EP0149337A2 - Apparat zur Erzeugung von Röntgenstrahlen und Verfahren zum Betrieb einer Röntgenröhre - Google Patents

Apparat zur Erzeugung von Röntgenstrahlen und Verfahren zum Betrieb einer Röntgenröhre Download PDF

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Publication number
EP0149337A2
EP0149337A2 EP84308697A EP84308697A EP0149337A2 EP 0149337 A2 EP0149337 A2 EP 0149337A2 EP 84308697 A EP84308697 A EP 84308697A EP 84308697 A EP84308697 A EP 84308697A EP 0149337 A2 EP0149337 A2 EP 0149337A2
Authority
EP
European Patent Office
Prior art keywords
filament
cathode
housing
transformer
anode
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.)
Withdrawn
Application number
EP84308697A
Other languages
English (en)
French (fr)
Other versions
EP0149337A3 (de
Inventor
Anthony Palermo
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 Nuclear Medicine Inc
Original Assignee
Picker International Inc
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 Picker International Inc filed Critical Picker International Inc
Publication of EP0149337A2 publication Critical patent/EP0149337A2/de
Publication of EP0149337A3 publication Critical patent/EP0149337A3/de
Withdrawn legal-status Critical Current

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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
    • H05G1/10—Power supply arrangements for feeding the X-ray tube
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/02—Constructional details
    • H05G1/04—Mounting the X-ray tube within a closed housing
    • H05G1/06—X-ray tube and at least part of the power supply apparatus being mounted within the same housing
    • 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

