The goal in cancer radiotherapy is to maximize tumor-kill while limiting toxic effects on nearby healthy anatomies. This is attempted via spatial localization of radiation dose; temporal dispersion of radiation dose; and judicious selection of a radiation modality. The spatial component involves prescribing a high dose to the tumor and putting upper limits on the dose delivered to the healthy anatomies. The radiation intensity profile is then optimized to meet this treatment protocol as closely as possible. The temporal component involves breaking the total planned dose into several treatment sessions called fractions, administered over several weeks. This gives the healthy tissue some time to recover between sessions, as it possesses better damage-repair capabilities than the tumor. The challenge is to choose an optimal number of fractions and the corresponding dosing schedule. Finally, while different modalities such as photons or protons can administer radiation, none is universally dominant owing to their distinct physical and biological properties. The goal is to simultaneously select an optimal modality (or a combination of modalities) and a fractionation schedule for each modality. I will outline how mathematical methods rooted in linear, nonlinear, convex, robust, inverse, and dynamic optimization can provide insights into these clinical decision-making problems.
Archis Gate is a professor and associate chair in the Department of Industrial & Systems Engineering at the University of Washington in Seattle, where he also held the College of Engineering Endowed Professorship in Healthcare Operations Research for five years. He joined the University of Washington as an assistant professor in 2006 after receiving a PhD in Industrial and Operations Engineering from the University of Michigan in 2006, and an MS in Management Science and Engineering from Stanford in 2003. He completed his undergraduate education at the Indian Institute of Technology, Bombay, India, in 2001. Archis is a recipient of the NSF CAREER award, and of the award for Excellence in Teaching Operations Research from the Institute of Industrial Engineers. Archis has served on the editorial boards of several journals. He served as the General Chair of the INFORMS 2019 Annual Meeting, and as a Program Co-Chair of the 2021 IISE Annual Conference.