Room: Stars at Night Ballroom 4
Purpose: In the event of a large-scale radiation incident, fast and reliable dose estimation is essential to identify individuals needing immediate care. Currently, many biodosimetry techniques are time consuming and require proper expertise to deploy. This study provides an update on the validation of an automated field-deployable in vivo electron paramagnetic resonance (EPR) instrument that can fill this need.
Methods: EPR is a technique, similar to nuclear magnetic resonance, where the presence of free radicals within tooth enamel are detected. Free radicals are formed when ionizing radiation converts carbonate impurities within enamel into radicals. Baseline measurements were carried out on upper central incisors of total body irradiation (TBI) and head and neck (H&N) radiotherapy patients prior to treatment. Additional measurements were taken between subsequent treatment fractions. The dose delivered to the patientâ€™s teeth was independently measured using optically stimulated luminescent dosimeters (OSLDs) and diodes to determine the relationship between delivered dose and EPR signal.
Results: 75 measurements were acquired on four TBI and six H&N patients over a period of 16 months. The measured data demonstrate a linear increase of EPR signal with respect to delivered dose over the range tested. A studentâ€™s t-test was used to test the goodness of the linear least squares-weighted fit derived from the data. The p-values was <0.00001, indicating statistically significant results assuming a significance level of 0.05. The standard error of inverse prediction (SEIP) for all measured data was 2.02 Gy. For the dose range most relevant for immediate triage (â‰¤ 7 Gy), the SEIP was 1.81 Gy.
Conclusion: EPR provides fast, in vivo measurements of absorbed dose in human subjects, with good correlation between the EPR signal and the delivered dose. EPR shows promise as an easily deployable and accurate method for triage of victims in the event of a radiological incident.
Funding Support, Disclosures, and Conflict of Interest: We acknowledge funding from the Biomedical Advanced Research and Development Authority (BARDA) within the U.S. Department of Health and Human Services, and the Pilot Project Program of the Dartmouth Physically Based Center for Medical Countermeasures Against Radiation, with NIH funding from the National Institute of Allergy and Infection Diseases (U19-AI091173).
Not Applicable / None Entered.