US3333104A - Plural x-ray tube power supply having pulse means for controlling the conduction of said tubes - Google Patents

Plural x-ray tube power supply having pulse means for controlling the conduction of said tubes Download PDF

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Publication number
US3333104A
US3333104A US413718A US41371864A US3333104A US 3333104 A US3333104 A US 3333104A US 413718 A US413718 A US 413718A US 41371864 A US41371864 A US 41371864A US 3333104 A US3333104 A US 3333104A
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Prior art keywords
voltage
ray tube
tubes
ray
conduction
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US413718A
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English (en)
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Bougle Jean
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Compagnie Generale de Radiologie SA
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Compagnie Generale de Radiologie SA
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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
    • H05G1/70—Circuit arrangements for X-ray tubes with more than one anode; Circuit arrangements for apparatus comprising more than one X ray tube or more than one cathode

Definitions

  • At least two X-ray tubes are connected across a D-C supply for being operated sequentially and at different voltages if desired.
  • Each X-ray tube is between and in series with a pair of switching tubes. Voltage across each X-ray tube is compared with a reference voltage and the difference voltage is used in a closed loop to control the grid voltage and the voltage drop across the switching tubes to thereby maintain a predetermined voltage on the X-ray tubes.
  • the present invention relates to high voltage generators for X-ray tubes and is particularly concerned with a generator that is capable of supplying several X-ray tubes at different voltages simultaneously for enabling a rapid succession of radiographs or radiostereoscopic views to be taken at different angles through the subject of an X-ray examination.
  • a known method for overcoming these disadvantages is to supply each X-ray tube from an individual high voltage generator and to take the radiographs successively and alternately with small time intervals between them.
  • the radiographic films are contained in film changers capable of synchronously delivering film into the path of each beam at a high rate, twelve per second, for example. It is seen that with this method it is possible to obtain for each angle of incidence or beam direction, a series of radiographs, those corresponding with one direction being alternate in time with those of the other.
  • the scattered radiation from one beam does not get onto the film related to the other beam but the method requires use of two expensive high voltage generators.
  • conventional high voltage generators it has been difiicult to exceed taking more than twelve radiographs per second.
  • An object of the present invention is to provide a high voltage generator, preferably three phase, that allows supplying one, two, or more X-ray tubes for taking as many as two hundred radiographs per second in one or more directions and that has independent regulation of the high voltage on each of the tubes.
  • Another object of the invention is to control the X-ray 3,333,104 Patented July 25, 1967 tubes with tetrode switching tubes that determine the start and end of an X-ray exposure and assist in maintaining the high voltage as a predetermined constant value during an exposure.
  • FIGURE 1 is a diagram of the essential features of a high voltage power supply and control for X-ray tubes according to the invention
  • FIGURE 2 is a graph of the form and timing of the pulses delivered by the X-ray tubes shown in FIGURE 1;
  • FIGURE 3 is a graph showing the relationship between the voltage of the high voltage generator and the voltage on the X-ray tube over a conduction interval of the latter.
  • two X-ray tubes 21 and 22 are adapted for being supplied from a single D-C source of high voltage to permit taking a rapid sequence of radiographs from different incidences.
  • the DC is obtained by rectifying A-C from a three phase transformer 1 having star connected secondary windings 3 and 4 which are coupled with primary windings 2 and 2.
  • the primary windings 2, 2' are respectively in star and delta to produce a phase shift in their secondary voltages or twelve pulses per cycle, which facilitates rectifying and filtering as is well-known.
