EP0459567A2 - Source quasi-monochromatique de rayons X - Google Patents

Source quasi-monochromatique de rayons X Download PDF

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Publication number
EP0459567A2
EP0459567A2 EP91201225A EP91201225A EP0459567A2 EP 0459567 A2 EP0459567 A2 EP 0459567A2 EP 91201225 A EP91201225 A EP 91201225A EP 91201225 A EP91201225 A EP 91201225A EP 0459567 A2 EP0459567 A2 EP 0459567A2
Authority
EP
European Patent Office
Prior art keywords
target
screen
radiation
anode
radiation source
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.)
Granted
Application number
EP91201225A
Other languages
German (de)
English (en)
Other versions
EP0459567A3 (en
EP0459567B1 (fr
Inventor
Geoffrey Dr. Harding
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.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Philips Patentverwaltung GmbH, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Patentverwaltung GmbH
Publication of EP0459567A2 publication Critical patent/EP0459567A2/fr
Publication of EP0459567A3 publication Critical patent/EP0459567A3/de
Application granted granted Critical
Publication of EP0459567B1 publication Critical patent/EP0459567B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details

Definitions

  • the invention relates to a radiation source for generating essentially monochromatic X-rays, with an anode for generating X-rays, a target enclosed by the anode for converting X-rays into fluorescent radiation, and with a screen located between the target and the anode for shielding the target against electrons .
  • Such a radiation source is known from DE-OS 37 16 618.
  • the metal screen has the task of keeping (scattering) electrons away from the target, which would lead to the fact that polychromatic brake radiation is generated in the target in addition to the practically monochromatic fluorescent radiation.
  • This screen is penetrated by the X-ray radiation emitted from the anode, which is converted into fluorescence radiation in the target.
  • the screen is as thin-walled as possible and consists of a low-atom material (e.g. titanium (for a target made of tantalum)).
  • the object of the invention is to design a radiation source of the type mentioned at the outset in such a way that even more fluorescent radiation or monochromatic X-radiation can be generated.
  • This object is achieved in that the screen contains an element with a high atomic number.
  • the invention is based on the knowledge that a screen that has an element with a high atomic number ("high” in the sense of the invention is an atomic number whose deviation from the atomic number of the target material is small compared to the atomic number in question) in the periodic table of the elements contains more X-ray radiation from the anode than an equally strong screen made of a low-atom element, but that the radiation comprising an element with a high atomic number generates braking radiation which is converted in the target mainly into fluorescent radiation. In this way, the overall yield of fluorescent radiation can be increased.
  • a preferred development of the invention provides that the screen and the target each contain the same element with a high atomic number. It is provided in a still further embodiment of the invention that the screen and the target consist of tantalum.
  • the advantage of the further development is, on the one hand, that the thermal expansion of the target and screen is the same in both cases, so that mechanical stresses cannot occur when heated, and, on the other hand, that the spectral purity of the spectrum generated is deteriorated as little as possible, because the characteristic radiation generated in the screen has the same wavelength as the fluorescence radiation generated in the target.
  • tantalum as the material for the target and the screen, the high melting point of this material is added, so that the radiation source can be subjected to a much greater electrical power than is possible with the known radiation source with a titanium screen.
  • the radiation source comprises a piston which encloses an evacuated room in which the anode, the screen and the target are located. While in the known radiation source the screen hermetically seals the radiation source from the outside, so that the target and the surface facing it come into contact with the atmospheric oxygen, the target or this screen surface is in this development within the vacuum space of the radiation source. The screen and the target can therefore withstand high temperatures better.
  • a collimator arrangement is provided which is designed such that only the radiation emanating from the target can pass through the collimator arrangement. As a result, the braking radiation generated in the screen is largely suppressed.
  • the radiation source which is designed to be rotationally symmetrical with respect to an axis 1, comprises a cathode part 2 and an anode part 3, which are connected to one another in a vacuum-tight manner via a piston 4.
  • the cathode part 2 is connected to the piston 4, which is made of metal, via an insulator, not shown, and carries a voltage of, for example, 160 kV or more. It comprises a filament 21 which surrounds the axis of symmetry 1 in a ring and a cathode die 22 which forms the paths of the electrons emitted from the filament 21 in the desired manner.
  • the anode part 3 comprises a hollow body consisting of two parts 32 and 33, the cavity of which is flowed through in the operating state by a liquid coolant supplied from the outside in a manner not shown in detail.
  • a partition 34 prevents the coolant in the shortest possible way from the coolant inlet to the coolant outlet (neither shown) flows.
  • the parts 32 and 33 of the anode body can for example consist of copper.
  • the part 32 of the anode body 32, 33 has an inner surface open towards the cathode part 2 in the form of a truncated cone surface 31.
