B2 EP0056552 B2 EP 0056552B2 EP 81402080 A EP81402080 A EP 81402080A EP 81402080 A EP81402080 A EP 81402080A EP 0056552 B2 EP0056552 B2 EP 0056552B2
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EP
European Patent Office
Prior art keywords
limiter
ray tube
envelope
radiation
secondary radiation
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 - Lifetime
Application number
EP81402080A
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German (de)
English (en)
French (fr)
Other versions
EP0056552A2 (fr
EP0056552B1 (fr
EP0056552A3 (en
Inventor
Emile Gabbay
Jean-Marie Penato
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.)
Thales SA
Original Assignee
Thomson CSF SA
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Publication date
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Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0056552A2 publication Critical patent/EP0056552A2/fr
Publication of EP0056552A3 publication Critical patent/EP0056552A3/fr
Publication of EP0056552B1 publication Critical patent/EP0056552B1/fr
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators

Definitions

  • the present invention relates to a universal secondary radiation limiter in an X-ray tube. It finds its application both in classical radiology and in radiotherapy.
  • a suitable target When a suitable target is bombarded by a fast flux of electrons, it emits a certain flux of photons in a spectral band related to the nature and the geometry of the target and related to the speed of the electrons.
  • Such generating devices are called X-ray tubes. They emit more particularly in the X-ray or y-ray band. It is also possible to use secondary photonic emissions. In all cases, the focal point is the material area emitting radiation.
  • a ray belonging to the primary radiation can be defined as a direct ray which is carried by a straight line cutting the central axis of the solid angle of the useful radiation at a point common to all the primary rays on the central axis of the primary radiation.
  • a secondary ray is carried by any straight line coming from the transmitting focus. This radiation, often of weak energy compared to the primary radiation, generates bad images in Radiology and parasitic irradiation causes in Radiotherapy. It should therefore be deleted as completely as possible.
  • a patent US-A-4,157,476 describes an X-ray apparatus comprising an X-ray tube, mounted in a protective envelope in which circulates a fluid used to cool the X-ray tube.
  • the protective sheath is made of a material absorbing radiation, and has an opening allowing the passage of an X-ray beam emitted by a focal point formed on an anode of the X-ray tube.
  • a conical sheath, made of an X-ray absorbing material is disposed in said opening and through the protective sheath from the outside of the latter up near the X-ray tube, facing said focal point, so as to constitute a beam limiting device.
  • the present invention proposes placing a secondary radiation limiter in the X-ray tube in the immediate vicinity of the emitting focus.
  • the collimators whose cross section is in the form of a grid or a grid, leave a trace by absorbing primary radiation in the field of the useful beam.
  • an X-ray source is described associated with a sample analysis device further comprising a window structure, that is to say a chamber or the tubular element of frusto-conical shape pointed in the immediate vicinity of the focus of the X-ray target on which the primary electron beam is focused.
  • This tubular chamber allows the useful X-ray beam to be directed radially but does not make it possible to eliminate or at least reduce the secondary radiation because no means is provided for this purpose.
  • the present invention to remedy these drawbacks of the prior art, is a secondary radiation limiter of simple conical shape, one end of which is fixed to the outlet window of the tube and the other close to the focal point emitting the radiation.
  • Secondary radiation may not be emitted only from the home. Indeed, the focus is the area bombarded by the electrons incident on the anode. A certain amount of electrons is emitted from the hearth. These electrons are called secondary electrons. They are expelled from the home with some kinetic energy and are attracted due to the anode potential. They therefore fall on it outside the focus, with an energy such that they also produce secondary radiation but outside the focus, that is to say extrafocal.
  • an X-ray tube comprising a vacuum-tight enclosure containing an anode which has a focal point emitting a useful beam of radiation, and a secondary radiation limiter consisting of an insulating and refractory shell of predetermined thickness of shape. conical, the axis of symmetry of which is aligned with the central axis of the useful radiation beam and made of a material comprising at least one element with a high atomic number so as to absorb secondary radiation, a limiter including the inlet opening of the envelope is located in the immediate vicinity of the emitting source and the outlet opening of which is linked by means of connection to an outlet window for the useful radiation beam.
  • the invention is illustrated by the description of a few X-ray tubes fitted with such limiters.
  • the exemplary embodiments are more particularly drawn from radiology but also find their application in radiotherapy.
  • the X-ray tube shown has a rotating anode 1 included in a vacuum-tight envelope 2. It also includes inside the envelope 2 a photon exciter which is here an electron gun not shown. The flow of electrons strikes the rotating anode 1, at the focal point 4 emitting the flow of photons.
  • the secondary radiation limiter 5 comprises a divergent conqiue envelope 6 of axis of symmetry aligned with the axis 7 of the useful field selected. This limiter 5 has an inlet opening 8 for the photon flux and an outlet opening 9 for the useful radiation.
  • the outlet opening is mechanically linked to the outlet window 10 of the tube.