Definitions

  • the present invention relates to X-ray generating apparatus, more especially X-ray tube heads, and to methods of operating X-ray tubes.
  • Prior X-ray tube heads have traditionally included a metallic enclosure with an X-ray transmissive window through which X-rays are transmitted. Inside the housing is mounted an X-ray tube surrounded by an oil or gas insulating dielectric.
  • the X-ray tube itself includes an anode and cathode which are electrically biased or energized with large accelerating voltages which accelerate electrons from the cathode through an evacuated chamber striking the anode with enough kinetic energy to produce x-radiation.
  • high voltage signals are routed through inputs into an X-ray tube housing to the cathode and anode.
  • One or more cathode filaments for generating the electrons must also be energized.
  • a filament is electrically interconnected to the high voltage cathode input.
  • a low magnitude alternating or D.C. voltage, superimposed on this high voltage generates A.C. or D.C. current causing electrons to be thermionically emitted from the cathode.
  • This filament excitation signal is routed from outside the tube housing via high voltage cabling and connectors leading to a so-called X-ray voltage generator.
  • the generator includes a filament transformer whose primary winding is typically part of a high voltage power transformer.
  • the filament voltages generally are a few volts (5-10) and may be either A.C. or D.C.
  • the anode generally is energized with an identical three conductor high voltage cable.
  • the three conductors are usually shorted together in the high voltage transformer and X-ray tube housing causing the cable to act as a single conductor.
  • a second type of prior X-ray tube head is used for dental X-ray or other low power applications.
  • the tube is housed in a self-contained unit having a metallic enclosure and beam window.
  • Also enclosed in the metallic enclosure are both filament and high voltage transformers. These transformers receive low voltage signals from outside the X-ray tube head and generate high voltage signals for the anode and cathode as well as the cathode filament voltage. Since only low voltage is routed to these X-ray tube heads, the high voltage connectors mentioned above are not needed.
  • U.S. Patent No. 2,356,645 to Atlee et al. discloses an X-ray tube head of this second type design.
  • the required three conductor high voltage cables in addition to being expensive in cost of materials, make the high voltage connections of low flexibility which is sometimes inconvenient, for example, in computed tomography equipment, and other environments where repeated flexing of the cabling leading to the X-ray tube head is needed.
  • an X-ray generating apparatus comprising:
  • said tube includes at least two cathode filaments; a separate filament transformer is mounted in said housing for individually energizing each said filament; and low voltage alternating current inputs are routed through said housing for individually energizing each said transformer.
  • said tube includes at least two cathode filaments and said apparatus additionally includes a switch for selectively coupling an output from said filament transformer to a selected one of said filaments.
  • said switch is suitably responsive to the frequency at which said transformer energized when in use to determine which filament is coupled to the transformer output.
  • the invention further provides a method of operating an X-ray tube comprising the steps of electrically energising the tube anode and cathode mounted inside a tube housing, energizing a filament transformer positioned within the housing by coupling a relatively low voltage alternating current signal through said housing to a transformer input, and energizing said cathode filament to thermionically emit electrons by coupling a transformer output to said filament.
  • Figure 1 shows an X-ray tube head shown generally at 10.
  • the head includes a housing 11 enclosing an X-ray tube 12.
  • the tube housing 11 comprises two end portions 14, 16 separated by an intermediate portion 17.
  • the intermediate portion is coupled to the end portions by fluid tight seals to allow the X-ray tube housing 11 to be filled with an insulating fluid, typically oil, that surrounds and insulates the X-ray tube 12.
  • the end portions 14, 16 include electrical receptacles 18, 20 wh'ich transmit high electrical voltages to the X-ray tube 12.
  • the disclosed X-ray tube 12 includes a rotatable anode 22 and a fixed filament cathode 24 mounted within an evacuated glass envelope 26. Electrons emitted by a cathode filament accelerate to a target or focal spot 27 on the anode. Sudden deceleration of the electrons causes X-rays 28 to be emitted.
  • the anode 22 is rotated in a conventional manner to distribute the heating about the anode circumference. This rotation is imparted by a motor 29 whose stator windings are energized with signals routed through a low voltage input cable 31.
  • the intermediate portion 16 of the X-ray tube housing 11 includes an X-ray transmissive window 30 of thin aluminium ( 0.5 mm ) or high impact plastic material such as "Lexan".
  • the window 30 is located adjacent to the anode focal spot 27 so that a portion of the generally spherical X-rays 28 from the focal spot pass through the window. Once it exits the housing the radiation can be collimated using techniques known in the art.
  • X-ray tubes include multiple cathode filaments which can be independently energized to produce different size focal spots on the anode 22 for different X-ray diagnostic applications.
  • U.S. Patent 4,109,151 to Pleil discloses one such multiple focal spot X-ray tube. The disclosure of that patent is also incorporated herein by reference.
  • the Figure 7 circuit 50 discloses a prior art energization technique requiring three high voltage inputs for the cathode.
  • the tube housing 10 encloses an X-ray tube 12 having a cathode 24 which includes two energizable electron emitting filaments 54, 56.
  • the filaments share a common high voltage input 58 which in a typical X-ray tube carries a high magnitude direct current voltage on the order of 75,000 volts referenced to ground.
