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US-12621919-B2 - Short pulse X-ray generator

US12621919B2US 12621919 B2US12621919 B2US 12621919B2US-12621919-B2

Abstract

Systems and methods for generating X-rays. The systems comprise: a voltage generator configured to generate a waveform comprising a plurality of pulses; a plurality of X-ray tubes that are each configured to emit pulses of X-rays responsive to the waveform; and a plurality of connectors that are each configured to be coupled to the voltage generator and communicate the waveform from the voltage generator to the X-ray tube. A dose and/or voltage of the pulses of X-rays is/are tunable in the field by adjusting at least one of (i) a line impedance of the system via an interchange of a first connector with another second connector of the plurality of connectors and (ii) a load impedance of the system via an interchange of a first X-ray tube with another second X-ray tube of the plurality of X-ray tubes.

Inventors

  • Norman Link
  • Glenn James
  • Yoko Kawai Parker
  • Alannah Myers
  • Chris Ferguson

Assignees

  • Fisica, Inc.

Dates

Publication Date
20260505
Application Date
20240821

Claims (20)

  1. 1 . A system, comprising: a voltage generator configured to create a waveform comprising a plurality of pulses; a plurality of X-ray tubes that are each configured to emit pulses of X-rays responsive to the waveform; and a plurality of connectors that are each configured to be coupled to the voltage generator and communicate the waveform from the voltage generator to the X-ray tube; wherein the dose or voltage of the pulses of X-rays is tunable in the field by adjusting at least one of (i) a line impedance of the system via an interchange of a first connector with another second connector of the plurality of connectors and (ii) a load impedance of the system via an interchange of a first X-ray tube with a second X-ray tube of the plurality of X-ray tubes.
  2. 2 . The system according to claim 1 , wherein the first X-ray tube and the second X-ray tube have different anode diameters, different anode distal ends shapes, different anode taper angles, different anode tapered shapes, different anode lengths, different anode materials, different total number of cathodes, different cathode shapes, different cathode sizes, different cathode inner ring shapes, different cathode thicknesses, different anode-cathode gaps, or different cathode-anode angles.
  3. 3 . The system according to claim 1 , wherein each of the plurality of X-ray tubes comprises at least one cathode and an elongate anode located adjacent to at least one cathode.
  4. 4 . The system according to claim 3 , wherein the at least one cold cathode has a ring shape with a center aperture through which a distal end of the elongate anode is proximal.
  5. 5 . The system according to claim 3 , wherein the elongate anode has a tapered distal end that is at least partially encompassed by the at least one cathode.
  6. 6 . The system according to claim 3 , wherein the at least one of the plurality of X-ray tubes comprises a plurality of cathodes that are equally or unequally spaced apart relative to a tip of the elongate anode and a point on the elongate anode where an optional tapered distal end begins.
  7. 7 . The system according to claim 3 , wherein at least one cathode has a cone-like shape with a smallest diameter located closest to the elongate anode.
  8. 8 . The system according to claim 7 , wherein a center axis of the at least one cathode is aligned with a center axis of the elongate anode, and the at least one cathode being disposed in front of a planar or flat end face of the elongate anode.
  9. 9 . The system according to claim 3 , wherein at least one cathode comprises: a first portion having a cone-like shape with a smallest diameter located closest to the elongate anode; and a second portion coupled to the first portion and having a cone-like shape with a largest diameter located closest to the elongate anode.
  10. 10 . The system according to claim 3 , wherein the elongate anode comprises a distal end with a concave or convex end face.
  11. 11 . The system according to claim 1 , wherein the plurality of pulses are equal to or less than five nanoseconds in length.
  12. 12 . The system according to claim 1 , wherein the voltage generator comprises a modular design in which a plurality of voltage generator modules may be added to the system through a use of a plurality of connectors to increase the voltage of the pulses or removed from the system to decrease the voltage of the pulses.
  13. 13 . The system according to claim 1 , wherein each connector of the plurality of connectors comprises: a proximal end member sized and shaped to facilitate an electrical connection between the voltage generator and the connector; a distal end member configured to provide a particular value for the line impedance and prevent formation of an electrical arc between the connector and an anode of an X-ray tube or the plurality of X-ray tubes that is in use; and an elongate conductive member extending through both the proximal and distal end members and providing a path for the waveform to travel from the voltage generator to the anode.
  14. 14 . The system according to claim 12 , wherein the elongate conductive member has a varying diameter with a first portion having a smaller diameter being disposed in the proximal end member of the connector and a second portion having a larger diameter being partially disposed in the distal end member of the connector.
  15. 15 . The system according to claim 13 , wherein the proximal end member of the connector comprises an internal conductive material encompassing the first portion of the elongate conductive member.
  16. 16 . The system according to claim 13 , wherein the connector further comprises an electrically resistive material encompassing the second portion that is disposed in the distal end member of the connector.
  17. 17 . The system according to claim 15 , wherein the electrical resistive material comprises silicone.
  18. 18 . The system according to claim 13 , wherein the distal end member of the connector comprises an external shaped surface that faces the X-ray tube, and is sized and shaped to provide a minimized distance between the connector and the X-ray tube and prevent an electrical arc from being formed between the connector and the X-ray tube.
  19. 19 . The system according to claim 17 , wherein the minimized distance is a variable distance that is largest at an outer edge of the external shaped surface and smallest at a center of the external shaped surface.
  20. 20 . A method for operating a system to generate X-rays in the field, comprising: generating a waveform comprising a plurality of pulses by a voltage generator; communicating the waveform to an X-ray tube via a connector having a first impedance; responsive to the waveform, emitting pulses of X-rays from the X-ray tube having a second impedance; and tuning a dose and/or a voltage of X-rays by adjusting the first or second impedances via the connector with another connector or an interchange of the X-ray tube with another X-ray tube.

