EP3648136A1 - Tube à rayons x qui peut être commuté rapidement entre des tensions de crête kv - Google Patents

Tube à rayons x qui peut être commuté rapidement entre des tensions de crête kv Download PDF

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Publication number
EP3648136A1
EP3648136A1 EP18203239.1A EP18203239A EP3648136A1 EP 3648136 A1 EP3648136 A1 EP 3648136A1 EP 18203239 A EP18203239 A EP 18203239A EP 3648136 A1 EP3648136 A1 EP 3648136A1
Authority
EP
European Patent Office
Prior art keywords
anode
electron beam
hybrid
auxiliary
structure according
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Withdrawn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
EP18203239.1A
Other languages
German (de)
English (en)
Inventor
Rolf Karl Otto Behling
Bernhard Gleich
Axel Thran
Bernd Rudi David
Roland Proksa
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.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips 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 Koninklijke Philips NV filed Critical Koninklijke Philips NV
Priority to EP18203239.1A priority Critical patent/EP3648136A1/fr
Priority to PCT/EP2019/078130 priority patent/WO2020088939A1/fr
Publication of EP3648136A1 publication Critical patent/EP3648136A1/fr
Withdrawn legal-status Critical Current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
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/24—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof
    • H01J35/30—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof by deflection of the cathode ray
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/24—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof
    • H01J35/30—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof by deflection of the cathode ray
    • H01J35/305—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof by deflection of the cathode ray by using a rotating X-ray tube in conjunction therewith
    • 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
    • H05G1/58—Switching arrangements for changing-over from one mode of operation to another, e.g. from radioscopy to radiography, from radioscopy to irradiation or from one tube voltage to another
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/12—Cooling
    • H01J2235/1204—Cooling of the anode

Definitions

  • the main problem with a fast-kilovolt-peak implementation is that is very difficult to implement a fast dose modulation which is necessary for low dose scans. It is also difficult to use very low current protocols as this increases the time to discharge the high voltage capacitor and allows only for slow change in voltage.
  • Charging up, for example from 80 kV to 140 kV is merely a matter of generator power. In contrast, discharging from 140 kV down to 80 kV is a challenge unless extra expensive means like additional switchable resistors are used.
  • the discharge current is then the tube current through the X-ray tube. This provides a lower limit to the time for ramp-down.
  • a first aspect of the invention relates a hybrid anode structure for fast kVp switching for dual energy CT, the hybrid anode structure comprising:
  • an X-ray tube may be provided with an auxiliary anode in terms of a fixed anode and a main, e.g. rotating anode, and a magnetic or electric field, for example by z-deflection, for directing an electron beam to either anode, or distributing the current between the first and the second anode ,whereby the electron beam passes, at least partially, at the rim of the second anode, which serves as X-ray generator, and with variable and adjustable ratio also hits the first anode, which serves as an electron dump.
  • the present invention advantageously provides a minimal waste of energy as well as a minimal leakage radiation due to low impact electron beam energy.
  • a practical point to consider is also the effort in calibration needed. As any current setting needs its own calibration, it is desired to have only a few of them while all clinical protocols shall be feasible.
  • a grooved anode is a solution to this problem, but it imposes a high load to the rotating anode and cooling becomes an issue.
  • the auxiliary anode is for instance V-shaped and is located below and at the side of the second anode.
  • the thermal load of the second anode is substantially reduced.
  • the first target area of the auxiliary anode is configured to receive the first portion of the electron beam in the grazing incidence by means of an inclined plane, tilted to a beam axis of the first portion of the electron beam. This advantageously provides improved heat dissipation inside the anode structure.
  • the first target area of the auxiliary anode is configured to receive the first portion of the electron beam in the grazing incidence by means of a groove, at least one side wall of which is tilted to an beam axis of the first portion of the electron beam. This advantageously provides improved heat dissipation inside the anode structure.
  • the auxiliary anode comprises molybdenum or tungsten. This advantageously provides improved X-ray tube reliability.
  • the deflector is configured to spread first portion of an electron beam over the first target area of the auxiliary anode and configured to increase an irradiated surface of the first target area of the auxiliary anode.
  • the deflector comprises a single-stage or a multistage collector and/or the deflector is configured to spread the beam by an angled structure and/or the deflector is configured to use:
  • a first target is constructed in a shallow angle where most of the electrons get scattered off and a second electron target surface is provided at a distance with even higher surface area, essentially a "hohlraum" absorber, a black body or blackbody as an idealized physical body that absorbs all incident electromagnetic radiation.
  • a "hohlraum” - a non-specific German word for a "hollow space” or “cavity” - is a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity.
  • the density of the wires in the hohlraum is such that the almost all of the primary beam touches a small wire while the scattered electrons are likely to strike the surface of the hohlraum.
  • a second aspect of the invention relates an X-ray tube comprising the hybrid anode structure according to the first aspect or according to any implementation of the first aspect.
  • FIG. 1 shows a schematic diagram of a diagram of the ideal tube voltage versus time according to an embodiment of the invention.
  • High tube current usually produces high X-ray flux to the patient. This is mostly unwanted. Instead, the X-ray flux in the used beam should be rather independent of the high tube current.
  • the current consumed by the X-ray tube or in other words, the current over voltage, is the same at all times of the scan. This ensures that the high kVp and low kVp times as well as the transition times remain constant and therefore the average high kVp and low kVp spectra.
  • condition at the cathode - for instance to be defined by parameters like filament current, acceleration voltages, temperature, pressure, electric resistance, heat capacitance - are kept constant.
  • a part of the electron beam is dumped where it cannot produce image relevant X-rays.
  • this can be realized with a groove at the anode and a large-scale z-deflection unit, best a magnetic one.
  • the fixed anode is provided below and to the side of the rotating anode, as shown in Fig. 1 .
  • the - optionally dynamic - electric or magnetic field deflects the electron beam at least partially off the rotating anode.
  • the fixed anode needs to have a special shape to cope with the high power density of the electron beam.
  • the width of the V-shaped groove is more than the width of the electron beam, for example the width of the V-shaped groove more than 1 mm or more than 0.5 mm or more than 100 ⁇ m.
  • the length of the groove is at least the length of the electron beam i.e. about at least 1 cm or at least 5 mm or at least 1 mm.
  • the energy absorbing surface needs to be at least 30 times of the equivalent area as provided by rotation of the rotating anode.
  • the groove is for example achieved by making the groove at least 15 mm deep or at least 20 mm deep or at least 30 mm deep.
  • the depth of the groove of at least 15 mm is enough as due to the scattered electrons, both surfaces of the V-structure are about equally subjected to the beam power, i.e. the depth of the groove of at least 15 mm is larger than any characteristic electron scattering length of the decay of hot electron in the anode.
  • FIG. 2 shows a schematic diagram of a hybrid anode structure for fast fast-kilovolt-peak switching for dual energy CT according to an embodiment of the invention.
  • maintaining the highest tube current may be applied, a current which the tube can deliver and sustain at highest tube voltage, e.g. 140 kV). This is typically done by setting the temperature of the thermionic electron emitter accordingly.
  • bias voltages in the cathode are adjusted as well.
  • the maximal tube current discharges the generator capacitance in the fastest way possible.
  • the beam dump may be biased or charged in such a way the electrons hits with minimal power.
  • the absolute of its negative voltage should be only a little less than the absolute of the momentary cathode voltage. Electrons will be absorbed, but their impact energy will be minimal, as will be the heat generated
  • the beam dump is configured such that electron backscattering is minimal, for instance by using carbon-based materials, or by using a grazing impact of the electron beam towards the auxiliary anode.
  • the beam dump in terms of the auxiliary anode is configured to be fluid-cooled.
  • FIG. 3 a schematic diagram of a hybrid anode structure for fast kilo-volt-peak switching for dual energy CT according to an embodiment of the invention.
  • the beam dump is a current source. Actively steer the bias of the beam dump by the generator. This must be done according to the predicted discharge pattern and the dumped portion of the electron beam. Re-use the energy supplied in the generator.
  • the beam dump may be configured to be basically float, and discharged by passive load.
  • the beam dump may be coupled to a resistor and/or to a capacitor and/or to an inductor to be discharged by passive load.
  • the X-ray tube as shown in Fig. 4 comprises a hybrid anode structure, a house, an anode support shaft and a rotor body.
  • the rotor body may for instance comprise cooper.
  • the X-ray tube as shown in Fig. 4 comprises an anode disc which is rotating and a fixed anode.

