Joel St Aubin


Faculty of Medicine & Dentistry - Oncology Dept


Area of Study / Keywords

medical physics radiotherapy


Dr. Joel St Aubin is currently appointed as Assistant Professor in the Department of Oncology in the Faculty of Medicine & Dentistry.


Stereotactic Radiotherapy
Highly conformal, high dose per fraction radiation treatments are convenient for the patient and provide an effective treatment option for many disease types and sites. Stereotactic treatments are delivered in one or more fractions, but typically less than five. Treatment techniques include stereotactic body radiotherapy (SBRT) for extra-cranial disease (such as lung, liver, spine etc.) and stereotactic radiosurgery (SRS) for intra-cranial. Dr. St. Aubin is the designated medical physicist for the Gamma Knife radiosurgery program at the University Hospital which will be used to deliver highly accurate and conformal treatments to benign and malignant tumors as well as certain functional disorders.

Medical linear accelerator design and simulation
Medical linear accelerators are the most common technology for the generation of therapeutic x-rays for cancer treatment. By redesigning and optimizing linear accelerator waveguide structures and electron injectors, increased x-ray output, higher particle energies, and smaller focal spots can be achieved. Most current medical linear accelerator technology lies within the s-band of microwave frequencies, but advancements in c-band and x-band technologies would allow for shorter waveguides, and smaller systems overall. Analysis of any new waveguide and electron gun design in external magnetic fields is critical for MRI-guided radiotherapy systems such as the Linac-MR at the CCI.

Finite Element dose calculations
Radiation transport is governed by the linear Boltzmann transport equation (LBTE). Accurate dose calculations require a numerical solution to the LBTE either via stochastic methods (Monte Carlo) or deterministic methods (grid based Boltzmann solvers). The Finite Element Method (FEM) has proven extremely accurate in the solution of the LBTE. The Linac-MR project creates an additional requirement for radiation dose calculations since patients are treated in the strong magnetic fields of the MRI. Therefore any Linac-MR related dose calculation must include the action of the Lorentz force on the relativistic particles set in motion. Investigations into first order and second order (Least Squares Finite Element) LBTE with external magnetic fields are being pursued.