Description

BACKGROUND Description of the Related Art With X-ray imaging, there is often a trade-off where one either needs higher amounts of penetration using a high energy X-rays, or better contrast which requires more X-ray dose during the same mission. These two goals have traditionally required separate sources. SUMMARY The present disclosure concerns implementing systems and methods for generating X-rays. The systems comprise: a voltage source generator configured to generate a waveform comprising a plurality of pulses; a plurality of X-ray tubes that are each configured to emit pulses of X-rays responsive to the applied voltage waveform; and at least one connector that is configured to be coupled to the voltage generator and communicate the waveform from the voltage generator to the X-ray tube. The trade-off of a dose versus the X-ray voltage of the pulses is tunable in the field by adjusting the load impedance of the system via an interchange of a first X-ray tube with another second X-ray tube of the plurality of X-ray tubes. The methods comprise: generating a waveform comprising one or more pulses by a voltage generator; communicating the waveform to an X-ray tube via a connector having a first impedance; emitting pulses of X-rays from the X-ray tube having a second impedance, responsive to the waveform; and tuning a dose or a voltage of the pulses of X-rays by adjusting the first or second impedances via the connector with another connector or an interchange of the X-ray tube with another X-ray tube. BRIEF DESCRIPTION OF THE DRAWINGS The present solution will be described with reference to the following drawing figures, in which like numerals represent like items throughout the figures. FIG. 1 provides an illustration of a system implementing the present solution. FIG. 2 provides an illustration of a model of the system shown in FIG. 1 and simulation results. FIG. 3 provides a graph showing actual data taken from a 150 kV SXG pulser system. FIGS. 4A-4C (collectively referred to as “FIG. 4”) provide illustrations that are useful for understanding the part modularity and/or interchangeability of the system shown in FIG. 1. FIGS. 5A-11B provide illustrations of various architectures for the cold cathode X-ray tube are shown in FIGS. 1 and 4. FIG. 12 provides graphs that are useful for understanding an inverse correlation of anode-cathode voltage to power. FIG. 13 provides a flow diagram of an illustrative method for generating X-rays and/or operating a system to generate X-rays. FIG. 14 provides an illustration of a computer system. DETAILED DESCRIPTION With X-ray imaging, there is a tradeoff between the need for higher penetration using a higher energy X-rays, or better contrast which requires more X-ray dose during the same mission. Conventionally, these two goals require different sources. The present document concerns solutions in which one X-ray source can be used to achieve either goal. The present X-ray source is configured to: provide a more energy efficient generation of X-rays (which may allow for superior battery operation); work with shorter, more robust X-ray tubes that hold up to field use; have almost no high voltage components thus leading to cooler running and longer mean time to failure (MTTF). Conventional solutions use relatively long voltage pulses (on the order of 30+ ns) with limited operating range as determined by the fixed impedance of the driver, a load impedance that determines or fixes X-ray voltage and dose, and spiral wound generators which have a relatively limited voltage range. Standard practice is to match the load and supply impedances which optimizes the power or energy transfer to the load but fixes the output (X-ray) voltage. Spiral generators tend to run hot and need regular cooling off periods which increases the required time on target and poor battery life. If a spiral generator will not work, (usually due to a need for higher voltages), then it becomes necessary to use very dangerous radioisotopes such as iridium-192 (˜460 keV) and cobalt-60 (˜1.25 keV). By combining a relatively short voltage pulse (˜1 ns) and a cold cathode X-ray tube, it is possible to tune the resulting X-ray to either be higher voltage or higher dose. It should be noted that conventional pulses are 25 ns or 70 ns. This new and novel approach allows user selected tradeoffs for one voltage generator to be used on a variety of X-ray imaging missions. The present solution implements the following concept(s): (i) transmission line tuned dose and voltage; (ii) improved cold cathode X-ray tube; (iii) building block X-ray pulser, and/or (iv) an innovative, high voltage, short pulse, generator-to-tube interface. Each of these concepts (i)-(iv) will be discussed in detail below. However, with regard to concept (i), it should be noted, by sending a relatively short voltage pulse into a tuned transmission line, the user can trade off the resulting X-ray's voltage for dose. With regard to concept (ii), it sho