Development of Compact, High-Current Cyclotrons for Medical Isotope Production
D. Winklehner (PI), J.M. Conrad (Co-PI)
Laboratory for Nuclear Science
Massachusetts Institute of Technology
This proposal aims to upgrade a record-current-producing H2+ ion source (MIST-1) to further improve on the award-winning HCHC cyclotron design, to develop special use cases for medical isotope production of this design, and to train the next generation of accelerator physicists with an emphasis on medical isotopes.
The HCHC is a new compact cyclotron design with a beam current x10 higher than on-market machines for isotope production. The original motivation for this R&D came from neutrino physics. However, it was soon realized that these high power, low-cost accelerators can be transformational for medical isotope production, because of the flexible design. Machines can be manufactured with output energies from 1.5 MeV/amu to 60 MeV/amu for any ion with q/m=1/2, including H2+ (as is used in neutrino physics),D+, He++, and even C6+.
This proposal will train a graduate student and two undergraduates who are members of the next generation of physicists pursuing breakthrough accelerator designs for isotope production. The first objective is to teach the students about the physics, hardware, and code for accelerator design through a project to upgrade the existing MIST-1 ion source (part of the HCHC injector). MIST-1 has been a successful training ground for past students at MIT and MIST-2 will be a cutting-edge device providing continuing hands-on hardware experience. The second objective is to develop the HCHC design and cost estimates for two case studies: production of 68Ge and 225Ac. The HCHC with the MIST-2 could produce 250 Ge/Ga generators for the PET imaging isotope 68Ga per week through irradiating liquid Ga targets by developing a beam-splitting plan to allow for use of multiple targets. An HCHC-accelerated D+ beam design could produce 225Ac, a valuable alpha-emitter for cancer therapy. This novel approach uses ~20 MeV neutrons resulting from D+ breakup in a thick beryllium target to flood a container of radium salts, generating 225Ac with no 227Ac contamination. However, beam losses on cyclotron-internal collimators must be well-understood for D+ beams due to activation-risks. This is another aim of this proposal.
Students will develop the MIST-2 ion source building on experience with the existing MIST-1 source. The MIST-2 will be commissioned using the existing test stand and then it will transferred to the HCHC-1.5 for measurement of the beam parameters at injection and turn 5 of the prototype. Results will be compared to the MIST-1 and to predictions from particle-in-cell simulations. These experiences will inform the isotope-production case studies that will use expansions of existing HCHC simulation code.
A defining feature of this work is that the HCHC development was university-initiated. As a result, this proposal is entirely university-centered, making this project ideal for the training of the next generation of scientists who will produce cutting-edge accelerators for isotope production. Along with training, this work demonstrating the application of the HCHC cyclotron will influence industry. Because of the low-cost and small footprint, the machines can be installed by consortia of hospitals and universities, benefiting society.