  • This may include an additional filtration window 11 made of a thin sheet of aluminum or beryllium. This additional filtration has a cumulative effect with the limiter, by absorbing less energetic rays therefore by further depleting the rate of secondary radiation relative to the useful radiation.
  • the mechanical connection means 12 of the outlet opening 9 to the outlet window 10 comprise a ring 13 brazed or welded to a fold in the wall of the envelope 2.
  • the inlet opening 8 is placed in the immediate vicinity of the emitting focus 4 of the photon flux.
  • the projection of the opening 8 on the anode 1 can contain or be contained by the surface of the hearth 4. This characteristic can make it possible to reduce the extent of the emitting hearth or to select, by construction of the tube, a zone of good show.
  • the limiter To be absorbing X photons, the limiter must be made of a material based on a chemical element with a high atomic number. The material must be electrically insulating so as not to induce potential differences with the anode and therefore modify the field lines in the tube. It must also be refractory, since it is placed near the hearth which is a very hot source.
  • the limiter according to the invention consists of a material based on uranium, hafnium or thorium which meet the three qualities mentioned.
  • the material can be an oxide of the three chemical elements mentioned above. It can also consist of a substrate covered with such oxides.
  • the mechanical connection means comprise a ring 13 made of an alloy such as for example the Dilver P or the Vacrion 10 in the case of an envelope made of stainless steel or copper.
  • FIG. 2 a focal point emitting photons AB has been shown in the half-space to the right of the line carrying the focal point AB.
  • the mediating line X is the axis of symmetry of the figure.
  • a schematic representation of a secondary radiation limiter CDEF is shown, the inlet and outlet openings of which are CD and EF respectively.
  • the primary radiation is included in the space limited by the lines GY and GZ, the point G being a point on the axis X of symmetry.
  • a primary radius is therefore defined as a line of this space passing through G.
  • the lines GY and GZ are the lines which carry the sides CE and DF of the limiter. They intercept the edges A and B of the hearth AB in the figure, but they can also cut the interior of the hearth by selecting a fraction.
  • the secondary radiation comprises all the rays carried by the straight lines coming from the focal point AB and which do not pass through the point G. If the walls CE and DF are absorbing the secondary radiation, the two zones of the space included between the straight lines BC and BE and the wall CE on the one hand, and the lines AD and AF and the wall DF on the other hand, are devoid of any secondary radiation. On the other hand, the zones of the space comprised between the lines BA and BC on the one hand and the lines AB and AD on the other hand each comprise secondary radiation. To reduce it, the CD inlet opening of the CDEF limiter should be brought closer to the AB hearth.
  • the extrafocal X-ray radiation is also considerably reduced.
  • an electron is re-emitted on the curve e. It hits the target at point H, outside the focus.
  • the rays of the sector of the space between the HD and HF rays emitted by the point H, called extrafocal rays are intercepted and absorbed by the wall DF of the limiter.
  • the approximation of the entry face CD of the focal point AB, as well as the enlargement of the limiter on the axis GX make it possible to reduce the share of extrafocal radiation in the useful X-ray beam.
  • FIG. 3 a tube with a fixed anode with a well has been shown.
  • the tube comprises a cathode 15 provided with a filament 16 and a concentrator 17.
  • An electron beam 18 penetrates into the well 19 of a fixed anode 20.
  • This anode comprises an emissive target 21 of photons and is pierced with a window 22 for the exit of the radiation.
  • a limiter 23 according to the invention is arranged in a neck 24 of the casing 14 of the tube. Its inlet opening is arranged opposite the window 22 of the fixed anode 20 and its outlet opening is linked as previously indicated to the radiation outlet window 25 with or without an additional filter.
  • the well 19 of the anode also participates in the reduction of the secondary radiation. It may therefore be useful to cover the wells 19 externally with a material as previously described to absorb the secondary radiation.
  • An X-ray tube provided with such a secondary radiation limiter has the advantage of bringing the emitting focus closer to the irradiated object without the intermediary of an external collimation chamber as described in the prior art.
  • the reduction in secondary radiation is considerably improved thanks to the approximation of the input face of the limiter of the emitting focus.
  • the emitting focal point can be constituted by an electron target but also by a target bombarded by incident photons which by Compton effect induce a new flux of photons in an improved spectral band according to a given emission diagram.
  • the limiter according to the invention has been described of the divergent type. It is possible to make it in the form of a converging cone, the inlet opening then being larger than the outlet opening without the main characters of the invention being changed.
  • the limiter according to the invention can therefore be adapted to any type of small focal tube, thus being a universal limiter of secondary radiation.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • X-Ray Techniques (AREA)
  • Radiation-Therapy Devices (AREA)
EP81402080A 1981-01-16 1981-12-28 Tube radiogène comportant un limiteur universel de rayonnement secondaire Expired - Lifetime EP0056552B2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8100775A FR2498375A1 (fr) 1981-01-16 1981-01-16 Limiteur universel de rayonnement secondaire dans un tube radiogene et tube radiogene comportant un tel limiteur
FR8100775 1981-01-16

