A real time radiation dosimeter includes a first electrode and a second electrode, such as cathode and anode electrodes. The second electrode is based on carbon nanomaterials, such as carbon nanotubes bucky paper, carbon nanotubes forest and graphene film. The dosimeter is connected to an electrometer, able to apply a bias voltage between the electrodes and to measure the collected charge. The manufactured detectors display an excellent linear response to dose. The dosimeter with nanotubes forest is able to collect charge also to zero voltage, allowing in vivo applications. The use of nanomaterials allows a miniaturized version of dosimeters.