  • the positive, or upper group in FIGURE 1 comprises diodes numbers 5 to 10.
  • the negative, or lower group is numbered 11 to 16.
  • the diodes in each group are fed in parallel from their secondary windings and each group is in series with the other.
  • the total D-C voltage appearing between positive line 41 and negative line 42 is equal to twice the voltage between either line 41 or line 42 and the symmetry point 39.
  • line 41 may be kilovolts maximum above ground, and line 42, 80 kilovolts below ground thereby attaining kilovolts to be applied across the X-ray tubes 21 and 22.
  • a milliammeter 40 reads the current through the X-ray tubes. 3
  • the positive rectifier group has a damping resistor 17 in series with a capacitor 18 which resistor and capacitor are in parallel with a discharge resistor 43.
  • the negative group has series connected capacitor 19 and resistor 20 in parallel with resistor 44.
  • the capacitors just named function in a complex way to yield energy when the X- ray tube begins to conduct, to obtain a fast rise time, and to absorb energy at the end, to avoid overvoltage.
  • the invention may use any stable D-C source of high voltage from a single or polyphase supply.
  • the three phase supply described above is well-known as exemplified by Swiss Patent 204,063 dated July 17, 1939.
  • FIGURE 1 two X-ray tubes 21 and 22 are shown although additional tubes may be supplied from high voltage lines 41, 42 if one desires more sequences of X-ray pictures from different aspects. Since the circuitry associated with each X-ray tube is basically the same, the description will be focused on that of X-ray tube 21 first.
  • This tube has in series with it a pair of tetrode high voltage switching tubes 23 and 24 which are controllable to connect the X-ray tube to the D-C line to start an exposure and to disconnect the X-ray tube at the end of an exposure. Because of the symmetry of the system, each tetrode switches one-half of the total D-C voltage. In a commercial embodiment, about 800 volts negative bias 3 is applied to the control grid of each tetrode to cut it off at 80 kilovolts on the plate.
  • the high voltage switching tetrodes 23 and 24 are controlled by a loop circuit that includes a reference voltage generator 27 and a comparator 28.
  • the reference voltage generator 27 delivers rectangularly shaped voltage pulses to the input 50 of comparator 28.
  • the voltage applied to X-ray tube depends on the amplitude of these pulses and the duration of an exposure interval depends on the width of the pulses.
  • the reference voltage generator 27 which establishes the pulse height and width.
  • the comparator 28 has two symmetrical portions, one positive and one negative with respect to ground point 39'.
  • a voltage appears between points 48 and 48 on a voltage divider circuit comprising resistors 30, 31, 46, and 47. Part of this voltage appears across resistors 46 and 47 in opposite polarity with respect to ground point 39' and this constitutes another input to comparator 28.
  • the comparato'r has the properties of the well-known differential amplifier with two inputs, a reference voltage signal on.
  • the comparator 28 compares these two signals, that is, takes the difference between them, and this difference is impressed n the control grids of the tetrodes 23 and 24 through a pair of small high voltage isolating transformer 49 and 49' respectively.
  • Comparator chassis 28 also has built into it a high frequency oscillator, not shown, but which feeds a pair of detector amplifiers 29 and 32 through the transformers 48 and 49.
  • the oscillator output frequency may be about 2.5 megacycles or any frequency that is high compared to the time of the exposure intervals.
  • This high frequency is a carrier wave which is modulated by the error signal.
  • Each detector amplifier 29, 32 demodulates and produces D-C bias voltage from the modulated signal and this voltage is applied to the control grids of the tetrodes 23, 24.
  • the X-ray tube does not conduct and there is no error signal or modulation.
  • the voltage on the control grids of vthe tetrodes is then maximum negative and the tetrodes are blocked.
  • tetrode 23 Before and after an exposure, tetrode 23 has nearly unlimited resistance to maintain the potential at point 48 at zero. During exposure, the voltage drop between its cathode and anode is constantly variable to maintain the potential at 48 precisely at the desired positive value. The effect is the same at point 48 for tetrode 24, except for the sign.
