Abstract: An optical scanner gives three dimensional dosimetric data by scanning, with at least one light beam, a translucent medium exhibiting optical properties which change upon receipt of radiant energy representing a dose distribution of the energy. At least one detector is employed to gather data indicative of changes in the optical properties of the medium after scanning from multiple directions to provide a representation of the optical properties in sections through the medium. Typical optical properties measured include optical density, light scattering, emitted light intensities, and combinations thereof.