US3852605A - Control circuitry for preventing damage to the target of a scanning x-ray generator - Google Patents

Control circuitry for preventing damage to the target of a scanning x-ray generator Download PDF

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Publication number
US3852605A
US3852605A US00427071A US42707173A US3852605A US 3852605 A US3852605 A US 3852605A US 00427071 A US00427071 A US 00427071A US 42707173 A US42707173 A US 42707173A US 3852605 A US3852605 A US 3852605A
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United States
Prior art keywords
electron beam
scanning
target
set forth
signals
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Expired - Lifetime
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US00427071A
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English (en)
Inventor
E Watanabe
E Kato
K Nakamura
T Fujii
T Shimomura
T Ito
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Jeol Ltd
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Jeol Ltd
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    • 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
    • H05G1/30—Controlling
    • H05G1/52—Target size or shape; Direction of electron beam, e.g. in tubes with one anode and more than one cathode
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/40—Arrangements for generating radiation specially adapted for radiation diagnosis
    • A61B6/4021—Arrangements for generating radiation specially adapted for radiation diagnosis involving movement of the focal spot
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/14—Arrangements for concentrating, focusing, or directing the cathode ray
    • H01J35/147—Spot size control
    • 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
    • H05G1/66—Circuit arrangements for X-ray tubes with target movable relatively to the anode

