Abstract:
An apparatus provides in-situ radiation treating utilizing a miniature energy transducer to produce x-rays, wherein the energy transducer includes a Schottky cathode tip. More specifically, the energy transducer includes a transducer body, an anode provided at a first end of the transducer body, and a cathode provided at a second end of the transducer body opposite the anode. The energy transducer is coupled to an energy source by a flexible insertion device. The energy source provides electrical and/or light signals to the energy transducer via the flexible insertion device. Light transmitted from the energy source to the energy transducer by the flexible insertion device is focused on a Schottky cathode tip of the cathode by the optical fiber provided in the hollow core of the anode. The application of the light signal to the cathode tip results in heating of the tip and along with the electric field generated by the acceleration voltage it leads to electron Schottky emission and electron acceleration towards the anode. In another preferred embodiment, an electrical current, transmitted from the energy source to the energy transducer by the flexible insertion device, is applied to the Schottky cathode tip of the cathode, causing thermo-emission. The electrons generated due to this process are accelerated towards the anode across a voltage difference between the anode and the cathode.
Abstract:
This invention is directed to an x-ray source comprising a housing, an elongated tubular probe, a target assembly, and a beam steering assembly. The housing encloses an electron beam source, and has elements for generating an electron beam along a beam path. The elongated tubular probe extends along a central axis from the housing about the beam path. The target assembly extends along the central axis and is adapted for coupling to the end of the probe distal form the housing. The target assembly includes a target element positioned along the beam path, wherein the target element is adapted to emit x-rays in a predetermined spectral range in response to incident electrons. The beam steering assembly includes a deflection element, a feedback network, and a deflection controller. The deflection element deflects the beam from a nominal axis to a selected surface region on the target element in response to a deflection control signal. The feedback network includes deflection sensing elements for sensing the deflection of the beam and elements for generating a feedback signal representative thereof. The deflection controller couples to the deflection element and to the feedback network and includes elements for generating a deflection control signal in response to the feedback signal.
Abstract:
The present invention is directed to an x-ray source for irradiating a volume in accordance with a predetermined dose distribution. The source comprises a housing, an elongated tubular probe, and a target assembly. The housing encloses an electron beam source and includes elements for generating an electron beam along a beam path. The tubular probe extends along a central axis from the housing about the beam path. The target assembly extends along the central axis and is adapted for coupling to the end of the probe distal from the housing. The target assembly includes a target element, a probe tip assembly, and a variable transmission shield. The target element is positioned in the beam path. The target element is adapted to emit x-rays in response to electrons incident thereon from the beam. The probe tip assembly and associated control electronics include elements for positioning the target element in the beam path, and is substantially x-ray transparent. The variable transmission shield is positioned on an outer surface of the probe tip assembly, and is adapted to control the position of the isodose surfaces of the x-rays emitted from the target and passing through the probe tip assembly.
Abstract:
The invention relates to multiple beam lasertrons. The n (n: integer greater than 1) electron beams of the lasertron are obtained from the same laser beam from which n secondary laser beams are extracted, by occultation, which are deflected respectively towards the n photocathodes of the lasertron.
Abstract:
A method suitable for preparing a specimen for inspection, the method comprising the steps of: irradiating a photocathode so that the photocathode emits electrons from a surface of the photocathode, wherein the emitted electrons each follow a trajectory, and the trajectories of the electrons are such that they can be extrapolated to intersect at a region within the photocathode, the region defining a virtual source, and wherein the photocathode comprises a rounded tip which has a radius of curvature; configuring the emitted electrons so that they form an electron beam; focusing the electron beam onto a specimen to form an image of the virtual source on the specimen. There is further provided a corresponding electron beam apparatus.
Abstract:
An X-ray tube has an anode and a photocathode inside a vacuum envelope and an electron multiplier is disposed between them. Such an electron multiplier may be a plurality of sequentially disposed dynodes or a microchannel plate. Because of the secondary electron emission from such an electron multiplier, a higher-power radiation is obtained without requiring a high optical power level to generate photoelectrons. The vacuum envelope may be of a rotary type with the anode and photocathode having annular regions.
Abstract:
A method of treating brain tumors in a patient, comprising the steps of: identifying and locating a brain tumor in vivo by affixing a stereotactic frame to the head of the patient, performing a computer tomographic (CT) scan of the skull of the patient to determine the location, size, and shape of the tumor with respect to the stereotactic frame, performing a biopsy by inserting an extraction tool along a path measured with respect to the frame to the tumor location, extracting a tissue from the location, removing the needle and the extracted tissue and analyzing the tissue; implanting at least a portion of an adjustable x-ray radiation source in the patient proximate the tumor, the adjustable radiation source including an electron beam source outside the head of the patient, and directing an electron beam produced by the source outside the head of the patient along the path to the location; and controlling the source to generate an x-ray radiation pattern characterized by a spatial and temporal distribution, to selectively irradiate the tumor.
Abstract:
This invention is directed to an x-ray source comprising a power supply, a flexible fiber optic cable assembly, a light source, and a target assembly. The power supply includes a first terminal and a second terminal, and elements for establishing an output voltage between the first terminal and the second terminal. The flexible fiber optical cable assembly has an originating end and a terminating end, and includes a fiber optical element extending from the originating end to the terminating end. The cable is adapted for transmitting light incident on the originating end to the terminating end. The light source includes elements for generating a beam of light at and directed to the originating end of the fiber optical cable assembly. The target assembly is affixed to the terminating end of the fiber optical cable assembly and is electrically coupled to the power supply by way of the first terminal and the second terminal. The target assembly includes elements for emitting x-rays in a predetermined spectral range, in response to light transmitted to the terminating end.
Abstract:
A charged particle control apparatus provides very high voltage particle beams. One or more photocell arrays provide bias voltages for beam accelerating stages. The arrays are made from a number of microfabricated photocells connected in series to produce a voltage output that is the sum of the voltages from the individual cells. Arrays of each stage are connected in series to produce a cumulative stage voltage that is applied to an accelerating electrode made part of the stage.These accelerating stages are disposed within a transparent vacuum chamber and are spaced from a charged particle source stage disposed near one end of the chamber. This charged particle source stage includes an emission source such as a photocathode. The photo arrays of the accelerating stages are connected in series to produce a potential that is applied to the particle source stage.Optical power illuminates the stages to generate desired voltage biases to the accelerating electrodes. A light source is used to excite the photocathode when this emission source is used. Electrons from the emission source are accelerated by the accelerating electrodes and are emitted from the chamber which is typically conjoined with other apparatus.By utilizing photocell arrays to generate beam current and accelerating biases, as well as a photocathode for providing a source of electrons, the apparatus of the invention is completely optically isolated thereby requiring no direct electrical connections to the apparatus even though multiple accelerating stages are used to facilitate the achievement of very high voltage particle beams.
Abstract:
A method suitable for preparing a specimen for inspection, the method comprising the steps of: irradiating a photocathode so that the photocathode emits electrons from a surface of the photocathode, wherein the emitted electrons each follow a trajectory, and the trajectories of the electrons are such that they can be extrapolated to intersect at a region within the photocathode, the region defining a virtual source, and wherein the photocathode comprises a rounded tip which has a radius of curvature; configuring the emitted electrons so that they form an electron beam; focusing the electron beam onto a specimen to form an image of the virtual source on the specimen. There is further provided a corresponding electron beam apparatus.