  • two additional high voltage inputs 60, 62 are needed. These inputs carry high voltage signals having a small magnitude A.C. or D.C. signal superimposed upon the high magnitude direct current signal carried by the input 58. Stated another way, the inputs 60, 62 also carry voltages on the order of 75,000 volts, plus or minus a small A.C. or D.C. signal on the order of 10 volts. This signal, when imposed across the filaments 54, 56 sets up a current which thermionically produces electron emissions. It should be appreciated that generally only one or the other of the two filaments 54, 56 will be energized at a given time so that only two of the three inputs 58, 60, 62 will be energized.
  • a high voltage positive input 64 of approximately 75,000 volts referenced to ground is coupled to the anode 22 so that the voltage separation between the cathode 24 and the anode 22 is on the order of 150,000 volts. This large voltage difference accelerates electrons from an energized one of the two filaments 54, 56, causing them to accelerate and strike the anode 22.
  • Both positive and negative high voltage inputs to the tube housing 11 are generated by a voltage generator 70.
  • This generator 70 includes circuitry (not shown) for generating a high voltage signal, includes two high voltage filament transformers 72, 73, and may or may not include rectifiers 74, 75 for generating the direct current signals needed for the three inputs 58, 60, 62.
  • Use of three inputs 58, 60, 62 to the housing 11 for the rube cathode 24 requires three pin contacts in the receptacle 18 to carry these high voltage signals to the housing.
  • the circuit 52 disclosed in Figure 8 is used to energize the two filaments 54, 56.
  • a high voltage generator 112 transmits two inputs 114, 116 to the housing 11.
  • a first input 114 carries a negative voltage having a magnitude of approximately 75,000 volts referenced to ground and the second input 116 carries a positive signal of the same magnitude.
  • the positive polarity signal energizes the tube anode 22 and is completely analagous to the anode signal transmitted in the prior art circuitry 50 shown in Figure 7.
  • the single negative input 114 replaces the three high voltage inputs 58, 60, 62 required to energize the prior art cathode 24.
  • Filament energization signals are generated by one of two filament transformers 120, 121 insulated for high voltage mounted inside the tube housing 11.
  • the secondary of each transformer 120, 121 is coupled to the high voltage input 114 at a junction 122.
  • a first bridge rectifier 124 rectifies an output from the first filament transformer 120 to impose a low level direct current signal across the filament 54 and a second bridge rectifier 125 rectifies the output from the second transformer 121.
  • the transformers 120, 121 are small, ferrite core, filament transformers insulated for 75,000 volts operating above 10 kilohertz with the secondary producing about 5 volts RMS at 5 amperes current.
  • a schematic of one such transformer showing a core 136, coil 138, primary leads 140a, b and secondary leads 142a, b is shown in Figure 6.
  • the connector 148 includes a female receptacle 150 positioned inside the cathode receptacle 18 bounded by a cavity- 152 in the housing 11.
  • the female receptacle 150 includes a single high voltage contact 154 connected to the two filament transformers 120, 121.
  • the receptacle 150 includes a flanged shoulder 156 which contacts an 0-ring seal 158 interposed between the housing 11 and the shoulder 156. This seal 158 prevents fluid within the cavity 152 from leaking outside the housing. This fluid helps isolate or insulate the connector 150 from the remaining portions of the X-ray tube housing 11.
  • a male connector 160 is inserted into the female receptacle 150 to route signals from the high voltage generator 112 to the cathode 24.
  • the male connector 160 is coupled to a high voltage cable 162 and held in place against the tube housing by a cable retainer 164. Once the male connector 160 is inserted into the female receptacle 150 this retainer 164 is tightened down by a threaded coupling 166 which mates with a threaded portion 168 of the receptacle 18.
  • the present invention employs single pin, high voltage contacts for both cathode and anode.
  • Use of the single pin and single high voltage signal allows the diameter of the male and female connectors 150, 160 to be reduced from the diameter required for the three pin prior art connector. It should be readily apparent that savings in cost of materials as well as cabling can be achieved by this aspect or feature of the invention.
  • the cathode portion 14 of the housing must be widened to accommodate the transformers 120, 121.
  • the transformers 120, 121 comprise two transformer cores 136 as well as two coils 138 which are mounted inside the cathode portion 14 in close proximity to the single high voltage contact 154.
  • FIG. 9 An alternate embodiment for energizing the filaments 54, 56 is illustrated in Figure 9.
  • single high voltage positive 1.70 and negative 172 inputs are employed so that the preferred connectors 150, 160 shown in Figure 4 can be utilized.
  • FIG. 8 rather than requiring three low voltage A.C. inputs 130, 132, 134 ( Figure 8) to the two filament transformer 120, 121 only two low voltage alternating current inputs 180, 182 to a single transformer 184 are needed.
  • the inputs 180, 182 are coupled to a primary of the single core filament transformer 184 having a secondary output which is rectified by a bridge rectifier 186.
  • a frequency sensing electronic switch 188 also mounted inside the housing and interposed between the output from the rectifier 186 and the cathode filaments 54, 56 determines which filament will be energized. This frequency sensing switch determines the input frequency of the signals entering the X-ray tube housing and depending upon the frequency closes one of two contacts 190, 192.
  • an energization of 10 kilohertz causes the contact 190 to be closed so that a first filament 54 is energized. If the driving frequency is 10.5 kilohertz, the switch 188 closes the second contact 192 energizing the second filament 56.
  • the advantage of this embodiment is that one filament transformer can be used instead of two.
  • the tube housing 11 need not be as large as the embodiment shown in Figures 1-3 since the frequency sensitive switch 188 requires very little space inside the housing 11.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)
EP84308697A 1984-01-16 1984-12-19 Apparat zur Erzeugung von Röntgenstrahlen und Verfahren zum Betrieb einer Röntgenröhre Withdrawn EP0149337A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US57088884A 1984-01-16 1984-01-16
US570888 1984-01-16

