Miniature x-ray tube with micro cathode

A method for producing a miniature x-ray tube on an elongated probe for use in delivering an x-ray dosage within a space in living tissue, comprising:

• depositing a layer of metal cathode filament material on a semiconductor substrate,
• etching away all but the desired filament from the deposited metal layer,
• etching away an area of the substrate supporting the filament such that the cathode filament hangs in free space supported by two filament ends which are secured to the substrate,
• providing an elongated flexible probe carrying three conductors, including first, second and third conductors,
• securing to a distal end of the probe the cathode and supporting substrate, and providing a vacuum enclosure so as to surround the cathode within a vacuum chamber defined by the vacuum enclosure, and the vacuum enclosure including an anode and target spaced from the cathode,
• connecting the first and second conductors of the probe to the cathode in a cathode heating circuit, and
• connecting the anode to the third conductor so that a high voltage potential can be placed between the cathode and the anode via the third conductor and one of said first and second conductors.

A method for producing a cathode for a miniature x-ray tube, comprising:

• depositing a layer of metal cathode filament material on a semiconductor substrate,
• etching away all but the desired filament from the deposited metal layer,
• etching away an area of the substrate supporting the filament such that the cathode filament hangs in free space supported by two filament ends which are secured to the substrate, and
• providing conductors on the semiconductor substrate in position for connection to a heater circuit on a probe to which the x-ray tube is to be connected.