Landscapes

  • X-Ray Techniques (AREA)
EP18203239.1A 2018-10-30 2018-10-30 Tube à rayons x qui peut être commuté rapidement entre des tensions de crête kv Withdrawn EP3648136A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP18203239.1A EP3648136A1 (fr) 2018-10-30 2018-10-30 Tube à rayons x qui peut être commuté rapidement entre des tensions de crête kv
PCT/EP2019/078130 WO2020088939A1 (fr) 2018-10-30 2019-10-17 Tube à rayons x pour commutation rapide de kilovolts en crête

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP18203239.1A EP3648136A1 (fr) 2018-10-30 2018-10-30 Tube à rayons x qui peut être commuté rapidement entre des tensions de crête kv

Publications (1)

Publication Number Publication Date
EP3648136A1 true EP3648136A1 (fr) 2020-05-06

Family

ID=64048698

Family Applications (1)

Application Number Title Priority Date Filing Date
EP18203239.1A Withdrawn EP3648136A1 (fr) 2018-10-30 2018-10-30 Tube à rayons x qui peut être commuté rapidement entre des tensions de crête kv

Country Status (2)

Country Link
EP (1) EP3648136A1 (fr)
WO (1) WO2020088939A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5423492A (en) * 1977-07-25 1979-02-22 Jeol Ltd X-ray generator
US20050163281A1 (en) 2002-05-31 2005-07-28 Hans Negle X-ray tube
US20100172475A1 (en) 2007-06-21 2010-07-08 Koninklijke Philips Electronics N.V. Fast dose modulation using z-deflection in a rotaring anode or rotaring frame tube
US20120269321A1 (en) * 2009-10-28 2012-10-25 Koninklijke Philips Electronics N.V. Switching of anode potential of an x-ray generating device
US20120326031A1 (en) 2011-05-02 2012-12-27 Uwe Wiedmann Method and device for applying dual energy imaging

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5423492A (en) * 1977-07-25 1979-02-22 Jeol Ltd X-ray generator
US20050163281A1 (en) 2002-05-31 2005-07-28 Hans Negle X-ray tube
US20100172475A1 (en) 2007-06-21 2010-07-08 Koninklijke Philips Electronics N.V. Fast dose modulation using z-deflection in a rotaring anode or rotaring frame tube
US20120269321A1 (en) * 2009-10-28 2012-10-25 Koninklijke Philips Electronics N.V. Switching of anode potential of an x-ray generating device
US20120326031A1 (en) 2011-05-02 2012-12-27 Uwe Wiedmann Method and device for applying dual energy imaging

Also Published As

Publication number Publication date
WO2020088939A1 (fr) 2020-05-07

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