Claire McCann

Ph.D. Candidate

B.A.Sc (2000), M.H.Sc (2002) University of Toronto

Thermal Therapy

Thermal therapy can be used to destroy solid tumours by heating them to temperatures ranging from 55°C to 90°C, inducing thermal coagulation and necrosis of the tumour.

Master’s Research

We have investigated the feasibility of interstitial microwave thermal therapy as a salvage treatment for prostate cancer patients who have local recurrence following failed Brachytherapy. Due to the electrically and thermally conductive nature of the brachytherapy seeds, potential existed for the seeds to redistribute the microwave energy, resulting in damage to surrounding critical structures or inadequate thermal dose to some prostate regions. To model this treatment, a 915 MHz helical antenna was inserted into a muscle-equivalent phantom with and without dummy brachytherapy seeds. SAR measurements were made and plane wave models based on Maxwell’s equations were used to characterize the electromagnetic scattering effects of the seeds. SAR measurements indicated only insignificant differences in the shape and size of the SAR patterns of the antenna in the no-seed and seed cases. The plane wave simulations demonstrated that scattering of the microwave energy by the seeds could be expected, resulting in hot spots at the seed edges. Lack of empirical evidence of microwave scattering suggests that the circularly polarized field of the helical antenna renders these effects too small to be detectable. The results suggest that interstitial microwave thermal therapy is a feasible salvage treatment following failed Brachytherapy, as the seeds do not compromise the localization of heating to the target volume.

PhD Research

We are currently investigating the ability to thermally coagulate a large tumour volume interstitially, with a single applicator, by magnetic induction. For patients not amenable to surgical resection and for those where X-ray radiotherapy is not curative, (for example patients with Stage III or IV non-small cell lung cancer or mesothelioma) subsequent treatment of such large tumours is often very difficult. Our goal is to induce coagulative necrosis in a large tumour using a minimally invasive technique.

Publications

Journal Papers

C. McCann, J.C. Kumaradas, M.R.Gertner, S.R.H. Davidson, A.M. Dolan, M.D. Sherar, Feasibility of Salvage Interstitial Microwave Thermal Therapy for Prostate Carcinoma Following Failed Brachytherapy: Studies in a Tissue Equivalent Phantom, Physics in Medicine and Biology 48(8): 1041-1052, 2003.

M.D. Sherar, J. Trachtenberg, S.R.H. Davidson, C. McCann, C.K.K. Yue, M.R. Gertner, Interstitial Microwave Thermal Therapy for Prostate Cancer, Journal of Endourology, 17(8): 617-625.

Other Refereed Contributions

C. McCann, Transperineal Insterstitial Microwave Therapy (TIMT) for Localized Carcinoma of the Prostate Following Failed Brachytherapy Seed Implantation: Phantom Studies, Twentieth Annual Meeting of the North American Hyperthermia Society, Reno, Nevada, April 20-24, 2002.

Contact

Princess Margaret Hospital, Room 8-324

610 University Avenue

Toronto, Ontario

CANADA M5G 2M9

Phone: (416) 946-4501 x5767

Fax: (416) 946-2086

e-mail: cmccann@uhnres.utoronto.ca

Last updated: October 1, 2003