Publications (2)

Publication Number Publication Date
EP0149337A2 true EP0149337A2 (de) 1985-07-24
EP0149337A3 EP0149337A3 (de) 1986-06-04

Family

ID=24281453

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84308697A Withdrawn EP0149337A3 (de) 1984-01-16 1984-12-19 Apparat zur Erzeugung von Röntgenstrahlen und Verfahren zum Betrieb einer Röntgenröhre

Country Status (3)

Country Link
EP (1) EP0149337A3 (de)
JP (1) JPS60163399A (de)
CA (1) CA1261974A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2589028A1 (fr) * 1985-10-18 1987-04-24 Thomson Cgr Generateur de rayons x
WO1988003355A1 (fr) * 1986-10-30 1988-05-05 Thomson-Cgr Gmbh & Co Convertisseur de chaleur pour generateur de rayons x
WO1989005564A1 (fr) * 1987-12-04 1989-06-15 General Electric Cgr S.A. Appareil de radio-diagnostic
DE4201616A1 (de) * 1992-01-22 1993-07-29 Philips Patentverwaltung Roentgeneinrichtung
CN101975785A (zh) * 2010-12-03 2011-02-16 丹东奥龙射线仪器有限公司 便携式高频x射线探伤机
CN111669884A (zh) * 2019-03-06 2020-09-15 北京艾立科技有限公司 X射线组合机头

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3103591A (en) * 1963-09-10 Radiographic systems and method
US3110810A (en) * 1958-10-30 1963-11-12 Philips Corp Device for optionally switching on either of two filament cathodes of an X-ray tube
US4065689A (en) * 1974-11-29 1977-12-27 Picker Corporation Dual filament X-ray tube
US4109151A (en) * 1974-12-31 1978-08-22 Picker Corporation Dual filament x-ray tube used in production of fluoroscopic images
US4315154A (en) * 1979-11-08 1982-02-09 Siemens Corporation Multiple focus X-ray generator
DE3001118A1 (de) * 1980-01-14 1981-07-16 Siemens AG, 1000 Berlin und 8000 München Roentgendiagnostikgenerator fuer eine roentgenroehre mit mehreren brennflecken
US4317040A (en) * 1980-07-14 1982-02-23 Pennwalt Corporation Low ripple regulated X-ray tube power supply filament transformer

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2589028A1 (fr) * 1985-10-18 1987-04-24 Thomson Cgr Generateur de rayons x
WO1988003355A1 (fr) * 1986-10-30 1988-05-05 Thomson-Cgr Gmbh & Co Convertisseur de chaleur pour generateur de rayons x
WO1989005564A1 (fr) * 1987-12-04 1989-06-15 General Electric Cgr S.A. Appareil de radio-diagnostic
DE4201616A1 (de) * 1992-01-22 1993-07-29 Philips Patentverwaltung Roentgeneinrichtung
CN101975785A (zh) * 2010-12-03 2011-02-16 丹东奥龙射线仪器有限公司 便携式高频x射线探伤机
CN111669884A (zh) * 2019-03-06 2020-09-15 北京艾立科技有限公司 X射线组合机头

Also Published As

Publication number Publication date
EP0149337A3 (de) 1986-06-04
JPS60163399A (ja) 1985-08-26
CA1261974A (en) 1989-09-26

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Inventor name: PALERMO, ANTHONY