An apparatus and method for measuring three-dimensional radiation dose distributions with high spatial and temporal resolution using a large-volume scintillator. The scintillator converts the radiation dose distribution into a visible light distribution. The visible light is transported to one or more photo-detectors, which measure the light intensity. The light signals are processed to correct for optical artifacts, and the three-dimensional light distribution is reconstructed. The reconstructed light distribution is post-processed to convert light amplitudes to measured radiation doses. The high temporal resolution of the detector makes it possible to observe the evolution of a dynamic dose distribution as it changes over time. Integral dose distributions can be measured by summing the dose over time.
