Radiation detector
From Tardis Wiki, the free Doctor Who reference
A radiation detector was a device that was worn to alert the user to the presence of radiation. During the Thousand Year War, some of the soldiers wore them as Skaro had become irradiated through nuclear war. Harry Sullivan was able to identify the device on a dead soldier and noted such technology was out of place next to his gas mask. (DW: Genesis of the Daleks)