  • the available voltage of the system must be greater than the voltage which is applied to the X-ray tube 21 if the tetrodes 23 and 24 are to regulate properly.
  • the line voltage to the transformer primaries 2, 2' must be high enough to account for the voltage drop in secondaries 3 and 4, in the diodes -16 in the filters and the DC lines.
  • the ripple of the D-C voltage appearing between lines 41 and 42 with respect to ground must not swing toward zero so much as to reduce the voltage on the X-ray tube below the desired total amount. This may be understood better by referring to FIGURE 3 which shows various voltages related to time. Above the zero axis or ground reference there is a twelve pulse ripple voltage wave 55 that represents the voltage on positive D-C line 41. Wave 56 is the counterpart for negative line 42.
  • the square wave voltage held across the X-ray tube by the tetrodes has its maximum positive and negative amplitudes marked 57 and 58. It may be seen, for example, that there is a difference be. tween the minimum amplitude of the ripple 55 and the X-ray tube voltage 57 and that the tetrodes must be able to regulate within the range of this difference. Then, according to the invention, the voltage between 57 and 58 that is applied to the X-ray tube 21, is always smooth and no ripple is imposed on it because of the variable impedance action of the controlled tetrodes.
  • Means for controlling the X-ray tube current are not shown because they are not partof the invention and are known. Suflice it to say that tube current is controlled by regulating the temperature and hence the emissivity of the X-ray tube cathode.
  • FIGURE 1 shows that tetrodes 25 and 26 in a companion circuit are controlled in the manner of tetrodes 23 and 24 described above. Again, there is a reference voltage generator 33, a comparator 34, resistors 36 and 37, and amplifiers 35 and 38.
  • the invention operates as follows: all tetrodes 2326 being blocked, voltage is applied to the primaries of high voltage transformer 1. This puts a direct voltage on lines 41, 42. The timer, not shown, then may initiate an expo'sure by exciting the reference voltage generator 27 through closed switch 45. Because of the fast response rate a voltage appears almost instantaneously'on the COII'C? spond X-ray tube 21. Any error signal produced in the comparator 28 immediately varies the bias on the tetrode control grids to maintain a constant voltage on X-ray tube 21. Each X-ray tube is associated with a rapid film changer or a recording camera, neither being shown, for recording radiographs or picture taken from an image intensifier tube.
  • the camera shutters may be 180 out of phase in a two X-ray tube system so that the aperture of one camera will be closed while the other is open.
  • the camera may be provided with commutator switches symbolized by 45 and 45' which may control their corresponding reference voltage generators in synchronism witheach other.
  • a sequence of pictures of difierent aspects of an organ may be run at very high recording speeds. If the cameras run at pictures per second one of the X-ray tubes produces X-ray pulses of 2 milliseconds, for example, a width represented by the distance a-b in FIGURE 2, corresponding with an X-ray pulse rate of 100 per second; thus the pulses are separated by 10 millisecond time intervals f-k.
  • the other X-ray tube also produces 2 millisecond X-ray pulses, as represented by the width c-d at the same rate but offset in relation to the first series of pulses by 5 milliseconds represented by the distances e-f.
  • the hatched zones H indicate the times during which the shutter of the corresponding camera is closed.
  • An X-ray systems comprising:
  • Searcy 32118 (i) a detector amplifier means associated with each tetrode and having input terminals for receiving the respective modulated signals and output terminals connected to supply a demodulated D-C signal to the control grid of each tetrode respectively, whereby to control the voltage on the tetrodes and hence the voltage on the X-ray tubes at values corresponding with the reference voltage generator output,
  • switch means in circuit with each reference voltage generator and adapted when opened to cause discontinuance of the reference voltage pulses, and when closed, to continue said pulses,

