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EP1280389A1 - Système de rayons X pour l'acquisition des radiographies - Google Patents

Système de rayons X pour l'acquisition des radiographies Download PDF

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Publication number
EP1280389A1
EP1280389A1 EP02016806A EP02016806A EP1280389A1 EP 1280389 A1 EP1280389 A1 EP 1280389A1 EP 02016806 A EP02016806 A EP 02016806A EP 02016806 A EP02016806 A EP 02016806A EP 1280389 A1 EP1280389 A1 EP 1280389A1
Authority
EP
European Patent Office
Prior art keywords
ray
emitter
grid
high voltage
current
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
EP02016806A
Other languages
German (de)
English (en)
Other versions
EP1280389B1 (fr
Inventor
Joachim Brendler
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 Intellectual Property and Standards GmbH
Philips Corporate Intellectual Property GmbH
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 Intellectual Property and Standards GmbH, Philips Corporate Intellectual Property GmbH, Koninklijke Philips Electronics NV filed Critical Philips Intellectual Property and Standards GmbH
Publication of EP1280389A1 publication Critical patent/EP1280389A1/fr
Application granted granted Critical
Publication of EP1280389B1 publication Critical patent/EP1280389B1/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
    • H01J35/045—Electrodes for controlling the current of the cathode ray, e.g. control grids
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting

