The development of advanced imaging and dosimetry for permanent breast seed implant radiation therapy

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An estimated 27,000 Canadian women will be diagnosed with breast cancer in 2020. The treatment, surgery followed by 3.5 to 7 weeks of daily radiation therapy (RT), presents a significant burden to both our health care system and our patients. In fact, patients in remote communities may not complete their RT due to challenges in undertaking treatment far from home. Permanent breast seed implant (PBSI) is a novel, effective, breast RT that is undertaken in a single day, thereby significantly reducing the healthcare burden. My research program is focused on developing novel imaging and dosimetry tools and techniques to help enable PBSI across Canada. PBSI is administered by implanting radioactive seeds into the breast under two-dimensional ultrasound (2DUS) imaging guidance. While effective, PBSI is technically challenging and my research group has pioneered the development of technology and dose analysis tools to increase the precision and robustness of PBSI. We were the first to quantify the uncertainty in implant delivery and to discover that US clarity impacts implant accuracy. We have developed methodologies for accurately recording skin dose (a risk for treatment toxicity) and target doses post-operatively. In collaboration with Robarts Imaging we have developed a non-clinical prototype 3DUS scanner for PBSI. Here we build on this work to address primary bottlenecks in PBSI imaging, precision, individualized targeting, and quantitative post-implant dosimetry. The aims of this proposal are: Aim 1: 3DUS based PBSI: Long-term: To develop a fully 3DUS-based PBSI technique. Five-year: To develop and verify 3DUS technology for PBSI target delineation and implant guidance, thereby enabling improved treatment accuracy over existing protocols. Aim 2: Individualized targeting: Long-term: To develop methodology for personalized, precision, PBSI. Five-year: To model uncertainties in implant delivery and establish individualized margins for PBSI targeting, thereby enabling high precision, individualized targeting of PBSI treatments. Aim 3: Accurate post-implant dosimetry: Long-term: To develop quantitative dosimetry systems for accurate dose-outcome analysis. Five-year: To model the dosimetric impacts of seed movement, skin delineation, and breast shielding on skin dose, and to experimentally determine the impact of breast position on treatment dose. The result will be improved accuracy of post-implant dose analysis over current methodologies.  This work will establish a technical framework to enable precise, image-guided, individualized, adaptive PBSI and ultimately support my long-term research goal to ensure the availability of single day breast cancer radiation treatment across Canada. My work will also positively impact Canada's future by training a diverse group of 5 HQP to be medical physics leaders in academia, hospitals, or industry. As a mentor for young women, my HQP training will help address the gender imbalance in our field.