Miniaturized low power x-ray source

An x-ray source comprising:

• A. a power supply including drive means for establishing an output voltage having a peak value in the approximate range of 10 kV to 90 kV,
• wherein the amplitude of said output voltage is a predetermined function of time;
• B. beam generator means responsive to said output voltage for emitting electrons to generate an electron beam along a beam path, said beam being characterized by a current in the approximate range of 1 nA to 100 .mu.A,
• wherein the magnitude of said current is a predetermined function of time;
• C. a target assembly positioned in said beam path, said target including at least one x-ray emission element adapted to emit x-rays in a predetermined spectral range in response to incident electrons from said beam;
• and
• D. field distribution means for establishing an x-ray radiation pattern having a spatial distribution, said spatial distribution being at least in part external to said source,
• wherein said beam generator means includes a photocathode, an anode adapted to attract electrons emitted from said photocathode, and means responsive to said output voltage coupled across the photocathode and anode for establishing an accelerating electric field between said photocathode and said anode, and
• wherein said anode is positioned between said photocathode and said target, said anode including an aperture through which said electrons pass.

An x-ray source comprising:

• a power supply including drive means for establishing an output voltage having a peak value in the approximate range of 10 kV to 90 kV, wherein the amplitude of said output voltage is a predetermined function of time;
• beam generator means responsive to said output voltage for emitting electrons to generate an electron beam along a beam path, said beam being characterized by a current in the approximate range of 1 nA to 100 .mu.A, wherein the magnitude of said current is a predetermined function of time;
• a target assembly positioned in said beam path, said target including at least one x-ray emission element for emitting x-rays in a predetermined spectral range in response to incident electrons from said beam;
• and
• field distribution means for establishing an x-ray radiation pattern having a spatial distribution, said spatial distribution being at least in part external to said source,
• wherein said beam generator means includes a thermionic emitter, an anode and means responsive to said output voltage for establishing an accelerating electric field between said thermionic emitter and said anode, and
• wherein said thermionic emitter includes a thermionic cathode having a first terminal and a second terminal, and said drive means comprises:
• A. a voltage multiplier network having a control voltage terminal and having a high voltage terminal coupled to said first terminal of said thermionic emitter, said voltage multiplier network including first circuit means coupled between said control voltage terminal and said high voltage terminal and responsive to an applied control voltage at said control voltage terminal for establishing said output voltage at said high voltage terminal,
• B. a thermionic emitter heater network having a current control terminal and including second circuit means capacitively coupled to said current control terminal for driving an rf ohmic heating current through said thermionic cathode in response to a current control signal applied at said current control terminal.

An x-ray source comprising:

• A. a power supply including drive means for establishing an output voltage having a peak value in the approximate range of 10 kV to 90 kV,
• wherein the amplitude of said output voltage is a predetermined function of time;
• B. beam generator means responsive to said output voltage for emitting electrons to generate an electron beam along a beam path, said beam being characterized by a current in the approximate range of 1 nA to 100 .mu.A,
• wherein the magnitude of said current is a predetermined function of time;
• C. a target assembly positioned in said beam path, said target including at least one x-ray emission element adapted to emit x-rays in a predetermined spectral range in response to incident electrons from said beam;
• and
• D. field distribution means for establishing an x-ray radiation pattern having a spatial distribution, said spatial distribution being at least in part external to said source,
• further comprising a closed housing, wherein said beam generator means and said target assembly are disposed within said housing, said housing having a window on one outer surface thereof, whereby said emitted x-rays are emitted through said window, and
• wherein said field distribution means comprises a shield assembly including means for restricting the x-rays emitted by said emission element, whereby said radiation pattern is restricted to have said spatial distribution.

An x-ray source comprising:

• A. a power supply including drive means for establishing an output voltage having a peak value in the approximate range of 10 kV to 90 kV,
• wherein the amplitude of said output voltage is a predetermined function of time;
• B. beam generator means responsive to said output voltage for emitting electrons to generate an electron beam along a beam path, said beam being characterized by a current in the approximate range of 1 nA to 100 .mu.A,
• wherein the magnitude of said current is a predetermined function of time;
• C. a target assembly positioned in said beam path, said target including at least one x-ray emission element adapted to emit x-rays in a predetermined spectral range in response to incident electrons from said beam;
• and
• D. field distribution means for establishing an x-ray radiation pattern having a spatial distribution, said spatial distribution being at least in part external to said source,
• further comprising a closed housing, wherein said beam generator means and said target assembly are disposed within said housing, said housing having a window on one outer surface thereof, whereby said emitted x-rays are emitted through said window, and
• further comprising an elongated cup-shaped sheath and associated skin entry port, said sheath and port having a biocompatible outer surface, and wherein at least the portion of said housing, including said window, is insertable into the interior of said sheath.

An x-ray source comprising:

• A. a power supply including drive means for establishing an output voltage having a peak value in the approximate range of 10 kV to 90 kV,
• wherein the amplitude of said output voltage is a predetermined function of time;
• B. beam generator means responsive to said output voltage for emitting electrons to generate an electron beam along a beam path, said beam being characterized by a current in the approximate range of 1 nA to 100 .mu.A,
• wherein the magnitude of said current is a predetermined function of time;
• C. a target assembly positioned in said beam path, said target including at least one x-ray emission element adapted to emit x-rays in a predetermined spectral range in response to incident electrons from said beam;
• and
• D. field distribution means for establishing an x-ray radiation pattern having a spatial distribution, said spatial distribution being at least in part external to said source,
• further comprising a closed housing, wherein said power supply, said beam generator means, and said target assembly are disposed within said housing, said housing having a window on one outer surface thereof, whereby said emitted x-rays are emitted through said window, and wherein at least a portion of said closed housing has a biocompatible outer surface.

An x-ray source comprising:

• A. a power supply including drive means for establishing an output voltage having a peak value in the approximate range of 10 kV to 90 kV,
• wherein the amplitude of said output voltage is a predetermined function of time;
• B. beam generator means responsive to said output voltage for emitting electrons to generate an electron beam along a beam path, said beam being characterized by a current in the approximate range of 1 nA to 100 .mu.A,
• wherein the magnitude of said current is a predetermined function of time;
• C. a target assembly positioned in said beam path, said target including at least one x-ray emission element adapted to emit x-rays in a predetermined spectral range in response to incident electrons from said beam;
• and
• D. field distribution means for establishing an x-ray radiation pattern having a spatial distribution, said spatial distribution being at least in part external to said source,
• wherein said target assembly includes a plurality of emission elements, and the x-ray emission characteristic of at least one of said emission elements is selectively controllable independent of each other of said emission elements.

A method of treating tumors in a patient, comprising the steps of:

• A. identifying and locating a tumor in vivo;
• B. implanting at least a portion of an adjustable x-ray radiation source in said patient proximate to said tumor;
• and
• C. controlling said source to generate an x-ray radiation pattern, characterized by a spatial and temporal distribution, to selectively irradiate said tumor.