Chapter 4

Dynamic Optimization in Radiotherapy

Archis Ghate
Industrial and Systems Engineering, University of Washington, Seattle, Washington 98195, archis@uw.edu

Abstract
The goal in external beam radiotherapy for cancer is to maximize tumor damage while limiting toxic effects of radiation on nearby healthy anatomies. This is achieved through spatial localization and temporal dispersion of radiation dose. Once a radiation intensity profile that achieves the maximum possible spatial localization is designed at the beginning of a multiweek treatment course, the total planned dose is split into a series of predetermined equal-dosage fractions delivered daily so that healthy cells can recover between sessions. Thus, existing mathematical methods for treatment planning employ static-deterministic optimization techniques, and hence cannot adapt to a tumor's uncertain biological response over time. In this tutorial, we review a recently proposed stochastic control framework, where the ultimate objective is to design individualized treatment strategies that dynamically adapt to tumor response to deliver the right dose to the right location at the right time.

Keywords: intensity-modulated radiation therapy; stochastic control; approximate dynamic programming

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Citation information:

Ghate A. Dynamic optimization in radiotherapy. J. Geunes, ed. INFORMS TutORials in Operations Research, Vol. 8. INFORMS, Hanover, MD, pp. 60--74.