From optimization of radiation dose distributions to optimal cancer treatments.

The history of optimization in radiation oncology is closely intertwined with the history ofPhysics in Medicine & Biology(PMB). Over the past four decades, many of the conceptual advances that transformed radiotherapy-from forward planning to inverse planning, from physical to biological optimization, and from treatment planning to treatment strategy optimization-were first reported in the pages of this journal. Looking back from the perspective of PMB's seventieth anniversary, one can trace a remarkably consistent intellectual trajectory: the progressive expansion of optimization from the design of radiation dose distributions to the optimization of entire cancer treatment pathways.