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  • X-Ray Techniques (AREA)
US413718A 1964-02-28 1964-11-25 Plural x-ray tube power supply having pulse means for controlling the conduction of said tubes Expired - Lifetime US3333104A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR965492A FR1395015A (fr) 1964-02-28 1964-02-28 Perfectionnements aux générateurs de haute tension pour appareils de radiologie

Publications (1)

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US3333104A true US3333104A (en) 1967-07-25

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US (1) US3333104A (fr)
ES (1) ES307728A1 (fr)
FR (1) FR1395015A (fr)
GB (1) GB1077742A (fr)
NL (1) NL6502463A (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3828194A (en) * 1972-05-12 1974-08-06 Siemens Ag X-ray diagnosing apparatus with a regulating device for the x-ray tube voltage
JPS49112170U (fr) * 1973-01-22 1974-09-25
JPS50159691A (fr) * 1974-06-13 1975-12-24
US4168436A (en) * 1976-11-15 1979-09-18 Tokyo Shibaura Electric Co., Ltd. Computed tomography
US4206357A (en) * 1978-01-20 1980-06-03 Siemens Aktiengesellschaft X-ray diagnostic generator
US4297638A (en) * 1978-09-15 1981-10-27 Lafrance Robert R X-ray system signal derivation circuits for heat unit indicators and/or calibration meters
US4453263A (en) * 1979-10-04 1984-06-05 Picker Corporation Constant potential H-V generator
US4777380A (en) * 1983-02-22 1988-10-11 Thomson-Csf Method of switching the electric supply between independent load circuits
US20090290683A1 (en) * 2006-08-31 2009-11-26 Koninklijke Philips Electronics N. V. Power supply for an x-ray generator system
US20110129067A1 (en) * 2009-11-30 2011-06-02 Kabushiki Kaisha Toshiba X-ray diagnostic apparatus and x-ray diagnostic method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2037767C3 (de) * 1970-07-30 1986-01-09 Siemens AG, 1000 Berlin und 8000 München Röntgendiagnostikapparat für kurze Belichtungszeiten mit Regelung der Röntgenröhrenspannung
DE3005182A1 (de) * 1980-02-12 1981-08-20 Siemens AG, 1000 Berlin und 8000 München Roentgendiagnostikgenerator mit stellmitteln fuer die roentgenroehrenspannung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB689799A (en) * 1950-07-22 1953-04-08 Gen Radiological Ltd Operation of x-ray tubes
US2838681A (en) * 1953-06-01 1958-06-10 Picker X Ray Corp X-ray method and apparatus
US2936413A (en) * 1956-02-27 1960-05-10 Radiation Inc Mdc-3a regulator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB689799A (en) * 1950-07-22 1953-04-08 Gen Radiological Ltd Operation of x-ray tubes
US2838681A (en) * 1953-06-01 1958-06-10 Picker X Ray Corp X-ray method and apparatus
US2936413A (en) * 1956-02-27 1960-05-10 Radiation Inc Mdc-3a regulator

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3828194A (en) * 1972-05-12 1974-08-06 Siemens Ag X-ray diagnosing apparatus with a regulating device for the x-ray tube voltage
JPS49112170U (fr) * 1973-01-22 1974-09-25
JPS5841640B2 (ja) * 1974-06-13 1983-09-13 株式会社東芝 Ｘ線装置
JPS50159691A (fr) * 1974-06-13 1975-12-24
US4168436A (en) * 1976-11-15 1979-09-18 Tokyo Shibaura Electric Co., Ltd. Computed tomography
US4206357A (en) * 1978-01-20 1980-06-03 Siemens Aktiengesellschaft X-ray diagnostic generator
US4297638A (en) * 1978-09-15 1981-10-27 Lafrance Robert R X-ray system signal derivation circuits for heat unit indicators and/or calibration meters
US4453263A (en) * 1979-10-04 1984-06-05 Picker Corporation Constant potential H-V generator
US4777380A (en) * 1983-02-22 1988-10-11 Thomson-Csf Method of switching the electric supply between independent load circuits
US20090290683A1 (en) * 2006-08-31 2009-11-26 Koninklijke Philips Electronics N. V. Power supply for an x-ray generator system
US7852986B2 (en) 2006-08-31 2010-12-14 Koninklijke Philips Electronics N.V. Power supply for an X-ray generator system
US20110129067A1 (en) * 2009-11-30 2011-06-02 Kabushiki Kaisha Toshiba X-ray diagnostic apparatus and x-ray diagnostic method
US8576987B2 (en) * 2009-11-30 2013-11-05 Kabushiki Kaisha Toshiba X-ray diagnostic apparatus and X-ray diagnostic method including switching an X-ray generator from an abnormal high voltage generator to a normal high voltage generator

Also Published As

Publication number Publication date
NL6502463A (fr) 1965-08-30
GB1077742A (en) 1967-08-02
ES307728A1 (es) 1965-05-01
FR1395015A (fr) 1965-04-09

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