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Electron Linac Offers Safe, Affordable Production Method for Medical Isotopes (IN 10-001, IN 04-039, IN 05-107)

Argonne National Laboratory

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<em>Schematic of a dual beam ERL for isotope production</em>
Schematic of a dual beam ERL for isotope production

Technology Marketing Summary

Scientists at Argonne National Laboratory have devised a safe, affordable way to ensure a reliable U.S. supply of selected medical isotopes. The invention has the potential to revitalize the domestic production of critical medical diagnostic materials and make the production process affordable even for small regional hospitals.

The innovative technology combines two Argonne patents, a superconducting cage-like radio-frequency (RF) cavity and a dual electron linear accelerator, or linac, in an energy-recovery configuration. The technology’s affordability is expected to satisfy growing demand for technetrium-99m (Tc-99), a medical isotope already scarce worldwide due to operational problems at the four aging nuclear reactors that produce 90 percent of the world’s supply.

Description

Cyclotrons and linear accelerators (linacs) are primary producers of medical radioisotopes, vital diagnostic tools for nuclear medicine. When injected into the body, isotopes can detect cancers and diseases of the heart, bone and kidney. Isotope-production systems are complex, however, and require huge capital investment to build, are costly to operate, and need regular oversight. High-current proton accelerators, if operated continuously, can themselves become radioactive through their interaction with scattered high-energy protons.

Electron linacs produce radioisotopes by virtue of an isotope target that receives the electron beam exit window and photo converters. The system consists of a cathode, an RF electron gun focusing elements to match the electron beam with an accelerating structure that creates a beam transmitted through a vacuum window into a high-atomic-mass material to create X-rays. The rays then strike a target to create isotopes. As shown in the figure, the isotope linac is an energy-recovery linac (ERL) in which an electron beam from Linac 1 is transmitted through an isotope-producing target. The electron beam energy is collected in Linac 2 and the RF power is used to accelerate the electron beam in Linac 2. The electron beam in Linac 2 is also transmitted through the same target then collected in Linac 1 to accelerate the electron beam in Linac 1. The ERL provides improved efficiency with reduced power requirements and provides improved thermal management of an isotope target and an electron-to-X-ray converter. The cost of the isotope ERL can be reduced further by using another Argonne invention, the cage cavity. The cage cavity uses an array of tubes to form an RF cavity. The cage cavity replaces conventional superconducting cavities to make the accelerating structures of the two linacs.

Benefits

Estimated to cost between $500,000 and $2 million to build, the RF cavity and electron linac pairing is affordable even for small hospitals to purchase and operate. By comparison, a conventional superconducting electron linear accelerator proposed as a high-yield source of medical isotopes is estimated at $150 million.

Electron linacs are safer to operate because they use the stable isotope molybdenum-100 instead of uranium to produce Tc-99 and require none of the nuclear safeguards of uranium. Linacs can produce other medical isotopes as well, making them highly flexible.

Applications and Industries
  • Pharmaceuticals industry;
  • Healthcare industry; and
  • University research facilities.
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Date
Patent 7,760,054
Patent
7,760,054
Tubular RF cage field confinement cavity
An RF cavity is provided with a plurality of tubes that are formed into a tubular cage in a predefined shape to define the RF cavity. A selected number of tubes and a selected tube diameter are provided to form a confinement cage for the RF fields within the RF cavity defined by the tubes. The multiple, small metal tubes are selectively bent to form different cavity shapes and sizes as needed to accelerate the particles and function as a confinement cage for the RF fields within the RF cavity defined by the tubes. The cost to fabricate RF cavities using the tubular cage design is significantly lower than the cost of producing a solid cavity using conventional fabrication technology.
Argonne National Laboratory 07/20/2010
Issued
Patent 7,394,201
Patent
7,394,201
Field emission cathode gating for RF electron guns and planar focusing cathodes
A novel method of gating electron emission from field-emitter cathodes for radio frequency (RF) electrode guns and a novel cathode that provides a focused electron beam without the need for magnetic fields or a curved cathode surface are provided. The phase and strength of a predefined harmonic field, such as the 3rd harmonic field, are adjusted relative to a fundamental field to cause a field emission cathode to emit electrons at predefined times for the generation of high-brightness electron beams. The emission time is gated responsive to the combined harmonic and fundamental fields and the response of the FE cathode to the combined fields. A planar focusing cathode includes a selected dielectric material, such as a ceramic material, to provide an electron beam emission surface. Metal surfaces are provided both radially around and behind the dielectric material to shape the electric fields that accelerate and guide the beam from the cathode surface.
Argonne National Laboratory 07/01/2008
Issued
Patent 6,987,361
Patent
6,987,361
Field emission cathode gating for RF electron guns and planar focusing cathodes
A novel method of gating electron emission from field-emitter cathodes for radio frequency (RF) electrode guns and a novel cathode that provides a focused electron beam without the need for magnetic fields or a curved cathode surface are provided. The phase and strength of a predefined harmonic field, such as the 3rd harmonic field, are adjusted relative to a fundamental field to cause a field emission cathode to emit electrons at predefined times for the generation of high-brightness electron beams. The emission time is gated responsive to the combined harmonic and fundamental fields and the response of the FE cathode to the combined fields. A planar focusing cathode includes a selected dielectric material, such as a ceramic material, to provide an electron beam emission surface. Metal surfaces are provided both radially around and behind the dielectric material to shape the electric fields that accelerate and guide the beam from the cathode surface.
Argonne National Laboratory 01/17/2006
Issued
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
IN 10001, ANL IN 04039 and ANL IN 05107PrototypeAvailable02/26/201302/26/2013

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To: Elizabeth Jordan<partners@anl.gov>