Provided herein are a wearable radiation detector and a method of controlling thereof, the detector including: the radiation collection unit operable to collect light and output a signal corresponding to the light collected; a memory; a display unit; a processor operable to receive the signal output by the radiation collection unit, to store a value in the memory corresponding to the signal output by the radiation collection unit, to output an output signal based at least on the signal corresponding to the light collected by the radiation collection unit and to control the display unit to display an indication corresponding to the output signal, wherein the determining includes continually calculating the maximum exposure level based on the light being received by the radiation collection unit.