An optical computed tomography system for comprehensive end-to-end verification of the delivered dose in phantoms is described. The optical computed tomography system includes a light source that emits light; a detector; and a light-collimating tank arranged between the light source and the detector. The light-collimating tank itself includes a transparent substrate having a recessed region formed therein; an incident light surface formed on the transparent substrate; and an exit light surface formed on the transparent substrate opposite the incident light surface and shaped to focus light toward a focal region located outside of the transparent substrate. In some configurations, the incident light surface is shaped to collimate light impinging on the incident light surface into parallel rays that pass through the tank towards the exit light surface.