Jean-Pierre Bissonnette

At a Glance

• CT and PET Imaging during a course of Radical Radiotherapy to monitor treatment response and respond to changes in anatomic and metabolic changes to enhance the therapeutic ratio
• Clinical trial: bosting RT dose to metabolic active tumor subvolumes to improve local control.
• Developing simulation environment to change attitudes and behaviours around errors in radiation therapy.

Short Bio

Dr. Jean-Pierre Bissonnette is the Associate Head for Professional and Academic Affairs for the Department of Medical Physics at the Princess Margaret Cancer Centre, where he has been employed since 2003. Prior, he was the coordinator then interim Head of Physics at the Centre Hospitalier de l’Université de Montréal. He graduated from McGill University with a M.Sc., then obtained his Ph.D. from the University of Western Ontario in 1996.

Dr. Bissonnette has been active in several areas relevant to radiotherapy, including quality assurance and patient safety, high-precision radiotherapy for the brain and the lung, post-graduate education, and monitoring response of locally-advanced lung cancer to combined chemo-radiotherapy using CT, CBCT and PET images. Current research topics include dose reconstruction based on image-guidance images, image-based adaptation of therapy and exploring the use of statistical tools to rationalize and limit the cost of quality control work.

Research Synopsis

Lung cancer continues to be the leading cause of cancer-related deaths in Canada and worldwide. The current standard of care for locally advanced cancer involves a course radiation therapy, typically combined with chemotherapy, delivered daily over the course of five to seven weeks. Unfortunately, disease control and survival remain low for these patients. Delivery of higher doses of radiation to lung tumors might improve cure rates; unfortunately, proximity of several organs at risk, such as the spinal cord, the heart, and uninvolved lung tissue, limits the deliverable radiation dose. Recent advances in radiotherapy technology, more precise targeting and monitoring have potential to improve treatment outcomes. For example, image-guided radiation therapy (IGRT), has allowed the daily localization of the tumor immediately prior to treatment and thus eliminated the large and frequent localization errors, ensuring the tumor receives the prescribed radiation dose. IGRT has also shown that a majority of lung cancer patients encounter significant reductions in tumor volume by the end of therapy, raising several questions regarding biological activity and tumor oxygenation. My research group is currently pursuing frequent biological imaging during therapy, using positron emission tomography (PET). PET is a non-invasive volumetric imaging method utilizing radioactive decay physics of positron-emitting radioisotopes. Radioisotopes, such as 18F, are combined with various biologic compounds or molecules (e.g. deoxyglucose) to create a radiotracer that is injected intravenously and is taken up preferentially by tumor cells, where the radioisotope decays. High intensity areas in PET images may indicate areas of high tumor metabolism or of potential hypoxia; both may indicate areas of radioresistance. Given that dose escalation to the entire tumor and nodal volume has proven counterproductive, it may be logical to only escalate dose only to target subvolumes of suspected radioresistance with higher; indeed, these subvolumes have been correlated with sites of recurrences. We are currently leading a clinical trial that explores this idea, where identified subvolumes are treated to up to 40% of the conventional dose provided that toxicities to organs at risk are minimized.

Radiotherapy is a very powerful and effective approach to cure cancer, but has devastating implication when misused. In recent years, the media has reported radiation therapy incidents with severe detrimental effects on several hundreds of patients, including death, in France, Canada, the United Kingdom, and the United States. Even though incident rates in radiotherapy are low, the public and the World Health Organization has deemed that it was not low enough, and that there is clearly a need to perform radiotherapy in a safer way. In parallel, radiotherapy technologies have changed notably, making the planning and delivery of this modality much more efficient through the use of automation. To ensure that radiotherapy can be administered in a safe manner, the current quality paradigm involves frequent checks of treatment planning and delivery parameters. My work in this domain has been focussed on rationalizing the expenditure of resources towards quality and safety, pushing for standardization of quality checks and formulating tests that are directly linked with potential hazard, with the ultimate objective of eliminating such hazards. Quantifiable measures of quality also lend themselves well to standard quality analytical tools, including statistical process control charts, failure modes and effect analysis, and sampling theory.

Graduate Students

Dipal Patel