Gafchromic film as a fast visual indicator of radiation exposure of first responders.

Three types of Gafchromic films have been studied to investigate their potential for use as a visually readable dosemeter for persons acting as first responders in connection with radiological or nuclear emergencies. The two most sensitive film types show a pronounced variation in sensitivity by photon energy and are therefore not suitable for use in cases of unknown exposures. The third film type tested (RTQA2), which is intended for quality control in radiation therapy has a sensitivity that is independent of the radiation quality, and is therefore considered as the most optimal for visual reading in situ. Tests carried out on a group of 10 human observers showed that absorbed doses down to 40 mGy can be detected by the eye. Read by a portable densitometer, qualitative absorbed dose estimates down to 9 mGy can be achieved. The colour change is obtained instantaneously, giving first responders immediate information about the presence of beta-, gamma- and X-ray radiation.