Energy and Angular Dependence of Thermoluminescent Materials to Beta Monitoring*

The increasing use of (sealed and nonsealed) beta radiation sources in medicine, industry and research implies the necessity of a metrologically reliable dose measurement in workers exposed to this type of radiation. The value of dose limits to be determined for occupational exposure in beta radiation fields is the equivalent dose on 1 cm2 of the evaluated skin, independently from the radiation-exposed area. However, a new denomination is being internationally suggested for this value which would be denominated radiation weighted dose. Beta particles with energies of approximately 60 keV may reach a 0.07 mm-depth in the tissue. A detector for radiation beta monitoring must be able to evaluate beta radiation dose with energies higher than 60 keV. The determination of extremity doses usually is made by means of thermoluminescent detectors because of their small dimensions. For measuring the equivalent dose in the skin, the detector must be thin, in order to avoid a significant radiation attenuation . However, the response in the majority of thermoluminescent dosimeters depends on the radiation energy and the irradiation geometry. The present study objective was to analyze the energy and angular dependence of different thermoluminescent materials for an appropriate choice of the material to be employed in workers occupationally exposed to beta radiation.