Cyclotrons
Cyclotrons are circular particle accelerators that use a combination of a static magnetic field and a rapidly varying electric field to accelerate charged particles along a spiral outward path. They are particularly noted for their ability to provide continuous beams of charged particles, a feature that is highly advantageous for applications such as cancer treatment through radiation therapy and the production of medical isotopes.
The compact size of cyclotrons compared to linear accelerators makes them especially suitable for use in hospitals and research facilities where space is at a premium. Additionally, cyclotrons facilitate the production of neutrons and positrons for various types of oncological and neurological imaging, providing essential capabilities in both medical diagnostics and treatment.
Main Components
A cyclotron consists of two D-shaped electrodes called “dees”, placed inside a vacuum chamber within a constant magnetic field. The magnetic field forces charged particles into a circular path, while an alternating electric field, generated by an RF oscillator, accelerates them each time they cross the gap between the dees. An ion source at the center of the cyclotron produces the charged particles.
Principle
The cyclotron accelerates particles using the interaction between the static magnetic field and the alternating electric field. Charged particles, such as protons or deuterons, are injected into the center and follow a circular path due to the magnetic field.
Each time the particles cross the gap between the dees, the alternating electric field accelerates them, increasing their energy. As the particles gain energy, their spiralling radius grows, and they move outward until they reach the desired energy level and are extracted.
Advantages
Cyclotrons are compact and energy-efficient, making them well-suited for facilities with limited space, such as hospitals. They are capable of producing continuous, high-intensity beams, which is advantageous for applications requiring steady particle flow, like isotope production or radiation therapy. Cyclotrons also offer precise control over particle energy, which is critical for medical treatments and research.
Applications
Cyclotrons are widely used in medicine for producing radioisotopes like Fluorine-18, essential for PET scans, and for proton therapy in cancer treatment. In scientific research, they are used to accelerate particles for nuclear physics experiments and to study nuclear reactions. Additionally, cyclotrons are used in imaging technologies that rely on positron and neutron production for detailed oncological and neurological diagnostics.
Wikipedia Link
Articles
IAEA News: A. Peeva, “Cyclotrons – What are They and Where Can you Find Them”
Cyclotron Produced Radionuclides: Guidelines for Setting Up a Facility
Cyclotron Produced Radionuclides: Physical Characteristics and Production Methods
Medical-isotope cyclotron designs go full circle – CERN Courier
Podcasts/Videos
Selection of Papers
M. Dehnel et al. “Practical Considerations in the Design of a High Current Commercial H¯ Cyclotron”, APAC 2007, pp.625-627, Indore, India, 2007.
K.L. Erdman et al. “Compact Commercial 9 MeV Deuteron Cyclotron with Pulsed Beam”, 16th Int’l Conf. on Cyclotrons and their App’s, East Lansing, MI, USA, 2001.
M.P. Dehnel et al. “Measurements of Injected Beam Deflections at the Exit of a Cyclotron Inflector as a Function of Applied Field or Beam Energy Perturbations”, 15th Int’l Conf. on Cyclotrons and their App’s, 239-242, Caen, France, 1998.
B.F. Milton et al. “Design of an Axial Injection System for the Seattle MC50 Cyclotron”, 15th Int’l Conf. on Cyclotrons and their App’s, 638-641, Caen, France, 1998.
M.P. Dehnel et al. “Measurements of Beam Emittance, Accelerated RF Phase Band, and Centering in a 1 MeV Test Cyclotron”, 15th Int’l Conf. on Cyclotrons and their App’s, 236-238, Caen, France, 1998.
K.L. Erdman et al. “Initial Operation of the Sherbrooke Ebco 19 MeV Cyclotron”, 15th Int’l Conf. on Cyclotrons and their App’s, 327-330, Caen, France, 1998.
M.P. Dehnel et al. “The Experimental Characterization of a Compact H¯ Cyclotron’s Spiral Inflector”, Nucl. Instrum. & Meth. in Phys., Vol. 397, Iss. 2-3, 1997.
M.P. Dehnel. “The Development of an Injection System for a Compact H¯ Cyclotron, the Concomitant Measurement of Injected Beam Properties and the Experimental Characterization of the Spiral Inflector”, Doctoral Thesis, The University of British Columbia, Vancouver, 1995.
M.P. Dehnel et al. “The TR16/8, A Dual Particle Cyclotron for Clinical Isotope Production”, Proc. 3rd European Part. Acc. Conf., Vol. 2, pp. 1682-1684, Berlin, 1992.
B.F. Milton et al. “First Beam in a New Compact Intense 30 MeV H¯ Cyclotron for Isotope Production”, Proc. 2nd European Part. Acc. Conf., Vol. 2, pp. 1812-1814, Nice, 1990.
Planche, R.A. Baartman, H.W. Koay, Y.N. Rao, L. Zhang, “Intensity limit in compact H- and H+2 cyclotrons”
Stammbach, S. Adam, A. Mezger, P.A. Schmelzbach, P. Sigg, “Cyclotron Performance and New Developments”, Proceedings of EPAC 2002, Paris, France.
R.E. Laxdal, A. Altman, T. Kuo, T. Kadantsev, “Beam Measurements on a Small Commercial Cyclotron”, Proceedings of EPAC 1994, London, England.
S.M. Qaim, “Use of Cyclotrons in Medicine”, Radiation Physics and Chemistry”, Volume 71, Issues 3-4, October-November 2004, Pages 917-926.
J.S.Chai et al, “Development of Medical Cyclotrons in KIRAMS”.
Cyclotron Manufacturers
Radioisotope Production
Therapy
Cyclotron Users
Hospitals – Imaging & Radiotherapy
University of Alberta – Cross Cancer Institute
University of Saskatchewan – Fedoruk Centre
Hospitals – Therapy
Radio-Pharmaceutical Companies
Universities
University of Jyvaskyla – Accelerator Laboratory
McMaster University Cyclotron Facility
University of Bern – Laboratory for High Energy Physics
National Laboratories
National Superconducting Cyclotron Laboratory