Definitions

  • This invention relates to an X-ray generating apparatus, particularly an X-ray generating apparatus in which the electron beam continuously or flying spot scans an X-ray generating target.
  • the X-ray thus obtained is made to irradiate an object and the X-ray transmitted through said object is detected, and the detected signal supplied to a cathode ray tube synchronized with the electron beam of the X-ray generator or the like, it is possible to'obtain a transmission X-ray image based on the continuous or flying spot scanning X-ray.
  • the intensity of the generated X-ray is weak. Accordingly, the resolution and contrast of the transmission X-ray image are poor; moreover, since the number of frames per second is limited, good pictures cannot be obtained.
  • V is the'accelerating voltage
  • P is the power of incident electron beam
  • K is a constant.
  • the power of the incident electron beam and the related acceleratingvoltage must be increased.
  • the electrical power of the electron beam irradiating 'a given area of the target is limited as shown in the following formula.
  • Wmax 17.8 (Tm-T) a K
  • Wmax is the maximum allowable target load
  • g 2 target is the specific heat (Cal/g" C) of the material constituting the target, and V is the travel rate of the target (cm/sec).
  • the formula shows that, by increasing the target travel rate, the target input power and the X-ray beam intensity are also increased. For example, if a copper target is used, the diameter of the electron beam is 1mm and the travel rate of the target is 2,000cm/sec, thus allowing an input power 10 times larger than that in the static state.
  • the conventional X-ray generating apparatus is designed to give a fairly strong X-ray beam by using a rotating target.
  • a rotating target since the diameter of the electron beam on the target is sometimes very small (in the order of several to several tens of microns) and moreover, since the electron beam remains at a fixed position for a specific period, if the. rotating target referred to above is used, even a minute vibration of the target will adversely effect the X-ray picture displayed on the C. R. T., etc.
  • the electron beam is usually deflected by a deflection means and then continuously or flying spot scanned over the target.
  • this type of device it is theoretically possible to increase the electron beam current according to the increase in scanning speed and thus generate a strong X-ray beam.
  • the contingency to be considered is that for some reason or other,.the rate of travel of the electron beam irradiating the target might be reduced or the beam might come to a complete standstill.
  • the heat generated when the electron beam current exceeds a certain limit is sufficient tocause the target to evaporate.
  • An object of this invention is to provide a continuous or flying spot type scanning X-ray generating apparatus capable of generating an extremely strong X-ray beam.
  • Another object of this invention is to provide a continuous' or flying spottype scanning 'X-ray generating apparatus capable of preventing the target from being damaged.
  • a continuous or flying spot type scanning X-ray generating apparatus has incorporated means for detecting the continuous or flying spot scanning speed of the electron beam and for controlling the beam according to said scanning speed.
  • the scanning speed may be obtained by measuring the distance travelled by the electron beam over the target I per unit time, said distance corresponding to the wave Tm is the melting point (C) of the material constitutstate only; if the target is moved at high speed, the heat distribution over the target will vary, so that the maximum allowable load Wmax becomes as follows.
  • the deflection signal is supplied to a wave-amplitude detector and a frequency detector and the two different output signals from these detectors are supplied to a multiplier circuit so as to obtain the product of both signals.
  • the deflection signal is supplied to a wave-amplitude detector and a frequency detector and the two different output signals from these detectors are supplied to a multiplier circuit so as to obtain the product of both signals.
  • the travelling speed of the electron beam on the target can be ascertained.
  • FIG. 1 is a block diagram showing one embodiment of this invention.
  • FIGS. 2 to 7 are block diagrams showing other embodiments of this invention.
  • an X-ray generating device 1 has at one end an electron gun comprised of a filament 2 and a Wehnelt electrode 3.
  • the electron'beam generated by said electron gun is accelerated by an anode 4 and focussed by first and second condenser lenses 5 and 6 on an X-ray generating target 7.
  • Said condenser lenses are energized by an scintillation power source 9,
  • Electron beam deflection coils 10 and 11 are provided between said condenser lenses 5 and 6, said deflection coils being supplied with deflecting signals by the control unit 8 via an amplifier 12.
  • an X-ray is generated from said target which passes through a pinhole 14 via a transmission window 13 in order to irradia'te an externally located objectlS.
  • the X-ray transmitted through said object 15 then enters an X-ray detector. 16 such as a scintallation detector. where it is detected.
  • the signal detected by the X-ray detector 16 after being amplified by an amplifier 17, is fed into a cathode ray tube 18 to which synchronizing deflection signals are applied from the control unit 8.
  • the: electron beam generated by the electron gun forming part of the X-ray generating tube 1 is finely focussed on the target 7 by condenser lenses 5 and 6 and deflected by deflection coils l0 and 11. Accordingly, said electron beam continuously or flying spot scans the target in accordance with the deflection signal supplied to said deflection coils.
  • the X-ray generating position of the target varies with time and since the direction of projection of the X-rays passing through the pinhole 14 varies in accordance with the irradiating position of the electron beam on said target, the object 15 is continuously or flying spot scanned by a beam of X -rays and a continuous or flying spot X-ray transmission image of said object is thereby displayed on the cathode ray tube 18.
  • the deflecting signal supplied to the deflection coils by the amplifier 12 is also supplied to a wave-amplitude the distance travelled by the electron beam over the target and the step number or'flying spot number corre sponds to the travelling time of said electron beam over said target. Accordingly, the product of the two different signals corresponds to the mean velocity of the electron beam on the target, and the signal corresponding to said velocity is supplied to the electron gun bias power source'22from the multiplier 21.
  • the bias voltage applied between the filament 2 and the Wehnelt electrode 3 from said bias power source 22 varies in ac-
  • the electron beam current increases and the density of the electron beam increases, thereby increasing the intensity of the X-ray beam generated by said target/On the other hand
  • the electron gun bias voltage is increased by the signal supplied to the bias power source 22 by the multiplier 21, thereby decreasing the density of said electron beam.
  • FIG. 2 shows another embodiment of this invention in which electron beam emission is suspended when the scanning speed of the electron beam on the target drops below a certain predetermined value.
  • This is achieved by providing a comparison circuit 23, a standard signal generator 24 and a control signal generator such as a pulse generator 25.
  • the output signal from the multiplier 21 is fed into the comparison circuit 23 together with a standard signal from the standard signal generator 24 and compared.
  • a pulse signal is generated by the pulse generator 25.
  • This pulsesignal is then supplied to the electron gun power source 22 which causes an increase in the bias voltage between the filament 2 and the Wehnelt electrode 3, thereby terminating'the outflow of electrons from the electron gun.
  • the electron gun power source 22 causes an increase in the bias voltage between the filament 2 and the Wehnelt electrode 3, thereby terminating'the outflow of electrons from the electron gun.
  • FIGS. 3, 4 and 5 show variations of the'general concept exemplified in the embodiment shown in FIG. 2.
  • a signal from the pulse generator 25 is supplied to the power source 27 of a rapid response, air cored or electrostatic auxiliary lens 26.
  • the power source 27 is switched-on and current or voltage is supplied to said auxiliary lens 26.
  • the spot diameter of the electron beam irradiating the target is instantaneously enlarged and the beam density is consequently reduced.
  • an electrostatic or electromagnetic deflection means 28 is arranged between the condenser lens means will operate to shift or deflect the electron beam over the surface of the target at high speed. In this case, it would be a good idea to deflect the beam so as to irra# diate a portion of the target surface where the generated X-rays are unable to reach the object.
  • the deflecting means 28 functions so as to deflect the electron beam to an extent such that it ceases to irradiate the target 7.
  • the power source 30 activated by a pulse from the pulse generator 25 supplies a constant DC. voltage to said deflecting means.
  • a secondary or auxiliary target 31 has been provided to prevent the inner wall of the X-ray generating device 1 from becoming pitted due to repeated electron beam impingement.
  • the embodiment shown in FIG. 6 is a modified version of the embodiment shown in FIG. 1 and is ideally suited when scanning the electron beam continuously.
  • 32 is a differential circuit which is connected to the output of the deflection signal amplifier I2 and which serves to detect the rate of variation of the deflection signal.
  • the signal from said differential circuit is supplied to the control unit 33 to control the bias power source 22, the condenser lens excitation power source 9 and/or the filament heating power source.
  • a differential amplifier of simple construction would serve ideally as a control unit.
  • Circuit construction can be further simplified by dispensing with the constant signal generating circuit 34 and the multiplier 21 and regulating the detector 19 (or detector output signals. This is possible as the in-,
  • FIGS. 6 and 7 can be applied to theembodiments described in FIGS. 2 to 5.
  • a scanning X-ray generating apparatus comprismg,
  • g. means for controlling the. electron beam in response to said obtained signals to prevent damage to the target.
  • the means for obtaining signals indicative of the travelling rate of the electron beam scanning said target comprises a means for detecting the frequency of the scanning signals, a means for detecting the wave-amplitude of said signals, and a means for obtaining the product of the output signals from said scanning signal frequency and wave amplitude detecting means.
  • the means for obtaining signals indicative of the travelling rate of the scanning electron beam comprises means for maintaining a constant scanning frequency and means for measuring the scanning wave-amplitude.
  • the means for obtaining signals indicative of the travelling rate of the scanning electron beam comprises means for maintaining thescanning wave-amplitude constant and means for measuring the scanning frequency.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Medical Informatics (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • Radiology & Medical Imaging (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Optics & Photonics (AREA)
  • Pathology (AREA)
  • Physics & Mathematics (AREA)
  • Biomedical Technology (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • Biophysics (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)
US00427071A 1972-12-27 1973-12-21 Control circuitry for preventing damage to the target of a scanning x-ray generator Expired - Lifetime US3852605A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP732159A JPS5318318B2 (US20100154141A1-20100624-C00001.png) 1972-12-27 1972-12-27