  • This lateral surface 31 is coated with a material that has a high atomic number, preferably with gold. The electrons emitted from the filament in the operating state hit this inner surface.
  • the electrons impinging on the anode 31 generate X-rays with a spectrum which is continuous up to a quantum energy determined by the voltage between the anode part and the cathode part and on which the line spectrum of gold is superimposed with a K line at approximately 68.8 keV.
  • the X-ray radiation strikes a target 36 made of tantalum through a thin cylindrical screen 35, which has the shape of a cone, the tip of which points away from the cathode part 2.
  • the target essentially converts X-ray quanta with an energy above the K absorption edge of the target (for tantalum approx. 67.4 keV) into monochromatic fluorescence radiation, the quantum energy of which is the characteristic energy of the target material (for tantalum: 57.5 keV) corresponds.
  • the screen 35 which carries the target 36, is fastened in a central bore in the disk-shaped part 33 of the anode body 32, 33, which is closed in a vacuum-tight manner by a window 37.
  • the invention uses the impact of the electrons on the screen 35 to generate additional X-rays.
  • the screen must consist of an element with a high atomic number or contain such an element to a sufficient extent.
  • the atomic number of this element should at most be slightly lower than that of the target, but if possible greater than 50.
  • the electron bombardment of the screen generates not only characteristic radiation but also polychromatic (braking) radiation. A much larger portion of this hits the target than of the radiation from the anode because the screen closely surrounds the target.
  • a suitable element - because of its high atomic number (74) and its high thermal resilience - would be tungsten, for example.
  • a screen made of tantalum is even cheaper than a screen made of tungsten.
  • the quantum energy of the characteristic radiation from tungsten is about 2 keV higher than that from tantalum. Even if the X-rays emitted by the screen were prevented from directly reaching the outside, this radiation could not be prevented from causing elastic or Compton scattering processes at the target, and in this way reaching the outside and impairing the spectral purity of the radiation.
  • the screen must be thick enough to keep the scattering electrons away from the target 36, but on the other hand it must be sufficiently thin so that the radiation emitted by the anode 31 is not weakened too much.
  • a suitable value for the wall thickness of the screen is 0.1 mm. Although this screen absorbs more X-rays than a titanium screen of the same strength, because of the additionally generated X-rays there is a higher emission of quasi-monochromatic radiation from the target 36 than with a titanium screen with the same wall thickness.
  • the screen becomes in operation due to its smaller area and wall thickness, and because of the lack of cooling, much hotter than the anode body.
  • the electrical power that can be supplied to the radiation source is therefore limited by the temperature resistance of the screen 35.
  • a tantalum umbrella is also superior to a titanium umbrella because of its much higher melting point. In connection with the significantly improved conversion of the electrical power into fluorescence radiation, this means that the intensity of the quasi-monochromatic radiation can be several times greater than in the case of a radiation source with a titanium screen.
  • the screen In order to take advantage of the high thermal load capacity of the tantalum components, it must be avoided that the tantalum parts come into contact with atmospheric oxygen. Therefore, the screen must not hermetically seal the radiation source from the outside - as in DE-OS 37 16 618, but must be provided with one or more small openings, not shown, so that the vacuum inside the bulb also the interior of the screen Fulfills.
  • the central hole in which the screen 35 is inserted is closed to the outside by the radiation exit window 37.
  • the radiation exit window is formed by a plate, which can also consist of tantalum. Because of the material used between the target and the radiation exit window, the absorption coefficient of the radiation exit window for the fluorescence radiation generated in the target is relatively low.
  • diaphragm arrangement In front of the radiation exit window there is e.g. from two perforated diaphragms 5, 6 provided diaphragm arrangement which is connected to the radiation source in a manner not shown.
  • the openings in this diaphragm arrangement are dimensioned such that the directly emerging X-ray radiation generated in the screen is largely suppressed by the diaphragm arrangement. This prevents the continuous spectrum of the radiation generated in the screen from affecting the spectral purity of the fluorescent radiation which passes through the diaphragm arrangement.
  • This diaphragm arrangement preferably consists of the same material as the target 36 and the window 37 — in the example, therefore, of tantalum.

Landscapes

  • X-Ray Techniques (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
EP91201225A 1990-05-26 1991-05-22 Source quasi-monochromatique de rayons X Expired - Lifetime EP0459567B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4017002A DE4017002A1 (de) 1990-05-26 1990-05-26 Strahlenquelle fuer quasimonochromatische roentgenstrahlung
DE4017002 1990-05-26

Publications (3)

Publication Number Publication Date
EP0459567A2 true EP0459567A2 (fr) 1991-12-04
EP0459567A3 EP0459567A3 (en) 1992-01-02
EP0459567B1 EP0459567B1 (fr) 1996-01-31

Family

ID=6407256

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91201225A Expired - Lifetime EP0459567B1 (fr) 1990-05-26 1991-05-22 Source quasi-monochromatique de rayons X

