Characterization of the Dosimetry System in Terms of Hp(3) for Eye-Lens Dose Assessment

This work presents the characterization of a thermoluminescence dosimetry system based on LiF:Mg,Cu,P (TLD-100H) detectors for the measurement of the personal dose equivalent, Hp(3), used in eye-lens monitoring. The study was carried out at the Laboratorio de Protec¸ ´ ao e Seguranc¸a Radiol ˜ ogica (LPSR) ´ of Instituto Superior Tecnico (IST) and the irradiations were carried out at the Laborat ´ orio de Metrologia ´ das Radiac¸oes Ionizantes (LMRI) of LPSR. A series of performance tests including linearity, repro- ˜ ducibility, energy dependence, and angular dependence were carried out as part of the type-testing of the detectors, in order to evaluate the system’s suitability for routine monitoring applications.

The results demonstrated a linear response within the 0.1-10 mSv range, with good reproducibility in the same range, which encompasses typical occupational exposure levels. The energy dependence test, performed with N80, N100, 137Cs, and 60Co radiation qualities, showed variations within acceptable values set in international standards [1].

Angular dependence was the most relevant evaluation, confirming reliable response between -60◦ and +60◦ , consistent with International Electrotechnical Commission (IEC) requirements [1] as well as ±90◦ , provided certain experimental conditions (Source to Detector Distance (SDD) ≥ 2.5m and shift of the phantom) are considered. The final expanded uncertainty for the system, considering all influencing factors, was 33.63% (k = 2). Overall, the TLD-100H dosimetry system proved fit for purpose, i.e. suitable for individual eye-lens dose assessment.