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US (1) US3852605A (US20100154141A1-20100624-C00001.png)
JP (1) JPS5318318B2 (US20100154141A1-20100624-C00001.png)
DE (1) DE2364142C3 (US20100154141A1-20100624-C00001.png)
FR (1) FR2212739B1 (US20100154141A1-20100624-C00001.png)
GB (1) GB1444109A (US20100154141A1-20100624-C00001.png)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4010370A (en) * 1974-11-13 1977-03-01 Emi Limited Computerized tomography apparatus with means to periodically displace radiation source
US4066902A (en) * 1974-03-23 1978-01-03 Emi Limited Radiography with detector compensating means
DE2730889A1 (de) * 1977-07-08 1979-01-18 Strahlen Umweltforsch Gmbh Einrichtung zur ortsaufloesenden materialuntersuchung einer probe
US4149076A (en) * 1976-04-05 1979-04-10 Albert Richard D Method and apparatus producing plural images of different contrast range by X-ray scanning
US4158142A (en) * 1977-03-17 1979-06-12 Haimson Research Corporation Method and apparatus incorporating no moving parts, for producing and selectively directing x-rays to different points on an object
US4160909A (en) * 1976-08-12 1979-07-10 E M I Limited X-ray tube arrangements
US4323779A (en) * 1977-06-03 1982-04-06 Albert Richard David Scanning radiographic method
US4352021A (en) * 1980-01-07 1982-09-28 The Regents Of The University Of California X-Ray transmission scanning system and method and electron beam X-ray scan tube for use therewith
DE3222514A1 (de) * 1982-06-16 1984-03-22 Feinfocus Röntgensysteme GmbH, 3050 Wunstorf Verfahren und vorrichtung zur erzeugung von roentgenstrahlung fuer stereoaufnahmen, tomografien und tomosynthesen
DE3222515A1 (de) * 1982-06-16 1984-03-22 Feinfocus Röntgensysteme GmbH, 3050 Wunstorf Feinfokus-roentgenroehre
EP0168776A2 (de) * 1984-07-19 1986-01-22 Scanray A/S Röntgenröhre
EP0173047A2 (de) * 1984-08-27 1986-03-05 Scanray A/S Röntgenröhre
US4631742A (en) * 1985-02-25 1986-12-23 General Electric Company Electronic control of rotating anode microfocus x-ray tubes for anode life extension
US5200985A (en) * 1992-01-06 1993-04-06 Picker International, Inc. X-ray tube with capacitively coupled filament drive
US5241577A (en) * 1992-01-06 1993-08-31 Picker International, Inc. X-ray tube with bearing slip ring
US5274690A (en) * 1992-01-06 1993-12-28 Picker International, Inc. Rotating housing and anode/stationary cathode x-ray tube with magnetic susceptor for holding the cathode stationary
US5291538A (en) * 1992-01-06 1994-03-01 Picker International. Inc. X-ray tube with ferrite core filament transformer
US20050163281A1 (en) * 2002-05-31 2005-07-28 Hans Negle X-ray tube
WO2007066243A3 (en) * 2005-12-08 2008-01-03 Koninkl Philips Electronics Nv Systems and methods for scanning and data acquisition in computed tomography (ct) applications
US20100142681A1 (en) * 2007-05-03 2010-06-10 Lars Lantto Arrangement for generation of x-ray radiation with a large real focus and a virtual focus adjusted according to requirements

