Wiktionary
film badge
n. A piece of photographic film worn on the torso to act as dosimeter in order to record radiation exposure to the wearer.
Usage examples of "film badge".
We issue each member of the crew with a dosimeter and periodically check a film badge for radiation dosage--which is invariably less than you'd get sitting on the beach on a moderately warm day.
On one side, high on her chest, a film badge was pinned, a dosimeter that everyone in the shelter had been instructed to wear.