A dosimeter (100) for radiation fields is described. The dosimeter includes a scintillator (1) a light pipe (2) having a first end in optical communication with the scintillator (1) and a light detector (6). The light pipe (2) may have a hollow core (3) with a light reflective material about the periphery of the hollow core (3). The dosimeter (100) may further include a light source (61) that generates light for use as a calibrating signal for a measurement signal and/or for use to check the light pipe (2).