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4196351A (en) * 1977-06-03 1980-04-01 Albert Richard David Scanning radiographic apparatus
JPS6322829Y2 (US20100154141A1-20100624-C00001.png) * 1979-10-05 1988-06-22
JPH0748091Y2 (ja) * 1992-06-04 1995-11-08 株式会社セイバン かばんの蓋止め具
AU3009597A (en) * 1996-05-07 1997-11-26 American Science And Engineering Inc. X-ray tubes for imaging systems
GB9620160D0 (en) * 1996-09-27 1996-11-13 Bede Scient Instr Ltd X-ray generator
US5896486A (en) * 1997-05-01 1999-04-20 Lucent Technologies Inc. Mass splice tray for optical fibers
BE1012248A6 (fr) * 1998-10-26 2000-08-01 Ind Control Machines S A Dispositif de controle a rayons x
US6236713B1 (en) 1998-10-27 2001-05-22 Litton Systems, Inc. X-ray tube providing variable imaging spot size
DE102005041923A1 (de) * 2005-09-03 2007-03-08 Comet Gmbh Vorrichtung zur Erzeugung von Röntgen- oder XUV-Strahlung
US9748070B1 (en) 2014-09-17 2017-08-29 Bruker Jv Israel Ltd. X-ray tube anode
GB2565138A (en) * 2017-08-04 2019-02-06 Adaptix Ltd X-ray generator
US11302508B2 (en) 2018-11-08 2022-04-12 Bruker Technologies Ltd. X-ray tube

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746862A (en) * 1970-11-30 1973-07-17 Picker Corp Protective circuit for x-ray tube and method of operation
US3783287A (en) * 1972-05-18 1974-01-01 Picker Corp Anode current stabilization circuit x-ray tube having stabilizer electrode

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3746862A (en) * 1970-11-30 1973-07-17 Picker Corp Protective circuit for x-ray tube and method of operation
US3783287A (en) * 1972-05-18 1974-01-01 Picker Corp Anode current stabilization circuit x-ray tube having stabilizer electrode