Publications (4)

Publication Number Publication Date
EP0056552A2 EP0056552A2 (fr) 1982-07-28
EP0056552A3 EP0056552A3 (en) 1982-08-04
EP0056552B1 EP0056552B1 (fr) 1987-02-11
EP0056552B2 true EP0056552B2 (fr) 1990-09-12

Family

ID=9254231

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81402080A Expired - Lifetime EP0056552B2 (fr) 1981-01-16 1981-12-28 Tube radiogène comportant un limiteur universel de rayonnement secondaire

Country Status (4)

Country Link
US (1) US4472827A (en])
EP (1) EP0056552B2 (en])
DE (1) DE3175923D1 (en])
FR (1) FR2498375A1 (en])

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3934321A1 (de) * 1989-10-13 1991-04-18 Siemens Ag Roentgenroehre mit austrittsfenster
FR2655192A1 (fr) * 1989-11-28 1991-05-31 Gen Electric Cgr Anode pour tube a rayons x a corps de base composite.
FR2655191A1 (fr) * 1989-11-28 1991-05-31 Genral Electric Cgr Sa Anode pour tube a rayons x.
US5033074A (en) * 1989-12-04 1991-07-16 Gte Laboratories Incorporated X-ray colllimator for eliminating the secondary radiation and shadow anomaly from microfocus projection radiographs
US5479021A (en) * 1991-06-10 1995-12-26 Picker International, Inc. Transmission line source assembly for spect cameras
FR2694504B1 (fr) * 1992-08-04 1994-09-16 Joel Kerjean Procédé et appareil pour le traitement de lésions par rayonnement à haute énergie.
FR2748848B1 (fr) * 1996-05-20 2003-03-07 Ge Medical Syst Sa Enveloppe pour source de rayonnement electromagnetique et procede pour l'elimination du rayonnement electromagnetique extrafocal
US6320936B1 (en) * 1999-11-26 2001-11-20 Parker Medical, Inc. X-ray tube assembly with beam limiting device for reducing off-focus radiation
DE10320700A1 (de) * 2003-05-08 2004-12-02 Siemens Ag Vakuumgehäuse für eine Röntgenröhre
DE102004025119B4 (de) * 2004-05-21 2012-08-02 Siemens Ag Röntgenstrahler
EP1941516A2 (en) * 2005-09-06 2008-07-09 Honeywell International Inc. Radio-opaque coatings used as shielding for radiation sources
WO2011010995A1 (en) 2009-07-21 2011-01-27 Analogic Corporation Anti-scatter grid or collimator
US8262288B2 (en) * 2010-01-21 2012-09-11 Analogic Corporation Focal spot position determiner
US9478050B2 (en) 2011-01-06 2016-10-25 Koninklijke Philips N.V. Imaging system for imaging an object
DE102018112054B4 (de) * 2018-05-18 2023-02-09 Yxlon International Gmbh Röntgenröhre mit Kollimator und Kollimatorvorrichtung für geschlossene Röntgenröhre

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1051495A (fr) * 1951-12-17 1954-01-15 Radiologie Cie Gle Perfectionnements aux appareils générateurs de rayonnement x
CH323153A (de) * 1953-07-18 1957-07-15 Philips Nv Vollschutz-Röntgenröhre, insbesondere für die Werkstoffprüfung
US3500097A (en) * 1967-03-06 1970-03-10 Dunlee Corp X-ray generator
FR2038757A5 (en) * 1969-03-28 1971-01-08 Atome Ind Radiation collimator
JPS5811079B2 (ja) * 1976-10-05 1983-03-01 株式会社東芝 Ｘ線源装置
NL7704473A (nl) * 1977-04-25 1978-10-27 Philips Nv Roentgenbuis.
US4157476A (en) * 1978-02-03 1979-06-05 General Electric Company Dental X-ray tube head
US4309637A (en) * 1979-11-13 1982-01-05 Emi Limited Rotating anode X-ray tube
US4343997A (en) * 1980-07-14 1982-08-10 Siemens Medical Laboratories, Inc. Collimator assembly for an electron accelerator

Also Published As

Publication number Publication date
FR2498375B3 (en]) 1983-09-16
EP0056552A2 (fr) 1982-07-28
EP0056552B1 (fr) 1987-02-11
FR2498375A1 (fr) 1982-07-23
EP0056552A3 (en) 1982-08-04
DE3175923D1 (en) 1987-03-19
US4472827A (en) 1984-09-18

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