Country Status (4)

Country Link
US (1) US5157704A (fr)
EP (1) EP0459567B1 (fr)
JP (1) JP3105292B2 (fr)
DE (2) DE4017002A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6141400A (en) * 1998-02-10 2000-10-31 Siemens Aktiengesellschaft X-ray source which emits fluorescent X-rays

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19639241C2 (de) * 1996-09-24 1998-07-23 Siemens Ag Monochromatische Röntgenstrahlenquelle
DE19805290C2 (de) * 1998-02-10 1999-12-09 Siemens Ag Monochromatische Röntgenstrahlenquelle
DE19905802A1 (de) * 1999-02-12 2000-08-17 Philips Corp Intellectual Pty Röntgenröhre
US7180981B2 (en) 2002-04-08 2007-02-20 Nanodynamics-88, Inc. High quantum energy efficiency X-ray tube and targets
US7158612B2 (en) * 2003-02-21 2007-01-02 Xoft, Inc. Anode assembly for an x-ray tube
CN1302510C (zh) * 2003-05-15 2007-02-28 谭大刚 基于透射阳极x线机的可变换准单能或双能荧光x线源
EP1627409B1 (fr) * 2003-05-19 2008-09-03 Koninklijke Philips Electronics N.V. Source a rayons x fluorescents
US7200203B2 (en) * 2004-04-06 2007-04-03 Duke University Devices and methods for targeting interior cancers with ionizing radiation
WO2006049051A1 (fr) * 2004-11-08 2006-05-11 Sii Nanotechnology Inc. Dispositif d’analyse à rayons x fluorescents
US20070089227A1 (en) * 2005-10-26 2007-04-26 Joseph Battiston Transfer seat with rotatable wing
WO2007088934A1 (fr) * 2006-02-01 2007-08-09 Toshiba Electron Tubes & Devices Co., Ltd. Source de rayons x et dispositif d'analyse de rayons x fluorescents
JP4738189B2 (ja) * 2006-02-01 2011-08-03 東芝電子管デバイス株式会社 Ｘ線源および蛍光ｘ線分析装置
US7876883B2 (en) * 2008-04-10 2011-01-25 O'hara David Mammography X-ray homogenizing optic
JP2012524374A (ja) 2009-04-16 2012-10-11 エリック・エイチ・シルバー 単色ｘ線の方法および装置
WO2014175762A1 (fr) 2013-04-25 2014-10-30 Siemens Aktiengesellschaft Dispositif et procédé de génération de rayons x
EP3641651A4 (fr) * 2017-05-19 2021-04-07 Imagine Scientific, Inc. Systèmes et procédés d'imagerie par rayons x monochromatiques
US10818467B2 (en) * 2018-02-09 2020-10-27 Imagine Scientific, Inc. Monochromatic x-ray imaging systems and methods
JP7299226B2 (ja) 2018-02-09 2023-06-27 イマジン サイエンティフィック，インコーポレイテッド 単色ｘ線撮像システム及び方法
WO2020056281A1 (fr) 2018-09-14 2020-03-19 Imagine Scientific, Inc. Systèmes de composant de rayons x monochromatiques et procédés

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2205297A (en) * 1938-07-23 1940-06-18 Gen Electric X-ray tube
US3567928A (en) * 1969-06-12 1971-03-02 Du Pont Fluorescent analytical radiation source for producing soft x-rays and secondary electrons
US3920999A (en) * 1972-12-05 1975-11-18 Strahlen Und Umweltforachung M X-Ray source
EP0292055A2 (fr) * 1987-05-18 1988-11-23 Philips Patentverwaltung GmbH Source de rayonnement pour la génération de rayons X essentiellement monochromatiques

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3963922A (en) * 1975-06-09 1976-06-15 Nuclear Semiconductor X-ray fluorescence device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2205297A (en) * 1938-07-23 1940-06-18 Gen Electric X-ray tube
US3567928A (en) * 1969-06-12 1971-03-02 Du Pont Fluorescent analytical radiation source for producing soft x-rays and secondary electrons
US3920999A (en) * 1972-12-05 1975-11-18 Strahlen Und Umweltforachung M X-Ray source
EP0292055A2 (fr) * 1987-05-18 1988-11-23 Philips Patentverwaltung GmbH Source de rayonnement pour la génération de rayons X essentiellement monochromatiques

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6141400A (en) * 1998-02-10 2000-10-31 Siemens Aktiengesellschaft X-ray source which emits fluorescent X-rays

Also Published As

Publication number Publication date
EP0459567A3 (en) 1992-01-02
JP3105292B2 (ja) 2000-10-30
DE4017002A1 (de) 1991-11-28
EP0459567B1 (fr) 1996-01-31
JPH04229539A (ja) 1992-08-19
DE59107329D1 (de) 1996-03-14
US5157704A (en) 1992-10-20

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