A system includes acquisition of first electronic image data representing a
phantom located at a first position and irradiated by a first radiation
field emitted by a radiation emitter, acquisition of second electronic
image data representing the phantom located at a second position based at
least on a first light field emitted by a light emitter and irradiated by
a second radiation field emitted by the radiation emitter, generation of
third electronic image data by correcting the second electronic image data
based at least on the first electronic image data, and determination of a
deviation between the first light field and the second radiation field
based at least on the third electronic image data.