Definitions

  • the invention relates to an x-ray system with at least one x-ray emitter provided with a control grid for generating x-ray images, at least one x-ray image converter with means for electronically reading out x-ray images and an x-ray generator for supplying the x-ray emitter.
  • the invention also relates to an X-ray generator suitable for such an X-ray system.
  • This problem is particularly pronounced when recording thin objects, for example in pediatrics, because due to the small object thickness and a predetermined value of the high voltage (e.g. 70 kV) only a very small mAs value may be switched (approx. 0 , 05 mAs). Due to the energy stored in the stored capacities, only mAs values that are several times higher than the desired mAs value can be switched with X-ray emitters (without control grid). With these values, an overexposure of an X-ray image can only be avoided if - contrary to e.g. B. the IEC regulations - the recording takes place at a lower voltage on the X-ray tube. With a lower voltage on the X-ray tube, however, the radiation exposure for the patient is greater.
  • the high voltage e.g. 70 kV
  • the new X-ray emitter already at the beginning of the preparation phase preceding an X-ray in the z. B. revolved the anode and the filament of the cathode of this X-ray tube is heated, X-rays emitted in an undesirable manner.
  • the object of the present invention is to provide an x-ray system or an x-ray generator with which, on the one hand, an accurate exposure of the x-ray image is possible and, on the other hand, at least largely avoid the problems which arise during the rapid transition from x-ray images with grid control to x-ray images without Grid control result.
  • the control grid or the current is blocked by the x-ray emitter.
  • the X-ray radiation is interrupted in this time interval, so that no further exposure of the X-ray image converter (or no overexposure) takes place. Due to the blocking of the X-ray emitter, the high voltage on the X-ray emitter decreases only very slowly in this time interval.
  • 1 and 2 denote two converter generators connected in series (with an earthed connection point), which usually have the following components, not shown in the drawing: a rectifier for generating a DC voltage from a mains voltage, an inverter for generating an AC voltage with a frequency in the KHz range and adjustable amplitude, and a high voltage generator with a high voltage transformer for generating a high voltage and a rectifier for rectifying the high voltage.
  • the converter generators 1 and 2 thus supply adjustable DC voltages of up to ⁇ 75 kV at their outputs.
  • the voltages supplied by the converter generators 1 and 2 can be adjusted in amplitude by a control circuit 3 and switched on and off.
  • the output voltages of the converter generators 1 and 2 are fed to an X-ray source 4 via two high-voltage cables 8, 9.
  • the X-ray emitter has on the cathode side, a first electron emitter 41, which can deliver a comparatively low electron current, which strikes the opposite anode 43 in a comparatively small focal spot, and a second, substantially larger electron emitter 42, which can emit a substantially larger electron current, which on the anode 43 in a much larger focal spot.
  • both electron emitters can be activated one after the other - preferably automatically, depending on how strongly the object 5 in the beam path absorbs the X-rays.
  • the two electron emitters 41 and 42 can be formed by filament filaments with external dimensions suitable for the respective focal spot.
  • One of the two electron emitters can be connected to a heating current source 44 via a switch 43.
  • the filament 42 is connected directly to the combination 43, 44, the filament 41 for the smaller focus is connected to this combination via a transmitter 45.
  • a control grid 46 is provided for switching the electron current of the electron emitter 41 on and off.
  • This control grid is an electrode, the potential of which can be changed in relation to the potential of the filament 41.
  • This control grid can be produced particularly easily if the cathode head which is anyway required for the formation of the electron paths emerging from the electron emitters and which is provided with an opening for each of the two electron emitters is used. Since the opening for the larger electron emitter 42 is larger, the electron current emitted by it could not be prevented with a comparatively small voltage (a few kV) between this grid 46 and the electron emitter 42.
  • the electron emitter 42 and the electrode 46 are therefore electrically connected to one another and carry the same potential, which is defined by the negative output voltage of the converter generator 2, which is supplied to the electron emitter 42 via the high-voltage cable 9.
  • the electron current emitted by the electron emitter 41 can be interrupted if the potential at the control grid 46 is a few kV more negative than at the electron emitter 41.
  • a voltage divider is provided, to which the Output voltage of the converter generator 2 is supplied for the negative high voltage and which comprises a fixed resistor 10 and an electronically controllable resistor 11.
  • One connection of the resistor 11 is galvanically connected to the electron emitter 41 via the transformer 11 and the other connection is connected to the high voltage output of the converter generator 2 and thus galvanically to the control grid 46.
  • the voltage drop across the resistor 11 therefore determines the magnitude of the bias voltage between the grid 46 and the electron emitter 41.
  • the electronically controllable resistor 11, can contain, for example, transistors connected in series, the conductivity of which can be switched from a first state to a second state by a grid control circuit 12.
  • the resistor 11 In the first switching state, the resistor 11 has a very high conductivity, so that practically the entire voltage drops across the resistor 10 and the electron emitter 41 has almost the same potential as the grid 46. In this state, the electrons emitted from the electron emitter 41 can completely the anode Reach 43.
  • the conductivity of the controllable resistor 11 is lower, so that a voltage drop of a few kV occurs across it. The potential at the grid 46 is then corresponding to this voltage drop more negative than the potential at the electron emitter 41, whereby the electron flow from the electron emitter 41 to the anode 43 is blocked.
  • the x-ray radiation generated by the x-ray emitter passes through the examination object 5 and is detected by an x-ray image converter which can be read out electronically.
  • the X-ray image converter can, for example, be a variety of e.g. B. 2000 x 2000 matrix-arranged photosensitive elements, which are arranged behind a fluorescent layer that converts the X-rays into visible light.
  • any other electronically readable X-ray image converter can be used, for example an X-ray image intensifier whose output image is converted into electrical signals by a CCD camera.
  • an image processing device 7 coupled to the X-ray image converter 6 contains a digital image, and the X-ray image converter can then be exposed again.
  • the image processing device 7, the grid control circuit 12 and the circuit 3 for switching the converter generators 1, 2 on and off are controlled by a control unit 13.
  • the course of an X-ray exposure over time is to be explained below with reference to FIG. 2, which represents the course over time of various electrical variables of the X-ray system shown in FIG. 1.
  • the first line shows the time profile of the high voltage U on the X-ray emitter 4.
  • the second line shows the time profile of the output signal S of the circuit 3, by means of which the high voltage is switched on and off.
  • the third line shows the time profile of the voltage between the grid and the cathode, while the fourth line shows the time profile of the dose rate D generated by the X-ray emitter 4.
  • the heating current source 44 Before the time T 1 , ie before the high voltage is switched on by the signal S, there is no voltage U at the X-ray emitter, and the voltage between the grid and the cathode is also zero. No X-rays are generated.
  • the heating current source 44 already heats up the electron emitter 41 and the anode 43 of the X-ray emitter 4, which is designed as a rotating anode, is revved up, so that at the end of this preparation time the full speed of the anode is reached and the electron emitter reaches a certain one Temperature has reached.
  • the switching signal S activates the converter generators 1 and 2, so that the voltage U on the X-ray source rises until it has reached a stationary value.
  • the voltage between the grid cathode remains at its previous value, so that the electron current can reach the anode unhindered and X-rays are generated.
  • the X-ray exposure is ended at time T 2 .
  • This end of recording can be generated by a timer or an automatic X-ray exposure device when the dose behind the object 5 has reached a certain value.
  • the conductivity of the controllable resistor 11 is suddenly reduced, so that the voltage between the grid and the cathode becomes negative and the electron flow through the X-ray tube 4 is blocked or interrupted; the X-ray image converter is therefore no longer exposed.
  • the high-voltage generation of the converter generators 1 and 2 is stopped.
  • the voltage U on the X-ray emitter decreases only very slowly in this phase due to the energy stored in the cable capacities and in the other capacities of the system.
  • the reading of the X-ray image converter which ends at time T 3 , also begins at time T 2 (for example 200 ms after time T 2 ).
  • the current through the x-ray emitter and thus the x-ray radiation must be interrupted during the reading.
  • the invention has been described above in connection with an electronically readable X-ray image converter.
  • the invention is also applicable to X-ray image converters that automatically - for. B. with a trolley - are transported from the beam path.
  • This can be, for example, a film / film combination that is moved into a park position after the exposure or a storage phosphor that is transported to a reading station where the X-ray exposure is read out with the aid of a laser.
  • highly sensitive image converters of this type or when recording the overexposure problem described at the beginning also arises from thin objects. It is eliminated in that the control grid remains locked in the time interval following the x-ray exposure in which the x-ray image converter is transported out of the beam path.

