Stephen BreenMSc, PhD
Assistant Professor

Contact Info

T. (416) 946-4501 Ext. 5421
F. (416) 946-6566


Princess Margaret Cancer Centre
610 University Avenue
ON, M5G 2M9

Clinical Interests

Image-guided intensity-modulated radiotherapy of head and neck cancers, Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging in treatment planning, 4D imaging for treatment planning, Statistical process control in quality assurance, Quality management in radiation oncology


Please contact Faculty Member for more information


BEng, Engineering Physics, Technical University of Nova Scotia
MSc, University of Western Ontario
PhD, University of Western Ontario

Professional Memberships

Member, Canadian College of Physicists in Medicine


Assistant Professor, Department of Radiation Oncology, University of Toronto
Medical Physicist, Princess Margaret Hospital/University Health Network


Research Synopsis:

  • Online image guidance with conebeam CT for head and neck radiotherapy
  • Autosegmentation of CT images for radiotherapy treatment planning
  • Target volume delineation with PET-CT for radiotherapy treatment planning
  • Application of process control theory to quality control in radiotherapy

Publications and Awards

Recent Publications

Breen SL, Moseley DJ, Zhang BB, Sharpe MB. Statistical process control for IMRT dosimetric verification. Med Phys 35(10):4417-4425, 2008.

Zeng GG, Breen SL, Bayley A, White E, Keller H, Dawson L, Jaffray DA. A method to analyze the cord geometrical uncertainties during head and neck radiation therapy using cone beam CT. Radiother Oncol. 90(9):228-230, 2009.

Velec M, Waldron JN, O’Sullivan B, Bayley A, Cummings B,Kim J, Ringash J, Breen SL, Lockwood, G; Dawson LA. Cone Beam CT Assessment of Inter- and Intra-Fraction Setup Error of Two Head and Neck Cancer Thermoplastic Masks. Int Jour Radiat Oncol Biol Phys. 76(3): 949-955, 2009.

Coolens C, Breen SL, Purdie TG, Owrangi A, Publicover J, Bartolac S, Jaffray DA. Implementation and Characterization of a 320-slice Volumetric CT scanner for Simulation in Radiation Oncology. Med Phys 36(11): 5120-5127, 2009.

Breen SL and Zhang BB. Audit of an automated checklist for quality control of radiotherapy treatment plans. Radiother Oncol. 97(3):579-584, 2009.

Qazi A, Pekar V, Kim J, Breen SL, Jaffray DA. Auto-segmentation of normal and target structures in head and neck ct images: a feature-driven model-based approach. Med Phys. 38:6160-70 2011

Weersink R, Hope A, Cho J, Breen SL, Jaffray DA. Improving superficial target delineation in radiation therapy with endoscopic tracking and registration. Med Phys. 38:6458-68. 2011

Back to Top