Radiation Dose Reconstruction Using Q-Band EPR Analysis of Mini-biopsy Dental Enamel Samples

This study focuses on recent advancements in biodosimetry using continuous wave (CW) Q-band electron paramagnetic resonance (EPR) spectroscopy and mini-biopsy samples from tooth enamel. When radiation is absorbed, the carbonate impurities in enamel (i.e., hydroxyapatite) are changed into •CO2- (carbon dioxide radical anions), which become trapped within the crystal lattice and remain stable for durations far exceeding human lifespans. This stability makes tooth enamel an ideal material for assessing radiation doses in both accident and retrospective scenarios. In contrast to traditional, more invasive CW X-band EPR (9.8 GHz) methods, the CW Q-band EPR technique allows for the non-invasive (or minimally invasive) collection of smaller enamel fragments. This enables faster, more comfortable sampling. Operating at approximately 34 GHz, CW Q-band EPR offers enhanced sensitivity and a significantly improved signal to noise ratio (S/N) compared to CW X-band EPR. This increased sensitivity is crucial for detecting lower radiation doses in smaller samples, making it particularly useful for accurately identifying high-risk individuals in radiation triage situations. For this study, mini biopsies weighing around 2 mg were extracted from teeth and analyzed at room temperature using CW Q-band EPR. Calibration curves were established using reference doses, allowing the precise calculation of doses from signal intensity. Radiation doses higher than 100 mSv were estimated with high precision and accuracy. The combination of CW Q-band EPR spectroscopy and mini-biopsy sampling of tooth enamel provides a rapid, reliable method for dose assessment in radiation triage scenarios. This advancement is essential for developing efficient biodosimetry techniques, enabling the timely identification and management of individuals exposed to ionizing radiation during radiation incidents. Additionally, this method proves invaluable for retrospective dose reconstruction in cases of chronic exposure applicable to individuals, groups, or entire populations.