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4066902A (en) * 1974-03-23 1978-01-03 Emi Limited Radiography with detector compensating means
US4010370A (en) * 1974-11-13 1977-03-01 Emi Limited Computerized tomography apparatus with means to periodically displace radiation source
US4149076A (en) * 1976-04-05 1979-04-10 Albert Richard D Method and apparatus producing plural images of different contrast range by X-ray scanning
US4160909A (en) * 1976-08-12 1979-07-10 E M I Limited X-ray tube arrangements
US4158142A (en) * 1977-03-17 1979-06-12 Haimson Research Corporation Method and apparatus incorporating no moving parts, for producing and selectively directing x-rays to different points on an object
US4323779A (en) * 1977-06-03 1982-04-06 Albert Richard David Scanning radiographic method
DE2730889A1 (de) * 1977-07-08 1979-01-18 Strahlen Umweltforsch Gmbh Einrichtung zur ortsaufloesenden materialuntersuchung einer probe
US4352021A (en) * 1980-01-07 1982-09-28 The Regents Of The University Of California X-Ray transmission scanning system and method and electron beam X-ray scan tube for use therewith
DE3222514A1 (de) * 1982-06-16 1984-03-22 Feinfocus Röntgensysteme GmbH, 3050 Wunstorf Verfahren und vorrichtung zur erzeugung von roentgenstrahlung fuer stereoaufnahmen, tomografien und tomosynthesen
DE3222515A1 (de) * 1982-06-16 1984-03-22 Feinfocus Röntgensysteme GmbH, 3050 Wunstorf Feinfokus-roentgenroehre
EP0168776A3 (de) * 1984-07-19 1988-03-30 Scanray A/S Röntgenröhre
EP0168776A2 (de) * 1984-07-19 1986-01-22 Scanray A/S Röntgenröhre
EP0173047A2 (de) * 1984-08-27 1986-03-05 Scanray A/S Röntgenröhre
EP0173047A3 (de) * 1984-08-27 1988-03-16 Scanray A/S Röntgenröhre
US4631742A (en) * 1985-02-25 1986-12-23 General Electric Company Electronic control of rotating anode microfocus x-ray tubes for anode life extension
US5200985A (en) * 1992-01-06 1993-04-06 Picker International, Inc. X-ray tube with capacitively coupled filament drive
US5241577A (en) * 1992-01-06 1993-08-31 Picker International, Inc. X-ray tube with bearing slip ring
US5274690A (en) * 1992-01-06 1993-12-28 Picker International, Inc. Rotating housing and anode/stationary cathode x-ray tube with magnetic susceptor for holding the cathode stationary
US5291538A (en) * 1992-01-06 1994-03-01 Picker International. Inc. X-ray tube with ferrite core filament transformer
US20050163281A1 (en) * 2002-05-31 2005-07-28 Hans Negle X-ray tube
US7123688B2 (en) * 2002-05-31 2006-10-17 Koninklijke Philips Electronics, N.V. X-ray tube
WO2007066243A3 (en) * 2005-12-08 2008-01-03 Koninkl Philips Electronics Nv Systems and methods for scanning and data acquisition in computed tomography (ct) applications
US20090161819A1 (en) * 2005-12-08 2009-06-25 Koninklijke Philips Electronics N.V. Systems and methods for scanning and data acquisition in computed tomography (ct) applications
US7782999B2 (en) 2005-12-08 2010-08-24 Koninklijke Philips Electronics N.V. Systems and methods for scanning and data acquisition in computed tomography (CT) applications
US20100142681A1 (en) * 2007-05-03 2010-06-10 Lars Lantto Arrangement for generation of x-ray radiation with a large real focus and a virtual focus adjusted according to requirements

Also Published As

Publication number Publication date
DE2364142A1 (de) 1974-07-04
JPS4990086A (US20100154141A1-20100624-C00001.png) 1974-08-28
FR2212739B1 (US20100154141A1-20100624-C00001.png) 1976-04-30
FR2212739A1 (US20100154141A1-20100624-C00001.png) 1974-07-26
JPS5318318B2 (US20100154141A1-20100624-C00001.png) 1978-06-14
DE2364142B2 (de) 1978-05-11
GB1444109A (en) 1976-07-28
DE2364142C3 (de) 1982-04-22

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