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Generation Of Surge Voltage And Current (AREA)
EP02016806A 2001-07-28 2002-07-26 Système de rayons X pour l'acquisition des radiographies Expired - Lifetime EP1280389B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10136947A DE10136947A1 (de) 2001-07-28 2001-07-28 Röntgensystem zur Erzeugung von Röntgenaufnahmen
DE10136947 2001-07-28

Publications (2)

Publication Number Publication Date
EP1280389A1 true EP1280389A1 (fr) 2003-01-29
EP1280389B1 EP1280389B1 (fr) 2007-10-10

Family

ID=7693496

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02016806A Expired - Lifetime EP1280389B1 (fr) 2001-07-28 2002-07-26 Système de rayons X pour l'acquisition des radiographies

Country Status (4)

Country Link
US (1) US6570958B2 (fr)
EP (1) EP1280389B1 (fr)
JP (1) JP2003142295A (fr)
DE (2) DE10136947A1 (fr)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006529052A (ja) * 2003-05-16 2006-12-28 コーニンクレッカ　フィリップス　エレクトロニクス　エヌ　ヴィ Ｘ線画像を曝射するための方法及び装置
WO2008020886A2 (fr) * 2006-02-09 2008-02-21 L-3 Communications Security And Detection Systems, Inc. Systèmes et procédés de balayage par rayonnement
DE102009051633B4 (de) 2009-11-02 2015-10-22 Siemens Aktiengesellschaft Spannungsstabilisierung für gittergesteuerte Röntgenröhren
US9069092B2 (en) 2012-02-22 2015-06-30 L-3 Communication Security and Detection Systems Corp. X-ray imager with sparse detector array
JP6441015B2 (ja) * 2014-10-06 2018-12-19 キヤノンメディカルシステムズ株式会社 Ｘ線診断装置及びｘ線管制御方法
US10991539B2 (en) * 2016-03-31 2021-04-27 Nano-X Imaging Ltd. X-ray tube and a conditioning method thereof
US10290460B2 (en) 2016-09-07 2019-05-14 General Electric Company X-ray tube with gridding electrode
DE102016222365B3 (de) * 2016-11-15 2018-04-05 Siemens Healthcare Gmbh Verfahren, Computerprogrammprodukt, computerlesbares Medium und Vorrichtung zur Erzeugung von Röntgenpulsen bei einer Röntgenbildgebung
EP4024436A1 (fr) * 2020-12-31 2022-07-06 VEC Imaging GmbH & Co. KG Source de rayons x multi-source hybride et système d'imagerie
CN113345782B (zh) * 2021-05-28 2022-07-01 武汉联影医疗科技有限公司 X射线管的阴极发射装置、x射线管、高压线缆和方法
DE102022206833B4 (de) * 2021-09-01 2025-06-18 Siemens Healthineers Ag Betreiben einer Röntgenröhre
JP2024037615A (ja) * 2022-09-07 2024-03-19 キヤノンメディカルシステムズ株式会社 Ｘ線診断装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2064893A (en) * 1979-11-21 1981-06-17 Emi Ltd Circuit for controlling the grid potential of a pulsed X-ray tube
WO2000052972A1 (fr) * 1999-03-02 2000-09-08 Hamamatsu Photonics K.K. Generateur de rayons x, installation de radiographie et systeme d'inspection aux rayons x

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4366395A (en) 1979-11-21 1982-12-28 Emi Limited Circuit for controlling the grid potential of a pulsed X-ray tube
JP4127728B2 (ja) 1998-01-13 2008-07-30 株式会社東芝 パルスｘ線装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2064893A (en) * 1979-11-21 1981-06-17 Emi Ltd Circuit for controlling the grid potential of a pulsed X-ray tube
WO2000052972A1 (fr) * 1999-03-02 2000-09-08 Hamamatsu Photonics K.K. Generateur de rayons x, installation de radiographie et systeme d'inspection aux rayons x
EP1158842A1 (fr) * 1999-03-02 2001-11-28 Hamamatsu Photonics K.K. Generateur de rayons x, installation de radiographie et systeme d'inspection aux rayons x

Also Published As

Publication number Publication date
US20030021380A1 (en) 2003-01-30
US6570958B2 (en) 2003-05-27
JP2003142295A (ja) 2003-05-16
EP1280389B1 (fr) 2007-10-10
DE50211031D1 (de) 2007-11-22
DE10136947A1 (de) 2003-02-06

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