Session

Overview: The choice of physical quantity for dose reporting in radiotherapy is crucial: it must correlate with clinical outcomes, be easily communicated to support consistent practice, and be accurately calculated or measured. Traditionally, dose to water fulfilled this role, as radiation doses were derived from measurements in water. However, modern dose calculation methods—such as Monte Carlo algorithms, linear Boltzmann solvers, and convolution/superposition techniques—now allow different dose definitions, creating uncertainty. This session will review recent recommendations clarifying these definitions, explain their historical context, discuss remaining challenges, and address quality assurance requirements for the reported dose quantity.